JP2016164228A - Resin sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin sheet capable of being used as an interlayer for glass laminate, an encapsulation material sheet for solar cell module or the like, capable of providing sufficient crosslinking speed, having suppressed foaming and excellent in PID property.SOLUTION: There is provided a resin sheet containing a copolymer (A) having a constitutional unit derived from ethylene and a constitutional unit derived from a (meth)acrylate monomer, at least one kind of crosslinking agent (B) selected from t-hexyl peroxy-based monocarbonate and t-amyl peroxy-based monocarbonate and a crosslinking assistant (C) with the crosslinking agent (B) of 0.2 to 0.5 pts.mass and the crosslinking assistant (C) of 0.5 to 1.5 pts.mass based on 100 pts.mass of the copolymer (A).SELECTED DRAWING: None

Description

  The present invention relates to a resin sheet.

  An interlayer film for laminated glass (hereinafter sometimes simply referred to as “intermediate film”) used for laminated glass in automobiles, railway vehicles, aircraft, ships, buildings, etc., a solar cell module sealing material sheet (hereinafter, Resin sheets are widely used as “sealant sheet”. In particular, the encapsulant sheet is a resin mainly composed of an ethylene-vinyl acetate copolymer (hereinafter referred to as “EVA”) that is excellent in transparency, processability, crosslinkability, and the like, and is flexible and excellent in the protection function of the power generation element. Sheets are widely used.

  However, EVA can be hydrolyzed to generate acetic acid under harsh environments such as high temperature and high humidity or high voltage, so that it is difficult to obtain excellent PID characteristics. Specifically, the generated acetic acid reduces the volume specific resistance value of the encapsulant sheet and causes the power generation element and the terminal to deteriorate. Therefore, when a sealing material sheet using EVA as a main component is used for a solar cell module, power generation efficiency tends to be reduced in a harsh environment.

  As a sealing material sheet using a resin other than EVA, a sealing material sheet using an ethylene-methyl methacrylate copolymer (EMMA) has been proposed (for example, Patent Documents 1 and 2). EMMA has performances such as flexibility, melting point, and transparency that are close to EVA, and functions to prevent the power generation elements of solar cell modules from coming into contact with the outside air and their functions to be reduced. It also has a buffering effect.

JP 2012-190878 A JP 2014-36182 A

  However, EMMA has poor crosslinkability as compared with EVA, and in the case of EVA, it is difficult to obtain a sufficient crosslinking rate with a crosslinking agent conventionally used. Therefore, in the resin sheet using EMMA, it is difficult to obtain excellent heat resistance that is particularly important in a solar cell module. Further, when a large amount of a crosslinking agent is used to increase the crosslinking rate, there is a problem that a foaming phenomenon due to a side reaction occurs and the appearance is deteriorated.

  The present invention provides a resin sheet that can be used as an interlayer film for laminated glass, a sealing material sheet for a solar cell module, and the like, has a sufficient crosslinking rate, suppresses foaming, and has excellent PID characteristics. With the goal.

In order to solve the above problems, the present invention employs the following configuration.
[1] From a copolymer (A) having a structural unit derived from ethylene and a structural unit derived from a (meth) acrylate monomer, t-hexyl peroxy monocarbonate, and t-amyl peroxy monocarbonate It contains at least one crosslinking agent (B) selected from the group consisting of, and a crosslinking aid (C). The resin sheet which is 2-0.5 mass part and whose said crosslinking adjuvant (C) is 0.5-1.5 mass part.
[2] The resin sheet according to [1], which is a sealing material sheet for a solar cell module.
[3] The resin sheet according to [1], which is an interlayer film for laminated glass.

  The resin sheet of the present invention can be used as an interlayer film for laminated glass, a sealing material sheet for a solar cell module, and the like, a sufficient crosslinking rate is obtained, foaming is suppressed, and the PID characteristics are excellent.

  The resin sheet of this invention contains the copolymer (A) mentioned later, a crosslinking agent (B), and a crosslinking adjuvant (C). Moreover, the resin sheet of this invention may contain an additive (D) as needed.

[Copolymer (A)]
The copolymer (A) is a copolymer having a structural unit derived from ethylene and a structural unit derived from a (meth) acrylate monomer. The copolymer (A) does not generate acetic acid due to a hydrolysis reaction even in a dump heat test (temperature / humidity test) or a high voltage load test. Therefore, excellent PID characteristics can be obtained by using the copolymer (A).

