KR102597797B1 - Laminate and its manufacturing method - Google Patents

Abstract

A laminate in which a film is laminated on at least one side of a sheet-shaped foam and satisfies the requirements (A) to (E) below, 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 ㎛, (C) The surface resistivity of the film is 1 × 10 ¹¹ Ω or more, (D) The foam and film do not contain an adhesive. (E) The peeling strength of the foam and film is 10mN/25mm to 100mN/25mm.
According to the present invention, when performing various processes on a thin foam, it is possible to provide a laminate that allows the desired processing without deforming the foam, the film can be appropriately peeled from the laminate, and the foam can be easily divided into single pieces. You can use it. Additionally, since the laminate is formed without an adhesive, the possibility of the adhesive remaining in the foam after peeling the film can be eliminated.

Description

Laminate and its manufacturing method

The present invention relates to a laminate obtained by laminating a sheet-shaped foam and a film, and to a method for manufacturing the same. In particular, even a thin foam can be processed as desired as a laminate without deforming it by laminating the film, and can be easily manufactured from the laminate. The present invention relates to a laminate that allows the film to be peeled off properly and to enable use of the foam alone, and to a method for manufacturing the same.

Foams, for example, polyolefin resin foams, have uniform and fine closed cells and have excellent cushioning properties and processability, so they are used in a variety of applications. Such foams can be easily thinned by stretching, slicing, etc., and maintain good cushioning and shock absorbing properties even in the thinned state, so they are suitably used as cushioning materials for electronic and electrical devices such as mobile phones. When the foam is used alone, it is used with an adhesive layer or the like formed on one or both sides of the foam. Additionally, these foams, regardless of the presence or absence of an adhesive layer, are subjected to various processing such as slitting to adjust the width to suit the shape of the electronic/electrical device or punching to match the shape, and then are used as housings for electronic/electrical devices, etc. It is assembled and used as a cushioning material, etc.

The foam used as described above is usually very thin, with a thickness of about 0.05 to 1.5 mm, or about 0.05 to 0.5 mm, and is low-densified to provide cushioning properties, so its strength is low, so various processing as described above is performed. When trying to do this, problems such as stretching and deformation due to tension during transportation or wrinkles may occur. Additionally, for the purpose of improving shock absorption, etc., in the case of foams where the resin itself has adhesive properties, such as ultra-low density polyethylene or ethylene-vinyl acetate copolymer, when the foam is rolled into a roll and stored for a long period of time, the foams adhere closely to each other, which is called blocking. This phenomenon occurs, and there is also a problem that excessive tension is required in the foam when peeling and unwinding the foam for use. In this way, when processing thin, especially low-density foam, there is a risk of various problems such as deformation, wrinkling, and blocking occurring.

In order to solve these problems, a method of winding the foam and the release paper (a concept including the release film) together is considered (for example, patent document 1). However, when only release paper is used, especially in the case of thin foam, there is a risk that air may enter between the foam and the release paper, causing problems such as deformation of the foam. There is also a method of bonding a film with an adhesive to the foam and winding it up. However, even if the film is peeled off and an attempt is made to use only the foam layer, the adhesive remains partially attached to the foam layer, and the desired form of foam use is achieved. There is a risk that problems such as difficulty in obtaining .

Publication No. WO2016/093133A1

Therefore, the object of the present invention is to enable the desired processing without deforming the foam when performing various processing on a thin foam, and to easily and appropriately peel the film from the laminate, which causes problems. The aim is to provide a laminate that enables use of the foam alone without using it, and a manufacturing method for the laminate.

As a result of careful study, the present inventors found that the above-described problem can be solved by the laminate and its manufacturing method described below.

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

(1) A laminate in which a film is laminated on at least one side of a sheet-shaped foam, and which 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) Foam and film are directly bonded without an adhesive.

(E) The peeling strength of the foam and 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 of 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 olefin resin.

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

(8) The laminate according to any one of (1) to (7), wherein the surface of the film 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 is used to fix parts constituting an electronic/electrical device to the device main body.

The method for manufacturing a laminate according to the present invention has the following structure.

(10) A method for producing a laminate in which a sheet-shaped foam and a film are brought into close contact, characterized by comprising, in this order, a charging step of charging either the foam or the film by applying an electric charge, and an adhesion step of bringing the foam and the film into close contact with each other, in this order. A method of manufacturing a laminate.

(11) In (10), after the adhesion step, a charge of opposite polarity to the charge on the adhesion surface between the foam and the film is given to the outer surface of the foam or film to increase the adhesion force on the adhesion surface. Method for manufacturing a laminate having an adhesion increasing process.

