阅读说明：本技术 分散有纤维素纤维的树脂复合材料、成型体以及复合构件 (Cellulose fiber-dispersed resin composite material, molded article, and composite member ) 是由 原英和 广石治郎 金宰庆 太附雅巳 铃木俊宏 池内正人 坂户二郎 于 2019-12-04 设计创作，主要内容包括：一种分散有纤维素纤维的树脂复合材料、使用了该复合材料的成型体、以及使用了该成型体的复合构件,该分散有纤维素纤维的树脂复合材料是将纤维素纤维分散于树脂中而成的,上述纤维素纤维的含量为1质量％以上且小于70质量％,将在下述测定条件下测定的上述纤维素纤维的长度加权平均纤维长设为LL、将数均纤维长设为LN时,LL和LN满足下述[式1]。<测定条件>对于将上述分散有纤维素纤维的树脂复合材料浸渍到可溶解该复合材料中的树脂的溶剂中而得到的溶解残渣,通过基于ISO 160652001中规定的纸浆-光学自动分析法的纤维长测定方法求出LL和LN。[式1]1.1<(LL/LN)<1.5。(A cellulose fiber-dispersed resin composite material, a molded article using the composite material, and a composite member using the molded article, wherein the cellulose fiber-dispersed resin composite material is obtained by dispersing cellulose fibers in a resin, the content of the cellulose fibers is 1 mass% or more and less than 70 mass%, and LL and LN satisfy the following [ formula 1] when the length-weighted average fiber length of the cellulose fibers measured under the following measurement conditions is LL and the number-average fiber length is LN. < measurement conditions > LL and LN were determined by a fiber length measurement method based on the pulp-optical automatic analysis method specified in ISO 160652001 for a dissolution residue obtained by immersing the above resin composite material in which cellulose fibers are dispersed in a solvent in which the resin in the composite material is soluble. [ formula 1]1.1< (LL/LN) < 1.5.)

1. A cellulose fiber-dispersed resin composite material comprising cellulose fibers dispersed in a resin, wherein,

the content of the cellulose fiber is 1 mass% or more and less than 70 mass%,

when the length-weighted average fiber length of the cellulose fiber measured under the following measurement conditions is LL and the number-average fiber length is LN, LL and LN satisfy the following [ formula 1],

< measurement conditions >

The dissolution residue obtained by immersing the resin composite material in which the cellulose fibers are dispersed in a solvent capable of dissolving the resin in the composite material is determined by a fiber length measuring method based on the pulp-optical automatic analysis method specified in ISO 160652001 to obtain LL and LN,

[ formula 1]1.1< (LL/LN) < 1.5.

2. The cellulose fiber-dispersed resin composite according to claim 1, wherein the LL and LN satisfy the following [ formula 1-2],

[ formula 1-2]1.1< (LL/LN) < 1.4.

3. The cellulose fiber-dispersed resin composite according to claim 1 or 2, wherein LW and LN satisfy the following [ formula 2] when LW is a weight-weighted average fiber length of the cellulose fibers measured under the following measurement conditions,

< measurement conditions >

LW is determined by a fiber length measuring method based on a pulp-optical automatic analysis method specified in ISO 160652001 for a dissolution residue obtained by immersing the resin composite material in which the cellulose fibers are dispersed in a solvent in which the resin in the composite material is soluble,

[ formula 2]1.1< (LW/LN) < 3.0.

4. The cellulose fiber-dispersed resin composite according to any one of claims 1 to 3, wherein the cellulose fiber has a length-weighted average fiber length of 0.3mm or more.

5. The cellulose fiber-dispersed resin composite according to any one of claims 1 to 4, wherein the content of the cellulose fibers in the cellulose fiber-dispersed resin composite is determined by a measurement method in which the content of the cellulose fibers in the cellulose fiber-dispersed resin composite is 5% by mass or more and less than 50% by mass,

< measuring method >

Thermogravimetric analysis TGA of a sample of the resin composite material in which cellulose fibers are dispersed was performed under a nitrogen atmosphere at a temperature rise rate of +10 ℃/min, and the content of cellulose fibers was calculated from the following [ formula 1],

[ formula I ] (cellulose fiber content [% by mass) ] x 100/(mass of sample before thermogravimetric analysis [ mg ]).

6. The cellulose fiber-dispersed resin composite according to any one of claims 1 to 5, wherein the resin comprises 1 or 2 or more of a polyolefin resin, an acrylonitrile-butadiene-styrene copolymer resin, an acrylonitrile-styrene copolymer resin, a polyamide resin, a polyvinyl chloride resin, a polyethylene terephthalate resin, a polybutylene terephthalate resin, a polystyrene resin, a 3-hydroxybutyrate-co-3-hydroxyhexanoate polymer resin, a polybutylene succinate resin, and a polylactic acid resin.

7. The cellulose fiber-dispersed resin composite according to any one of claims 1 to 6, wherein the resin comprises a polyolefin resin, and a dissolution residue obtained by immersion in a solvent that can dissolve the resin in the composite under the measurement conditions of LL, LN, and LW is a hot xylene dissolution residue.

8. The cellulose fiber-dispersed resin composite according to any one of claims 1 to 7, wherein the cellulose fiber-dispersed resin composite is obtained by dispersing aluminum in the resin.

9. A cellulose fiber-dispersed resin composite according to claim 8, wherein at least a part of the aluminum has a bent structure.

10. The cellulose fiber-dispersed resin composite according to claim 8 or 9, wherein the cellulose fiber-dispersed resin composite exhibits a peel strength of 1.0N/10mm or more from an aluminum foil when thermally bonded to the aluminum foil.

11. The cellulose fiber-dispersed resin composite according to any one of claims 1 to 10, wherein the cellulose fiber-dispersed resin composite contains at least one compound selected from the group consisting of a metal salt of an organic acid, and silicone.

12. The cellulose fiber-dispersed resin composite according to any one of claims 1 to 11, wherein the cellulose fiber-dispersed resin composite is obtained by dispersing resin particles made of a resin different from the resin in the resin.

13. A cellulosic fibre dispersed resin composite according to any one of claims 1 to 12 wherein at least part of the resin and/or at least part of the cellulosic fibres are derived from recycled material.

14. A molded article comprising the resin composite material in which cellulose fibers are dispersed according to any one of claims 1 to 13.

15. The molded body according to claim 14, wherein the molded body is a tubular body or a multi-segment body obtained by dividing a tubular body.

16. A composite member comprising the molded article according to claim 14 or 15 and another material in combination.

17. A cellulose fiber-dispersed resin composite material according to any one of claims 1 to 13, which is used for joining to a metal to form a composite.

Technical Field

The present invention relates to a resin composite material in which cellulose fibers are dispersed, a molded article, and a composite member.

Background

In order to improve the mechanical properties of resin products, fiber-reinforced resins are known in which reinforcing fibers such as glass fibers, carbon fibers, and cellulose fibers are mixed with a resin.

When glass fibers are used as reinforcing fibers, glass fibers, which are nonflammable inorganic substances, remain in large amounts as ash even when burned by heat recovery or the like, and there is a problem in the energy recovery rate in recycling. In addition, glass fibers have a higher specific gravity than resin, and also have a problem of an increase in weight of fiber-reinforced resin. Further, since glass fibers have a large capacity as compared with resins, it takes time to cool and solidify the glass fibers after molding, and there is a limit to improve the production efficiency of resin products.

In addition, the above problems can be solved by using carbon fibers instead of glass fibers as the reinforcing fibers. However, carbon fibers are expensive, and when they are used as reinforcing fibers, there is a problem that the cost of resin products increases.

On the other hand, cellulose fibers are light in weight, have less combustion residue in heat recovery and the like, and are relatively low in cost, and therefore, are advantageous in terms of weight reduction, recyclability, cost and the like. Techniques related to fiber-reinforced resins using cellulose fibers have been reported. For example, patent document 1 describes the following: adhering wax to the waste paper pulp fiber in a dry state subjected to the opening treatment, and kneading the obtained composite material with a matrix resin to obtain a composite material; in addition, the fiber length weighted average fiber length of the opened waste paper pulp fiber is 0.1-5.0 mm.

Further, patent document 2 discloses a paper-containing resin composition containing a pulverized product of paper containing 50 mass% or more of bleached chemical pulp of conifer and a resin, and having a melt flow rate of 2.0 to 7.0g/10 min. Patent document 2 describes that the average fiber length of the pulp is 0.3 to 2 mm.

Patent document 3 describes the following: mixing the crushed waste paper with a polyolefin elastomer, mixing a specific amount of thermoplastic resin granules with the obtained waste paper granules, heating and mixing, and granulating to obtain granules; the waste paper is crushed to an average thickness of 0.01 to 0.1mm and an average length of 0.1 to 2.5 mm.

Patent document 4 discloses a resin composition containing specific amounts of a thermoplastic resin, cellulose fibers, a water-soluble resin, and a modified olefin resin, and describes that cellulose fibers having an aspect ratio of 5 or more are used.

Patent document 5 describes the following: paper pellets obtained by absorbing water in pellets of a pulverized product of film-laminated paper are mixed with a polypropylene resin and a maleic anhydride-modified polypropylene resin, fed to a twin-screw extruder, and kneaded to obtain pellets of a thermoplastic resin composition containing paper, and the pellets are injection-molded.

