JP2014214211A - Composition for producing sheet for forming laminate, production method of the same, and sheet for forming laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composition for producing a sheet for forming a laminate including an ethylene-vinyl acetate copolymer and a polystyrene-based resin, which is excellent in working characteristics such as a film forming property in producing a sheet.SOLUTION: A composition for producing a sheet for forming a laminate including an ethylene-vinyl acetate copolymer and a polystyrene-based resin is disclosed. The composition has a sea-island structure in which the ethylene-vinyl acetate copolymer forms a sea phase and the polystyrene-based resin forms an island phase. An average diameter (((average major diameter (l))+(average minor diameter (d)))/2) of the island phase composed of the polystyrene-based resin is 40 μm or less and an average aspect ratio ((average major diameter (l))/(average minor diameter (d))) of the island phase composed of the polystyrene-based resin is 40 or less. A production method of the composition, and a sheet for forming a laminate using the composition are disclosed.

Description

  The present invention relates to a composition for producing a sheet containing an ethylene-vinyl acetate copolymer and a polystyrene-based resin used for forming a laminate such as a sealing film for solar cells and an intermediate film for laminated glass. The present invention relates to a composition excellent in processing characteristics such as film forming properties.

  Conventionally, a sheet (EVA sheet) made of a composition containing an ethylene-vinyl acetate copolymer (hereinafter also referred to as EVA) as a main component is inexpensive and has high transparency. And as a sealing film for solar cells. As shown in FIG. 2, the laminated glass intermediate film is sandwiched between the glass plates 11A and 11B and has a surface-side transparent protective member 21 made of a solar cell 24 and a glass substrate so as to show penetration resistance. And between the solar cell 24 and the back-side protection member (back cover) 22 and exhibit functions such as ensuring insulation and ensuring mechanical durability.

  In recent years, ethylene copolymers such as EVA, polyethylene (hereinafter also referred to as PE), polypropylene (hereinafter also referred to as PP), etc., for the purpose of improving heat resistance, creep resistance, and water vapor permeability. A sealing film composition or a sealing sheet containing polyolefin has been developed (Patent Documents 1 and 2).

JP 2001-332750 A JP 2010-059277 A

  In addition, as a thermoplastic resin that is widely used in the same manner as the above-described polyolefin, there is a polystyrene resin (hereinafter also referred to as PSs) such as polystyrene (hereinafter also referred to as PS). In addition, a polystyrene resin can be mixed with an ethylene copolymer. By mixing the polystyrene resin, it can be expected to improve the durability of the sealing film composition or the sealing sheet (reducing the amount of acetic acid generated), improve the insulation, and improve the dimensional stability due to high heat resistance.

  However, according to the study by the present inventors, a composition in which EVA and a polystyrene resin are mixed has lower processing characteristics at the time of sheet production than a composition containing EVA as a main component (EVA composition). I found out that

  That is, when the resin composition is formed into a sheet, for example, the materials are first mixed by a primary kneading step, and then, if necessary, secondary kneading such as roll kneading is performed, and the film is formed by calendering or the like. At this time, the viscosity of the resin composition in the film-forming process after the primary kneading process after the primary kneading process greatly affects the processing characteristics such as film-forming properties. It is necessary to adjust to a viscosity range). Since the viscosity of the resin composition generally changes according to the temperature, the viscosity can be adjusted by adjusting the temperature of the resin composition. In the case of an EVA composition, the viscosity gradually changes with a change in temperature in the vicinity of the temperature at which the workable viscosity range can be obtained. Therefore, the width of the temperature range in which the workable viscosity range can be obtained (also referred to as the workable temperature range). ) Is large.

  Even in a resin composition in which EVA and a polystyrene resin are mixed, since the polystyrene resin is non-crystalline, the processable temperature range is not a problem. However, since the polystyrene resin has a high melting point, the EVA and the polystyrene resin In the resin composition in which is mixed with the EVA composition, the temperature at which the workable viscosity range is obtained tends to be higher than that of the EVA composition, and the energy cost is increased. Especially when the mixing ratio of polystyrene resin is high, the existing film forming apparatus for processing the EVA composition, for example, a calender molding apparatus using water as a temperature control solvent, cannot be processed beyond the temperature control range. In addition, there is a possibility that the processable viscosity cannot be realized at a temperature that can be processed by a normal molding apparatus or the like.

  Accordingly, an object of the present invention is a composition for producing a laminate-forming sheet containing an ethylene-vinyl acetate copolymer and a polystyrene resin, and has a problem in a temperature range where the above processable viscosity is obtained. An object of the present invention is to provide a composition which is improved and has excellent processing characteristics such as film-forming properties during sheet production.

  Moreover, the objective of this invention is providing the manufacturing method of the said sheet | seat composition for laminated body formation.

  Furthermore, the objective of this invention is providing the sheet | seat for laminated body formation using the said composition for sheet | seat formation for laminated body formation.

