JP2012196809A - Forming method of polyester resin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a forming method of a heat resistance polyester film.SOLUTION: Polyester in a general formula (1) and polyester in a general formula (2) are vertically and laterally extended at a temperature of not lower that (Tg-20°C) and not higher than (Tg+35°C), and two-axially extended at not smaller than a multiple of 1.15 and not larger than 1.30. Heat treatment is performed by a first heat treatment process for performing lateral both-end heat treatment at a temperature of not lower than (Tg-30°C) and not higher than (Tg-10°C), and a second heat treatment process for performing heat treatment without gripping the lateral ends at a lower temperature of not lower than (Tg-50°C) and not higher than (Tg-30°C).

Description

  The present invention relates to a method for producing a polyester resin film, and more particularly to a method for producing a biaxially stretched and heat-treated polyester resin film.

  Inorganic glass materials are widely used as transparent materials because they are excellent in transparency and heat resistance and have small optical anisotropy. However, inorganic glass is difficult to mold, has a large specific gravity, and is brittle. For this reason, the molded glass product is heavy and has drawbacks such as being easily damaged.

  Because of these drawbacks, development of resin materials that can replace inorganic glass materials has been underway. For example, polymethyl methacrylate, polycarbonate, polyethylene terephthalate, and the like are known as resin materials intended to replace inorganic glass materials. These resin materials are lightweight, have excellent mechanical properties, and are excellent in workability. Therefore, these resin materials are used for various purposes such as lenses and films.

  In recent years, replacement of a display substrate from glass to resin has been studied. In particular, a resin substrate capable of forming ITO (indium tin oxide) is required. The reason is that by using a resin substrate, the display substrate can be reduced in weight and thickness, and the impact resistance of the display substrate can be increased. In order to replace the glass substrate with a resin substrate, the resin substrate is required to have heat resistance (approximately 150 ° C. to 250 ° C.). Further, when manufacturing a display substrate while heating the resin substrate, particularly when annealing the resin substrate after forming ITO, the resin substrate is required to have a low coefficient of linear thermal expansion from the viewpoint of dimensional stability.

  In order to realize a resin material having heat resistance and a low linear thermal expansion coefficient, Patent Document 1 discloses a low linear thermal expansion coefficient using a resin having an aromatic diol (in particular, bifer) and a polyarylate structure of dicarboxylic acid. Disclosed is a film having

  However, in the manufacturing method described in Patent Document 1, the resin stretched biaxially is heat-treated in a nitrogen atmosphere at 250 ° C. for 24 hours to thermally relax the resin. Since a lot of time is spent on the heat treatment, the suitability for manufacturing is a problem. Furthermore, if heat treatment for a long time is performed on the film, the film may be oxidized and the transmittance may be lowered in addition to the problem of manufacturing suitability.

JP 2007-254663 A

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a method for producing a polyester resin film with improved production suitability.

  The present inventors pay attention to the combined effect of introducing a plurality of biphenol units using 4,4′-biphenol having at least a substituent at 3,3 ′, 5,5′-, and the production conditions thereof. As a result of extensive research, the inventors have found a method for producing a polyester resin film capable of reducing the linear thermal expansion coefficient and improving the production suitability, and have reached the present invention.

  The method for producing a polyester resin film of the present invention includes a step of preparing a polyester resin containing a structure represented by the general formula (1) and a structure represented by the general formula (2), and (Tg-20 ° C) or more. (Tg + 35 ° C.) A biaxial stretching step of stretching the polyester resin in the longitudinal direction and the transverse direction at a temperature range of (Tg + 35 ° C.) or less by 1.15 times or more and 1.30 times or less, and a heat treatment step of heat-treating the stretched polyester resin. Wherein the heat treatment step is performed in a temperature range of (Tg-30 ° C.) or more and (Tg-10 ° C.) or less while holding both ends in the transverse direction of the stretched polyester resin at regular intervals. After the first heat treatment step and the first heat treatment step, the temperature is lower than that of the first heat treatment step and is in the temperature range of (Tg-50 ° C.) to (Tg-30 ° C.). And a second heat treatment step of performing heat treatment without gripping the end of the transverse stretching polyester resin.

  (Tg: Glass transition temperature of polyester resin)

(In general formula (1), R _{11 to} R ₁₄ each independently represents a hydrogen atom or a substituent, and R _{15 to} R ₁₈ each independently represents a substituent.)

(In the general formula (2), R _{21 to} R ₂₆ each independently represents a hydrogen atom or a substituent, and at least one of the R _{21 to} R ₂₆ represents a substituent.)
A polyester resin containing a structure represented by the general formula (1) and a structure represented by the general formula (2) was used. As a result, the polyester resin is biaxially stretched at a low draw ratio of 1.15 times or more and 1.30 times or less in the longitudinal direction and the transverse direction in a temperature range of (Tg−20 ° C.) to (Tg + 35 ° C.). The orientation of the molecular chain can be easily controlled in two dimensions. By controlling the molecular chains in two dimensions, the linear thermal expansion coefficient of the polyester resin film can be reduced. Moreover, since the draw ratio is small, the stress remaining in the polyester resin is small. Heat treatment (thermal relaxation) time for removing stress can be shortened.

  The stretched polyester resin is subjected to a thermal relaxation treatment in a heat treatment step including a first heat treatment step and a second heat treatment step subsequent thereto. In the first heat treatment step, heat treatment is performed in a temperature range of (Tg−30 ° C.) or more and (Tg−10 ° C.) or less while holding both ends in the transverse direction of the stretched polyester resin at regular intervals. Thereby, it can prevent that a polyester resin shrink | contracts. In the second heat treatment step, heat treatment is performed in a temperature range of (Tg−50 ° C.) or more and less than (Tg−30 ° C.) without gripping the lateral ends of the stretched polyester resin. Thereby, a residual stress can be made small. After the heat treatment while gripping the end portion, the residual stress is relieved by performing the heat treatment without gripping. By performing the two-stage heat treatment, the thermal shrinkage rate of the polyester resin film can be reduced.

  Since the heat treatment time can be shortened, coloring of the polyester resin film due to oxidation, surface roughness, curling of the polyester resin film, and the like can be prevented.

In the method for producing a polyester resin film of the present invention, preferably, in the general formula (1), R ^{15 to} R ¹⁸ are each independently a halogen atom, an alkyl group, an aryl group, or an alkoxy group.

In the method for producing a polyester resin film of the present invention, preferably, in the general formula (1), R ^{15 to} R ¹⁸ are each independently a fluorine atom, a chlorine atom, a bromine atom, an alkyl group having 1 to 4 carbon atoms, A phenyl group or a methoxy group.

In the method for producing a polyester resin film of the present invention, preferably, in the general formula (2), R ^{21 to} R ²⁶ are each independently a hydrogen atom, a halogen atom, an alkyl group, an aryl group, or an alkoxy group.