(12) The method for manufacturing a laminate according to (10) or (11), wherein in the charging step, the surface of the film on the side that is brought into close contact with the foam 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 pressing 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 materials (A) and (B) below.

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

(B) Film with a thickness of 25∼250㎛ 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 and its manufacturing method of the present invention, when performing various processes on a thin foam, it is possible to provide a laminate that can be processed as desired without deforming the foam. Additionally, the film can be appropriately peeled from the laminate, and the foam can be easily used alone. Additionally, by forming a laminate without an adhesive, the possibility of the adhesive remaining in the foam after peeling off the film can be eliminated.

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

Below, the present invention will be described in detail along with 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, shock absorption and cushioning properties become insufficient. On the other hand, if the thickness exceeds 1.5 mm, it is undesirable because it becomes impossible to achieve thinning of the electronic/electrical device, especially when it is used to fix parts constituting the electronic/electrical device to the device body. A more preferable range is a thickness of 0.05 to 0.5 mm.

The foam used in the present invention is preferably composed mainly of olefin resin, especially polyolefin resin. The polyolefin-based resin is not particularly limited, but examples include polyethylene-based resins represented by low-density polyethylene, high-density polyethylene, linear low-density polyethylene, and ultra-low-density polyethylene (the definition of density here is as follows. Ultra-low density: 0.910 g) /㎤ or less, low density: 0.910 g/㎤ or more and 0.940 g/㎤ or less, high density: greater than 0.940 g/㎤ and 0.965 g/㎤ or less), copolymer with ethylene as the main component, or homopolypropylene, ethylene-propylene random Examples include polypropylene-based resins such as copolymers and ethylene-propylene block copolymers, and may be any of these mixtures. Examples of the copolymer containing ethylene as a main component include ethylene and an α-olefin having 4 or more carbon atoms (e.g., ethylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-olefin, -heptene, 1-octene, etc.) are obtained by polymerizing ethylene-α-olefin copolymer, ethylene-vinyl acetate copolymer, etc. As the polyolefin-based resin, more preferably polyethylene-based resins such as low-density polyethylene, linear low-density polyethylene, and ultra-low-density polyethylene, ethylene-α-olefin copolymer, and ethylene-vinyl acetate copolymer. More preferably, it is low-density polyethylene, linear low-density polyethylene, and ultra-low-density polyethylene. These polyolefin resins may be one type or a mixture of two or more types. Most preferably, it is low-density polyethylene, linear low-density polyethylene, ethylene-vinyl acetate copolymer alone, or a mixture thereof.

Additionally, thermoplastic resins other than polyolefin resins may be added as long as they do not significantly impair the properties of the foam. Thermoplastic resins other than polyolefin resins referred to herein include resins that do not contain halogen, such as polystyrene, acrylic resins such as polymethyl methacrylate and styrene-acrylic acid copolymers, styrene-butadiene copolymers, and ethylene-vinyl acetate copolymers. Polyvinyl acetate, polyvinyl alcohol, polyvinyl acetal, polyvinyl pyrrolidone, petroleum resin, cellulose derivatives such as cellulose, cellulose acetate, cellulose nitrate, methyl cellulose, hydroxymethyl cellulose, and hydroxypropyl cellulose, low molecular weight. Polyolefins such as polyethylene, high molecular weight polyethylene, and polypropylene, saturated alkyl polyester resin, polyethylene terephthalate, polybutylene terephthalate, aromatic polyester resin made from polyarylate, polyamide resin, polyacetal resin, polycarbonate resin, poly Examples include ester sulfone resin, polyphenylene sulfide resin, polyether ketone resin, vinyl polymerizable monomer, and copolymers having nitrogen-containing vinyl monomer. In addition, polystyrene-based thermoplastic elastomer (SBC, TPS), polyolefin-based thermoplastic elastomer (TPO), polyvinyl chloride-based thermoplastic elastomer (TPVC), polyurethane-based thermoplastic elastomer (TPU), polyester-based thermoplastic elastomer (TPEE, TPC), and polyamide. Thermoplastic elastomer (TPAE, TPA), polybutadiene thermoplastic elastomer (RB), hydrogenated styrene butadiene rubber (HSBR), styrene/ethylene butylene/olefin crystal block polymer (SEBC), olefin crystal/ethylene butylene/olefin crystal block. Block copolymers such as polymer (CEBC), styrene/ethylene butylene/styrene block polymer (SEBS), and olefin block copolymer (OBC), polyolefin-vinyl graft copolymer, polyolefin-amide graft copolymer, and alpha-olefin. and elastomers such as graft copolymers such as copolymers, polyolefin-acrylic graft copolymers, and polyolefin-cyclodextrin graft copolymers.