  The (meth) acrylate monomer is a monomer composed of an ester of acrylic acid or methacrylic acid. Examples of (meth) acrylate monomers include methyl methacrylate (MMA), methyl acrylate, ethyl acrylate, butyl acrylate, and the like.

Specific examples of the copolymer (A) include, for example, ethylene-methyl methacrylate copolymer (EMMA), ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-butyl acrylate copolymer, and the like. Can be mentioned. Among these, EMMA is preferable from the viewpoint of transparency.
A copolymer (A) may be used individually by 1 type, and may use 2 or more types together.

  15-35 mass% is preferable with respect to all the structural units, and, as for the ratio of the structural unit derived from the (meth) acrylate type monomer in a copolymer (A), 20-30 mass% is more preferable.

The melting point of the copolymer (A) is preferably 60 to 100 ° C. If the melting point of the copolymer (A) is at least the lower limit, it is easy to ensure basic performance as an intermediate film or a sealing material sheet. If the melting point of the copolymer (A) is not more than the upper limit value, it is easy to suppress the generation of bubbles.
The melting point is measured by differential thermal analysis.
The melting point of the copolymer (A) can be adjusted, for example, by adjusting the crystallinity of the copolymer (A). The higher the crystallinity of the copolymer (A), the higher the melting point of the copolymer (A).

The melt mass flow rate (hereinafter referred to as “MFR”) of the copolymer (A) is preferably 5 to 40 g / 10 min, and more preferably 5 to 30 g / min. If MFR of a copolymer (A) is more than a lower limit, it is excellent in workability. If MFR of a copolymer (A) is below an upper limit, it will be easy to ensure the basic performance as an intermediate film or a sealing material sheet.
The MFR is a value measured under conditions of a temperature of 190 ° C. and a load of 21.18 N in accordance with JIS K6924-2: 1997.

[Crosslinking agent (B)]
The crosslinking agent (B) is at least one crosslinking agent selected from the group consisting of t-hexyl peroxy monocarbonate and t-amyl peroxy monocarbonate.
The t-hexylperoxy monocarbonate is a compound having a t-hexylperoxy group and one carbonate group. Examples of the t-hexyl peroxy monocarbonate include t-hexyl peroxy isopropyl monocarbonate.
The t-amyl peroxy monocarbonate is a compound having a t-amyl peroxy group and one carbonate group. Examples of the t-amyl peroxy monocarbonate include t-amyl peroxyisopropyl carbonate, t-amyl peroxy-2-ethylhexyl carbonate, and the like.
A crosslinking agent (B) may be used individually by 1 type, and may use 2 or more types together.

  Content of the crosslinking agent (B) in a resin sheet is 0.2-0.5 mass part with respect to 100 mass parts of copolymers (A), and 0.3-0.5 mass part is preferable. If the content of the crosslinking agent (B) is at least the lower limit value, a sufficient crosslinking rate can be obtained. If content of a crosslinking agent (B) is below an upper limit, it can suppress that foaming arises. Moreover, if content of a crosslinking agent (B) is in the said range, the outstanding PID characteristic will be acquired.

[Crosslinking aid (C)]
The crosslinking aid (C) is a compound having two or more polymerizable unsaturated groups (vinyl group, allyl group, (meth) acryloxy group, isocyanate group, etc.).
Examples of the crosslinking aid (C) include triallyl isocyanurate, triallyl cyanurate, trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, and the like.
As the crosslinking aid (C), one type may be used alone, or two or more types may be used in combination.

  Content of the crosslinking adjuvant (C) in a resin sheet is 0.5-1.5 mass parts with respect to 100 mass parts of copolymers (A), and 0.6-1.0 mass part is preferable. . If the content of the crosslinking aid (C) is at least the lower limit value, a sufficient crosslinking rate can be obtained. If content of a crosslinking adjuvant (C) is below an upper limit, sufficient crosslinking rate will be obtained and it can suppress that foaming arises.

[Additive (D)]
As the additive (D), a known additive used for an interlayer film or a sealing material sheet can be used without limitation. For example, a weathering agent, an antioxidant, an adhesion assistant, a discoloration preventing agent, a pigment, a filler, etc. Is mentioned.
An additive (D) may be used individually by 1 type, and may use 2 or more types together.

