KR101229678B1 - Preparation method for high thermally conductive and electrically insulating EVA sheet for solar cell encapsulant - Google Patents

Abstract

The present invention relates to a method for manufacturing an EVA sheet for solar cell encapsulation material having excellent electrical insulation and thermal conductivity, and more particularly, to an ethylene vinyl acetate copolymer resin, an additive having excellent electrical insulation and thermal conductivity, an ultraviolet light absorber, a light stabilizer, and a crosslinking agent. And a crosslinking aid and a silane coupling agent to form a sheet, and to a method for producing a EVA sheet for solar cell encapsulant.

Description

Preparation method of EAA sheet for solar cell encapsulation material having excellent electrical insulation and thermal conductivity {Preparation method for high thermally conductive and electrically insulating 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 electrical insulation and thermal conductivity, and more particularly, excellent in electrical insulation and thermal conductivity 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 an sheet by mixing an additive, an ultraviolet absorbent, a light stabilizer, 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 the solar light is incident, and on the other side, the sheet having excellent water barrier and weather resistance It is laminated. 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 a crosslinking agent, a crosslinking aid, a silane coupling agent, an antioxidant, a light stabilizer, and a UV 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.

On the other hand, in general, the amount of photovoltaic power generation is closely correlated with the temperature of the solar cell operation module, and more particularly in the case of a crystalline silicon solar cell module. In other words, as the operating module temperature increases, the amount of generation decreases in inverse relationship. According to the literature, although the amount of solar radiation is the same day, the amount of generation in the summer with high module temperature is lower than the amount of generation in winter with low module temperature. (Shin Hye-Young, Master's Thesis, Hongik University "A Study on the Output by Temperature Change of Front and Back of Solar Module", 2009).

However, the conventional solar cell module is surrounded by an extremely low thermal conductivity EVA sheet above, below, and around the cell (EVA thermal conductivity: 0.23 W / mK). There was a disadvantage that can not be released to the outside.

Recently, various technologies have been developed and applied for a solution to compensate for the above disadvantages, and as a representative example, in Korean Laid-Open Patent Publication No. 10-2010-0131201, a solar cell module has a backsheet removed. In the structure, by adding a thermally conductive metal powder to the back of the EVA sheet, a technology for maximizing the power generation efficiency by lowering the temperature inside the module by the heat dissipation effect of the EVA sheet having a heat dissipation characteristic is disclosed. However, most of the metal powders cited in this patent are not only suitable for solar cell encapsulation materials that require electrical insulation due to their excellent thermal conductivity and electrical conductivity. Since only EVA sheet containing a thermally conductive metal powder is used, there is a possibility that long-term weather resistance problems will also occur.

An object of the present invention is to provide a method for producing an EVA sheet for solar cell encapsulant having excellent electrical insulation and thermal conductivity, which is particularly suitable for use between a cell and a cell back side protective member in a solar cell module.

The method for manufacturing an EVA sheet for solar cell encapsulation according to the present invention is characterized in that the sheet is formed by mixing an additive, an ultraviolet absorber, a light stabilizer, a crosslinking agent, a crosslinking aid, and a silane coupling agent which are excellent in electrical insulation and thermal conductivity with EVA resin. It is done.

In one embodiment, the manufacturing method of the EVA sheet for solar cell encapsulation material of the present invention, by mixing the EVA resin with additives, UV absorbers, light stabilizers, crosslinking agents, crosslinking aids and silane coupling agents together with excellent electrical insulation and thermal conductivity Shaping and kneading at a temperature below the decomposition temperature of the crosslinking agent to form a sheet.

In another embodiment, the manufacturing method of the EVA sheet for solar cell encapsulant of the present invention, EVA resin composition obtained by uniformly mixing the additives, ultraviolet absorbers and light stabilizers excellent in electrical insulation and thermal conductivity with EVA resin of the crosslinking agent in the extruder It melt | melts and knead | mixes a crosslinking agent, a crosslinking adjuvant, and a silane coupling agent, melt | melting below a decomposition temperature, and shape | molding a sheet | seat.

An example of a method of manufacturing an EVA sheet for solar cell encapsulant of the present invention according to this embodiment may include the following steps:

(1) melt-kneading an EVA resin with an additive having excellent electrical insulation and thermal conductivity, an ultraviolet absorber and a light stabilizer at 80 to 220 ° C. to obtain a resin composition, and

(2) mixing the crosslinking agent, the crosslinking aid and the silane coupling agent to the EVA resin composition obtained in the step (1) to melt kneading at a temperature below the decomposition temperature of the crosslinking agent to form a sheet.

