WO2015182546A1

WO2015182546A1 - Polyester resin composition, master pellet, polyester film, back sheet for solar cell module, and solar cell module

Info

Publication number: WO2015182546A1
Application number: PCT/JP2015/064890
Authority: WO
Inventors: 福田　誠; 上平　茂生; 圭原田; 山▲崎▼　一樹; 倫弘小川
Original assignee: 富士フイルム株式会社
Priority date: 2014-05-30
Filing date: 2015-05-25
Publication date: 2015-12-03
Also published as: JP6341998B2; JPWO2015182546A1

Abstract

The present invention addresses the problem of providing a polyester film having a good surface state and being provided with both hydrolysis resistance and visible-light shielding properties, and suppressing the formation of irritant gas in the manufacturing process. The present invention relates to a polyester resin composition including a compound represented by general formula (1), a pigment, and a polyester. The present invention further relates to a master pellet, a polyester film, a back sheet for a solar cell module, and a solar cell module. In general formula (1), R² represents an alkyl group which may have a substituent, a cycloalkyl group which may have a substituent, an aryl group which may have a substituent, or an alkoxy group which may have a substituent, R³ represents a specific alkyl group or a specific aryl group, and R¹¹, R¹², and R¹³ each independently represent a hydrogen atom, an alkyl group which may have a substituent, or an aryl group which may have a substituent.

Description

Polyester resin composition, master pellet, polyester film, solar cell module back sheet and solar cell module

The present invention relates to a polyester resin composition containing an imino ether compound, a master pellet formed using the polyester resin composition, and a polyester film. Furthermore, this invention relates to a solar cell module provided with the backsheet for solar cell modules which has a polyester film, and a backsheet for solar cell modules.

A solar cell module generally has a structure in which glass or a front sheet / transparent filling material (sealing material) / solar cell element / sealing material / back sheet are laminated in this order from the light-receiving surface side where sunlight enters. is doing. Specifically, a solar cell element is generally structured to be embedded in a resin (sealing material) such as EVA (ethylene-vinyl acetate copolymer) and further to a solar cell protective sheet. The The protection sheet for solar cells, particularly the back sheet for the solar cell module, which is the outermost layer, is supposed to be placed in an environment where it is exposed to outdoor wind and rain, direct sunlight, etc. for a long period of time. Therefore, excellent weather resistance (moisture and heat resistance, heat resistance) is required.

Conventionally, a polyester film, particularly a polyethylene terephthalate (hereinafter referred to as PET) film has been used for a back sheet for a solar cell module. Polyester films are widely used industrially because they have excellent heat resistance, mechanical properties, chemical resistance, and the like. In addition, a white polyester film to which a white pigment is added may be used for the solar cell module backsheet in order to increase concealability and sunlight reflectance (Patent Documents 1 and 2).

However, since the polyester film has poor hydrolysis resistance, the molecular weight decreases due to hydrolysis, and embrittlement progresses, resulting in a decrease in mechanical properties. For this reason, practical strength could not be maintained over a long period of time as a back sheet for solar cells.

As a method for suppressing hydrolysis of a polyester film, a method of sealing carboxylic acid remaining at the terminal of polyester is known. Examples of the terminal blocking agent that seals the carboxylic acid remaining at the terminal of the polyester include a carbodiimide compound or a cyclic imino ether compound. For example, Patent Document 3 discloses a polyester film containing a carbodiimide compound or a cyclic imino ether compound. In this document, it is proposed to improve the dimensional stability and hydrolysis resistance of a polyester by reacting a carbodiimide compound and a cyclic imino ether compound with a carboxylic acid at the terminal of the polyester. In Patent Document 3, an oxazoline compound or an oxazine compound is used as the cyclic imino ether compound.

International Publication WO2010 / 113920 Japanese Patent No. 5288068 JP 2010-31174 A

In Patent Documents 1 and 2, the concealability and reflectance of visible light can be increased by mixing a white pigment with a polyester film. In Patent Documents 1 and 2, it is also studied to increase the hydrolysis resistance of the white polyester film by adjusting the layer structure and the amount of white pigment added. However, the inventors have found that the polyester films disclosed in Patent Documents 1 and 2 have insufficient hydrolysis resistance. Furthermore, in the polyester film to which the white pigment is added, hydrolysis tends to proceed more easily than the polyester film to which the white pigment is not added, and it is the present inventors that the conventional method cannot sufficiently suppress hydrolysis. It became clear by examination.

In order to suppress hydrolysis of the polyester film, as described in Patent Document 3, it has been studied to add a terminal blocking agent. However, when the carbodiimide compound described in Patent Document 3 is used, there is a problem that free isocyanate is volatilized. Since such a volatilizing gas is an irritating gas, it has been desired that the volatilization be suppressed.

It is conceivable to use a cyclic imino ether compound as an end-capping agent that is considered to generate little volatilization gas. However, the cyclic imino ether compound is known to self-polymerize, and it has been clarified by the present inventors that the self-polymerized cyclic imino ether compound exists as a gel component in the polyester resin. Such a gel component raises the viscosity of the polyester resin, which causes a problem of deteriorating the surface state of the polyester film.

Therefore, in order to solve such problems of the prior art, the present inventors have proceeded with a study for the purpose of providing a polyester film having both hydrolysis resistance and visible light hiding property. In addition, the inventors of the present invention have studied for the purpose of suppressing the generation of irritating gas in the production process of a polyester film having both hydrolysis resistance and visible light hiding property. Furthermore, the inventors of the present invention have studied in the production process of the polyester film for the purpose of suppressing the increase in the viscosity of the polyester resin composition and providing a polyester film having a good surface shape.

As a result of intensive studies to solve the above problems, the present inventors have used an imino ether compound having a specific structure as an end-capping agent, and by adding a pigment, the hydrolysis resistance of the polyester film It was found that both the visible light concealment property can be improved. Furthermore, it has been found that by using an imino ether compound having a specific structure as an end-capping agent, generation of an irritating gas in the production process of a polyester film can be suppressed, and a polyester film having a good film surface shape can be obtained. It was.
Specifically, the present invention has the following configuration.

[1] A polyester resin composition comprising a compound represented by the following general formula (1), a pigment, and a polyester;

In general formula (1), R ² has an alkyl group which may have a substituent, a cycloalkyl group which may have a substituent, an aryl group which may have a substituent, or a substituent. R ³ represents an alkyl group represented by the following general formula (2) or an aryl group represented by the following general formula (3), and R ¹¹ , R ¹² and R ¹³ are each independently Represents a hydrogen atom, an alkyl group which may have a substituent, or an aryl group which may have a substituent. R ² , R ³ , R ¹¹ , R ¹² and R ¹³ may be bonded to each other to form a ring. However, when R ³ is represented by the following general formula (2), the bond formed by at least one of R ¹¹ to R ¹³ and at least one of R ³¹ to R ³³ is a bond having two or more linking atoms.

In the general formula (2), R ³¹ , R ³² and R ³³ each independently represent a hydrogen atom or a substituent. R ³¹ , R ³² and R ³³ may be connected to each other to form a ring. In General Formula (3), R ⁴¹ represents a substituent, and when a plurality of R ⁴¹ are present, they may be the same or different. N represents an integer of 0 to 5. In general formulas (2) and (3), * represents a position bonded to a nitrogen atom.
[2] The polyester resin composition according to [1], containing 0.05 to 35% by mass of the compound represented by the general formula (1) with respect to the total mass of the polyester resin composition.
[3] The polyester resin composition according to [1] or [2], which contains 0.2 to 50% by mass of pigment with respect to the total mass of the polyester resin composition.
[4] The polyester resin composition according to any one of [1] to [3], wherein the compound is represented by the following general formula (4);

In general formula (4), R ² has an alkyl group which may have a substituent, a cycloalkyl group which may have a substituent, an aryl group which may have a substituent, or a substituent. R ¹¹ , R ¹² and R ¹³ each independently represents a hydrogen atom, an alkyl group which may have a substituent, or an aryl group which may have a substituent. R ⁴¹ represents a substituent, and when a plurality of R ⁴¹ are present, they may be the same or different. n represents an integer of 0 to 5.
[5] The polyester resin composition according to any one of [1] to [4], wherein the compound is represented by the following general formula (5):

In general formula (5), R ¹¹ , R ¹² and R ¹³ each independently represent a hydrogen atom, an alkyl group which may have a substituent, or an aryl group which may have a substituent. R ²¹ and R ⁴¹ each independently represent a substituent. When a plurality of R ²¹ and R ⁴¹ are present, they may be the same or different. n represents an integer of 0 to 5, and m represents an integer of 0 to 5.
[6] The polyester resin composition according to any one of [1] to [5], wherein the compound is represented by the following general formula (6):

In General Formula (6), R ¹¹ , R ¹² and R ¹³ each independently represent a hydrogen atom, an alkyl group which may have a substituent, or an aryl group which may have a substituent. R ⁴¹ represents a substituent, and when a plurality of R ⁴¹ are present, they may be the same or different. n represents an integer of 0 to 5. P represents an integer of 2 to 4, and L ¹ represents an alkylene part which may have a substituent, a cycloalkylene part which may have a substituent, or a substituent at the bond terminal to the carbon atom. The p-valent group which is the arylene part which may have or the alkoxylene part which may have a substituent is represented.
[7] The polyester resin composition according to any one of [1] to [6], wherein the compound is represented by the following general formula (7);

In general formula (7), R ² has an alkyl group that may have a substituent, a cycloalkyl group that may have a substituent, an aryl group that may have a substituent, or a substituent. R ¹¹ , R ¹² and R ¹³ each independently represents a hydrogen atom, an alkyl group which may have a substituent, or an aryl group which may have a substituent. P represents an integer of 2 to 4, and L ² represents an arylene moiety that may have a substituent, or a cycloalkylene moiety that may have a substituent, at the bond terminal to the nitrogen atom. Represents a p-valent group.
[8] The polyester resin composition according to any one of [1] to [7], wherein the compound is represented by the following general formula (8);

In general formula (8), R ² has an alkyl group which may have a substituent, a cycloalkyl group which may have a substituent, an aryl group which may have a substituent, or a substituent. R ⁴¹ represents a substituent, and when a plurality of R ⁴¹ are present, they may be the same or different. n represents an integer of 0 to 5. P represents an integer of 2 to 4, and L ³ represents a p-valent group in which the bond terminal to the oxygen atom is an alkylene part. However, in the alkylene part of L ³ , part or all of the hydrogen atoms may be substituted with an alkyl group which may have a substituent or an aryl group which may have a substituent.
[9] The polyester resin composition according to any one of [1] to [8], wherein the pigment is a white pigment.
[10] The polyester resin composition according to any one of [1] to [9], wherein the pigment is titanium oxide.
[11] A master pellet formed using the polyester resin composition according to any one of [1] to [10].
[12] A polyester film formed using the polyester resin composition according to any one of [1] to [10].
[13] The polyester film according to [12], containing 0.1 to 2% by mass of the compound represented by the general formula (1) with respect to the total mass of the polyester film.
[14] The polyester film according to [12] or [13], which contains 0.5 to 10% by mass of pigment with respect to the total mass of the polyester film.
[15] The polyester film according to any one of [12] to [14], which is a biaxially oriented film.
[16] A back sheet for a solar cell module using the polyester film according to any one of [12] to [15].
[17] A solar cell module comprising the solar cell module backsheet according to [16].

