JP2015059052A - Sheet for forming laminate, and method for producing laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet for forming a laminate that is composed mainly of EVA, can easily and sufficiently perform the removal of air bubbles present in the laminate through a pressurizing step by using a nip roll and can produce a good laminate and to provide a method for producing the laminate.SOLUTION: The sheet for forming a laminate is used in the method for producing a laminate including a step of pressurizing by using a nip roll, comprises a composition including an ethylene/vinyl acetate copolymer and a crosslinking agent, and has formed on at least one surface thereof a convexoconcave pattern composed of a concave part of lattice pattern and a convex part surrounded by the concave part. The pitch of the lattice pattern is 200-800 μm and the maximum height Ry (in accordance with JIS-B-0601-1994) of the surface on which the convexoconcave pattern is formed is 40-150 μm. The method for producing a laminate uses the sheet for forming a laminate.

Description

  The present invention relates to a laminate-forming sheet mainly composed of an ethylene-vinyl acetate copolymer used for the production of laminates such as laminated glass and solar cells (seal film for solar cell, intermediate film for laminated glass, etc.) In particular, the present invention relates to a laminate forming sheet useful for manufacturing a laminate including a step of pressing with a nip roll.

  Conventionally, a sheet (hereinafter also referred to as an EVA sheet) mainly composed of an ethylene-vinyl acetate copolymer (hereinafter also referred to as EVA) is inexpensive and has excellent adhesiveness and high transparency. It is used as a sheet for forming a laminate such as an interlayer film for laminated glass. As shown in FIG. 3A, the laminated glass interlayer film is sandwiched between glass plates 11A and 11B and exhibits functions such as penetration resistance and prevention of broken glass scattering. In addition, the EVA sheet can improve adhesion, penetration resistance, durability, and the like by crosslinking the copolymer using a crosslinking agent such as an organic peroxide.

  When manufacturing laminates such as laminated glass, etc., when laminating a laminate material such as a plurality of glass plates and a laminate-forming sheet, on the boundary surface between the laminate-forming sheet and the glass plate, etc. It is necessary to discharge the existing air so that no bubbles are generated. This is because if air bubbles are present in a laminated body such as laminated glass, performance deterioration and appearance defects may occur due to a decrease in transparency.

  Accordingly, as a method for producing a laminated body such as laminated glass, for example, (1) a laminated body in which a laminated body forming sheet is sandwiched between a plurality of substrates is put in a vacuum bag, deaerated, and pressed under heating. By performing pre-compression, the air in the laminate forming sheet and the interface between the substrate and the laminate forming sheet is removed to the extent that bubbles remain, and then in the main heating and pressurization with a high-temperature and high-pressure container. A method for sufficiently removing bubbles, or (2) a laminate in which a laminate-forming sheet is sandwiched between a plurality of substrates is heated while passing through a heating zone while being conveyed, and then sandwiched between nip rolls and pressed. Preliminary pressure bonding is used to squeeze out air at the boundary surface between the substrate and the laminate forming sheet, and then, if necessary, a method of performing main heating and pressurization with a high-temperature and high-pressure container is used. ing.

  In general, the method (2) using a nip roll is advantageous in that the crimping process can be performed continuously. For example, in Patent Document 1, in order to streamline the manufacturing process of laminated glass, it is made of a resin having specific viscoelastic properties (glass transition temperature, storage elastic modulus), and an intermediate film having a predetermined range of thickness is used. A method is disclosed in which laminated glass is continuously produced by pressure contact with a nip roll.

  However, when an EVA sheet is used as the laminate forming sheet, there is a restriction such that bubbles are difficult to escape when the thickness is increased. Therefore, the pre-compression bonding process using a vacuum bag is currently used (1) Has become the mainstream. Therefore, even when an EVA sheet is used, a method for efficiently producing a laminate by the method (2) using a nip roll has been studied. In recent years, from an EVA sheet having a specific melt viscosity, surface property, and thickness. It has been found that the use of the interlayer film for laminated glass makes it possible to satisfactorily remove bubbles in the laminated glass by a pressure-bonding process using a nip roll (Patent Document 2).

JP-A-11-209150 JP 2012-66984 A

However, even in the production method of Patent Document 2, there are restrictions on the conditions for the predetermined melt viscosity and thickness of the EVA sheet, and therefore a method with fewer restrictions is desired.
In addition, in the pre-compression process using nip rolls, it is difficult to adjust the temperature with high accuracy, so the temperature range in which the air bubbles in the laminate can be removed by nip rolls (hereinafter also referred to as nip roll processable temperature ranges) is wide. is necessary.

  Accordingly, an object of the present invention is a sheet for forming a laminate comprising EVA as a main component, and air bubbles in the laminate can be easily and sufficiently removed by a pressurizing process using a nip roll, resulting in poor appearance. It is providing the sheet | seat for laminated body formation which can manufacture the favorable laminated body without such.

  Another object of the present invention is a method for producing a laminate using a laminate-forming sheet mainly composed of EVA, and sufficiently removing bubbles in the laminate by a pressurizing step using a nip roll. It is possible to provide a production method that can produce a good laminate without appearance defects.