  The above object is a laminate-forming sheet manufacturing composition comprising an ethylene-vinyl acetate copolymer and a polystyrene resin, wherein the ethylene-vinyl acetate copolymer is a sea phase, and the polystyrene resin is It has a sea-island structure as an island phase, and the average diameter ((average major axis (l) + average minor axis (d)) / 2) of the island phase made of the polystyrene resin is 40 μm or less, and from the polystyrene resin The average aspect ratio of the island phase (average major axis (l) / average minor axis (d)) is 40 or less. As a result, even in a composition in which an ethylene-vinyl acetate copolymer (EVA) and a polystyrene resin (PSs) are mixed, the temperature at which a processable viscosity range can be obtained is close to that of an EVA composition, and processing characteristics are obtained. Can be improved.

  This is because, in the above composition, the EVA component is the sea phase (continuous phase) and the PSs component is the island phase, so that EVA and PSs are a co-continuous structure, or the EVA component is the island phase and the PSs component is the sea phase. This is thought to be because the physical properties of PSs are less likely to be expressed as compared to the case where they are mixed. Moreover, the processing characteristic of a composition can be improved and the compounding ratio of PSs can be made high by making the average diameter of the island phase of PSs and the average aspect ratio of the island phase of PSs as described above. .

  Preferred embodiments of the laminate-forming sheet-producing composition of the present invention are as follows.

(1) The mass ratio (EVA: PSs) of the ethylene-vinyl acetate copolymer (EVA) and the polystyrene resin (PSs) is in the range of 65:35 to 45:55. If the blending ratio of EVA and PSs is in the above range, effects such as improvement in durability by blending PSs can be sufficiently obtained, and the composition has excellent processing characteristics by having the sea-island structure described above. be able to.
(2) The sea-island structure is such that the ethylene-vinyl acetate copolymer (EVA) and the polystyrene-based resin (PSs) have a viscosity V _PSs [Pas] of PSs with respect to a viscosity V _EVA [Pa · s] of _EVA . -It is obtained by kneading under the condition that s] is 0.1 to 20.0 times. Thereby, it can be set as the composition which has said sea-island structure in which the compounding ratio of PSs is still higher.
(3) The sea-island structure is obtained by kneading the ethylene-vinyl acetate copolymer and the polystyrene resin under conditions of a shear rate of 10 to 1500 s ⁻¹ .
(4) The temperature at which the viscosity of the composition is 30000 Pa · s is 70 to 100 ° C., and the width of the temperature range in which the viscosity of the composition is 20000 to 50000 Pa · s is 5.0 ° C. or more.
(5) The melt flow rate defined by JIS K7210 of the ethylene-vinyl acetate copolymer is 1.0 to 50.0 g / 10 min.
(6) The vinyl acetate content of the ethylene-vinyl acetate copolymer is 20 to 40% by mass.

Another object of the present invention is a method for producing a laminate-forming sheet-producing composition of the present invention, wherein the ethylene-vinyl acetate copolymer (EVA) and the polystyrene resin (PSs) are made of EVA. is achieved by a manufacturing method wherein the viscosity of _PSs V PSs [Pa · s] includes a kneading step of kneading under conditions to be 0.1 to 20.0 times relative viscosity V _EVA [Pa · s] .

In the production method of the present invention, the kneading step is preferably a step of kneading under conditions of a shear rate of 10 to 1500 s ⁻¹ . Moreover, it is preferable that the kneading step is a step of kneading under a temperature condition of 100 to 200 ° C.

  Furthermore, an object of the present invention is a sheet for forming a laminate, wherein the composition of the present invention is formed into a sheet. Since the laminate-forming sheet of the present invention is manufactured using the composition of the present invention, by including PSs, heat resistance and the like are imparted and obtained under the same conditions as the EVA composition, This is a high-quality and low-cost sheet for forming a laminate.

  The laminate-forming sheet of the present invention is preferably a laminated glass interlayer film or a solar cell sealing film.

  According to the present invention, in a composition for producing a laminate-forming sheet such as an interlayer film for laminated glass and a sealing film for solar cell, which has improved durability by blending PSs with EVA, A processable viscosity range is obtained at the same temperature as in the case of the composition, and a composition having excellent processing characteristics can be obtained. Therefore, the composition of the present invention can produce a laminate-forming sheet under the same conditions as the EVA composition, and the laminate-forming sheet thus obtained can be said to be of high quality and low cost. .

It is a schematic sectional drawing for demonstrating the sea island structure of the composition for sheet | seat formation for laminated bodies formation of this invention. It is a schematic sectional drawing of a general laminated glass It is a schematic sectional drawing of a common solar cell.

  Hereinafter, the composition for producing a laminate-forming sheet of the present invention will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view for explaining the sea-island structure of the composition for producing a laminate-forming sheet of the present invention, and FIG. 1 (a) shows a state where EVA and PSs have a co-continuous structure. 1 (b) shows a state of sea-island structure in which EVA is a sea phase (continuous phase) and PSs is an island phase, and FIG. 1 (c) shows a PSs component is a sea phase and an EVA component is It shows the state of sea island structure, which is an island phase.

  In the resin composition in which EVA and PSs are mixed, the states shown in FIGS. 1A to 1C can be taken depending on the mixing ratio and mixing conditions. The composition for producing a laminate-forming sheet of the present invention contains EVA PSs, and as shown in FIG. 1 (b), the EVA component is a sea phase and the PSs component is an island phase, which will be described later. It has a specific sea-island structure.

