KR20200131218A - Laminate and its manufacturing method - Google Patents

Abstract

A laminate in which a film is laminated on at least one surface of a sheet-like foam and satisfies the following requirements (A) to (E), and a method for producing the same.
(A) the thickness of the foam is 0.05 to 1.5 mm, (B) the thickness of the film is 25 to 250 μm, (C) the surface resistivity of the film is 1×10 ¹¹ Ω or more, (D) the foam and the film do not intervene with an adhesive. (E) The peeling strength of the foam and the film is 10mN/25mm-100mN/25mm.
According to the present invention, when various processing is performed on a thin foam, it is possible to provide a laminate that is capable of desired processing without deformation of the foam, and the film can be appropriately peeled from the laminate, and the foam can be easily removed by itself. Can be used. In addition, since a laminate is formed without interposing an adhesive, the possibility that the adhesive remains in the foam after peeling the film can be eliminated.

Description

Laminate and its manufacturing method

The present invention relates to a laminate in which a sheet-shaped foam and a film are laminated, and to a method for manufacturing the same.Especially, even if it is a thin foam, by laminating the film, it enables desired processing as a laminate without deformation without deformation, and easy from a laminate. In addition, it relates to a laminate and a method for producing the same, in which the film can be peeled off appropriately, and thus the foam can be used as a single body.

Foams, for example, polyolefin-based resin foams, have uniform and fine closed cells, and have excellent buffering properties and processability, and are therefore used in various applications. Such a foam can be easily thinned by stretching or slicing, and since it maintains good buffering properties and shock absorption properties even in a thinned state, it is suitably used as a buffer material for electronic and electrical devices such as mobile phones. If the foam is used as a foam alone, it is used in a state in which an adhesive layer or the like is formed on one or both sides of the foam. In addition, regardless of the presence or absence of an adhesive layer, these foams are subjected to various processing such as slit processing to adjust the width according to the shape of electronic and electrical devices, punching processing to match the shape, and then housings of electronic and electrical devices. It is assembled and used as a cushioning material.

The foam used as described above is usually very thin, with a thickness of about 0.05 to 1.5 mm, and also about 0.05 to 0.5 mm, and has a low density to impart a buffering property and thus has a low strength. When attempting to do so, there may be problems such as spreading and deforming due to the tension at the time of conveyance, or wrinkles entering. In addition, for the purpose of improving shock absorption, etc., in the case of a resin itself having adhesiveness, such as an ultra-low density polyethylene or an ethylene-vinyl acetate copolymer, when the foam is wound in a roll shape and stored for a long time, the foams are in close contact with each other and are called blocking. There is also a problem in that an excessive tension is required in the foam when peeling and unwinding in order to use the foam. In this way, there is a concern that various problems such as deformation, wrinkles, blocking, etc. may occur when processing a foam having a thin thickness and particularly a low density.

In order to solve these problems, a method of winding up a foam and a release paper (concept including a release film) together is considered (for example, Patent Document 1). However, when only the release paper is used, particularly in the case of a thin foam, there is a concern that problems such as air enters between the foam and the release paper and the foam is deformed. In addition, there is a method such as bonding a film with an adhesive to the foam and winding it up, but even if the film is peeled and obtained to use only the foam layer, the adhesive partially adheres to the foam layer side, and the desired foam is used. There is a concern that problems such as difficult to obtain.

WO2016/093133A1 publication

Therefore, the subject of the present invention is to enable the desired processing without deformation of the foam when various processing is performed on a foam having a thin thickness, and the film can be easily and appropriately peeled from the laminate, causing a problem. It is to provide a laminate that allows the foam to be used alone, and a method for producing the laminate.

As a result of intensive examination, the inventors of the present invention have found that the above-described problem can be solved by the laminate of the following description and a method for producing the same.

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

(1) A laminate in which a film is laminated on at least one side of a sheet-like foam, and the laminated body satisfies the following requirements (A) to (E).

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

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

(C) The surface resistivity of the film is 1×10 ¹¹ Ω or more

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

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

(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 25 mN/25 mm to 100 mN/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 potential of the laminate is in the range of -15 to +15 kV.

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

(7) The laminate according to any one of (1) to (6), wherein the foam has an apparent density in the range of 100 kg/m 3 to 500 kg/m 3.

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

(9) The laminate according to any one of (1) to (8), wherein the foam from which the film has been peeled off is used to fix the components constituting the electronic/electric device to the device body.

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

(10) A method for producing a laminate in which a sheet-shaped foam and a film are in close contact, characterized in that it has a charging step in which electric charges are applied to one of the foam or film to be charged, and an adhesion step in which the foam and the film are brought into close contact with each other in this order. Method for producing a laminated body to be.

(11) In (10), after the adhesion step, a charge having a polarity opposite to that on the adhesion surface of the foam or film is given to the outer surface of the foam or film, thereby increasing the adhesion on the adhesion surface. A method of manufacturing a laminate having a step of increasing adhesion.

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

(13) The method for producing a laminate according to any one of (10) to (12), wherein the adhesion step includes a step of compressing the foam and the film with a nip roller.