Patent document 6 describes the following: the polyolefin resin, the powdery cellulose, and water are kneaded by a twin-screw extruder, whereby the area of the cellulose aggregates can be reduced.

Documents of the prior art

Patent document

Patent document 1: international publication No. 2012/070616

Patent document 2: japanese patent laid-open No. 2007 and 45863

Patent document 3: japanese patent No. 3007880

Patent document 4: japanese laid-open patent publication No. 2012-236906

Patent document 5: japanese patent laid-open publication No. 2007-260941

Patent document 6: international publication No. 2018/180469

Disclosure of Invention

Problems to be solved by the invention

In the case of a cellulose fiber-reinforced resin, the affinity of the interface between the hydrophobic resin and the hydrophilic cellulose fiber is insufficient, and the reinforcing effect of the cellulose fiber may not be sufficiently exhibited. In order to solve this problem, it is known to improve the affinity between the resin and the cellulose fiber by compounding an acid-modified resin or the like.

On the other hand, regarding the characteristics of cellulose fibers that affect the reinforcing effect of a resin, as described in patent documents 1 to 4, the size and shape of the cellulose fibers used have been studied. Further, as described in patent documents 5 and 6, the dispersion state of cellulose fibers and aggregates of cellulose fibers by kneading with a twin-screw extruder to which water is added have been studied.

However, in the above patent documents, the size and shape of the cellulose fiber are only mentioned before mixing with the resin, or the dispersion state of the cellulose fiber or the aggregate of the cellulose, but the size and shape of the cellulose fiber after kneading and dispersing in the resin and the distribution state of the fiber length are not accurately known.

The present invention addresses the problem of providing a composite material having excellent mechanical properties such as tensile strength and flexural strength, which is obtained by dispersing cellulose fibers in a resin, a molded article using the composite material, and a composite member using the molded article.

Means for solving the problems

The present inventors have studied the relationship between the improvement of mechanical properties of a resin composite material in which cellulose fibers are dispersed and the fiber length of the cellulose fibers. Specifically, the study was performed based on the following predictions: the difference in the distribution of the fiber length is present between the cellulose fiber before being mixed with the resin and the cellulose fiber in a state of being kneaded with the resin; the distribution of the fiber length varies depending on the kneading conditions, and the state of the distribution of the fiber length after kneading affects the mechanical properties of the obtained composite material.

That is, the present inventors have immersed a composite material obtained by kneading a resin and cellulose fibers in a solvent soluble to the resin to dissolve the resin, taken out the cellulose fibers, and analyzed the fiber length distribution in detail, and as a result, have found that the fiber length distribution of the cellulose fibers in the composite material is different between before and after kneading, and that the mechanical properties of the obtained composite material can be improved by adjusting the fiber length distribution of the cellulose fibers in the composite material to a specific distribution state.

The present invention has been completed based on further repeated studies on these technical ideas.

The above object of the present invention can be achieved by the following means.

[1]

A cellulose fiber-dispersed resin composite material comprising cellulose fibers dispersed in a resin, wherein,

the content of the cellulose fiber is 1 mass% or more and less than 70 mass%,

when the length-weighted average fiber length of the cellulose fibers measured under the following measurement conditions is LL and the number-average fiber length is LN, LL and LN satisfy the following [ formula 1 ].

< measurement conditions >

The dissolution residue obtained by immersing the resin composite material in which the cellulose fibers are dispersed in a solvent capable of dissolving the resin in the composite material was determined by a fiber length measuring method based on the pulp-optical automatic analysis method specified in ISO 160652001 to obtain LL and LN.

[ formula 1]1.1< (LL/LN) <1.5

[2]

The cellulose fiber-dispersed resin composite according to [1], wherein the LL and LN satisfy the following [ formula 1-2 ].

[ formula 1-2]1.1< (LL/LN) <1.4

[3]

The cellulose fiber-dispersed resin composite according to [1] or [2], wherein LW and LN satisfy the following [ formula 2] when LW is a weight-weighted average fiber length of the cellulose fibers measured under the following measurement conditions.

< measurement conditions >

The LW was determined by a fiber length measurement method based on the pulp-optical automatic analysis method specified in ISO 160652001 for the dissolution residue obtained by immersing the resin composite material in which the cellulose fibers are dispersed in a solvent in which the resin in the composite material is soluble.

[ formula 2]1.1< (LW/LN) <3.0

[4]

The resin composite material having cellulose fibers dispersed therein according to any one of [1] to [3], wherein the cellulose fibers have a length-weighted average fiber length of 0.3mm or more.

[5]

The cellulose fiber-dispersed resin composite according to any one of [1] to [4], wherein the content of the cellulose fibers in the cellulose fiber-dispersed resin composite is determined by a measurement method in which the content of the cellulose fibers in the cellulose fiber-dispersed resin composite is 5% by mass or more and less than 50% by mass.

< measuring method >

A sample of the resin composite material in which the cellulose fiber was dispersed was subjected to thermogravimetric analysis (TGA) at a temperature increase rate of +10 ℃/min under a nitrogen atmosphere, and the content of the cellulose fiber was calculated from the following [ formula 1 ].

[ formula I ] (cellulose fiber content [% by mass) ] x 100/(mass [ mg ] of the sample before thermogravimetric analysis) (mass decrease [ mg ] of the sample between 200 and 380 ℃)

[6]

The cellulose fiber-dispersed resin composite according to any one of [1] to [5], wherein the resin contains 1 or 2 or more of a polyolefin resin, an acrylonitrile-butadiene-styrene copolymer resin, an acrylonitrile-styrene copolymer resin, a polyamide resin, a polyvinyl chloride resin, a polyethylene terephthalate resin, a polybutylene terephthalate resin, a polystyrene resin, a 3-hydroxybutyrate-co-3-hydroxyhexanoate polymer resin, a polybutylene succinate resin, and a polylactic acid resin.

[7]

The cellulose fiber-dispersed resin composite according to any one of [1] to [6], wherein the resin contains a polyolefin resin, and a dissolution residue obtained by immersing the resin in a solvent capable of dissolving the resin in the composite under the measurement conditions of LL, LN, and LW is a hot xylene dissolution residue.

[8]

The cellulose fiber-dispersed resin composite according to any one of [1] to [7], wherein the cellulose fiber-dispersed resin composite is obtained by dispersing aluminum in the resin.

[9]

The cellulose fiber-dispersed resin composite according to [8], wherein at least a part of the aluminum has a bent structure.

[10]

The cellulose fiber-dispersed resin composite according to [8] or [9], wherein the cellulose fiber-dispersed resin composite exhibits a peel strength of 1.0N/10mm or more from an aluminum foil when thermally bonded to the aluminum foil.

[11]

The cellulose fiber-dispersed resin composite according to any one of [1] to [10], wherein the cellulose fiber-dispersed resin composite contains at least one compound selected from a metal salt of an organic acid, and silicone.

[12]

The cellulose fiber-dispersed resin composite according to any one of [1] to [11], wherein the cellulose fiber-dispersed resin composite is obtained by dispersing resin particles made of a resin different from the resin in the resin.

[13]

The resin composite material in which cellulose fibers are dispersed according to any one of [1] to [12], wherein at least a part of the resin and/or at least a part of the cellulose fibers are derived from a recycled material.

[14]

A molded article comprising the resin composite material in which cellulose fibers are dispersed according to any one of [1] to [13 ].

[15]

The molded article according to [14], wherein the molded article is a tubular body or a multi-piece body obtained by splitting a tubular body.

[16]

A composite member comprising the molded article according to [14] or [15] and another material in combination.

[17]

The resin composite material in which cellulose fibers are dispersed according to any one of [1] to [13], which is used for forming a composite by bonding to a metal.

In the present invention, the numerical range represented by the term "to" means a range including the numerical values described before and after the term "to" as the lower limit value and the upper limit value.

ADVANTAGEOUS EFFECTS OF INVENTION

The resin composite material, the molded article, and the composite member in which cellulose fibers are dispersed according to the present invention are obtained by dispersing cellulose fibers in a resin, and are excellent in mechanical properties such as tensile strength and flexural strength.

Drawings

Fig. 1 is a graph showing a fiber length distribution of cellulose fibers contained in a composite material in one embodiment of the composite material of the present invention.

Detailed Description

Preferred embodiments of the present invention will be described.

[ resin composite Material having cellulose fiber dispersed therein ]

The cellulose fiber-dispersed resin composite material of the present invention (hereinafter also simply referred to as "the composite material of the present invention") has cellulose fibers dispersed in a resin, and the content of the cellulose fibers in the composite material of the present invention (100 mass%) is 1 mass% or more and less than 70 mass%. When the content of the cellulose fiber is within this range, a composite material in which the cellulose fiber is uniformly dispersed can be easily obtained, and the mechanical properties can be effectively improved. The composite material of the present invention may contain inorganic substances such as aluminum, various additives, and the like, depending on the kind of raw materials used.

The content (% by mass) of the cellulose fibers contained in the composite material of the present invention is determined by using the following value obtained by thermogravimetric analysis.