In the method for producing a polyester resin film of the present invention, preferably, in the general formula (2), R ^{21 to} R ²⁶ are each independently a hydrogen atom, a fluorine atom, a bromine atom, a chlorine atom, or a carbon number of 1 to 4. An alkyl group, a phenyl group or a methoxy group;

  The method for producing a polyester resin film of the present invention preferably contains a structure represented by the following general formula (3).

(In General Formula (3), R ^{31 to} R ³⁸ each independently represents a hydrogen atom or a substituent. X represents a linking group which may have a substituent and may be a part of a ring structure. In some cases, at least one of R ^{31 to} R ³⁴ may be bonded to form a ring structure.)
The method for producing a polyester resin film of the present invention preferably satisfies the following formula (A).

0.2 ≦ (a + b) / (a + b + c) ≦ 0.9
(In formula (A), a represents the content (unit: mol%) of the structure represented by the general formula (1) in the polyester resin, and b is represented by the general formula (2) in the polyester resin. The structure content (unit: mol%) is represented, and c represents the structure content (unit: mol%) represented by the general formula (3) in the polyester resin.
The method for producing a polyester resin film of the present invention preferably contains a structure represented by the following general formula (4).

(In the general formula (4), R ⁴¹ each independently represents a substituent, and m represents an integer of 0 to 3.)
The method for producing a polyester resin film of the present invention preferably contains a structure represented by the following general formula (5).

(In general formula (5), R ⁵¹ and R ⁵² each independently represent a substituent, and n and k each independently represent an integer of 0 to 3.)
In the method for producing a polyester resin film of the present invention, preferably, in the biaxial stretching step, the polyester resin is stretched in the longitudinal direction and the transverse direction with a tension of 10 Mpa or more and 80 Mpa.

  In the method for producing a polyester resin film of the present invention, preferably, in the biaxial stretching step, the polyester resin is stretched in the longitudinal direction and the transverse direction at a temperature range of (Tg + 10 ° C.) to (Tg + 25 ° C.) with a tension of 20 Mpa to 50 Mpa. The film is stretched by 1.20 times or more and 1.25 times or less in each direction.

  In the method for producing a polyester resin film of the present invention, preferably, in the biaxial stretching step, the polyester resin is stretched sequentially or simultaneously in the longitudinal direction and the transverse direction.

  In the method for producing a polyester resin film of the present invention, preferably, in the first heat treatment step, a width direction of the stretched polyester resin is gripped using a tenter.

  In the method for producing a polyester resin film according to the present invention, preferably, in the second heat treatment step, the stretched polyester resin is supported by a roller to grip a lateral end of the stretched polyester resin. Do not heat-treat.

  In the method for producing a polyester resin film according to the present invention, preferably, in the second heat treatment step, the stretched polyester resin is air-lifted so that the heat treatment is performed without gripping the width direction of the stretched polyester resin. Do.

  In the method for producing a polyester resin film of the present invention, preferably, in the step of preparing the polyester resin, the polyester resin is prepared by any one of a melt film forming method and a solution casting method.

  In the method for producing a polyester resin film of the present invention, preferably, the polyester resin film that has undergone the heat treatment step has a linear thermal expansion coefficient of 30 ppm / K or less.

  The method for producing a polyester resin film of the present invention preferably has a heat shrinkage rate of 30 ppm or less at 200 ° C. for 60 minutes.

  In the method for producing a polyester resin film of the present invention, the polyester resin film that has undergone the heat treatment step preferably has a linear thermal expansion coefficient of 20 ppm / K or less and a thermal shrinkage rate of 20 ppm or less at 200 ° C. for 60 minutes.

  In the method for producing a polyester resin film of the present invention, preferably, in the heat treatment step, the first heat treatment step is performed until the stress of the stretched polyester resin becomes substantially constant.

  The polyester resin film of the present invention is a polyester resin film produced by the method for producing a polyester resin film, and has a linear thermal expansion coefficient of 20 ppm / K or less and a thermal contraction rate of 20 ppm or less at 200 ° C. for 60 minutes. The visible light transmittance is 90% or more.

  The polyester resin film of the present invention preferably has a gas barrier layer.

  The polyester resin film of the present invention preferably has a transparent conductive layer.

  The solar cell of this invention is equipped with the said polyester resin film.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacture appropriateness of the manufacturing method of a polyester resin film can be improved.

The block diagram which shows an example of a manufacturing line. The block diagram which shows an example of the apparatus for enforcing a solution casting method. The block diagram which shows an example of the apparatus for extending | stretching simultaneously. The block diagram which shows an example of a heat processing apparatus. The table | surface which shows the conditions and result of an Example.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. The present invention will be described by the following preferred embodiments, but can be modified in many ways without departing from the scope of the present invention, and other embodiments than the present embodiment are utilized. be able to. Accordingly, all modifications within the scope of the present invention are included in the claims.

[Polyester resin]
The polyester resin contains a structure represented by the general formula (1) and a structure represented by the general formula (2).

(In general formula (1), R _{11 to} R ₁₄ each independently represents a hydrogen atom or a substituent, and R _{15 to} R ₁₈ each independently represents a substituent.)

(In the general formula (2), R _{21 to} R ₂₆ each independently represents a hydrogen atom or a substituent, and at least one of the R _{21 to} R ₂₆ represents a substituent.)
Since the structure represented by the general formula (1) and the structure represented by the general formula (2) are contained, the orientation of the molecular chain can be controlled by biaxial stretching with a small stretching ratio. As a result, the linear thermal expansion coefficient of the polyester resin can be reduced.

  The polyester resin contains an ester bond in the main chain. In addition to the structure derived from aromatic diol such as the structure represented by the general formula (1) and the structure represented by the general formula (2), it has a structure derived from a polyvalent carboxylic acid (preferably a dicarboxylic acid). And both have a structure linked by an ester bond.

  Hereinafter, the relationship between the structure and function of the resin will be described in order from the general formula (1) together with the structure that is preferably included.

[Structure derived from aromatic diol]
(Structure represented by general formula (1))

In the general formula (1), R ^{11 to} R ¹⁴ each independently represent a hydrogen atom or a substituent, and R ^{15 to} R ¹⁸ each independently represent a substituent.

In the general formula (1), as a preferable substituent represented by R ^{15 to} R ¹⁸ , an alkyl group (preferably having 1 to 10 carbon atoms, such as a methyl group, an ethyl group, an isopropyl group, a tert-butyl group, etc.). ), Halogen atoms (for example, chlorine atom, bromine atom, iodine atom and the like), aryl groups (preferably having 6 to 20 carbon atoms, for example, phenyl group, biphenyl group, naphthyl group and the like), alkoxy groups (having 1 to 10 carbon atoms). For example, methoxy group, ethoxy group, isopropoxy group and the like), acyl group (preferably having 2 to 10 carbon atoms, for example, acetyl group, propionyl group, butyryl group and the like), acylamino group (having 1 to 10 carbon atoms). Preferably, for example, a formylamino group, an acetylamino group, etc.), a nitro group, a cyano group, a group combining these, and the like can be mentioned.