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

(A) a foam with a thickness of 0.05 to 1.5 mm

(B) A film having a thickness of 25 to 250 μm and a surface resistivity of 1×10 ¹¹ Ω or more

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

(Effects of the Invention)

According to the laminate of the present invention and a method for producing the same, it is possible to provide a laminate capable of desired processing without deformation of the foam when various processing is performed on a foam having a thin thickness. In addition, the film can be appropriately peeled from the laminate, and the foam can be easily used alone. Moreover, by setting it as a laminated body without interposing an adhesive, the possibility that an adhesive remains in the foam after peeling a film can be eliminated.

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

Hereinafter, the present invention will be described in detail together with the embodiments.

The sheet-shaped foam used in the present invention has a thickness of 0.05 to 1.5 mm. If the thickness of the foam is less than 0.05 mm, the shock absorption and cushioning properties will be insufficient. On the other hand, when the thickness exceeds 1.5 mm, especially when it is used to fix the components constituting the electronic/electric apparatus to the apparatus main body, it is not preferable to achieve a thinner of the electronic/electric apparatus. A more preferable range is 0.05 to 0.5 mm in thickness.

It is preferable that the foam used in the present invention is mainly composed of an olefin-based resin, particularly a polyolefin-based resin. Although it does not specifically limit as a polyolefin-type resin, For example, polyethylene-type resin represented by low-density polyethylene, high-density polyethylene, linear low-density polyethylene, ultra-low-density polyethylene, etc. (the definition of the density here is as follows. Ultra-low density: 0.910 g /Cm 3 or less, low density: 0.910 g/cm 3 or more and 0.940 g/cm 3 or less, high density: 0.940 g/cm 3 or more and 0.965 g/cm 3 or less) or a copolymer containing ethylene as a main component, or homopolypropylene, ethylene-propylene random Polypropylene resins typified by copolymers and ethylene-propylene block copolymers, and the like, and any of a mixture thereof may be used. Examples of the ethylene-based copolymer include ethylene and an 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, etc.) are polymerized to obtain an ethylene-?-olefin copolymer, an ethylene-vinyl acetate copolymer, and the like. The polyolefin-based resin is more preferably a polyethylene-based resin such as low-density polyethylene, linear low-density polyethylene, and ultra-low-density polyethylene, an ethylene-α-olefin copolymer, and an ethylene-vinyl acetate copolymer. More preferably, they are low density polyethylene, linear low density polyethylene, and ultra low density polyethylene. These polyolefin resins may be either one type or a mixture of two or more types. Most preferably, low-density polyethylene, linear low-density polyethylene, ethylene-vinyl acetate copolymer alone or a mixture thereof.

In addition, other thermoplastic resins other than polyolefin resins may be added as long as the properties of the foam are not significantly impaired. Thermoplastic resins other than polyolefin resins herein are polystyrene, acrylic resins such as polymethyl methacrylate and styrene-acrylic acid copolymers, styrene-butadiene copolymers, and ethylene-vinyl acetate copolymers for resins that do not contain halogen. Polymer, polyvinyl acetate, polyvinyl alcohol, polyvinyl acetal, polyvinylpyrrolidone, petroleum resin, cellulose, cellulose acetate, cellulose nitrate, methylcellulose, hydroxymethylcellulose, cellulose derivatives such as hydroxypropylcellulose, low molecular weight Polyolefin such as polyethylene, high molecular weight polyethylene, polypropylene, saturated alkyl polyester resin, polyethylene terephthalate, polybutylene terephthalate, aromatic polyester resin made of polyarylate, polyamide resin, polyacetal resin, polycarbonate resin, poly Ester sulfone resin, polyphenylene sulfide resin, polyether ketone resin, a copolymer having a vinyl polymerizable monomer and a nitrogen-containing vinyl monomer, and the like. In addition, polystyrene-based thermoplastic elastomer (SBC, TPS), polyolefin-based thermoplastic elastomer (TPO), vinyl chloride-based thermoplastic elastomer (TPVC), polyurethane-based thermoplastic elastomer (TPU), polyester-based thermoplastic elastomer (TPEE, TPC), polyamide Thermoplastic elastomer (TPAE, TPA), polybutadiene thermoplastic elastomer (RB), hydrogenated styrene butadiene rubber (HSBR), styrene/ethylenebutylene/olefin crystal block polymer (SEBC), olefin crystal/ethylenebutylene/olefin crystal block Block copolymers such as polymer (CEBC), styrene/ethylenebutylene/styrene block polymer (SEBS), and olefin block copolymer (OBC), polyolefin-vinyl graft copolymer, polyolefin-amide graft copolymer, alpha-olefin And elastomers such as graft copolymers such as copolymers, polyolefin-acrylic graft copolymers, and polyolefin-cyclodextrin graft copolymers.

In addition, in the resin containing halogen, polyvinyl chloride, polyvinylidene chloride, polyethylene trifluoride, polyvinylidene fluoride resin, fluorocarbon resin, perfluorocarbon resin, solvent-soluble perfluorocarbon resin, etc. Can be lifted. Thermoplastic resins other than these polyolefin resins may be one type or may be contained in plural types. In particular, for the purpose of imparting flexibility and shock absorption, it is a preferred form to add an elastomer, and the type and amount are selected according to the desired physical properties.

In the foam used in the present invention, within the scope of not impairing the effects of the present invention, antioxidants such as phenolic, phosphorus, amine and sulfur, metal detoxification agents, fillers such as mica or talc, bromine and phosphorus, etc. Flame retardants, flame retardant aids such as antimony trioxide, antistatic agents, lubricants, pigments, and additives such as polytetrafluoroethylene may be added.

