KR101090834B1 - Method for preparing adhesive sheet for solar celll - Google Patents

Abstract

PURPOSE: A method for manufacturing the adhesive sheet for a solar cell is provided to improve productivity and reduce manufacturing costs by molding an ethylene copolymer without the limit of temperature. CONSTITUTION: A sheet is manufactured by molding the mixture including an ethylene copolymer and additives(S0). A cross-linking agent is coated on an ethylene copolymer sheet(S1). A coated sheet is dried at a temperature of 30 to 50°C for 1 second to 120 seconds(S2). A dried sheet is frozen at a temperature of 10 to 20°C for 1 second to 120 seconds(S3).

Description

Manufacturing Method of Adhesive Sheet for Solar Cell {METHOD FOR PREPARING ADHESIVE SHEET FOR SOLAR CELLL}

The present invention relates to a method for producing a solar cell adhesive sheet having advantages in productivity and cost without causing gelation by a crosslinking agent that lacks thermal stability.

Recently, solar cells which directly convert the energy of solar energy, which is clean energy, into electricity as a next generation energy source are rapidly spreading.

Generally, as shown in FIG. 1, a solar cell includes a solar cell element 1, an upper protective material 2 and a lower protective material or a back sheet 3 which are respectively located above and below the solar cell device 1. These are fixed and constituted by the adhesive sheet 4.

In order to increase the power generation efficiency of the solar cell, the adhesive sheet 4 is required to have excellent transmittance and adhesion and less yellowing in a durable environment. In view of this, an adhesive sheet 4 such as ethylene-vinyl acetate (EVA) It is made of a copolymer. Specifically, various additives such as a crosslinking agent and the like are added to the ethylene-vinyl acetate copolymer, and then uniformly mixed with each other, and then produced in a sheet shape at a temperature at which the crosslinking agent is not decomposed. The prepared adhesive sheet is bonded together with a member constituting the solar cell using a device such as a vacuum bonding machine, and then fixed to the member by crosslinking.

However, there is a problem in that the crosslinking agent among the additives is deficient in thermal stability and decomposes during the molding into a sheet shape to cause the crosslinking reaction to cause gelation.

In consideration of these problems, a method of suppressing an increase in the process temperature by lowering the line speed of the molding process during the manufacture of the adhesive sheet has been proposed. That is, in order to improve productivity, the line speed of the molding process should be increased, and thus the process temperature is inevitably increased. As another method, a method of excluding the use of a crosslinking agent has been proposed, but the adhesive sheet prepared by this method has a poor airtightness and thus has poor adhesion performance, poor weatherability and long-term stability, making it difficult to apply as an adhesive sheet for solar cells. .

It is an object of the present invention to provide a method for manufacturing a solar cell adhesive sheet which has advantages in terms of productivity and improved productivity while preventing excellent gelation by a crosslinking agent lacking thermal stability.

1. coating a crosslinking agent on an ethylene-based copolymer sheet; And drying the coated sheet at a temperature of 30 to 50 ° C. for 1 to 120 seconds.

2. according to the above 1, before the coating step of forming a mixture containing an ethylene-based copolymer to prepare a sheet for producing a solar cell adhesive sheet comprising a step.

3. In the above 2, the mixture is a method for producing a solar cell adhesive sheet comprising an ethylene-based copolymer and additives.

4. In the above 2, the molding is a manufacturing method of the solar cell adhesive sheet is carried out at a temperature of 80 to 220 ℃.

5. In the above 1, the ethylene-based copolymer melt mass flow (MFR) is 20 to 40g / 10 minutes manufacturing method of the solar cell adhesive sheet.

6. In the above 1, wherein the crosslinking agent is mixed with an organic solvent manufacturing method for a solar cell adhesive sheet.

7. In the above 1, the coating method of the solar cell adhesive sheet is performed by the slit coating, slot coating, dip coating, spray coating, gravure coating or squeeze coating method.

8. according to the above 1, the coating is a manufacturing method of the solar cell adhesive sheet is carried out for 1 to 120 seconds at a temperature of 30 to 40 ℃.

9. according to the above 1, the method of manufacturing a solar cell adhesive sheet further comprising the step of cooling the dried sheet after the drying step.

10. In the above 9, the cooling method for manufacturing a solar cell adhesive sheet is performed for 1 to 120 seconds at a temperature of 10 to 20 ℃.

