阅读说明：本技术 交联聚烯烃系树脂发泡体及叠层体 (Crosslinked polyolefin resin foam and laminate ) 是由 松井梨绘 于 2019-09-27 设计创作，主要内容包括：本发明是一种交联聚烯烃系树脂发泡体,是将至少含有聚烯烃系树脂的聚烯烃系树脂组合物交联发泡而成的交联聚烯烃系树脂发泡体,其在厚度为0.3mm以上且小于1.0mm的情况下全光线透射率为45％以上,并且在厚度为1.0mm以上且5.0mm以下的情况下全光线透射率为30％以上。根据本发明,可以提供具有优异的光透射性的交联聚烯烃系树脂发泡体。(The present invention is a crosslinked polyolefin resin foam obtained by crosslinking and foaming a polyolefin resin composition containing at least a polyolefin resin, wherein the crosslinked polyolefin resin foam has a total light transmittance of 45% or more when the thickness is 0.3mm or more and less than 1.0mm, and has a total light transmittance of 30% or more when the thickness is 1.0mm or more and 5.0mm or less. According to the present invention, a crosslinked polyolefin resin foam having excellent light transmittance can be provided.)

1. A crosslinked polyolefin resin foam obtained by crosslinking and foaming a polyolefin resin composition containing a polyolefin resin,

the crosslinked polyolefin resin foam has a total light transmittance of 45% or more when the thickness is 0.3mm or more and less than 1.0mm, and a total light transmittance of 30% or more when the thickness is 1.0mm or more and 5.0mm or less.

2. The crosslinked polyolefin resin foam according to claim 1, wherein the content of the polyolefin resin is 65% by mass or more based on the total amount of the resin components contained in the polyolefin resin composition.

3. The crosslinked polyolefin resin foam according to claim 1 or 2, wherein the content of 1 polyolefin resin is 65% by mass or more based on the total amount of the resin components contained in the polyolefin resin composition.

4. The crosslinked polyolefin resin foam according to any one of claims 1 to 3, wherein the polyolefin resin is at least 1 selected from the group consisting of a polyethylene resin, a polypropylene resin, and an ethylene-vinyl acetate copolymer.

5. The crosslinked polyolefin resin foam according to any one of claims 1 to 4, wherein the content of 1 of the polyethylene resin, the polypropylene resin, or the ethylene-vinyl acetate copolymer is 65% by mass or more based on the total amount of the resin components contained in the polyolefin resin composition.

6. The crosslinked polyolefin resin foam according to any one of claims 1 to 5, wherein the polyolefin resin composition contains a nucleating agent.

7. The crosslinked polyolefin resin foam according to any one of claims 1 to 6, wherein the polyolefin resin composition contains an elastomer.

8. The crosslinked polyolefin resin foam according to any one of claims 1 to 7, which has an expansion ratio of 1.3 to 40 times.

9. The crosslinked polyolefin resin foam according to any one of claims 1 to 8, which is for an automobile interior material.

10. An adhesive tape comprising the crosslinked polyolefin resin foam according to any one of claims 1 to 9 and an adhesive material provided on at least one surface of the foam.

11. A laminate comprising the crosslinked polyolefin resin foam according to any one of claims 1 to 9 and a surface material provided on at least one surface of the foam.

12. An optical display member comprising the crosslinked polyolefin resin foam according to any one of claims 1 to 9.

13. A laminate comprising a skin layer and a foam layer, wherein the laminate has an Asker C hardness of 70 or less and a total light transmittance of more than 0.01%.

14. The laminate according to claim 13, wherein the skin layer has a thickness of 0.2 to 1.0 mm.

15. The laminate according to claim 13 or 14, wherein the skin layer has a total light transmittance of 0.02 to 30%.

16. The laminate according to any one of claims 13 to 15, wherein the thickness of the foam layer is 0.5 to 5 mm.

17. The laminate according to any one of claims 13 to 16, wherein the foamed layer has a total light transmittance of 10% or more.

18. The laminate according to any one of claims 13 to 17, wherein the foam layer has an expansion ratio of 7 to 40 times.

19. The laminate according to any one of claims 13 to 18, wherein the foam layer is a polyolefin foam layer or a polyurethane foam layer.

20. The laminate according to any one of claims 13 to 19, further comprising at least one of a printed layer and a printed film layer.

21. The laminate according to claim 20, wherein the printing layer is formed by printing a surface of at least one of the foam layer and the skin layer.

22. A light display member comprising the laminate according to any one of claims 13 to 21.

23. The light display means of claim 22, having a sensor element.

24. Light display means according to claim 22 or 23 provided with a display having sensor elements.

Technical Field

The present invention relates to a crosslinked polyolefin resin foam and a laminate obtained by crosslinking and foaming a polyolefin resin.

Background

Foams using polyolefin resins are used in various industrial fields because they are excellent in flexibility, cushioning properties, sealing properties, and heat insulating properties. For example, an adhesive tape in which the foam and the adhesive layer are laminated is used for devices equipped with a touch panel, such as a mobile phone and a smartphone. In such applications, the foam can easily adhere to fine irregularities inside the device by utilizing the flexibility of the foam. Further, the flexibility and adhesiveness of the foam may be used to protect the components inside the device from external factors such as impact and water.

On the other hand, since the foam has a large number of cells inside, it is difficult to make the foam transparent due to the difference in the refractive index between the air in the cells and the resin constituting the foam. Therefore, unlike an adhesive tape using a transparent base material such as a cellophane tape, an adhesive tape using a polyolefin resin foam as a base material is difficult to confirm a bonding position with the tape interposed therebetween, and the manufacturing efficiency of electronic devices and the like is lowered.

As a foam for solving such problems, patent document 1 proposes a polyolefin resin foam having a closed cell structure, having a total light transmittance of 15% or more, and having shrinkage ratios in the longitudinal direction (MD) and the width direction (TD), and an average cell diameter, thickness, apparent density, and 25% compression hardness in the longitudinal direction (MD) adjusted to specific ranges. Further, patent document 2 proposes an acrylic resin foam characterized in that the average cell diameter is 1.2mm or more. In cited documents 1 and 2, the light transmittance of the foam is improved mainly by adjusting the average cell diameter.

Further, patent document 3 proposes a heat insulating foam formed of a thermoplastic resin having a total light transmittance of 80% or more, having an expansion ratio of 5 to 100 times, and having an average cell diameter of 1 to 15 mm. In patent document 3, the light transmittance of the foam is improved by using a resin having a high total light transmittance such as methyl methacrylate.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2017-190375

Patent document 2: japanese patent laid-open publication No. 2013-203984

Patent document 3: japanese laid-open patent publication No. H08-067757

Disclosure of Invention

Problems to be solved by the invention

However, even when the polyolefin resin foam has an average cell diameter adjusted as in patent document 1, the total light transmittance is less than 20% if the thickness of the foam exceeds 0.3mm, and therefore there is room for improvement. On the other hand, as in patent documents 2 and 3, the problem of light transmittance may be solved by using an acrylic resin foam, but the acrylic resin foam has a problem that it is inferior in mechanical properties, flexibility, and the like, as compared with a foam obtained by electron beam crosslinking such as a polyolefin resin foam.

The present invention has been made in view of the above-mentioned conventional circumstances, and an object thereof is to provide a crosslinked polyolefin resin foam having excellent light transmittance.

The foams described in patent documents 1 to 3 have room for improvement from the viewpoint of combining high light transmittance and soft touch when used as a light display member having a function of displaying information such as temperature, time, and vehicle speed by light in a vehicle such as an automobile, for example. Another object of the present invention is to provide a laminate suitable for use as an optical display member, having high light transmittance, and having a soft touch.

Means for solving the problems

As a result of intensive studies, the present inventors have found that a crosslinked polyolefin resin foam having high light transmittance can be obtained by appropriately adjusting the expansion ratio, the resin component, and the compound blended with the resin, and have completed the present invention.

That is, the present invention is mainly directed to the following [1] to [24 ].

[1] A crosslinked polyolefin resin foam obtained by crosslinking and foaming a polyolefin resin composition containing a polyolefin resin,

the crosslinked polyolefin resin foam has a total light transmittance of 45% or more when the thickness is 0.3mm or more and less than 1.0mm, and a total light transmittance of 30% or more when the thickness is 1.0mm or more and 5.0mm or less.

[2] The crosslinked polyolefin resin foam according to [1], wherein the content of the polyolefin resin is 65% by mass or more based on the total amount of the resin components contained in the polyolefin resin composition.

[3] The crosslinked polyolefin resin foam according to [1] or [2], wherein the content of the 1 polyolefin resin is 65% by mass or more based on the total amount of the resin components contained in the polyolefin resin composition.

[4] The crosslinked polyolefin resin foam according to any one of the above [1] to [3], wherein the polyolefin resin is at least 1 selected from the group consisting of polyethylene resins, polypropylene resins, and ethylene-vinyl acetate copolymers.

[5] The crosslinked polyolefin resin foam according to any one of the above [1] to [4], wherein the content of any one of 1 polyethylene resin, polypropylene resin, and ethylene-vinyl acetate copolymer is 65% by mass or more based on the total amount of the resin components contained in the polyolefin resin composition.

[6] The crosslinked polyolefin resin foam according to any one of the above [1] to [5], wherein the polyolefin resin composition contains a nucleating agent.

[7] The crosslinked polyolefin resin foam according to any one of the above [1] to [6], wherein the polyolefin resin composition contains an elastomer.

[8] The crosslinked polyolefin resin foam according to any one of the above [1] to [7], which has an expansion ratio of 1.3 to 40 times.

[9] The crosslinked polyolefin resin foam according to any one of the above [1] to [8], which is for an automobile interior material.

[10] An adhesive tape comprising the crosslinked polyolefin resin foam according to any one of [1] to [9] and an adhesive material provided on at least one surface of the foam.

[11] A laminate comprising the crosslinked polyolefin resin foam according to any one of [1] to [9] and a surface material provided on at least one surface of the foam.

[12] An optical display member comprising the crosslinked polyolefin resin foam according to any one of the above [1] to [9 ].

[13] A laminate comprising a skin layer and a foam layer, wherein the laminate has an Asker C hardness of 70 or less and a total light transmittance of more than 0.01%.

[14] The laminate according to the above [13], wherein the skin layer has a thickness of 0.2 to 1.0 mm.

[15] The laminate according to the above [13] or [14], wherein the skin layer has a total light transmittance of 0.02 to 30%.

[16] The laminate according to any one of the above [13] to [15], wherein the thickness of the foam layer is 0.5 to 5 mm.

[17] The laminate according to any one of the above [13] to [16], wherein the foamed layer has a total light transmittance of 10% or more.

[18] The laminate according to any one of the above [13] to [17], wherein the expansion ratio of the foam layer is 7 to 40 times.

[19] The laminate according to any one of the above [13] to [18], wherein the foam layer is a polyolefin foam layer or a polyurethane foam layer.

[20] The laminate according to any one of the above [13] to [19], further comprising at least one of a printed layer and a printed film layer.

[21] The laminate according to item [20], wherein the printed layer is formed by printing on a surface of at least one of the foam layer and the skin layer.

[22] A light display member comprising the laminate according to any one of [13] to [21 ].

[23] The light display member according to the above [22], which has a sensor element.

[24] The light display member according to the above [22] or [23], which is provided with a display having a sensor element.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, a crosslinked polyolefin resin foam having excellent light transmittance can be provided.

The laminate of the present invention is a laminate exhibiting high light transmittance and soft touch.