  When manufacturing a sheet for forming a laminate using a resin composition, for example, first, a primary kneading step of mixing each material is performed using a biaxial kneader and the like, and then, if necessary, two steps such as roll kneading are performed. Next, kneading is performed to form a film by calendar molding or extrusion molding. At this time, since the viscosity of the resin composition in the film-forming process after the primary kneading process greatly affects the processing characteristics such as film-forming properties, the viscosity of the resin composition is adjusted to a certain range (processable viscosity range). It becomes necessary to do. For example, in order to obtain good film forming properties in calendar molding or the like using an EVA composition, the viscosity of the resin composition in the film forming process is preferably 5,000 to 100,000 Pa · s, and more preferably 20,000 to 50,000 Pa · s. .

  Since the viscosity of the resin composition generally changes depending on the temperature, the viscosity can be adjusted by adjusting the temperature of the resin composition. Since the change in the viscosity accompanying the temperature change varies depending on the resin composition, the width of the temperature range (processable temperature width) where the processable viscosity range is obtained varies depending on the resin composition. Usually, it is difficult to adjust the temperature of the resin composition with high accuracy in a film forming process and the like, and it becomes difficult to process. Therefore, the processable temperature range of the resin composition is preferably large, and generally 5 ° C. or more is preferable. . In addition, the temperature at which the workable viscosity range can be obtained also increases the energy cost when the temperature becomes high.For example, when using a film forming apparatus such as a calendering apparatus using water as a temperature adjusting solvent, the temperature adjusting range is set. There is a risk that it will be impossible to process beyond that. Therefore, the temperature at which the workable viscosity range is obtained is preferably 95 ° C. or lower.

  In the case of an EVA composition, the viscosity gradually changes with the change of temperature near the temperature at which the above processable viscosity range is obtained, so a processable temperature range of 5 ° C. or more is obtained, and the processable viscosity range Is obtained at a temperature of 90 ° C. or lower.

  On the other hand, in the resin composition in which EVA and PSs are mixed, the state of the resin composition is such that the EVA component and the PSs component as shown in FIG. In the case of a mixed composition having a sea-island structure in which the PSs component as shown in FIG. 1C is a sea phase and the EVA component is an island phase as shown in FIG. 1C, a processable viscosity range is obtained. The temperature may exceed 95 ° C. On the other hand, even if the blending ratio of EVA and PSs is the same, the state of the resin composition is the sea island where the EVA component as shown in FIG. 1B is the sea phase and the PSs component is the island phase. In the case of the composition of the present invention having a structure, the temperature at which a workable viscosity range can be obtained can be brought close to the EVA composition, and the processing characteristics can be improved. This is because when the EVA component is the sea phase and the PSs component is the island phase, the EVA and PSs have a co-continuous structure (FIG. 1 (a)), or the EVA component is the island phase and the PSs component is the sea phase. This is probably because the physical properties of PSs are less likely to be expressed as compared with the case where the mixture is mixed (FIG. 1C).

  Moreover, in the composition of this invention, the form of the island phase which consists of PSs which comprises a sea island structure is prescribed | regulated. As for the size of the island phase, for example, in FIG. 1B, the cross-sectional shape is shown as a circle or an ellipse, but the average value of the average major axis (l) and the average minor axis (d) of the island phase is averaged. In the case of the diameter, the average diameter ((average major axis (l) + average minor axis (d)) / 2) of the island phase made of PSs is 40 μm or less. Thereby, the processing characteristics of the resin composition can be further improved. Moreover, the compounding ratio of PSs can be further increased by making the island phase dense. The average diameter of the island phase is more preferably 2 to 30 μm, particularly preferably 5 to 25 μm. If the size of the island phase is too large, a property close to a co-continuous structure may occur, and if it is too small, the viscosity may increase.

  The shape of the island phase is not particularly specified, and examples of the cross-sectional shape include a polygon such as a circle, an ellipse, and a rectangle, a rounded polygon such as a rounded rectangle, or a combination of these. It is done. When the island phase has a polygonal or rounded polygonal shape, the average diameter of the island phase is the average major axis (l) and the average with the maximum distance in the longitudinal direction as the major axis and the maximum distance in the width direction as the minor axis. The minor axis (d) is calculated.

  Further, if the average aspect ratio (average major axis (l) / average minor axis (d)) of the island phase made of PSs is too large, it becomes easy to form a co-continuous structure due to coalescence of the island phases, and is 40 or less. .

  Thereby, the compounding ratio of PSs can be further increased. The average aspect ratio of the island phase is more preferably 1 to 30, and particularly preferably 1 to 10.

  These numerical values are, for example, a photograph in which the cross section of the resin composition (by cross-section using a microtome) is magnified 1000 times with an optical microscope or a transmission electron microscope, or the cross section of the resin composition is AFM (interatomic It can be calculated by measuring the island phase in an arbitrarily sampled part from a photograph obtained by mapping the elastic modulus using a force microscope.

  In the composition of the present invention, the blending ratio of EVA and PSs is not particularly limited, but the durability of the laminate-forming sheet obtained by mixing PSs (reduction in acetic acid generation), insulation improvement, In order to obtain a composition with sufficient effects such as improvement in dimensional stability due to high heat resistance, and sufficient sea island structure as described above, and excellent processing characteristics, the mass ratio of EVA and PSs (EVA: PSs) is preferably in the range of 65:35 to 45:55. Since the effect of the present invention is exhibited particularly when the blending ratio of PSs is high, EVA: PSs is more preferably 60:40 to 45:55, and particularly preferably 50:50 to 45:55.

