KR101228703B1 - Preparation method for excellent weather stable EVA sheet for solar cell encapsulant - Google Patents

Abstract

The present invention relates to a method for producing an ethylene vinyl acetate copolymer sheet for solar cell encapsulation material having improved weather resistance, and more particularly, a specific light stabilizer, a specific ultraviolet absorber, a crosslinking agent, a crosslinking aid, and an ethylene vinyl acetate copolymer resin. The manufacturing method of the EVA sheet | seat for solar cell sealing materials characterized by mixing a silane coupling agent and forming a sheet | seat.

Description

Preparation method of EAB sheet for solar cell encapsulant with excellent weatherability {{Preparation method for excellent weather stable EVA sheet for solar cell encapsulant}

The present invention relates to a method for producing an EVA sheet for solar cell encapsulation material having excellent weather stability, and more specifically, to a ethylene vinyl acetate copolymer (hereinafter referred to as "EVA") resin, a specific light stabilizer, a specific ultraviolet absorber, A crosslinking agent, a crosslinking aid and a silane coupling agent are mixed to form a sheet, and a method for manufacturing a EVA sheet for solar cell encapsulant.

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, since EVA sheet for solar cell encapsulation material requires high transparency, adhesiveness and weather resistance after crosslinking, various additives such as crosslinking agent, crosslinking aid, silane coupling agent, antioxidant, light stabilizer and ultraviolet absorber 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, light stabilizers and ultraviolet absorbers used in EVA sheets used for most solar cell encapsulation materials now exhibit excellent properties of inhibiting photo-oxidation reactions in the case of low molecular weight, but volatilization and There is a problem that the light stability properties are degraded as the sheet surface is transferred, and self-decomposition occurs due to high temperature during lamination and crosslinking, or side reactions with other additives are likely to occur. This may cause discoloration of EVA sheet and degradation of properties.

An object of the present invention is to provide a method for producing an EVA sheet for solar cell encapsulation material having excellent yellowing stability and weathering stability.

The manufacturing method of EVA sheet for solar cell sealing material which concerns on this invention is characterized by shape | molding a sheet by mixing a specific light stabilizer, a specific ultraviolet absorber, a crosslinking agent, a crosslinking adjuvant, and a silane coupling agent to EVA resin.

In one embodiment, the manufacturing method of the EVA sheet for solar cell encapsulation material of the present invention, by mixing the light stabilizer, ultraviolet absorber, crosslinking agent, crosslinking aid and silane coupling agent together with the EVA resin by melt kneading at the decomposition temperature of the crosslinking agent below Molding the sheet.

In another embodiment, the manufacturing method of the EVA sheet for solar cell encapsulation material of the present invention, the crosslinking agent while melting the EVA resin composition obtained by uniformly mixing the light stabilizer and the ultraviolet absorber in the EVA resin below the decomposition temperature of the crosslinking agent in the extruder, And supplying the mixture of the crosslinking aid and the silane coupling agent to the extruder through a separate raw material supply device to melt kneading and forming a sheet.

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 the manufacturing method of the EVA sheet for solar cell encapsulation according to the present invention, the EVA resin is a vinyl acetate (VA) content of 25 to 32% by weight, the melt index (190 ℃, measured by a load of 2.16kg) of 6 ~ It is preferable that the content of the vinyl acetate is in the range of 30 g / 10 minutes, but the transparency, flexibility and blocking resistance are not preferable when the content of the vinyl acetate is outside the above range, and the sheet formability and the mechanical properties are poor when the melt index is outside the above range. Apart is not desirable.

The light stabilizer used in the present invention may be, for example, those having an acryl or methacryl group including a HALS group (piperidine group), and specific examples thereof include 2,2,6,6-tetramethyl-4. -Piperidyl acrylate, 2,2,6,6-tetramethyl-4-piperidyl methacrylate, 1,2,2,6,6-pentamethyl-4-piperidyl acrylate, 1, One or more types selected from the group consisting of 2,2,6,6-pentamethyl-4-piperidyl methacrylate and the like can be used.

In the manufacturing method of the EVA sheet for solar cell encapsulation material according to the present invention, it is preferable to use 0.01 to 0.5 parts by weight of the light stabilizer with respect to 100 parts by weight of the EVA resin, when the content of the light stabilizer is less than 0.01 parts by weight It is not preferable because the light stability effect is insignificant.

