阅读说明：本技术 叠层体及其制造方法 (Laminate and method for producing same ) 是由 冈善之 石田浩 福崎裕太 秋山律文 于 2019-02-26 设计创作，主要内容包括：本发明涉及在片状的发泡体的至少一面叠层膜,并满足以下(A)～(E)的要件的叠层体及其制造方法。(A)发泡体的厚度为0.05～1.5mm,(B)膜的厚度为25～250μm,(C)膜的表面电阻率为1×10<Sup>11</Sup>Ω以上,(D)发泡体与膜不经由粘着剂而直接接合,(E)发泡体与膜的剥离强度为10mN/25mm～100mN/25mm。通过本发明,可以提供在对薄的发泡体进行各种加工时,发泡体不变形,能够进行所希望的加工的叠层体,可以从叠层体适当剥离膜,从而可以容易地单独使用发泡体。此外,由于不经由粘着剂而制成叠层体,因此可以消除在膜剥离后的发泡体残存粘着剂的可能性。(The present invention relates to a laminate in which a film is laminated on at least one side of a foam in a sheet form and satisfies the following requirements (A) to (E) and a method for producing the same, wherein (A) the thickness of the foam is 0.05 to 1.5mm, (B) the thickness of the film is 25 to 250 [ mu ] m, and (C) the surface resistivity of the film is 1 × 10 11 Omega or more, (D) the foam and the film are directly bonded without using an adhesive, and (E) the peel strength between the foam and the film is 10mN/25mm to 100mN/25 mm. The present invention can provide a laminate which can be processed as desired without deforming a foam when a thin foam is subjected to various kinds of processing, and can suitably peel off a film from the laminate, thereby allowing the foam to be used alone easily. Further, since the laminate is made without using an adhesive, the possibility that the adhesive remains in the foam after the film is peeled off can be eliminated.)

1. A laminate comprising a sheet-like foam and a film laminated on at least one surface of the foam, wherein the laminate satisfies the following requirements (A) to (E),

(A) the thickness of the foam is 0.05 to 1.5mm,

(B) the thickness of the film is 25 to 250 μm,

(C) the film had a surface resistivity of 1 × 10¹¹The content of the carbon dioxide is more than omega,

(D) the foam and the film are directly bonded without an adhesive,

(E) the peel strength between the foam and the film is 10mN/25mm to 100mN/25 mm.

2. The laminate according to claim 1, wherein the foam has a thickness of 0.05 to 0.5 mm.

3. The laminate according to claim 1 or 2, wherein the peel strength between the foam and the film is in the range of 25mN/25mm to 100mN/25 mm.

4. The laminate according to any one of claims 1 to 3, wherein the potential of the laminate is in the range of-30 to +30 kV.

5. The laminate according to claim 4, wherein the potential of the laminate is in the range of-15 to +15 kV.

6. The laminate according to any one of claims 1 to 5, wherein the foam and the film are each mainly composed of an olefin resin.

7. The laminate according to claim 1 to 6, wherein the foam has an apparent density of 100kg/m³～500kg/m³The range of (1).

8. The laminate according to any one of claims 1 to 7, wherein a surface of the film on a side to be in close contact with the foam is electrically charged.

9. The laminate according to any one of claims 1 to 8, wherein the film-peeled foam is used for fixing a member constituting an electronic/electrical device to a device body.

10. A method for manufacturing a laminate in which a sheet-like foam and a film are brought into close contact with each other, comprising the steps of: a charging step of charging the foam or the film by applying an electric charge thereto; and a bonding step for bonding the foam to the film.

11. The method for producing a laminate according to claim 10, comprising, after the adhesion step, the adhesion force increasing step of: an outer surface of the foam or the film is provided with a charge having an opposite polarity to a charge of a bonding surface of the foam or the film, and the bonding force of the bonding surface is increased.

12. The method of producing a laminate according to claim 10 or 11, wherein in the charging step, a surface of the film on the side of being in close contact with the foam is charged.

13. The method of producing a laminate according to any one of claims 10 to 12, wherein the bonding step comprises a step of pressing the foam and the film against each other with a roller.

14. The method for producing a laminate according to any one of claims 10 to 13, wherein the following materials (A) and (B) are used,

(A) a foam having a thickness of 0.05 to 1.5mm,

(B) a thickness of 25 to 250 μm and a surface resistivity of 1 × 10¹¹Omega or higher film.