  According to the study by the present inventors, it was found that it is difficult to uniformly heat the laminate in the pre-compression process using the nip roll, and temperature distribution may occur in the central portion and the peripheral portion in the plan view of the laminate. It was. When EVA reaches a certain temperature, the viscosity tends to rapidly decrease. Therefore, when an EVA sheet is used as the laminate-forming sheet, when the temperature distribution occurs, EVA in the central portion and the peripheral portion of the EVA sheet in a plan view Large differences in viscosity (fluidity) may occur. Then, when the temperature of the peripheral portion in plan view is higher than that of the central portion, the EVA in the peripheral portion where the fluidity has increased blocks the bubble outlet, and large bubbles remain between the EVA sheet and the substrate such as the glass plate, and then It is considered that the bubbles cannot be removed even by the final press bonding step. It is considered that such a phenomenon could not be sufficiently prevented by the shallow embossing conventionally imparted to the laminate forming sheet. Therefore, the present inventors diligently studied the surface properties of a laminate-forming sheet (hereinafter also referred to as EVA sheet) containing EVA as a main component, and reached the present invention.

  That is, the above object is a laminate forming sheet used in a laminate production method including a step of applying pressure using a nip roll, comprising a composition comprising an ethylene-vinyl acetate copolymer and a crosslinking agent, and at least one of them. A concave / convex pattern composed of a concave portion of the lattice pattern and a convex portion surrounded by the concave portion is formed on the surface, and the pitch of the lattice pattern is 200 to 800 μm, and the maximum of the surface on which the concave / convex pattern is formed The height Ry (conforming to JIS-B-0601-1994) is 40 to 150 μm, and is achieved by the laminate-forming sheet.

  In the case of an EVA sheet in which concave and convex patterns are formed so as to have the maximum height Ry of the surface in the above range in the concave portion of the lattice pattern with the pitch in the above range, in the preliminary press-bonding step by the nip roll, the central portion in the plan view of the laminate Even when the temperature distribution occurs in the peripheral portion or the like, the shape of the concave portion of the lattice pattern can be maintained in a wide temperature range, so that bubbles at the boundary surface between the substrate such as a glass plate and the EVA sheet are easily removed. Further, since the remaining bubbles are also dispersed in a small amount, it is possible to prevent bubbles from remaining in the product by the subsequent main pressure bonding step. Furthermore, with such an EVA sheet, it is possible to achieve a nip roll processable temperature range with a sufficient width, and it is possible to easily and sufficiently remove bubbles in the laminate.

Preferred embodiments of the laminate-forming sheet of the present invention are as follows.
(1) The pitch of the lattice pattern is 250 to 750 μm, and the maximum height Ry (based on JIS-B-0601-1994) of the surface is 50 to 85 μm. Further, a wider temperature range capable of nip roll processing is obtained, and air bubbles can be easily removed from the laminated body.
(2) The area ratio (concave / convex ratio) of the area of the concave portion of the lattice pattern in plan view to the area of the convex portion surrounded by the concave portion in plan view is 0.05 to 0.4.
(3) An interlayer film for laminated glass.

In addition, the object is to sandwich a laminate-forming sheet between at least two laminate materials, to obtain a laminate, and after heating the laminate, pressurization is performed by using a nip roll. And a step of cross-linking and integrating the laminate by further heating the laminate after the crimping step, and a method for producing a laminate,
The laminate-forming sheet is made of a composition containing an ethylene-vinyl acetate copolymer and a cross-linking agent, and a concavo-convex pattern consisting of concave portions of a lattice pattern and convex portions surrounded by the concave portions is formed on at least one surface. The pitch of the lattice pattern is 200 to 800 μm, and the maximum height Ry (based on JIS-B-0601-1994) of the surface on which the concavo-convex pattern is formed is 40 to 150 μm. This is achieved by the manufacturing method of the laminate.

  As described above, if the EVA sheet has a concave / convex pattern formed so as to have the maximum height Ry of the surface of the above-mentioned range in the concave portion of the lattice pattern having the above-mentioned range, the pre-compression process using the nip rolls can be used to form the laminated body. Since air bubbles can be easily and sufficiently removed, a good laminate with no poor appearance can be produced.

The preferable aspect of the manufacturing method of the laminated body of this invention is as follows.
(1) The pitch of the lattice pattern is 250 to 750 μm, and the maximum height Ry (based on JIS-B-0601-1994) of the surface is 50 to 85 μm.
(2) The area ratio (concave / convex ratio) of the area of the concave portion of the lattice pattern in plan view to the area of the convex portion surrounded by the concave portion in plan view is 0.05 to 0.4.
(3) The laminate is a laminated glass.