Further, the foam used in the present invention may be colored black. Examples of black colorants used when coloring black include carbon black (furnace black, channel black, acetylene black, thermal black, lamp black, etc.), graphite, copper oxide, manganese dioxide, aniline black, perylene black, and titanium black. , Cyanine black, activated carbon, ferrite (non-magnetic ferrite, magnetic ferrite, etc.), magnetite, chromium oxide, iron oxide, molybdenum disulfide, chromium complex, complex oxide black pigment, anthraquinone organic black pigment, etc. I can. Among them, carbon black is preferable from the viewpoint of cost and availability.

Black colorants can be used alone or in combination of two or more. The amount of the black colorant to be used is not particularly limited, and may be an amount appropriately adjusted so as to impart desired optical properties to the double-sided adhesive sheet of the present invention.

It is preferable that the apparent density of the foam used in the present invention is 100 kg/m 3 to 500 kg/m 3. If the apparent density is less than 100 kg/m 3, the strength of the foam decreases, wrinkles and the like tend to occur at the time of processing, and the shock absorbency decreases, which is not preferable. When it exceeds 500 kg/m3, it becomes hard and the buffer property falls, which is not preferable. More preferably, it is a range of 200 kg/m 3 to 400 kg/m 3.

The foam used in the present invention may be a crosslinked foam (referred to as a crosslinked foam) or a non-crosslinked foam (referred to as a non-crosslinked foam), and an appropriate foam may be selected according to the purpose or shape. However, since the surface of the resin foam has smoothness, heat resistance is improved, and the resulting foam can be further thinned by stretching and rolling, it is preferable to use a crosslinked foam. 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 it is preferably 1×10 ¹⁰ Ω or more. If the surface resistivity is less than 1×10 ¹⁰ Ω, the adhesion to the film decreases, which is not preferable. More preferably, it is 1×10 ¹² Ω or more. In order to adjust the surface resistivity, it is a preferred form to use a polyolefin-based resin as a main component and to add an antistatic agent or the like as necessary. Examples of such antistatic agents include monomer type antistatic agents such as N,N-bis(hydroxyethyl)alkylamine, alkyl allylsulfonate, and alkylsulfonate, and 1-propyl-3-methylpyridinium bistrifluoro. Ionic liquids such as romethanesulfonate, 1-butyl-3-methylpyridinium trifluoromethanesulfonate, polyethylene oxide, polypropylene oxide, polyethylene glycol, polyesteramide, polyether esteramide, ethylene- Charging of polymer types such as ionomers such as methacrylic acid copolymers, quaternary ammonium salts such as polyethylene glycol methacrylate copolymers, and copolymers of olefinic blocks and hydrophilic blocks described in Japanese Patent Laid-Open No. 2001-278985 Inhibitors, etc. are mentioned.

It is preferable that the centerline surface roughness (Ra) of the foam used in the present invention is 30 μm or less. When the surface roughness of the foam exceeds 30 µm, air tends to enter the interface when the laminate of the foam and the film is formed, and adhesion tends to decrease, which is not preferable. More preferably, it is 25 micrometers or less.

As a method for producing the foam used in the present invention, a conventionally known method can be used. For example, an electron beam crosslinked foam obtained by molding a resin composition into a sheet shape using a thermally decomposable foaming agent, irradiating it with ionizing radiation to crosslink the resin, and then heating the sheet to a decomposition temperature or higher of the foaming agent to obtain a foam. In the same manner, a method for producing a chemically crosslinked foam in which a thermally decomposable foaming agent and an organic peroxide are formed into a sheet shape together with a resin composition, and then heated to crosslink the resin, and the carbon dioxide gas in a super boundary state from the middle of the extruder And a method of producing an extruded foam obtained by injecting nitrogen gas or butane gas and extruding from a crest to obtain a foam.

In addition, a slicing process in which the foam produced by these methods is divided in the thickness direction to form a thin film, a stretching process that uniaxially or biaxially stretches while heating, and a compression process in which the heated foam is sandwiched with a roll, etc. Also can be used preferably.

The average cell diameter of the foam used in the present invention is not particularly limited, but a smaller one makes the surface smooth, and is preferable from the viewpoint of improving the adhesiveness in the case of a laminate and flexibility. If it is attempted to be too small, it is necessary to make the resin highly viscous, which significantly reduces productivity. From this point of view, the average cell diameter of the foam is preferably in the range of 20 µm to 400 µm, more preferably in the range of 20 µm to 200 µm.

The average cell diameter of the foam is calculated as follows. The cross section of the foam sheet was observed at 50 times magnification using a scanning electron microscope (SEM) (manufactured by Hitachi High-Tech Corporation, S-3000N), and the cell diameter was measured using image and measurement software obtained. In addition, the bubble diameter is measured for each of the longitudinal direction (MD) and the width direction (TD) within the range of 1.5 mm×1.5 mm of the captured image, and the average bubble diameter in each direction is calculated, and the average value Was taken as the average cell diameter. Moreover, it measured in ten visual fields and calculated|required as an arithmetic average.

Next, the film used in 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, it is preferable because wrinkles tend to occur when slit processing is performed to adjust the laminate to the optimum width, and the workability decreases, such as easy deformation of the laminate during punching. Not. If it exceeds 250㎛, the rationality is poor in terms of economy. The film may be a stretched film or a non-stretched film, but a biaxially stretched film is most preferred in order to prevent deformation of the laminate.