15. The method for producing a laminate according to claim 14, wherein the thickness of the foam is 0.05 to 0.5 mm.

Technical Field

The present invention relates to a laminate in which a sheet-like foam and a film are laminated and a method for producing the same, and more particularly, to a laminate in which desired processing can be performed as a laminate without deforming the film even when the foam is thin, and the film can be easily and appropriately peeled from the laminate, thereby enabling the foam to be used alone, and a method for producing the same.

Background

Foamed products such as polyolefin resin foamed products have uniform and fine closed cells and excellent cushioning properties and processability, and therefore, are used in various applications. Such a foam can be easily made into a film by stretching, slicing, or the like, and retains excellent cushioning properties and impact absorbability even in a state of being made into a film, and therefore, is suitably used as a cushioning material for electronic/electrical devices such as cellular phones. The foam may be used alone or in a state where an adhesive layer or the like is provided on one or both surfaces of the foam. Such a foam is incorporated into a housing of an electronic/electric device or the like as a cushioning material or the like after various processes such as a cutting process for adjusting a width according to a form of the electronic/electric device and a punching process for conforming a shape are performed regardless of the presence or absence of an adhesive layer.

The foam used as described above is usually about 0.05 to 1.5mm thick, more usually about 0.05 to 0.5mm, very thin, and low in density and strength for providing cushioning properties, and therefore, when various processes such as described above are performed, problems such as deformation and wrinkling may occur due to stretching caused by tension during transportation. Further, in the case of a foam having a tackiness of a resin itself such as ultra-low density polyethylene or ethylene-vinyl acetate copolymer for the purpose of improving impact absorbability, there is a problem that the foam adheres to each other when the foam is wound into a roll and stored for a long period of time, and a phenomenon called blocking occurs, and an excessive tension is required for the foam when the foam is unwound for peeling to use the foam. When a foam having a small thickness, particularly a low density, is processed in this way, various problems such as deformation, wrinkles, blocking, and the like may occur.

In order to solve these problems, a method of winding a foam together with a release paper (a concept including a release film) is conceivable (for example, patent document 1). However, in the case of using only the release paper, in the case of a particularly thin foam, there may be a problem that air enters between the foam and the release paper, and the foam is deformed. Further, there is also a method of laminating a film or the like coated with an adhesive to a foam and winding the film, but there is a possibility that even if the film is peeled off for use in order to obtain only a foam layer, the adhesive remains partially adhered to the foam layer side, and a desired foam use form is not easily obtained.

Disclosure of Invention

Problems to be solved by the invention

Accordingly, an object of the present invention is to provide a laminate in which a foam having a small thickness can be processed as desired without deforming the foam when the foam is subjected to various kinds of processing, and a film can be easily and appropriately peeled from the laminate, whereby the foam can be used alone without causing any problem, and a method for producing the laminate.

Means for solving the problems

As a result of intensive studies, the present inventors have found that the above problems can be solved by a laminate described below and a method for producing the same.

That is, the laminate according to the present invention has the following structure.

(1) A laminate comprising a sheet-like foam and a film laminated on at least one surface of the foam, wherein the following requirements (A) to (E) are satisfied.

(A) The thickness of the foam is 0.05 to 1.5mm

(B) The thickness of the film is 25 to 250 μm

(C) The film had a surface resistivity of 1 × 10¹¹Omega or more

(D) The foam and the film are directly bonded without using an adhesive

(E) The peel strength between the foam and the film is 10mN/25mm to 100mN/25mm

(2) The laminate according to (1), wherein the foam has a thickness of 0.05 to 0.5 mm.

(3) The laminate according to (1) or (2), wherein the peel strength between the foam and the film is in the range of 25mN/25mm to 100mN/25 mm.

(4) The laminate according to any one of (1) to (3), wherein the potential of the laminate is in the range of-30 to +30 kV.

(5) The laminate according to (4), wherein the laminate has a potential in the range of-15 to +15 kV.

(6) The laminate according to any one of (1) to (5), wherein the foam and the film are both mainly composed of an olefin resin.

(7) The laminate according to any one of (1) to (6), wherein the foam has an apparent density of 100kg/m³～500kg/m³The range of (1).

(8) The laminate according to any one of (1) to (7), wherein a surface of the film on the side of adhesion to the foam is charged.

(9) The laminate according to any one of (1) to (8), wherein the foam from which the film is peeled is used for fixing a member constituting an electronic/electric device to a device body.

The method for producing a laminate according to the present invention has the following configuration.