According to the present invention, a crosslinking agent lacking thermal stability during the molding of an ethylene copolymer may be decomposed to cause a crosslinking reaction or gelling thereof, thereby producing a solar cell adhesive sheet.

In addition, the present invention can form the ethylene-based copolymer without limiting the temperature can increase the line speed can greatly contribute to the productivity improvement, there is an advantage in terms of cost.

In addition, the present invention is capable of forming the ethylene copolymer at high temperature, so that the shrinkage rate can be suppressed by inducing the crystallization of the ethylene copolymer to produce a non-shrinkable product excellent in durability and adhesion without a separate annealing equipment. Can be.

1 is a schematic cross-sectional view of a solar cell,
2 is a manufacturing process chart of the solar cell adhesive sheet according to an embodiment of the present invention,
3 is a manufacturing process chart of the solar cell adhesive sheet according to another embodiment of the present invention,
Figure 4 is a manufacturing process of the adhesive sheet for a solar cell according to another embodiment of the present invention.

The present invention relates to a method for producing a solar cell adhesive sheet having advantages in productivity and cost without causing gelation by a crosslinking agent that lacks thermal stability.

Hereinafter, the present invention will be described in detail.

Method for producing a solar cell adhesive sheet of the present invention comprises the steps of coating a crosslinking agent on the ethylene-based copolymer sheet; And drying the coated sheet at a temperature of 30 to 50 ° C. for 1 to 120 seconds.

Method for manufacturing an adhesive sheet for a solar cell according to an embodiment of the present invention, as shown in Figure 2, the step of coating a crosslinking agent on the ethylene-based copolymer sheet (S1) and drying the coated sheet (S2) It includes.

In addition, the manufacturing method of the solar cell adhesive sheet according to another embodiment of the present invention, as shown in Figure 3, the step of coating a crosslinking agent on the ethylene-based copolymer sheet (S1), drying the coated sheet ( S2) and cooling the dried sheet (S3).

In addition, the manufacturing method of the solar cell adhesive sheet according to another embodiment of the present invention, as shown in Figure 4, containing the ethylene copolymer before the step (S1) of coating the crosslinking agent on the ethylene-based copolymer sheet It may comprise the step (S0) to form a mixture to form a sheet.

First, a mixture containing an ethylene copolymer is molded to prepare a sheet (S0).

The mixture containing the ethylene copolymer may include additives other than the ethylene copolymer and the crosslinking agent.

The ethylene copolymer has a melt mass flow rate (MFR) of 0.1 to 100 g / 10 minutes, preferably 20 to 40 g / 10 minutes at a load of 190 ° C. and 2160 kg, in view of moldability and mechanical properties. If the melt mass flow (MFR) does not fall within the above range can be reduced coating properties when coated with a crosslinking agent.

As an ethylene copolymer, Ethylene-vinyl ester copolymers, such as ethylene-vinyl acetate; Ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-methyl methacrylate copolymer, ethylene-ethyl methacrylate copolymer, ethylene-isobutyl acrylate copolymer, ethylene-n-butyl acrylate copolymer Ethylene-unsaturated carboxylic acid ester copolymers; Ethylene-unsaturated carboxylic acid copolymers such as ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, and ethylene-isobutyl methacrylate-methacrylic acid copolymer; These ionomers etc. are mentioned, These can be used individually or in mixture of 2 or more types. Among these, an ethylene-vinyl acetate copolymer is preferable in consideration of the suitability for physical properties required as an adhesive sheet for solar cells and the reactivity with a crosslinking agent, such as formability, transparency flexibility, adhesiveness, light resistance, and the like.

When ethylene-vinyl acetate copolymer is used, the content of vinyl acetate is preferably 20 to 40% by weight, preferably 25 to 35% by weight in consideration of transparency, flexibility, reactivity with a crosslinking agent, and the like.

A commercially available product can also be used as an ethylene-vinyl acetate copolymer. For example, TPC MA-10 (vinyl acetate content 32%, melt mass flow 40g / 10min), KA-40 (vinyl acetate content 28%, melt mass flow 20g / 10min), DuPont PV 1650 (vinyl acetate content) 33%, melt mass flow of 31 g / 10 min).

Examples of the additive include silane coupling agents, crosslinking aids, ultraviolet absorbers, and the like, and antioxidants, light stabilizers, light diffusing agents, flame retardants, and discoloration inhibitors may be further used.