The film used in the present invention needs to have a surface resistivity of 1×10 ¹¹ Ω or more, and preferably 1×10 ¹⁸ Ω or less. If the surface resistivity is less than 1×10 ¹¹ Ω, the potential is lost when laminated with the foam, and the foam cannot be brought into close contact with the foam. The surface resistivity of the film can be adjusted by the amount of the antistatic agent added to the resin composition constituting the film. When adding an antistatic agent, a known one can be used.

The material of the film used in the present invention is not particularly limited, but in order to maintain the potential of the laminate in an appropriate range, and from the viewpoint of economic rationality, it is preferable that it is mainly composed of an olefin resin. Polyolefin-based resins include polyethylene-based resins typified by low-density polyethylene, high-density polyethylene, linear low-density polyethylene, and ultra-low-density polyethylene (the definition of the density here is as follows. Ultra-low density: less than 0.910 g/cm 3, low density: 0.910 g/) Cm 3 or more and 0.940 g/cm 3 or less, high density: greater than 0.940 g/cm 3 and less than 0.965 g/cm 3 ), or a copolymer containing ethylene as a main component, or a homopolypropylene, ethylene-propylene random copolymer, or ethylene-propylene block copolymer And polypropylene resins typified by the like, and any of these mixtures may be used. Among these, a film mainly composed of polypropylene having high rigidity is most preferred from the viewpoint of making wrinkles and the like less likely to occur when processing a laminate. In addition, even if it consists of a homopolymer of propylene, it may contain the copolymerization component etc. of another unsaturated hydrocarbon, etc. within the range which does not impair the object of the present invention, and a polymer other than propylene may be blended. As a monomer component constituting such a copolymerized component or a blended product, for example, ethylene, propylene (in the case of a copolymerized blended product), 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, 5-methyl-2 -Norbornene, etc. are mentioned. It is preferable that the copolymerization amount or blending amount is less than 1 mol% in terms of dielectric breakdown resistance and rigidity, and less than 10 mass% in the blending amount.

Next, the laminate of the present invention will be described.

In the laminate of the present invention, it is necessary that the foam and the film are directly bonded without interposing an adhesive. In the present invention, this direct bonding is achieved by applying an electric charge to either the foam or the film, and electrostatic adhesion using the electric charge. Therefore, after peeling the film from the laminate of the present invention, the adhesive does not exist on the film-side surface of the foam.

The laminate of the present invention can be assembled into an electronic/electric device housing after performing various processes such as slit processing or punching, and in particular, a foam in a state in which the film is peeled from the laminate is used as a layer having good buffering properties and shock absorption properties. Can be assembled as. As for the assembly form of the foam, an adhesive layer is formed on the surface of the opposite film side of the foam, or a non-adhesive layer is once formed on the surface of the opposite film side to align with the housing, and then the non-adhesive layer is peeled off to form the adhesive layer. Various forms are adopted, such as forming or forming an adhesive layer after peeling the film on the film-side surface of the foam. However, if a pressure-sensitive adhesive is present on the surface of the foam in advance, especially if the pressure-sensitive adhesive remains on the film-side surface of the foam after peeling the film, it is easy to engage air at the interface with the pressure-sensitive adhesive applied later, or to deteriorate the appearance. It is not desirable because there is a possibility that problems such as losing may occur.

Further, since the foam has a low density, the material strength is weak, and when an attempt is made to remove the adhesive layer formed or remaining on the foam, the foam may destroy the material. Therefore, it is difficult to remove the already existing adhesive layer before newly forming the adhesive layer.

On the other hand, in the laminate of the present invention, since the foam and the film are directly bonded to each other without an adhesive, the adhesive does not exist on the film side of the foam after peeling the film, and is supported by the film in the form of a laminate. It becomes possible to easily form a pressure-sensitive adhesive layer suitable for the application or site in which the foam is used on the side of the film opposite to the foam.

Conventionally, in general, in the case of forming an adhesive layer on the surface of a foam, a liquid containing a solvent and an adhesive is applied onto a substrate such as a film or release paper, dried in an oven, etc., and then bonded to the foam to form a film or release paper. A method of removing is known. Since the foam has a low density and low strength, it increases when heated. Therefore, the production speed is increased by applying an adhesive to a film or release paper, drying and then bonding, rather than applying a solution containing an adhesive to the foam side. It is possible to improve and is preferably used. Also in this process, if a film is directly bonded to the surface of the foam that is not bonded to the pressure-sensitive adhesive without any pressure-sensitive adhesive in advance, it is possible to prevent the foam from deforming due to winding tension or the like.

As described above, in the present invention, it becomes easy to perform various processing by setting the foam and the film to be a laminate in which the foam and the film are directly bonded without interposing an adhesive.

In the laminate of the present invention, the peel strength between the foam and the film is in the range of 10 mN/25 mm to 100 mN/25 mm. If the peel strength between the foam and the film is less than 10mN/25mm, it is not preferable because the foam and the film peel off during various processing on the laminate. If it exceeds 100mN/25mm, the foam is deformed when peeling the film. This is not desirable because there is a possibility to do it. More preferably, it is the range of 25mN/25mm-100mN/25mm. The peel strength between the foam and the film can be controlled by appropriately adjusting conditions such as surface resistivity, surface roughness, and discharge amount of the foam or film.