R ^{15 to} R ¹⁸ are more preferably an alkyl group, a halogen atom, an aryl group, an alkoxy group, a cyano group, or a nitro group, and particularly preferably a halogen atom, an alkyl group, an aryl group, or an alkoxy group, and more particularly Preferred is a fluorine atom, chlorine atom, bromine atom, alkyl group having 1 to 4 carbon atoms, phenyl group or methoxy group, and particularly preferred is a fluorine atom, chlorine atom, methyl group, ethyl group, phenyl group or methoxy group. is there. From the viewpoint of satisfying all of the solubility in an organic solvent, the adjustment to the range of Tg in which the melt film-forming property and heat resistance are balanced, the linear thermal expansion coefficient and the transparency, all are preferable.

[3] The polyester resin according to [1], wherein in the general formula (1), R ^{15 to} R ¹⁸ are independent of each other.

R ^{15 to} R ¹⁸ may be independently different substituents or all may be the same substituent. However, it is preferable that R ^{15 to} R ¹⁸ are all the same substituent. From the viewpoint of

In the general formula (1), R ^{11 to} R ¹⁴ each independently represents a hydrogen atom or a substituent. Preferred examples of the substituent represented by R ^{11 to} R ¹⁴ include the same as the preferred examples of the substituent represented by R ^{15 to} R ¹⁸ . R ^{11 to} R ¹⁴ are more preferably a hydrogen atom, an alkyl group, a halogen atom, an aryl group, an alkoxy group, a cyano group, or a nitro group, and particularly preferably a hydrogen atom, a halogen atom, or an alkyl group, and more particularly Preferably they are a hydrogen atom, a fluorine atom, a chlorine atom, or a methyl group. From the viewpoints of satisfying all of the solubility in an organic solvent, the adjustment to the range of Tg in which the melt film-forming property and the heat resistance are balanced, the linear thermal expansion coefficient and the transparency, R ^{11 to} R ¹⁴ are hydrogen atoms. Or it is preferably a methyl group.

In the general formula (1), when at least one of R ^{11 to} R ¹⁴ is an alkyl group, it is preferable that two of them are alkyl groups (preferably methyl groups) and the remaining two are hydrogen atoms. . In this case, the positions of the two substituents are preferably two positions R ¹¹ and R ¹⁴ or two positions R ¹² and R ¹³ . On the other hand, when at least one of R ^{11 to} R ¹⁴ is a halogen atom, all are preferably the same halogen atom (preferably a fluorine atom or a chlorine atom).

  Although the specific example of General formula (1) is shown below, the structure represented by General formula (1) which can be used by this invention is not limited to these.

(Structure represented by general formula (2))
The polyester resin film of this embodiment contains the structure represented by General formula (2).

(In the general formula (2), R ^{21 to} R ²⁶ represent a hydrogen atom or a substituent, and at least one of the R ^{21 to} R ²⁶ represents a substituent.)
Preferred examples of the substituent represented by R ^{21 to} R ²⁶ include the same as the preferred examples of the substituent represented by R ^{15 to} R ¹⁸ in the general formula (1).

R ^{21 to} R ²⁶ are more preferably a hydrogen atom, an alkyl group, a halogen atom, an aryl group, an alkoxy group, a cyano group, or a nitro group, and particularly preferably a hydrogen atom, a halogen atom, an alkyl group, an aryl group, or an alkoxy group. More preferably a hydrogen atom, a fluorine atom, a bromine atom, a chlorine atom, an alkyl group having 1 to 4 carbon atoms, a phenyl group or a methoxy group, and further preferably a hydrogen atom, a methyl group or a phenyl group. .

In the general formula (2), it is preferable that two of R ^{21 to} R ²⁶ are substituents and the remaining four are hydrogen atoms. In this case, the positions of the two substituents are preferably two positions R ²¹ and R ²⁴ or two positions R ²⁵ and R ²⁶ .

  Specific examples of the structure represented by the general formula (2) are shown below, but the structure represented by the general formula (2) that can be used in the present invention is not limited thereto.

(Structure represented by the general formula (3))
The resin of the present embodiment has an aromatic diol-derived structure, in addition to a biphenol-derived structure such as the structure represented by the general formula (1) and the structure represented by the general formula (2). It may have a structure derived from an aromatic diol.

  Examples of the structure derived from the other aromatic diol that the resin of this embodiment may have include structures derived from bisphenols, and the polyester resin of the present invention is represented by the following general formula (3). It is preferable to contain the structure made.

In the general formula (3), R ^{31 to} R ³⁸ each independently represents a hydrogen atom or a substituent. X may have a substituent and represents a linking group that may be a part of the ring structure. In this case, X may be bonded to at least one of R ^{31 to} R ³⁴ to form a ring structure.

  The polyester resin of the present embodiment has a structure represented by the general formula (3) in addition to the components of the linear structure represented by the general formulas (1) and (2). It is preferable from the viewpoint of further improving the stretchability, particularly the breaking elongation, while achieving both a low linear thermal expansion coefficient.

Preferable R ^{31 to} R ³⁸ in the general formula (3) are a hydrogen atom, an alkyl group (preferably having 1 to 10 carbon atoms, such as a methyl group, an ethyl group, an isopropyl group, a tert-butyl group), a halogen atom. (For example, a chlorine atom, a bromine atom, an iodine atom, etc.), an aryl group (C6-C20 is preferable, for example, a phenyl group, a biphenyl group, a naphthyl group, etc.), an alkoxy group (C1-C10 is preferable, for example, , Methoxy group, ethoxy group, isopropoxy group and the like), acyl group (preferably having 2 to 10 carbon atoms, for example, acetyl group, propionyl group, butyryl group and the like), acylamino group (preferably having 1 to 10 carbon atoms, Formylamino group, acetylamino group, etc.), nitro group, cyano group and the like. More preferred are a hydrogen atom, an alkyl group, a halogen atom, an aryl group, an alkoxy group and a nitro group, and particularly preferred are a hydrogen atom, an alkyl group and a halogen atom.

In general formula (3), X represents a divalent linking group. Examples of X include an alkylene group, an alkylidene group, a perfluoroalkylidene group, an oxygen atom, a sulfur atom, a ketone group, a sulfonyl group, and —NR′— (R ′ is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms). , -CO-NH-. X may be a part of a ring structure, that is, X itself may be a linking group containing a ring, and the benzene is linked to both sides of X together with at least one of R ^{31 to} R ³⁴ . It means that a fused ring may be made with one and / or both of the rings. Examples of the linking group in which X itself includes a ring include a fluorene ring, an indandione ring, an indanone ring, an indene ring, an indan ring, a tetralone ring, an anthrone ring, a cyclohexane ring, a cyclopentane ring, a chroman ring, and 2,3-dihydro Examples thereof include a benzofuran ring, an indoline ring, a tetrahydropyran ring, a tetrahydrofuran ring, and a dioxane ring. Among them, X is preferably an alkylidene group, oxygen atom, sulfur atom, ketone group, amino group or sulfonyl group, and particularly preferably isopropylidene or oxygen atom.

