KR20120120620A - Prepatation method for excellent UV irradiation stable EVA sheet for solar cell encapsulant - Google Patents

Abstract

PURPOSE: A manufacturing method of ethylene vinyl acetate copolymer sheet is provided to prevent a surface of a sheet by a polymerizable UV absorber by curing and to provide an ethylenevinylacetate sheet with improved yellowing stability and UV stabilizing effect without difficulty of process such as melting, dispersion, etc. CONSTITUTION: A manufacturing method of ethylene vinyl acetate copolymer sheet comprises: a step of molding a sheet by mixing a polymerizable UV absorber, a crosslinking aid, a UV stabilizer, and silane coupling agent into an ethylene vinyl acetate copolymer resin. On the basis of 100.0 parts by weight of the ethylene vinyl acetate copolymer resin, the used amount of the polymerizable UV absorber is 0.01-0.5 parts by weight. The vinylacetate content of the ethylene vinyl acetate copolymer is 25-32 weight%. The melt index(190 °C, 2.16kg) is 6-30 g/10minutes.

Description

Manufacturing method of EVA sheet for solar cell encapsulant with excellent UV stability {Prepatation method for excellent UV irradiation 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 UV stability, and more particularly, a UV absorber, a crosslinking agent, a crosslinking aid, which is polymerizable to an ethylene vinyl acetate copolymer (hereinafter referred to as EVA) resin, The manufacturing method of the EVA sheet | seat for solar cell sealing materials characterized by mixing a silane coupling agent and an ultraviolet stabilizer, and shape | molding a sheet | seat.

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 a solar cell encapsulation material, in which yellowing stability and UV stabilization effect can be maintained for a long time.

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

In one embodiment, the manufacturing method of the EVA sheet for solar cell encapsulation material of the present invention, by mixing together a UV absorber, a crosslinking agent, a crosslinking aid, a UV stabilizer and a silane coupling agent polymerizable to the EVA resin to melt at the decomposition temperature of the crosslinker. The sheet is formed by kneading.

In another embodiment, the method for manufacturing the EVA sheet for solar cell encapsulation material of the present invention, the polymerizable ultraviolet absorber while melting the EVA resin composition obtained by uniformly mixing the UV stabilizer with the EVA resin at the extruder below the decomposition temperature of the crosslinking agent. And supplying a mixture of a crosslinking agent, a crosslinking aid and a 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 vinyl acetate is in the range of 30 g / 10 minutes, which is not preferable because of transparency, flexibility and blocking resistance, and when the melt index is out of the range, sheet formability and mechanical properties are inferior. Not.

The type of polymerizable ultraviolet absorbent used in the present invention is not particularly limited, and for example, at least one monomer having a structure having a double bond in the benzophenone series, the benzotriazole series, or the benzotriazine series can be used. Can be. Specific examples of the benzophenone-based ultraviolet absorber monomer 4-methylacryloxy-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-dimethacrylate (1, 3-bis- (4-benzoyl-3-hydroxyphenoxy) -prop-2-yl-3,3-dimethacrylate), 4-benzoyl-3-hydroxyphenylacrylate, 2- (4-benzoyl-3-hydroxyphenoxy) ethyl acrylate (2- (4-Benzoyl-3-hydroxyphenoxy) ethylacrylate) etc. are mentioned, As a specific example of a benzotriazole type ultraviolet absorber monomer, it is 2 [2]. -Hydroxy-4- Coxy- (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-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] ethyl methacrylate (2- [3- (2H-benzotriazol-2-yl) -4-hydroxyphenyl] ethyl methacrylate), and the like, and specific examples of the benzotriazine type ultraviolet absorber monomer include 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 method for producing an EVA sheet for solar cell encapsulation according to the present invention, it is preferable to use 0.01 to 0.5 parts by weight of a polymerizable ultraviolet absorber based on 100 parts by weight of the EVA resin, and the content of the polymerizable ultraviolet absorber is 0.01 weight. If it is less than the amount, the ultraviolet ray stabilizing 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 include 2,4-dimethyl-2,5-bis (t-butylperoxy) hexane (2,5-dimethyl-2,5-bis (t-butylperoxy) hexane And t-butyl-2-ethylhexyl monoperoxycarbonate (tert-butylperoxy-2-ethylhexyl carbonate), and the like, and specific examples of the alkyl peroxy ester-based crosslinking agent are 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 ultraviolet stabilizer used in the present invention is not particularly limited in kind, and for example, a hindered amine ultraviolet stabilizer can be used, and specific examples include bis (2,2,6,6, -tetra). Methyl-4-piperidyl) sebacate (bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate), bis- (ene-octyloxy-tetramethyl) piperidinyl sebacate (bis- ( N-octyloxy-tetramethyl) piperidinyl sebacate), bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate (bis (1,2,2,6,6-pentamethyl-4- piperidyl) sebacate) and methyl-1,2,2,6,6-pentamethyl-4-piperidyl sebacate (methyl 1,2,2,6,6-pentamethyl-4-piperidyl sebacate) It can use 1 or more types chosen from.