According to the present invention, a polyester film having both hydrolysis resistance and visible light hiding property can be provided. Moreover, according to this invention, generation | occurrence | production of stimulating gas can be suppressed in the manufacturing process of the polyester film which has both hydrolysis resistance and visible-light concealment property. Furthermore, according to this invention, even if it contains a terminal blocker, the viscosity of the polyester resin is not increased, and a polyester film having a good film surface shape can be obtained.

Hereinafter, the present invention will be described in detail. The description of the constituent elements described below may be made based on representative embodiments and specific examples, but the present invention is not limited to such embodiments. In the present specification, a numerical range expressed using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

(Imino ether compound)
The imino ether compound used in the present invention is represented by the following general formula (1).

In the general formula (2), R ³¹ , R ³² and R ³³ each independently represent a hydrogen atom or a substituent. R ³¹ , R ³² and R ³³ may be connected to each other to form a ring. In General Formula (3), R ⁴¹ represents a substituent, and when a plurality of R ⁴¹ are present, they may be the same or different. N represents an integer of 0 to 5. In general formulas (2) and (3), * represents a position bonded to a nitrogen atom.

In the general formula (1), the alkyl group represented by R ² is preferably an alkyl group having 1 to 20 carbon atoms, and more preferably an alkyl group having 1 to 12 carbon atoms. The alkyl group represented by R ² may be linear or branched. Further, the alkyl group represented by R ² may be a cycloalkyl group. Examples of the alkyl group represented by R ² include methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, tert-butyl group, sec-butyl group, iso-butyl group, n-pentyl group, Examples thereof include a sec-pentyl group, an iso-pentyl group, an n-hexyl group, a sec-hexyl group, an iso-hexyl group, and a cyclohexyl group. Of these, a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, an iso-butyl group, and a cyclohexyl group are more preferable.
The alkyl group represented by R ² may further have a substituent. Examples of the substituent include the alkyl group, aryl group, alkoxy group, halogen atom, nitro group, amide group, hydroxyl group, ester group, ether group, and aldehyde group. The number of carbon atoms of the alkyl group represented by R ² may indicate the number of carbon that does not contain a substituent group.

The aryl group represented by R ² is preferably an aryl group having 6 to 20 carbon atoms, and more preferably an aryl group having 6 to 12 carbon atoms. Examples of the aryl group represented by R ² include a phenyl group and a naphthyl group, and among them, a phenyl group is particularly preferable. The aryl group represented by R ² may further have a substituent. In addition, as said substituent, said substituent can be illustrated similarly, However, As long as reaction of an imino ether group and a carboxyl group can be advanced, a substituent in particular is not restrict | limited. The number of carbon atoms of the aryl group represented by R ² is the number of carbon atoms not including a substituent.

The alkoxy group represented by R ² is preferably an alkoxy group having 1 to 20 carbon atoms, more preferably an alkoxy group having 1 to 12 carbon atoms, and an alkoxy group having 2 to 6 carbon atoms. Is particularly preferred. The alkoxy group represented by R ² may be linear, branched or cyclic. Preferable examples of the alkoxy group represented by R ² include a group in which —O— is linked to the terminal of the alkyl group represented by R ² . The alkoxy group represented by R ² may further have a substituent. In addition, as said substituent, said substituent can be illustrated similarly, However, As long as reaction of an imino ether group and a carboxyl group can be advanced, a substituent in particular is not restrict | limited. The number of carbon atoms of the alkoxy group represented by R ^2, indicate the number of carbon that does not contain a substituent group.

R ³ represents an alkyl group represented by the general formula (2) or an aryl group represented by the general formula (3). In the general formula (2), R ³¹ , R ³² and R ³³ each independently represent a hydrogen atom or a substituent. When R ³¹ , R ³² and R ³³ are substituents, they may be linked to each other to form a ring. Examples of the substituent include the alkyl group, aryl group, alkoxy group, halogen atom, nitro group, amide group, hydroxyl group, ester group, ether group, and aldehyde group. R ³¹ , R ³² and R ³³ may be all hydrogen atoms or the same substituent or different substituents. Further, the alkyl group represented by the general formula (2) may be linear or branched. Further, the alkyl group represented by the general formula (2) may be a cycloalkyl group.
In the general formula (3), R ⁴¹ represents a substituent, and n represents an integer of 0 to 5. When n is 2 or more, R ⁴¹ may be the same or different. In addition, as a substituent, said substituent can be illustrated similarly. N is more preferably from 0 to 3, and further preferably from 0 to 2.

R ¹¹ , R ¹² and R ¹³ each independently represent a hydrogen atom, an alkyl group which may have a substituent, or an aryl group which may have a substituent. The alkyl group and aryl group can be exemplified similarly an alkyl group and aryl group R ² can be taken.

R ² , R ³ , R ¹¹ , R ¹² and R ¹³ are preferably not bonded to form a ring, but R ² , R ³ , R ¹¹ , R ¹² and R ¹³ are bonded to each other to form a ring. May be. For example, when R ³ is represented by the above general formula (3), R ⁴¹ and at least one of R ¹¹ to R ¹³ may combine to form a ring, and a benzene ring and R ¹¹ to R ¹³ A ring containing any of the above may form a condensed ring. When R ³ is represented by the general formula (3), it is preferable that R ⁴¹ and at least one of R ¹¹ to R ¹³ are not bonded to form a ring.
However, when R ³ is represented by the general formula (2), the bond formed by at least one of R ¹¹ to R ¹³ and at least one of R ³¹ to R ³³ is a bond having two or more linking atoms. When R ³ is represented by the above general formula (2), the bond formed by one of R ¹¹ to R ¹³ and one of R ³¹ to R ³³ is a bond having two or more linking atoms, and a double bond A bond is preferred. When R ³ is represented by the general formula (2), it is preferable that at least one of R ¹¹ to R ¹³ and at least one of R ³¹ to R ³³ are not bonded to form a ring.

General formula (1) may include a repeating unit. In this case, at least one of R ² , R ³ or R ¹¹ to R ¹³ is a repeating unit, and this repeating unit preferably includes an imino ether part.

In addition, the imino ether compound used in the present invention is preferably represented by the following general formula (4).

In general formula (4), R ² has an alkyl group which may have a substituent, a cycloalkyl group which may have a substituent, an aryl group which may have a substituent, or a substituent. R ¹¹ , R ¹² and R ¹³ each independently represents a hydrogen atom, an alkyl group which may have a substituent, or an aryl group which may have a substituent. R ⁴¹ represents a substituent, and when a plurality of R ⁴¹ are present, they may be the same or different. n represents an integer of 0 to 5.

In the general formula (4), R ² , R ¹¹ , R ¹² and R ¹³ are the same as those in the general formula (1), and preferred ranges are also the same. Moreover, in General formula (4), ^R41 is the same as that in General formula (3), and its preferable range is also the same. N is preferably 0 to 3, more preferably 0 to 2.

The imino ether compound used in the present invention is preferably represented by the following general formula (5).

In general formula (5), R ¹¹ , R ¹² and R ¹³ each independently represent a hydrogen atom, an alkyl group which may have a substituent, or an aryl group which may have a substituent. R ²¹ and R ⁴¹ each independently represent a substituent. When a plurality of R ²¹ and R ⁴¹ are present, they may be the same or different. n represents an integer of 0 to 5, and m represents an integer of 0 to 5.

In the general formula (5), R ¹¹ , R ¹² and R ¹³ are the same as those in the general formula (1), and preferred ranges are also the same. In the general formula (5), R ⁴¹ is the same as that in the general formula (3), and the preferred range is also the same. ^{Incidentally,} it is possible to illustrate the same substituents as ^{R 41} in the ^{R 21} also, the general formula (3).

In the general formula (5), n is preferably 0 to 3, and more preferably 0 to 2. Further, m is preferably 0 to 3, and more preferably 0 to 2.

The imino ether compound used in the present invention is preferably represented by the following general formula (6).

In General Formula (6), R ¹¹ , R ¹² and R ¹³ each independently represent a hydrogen atom, an alkyl group which may have a substituent, or an aryl group which may have a substituent. R ⁴¹ represents a substituent, and when a plurality of R ⁴¹ are present, they may be the same or different. n represents an integer of 0 to 5. P represents an integer of 2 to 4, and L ¹ represents an alkylene part which may have a substituent, a cycloalkylene part which may have a substituent, or a substituent at the bond terminal to the carbon atom. The p-valent group which is the arylene part which may have or the alkoxylene part which may have a substituent is represented.

In the general formula (6), R ¹¹ , R ¹² and R ¹³ are the same as those in the general formula (1), and preferred ranges are also the same. Moreover, in General formula (6), ^R41 is the same as that in General formula (3), and its preferable range is also the same. N is preferably 0 to 3, more preferably 0 to 2.

In General Formula (6), L ¹ may have an alkylene part that may have a substituent, a cycloalkylene part that may have a substituent, or a substituent at the terminal of the bond with the carbon atom. A p-valent group which is an arylene part or an alkoxylene part which may have a substituent is represented. p represents an integer of 2 to 4, and p is preferably 2 or 3.
Specific examples of the divalent group include an alkylene group that may have a substituent, a cycloalkylene group that may have a substituent, an arylene group that may have a substituent, and a substituent. And an alkoxylene group which may be used. In addition, the bond terminal to the carbon atom has an alkylene part which may have a substituent, a cycloalkylene part which may have a substituent, an arylene part which may have a substituent, or a substituent. A partial structure, such as —SO ₂ —, —CO—, a substituted or unsubstituted alkylene part, a substituted or unsubstituted alkenylene part, an alkynylene part, a substituted or unsubstituted phenylene part, And a group containing at least one selected from a substituted or unsubstituted biphenylene moiety, a substituted or unsubstituted naphthylene moiety, —O—, —S— and —SO—.
Specific examples of the trivalent group include, for example, a group obtained by removing one hydrogen atom from those having a substituent among the groups listed as examples of the divalent group.
Specific examples of the tetravalent group include, for example, a group obtained by removing two hydrogen atoms from those having a substituent among the groups listed as examples of the divalent group.