The ultraviolet absorber used for this invention can use 1 or more types of monomers which have a methacryl, an acryl, or an allyl group as a benzophenone system, a benzotriazole system, or a benzotriazine system, for example. As a specific example of the said benzophenone type ultraviolet absorber monomer, 4-methacryloxy-2-hydroxybenzophenone (4-methacryloxy-2-hydroxybenzophenone), 4-allyloxy-2-hydroxybenzophenone ( 4-allyloxy-2-hydroxybenzophenone), 1,3-bis- (4-benzoyl-3-hydroxyphenoxy) -prop-2-yl-acrylate (1,3-bis- (4-benzoyl-3 -hydroxyphenoxy) -prop-2-yl-acrylate), 1,3-bis- (4-benzoyl-3-hydroxyphenoxy) -prop-2-yl-methacrylate (1,3-bis- ( 4-benzoyl-3-hydroxyphenoxy) -prop-2-yl-methacrylate), 1,3-bis- (4-benzoyl-3-hydroxyphenoxy) prop-2-yl-3,3-dimethacryl Rate (1,3-bis- (4-benzoyl-3-hydroxyphenoxy) -prop-2-yl-3,3-dimethacrylate), 4-benzoyl-3-hydroxyphenylacrylate (4-benzoyl-3-hydroxyphenylacrylate ), 2- (4-benzoyl-3-hydroxyphenoxy) ethyl acrylate (2- (4-benzoyl-3-hydroxyphenoxy) ethylacrylate), and the like, and specific examples of the benzotriazole-based ultraviolet absorber monomers 2 [2-he Hydroxy-4-alkoxy- (2-oxypropyl-α-methylacrylate) -phenyl] 2H-benzotriazole (2 [2-hydroxy-4-alkoxy- (2-oxypropyl-α-methylacrylate) -phenyl] 2H-benzotriazole), 2 [2-hydroxy-4-alkoxy- (2-oxypropyl-α-methylacrylate) -phenyl] 2H-4-methoxybenzotriazole (2 [2-hydroxy-4-alkoxy -(2-oxypropyl-α-methylacrylate) -phenyl] 2H-4-methoxybenzotriazole), 2- (2H-benzotriazol-2-yl) -4-methyl-6- (2-propenyl) phenol (2- (2H-benzotriazol-2-yl) -4-methyl-6- (2-propenyl) phenol), 2- [3- (2H-benzotriazol-2-yl) -4-hydroxyphenyl] ethylmethacryl Rate (2- [3- (2H-benzotriazol-2-yl) -4-hydroxyphenyl] ethylmethacrylate), 2- (2H-benzotriazol-2-yl) -4-methyl-6- (2-propenyl) Phenol (2- (2H-benzotriazol-2-yl) -4-methyl-6- (2-propenyl) phenol), and the like, and specific examples of the benzotriazine-based ultraviolet absorber monomer are 3- [4- { 4,6-bis (2,4-dimethylphenyl) -1,3,5-triazin-2-yl} -3-hydroxyphenoxy] -2-hydroxypropyl methacrylate (3- [4- {4,6-bis (2,4-dimethylphenyl) -1,3,5-triazine-2-yl} -3-hydroxyphenoxy] -2-hydroxypropyl methacrylate).

In the manufacturing method of the EVA sheet for solar cell encapsulant according to the present invention, it is preferable to use 0.01 to 0.5 parts by weight of the ultraviolet absorber with respect to 100 parts by weight of the EVA resin, when the content of the ultraviolet absorber is less than 0.01 parts by weight. In the case of less than 0.5 parts by weight, it is not preferable because the ultraviolet absorption effect is insignificant.

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 specific light stabilizer and a specific ultraviolet absorber in place of the conventional light stabilizer and the ultraviolet absorber, it is transferred to the surface of the sheet by the change with time, or the yellowing stability as well as the weather without difficulty of processing such as melting and dispersion. The effect which stability improves can be aimed at.