It is preferable that the said ultraviolet stabilizer contains 0.01-0.3 weight part with respect to 100 weight part of EVA resin, but when it is less than 0.01 weight part, the light stability effect is insignificant, and it is not preferable, and when it exceeds 0.3 weight part, it is unpreferable in economical efficiency.

The silane coupling agent used for this invention does not have a restriction | limiting in particular in the kind, For example, an organosilicon compound can be used, As a specific example, 3-methacryloxypropyl trimethoxysilane, etc. 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 ultraviolet absorber instead of the conventional ultraviolet absorber, the effect of shifting to the surface of the sheet due to the change over time, or improving the yellowing stability as well as the ultraviolet stability without difficulty of processing such as melting and dispersing can be improved. Can be.

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

Sigma Aldrich's 4-allyloxy-2-hydroxy as a polymerizable UV absorber monomer 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 0.3 parts by weight of benzophenone (4-allyloxy-2-hydroxybenzophenone), Tinuvin 770 (bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate from BASF) as a UV stabilizer. 0.7 parts by weight of Luperox TBEC (t-butyl-2-ethylhexyl monoperoxycarbonate) from Alkema, 0.5 parts by weight of TAICROS (triallyl isocyanurate) from Evonik as a crosslinking aid, and Dow Corning as a silane coupling agent After mixing 0.5 parts by weight of OFS 6030 (3-methacryloxypropyltrimethoxysiloxane), the extruder temperature was 90 ° C, the T-die temperature was 100 ° C, the sheet linear velocity was 6.5 meters per minute, and the thickness was 0.45. mm sheets were prepared.

Example 2

Polymerizable UV absorber monomer 2- (2H-benzotriazol-2-yl) -4-methyl-6- (2-propenyl) phenol (2- (2H-benzotriazol-2-yl) -4 from Sigma Aldrich A sheet was prepared in the same manner as in Example 1, except that 0.3 part by weight of -methyl-6- (2-propenyl) phenol) was added.

Example 3

3- [4- {4,6-bis (2,4-dimethylphenyl) -1,3,5-triazin-2-yl} -3-hydroxyphenoxy] -2- as a polymerizable ultraviolet absorbent monomer Hydroxypropyl methacrylate (3- [4- {4,6-bis (2,4-dimethylphenyl) -1,3,5-triazine-2-yl} -3-hydroxyphenoxy] -2-hydroxypropyl methacrylate) A sheet was prepared in the same manner as in Example 1, except that 0.3 parts by weight of the powder was added.

Comparative Example 1

A sheet was prepared in the same manner as in Example 1, except that 0.3 parts by weight of Chimassorb 81 (2-hydroxy-4-octyloxy-benzophenone) manufactured by BASF Corporation was added as an ultraviolet absorber.

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), 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 (%) 89.5% 90% 89% 90.2 Light transmittance (%) > 90% > 90% > 90% > 90% Tensile Strength (DH)
(kgf / cm2) 230 230 245 250 250 235 221 222 Tensile strength (UV)
(kgf / cm2) 155 170 160 145 Elongation (DH) (%) 550 550 560 540 530 540 540 520 Elongation (UV) (%) 530 525 500 490 YI (DH) 1.80 5.30 1.77 5.20 1.86 4.5 1.99 5.8 YI (UV) 6.25 6.50 6.76 8.30

* 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 stability, it can be seen that UV stability is further improved over time.

Claims (7)

A method for producing an ethylene vinyl acetate copolymer sheet for a solar cell encapsulating material comprising forming a sheet by mixing an ethylene vinyl acetate copolymer resin with a polymerizable ultraviolet absorber and an organic peroxide, a crosslinking aid, an ultraviolet stabilizer and a silane coupling agent as a crosslinking agent. The sheet according to claim 1, wherein the ethylene vinyl acetate copolymer resin is mixed with a polymerizable ultraviolet absorber, an organic peroxide, a crosslinking aid, an ultraviolet stabilizer and a silane coupling agent together to melt and knead the organic peroxide at a decomposition temperature or less to form a sheet. The manufacturing method of the ethylene vinyl acetate copolymer sheet for solar cell sealing materials which are used. The polymerizable UV absorber, organic peroxide, crosslinking according to claim 1, wherein the ethylene vinyl acetate copolymer resin composition obtained by uniformly mixing the UV stabilizer with the ethylene vinyl acetate copolymer resin is melted at the decomposition temperature of the organic peroxide in the extruder. A method of manufacturing an ethylene vinyl acetate copolymer sheet for solar cell encapsulating material, characterized in that a mixture of a preparation and a silane coupling agent is supplied to the extruder through a separate raw material supply device and melt kneaded to form a sheet. The ethylene vinyl acetate air for solar cell encapsulation material according to any one of claims 1 to 3, wherein 0.01 to 0.5 parts by weight of the polymerizable ultraviolet absorber is used with respect to 100 parts by weight of the ethylene vinyl acetate copolymer resin. Method for producing coalesced sheet. 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 solar cell according to any one of claims 1 to 3, wherein the polymerizable ultraviolet absorber is at least one selected from compounds having a double bond in the benzophenone series, the benzotriazole series, or the benzotriazine series. The manufacturing method of the ethylene vinyl acetate copolymer sheet for sealing materials. 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.