In the composition of the present invention, the above-mentioned sea-island structure may be obtained under any conditions. In the case of a composition having a higher PSs blending ratio, it is difficult to form a sea-island structure as shown in FIG. For example, when EVA and PSs are kneaded, they are kneaded under conditions where the viscosity V _PSs [Pa · s] of PSs is 0.1 to 20.0 times the viscosity V _EVA [Pa · s] of _EVA . Is preferably obtained. When EVA and PSs are kneaded under these conditions, a composition having a sea-island structure with a higher blending ratio of PSs can be obtained. In the above kneading conditions, the viscosity V _PSs [Pa · s] of _{PSs with} respect to the _EVA viscosity V _EVA [Pa · s] is more preferably 2.0 to 18.0 times, and further preferably 4.0 to 18.0. In particular, 6.0 to 18.0 times is preferable. As a result, the EVA component flows better than the PSs component, so that even with a small amount of EVA blended, the EVA component flows easily, and only EVA tends to form a continuous phase. Thereby, it can be set as the composition which has a sea island structure where the compounding ratio of PSs is still higher.

Further, under the above conditions, the EVA viscosity V _EVA is preferably 600 to 50000 Pa · s, more preferably 1000 to 20000 Pa · s. On the other hand, the viscosity V _PSs of PSs is preferably 1000 to 70000 Pa · s, and more preferably 5000 to 50000 Pa · s. The viscosity of these resins can be measured using, for example, a capillary rheometer, the shear rate is 18 s ⁻¹ , and the temperature is the actual processing temperature. The viscosity ratio can be calculated from this viscosity.

Moreover, as conditions for forming the sea-island structure, the shear rate when kneading EVA and PSs is preferably 10 to 1500 s ⁻¹ . Thereby, the island phase of PSs can be formed more densely, and a composition having a sea-island structure with a higher blending ratio of PSs can be obtained. In the above kneading conditions, the shear rate is further preferably 100 to 1000 s ⁻¹ , particularly preferably 200 to 800 s ⁻¹ .

Since the composition of the present invention exerts an effect at the stage of being used in the film forming process in the production of the laminate-forming sheet, the temperature at which the viscosity of the composition becomes 30000 Pa · s (the central processing in the composition of the present invention) (Possible temperature) is preferably 70 to 100 ° C, more preferably 80 to 95 ° C. Moreover, it is preferable that the width | variety (temperature range which can process the composition of this invention) of the temperature range from which the viscosity of a composition will be 20000-50000 Pa.s is 5.0 degreeC or more.

The relationship between the viscosity and temperature of these resin compositions can be determined, for example, by using a capillary rheometer and measuring the viscosity by increasing the temperature at a shear rate of 18 s ⁻¹ .

[Polystyrene resin]
In the present invention, the polystyrene resin means a polymer having a repeating unit derived from an aromatic vinyl compound monomer. Examples of the aromatic vinyl compound monomer include styrene, α-methylstyrene, β-methylstyrene, paramethylstyrene, and halostyrene. Polystyrene resins include homopolymers of these aromatic vinyl compound monomers, or polybutadiene, polyisoprene, butyl rubber, EPDM, ethylene-propylene copolymer, natural rubber, epichlorohydrin, etc. of these polymers. And an aromatic vinyl compound-containing copolymer such as a styrene-acrylonitrile copolymer, a styrene-butadiene copolymer, a styrene-maleic anhydride copolymer, and the like. There is no restriction | limiting in particular also as a manufacturing method of a polystyrene-type resin, A well-known polymerization method can be used. As the polystyrene resin in the present invention, polystyrene is preferable.

  Polystyrene is a styrene homopolymer (general polystyrene) and styrene polymer modified with synthetic rubber (impact polystyrene) to improve impact resistance, as defined in JIS. JIS K6923 -1: Refer to the annex of 1997). In the present invention, general-purpose polystyrene (PS) is particularly preferable.

The density of PS (according to JIS K7112: 1999) is generally 1.03-1.09 g / cm ³ . The melt flow rate (MFR) of PS (according to JIS K7210: 1999) is preferably 1 g / 10 min or more, and more preferably 1.5 to 30.0 g / 10 min. The MFR was measured under the conditions of 200 ° C. and load 49.03N.

[Ethylene-vinyl acetate copolymer]
In this invention, the content rate of the vinyl acetate in an ethylene-vinyl acetate copolymer (EVA) is 20-45 mass% normally 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 vinyl acetate content is less than 20% by mass, the laminate-formed sheet obtained by using the composition of the present invention may be crosslinked and cured at a high temperature, whereby the transparency of the sheet after crosslinking and curing may not be sufficient. is there. Moreover, when it exceeds 45 mass%, the hardness of the sheet | seat after bridge | crosslinking hardening obtained may become inadequate, and also carboxylic acid, alcohol, an amine, etc. generate | occur | produce and in an interface with the other member in a laminated body, etc. There is a risk that foaming is likely to occur.