  Further, the structure represented by the general formula (3) is more preferably a structure that can be bent relatively (bending component), that is, X is X in the structure of a benzene ring-X-benzene ring. It is preferable that the ring itself does not contain a ring, and it is particularly preferable that the structure represented by the general formula (3) such as a p-phenylene group does not become a linear component (terphenylene linear structure). Is preferable from the viewpoint of further improving the stretchability, particularly the elongation at break, while achieving both a low linear thermal expansion coefficient.

  In general formula (3), the bonding position of the two oxygen atom linking groups may be anywhere on the benzene ring. Among them, the bonding positions of the two oxygen atom linking groups are preferably the 4th and 4 ′ positions of the benzene ring.

  Specific examples of the structure represented by the general formula (3) are shown below, but the structure represented by the general formula (3) that can be used in the present invention is not limited thereto.

[Structure derived from divalent carboxylic acid]
(Structure represented by formula (4))
In the polyester resin of this embodiment, it is preferable that an aromatic diol and a divalent carboxylic acid are linked by an ester bond. Although there is no restriction | limiting in particular as said divalent carboxylic acid, It is preferable from a viewpoint of reducing a linear thermal expansion coefficient that the resin of this invention contains the structure represented by following General formula (4) at least.

(In the general formula (4), R ⁴¹ each independently represents a substituent, and m represents an integer of 0 to 3.)
The preferred range of the substituent represented by R ⁴¹ are the same as the preferred substituents represented by R ¹¹ to R ^18.

  The m represents an integer of 0 to 3, preferably 0 to 2, more preferably 0 or 1, and particularly preferably 0.

  The polyester resin of the present embodiment has a structure represented by the following general formula (5) and / or the following general formula in addition to the structure represented by the general formula (4) as the structure derived from other divalent carboxylic acids. It preferably has a structure represented by the formula (6), and has either a structure represented by the following general formula (5) or a structure represented by the following general formula (6). It is preferable.

(Structure represented by formula (5))
It is preferable that the polyester resin of the present embodiment contains a structure represented by the following general formula (5) from the viewpoint of finely adjusting in the direction of increasing Tg and improving the melt film-forming property.

(In general formula (5), R ⁵¹ and R ⁵² each independently represent a substituent, and n and k each independently represent an integer of 0 to 3.)
Preferred examples of the substituent groups R ⁵¹ and R ⁵² in the general formula (5) represents, an alkyl group (having 1 to 10 carbon atoms are preferred, for example, a methyl group, an ethyl group, an isopropyl group, a tert- butyl group) , Halogen atoms (for example, chlorine atom, bromine atom, iodine atom and the like), aryl groups (preferably having 6 to 20 carbon atoms, for example, phenyl group, biphenyl group and naphthyl group), alkoxy groups (having 1 to 10 carbon atoms) Preferably, for example, a methoxy group, an ethoxy group, an isopropoxy group, etc., an acyl group (C2-C10 is preferable, for example, an acetyl group, a propionyl group, a butyryl group, etc.), an acylamino group (C1-C10 is preferable). And formylamino group, acetylamino group, etc.), nitro group, cyano group and the like. More preferred are an alkyl group, a halogen atom, an aryl group, an alkoxy group, and a nitro group, and particularly preferred are an alkyl group and a halogen atom.

  In the general formula (5), the position at which the carbonyl group is linked may be any carbon of the naphthalene ring, and two carbonyl groups may be linked to one ring. The carbonyl group is preferably bonded at the 2nd or 3rd position and preferably at the 6th or 7th position, and more preferably at the 2nd or 6th position.

  N and k each independently represents an integer of 0 to 3, n is preferably an integer of 0 to 2, and k is preferably an integer of 0 to 2.

  Specific examples of the structure represented by the general formula (5) are shown below, but the structure represented by the general formula (5) that can be used in the present invention is not limited thereto.

(Structure represented by the general formula (6))
It is preferable that the polyester resin of this embodiment contains the structure represented by General formula (6).

In the general formula (6), R ^{61 to} R ⁶⁴ each independently represents a hydrogen atom or a substituent. )
Preferred substituents represented by R ^{61 to} R ⁶⁴ are the same as the preferred substituents represented by R ^{11 to} R ¹⁸ . R ^{61 to} R ⁶⁴ are preferably hydrogen atoms.

(Other structures)
As long as the polyester resin of this embodiment is a structure derived from an aromatic diol or a divalent carboxylic acid as long as it is not contrary to the gist of the present invention, the polyester resin has a structure other than the structure represented by the general formula (1) to the general formula (6). You may have a structure. In the present specification, the structure derived from the aromatic diol means, for example, the structure represented by the general formula (1), the structure represented by the general formula (2), or the general formula (3). Including structures to be made. In the present specification, the structure derived from the dicarboxylic acid is, for example, a structure represented by the general formula (4), a structure represented by the general formula (5), and a structure represented by the general formula (6). Etc.

  In addition to the ester bond, the resin of the present embodiment may contain an ether bond, a carbonate bond, a sulfone bond, a ketone bond, an imide bond, an amide bond, a urethane bond, or a urea bond, alone or in combination. Good. Other structures that form these bonds include known structures that are known to be able to be included in the polyester resin, as long as they do not contradict the spirit of the present invention.

(Ratio of each structure in the resin)
In the polyester resin of this embodiment, the aromatic diol component preferably satisfies the following formula (A) from the viewpoint of reducing the linear thermal expansion coefficient.

0.2 ≦ (a + b) / (a + b + c) ≦ 0.9 (A)
(In formula (A), a represents the content (unit: mol%) of the structure represented by the general formula (1) in the polyester resin, and b is represented by the general formula (2) in the polyester resin. The structure content (unit: mol%) is represented, and c represents the structure content (unit: mol%) represented by the general formula (3) in the polyester resin.
In particular, when X is a dimethyl-substituted carbon atom, it is preferable that (a + b) / (a + b + c) ≧ 0.2 because the linear thermal expansion coefficient tends to be lowered. The lower limit of (a + b) / (a + b + c) is more preferably 0.4 or more, and particularly preferably 0.5 or more.

  The upper limit of (a + b) / (a + b + c) is preferably 0.9 or less, more preferably 0.8 or less, and preferably 0.75 or less from the viewpoint of transparency and stretchability. Particularly preferred.

  On the other hand, in the polyester resin of the present embodiment, the structure derived from the biphenol and the structure represented by the general formulas (4) and (5) (preferably a structure derived from terephthalic acid) satisfy the following formula (B). The knowledge that it is preferable from the viewpoint of lowering the thermal expansion coefficient was obtained empirically.