The silane coupling agent is a component that improves the adhesion to other members constituting the solar cell, such as low iron tempered glass, back sheet, etc. when manufacturing the solar cell using the solar cell adhesive sheet.

Examples of the silane coupling agent include compounds having an alkoxy group hydrolyzable together with an unsaturated group such as a vinyl group, an acryloxy group, a methacryloxy group, an amino group, an epoxy group and the like. Specifically, N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane, N- (β-aminoethyl) -γ-aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, γ- Glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, vinyltrichlorosilane, vinyltri-β-methoxyethoxysilane, β- (3, 4-ethoxycyclohexyl) ethyl trimethoxysilane, etc. are mentioned, These can be used individually or in mixture of 2 or more types.

The silane coupling agent is preferably contained in an amount of 0.1 to 2 parts by weight based on 100 parts by weight of the ethylene copolymer. If the content is less than 0.1 parts by weight, the adhesion improving effect may be insignificant, and if the content is more than 2 parts by weight, the additional adhesion improving effect is not large, which is uneconomical.

The crosslinking aid is a component that promotes a crosslinking reaction to increase the degree of crosslinking of the ethylene copolymer. Polyallyl compounds such as triallyl isocyanurate, triallyl cyanurate, diallyl phthalate, diallyl fumarate, and diallyl maleate ; Poly (meth) acryloxy compounds such as ethylene glycol diacrylate, ethylene glycol dimethacrylate, trimethylolpropane trimethacrylate and the like; Divinylbenzene etc. are mentioned, These can be used individually or in mixture of 2 or more types.

The crosslinking aid is preferably contained in an amount of 0.5 to 5 parts by weight based on 100 parts by weight of the ethylene copolymer. If the content is less than 0.5 parts by weight, the crosslinking promoting effect may be insignificant, and when it is more than 5 parts by weight, yellowing may occur.

As a ultraviolet absorber, a benzophenone type compound, a benzotriazole type compound, a triazine type compound, a salicylic acid ester type compound, etc. are mentioned. Commercially available products include Tinuvin 328, Tinuvin 1577 FF, Tinuvin 120, Chimasorb 81, and the like; Sumisorb 130, sumisorb 350, sumisorb 110 from Sumitomo Chemical Co., Ltd .; Seepro 102, seesorb 707, seesorb 101, etc. of ciprocasei can also be used. These can be used individually or in mixture of 2 or more types.

The ultraviolet absorber is preferably contained in an amount of 0.1 to 2 parts by weight based on 100 parts by weight of the ethylene copolymer. If the content is less than 0.1 parts by weight of the sunscreen may be insignificant, and if more than 2 parts by weight may cause yellowing.

The mixture containing the components as described above is molded to prepare a sheet. The molding method is not particularly limited, and examples thereof include a known method using a T-die extruder, a calender molding machine, or the like. The method using a T-die extruder is a method of manufacturing a sheet through a T-die while melt-mixing the raw material mixture in an extruder, and the method using a calender molding machine produces a sheet by rolling while melting the raw material mixture in several rolls. That's how. Among these, the calender molding machine requires a large number of expensive calender rolls to increase the thickness uniformity of the sheet to be manufactured, and therefore, a method using a T-die is mainly used in terms of economy. Specifically, after mixing, drying, and blending a mixture containing an ethylene-based copolymer and an additive except a crosslinking agent, it is supplied to a feeder of a T-die extruder, and melt mixing of the mixture supplied through the extruder is performed. The molten mixture is transferred quantitatively to the T-die and made into a sheet using the T-die.

In particular, in the present invention, since the sheet is manufactured using a mixture containing no crosslinking agent as a raw material, it is not necessary to consider the decomposition temperature of the crosslinking agent, and even when the line speed of the molding process is increased, the temperature change due to the exotherm is not significantly affected. Therefore, it can be molded at a high temperature without restriction. Usually, the mixture containing the crosslinking agent can be molded at a temperature of 120 ° C. or lower, and in this case, part of the crosslinking agent is decomposed to cause gelation, and thus the molding is performed at the lowest possible temperature. On the other hand, the molding temperature in the present invention is not particularly limited, for example, it may be carried out at a temperature of 80 to 220 ℃. That is, it can be molded at high temperature and fast process line speed to improve productivity as well as to reduce the shrinkage rate by inducing the crystallization of the ethylene-based copolymer to produce non-shrinkable products without a separate annealing equipment. .