In addition, as described above, the surface resistivity of the foam used in the present invention is preferably 1×10 ¹⁰ Ω or higher, and the surface resistivity of the film used in the present invention is 1×10 ¹¹ Ω or higher, but both materials If one having a low resistivity is used, there is a possibility that the adhesive strength between the foam and the film in the laminate will not fall within the above range. Therefore, as a preferred form of combination, a laminate of a foam having a surface resistivity of 1×10 ^{16 to} 1×10 ¹⁸ Ω, a film having a surface resistivity of 1×10 ^{11 to} 1×10 ¹⁴ Ω, and a surface resistivity of 1×10 ¹⁰ A laminate of a foam of -1×10 ¹⁵ Ω and a film having a surface resistivity of 1×10 ^{16 to} 1×10 ¹⁸ Ω is preferable because it can obtain an appropriate adhesive strength capable of achieving the above range of peel strength.

It is preferable that the potential of the laminate of the present invention is in the range of -30 to +30 kV. If the absolute value of the potential exceeds ±30 kV, it is not preferable because the potential is too high and dust in the surrounding environment tends to adhere, and self-discharge or the like tends to occur. It is more preferably in the range of -15 to +15 kV, and still more preferably in the range of -10 to +10 kV.

In the laminate of the present invention, it is preferable that the surface of the film in close contact with the foam is charged. In order to make the film and the foam come in close contact by charging, it is preferable to charge one or both of the film or foam, but if the foam is treated with a high voltage to charge it, defects such as pinholes are likely to occur. It is desirable to charge the surface being made. In addition, although the surface of the film that is in close contact with the foam or the surface that is not in close contact may be subjected to charging (even when the non-adhering surface is subjected to the charging treatment, the surface in close contact with the foam is charged as a result), but the adhesion strength In order to increase the value, it is preferable to charge the surface of the film on the side in close contact with the foam.

In the laminate, whether or not which side is charged can be confirmed by spraying toner used in a copier called the dust figure method (Electrostatic Handbook, published in 1981, The Electrostatic Society Edition, p.373). The dust figure method is a method in which charged colored fine particles are floated in the vicinity of an electric charge and attached and developed by electrostatic force. As a developer used in the dust figure method, powder toner generally used in color copiers is suitable. Preferably, the average particle diameter is several µm to tens of µm. In addition, since the adhesion force of the powder changes depending on the ambient humidity as a work environment, the reproducibility is better when evaluated under a constant environment such as 40 to 60% humidity.

For example, the following evaluation conditions can be applied.

Electrostatic Toner:

Color: red

Particle diameter: Weight average particle diameter: 14.8 μm (6 μm or less: 0.2% by weight, 25 μm or more: 1.8% by weight)

Specific charge: -1.2μC/g

Incidental Toner:

Color: blue

Particle diameter: Weight average particle diameter: 12.5 μm (6 μm or less: 0.8% by weight, 20 μm or more: 1.6% by weight)

Specific charge: -23.1 μC/g

In addition, the average particle diameter of the toner shown here is a value measured using an aperture tube having a diameter of 100 µm with MULTISIZERII manufactured by COULTER. In addition, about the specific charge, it is the value measured by the blow method charge quantity measuring apparatus (TB-500 type manufactured by Toshiba Chemical Corporation). Specifically, the toner to be measured and the iron powder carrier (TSV-200R of Powdertech Co., Ltd.) were mixed in a weight ratio of 1:19, respectively, and a powder sample after stirring for 5 minutes by a ball mill was used in the charge amount measuring device. Put only 0.2g in the measuring cell, set a blow pressure of 0.5kg/cm2 and a blow time of 60 seconds, and use a 400 mesh stainless steel mesh on a mesh screen as the weight of the toner (0.2g×1/20=0.01g). It is calculated by dividing it.

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

The manufacturing method of the laminate 3 of the present invention is to have in this order a charging step of charging and charging either of the sheet-shaped foam 2 or the film 1, and an adhesion step of bringing the foam and the film into close contact. need. The charging process and the adhesion process may be performed continuously with the process of manufacturing a foam, and may be performed after winding up the foam once.

The charging method of the charging device 4 in which any one of the foam 2 or the film 1 is charged and charged is not particularly limited, and for example, (1) the foam 2 or one side of the film 1 Overlapping the grounded flat electrode, installing a needle electrode or wire electrode electrically connected to a DC high voltage power source at predetermined intervals on the other side of the foam (2) or film (1), and the tip or wire electrode of the needle electrode A method of generating corona discharge by concentrating the electric field in the vicinity of the surface of and ionizing air to charge it, (2) holding the foam (2) or film (1) with a pair of flat electrodes, and grounding one flat electrode In addition, the other flat electrode is connected to a high-voltage DC power supply and charged by applying a DC or pulsed high voltage to the foam (2) or film (1), and (3) ionizing radiation such as electron beams or X-rays or ultraviolet rays. A method of irradiating the foam (2) or film (1) and ionizing nearby air to charge it is exemplified, but the method by corona discharge treatment in (1) is the most easily injectable method. desirable.

In the corona discharge treatment, the foam 2 or the film 1 can be charged by applying a voltage of 0 to ±30 kV to a discharge distance of about 5 to 30 mm. In the case of charging the foam, if the applied voltage is too high, the hole may be emptied when the discharge is concentrated, so it is preferable to set it in the range of 0 to ±20 kV.