(10) A method for manufacturing a laminate in which a sheet-like foam and a film are brought into close contact with each other, comprising the steps of: a charging step of charging the foam or the film by applying an electric charge thereto; and a bonding step for bonding the foam to the film.

(11) The method for producing a laminate according to item (10), further comprising, after the adhesion step, the adhesion force increasing step of: the outer surface of the foam or the film is provided with a charge having a polarity opposite to the charge of the bonding surface of the foam or the film, and the bonding force of the bonding surface is increased.

(12) The method for producing a laminate according to (10) or (11), wherein in the charging step, a surface of the film on the side of being in close contact with the foam is charged.

(13) The method of producing a laminate according to any one of (10) to (12), wherein the bonding step includes a step of pressing the foam and the film against each other with a nip roller.

(14) The method for producing a laminate according to any one of (10) to (13), which uses the following materials (A) and (B).

(A) Foam having a thickness of 0.05 to 1.5mm

(B) A thickness of 25 to 250 μm and a surface resistivity of 1 × 10¹¹Films above Ω

(15) The method for producing a laminate according to item (14), wherein the foam has a thickness of 0.05 to 0.5 mm.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the laminate and the production method thereof of the present invention, a laminate can be provided which can be processed as desired without deforming a foam when a foam having a small thickness is subjected to various kinds of processing. Further, the film can be appropriately peeled from the laminate, and the foam can be easily used alone. Further, by forming the laminate without using an adhesive, the possibility of the adhesive remaining in the foam after the film is peeled can be eliminated.

Drawings

Fig. 1 is a schematic configuration diagram showing a method for manufacturing a laminate according to an embodiment of the present invention.

Detailed Description

The present invention will be described in detail below together with embodiments.

The thickness of the sheet-like foam used in the present invention is 0.05 to 1.5 mm. If the thickness of the foam is less than 0.05mm, the impact absorbability and the cushioning property are insufficient. On the other hand, if the thickness exceeds 1.5mm, it is not preferable because thinning of the electronic/electric device cannot be achieved particularly when the electronic/electric device is used to fix components constituting the electronic/electric device to the device body. More preferably, the thickness is in the range of 0.05 to 0.5 mm.

The foam used in the present invention is preferably mainly composed of an olefin resin, and particularly preferably composed of a polyolefin resin. The polyolefin resin is not particularly limited, and examples thereof include polyethylene resins typified by low-density polyethylene, high-density polyethylene, linear low-density polyethylene, and ultra-low-density polyethylene (the density is defined as follows; ultra-low density: less than 0.910 g/cm)³And low density: 0.910g/cm³Above and 0.940g/cm³The following, high density: greater than 0.940g/cm³And 0.965g/cm³The above-mentioned copolymer containing ethylene as a main component includes, for example, an ethylene- α -olefin copolymer obtained by polymerizing ethylene with α -olefin having 4 or more carbon atoms (for example, ethylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene, and the like), an ethylene-vinyl acetate copolymer, and the like, and the polyolefin-based resin is more preferably a low-density polyethylene, a linear low-density polyethylene, a polyethylene-based resin such as an ultra-low-density polyethylene, an ethylene- α -olefin copolymer, an ethylene-vinyl acetate copolymer, further preferably a low-density polyethylene, a linear low-density polyethylene, an ultra-low-density polyethylene, and the like.

In addition, other thermoplastic resins other than the polyolefin-based resin may be added as long as the properties of the foam are not significantly impaired. Examples of the thermoplastic resin other than the polyolefin resin include, in the case of a resin containing no halogen, acrylic resins such as polystyrene, polymethyl methacrylate and styrene-acrylic acid copolymer, cellulose derivatives such as styrene-butadiene copolymer, ethylene-vinyl acetate copolymer, polyvinyl acetate, polyvinyl alcohol, polyvinyl acetal, polyvinylpyrrolidone, petroleum resin, cellulose acetate, cellulose nitrate, methyl cellulose, hydroxymethyl cellulose and hydroxypropyl cellulose, polyolefins such as low molecular weight polyethylene, high molecular weight polyethylene and polypropylene, saturated alkyl polyester resins, polyethylene terephthalate, polybutylene terephthalate and polyarylate, aromatic polyester resins such as polyamide resin, polyacetal resin, polycarbonate resin, and the like, Polyester sulfone resins, polyphenylene sulfide resins, polyether ketone resins, copolymers having a vinyl polymerizable monomer and a nitrogen-containing vinyl monomer, and the like. Further examples of the thermoplastic elastomer include polystyrene-based thermoplastic elastomers (SBC, TPS), polyolefin-based thermoplastic elastomers (TPO), vinyl chloride-based thermoplastic elastomers (TPVC), polyurethane-based thermoplastic elastomers (TPU), polyester-based thermoplastic elastomers (TPEE, TPC), polyamide-based thermoplastic elastomers (TPAE, TPA), polybutadiene-based thermoplastic elastomers (RB), Hydrogenated Styrene Butadiene Rubbers (HSBR), block copolymers such as styrene/ethylenebutylene/olefin crystalline block polymers (SEBC), olefin crystalline/ethylenebutylene/olefin crystalline block polymers (CEBC), styrene/ethylenebutylene/styrene block polymers (SEBS), Olefin Block Copolymers (OBC), polyolefin-vinyl compound-based graft copolymers, polyolefin-amide-based graft copolymers, α -olefin copolymers, poly (meth) acrylates, poly (meth, And elastomers such as graft copolymers including polyolefin-acrylic graft copolymers and polyolefin-cyclodextrin graft copolymers.