  The sheet for forming a laminate mainly composed of EVA according to the present invention has a concave / convex pattern formed so as to have the maximum height Ry of the surface of the predetermined range at the concave portions of the lattice pattern having the predetermined range. Even when a temperature distribution occurs in the pre-compression bonding step, the shape of the concave portion of the lattice pattern can be maintained in a wide temperature range, so that bubbles on the boundary surface between the substrate such as a glass plate and the EVA sheet are easily removed. Further, the remaining bubbles are also dispersed in a small size, and the bubbles can be prevented from remaining in the product by the subsequent main pressure bonding step. Furthermore, with such an EVA sheet, it is possible to achieve a nip roll processable temperature range with a sufficient width, and it is possible to easily and sufficiently remove bubbles in the laminate. Therefore, by the method for manufacturing a laminate of the present invention, it is possible to manufacture a laminate using an EVA sheet with a high yield by efficiently suppressing occurrence of defective appearance using a continuous pre-bonding step. it can.

It is the schematic for demonstrating the uneven | corrugated pattern formed in the sheet | seat for laminated body formation of this invention, (a) shows a schematic plan view, (b) is line AA 'in Fig.1 (a). The schematic sectional drawing at the time of cutting is shown. It is a schematic sectional drawing which shows a typical example of the manufacturing method of the laminated body of this invention. It is a schematic sectional drawing which shows the example of a common laminated glass, (a) shows the laminated glass of two glass plates, (b) shows the laminated glass of a glass plate and a plastic film, (c ) Shows a laminated glass of a glass plate and a plastic film having a heat ray shielding layer.

  The laminate-forming sheet of the present invention is a laminate-forming sheet used in a laminate-producing method including a step of pressing using a nip roll, and is composed of a composition containing at least EVA and a crosslinking agent (EVA composition). And as shown in FIG. 1, the uneven | corrugated pattern which consists of the recessed part 11 of a lattice pattern and the several convex part 12 enclosed by the recessed part 11 is formed in at least one surface. The pitch p of the lattice pattern of the recesses 11 is 200 to 800 μm, and the maximum height Ry of the surface on which the uneven pattern is formed is 40 to 150 μm. The maximum height Ry of the surface is a value measured according to JIS-B-0601-1994. That is, a predetermined length is extracted from the roughness curve in the direction of the average line, and the sum of the height from the average line of the extracted portion to the highest peak and the depth to the lowest valley bottom is obtained. is there.

  The reason why bubbles tend to remain when an EVA sheet is used in the pre-pressing step by the nip roll is considered as follows. That is, in the preliminary press-bonding step using nip rolls, it is difficult to heat the laminate uniformly, and temperature distribution may occur in the central portion and the peripheral portion in plan view of the laminate. In general, when EVA reaches a certain temperature, the viscosity tends to decrease abruptly. Therefore, there may be a large difference in the viscosity (fluidity) of EVA at the central portion and the peripheral portion in the plan view of the EVA sheet. Then, when the temperature of the peripheral portion in plan view is higher than that of the central portion, the EVA in the peripheral portion where the fluidity has increased blocks the bubble outlet, and large bubbles remain between the EVA sheet and the substrate such as the glass plate, and then It is considered that the bubbles cannot be removed even by the final press bonding step.

  In the case of the EVA sheet on which the above-described concave / convex pattern is formed, even in the case where a temperature distribution occurs in the central portion and the peripheral portion in a plan view of the laminated body in the pre-compression bonding process using nip rolls, Since the shape of the concave portion 11 can be maintained, bubbles on the boundary surface between the substrate such as a glass plate and the EVA sheet are easily removed. Further, since the remaining bubbles are also dispersed in a small amount, it is possible to prevent bubbles from remaining in the product by the subsequent main pressure bonding step. As will be described later, in general, in the pre-bonding step using a nip roll, since heating is performed by a heating furnace or the like continuously before pressing the nip roll, it is difficult to adjust the temperature with high accuracy. If it is a sheet | seat, since the shape of the recessed part of a grating | lattice pattern can be maintained in a wide temperature range, it can be set as a sufficient width of the nip roll processable temperature range, and the bubble removal in a laminated body can be performed easily and fully. . Note that the nip roll processable temperature range is preferably 20 ° C. or higher.

  In addition, said uneven | corrugated pattern may be formed only in one surface of an EVA sheet, and may be formed in both surfaces. In terms of easy removal of bubbles on both surfaces of the EVA sheet, it is preferable that the above uneven pattern is formed on both surfaces.

  In the present invention, the pitch p of the lattice pattern of the recesses 11 of the concavo-convex pattern formed on the EVA sheet is 200 to 800 μm, preferably a minimum value of 250 μm or more, more preferably 400 μm or more, and preferably an upper limit value. It is 750 μm or less, more preferably 700 μm or less. The maximum surface height Ry is 40 to 150 μm, and the lower limit is preferably 45 μm or more, more preferably 50 μm or more, particularly preferably 60 μ or more, and the upper limit is preferably 125 μm or less. Is 85 μm or less. If the pitch of the lattice pattern is too small or the maximum height Ry is too small, the shape of the concave portion 11 of the lattice pattern may not be maintained in the pre-compression bonding process using nip rolls, and bubbles may be difficult to escape. In addition, if the pitch of the lattice pattern is too large or the maximum height Ry is too large, the groove volume of the recess 11 becomes large, and the remaining bubbles become large during the pre-bonding process by the nip roll, and the main pressure bonding. In the process, bubbles may not be completely removed. If the pitch of the lattice pattern in the above preferable range and the maximum height Ry of the surface are obtained, a wider temperature range capable of nip roll processing can be obtained, and bubbles in the laminate can be removed more easily. In FIG. 1A, the shape of the convex portion 12 in plan view is a square, but it may be a rhombus or a rectangle, and may be a parallelogram as long as the above effect can be obtained. The shape of the projection 12 in a plan view is preferably a square in that the bubbles can easily escape uniformly. Moreover, in FIG.1 (b), although the edge part of the convex part 12 is formed perpendicularly | vertically, it may be a mountain shape with a taper.