In the step (1), the temperature at the time of melt kneading is preferably 80 ~ 220 ℃, if out of this temperature range, sheet formability is bad, it is not preferable.

In the step (2), the crosslinking agent, the crosslinking aid and the silane coupling agent are mixed with the EVA resin composition obtained in the step (1) to melt kneading at a temperature below the decomposition temperature of the crosslinking agent to form a sheet.

Alternatively, in step (2), a mixture of a crosslinking agent, a crosslinking aid, and a silane coupling agent is separately dissolved while melting the EVA resin composition obtained by the above step (1) with an additive dispersed uniformly at an decomposition temperature of the organic peroxide or less with an extruder. The sheet may be formed by supplying the extruder through a raw material supply device to melt-kneading the sheet.

In the step (2), when melt kneading at a temperature higher than the decomposition temperature of the crosslinking agent, sheet formability is bad or cross-linking occurs, which is not preferable.

In another embodiment, the manufacturing method of the EVA sheet for solar cell encapsulant of the present invention, the additive-containing EVA sheet (insulating heat-resistant EVA sheet) excellent in electrical insulation and thermal conductivity by the manufacturing method of the EVA sheet of the present invention as described above In manufacturing the sheet, the EVA sheet for conventional solar cell encapsulant which does not contain the additive having excellent electrical insulation and thermal conductivity is co-extruded into at least one of the upper and lower surfaces of the EVA sheet and formed into a sheet having a multilayer structure. It involves doing.

In the sheet of such a multilayer structure, the thickness of the additive-containing insulating heat resistant EVA sheet excellent in electrical insulation and thermal conductivity according to the present invention is preferably 50% or more of the total thickness of the multilayer EVA sheet in terms of electrical insulation and thermal conductivity. Is preferably 50 to 80%.

In the method of manufacturing an EVA sheet for solar cell encapsulation according to the present invention, the EVA resin has a vinyl acetate (VA) content of 15 to 32% by weight, and a melt index (measured by a load of 190 ° C. and 2.16 kg) is 1 to 1. It is preferable that the content of the vinyl acetate is in the range of 30 g / 10 minutes, which is not preferable because of its flexibility and blocking resistance, and when the melt index is out of the range, sheet formability and mechanical properties are poor. Not.

The additive having excellent electrical insulation and thermal conductivity used in the present invention is not particularly limited in its kind, and is selected from the group consisting of, for example, boron nitride, zinc oxide, magnesium oxide, aluminum oxide, silicon carbide, and ulastonite. 1 or more types can be used.

It is preferable that the average particle size of the additive having excellent electrical insulation and thermal conductivity is 0.5 to 100 μm. However, when the average particle size of the additive is less than 0.5 μm, economical efficiency is not preferable, and when the average particle size exceeds 100 μm, thermal conductivity is exceeded. The effect is negligible and undesirable.

In the method for producing an EVA sheet for solar cell encapsulation according to the present invention, it is preferable to use 1.0 to 80 parts by weight of an additive having excellent electrical insulation and thermal conductivity with respect to 100 parts by weight of the EVA resin, but the content of the additive is 1.0 If it is less than the weight part, the heat conduction effect is insignificant, and it is not preferable. If it exceeds 80 parts by weight, economic efficiency is inferior.

The ultraviolet absorbers used in the present invention are 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-2'-carboxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2 -Hydroxy-4-n-dodecyloxybenzophenone, 2-hydroxy-4-n-octadecyloxybenzophenone, 2-hydroxy-4-benzyloxybenzophenone, 2-hydroxy-4-methoxy -5-Sulfobenzophenone, 2-hydroxy-5-chlorobenzophenone, 2,4-dihydroxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-di One or more types selected from the group consisting of hydroxy-4,4'-dimethoxybenzophenone and 2,2 ', 4,4'-tetrahydroxybenzophenone 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 ultraviolet absorber with respect to 100 parts by weight of the EVA resin, but less than 0.01 parts by weight of the ultraviolet stabilizing effect is insignificant It is unpreferable, and when it exceeds 0.5 weight part, it becomes discolored or it is uneconomical and unpreferable.

The light stabilizer used in the present invention is not particularly limited in kind, and for example, a hindered amine light stabilizer may be used, and specific examples thereof include bis (2,2,6,6-tetramethyl- 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) and the like. One or more kinds selected may be used.

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 0.3 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 The light stability effect is not preferable because it is insignificant, and when it exceeds 0.3 parts by weight, it is not preferable because of poor economic efficiency.