In addition, resins containing halogen include polyvinyl chloride, polyvinylidene chloride, polyethylene chloride trifluoride, polyvinylidene fluoride resin, fluorocarbon resin, perfluorocarbon resin, and solvent-soluble perfluorocarbon resin. I can hear it. The number of thermoplastic resins other than these polyolefin resins may be one or multiple types may be contained. In particular, it is preferable to add an elastomer for the purpose of providing flexibility or shock absorption, and the type and amount are selected according to the desired physical properties.

In the foam used in the present invention, within the range that does not impair the effect of the present invention, antioxidants such as phenol-based, phosphorus-based, amine-based and sulfur-based, metal release inhibitors, fillers such as mica and talc, bromine-based and phosphorus-based, etc. Flame retardants, flame retardant aids such as antimony trioxide, antistatic agents, lubricants, pigments, and additives such as polytetrafluoroethylene can be added.

Additionally, the foam used in the present invention may be colored black. Black colorants used when coloring black include, for example, 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. All known colorants such as cyanine black, activated carbon, ferrite (non-magnetic ferrite, magnetic ferrite, etc.), magnetite, chromium oxide, iron oxide, molybdenum disulfide, chromium complex, complex oxide-based black pigment, and anthraquinone-based organic black pigment can be used. You can. Among them, carbon black is preferable from the viewpoint of cost and availability.

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

The apparent density of the foam used in the present invention is preferably 100 kg/m3 to 500 kg/m3. If the apparent density is less than 100 kg/m3, the strength of the foam decreases, wrinkles, etc. are likely to occur during processing, and shock absorbency decreases, which is not preferable. If it exceeds 500 kg/m3, it becomes hard and the cushioning properties decrease, so it is not preferable. More preferably, it is in the range of 200 kg/m3 to 400 kg/m3.

The foam used in the present invention can be either crosslinked foam (referred to as crosslinked foam) or non-crosslinked foam (referred to as non-crosslinked foam), and an appropriate foam may be selected depending on the application 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 crosslinking degree 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 1×10 ¹⁰ Ω or more. If the surface resistivity is less than 1×10 ¹⁰ Ω, it is not preferable because the adhesion to the film decreases. More preferably, it is 1×10 ¹² Ω or more. In order to adjust the surface resistivity, it is preferable to use polyolefin resin as the main component and add antistatic agents, etc. as needed. Examples of such antistatic agents include monomer-type antistatic agents such as N,N-bis(hydroxyethyl)alkylamine, alkylallyl sulfonate, and alkyl sulfonate, and 1-propyl-3-methylpyridinium/bistrifluoro. Ionic liquids such as lomethane sulfonate, 1-butyl-3-methylpyridinium and trifluoromethane sulfonate, polyethylene oxide, polypropylene oxide, polyethylene glycol, polyester amide, polyether ester amide, ethylene- Ionomers such as methacrylic acid copolymers, quaternary ammonium salts such as polyethylene glycol methacrylate-based copolymers, and polymer-type charging agents such as copolymers of olefin-based blocks and hydrophilic blocks described in Japanese Patent Application Laid-Open No. 2001-278985. Preventative agents, etc. can be mentioned.

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, it is undesirable because air tends to enter the interface when forming a laminate of foam and film, which tends to reduce adhesion. More preferably, it is 25㎛ or less.

As a method for producing the foam used in the present invention, a conventionally known method can be used. For example, electron beam crosslinked foam is obtained by molding a resin composition into a sheet using a pyrolytic blowing agent, crosslinking the resin by irradiating it with ionizing radiation, and then heating the sheet above the decomposition temperature of the blowing agent to obtain a foam. A method for producing a chemically crosslinked foam, in which a pyrolytic foaming agent and an organic peroxide are formed into a sheet shape together with a resin composition and then heated to foam while crosslinking the resin. Carbon dioxide in a superboundary state is added from the middle of the extruder. Examples include a method of producing an extruded foam in which nitrogen gas, butane gas, etc. are injected and the foam is extruded from a spinneret.

In addition, slicing processing in which the foam created by these methods is divided in the thickness direction to thin it out, stretching processing in which the foam is stretched uniaxially or biaxially while heating, and compression processing in which the heated foam is sandwiched between rolls, etc., are used alone or in combination to thin the foam. It can also be used preferably.

The average cell diameter of the foam used in the present invention is not particularly limited, but a smaller size is preferable in terms of smoother surface, improved adhesion when forming a laminate, and flexibility. If it is made too small, it becomes necessary to make the resin highly viscous, which significantly reduces productivity. From this viewpoint, the average cell diameter of the foam is preferably in the range of 20 μm to 400 μm, and more preferably in the range of 20 μm to 200 μm.

