KR101161996B1 - Prepatation method for excellent photostable eva sheet for solar cell encapsulant - Google Patents

Abstract

PURPOSE: A manufacturing method of an EVA sheet for a solar cell encapsulating material with a superior light stability is provided to improve weatherability by adding a monomer having a functional group capable of simultaneously having an absorption function and a stabilization function of ultraviolet rays. CONSTITUTION: A sheet is formed by mixing a monomer, organic peroxides, a bridging making agent, and a silane coupling agent. The monomer has a functional group which simultaneously performs an absorption function and a stabilization function of ultraviolet rays on an ethylene vinyl acetate copolymer resin. The monomer has a benzophenone, a benzotriazole or a benzoben triazine structure. The content of vinyl acetate in an ethylene vinyl acetate copolymer resin is 25 weight%-32 weight%. A melt index of the ethylene vinyl acetate copolymer resin is 6-30g/10 minutes.

Description

Manufacturing method of EVA sheet for solar cell encapsulant with excellent light stability {Prepatation method for excellent photostable EVA sheet for solar cell encapsulant}

The present invention relates to a method for manufacturing an EVA sheet for solar cell encapsulation material having excellent light stability, and more specifically, simultaneously expresses an ultraviolet absorbing function and a light stabilizing function in an ethylene vinyl acetate copolymer (hereinafter referred to as EVA) resin. The present invention relates to a method for producing an EVA sheet for solar cell encapsulant, comprising forming a sheet by mixing a polymerizable monomer having a functional group, a crosslinking agent, a crosslinking aid and a silane coupling agent.

The solar cell module used in solar power generation is usually EVA sheet is used on both sides to protect the cell, additionally, transparent glass substrate on the side where solar light is incident, and lamination on the other side of sheet with excellent water vapor barrier and weather resistance. It is. The laminating method is to laminate a transparent glass substrate, an EVA sheet, a cell, an EVA sheet, a gas barrier sheet, and then heat and crosslink the adhesive under a specific temperature and pressure.

Generally, EVA sheet for solar cell encapsulant requires high transparency, adhesiveness, and weather resistance after crosslinking. Therefore, various additives such as crosslinking agent, crosslinking aid, silane coupling agent, antioxidant, UV stabilizer, ultraviolet absorber, etc. are added to EVA. The EVA sheet for sealing material is manufactured by melt-kneading at the temperature more than the melting temperature of EVA and below the decomposition temperature of the organic peroxide which is a crosslinking agent.

However, UV absorbers used in EVA sheets used for most solar cell encapsulation materials now exhibit excellent properties of inhibiting photo-oxidation reactions at low molecular weights. As it blooms, there is a problem of deteriorating light stability, deterioration of adhesion to cells, cover glass, and back sheet, and self-degradation due to high temperature during lamination and crosslinking, or side reaction with other additives. . This may cause discoloration of EVA sheet and degradation of properties.

It is an object of the present invention to provide a method for producing an EVA sheet for solar cell encapsulation, in which yellowing stability and light stabilization effect can be maintained for a long time.

EVA sheet for solar cell encapsulation according to the present invention is to form a sheet by mixing a polymerizable monomer, a crosslinking agent, a crosslinking aid and a silane coupling agent having a functional group that simultaneously expresses the ultraviolet absorption function and the light stabilization function in EVA resin. It features.

In one embodiment, the manufacturing method of the EVA sheet for solar cell encapsulation material of the present invention, a polymerizable monomer, a crosslinking agent, a crosslinking aid and a silane coupling agent having a functional group which simultaneously expresses UV absorbing function and light stabilizing function in EVA resin. Mixing together to melt kneaded at the decomposition temperature of the crosslinker below to form a sheet.

In another embodiment, the method for producing the EVA sheet for solar cell encapsulation material of the present invention, EVA resin composition obtained by uniformly mixing a polymerizable monomer having a functional group that simultaneously expresses the ultraviolet absorbing function and light stabilizing function in the EVA resin And melting and kneading the mixture of the crosslinking agent, the crosslinking aid and the silane coupling agent to the extruder through a separate raw material supply device while melting the mixture at a temperature below the decomposition temperature of the crosslinking agent in the extruder.