Examples of the weathering agent include light stabilizers such as hindered amine light stabilizers, ultraviolet absorbers such as benzophenone ultraviolet absorbers, benzotriazole ultraviolet absorbers, and salicylic acid ester ultraviolet absorbers.
Examples of the antioxidant include hindered phenol antioxidants and phosphite antioxidants.
Examples of the adhesion assistant include vinyltriethoxysilane, vinyltris (2-methoxyethoxy) silane, 3-methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, N-2- (aminoethyl)- Examples include 3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-aminopropyltriethoxysilane, and 3-mercaptopropyltrimethoxysilane.

  0.1-3.0 mm is preferable and, as for the thickness of the resin sheet of this invention, 0.4-1.0 mm is more preferable. If the thickness of the resin sheet is equal to or greater than the lower limit, the ultraviolet shielding property is excellent. If the thickness of the resin sheet is less than or equal to the upper limit value, the workability during processing is excellent.

[Production method]
The method for producing the resin sheet of the present invention is not particularly limited, and for example, a copolymer (A), a crosslinking agent (B), a crosslinking aid (C), and an additive (D) used as necessary are kneaded. Then, after obtaining the resin composition, a method of forming the resin composition into a sheet and the like can be mentioned.

Examples of the kneading method include a method using an extruder, a ribbon blender, a plastograph, a kneader, a Banbury mixer, a calendar roll, and the like.
Examples of the sheet forming method include an extrusion molding method using a T die, a press molding method, and the like. Moreover, when making a resin composition into a solution, it can also be formed into a sheet by applying the resin composition to a release sheet and drying.

[Usage]
The use of the resin sheet of the present invention is not particularly limited, and a solar cell module sealing material sheet or a laminated glass interlayer film is preferable.
In the solar cell module using the resin sheet of the present invention as a sealing material sheet, a known configuration can be adopted except that the resin sheet of the present invention is used. For example, a solar cell module having a laminated structure such as a sealing material layer / back sheet containing glass plates / cells, and using the resin sheet of the present invention as a sealing material sheet for forming the sealing material layer is mentioned. It is done.

  In the laminated glass using the resin sheet of the present invention as an intermediate film, a known configuration can be adopted except that the resin sheet of the present invention is used. For example, the resin sheet of the present invention has a laminated structure of glass plate / first intermediate film / PET film / second intermediate film / glass plate, and either or both of the first intermediate film and the second intermediate film. Laminated glass using is used. In this case, it is preferable to use the resin sheet of the present invention for both the first intermediate film and the second intermediate film. Moreover, it is good also as laminated glass which has a laminated structure of a glass plate / intermediate film / glass plate, and uses the resin sheet of this invention for this intermediate film.

[Function and effect]
As described above, in the encapsulant sheet using EVA, there is a problem that the PID characteristic is lowered by acetic acid generated by hydrolysis of EVA. Moreover, in the sealing material sheet using conventional EMMA such as Patent Documents 1 and 2, it is difficult to obtain a sufficient cross-linking speed, so that it is difficult to obtain excellent heat resistance, and foaming occurs when the amount of the cross-linking agent is increased. There's a problem. As one of the causes of the foaming phenomenon, carbon dioxide gas may be generated by a side reaction of the crosslinking agent.

  On the other hand, in the resin sheet of the present invention, since the copolymer (A) is used, the performance such as flexibility, melting point and transparency is almost the same as EVA and acetic acid is generated by hydrolysis reaction. Therefore, excellent PID characteristics can be obtained. Moreover, with respect to the copolymer (A), by using a specific crosslinking agent (B), which is a monocarbonate-based crosslinking agent that does not generate carbon dioxide gas, and a crosslinking aid (C) in a specific ratio, A sufficient crosslinking rate can be obtained, and foaming can be suppressed.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited by the following description.
[Crosslinking time T90]
The encapsulant sheet of each example was crosslinked at a crosslinking setting temperature of 150 ° C. with a curast meter manufactured by JSR, and the time to reach 90% of the maximum torque was measured as the crosslinking time T90. Those having a crosslinking time T90 within 720 seconds were designated as “◯ (passed)”, and those exceeding 720 seconds were designated as “x (failed)”.

[Foaming test]
Using the sealing material sheet of each example, white wrinkled glass (3.2 mm thickness) / sealing material sheet / power generating element fixing tape / sealing material sheet / back sheet (0.25 mm thickness) are laminated in this order. A test piece was obtained. Next, the test piece was deaerated with a laminator for 3 minutes and then fixed by heating at a press pressure of 100 kPa and a press time of 3 minutes, and then heated in an oven at 150 ° C. for 30 minutes for crosslinking. After the obtained test piece was further heated for 2 hours, the presence or absence of foaming due to outgas in the sealing layer was confirmed. Those with no foaming were designated as “◯ (passed)”, and those with foaming were designated as “x (failed)”.