When the ethylene-based copolymer sheet is prepared, a crosslinking agent is coated on the prepared ethylene-based copolymer sheet (S1).

In particular, the present invention is characterized by suppressing thermal decomposition and gelling phenomenon by eliminating the use of a crosslinking agent lacking thermal stability in the production of the ethylene-based copolymer sheet and applying the excluded crosslinking agent to the surface of the prepared sheet. In addition, the present invention is characterized in that only the crosslinking agent is used without using any additives used in the preparation of the ethylene-based copolymer sheet in addition to the organic solvent for coating in the coating of the crosslinking agent. When components other than the crosslinking agent are used in coating, it is difficult to obtain the desired sufficient physical properties.

It is preferable to use a crosslinking agent in which the decomposition temperature (the temperature having a half life of 1 hour) is 150 ° C. or less and a liquid state at room temperature in consideration of the ease of coating.

Examples of the crosslinking agent are cumyl peroxide (142 ° C.), dicumyl peroxide (135 ° C.), 1,3-bis (2-t-butylperoxyisopropyl) hexane (137 ° C.), 2,5-dimethyl-2,5 Bis (t-butylperoxy) hexane (140 ° C.), t-butyl cumyl peroxide (142 ° C.), dit-butyl peroxide (149 ° C.), 2,5-dimethyl-2,5-bis (t Alkyl peroxide compounds such as -butyl peroxy) hexyn-3,1,3-bis (tertiary butylperoxyisopropyl) benzene (137 ° C); t-butylperoxyisobutyrate (102 ° C), t-butylperoxymaleic acid (110 ° C), t-butylperoxyisonanoate (123 ° C), t-butylperoxyisopropylcarbonate (119 ° C), t -Butyl peroxy-2-ethylhexyl carbonate (121 degreeC), t-butyl peroxy acetate (123 degreeC), t-butylperoxy benzoate (125 degreeC), 2,5-dimethyl-2,5-bis ( Alkyl peroxy ester compounds such as benzoyl peroxy) hexane (118 ° C) and 2,5-dimethylhexyl-2,5-bisperoxybenzoate (118 ° C); 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane (112 ° C), 1,1-bis (t-butylperoxy) cyclohexane (112 ° C), 1,1- Bis (t-amylperoxy) cyclohexane (112 ° C), 2,2-bis (t-butylperoxy) butane (112 ° C), n-butyl-4,4-bis (t-butylperoxy) ballet Peroxy ketal compounds, such as a rate (129 degreeC) and ethyl-3, 3-bis (t-butylperoxy) butyrate (135 degreeC), etc. are mentioned, These can be used individually or in mixture of 2 or more types.

The crosslinking agent is preferably coated to have a content of 0.5 to 1.5 parts by weight based on 100 parts by weight of the ethylene copolymer resin. If the content is less than 0.5 parts by weight, the degree of crosslinking may be insufficient, and if it is more than 1.5 parts by weight, excessive crosslinking reaction may be caused.

The crosslinking agent may be mixed with an organic solvent. The kind of organic solvent is not specifically limited, For example, methyl ethyl ketone (MEK), isopropanol (IPA), methyl isobutyl ketone (MIBK), etc. are mentioned, These can be used individually or in mixture of 2 or more types. The organic solvent may be mixed in an amount of 1,000 to 2,000 parts by weight based on 100 parts by weight of the crosslinking agent. When the content is less than 1,000 parts by weight, the coating property of the crosslinking agent may be lowered, thereby lowering the crosslinking efficiency. When the content is more than 2,000 parts by weight, the content of the crosslinking agent in the coating solution may be relatively low to lower the crosslinking efficiency.

The coating method is not particularly limited, and known methods such as slit coating, slot coating, dip coating, spray coating, gravure coating or squeeze coating can be used.

In addition, the coating is preferably performed for 1 to 120 seconds, preferably 10 to 60 seconds at a temperature of 30 to 40 ℃. In the case of coating under such conditions, the coating of the crosslinking agent may be completed within a short time, and the degradation of the crosslinking agent may be suppressed during the coating process.

In the present invention, when the coating is completed, while drying the coated ethylene-based copolymer sheet, it is characterized by drying in a short time (S2).