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, and also it can also 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 system 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 silane coupling agent used in the present invention is not particularly limited in kind, 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 necessary.

According to the present invention, by adding an additive having excellent electrical insulation and thermal conductivity to an existing EVA sheet composition for a solar cell encapsulation material, it is possible to lower the internal temperature of the solar cell module, and to maximize the power generation efficiency of the module.

1 is an example of a solar cell module consisting of a cover glass, a transparent EVA sheet, a solar cell, an insulating heat-resistant EVA sheet and a protective backsheet prepared according to the present invention,
2 is an example of a multilayer structure sheet made of a transparent EVA sheet, an insulating heat-resistant EVA sheet, and a transparent EVA sheet produced by the present invention.

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, Germany ESK Ceramics as an additive having excellent electrical insulation and thermal conductivity based on 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. 20 parts by weight of boron nitride (BORONID® S1-SF, average particle diameter: 2 µm), 0.3 parts by weight of Chimassorb 81 (2-hydroxy-4-octyloxy-benzophenone) from BASF Corporation as a UV absorber, UV stabilizer (light stabilizer) As a BASF Tinuvin 770 (bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate) 0.1 parts by weight of the mixture was added to the extruder, melt-kneaded at an extrusion temperature of 190 ℃ pelletized EVA resin A composition was obtained.

0.7 parts by weight of Luperox TBEC (t-butyl-2-ethylhexyl monoperoxycarbonate) manufactured by Alchema Inc. as a crosslinking agent with respect to 100 parts by weight of the EVA resin composition pellet obtained above, TAICROS (triallyl isocyanur) manufactured by Evonik Corporation as a crosslinking aid Rate) 0.5 parts by weight and 0.5 parts by weight of OFS 6030 (3-methacryloxypropyltrimethoxysiloxane) manufactured by Dow Corning as a silane coupling agent, followed by mixing the extruder temperature at 90 ° C and the T-die temperature at 100 ° C. The sheet having a thickness of 0.45 mm was prepared with a linear velocity of 6.5 meters per minute.

Example 2

A sheet was manufactured in the same manner as in Example 1, except that 45 parts by weight of boron nitride (BORONID® S1-SF) manufactured by ESK Ceramics, Germany, was added as an additive having excellent electrical insulation and thermal conductivity.

Example 3

A sheet was manufactured in the same manner as in Example 1, except that 20 parts by weight of aluminum nitride H Grade (average particle diameter: 1 mu m) manufactured by Tokuyama, Japan, was added as an additive having excellent electrical insulation and thermal conductivity.

Example 4

The same composition as in Example 1 was melt-kneaded under the same molding conditions, and the same composition as Example 1 was melt-kneaded under the same molding conditions except that boron nitride was not added in the extruder 2 to co-extrude the die. Co-extruded melt kneaded in Extruder 1 into an intermediate layer having a thickness of 350 μm, and co-extruded into the upper and lower layers of the melt kneaded in Extruder 2 into a three-layered sheet having a total thickness of 0.45 mm It was.

Comparative Example 1

Vasp's Chimassorb 81 (2-hydroxy-4-octyloxy-) as a UV absorber 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) according to the composition of Table 1. 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 a sheet having a thickness of 0.45 mm was produced with an extruder temperature of 90 ° C and a T-die temperature of 100 ° C and a linear speed of the sheet of 6.5 meters per minute.

Example 5

In the case of specimen preparation for measuring the adhesive strength with tempered glass, 1 sheet of EVA sheet (200 mm × 160 mm) obtained in Example 1 was placed on the low iron tempered glass (200 mm × 200 mm), and the DNP backsheet (200 mm × 200 mm), and in the case of specimen preparation for measuring crosslinkability, electrical insulation and thermal conductivity, one sheet of EVA sheet (200 mm x 160 mm) obtained in Example 1 was placed on a Teflon sheet, and the Teflon sheet was placed thereon again, and the temperature was 150 ° C. After the vacuum step for 6 minutes, and then, the specimen was prepared by crosslinking by maintaining the difference between the laminator upper pressure and lower pressure at 100Mpa for 16 minutes. After the cooling process at room temperature, the internal bubbles and residual states of the prepared specimens were visually observed. The crosslinked specimens were evaluated for adhesive strength (N / cm), crosslinking degree, electrical insulation, and thermal conductivity. Peel test conditions with glass were measured at a peel rate of 152 mm / min in a 180 degree direction using a UTM tensile strength meter according to ASTM 903. The crosslinking degree was measured using solvent xylene according to ASTM D2765, the volume specific resistance was measured according to ASTM D257 for electrical insulation, and the thermal conductivity was evaluated according to ASTM E 1530 (plate heat flow method).