  In this invention, in order to provide moderate softness | flexibility to the sheet | seat after bridge | crosslinking hardening, 20-40 mass% is preferable and, as for the vinyl acetate content rate in EVA, 22-35 mass% is preferable.

  The EVA melt flow rate (MFR) (according to JIS K7210: 1999) 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 composition for the solar cell sealing film of the present invention, in addition to EVA, an ethylene-unsaturated carboxylic acid copolymer such as an ethylene-acrylic acid copolymer or an ethylene-methacrylic acid copolymer, the ethylene -Ionomer, ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-methyl methacrylate copolymer in which some or all of the carboxyl groups of the unsaturated carboxylic acid copolymer are neutralized with the above metals. Polymer, ethylene-isobutyl acrylate copolymer, ethylene-unsaturated carboxylic acid ester copolymer such as ethylene-n-butyl acrylate copolymer, ethylene-isobutyl acrylate-methacrylic acid copolymer, ethylene- Ethylene-unsaturated carboxylic acid ester-unsaturated polymer such as n-butyl acrylate-methacrylic acid copolymer An ethylene-polar monomer copolymer such as an ionomer in which a part or all of the carboxyl group thereof is neutralized with the above metal, an ethylene-vinyl ester copolymer such as an ethylene-vinyl acetate copolymer, etc. Polyvinyl acetal resins (for example, polyvinyl formal, polyvinyl butyral (PVB resin), modified PVB), and vinyl chloride resin may be used as secondary materials.

  In addition to EVA and PSs, the composition of the present invention may contain a crosslinking agent, a crosslinking aid, an adhesion improver, a plasticizer, and the like as necessary.

[Crosslinking agent]
The crosslinking agent can form an EVA crosslinked structure, and can improve the strength, adhesion and durability of the laminate-forming sheet obtained using the composition of the present invention. As the crosslinking agent, an organic peroxide or a photopolymerization initiator is preferably used. Especially, since the sheet | seat for laminated body formation with which the adhesive force, transparency, 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, from the viewpoint of resin processing temperature and storage stability, for example, benzoyl peroxide curing agent, tert-hexyl peroxypivalate, tert-butyl peroxypivalate, 3, 5, 5- Trimethylhexanoyl peroxide, di-n-octanoyl peroxide, lauroyl peroxide, stearoyl peroxide, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, succinic acid peroxide, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane, 2,5-dimethyl-2,5-di (2-ethylhexanoylperoxy) hexane, 1-cyclohexyl-1-methylethyl Peroxy-2-ethylhexanoate, tert-hexyl par Xyl-2-ethylhexanoate, 4-methylbenzoyl peroxide, tert-butylperoxy-2-ethylhexanoate, m-toluoyl + benzoyl peroxide, benzoyl peroxide, 1,1-bis (tert-butyl Peroxy) -2-methylcyclohexane, 1,1-bis (tert-hexylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis (tert-hexylperoxy) cyclohexane, 1,1-bis (Tert-Butylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis (tert-butylperoxy) cyclohexane, 2,2-bis (4,4-di-tert-butylperoxycyclohexyl) Propane, 1,1-bis (tert-butylperoxy) Clododecane, tert-hexylperoxyisopropyl monocarbonate, tert-butylperoxymaleic acid, tert-butylperoxy-3,3,5-trimethylhexane, tert-butylperoxylaurate, 2,5-dimethyl-2 , 5-di (methylbenzoylperoxy) hexane, tert-butylperoxyisopropyl monocarbonate, tert-butylperoxy-2-ethylhexyl monocarbonate, tert-hexylperoxybenzoate, 2,5-di-methyl-2, 5-di (benzoylperoxy) hexane and the like.

  As organic peroxides, in particular 2,5-dimethyl-2,5 di (tert-butylperoxy) hexane, 1,1-bis (tert-hexylperoxy) -3,3,5-trimethylcyclohexane, tert -Butylperoxy-2-ethylhexyl monocarbonate is preferred. Thereby, a laminate-forming sheet having excellent insulating properties can be obtained. Such a sheet is effective when used as a solar cell sealing film.

  Although there is no restriction | limiting in particular in content of the said organic peroxide, Preferably it is 0.1-5 mass parts with respect to 100 mass parts of mixtures of EVA and PSs, More preferably, it is 0.2-3 mass parts Is preferred.

  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, Methylphenylglyoxylate can be used. Preferably, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- (4- (methylthio) phenyl) -2-morpholinopropane-1, benzophenone Etc. 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.

  It is preferable that content of the said photoinitiator is 0.5-5.0 mass parts with respect to 100 mass parts of mixtures of EVA and PSs.

[Crosslinking aid]
The crosslinking aid can improve the gel fraction of EVA and improve the adhesion and durability of the laminate-forming sheet obtained using the composition of the present invention.

  The content of the crosslinking aid is generally 10 parts by mass or less, preferably 0.1 to 5 parts by mass, more preferably 0.1 to 2.5 parts by mass with respect to 100 parts by mass of the mixture of EVA and PSs. used. 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]
As the adhesion improver, a silane coupling agent can be used. Thereby, the adhesive force of the obtained sheet | seat for laminated body formation can be improved further. 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 0.7 parts by mass, more preferably 0.3 to 0.65 parts by mass with respect to 100 parts by mass of the mixture of EVA and PSs.