The average cell diameter of the foam is calculated as follows. A cross section of the foam sheet was observed at a magnification of 50 times using a scanning electron microscope (SEM) (S-3000N, manufactured by Hitachi High-Tech Corporation), and the cell diameter was measured using the resulting image and measurement software. In addition, the cell diameter is measured in the longitudinal direction (MD) and the transverse direction (TD) within the 1.5 mm × 1.5 mm range of the captured image, the average cell diameter in each direction is calculated, and the average value is was taken as the average bubble diameter. Additionally, measurements were made in 10 fields of view, and the arithmetic mean was obtained.

Next, the film used in the laminate of the present invention is explained.

The thickness of the film used in the present invention is in the range of 25 to 250 μm. If it is less than 25㎛, not only will wrinkles be likely to occur when slitting to adjust the laminated body to the optimal width, but the laminated body will easily deform during punching, and workability will decrease, so it is preferable. don't do it If it exceeds 250㎛, economic rationality is poor. The film may be either a stretched film or an unstretched film, but a biaxially stretched film is most preferable to prevent deformation of the laminate.

The surface resistivity of the film used in the present invention needs to be 1×10 ¹¹ Ω or more, and is preferably 1×10 ¹⁸ Ω or less. If the surface resistivity is less than 1×10 ¹¹ Ω, the dislocations are lost when laminated with the foam, making it impossible to adhere to the foam. The surface resistivity of the film can be adjusted by adding the antistatic agent to the resin composition constituting the film. When 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 composed mainly of olefin resin in order to maintain the potential of the laminate in an appropriate range and from the viewpoint of economic rationality. Polyolefin-based resins include low-density polyethylene, high-density polyethylene, linear low-density polyethylene, and ultra-low-density polyethylene (the definition of density here is as follows: ultra-low density: less than 0.910 g/cm3, low density: 0.910 g/cm3). ㎤ or more and 0.940 g/㎤ or less, high density: greater than 0.940 g/㎤ and 0.965 g/㎤ or less), copolymers containing ethylene as a main component, or homopolypropylene, ethylene-propylene random copolymer, and ethylene-propylene block copolymer. and polypropylene-based resins represented by these, etc., and any mixture thereof may be used. Among these, a film mainly composed of polypropylene with high rigidity is most preferable from the viewpoint of preventing wrinkles etc. from occurring when processing the laminate. Furthermore, even if it is made of a homopolymer of propylene, it may contain copolymerization components of other unsaturated hydrocarbons, etc., as long as it does not impair the purpose of the present invention, and polymers other than propylene alone may be blended. Monomer components constituting such copolymerization components or blends include, for example, ethylene, propylene (in the case of copolymerization blends), 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. can be mentioned. From the viewpoint of dielectric breakdown resistance and rigidity, the copolymerization amount or blending amount is preferably less than 1 mol% and the blending amount is preferably less than 10 mass%.

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

The laminate of the present invention requires that the above-mentioned foam and film are directly bonded without an adhesive being interposed. 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, no adhesive is present on the film-side surface of the foam.

The laminate of the present invention can be assembled into an electronic/electrical device housing after performing various processes such as slitting or punching, and in particular, the foam in the state of peeling the film from the laminate can be used as a layer having good cushioning properties and shock absorption properties. It can be assembled as. As a form of assembly of the foam, an adhesive layer is formed on the surface of the foam opposite the film side, or a non-adhesive layer is first formed on the opposite film-side surface and aligned with the housing, and then the non-adhesive layer is peeled off to form an adhesive layer. Various forms are adopted, such as forming an adhesive layer after peeling the film on the film side of the foam. However, if an adhesive previously exists on the surface of the foam, especially if the adhesive remains on the film-side surface of the foam after the film is peeled off, air may enter the interface with the adhesive applied later, and the appearance will easily deteriorate. It is not advisable as there is a possibility of problems such as losing.

Additionally, because 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 be destroyed. Therefore, it is difficult to remove the already existing adhesive layer before forming a new adhesive layer.

On the other hand, in the laminate of the present invention, since the foam and the film are directly bonded without an adhesive intervening, there is no adhesive on the film-side surface of the foam after peeling off the film, and it is supported by the film in the laminate form. It is possible to easily form an adhesive layer suitable for the purpose or area where the foam is used on the surface of the foam opposite to the film.

Conventionally, when 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. Methods for removing are known. Foam has a low density and low strength, so it expands when heated. Therefore, rather than applying a solution containing an adhesive to the foam side, the method of applying an adhesive to a film or release paper, drying it, and then bonding it together speeds up production. It is possible to improve and is preferably used. Also in this process, if a film is used that is bonded directly to the side of the foam that is not bonded to the adhesive without preliminarily interposing the adhesive, it is possible to prevent the foam from being deformed due to winding tension or the like.