Drawings

FIG. 1 is a sectional view of one embodiment of the laminate of the present invention.

FIG. 2 is a sectional view of another embodiment of the laminate of the present invention.

FIG. 3 is a sectional view of another embodiment of the laminate of the present invention.

Fig. 4 is a plan view showing an example of the printing layer of the present invention.

Detailed Description

[1 st invention ]

The invention 1 in the present invention is a crosslinked polyolefin resin foam described below.

[ crosslinked polyolefin resin foam ]

The crosslinked polyolefin resin foam of the present invention is a crosslinked polyolefin resin foam obtained by crosslinking and foaming a polyolefin resin composition containing a polyolefin resin.

The crosslinked polyolefin resin foam of the present invention has a total light transmittance of 45% or more when the thickness is 0.3mm or more and less than 1.0mm, and a total light transmittance of 30% or more when the thickness is 1.0mm or more and 5.0mm or less. When the total light transmittance is within the above range, a crosslinked polyolefin resin foam having excellent light transmittance according to the thickness can be provided.

In addition, the crosslinked polyolefin resin foam is preferably composed mainly of a polyolefin resin. Specifically, the content of the polyolefin resin is preferably 65% by mass or more based on the total amount of the resin components contained in the polyolefin resin composition. In general, crosslinked polyolefin resin foams that use a polyolefin resin as a main component tend to have reduced light transmittance, but in the present invention, as will be described later, by appropriately adjusting the expansion ratio, resin component, compound blended with a resin, and the like, crosslinked polyolefin resin foams having excellent total light transmittance can be obtained.

< full light transmittance >

The crosslinked polyolefin resin foam (hereinafter, also referred to as "foam") of the present invention has a total light transmittance of 45% or more when the thickness is 0.3mm or more and less than 1.0 mm. When the total light transmittance is 45% or more when the thickness of the foam is 0.3mm or more and less than 1.0mm, the foam has sufficient light transmittance, and thus can be suitably used for optical display members for automobile interior, electronic devices such as smart phones, and the like. From this viewpoint, when the thickness of the foam is 0.3mm or more and less than 1.0mm, the total light transmittance is preferably 50% or more, more preferably 55% or more, further preferably 60% or more, and particularly preferably 70% or more. When the thickness is 0.3mm or more and less than 1.0mm, the higher the total light transmittance is, the better, but it is, for example, 95% or less.

When the thickness is 0.3mm or more and less than 1.0mm, the total light transmittance can be set to the above range by appropriately adjusting the expansion ratio, the resin component, the compound blended with the resin, and the like. The total light transmittance can be measured by the method described in examples.

The foam of the present invention has a total light transmittance of 30% or more when the thickness is 1.0mm or more and 5.0mm or less. When the thickness of the foam is 1.0mm or more and 5.0mm or less, the total light transmittance is 30% or more, since sufficient light transmittance and impact absorbability are both obtained, the foam can be suitably used for light transmissive members for automobile interior and electronic devices such as smart phones. From this viewpoint, when the thickness of the foam is 1.0mm or more and 5.0mm or less, the total light transmittance is preferably 35% or more, more preferably 40% or more, and still more preferably 45% or more. When the thickness of the foam is 1.0mm or more and 5.0mm or less, the higher the total light transmittance is, the better, but the total light transmittance is, for example, 90% or less. When the thickness is 1.0mm to 5.0mm, the total light transmittance can be set to the above range by appropriately adjusting the expansion ratio, the resin component, the compound blended with the resin, and the like.

< degree of crosslinking (gel fraction) >)

The degree of crosslinking (gel fraction) of the foam of the present invention is preferably 15 to 60% by mass. When the gel fraction is not less than the lower limit, sufficient crosslinking is formed in the foam, and therefore the mechanical strength tends to be high. Further, if the degree of crosslinking is not more than these upper limit values, the flexibility of the foam and the like can be easily ensured. From such a viewpoint, the crosslinking degree is more preferably 20 to 55% by mass, and still more preferably 25 to 50% by mass. The degree of crosslinking can be measured by the measurement method described later.

< expansion ratio >

The foaming ratio of the foam is preferably 1.3 to 40 times, more preferably 1.5 to 12 times, still more preferably 1.8 to 9 times, and still more preferably 2.0 to 7 times. When the expansion ratio is not less than the lower limit, the light transmittance is improved, and the foam is appropriately expanded to improve flexibility and impact absorption. Further, although the light transmittance tends to be improved if the expansion ratio is high, the upper limit value is preferably not more than the above-mentioned upper limit value in order to secure the mechanical strength. In the present invention, the total light transmittance can be improved by adjusting the expansion ratio and appropriately selecting the kind of resin, nucleating agent, and the like to be described later.

< apparent Density >

In the present invention, the apparent density of the foam is preferably 0.05 to 0.60g/cm³. When the apparent density of the foam is within the above range, the light transmittance is improved, and at the same time, certain flexibility and mechanical strength are imparted, and the impact absorbability and the like are also improved. From these viewpoints, the apparent density is more preferably 0.10 to 0.50g/cm³More preferably 0.15 to 0.40g/cm³。

< thickness >

The thickness of the foam of the present invention is 0.3 to 5.0mm, preferably 0.3 to 2.0mm, and more preferably 0.3 to 1.5 mm. When the thickness of the foam is not less than the lower limit, the light transmittance can be improved while maintaining the mechanical strength. On the other hand, if the upper limit value is less than or equal to the above-described upper limit value, the light-transmissive optical element can be used in small electronic devices such as smartphones while maintaining the light transmittance.

(iii) compressive Strength of < 25 >

The 25% compressive strength of the foam is preferably 30 to 200 kPa. When the 25% compressive strength is not more than the upper limit, the flexibility of the foam is improved, and the following property to an adherend, for example, when the adhesive tape is produced, is improved. On the other hand, if the 25% compressive strength is not less than the lower limit, the mechanical strength, impact absorbability, and the like become good. From these viewpoints, the 25% compressive strength of the foam is more preferably 30 to 150 kPa.

The 25% compressive strength is a value measured by a measuring method according to JIS K6767.

< polyolefin resin >

The polyolefin resin is preferably at least 1 selected from the group consisting of polyethylene resins, polypropylene resins, and ethylene-vinyl acetate copolymers. These resins may be used alone in any 1 kind, or may be used in combination of 2 or more kinds.

The foam of the present invention preferably contains a polyolefin resin as a main component, and specifically, the content of the polyolefin resin is preferably 65 mass% or more based on the total amount of the resin components contained in the polyolefin resin composition. When the content of the polyolefin resin is 65% by mass or more, the mechanical strength, flexibility, and the like of the foam can be easily ensured. As will be described later, it is easy to use 1 polyolefin resin as the main component resin. From these viewpoints, the content of the polyolefin resin is preferably 70 to 100% by mass, more preferably 75 to 100% by mass, based on the total amount of the resin components contained in the foam resin composition. Hereinafter, the total amount of the resin component contained in the polyolefin resin composition is simply referred to as "total amount of the resin component".

Polyethylene resin

As the polyethylene resin, a low density polyethylene resin (0.93 g/cm)³Hereinafter, LDPE), medium density polyethylene resin (more than 0.930 g/cm)³And less than 0.942g/cm³MDPE), high density polyethylene resin (0.942 g/cm)³HDPE above). Further, a suitable example of the low-density polyethylene resin is a linear low-density polyethylene resin (LLDPE).

Among them, linear low-density polyethylene resins and high-density polyethylene resins are preferable, and linear low-density polyethylene resins are more preferable. By using these resins, the rate of change in the compressive strength of the foam is likely to be low.

Further, the linear low-density polyethylene resin preferably has a density of 0.90g/cm³Above, more preferably 0.91g/cm³Above and 0.93g/cm³The following. Further, the density of the high-density polyethylene resin is preferably 0.98g/cm³Hereinafter, more preferably 0.95g/cm³Above and 0.97g/cm³The following. When the density of the high-density polyethylene resin or the linear low-density polyethylene resin is in these ranges, the compression strength and the like can be easily reduced without impairing the flexibility of the foam.

The polyethylene resin may be a homopolymer of ethylene, or a copolymer of ethylene and a small amount of α -olefin, which contains ethylene as a main component (preferably 75% by mass or more, more preferably 90% by mass or more of the total monomers). The α -olefin is preferably an α -olefin having 3 to 12 carbon atoms, more preferably 4 to 10 carbon atoms, and specifically includes 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene, and the like. In addition, these α -olefins may be used alone or in combination of 2 or more.

Further, the polyethylene resin may be used alone in 1 kind, or may be used in combination in 2 or more kinds.

Polypropylene resin

The polypropylene resin may be homopolypropylene which is a homopolymer of propylene, and examples thereof include a copolymer of propylene with a small amount of ethylene and an α -olefin other than propylene, the copolymer having propylene as a main component (preferably 75% by mass or more, more preferably 90% by mass or more of the total monomers).

Examples of the copolymer of propylene and an α -olefin other than ethylene and propylene include a block copolymer (block polypropylene), a random copolymer (random polypropylene), and a random block copolymer.

The α -olefin other than propylene includes α -olefins having about 4 to 10 carbon atoms such as 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, and 1-octene, and among them, ethylene is preferable from the viewpoint of moldability and heat resistance. In addition, in the copolymer, these alpha-olefins can be used alone or in combination of 2 or more.

The polypropylene resin may be used alone, or 2 or more kinds may be used in combination.

In the present invention, any of a polyethylene resin, a polypropylene resin, or a mixture thereof, which is polymerized by a polymerization catalyst such as a ziegler/natta compound, a metallocene compound, or a chromium oxide compound, can be used. By using a polyethylene resin, particularly a linear low-density polyethylene, obtained by using a polymerization catalyst for a metallocene compound, a foam having high flexibility and high impact absorbability can be easily obtained.

Ethylene-vinyl acetate copolymer

Examples of the ethylene-vinyl acetate copolymer used as the polyolefin resin include an ethylene-vinyl acetate copolymer containing 50 mass% or more of a structural unit derived from ethylene. Since the ethylene-vinyl acetate copolymer has high compatibility with a polyethylene resin and a polypropylene resin, the light transmittance of the foam is improved by using the ethylene-vinyl acetate copolymer in combination with 1 or more selected from the group consisting of a polyethylene resin and a polypropylene resin.

The density of the ethylene-vinyl acetate copolymer is preferably 0.92g/cm³Above, more preferably 0.93g/cm³Above, more preferably 0.94g/cm³Above, it is preferably 0.97g/cm³Hereinafter, more preferably 0.96g/cm³The following. When the density of the ethylene-vinyl acetate copolymer is in these ranges, the flexibility of the foam is not impaired, and the compressive strength and the like are easily lowered.

In the present invention, the polyolefin resin composition preferably uses any 1 of the above polyolefin resins as a main component resin. The main component resin is any 1 resin among polyolefin resins, and is contained in an amount of 65 mass% or more based on the total amount of the resin components, and therefore, it is preferable that any 1 resin among polypropylene resins, polyethylene resins, or ethylene-vinyl acetate copolymers is contained in an amount of 65 mass% or more.

In general, if 2 or more resins are blended, the resins are not completely mixed with each other, and turbidity is generated due to mixing, but in the present invention, by using 1 specific resin (i.e., a single resin component) as a main component resin, turbidity generated due to blending is not easily generated, and the light transmittance of the foam is improved.