  On the other hand, when the concave / convex pattern formed on the EVA sheet is not the concave portion 11 of the lattice pattern, for example, the convex portion is a tortoiseshell type concave / convex pattern, as shown in the examples described later, it is difficult for bubbles to escape. Cannot be achieved. This is presumably because the shape of the recess is difficult to maintain and the passage through which the bubbles escape is easily blocked.

  In the present invention, in the concavo-convex pattern formed on the EVA sheet, the area ratio (concave / convex ratio) of the area in the plan view of the concave portion 11 of the lattice pattern to the area in the plan view of the convex portion 12 surrounded by the concave portion 11 is 0.05 to 0.4 is preferable, 0.1 to 0.4 is more preferable, and 0.2 to 0.4 is still more preferable. If the concave / convex ratio is too small, bubbles are difficult to escape, and if the concave / convex ratio is too large, the shape of the concave portion is difficult to be maintained. Moreover, although the line width of the lattice pattern of a recessed part changes also with the pitch of a lattice pattern, 10-100 micrometers is preferable and 10-60 micrometers is more preferable.

Below, the material of the EVA composition which comprises the sheet | seat for laminated body formation of this invention is demonstrated.
[Ethylene-vinyl acetate copolymer]
In the present invention, the content of vinyl acetate in the ethylene-vinyl acetate copolymer (EVA) is usually 20 to 40% by mass with respect to the mass of EVA. There exists a tendency for the composition obtained to become hard, so that the content of the vinyl acetate unit of EVA is low. If the content of vinyl acetate is too low, when the laminate-forming sheet obtained using the composition of the present invention is crosslinked and cured at a high temperature, the transparency of the sheet after crosslinking and curing may not be sufficient. Further, if the vinyl acetate content is too high, the hardness of the obtained sheet after cross-linking and curing may be insufficient, and further, carboxylic acid, alcohol, amine, etc. are generated, and other members in the laminate, etc. There is a possibility that foaming is likely to occur at the interface.

  In the present invention, in order to impart moderate flexibility to the sheet after cross-linking and curing, the content of vinyl acetate in EVA is preferably 20 to 35% by mass, more preferably 22 to 30% by mass, and particularly preferably 24 to 28 mass% is preferable.

  The EVA melt flow rate (MFR) (according to JIS-K7210) is preferably 1.0 g / 10 min or more. The MFR is more preferably 1.0 to 50.0 g / 10 min, and particularly preferably 4.0 to 30.0 g / 10 min. In addition, MFR is measured on condition of 190 degreeC and load 21.18N.

  In the laminate-forming sheet of the present invention, in addition to EVA, an ethylene-unsaturated carboxylic acid copolymer such as an ethylene-acrylic acid copolymer and an ethylene-methacrylic acid copolymer, the ethylene-unsaturated carboxylic acid An ionomer in which part or all of the carboxyl groups of the acid copolymer are neutralized with the above metal, ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-methyl methacrylate copolymer, ethylene -An ethylene-unsaturated carboxylic acid ester copolymer such as an isobutyl acrylate copolymer, an ethylene-n-butyl acrylate copolymer, an ethylene-isobutyl acrylate-methacrylic acid copolymer, an ethylene-acrylic acid n- Ethylene-unsaturated carboxylic acid ester-unsaturated carboxylic acid such as butyl-methacrylic acid copolymer Copolymer and ethylene-polar monomer copolymer such as an ionomer in which a part or all of its carboxyl groups are neutralized with the above metal, ethylene-vinyl ester copolymer such as ethylene-vinyl acetate copolymer, polyvinyl Acetal resins (for example, polyvinyl formal, polyvinyl butyral (PVB resin), modified PVB), polyethylene resin, and vinyl chloride resin may be used as secondary agents.

[Crosslinking agent]
In the laminate forming sheet of the present invention, the crosslinking agent used in the EVA composition can form an EVA crosslinked structure, and can improve the adhesiveness, strength, and durability of the laminate forming sheet. Is. It is preferable to use an organic peroxide or a photopolymerization initiator. Especially, since the sheet | seat for laminated body formation in which the adhesive force, moisture resistance, and the temperature dependence of penetration resistance were improved is obtained, it is preferable to use an organic peroxide.

  Any organic peroxide may be used as long as it decomposes at a temperature of 100 ° C. or higher and generates radicals. The organic peroxide is generally selected in consideration of the film formation temperature, the adjustment conditions of the composition, the curing temperature, the heat resistance of the adherend, and the storage stability. In particular, those having a decomposition temperature of 70 hours or more with a half-life of 10 hours are preferred.