In this way, in the present invention, it becomes easy to perform various processing by forming a laminate in which the foam and the film are directly bonded without an adhesive.

In the laminate of the present invention, the peeling strength between the foam and the film is in the range of 10 mN/25 mm to 100 mN/25 mm. If the peeling strength of the foam and film is less than 10mN/25mm, it is undesirable because the foam and film will peel off during various processes on the laminate, and if it exceeds 100mN/25mm, the foam will deform when peeling the film. It is not advisable because there is a possibility that it may fail. More preferably, it is in the range of 25mN/25mm to 100mN/25mm. The peel strength of the foam and film can be controlled by optimizing conditions such as surface resistivity, surface roughness, and discharge amount of the foam or film.

In addition, as mentioned above, the surface resistivity of the foam used in the present invention is preferably 1 × 10 ¹⁰ Ω or more, and the surface resistivity of the film used in the present invention is 1 × 10 ¹¹ Ω or more, but the surfaces of both materials together If one with a low resistivity is used, the adhesion strength between the foam and the film in the laminate may not fall within the above range. Therefore, a preferred combination is a laminate of a foam with a surface resistivity of 1×10 ¹⁶ to 1×10 ¹⁸ Ω and a film with a surface resistivity of 1×10 ¹¹ to 1×10 ¹⁴ Ω, and a laminate of a foam with a surface resistivity of 1×10 16 to 1×10 ^{18 Ω} . A laminate of a foam having a surface resistivity of ∼1×10 ¹⁵ Ω and a film having a surface resistivity of ∼1×10 ¹⁶ ∼1×10 ¹⁸ Ω is preferred because it can obtain an appropriate adhesion strength that can achieve the above peel strength range.

The potential of the laminate of the present invention is preferably in the range of -30 to +30 kV. If the absolute value of the potential exceeds ±30 kV, it is undesirable because the potential is too high, making it easier for dust in the surrounding environment to adhere and also because self-discharge and the like are likely to occur. More preferably, it is in the range of -15 to +15 kV, and even more preferably in the range of -10 to +10 kV.

In the laminate of the present invention, it is preferable that the surface in close contact with the foam of the film is electrically charged. In order to bring the film and foam into close contact by electrification, it is preferable to electrify either the film or the foam, or both. However, if the foam is treated with high voltage to charge it, defects such as pinholes are likely to occur, so the film is in close contact with the foam. It is desirable to electrify the surface being applied. Additionally, either the side of the film that is in close contact with the foam or the side that is not in close contact may be charged (even if the side that is not in close contact is charged, the side that is in close contact with the foam will be charged as a result), but the adhesion strength In order to increase , it is desirable to electrify the side of the film that is in close contact with the foam.

In a laminate, which surface is charged can be confirmed by a method called the dust figure method of spraying toner used in a copier (Electrostatic Handbook, published in 1981, Electrostatic Society edition, p. 373). The dust figure method is a method of floating charged colored fine particles near a charged body and causing them to attach and develop by electrostatic force. A powder toner commonly used in color copiers is suitable as a developer used in the dust figure method. Preferably, the average particle diameter is from several ㎛ to tens of ㎛. In addition, since the adhesion of the powder changes depending on the ambient humidity in the working environment, 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 size: Weight average particle size: 14.8㎛ (6㎛ or less: 0.2% by weight, 25㎛ or more: 1.8% by weight)

Specific charge: -1.2μC/g

Troubleshooting Toner:

Color: Blue

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

Specific charge: -23.1μC/g

In addition, the average particle diameter of the toner shown here is a value measured using an aperture tube with a diameter of 100 μm using MULTISIZERII manufactured by COULTER. In addition, the specific charge is a value measured by a blow method charge quantity measuring device (TB-500 type manufactured by Toshiba Chemical Corporation). Specifically, the toner to be measured and the iron carrier (TSV-200R from Powdertech Co., Ltd.) were mixed at a weight ratio of 1:19, stirred for 5 minutes by a ball mill, and then the powder sample was placed in the charge quantity measurement device. Only 0.2g was put into the measurement cell, blow pressure was 0.5kg/㎠, blow time was 60 seconds, and the value measured using a 400 mesh stainless steel mesh screen was converted to the weight of toner (0.2g×1/20=0.01g). It is obtained by dividing the value.

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

The method for manufacturing the laminate 3 of the present invention includes, in this order, an electrification process in which either the sheet-shaped foam 2 or the film 1 is charged by applying an electric charge, and an adhesion process in which the foam and the film are brought into close contact with each other in this order. need. The charging process and adhesion process may be performed sequentially in the process of manufacturing the foam, or may be performed once after the foam has been wound.