Drying is preferably performed for 1 to 120 seconds, preferably 5 to 60 seconds at a temperature of 30 to 50 ℃. If the drying temperature is less than 30 ℃ organic solvent contained in the cross-linking agent coating liquid may not be completely dried, if the drying temperature is greater than 50 ℃ may cause decomposition of the cross-linking agent. In addition, when the drying time is greater than 120 seconds, the length of the drying furnace is increased when the drying temperature is considered, and the cost may be increased in comparison with the production amount.

In addition, the dried ethylenic copolymer sheet is cooled in a short time (S3).

Cooling is preferably performed for 1 to 120 seconds, preferably 5 to 60 seconds at a temperature of 10 to 20 ℃. If the cooling temperature is less than 10 ° C, dew may be generated due to moisture. If the cooling temperature is higher than 20 ° C, a blocking problem may occur due to stickiness on the surface of the sheet. In addition, when the cooling time is more than 120 seconds, the length of the cooling furnace is long, which is not advantageous in terms of productivity and cost.

Drying and cooling may be performed using a dryer and a cooler, respectively, or may be continuously performed using a single device capable of temperature control.

In the present invention, the thickness of the sheet is adjusted between the step (S0) and the step of coating (S1) of preparing the ethylene-based copolymer sheet, or after the step (S2) of drying, preferably after the step (S3) of cooling. It may further comprise a step.

In addition, after the step of drying (S2) or the step of cooling (S3) may further include the step of inspecting the defect of the sheet and the step of winding in the form of a roll using a winder.

According to the manufacturing method of the adhesive sheet for solar cells of the present invention configured as described above, the crosslinking agent lacking thermal stability during the molding of the ethylene-based copolymer is decomposed to cause a crosslinking reaction or gelling caused by this to reduce the shrinkage rate and adhesion It is possible to manufacture an adhesive sheet for solar cells with excellent durability. In addition, when forming the ethylene-based copolymer, it is not necessary to consider not only temperature limitation but also a problem of temperature increase due to heat generation, thereby increasing the line speed to improve productivity and reduce costs.

Hereinafter, preferred examples are provided to aid the understanding of the present invention, but these examples are merely illustrative of the present invention and are not intended to limit the scope of the appended claims. It is apparent to those skilled in the art that various changes and modifications can be made to the present invention, and such modifications and changes belong to the appended claims.

Example

Example 1

100 parts by weight of ethylene-vinyl acetate copolymer (KA-40, TPC), 2 parts by weight of triallyl isocyanurate (TAIC 2, Nippon Chemical Co., Ltd.) as a crosslinking aid, γ-methacryloxypropyltrime as a silane coupling agent 0.5 parts by weight of oxysilane (KBM-503, Shin-Etsu), 0.35 parts by weight of 2-hydroxy-4-n-octoxybenzophenone (Sumisorb 130, Sumitomo Chemical Co., Ltd.) as an ultraviolet absorber, and a phenolic compound (sumilizer GP, 0.01 parts by weight of Sumitomo Chemical Co., Ltd. was mixed at 25 ° C. for 30 minutes using a super mixer. This mixture was produced in a sheet having a thickness of 0.5 mm at a molding temperature of 150 ° C. using a single extruder (screw diameter 40 mm, L / D = 26, Oil Industry Co., Ltd.).

On the surface of the sheet, a solution containing 100 parts by weight of t-butyl peroxy-2-ethylhexyl carbonate (Lupenox TBEC, Alkema) as a crosslinking agent and 1500 parts by weight of isopropanol as an organic solvent was mixed using a dip coater. Coating for 60 seconds at the coating temperature. At this time, it coated with 1.5 weight part of t-butyl peroxy-2-ethylhexyl carbonate (Lupenox TBEC, Alchema) which is a crosslinking agent with respect to 100 weight part of ethylene-vinyl acetate copolymers (KA-40, TPC).

The coated sheet was dried in a drying furnace at 30 ° C. for 60 seconds.

The dried sheet was cooled in a drying furnace at 10 ° C. for 60 seconds to prepare an adhesive sheet.

Example 2

In the same manner as in Example 1, a sheet was produced at a molding temperature of 200 ° C.

Example 3

The same process as in Example 1, but was coated with a coating temperature of 40 ℃.

Example 4

The same process as in Example 1, but was dried at a temperature of 40 ℃.