In addition, the surface to be subjected to the corona discharge treatment is not limited to any surface, but it is more preferable to charge the surface of the foam 2 or the film 1 in close contact with the other material in order to increase the adhesion. Further, in order to uniformly adhere to the end of the product, it is necessary to increase the width of the electrode relative to the width of the object to be treated of the film 1 or foam 2.

It is preferable that the amount of discharge at the time of charging treatment by corona discharge is in the range of 0.5 to 100 J/m 2. If the amount of discharge is less than 0.5 J/㎡, the adhesion between the foam (2) and the film (1) decreases, which is not preferable. If the discharge exceeds 100 J/㎡, the film (1) or the foam (2) has a hole defect such as a pinhole. This is not desirable because it is likely to occur. More preferably, it is in the range of 1.0 to 100 J/m 2.

In addition, the amount of discharge is a value calculated by the following equation. However, the width of the electrode for discharging is wider than that of the film 1 or the foam 2.

Discharge amount (J/㎡) = power (W)/{line speed (m/s)×width of film or foam (m)}

As the step of bringing the foam 2 and the film 1 into close contact, it can be achieved by bringing another material into contact with the charged foam 2 or film 1 to make electrostatic contact, but air is applied to the contact surface. In order not to engage, it is preferable to press with nip rollers 6a, 6b or a plate as shown in Fig. 1. In particular, from the viewpoint of continuous productivity, it is most preferable to make close contact with the nip rollers 6a and 6b. The material of the nip rollers 6a and 6b is not particularly limited, and conventionally known metal-metal nip rollers, rubber-metal nip rollers, and the like can be used.

In the present invention, after the foam (2) and the film (1) are brought into close contact, the charge on the outer surface of the foam (2) or film (1) is opposite to the charge on the adhesion surface of the foam (2) and the film (1). It is particularly preferable to have a process of increasing adhesion by giving polarized charges. For example, a corona discharge treatment is performed by applying a static charge to the surface of the film 1 on the side in close contact with the foam 2 by the charging device 4 as shown in FIG. 1 to laminate the foam 2 Then, after forming the laminate 3, the charge is neutralized by irradiating negative charges on the outer surface of the foam 2 with the antistatic device 5 to reduce the potential as the laminate 3, and further, the foam ( It becomes possible to improve the adhesion between 2) and the film 1. In addition, it is also one of the preferred modes that the reverse polarity charge is supplied in a state in which an electrostatic charge and a negative charge are mixed. As described above, the means for imparting reverse polarity charge is not particularly limited, and examples thereof include a high-pressure applied static electricity removal device, a self-discharge static electricity removal device, and a device that irradiates ionizing radiation such as soft X-rays and α-rays. , High-pressure applied static electricity removal device by corona discharge is most preferred. In addition, from the viewpoint of efficiently charging the foam 2 or film 1, a counter roller 8 is provided on a surface facing the charging device 4 with the foam 2 or film 1 interposed therebetween. It is desirable. By installing the counter roller 8, an electric field is formed between the counter roller 8 and the discharge electrode of the charging device 4, and ions generated in the corona discharge are efficiently transferred to the foam 2 or the film 1 on the roller. It becomes possible to contact, and it becomes possible to improve the efficiency of the charging treatment. The material of the counter 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, since processing efficiency decreases when the roller is charged, it is preferable that it is a rubber having conductivity.

Others In order to manufacture the laminate of the present invention, an unwinding machine for unwinding the foam (2) and film (1) at a certain tension and speed, and applying an appropriate tension to the foam (2) and film (1) to prevent meandering, etc. It is preferable that a guide roller 7 is provided, a cutter such as a shear blade or a leather blade for cutting the laminate 3 to a desired width, a winder for winding the laminate, and the like.

Example

Hereinafter, the present invention will be described in detail by way of examples. In addition, the measurement method and the evaluation method are as shown below.

(1) thickness of foam

The thickness of the foam was measured in accordance with ISO 1923 (1981) "Measurement method for the dimension of foamed plastic and rubber." Specifically, by using a dial gauge attached with a circular measuring instrument having an area of 10 cm 2, the foam cut to a predetermined size is placed on a flat surface, and then the foam is measured by contacting the surface of the foam with a constant pressure of 10 g.

(2) the apparent density of the foam

The apparent density of the foam is a value measured and calculated according to JIS K6767 (1999) "Expanded plastic-polyethylene-test method". The thickness of the foam cut into an area of 10 cm 2 was measured, and the mass of this test piece was also weighed. The value obtained by the following equation is called the apparent density and the unit is kg/m3.

Apparent density (kg/㎥) = {mass of test piece (kg)/area of test piece 0.01 (㎡)/ thickness of test piece (m)}

(3) degree of crosslinking of foam

The measurement of the degree of crosslinking of the foam is carried out as follows. The foam is cut into about 0.5 mm x 0.5 mm, and about 100 mg is weighed with an accuracy of 0.1 mg. After being immersed in 200 ml of tetralin at a temperature of 140° C. for 3 hours, it is naturally filtered through a stainless steel mesh of 100 mesh, and the insoluble matter on the wire mesh is dried in a hot air oven at 120° C. for 1 hour. Then, it is cooled for 30 minutes in a desiccator containing silica gel, the mass of this insoluble component is precisely weighed, and the gel fraction of the foam is calculated as a percentage according to the following equation.