The charging method of the charging device 4, which charges either the foam 2 or the film 1 by applying an electric charge, is not particularly limited. For example, (1) on one side of the foam 2 or the film 1. The grounded flat electrodes are overlapped, and needle electrodes or wire electrodes electrically connected to a direct current high-voltage power supply are installed at predetermined intervals on the other side of the foam 2 or film 1, and the tips of the needle electrodes or wire electrodes are provided. A method of generating a corona discharge by concentrating an electric field near the surface and ionizing and charging the air, (2) holding the foam (2) or film (1) between a pair of plate electrodes and grounding one of the plate electrodes. In addition, a method of charging the foam (2) or film (1) by connecting the other flat electrode to a high-voltage direct current power supply and applying a direct current or pulsed high voltage to the foam (2) or film (1); (3) ionizing radiation such as electron beams, X-rays, or ultraviolet rays; Examples include a method of irradiating the foam (2) or film (1) and ionizing nearby air to charge it. However, the method of (1) using corona discharge treatment is the best method for easily injecting charge. desirable.

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

In addition, there is no limitation on which side the corona discharge treatment is performed on, but it is more preferable to charge the side that is in close contact with the other material of the foam 2 or the film 1 in order to increase adhesion. In addition, in order to uniformly adhere to the ends of the product, it is necessary to widen the width of the electrode relative to the width of the object to be treated, such as the film 1 or the foam 2.

The discharge amount when electrifying by corona discharge is preferably in the range of 0.5 to 100 J/m2. If the discharge amount is less than 0.5 J/m2, it is undesirable because the adhesion between the foam 2 and the film 1 decreases, and if it exceeds 100 J/m2, hole defects such as pinholes may occur in the film 1 or the foam 2. This is undesirable because it is likely to occur. More preferably, it is in the range of 1.0 to 100 J/m2.

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

Discharge amount (J/㎡) = Power (W)/{Line speed (m/s) × Width of film or foam (m)}

The process of bringing the foam 2 and the film 1 into close contact can be achieved by bringing one of the materials into contact with the electrically charged foam 2 or the film 1 and bringing them into electrostatic contact. However, air is applied to the contact surface. In order to prevent engagement, 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 desirable to bring them into close contact using 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, etc. 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 the film (1) is inverse to the charge on the adhesive surface of the foam (2) and the film (1). It is particularly desirable to have a process to increase adhesion by applying a polar charge. For example, the surface of the film 1 in close contact with the foam 2 is subjected to corona discharge treatment by applying an electrostatic charge using a charging device 4 as shown in FIG. 1 to laminate the film 1 with the foam 2. After forming the laminate 3, the outer surface of the foam 2 is irradiated with a negative charge by the static electricity elimination device 5, so that the electric charge is neutralized and the potential in the laminate 3 can be reduced, and the foam (2) It becomes possible to improve the adhesion between 2) and the film 1. In addition, one of the preferred forms of supplying charges of reverse polarity is to carry out a mixture of positive and negative charges. In this way, the means for imparting a charge of reverse polarity is not particularly limited, and includes a high-pressure applied static electricity removal device, a self-discharge type static electricity removal device, and a device that irradiates ionizing radiation such as soft X-rays or α-rays. , a high-pressure static electricity removal device using corona discharge is most desirable. In addition, from the viewpoint of efficiently charging the foam (2) or film (1), an opposing electrode roller (8) is provided on the surface opposite to the charging device (4) with the foam (2) or film (1) interposed therebetween. It is desirable. By providing the counter electrode roller 8, an electric field is formed between the counter electrode roller 8 and the discharge electrode of the charging device 4, and the ions generated in the corona discharge are efficiently transferred to the foam 2 or film 1 on the roller. It becomes possible to touch the surface and improve the efficiency of charging treatment. The material of this counter roller 8 is not particularly limited, and either a metal roller or a rubber roller can be used. However, in the case of a rubber roller, treatment efficiency decreases if the roller becomes charged, so it is preferable that the roller is a conductive rubber.

In order to manufacture the laminate of the present invention, an unwinder is used to unwind the foam (2) and the film (1) at a certain tension and speed, and an appropriate tension is applied to the foam (2) and the film (1) to prevent meandering, etc. It is desirable to provide a guide roller 7 for cutting the laminated body 3 to a desired width, a cutter such as a shear blade or leather blade for cutting the laminated body 3 to a desired width, and a winder for winding the laminated body.

Example

Below, the present invention is explained in detail by examples. In addition, the measurement method and evaluation method are as shown below.