In the case of melt-kneading at a temperature higher than the decomposition temperature of the crosslinking agent during sheet forming, sheet formability is bad or cross-linking occurs, which is not preferable.

In manufacturing the EVA sheet for solar cell encapsulation according to the present invention, the EVA resin has a vinyl acetate (VA) content of 25 to 32% by weight, and a melt index (190 ° C., measured under a load of 2.16 kg) of 6 to 30 g / 10 minutes is preferable, but when the content of vinyl acetate is out of the above range, transparency, flexibility, and blocking resistance are not preferable, and when the melt index is out of the above range, sheet formability and mechanical properties are not preferable, which is not preferable. .

The polymerizable monomer having a functional group that simultaneously expresses the ultraviolet absorbing function and the ultraviolet stabilizing function used in the present invention has a benzophenone, benzotriazole, or bentriazine structure as the ultraviolet absorbing function and is hindered by the ultraviolet stabilizing function. One or more types selected from the group consisting of monomers having an amine structure can be used, and the type thereof is not particularly limited. As a specific example of the polymerizable monomer which has a functional group which expresses the said ultraviolet absorption function and an ultraviolet stabilization function simultaneously, it is following General formula (1)

일반식(1)

In general formula (1)

Wherein M has a structure of the following (1 ') or (1 "),

R ₁ and R ₂ represent a hydrogen atom or a straight alkyl or alkoxy group having 1 to 18 carbon atoms, and R represents a hydrogen atom or a methyl group.

The polymerizable monomer having a functional group which simultaneously expresses another ultraviolet absorbing function and ultraviolet stabilizing function used in the present invention is represented by the following general formula (2)

일반식(2)

General formula (2)

(Wherein M has a structure of (1 ′) or (1 ″), and R ₁ , R ₂ , R ₃ and R ₄ are hydrogen atoms, or hydroxy groups, or straight chain alkyl groups having 1 to 18 carbon atoms or alkoxy Group, and R represents a hydrogen atom or a methyl group).

The polymerizable monomer having a functional group which simultaneously expresses another ultraviolet absorbing function and ultraviolet stabilizing function used in the present invention is represented by the following general formula (3)

일반식(3)

General formula (3)

(Wherein M has a structure of (1 ′) or (1 ″), R ₁ , R ₂ and R ₃ represent a hydrogen atom or a hydroxy group or a straight alkyl or alkoxy group having 1 to 18 carbon atoms, R may represent a hydrogen atom or a methyl group).

In the method for producing an EVA sheet for solar cell encapsulation according to the present invention, the polymerizable monomer having a functional group that simultaneously expresses the ultraviolet absorbing function and the ultraviolet stabilizing function includes 0.01 to 0.5 parts by weight based on 100 parts by weight of the EVA resin. If the amount is less than 0.01 part by weight, the light stabilization effect is insignificant and undesirable. If the content is more than 0.5 part by weight, discoloration or economical efficiency is not preferred.

Examples of the crosslinking agent used in the present invention include organic peroxides. For example, a dialkyl peroxide crosslinking agent having a half-life temperature (decomposition temperature) of 130 to 160 ° C and an alkyl having a half-life temperature of 100 to 135 ° C. 1 or more types chosen from the group which consists of a peroxy ester-type crosslinking agent or a peroxy ketal can be used, It is also possible to use together 2 or more types from which the half-life temperature differs for 1 hour.

Specific examples of the dialkyl peroxide crosslinking agent are 2,4-dimethyl-2,5-bis (t-butylperoxy) hexane (2,5-dimethyl-2,5-bis (t-butylperoxy) hexane) Specific examples of the alkyl peroxy ester-based crosslinking agent include t-butyl-2-ethylhexyl monoperoxycarbonate and the like, and the peroxy ketal type is 1,1-. Di- (t-butylperoxy) -3,3,5-trimethylcyclohexane (1,1-di- (t-butylperoxy) -3,3,5-trimethylcyclohexane) etc. are mentioned.