< method for determining cellulose fiber content (cellulose effective mass ratio) >

The composite material sample (10mg) obtained was dried in advance at 80 ℃ for 1 hour in an atmospheric atmosphere, subjected to thermogravimetric analysis (TGA) at a temperature rise rate of +10 ℃/min from 23 ℃ to 400 ℃ in a nitrogen atmosphere, and the content (mass%, also referred to as cellulose effective mass ratio) of cellulose fibers was calculated from the following [ formula I ].

[ formula I ] (cellulose fiber content [% by mass) ] which is (mass decrease amount of composite material sample between 200 and 380 ℃ C. [ mg ]) × 100/(mass of composite material sample in dry state before thermogravimetric analysis [ mg ])

When the temperature is raised to 200 to 380 ℃ at a temperature raising rate of +10 ℃/min in a nitrogen atmosphere, the cellulose fibers are substantially thermally decomposed and disappear. In the present invention, the mass% calculated by the above [ formula I ] is regarded as the content of the cellulose fibers contained in the composite material. However, a part of the cellulose fibers (in some cases) does not disappear but remains in the temperature range, and if the temperature range is exceeded, for example, the resin component disappears, or if a high-temperature decomposable compound coexists, the cellulose fibers cannot be distinguished from the thermally decomposed weight reduction or the residual component, and the measurement of the amount of the cellulose fibers becomes difficult. Therefore, in the present invention, the mass% calculated from [ formula I ] is used to grasp the amount of cellulose fibers, but the relationship between the amount of cellulose fibers thus obtained and the mechanical properties of the composite material is highly correlated.

In the composite material of the present invention, LL and LN satisfy the following [ formula 1] when LL is a length-weighted average fiber length of the cellulose fibers and LN is a number-average fiber length measured under the following measurement conditions.

[ formula 1]1.1< (LL/LN) <1.5

The LL and LN above are determined as follows: a dissolution residue (insoluble component) obtained by immersing a resin composite material in which cellulose fibers are dispersed in a solvent capable of dissolving a resin in the composite material is determined by a fiber length measuring method based on a pulp-optical automatic analysis method specified in ISO 160652001(JIS P82262006).

More specifically, the LL and LN are derived from the following equation. LL is the average fiber length weighted by the length of the fiber.

LL＝(Σn_il_i ²)/(Σn_il_i)

LN＝(Σn_il_i)/(Σn_i)

Here, n is_iIs the number of fibres in the ith length range, l_iIs the central value of the ith length range.

LL/LN is an index representing the width of the distribution of fiber lengths. A larger LL/LN indicates a larger width of the distribution of fiber lengths, whereas a smaller LL/LN indicates a narrower distribution of fiber lengths.

The composite material of the present invention can sufficiently improve the mechanical strength of the composite material by satisfying 1.1< (LL/LN) < 1.5. If LL/LN is too large, the distribution of fiber length becomes too wide, and the proportion of fibers as short fibers increases relative to the average fiber length. If LL/LN is too small, the distribution of fiber length becomes too narrow, and the proportion of long fibers decreases relatively. In any case, the composition tends to exhibit an adverse effect in terms of improvement in mechanical strength. The composite material of the present invention has a structure in which the relationship between LL and LN satisfies the above [ formula 1 ].

If LL/LN is too small, the distribution of fiber length becomes too narrow, the proportion of long fibers becomes relatively low, and it becomes difficult to sufficiently improve mechanical strength such as tensile strength. From this aspect, (LL/LN) is preferably greater than 1.15. That is, it is preferable to satisfy 1.15< (LL/LN) < 1.5.

If LL/LN is too large, the distribution of the fiber length becomes too wide, the proportion of the fibers as long fibers increases relative to the average fiber length, and the proportion of the fibers as short fibers also increases, so that variations in mechanical strength such as tensile strength are likely to occur, and it is difficult to sufficiently improve the mechanical strength such as tensile strength. From this aspect, (LL/LN) is also preferably less than 1.4. That is, it is also preferable to satisfy 1.1< (LL/LN) < 1.4.

The solvent that can dissolve the resin in the composite material is appropriately selected depending on the kind of the resin in the composite material, and for example, when the resin is polyolefin, hot xylene or the like can be given, but the solvent is not limited thereto as long as the resin in the composite material can be dissolved without dissolving the cellulose fiber.

The composite material of the present invention also preferably satisfies LL and LN described below [ formula 1-2], also preferably satisfies LL and LN described below [ formula 1-2b ], more preferably satisfies [ formula 1-3], and further more preferably satisfies [ formula 1-4 ].

[ formula 1-2]1.1< (LL/LN) <1.4

[ formula 1-2b ]1.15< (LL/LN) <1.5

[ formulae 1-3]1.15< (LL/LN) <1.4

[ formulae 1-4]1.2< (LL/LN) <1.3

The fiber length of the cellulose fiber in the composite material can be measured to some extent by observing the surface of the composite material or a substance formed into a film by slicing, pressing, or the like. However, in such a method of measuring with a two-dimensional observation surface, since the observation surface is limited to a specific surface, the fiber length of all the individual fibers dispersed in the resin cannot be accurately measured. This is because there are many of the following situations for cellulose fibers in a composite material: the fibers are superposed in the thickness direction of the film, or the fibers are arranged obliquely from the observation plane. It is also considered that the fiber length is measured by analysis of a transmission tomographic image such as X-ray CT, but actually, the contrast of the cellulose fiber in the composite material is not always clear, and it is difficult to accurately measure the fiber length. The present inventors have accurately measured the fiber length distribution of cellulose fibers in a composite material, and have found a conventionally unknown technical relationship between the measured value and the mechanical properties of the composite material, and have completed the present invention based on this technical idea.

In the composite material of the present invention, when the weight-weighted (length-weighted) average fiber length of the cellulose fibers is LW, LW and LN preferably satisfy the following [ formula 2 ].

[ formula 2]1.1< (LW/LN) <3.0

The LW is also determined as follows, similarly to LL and LN: a dissolution residue (insoluble component) obtained by immersing a resin composite material in which cellulose fibers are dispersed in a solvent capable of dissolving a resin in the composite material is determined by a fiber length measuring method based on a pulp-optical automatic analysis method specified in ISO 160652001(JIS P82262006).

More specifically, the LW is derived from the following equation. LW is the average fiber length weighted by the square of the fiber length.

LW＝(Σn_il_i ³)/(Σn_il_i ²)

Here, n is_iIs the number of fibres in the ith length range, l_iIs the central value of the ith length range.

LW/LN is an index representing the width of the distribution of fiber lengths. A larger LW/LN indicates a larger width of the distribution of fiber lengths, whereas a smaller LW/LN indicates a narrower distribution of fiber lengths. When LW/LN is too large, variation in mechanical characteristics tends to be large. When LW/LN is compared with LL/LN, LW/LN is an index indicating the degree of distribution width on the longer fiber side, since LW/LN increases sharply when there are many cellulose fibers having a longer fiber length, as can be seen from the formula for defining LW/LN.

The composite material of the present invention satisfies 1.1<(LW/LN)<3.0, the mechanical strength of the composite material can be further improved. From further improvementMechanical strengthFrom the aspect of (1), the relationship between LW and LN of the composite material of the present invention more preferably satisfies the following [ formula 2-2]]Further preferably satisfies the following [ formula 2-3]]。

[ formula 2-2]1.5< (LW/LN) <2.3

[ formula 2-3]1.5< (LW/LN) <2.1

The above-mentioned relationship between LL and LN of the composite material of the present invention preferably satisfies the following [ formula 3 ]. Here, LL and LN in [ formula 3] have the unit μm.

[ formula 3] (LL/LN) < (LL x 0.0005+1.05)

By satisfying the above [ formula 3], the mechanical strength of the composite material can be further improved. From this aspect, the relationship between LL and LN described above in the composite material of the present invention more preferably satisfies the following [ formula 3-2], still more preferably satisfies [ formula 3-3], and yet still more preferably satisfies [ formula 3-4 ]. By satisfying all of the above formulas [ formula 3] to [ formula 3-4], tensile strength, flexural strength, and the like, as well as flexural modulus can be improved. Here, LL and LN in [ formula 3-2], [ formula 3-3], [ formula 3-4] are in μm.

[ formula 3-2] (LL/LN) < (LL x 0.0005+1.00)

[ formula 3-3] (LL/LN) < (LL x 0.0005+0.95)

[ formula 3-4] (LL × 0.0005+0.85) < (LL/LN)

When the resin constituting the composite material includes a polyolefin resin, hot xylene (130 to 150 ℃) can be used as a solvent that can dissolve the resin in the composite material under the conditions for measuring LL, LN, and LW described above.

In the composite material of the present invention, the content of the cellulose fiber in the composite material (100 mass%) is 1 mass% or more and less than 70 mass%. The content of the cellulose fibers in the composite material is more preferably 3% by mass or more, further preferably 5% by mass or more, and further preferably 10% by mass or more, from the viewpoint of improving mechanical properties. In addition, when further improvement of the flexural strength is considered, the content of the cellulose fiber in the composite material is preferably 25% by mass or more.

In the composite material of the present invention, the content of the cellulose fiber in the composite material is preferably less than 50% by mass, and also preferably less than 40% by mass, from the viewpoint of further suppressing the water absorption.

In the composite material of the present invention, the content of the cellulose fiber is preferably 5% by mass or more and less than 50% by mass, and also preferably 15% by mass or more and less than 40% by mass.