In the present invention, by setting p to 2 to 4, a compound having two or more imino ether moieties in one molecule can be obtained, and a more excellent end-capping effect can be exhibited. Furthermore, by using a compound having two or more imino ether moieties in one molecule, the imino ether value (total molecular weight / number of functional groups of imino ether) can be lowered, and the imino ether compound and the terminal carboxyl group of the polyester can be efficiently produced. Can be reacted.

The imino ether compound used in the present invention is preferably represented by the following general formula (7).

In general formula (7), R ² has an alkyl group that may have a substituent, a cycloalkyl group that may have a substituent, an aryl group that may have a substituent, or a substituent. R ¹¹ , R ¹² and R ¹³ each independently represents a hydrogen atom, an alkyl group which may have a substituent, or an aryl group which may have a substituent. P represents an integer of 2 to 4, and L ² represents an arylene moiety that may have a substituent, or a cycloalkylene moiety that may have a substituent, at the bond terminal to the nitrogen atom. Represents a p-valent group.

In the general formula (7), R ² , R ¹¹ , R ¹² and R ¹³ are the same as those in the general formula (1), and preferred ranges are also the same.

In General Formula (7), L ² represents a p-valent group whose bond terminal to the nitrogen atom is an arylene part that may have a substituent or a cycloalkylene part that may have a substituent. To express. L ² is preferably a p-valent group whose bond terminal to the nitrogen atom is an arylene moiety that may have a substituent. p represents an integer of 2 to 4, and p is preferably 2 or 3.
Specific examples of L ² include an arylene group which may have a substituent and a cycloalkylene group which may have a substituent. The bond terminal to the nitrogen atom is an arylene moiety which may have a substituent or a cycloalkylene moiety which may have a substituent, and as a partial structure, —SO ₂ —, —CO—, Substituted or unsubstituted alkylene part, substituted or unsubstituted alkenylene part, alkynylene part, substituted or unsubstituted phenylene part, substituted or unsubstituted biphenylene part, substituted or unsubstituted naphthylene part, -O-, -S- And a group containing at least one selected from —SO—.

The imino ether compound used in the present invention is preferably represented by the following general formula (8).

In general formula (8), R ² has an alkyl group which may have a substituent, a cycloalkyl group which may have a substituent, an aryl group which may have a substituent, or a substituent. R ⁴¹ represents a substituent, and when a plurality of R ⁴¹ are present, they may be the same or different. n represents an integer of 0 to 5. P represents an integer of 2 to 4, and L ³ represents a p-valent group in which the bond terminal to the oxygen atom is an alkylene part. However, in the alkylene part of L ³ , part or all of the hydrogen atoms may be substituted with an alkyl group which may have a substituent or an aryl group which may have a substituent.

In the general formula (8), R ² are each as agreed in the general formula (1), and preferred ranges are also the same. Moreover, in General formula (8), ^R41 is the same as that in General formula (3), and its preferable range is also the same. N is preferably 0 to 3, more preferably 0 to 2.

In General Formula (8), L ³ represents a p-valent group in which the bond terminal to the oxygen atom is an alkylene part. In the alkylene part of L ³ , part or all of the hydrogen atoms may be substituted with an alkyl group which may have a substituent or an aryl group which may have a substituent. p represents an integer of 2 to 4, and p is preferably 2 or 3.
Specific examples of L ³ include an alkylene group. In addition, the bond terminal to the oxygen atom is an alkylene moiety, and the partial structure includes —SO ₂ —, —CO—, a substituted or unsubstituted alkylene group, a substituted or unsubstituted alkenylene group, an alkynylene group, substituted or unsubstituted And a group containing at least one selected from a substituted phenylene group, a substituted or unsubstituted biphenylene group, a substituted or unsubstituted naphthylene group, —O—, —S— and —SO—.

The molecular weight per iminoether part of the iminoether compound is preferably 1000 or less, more preferably 750 or less, and even more preferably 500 or less. By setting the molecular weight per imino ether part within this range, it is possible to seal the terminal carboxylic acid group of the polyester with a low addition amount.

The molecular weight of the whole imino ether compound is preferably 300 or more, and more preferably 400 or more. By setting the molecular weight of the imino ether within this range, volatilization can be more effectively suppressed.

The imino ether compound is preferably a bifunctional or higher functional compound, and more preferably a bifunctional, trifunctional or tetrafunctional compound from the viewpoint of ease of synthesis. Here, the functional number represents the number of imino ether parts contained in the compound, and the bifunctional imino ether compound means a compound containing two imino ether parts. By making the iminoether compound a bifunctional or higher compound, the end-capping effect can be further enhanced.

Although the preferable specific example of General formula (1) is shown below, this invention is not limited to this.

(Chemical modification method of terminal carboxyl group of polyester)
Chemical modification of the terminal carboxyl group of the polyester can be performed by mixing the iminoether compound represented by the general formula (1) and the polyester in a molten state. When the imino ether compound and the polyester are reacted at 100 to 350 ° C., the imino ether group and the polyester terminal carboxyl group react to form a carboxylic acid ester as shown in the following reaction scheme. Moreover, since the imino ether compound represented by the general formula (1) becomes an amide compound by reacting with the terminal carboxyl group of the polyester, the amide compound is also included in the polyester resin composition.

The reaction rate between the imino ether compound represented by the general formula (1) and the polyester terminal carboxyl group is preferably 0.1 to 99%, more preferably 1 to 90%, and more preferably 2 to 80%. More preferably. By setting the reaction rate within the above range, the hydrolysis resistance can be sufficiently improved. Furthermore, by setting the reaction rate within the above range, the generated amide compound can be prevented from crying from the polyester film, and the surface state of the polyester film can be made better.

Conventionally, carboxylic acid has been esterified by reacting oxazoline or oxazine with carboxylic acid. It is known that a ring-opening reaction occurs when oxazoline or oxazine is used as a terminal blocking agent. It is also known that self-condensation proceeds as a side reaction simultaneously with the ring-opening reaction.

The self-condensation accompanied by the ring-opening reaction as described above is considered to be caused by the high nucleophilicity of the amide group of the alkylamide generated by the ring-opening reaction. On the other hand, the chain compounds of the imino ethers of the present invention are not self-condensed, and those of cyclic compounds are not highly nucleophilic in the aromatic amide obtained by the esterification reaction. It is thought that there is nothing. Thereby, it can suppress that an imino ether compound gelatinizes in a polyester resin.

(Pigment)
The polyester resin composition of the present invention contains a pigment. Examples of the pigment include inorganic pigments such as titanium oxide, barium sulfate, silicon oxide, aluminum oxide, magnesium oxide, calcium carbonate, kaolin, talc, ultramarine blue, bitumen, and carbon black, and organic pigments such as phthalocyanine blue and phthalocyanine green. It is done. Among these, it is preferable to use a white pigment, more preferably titanium oxide, barium sulfate or calcium carbonate, and particularly preferably titanium oxide.

The average particle diameter of the pigment is preferably 0.03 to 0.8 μm in volume average particle diameter, and more preferably 0.15 to 0.5 μm. By setting the average particle size within the above range, the light reflection efficiency can be increased. The average particle diameter is a value measured by a laser analysis / scattering particle size distribution measuring apparatus LA950 (manufactured by Horiba, Ltd.).

As a method for adding the pigment to the polyester resin composition, various conventionally known methods can be used. The following method can be mentioned as the typical method.
(A) A method in which a pigment is added before the end of the transesterification or esterification reaction during the synthesis of the polyester, or a pigment is added before the start of the polycondensation reaction.
(B) A method in which a pigment is added to polyester and melt-kneaded.
(C) Master pellets (also referred to as master batches) to which a large amount of pigment is added in the methods (A) and (B) above are produced, and these are kneaded with a polyester not containing a pigment to obtain a predetermined amount of pigment. The method of containing.
(D) The method of using the master pellet of said (C) as it is.

Among these, as the method for adding the pigment to the polyester resin composition, it is preferable to employ the method (C). In the method (C), it is also possible to employ a method in which a polyester resin and a pigment that have not been dried in advance are put into an extruder and master pellets are produced while degassing moisture and air. In addition, it is preferable to prepare a master pellet using a polyester resin which has been dried in advance, because an increase in the acid value of the polyester can be suppressed.

When preparing master pellets, it is preferable to reduce the moisture content of the polyester to be added in advance by drying. The drying conditions are preferably 100 to 200 ° C., more preferably 120 to 180 ° C., for 1 hour or longer, more preferably 3 hours or longer, and even more preferably 6 hours or longer. Thereby, it is sufficiently dried so that the moisture content of the polyester resin is preferably 50 ppm or less, more preferably 30 ppm or less. The mixing may be performed by a batch method, or may be performed by a single-screw or biaxial or more kneading extruder. When producing master pellets while deaeration, the polyester resin is melted at a temperature of 250 to 300 ° C., preferably 270 to 280 ° C., and one, preferably two or more deaeration ports are provided in the kneader. It is preferable to adopt a method such as performing continuous suction deaeration of 0.05 MPa or more, more preferably 0.1 MPa or more, and maintaining the reduced pressure in the mixer.

(polyester)
The polyester resin composition of the present invention contains polyester. The polyester that can be used in the present invention is not particularly limited, but is preferably a saturated polyester. By using a saturated polyester, a polyester film that is superior in terms of mechanical strength as compared with a film using an unsaturated polyester can be obtained.

Polyester has a —COO— bond or —OCO— bond in one molecular chain of the polymer. The terminal group of the polyester is an OH group, a COOH group, or a protected group OR ^X group or COOR ^X group (R ^X is an arbitrary substituent such as an alkyl group), which is an aromatic dibasic acid or A linear saturated polyester synthesized from the ester-forming derivative and diol or the ester-forming derivative is preferable. As the linear saturated polyester, for example, those described in JP-A-2009-155479 and JP-A-2010-235824 can be appropriately used.

Specific examples of the linear saturated polyester include polyethylene terephthalate (PET), polyethylene isophthalate, polybutylene terephthalate, poly (1,4-cyclohexylenedimethylene terephthalate), polyethylene-2,6-naphthalate, of which polyethylene terephthalate or Polyethylene-2,6-naphthalate is particularly preferred from the viewpoint of the balance between mechanical properties and cost, and polyethylene terephthalate is more particularly preferred.