The resin to be the main component resin is preferably any one of a polypropylene resin and a polyethylene resin, and more preferably a polypropylene resin, among the above resins. The foam is excellent in heat resistance by using a polypropylene resin as the main component resin, and can be suitably used for automobile interior materials.

More specifically, when a polypropylene resin is used as the main component resin, the polypropylene resin is preferably contained in an amount of 65% by mass or more, preferably 75% by mass or more, more preferably 85% by mass or more, and most preferably 100% by mass, based on the total amount of the resin components.

Further, it is preferable that the specific 1 resin out of the polypropylene resins is contained in an amount of 65 mass% or more based on the total amount of the resin components. For example, it is preferable to make the block polypropylene content 65 mass% or more or to make the random polypropylene content 65 mass% or more, and in this case, these specific 1 types of resins are also preferably contained by 75 mass% or more, more preferably 85 mass% or more, and most preferably 100 mass%.

Similarly, when a polyethylene resin is used as the main component resin, the polyethylene resin is preferably contained in an amount of 65 mass% or more, preferably 75 mass% or more, and more preferably 85 mass% or more, based on the total amount of the resin components.

Further, it is preferable that the specific 1 resin among the polyethylene resins is contained in an amount of 65 mass% or more based on the total amount of the resin components. For example, LDPE is preferably 65 mass% or more, and in this case, these specific 1 kind of resins are also preferably 75 mass% or more, and more preferably 85 mass% or more.

In addition, in the case of using a polypropylene resin as the main component resin, as the polyolefin-based resin, the polypropylene resin may be used alone, but in addition to the polypropylene resin, at least 1 selected from the group consisting of a polyethylene resin and an ethylene-vinyl acetate copolymer may be used in combination. If the polypropylene resin is used alone, it is not necessary to be compatible with other polyolefin resins, and thus a decrease in transparency caused by mixing of resins with each other can be prevented. Further, by using a polypropylene resin in combination with at least 1 selected from the group consisting of an ethylene-vinyl acetate copolymer and a polyethylene resin, compatibility becomes good and transparency is maintained well. Further, since the degree of crosslinking and the expansion ratio can be easily adjusted, the total light transmittance of the foam can be easily adjusted.

In this case, it is preferable that the content of the polypropylene resin is 65 to 95% by mass and the content of at least one selected from the group consisting of the polyethylene resin and the ethylene-vinyl acetate copolymer is 5 to 35% by mass based on the total amount of the resin components. The content of the organic solvent is more preferably 75 to 95% by mass, the content of the organic solvent is more preferably 5 to 25% by mass, the content of the organic solvent is more preferably 85 to 95% by mass, and the content of the organic solvent is more preferably 5 to 15% by mass.

The resin used in combination is preferably either a polyethylene resin or an ethylene-vinyl acetate copolymer, and more preferably an ethylene-vinyl acetate copolymer.

When a polypropylene resin is used as the main component resin, an elastomer may be further used as described later. The content of the elastomer in this case is as described later.

On the other hand, in the case of using a polyethylene resin as the main component resin, at least 1 selected from the group consisting of a polypropylene resin and an ethylene-vinyl acetate copolymer may be used in combination as the polyolefin resin in addition to the polyethylene resin, but it is preferable to use the polyethylene resin alone. However, when the polyethylene resin is used alone, it is preferable to further use an elastomer described later, and the content of the elastomer in this case is as described later.

The resin constituting the foam may be composed of only a polyolefin resin, but may be a resin obtained by mixing a polyolefin resin and an elastomer. When the polyolefin resin composition contains an elastomer, the crystallinity of the polyolefin resin can be reduced, and the total light transmittance of the foam can be improved. That is, in the present invention, it is preferable to use an elastomer that functions as a so-called transparentizing agent.

Further, by using an elastomer, the flexibility and impact absorbability of the foam can be improved.

As the elastomer, an elastomer having good compatibility with a polyolefin resin is used, and specific examples thereof include ethylene-propylene-diene rubber (EPDM), ethylene-propylene rubber (EPM), styrene rubber, and the like.

Further, as the elastomer, a thermoplastic elastomer can be cited. Examples of the thermoplastic elastomer include olefin-based thermoplastic elastomers and styrene-based thermoplastic elastomers.

The elastomer may be used alone with 1 kind of the above components, or may be used in combination with 2 or more kinds. From the viewpoint of easily adjusting the total light transmittance of the foam within the above range, styrene rubber, olefin-based thermoplastic elastomers, and styrene-based thermoplastic elastomers are preferred, and styrene rubber and styrene-based thermoplastic elastomers are more preferred.

The styrene rubber includes various polymers such as a random copolymer of styrene and a conjugated diene compound, and hydrogenated products thereof. Specifically, styrene butadiene copolymer (SBR) and hydrogenated product thereof (HSBR) are exemplified.

Examples of the olefinic thermoplastic elastomer include a blend type and a dynamic crosslinking type, and more specifically, a thermoplastic elastomer in which a thermoplastic crystalline polyolefin such as polypropylene or polyethylene is used for a hard segment, and a fully vulcanized or partially vulcanized rubber is used for a soft segment. Examples of the soft segment component include butyl rubber, halobutyl rubber, EPDM, EPM, acrylonitrile/butadiene rubber, NBR, natural rubber, etc., and EPDM is preferably used.

Further, as the olefinic thermoplastic elastomer, a block copolymer type can be also exemplified. The block copolymer type includes a material having a crystalline block and a soft segment block, and more specifically, a crystalline olefin block-ethylene/butene copolymer-crystalline olefin block copolymer (CEBC) is exemplified. In the CEBC, the crystalline olefin block is preferably a crystalline ethylene block, and commercially available products of such CEBC include "DYNARON 6200P" manufactured by JSR.

Examples of the styrene-based thermoplastic elastomer include a block copolymer having a polymer or copolymer block of styrene and a polymer or copolymer block of a conjugated diene compound. Examples of the conjugated diene compound include isoprene and butadiene.

The styrene-based thermoplastic elastomer used in the present invention may or may not be hydrogenated. In the case of hydrogenation, the hydrogenation may be carried out by a known method.

The styrene-based thermoplastic elastomer is usually a block copolymer, and examples thereof include a styrene-isoprene block copolymer, a styrene-isoprene-styrene block copolymer, a styrene-butadiene-styrene block copolymer, a styrene-ethylene/butylene-styrene block copolymer (SEBS), a styrene-ethylene/propylene-styrene block copolymer (SEPS), a styrene-ethylene/butylene block copolymer (SEB), a styrene-ethylene/propylene block copolymer (SEP), a styrene-ethylene/butylene-crystalline olefin block copolymer (SEBC), and the like.

The styrene-based thermoplastic elastomer is preferably a block copolymer, and particularly preferably SEBC. By using such an elastomer in combination with a polyolefin resin, the light transmittance of the foam can be improved by further adjusting the expansion ratio.

Further, commercially available products of styrene-based thermoplastic elastomers include a trade name "DYNARON 1320P" (styrene content: 10 mass%), a trade name "DYNARON 8600P" (styrene content: 15 mass%) manufactured by JSR, and a trade name "DYNARON 4600P" (styrene content: 20 mass%).

In the present invention, when the polyolefin resin is used in combination with the elastomer as the resin component, the content of the elastomer is preferably 5 to 30% by mass, more preferably 8 to 22% by mass, based on the amount of the resin component. If the content of the elastomer is within these ranges, the light transmittance of the foam can be further improved while maintaining the mechanical strength of the foam.

< nucleating agent >

The polyolefin resin composition of the present invention preferably contains a nucleating agent. The nucleating agent used in the present invention is not particularly limited as long as it has an effect of increasing the rate of progress of the process of generating crystal nuclei. By adding a nucleating agent to a polyolefin resin such as a polyethylene resin or a polypropylene resin, the size of crystals to be generated can be reduced, and thus the transparency of the foam can be improved.

The nucleating agent used in the present invention has an effect of accelerating the molecular chain orientation through the adsorption process of the molecular chains of the polymer, as an effect of accelerating the progress rate of the crystal nucleus formation process.

More specifically, there may be mentioned high-melting point polymers, organic carboxylic acids or metal salts thereof, aliphatic alcohols, dibenzylidene sorbitol or derivatives thereof, abietic acid partial metal salts, amide compounds, inorganic fine particles, organic phosphoric acid compounds or metal salts thereof, imides, quinacridones, quinones, aromatic sulfonic acid salts or metal salts thereof, saccharides, and mixtures thereof. These may be used alone in 1 kind, or may be used in combination of 2 or more kinds.

Examples of the high-melting-point polymer include polyolefins such as poly-3-methylpentene-1 and poly-3-methylbutene-1, polyvinyl cycloalkanes such as polyvinyl cyclohexane and polyvinyl cyclopentane, syndiotactic polystyrene, and polyalkenylsilane.

Examples of the organic carboxylic acid and the metal salt thereof include benzoic acid, p-tert-butylbenzoic acid, adipic acid, thiophenecarboxylic acid, pyrrolecarboxylic acid, aluminum benzoate, aluminum p-tert-butylbenzoate, sodium adipate, sodium thiophenecarboxylate, and sodium pyrrolecarboxylate.

Examples of dibenzylidene sorbitol and its derivatives include dibenzylidene sorbitol, 1, 3: 2, 4-bis (o-3, 4-dimethylbenzylidene) sorbitol, 1, 3: 2, 4-bis (o-2, 4-dimethylbenzylidene) sorbitol, 1, 3: 2, 4-bis (o-4-ethylbenzylidene) sorbitol, 1, 3: 2, 4-bis (o-4-chlorobenzylidene) sorbitol, 1, 3: 2, 4-dibenzylidene sorbitol, and the like. Commercially available products of dibenzylidene sorbitol and its derivatives include ゲルオール MD and ゲルオール MD-R (trade name) manufactured by Nissan chemical Co., Ltd.

Examples of the rosin acid partial metal salt include パインクリスタル KM1600, パインクリスタル KM1500, and パインクリスタル KM1300 (trade name) manufactured by seikagawa chemical industries co.

Examples of the amide compound include adipamide, suberoylanilide, and the like.

Examples of the inorganic fine particles include talc, clay, mica, asbestos, glass fiber, glass flake, glass bead, calcium silicate, montmorillonite, bentonite, graphite, aluminum powder, alumina, silica, diatomaceous earth, titanium oxide, magnesium oxide, pumice powder, pumice ball, aluminum hydroxide, magnesium hydroxide, basic magnesium carbonate, dolomite, calcium sulfate, potassium titanate, barium sulfate, calcium sulfite, and molybdenum sulfide.

The organic metal phosphate is preferably one having a small odor of the organic metal phosphate represented by the following general formula (1).

(in the formula, R¹R represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms²And R³Each represents a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group, an aryl group or an aralkyl group. M represents 1 selected from alkali metals, alkaline earth metals, aluminum and zinc. M represents 0, n represents 1 when M is an alkali metal, n represents 1 or 2 when M is an alkaline earth metal or zinc, M represents 1 when n is 1, M represents 0 when n is 2, M represents 1 when M is aluminum, and n represents 2. )

As commercially available products of metal salts of organic phosphoric acid, アデカスタブ NA-11 and アデカスタブ NA-21 (ADEKA, Co., Ltd.) are exemplified.

Among the nucleating agents, a saccharide-based one is preferable from the viewpoint of compatibility with an olefin-based one and transparency. Examples of the saccharide-based system include sorbitol-based, Nonitol-based (Nonitol-based), and xylitol-based systems, and more preferably 1 or more selected from these are used as the nucleating agent.