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

According to the composition of Table 1, Adeka's LA-82 (1,2) was used as a light stabilizer based on 100 parts by weight of EVA resin (28% by weight of vinyl acetate, 15 g / 10 min of melt index, Samsung Total E280PV) containing no additives. , 2,6,6-pentamethyl-4-piperidyl methacrylate) 0.1 part by weight, 0.3 parts by weight of 4-allyloxy-2-hydroxybenzophenone from Sigmas Aldrich as a UV absorber monomer, and a crosslinking agent 0.7 parts by weight of Luperox TBEC (t-butyl-2-ethylhexyl monoperoxycarbonate), 0.5 parts by weight of TAICROS (triallyl isocyanurate) manufactured by Evonik as a crosslinking aid, and OFS 6030 (manufactured by Dow Corning as a silane coupling agent) 0.5 parts by weight of 3-methacryloxypropyltrimethoxysiloxane) was mixed, and the sheet was 0.45 mm thick with an extruder temperature of 90 ° C. and a T-die temperature of 100 ° C. and a linear velocity of the sheet of 6.5 m / min. Prepared.

Example 2

As in Example 1, except that 0.3 parts by weight of 2- (2H-benzotriazol-2-yl) -4-methyl-6- (2-propenyl) phenol from Sigma Aldrich was added as the ultraviolet absorber monomer. The sheet was produced by the method.

Example 3

3- [4- {4,6-bis (2,4-dimethylphenyl) -1,3,5-triazin-2-yl} -3-hydroxyphenoxy] -2-hydroxy as ultraviolet absorber monomer A sheet was manufactured in the same manner as in Example 1, except that 0.3 part by weight of propyl methacrylate was added.

Comparative Example 1

0.1 parts by weight of BASF's Tinuvin770 (bis (2,2,6,6, -tetramethyl-4-piperidyl) sebacate) was added as a light stabilizer, and BASF's Chimassorb 81 (2-hydroxy-4) was added as an ultraviolet absorber. -Octyloxy-benzophenone) A sheet was prepared in the same manner as in Example 1, except that 0.3 part by weight of the compound was added.

Example 4

On top of the low iron tempered glass (200mm × 200mm) 1 EVA sheet (200mm × 160mm) obtained in Example 1 was placed thereon, DNP's backsheet (200mm × 200mm) was placed thereon, and vacuum step was performed at 150 ° C. for 6 minutes. 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) for weather stability test, tensile strength difference, elongation The difference and yellowness difference (ΔYI) were 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

* 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 In addition to the stability it can be seen that the weather stability is further improved.

Claims (9)

From benzophenone-based, benzotriazole-based or benzotriazine-based compounds containing at least one light stabilizer selected from piperidine-based compounds containing acryl or methacryl groups, methacryl, acryl or allyl groups in ethylene vinyl acetate copolymer resin A method for producing an ethylene vinyl acetate copolymer sheet for a solar cell encapsulating material comprising forming a sheet by mixing an organic peroxide, a crosslinking aid and a silane coupling agent as one or more selected ultraviolet absorbers and crosslinking agents. The method of claim 1, wherein the ethylene vinyl acetate copolymer resin is mixed with the light stabilizer, the ultraviolet absorbent, the organic peroxide, the crosslinking aid, and the silane coupling agent together to melt-knead the organic peroxide at a decomposition temperature below to form a sheet. A method for producing an ethylene vinyl acetate copolymer sheet for solar cell encapsulant. The organic peroxide, crosslinking aid, and the ethylene vinyl acetate copolymer resin composition of claim 1, wherein the ethylene vinyl acetate copolymer resin composition obtained by mixing the light stabilizer and the ultraviolet absorber with the ethylene vinyl acetate copolymer resin is melted at or below the decomposition temperature of the organic peroxide in an extruder. A method of producing an ethylene vinyl acetate copolymer sheet for solar cell encapsulation, characterized in that to form a sheet by supplying a mixture of silane coupling agent to the extruder through a separate raw material supply device to melt kneading. The ethylene vinyl acetate copolymer sheet for solar cell encapsulating materials according to any one of claims 1 to 3, wherein the light stabilizer is used in an amount of 0.01 to 0.5 parts by weight based on 100 parts by weight of the ethylene vinyl acetate copolymer resin. Manufacturing method. The ethylene vinyl acetate copolymer sheet for solar cell encapsulating materials according to any one of claims 1 to 3, wherein 0.01 to 0.5 parts by weight of the ultraviolet absorber is used with respect to 100 parts by weight of the ethylene vinyl acetate copolymer resin. Manufacturing method. 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. delete delete 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.