The polyester may be a homopolymer or a copolymer. Further, polyester may be blended with other kinds of resins such as polyimide in a small amount. Moreover, as polyester, you may use crystalline polyester which can form anisotropy at the time of melt film forming.

As for the molecular weight of the polyester, the weight average molecular weight (Mw) is preferably 5000 to 100,000, more preferably 8000 to 80,000, and particularly preferably 12,000 to 60,000 from the viewpoints of heat resistance and viscosity. As the weight average molecular weight of the polyester, a value in terms of polymethyl methacrylate (PMMA) measured by gel permeation chromatography (GPC) using hexafluoroisopropanol as a solvent can be used.

Polyester can be synthesized by a known method. For example, polyester can be synthesized by a known polycondensation method or ring-opening polymerization method, and any of transesterification and direct polymerization can be applied.

The component derived from the carboxylic acid of the polyester is preferably a component derived from an aromatic dibasic acid or an ester-forming derivative thereof. When the polyester used in the present invention is a polymer or copolymer obtained by a condensation reaction mainly comprising an aromatic dibasic acid or an ester-forming derivative thereof and a diol or an ester-forming derivative thereof, An aromatic dibasic acid or an ester-forming derivative thereof and a diol or an ester-forming derivative thereof can be produced by an esterification reaction or an ester exchange reaction and then a polycondensation reaction. Moreover, the carboxylic acid value and intrinsic viscosity of the polyester can be controlled by selecting the raw material and reaction conditions. In order to effectively advance the esterification reaction or transesterification reaction and polycondensation reaction, it is preferable to add a polymerization catalyst during these reactions.

As a polymerization catalyst for polymerizing the polyester, it is preferable to use Al-based, Sb-based, Ge-based, and Ti-based compounds from the viewpoint of suppressing the carboxyl group content to a predetermined range or less. It is preferable to use it. In the case of using a Ti compound, an embodiment in which polymerization is performed by using the Ti compound as a catalyst in the range of 1 to 30 ppm, more preferably 3 to 15 ppm is preferable. When the proportion of the Ti-based compound is within the above range, the terminal carboxyl group can be adjusted within a predetermined range, and the hydrolysis resistance of the polymer substrate can be kept low.

Examples of the synthesis of polyester using a Ti compound include Japanese Patent Publication No. 8-301198, Japanese Patent No. 2543624, Japanese Patent No. 3335683, Japanese Patent No. 3717380, Japanese Patent No. 397756, Japanese Patent No. 3996226, Japanese Patent No. 3997866, Japanese Patent No. 39968661, The methods described in Japanese Patent No. 40000867, Japanese Patent No. 4053837, Japanese Patent No. 4127119, Japanese Patent No. 4134710, Japanese Patent No. 4159154, Japanese Patent No. 4269704, Japanese Patent No. 413538, and the like can be applied, and the contents thereof are incorporated herein.

The polyester is preferably one that has been solid-phase polymerized after polymerization. The solid-phase polymerization method may be a continuous method (a method in which a tower is filled with a resin, and this is slowly heated for a predetermined time and then sent out), or a batch method (a resin is placed in a container). Or a method of heating for a predetermined time). Specifically, solid phase polymerization is described in Japanese Patent No. 2621563, Japanese Patent No. 3121876, Japanese Patent No. 3136774, Japanese Patent No. 3603585, Japanese Patent No. 3616522, Japanese Patent No. 3617340, Japanese Patent No. 3680523, Japanese Patent No. 3717392, Japanese Patent No. 4167159, etc. Methods can be applied, the contents of which are incorporated herein.

The temperature of the solid phase polymerization is preferably 170 to 240 ° C, more preferably 180 to 230 ° C, and further preferably 190 to 220 ° C. The solid phase polymerization time is preferably 5 to 100 hours, more preferably 10 to 75 hours, and further preferably 15 to 50 hours. The solid phase polymerization is preferably performed in a vacuum or in a nitrogen atmosphere.

(Polyester resin composition)
The polyester resin composition of the present invention contains the above-described imino ether compound, a pigment, and polyester. In addition, unless the polyester resin composition of this invention is contrary to the meaning of this invention, it does not refuse containing compounds other than the imino ether compound mentioned above. For example, a carbodiimide compound, a ketene imine compound, an epoxy compound, an oxazoline compound, and the like can be used in combination. However, the content of the imino ether compound contained in the polyester resin composition of the present invention is preferably 70% by mass or more and more preferably 80% by mass or more with respect to the organic compound other than the polyester. More preferably, it is 90% by mass or more.

The imino ether compound described above is preferably contained in an amount of 0.05 to 35% by mass, more preferably 0.05 to 20% by mass, and more preferably 0.5 to 20% by mass with respect to the total mass of the polyester resin composition. % Is more preferable, and 1 to 20% by mass is particularly preferable. By making content of an imino ether compound into the said range, the hydrolysis resistance of a polyester film can be improved. Furthermore, by setting the content of the imino ether compound within the above range, in addition to improving the visible light hiding property of the polyester film, it is possible to improve the film thickness uniformity when the polyester film is formed. .

The pigment is preferably contained in an amount of 0.2 to 50% by mass, more preferably 0.4 to 50% by mass, and further preferably 5 to 50% by mass based on the total mass of the polyester resin composition. preferable. By making content of the pigment in a polyester resin composition into the said range, the visible light concealment property of a polyester film can be improved, and also the reflectance of sunlight can be improved.

The above-mentioned imino ether compound contained in the polyester resin composition suppresses hydrolysis of the polyester by sealing the end of the polyester. In the step of kneading the white pigment into the polyester, the polyester may be hydrolyzed due to moisture contained in the pigment, and the polyester may be thermally decomposed due to heat generated by the shearing of the pigment particles. The above-described imino ether compound can suppress thermal decomposition of polyester promoted by heat generated by shearing of pigment particles.

Further, various additives such as compatibilizers, plasticizers, weathering agents, antioxidants, heat stabilizers, lubricants are included in the polyester resin composition of the present invention as long as the effects of the present invention are not impaired. Further, it may contain an antistatic agent, a brightening agent, a coloring agent, a conductive agent, an ultraviolet absorber, a flame retardant, a flame retardant aid, a dye, and the like.

(Master pellet)
The present invention also relates to a master pellet formed using the above-described polyester resin composition. The master pellet is a kneaded polyester resin composition formed into chips, and is formed by extrusion molding of the polyester resin composition. Examples of the shape of the master pellet include a cylindrical shape, and the length may be 1 to 10 mm in length and the base diameter may be 1 to 10 mm.

The master pellet of the present invention contains the above-described iminoether compound and pigment, and the preferred content is the same as the content range contained in the polyester resin composition. That is, the above-mentioned imino ether compound is preferably contained in an amount of 0.05 to 35% by mass, more preferably 0.05 to 20% by mass, and more preferably 0.5 to 20% by mass with respect to the total mass of the master pellet. % Is more preferable, and 1 to 20% by mass is particularly preferable. Further, the pigment is preferably contained in an amount of 0.2 to 50% by mass, more preferably 0.4 to 50% by mass, and further preferably 5 to 50% by mass with respect to the total mass of the master pellet. preferable.

(Polyester film)
The present invention also relates to a polyester film formed using the above-described polyester resin composition. The polyester film of the present invention can be formed by melting and extruding the above-described polyester resin composition, or by melt-kneading and extruding the above-described polyester resin composition and another polyester resin composition. It can also be formed. Here, it is preferable that another polyester resin composition is a polyester resin composition comprised from the polyester contained in the polyester resin composition mentioned above.

The polyester film of the present invention contains the above-described imino ether compound. The imino ether compound is preferably contained in an amount of 0.05 to 3% by weight, more preferably 0.1 to 2% by weight, and more preferably 0.1 to 1.5% by weight based on the total weight of the polyester film. More preferably. By making content of an imino ether compound into the said range, the hydrolysis resistance of a polyester film can be improved. Furthermore, by setting the content of the imino ether compound within the above range, in addition to improving the visible light hiding property of the polyester film, it is possible to improve the film thickness uniformity when the polyester film is formed. .

Furthermore, the polyester film of the present invention contains a pigment. The pigment is preferably contained in an amount of 0.1 to 10% by mass, more preferably 0.5 to 10% by mass, and further preferably 0.5 to 5% by mass with respect to the total mass of the polyester film. preferable. By making content of the pigment in a polyester film into the said range, the visible light concealment property of a polyester film can be improved, and also the reflectance of sunlight can be raised.

The thickness of the polyester film of the present invention varies depending on the application, but when used as a member of a back sheet for a solar cell module, it is preferably 25 μm to 300 μm, more preferably 120 to 300 μm. When the thickness is 25 μm or more, sufficient mechanical strength is obtained, and when the thickness is 300 μm or less, a merit in cost can be obtained.

The polyester film of the present invention is preferably stretched and more preferably biaxially stretched. That is, the polyester film of the present invention is preferably a biaxially oriented film. Especially, it is especially preferable compared with extending | stretching of tubular etc. that it is plane biaxially stretched, and it is more especially preferable that it is biaxially stretched sequentially. The biaxially stretched polyester film is stretched in the longitudinal direction (MD: Machine Direction) (hereinafter also referred to as “longitudinal stretching”) and in the width direction (TD: Transverse Direction) (hereinafter also referred to as “lateral stretching”). It is a film that has been applied. Each of the longitudinal stretching and the lateral stretching may be performed once, may be performed a plurality of times, and may be stretched longitudinally and laterally at the same time.

The MD orientation and TD orientation of the polyester film of the present invention are each preferably 0.14 or more, more preferably 0.155 or more, and particularly preferably 0.16 or more. When the degree of orientation is 0.14 or more, the restraint property of the amorphous chain is improved (the mobility is lowered), and the hydrolysis resistance is improved. MD and TD orientations were measured using x, y, and biaxially oriented films in a 25 ° C. atmosphere using an Abbe refractometer, a monochromatic sodium D line as a light source, and methylene iodide as a mounting solution. The refractive index in the z direction is measured, and can be calculated from MD orientation degree: Δn (xz), TD orientation degree; Δn (yz).