In the case where a nucleating agent is used in the present invention, the content of the nucleating agent in the polyolefin resin composition is preferably 0.5 to 10 parts by mass, more preferably 1.5 to 8 parts by mass, and still more preferably 2 to 7 parts by mass, per 100 parts by mass of the polyolefin resin. If the content of the nucleating agent is not less than the lower limit, the transparency of the foam is improved. On the other hand, if the content of the nucleating agent is not more than the upper limit, the transparency of the foam can be improved while suppressing the production cost.

The polyolefin resin composition of the present invention may contain both a nucleating agent and an elastomer, but preferably contains either one. By providing either of them, the light transmittance can be effectively improved.

< blowing agent >

The foam of the present invention is obtained by foaming a polyolefin resin composition containing a resin containing a polyolefin resin, a foaming agent, and the like. The foaming agent is preferably a thermal decomposition type foaming agent.

As the thermal decomposition type foaming agent, an organic foaming agent or an inorganic foaming agent can be used. Examples of the organic blowing agent include azodicarbonamide, metal salts of azodicarboxylic acid (such as barium azodicarboxylate), azo compounds such as azobisisobutyronitrile, nitroso compounds such as N, N '-dinitrosopentamethylenetetramine, hydrazine derivatives such as biurea, 4' -oxybis (benzenesulfonylhydrazide) and toluenesulfonylhydrazide, and semicarbazide compounds such as toluenesulfonylsemicarbazide.

Examples of the inorganic foaming agent include ammonium carbonate, sodium carbonate, ammonium hydrogen carbonate, sodium hydrogen carbonate, ammonium nitrite, sodium borohydride, anhydrous monosodium citrate, and the like.

Among them, from the viewpoint of obtaining fine bubbles and from the viewpoint of economy and safety, the azo compound is preferable, and azodicarbonamide is more preferable.

The thermal decomposition type foaming agent can be used alone in 1, also can be combined with more than 2.

The content of the foaming agent in the polyolefin resin composition is preferably 1 to 30 parts by mass, more preferably 2 to 25 parts by mass, and still more preferably 2 to 20 parts by mass, based on 100 parts by mass of the polyolefin resin. By adjusting the mixing amount of the foaming agent to 1 part by mass or more, the foamable sheet is appropriately foamed, and appropriate flexibility and impact absorbability can be imparted to the foam. Further, by setting the mixing amount of the foaming agent to 30 parts by mass or less, excessive foaming of the foam can be prevented, and the mechanical strength and the like of the foam can be improved.

< additive >

The polyolefin resin composition may contain components such as a crosslinking assistant, a decomposition temperature regulator, and an antioxidant.

As the crosslinking assistant, a polyfunctional monomer may be used. By adding the crosslinking assistant to the polyolefin-based resin, the dose of ionizing radiation irradiated in the step (2) described later is reduced, and the resin molecules are prevented from being cut or deteriorated due to the irradiation of ionizing radiation.

Specific examples of the crosslinking assistant include compounds having 3 functional groups in 1 molecule, such as trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, triallyl trimellitate, triallyl 1,2, 4-benzenetrimethacrylate, and triallyl isocyanurate, 1, 6-hexanediol dimethacrylate, 1, 9-nonanediol dimethacrylate, 1, 10-decanediol dimethacrylate, and divinylbenzene, and compounds having 2 functional groups in 1 molecule, such as diallyl phthalate, diallyl terephthalate, diallyl isophthalate, ethylvinylbenzene, neopentyl glycol dimethacrylate, lauryl methacrylate, and stearyl methacrylate.

These crosslinking assistants may be used alone or in combination of 2 or more.

The amount of the crosslinking aid added is preferably 0.5 to 10 parts by mass, more preferably 1.0 to 8 parts by mass, and still more preferably 1.5 to 5 parts by mass, based on 100 parts by mass of the polyolefin resin. When the amount is 0.5 parts by mass or more, the foam can stably obtain a desired degree of crosslinking, and when the amount is 10 parts by mass or less, the degree of crosslinking of the foam can be easily controlled.

The polyolefin resin composition may contain a decomposition temperature regulator. The decomposition temperature regulator is compounded as a substance for regulating the decomposition temperature of the thermal decomposition type foaming agent to be low or the decomposition rate to be high, and specific compounds include zinc oxide, zinc stearate, urea and the like. The decomposition temperature regulator is blended in an amount of, for example, 0.01 to 5 parts by mass per 100 parts by mass of the polyolefin resin, for the purpose of adjusting the surface state of the foam.

An antioxidant may be blended in the polyolefin resin composition. Examples of the antioxidant include phenol antioxidants such as 2, 6-di-tert-butyl-p-cresol and pentaerythritol tetrakis [3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ], sulfur antioxidants such as dilauryl thiodipropionate, phosphorus antioxidants, and amine antioxidants. The antioxidant is compounded, for example, in an amount of 0.01 to 5 parts by mass per 100 parts by mass of the polyolefin resin.

In addition to these, additives generally used for foams, such as a heat stabilizer, a coloring agent, a flame retardant, an antistatic agent, and a filler, may be blended in the polyolefin resin composition.

[ method for producing foam ]

The method for producing the foam of the present invention is not particularly limited, and the foam can be produced by heating a foamable sheet formed from a polyolefin resin composition containing at least a resin and a thermal decomposition type foaming agent to foam the thermal decomposition type foaming agent. More specifically, the production method preferably includes the following steps (1) to (3).

Step (1): process for molding foamable sheet comprising polyolefin resin composition containing at least resin and thermal decomposition type foaming agent

Step (2): step of irradiating the foamable sheet with ionizing radiation to crosslink the foamable sheet

Step (3): heating the crosslinked foamable sheet to foam a thermal decomposition type foaming agent to obtain a foam

In the step (1), a method for molding the foamable sheet is not particularly limited, and for example, the foamable sheet may be molded by supplying the resin and the additive to an extruder, melt-kneading the mixture, and extruding the polyolefin resin composition in a sheet form from the extruder. The foam can be molded by pressing or the like the polyolefin resin composition.

The molding temperature of the foamable sheet (i.e., the temperature at the time of extrusion or the temperature at the time of pressing) is preferably 50 ℃ or more and 250 ℃ or less, and more preferably 80 ℃ or more and 180 ℃ or less.

In the step (2), as a method for crosslinking the polyolefin resin composition, a method of irradiating an ionizing radiation such as an electron beam, an α ray, a β ray, or a γ ray to the foamable sheet is used. The irradiation amount of the ionizing radiation may be adjusted so that the degree of crosslinking of the obtained foam is within the desired range, and is preferably 1 to 12Mrad, and more preferably 1.5 to 8 Mrad.

In the step (3), the heating temperature at which the polyolefin resin composition is heated to foam the thermal decomposition type foaming agent may be not less than the foaming temperature of the thermal decomposition type foaming agent, and is preferably 200 to 300 ℃, and more preferably 220 to 280 ℃.

Further, in the present manufacturing method, the foam may be stretched in either or both of MD or TD. The stretching of the foam may be performed after the foam is obtained by foaming the foamable sheet, or may be performed while the foamable sheet is foamed. In addition, when the foam is stretched after the foamable sheet is foamed to obtain the foam, the foam may be stretched while maintaining the molten state during foaming without cooling the foam, or may be stretched after cooling the foam and heating the foam again to form a molten or softened state. The foam is easily thinned by stretching. The foam may be heated to 100 to 280 ℃, preferably 150 to 260 ℃ during stretching. In the present invention, by stretching the foam, the cell diameter of the foam becomes large along one or both of MD and TD, and the light transmittance is likely to be high.

However, the present production method is not limited to the above, and a foam may be obtained by a method other than the above. For example, instead of irradiation with ionizing radiation, crosslinking may be performed by a method in which an organic peroxide is mixed in advance with the polyolefin-based resin composition, and the foamable sheet is heated to decompose the organic peroxide.

In addition, in the production of the foam of the present invention, a foam having a desired thickness can be produced by slicing the obtained foam.

[ method of Using foam ]

The foam of the present invention can be suitably used for various electronic devices, automobile interior materials, and the like, and is more preferably used for automobile interior materials. Examples of the electronic device include a mobile phone such as a smartphone, a game device, an electronic manual, a tablet terminal, a notebook personal computer, and the like.

The foam can be used as, for example, a sealing material or an impact absorbing material in various electronic devices. The foam of the present invention is excellent in light transmittance, and therefore, can be bonded to various electronic components and the like with high positional accuracy because the bonding position and the like can be confirmed through the foam sheet.

The foam of the present invention can be suitably used as a light display member. The light display member is a member in which a light source such as a Light Emitting Diode (LED) is disposed on one surface (i.e., a rear surface) side of the foam, and light is irradiated from the light source toward the foam to transmit the light through the foam, and various information is displayed on the other surface (i.e., a front surface) side of the foam by the light from the light source.

The foam may be laminated with other members to form a laminate. Specifically, a laminate having the foam of the present invention and a surface material provided on at least one side of the foam is preferably produced. Such a laminate can be used for any of electronic devices and automobile interiors, but is preferably used for automobile interiors.

The laminate is preferably used as a light display member. In the light display member, light is irradiated from the back side of the foam body using a light source such as a Light Emitting Diode (LED) and the like, and the light is transmitted through the foam body and the surface material, whereby various information (such as a vehicle speed) can be displayed on the surface material. Further, if the surface material is provided with the geometrically patterned irregularities or the like, the transmitted light floats in the geometrically patterned manner, so that the design of the interior of the automobile can be improved.

Surface materials are also called skin materials in automobile interior materials. Specifically, examples of the surface material include a polyvinyl chloride sheet, a mixed resin of polyvinyl chloride and an ABS resin, a resin sheet exemplified in a thermoplastic elastomer sheet, and leathers such as woven fabrics, knitted fabrics, nonwoven fabrics, artificial leathers, and synthetic leathers using natural fibers and artificial fibers. The surface material may be appropriately provided with the geometrically patterned irregularities as described above. Among them, a resin sheet is preferable, and a resin sheet having light transmittance is more preferable. By using a light-transmitting resin sheet, various information can be displayed on the surface material by the light from the light source. Further, light transmittance can be given to the entire laminate.

The thickness of the surface material is not particularly limited, but is, for example, 0.1 to 5mm, preferably 0.2 to 2mm, and more preferably 0.2 to 1 mm. By setting the thickness of the surface material within these ranges, the mechanical strength and the like of the surface material can be improved, and high light transmittance and the like can be ensured. Further, by setting the thickness of the surface material to 0.2mm or more, the inside of the foam or the like can be prevented from being seen through.

The total light transmittance of the surface material is not particularly limited, but is preferably 0.02 to 30%. If the total light transmittance of the surface material is 0.02% or more, the total light transmittance of the entire laminate can be easily adjusted to a certain level or more. If the total light transmittance of the surface material is 30% or less, the interior of the foam or the like can be easily prevented from being seen through the surface material. The total light transmittance of the surface material is preferably 0.05 to 25%, more preferably 0.1 to 22%.

Examples of the method of bonding the surface materials include extrusion lamination, adhesive lamination in which the surface materials are bonded after applying an adhesive, heat lamination (hot melt method), hot melt method, high frequency welding method, and the like, and any method may be used as long as both are bonded.

When the foam is used for an automobile interior material, the foam and the laminate having the foam can be appropriately molded into a desired shape. Examples of the molding method include vacuum molding, compression molding, and press molding.