In addition, in the case of the resin containing halogen, polyvinyl chloride, polyvinylidene 1, 1-dichloroethylene, polychlorotrifluoroethylene, poly 1, 1-difluoroethylene resin, fluorocarbon resin, perfluorocarbon resin, solvent-soluble perfluorocarbon resin, and the like can be given. These thermoplastic resins other than the polyolefin-based resin may be one kind or may include a plurality of kinds. In particular, for the purpose of imparting flexibility and impact absorbability, it is preferable to add an elastomer, and the type and amount can be selected according to desired physical properties.

The foam used in the present invention may contain additives such as phenol-based, phosphorus-based, amine-based, sulfur-based antioxidants, metal damage preventing agents, fillers such as mica and talc, bromine-based, phosphorus-based flame retardants, flame retardant aids such as antimony trioxide, antistatic agents, lubricants, pigments, polytetrafluoroethylene, and the like, as long as the effects of the present invention are not impaired.

Further, the foam used in the present invention may be colored black. As the black colorant used when the coloring is black, for example, any known colorant such as carbon black (furnace black, channel black, acetylene black, thermal black, lamp black, etc.), graphite, copper oxide, manganese dioxide, aniline black, perylene black, titanium black, cyanine black, activated carbon, ferrite (nonmagnetic ferrite, magnetic ferrite, etc.), magnetite, chromium oxide, iron oxide, molybdenum disulfide, chromium complex compounds, composite oxide-based black pigments, anthraquinone-based organic black pigments, and the like can be used. Among them, carbon black is preferable from the viewpoint of cost and availability.

The black coloring agent may be used alone or in combination of 2 or more. The amount of the black colorant used is not particularly limited, and may be adjusted as appropriate so as to impart desired optical properties to the double-sided pressure-sensitive adhesive sheet of the present invention.

The foam used in the present invention preferably has an apparent density of 100kg/m³～500kg/m³. If the apparent density is less than 100kg/m³This is not preferable because the strength of the foam is lowered, wrinkles and the like are likely to occur during processing, and the impact absorbability is lowered. If it exceeds 500kg/m³It becomes hard and the cushioning property is lowered, which is not preferable. More preferably 200kg/m³～400kg/m³The range of (1).

The foam used in the present invention may be any of a crosslinked foam (referred to as a crosslinked foam) and an uncrosslinked foam (referred to as an uncrosslinked foam), and an appropriate foam may be selected depending on the application and shape. However, a crosslinked foam is preferred because the surface of the resin foam has smoothness and heat resistance is improved, and the produced foam can be further made into a thin film by stretching or rolling. The degree of crosslinking of the crosslinked foam is preferably in the range of 5 to 50%.

The surface resistivity of the foam used in the present invention is not particularly limited, but is preferably 1 × 10¹⁰Omega. or more, if the surface resistivity is less than 1 × 10¹⁰Omega, the adhesion with the membrane is reduced, therefore is not preferred, more preferably 1 × 10¹²Omega or more. In order to adjust the surface resistivity, it is preferable to use a polyolefin resin as a main component and add an antistatic agent or the like as needed. Examples of such antistatic agents include monomeric antistatic agents such as N, N-bis (hydroxyethyl) alkylamine, alkylallyl sulfonate and alkylsulfonate, and 1-propyl-3-methylpyridineBis (trifluoromethane) sulfonate, 1-butyl-3-methylpyridineExamples of the antistatic agent include polymeric antistatic agents such as trifluoromethanesulfonate plasma liquids, polyethylene oxides, polypropylene oxides, polyethylene glycols, polyester amides, polyether ester amides, ethylene-methacrylic acid copolymers and other plasma crosslinked polymers, quaternary ammonium salts such as polyethylene glycol methacrylate copolymers, and copolymers of olefin blocks and hydrophilic blocks described in Japanese patent laid-open No. 2001-278985.