[PID test]
Using the sealing material sheet of each example, white grain glass (3.2 mm thickness) / sealing material sheet / power generation element / sealing material sheet / back sheet (0.25 mm thickness) was laminated in this order. Next, the laminate was degassed with a laminator for 3 minutes, and then heat-fixed at a press pressure of 100 kPa and a press time of 3 minutes, and then heated in an oven at 150 ° C. for 30 minutes to be crosslinked to obtain a solar cell module. Next, the obtained solar cell module was subjected to a PID test in which a high voltage load of 1000 V was applied for 700 hours under a room temperature environment, and the rate of decrease in power generation efficiency after the test relative to the power generation efficiency before the test was measured. The power generation efficiency was measured with a solar simulator. Those with a decrease rate of 2% or less were evaluated as “◯ (passed)”, and those with a reduction rate exceeding 2% were determined as “× (failed)”.

[Raw materials]
The raw materials used in this example are shown below.
(Copolymer (A))
Copolymer A1: EMMA (product name “Aclift”, manufactured by Sumitomo Chemical Co., Ltd., proportion of structural units derived from MMA: 25 mass%, MFR: 7 g / min, melting point: 80 ° C.).

(Copolymer (X) (Comparison))
Copolymer X: EVA (product name “DQDJ-3269”, manufactured by Nippon Unicar Co., Ltd., proportion of structural units derived from vinyl acetate: 28% by mass, MFR: 20 g / min, melting point: 69 ° C.).

(Crosslinking agent (B))
Cross-linking agent B1: t-hexyl peroxyisopropyl monocarbonate (product name “Perhexyl I”, manufactured by NOF Corporation).
Cross-linking agent B2: t-amyl peroxyisopropyl carbonate (product name “Lupelox TAIC”, manufactured by Arkema Yoshitomi).
Cross-linking agent B3: t-amylperoxy-2-ethylhexyl carbonate (product name “Lupelox TAEC”, manufactured by Arkema Yoshitomi).

(Crosslinking agent (Y) (Comparison target))
Crosslinking agent Y: 2,5-dimethyl-2,5-di (t-butylperoxy) hexane (product name “Kayahexa AD”, manufactured by Kayaku Akzo Corporation).

(Crosslinking aid (C))
Crosslinking aid C1: triallyl isocyanurate (product name “TAIC (registered trademark)”, manufactured by Nippon Kasei Co., Ltd.).

(Additive (D))
Adhesion aid D1: 3-methacryloxypropyltrimethoxysilane (product name “KBM-503”, manufactured by Shin-Etsu Silicone).
Weathering agent D2: 2-hydroxy-4-n-octyloxybenzophenone (product name “Chemisorb 81”, manufactured by BASF Japan Ltd.).

[Example 1]
100 parts by weight of copolymer A1, 0.2 parts by weight of crosslinking agent B1, 0.5 parts by weight of crosslinking aid C1, 0.25 parts by weight of adhesion assistant D1, and 0 of weathering agent D2. .35 parts by mass was kneaded with a ribbon blender and extruded using a single screw extruder equipped with a T die to obtain a sealing material sheet having a thickness of 0.5 mm.

[Example 2]
A sealing material sheet was obtained in the same manner as in Example 1 except that the amount of the crosslinking agent B1 was changed to 0.3 parts by mass.

[Example 3]
A sealing material sheet was obtained in the same manner as in Example 1 except that the amount of the crosslinking agent B1 was changed to 0.3 parts by mass and the amount of the crosslinking assistant C1 was changed to 1.5 parts by mass.

[Example 4]
A sealing material sheet was obtained in the same manner as in Example 1 except that the amount of the crosslinking agent B1 was changed to 0.5 parts by mass and the amount of the crosslinking assistant C1 was changed to 1.0 parts by mass.

[Example 5]
A sealing material sheet was obtained in the same manner as in Example 1 except that 0.3 parts by mass of the crosslinking agent B2 was used instead of the crosslinking agent B1.

[Example 6]
A sealing material sheet was obtained in the same manner as in Example 1 except that 0.5 parts by mass of the crosslinking agent B2 was used instead of the crosslinking agent B1 and the amount of the crosslinking assistant C1 was changed to 1.0 part by mass. .