(1) Thickness of foam

The thickness of the foam was measured according to ISO 1923 (1981) “Method for measuring the dimensions of foamed plastics and rubber.” Specifically, using a dial gauge with a circular measuring point having an area of 10 cm2, the foam cut to a certain size is placed on a flat table and then measured by contacting the surface of the foam with a constant pressure of 10 g.

(2) Apparent density of foam

The apparent density of the foam is a value measured and calculated in accordance with JIS K6767 (1999) "Foamed plastic - polyethylene - test method." The thickness of the foam cut into an area of 10 cm2 is measured, and the mass of this test piece is also weighed. The value obtained by the formula below is called the apparent density, and the unit is kg/㎥.

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

(3) Crosslinking degree of foam

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

Degree of crosslinking (%) = {mass of insoluble matter (mg)/mass of weighed foam (mg)} x 100

(4) Surface roughness of foam

The surface roughness of the foam was measured using a surface roughness measuring device (model: SE-2300, manufactured by Kosaka Laboratory Ltd.), and the center line average roughness (Ra) was determined. However, the measurement location was the surface on which the foam film was laminated. The measurement direction is within the surface of the foam sheet, and measurements are made in two directions, the longitudinal direction and the direction perpendicular to it, and the number of measurements is once for each. Among these measured values, the highest value was taken as the surface roughness of the foam.

(5) Thickness of film

The thickness of the film was measured at 10 random 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 foams and films

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

(7) Peel strength of laminate

For the peel strength of the laminate, a test piece was prepared by cutting the created laminate so that the length in the longitudinal direction of the product (winding direction in Fig. 1) was 150 mm and the width was 25 mm. One end of this test piece was inserted into each laminated body and fixed, and only the film of the laminated body was fixed with scissors on the other side, and peeling was performed using TENSILON UCT-500 manufactured by Orientec Corporation at a speed of 200 mm/min and a peeling angle of 180°. A peeling test was conducted by pulling the film at a distance of 80 mm. The obtained peeling strength was the maximum peeling strength value within a peeling distance of 80 mm, and the average value obtained from the values measured twice was taken as the peeling strength.

(8) Dislocation of laminate

The potential of the laminate was measured using a digital electrostatic potential meter KSD-1000 manufactured by Kasuga Electric Works Ltd. Measurements were made using an electrometer 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 processability)

The created laminate was subjected to slit processing and evaluated for the presence or absence of wrinkles. Leather blades were installed every 140 mm on a slit machine that was connected to a mechanical motor for unwinding and capable of winding at an arbitrary speed, and slit processing was performed at a processing speed of 40 m/min, and six products with a width of 140 mm were collected at the same time. If even one of the six collected products had no wrinkles, it was rated as passing (○), and if even one of the products had wrinkles, it was rated as failing (×).

Tables 1 and 2 show the foams and films used.

[Reference Example 1]

With respect to 100 parts by weight of linear low-density polyethylene resin with a density of 925 kg/㎥, 2 kg of pyrolytic blowing agent azodicarbonamide and 0.2 g of phenolic antioxidant IRGANOX 1010 were uniformly mixed and supplied to an extruder, and the resin temperature was 170. It was extruded while melt-kneading at ℃ and formed into a long sheet shape. Next, this sheet was irradiated with an electron beam to crosslink the resin, and then continuously poured into a molten salt bath set at 235°C to create crosslinked foam A. The thickness of the obtained foam was 0.4 mm and the density was 250 kg/m3.

[Reference Example 2]

The foam prepared in Reference Example 1 was stretched 200% in the longitudinal direction with four rolls set at 80°C, then placed into a tenter set at 120°C and stretched 200% while held at both ends with clips to obtain a thickness of 0.1 mm and a density of 300. Foam B of kg/m3 was prepared.

[Reference Example 3]

In Reference Example 1, the addition amount of the pyrolytic foaming agent was set to 4.5 kg to create a foam with a thickness of 2 mm and a density of 430 kg/m3. After slicing the created foam with a slice processor to slice 0.4 mm of the surface layer, it was stretched in the longitudinal direction in a heating furnace set to a temperature of 110°C to create foam C with a thickness of 0.5 mm and a density of 475 kg/m3.

[Reference Example 4]

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

[Reference Example 5]

Foam E was prepared in the same manner as in Reference Example 1, except that 15 parts by weight of Ketchen black was added to 100 parts by weight of polyethylene resin.

[Reference Example 6]

Low-density polyethylene with a density of 918 kg/m3 is fed from the extruder hopper, superboundary 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, it was cut to create non-crosslinked foam F.