[Others]
Examples of plasticizers include phosphites such as trisisodecyl phosphite and trisnonylphenyl phosphite and phosphorus-containing compounds such as phosphate esters, adipic acid ether esters, trimellitate n-octyl, dioctyl phthalate, dihexyl adipate, sebacic acid Esters of polybasic acids such as dibutyl, 2,2,4-trimethyl-1,3-pentanediol disobutyrate, triethylene glycol-di-2-ethylbutyrate, tetraethylene glycol diheptanoate, triethylene glycol Polyesters such as dipelargonate, epoxidized fatty acid alkyl esters and the like can be used.

  Moreover, you may use the other additive of said material for the composition in this invention by the use of the sheet | seat for laminated body obtained. 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, various additives such as an acryloxy group-containing compound, a methacryloxy group-containing compound, an epoxy group-containing compound, an ultraviolet absorber, a light stabilizer, and / or an anti-aging agent may be added as necessary for adjustment. .

[Manufacturing Method of Composition for Manufacturing Sheet for Forming Laminate]
The manufacturing method of the composition for manufacturing a laminate-forming sheet of the present invention is not particularly limited as long as the above-described sea-island structure is formed. In particular, in the case of a composition having a high blending ratio of PSs, it is difficult to form a sea-island structure. That is, EVA and PSs are more preferably under conditions where the viscosity V _PSs [Pa · s] of _PSs is 0.1 to 20 times the viscosity V _EVA [Pa · s] of _EVA . It is preferable to include a kneading step of kneading under the conditions of ˜18.0 times, more preferably 4.0 to 18.0 times, particularly preferably 6.0 to 18.0 times. A kneading step is preferably performed at a speed of 10 to 1500 s ⁻¹ , more preferably 100 to 1000 s ⁻¹ , particularly preferably 200 to 800 s ⁻¹ .

  The temperature condition of the kneading step can be appropriately adjusted depending on the type of EVA and PSs. When the composition contains a crosslinking agent, the temperature is preferably such that the crosslinking agent does not react or hardly reacts. When kneading at a high temperature to adjust the viscosity of EVA and PSs, it is preferable to carry out in a short time so that the crosslinking agent does not react, or to separate the resin kneading step and the compounding agent kneading step such as the crosslinking agent. For example, when using a twin-screw kneader, knead the resin at a high temperature such as 230 ° C in the first half of the twin-screw kneader, lower the temperature to 120 ° C or the like in the second half, and add the compounding agent by side feed And can be kneaded. The temperature condition is preferably 100 to 230 ° C, more preferably 120 to 180 ° C.

  The kneading step may be performed with any apparatus. For example, EVA and PSs and, if necessary, each of the above materials are introduced into a super mixer (high-speed fluid mixer), a twin-screw kneader, a planetary gear kneader, a single-screw extruder, etc. Knead under.

  The composition of the present invention is usually produced as an intermediate in the production process of the laminate-forming sheet, and then used in a film-forming process (including secondary kneading as necessary) The manufacturing process of the composition of the present invention and the subsequent film-forming process do not need to be temporally and spatially continuous processes. From the viewpoint of energy cost and quality, it is preferable that the composition of the present invention is produced and continuously used in the film forming process.

[Laminated body forming sheet]
The laminate forming sheet of the present invention is obtained by forming the laminate forming sheet manufacturing composition of the present invention into a sheet. The laminate-forming sheet of the present invention is formed by subjecting the composition of the present invention to secondary extrusion such as roll kneading, if necessary, and then by ordinary extrusion molding or calendar molding (calendering). It can be manufactured by a method for obtaining a sheet-like material. The heating temperature during film formation is preferably a temperature at which the crosslinking agent does not react or hardly reacts, particularly when a crosslinking agent is blended. For example, it is preferably 50 to 90 ° C, particularly 40 to 80 ° C. The thickness of the laminate forming sheet is not particularly limited and can be appropriately set depending on the application. Generally, it is in the range of 50 μm to 2 mm.

[Usage]
Since the laminate-forming sheet of the present invention is manufactured using the composition of the present invention, by including PSs, heat resistance and the like are imparted and obtained under the same conditions as the EVA composition, This is a high-quality and low-cost sheet for forming a laminate. Moreover, since it can be used similarly to the sheet | seat formed from the EVA composition, it can be preferably used as an intermediate film for laminated glasses, or a sealing film for solar cells.

When used as an intermediate film for laminated glass, the laminated glass is usually produced by interposing the sheet for forming a laminate (intermediate film) of the present invention between two transparent substrates and joining them together. For example, as shown in FIG. 2, the laminated glass is produced by sandwiching the intermediate film 12 between the two transparent substrates 11A and 11B, degassing the obtained laminate, and then heating. A pressing method or the like is used. These processes are performed using, for example, a vacuum bag method, a nip roll method, or the like. Thereby, the intermediate film 12 is cured, and the intermediate film 12 and the transparent substrates 11A and 11B can be bonded and integrated. As production conditions, for example, the laminate is preliminarily pressure-bonded at a temperature of 80 to 120 ° C., and EVA is crosslinked by heat treatment at 100 to 150 ° C. (particularly around 130 ° C.) for 10 minutes to 1 hour. Further, the heat treatment may be performed under pressure. At this time, it is preferable to carry out while pressing the laminate at a pressure of 1.0 × 10 ³ Pa to 5.0 × 10 ⁷ Pa. Cooling after crosslinking is generally performed at room temperature, and in particular, the faster the cooling, the better.