A + B + 0.5 × D + 0.5 × E ≧ 80 (B)
(In the formula (B), A represents the content (unit: mol%) of the structure derived from the aromatic diol represented by the general formula (1) with respect to the structure derived from all the aromatic diols contained in the polyester resin. B represents the content (unit: mol%) of the structure derived from the aromatic diol represented by the general formula (2) with respect to all the structures derived from the aromatic diol contained in the polyester resin, and D represents the polyester. Represents the content (unit: mol%) of the structure derived from the dicarboxylic acid represented by the general formula (4) with respect to the structure derived from all the dicarboxylic acids contained in the resin, and E represents all the contents contained in the polyester resin. Represents the content (unit: mol%) of the structure derived from the dicarboxylic acid represented by the general formula (5) with respect to the structure derived from the dicarboxylic acid having linkage positions at the 2nd and 6th positions.
Hereinafter, the left side of the formula (B), that is, the value of A + B + 0.5 × D + 0.50 × E is also referred to as a linear component amount.

  The mathematical meaning of the linear component amount formula (B) is related to the linear thermal expansion coefficient of the film obtained by uniaxial stretching.

  The linear component amount, that is, the value on the left side of the formula (B) is more preferably 80 to 120, and particularly preferably 90 to 120.

  The polyester resin of the present embodiment has a structure (preferably a structure derived from isophthalic acid) in which the weight of the structure represented by the general formula (4) (preferably a structure derived from terephthalic acid) is represented by the general formula (6). It is preferable that it is larger than the weight.

  The weight ratio of the structure represented by the general formula (4) and the structure represented by the general formula (6) is preferably 55:45 to 85:15, and 55:45 to 75:25. It is more preferable that the ratio is 60:40 to 75:25. It is preferable that the weight ratio of the structure represented by the general formula (4) and the structure represented by the general formula (6) is 55:45 to 85:15 because the linear thermal expansion coefficient becomes low.

  In particular, if the weight ratio of the structure represented by the general formula (4) and the structure represented by the general formula (6) is 55:45 or more, the linear thermal expansion coefficient is preferably small, and the weight ratio is 85:15 or less. If so, the melting temperature does not become excessively high, melting becomes easy, and the film obtained after melting is less likely to become cloudy, which is preferable.

  On the other hand, when the weight of the structure represented by the general formula (4) is equal to or smaller than the weight of the structure represented by the general formula (6), the polyester resin of the present embodiment has the general formula (1). It is also preferable that the total content of the structure represented by the formula and the structure represented by the general formula (2) is high.

(Production method of resin)
In general, the resin of the present embodiment can be synthesized using a biphenol derivative, dicarboxylic acid and / or a derivative thereof as a monomer. Further, it may be synthesized as a copolymer using a bisphenol derivative or the like.

  As a general synthesis method of a biphenol derivative having a substituent, mention is made of the method described in Macromolecules, 1996, 29, pages 3727-3735, Journal of Textile Chemistry, Vol. 84, No. 2 (1963), pages 143-145. Can do.

  The dicarboxylic acid derivative can be synthesized by a method similar to the method of introducing a substituent into dialkylnaphthalene and oxidizing the alkyl group. General methods for introducing substituents into dialkylnaphthalenes include Journal of Organic Chemistry, 2003, 68 (22), 8373-8378; Hetreroatom Chemistry, 2001, 12 (4), 287-292; Journal of the Chemical Society, Perkin Transactions 1: Organic and Bio-Organic Chemistry, 1981, (3) 746-750; Journal of the Chemical Society [Section] D: Chemical Communications, (24), 1487, 1969 Can be mentioned.

  As a general method for oxidizing an alkyl group substituted with naphthalene, the method described in Journal of organic Chemistry, 50 (22), pages 4211-4218, 1985 can be exemplified.

  As a general method for synthesizing polyarylate using the above-mentioned monomers, there can be mentioned the methods described in New Polymer Experiments 3 Polymer Synthesis / Reaction (2), Kyoritsu Shuppan (Items 87 to 95).

  Moreover, there is no restriction | limiting in particular about the order which adds each monomer component at the time of a synthesis | combination, Even if it adds all the monomer components simultaneously, only diphenolic acid derivative may be polymerized after polymerizing only biphenol and bisphenol first. .

  Also synthesized by solution polymerization in which divalent carboxylic acid halide and dihydric phenol are reacted in an organic solvent, and melt polycondensation in which divalent carboxylic acid and divalent phenol are reacted in the presence of diallyl carbonate or acetic anhydride. Also good.

(Specific examples of resin)
Although the specific example of the polyester resin of this invention is shown below, the polyester resin which can be used by this invention is not limited to these. In P-1 to P-9, the numbers on the lower right of the parenthesis represent the mol% of each structure in the polyester resin.

(Resin characteristics)
The polyester resin of the present embodiment is a copolymer. The polymerization format may be random number 10, block copolymerization, or other polymerization formats.

  The polyester resin of the present embodiment has a glass transition temperature (Tg) of 170 ° C. to 270 ° C., preferably a glass transition temperature of 180 ° C. to 260 ° C., more preferably a glass of 190 ° C. to 260 ° C. Has a transition temperature.

  Since the polyester resin of this Embodiment has the glass transition temperature of the above-mentioned temperature range, the film made from this polyester resin has high transparency. Moreover, the glass transition temperature of the polyester resin of this embodiment is 170 degreeC or more. Therefore, even when ITO is laminated on a resin substrate using this resin by a high temperature process, the dimensional stability of the resin substrate can be improved.

(Solubility)
The polyester resin of this embodiment is preferably soluble in a solvent such as methylene chloride, chloroform, and tetrahydrofuran. In particular, it is preferable to dissolve in methylene chloride having a low boiling point.

[Production method of polyester resin film]
FIG. 1 shows an example of a production line for a polyester resin film. As shown in FIG. 1, the production line 10 mainly includes a preparation zone for preparing a polyester resin before stretching, a stretching zone for stretching the polyester resin biaxially, and a heat treatment zone for performing a heat treatment on the biaxially stretched polyester resin. And a winding zone for winding the polyester resin film.

(Preparation process of polyester resin)
A polyester resin is prepared using a melt film forming method or a solution casting method. The preparation zone of FIG. 1 shows the preparation of the polyester resin by the melt film forming method.

  First, a resin composition containing the polyester resin of the present embodiment is prepared in the form of pellets. This tree species composition may contain stabilizers such as anti-coloring agents and other additives.

  A pellet-shaped resin composition is charged into the melt extruder 20. As the melt extruder 20, a known melt extruder can be used. In particular, a twin screw extruder is preferable. The temperature of the resin composition in the melt extruder 20 is preferably 250 ° C to 350 ° C, more preferably 260 ° C to 350 ° C, and particularly preferably 270 ° C to 340 ° C. There is no particular limitation on the time for melt kneading.

  Next, the resin composition melt-kneaded by the melt extruder 20 is supplied to the die 22. There is no restriction | limiting in particular as the die | dye 22, A well-known die | dye can be used, A T die, a hanger coat die, etc. can be used. In particular, it is preferable to use a hanger coat die.

  The film-like molten resin composition discharged from the die 22 is supplied onto the casting drum 24. The molten resin composition is cooled and solidified on the casting drum 24. As a method for cooling and solidifying, a touch roll method in which a touch roll is disposed at a position facing the casting drum 24, a multistage method in which a plurality of casting drums are disposed, or the like can be employed.