[Reference Example 7]

With respect to 100 parts by weight of ethylene-vinyl acetate copolymer with a vinyl acetate content of 14%, 2.7 kg of pyrolytic blowing agent azodicarbonamide and 0.2 g of phenolic antioxidant IRGANOX 1010 were uniformly mixed and supplied to an extruder, and the resin temperature was 150. It was extruded while melt-kneading at ℃ and formed into a long sheet shape with a thickness of 0.9 mm. Next, this sheet was irradiated with an electron beam to form bridges with the resin, and then continuously poured into a molten salt bath set at 235°C to create a crosslinked foam G. The thickness of the obtained foam was 1.5 mm and the density was 140 kg/m3.

The film shown in Table 2 was a commercially available biaxially oriented polypropylene film.

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

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

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

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

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

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

[Example 1]

Foam A with a product width of 1 m and film b with a product width of 1 m are each set in an unwinder as shown in FIG. 1, and while unwinding at a line speed of 20 m/min, Kasuga Electric Works Ltd. is placed on the side of the film in contact with the foam. Using the first charging device PST-2005N, charging was performed at a voltage of -15 kV with a distance of 15 mm between the electrode and the film surface. Subsequently, it was introduced into a nip roller and nipped at a pressure of 0.3 MPa to stack the foam and film to form a laminate. After that, the surface of the foam was destaticized at 4 kV using a static eliminator made by SIMCO JAPAN (power source: POWER UNIT 150, electrode ss-50), and the laminate was wound with a winding tension of 100 mN.

The potential of the created laminate was +3.1 kV, and the peeling strength of the foam and film was 40 mN/25 mm. Subsequently, slit processing was performed on this laminate, and a product with a good appearance was obtained, with no wrinkles due to deformation of the foam, no air entrapment, etc. The results are shown in Table 3.

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

In Examples 2 to 14 and Comparative Examples 1 and 2, a laminate was prepared in the same manner as in Example 1 under the conditions shown in Table 3, and the dislocation and adhesion strength of the obtained laminate were measured and evaluated by slit processing. carried out.

As shown in Table 3, good results, especially good slitting properties, were obtained in Examples 1 to 14 that satisfied the conditions specified in the present invention, but good results were obtained in Comparative Examples 1 and 2 that did not satisfy the conditions specified in the present invention. No results were obtained.

The laminate according to the present invention is applicable to all applications that require the use of thin foam, and can be especially suitable for installing shock absorbers or shock absorbers in electronic and electrical devices such as mobile phones.

1 Film 2 Foam
3 Laminate 4 Charging device
5 Static eliminator 6a, 6b nip roller
7 Guide roller 8 Opposite roller

Claims (15)

A laminate in which a film is laminated on at least one side of a sheet-shaped foam, satisfying the following requirements (A) to (E), and the potential of the laminate is in the range of -30 to +30 kV. laminate.
(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) Foam and film are directly bonded without an adhesive.
(E) Peel strength of foam and film is 10mN/25mm to 100mN/25mm According to claim 1,
A laminate with a foam thickness of 0.05 to 0.5 mm. According to claim 1,
A laminate in which the peel strength of the foam and film is in the range of 25mN/25mm to 100mN/25mm. delete According to claim 1,
A laminate whose potential is in the range of -15 to +15 kV. According to claim 1,
A laminate in which both the foam and the film are composed of olefin resin. According to claim 1,
A laminate whose apparent density of the foam is in the range of 100 kg/㎥ to 500 kg/㎥. The method according to any one of claims 1 to 3 and 5 to 7,
A laminate in which the side in close contact with the foam of the film is electrically charged. According to claim 1,
A laminate in which foam from which the film has been peeled is used to secure the parts that make up electronic and electrical devices to the device body. A method of manufacturing a laminate in which a sheet-shaped foam and a film are brought into close contact with each other, comprising a charging process in which either the foam or the film is charged by applying an electric charge, and an adhesion process in which the foam and the film are brought into close contact with each other, in this order. Manufacturing method. According to claim 10,
Manufacture of a laminate having an adhesion enhancement step of giving the outer surface of the foam or film, after the adhesion process, a charge with a polarity opposite to that of the charge on the adhesion surface between the foam and the film, thereby increasing the adhesion on the adhesion surface. method. The method of claim 10 or 11,
A method of manufacturing a laminate in which, in the charging process, the surface of the film on the side that is brought into close contact with the foam is charged. The method of claim 10 or 11,
A method of producing a laminate wherein the adhesion process includes pressing the foam and the film with a nip roller. The method of claim 10 or 11,
A method for producing a laminate using the materials (A) and (B) below.
(A) Foam with a thickness of 0.05 to 1.5 mm
(B) Film with a thickness of 25∼250㎛ and a surface resistivity of 1×10 ¹¹ Ω or more. According to claim 14,
Method for producing a laminate with a foam thickness of 0.05 to 0.5 mm.