  Examples of the organic peroxide include 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane, 2,5-dimethylhexane-2,5-dihydroperoxide, 3-di-t- Butyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-bis (t-butylperoxy) hexyne, α, α'-bis (t-butylperoxyisopropyl) benzene, n-butyl-4 , 4-bis (t-butylperoxy) butane, t-butylperoxy-2-ethylhexyl monocarbonate, t-hexylperoxyisopropyl monocarbonate, 2,2-bis (t-butylperoxy) butane, 1-bis (t-hexylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis (t-butylperoxy) -3,3 -Trimethylcyclohexane, 1,1-bis (t-butylperoxy) cyclohexane, 2,2-bis (4,4-di-t-butylperoxycyclohexyl) propane, 1,1-bis (t-butylperoxy) ) Cyclododecane, 1,1-bis (t-butylperoxy) cyclohexane, benzoyl peroxide curing agents (t-butylperoxybenzoate, etc.) and the like.

  As the organic peroxide, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane or tert-butylperoxy-2-ethylhexyl monocarbonate is particularly preferable. Thereby, the sheet | seat for laminated body formation which is bridge | crosslinked favorably and has the outstanding transparency is obtained.

  The content of the organic peroxide used in the EVA composition is preferably 0.1 to 5 parts by mass, more preferably 0.2 to 3 parts by mass with respect to 100 parts by mass of EVA. If the content of the organic peroxide is small, the crosslinking speed may be reduced during the crosslinking and curing, and if it is large, the compatibility with EVA may be deteriorated.

  As the photopolymerization initiator, any known photopolymerization initiator can be used, but a photopolymerization initiator having good storage stability after blending is desirable. Examples of such a photopolymerization initiator include 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, and 2-methyl-1- (4- (methylthio) phenyl). Acetophenones such as -2-morpholinopropane-1, benzoins such as benzyldimethylketal, benzophenones such as benzophenone, 4-phenylbenzophenone and hydroxybenzophenone, thioxanthones such as isopropylthioxanthone and 2-4-diethylthioxanthone, As other special ones, methylphenylglyoxylate can be used. Particularly preferably, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- (4- (methylthio) phenyl) -2-morpholinopropane-1, Examples include benzophenone. These photopolymerization initiators may be optionally selected from one or more known photopolymerization accelerators such as a benzoic acid type such as 4-dimethylaminobenzoic acid or a tertiary amine type. It can be used by mixing at a ratio. Moreover, it can be used individually by 1 type of only a photoinitiator, or 2 or more types of mixture.

  Content of the said photoinitiator is 0.1-5 mass parts with respect to 100 mass parts of EVA, Preferably it is 0.2-3 mass parts.

[Crosslinking aid]
In the laminate-forming sheet of the present invention, the EVA composition may further contain a crosslinking aid, if necessary. The crosslinking aid can improve the gel fraction of EVA and improve the adhesion and durability of the EVA film.

  The content of the crosslinking aid is generally 10 parts by mass or less, preferably 0.1 to 5 parts by mass, and more preferably 0.1 to 2.5 parts by mass with respect to 100 parts by mass of EVA. Thereby, the laminated body formation sheet which is further excellent in adhesiveness is obtained.

  Examples of the crosslinking aid (compound having a radical polymerizable group as a functional group) include trifunctional crosslinking aids such as triallyl cyanurate and triallyl isocyanurate, and (meth) acrylic esters (eg, NK ester) ) Monofunctional or bifunctional crosslinking aids. Of these, triallyl cyanurate and triallyl isocyanurate are preferable, and triallyl isocyanurate is particularly preferable.

[Adhesion improver]
In the laminate-forming sheet of the present invention, the EVA composition may further contain an adhesion improver in order to impart further excellent adhesive force. As the adhesion improver, a silane coupling agent can be used. Examples of the silane coupling agent include γ-chloropropyltrimethoxysilane, vinyltriethoxysilane, vinyltris (β-methoxyethoxy) silane, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, and γ-glycidoxypropyl. Trimethoxysilane, γ-glycidoxypropyltriethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, vinyltrichlorosilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N Mention may be made of -β- (aminoethyl) -γ-aminopropyltrimethoxysilane. These silane coupling agents may be used alone or in combination of two or more. Of these, γ-methacryloxypropyltrimethoxysilane is particularly preferred.

  The content of the silane coupling agent is preferably 0.1 to 2 parts by mass, more preferably 0.1 to 0.65 parts by mass with respect to 100 parts by mass of EVA.

[Others]
In the laminate-forming sheet of the present invention, the EVA composition may use other additives depending on the use of the laminate-forming sheet. For example, when used as an interlayer film for laminated glass or a sealing film for solar cells, various physical properties (such as mechanical properties, optical properties such as adhesion, transparency, heat resistance, light resistance, crosslinking speed, etc.) Alternatively, for adjustment, one or two kinds of various additives such as a plasticizer, an acryloxy group-containing compound, a methacryloxy group-containing compound, an epoxy group-containing compound, an ultraviolet absorber, a light stabilizer, and an anti-aging agent are used as necessary. You may add more. The addition amount of various additives is preferably in the range of 5 parts by mass or less with respect to 100 parts by mass of EVA.