The composite material of the present invention is suitable as a constituent material of a molded article (resin product) requiring mechanical strength to a certain degree or more. The composite material of the present invention satisfies the relationship [ formula I ] described above with respect to the cellulose fibers in the composite material, and is excellent in mechanical strength. The reason is not clear, but is presumed to be: for example, the reinforcing effect of the cellulose fiber with respect to the slow deformation and the high-speed deformation depends on the specific length of the cellulose fiber, and the mechanical strength can be improved by appropriately varying the fiber length by setting the fiber length distribution of the cellulose fiber to a specific range.

The cellulose fibers dispersed in the composite material of the present invention preferably include cellulose fibers having a fiber length of 0.3mm or more. By including cellulose fibers having a fiber length of 0.3mm or more, the mechanical strength such as flexural strength can be further improved. From this viewpoint, it is more preferable to include cellulose fibers having a fiber length of 1mm or more.

In the composite material of the present invention, the cellulose fibers in the composite material preferably have a length-weighted average fiber length of 0.3mm or more. By setting the length-weighted average fiber length to 0.3mm or more, the mechanical strength such as flexural strength can be further improved. From this point of view, the length-weighted average fiber length of the cellulose fibers is more preferably 0.5mm or more, and still more preferably 0.7mm or more. The cellulose fibers in the composite material generally have a length-weighted average fiber length of 1.3mm or less.

The resin constituting the composite material of the present invention includes various thermoplastic resins and thermosetting resins, and preferably includes a thermoplastic resin in view of moldability. Specifically, examples of the thermoplastic resin include thermoplastic resins such AS polyvinyl chloride resin, acrylonitrile-butadiene-styrene copolymer resin (ABS resin), acrylonitrile-styrene copolymer resin (AS resin), polyamide resin (nylon), polyethylene terephthalate resin, polybutylene terephthalate resin, and polystyrene resin, thermoplastic biodegradable resins such AS 3-hydroxybutyrate-co-3-hydroxyhexanoate polymer resin (PHBH), polybutylene succinate resin, and polylactic acid resin, in addition to polyolefin resins such AS polyethylene resin and polypropylene resin. The composite material of the present invention may use 1 or 2 or more of these resins. Among these, the resin of the composite material preferably contains a polyolefin resin, and 50% by mass or more (preferably 70% by mass or more) of the resin constituting the composite material is preferably a polyolefin resin.

As the polyolefin resin, a polyethylene resin, a polypropylene resin, or also a mixture (blend resin) of a polyethylene resin and a polypropylene resin is preferable. Further, resins such as ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-methyl methacrylate copolymer, ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, ethylene-glycidyl methacrylate copolymer, ethylene-propylene copolymer and other ethylene copolymers (copolymers containing ethylene as a constituent component), and polybutene are also preferable as the polyolefin resin used in the composite material of the present invention. The polyolefin resin may be used alone in 1 kind, or may be used in combination in 2 or more kinds. The polyolefin resin constituting the composite material of the present invention is preferably a polyethylene resin and/or a polypropylene resin, and more preferably a polyethylene resin.

Examples of the polyethylene include Low Density Polyethylene (LDPE) and High Density Polyethylene (HDPE). The resin constituting the composite material of the present invention is preferably a polyolefin resin, and the polyolefin is preferably polyethylene, and particularly preferably low-density polyethylene.

As described above, the composite material of the present invention may contain two or more kinds of resins. For example, a polyolefin resin may be used in combination with polyethylene terephthalate and/or nylon. In this case, the total amount of polyethylene terephthalate and/or nylon is preferably 10 parts by mass or less with respect to 100 parts by mass of the polyolefin resin.

The low density polyethylene mentioned above means a density of 880kg/m³Above and below 940kg/m³The polyethylene of (1). The high density polyethylene is a polyethylene having a density higher than that of the low density polyethylene.

The low-density polyethylene may be what is called "low-density polyethylene" or "ultra-low-density polyethylene" having long-chain branches, linear low-density polyethylene (LLDPE) obtained by copolymerizing ethylene and a small amount of an α -olefin monomer, or "ethylene- α -olefin copolymer elastomer" included in the above density range.

The content of the resin in the composite material of the present invention is preferably 30% by mass or more, preferably 40% by mass or more, and more preferably 50% by mass or more. The content of the resin in the composite material of the present invention is usually less than 99 mass%, preferably less than 95 mass%, more preferably less than 90 mass%, and also preferably less than 85 mass%.

When the total content of the cellulose fiber and the resin in the composite material is less than 100% by mass, the remainder may contain, for example, the components described below as appropriate depending on the purpose and the raw materials used.

The composite material of the present invention is also preferably a resin in which aluminum is dispersed in addition to cellulose fibers. By containing aluminum, the thermal conductivity, visibility, light-shielding property, and sliding property of the composite material are improved. When aluminum is dispersed in the resin, the content of aluminum in the composite material of the present invention is preferably 1 mass% to 30 mass%. When the content of aluminum is within this range, the workability of the composite material can be further improved, and it becomes more difficult to produce an aluminum block during the processing of the composite material. The aluminum may be derived from an aluminum film layer of polyethylene laminated paper as a raw material. The aluminum thin film layer of the polyethylene laminated paper is not melted during melt kneading, but is gradually sheared and refined by a shearing force during kneading.

In the composite material of the present invention, the content of aluminum is preferably 5 mass% or more and 20 mass% or less in consideration of thermal conductivity, flame retardancy, and the like in addition to the above-described workability.

The average of the maximum X-Y lengths of the aluminum dispersed in the composite material of the present invention is preferably 0.02 to 2mm, and more preferably 0.04 to 1 mm. As will be described later, the average of the X-Y maximum lengths is the average of the X-Y maximum lengths as determined by image analysis software.

When the composite material contains aluminum, the aluminum preferably contains an aluminum dispersoid having a maximum length of X-Y of 0.005mm or more. The ratio of the number of aluminum dispersoids having a maximum length of X-Y of 0.005mm or more to the number of aluminum dispersoids having a maximum length of X-Y of 1mm or more is preferably less than 1%. When the ratio is less than 1%, workability of the composite material can be further improved, and it becomes more difficult to produce an aluminum block during processing of the composite material.

Further, the aluminum content can improve the sliding property, and even when the molded pieces of the composite material obtained by molding the composite material are placed one on another, for example, the molded pieces are difficult to adhere to each other and are easily peeled off. In the composite material, the aluminum preferably has a scale-like structure, and further at least a part of the aluminum has a scale-like bent structure, from the viewpoint of effectively exhibiting the function of the aluminum.

Further, the aluminum content improves the sliding property between the composite material molded bodies at room temperature, and improves the adhesion property when the composite material is thermally bonded to a metal. The aluminum-containing composite material can exhibit a peel strength of, for example, 1.0N/10mm or more between the aluminum foil and the composite material when thermally bonded to the aluminum foil. Regarding the peel strength, a sheet of the composite material and an aluminum foil having a thickness of 0.1mm were peeled at 170 ℃ for 5 minutes in a ratio of 1kg/cm²Thermally adhering by heat pressing, cutting the obtained material into strips 25mm wide, and for the strips, aluminum foil was oriented at 5 degrees in the 90 ° direction at 23 ℃Peeling was performed at a speed of 0 mm/min, and the above peel strength was obtained based on the average of the peel strengths observed at this time.

The composite material of the present invention may be a polyolefin resin in which resin particles different from the polyolefin resin are further dispersed. By dispersing resin particles different from the polyolefin resin, a composite material having further improved mechanical strength can be produced. The resin particles preferably have a maximum diameter of 10 μm or more, and more preferably have a maximum diameter of 50 μm or more. It is also preferable that the maximum diameter is 10 μm or more and the aspect ratio is 5 or more. Particularly preferably, the resin composition is in the form of a flake, and has a maximum diameter of 10 μm or more and an aspect ratio of 5 or more. The content of the resin particles in the composite material is preferably 0.1 mass% or more and 30 mass% or less. The resin particles preferably contain a resin having a melting point higher by 10 ℃ or more than that of the polyolefin resin as the matrix. In addition, the resin particles also preferably contain a resin having a melting point at 170 ℃ or higher and/or a resin showing an endothermic peak at 170 ℃ or higher and 350 ℃ or lower by differential scanning calorimetry. When a molded body is molded from the composite material, the resin particles can remain, and the strength of the resin composite material can be further improved. Examples of the resin particles include those containing at least one of polyethylene terephthalate, polybutylene terephthalate, and polyamide, and among them, polyethylene terephthalate is preferable.

The above-mentioned resin and cellulose fibers constituting the composite material of the present invention may be at least partially derived from recycled materials. In addition, the aluminum, polypropylene, polyethylene terephthalate, and nylon that may be included in the composite material of the present invention may also have at least a portion thereof derived from recycled materials. By using the recycled material, the manufacturing cost of the composite material can be suppressed.

Examples of the recycling material include: a polyethylene laminate having a paper and a polyethylene film layer; a polyethylene laminate having a paper layer, a polyethylene film layer and an aluminum film layer; beverage packages and/or food packages composed of these processed papers; or waste paper, recycled resin, etc. Two or more of these may be used. More preferably, the laminated paper and/or the beverage or food package is treated with a pulper to remove a paper portion, and a polyethylene film sheet having the obtained cellulose fibers adhered thereto (hereinafter also referred to as "cellulose fiber-adhered polyethylene film sheet") is preferably used as a recycling material. When the laminated paper or the beverage and food package has an aluminum film layer, aluminum is also adhered to the polyethylene film sheet to which the cellulose fiber is adhered.