  In the preparation zone, a solution casting method can be adopted instead of the melt film forming method. FIG. 2 shows the preparation of a polyester resin by the solution casting method. The production line mainly includes a casting band 34 that is stretched over a stock tank 30, a casting die 31, and rotating rollers 32 and 33 to support the casting film, and a peeling roller 35 that peels the casting film from the casting band 34. Is provided.

  The resin composition containing the polyester resin of the present embodiment is dissolved in a solvent to prepare a dope. The dope is introduced into the stock tank 30 and stirred by the stirrer 36. The dope is supplied to the casting die 31 via the pump 37 and the filtering device 38. The dope is supplied from the casting die 31 onto the casting band 34. A casting film is formed on the casting band 34. While the casting film is moved by the casting band 34, the casting film is dried by a drying wind or the like. After the solvent is removed to a predetermined concentration or less, the casting film is peeled off from the casting band 34 by the peeling roller 35. About a solution casting method, it is not limited to the above-mentioned apparatus, For example, it can replace with the casting band 34 and a casting drum can be used.

(Drawing process of polyester resin)
In the stretching zone of the production line 10, the longitudinal stretching device 50 and the lateral stretching device 60 are arranged in this order from the upstream side to the downstream side in the film transport direction. The longitudinal stretching apparatus 50 includes two nip rolls 52 and 54. The downstream nip roll 54 transports the polyester resin at a transport speed faster than that of the upstream nip roll 52. Thereby, the polyester resin is stretched in the longitudinal direction.

  In the present embodiment, the polyester resin is stretched by 1.15 times or more and 1.30 times or less in the longitudinal direction in a temperature range of (Tg−20 ° C.) or more and (Tg + 35 ° C.) or less by the longitudinal stretching apparatus 50. By using the polyester resin of the present embodiment, the molecular chain can be easily oriented in one direction (longitudinal direction) at a low draw ratio of 1.15 times or more and 1.30 times or less. At this time, the polyester resin is longitudinally stretched with a tension of 10 Mpa or more and 80 Mpa.

  The temperature range of longitudinal stretching is preferably (Tg + 10 ° C.) or more and (Tg + 25 ° C.) or less, the longitudinal stretching ratio is preferably 1.20 times or more and 1.25 times or less, and the tension of longitudinal stretching is 20 Mpa or more. It is preferable that it is 50 Mpa or less.

  The draw ratio is defined by the size of the film after stretching relative to the size of the original film.

  The longitudinally stretched polyester resin is stretched in the lateral direction (direction orthogonal to the transport direction) by the lateral stretching device 60. A tenter device can be suitably used as the transverse stretching device 60. For example, both ends of the longitudinally stretched polyester resin in the width direction are held by clips, and the polyester resin is stretched in the lateral direction by moving the clip.

  In the present embodiment, the polyester resin is stretched by 1.15 times or more and 1.30 times or less in the longitudinal direction in a temperature range of (Tg−20 ° C.) or more and (Tg + 35 ° C.) or less by the transverse stretching device 60. By using the polyester resin of the present embodiment, the molecular chain can be easily oriented in one direction (lateral direction) at a low draw ratio of 1.15 times or more and 1.30 times or less. At this time, the polyester resin is laterally stretched with a tension of 10 Mpa or more and 80 Mpa.

  The transverse stretching temperature range is preferably (Tg + 10 ° C.) or more and (Tg + 25 ° C.) or less, the transverse stretching ratio is preferably 1.20 times or more and 1.25 times or less, and the transverse stretching tension is 20 Mpa or more. It is preferable that it is 50 Mpa or less.

  The draw ratio is calculated in the same manner as described above.

  By biaxially stretching the polyester resin, the molecular chain is oriented in two directions, the longitudinal direction and the transverse direction. Since the film is drawn at a low draw ratio, the stress remaining in the polyester resin can be reduced. As a result, the heat treatment time for removing the residual stress can be shortened.

  In the stretching zone of FIG. 1, the longitudinal stretching and the lateral stretching of the polyester resin were sequentially performed. Without being limited to this, longitudinal stretching and lateral stretching can be performed simultaneously.

  FIG. 3 is a plan view of a tenter device 70 that performs simultaneous biaxial stretching. The tenter device 70 shown in the figure is a device that simultaneously stretches in the longitudinal and lateral directions while being conveyed to a polyester resin. The tenter device 70 includes two rails 71 and 72 and endless chains 73 and 74. The two rails 71 and 72 are disposed on both sides of the polyester resin. The interval between the two rails 71 and 72 is arranged so as to increase from the upstream side to the downstream side in the transport direction.

  The endless chains 73 and 74 are respectively spanned between upstream driving sprockets 75 and 76 and downstream driven sprockets 77 and 78. The endless chains 73 and 74 are guided by the two rails 71 and 72. By driving the driving sprockets 75 and 76, the endless chains 73 and 74 run around while being guided by the two rails 71 and 72.

  A large number of clips 80, 80... Are attached to the endless chains 73, 74 at a predetermined pitch. The side edges of the polyester resin are gripped by the clip 80. The clip 80 moves with the endless chains 73 and 74. The pitch of the clips 80 (the interval between the clips 80 in the transport direction) changes as the clips 80 move. The interval on the downstream side is wider than the interval on the upstream side. Further, with respect to the interval between the two rails 71 and 72, the interval on the downstream side is wider than the interval on the upstream side.

  The endless chains 73 and 74 are driven while the side edges of the polyester resin are gripped by the clips 80. Thereby, the polyester resin is simultaneously stretched in the longitudinal direction and the transverse direction.

  In the tenter device 70, the film is stretched by 1.15 times or more and 1.30 times or less simultaneously in the longitudinal direction and the transverse direction in a temperature range of (Tg−20 ° C.) to (Tg + 35 ° C.). At this time, the polyester resin is longitudinally stretched with a tension of 10 Mpa or more and 80 Mpa.

  The temperature range of simultaneous stretching is preferably (Tg + 10 ° C.) or more and (Tg + 25 ° C.) or less, the magnification of simultaneous stretching is preferably 1.20 times or more and 1.25 times or less, and the tension of simultaneous stretching is 20 Mpa or more. It is preferable that it is 50 Mpa or less. The simultaneous stretching ratio is calculated in the same manner as described above.

  The polyester resin of this embodiment has a structure in which molecular chains are ideally aligned by stretching in the vicinity of Tg. Thereby, molecular chains can be oriented in the above temperature range and with a small draw ratio.

(Polyester resin heat treatment process)
A heat treatment apparatus 90 is disposed in the heat treatment zone of the production line 10. The heat treatment apparatus 90 includes at least a first heat treatment region 92 and a second heat treatment region 94. In the first heat treatment region 92, the polyester resin is subjected to heat treatment while gripping both ends in the lateral direction of the polyester resin at regular intervals in a temperature range of (Tg-30 ° C.) to (Tg-10 ° C.).