[ adhesive tape ]

The pressure-sensitive adhesive tape of the present invention uses the foam of the present invention as a base material, and a pressure-sensitive adhesive material is provided on one surface or both surfaces of the foam. The thickness of the adhesive tape is usually about 0.5 to 2.0 mm.

The thickness of the adhesive material constituting the adhesive tape is preferably 50 to 200 μm, and more preferably 80 to 150 μm. When the thickness of the adhesive material constituting the adhesive tape is 50 to 200 μm, the thickness of the adhesive tape can be reduced and the light transmittance can be improved.

The pressure-sensitive adhesive material may be a single pressure-sensitive adhesive layer laminated on at least one surface of the foam, or may be a double-sided pressure-sensitive adhesive sheet adhered to at least one surface of the foam, as long as it has at least a pressure-sensitive adhesive layer. The double-sided adhesive sheet includes a base and adhesive layers provided on both sides of the base. The double-sided adhesive sheet is used to adhere one adhesive layer to a resin foam sheet and to adhere the other adhesive layer to another member.

The adhesive constituting the adhesive layer is not particularly limited, and for example, an acrylic adhesive, a urethane adhesive, a rubber adhesive, a silicone adhesive, or the like can be used. Further, a release sheet such as release paper may be further bonded to the adhesive material.

The adhesive tape using the foam of the present invention can be used as an impact absorbing material, a sealing material, or the like incorporated in an electronic device main body. The foam may be bonded to the surface material via an adhesive layer of an adhesive tape.

[2 nd invention ]

The invention 2 of the present invention is a laminate described below.

[ laminate ]

The invention of claim 2 is a laminate comprising a skin layer and a foam layer, wherein the laminate has an Asker C hardness of 70 or less and a total light transmittance of more than 0.01%.

Fig. 1 shows a cross-sectional view of one embodiment of the laminate of the present invention. The laminate of the present invention is a laminate 10 including a skin layer 11 and a foam layer 12, wherein the skin layer 11 is laminated on one surface of the foam layer 12. When the laminate 10 is used, for example, as an interior material of an automobile, the skin layer 11 is, for example, a resin sheet, and by laminating it on the foam layer 12, a high-grade feeling can be given to a user (driver, etc.).

Further, an LED13 is provided on the other surface side of the foam layer 12, and the LED13 can display necessary information such as temperature, time, and vehicle speed by emitting light in a vehicle such as an automobile. The light emitted from the LED13 passes through the foam layer 12 and the skin layer 11, and thus, a person can perceive necessary information from the skin layer 11 side. In the drawings, the LED13 is illustrated as a layer, but may not necessarily be a layer. Although the LED13 is shown as being provided in contact with the foam layer or the like, the LED13 may be disposed at a predetermined distance from the foam layer or the like.

The laminate 10 of the present invention has a total light transmittance of at least a certain value, and thus a person can easily perceive necessary information. In addition, the laminate has a soft touch by the Asker C hardness being a certain value or less. In fig. 1, the skin layer 11 and the foam layer 12 are directly laminated, but an adhesive layer, not shown, may be provided between the skin layer 11 and the foam layer 12.

Fig. 2 shows another embodiment of the laminate of the present invention. The laminate 10 shown in fig. 2 further includes a printed layer 14. More specifically, the laminate 10 is formed by laminating the skin layer 11, the foam layer 12, and the printed layer 14 in this order, and the LED13 is provided on the surface side of the printed layer 14 opposite to the surface where the foam layer 12 is present. The printed layer 14 has a light blocking portion for blocking light emitted from the LED13 and a light transmitting portion for transmitting light, and the necessary information is confirmed from the surface layer side by the light of the LED13 by forming the light transmitting portion into a predetermined character shape or the like. Fig. 4 shows an example of a plan view of the printing layer 14, where a black portion is a light-shielding portion and a white-bottomed portion is a light-transmitting portion, and in this case, the white-bottomed portion (S) is perceived from the surface layer side.

In fig. 2, the printing layer 14 is formed on the surface of the foam layer 12 by a known method, but the form of providing the printing layer 14 is not limited to this form, and the printing layer 14 may be formed by printing on the surface of at least one of the foam layer 12 and the skin-like layer 11.

In addition, a printed film layer in which the surface of at least one of the films is printed may be used instead of the printed layer 14. The printed film layer also similarly has a light shielding portion for shielding light and a light transmitting portion for transmitting light. In other words, the laminate 10 may include at least one of the printed layer and the printed film layer, and such a laminate 10 may display information corresponding to the shape of the light-transmitting portion of the printed layer or the printed film layer.

As shown in fig. 3, the printing layer 14 may be provided between the skin layer 11 and the foam layer 12. In the laminate 10 of fig. 2 or 3, an adhesive layer, not shown, may be provided between the layers.

(Total light transmittance of the laminate)

The total light transmittance of the laminate having a skin layer and a foamed layer in the present invention is more than 0.01%. If the total light transmittance of the laminate is 0.01% or less, the light transmittance is poor, and it is difficult to recognize necessary information from the surface layer side. The total light transmittance of the laminate is preferably 0.02% or more, more preferably 0.5% or more, and further preferably 1% or more. In addition, as described above, the laminate is preferably capable of sensing necessary information from the surface layer side when light is irradiated from an LED or the like, but is preferably not capable of seeing the inside of the foam layer, the print layer, the printed film layer, or the like from the surface layer side when light is not irradiated. From such a viewpoint, the total light transmittance of the laminate is preferably 5% or less, more preferably 4% or less, and still more preferably 3% or less.

The total light transmittance of the laminate means the maximum total light transmittance of the laminate when the laminate includes at least one of the printed layer and the printed film layer. That is, the printed layer and the printed film layer include the light blocking portion that does not transmit light and the light transmitting portion that transmits light as described above, and the maximum total light transmittance of the laminate is the total light transmittance when the light transmitting portion is a measurement target.

The total light transmittance of the laminate can be adjusted by the thickness, composition, and the like of the skin layer and the foam layer, which will be described later.

(Asker C hardness of laminate)

The laminate of the present invention has an Asker C hardness of 70 or less. If the Asker C hardness of the laminate exceeds 70, it is difficult to maintain a soft touch. The Asker C hardness of the laminate is preferably 60 or less, more preferably 50 or less, and further preferably 40 or less. The lower limit of the Asker C hardness is not particularly limited, but the Asker C hardness of the laminate is preferably 5 or more, more preferably 10 or more, from the viewpoint of maintaining a certain mechanical strength. The Asker C hardness of the laminate can be adjusted by the thickness of the foam layer, the expansion ratio, and the like.

(skin layer)

The thickness of the skin layer is not particularly limited as long as the total light transmittance and Asker C hardness of the laminate are within the above ranges, and is preferably 0.2 to 1.0 mm. By setting the thickness of the skin layer to 1.0mm or less, the total light transmittance and Asker C hardness of the laminate can be easily adjusted to the above ranges. Further, by setting the thickness of the skin layer to 0.2mm or more, it becomes easy to prevent the foamed layer and the printing film layer provided as necessary from being seen through from the skin layer side. The thickness of the skin layer is more preferably 0.2 to 0.8mm, and still more preferably 0.2 to 0.7 mm.

The total light transmittance of the surface layer is preferably 0.02-30%. If the total light transmittance of the skin layer is 0.02% or more, the total light transmittance of the laminate can be easily adjusted to a certain level or more as described above. If the total light transmittance of the skin layer is 30% or less, the foamed layer and the printing film layer provided as necessary can be easily prevented from being seen through from the skin layer side. The total light transmittance of the skin layer is preferably 0.05 to 25%, more preferably 0.1 to 22%.

The skin layer may contain a pigment such as carbon black, titanium dioxide, pearl particles, and metal powder such as aluminum powder, from the viewpoint of adjusting the total light transmittance to a desired value. The skin layer preferably contains a resin sheet and a pigment described later, and the content of the pigment in the skin layer is preferably 0.01 to 3% by mass, more preferably 0.02 to 1% by mass, based on the total amount of the skin layer.

The material constituting the skin layer is not particularly limited, and examples thereof include a polypropylene sheet, a polyethylene sheet, an olefin thermoplastic elastomer (TPO) sheet, a polyvinyl chloride sheet, a resin sheet exemplified in a mixed resin sheet of polyvinyl chloride and ABS resin, and leathers such as woven fabrics, knitted fabrics, nonwoven fabrics, artificial leathers, and synthetic leathers using natural fibers and artificial fibers.

Among them, from the viewpoint of easily adjusting the total light transmittance to a desired range, a resin sheet is preferable, and among them, a polypropylene sheet and an olefin-based thermoplastic elastomer sheet are preferable, and an olefin-based thermoplastic elastomer sheet is more preferable.

From the viewpoint of improving design properties, a wrinkle pattern may be formed on the surface of the skin-like layer. Further, a surface of the epidermis layer may be provided with a skin line, a wood grain pattern, or the like using a silicone stamp having unevenness transferred from genuine leather, stone, wood, or the like.

In addition, various coatings may be applied to the surface of the skin layer from the viewpoint of preventing damage.

(foam layer)

The foam layer constituting the laminate of the present invention will be described below.

< thickness >

The thickness of the foam layer is not particularly limited as long as the total light transmittance and Asker C hardness of the laminate are within the above ranges, but is preferably 0.5 to 5 mm. By setting the thickness of the foam layer to 0.5mm or more, the feel of the laminate is easily soft. Further, the total light transmittance of the laminate can be easily adjusted to the above range by setting the thickness of the foam layer to 5mm or less. The thickness of the foam layer is preferably 0.5 to 4mm, more preferably 0.6 to 3.5 mm.

< full light transmittance >

The total light transmittance of the foam layer is preferably 10% or more. When the total light transmittance of the foam layer is 10% or more, the total light transmittance of the laminate can be easily adjusted to the above range. The total light transmittance of the foam layer is more preferably 20% or more, and still more preferably 30% or more. The higher the total light transmittance of the foam layer, the better, but usually 95% or less.

< expansion ratio >

The expansion ratio of the foam layer is not particularly limited, but is preferably 7 to 40 times. When the expansion ratio is 7 times or more, the Asker C hardness of the laminate becomes low, the touch is likely to be soft, and the total light transmittance of the laminate is also likely to be adjusted to the above range. By setting the expansion ratio of the foam layer to 40 times or less, the mechanical strength of the laminate can be set to a constant or more. The expansion ratio of the foam layer is more preferably 10 to 35 times, and still more preferably 12 to 33 times.

< degree of crosslinking (gel fraction) >)

The crosslinking degree (gel fraction) of the polyolefin foam layer is preferably 5 to 60 mass%. If the gel fraction is not less than the lower limit, sufficient crosslinking is formed in the foam layer, and therefore the mechanical strength tends to be high. Further, if the degree of crosslinking is not more than these upper limit values, a soft touch feeling is easily ensured. From such a viewpoint, the crosslinking degree is more preferably 10 to 50% by mass, and still more preferably 10 to 40% by mass. The degree of crosslinking can be measured by the measurement method described later.

< Material >

The foam layer is preferably formed of a resin, and specifically, is preferably a polyolefin foam layer or a polyurethane foam layer, and more preferably a polyolefin foam layer. The polyolefin foam layer is formed by foaming a foamable resin composition containing a polyolefin resin, and examples of the polyolefin resin include a polypropylene resin, a polyethylene resin, an ethylene-vinyl acetate copolymer, and the like, and these may be used alone or in a mixture of 2 or more.