[Manufacture of laminated body forming sheet]
There is no restriction | limiting in particular in the manufacturing method of the sheet | seat for laminated body formation of this invention, It can manufacture by forming the above-mentioned EVA composition into a sheet form by a conventionally well-known method. For example, the EVA composition is mixed by heating and kneading the EVA and the cross-linking agent and, if necessary, the above-described various materials with a super mixer (high-speed fluid mixer), a twin-screw kneader, a roll mill, etc., and then extruded. It can be manufactured by a method of forming into a sheet by molding or calendar molding (calendering). And after shaping | molding in a sheet form, the embossing roller and embossing plate of the reverse pattern of the said uneven | corrugated pattern are pressed on the sheet | seat surface on the surface of at least one of a sheet | seat, and said uneven | corrugated pattern is formed. The heat-kneading temperature and the molding temperature are preferably temperatures at which the crosslinking agent does not react or hardly reacts. For example, 40 to 90 ° C, particularly 50 to 80 ° C is preferable. The thickness of the laminate forming sheet is generally in the range of 50 μm to 2 mm.

  The laminate-forming sheet of the present invention may be composed of one EVA sheet or may have a multilayer structure in which two or more EVA sheets are laminated.

  When a laminate is produced using the laminate-forming sheet of the present invention, air bubbles in the laminate can be sufficiently removed in the pressure-bonding process in which pressurization is performed using a nip roll, resulting in a decrease in transparency of the laminate due to air bubbles. Since it is difficult, the laminate-forming sheet of the present invention is suitable as an interlayer film for laminated glass that requires high transparency.

[Manufacturing method of laminate]
The manufacturing method of the laminated body of this invention is demonstrated referring drawings. The method for producing a laminate of the present invention includes a step of sandwiching a laminate-forming sheet between at least two laminate materials to obtain a laminate (uncured), heating the laminate (uncured), It includes a step of pre-pressing by pressurizing using a nip roll, and then a step of cross-linking and integrating by further heating the laminate (after pre-pressing). And as a laminated body formation sheet, the same prescribed EVA sheet as the laminated body formation sheet of the present invention (consisting of a composition containing EVA and a cross-linking agent, surrounded on at least one surface by a concave portion of a lattice pattern and the concave portion. An EVA sheet in which a concavo-convex pattern consisting of convex portions is formed, the pitch of the lattice pattern is 200 to 800 μm, and the maximum height Ry of the surface on which the concavo-convex pattern is formed is 40 to 150 μm) Is used. As described above, even if the EVA sheet is an EVA sheet in which a concave / convex pattern is formed so as to have the maximum height Ry of the surface in the above range in the concave portion of the lattice pattern having the pitch in the above range, a spare by a nip roll is used. Since the bubbles in the laminate can be easily and sufficiently removed by the crimping step, a good laminate having no poor appearance can be produced.

  FIG. 2 is a schematic cross-sectional view showing a typical example of the method for producing a laminate of the present invention. In FIG. 2, first, the laminate forming sheet 102 is sandwiched between two substrates 101 </ b> A and 101 </ b> B to form a laminate (uncured) 120. The laminate is passed through the heating furnace 301 while being transported by the transport device 303. The heating furnace 301 includes a heater unit 302 and can heat the laminated body forming sheet 102 to a predetermined temperature while the laminated body (uncured) 120 passes through the heating furnace 301. Thereafter, the laminate (uncured) 120 is passed between nip rolls 304 composed of two pairs of opposing roll portions. The nip roll 304 is a device that continuously pressurizes what passes between the roll portions with a predetermined linear pressure. Thereby, the laminated body (uncured) 120 is pressurized, and the heated laminated body forming sheet 102 is pressure-bonded to the boundary surface between the substrates 101A and 101B to obtain a laminated body (after preliminary pressure bonding) 120 '. At this time, since the laminate forming sheet 102 is an EVA sheet on which the above-described uneven pattern is formed, the central portion and the peripheral portion of the laminate (uncured) 120 in plan view are uniformly heated by the heating furnace 301. Even if the temperature distribution is generated in the central portion and the peripheral portion in the plan view of the laminate forming sheet 102, from the boundary surface between the laminate forming sheet 102 and the substrates 101A and 101B by the pressurizing process using the nip roll 304. It is easy to remove bubbles.

  A conventionally well-known thing can be used for the conveying apparatus 303, the heating furnace 301, and the nip roll 304. FIG. Any method may be used for heating the heater unit 32 of the heating furnace 301. Examples thereof include a hot air heating method and an infrared heating method. Instead of the heating furnace 301, a heating roll type heating device may be used. The heating is not particularly limited as long as it is a temperature at which the crosslinking agent contained in the EVA composition of the laminate forming sheet 102 does not react. In consideration of the fluidity of the laminate-forming sheet 102 and the stress relaxation property during pressurization, the laminate-forming sheet 102 is heated so that the temperature of the laminate-forming sheet 102 is in the range of 55 to 95 ° C. before being pressed by the nip roll. It is preferable to perform heating so that the temperature is in the range of 65 to 95 ° C, particularly 70 to 95 ° C. The temperature difference between the central portion and the peripheral portion in plan view of the laminate forming sheet is preferably 15 ° C. or less.