The terminal carboxyl group content in the polyester film (the carboxylic acid value of the polyester, hereinafter also referred to as AV) is preferably 25 eq / ton or less, more preferably 20 eq / ton or less, particularly preferably 16 eq / ton or less with respect to the polyester. And more particularly preferably 15 eq / ton or less. When the carboxyl group content is 25 eq / ton or less, it is possible to maintain the hydrolysis resistance and heat resistance of the polyester film by combining with the imino ether compound, and it is possible to suppress a decrease in strength when the moisture and heat age. . The terminal carboxyl group content in the polyester can be adjusted by polymerization catalyst species, polymerization time, and film forming conditions (film forming temperature and time). The carboxyl group content is H.264. A. Pohl, Anal. Chem. 26 (1954) 2145, and can be measured by a titration method. Specifically, the polyester is dissolved in benzyl alcohol at 205 ° C., a phenol red indicator is added, and titrated with a solution of sodium hydroxide in water / methanol / benzyl alcohol to determine the carboxylic acid value (eq / ton) can be calculated.

The terminal hydroxyl group content in the polyester film is preferably 120 eq / ton or less, more preferably 90 eq / ton or less, based on the polyester. The lower limit of the hydroxyl group content is preferably 20 eq / ton or more from the viewpoint of adhesion to the upper layer. The hydroxyl group content in the polyester can be adjusted by the polymerization catalyst species, the polymerization time, and the film forming conditions (film forming temperature and time). As the terminal hydroxyl group content, a value measured by ¹ H-NMR using a deuterated hexafluoroisopropanol solvent can be used.

The intrinsic viscosity (IV) of the polyester film of the present invention is preferably from 0.55 to 0.94 dl / g, more preferably from 0.60 to 0.84 dl / g, and from 0.62 to 0.80 dl / g. Particularly preferred. By making the intrinsic viscosity of the polyester film within the above range, the film forming property can be improved and the film thickness uniformity can be improved.
The intrinsic viscosity (IV) of the polyester is the intrinsic viscosity of the polyester in which all the polyesters are mixed when there are two or more kinds of polyesters used in film formation (such as when the recovered polyesters of JP2011-256337A are used). It is preferable that the viscosity satisfies the above range.
The intrinsic viscosity (IV) of the polyester can be calculated from the solution viscosity measured at 25 ° C. by dissolving the polyester in orthochlorophenol, using the following equation.
ηsp / C = [η] + K [η] ² · C
Here, ηsp = (solution viscosity / solvent viscosity) −1, C is the weight of dissolved polymer per 100 ml of solvent (1 g / 100 ml in this measurement), and K is the Huggins constant (0.343) The solution viscosity and the solvent viscosity can be measured using an Ostwald viscometer.

(Production method of polyester film)
(Film forming process)
In the film forming step, an unstretched film can be formed by pouring a melt obtained by melting a mixture containing polyester, the above-described iminoether compound, and a pigment and cooling and solidifying the melt. The melt is preferably passed through a gear pump or a filter, and the melt that has passed through the filter is extruded through a die to a cooling roll and cooled and solidified. The extruded melt can be brought into close contact with the cooling roll using an electrostatic application method. At this time, the surface temperature of the cooling roll is preferably about 10 to 40 ° C.

(Stretching process)
The (unstretched) film formed by the film forming step can be subjected to a stretching treatment in the stretching step. In the stretching step, the film that has been cooled and solidified with a cooling roll (unstretched) is preferably stretched in one or two directions, and more preferably stretched in two directions. In stretching in two directions (biaxial stretching), the longitudinal stretching and the lateral stretching may each be performed once, or may be performed a plurality of times, and may be simultaneously performed in the longitudinal and lateral directions.
The stretching treatment is preferably performed at a glass temperature (Tg) ° C. to (Tg + 60) ° C. of the film, more preferably Tg + 3 ° C. to Tg + 40 ° C., and further preferably Tg + 5 ° C. to Tg + 30 ° C.

The preferred draw ratio is at least 280 to 500%, more preferably 300 to 480%, still more preferably 320 to 460%. In the case of biaxial stretching, the film may be stretched evenly in the vertical and horizontal directions, but it is more preferable to stretch one of the stretch ratios more than the other and unevenly stretch. Either vertical (MD) or horizontal (TD) may be increased. The draw ratio here is determined using the following equation.
Stretch ratio (%) = 100 × (length after stretching) / (length before stretching)

The biaxial stretching treatment is performed, for example, at (Tg ₁ ) ° C. to (Tg ₁ +60) ° C., which is the glass transition temperature of the film, so that the total magnification becomes 3 to 6 times, once or twice in the longitudinal direction. Thereafter, the film can be applied at (Tg ₁ ) ° C. to (Tg + 60) ° C. so that the magnification is 3 to 5 times in the width direction.

The biaxial stretching process can be stretched in the longitudinal direction using two or more pairs of nip rolls whose peripheral speed on the outlet side is increased (longitudinal stretching), and both ends of the film are gripped by chucks and orthogonally oriented (longitudinal direction). (Perpendicular direction) can be performed (lateral stretching).

In the stretching step, the film can be heat-treated before or after the stretching treatment, preferably after the stretching treatment. By performing heat treatment, microcrystals can be generated, and mechanical properties and durability can be improved. The film may be subjected to a heat treatment at about 180 to 210 ° C. (more preferably 185 to 220 ° C.) for 1 to 60 seconds (more preferably 2 to 30 seconds).

In the stretching step, a thermal relaxation treatment can be performed after the heat treatment. The thermal relaxation treatment is a treatment for shrinking the film by applying heat to the film for stress relaxation. The thermal relaxation treatment is preferably performed in both the MD and TD directions of the film. The various conditions in the thermal relaxation treatment are preferably treatment at a temperature lower than the heat treatment temperature, and preferably 130 to 220 ° C. In the heat relaxation treatment, the thermal shrinkage (150 ° C.) of the film is preferably 1 to 12%, more preferably 1 to 10% for both MD and TD. For heat shrinkage (150 ° C), a sample with a measurement direction of 350 mm and a width of 50 mm was cut out, marked at 300 mm intervals near both ends in the longitudinal direction of the sample, and fixed at one end to an oven adjusted to a temperature of 150 ° C. The other end is left free for 30 minutes, and then the distance between the gauge points is measured at room temperature. This length is defined as L (mm), and the heat shrinkage rate is obtained by the following formula using the measured value. Can do.
150 ° C. thermal shrinkage (%) = 100 × (300−L) / 300
Further, when the thermal contraction rate is positive, it indicates shrinkage, and negative indicates elongation.

(Back sheet for solar cell module)
The polyester film of the present invention can also be used as a laminated film in which a coating layer such as an easy adhesion layer is provided thereon. Moreover, the polyester film and laminated | multilayer film of this invention can be used suitably as a solar cell module backsheet (protective sheet of a solar cell module). Since the polyester film of the present invention has a good surface shape and excellent moisture and heat resistance, when used in a back sheet for a solar cell module, the solar cell module can be protected for a long period of time. Furthermore, since the polyester film of the present invention has visible light concealability and can reflect sunlight, the power generation efficiency of the solar cell module is not impaired.

A back sheet for a solar cell module can be formed by laminating the following functional layer on the polyester film of the present invention. When laminating functional layers, it is preferable to provide an easy-adhesion layer in between. In addition, before laminating | stacking a functional layer, it is preferable to surface-treat the surface of a polyester film, for example, a flame treatment, a corona treatment, a plasma treatment, an ultraviolet treatment etc. can be given.

<Reflective layer (colored layer)>
Although the polyester film of this invention can also exhibit the function as a reflective layer (colored layer), the solar cell module backsheet may further have a reflective layer (colored layer) as a functional layer. The colored layer is a layer arranged in contact with the surface of the polyester film or through another layer, and can be constituted using a pigment or a binder. By providing the reflective layer, it is possible to reflect the light that has passed through the solar cell and reaches the back sheet out of the sunlight incident on the solar cell module, and return it to the solar cell. Thereby, power generation efficiency can be improved.

(binder)
As the binder used in the reflective layer, acrylic, polyester, polyurethane, and polyolefin polymers can be used. Of these, polyolefin polymers are preferred.

The solar cell module backsheet of the present invention is preferably provided with a light reflecting layer on the inner side surface (side to be bonded to the sealing material). The reflective layer preferably contains an epoxy-based, isocyanate-based, oxazoline-based, carbodiimide-based or the like crosslinking agent in order to further improve the adhesion with the sealing material. Of these cross-linking agents, carbodiimide cross-linking agents and oxazoline cross-linking agents are particularly preferable from the viewpoint of ensuring adhesion after wet heat aging.

It is preferable to add a white pigment to the reflective layer for the purpose of increasing the reflectance. Preferred examples of the white pigment include titanium oxide, barium sulfate, silicon oxide, aluminum oxide, magnesium oxide, calcium carbonate, kaolin, and talc. Of these, titanium oxide is particularly preferable from the viewpoints of whiteness, reflectance, and durability. Titanium oxide has three types of crystal systems of rutile, anatase, and brookite, but those having a rutile crystal structure are preferred because of their high refractive index, whiteness, and low photocatalytic activity.

In the reflective layer, known additives such as surfactants and preservatives may be added as necessary. Examples of the surfactant include known surfactants such as anionic and nonionic surfactants. Examples of the anionic surfactant include sodium alkyl sulfate and sodium alkylbenzene sulfonate, and examples of the nonionic surfactant include polyoxyethylene alkyl ether. Also preferred are fluorosurfactants such as sodium perfluoroalkyl sulfate.

The thickness of the reflective layer is preferably 3 to 10 μm, more preferably 4 to 8 μm. By making the thickness of the reflective layer in the range of 3 to 10 μm, it is possible to achieve both required reflectance and adhesiveness.

The method for forming the reflective layer is not particularly limited, and can be formed using a known coating method such as a roll coating method, a bar coater method, a slide die method, or a gravure coater method. There is no restriction | limiting also in a coating solvent, You may use organic solvent type | system | group solvents like methyl ethyl ketone, toluene, and xylene, or you may use water as a solvent. Considering that the environmental load is small, it is particularly preferable to use water as a solvent. The coating solvent may be used alone or in combination. In particular, in the case of an aqueous coating solvent, a mixed solvent obtained by adding a small amount of a water-miscible organic solvent to water may be used.
Although there is no particular limitation on the drying of the reflective layer, it is preferable to dry at a temperature of about 120 to 200 ° C. for about 1 to 10 minutes from the viewpoint of shortening the drying time. When the drying temperature is less than 120 ° C., the drying time becomes long, which is disadvantageous in production. Conversely, if it exceeds 200 ° C., the flatness of the resulting backsheet may be impaired.

<Overcoat layer>
The back sheet for a solar cell module of the present invention may be provided with an overcoat layer on the reflective layer for the purpose of improving the adhesion to the sealing material.