When such recycled materials are used as raw materials, the composite material of the present invention can be obtained by melt kneading, for example, which will be described later.

The water content of the composite material of the present invention is preferably less than 1 mass%. The water content is determined as follows: the mass reduction rate (% by mass) in the case of Thermal Gravimetric Analysis (TGA) was determined from 23 ℃ to 120 ℃ at a temperature increase rate of +10 ℃/min under a nitrogen atmosphere within 6 hours after the production of the composite material.

The composite material of the present invention may contain at least one compound selected from the group consisting of a metal salt of an organic acid, and silicone. The composite material containing these compounds has improved fluidity during heating, and is less likely to cause molding failure during molding. Preferable examples of the above compound include metal salts of fatty acids such as zinc stearate and sodium stearate, and fatty acids such as oleic acid and stearic acid.

The composite material of the present invention may also contain an inorganic material. By containing an inorganic material, flexural elasticity, impact resistance and flame retardancy can be improved. Examples of the inorganic material include calcium carbonate, talc, clay, magnesium oxide, aluminum hydroxide, magnesium hydroxide, and titanium oxide.

The composite material of the present invention may contain flame retardants, antioxidants, stabilizers, weather-resistant agents, compatibilizers, impact modifiers, and the like according to the purpose. In addition, an oil component or various additives may be contained for the purpose of improving processability. Examples thereof include a vinylidene fluoride copolymer such as paraffin wax, a modified polyethylene wax, a stearate, a hydroxystearate, and a vinylidene fluoride-hexafluoropropylene copolymer, and an organic modified silicone.

The composite material of the present invention may contain carbon black, various pigments, dyes. The composite material of the present invention may contain a metallic luster-based coloring material. The conductive coating composition may contain a conductivity-imparting component such as conductive carbon black. In addition, the composite material of the present invention may contain a thermal conductivity-imparting component.

The composite material of the present invention may also be crosslinked. Examples of the crosslinking agent include organic peroxides, and specific examples thereof include dicumyl peroxide. The composite material of the present invention may be crosslinked by a silane crosslinking method.

The shape of the composite material of the present invention is not particularly limited. For example, the composite material of the present invention may be in the form of particles, or the composite material of the present invention may be molded into a desired shape. When the composite material of the present invention is in the form of granules, the granules are suitable as a constituent material of a molded article (resin product).

The use of the composite material of the present invention is not particularly limited, and it can be widely used as various members or raw materials thereof.

[ preparation of a cellulose fiber-dispersed resin composite Material ]

Next, a preferred embodiment of the method for producing a composite material of the present invention will be described. The composite material of the present invention is not limited to one obtained by the following method as long as the specification of the present invention is satisfied.

The composite material of the present invention can be a form containing a desired cellulose fiber by adjusting the kneading conditions at the time of kneading, adding an additive, or selecting and compounding a cellulose material to be used. For example, the fiber length distribution of the cellulose fibers in the obtained composite material can be adjusted by the kneading time, kneading speed, kneading temperature, the amount of an additive such as water, and the timing of addition. In this case, the average fiber length of the cellulose fibers tends to vary due to kneading, and therefore, it is important to adjust the average fiber length in view of this point.

For example, if the energy input amount during kneading is increased by increasing the kneading time or the kneading speed, the dispersibility of the cellulose fibers is improved to some extent, but the fiber length tends to be shortened. This short fiberization has an adverse effect on the mechanical strength of the composite material. That is, since an increase in the amount of energy input during kneading often brings about a decrease in fiber length and a narrow fiber length distribution at the same time, it is necessary to control them to a desired range.

Although also depending on the mixing conditions, the addition of water sometimes results in a fiber length distribution of the fibers that is relatively smaller than the average fiber length of the fibers. The reason is not known, but it is presumed that the polar interaction between water and cellulose fibers, relaxation of shearing force by water during kneading, and the like act. In particular, when a laminated paper is used as the fiber material, or when a resin sheet having cellulose adhered thereon is used as a part of the laminated paper from which the paper part is removed to some extent, the fiber length distribution in the obtained composite material tends to be easily changed depending on kneading conditions and the like.

The composite material of the present invention is preferably obtained by adjusting the conditions in view of the above and melt-kneading the resin and the fiber material.

For the melt kneading, a general kneading apparatus such as a kneader or a twin-screw extruder can be used. Preferably, a batch-type kneading apparatus such as a kneader can be used. In the twin-screw extruder, too much kneading may result in short and too narrow a distribution of the cellulose fiber length, and the mechanical strength of the composite material may not be sufficiently improved.

A batch kneader such as a kneader can easily control the cellulose fiber length and the distribution of the fiber length to a desired range. For example, when a kneader such as a batch kneader is used, the fiber length distribution can be controlled to a preferable range by adding water during kneading, and the mechanical strength of the composite material can be improved. When water is added from the beginning of kneading, the distribution of the cellulose fiber length in the obtained composite material becomes narrow, and the mechanical strength of the composite material tends not to be sufficiently improved. This is considered to be because the time for which the cellulose fibers are in contact with water in a state where the resin is not melted becomes long, and the water acts excessively on the cellulose fibers. On the other hand, when water is not added, the distribution of the cellulose fiber length becomes broad, and the mechanical strength of the composite material cannot be sufficiently improved or the strength of the composite material tends to be uneven. This is considered to be because, when cellulose fibers such as cellulose fibers derived from paper are adhered to each other without adding water, the adhesion is not easily separated, shearing during kneading is easily applied only to a part of the fibers, and the finer the fibers are, the more the fibers are made into fine fibers.

Here, "melt kneading" means kneading at a temperature at which a resin (thermoplastic resin) in a raw material melts. Preferably, the melt-kneading is carried out at a temperature and for a treatment time at which the cellulose fibers are not modified. By "no modification of the cellulose fibers" is meant that the cellulose fibers do not undergo significant discoloration, burning, or carbonization.

The temperature during the melt kneading (temperature of the melt-kneaded product) is, for example, 110 to 280 ℃ and more preferably 130 to 220 ℃ in the case of using a polyethylene resin.

In the melt kneading, the amount of the cellulose material is preferably adjusted so that the content of the cellulose fiber in the composite material to be obtained is within the above-described preferred range.

Examples of the cellulose material include materials mainly composed of cellulose, and more specifically, pulp, paper, waste paper, paper dust, recycled pulp, paper sludge, laminated paper, and broke of laminated paper.

In order to improve the whiteness of cellulose fibers and paper, the paper and waste paper may contain a filler (e.g., kaolin and talc), a sizing agent, and the like, which are generally contained. Here, the sizing agent is added for the following purpose: the paper is prevented from being smeared or bleeding on the back surface by suppressing the permeability of a liquid such as ink to paper, and a certain degree of water resistance is provided. Rosin soap, alkyl ketene dimer, alkenyl succinic anhydride, polyvinyl alcohol, and the like are mainly used. The surface sizing agent may be oxidized starch, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, or the like. For example, various additives contained in paper and waste paper, ink components, lignin, and the like may be contained.

In order to improve the whiteness of the polyethylene resin, cellulose fiber, paper, the laminate processed paper may contain a filler (e.g., kaolin, talc), a sizing agent, and the like, which are generally contained. Here, the sizing agent is added for the following purpose: the paper is prevented from being smeared or bleeding on the back surface by suppressing the permeability of a liquid such as ink to paper, and a certain degree of water resistance is provided. Rosin soap, alkyl ketene dimer, alkenyl succinic anhydride, polyvinyl alcohol, and the like are mainly used. The surface sizing agent may be oxidized starch, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, or the like. For example, various additives, ink components, and the like contained in the raw material laminated paper may be contained.

Pulp includes mechanical pulp, which contains lignin and inclusions, and chemical pulp. On the other hand, chemical pulp contains almost no lignin, but sometimes contains foreign substances other than lignin. The cellulose amount in the cellulose raw material such as pulp, paper, waste paper, paper dust, recycled pulp, paper sludge, laminated paper, broke of laminated paper used in the present invention is apparently different depending on the influence of impurities, additives, and the like in each material, or the influence of undecomposed components of cellulose outside the measurement temperature range in thermogravimetric analysis of the cellulose amount, and the like, but in the present invention, the cellulose fiber amount obtained by [ formula 1] based on the thermogravimetric analysis is used as the cellulose fiber amount.

[ molded article ]

The molded article of the present invention is a molded article molded into a desired shape by using the composite material of the present invention. The molded article of the present invention may be a sheet-shaped, plate-shaped, tubular, or various structures. Examples of the tubular molded article include straight tubes, bent tubes, corrugated tubes, and the like having a substantially circular or rectangular cross section. Further, there may be mentioned a multi-segment body obtained by dividing a tubular molded body such as a straight tube, a bent tube, or a corrugated tube having a substantially circular or rectangular cross section by half-segmentation or the like. In addition to the pipe-joining member, the molded article of the present invention can be used as a member for civil engineering, building material, automobile, or wire protection. The molded article of the present invention can be obtained by subjecting the composite material of the present invention to a usual molding means such as injection molding, extrusion molding, press molding, blow molding, or the like.