  The nip roll 304 may be any type and may have a plurality of pairs of nip rolls. Moreover, in order to avoid the temperature fall at the time of pressurization, what was comprised with the heating roll may be used. The linear pressure applied by the nip roll 304 is not particularly limited, but is preferably 5 to 100 kN / m, and more preferably 10 to 50 kN / m.

After the above-described pressure bonding step, the layered body (after preliminary pressure bonding) 120 ′ is heated to perform a cross-linking and integration step (heating cross-linking step) to obtain a layered body. A conventionally well-known method can be used for a heat-crosslinking process. For example, high-temperature and high-pressure treatment such as autoclave can be used. There is no restriction | limiting in particular in heating conditions, It adjusts also by mixing | blending of the crosslinking agent etc. which are contained in the above-mentioned EVA composition. Usually, heating is performed at 100 to 155 ° C. (particularly around 130 ° C.) for 10 minutes to 1 hour. Heating is preferably performed while pressurizing at a pressure of 1.0 × 10 ³ Pa to 5.0 × 10 ⁷ Pa. At this time, cooling after cross-linking of the laminate is generally performed at room temperature. Air bubbles are sufficiently removed from the laminated body (after pre-compression bonding) 120 ′ by the pressure bonding step of applying pressure using a nip roll, so that a good laminated body can be obtained by the heat crosslinking step.

  According to the method for manufacturing a laminate of the present invention, it is possible to sufficiently remove bubbles in the laminate in the pressure-bonding step of applying pressure using a nip roll, and it is difficult to cause a decrease in transparency of the laminate due to bubbles. It is suitable for the production of laminated glass that requires high transparency.

[Manufacture of laminated glass]
When the laminated glass is produced by the method for producing a laminate of the present invention, for example, the laminate forming sheet of the present invention is used as the interlayer film 22 for laminated glass of the laminated glass shown in FIG. And 21B can be manufactured according to the manufacturing method of the laminated body shown in FIG. In other words, a laminated body forming sheet (intermediate film) is sandwiched between two transparent substrates such as glass plates to form a laminated body (uncured), heated, and then pressed using a nip roll. Is preliminarily pressure-bonded by heating and further integrated by crosslinking to produce a laminated glass.

  Examples of the transparent substrate include green terephthalate (PET), polyethylene naphthalate (PEN), polyethylene butyrate, polymethyl methacrylate, in addition to glass plates such as green glass, silicate glass, inorganic glass plate, and non-colored transparent glass plate. A plastic substrate or film such as (PMMA) may be used. A glass plate is preferable in terms of heat resistance, weather resistance, impact resistance, and the like. The thickness of the transparent substrate is generally about 0.1 to 20 mm. The two transparent substrates may be the same or may be used in combination with different base materials. As an example of combining different transparent substrates, in FIG. 3B, an interlayer film 32 for laminated glass using the laminate forming sheet of the present invention is sandwiched between a glass plate 31 and a plastic film 33 such as a PET film. Then, a PET film-laminated glass produced in the same manner as described above is shown. In FIG. 3C, an interlayer film for laminated glass 42 using the laminate-forming sheet of the present invention is heated on the glass plate 41 and the surface. A heat ray shielding PET laminated glass produced in the same manner as described above by being sandwiched between plastic films 43 on which a shielding layer 44 is formed is shown.

Hereinafter, the present invention will be described with reference to examples.
[Examples 1 to 13, Comparative Examples 1 to 19]
1. Preparation of Laminate Forming Sheet A composition having the following composition was kneaded at 60 to 70 ° C. with a roll mill and calendered at 70 ° C. to prepare an EVA sheet (thickness: 0.5 mm). And the embossing plate which has the inversion pattern of a desired uneven | corrugated pattern was pressed to the EVA sheet | seat, and the laminated body formation sheet of each Example and comparative example which has the uneven | corrugated pattern shown to Tables 1-3 was produced. In addition, the maximum height Ry of the surface on which the concavo-convex pattern was formed was measured according to JIS B-0601-1994 using a surface roughness meter SURFCOM 480 (manufactured by Tokyo Seimitsu Co., Ltd.). The concave / convex ratio was calculated from the area measured from the cross section.
(Combination)
EVA (Ultrasen UE634 (manufactured by Tosoh Corporation), vinyl acetate content 26% by mass): 100 parts by mass Crosslinking agent (tert-butyl peroxy-2-ethylhexyl monocarbonate (perbutyl E (manufactured by NOF Corporation))): 2 Mass parts Crosslinking aid (triallyl isocyanurate): 1 part by mass Silane coupling agent (γ-methacryloxypropyltrimethoxysilane (SZ6030 (manufactured by Toray Dow Corning)): 0.3 parts by mass