The center line surface roughness Ra of the foam used in the present invention is preferably 30 μm or less. If the surface roughness of the foam exceeds 30 μm, the foam and the film laminate, when forming, easily in the interface of air, adhesion to reduce the tendency, therefore is not preferred. More preferably 25 μm or less.

As a method for producing the foam used in the present invention, a conventionally known method can be used. Examples of the method include a method for producing an electron beam crosslinked foam, which comprises molding a resin composition into a sheet using a thermal decomposition type foaming agent, irradiating the sheet with ionizing radiation to crosslink the resin, and heating the sheet to a temperature not lower than the decomposition temperature of the foaming agent to obtain a foam; a process for producing a chemically crosslinked foam, which comprises molding a resin composition into a sheet together with a thermal decomposition type foaming agent and an organic peroxide, and then heating the sheet to foam the resin while crosslinking the resin; and a method for producing an extruded foam, in which a supercritical carbon dioxide gas, a supercritical nitrogen gas, a supercritical butane gas, or the like is injected from the middle of an extruder and extruded from a die to obtain a foam.

The foam obtained by further thinning the foam produced by these methods may be preferably used alone or in combination of a plurality of the following processes: slicing processing for thinning the film by dividing the film in the thickness direction; a drawing process of heating and drawing uniaxially or biaxially; and compression processing in which the heated foam is sandwiched between rollers and the like.

The average cell diameter of the foam used in the present invention is not particularly limited, but is preferably small from the viewpoint of the smoothness of the surface, the improvement of adhesion when a laminate is produced, and flexibility. If the amount is too small, the resin must be highly viscous, which significantly reduces productivity. From such a viewpoint, the average cell diameter of the foam is preferably in the range of 20 to 400 μm, and more preferably in the range of 20 to 200 μm.

The average cell diameter of the foam was calculated as follows. The cross section of the foam sheet was observed at a magnification of 50 times using a Scanning Electron Microscope (SEM) (manufactured by hitachi ハイテクノロジーズ, ltd., S-3000N), and the cell diameter (diameter) was measured using the obtained image and measurement software. The cell diameter was measured in each of the longitudinal direction (MD) and the width direction (TD) within 1.5mm × 1.5mm of the captured image, and the average cell diameter in each direction was calculated and the average value thereof was defined as the average cell diameter. The measurement was performed in 10 fields and obtained as an arithmetic mean.

Next, a film used for the laminate of the present invention will be described.

The thickness of the film used in the present invention is in the range of 25 to 250 μm. If the thickness is less than 25 μm, wrinkles are likely to occur in the laminate during cutting for adjusting the laminate to an optimum width, and the laminate is likely to be deformed during punching, which results in a reduction in workability. In the case of more than 250 μm, there is no economical justification. The film may be either a stretched film or an unstretched film, but a biaxially stretched film is most preferable in order to prevent deformation of the laminate.

The surface resistivity of the film used in the present invention needs to be 1 × 10¹¹Omega or more, preferably 1 × 10¹⁸Omega. or less, if the surface resistivity is less than 1 × 10¹¹Omega, in the foam laminated layer when the potential disappears, and can not be adhered to the foam. The surface resistivity of the film can be adjusted by the amount of the antistatic agent added in the resin composition constituting the film. In the case of adding an antistatic agent, a known antistatic agent can be used.