[ composite Member ]

The molded article of the present invention can be combined with another material (member) to obtain a composite member. The form of the composite member is not particularly limited. For example, a composite member having a laminated structure in which a layer made of the molded article of the present invention and a layer made of another material are combined can be produced. The composite member is also preferably a tubular structure. Examples of the other material constituting the composite member in combination with the molded article of the present invention include a thermoplastic resin material, a metal material, and the like.

For example, the composite material of the present invention can be used to join metals to form a composite. The composite may be a laminate comprising a layer of the composite material of the present invention and a layer of a metal. The composite is also preferably a coated metal pipe having a coating layer using the composite material of the present invention on the outer periphery and/or inner periphery of the metal pipe. The coated metal pipe can be used as an electromagnetic wave shielding pipe, for example. The bonding of the composite material of the present invention to the metal is preferably a direct bonding of the two. The joining may be performed by a conventional method such as thermal bonding. In addition, the composite material of the present invention can also be used as an adhesive sheet. For example, in order to bond a metal to a polyolefin resin material, the composite material of the present invention may be used as an adhesive resin layer by interposing the metal and the polyolefin resin material therebetween. In addition, the composite material of the present invention can also be used as a hot melt adhesive.

The composite member of the present invention can be suitably used as a member for civil engineering, building materials or automobiles or a raw material thereof.

When the composite material of the present invention is joined to a metal to form a composite, the kind of the metal is not particularly limited. The metal preferably comprises at least one of aluminum, copper, steel, aluminum alloys, copper alloys, stainless steel, magnesium alloys, lead alloys, silver, gold, and platinum. Among them, the metal preferably contains at least one of aluminum, an aluminum alloy, copper, and a copper alloy, and more preferably contains at least one of aluminum, an aluminum alloy, copper, and a copper alloy. In addition, the metal preferably contains aluminum and/or an aluminum alloy, and is also preferably aluminum and/or an aluminum alloy.

Examples

The present invention is further illustrated based on examples, but the present invention is not limited to these modes. The measurement method and evaluation method of each index in the present invention are as follows.

[ cellulose content in composite Material ]

The composite material sample (10mg) obtained was dried in advance at 80 ℃ for 1 hour in an atmospheric atmosphere, and thermogravimetric analysis (TGA) was performed at a temperature rise rate of +10 ℃/min from 23 ℃ to 400 ℃ in a nitrogen atmosphere, and the content (mass%) of the cellulose fiber was calculated from the following [ formula 1 ]. 5 identical composite material samples were prepared, and thermogravimetric analysis was performed on each composite material sample in the same manner as described above to obtain an average of 5 values of the calculated cellulose fiber content (% by mass), and the average was taken as the cellulose fiber content (% by mass).

[ formula I ] (cellulose fiber content [% by mass) ] which is (mass decrease amount of composite material sample between 200 and 380 ℃ C. [ mg ]) × 100/(mass of composite material sample in dry state before thermogravimetric analysis [ mg ])

[ Length-weighted average fiber length, number-average fiber length, weight-weighted average fiber length ]

The length-weighted average fiber length and the number average fiber length were measured by a fiber length measuring method based on the pulp-optical automatic analysis method specified in ISO 160652001(JIS P82262006) for the hot xylene dissolution residue (insoluble component) of the composite material. Specifically, 0.1 to 1g of a molded piece of the composite material was cut out, and the sample was wrapped with a 400-mesh stainless steel net and immersed in 100ml of xylene at 138 ℃ for 24 hours. Subsequently, the sample was lifted and dried in vacuum at 80 ℃ for 24 hours. Using the hot xylene dissolution residue (insoluble component) of the composite material thus obtained, the length-weighted average fiber length, the number-average fiber length, and the weight-weighted average fiber length were determined by a fiber length measurement method based on a pulp-optical automatic analysis method. MORFI COMPACT, manufactured by TECHPAP, was used for the determination.

[ tensile Strength ]

Test pieces were prepared by injection molding, and the tensile strength of test piece No. 2 was measured according to JIS K71131995. The unit is "MPa".

[ flexural Strength and flexural modulus ]

The flexural strength and flexural modulus were measured at a specimen thickness of 4mm and a bending speed of 2mm/min in accordance with JIS K712016. Specifically, test pieces (thickness 4mm, width 10mm, length 80mm) were prepared by injection molding, and a bending test was carried out in accordance with JIS-K712016 by applying a load at a distance between the fulcrums of 64mm, a radius of curvature of the fulcrum and the point of action of 5mm, and a test speed of 2mm/min to measure the bending strength (MPa) and the bending modulus (MPa).

Here, the flexural modulus Ef is obtained as follows

Bending stress σ f1 measured as deflection amount at strain 0.0005 (. epsilon.f 1),

Bending stress σ f2 measured as deflection at a strain of 0.0025 (. epsilon.f 2),

dividing the difference by the difference between the corresponding strain amounts,

namely, it is determined by the following equation.

Ef＝(σf2－σf1)/(εf2－εf1)

The amount of deflection S for determining the bending stress at this time can be determined by the following equation.

S＝(ε·L²)/(6·h)

S: deflection

Epsilon: bending strain

L: distance between fulcrums

h: thickness of

[ peeling Strength ]

The composite material was formed into a sheet having a thickness of 1mm and a length of 20cm by press molding. The sheet was laminated with an aluminum foil (1N-30 material (soft, double-sided polished) having a thickness of 0.1mm, manufactured by UACJ, Inc.) and preheated at 170 ℃ for 5 minutes, and then heated and pressed at 170 ℃ under a pressure of 4.2MPa for 5 minutes to perform thermal bonding. The thus-obtained laminate was left to stand at 23 ℃ for 2 days or longer, and then cut into strips having a width of 25mm and a length of 20cm, to prepare 5 of the above-mentioned samples. For each strip sample, the aluminum foil was peeled off at a rate of 50 mm/min in the direction of 90 ° (direction perpendicular to the sheet surface). In this peeling, the average of the peel strengths of the sample having the largest peel strength and the sample having the smallest peel strength was calculated, and the obtained average was defined as the peel strength of the composite material.

[ preparation example 1]

In preparation example 1, a composite material was prepared using low-density polyethylene and an ethylene-acrylic acid copolymer as resins and pulp as a fiber material. The details will be described in examples 1 to 2 and comparative examples 1 to 2 below.

< example 1>

In example 1, low-density polyethylene 1(NOVATEC LC600A, manufactured by japan polyethylene co., ltd.), pulp 1(ARBOCEL BC200, manufactured by Rettenmaier) and ethylene-acrylic acid copolymer 1(NUCREL, manufactured by DuPont-Mitsui Polychemicals) were mixed at the compounding ratio (unit: parts by mass) shown in the upper stage of table 1, and melt-kneaded by a kneader to obtain a composite material. 1.5 parts by mass of water was added during kneading. Thus, a cellulose fiber-dispersed resin composite material of example 1 was obtained.

In example 1, and in each of the following examples and comparative examples, the water content of the obtained composite material was less than 1 mass%.

< example 2>

In example 2, low-density polyethylene 1(NOVATEC LC600A, manufactured by japan polyethylene co., ltd.), pulp 2 (arbocef 400, manufactured by Rettenmaier) and ethylene-acrylic acid copolymer 1(NUCREL, manufactured by DuPont-Mitsui Polychemicals) were mixed at the compounding ratio (unit: parts by mass) shown in the upper stage of table 1, and melt-kneaded by a kneader to obtain a composite material. 40 parts by mass of water was added during kneading. Thus, a cellulose fiber-dispersed resin composite material of example 2 was obtained.

< comparative example 1>

Low-density polyethylene 1(NOVATEC LC600A, manufactured by japan polyethylene corporation), pulp 1(ARBOCELBC200, manufactured by Rettenmaier) and ethylene-acrylic acid copolymer 1(NUCREL, manufactured by DuPont-Mitsui polychemials) were mixed at the mixing ratio (unit: parts by mass) shown in the upper stage of table 1, and melt-kneaded by a kneader to obtain a composite material. At the time of kneading, 40 parts by mass of water was added from the beginning. Thus, a cellulose fiber-dispersed resin composite material of comparative example 1 was obtained.

< comparative example 2>

Low-density polyethylene 1(NOVATEC LC600A, manufactured by NOVATEC polyethylene Co., Ltd.) was used as comparative example 2.

The middle section of table 1 shows the content of cellulose fibers in each example or comparative example, and the lower section of table 1 shows the evaluation results and the like.

[ TABLE 1]

TABLE 1

As shown in Table 1, even when the same pulp was used and the same raw material mixing amount was used, the composite material of the present invention having LL/LN of more than 1.1 exhibited high values of tensile strength, flexural strength, and flexural modulus (comparison of example 1 with comparative example 1).

In example 2, in which LL/LN was within the range specified in the present invention, the tensile strength, flexural strength, and flexural modulus were all high, and it was found that the mechanical strength was excellent.

[ preparation example 2]

In preparation example 2, a composite material was prepared using high-density polyethylene as a resin and broke of a laminated paper as a fiber material. In some examples, an acid-modified polyethylene resin is blended. The details will be described in examples 3 to 6 and comparative examples 3 and 4 below.