2. Production of laminated body (laminated glass) Using each laminated body forming sheet as an intermediate film, a laminated body (uncured) sandwiched between two glass plates (size: 1000 mm × 1000 mm, thickness: 3 mm) is formed. Then, using a pressure bonding device having a heating device (hot air heating method) and a pressure device using a nip roll (see FIG. 2), the laminate-forming sheet is heated, then pre-bonded, and then subjected to a temperature of 135 ° C. by an autoclave. A laminated glass was produced by pressure treatment for 60 minutes under the above conditions. At this time, it is performed while changing the surface temperature of the glass plate in the preliminary press-bonding of the laminate by the nip roll, observing the appearance of the obtained laminated glass, evaluating the state of the bubbles, and the range in which no bubbles that can be visually confirmed are recognized The width of the pre-compression bonding temperature (temperature range at which nip roll processing is possible) from which a laminated glass can be obtained was obtained. The surface temperature of the glass plate was measured with a radiation thermometer.

3. Evaluation results The evaluation results are shown in Tables 1 to 3.

  As shown in Tables 1 to 3, a concavo-convex pattern composed of a concave portion of the lattice pattern and a convex portion surrounded by the concave portion is formed, the pitch of the lattice pattern is 200 to 800 μm, and the maximum height Ry of the surface is The laminate forming sheets (EVA sheets) of Examples 1 to 13 having a thickness of 40 to 150 μm show a nip roll processable temperature range of 20 ° C. or higher in a press bonding process using a nip roll, and a preliminary press bonding process using the nip roll. It was shown that the laminated glass having a good appearance can be easily produced by removing bubbles. On the other hand, the laminated body forming sheets of Comparative Examples 1 to 16 having uneven patterns outside the above range, and Comparative Examples 17 to 19 having a turtle shell shape in the plan view of the convex portion have a nip roll processable temperature range of 10 ° C. or less. It was difficult to remove air bubbles in the pre-compression process using a nip roll.

  In addition, this invention is not limited to the structure and Example of said embodiment, A various deformation | transformation is possible within the range of the summary of invention.

  According to the present invention, a laminate such as laminated glass can be provided with high productivity using a laminate-forming sheet containing EVA that is inexpensive and excellent in adhesiveness and transparency.

11 Concave part 12 of lattice pattern Convex part 21A, 21B Transparent substrate 22, 32, 42 Intermediate film 31 for laminated glass 31, 41 Glass plate 33, 43 Transparent plastic film 44 Heat ray shielding layer
101A, 101B Substrate 102 Laminate Forming Sheet 120 Laminate (Uncured)
120 'laminate (after pre-bonding)
301 Heating furnace 302 Heater unit 303 Conveying device 304 Nip roll

Claims (8)

A laminate forming sheet used in a laminate production method including a step of applying pressure using a nip roll,
Comprising a composition comprising an ethylene-vinyl acetate copolymer and a crosslinking agent;
On at least one surface, a concavo-convex pattern consisting of a concave portion of a lattice pattern and a convex portion surrounded by the concave portion is formed,
The lattice pattern has a pitch of 200 to 800 μm, and a maximum height Ry (based on JIS-B-0601-1994) of the surface on which the concavo-convex pattern is formed is 40 to 150 μm. Body forming sheet.   The laminate forming sheet according to claim 1, wherein the pitch of the lattice pattern is 250 to 750 μm, and the maximum height Ry (based on JIS-B-0601-1994) of the surface is 50 to 85 μm.   The area ratio (concave / convex ratio) of the area of the concave portion of the lattice pattern in plan view to the area of the convex portion surrounded by the concave portion in plan view is 0.05 to 0.4. A laminate forming sheet.   It is an intermediate film for laminated glass, The sheet | seat for laminated body formation of any one of Claims 1-3. Sandwiching a laminate-forming sheet between at least two laminate materials to obtain a laminate,
A pressure-bonding step in which the laminated body is heated and then pressure-bonded by pressurization using a nip roll; and after the pressure-bonding step, the layered body is further heated and cross-linked and integrated. A method of manufacturing a laminate,
The laminate-forming sheet is composed of a composition containing an ethylene-vinyl acetate copolymer and a crosslinking agent,
On at least one surface, a concavo-convex pattern consisting of a concave portion of a lattice pattern and a convex portion surrounded by the concave portion is formed,
The lattice pattern has a pitch of 200 to 800 μm, and a maximum height Ry (based on JIS-B-0601-1994) of the surface on which the concavo-convex pattern is formed is 40 to 150 μm. Body manufacturing method.   The method for manufacturing a laminate according to claim 5, wherein a pitch of the lattice pattern is 250 to 750 μm, and a maximum height Ry (based on JIS-B-0601-1994) of the surface is 50 to 85 μm.   The area ratio (concave / convex ratio) of the area of the concave portion of the lattice pattern in plan view to the area of the convex portion surrounded by the concave portion in plan view is 0.05 to 0.4. The manufacturing method of the laminated body of description.   The said laminated body is a laminated glass, The manufacturing method of any one of Claims 5-7.

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