Example 5

In the same manner as in Example 1, was coated using a solution containing 100 parts by weight of t-butyl peroxy-2-ethylhexyl carbonate (Lupenox TBEC, Alkema) as a crosslinking agent and 1000 parts by weight of isopropanol as an organic solvent. .

Comparative Example 1

100 parts by weight of ethylene-vinyl acetate copolymer (KA-40, TPC), 1.5 parts by weight of t-butyl peroxy-2-ethylhexyl carbonate (Lupenox TBEC, Alchema) as a crosslinking agent, triallyl isocyanur as a crosslinking aid 2 parts by weight of talate (TAIC 2, Nippon Chemical Co., Ltd.), 0.5 part by weight of γ-methacryloxypropyltrimethoxysilane (KBM-503, Shin-Etsu) as a silane coupling agent, 2-hydroxy-4-n- as an ultraviolet absorber. 0.35 parts by weight of octocibenzophenone (sumisorb 130, Sumitomo Chemical Co., Ltd.), 0.01 parts by weight of phenolic compound (sumilizer GP, Sumitomo Chemical Co., Ltd.) as an antioxidant was mixed at 25 ° C. for 30 minutes using a super mixer. The mixture was molded to a thickness of 0.5 mm at a molding temperature of 110 ° C. using a single extruder (screw diameter 40 mm, L / D = 26, Yusung Industrial Co., Ltd.) to prepare an adhesive sheet.

Comparative Example 2

100 parts by weight of ethylene-vinyl acetate copolymer (KA-40, TPC), 0.35 parts by weight of 2-hydroxy-4-n-octoxybenzophenone (sumisorb 130, Sumitomo Chemical Co., Ltd.) as an ultraviolet absorber, and a phenolic compound as an antioxidant (sumilizer GP, Sumitomo Chemical Co., Ltd.) 0.01 parts by weight was mixed for 30 minutes at 25 ℃ using a super mixer. This mixture was produced in a sheet having a thickness of 0.5 mm at a molding temperature of 150 ° C. using a single extruder (screw diameter 40 mm, L / D = 26, Oil Industry Co., Ltd.).

100 parts by weight of t-butyl peroxy-2-ethylhexyl carbonate (Lupenox TBEC, Alkema Co.) as a crosslinking agent on the surface of the prepared sheet, and 50 weights of triallyl isocyanurate (TAIC 2, Nippon Chemical Co., Ltd.) as a crosslinking aid. In addition, a solution in which 50 parts by weight of γ-methacryloxypropyltrimethoxysilane (KBM-503, Shin-Etsu) as a silane coupling agent and 1500 parts by weight of isopropanol in an organic solvent was mixed at a coating temperature of 30 ° C. using a dip coater. Coating for seconds

The coated sheet was dried in a drying furnace at 30 ° C. for 60 seconds.

The dried sheet was cooled in a drying furnace at 10 ° C. for 60 seconds to prepare an adhesive sheet.

Comparative Example 3

In the same manner as in Example 1, the coated sheet was dried for 60 seconds in a drying furnace of 60 ℃.

Comparative Example 4

In the same manner as in Example 1, the coated sheet was dried for 130 seconds in a drying furnace of 30 ℃.

Test Example

Physical properties of the adhesive sheets prepared in Examples and Comparative Examples were measured by the following method, and the results are shown in Table 1 below.

1. Shrinkage (%)

The prepared adhesive sheet was cut into rectangular pieces having a length of 35 cm x 10 cm in the length direction to prepare a specimen, and then the lengths of the lengthwise directions were accurately measured. The specimen was placed on a low iron tempered glass of the same size, heated at 155 ° C. for 3 minutes, crosslinked, and the length thereof was measured. Using the measured values, the shrinkage ratio was calculated by the following equation (1):

(Wherein L ₁ is the longitudinal length of the specimen before crosslinking and L ₂ is the longitudinal length of the specimen after crosslinking).

2. Adhesion

(1) adhesion to low iron tempered glass

Insert the adhesive sheet prepared between the low iron tempered glass used as the upper protective material for solar cells and polyethylene terephthalate (PET) film, and melt-bonded using a vacuum bonding machine at 150 ° C. for 20 minutes to form low iron tempered glass / adhesive sheet / PET A laminate of films was prepared. After peeling an adhesive sheet by hand from the low iron tempered glass of the manufactured laminated body, the state was visually observed and the adhesive force was evaluated.