  Since both ends of the lateral direction of the polyester resin are held at regular intervals, it is possible to prevent the polyester resin from rapidly contracting. The polyester resin is subjected to heat treatment in the first heat treatment region 92 until the stress of the polyester resin becomes substantially constant. The reason why the temperature range is (Tg-30 ° C.) or more and (Tg-10 ° C.) or less is that if it is Tg or more, the molecular chain may return rapidly and break.

  Here, “stress is substantially constant” means that the variation in residual stress is within a predetermined range. Specifically, a polyester resin sample is collected at the end of the first heat treatment region, a small sample is cut out in the width direction, and the thermal contraction rate is measured. Can do.

  Next, in the second heat treatment region 94, the lateral end portion of the polyester resin in a temperature range lower than the heat treatment temperature of the first heat treatment region 92 and not lower than (Tg-50 ° C.) and not higher than (Tg-30 ° C.). The polyester resin is subjected to a heat treatment without holding it. The heat treatment is performed until the stress of the polyester resin becomes substantially constant in the first heat treatment region 92. Therefore, in the second heat treatment region 94, the polyester resin is not gripped by the lateral ends of the polyester resin. Even if heat treatment is applied to the polyester resin, the polyester resin hardly shrinks. Since the heat treatment temperature of the second heat treatment region 94 is lower than the heat treatment temperature of the first heat treatment region 92 and the lateral ends of the polyester resin are not gripped, heat treatment can be performed without curling the polyester resin.

  By making the first heat treatment temperature higher than the second heat treatment temperature, it is possible to prevent the film from curling. Moreover, residual stress can be removed by not gripping the end portion in the second heat treatment.

  The heat treatment time in the heat treatment zone is from 1 minute to 120 minutes, preferably from 3 minutes to 60 minutes, and particularly preferably from 3 minutes to 20 minutes.

  FIG. 4 is a plan view of the heat treatment apparatus 90. A heat treatment apparatus 90 shown in the figure is an apparatus for performing heat treatment on a polyester resin while being conveyed to the polyester resin. In the first heat treatment region 92, two rails 95 and 96 and endless chains 97 and 98 are arranged. The two rails 95 and 96 are arranged on both sides of the polyester resin. The distance between the two rails 95 and 96 is set to be a constant distance from the upstream side to the downstream side in the transport direction. Here, the constant interval is a ratio of the longest interval between the two rails 95, 96 to the shortest interval between the two rails 95, 96 (longest interval / shortest interval) of 1 to 1.1. It means that. Therefore, the constant interval does not mean that the interval between the two rails 95 and 96 is the same in all sections, but is more preferably constant.

  Endless chains 97 and 98 are respectively spanned between upstream driving sprockets 99 and 100 and downstream driven sprockets 101 and 102. The endless chains 97 and 98 are guided by two rails 95 and 96. By driving the driving sprockets 99 and 100, the endless chains 97 and 98 run around while being guided by the two rails 95 and 96.

  A large number of clips 103, 103... Are attached to the endless chains 97, 98 at a predetermined pitch. The clip 103 grips the side edge of the polyester resin. The clip 103 moves with the endless chains 97 and 98. The pitch of the clips 103 (the interval between the clips 103 and 103 in the transport direction) is substantially constant.

  The endless chains 97 and 98 are driven while the side edges of the polyester resin are gripped by the clip 103. Thereby, heat processing is performed in the state where the both ends of the width direction of the polyester resin were gripped.

  A guide roller 104 is provided in the second heat treatment region 94. The gripping of both ends by the clip 103 is released, and the polyester resin is conveyed while being supported by the guide roller 104. The polyester resin is heat-treated in a state where the end portion of the polyester resin is not gripped, that is, in a so-called free state.

  In the second heat treatment region 94 of FIG. 4, the conveyance of the polyester resin by the guide roller 104 is shown. Instead of conveyance by the guide roller 104, conveyance by air levitation can be performed. For example, air levitation conveyance can be carried out by disposing a bar in the second heat treatment region 94 that injects gas from a plurality of injection ports to float the polyester resin from the injection surface.

  By performing the above-described two-stage heat treatment on the stretched polyester resin in the heat treatment zone, the thermal shrinkage rate of the polyester resin film can be reduced. This is to completely remove the residual stress reduced to the limit by the fixed annealing.

  In the present embodiment, an example in which the stretching process and the heat treatment process are performed using different apparatuses has been described. However, the present invention is not limited to this. For example, the first heat treatment is performed on the polyester resin in the tenter device by holding the polyester resin at a constant interval in the tenter device after transverse stretching or simultaneous biaxial stretching in the tenter device. Can be applied.

(Winding process)
The heat-treated polyester resin film is wound on a film roll by a winder 200.

(Characteristics of film)
By orienting molecular chains by biaxial stretching, the linear thermal expansion coefficient of the polyester resin film can be made 30 ppm / K or less. The linear thermal expansion coefficient of the polyester resin film is preferably 20 ppm / K or less. When the linear thermal expansion coefficient of the polyester resin film is 30 ppm / K or less, when an inorganic thin film is laminated on the film, it is possible to control the generation of cracks due to the difference in expansion coefficient during heating and the warping of the film.

  By performing the heat treatment twice on the biaxially stretched polyester resin, the thermal shrinkage of the polyester resin film can be reduced to 30 ppm or less at 200 ° C. for 60 minutes. The heat shrinkage rate of the polyester resin film is preferably 20 ppm or less at 200 ° C. for 60 minutes. When the heat shrinkage is 30 ppm or less at 200 ° C. for 60 minutes, cracking of the upper electrode can be prevented.

(Functional layer)
Other layers may be formed on the surface of the polyester resin film of the present embodiment depending on the application. Further, for the purpose of improving the adhesion to other parts, the film surface may be subjected to treatment such as saponification, corona treatment, flame treatment, glow discharge treatment and the like. Further, an anchor layer may be provided on the film surface.

-Gas barrier layer-
In the polyester resin film of the present embodiment, a gas barrier layer can be laminated on at least one side in order to suppress gas permeability. As a preferable gas barrier layer, for example, a metal oxide mainly composed of one or more metals selected from the group consisting of silicon, aluminum, magnesium, zinc, zirconium, titanium, yttrium and tantalum, silicon, aluminum, Mention may be made of films formed of metal nitrides of boron or mixtures thereof. Among these, the main component is silicon oxide having a ratio of the number of oxygen atoms to the number of silicon atoms of 1.5 to 2.0 in terms of gas barrier properties, transparency, surface smoothness, flexibility, film stress, cost, and the like. A film formed of a metal oxide is good. The gas barrier layer made of these inorganic compounds is formed by vapor deposition such as sputtering, vacuum deposition, ion plating, plasma CVD, Cat-CVD, etc., by depositing a material from the vapor phase to form a film. Can be made. Among these, the sputtering method and the Cat-CVD method that can provide particularly excellent gas barrier properties are preferable. Further, the temperature may be raised to 50 to 250 ° C. while the gas barrier layer is provided.