As the binder for the overcoat layer, those described for the reflective layer can be preferably used. As the type of crosslinking agent for the overcoat layer, those described for the reflective layer can be preferably used.
Further, as the type and amount of other additives in the overcoat layer, those described in the reflective layer can be preferably used.

The film thickness of the overcoat layer is preferably in the range of 0.1 to 1.0 μm, more preferably 0.2 to 0.8 μm. By setting the thickness of the overcoat layer in the range of 0.1 to 1.0 μm, it is possible to obtain strong adhesiveness with the sealing material.

As the method for forming the overcoat layer, the coating solvent, and the drying method, those described in the reflective layer can be preferably used.

<Back layer>
The back sheet for a solar cell module of the present invention is preferably provided with a back layer for protecting the support on the outer surface (the surface on the opposite side of the solar cells). As the binder for the back layer, it is preferable to use a silicone-based composite polymer described below from the viewpoint of durability and adhesion to the support. The silicone-based composite polymer (hereinafter sometimes referred to as “composite polymer”) includes a — (Si (R ¹ ) (R ² ) —O) _n — moiety in the molecule and a polymer structure part that is copolymerized with the above-described part. It is a polymer. By using a silicone-based composite polymer as a binder for the back surface layer, it becomes possible to make the adhesion between the back surface layer and the support particularly good, and it is possible to keep the decrease in adhesion small even after a long period of time. It becomes possible.

The silicone composite polymer is preferably in the form of an aqueous polymer dispersion (so-called latex). When the silicone-based composite polymer is an aqueous polymer in the form of latex, the silicone-based composite polymer preferably has a water-affinity functional group such as a carboxyl group, a sulfonic acid group, a hydroxyl group, or an amide group. When the silicone composite polymer has a carboxyl group, the carboxyl group may be neutralized with sodium, ammonium, amine or the like.
In addition, when silicone composite polymers are used in the form of latex, emulsification stability of surfactants (eg, anionic and nonionic surfactants) and polymers (eg: polyvinyl alcohol) to improve stability An agent may be included. Further, if necessary, a pH adjuster (eg, ammonia, triethylamine, sodium bicarbonate, etc.), preservative (eg: 1,3,5-hexahydro- (2-hydroxyethyl) -s-triazine, 2- (4 -Thiazolyl) benzimidazole), thickeners (eg, sodium polyacrylate, methylcellulose, etc.), film-forming aids (eg: butyl carbitol acetate, etc.), etc. Also good.

It is preferable to add a crosslinking agent to the back layer in order to improve adhesion to the support. As the kind of the cross-linking agent, those described for the reflective layer can be used.

It is preferable to add an ultraviolet absorber to the back layer. Examples of ultraviolet absorbers include, for example, salicylic acid-based, benzophenone-based, benzotriazole-based, cyanoacrylate-based ultraviolet absorbers, hindered amine-based ultraviolet stabilizers, and the like in the case of organic ultraviolet absorbers. . Examples of inorganic ultraviolet absorbers include metal oxides such as titanium oxide, zinc oxide, and cerium oxide, and carbon-based components such as carbon, fullerene, carbon fiber, and carbon nanotube. Of these, titanium oxide is particularly preferable from the viewpoint of cost and durability.

A white pigment may be added to the back layer for the purpose of supplementing the reflectance of the reflective layer. Regarding the type of white pigment, the white pigment described in the reflective layer can be preferably used. In addition, when using a titanium oxide as a white pigment, it can serve as a pigment and a ultraviolet absorber. As the types and addition amounts of other additives in the back layer, those described in the reflective layer can be preferably used.

The thickness of the back layer is preferably 3 to 12 μm, more preferably 4 to 8 μm. By setting the thickness of the back layer in the range of 3 to 12 μm, both necessary durability and adhesiveness can be achieved.

As the back layer forming method, coating solvent, and drying method, those described in the reflective layer can be preferably used.

<Back side protective layer>
In the solar cell module backsheet of the present invention, a back surface protective layer may be provided on the back surface layer for the purpose of further improving durability.

The binder for the back surface protective layer is preferably a fluoropolymer from the viewpoint of durability. The fluorine-based polymer that can be preferably used in the present invention is a polymer containing a fluorine-containing monomer in the main chain or side chain. The fluorine-containing monomer may be contained in either the main chain or the side chain, but is preferably contained in the main chain from the viewpoint of durability.

When the fluoropolymer is used in a latex form, the particle size is preferably about 50 to 500 nm, and the solid content concentration is preferably about 15 to 50% by mass. The fluorine-based polymer preferably has a water-affinity functional group such as a carboxyl group, a sulfonic acid group, a hydroxyl group or an amide group when the aqueous polymer is in the form of latex.

It is preferable to add a crosslinking agent to the back surface protective layer in order to improve the adhesion to the support. As the kind of the cross-linking agent, those described for the reflective layer can be used.

) A slipping agent may be added to the back surface protective layer as necessary. Examples of the slip agent include synthetic wax compounds, natural wax compounds, surfactant compounds, inorganic compounds, organic resin compounds, and the like. Among these, from the viewpoint of the surface strength of the polymer layer, a compound selected from synthetic wax compounds, natural wax compounds, and surfactant compounds is preferable.

If necessary, colloidal silica may be added to the back surface protective layer. In colloidal silica, fine particles containing silicon oxide as a main component are present in a fine particle state with water or a monovalent alcohol or diol or a mixture thereof as a dispersion medium.

As the types and addition amounts of other additives for the back surface protective layer, those described for the reflective layer can be preferably used.

The thickness of the back surface protective layer is preferably 0.5 to 6 μm, more preferably 1 to 5 μm. If the thickness of the back surface protective layer is 0.5 μm or more, the durability is sufficient, and if it is 6 μm or less, it is advantageous in terms of cost. As the coating method, coating solvent, and drying method for the back surface protective layer, those described in the reflective layer can be preferably used.

(Solar cell module)
The solar cell module of the present invention includes the polyester film of the present invention or the back sheet for the solar cell module of the present invention. The solar cell module of the present invention comprises a solar cell element that converts light energy of sunlight into electric energy, a transparent substrate on which sunlight is incident, and the polyester film (back sheet for solar cell) of the present invention described above. It is arranged and arranged between. The substrate and the polyester film can be formed by sealing with a resin (so-called sealing material) such as an ethylene-vinyl acetate copolymer.

Components other than solar cell modules, solar cells, and backsheets are described in detail in, for example, “Solar Power Generation System Constituent Materials” (supervised by Eiichi Sugimoto, Industrial Research Committee, Inc., issued in 2008).

The transparent substrate only needs to have a light-transmitting property through which sunlight can be transmitted, and can be appropriately selected from base materials that transmit light. From the viewpoint of power generation efficiency, the higher the light transmittance, the better. For such a substrate, for example, a glass substrate, a transparent resin such as an acrylic resin, or the like can be suitably used.

Solar cell elements include silicon-based materials such as single crystal silicon, polycrystalline silicon, and amorphous silicon, III-V groups such as copper-indium-gallium-selenium, copper-indium-selenium, cadmium-tellurium, gallium-arsenic, and II Various known solar cell elements such as -VI group compound semiconductor systems can be applied.

Hereinafter, the features of the present invention will be described more specifically with reference to examples and comparative examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.

The imino ethers (1) to (7) used in Examples and Comparative Examples were synthesized by the following synthesis method.

[Synthesis Example 1]
<Synthesis of iminoether (1)>

In a 5 L three-necked flask, 600 g (2.80 mol) of triethoxymethylbenzene, 498 g (1.28 mol) of 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 480 ml of toluene, 0.24 g of methanesulfonic acid ( 2.5 mmol) was added, and the mixture was stirred for 2 hours with heating under reflux. The reaction system temperature was set to 100 ° C. or lower, and the refluxed ethanol was removed with a Dean-Stark apparatus. After confirming the completion of the reaction by TLC (thin layer chromatography), the reaction mixture was cooled to room temperature, and methanol was added for crystallization to obtain 777 g of iminoether (1) (yield 95%). The obtained compound was identified by ¹ H-NMR.

[Synthesis Example 2]
<Synthesis of iminoether (2)>

In a 5 L three-necked flask, 512 g (2.80 mol) of trimethoxymethylbenzene, 498 g (1.28 mol) of 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 480 ml of toluene, 0.24 g of methanesulfonic acid ( 2.5 mmol) was added, and the mixture was stirred for 2 hours with heating under reflux. The reaction system temperature was set to 100 ° C. or lower, and the refluxed methanol was removed with a Dean-Stark apparatus. After confirming the completion of the reaction by TLC, the reaction mixture was cooled to room temperature, and methanol was added for crystallization to obtain 745 g of iminoether (2) (yield 95%). The obtained compound was identified by ¹ H-NMR.

[Synthesis Example 3]
<Synthesis of iminoether (3)>

In a 5 L three-necked flask, trimethyl orthoacetate 338 g (2.80 mol), 2,2-bis [4- (4-aminophenoxy) phenyl] propane 498 g (1.28 mol), toluene 480 ml, methanesulfonic acid 0.24 g (2 0.5 mmol), and the mixture was stirred for 2 hours under reflux with heating. The reaction system temperature was set to 100 ° C. or lower, and the refluxed methanol was removed with a Dean-Stark apparatus. After confirming the completion of the reaction by TLC, the mixture was cooled to room temperature, and methanol was added for crystallization to obtain 615 g of iminoether (3) (yield 92%). The obtained compound was identified by ¹ H-NMR.

[Synthesis Example 4]
<Synthesis of iminoether (4)>

A 5 L three-necked flask was charged with 512 g (2.80 mol) of trimethoxymethylbenzene, 310 g (1.28 mol) of 4,4′-diaminobenzanilide, 480 ml of toluene, and 0.24 g (2.5 mmol) of methanesulfonic acid, and heated to reflux. Stir for 2 hours. The reaction system temperature was set to 100 ° C. or lower, and the refluxed methanol was removed with a Dean-Stark apparatus. After confirming the completion of the reaction by TLC, the reaction mixture was cooled to room temperature, and methanol was added for crystallization to obtain 504 g (yield 85%) of iminoether (4). The obtained compound was identified by ¹ H-NMR.

[Synthesis Example 5]
<Synthesis of iminoether (5)>

A 5 L three-necked flask was charged with 512 g (2.80 mol) of trimethoxymethylbenzene, 191.8 g (1.28 mol) of 4-aminoacetanilide, 480 ml of toluene, and 0.24 g (2.5 mmol) of methanesulfonic acid. Stir for hours. The reaction system temperature was set to 100 ° C. or lower, and the refluxed methanol was removed with a Dean-Stark apparatus. After confirming the completion of the reaction by TLC, the mixture was cooled to room temperature, and methanol was added for crystallization to obtain 309 g of iminoether (5) (yield 90%). The obtained compound was identified by ¹ H-NMR.