(2) adhesion to the backsheet

Put the adhesive sheet prepared between the back sheet (TPT, SEC company) and PET film used as the lower protective material for solar cells and melt-bonded in the same manner as in the above (1) to obtain a laminate of the back sheet / adhesive sheet / PET film Prepared. After peeling the adhesive sheet by hand from the back sheet of the produced laminate, the adhesive strength was evaluated in the same manner as above.

<Evaluation Criteria>

○: The adhesive sheet does not peel off from the low iron tempered glass and the back sheet.

X: An adhesive sheet peels from one or more of low iron tempered glass or a back sheet.

3. Crosslinking degree ( Gel fraction ,%)

A laminated sheet of a release film / adhesive sheet / release film was prepared by putting the prepared adhesive sheet between two release films and melt bonding using a vacuum bonding machine. After removing the release film from the prepared laminate, the adhesive sheet was taken and put into 100 ml of xylene and heated at 110 ℃ for 24 hours. Subsequently, the insoluble fraction was filtered through a wire mesh of 25 mesh, and the filtered insoluble fraction was dried in a vacuum oven at 110 ° C. and weighed. The gel fraction was calculated by the following Equation 2 using the measured weight.

(W ₁ is the weight of the adhesive sheet taken, W ₂ is the weight of dried insoluble content).

4. Manufacture yield (%)

Based on one process line, the weight of the raw materials used in the molding of the adhesive sheet was measured, and the weight of the sheet except for the defect in the prepared adhesive sheet was measured. The gel fraction was calculated by the following Equation 3 using the measured weight.

(Wherein A is the weight of the raw material and B is the weight of the sheet excluding the defect).

division Shrinkage (%) Adhesion Degree of crosslinking (%) Manufacturing yield (%) Glass Backsheet Example 1 0.3 ○ ○ 84 97 Example 2 0.5 ○ ○ 87 96.5 Example 3 0.4 ○ ○ 85 98 Example 4 0.4 ○ ○ 86 96 Example 5 0.5 ○ ○ 85 95 Comparative Example 1 13.5 ○ ○ 84 85 Comparative Example 2 0.9 ○ × 79 79 Comparative Example 3 0.8 × ○ 83 88 Comparative Example 4 0.6 × × 71 79

As shown in Table 1, the adhesive sheets of Examples 1 to 5 prepared by the manufacturing method of the present invention can be manufactured without limitation in molding temperature compared to the adhesive sheets of Comparative Examples 1 to 4, so that the shrinkage is 1% or less. Although it was low, it was excellent in adhesive force and crosslinking degree. In addition, only a simple defect due to the adhesion of foreign matter, rather than a defect due to gelation, and the production yield is also higher than 90%, there was an advantage in terms of productivity and cost.

On the other hand, Comparative Example 1 in which a crosslinking agent was used when molding into a sheet as in the prior art was molded at a lower temperature than in Example, thereby minimizing thermal decomposition and gelation of the crosslinking agent, but a large shrinkage was observed. Example 2, Comparative Examples 3 and 4, respectively, in which the drying temperature and time were not within the scope of the present invention, were difficult to satisfy both the physical properties and the yield.

Claims (10)

Molding the mixture including the ethylenic copolymer and the additive to prepare a sheet;
Coating a crosslinking agent on the ethylene-based copolymer sheet; And
Drying the coated sheet at a temperature of 30 to 50 ° C. for 1 to 120 seconds,
The additive comprises a silane coupling agent, a crosslinking aid and a ultraviolet absorber,
The crosslinking agent is a method for producing a solar cell adhesive sheet that is mixed with an organic solvent.
delete delete The method of claim 1, wherein the molding is performed at a temperature of 80 to 220 ℃.
The method of claim 1, wherein the ethylene copolymer has a melt mass flow (MFR) of 20 to 40 g / 10 minutes.
delete The method of claim 1, wherein the coating is performed by a slit coating, slot coating, dip coating, spray coating, gravure coating, or squeeze coating method.
The method of claim 1, wherein the coating is performed for 1 to 120 seconds at a temperature of 30 to 40 ℃.
The method of claim 1, further comprising cooling the dried sheet after the drying step.
The method of claim 9, wherein the cooling is performed at a temperature of 10 to 20 ° C. for 1 to 120 seconds.

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