Crosslinking degree (%) = {mass of insoluble matter (mg)/mass of weighed foam (mg)}×100

(4) surface roughness of foam

The surface roughness of the foam was measured by a surface roughness measuring instrument (model: SE-2300, manufactured by Kosaka Laboratory Ltd.), and the center line average roughness (Ra) was determined. However, the measurement site measured the surface to be laminated with the film of the foam. The measurement direction is within the plane of the foam sheet, the measurement is performed in two directions in the longitudinal direction and in a direction perpendicular to it, and the number of measurements is once for each. The highest value among these measured values was taken as the surface roughness of the foam.

(5) film thickness

The thickness of the film was determined by measuring the thickness of 10 arbitrary points using a digital micrometer µ-mate M-30 manufactured by Sony Manufacturing Systems Corporation, and the average value was taken as the film thickness.

(6) Surface resistivity of foam and film

The surface resistivity was measured using R8340 manufactured by Advantest. The foam was cut into 50 x 50 mm, left to stand for 24 hours in an environment at a temperature of 20° C. and a humidity of 50% RH, and then the applied voltage of 100 V and the surface resistivity after 1 minute were used. It was set as the average value measured twice.

(7) Peel strength of laminate

The peel strength of the laminated body was cut so that the length of the product in the longitudinal direction (winding direction in Fig. 1) was 150 mm and the width was 25 mm with respect to the created laminate to obtain a test piece. One end of this test piece was inserted and fixed for each laminate, and only the film of the laminate was fixed with the other scissors, and using TENSILON UCT-500 manufactured by Orientec Corporation, the speed was 200 mm/min, the peeling angle was 180°, and the peeling was performed. The film was pulled out at a distance of 80 mm to perform a peel test. The obtained peel strength was the maximum peel strength value within 80 mm of peel distance, and the average value calculated|required from the value measured twice was made into the peel strength.

(8) potential of the laminate

The electric potential of the laminate was measured using a digital electrostatic electric potential measuring device KSD-1000 manufactured by Kasuga Electric Works Ltd. The electrometer was applied and measured from the film side and the foam side of the laminate, and the average value was taken as the potential of the laminate.

(9) Evaluation of the properties of the laminate (slit workability)

The resulting laminate was subjected to slit processing to evaluate the presence or absence of wrinkles. A leather blade was installed every 140 mm in a slit processing machine that was connected to a mechanical motor to unwind and wound up at an arbitrary speed, and slit was performed at a processing speed of 40 m/min, and six products having a width of 140 mm were simultaneously collected. One of the six collected products was taken as pass (○), and if even one had wrinkles, it was set as reject (x).

The foams and films used in Tables 1 and 2 are shown.

[Reference Example 1]

With respect to 100 parts by weight of a linear low-density polyethylene resin having a density of 925 kg/㎥, 2 kg of azodicarbonamide, a thermal decomposition type foaming agent, and 0.2 g of a phenolic antioxidant IRGANOX 1010 were uniformly mixed and supplied to the extruder, and the resin temperature was 170. It extruded while melt-kneading at°C and formed into a long sheet shape. Subsequently, the sheet was irradiated with an electron beam to crosslink the resin, and then it was continuously introduced into a molten salt bath set at 235°C to prepare a crosslinked foam A. The obtained foam had a thickness of 0.4 mm and a density of 250 kg/m 3.

[Reference Example 2]

The foam prepared in Reference Example 1 was stretched 200% in the longitudinal direction with 4 rolls set at 80°C, then put into a tenter set at 120°C, and stretched 200% while holding both ends with a clip, so that a thickness of 0.1 mm and a density of 300 A kg/m3 foam B was prepared.

[Reference Example 3]

In Reference Example 1, a foam having a thickness of 2 mm and a density of 430 kg/m 3 was prepared by making the addition amount of the pyrolytic foaming agent 4.5 kg. After slicing the surface layer of 0.4 mm by a slicing machine, the resulting foam was stretched in the longitudinal direction in a heating furnace set at a temperature of 110°C to produce a foam C having a thickness of 0.5 mm and a density of 475 kg/m 3.

[Reference Example 4]

In Reference Example 1, foam D was prepared in the same manner except that 10 parts by weight of sodium dodecylbenzenesulfonate was added to 100 parts by weight of the polyethylene resin.

[Reference Example 5]

In Reference Example 1, foam E was prepared in the same manner except that 15 parts by weight of Kecheon Black was added to 100 parts by weight of the polyethylene resin.

[Reference Example 6]

Low-density polyethylene with a density of 918 kg/m3 is injected from the hopper of the extruder, super-border carbon dioxide gas is injected from the middle of the first stage of a tandem extruder with two single-screw extruders, and extruded from a circular die while cooling in the second stage extruder. After molding with, it was cut to prepare a non-crosslinked foam F.

[Reference Example 7]

With respect to 100 parts by weight of an ethylene-vinyl acetate copolymer having 14% vinyl acetate, 2.7 kg of azodicarbonamide, a pyrolytic foaming agent, and 0.2 g of a phenolic antioxidant IRGANOX 1010 were uniformly mixed and supplied to an extruder, and a resin temperature of 150 It extruded while melt-kneading at°C and formed into a long sheet shape with a thickness of 0.9 mm. Subsequently, the sheet was irradiated with an electron beam to attach the resin to the bridge, and then continuously poured into a molten salt bath set at 235°C to prepare a crosslinked foam G. The obtained foam had a thickness of 1.5 mm and a density of 140 kg/m 3.