< example 3>

In example 3, broke of polyethylene laminated paper (having paper, a polyethylene film layer, and an aluminum film layer) was pulverized by a rotary blade type pulverizer (manufactured by HORAI corporation), and the pulverized material and high-density polyethylene 1(NOVATEC HJ490, manufactured by japan polyethylene corporation) were mixed at the compounding ratio shown in the upper stage of table 2, and melt-kneaded by a kneader, to obtain a composite material. 30 parts by mass of water was added during the kneading. Thus, a cellulose fiber-dispersed resin composite material of example 3 was obtained.

< examples 4 and 5>

In examples 4 and 5, broke of polyethylene laminated paper (having paper, a polyethylene film layer, and an aluminum film layer) was pulverized by a rotary blade type pulverizer (manufactured by HORAI corporation), and the pulverized material, high-density polyethylene 1(NOVATEC HJ490, manufactured by japan polyethylene corporation), and acid-modified polyethylene resin 1 (maleic acid-modified polyethylene, fusibond, dupont) were mixed at the compounding ratio shown in the upper stage of table 2, and melt-kneaded by a kneader, to obtain a composite material. In example 4, 60 parts by mass of water was added during kneading, and in example 5, 100 parts by mass of water was added. Thus, the resin composite materials in which the cellulose fibers were dispersed in examples 4 and 5 were obtained.

< example 6>

In example 6, broke of polyethylene laminated paper (having paper, a polyethylene film layer, and an aluminum film layer) was pulverized by a rotary blade type pulverizer (manufactured by HORAI corporation), and the pulverized material and high-density polyethylene 1(NOVATEC HJ490, manufactured by japan polyethylene corporation) were mixed at the compounding ratio shown in the upper stage of table 2, and melt-kneaded by a twin-screw extruder to obtain a composite material. In example 6, 60 parts by mass of water was added from the beginning of melt kneading. Thus, a cellulose fiber-dispersed resin composite material of example 6 was obtained.

< comparative example 3>

A resin composite material in which cellulose fibers were dispersed of comparative example 3 was obtained in the same manner as in example 3, except that no water was added during kneading in example 3.

< comparative example 4>

High-density polyethylene 1(NOVATEC HJ490, manufactured by japan polyethylene corporation) was used as comparative example 4.

The middle section of table 2 shows the content of cellulose fibers in each example or comparative example, and the lower section of table 2 shows the evaluation results and the like.

[ TABLE 2]

TABLE 2

As shown in table 2, even when the same fiber material was used and the same raw material blending amount was used, the composite material of the present invention having LL/LN less than 1.5 exhibited high values of tensile strength, flexural strength, and flexural modulus (comparison of example 3 and comparative example 3).

In addition, it is known that: by replacing a part of the polyethylene resin with the acid-modified resin, LL/LN can be adjusted to a more preferable range, and the tensile strength and the flexural strength can be further improved (examples 4 and 5).

[ preparation example 3]

In production example 3, a small amount of an acid-modified polyethylene resin was compounded in the same manner as in examples 4 and 5 of production example 2 to prepare a composite material. The details will be described in examples 7 to 10 and comparative example 5 below.

< examples 7 to 8>

In examples 7 to 8, broke of polyethylene laminated paper (having paper, a polyethylene film layer, and an aluminum film layer) was pulverized by a rotary blade type pulverizer (manufactured by HORAI corporation), and the pulverized material, high-density polyethylene 1(NOVATEC HJ490 manufactured by japan polyethylene corporation) and acid-modified polyethylene 1 (maleic acid-modified polyethylene, FUSABOND, manufactured by dupont) were mixed at the compounding ratio shown in the upper stage of table 3, and melt-kneaded by a kneader, thereby obtaining a composite material. In example 7, 50 parts by mass of water was added first, and 50 parts by mass of water was further added during kneading. In example 8, 100 parts by mass of water was added during kneading. Thus, the resin composite materials in which the cellulose fibers of examples 7 to 8 were dispersed were obtained.

< example 9>

In example 9, broke of polyethylene laminated paper (having paper, a polyethylene film layer, and an aluminum film layer) was pulverized by a rotary blade type pulverizer (manufactured by HORAI corporation), and the pulverized material, high-density polyethylene 1(NOVATEC HJ490 manufactured by japan polyethylene corporation), and acid-modified polyethylene 1 (maleic acid-modified polyethylene, FUSABOND, manufactured by dupont) were mixed at the compounding ratio shown in the upper stage of table 3, and melt-kneaded by a kneader, to obtain a composite material. In example 9, 100 parts by mass of water was added during melt kneading. The composite material thus obtained was further subjected to pulverization treatment with a pulverizer and kneading treatment with a kneader alternately 2 times. Thus, a cellulose fiber-dispersed resin composite material of example 9 was obtained.

< example 10>

In example 10, broke of polyethylene laminated paper (having paper, a polyethylene film layer, and an aluminum film layer) was pulverized by a rotary blade type pulverizer (manufactured by HORAI corporation), and the pulverized material, high-density polyethylene 1(NOVATEC HJ490 manufactured by japan polyethylene corporation), and acid-modified polyethylene 1 (maleic acid-modified polyethylene, FUSABOND, manufactured by dupont) were mixed at the compounding ratio shown in the upper stage of table 3, and melt-kneaded by a twin-screw extruder to obtain a composite material. In example 10, 100 parts by mass of water was added from the beginning of melt kneading. Thus, a cellulose fiber-dispersed resin composite material of example 10 was obtained.

< comparative example 5>

In comparative example 5, broke of polyethylene laminated paper (having paper, a polyethylene film layer, and an aluminum film layer) was pulverized by a rotary blade type pulverizer (manufactured by HORAI corporation), and the pulverized material, high-density polyethylene 1(NOVATEC HJ490 manufactured by japan polyethylene corporation) and acid-modified polyethylene 1 (maleic acid-modified polyethylene, FUSABOND, manufactured by dupont) were mixed at the compounding ratio shown in the upper stage of table 3, and melt-kneaded by a kneader to obtain a composite material. In comparative example 5, 100 parts by mass of water was added from the beginning of kneading. The composite material thus obtained was further subjected to pulverization treatment with a pulverizer and kneading treatment with a kneader alternately 2 times. Thus, a cellulose fiber-dispersed resin composite material of comparative example 5 was obtained.

The middle section of table 3 shows the content of cellulose fibers in each example or comparative example, and the lower section of table 3 shows the evaluation results and the like. In the column where the respective formulas in the following table satisfy, ". smallcircle" means satisfied (satisfies the corresponding expression), "x" means not satisfied (does not satisfy the corresponding expression).

[ TABLE 3]

TABLE 3

As shown in Table 3, even when the same fiber material was used and the same raw material blending amount was used, the composite material of the present invention having LL/LN of more than 1.1 was improved in tensile strength and flexural strength (comparison between example 10 and comparative example 5).

In addition, it is also known that: the composite materials satisfying the requirements of the present invention are excellent in mechanical strength, and among them, the mechanical strength is further improved when the composite materials satisfy the following formulas [3] to [ 3-4] (examples 7 to 10).

[ preparation example 4]

In production example 4, a composite material was produced by using high-density polyethylene as a resin, and blending a small amount of an acid-modified polyethylene resin and waste paper as a fiber material. The details will be described in the following examples 11 to 13.

< examples 11 to 13>

High-density polyethylene 1(NOVATEC HJ490, manufactured by japan polyethylene corporation), acid-modified polyethylene 1 (maleic acid-modified polyethylene, FUSABOND, dupont), and waste paper were mixed at the compounding ratio shown in the upper stage of table 4, and melt-kneaded by a kneader to obtain a composite material. During the kneading, 1.7 parts by mass of water was added.

Here, as the waste paper, shredded articles of paper shredder used for office paper in example 11, shredded articles of newspaper used in example 12 (using a rotary blade shredder (manufactured by HORAI corporation)), and shredded articles of broke of paper (having paper, a polyethylene film layer, and an aluminum film layer) laminated and processed using polyethylene in example 13 (using a rotary blade shredder (manufactured by HORAI corporation)).

The cellulose fiber content of each example is shown in the middle section of table 4, and the evaluation results and the like are shown in the lower section of table 4.

[ TABLE 4]

TABLE 4

From the results of table 4 above, it is understood that the composite material of the present invention has further improved mechanical strength when [ formula 3] to [ formula 3-4] are satisfied (comparison between example 11 and examples 12 to 13).

[ preparation example 5]

In preparation example 5, a composite material was prepared using low-density polyethylene as a resin and broke of a laminated paper as a fiber material. The details will be described in examples 14 to 16 and comparative example 6 below.

< example 14>

In example 14, broke of polyethylene laminated paper (having paper, a polyethylene film layer, and an aluminum film layer) was pulverized by a rotary blade type pulverizer (manufactured by HORAI corporation), and the pulverized material and low density polyethylene 1(NOVATEC LC600A, manufactured by japan polyethylene corporation) were mixed at the compounding ratio shown in the upper stage of table 5, and melt-kneaded by a kneader, to obtain a composite material. 40 parts by mass of water was added during kneading. Thus, a cellulose fiber-dispersed resin composite material of example 14 was obtained.