[Example 7]
A sealing material sheet was obtained in the same manner as in Example 1 except that 0.3 parts by mass of the crosslinking agent B3 was used instead of the crosslinking agent B1.

[Example 8]
A sealing material sheet was obtained in the same manner as in Example 1 except that 0.5 parts by mass of the crosslinking agent B3 was used instead of the crosslinking agent B1, and the amount of the crosslinking assistant C1 was changed to 1.0 part by mass. .

[Comparative Example 1]
A sealing material sheet was obtained in the same manner as in Example 1 except that the amount of the crosslinking agent B1 was changed to 0.1 parts by mass.

[Comparative Example 2]
A sealing material sheet was obtained in the same manner as in Example 1 except that the amount of the crosslinking agent B1 was changed to 0.7 parts by mass and the amount of the crosslinking assistant C1 was changed to 1.0 parts by mass.

[Comparative Example 3]
A sealing material sheet was obtained in the same manner as in Example 1 except that the amount of the crosslinking agent B1 was changed to 0.3 parts by mass and the amount of the crosslinking assistant C1 was changed to 2.0 parts by mass.

[Comparative Example 4]
A sealing material sheet was obtained in the same manner as in Example 1 except that the crosslinking agent Y was used instead of the crosslinking agent B1.

[Comparative Example 5]
A sealing material sheet was obtained in the same manner as in Example 1 except that 0.5 parts by mass of the crosslinking agent Y was used instead of the crosslinking agent B1 and the amount of the crosslinking aid C1 was changed to 1.0 part by mass. .

[Comparative Example 6]
A sealing material sheet was obtained in the same manner as in Example 1 except that 0.8 parts by mass of the crosslinking agent Y was used instead of the crosslinking agent B1 and the amount of the crosslinking assistant C1 was changed to 1.5 parts by mass. .

[Comparative Example 7]
A sealing material sheet was obtained in the same manner as in Example 1 except that the copolymer X was used instead of the copolymer A1, and the crosslinking agent Y was used instead of the crosslinking agent B1.

[Comparative Example 8]
Example except that copolymer X was used in place of copolymer A1, 0.5 parts by mass of crosslinking agent Y was used in place of crosslinking agent B1, and 1.0 part by mass of crosslinking aid C1 was used. In the same manner as in Example 1, a sealing material sheet was obtained.

  Tables 1 and 2 show the compositions and evaluation results of the sealing material sheets of Examples 1 to 8 and Comparative Examples 1 to 8.

As shown in Table 1 and Table 2, in the sealing material sheets of Examples 1 to 8, the crosslinking rate was sufficiently high, foaming was suppressed, and the PID characteristics were also excellent.
In the sealing material sheet of Comparative Example 1 having a small amount of the crosslinking agent B1, a sufficient crosslinking rate was not obtained and the PID characteristics were inferior. In the sealing material sheet of Comparative Example 2 having a large amount of the crosslinking agent B1, foaming was observed in the sealing layer, and the PID characteristics were inferior. In the sealing material sheet of Comparative Example 3 having a large amount of the crosslinking assistant C1, foaming was observed in the sealing layer.
In the sealing material sheets of Comparative Examples 4 to 6 using the crosslinking agent Y instead of the crosslinking agent B1, a sufficient crosslinking rate was not obtained. In Comparative Examples 4 and 5, the PID characteristics were inferior, and in Comparative Example 6, foaming was observed in the sealing layer.
In Comparative Examples 7 and 8 using the copolymer X (EVA) instead of the copolymer A1 (EMMA), a sufficient crosslinking rate was obtained even when the crosslinking agent Y was used, but the PID characteristics were inferior. .

Claims (3)

From the group consisting of a copolymer (A) having a structural unit derived from ethylene and a structural unit derived from a (meth) acrylate monomer, t-hexyl peroxy monocarbonate, and t-amyl peroxy monocarbonate Containing at least one selected crosslinking agent (B) and crosslinking aid (C),
The crosslinking agent (B) is 0.2 to 0.5 parts by mass and the crosslinking aid (C) is 0.5 to 1.5 parts by mass with respect to 100 parts by mass of the copolymer (A). A resin sheet.   The resin sheet according to claim 1, which is a solar cell module sealing material sheet.   The resin sheet according to claim 1, which is an interlayer film for laminated glass.