The material of the film used in the present invention is not particularly limited, but it is preferably mainly composed of an olefin-based resin in order to maintain the potential of the laminate in an appropriate range and from the viewpoint of economic rationality. Examples of the polyolefin resin include polyethylene resins represented by low-density polyethylene, high-density polyethylene, linear low-density polyethylene, and ultra-low-density polyethylene (the density is defined as follows; ultra-low density: less than 0.910 g/cm)³And low density: 0.910g/cm³Above and 0.940g/cm³The following, high density: greater than 0.940g/cm³And 0.965g/cm³Hereinafter), a copolymer containing ethylene as a main component, a polypropylene resin typified by homopolypropylene, an ethylene-propylene random copolymer, an ethylene-propylene block copolymer, or the like, and any of mixtures thereof may be used. Among them, a film mainly composed of polypropylene having high rigidity is most preferable from the viewpoint that wrinkles and the like are not easily generated when the laminate is processed. Further, even if the propylene homopolymer is used, the propylene homopolymer may contain other unsaturated hydrocarbons within a range not impairing the object of the present inventionCopolymerization components, etc., polymers other than propylene alone may also be blended. Examples of such a copolymerization component and a monomer component constituting the blend include ethylene, propylene (in the case of a copolymerized blend), 1-butene, 1-pentene, 3-methylpentene-1, 3-methylbutene-1, 1-hexene, 4-methylpentene-1, 5-ethylhexene-1, 1-octene, 1-decene, 1-dodecene, vinylcyclohexene, styrene, allylbenzene, cyclopentene, norbornene, and 5-methyl-2-norbornene. From the viewpoint of dielectric breakdown resistance and rigidity, the amount of copolymerization or blending is preferably less than 1 mol% in the case of copolymerization, and preferably less than 10 mass% in the case of blending.

Next, a laminate of the present invention will be explained.

The laminate of the present invention requires that the foam and the film be directly bonded to each other without using an adhesive. In the present invention, the direct bonding is achieved by providing an electric charge to either the foam or the film and utilizing the electrostatic adhesion of the electric charge. Therefore, after the film is peeled from the laminate of the present invention, no adhesive is present on the film side surface of the foam.

The laminate of the present invention can be assembled to an electronic/electric device case after various processes such as cutting and punching, and particularly, the foam body in a state where the film is peeled from the laminate can be assembled as a layer having good cushioning properties and impact absorbability. As the assembly form of the foam, various forms are adopted such as providing an adhesive layer on the opposite surface of the foam on the film side, providing a micro adhesive layer on the opposite surface of the film side once and aligning with the case, and then peeling the micro adhesive layer to provide an adhesive layer, or further providing an adhesive layer on the surface of the foam on the film side after peeling the film. However, if the adhesive is present on the surface of the foam in advance, particularly if the adhesive remains on the surface of the foam on the film side after the film is peeled off, there is a possibility that problems such as air entry at the interface with the adhesive applied later, or a reduction in appearance are liable to occur, and this is not preferable.

Further, the foam has a low density and therefore a low material strength, and if the adhesive layer provided on the foam or remaining on the foam is removed, the foam may be damaged. It is therefore also difficult to remove the adhesive layer already present before it is desired to replace it.

On the other hand, in the laminate of the present invention, since the foam and the film are directly bonded without using an adhesive, the adhesive is not present on the surface of the foam on the film side after the film is peeled off, and an adhesive layer suitable for the application and the site where the foam is used can be easily provided on the opposite surface of the foam on the film side supported by the film in the laminate form.

Conventionally, in general, when an adhesive layer is provided on the surface of a foam, a method of applying a liquid containing a solvent and an adhesive to a base material such as a film or a release paper, drying the base material in an oven or the like, bonding the base material to the foam, and removing the film or the release paper is known. Since the foam is low in density and strength and therefore tends to elongate in a heated state, a method of applying an adhesive to a film or a release paper and drying and then bonding the film or the release paper can improve the production speed as compared with a method of applying a solution containing an adhesive to the foam side, and is preferably used. In this process, if a film is directly bonded to the surface of the foam that is not bonded to the adhesive without the adhesive, deformation of the foam due to winding tension or the like can be prevented.

In this way, in the present invention, by forming the foam and the film into a laminate directly joined without an adhesive, various processing can be easily performed.

In the laminate of the present invention, the peel strength between the foam and the film is in the range of 10mN/25mm to 100mN/25 mm. If the peel strength of the foam and the film is less than 10mN/25mm, the foam and the film are peeled off in the process of subjecting the laminate to various kinds of processing, and therefore, it is not preferable, and if it exceeds 100mN/25mm, the foam may be deformed when the film is peeled off, and therefore, it is not preferable. More preferably, it is in the range of 25mN/25mm to 100mN/25 mm. The peel strength between the foam and the film can be controlled by optimizing the conditions of the foam, the surface resistivity of the film, the surface roughness, the discharge amount, and the like.

As described above, the surface resistivity of the foam used in the present invention is preferably 1 × 10¹⁰Omega or more, if the surface resistivity of the film used in the present invention is 1 × 10¹¹However, if both materials have low surface resistivity, the adhesion strength between the foam and the film in the laminate may not fall within the above range, and therefore, the surface resistivity is 1 × 10 as a preferable combination¹⁶～1×10¹⁸Omega foam and surface resistivity of 1 × 10¹¹～1×10¹⁴Laminate of omega-form films and having surface resistivity of 1 × 10¹⁰～1×10¹⁵Omega foam and surface resistivity of 1 × 10¹⁶～1×10¹⁸A laminate of Ω films is preferable because appropriate adhesion strength can be obtained, which can achieve the above peel strength range.