< example 15>

In example 15, broke of polyethylene laminated paper (having paper, a polyethylene film layer, and an aluminum film layer) was pulverized by a rotary blade type pulverizer (manufactured by HORAI corporation), and the pulverized material and low density polyethylene 1(NOVATEC LC600A, manufactured by japan polyethylene corporation) were mixed at the compounding ratio shown in the upper stage of table 5, and melt-kneaded by a kneader, to obtain a composite material. During kneading, 10 parts by mass of water was added 4 times to mix the mixture (the total amount of water mixed was 40 parts by mass). Thus, a cellulose fiber-dispersed resin composite material of example 15 was obtained.

< example 16>

In example 16, broke of polyethylene laminated paper (having paper, a polyethylene film layer, and an aluminum film layer) was pulverized by a rotary blade type pulverizer (manufactured by HORAI corporation), and the pulverized material and low density polyethylene 1(NOVATEC LC600A, manufactured by japan polyethylene corporation) were mixed at the compounding ratio shown in the upper stage of table 5, and melt-kneaded by a kneader. 40 parts by mass of water was added during kneading. The obtained composite material was further subjected to pulverization treatment with a pulverizer and kneading treatment with a kneader alternately 2 times. Thus, a cellulose fiber-dispersed resin composite material of example 16 was obtained.

< comparative example 6>

In comparative example 6, broke of polyethylene laminated paper (having paper, a polyethylene film layer and an aluminum film layer) was pulverized by a rotary blade type pulverizer (manufactured by HORAI corporation), and the pulverized material and low density polyethylene 1(NOVATEC LC600A, manufactured by japan polyethylene corporation) were mixed at the compounding ratio shown in the upper stage of table 5 and melt-kneaded by a kneader. At the time of kneading, 40 parts by mass of water was added from the beginning. The obtained composite material was further subjected to pulverization treatment with a pulverizer and kneading treatment with a kneader alternately 2 times. Thus, a cellulose fiber-dispersed resin composite material of comparative example 6 was obtained.

The middle section of table 5 shows the content of cellulose fibers in each example or comparative example, and the lower section of table 5 shows the evaluation results and the like.

[ TABLE 5]

TABLE 5

As shown in Table 5, even when the same fiber material was used and the same raw material blending amount was used, it was found that the composite material of the present invention having LL/LN of more than 1.1 was improved in all of tensile strength, flexural strength and flexural modulus (comparison between example 16 and comparative example 6). In addition, it is also known that: the composite materials satisfying the requirements of the present invention are excellent in mechanical strength, and among them, the mechanical strength is further improved when the composite materials satisfy the following formulas [3] to [ 3-4] (examples 14 to 16).

The content of aluminum in the composite material obtained in example 15 was 8.1 mass%. The cross section of the bending test piece was observed for the composite material of example 15, and as a result, a folded structure in which aluminum was bent was observed. Further, with respect to the composite material of example 15, the peel strength with the aluminum foil was observed by the above-mentioned method, and the result was 1.7N/10 mm. For the same polyethylene single substance as used in example 15 (comparative example 2), the peel strength with aluminum foil was 0.8N/10 mm. The composite material of example 15, which contained aluminum and had cellulose fibers with a specific fiber length distribution using the laminated paper as a raw material, had high peel strength and also had excellent adhesion to metals.

[ preparation example 6]

In preparation example 6, a composite material was prepared by using high-density polyethylene as a resin and a small amount of an acid-modified polyethylene resin as a blend, and using broke of a laminated paper as a fiber material. The details will be described in examples 17 to 18 below.

< example 17>

In example 17, broke of polyethylene laminated paper (having paper, a polyethylene film layer, and an aluminum film layer) was pulverized by a rotary blade type pulverizer (manufactured by HORAI corporation), and the pulverized material, high-density polyethylene 1(NOVATEC HJ490 manufactured by japan polyethylene corporation), and acid-modified polyethylene 1 (maleic acid-modified polyethylene, FUSABOND, manufactured by dupont) were mixed at the compounding ratio shown in the upper stage of table 6, and melt-kneaded by a kneader to obtain a composite material. 100 parts by mass of water was added during the kneading. Thus, a cellulose fiber-dispersed resin composite material of example 17 was obtained.

< example 18>

In example 18, broke of polyethylene laminated paper (having paper, a polyethylene film layer, and an aluminum film layer) was pulverized by a rotary blade type pulverizer (manufactured by HORAI corporation), and the pulverized material, high-density polyethylene 1(NOVATEC HJ490 manufactured by japan polyethylene corporation), and acid-modified polyethylene 1 (maleic acid-modified polyethylene, FUSABOND, manufactured by dupont) were mixed at the compounding ratio shown in the upper stage of table 6, and melt-kneaded by a kneader, to obtain a composite material. 5 parts by mass of water was added during the kneading. Thus, a cellulose fiber-dispersed resin composite material of example 18 was obtained.

The cellulose fiber content of each example is shown in the middle of table 6, and the evaluation results and the like are shown in the lower stage of table 6. The results of example 8 and example 5 are also described for reference.

[ TABLE 6]

TABLE 6

As shown in Table 6, when LW/LN is increased, the coefficient of variation of tensile strength tends to be increased (example 18).

[ preparation example 7]

In production example 7, a composite material was produced by using high-density polyethylene as a resin, and blending a small amount of an acid-modified polyethylene resin and waste paper as a fiber material. The details will be described in the following examples 19 to 20.

< examples 19 to 20>

High-density polyethylene 1(NOVATEC HJ490, manufactured by japan polyethylene corporation), acid-modified polyethylene 1 (maleic acid-modified polyethylene, FUSABOND, dupont), and waste paper were mixed at the compounding ratio shown in the upper stage of table 7, and melt-kneaded by a kneader to obtain a composite material. 3.3 parts by mass of water was added during kneading.

Here, as the waste paper, shredder shredded articles of office paper were used in example 19, and shredded articles of newspaper (using a rotary blade shredder (manufactured by HORAI corporation)) were used in example 20.

The cellulose fiber content of each example is shown in the middle of table 7, and the evaluation results and the like are shown in the lower stage of table 7. Further, fig. 1 shows a graph showing the fiber length distribution of each example. In FIG. 1, A is the composite material of example 19 and B is the composite material of example 20.

[ TABLE 7]

TABLE 7

As shown in table 7, when example 19 and example 20 were compared, the length weighted average fiber length of example 19 was smaller. However, example 19 has higher tensile strength and bending strength. It has been considered that the longer the fiber length of the cellulose fiber is, the higher the mechanical properties are. However, the results of table 7 above show that: by suppressing LL/LN to a certain level (for example, by making LL/LN less than 1.3 or by a constitution satisfying [ formula 3-2 ]), the mechanical properties of the composite material can be effectively improved even if the fiber length of the cellulose fiber is short.

[ preparation example 8]

In preparation example 8, a composite material was prepared using polypropylene as a resin and broke of a laminated paper as a fiber material. The details will be described in examples 21 to 22 and comparative example 7 below.

< example 21>

Broke of polyethylene laminated paper (having paper, a polyethylene film layer, and an aluminum film layer) was pulverized by a rotary blade type pulverizer (manufactured by HORAI corporation), and the pulverized material and polypropylene were mixed at the compounding ratio shown in the upper stage of table 8. As the polypropylene resin, J783HV, MI12.7g/min, manufactured by PRIME POLYMER, K.K.. The mixture was put into a kneader to be melt-kneaded. 50 parts by mass of water was added during kneading. Thus, a resin composite material in which cellulose fibers are dispersed is produced.

< example 22>

Broke of polyethylene laminated paper (having paper, a polyethylene film layer, and an aluminum film layer) was pulverized by a rotary blade type pulverizer (manufactured by HORAI corporation), and the pulverized material and polypropylene were mixed at the compounding ratio shown in the upper stage of table 8. As the polypropylene resin, J783HV, MI12.7g/min, manufactured by PRIME POLYMER, K.K.. The mixture was melt-kneaded by a twin-screw extruder to obtain a composite material. 50 parts by mass of water was added from the beginning of melt kneading. Thus, a resin composite material in which cellulose fibers are dispersed is obtained.

< comparative example 7>

Broke of paper was laminated using a polypropylene resin and a polyethylene as a paper raw material, and kneading conditions were changed to produce a resin composite material in which cellulose fibers were dispersed. Broke of polyethylene laminated paper (having paper, a polyethylene film layer, and an aluminum film layer) was pulverized by a rotary blade pulverizer (manufactured by HORAI corporation), the pulverized material was mixed with a polypropylene resin (J783HV, mi12.7g/min, manufactured by PRIME POLYMER) at a compounding ratio shown in the upper stage of table 8, and the mixture was put into a kneader and melt-kneaded to obtain a composite material. 50 parts by mass of water was added from the beginning of melt kneading. The obtained composite material was further subjected to pulverization treatment with a pulverizer and kneading treatment with a kneader alternately 2 times. Thus, a cellulose fiber-dispersed resin composite material of comparative example 7 was obtained.

The composition of each composite material is shown in the middle of table 8, and the evaluation results and the like are shown in the lower part of table 8.

[ TABLE 8]

TABLE 8

As shown in Table 8, the composite material of comparative example 7 having LL/LN of less than 1.1 exhibited poor mechanical properties.

While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

The present application claims priority based on japanese patent application 2018-228578 filed in japan on 12/5/2018, which is hereby incorporated by reference and the contents of which are incorporated as part of the description of the present specification.