The resin forming the foam layer is preferably only 1 type. By using only 1 type, turbidity due to blending hardly occurs, and the light transmittance of the foam layer can be improved.

The foam layer may be a single foam layer or a multilayer foam layer obtained by laminating 2 or more foams. The foams constituting the multilayer foam layer may have different physical properties such as composition, thickness, total light transmittance, expansion ratio, and crosslinking degree, and preferably satisfy the physical properties as the entire multilayer foam layer.

Polyethylene resin

As the polyethylene resin, a low density polyethylene resin (0.93 g/cm)³Hereinafter, LDPE), medium density polyEthylene resin (greater than 0.930 g/cm)³And less than 0.942g/cm³MDPE), high density polyethylene resin (0.942 g/cm)³HDPE above). Further, a suitable example of the low-density polyethylene resin is a linear low-density polyethylene resin (LLDPE).

The polyethylene resin may be a homopolymer of ethylene, or a copolymer of ethylene and a small amount of α -olefin, which contains ethylene as a main component (preferably 75% by mass or more, more preferably 90% by mass or more of the total monomers). The α -olefin is preferably an α -olefin having 3 to 12 carbon atoms, more preferably 4 to 10 carbon atoms, and specifically includes 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene, and the like. In addition, in the copolymer, these alpha-olefins can be used alone or in combination of 2 or more.

Further, the polyethylene resin may be used alone in 1 kind, or may be used in combination in 2 or more kinds.

Polypropylene resin

The polypropylene resin may be homopolypropylene which is a homopolymer of propylene, and examples thereof include a copolymer of propylene with a small amount of ethylene and an α -olefin other than propylene, the copolymer having propylene as a main component (preferably 75% by mass or more, more preferably 90% by mass or more of the total monomers).

Examples of the copolymer of propylene and an α -olefin other than ethylene and propylene include a block copolymer (block polypropylene), a random copolymer (random polypropylene), and a random block copolymer.

The α -olefin other than propylene includes α -olefins having about 4 to 10 carbon atoms such as 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, and 1-octene, and among them, ethylene is preferable from the viewpoint of moldability and heat resistance. In addition, in the copolymer, these alpha-olefins can be used alone or in combination of 2 or more.

The polypropylene resin may be used alone, or 2 or more kinds may be used in combination.

In the present invention, any of a polyethylene resin, a polypropylene resin, or a mixture thereof, which is polymerized by a polymerization catalyst such as a ziegler/natta compound, a metallocene compound, or a chromium oxide compound, can be used.

Ethylene-vinyl acetate copolymer

Examples of the ethylene-vinyl acetate copolymer used as the polyolefin resin include an ethylene-vinyl acetate copolymer containing 50 mass% or more of a structural unit derived from ethylene. Since the ethylene-vinyl acetate copolymer has high compatibility with a polyethylene resin and a polypropylene resin, the ethylene-vinyl acetate copolymer may be used in combination with 1 or more selected from the group consisting of a polyethylene resin and a polypropylene resin.

The density of the ethylene-vinyl acetate copolymer is preferably 0.92g/cm³Above, more preferably 0.93g/cm³Above, more preferably 0.94g/cm³Above, it is preferably 0.97g/cm³Hereinafter, more preferably 0.96g/cm³The following.

The polyolefin foam layer may be composed of only the above polyolefin resin, but may be a mixture of a polyolefin resin and an elastomer. Examples of the elastomer include ethylene-propylene-diene rubber (EPDM), ethylene-propylene rubber (EPM), and styrene rubber. Further, as the elastomer, a thermoplastic elastomer can be cited. Examples of the thermoplastic elastomer include olefin-based thermoplastic elastomers and styrene-based thermoplastic elastomers.

The content of the polyolefin resin in the polyolefin foam layer is preferably 50% by mass or more, more preferably 70% by mass or more, and further preferably 90% by mass or more, based on the total foam layer.

The polyurethane foam layer is formed from a polyurethane resin, and is formed by foaming a foamable resin composition containing a polyol compound and a polyisocyanate compound, as will be described later.

The content of the polyurethane resin in the polyolefin foam layer is preferably 50% by mass or more, more preferably 70% by mass or more, and further preferably 90% by mass or more, based on the total foam layer.

[ production of foam layer ]

The foamed layer in the present invention is formed by foaming the foamable resin composition. Examples of the foaming method include a method of foaming using a thermal decomposition type foaming agent, a foaming agent such as water, and the like, and a method of foaming using an inert gas such as carbon dioxide or butane gas, and the like, as described later.

(production of polyolefin foam layer)

The polyolefin foam layer is produced by, for example, foaming a foamable resin composition containing the polyolefin resin and a foaming agent. Examples of the foaming agent include a chemical foaming agent and a physical foaming agent.

< blowing agent >

The chemical foaming agent is preferably a thermal decomposition type foaming agent. As the thermal decomposition type foaming agent, an organic foaming agent or an inorganic foaming agent can be used. Examples of the organic blowing agent include azodicarbonamide, metal salts of azodicarboxylic acid (such as barium azodicarboxylate), azo compounds such as azobisisobutyronitrile, nitroso compounds such as N, N '-dinitrosopentamethylenetetramine, hydrazine derivatives such as biurea, 4' -oxybis (benzenesulfonylhydrazide) and toluenesulfonylhydrazide, and semicarbazide compounds such as toluenesulfonylsemicarbazide.

Examples of the inorganic foaming agent include ammonium carbonate, sodium carbonate, ammonium hydrogen carbonate, sodium hydrogen carbonate, ammonium nitrite, sodium borohydride, anhydrous monosodium citrate, and the like.

Among them, from the viewpoint of obtaining fine bubbles and from the viewpoint of economy and safety, the azo compound is preferable, and azodicarbonamide is more preferable.

The thermal decomposition type foaming agent can be used alone in 1, also can be combined with more than 2.

Examples of the physical blowing agent include an inert gas described below.

The content of the foaming agent in the foamable resin composition is preferably 1 to 30 parts by mass, more preferably 2 to 25 parts by mass, and still more preferably 2 to 20 parts by mass, based on 100 parts by mass of the polyolefin resin. By setting the mixing amount of the foaming agent to 1 part by mass or more, the foam layer is appropriately foamed, and a certain flexibility can be provided. Further, by setting the mixing amount of the foaming agent to 30 parts by mass or less, excessive foaming of the foam layer can be prevented, and the mechanical strength and the like of the foam layer can be improved.

< nucleating agent >

The foamable resin composition may contain a nucleating agent. The nucleating agent is not particularly limited as long as it has an effect of increasing the rate of progress of the crystal nucleus formation process. By adding a nucleating agent to a polyolefin resin such as a polyethylene resin or a polypropylene resin, the size of crystals to be generated can be reduced, and thus the transparency of the foam layer can be improved.

Examples of the nucleating agent include substances having an effect of accelerating the molecular chain orientation through the adsorption process of the molecular chains of the polymer, as an effect of accelerating the progress rate of the crystal nucleus formation process.

More specifically, there may be mentioned high-melting point polymers, organic carboxylic acids or metal salts thereof, aliphatic alcohols, dibenzylidene sorbitol or derivatives thereof, abietic acid partial metal salts, amide compounds, inorganic fine particles, organic phosphoric acid compounds or metal salts thereof, imides, quinacridones, quinones, aromatic sulfonic acid salts or metal salts thereof, saccharides, and mixtures thereof. These may be used alone in 1 kind, or may be used in combination of 2 or more kinds.

< additive >

The foamable resin composition may contain components such as a crosslinking assistant, a decomposition temperature regulator, and an antioxidant. The kinds and amounts of the crosslinking assistant, decomposition temperature adjuster, and antioxidant are the same as described above.

In addition to these, additives generally used for foams, such as a heat stabilizer, a colorant, a flame retardant, an antistatic agent, and a filler, may be blended in the foamable resin composition.

(Process for producing polyolefin foam layer)

The method for producing the polyolefin foam layer is not particularly limited, and the polyolefin foam layer can be produced by heating a foamable sheet formed from a foamable resin composition containing at least a polyolefin resin and a thermal decomposition type foaming agent to foam the thermal decomposition type foaming agent. More specifically, the production method preferably includes the following steps (1) to (3).

Step (1): process for molding foamable sheet comprising foamable resin composition containing at least polyolefin resin and thermal decomposition type foaming agent

Step (2): step of irradiating the foamable sheet with ionizing radiation to crosslink the foamable sheet

Step (3): a step of heating the crosslinked foamable sheet to foam a thermal decomposition type foaming agent to obtain a foam layer

In the step (1), a method for molding the foamable sheet is not particularly limited, and for example, the foamable resin composition may be molded by supplying the polyolefin resin, the thermal decomposition type foaming agent, the nucleating agent compounded as needed, and the additive to an extruder, melt-kneading the mixture, and extruding the foamable resin composition from the extruder in a sheet form. The foam layer can be formed by pressing or the like the foamable resin composition.

The molding temperature of the foamable resin composition (i.e., the temperature at the time of extrusion or the temperature at the time of pressing) is preferably 50 ℃ or higher and 250 ℃ or lower, and more preferably 80 ℃ or higher and 180 ℃ or lower.

As a method for crosslinking the foamable sheet in the step (2), a method of irradiating the foamable sheet with ionizing radiation such as electron beam, α -ray, β -ray, or γ -ray is used. The dose of the ionizing radiation may be adjusted so that the degree of crosslinking of the resulting foam layer is within the desired range, but is preferably 1 to 9Mrad, and more preferably 1.9 to 5 Mrad.

In the step (3), the heating temperature at which the foamable sheet is heated to foam the thermal decomposition type foaming agent may be not less than the foaming temperature of the thermal decomposition type foaming agent, but is preferably 200 to 300 ℃, and more preferably 220 to 280 ℃.

In the present production method, the foamable sheet may be stretched in either or both of MD and TD. The stretching of the foamable sheet may be performed after the foamable sheet is foamed to obtain the foamed layer, or may be performed while the foamable sheet is foamed. In addition, in the case where the foam layer is stretched after the foam sheet is foamed to obtain the foam layer, the foam layer may be stretched while maintaining the molten state during foaming without cooling the foam layer, or the foam layer may be cooled and then heated again to be in a molten or softened state, and then the foam may be stretched. The foam layer is easily thinned by stretching. The foam layer may be heated to 100 to 280 ℃, preferably 150 to 260 ℃ during stretching. In the present invention, by stretching, the cell diameter of the foam is increased along one or both of MD and TD, and the light transmittance is likely to be high.

However, in the steps (1) to (3), crosslinking may be performed by a method of mixing an organic peroxide in advance with the polyolefin resin composition and heating the foamable sheet to decompose the organic peroxide, instead of irradiating with ionizing radiation.

The method for producing the polyolefin foam layer is not limited to the method for performing the steps (1) to (3), and the polyolefin foam layer may be foamed by physical foaming.

When the foaming is performed by physical foaming, it is preferable to impregnate a physical foaming agent into a resin composition containing a polyolefin resin, a nucleating agent compounded as needed, and an additive. The impregnation with the physical foaming agent is preferably performed after the resin composition is molded into a sheet. The resin composition may be formed into a sheet, irradiated with electron beams, and impregnated with a physical foaming agent. The electron beam irradiation can be performed by the same method as in the step (2).