The laminate of the present invention preferably has a potential in the range of-30 to +30 kV. If the absolute value of the potential is higher than ± 30kV, the potential is too high and dust in the surrounding environment is liable to adhere thereto, and in addition, self-discharge or the like is liable to occur, which is not preferable. More preferably in the range of-15 to +15kV, and still more preferably in the range of-10 to +10 kV.

In the laminate of the present invention, the surface of the film that is in contact with the foam is preferably charged. In order to make the film and the foam body through the electrification and close contact, preferably to the film or foam body, or both of them is charged treatment, but if the foam body is charged and high voltage treatment, if easy to generate pin hole defects, so preferably to make the film and the foam body close contact surface electrification. Further, either the surface of the film that is in close contact with the foam or the surface that is not in close contact with the foam may be subjected to electrification (even in the case where the surface that is not in close contact with the foam is subjected to electrification, the surface that is in close contact with the foam is electrified as a result), but in order to increase the adhesion strength, it is preferable to electrify the surface of the film that is in close contact with the foam.

In the laminate, which surface is charged can be confirmed by a method called a powder image method, in which toner used in a copying machine is ejected (electrostatic ハンドブック (handbook), published in 1981, electrostatic encoding, p.373). The powder imaging method is a method in which charged colored fine particles are suspended in the vicinity of a charged body and are adhered and developed by electrostatic force. As a developing material used in the powder image method, a powder toner generally used in a color copying machine is suitable. Preferably, the average particle diameter is several μm to several tens of μm. In addition, since the adhesion of the powder changes depending on the ambient humidity as the operation environment, the reproducibility is good when evaluated in a fixed environment such as a humidity of 40 to 60%.

For example, the following evaluation conditions can be applied.

Positive charging toner:

color: red colour

Particle size: weight average particle size: 14.8 μm (6 μm or less: 0.2 wt%, 25 μm or more: 1.8 wt%)

Specific load: -1.2. mu.C/g

Negative chargeable toner:

color: blue color

Particle size: weight average particle size: 12.5 μm (less than 6 μm: 0.8 wt%, greater than 20 μm: 1.6 wt%)

Specific load: 23.1. mu.C/g

The average particle diameter of the toner shown here is a value measured by using a pore tube having a diameter of 100 μm, manufactured by COULTER corporation, multisisizerii. The specific charge is a value measured by an air stripping method charge measuring apparatus (model TB-500 manufactured by Toshiba ケミカル). Specifically, the toner to be measured and the iron powder carrier (TSV-200R, パウダーテック) were mixed in a ratio of 1: 19, and only 0.2g of the powder sample stirred for 5 minutes by the ball mill was put into the measuring unit of the above-mentioned electric charge measuring apparatus, and the blowing pressure was set to 0.5kg/cm²The blowing time was 60 seconds, and was determined by dividing the value measured using a 400-mesh stainless steel screen by the weight of the toner (0.2g × 1/20 ═ 0.01 g).

Next, a method for producing a laminate of the present invention using the foam and the film will be described with reference to fig. 1, which is one of preferred embodiments.

The method for producing the laminate 3 of the present invention needs to sequentially include the following steps: a charging step of charging either the foam 2 or the film 1 in a sheet form by applying an electric charge thereto; and a bonding step for bonding the foam to the film. The charging step and the adhesion step may be performed continuously with the step of producing the foam, or may be performed after the foam is once wound.

A charging method of the charging device 4 for charging either the foam 2 or the film 1 by applying an electric charge thereto is not particularly limited, and examples thereof include (1) a method in which a grounded plate electrode is superposed on one surface of the foam 2 or the film 1, a needle electrode or a wire electrode electrically connected to a direct-current high-voltage power supply is arranged at a predetermined interval on the other surface side of the foam 2 or the film 1, corona discharge is generated by concentrating an electric field at the tip of the needle electrode or in the vicinity of the surface of the wire electrode, and air is ionized to be charged; (2) a method of charging the foam 2 or the film 1 by applying a dc or pulse-like high voltage to the foam 2 or the film 1 by sandwiching the foam 2 or the film 1 between a pair of plate electrodes, grounding one of the plate electrodes and connecting the other plate electrode to a high-voltage dc power supply, (3) a method of charging the foam 2 or the film 1 by irradiating the foam 2 or the film 1 with an ionizing radiation such as an electron beam or an X-ray or an ultraviolet ray to ionize the air in the vicinity, and the like, but the method of applying the corona discharge treatment (1) is most preferable as a method capable of easily injecting charges.