[Synthesis Example 6]
<Synthesis of iminoether (6)>

A 5 L three-necked flask was charged with 210 g (1.0 mol) of 4,4′-methylenebis (cyclohexylamine), 243 g (2.4 mol) of triethylamine and 1.0 L of dimethylacetamide, and 336 g (2.4 mol) of benzoyl chloride in an ice bath. Was added dropwise, and the mixture was stirred at room temperature for 1 hour. 2.0 L of 1 mol / L hydrochloric acid water was added, and the mixture was stirred for 1 hour and filtered to obtain 397 g (yield 95%) of (6-1). The obtained compound was identified by ¹ H-NMR.

To a 5 L three-necked flask, 300 g of (6-1) and 1.0 L of thionyl chloride were added and stirred at 65 ° C. for 2 hours, and then excess thionyl chloride was removed under reduced pressure. After cooling to room temperature, 1.0 ml of THF (tetrahydrofuran) was added, and 310 g (1.6 mol) of SM-28 (sodium methylate 28% methanol solution) was added dropwise in an ice bath, followed by stirring at room temperature for 1 hour. 1.5 L of ethyl acetate and 1.0 L of pure water were added for liquid separation, dried over magnesium sulfate, and concentrated to obtain a solid. Methanol 2.0L was added there, and it stirred at room temperature for 1 hour, and obtained 288 g (yield 90%) of imino ether (6) by filtering. The obtained compound was identified by ¹ H-NMR.

[Synthesis Example 7]
<Imino ether (7)>

A 5-L flask was charged with 296 g (2.4 mol) of 2-aminobenzyl alcohol, 243 g (2.4 mol) of triethylamine and 1.5 L of dimethylacetamide, and 203 g (1.0 mol) of terephthalic acid chloride was added in portions in an ice bath. After stirring for 1 hour, 2.0 L of 1 mol / L hydrochloric acid water was added, stirred for 1 hour, and filtered to obtain 357 g (yield 95%) of (7-1). The obtained compound was identified by ¹ H-NMR.
To a 5 L three-necked flask, 300 g (0.8 mol) of (7-1) and 1.0 L of thionyl chloride were added and stirred at 65 ° C. for 2 hours, and then excess thionyl chloride was concentrated and removed. After adding 1.0 L of methanol, 386 g (2.0 mol) of SM-28 was slowly added dropwise in an ice bath, and the mixture was stirred at room temperature for 1 hour and at 40 ° C. for 50 hours. The precipitate was filtered to remove methanol under reduced pressure, 1.5 L of ethyl acetate was added, and the mixture was separated, dried over magnesium sulfate, crystallized by adding methanol, and filtered to iminoether (7) 136 g (yield 50%) was obtained. The obtained compound was identified by ¹ H-NMR.

(Production and evaluation of master pellets (polyester pellets))
<Synthesis of polyethylene terephthalate (PET (1), PET (2))>
-Process (A)-
4.7 tons of high-purity terephthalic acid and 1.8 tons of ethylene glycol were mixed for 90 minutes to form a slurry, which was continuously supplied to the first esterification reactor at a flow rate of 3800 kg / h. Next, an ethylene glycol solution of a citrate chelate titanium complex in which citric acid is coordinated to Ti metal (manufactured by Johnson Matthey, VERTEC AC-420) is continuously supplied to the first esterification reactor, and the temperature in the reactor is increased. While stirring at 250 ° C., the reaction was carried out with an average residence time of about 4.3 hours to obtain an oligomer. At this time, the citric acid chelate titanium complex was continuously added so that the amount of Ti added was 9 ppm in terms of element. The acid value of the obtained oligomer was 550 eq / ton.

The obtained oligomer was transferred to the second esterification reaction tank and reacted with stirring at a reaction tank temperature of 250 ° C. and an average residence time of 1.2 hours to obtain an oligomer having an acid value of 180 eq / ton. The inside of the second esterification reaction tank is divided into three zones from the first zone to the third zone. From the second zone, an ethylene glycol solution of magnesium acetate is added, and the amount of Mg added is 75 ppm in terms of element. Then, from the third zone, an ethylene glycol solution of trimethyl phosphate was continuously supplied so that the addition amount of P was 65 ppm in terms of element. The ethylene glycol solution of trimethyl phosphate was prepared by adding a 25 ° C. trimethyl phosphate solution to a 25 ° C. ethylene glycol solution and stirring at 25 ° C. for 2 hours (phosphorus compound content in the solution: 3 .8% by mass).
As a result, an esterification reaction product was obtained.

-Process (B)-
The esterification reaction product obtained in the step (A) was continuously supplied to the first polycondensation reaction tank. Next, polycondensation (ester exchange reaction) is performed with an average residence time of about 1.8 hours while stirring the esterification reaction product at a reaction temperature of 270 ° C. and a reaction vessel pressure of 20 torr (2.67 × 10 ⁻³ MPa). It was.

Next, the obtained reaction product was transferred from the first polycondensation reaction tank to the second double condensation reaction tank. Thereafter, the reaction product was stirred in the second double condensation reaction vessel at a reaction vessel temperature of 276 ° C. and a reaction vessel pressure of 5 torr (6.67 × 10 ⁻⁴ MPa), and the reaction was conducted under the condition of a residence time of about 1.2 hours. (Transesterification reaction).

Subsequently, the reaction product obtained by the transesterification reaction is further transferred from the second double condensation reaction tank to the third triple condensation reaction tank. In this reaction tank, the reaction tank temperature is 278 ° C. and the reaction tank pressure is 1. Polyethylene terephthalate having a carboxylic acid number of 24 eq / ton and an intrinsic viscosity of 0.63 dl / g was reacted (transesterification reaction) with stirring at 5 torr (2.0 × 10 ⁻⁴ MPa) and a residence time of 1.5 hours. A resin (PET (1)) was obtained.

-Process (C)-
The resin was dried at 170 ° C. for 5 hours. Thereafter, the pellets were transferred to a solid phase polymerization tank, and solid phase polymerization was performed at 210 ° C. while flowing N ₂ gas containing 200 ppm of water vapor to 1 Nm ³ / hr per kg of the resin in the solid phase polymerization tank. By changing the solid-state polymerization time and the ethylene glycol (EG) gas concentration blown into the N ₂ gas, a polyethylene terephthalate resin (PET ()) having an intrinsic viscosity of 0.78 dl / g, a carboxylic acid value of 12 eq / ton, and a melting point of 255 ° C. 2)) was obtained.
In addition, by increasing the solid phase polymerization time, the carboxylic acid value decreases and the intrinsic viscosity increases. Moreover, a carboxylic acid value can be reduced by increasing EG gas. Note that increasing the EG gas does not affect the intrinsic viscosity.

(Preparation of master pellet (1))
-Extrusion molding-
The master pellet (1) was prepared by mixing 0.5 parts by mass of iminoether (1) and 44.0 parts by mass of titanium oxide with respect to 55.5 parts by mass of PET (2) solid-phase polymerized by the above method. . Specifically, the master pellet was prepared using a twin-screw kneading extruder. That is, PET resin was added from a hopper, and the end-capping agent of the powder was added and kneaded while being measured from the hopper using a feeder. The kneaded composition was extruded into a strand shape, then cooled with water and cut to prepare a master pellet (1). The master pellet (1) was a cylindrical size having a length of 3 mm and a base diameter of 2 mm.

(Preparation of master pellets (2) to (27))
Master pellets (2) to (27) were prepared in the same manner as the master pellet (1), except that the types and addition amounts of the resin, end-capping agent and pigment were changed to the conditions shown in Table 1 below. did.
The PEN (polyethylene naphthalate) used in the master pellet (17) was Teonex TN-80655 (manufactured by Teijin Limited). As the PBT (polybutylene terephthalate) used in the master pellet (18), DURANEX 2000 (manufactured by Polyplastics) was used.
Moreover, in the master pellets (23) and (24), the following Stabaxol P400 (manufactured by Rhein Chemie) was used as a terminal blocking agent. In the master pellet (25), the following BOXA (manufactured by Wako Pure Chemical Industries, Ltd.) was used as the end-capping agent. In the master pellet (26), POXA Epocross RPS (manufactured by Nippon Shokubai Co., Ltd.) was used as the end-capping agent. In the master pellet (27), the imino ether compound (7) synthesized in Synthesis Example 7 was used as a terminal blocking agent.

<Evaluation of volatility of master pellet>
When producing a master pellet, it was evaluated whether odor and white smoke were generated. The evaluation results are shown in Table 1. When producing a master pellet, it is preferable that white smoke is not generated, and it is more preferable that both odor and white smoke are not generated.
A: No odor and white smoke B: Odor but no white smoke C: Both odor and white smoke

From Table 1, it can be seen that the use of the iminoether compound represented by the general formula (1) of the present invention suppresses the generation of white smoke during the preparation of the master pellet (master pellets (1) to (21)). . In particular, it is understood that generation of both odor and white smoke can be suppressed by using an imino ether compound represented by the general formula (1) and having a molecular weight of 300 or more (master pellet (1 ) To (13) and master pellets (15) to (19)). Further, the addition amount of the imino ether compound represented by the general formula (1) is preferably 0.05 to 35% by mass with respect to the total mass of the master pellet, and the addition amount of the pigment is 0.2 to 50%. It can be seen that the content is preferably mass% (master pellets (19) to (21)).

Next, a polyester film was prepared using the master pellets (1) to (18) and (22) to (27), and the performance was evaluated.

Example 1 Production and Evaluation of Polyester Film <4> Formation of Polyethylene Terephthalate Film (Biaxially Stretched Film) After drying the obtained master pellet (1) so that the water content is 100 ppm or less, the resin composition The same PET (2) as used in the preparation of the master pellet was used so that the content of iminoether (1) was 0.05% by mass and the content of titanium oxide was 4.4% by mass with respect to the entire product. And extruded while mixing to obtain an unstretched film. For extrusion, a twin screw extruder was used, and melted and kneaded at 280 ° C. in a nitrogen stream. This melt (melt) was extruded through a gear pump, a filter and a die onto a chill roll to produce an unstretched film having a thickness of 3222 mm. did.
After heating this unstretched film with a radiant heater until the film surface temperature reaches about 85 ° C., the film is heated 3.0 times in the longitudinal direction (conveying direction) and then sent to the tenter until the film surface temperature reaches about 140 ° C. Thereafter, the film was stretched 4.2 times in the width direction and heat treated at 220 ° C. to obtain a biaxially stretched film having a thickness of 250 μm and a width of 1100 mm. This was designated as the polyester film of Example 1.