It is preferable that the said crosslinking agent contains 0.3-1.5 weight part with respect to 100 weight part of EVA resin, but when it is less than 0.3 weight part, the crosslinking effect is insignificant, and it is unpreferable, and when it exceeds 1.5 weight part, it is unpreferable in economical efficiency.

The type of crosslinking aid used in the present invention is not particularly limited, and for example, a polyallyl compound or a polymethacryloxy compound can be used, and specific examples thereof include triallyl isocyanurate and the like. Can be mentioned.

It is preferable that the said crosslinking adjuvant contains 0.3-1.5 weight part with respect to 100 weight part of EVA resin, but when it is less than 0.3 weight part, the crosslinking effect is insignificant, and when it exceeds 1.5 weight part, it is unpreferable in economical efficiency.

The type of silane coupling agent used in the present invention is not particularly limited, and for example, an organosilicon compound can be used, and specific examples thereof include 3-methacryloxypropyl methoxy silane (3-Methacryloxypropyl trimethoxysilane) and the like. Can be mentioned.

The silane coupling agent preferably contains 0.3 to 1.5 parts by weight with respect to 100 parts by weight of EVA resin, but less than 0.3 parts by weight is not preferred because it does not exhibit an additive effect. not.

In the method for manufacturing a sheet for solar cell encapsulant according to the present invention, in addition to the above components, conventional additives may be further added as needed.

According to the present invention, by adding a polymerizable monomer having a functional group that simultaneously expresses an ultraviolet absorbing function and an ultraviolet stabilizing function, instead of the existing ultraviolet absorbent or ultraviolet stabilizer, the sheet is transferred to the surface of the sheet by aging, melting, dispersing, etc. It is possible to achieve the effect of improving yellowing stability as well as weathering stability without difficulty of processing.

Hereinafter, the present invention will be described in more detail with reference to the following examples, but the scope of the present invention is not limited to these examples.

Example # 1

With respect to 100 parts by weight of EVA resin (28% by weight of vinyl acetate, 15 g / 10 minutes of melt index, Samsung Total E280PV) containing no additives, a polymerizable monomer having a functional group that simultaneously expresses ultraviolet absorbing function and ultraviolet stabilizing function 4- (4- (allyloxy) -6- (1,2,2,6,6-pentamethylpiperidin-4-yloxy) -1,3,5-triazin-2-yloxy) 2-hydroxyphenyl (phenyl) methanone [4- (4- (allyloxy) -6- (1,2,2,6,6-pentamethylpiperidin-4-yloxy) -1,3,5-triazin-2 -yloxy) -2-hydroxyphenyl) (phenyl) methanone] 0.3 parts by weight, 0.7 parts by weight of Luperox TBEC (t-butyl-2-ethylhexyl monoperoxycarbonate) from Alkema as crosslinking agent, TAICROS ( 0.5 parts by weight of triallyl isocyanurate) and 0.5 parts by weight of OFS 6030 (3-methacryloxypropyltrimethoxysiloxane) from Dow Corning Co., Ltd. were mixed with a silane coupling agent, and then the extruder temperature was 90 deg. Is 100 ° C, and the linear velocity of the sheet is divided into A sheet having a thickness of 0.45 mm was prepared at 6.5 meters per square meter.

Example # 2

A polymerizable monomer having a functional group that simultaneously expresses ultraviolet absorbing function and ultraviolet stabilizing function, and is 2- (5- (4- (allyloxy) -6- (2,2,6,6-tetramethylpiperidine-4). -Yloxy) -1,3,5-triazin-2-ylamino) -2H-benzo [d] [1,2,3] triazol-2-yl) phenol [2- (5- (4- (allyloxy) -6- (2,2,6,6-tetramethylpiperidin-4-yloxy) -1,3,5-triazin-2-ylamino) -2H-benzo [d] [1,2,3] triazol- 2-yl) phenol] was prepared in the same manner as in Example 1, except that 0.3 parts by weight of 2-yl) phenol] was added.