Example 6

Except for using the sheet prepared in Example 2, the specimen was prepared in the same manner as in Example 5, and observed, measured and evaluated in the same manner.

Example 7

Except for using the sheet prepared in Example 3, the specimen was prepared in the same manner as in Example 5, observed, measured and evaluated in the same manner.

Example 8

Except for using the sheet prepared in Example 4, the specimen was prepared in the same manner as in Example 5, 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 5, observed, measured and evaluated in the same manner.

Table 2 shows the results of evaluating the physical properties of the crosslinked sheets obtained in Examples 5 to 8 and Comparative Example 2.

As shown in the results of Table 2, according to the method according to the present invention, it is possible to manufacture an EVA sheet for solar cell encapsulant having excellent thermal conductivity without significantly lowering the degree of crosslinking, adhesive strength, and electrical insulation. It can be seen.

10 ... Cover glass
30A. Transparent EVA sheet
40 ... Solar cell
30B. Insulation Heat Resistant EVA Sheet
20 ... Protective member layer
31B. Transparent EVA sheet
32B. Insulation Heat Resistant EVA Sheet
31B. Transparent EVA sheet

Claims (13)

delete delete delete Method for producing an ethylene vinyl acetate copolymer sheet for a solar cell encapsulation material comprising the following steps;
(1) melting and kneading an ethylene vinyl acetate copolymer resin with an electrically insulating and thermally conductive additive, an ultraviolet absorber, and a light stabilizer at 80 to 220 ° C. to obtain a resin composition, and
(2) mixing the organic peroxide, the crosslinking aid and the silane coupling agent as a crosslinking agent in the ethylene vinyl acetate copolymer resin composition obtained in the step (1) to melt kneading at a temperature below the decomposition temperature of the crosslinking agent to form a sheet. The method according to claim 4, wherein in step (2), an organic peroxide, a crosslinking aid and a silane coupling agent are mixed with the ethylene vinyl acetate copolymer resin composition obtained in step (1), and then melted at a decomposition temperature of the organic peroxide. A method for producing an ethylene vinyl acetate copolymer sheet for solar cell encapsulant, which is kneaded to form a sheet. The method of claim 4, wherein the mixture of the organic peroxide, the crosslinking aid and the silane coupling agent is supplied to the ethylene vinyl acetate copolymer resin composition obtained in the step (1) in the step (2) through a separate raw material supply device, and melted. A method for producing an ethylene vinyl acetate copolymer sheet for solar cell encapsulant, which is kneaded to form a sheet. 5. The method of claim 4, wherein at the time of forming the electrically insulating and thermally conductive additive-containing ethylene vinyl acetate copolymer sheet, the electrically insulating and thermally conductive additives are contained on at least one of upper and lower surfaces of the ethylene vinyl acetate copolymer sheet. A method of manufacturing an ethylene vinyl acetate copolymer sheet for solar cell encapsulation, further comprising co-extruding an ethylene vinyl acetate copolymer sheet for solar cell encapsulation that is not formed. 8. The ethylene vinyl acetate copolymer for solar cell encapsulation material according to claim 7, wherein the thickness of the electrically insulating and thermally conductive additive-containing ethylene vinyl acetate copolymer sheet is 50 to 80% of the total thickness of the multilayer structure sheet. Manufacturing method of the sheet. The ethylene vinyl for solar cell encapsulation material according to any one of claims 4 to 8, wherein 1.0 to 80 parts by weight of the electrically insulating and thermally conductive additive is used based on 100 parts by weight of the ethylene vinyl acetate copolymer resin. Process for the preparation of acetate copolymer sheet. The vinyl acetate content of the ethylene vinyl acetate copolymer resin is 15 to 32% by weight, and the melt index (190 DEG C, measured at a load of 2.16 kg) is 1 to 30 g. Method for producing an ethylene vinyl acetate copolymer sheet for solar cell encapsulation material characterized in that / 10 minutes. The method of claim 4, wherein the electrically insulating and thermally conductive additive is one or more selected from the group consisting of boron nitride, zinc oxide, magnesium oxide, aluminum oxide, silicon carbide, and ulastonite. A method for producing an ethylene vinyl acetate copolymer sheet for solar cell encapsulant. The method of manufacturing an ethylene vinyl acetate copolymer sheet for solar cell encapsulation according to any one of claims 4 to 8, wherein the average particle size of the electrically insulating and thermally conductive additives is 0.5 to 100 µm.


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