(Examples 2 to 18)
A polyester film was produced in the same manner as in Example 1 using master pellets (2) to (18). When the polyester film was produced, the master pellets (2) to (18) were mixed with the same resin as that used for producing the master pellet. The polyester films containing the master pellets (2) to (18) correspond to the polyester films of Examples 2 to 18, respectively.

(Comparative Example 1)
Only the above PET (2) was extruded to obtain an unstretched film. The unstretched film was heat-treated and stretched in the same manner as in Example 1 to obtain a polyester film of Comparative Example 1.

(Comparative Examples 2 to 7)
A polyester film was produced in the same manner as in Example 1 using master pellets (22) to (27). When preparing the polyester film, the master pellets (22) to (27) were mixed with the same resin as that used for preparing the master pellet. The polyester films containing the master pellets (22) to (27) correspond to the polyester films of Comparative Examples 2 to 7, respectively.

<Performance evaluation of polyester film>
(Viscosity change)
The intrinsic viscosity (IV) of the film and the intrinsic viscosity (IV) of the master pellet were evaluated according to the following evaluation criteria. Intrinsic viscosity (IV) was calculated using the following formula from a solution viscosity measured at 25 ° C. by dissolving polyester in orthochlorophenol.
ηsp / C = [η] + K [η] ² · C
Here, ηsp = (solution viscosity / solvent viscosity) −1, C is the weight of dissolved polymer per 100 ml of solvent (1 g / 100 ml in this measurement), and K is the Huggins constant (0.343) The solution viscosity and the solvent viscosity were measured using an Ostwald viscometer.
A: IV of film is equal to or less than IV of master pellet
B: IV of film increased from IV of master pellet

(Moisture and heat resistance (PCT test))
The hydrolysis resistance was evaluated based on the half life of elongation at break. The elongation at break half life is that the polyester film obtained in the examples and comparative examples is subjected to a storage treatment (heat treatment) under the conditions of 120 ° C. and a relative humidity of 100%. The breaking elongation (%) shown was evaluated by measuring a storage time at which the breaking elongation (%) shown by the polyester film before storage was 50%. The obtained results are shown in Table 2 below. It shows that the hydrolysis resistance of a polyester film is excellent, so that break elongation retention half-life is long. The breaking elongation half-life is preferably 80 hours or longer, more preferably 90 hours or longer.
A: Break elongation half-life is 90 hours or more B: Break elongation half-life is 80 hours or more and less than 90 hours C: Break elongation half-life is 70 hours or more and less than 80 hours D: Break elongation half-life is 60 hours or more Less than 70 hours E: Half elongation at break is less than 60 hours

(Volatile component)
The obtained polyester film was heated at 280 ° C. for 10 minutes, and the generated gas was detected. The amount of the volatile component in the film was measured by gas chromatography (manufactured by JASCO Corporation, trade name P & T-GC / MS) according to the following criteria, and evaluated according to the following criteria. The volatilization component contains an imino ether-derived compound, specifically, an imino ether compound and an amide compound. That is, a small amount of volatilized component detected means that the volatilization of the imino ether compound and the amide compound is small and the production environment is improved. The detected amount of the volatilized component is preferably 100 ppm or less, more preferably the detection limit (1 ppm or less).
A: Volatile component derived from imino ether is below detection limit B: Volatile component derived from imino ether was detected at 100 ppm or less C: Volatile component derived from imino ether was detected at 100 ppm or more

(Visible light concealment)
The optical density (OD) in the visible light region (380 to 700 nm) was measured with a Macbeth light densitometer, and evaluated according to the following evaluation criteria. A and B are practically acceptable standards.
A: Optical density exceeding 0.6 (OD) B: Optical density exceeding 0.4 (OD) and not more than 0.6 (OD) C: Optical density Of 0.4 or less (OD)

(Film surface)
With respect to the obtained polyester film, the surface state of the film was evaluated according to the following criteria. A is a practically acceptable standard.
A: The film is visually observed, and there are no irregularities on the film surface. B: The film is visually observed, and there are irregularities on the film surface.

From Table 2, it can be seen that in the polyester films obtained in Examples 1 to 18, the viscosity change of the resin composition at the time of production was small, and the volatilization of the volatilization component derived from the imino ether compound and the amide compound was suppressed. . In particular, it can be seen that in the polyester film containing the imino ether compounds (1) to (5), the viscosity change is less during film production.
It can also be seen that the polyester films obtained in Examples 1 to 18 are excellent in heat and moisture resistance. In particular, it can be seen that good moisture and heat resistance is obtained when the iminoether compound is contained in an amount of 0.1% by mass or more based on the total mass of the polyester film.
Furthermore, it can be seen that the polyester films obtained in Examples 1 to 18 have a sufficient visible light hiding property, and the film has a good surface shape. In particular, when the iminoether compound is contained in an amount of 2% by mass or less with respect to the total mass of the polyester film and the pigment is contained in an amount of 0.5% by mass or more with respect to the total mass of the polyester film, the visible light hiding property is increased.

According to the present invention, it is possible to provide a polyester film having both hydrolysis resistance and visible light concealing property and having a good film surface shape. Moreover, according to this invention, generation | occurrence | production of stimulating gas can be suppressed in the manufacturing process of the polyester film which has both hydrolysis resistance and visible-light concealment property, and industrial applicability is high.

Claims

A polyester resin composition comprising a compound represented by the following general formula (1), a pigment, and polyester;

In general formula (1), R 2 has an alkyl group which may have a substituent, a cycloalkyl group which may have a substituent, an aryl group which may have a substituent, or a substituent. R 3 represents an alkyl group represented by the following general formula (2) or an aryl group represented by the following general formula (3), and R 11 , R 12 and R 13 are each independently Represents a hydrogen atom, an alkyl group which may have a substituent, or an aryl group which may have a substituent. R 2 , R 3 , R 11 , R 12 and R 13 may be bonded to each other to form a ring. However, when R 3 is represented by the following general formula (2), the bond formed by at least one of R 11 to R 13 and at least one of R 31 to R 33 is a bond having two or more linking atoms.

In the general formula (2), R 31 , R 32 and R 33 each independently represent a hydrogen atom or a substituent. R 31 , R 32 and R 33 may be connected to each other to form a ring. In General Formula (3), R 41 represents a substituent, and when a plurality of R 41 are present, they may be the same or different. N represents an integer of 0 to 5. In general formulas (2) and (3), * represents a position bonded to a nitrogen atom.
The polyester resin composition according to claim 1, comprising 0.05 to 35% by mass of the compound represented by the general formula (1) with respect to the total mass of the polyester resin composition.
The polyester resin composition according to claim 1 or 2, comprising 0.2 to 50% by mass of the pigment with respect to the total mass of the polyester resin composition.
The polyester resin composition according to any one of claims 1 to 3, wherein the compound is represented by the following general formula (4):

In general formula (4), R 2 has an alkyl group which may have a substituent, a cycloalkyl group which may have a substituent, an aryl group which may have a substituent, or a substituent. R 11 , R 12 and R 13 each independently represents a hydrogen atom, an alkyl group which may have a substituent, or an aryl group which may have a substituent. R 41 represents a substituent, and when a plurality of R 41 are present, they may be the same or different. n represents an integer of 0 to 5.
The polyester resin composition according to any one of claims 1 to 4, wherein the compound is represented by the following general formula (5):

In general formula (5), R 11 , R 12 and R 13 each independently represent a hydrogen atom, an alkyl group which may have a substituent, or an aryl group which may have a substituent. R 21 and R 41 each independently represent a substituent. When a plurality of R 21 and R 41 are present, they may be the same or different. n represents an integer of 0 to 5, and m represents an integer of 0 to 5.
The polyester resin composition according to any one of claims 1 to 5, wherein the compound is represented by the following general formula (6):

In General Formula (6), R 11 , R 12 and R 13 each independently represent a hydrogen atom, an alkyl group which may have a substituent, or an aryl group which may have a substituent. R 41 represents a substituent, and when a plurality of R 41 are present, they may be the same or different. n represents an integer of 0 to 5. P represents an integer of 2 to 4, and L 1 represents an alkylene part which may have a substituent, a cycloalkylene part which may have a substituent, or a substituent at the bond terminal to the carbon atom. The p-valent group which is the arylene part which may have or the alkoxylene part which may have a substituent is represented.
The polyester resin composition according to any one of claims 1 to 6, wherein the compound is represented by the following general formula (7):

In general formula (7), R 2 has an alkyl group that may have a substituent, a cycloalkyl group that may have a substituent, an aryl group that may have a substituent, or a substituent. R 11 , R 12 and R 13 each independently represents a hydrogen atom, an alkyl group which may have a substituent, or an aryl group which may have a substituent. P represents an integer of 2 to 4, and L 2 represents an arylene moiety that may have a substituent, or a cycloalkylene moiety that may have a substituent, at the bond terminal to the nitrogen atom. Represents a p-valent group.
The polyester resin composition according to any one of claims 1 to 7, wherein the compound is represented by the following general formula (8):

In general formula (8), R 2 has an alkyl group which may have a substituent, a cycloalkyl group which may have a substituent, an aryl group which may have a substituent, or a substituent. R 41 represents a substituent, and when a plurality of R 41 are present, they may be the same or different. n represents an integer of 0 to 5. P represents an integer of 2 to 4, and L 3 represents a p-valent group in which the bond terminal to the oxygen atom is an alkylene part. However, in the alkylene part of L 3 , part or all of the hydrogen atoms may be substituted with an alkyl group which may have a substituent or an aryl group which may have a substituent.
The polyester resin composition according to any one of claims 1 to 8, wherein the pigment is a white pigment.
The polyester resin composition according to any one of claims 1 to 9, wherein the pigment is titanium oxide.
Master pellets formed using the polyester resin composition according to any one of claims 1 to 10.
A polyester film formed using the polyester resin composition according to any one of claims 1 to 10.
The polyester film according to claim 12, comprising 0.1 to 2% by mass of the compound represented by the general formula (1) with respect to the total mass of the polyester film.
The polyester film according to claim 12 or 13, comprising 0.5 to 10% by mass of the pigment with respect to the total mass of the polyester film.
The polyester film according to any one of claims 12 to 14, which is a biaxially oriented film.
A solar cell module backsheet using the polyester film according to any one of claims 12 to 15.
A solar cell module comprising the solar cell module backsheet according to claim 16.