  As the transparent substrate, for example, a plastic film may be used in addition to a glass plate such as a silicate glass, an inorganic glass plate, and a non-colored transparent glass plate. Examples of the plastic film include a polyethylene terephthalate (PET) film, a polyethylene aphthalate (PEN) film, and a polyethylene butyrate film, and a PET film is preferred. The thickness of the transparent substrate is generally about 0.05 to 20 mm.

  Moreover, when using for the sealing film for solar cells, normally, the laminated body formation sheet | seat (sealing film) of this invention is interposed between the surface side transparent protection member and the back surface side protection member, and it is bridge-integrated. By making it into a solar cell, the solar cell is sealed. In order to sufficiently seal the solar cell, the front side transparent protective member, the front side sealing film, the solar cell, the back side sealing film and the back side protective member are laminated in that order, After pre-pressing under reduced pressure and degassing the air remaining in each layer, the sealing film may be crosslinked and cured by heating and pressurization. In addition, in this invention, the side (light-receiving surface side) where the light of the solar cell is irradiated is referred to as “front surface side”, and the surface opposite to the light-receiving surface of the solar cell is referred to as “back surface side”.

For example, as shown in FIG. 3, the solar cell is manufactured by laminating the front surface side transparent protective member 21, the front surface side sealing film 23 </ b> A, the solar cell 24, the back surface side sealing film 23 </ b> B, and the back surface side protective member 22. The sealing films 23A and 23B may be cross-linked and cured according to a conventional method such as heat and pressure. In order to heat and pressurize, for example, the laminate is heated with a vacuum laminator at a temperature of 135 to 180 ° C., further 140 to 180 ° C., particularly 155 to 180 ° C., a degassing time of 0.1 to 5 minutes, and a press pressure of 0.1. What is necessary is just to heat-press in about 1.5 kg / cm < ² > and press time 5-15 minutes. At the time of heating and pressing, the EVA contained in the front surface side sealing film 23A and the rear surface side sealing film 23B is cross-linked, whereby the front surface side transparent film is protected via the front surface side sealing film 23A and the back surface side sealing film 23B. The member 21, the back surface side protection member 22, and the solar cell 24 can be integrated to seal the solar cell 24.

  The laminate forming sheet (sealing film) of the present invention is not limited to a solar battery using a single crystal or polycrystalline silicon crystal solar battery cell as shown in FIG. It can also be used for sealing films of thin film solar cells such as thin film amorphous silicon solar cells and copper indium selenide (CIS) solar cells. In this case, for example, the back side sealing is performed on the thin film solar cell element layer formed by chemical vapor deposition on the surface of the front side transparent protective member such as a glass substrate, a polyimide substrate, or a fluororesin transparent substrate. A structure in which a film and a back surface side protective member are laminated and bonded and integrated, a surface side sealing film and a surface side transparent protective member are laminated and bonded on a solar cell element formed on the surface of the back surface side protective member An integrated structure, or a structure in which a surface-side transparent protective member, a surface-side sealing film, a thin-film solar cell element, a back-side sealing film, and a back-side protective member are laminated in this order and bonded and integrated. Can be mentioned.

  The surface-side transparent protective member 21 used in the present invention is usually a glass substrate such as silicate glass. As for the thickness of a glass substrate, 0.1-10 mm is common, and 0.3-5 mm is preferable. The glass substrate may generally be chemically or thermally strengthened.

  The back side protection member 22 used in the present invention is preferably a plastic film such as polyethylene terephthalate (PET). Further, a film obtained by laminating a fluorinated polyethylene film, particularly a fluorinated polyethylene film / Al / fluorinated polyethylene film in this order in consideration of heat resistance and wet heat resistance may be used.

  Hereinafter, the present invention will be described with reference to examples.

(Examples 1-8, Comparative Examples 1-4)
EVA and PS having physical properties shown in Table 1 were kneaded with each blending amount and kneading conditions to prepare an EVA and PS mixed composition. The viscosity of and PS on the viscosity of the EVA in the composition (PS Viscosity / EVA viscosity) is used Capirograph (manufactured by Toyo Seiki Co.), the viscosity of the shear rate 18s ^-1, the resin at 200 ° C. temperature of the kneading temperature Was measured and calculated.

For each of the obtained resin compositions, the viscosity was measured using a capillograph (manufactured by Toyo Seiki Co., Ltd.) with the temperature raised at a shear rate of 18 s ⁻¹ . The width of the temperature range in which the viscosity of the composition was 20000 to 50000 Pa · s was defined as the workable temperature range, and the temperature at which the viscosity was 30000 Pa · s was determined as the central workable temperature.

  As a pass / fail judgment, the processable temperature range is ○ when the temperature is 5 ° C. or higher, and × when the temperature is less than 5 ° C., and the center processable temperature is ○ when the temperature is 70 ° C. or higher and 95 ° C. or lower, higher than 95 ° C. and 100 ° C. In the following cases, Δ, and in the case of higher than 100 ° C., ×.