Example # 3

A polymerizable monomer having a functional group that simultaneously expresses ultraviolet absorbing function and ultraviolet stabilizing function, and is 2- (4- (allyloxy) -6- (1,2,2,6,6-pentamethylpiperidine-4- Yloxy) -1,3,5-triazin-2-ylamino) -4-methyl-6- (5-methyl-2H-benzo [d] [1,2,3] triazol-2-yl) Phenol [2- (4- (allyloxy) -6- (1,2,2,6,6-pentamethylpiperidin-4-yloxy) -1,3,5-triazin-2-ylamino) -4-methyl-6- A sheet was manufactured in the same manner as in Example 1, except that 0.3 part by weight of (5-methyl-2H-benzo [d] [1,2,3] triazol-2-yl) phenol] was added.

Comparative Example 1

To 100 parts by weight of EVA resin (28% by weight of vinyl acetate, 15g / 10 minutes of melt index, Samsung Total E280PV) containing no additives, BASF Chimassorb 81 (2-hydroxy-4-octyloxy- Benzophenone) 0.3 parts by weight, BASF Tinuvin 770 (bis (2,2,6,6, -tetramethyl-4-piperidyl) sebacate) 0.1 parts by weight, UV stabilizer, Alkema Luperox TBEC (t 0.7 parts by weight of -butyl-2-ethylhexyl monoperoxycarbonate), 0.5 parts by weight of TAICROS (triallyl isocyanurate) from Evonik as a crosslinking aid, and OFS 6030 (3-methacryl) from Dow Corning as a silane coupling agent. Oxypropyltrimethoxysiloxane) 0.5 parts by weight was mixed and then an extruder temperature of 90 deg. C and a T-die temperature were set to 100 deg.

Example 4

Place 1 sheet of EVA sheet (200 mm x 160 mm) obtained in Example 1 on the low iron tempered glass (200 mm x 200 mm), and place the DNP backsheet (200 mm x 200 mm) on it, and vacuum step for 6 minutes at a temperature of 150 ° C. Then, the specimen was prepared by cross-linking by maintaining the difference between the laminator upper pressure and the lower pressure at 100 Mpa for 16 minutes. After observing the internal bubbles and residual conditions of the prepared specimens after the cooling process at room temperature, the crosslinking degree was measured for the crosslinked specimens, and the tensile strength and elongation and colorimeter (Hunter Lab., UltraScan) with Hunter Lab's Ultrascan Prospect. After measuring yellowness (YI) with PRO Colorimeter, and after 1,000 hours in UV irradiation (340nm, 60 ℃) and constant temperature and humidity (85 ℃, 85% relative humidity), the difference in tensile strength, elongation and yellowing (ΔYI) was evaluated.

Example 5

Except for using the sheet prepared in Example 2, the specimen was prepared in the same manner as in Example 4, and observed, measured and evaluated in the same manner.

Example 6

Except for using the sheet prepared in Example 3, the specimen was prepared in the same manner as in Example 4, observed, measured and evaluated in the same manner.

Comparative Example 2

Except for using the sheet prepared in Comparative Example 1, a specimen was prepared in the same manner as in Example 4, observed, measured and evaluated in the same manner.

Table 1 shows the results of evaluating the physical properties of the crosslinked sheets obtained in Examples 4 to 6 and Comparative Example 2.

Example 4 Example 5 Example 6 Comparative Example 2 Weather resistance test time (hr) 0 1000 0 1000 0 1000 0 1000 Degree of crosslinking (%) 88.6 90.5 91 90.0 Light transmittance (%) > 90% > 90% > 90% > 90% Tensile Strength (DH)
(kgf / cm2) 245 230 240 250 250 235 253 211 Tensile strength (UV)
(kgf / cm2) 175 170 174 105 Elongation (DH) (%) 550 550 560 540 530 550 580 550 Elongation (UV) (%) 530 540 520 480 YI (DH) 1.80 5.10 1.77 5.15 1.86 5.4 1.67 6.1 YI (UV) 6.5 6.75 6.35 8.34

* UV = UV irradiation (340nm, 60 ℃)

* DH = constant temperature and humidity (85 ℃, relative humidity 85%)

As shown in the results of Table 1, according to the method according to the present invention, it is possible to manufacture a transparent solar cell encapsulation EVA sheet, when laminating and crosslinking with the sheet produced by the method of the present invention, yellowing It can be seen that the weathering stability is further improved, including stability as well as light stability.