In the corona discharge treatment, the foam 2 or the film 1 can be electrically charged by applying a voltage of 0 to + -30 kV at a discharge distance of about 5 to 30 mm. When the foam is charged, if the applied voltage is too high, the possibility of open pores occurring when the discharge is concentrated is high, and therefore, the range of 0 to ± 20kV is preferable.

Further, the surface to be subjected to the corona discharge treatment is not limited to any one, but in order to improve the adhesion, it is more preferable to charge the surface of the foam 2 or the film 1 that is in adhesion with another material. Further, in order to uniformly adhere to the end of the product, it is necessary to make the width of the electrode wider than the width of the object to be processed, such as the film 1 or the foam 2.

Discharge amount in the case of performing electrification treatment by corona dischargePreferably 0.5 to 100J/m²The range of (1). If the discharge amount is less than 0.5J/m²The foam 2 and the film 1 adhesion is reduced, therefore is not preferred, if more than 100J/m²This is not preferable because a defect of open pores such as pinholes may occur in the film 1 or the foam 2. More preferably 1.0 to 100J/m²The range of (1).

The discharge amount is a value calculated by the following equation. Wherein the width of the electrode for discharge is wider than the width of the film 1 or the foam 2.

Discharge capacity (J/m)²) Electric power (W)/{ linear velocity (m/s) × width (m) of film or foam }

The step of bringing the foam 2 into close contact with the film 1 can be performed by bringing another material into contact with the foam 2 or the film 1 subjected to the electrification treatment to bring the foam and the film into close contact with each other electrostatically, but in order not to allow air to enter the close contact surface, it is preferable to press the foam and the film with rolls 6a and 6b, a plate, or the like as shown in fig. 1. In particular, from the viewpoint of continuous productivity, it is most preferable to use the rolls 6a and 6b to cause adhesion. The material of the rolls 6a and 6b is not particularly limited, and conventionally known metal-metal rolls, rubber-metal rolls, and the like can be used.

In the present invention, it is particularly preferable that the foam 2 and the film 1 are adhered to each other, and then the following steps are provided: the outer surface of the foam 2 or the film 1 is provided with a charge having a polarity opposite to the charge of the bonding surface of the foam 2 and the film 1, thereby increasing the bonding force. For example, after a laminate 3 is produced by laminating the film 1 on the side of the film 1 that is in close contact with the foam 2 by applying a positive charge to the foam 2 by a charging device 4 as shown in fig. 1 and performing a corona discharge treatment, the outer surface of the foam 2 is irradiated with a negative charge by a charge removal device 5, whereby the charge is neutralized, the potential of the laminate 3 can be reduced, and the close contact between the foam 2 and the film 1 can be improved. It is also one of preferable modes that the supply of the electric charges of opposite polarities is performed in a state where positive and negative electric charges are mixed. The means for supplying the opposite-polarity charges in this way is not particularly limited, and examples thereof include a high-voltage application type static electricity removing device, a self-discharge type static electricity removing device, a device which irradiates ionizing radiation such as soft X-rays and α -rays, and the like. In addition, from the viewpoint of efficiently charging the foam 2 or the film 1, it is preferable to provide the counter electrode roll 8 on the surface facing the charging device 4 with the foam 2 or the film 1 interposed therebetween. By providing the counter electrode roll 8, an electric field can be formed between the counter electrode roll 8 and the discharge electrode of the charging device 4, and ions generated by corona discharge can be efficiently sent to the foam 2 or the film 1 on the roll, thereby improving the efficiency of the charging process. The material of the counter electrode roller 8 is not particularly limited, and any of a metal roller and a rubber roller can be used. However, in the case of a rubber roller, the process efficiency is lowered if the roller is charged, and therefore, rubber having conductivity is preferable.

In order to produce the laminate of the present invention, it is preferable to provide an unwinder for unwinding the foam 2 and the film 1 at a constant tension and speed, a guide roller 7 for applying an appropriate tension to the foam 2 and the film 1 and preventing meandering, a cutter such as a shear knife or a razor for cutting the laminate 3 to a desired width, a winder for winding the laminate, and the like.