  Further, for each composition, a cross-section is obtained using a microtome (manufactured by Leica), and the cross-section is subjected to elastic modulus mapping with an AFM (Atomic Force Microscope) (manufactured by Toyo Technica Co., Ltd.), and the sea-island structure of EVA and PS Was observed. When EVA is the sea phase (continuous phase) and PS is the island phase, ◯, when EVA and PS are both in continuous phase, Δ, PS becomes the continuous phase and EVA becomes the island phase When it is, it was set as x.

In addition, binarized image processing (calculated by excluding the island phase having a major axis of 1.2 μm or less from the viewpoint of resolution is determined as noise) is performed for those in which PS island phases are recognized. 2500 [mu] m 2 in the case of atomic force microscopy) ^image, in the case of an optical microscope image were measured major axis and the minor axis of the island phase existing in 4900Myuemu ^2, the average diameter of the average value ((average major axis (l) + mean The minor axis (d)) / 2) and the average aspect ratio (average major axis (l) / average minor axis (d)) were determined.

(Evaluation results)
The evaluation results are shown in Table 1.

  As shown in Table 1, the compositions of Examples 1 to 8 having a sea-island structure in which EVA is the sea phase and PS is the island phase have a workable temperature range of 5 ° C. or more and a central workable temperature. The composition was found to be a composition having a temperature of 95 ° C. or lower and excellent processing characteristics such as film forming properties during sheet production. The average diameter of the PS island phase in these examples was 40 μm or less, and the average aspect ratio was 40 or less. In Comparative Examples 1 and 2, the above-mentioned sea-island structure was observed, but the average aspect ratio of the PS island phase of Comparative Example 1 was larger than 40, and the average diameter of the PS island phase of Comparative Example 2 was larger than 40 μm.

  In the case of such a composition, the center processable temperature greatly exceeded 100 ° C., and the composition was difficult to process. This is thought to be due to the fact that the average diameter of the island phase is too large or the average aspect ratio is too large, indicating a property close to a co-continuous structure.

  Moreover, the composition which does not have a sea-island structure where PS is an island phase as in Comparative Examples 3 and 4 also had a very high center processable temperature and was difficult to process.

  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 laminated glass with high transparency and a solar cell with high power generation efficiency can be easily provided.

11A, 11B Transparent substrate 12 Intermediate film 21 Front side transparent protective member 22 Back side protective member 23A Front side sealing film 23B Back side sealing film 24 Solar cell

Claims (12)

A composition for producing a laminate-forming sheet comprising an ethylene-vinyl acetate copolymer and a polystyrene resin,
The ethylene-vinyl acetate copolymer has a sea-island structure where the sea phase is the sea phase and the polystyrene resin is the island phase,
The average diameter ((average major axis (l) + average minor axis (d)) / 2) of the island phase made of the polystyrene-based resin is 40 μm or less,
An average aspect ratio (average major axis (l) / average minor axis (d)) of an island phase made of the polystyrene resin is 40 or less.   The composition according to claim 1, wherein a mass ratio (EVA: PSs) of the ethylene-vinyl acetate copolymer (EVA) and the polystyrene resin (PSs) is in a range of 65:35 to 45:55. The sea-island structure is such that the ethylene-vinyl acetate copolymer (EVA) and the polystyrene resin (PSs) have a viscosity V _PSs [Pa · s] of _{PSs with} respect to a viscosity V _EVA [Pa · s] of _EVA . The composition of Claim 1 or 2 obtained by knead | mixing on the conditions used as 0.1-20.0 times. The composition according to any one of claims 1 to 3, wherein the sea-island structure is obtained by kneading the ethylene-vinyl acetate copolymer and the polystyrene resin under conditions of a shear rate of 10 to 1500 s- ¹ . .   The temperature at which the viscosity of the composition is 30000 Pa · s is 70 to 100 ° C, and the width of the temperature range in which the viscosity of the composition is 20000 to 50000 Pa · s is 5.0 ° C or more. The composition of any one of these.   The composition according to any one of claims 1 to 4, wherein the ethylene-vinyl acetate copolymer has a melt flow rate defined by JIS K7210 of 1.0 to 50.0 g / 10 min.   The composition according to any one of claims 1 to 6, wherein the ethylene-vinyl acetate copolymer has a vinyl acetate content of 20 to 40% by mass. It is a manufacturing method of the composition for sheet | seat manufacture for laminated bodies of any one of Claims 1-7,
The ethylene-vinyl acetate copolymer (EVA) and the polystyrene resin (PSs) have a viscosity V _PSs [Pa · s] of PSs of _0.1 to 20.0 with respect to the viscosity V _EVA [Pa · s] of _EVA . A production method comprising a kneading step of kneading under doubled conditions. The manufacturing method according to claim 8, wherein the kneading step is a step of kneading under conditions of a shear rate of 10 to 1500 s ⁻¹ .   The manufacturing method according to claim 8 or 9, wherein the kneading step is a step of kneading under a temperature condition of 100 to 200 ° C.   A sheet for forming a laminate, wherein the composition according to any one of claims 1 to 7 is formed into a sheet.   The sheet for forming a laminate according to claim 11, which is an interlayer film for laminated glass or a sealing film for solar cell.

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