Claims (8)

A polymerizable monomer having a functional group that simultaneously expresses an ultraviolet absorbing function and a light stabilizing function in an ethylene vinyl acetate copolymer resin, and a solar cell encapsulation comprising mixing an organic peroxide, a crosslinking aid and a silane coupling agent as a crosslinking agent to form a sheet. Method for producing ethylene vinyl acetate copolymer sheet for reuse. The decomposition temperature of the organic peroxide according to claim 1, wherein the ethylene vinyl acetate copolymer resin is mixed with a polymerizable monomer, an organic peroxide, a crosslinking aid, and a silane coupling agent together with a functional group that simultaneously expresses UV absorption and light stabilization functions. Method for producing an ethylene vinyl acetate copolymer sheet for solar cell encapsulation material characterized by melting and kneading below. The decomposition temperature of the organic peroxide in the extruder according to claim 1, wherein the ethylene vinyl acetate copolymer resin composition obtained by mixing the ethylene vinyl acetate copolymer resin with a polymerizable monomer having a functional group which simultaneously expresses the ultraviolet absorption function and the light stabilization function is extruded. While melting below, an ethylene vinyl acetate copolymer sheet for solar cell encapsulating material, characterized in that a mixture of an organic peroxide, a crosslinking aid and a silane coupling agent is supplied to the extruder through a separate raw material supply device to melt and kneading to form a sheet. Manufacturing method. The polymerizable monomer according to any one of claims 1 to 3, wherein the polymerizable monomer having a functional group which expresses the ultraviolet absorbing function and the light stabilizing function simultaneously with respect to 100 parts by weight of the ethylene vinyl acetate copolymer resin. A method for producing an ethylene vinyl acetate copolymer sheet for solar cell encapsulant, characterized in that the use of a portion. The vinyl acetate content of the said ethylene vinyl acetate copolymer resin is 25 to 32 weight%, and melt index (190 degreeC, 2.16 kg) is 6-30 g / 10min. A method for producing an ethylene vinyl acetate copolymer sheet for solar cell encapsulant. The polymerizable monomer according to any one of claims 1 to 3, wherein the polymerizable monomer having a functional group that simultaneously expresses the ultraviolet absorbing function and the ultraviolet stabilizing function has a benzophenone, benzotriazole, or benzobentriazine structure. A method for producing an ethylene vinyl acetate copolymer sheet for solar cell encapsulant, characterized in that at least one member selected from the group consisting of monomers having a hindered amine structure. The polymerizable monomer having a functional group that simultaneously expresses the ultraviolet absorbing function and the ultraviolet stabilizing function has a structure represented by the following general formula (1), (2) or (3). Method for producing an ethylene vinyl acetate copolymer sheet for solar cell encapsulant:
In general formula (1)

Wherein M has a structure of the following (1 ') or (1 "),

R ₁ and R ₂ represent a hydrogen atom or a straight alkyl or alkoxy group having 1 to 18 carbon atoms, and R represents a hydrogen atom or a methyl group),
General formula (2)

(Wherein M has the structure of (1 ′) or (1 ″), and R ₁ , R ₂ , R ₃ and R ₄ are hydrogen atoms, hydroxy groups, or straight chain alkyl groups having 1 to 18 carbon atoms or An alkoxy group, R represents a hydrogen atom or a methyl group),
General formula (3)

(Wherein M has a structure of (1 ′) or (1 ″), R ₁ , R ₂ and R ₃ represent a hydrogen atom or a hydroxy group or a straight alkyl or alkoxy group having 1 to 18 carbon atoms, R represents a hydrogen atom or a methyl group). The method for producing an ethylene vinyl acetate copolymer sheet for solar cell encapsulation according to any one of claims 1 to 3, wherein two or more kinds of organic peroxides having different decomposition temperatures are used.