As the physical blowing agent, a high-pressure inert gas is preferably used. The inert gas is not particularly limited as long as it is inert to the resin composition and can be impregnated with the resin composition, and examples thereof include carbon dioxide, butane gas, nitrogen gas, and air. These gases may be used in combination. Among them, carbon dioxide gas and butane gas are preferable from the viewpoint of easily increasing the expansion ratio of the foam layer. The inert gas used in impregnation is preferably in a supercritical state or a subcritical state.

(production of polyurethane foam layer)

The polyurethane-based foam layer is obtained by foaming and curing a foamable resin composition containing a polyol compound, an isocyanate compound, and a foaming agent.

< polyol Compound >

Examples of the polyol compound include polylactone polyol, polycarbonate polyol, aromatic polyol, alicyclic polyol, aliphatic polyol, polyester polyol, and polyether polyol. The polyol compound may be a polymer polyol. The polyol compound may be used alone in 1 kind, or may be used in combination of 2 or more kinds.

Examples of the polylactone polyol include polypropiolactone diol, polycaprolactone diol, and polypentanolide diol.

The polycarbonate polyol may be a dealcoholization product of a hydroxyl group-containing compound and a carbonate compound. Examples of the hydroxyl group-containing compound include ethylene glycol, propylene glycol, butylene glycol, pentylene glycol, hexylene glycol, octylene glycol, nonanediol, and the like. Examples of the carbonate compound include diethyl carbonate and dipropyl carbonate.

Examples of the aromatic polyol include bisphenol a, bisphenol F, phenol novolac, cresol novolac, and the like.

Examples of the alicyclic polyol include cyclohexanediol, methylcyclohexanediol, isophorone diol, dicyclohexylmethane diol, and dimethyldicyclohexylmethane diol.

Examples of the aliphatic polyhydric alcohol include ethylene glycol, propylene glycol, butylene glycol, pentylene glycol, hexylene glycol, and the like.

Examples of the polyester polyol include dehydration condensates of polybasic acids and polyhydric alcohols, ring-opening polymers of lactones, and condensates of hydroxycarboxylic acids and polyhydric alcohols. Examples of the polybasic acid include adipic acid, azelaic acid, sebacic acid, terephthalic acid, isophthalic acid, succinic acid, and the like. Examples of the polyhydric alcohol include bisphenol a, ethylene glycol, propylene glycol, butylene glycol, diethylene glycol, hexylene glycol, neopentyl glycol, and the like. Examples of the lactone include epsilon-caprolactone and alpha-methyl-epsilon-caprolactone. Examples of the hydroxycarboxylic acid include castor oil and a reaction product of castor oil and ethylene glycol.

Examples of the polyether polyol include ring-opened polymers of an active hydrogen compound having 2 or more active hydrogen atoms and an alkylene oxide (alkylene oxide). Examples of the alkylene oxide include ethylene oxide (ethylene oxide), propylene oxide (propylene oxide), and tetrahydrofuran. The molecular weight of the above active hydrogen compound is preferably low. Examples of the active hydrogen compound include diol compounds such as bisphenol a, ethylene glycol, propylene glycol, butylene glycol, and 1, 6-hexanediol, triol compounds such as glycerin and trimethylolpropane, and amine compounds such as ethylenediamine and butanediamine.

Examples of the polymer polyol include graft polymers obtained by graft polymerization of an unsaturated organic compound and a polyol compound, polybutadiene polyols, polyol-modified polyols, and hydrogenated products thereof.

In the graft polymer, examples of the polyol compound include aromatic polyols, alicyclic polyols, aliphatic polyols, polyester polyols, polyether polyols, and the like. Examples of the unsaturated organic compound include acrylonitrile, styrene, and methyl (meth) acrylate.

Examples of the modified polyol of the polyol include a reaction modified product of a polyol and an alkylene oxide. Examples of the polyhydric alcohol include 3-membered alcohols such as glycerin and trimethylolpropane, 4-to 9-membered alcohols such as pentaerythritol, sorbitol, mannitol, sorbitan, diglycerol, dipentaerythritol, sucrose, glucose, mannose, fructose, methylglucoside and derivatives thereof, phenol, phloroglucinol, cresol and pyrogallol, catechol, hydroquinone, bisphenol a, bisphenol F, bisphenol S, 1-hydroxynaphthalene, 1,3,6, 8-tetrahydroxynaphthalene, anthralin, phenol compounds such as 1,4,5, 8-tetrahydroxyanthracene and 1-hydroxypyrene, polybutadiene polyol, castor oil polyol, (co) polymers of hydroxyalkyl (meth) acrylates, polyfunctional (e.g., having a functional group of 2 or more and 100 or less) polyols such as polyvinyl alcohol, and condensates of phenol and formaldehyde (novolak). Examples of the alkylene oxide include alkylene oxides having 2 to 6 carbon atoms. Specific examples of the alkylene oxide include ethylene oxide, 1,2-propylene oxide (1,2-propylene oxide), 1,3-propylene oxide (1,3-propylene oxide), 1,2-butylene oxide (1,2-butylene oxide), and 1,4-butylene oxide (1,4-butylene oxide). From the viewpoint of improving the properties and reactivity, the alkylene oxide is preferably 1,2-propylene oxide, ethylene oxide, or 1,2-butylene oxide, and more preferably 1,2-propylene oxide or ethylene oxide. The alkylene oxide may be used alone in 1 kind or in combination of 2 or more kinds.

< polyisocyanate Compound >

Examples of the polyisocyanate compound include aromatic polyisocyanate, alicyclic polyisocyanate, and aliphatic polyisocyanate.

Examples of the aromatic polyisocyanate include phenylene diisocyanate, toluene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, dimethyldiphenylmethane diisocyanate, triphenylmethane triisocyanate, naphthalene diisocyanate, and Polymethylene polyphenyl polyisocyanate (Polymethylene polyphenyl polyisocyanate).

Examples of the alicyclic polyisocyanate include cyclohexyl diisocyanate, methylcyclohexyl diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, and dimethyldicyclohexylmethane diisocyanate.

Examples of the aliphatic polyisocyanate include methylene diisocyanate, ethylene diisocyanate, propylene diisocyanate, 1, 4-tetramethylene diisocyanate, and 1, 6-hexamethylene diisocyanate.

The content of the isocyanate compound is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, preferably 35 parts by mass or less, and more preferably 30 parts by mass or less, relative to 100 parts by mass of the polyol compound.

< blowing agent >

Examples of the blowing agent used for producing the polyurethane foam layer include water and an organic halogen compound.

Examples of the organic halogen compound include an organic chlorine compound and an organic fluorine compound.

Examples of the organic chlorine compound include dichloroethane, propyl chloride, isopropyl chloride, butyl chloride, isobutyl chloride, pentyl chloride, and isopentyl chloride.

Examples of the organic fluorine compound include difluoromethane (HFC32), 1,1,1,2, 2-pentafluoroethane (HFC125), 1,1, 1-trifluoroethane (HFC143a), 1,1,2, 2-tetrafluoroethane (HFC134), 1,1,1, 2-tetrafluoroethane (HFC134a), 1, 1-difluoroethane (HFC152a), 1,1,1,2,3,3, 3-heptafluoropropane (HFC227ea), 1,1,1,3, 3-pentafluoropropane (HFC245fa), 1,1,1,3, 3-pentafluorobutane (HFC365mfc), and 1,1,1,2,2,3,4,5,5, 5-decafluoropentane (HFC4310 mee).

The content of the blowing agent may be appropriately adjusted depending on the type of the blowing agent. When water is used as the blowing agent, the blowing agent may be used in an amount of preferably 1 to 10 parts by mass, more preferably 1 to 5 parts by mass, based on 100 parts by mass of the total of the polyol compound and the polyisocyanate compound. When the organic halogen compound is used as the blowing agent, the blowing agent may be used in an amount of preferably 1 to 10 parts by mass, more preferably 1 to 5 parts by mass, based on 100 parts by mass of the total of the polyol compound and the polyisocyanate compound. When water and an organic halogen compound are used as the blowing agent, the mixing amounts are preferably adjusted so as to fall within the above ranges.

< catalyst >

The foamable resin composition may contain a catalyst. Examples of the catalyst include a urethane-forming catalyst and a trimerization catalyst. Examples of the urethane-forming catalyst include amine catalysts. Examples of the trimerization catalyst include aromatic compounds, alkali metal salts of carboxylic acids, quaternary ammonium salts of carboxylic acids, and quaternary ammonium salt/ethylene glycol mixtures.

The content (total amount) of the catalyst is preferably 0.05 to 1 part by mass based on 100 parts by mass of the total of the polyol compound and the polyisocyanate compound.

The foamable resin composition for producing a polyurethane foam layer may contain, in addition to the above, a decomposition temperature regulator, an antioxidant, a heat stabilizer, a colorant, a flame retardant, an antistatic agent, a filler, and the like.

The polyurethane foam layer can be obtained by foaming and curing the foamable resin composition. For example, the foamable resin composition may be injected into a mold, heated, foamed, and cured. The thickness of the foamed layer can be adjusted by, for example, slicing the obtained cured product into a desired thickness after foaming and curing the foamable resin composition.

(printing layer, printing film layer)

The laminate of the present invention may include at least one of a printed layer and a printed film layer as described above. Thus, the shape corresponding to the printed pattern can be perceived from the surface layer side by light. The printing layer can be formed by printing on one surface of the foam layer, for example. The printed film layer is obtained by forming a printed layer on a base film such as a polyester film such as a polyolefin film or a PET film. As a method for forming the print layer, a known method such as an inkjet method can be suitably used. The thickness of the printing layer is preferably 1 to 25 μm, and more preferably 2 to 10 μm. The thickness of the printing film layer is preferably 4 to 50 μm, and more preferably 12 to 25 μm.

In addition, even when the laminate is not provided with the print layer and the print film layer, the character information can be recognized from the surface layer side by irradiating light irradiated from the foam layer side so that a certain character information is displayed.

(production of a laminate)

The laminate of the present invention can be produced by laminating a foam layer, a skin layer, and a printed film layer provided as needed, for example. The specific layer structure is as described above. The foam layer may be a foam layer having a printed layer formed thereon. The laminate may be formed by heat lamination or by bonding the layers to each other with an adhesive.

(light display means)

The laminate of the present invention can be suitably used as a light display member. That is, the light display member including the laminate is preferable. The structure of the light display member is not particularly limited, but the light display member preferably includes a laminate and an information display member, and may be, for example, a light display member in which a skin layer, a foam layer, and an information display member are laminated in this order. Examples of the information display member include a display, and an LED array. The arranged LEDs are materials in which a plurality of LEDs are arranged in a specific shape in order to display specific information.

The light display member may have a sensor element, and for example, the information display section may be a display having a sensor element such as a touch panel.

The light display member is suitably used for a vehicle such as an automobile, and is preferably used for displaying necessary information such as temperature, time, vehicle speed, danger, safety, and advance notice, or for design and illumination.

Examples

The present invention will be described in further detail with reference to examples, but the present invention is not limited to these examples.

[ invention 1: crosslinked polyolefin resin foam

[ measurement method ]

The measurement methods of the physical properties in the present specification are as follows.

< apparent Density >

The apparent density of the foam was measured in accordance with JIS K7222: 2005.

< expansion ratio >

The expansion ratio is calculated by dividing the density of the foamable sheet before foaming by the density of the foam after foaming (apparent density).