The film shown in Table 2 purchased and used a commercially available biaxially stretched polypropylene film.

Film a: Toyobo Co., Ltd. P002 (thickness 40 µm)

Film b: Toyobo Co., Ltd. P2161 (thickness 40 µm)

Film c: Toyobo Co., Ltd. P2161 (thickness 30 µm)

Film d: PAS-P1M (thickness 40 μm) manufactured by Futamura Chemical Co., Ltd.

Film e: Futamura Chemical Co., Ltd. PAS-P2 (thickness 30 µm)

Film f: Toyobo Co., Ltd. P2102 (thickness 20 µm)

[Example 1]

As shown in Fig. 1, the foam A having a product width of 1 m and the film b having a product width of 1 m are respectively set with an unwinding machine, and unwinding at a speed of 20 m/min at a line speed, Kasuga Electric Works Ltd. Using the charging device PST-2005N, charging treatment was performed at a voltage of -15 kV with a distance between the electrode and the film surface of 15 mm. Subsequently, it was introduced into a nip roller and nip at a pressure of 0.3 MPa to laminate the foam and the film to obtain a laminate. Thereafter, the surface of the foam was discharged at 4 kV using a SIMCO JAPAN-made anti-static agent (power source: POWER UNIT 150, electrode ss-50), and the laminate was wound up with a winding tension of 100 mN.

The potential of the created laminate was +3.1 kV, and the peel strength between the foam and the film was 40 mN/25 mm. Subsequently, when the laminate was subjected to slit processing, a product having good appearance was obtained without wrinkles due to deformation of the foam body, air engagement, etc. Table 3 shows the results.

[Examples 2 to 14, Comparative Examples 1 and 2]

In Examples 2 to 14 and Comparative Examples 1 and 2, in the same manner as in Example 1, the potential and adhesion strength of the laminate obtained by creating a laminate under the conditions shown in Table 3 were measured, and evaluation by slit processing was performed. Carried out.

As shown in Table 3, in Examples 1 to 14 satisfying the conditions specified in the present invention, good results, particularly good slit workability were obtained, but in Comparative Examples 1 and 2, which did not satisfy the conditions specified in the present invention, good results. No results were obtained.

(Industrial availability)

The laminate according to the present invention is particularly applicable to all applications requiring the use of a thin foam, and can be particularly suitably used in the case of installing a cushioning material or a shock absorbing material for electronic/electric devices such as mobile phones.

1 film 2 foam
3 stacked body 4 charging device
5 Antistatic device 6a, 6b nip roller
7 Guide roller 8 Counter-pole roller

Claims (15)

A laminate in which a film is laminated on at least one side of a sheet-like foam, and the laminated body satisfies the following requirements (A) to (E).
(A) The thickness of the foam is 0.05 to 1.5 mm
(B) the thickness of the film is 25 to 250㎛
(C) The surface resistivity of the film is 1×10 ¹¹ Ω or more
(D) The foam and the film are directly bonded without an adhesive
(E) The peel strength between the foam and the film is 10 mN/25 mm to 100 mN/25 mm The method of claim 1,
A laminate having a foam thickness of 0.05 to 0.5 mm. The method according to claim 1 or 2,
A laminate in which the peel strength of the foam and the film is in the range of 25 mN/25 mm to 100 mN/25 mm. The method according to any one of claims 1 to 3,
A laminate in which the potential of the laminate is in the range of -30 to +30 kV. The method of claim 4,
A laminate in which the potential of the laminate is in the range of -15 to +15 kV. The method according to any one of claims 1 to 5,
A laminate in which both the foam and the film are mainly composed of an olefin resin. The method according to any one of claims 1 to 6,
A laminate having an apparent density of the foam in the range of 100 kg/m 3 to 500 kg/m 3. The method according to any one of claims 1 to 7,
A laminate in which the surface of the film on the side in close contact with the foam body is charged. The method according to any one of claims 1 to 8,
A laminate in which the foam from which the film has been peeled off is used to fix parts constituting electronic and electrical devices to the device body. A method for producing a laminate in which a sheet-like foam and a film are in close contact, comprising in this order a charging step in which an electric charge is applied to one of the foam or film to be charged, and an adhesion step in which the foam and the film are in close contact. Manufacturing method. The method of claim 10,
Production of a laminate having an adhesion increasing step of increasing the adhesion on the adhesion surface by giving a charge of opposite polarity to the charge on the adhesion surface of the foam or film on the outer surface of the foam or film after the adhesion step Way. The method of claim 10 or 11,
In the charging step, a method for producing a laminate in which the surface of the film on the side to be in close contact with the foam is charged. The method according to any one of claims 10 to 12,
A method for producing a laminate comprising the step of compressing the foam and the film with a nip roller in the adhesion step. The method according to any one of claims 10 to 13,
A method for producing a laminate using the following materials (A) and (B).
(A) a foam with a thickness of 0.05 to 1.5 mm
(B) A film having a thickness of 25 to 250 μm and a surface resistivity of 1×10 ¹¹ Ω or more The method of claim 14,
A method for producing a laminate in which the foam has a thickness of 0.05 to 0.5 mm.

Images