< degree of crosslinking (gel fraction) >)

A test piece of about 100mg was sampled from the foam sheet, and the weight A (mg) of the test piece was precisely measured. Next, the test piece was subjected to 30cm xylene at 120 ℃ C³Soaking for 24 hr, and sieving with 200 mesh metal netThe insoluble matter on the wire gauze was collected by filtration, vacuum-dried, and the weight B (mg) of the insoluble matter was precisely measured. From the obtained value, the degree of crosslinking (% by mass) was calculated by the following formula.

Degree of crosslinking (% by mass) — (B/a) × 100

< full light transmittance >

The total light transmittance of the foam was measured using a haze meter in accordance with ASTM D1003 for foams adjusted to the thickness shown in table 1.

< evaluation of recognizability >

The evaluation of the visibility was performed as follows.

First, a polyvinyl chloride sheet (thickness: 0.6mm) to which an ABS resin was added was prepared as a skin material. The characters "abc" were written on the surface of the polyvinyl chloride sheet so that the size of 1 character became 12 pounds (font).

Next, the 2-layer laminate of the crosslinked polyolefin resin foam produced in examples and comparative examples and the skin material was placed in a press mold (depth 10mm, mold 8mm, radius of curvature of concave portion 5mm) maintained at 160 ℃ at a rate of 0.2kg/cm²Is pressed for 25 seconds to obtain a molded article.

The molded article was LED-lit from the crosslinked polyolefin resin foam body side toward the skin material side, and it was judged whether or not characters could be recognized from a place at a distance of 1 m. The case where the character can be recognized is referred to as "a", and the case where the character cannot be recognized is referred to as "B". The results are shown in table 1.

< use of raw materials >

The materials used in the examples and comparative examples are as follows.

[ polyolefin resin ]

PP: "ノーブレン AD 571" manufactured by Sumitomo chemical Co., Ltd. (density: 0.900 g/cm)³)

LLDPE: "ニポロン -Z ZF 231B" manufactured by DONG ソー K.K. (density: 0.917 g/cm)³)

LDPE (Low-Density polyethylene): yu Zhi Wan- ポリエチレン Kabushiki Kaisha "UBE ポリエチレン F522N" (density: 0.922 g/cm)³)

EVA (1): "ウルトラセン 636" manufactured by "Dow ソー Inc. (density: 0.941 g/cm)³)

EVA (2): "ウルトラセン 710" (density: 0.949 g/cm) of "DONG ソー K.K.)³)

[ elastomer ]

HSBR (high speed bulk blending ratio): JSR company "DYNARON 1320P"

SEBC (styrene-ethylene-butadiene-styrene copolymer): JSR company "DYNARON 4600P"

Nucleating agent: sugar series, Beijing インキ Kagaku (Chinese character of imperial barberry) 'NAT-95'

Foaming agent: ronghe chemical Co., Ltd, "AC # R" (azodicarbonamide)

Crosslinking assistant agent: kyoeisha chemical "ライトエステル 1.9.9-ND" (1, 9-nonanediol dimethacrylate)

Antioxidant: BASF ジャパン "イルガノックス 1010"

Decomposition temperature adjuster (1): made by Sakai chemical industry Zinc oxide

Decomposition temperature adjuster (2): sakai chemical industry "SZ-2000" Zinc stearate

Example 1

A foamable sheet having a thickness of 0.3mm was obtained by melt-kneading 80 parts by mass of a polypropylene resin (PP), 19 parts by mass of a polyethylene resin (LLDPE), 2 parts by mass of a nucleating agent, 8 parts by mass of a foaming agent, 3 parts by mass of a crosslinking assistant, and 0.8 part by mass of an antioxidant, followed by pressing. The resultant foamable sheet was irradiated with 3Mrad of electron beam at an acceleration voltage of 500keV on both sides thereof, to crosslink the foamable sheet. The crosslinked expandable sheet was then expanded by heating to 250 ℃ to obtain an apparent density of 0.09g/cm³And a foam sheet having a thickness of 1.0 mm.

The evaluation results of the obtained foam are shown in table 1.

Examples 2 to 17 and comparative examples 1 to 6

The preparation of the polyolefin resin composition was carried out in the same manner as in example 1, except that the compounding of the polyolefin resin composition was changed as shown in table 1 and the electron beam irradiation amount was adjusted so as to obtain the crosslinking degree in table 1. The evaluation results of the obtained foam are shown in table 1.

[ Table 1]

From the above results, it is clear that the polyolefin resin foam of the present invention has excellent light transmittance when the thickness is 0.3mm to 5.0 mm.

[ invention 2: laminate ]

The evaluation method is as follows.

< Asker C hardness >

The measurement was performed by using an Asker rubber durometer type C (manufactured by Polymer Meter Co., Ltd.) with the stylus of the durometer in contact with the skin layer of the laminate. The measurement was carried out at 25 ℃.

< expansion ratio >

The expansion ratio is calculated by obtaining the density (apparent density) of the foam layer and calculating the reciprocal of the density. Apparent density was measured according to JIS K7222: 2005.

< gel fraction (degree of crosslinking) >

A test piece of about 100mg was sampled from the foam layer, and the weight A (mg) of the test piece was precisely measured. Next, the test piece was subjected to 30cm xylene at 120 ℃ C³After being immersed in the solvent, the resulting solution was left to stand for 24 hours, filtered through a 200-mesh wire gauze to collect insoluble matter on the wire gauze, vacuum-dried, and the weight B (mg) of the insoluble matter was precisely measured. From the obtained value, the degree of crosslinking (% by mass) was calculated by the following formula.

Degree of crosslinking (% by mass) — (B/a) × 100

< full light transmittance >

The total light transmittance was measured according to ASTM D1003 using a haze meter.

< evaluation of feeling of penetration >

The inner part was visually observed from the skin layer side, and evaluated by the degree of visibility of the foam layer.

A. the foam layer was completely invisible

B.the foam layer can be seen partially

C. the entirety of the foam layer can be seen

< raw Material for foam layer >

The materials used in the examples and comparative examples are as follows.

[ polyolefin resin ]

Polypropylene resin (PP): "ノーブレン AD 571" manufactured by Sumitomo chemical Co., Ltd. (density: 0.900 g/cm)³)

Polyethylene resin (LLDPE, linear low-density polyethylene): "ニポロン -Z ZF 231B" manufactured by DONG ソー K.K. (density: 0.917 g/cm)³)

Polyethylene resin (LDPE (1), low density polyethylene): yu Zhi Wan- ポリエチレン Kabushiki Kaisha "UBE ポリエチレン F522N" (density: 0.922 g/cm)³)

Polyethylene resin (LDPE (2), low density polyethylene): sdabic "1905 UO" (density: 0.920 g/cm)³)

EVA: "ウルトラセン 636" manufactured by "Dow ソー Inc. (density: 0.941 g/cm)³)

[ polyurethane resin ]

Polyol compound (1): sanyo chemical GP3000

Polyol compound (2): ethylene glycol

Polyisocyanate compound (b): japanese ポリウレタンコロネート T-80

[ foaming agent ]

Azodicarbonamide (1): ronghe chemical Co., Ltd, "AC # R" (azodicarbonamide)

Azodicarbonamide (2): otsuka chemical corporation "SO-L" (azodicarbonamide)

Water (W)

Crosslinking assistant agent: kyoeisha chemical "ライトエステル 1.9.9-ND" (1, 9-nonanediol dimethacrylate)

Antioxidant: BASF ジャパン "イルガノックス 1010"

Decomposition temperature regulator: sakai chemical "acidified mutant type II"

Catalyst: formation of Ridong into "U-28"

Foam stabilizer: モメンティブ L-626 "

< epidermal layer >

The skin layers used in the examples and comparative examples each contain a pigment masterbatch (PEX 99901, manufactured by imperial beijing インキ, imperial, or the like) containing 40 wt% of a pigment (carbon black), and an olefin-based thermoplastic elastomer (TPO). The blending amount of the pigment masterbatch and the content of the pigment were adjusted as shown in table 2. The pigment contents shown in Table 2 are based on the total amount of the skin layer.

(example 18)

A foamable sheet was obtained by melt-kneading 85 parts by mass of a polypropylene resin (PP), 15 parts by mass of a polyethylene resin (LLDPE), 6 parts by mass of a foaming agent, 3 parts by mass of a crosslinking assistant, and 0.5 part by mass of an antioxidant, and then pressing the mixture. The resultant foamable sheet was irradiated with 2Mrad of electron beam at an acceleration voltage of 800keV on both sides thereof, to crosslink the foamable sheet. The crosslinked expandable sheet was then heated to 250 ℃ and expanded to obtain a foam layer having an expansion ratio of 13 times and a thickness of 0.6 mm.

The resulting foam layer and skin layer were laminated by means of an adhesive sheet (product of hydration, "3803H") having a thickness of 0.03mm to obtain a laminate.

The obtained laminate was subjected to various evaluations, and the results are shown in table 2.

(examples 19 to 24, 28 and 29 and comparative examples 8 to 10)

A laminate was obtained in the same manner as in example 18, except that the composition of the foamable resin composition and the type of the skin layer were changed as shown in table 2, and the irradiation conditions of the electron beam were appropriately changed so that the crosslinking degree was changed as shown in table 2.

The obtained laminate was subjected to each evaluation, and the results are shown in table 2.

(example 25)

100 parts by mass of a polyethylene resin (LDPE (2)) and 0.5 part by mass of an antioxidant were fed into a single-screw extruder, and supercritical carbon dioxide was injected at 7MPa and mixed. Then, the temperature was decreased as the extrusion proceeds in the direction of the tip of the single-screw extruder, and the temperature at the die outlet was set to 110 ℃.

The both surfaces of the obtained sheet-like foam were irradiated with an electron beam of 1.9Mrad at an accelerating voltage of 500keV to crosslink the foam, thereby obtaining a foam layer.

The resulting foam layer and skin layer were laminated by means of an adhesive sheet (product of hydration, "3803H") having a thickness of 0.03mm to obtain a laminate.

Comparative examples 7 and 11

A laminate was obtained in the same manner as in example 25, except that the irradiation conditions of the electron beam were changed so that the degree of crosslinking of the foam layer was as shown in table 2, and the type of the skin layer was changed as shown in table 2.

The obtained laminate was subjected to various evaluations, and the results are shown in table 2.

(example 26)

A foamable resin composition was prepared by mixing 100 parts by mass of a polyol compound (1) and 5 parts by mass of a polyol compound (2), 20 parts by mass of a polyisocyanate compound, 0.1 part by mass of U-28 as a catalyst, 2 parts by mass of L626 as a foam stabilizer, and 2 parts by mass of water as a foaming agent. The foamable composition was injected into a mold (150 mm. times.150 mm. times.50 mm), and then heated in an oven at 80 ℃ for 60 minutes to foam and cure the composition, thereby obtaining a cured product. This solidified body was sliced to obtain a foamed layer having a thickness of 3 mm.

The resulting foam layer and skin layer were laminated with a 0.03mm adhesive sheet (product of hydration, "3803H") to obtain a laminate.

The obtained laminate was subjected to various evaluations, and the results are shown in table 2.

(example 27)

A laminate was obtained in the same manner as in example 26, except that the composition of the foamable resin composition, the type of the skin layer, and the like were changed as shown in table 2.

The obtained laminate was subjected to various evaluations, and the results are shown in table 2.

[ Table 2]

The laminate of the present invention has a soft touch, a high total light transmittance, and an excellent light transmittance because the Asker C hardness is a certain value or less, and thus it is known that necessary information can be easily recognized from the surface layer side.

Description of the symbols

10 laminated body

11 epidermis layer

12 foam layer

13 LED

And 14, printing the layer.