  The thickness of the gas barrier layer is preferably 10 to 300 nm, and more preferably 30 to 200 nm.

  The gas barrier layer may be provided on the same side or the opposite side to the transparent conductive layer described later.

Gas barrier properties of the polyester resin film of the present embodiment, it is preferable, 0~3g / m ² · day that 40 ° C., water vapor permeability measured at 90% relative humidity is 0~5g / m ² · day More preferably, it is more preferably 0 to ² g / m ² · day. Further, 40 ° C., the oxygen permeability measured at 90% relative humidity is preferably ^{0~1ml / m 2 · day · atm} (0~1 × 10 5 ml / m 2 · day · Pa), 0 -0.7 ml / m ² · day · atm (0 to 0.7 × 10 ⁵ ml / m ² · day · Pa) is more preferable, and 0 to 0.5 ml / m ² · day · atm (0 More preferably, it is -0.5 * 10 < ⁵ > ml / m < ² > * day * Pa). If the gas barrier performance is within the above range, for example, when used in an organic EL display device or a liquid crystal display device, it is preferable that deterioration of the EL element due to water vapor and oxygen can be substantially eliminated.

  In order to improve the gas barrier performance, it is preferable to form a defect compensation layer adjacent to the gas barrier layer. As the defect compensation layer, for example, (1) an inorganic oxide layer produced by using a sol-gel method as described in US Pat. No. 6,171,663 and Japanese Patent Application Laid-Open No. 2003-94572, (2) US Pat. The organic material layer described in the specification can be used. These defect compensation layers can be prepared by vapor deposition under vacuum and then curing with ultraviolet rays or electron beams, or by applying and then curing with heating, electron beams, ultraviolet rays or the like. When the defect compensation layer is produced by a coating method, various conventional coating methods such as spray coating, spin coating, and bar coating can be used.

  The polyester resin film of this embodiment may be provided with an inorganic barrier layer, an organic barrier layer, an organic-inorganic hybrid barrier layer, etc. for the purpose of imparting chemical resistance.

-Transparent conductive layer-
A transparent conductive layer may be laminated on at least one side of the film of the present invention. A known metal film, metal oxide film, or the like can be applied as the transparent conductive layer. Among these, a metal oxide film having excellent transparency, conductivity, and mechanical properties is preferably used as the transparent conductive layer. The metal oxide film is, for example, a metal oxide film of indium oxide, cadmium oxide or tin oxide to which tin, tellurium, cadmium, molybdenum, tungsten, fluorine, zinc, germanium or the like is added as an impurity; an oxide to which aluminum is added as an impurity Examples thereof include metal oxide films such as zinc and titanium oxide. Among them, an indium oxide thin film mainly composed of tin oxide and containing 2 to 15% by mass of zinc oxide is excellent in transparency and conductivity, and is preferably used.

  The transparent conductive layer can be formed by any method as long as it can form a target thin film. For example, a vapor deposition method that forms a film by depositing a material from the vapor phase, such as sputtering, vacuum deposition, ion plating, plasma CVD, and Cat-CVD, is suitable. The film can be formed by the methods described in Japanese Patent Laid-Open Nos. 2002-322561 and 2002-361774. Among these, the sputtering method is preferable from the viewpoint that particularly excellent conductivity and transparency can be obtained.

  The preferred degree of vacuum of the sputtering method, vacuum deposition method, ion plating method, or plasma CVD method is 0.133 mPa to 6.65 Pa, preferably 0.665 mPa to 1.33 Pa. Before forming the transparent conductive layer, it is preferable to subject the base film to a surface treatment such as plasma treatment (reverse sputtering) or corona treatment. Moreover, you may heat up to 50-200 degreeC during providing the transparent conductive layer.

  The film thickness of the transparent conductive layer thus obtained is preferably 20 to 500 nm, and more preferably 50 to 300 nm.

  The surface electrical resistance of the transparent conductive layer measured at 25 ° C. and 60% relative humidity is preferably 0.1 to 200Ω / □, and more preferably 0.1 to 100Ω / □. More preferably, it is 0.5-60Ω / □. Moreover, the light transmittance of the transparent conductive layer is preferably 80% or more, more preferably 83% or more, and further preferably 85% or more.

[Image display device]
The polyester resin film of this embodiment described above can be used for an image display device. Here, the type of the image display device is not particularly limited, and conventionally known ones can be exemplified. Moreover, the flat panel display excellent in display quality is producible using the polyester resin film of this embodiment as a board | substrate. Examples of the flat panel display include a liquid crystal display device, a plasma display, organic electroluminescence (EL), inorganic electroluminescence, a fluorescent display tube, a light emitting diode, and a field emission type. Besides these, a conventional glass substrate has been used. It can be used as a substrate instead of a display-type glass substrate. Furthermore, the polyester resin film of this embodiment can be applied to uses such as solar cells and touch panels in addition to flat panel displays. The touch panel can be applied to, for example, those described in JP-A-5-127822, JP-A-2002-48913, and the like.

  Moreover, the thin film transistor TFT can be produced on the polyester resin film of the present embodiment. The TFT can be manufactured by a known method disclosed in Japanese Patent Application Laid-Open No. 11-102867, Japanese Patent Application Laid-Open No. 10-512104, and Japanese Patent Application Laid-Open No. 2001-68681. Further, these substrates may have a color filter for color display. The color filter may be manufactured using any method, but is preferably manufactured using a photolithography technique.

  The TFT manufactured in the present invention may be an amorphous silicon TFT or a polycrystalline silicon TFT. An annealing method by laser irradiation is preferably used for polycrystallizing amorphous silicon.

  Examples of the method for forming silicon of the semiconductor layer of the TFT include a sputtering method, a plasma CVD method, an ICP-CVD method, a Cat-CVD method, and the like, but the sputtering method is preferable. By manufacturing by a sputtering method, the hydrogen concentration in the silicon thin film can be reduced, and peeling of the silicon layer due to laser irradiation for polycrystallization can be prevented.

  Intrinsic silicon thin film, impurity silicon thin film, silicon nitride thin film, silicon oxide thin film, etc. necessary for TFT fabrication can be formed on the polyester resin film of this embodiment by plasma CVD, but the substrate temperature at that time is 250 ° C. or less. It is preferable.

  ITO and IZO can be formed on the pixel electrode by sputtering. The heat treatment temperature for lowering the resistivity is preferably 250 ° C. or lower.

  The structure of the TFT manufactured in the present invention may be any structure such as a channel etching type, an etching stopper type, a top gate type, and a bottom gate type.

  When the polyester resin film of the present embodiment is used as a substrate for liquid crystal display devices or the like, the resin composition constituting the film is preferably an amorphous polymer in order to achieve optical uniformity. Furthermore, for the purpose of controlling retardation (Re) and its wavelength dispersion, resins having different signs of intrinsic birefringence can be combined, or resins having a large (or small) wavelength dispersion can be combined.

  The polyester resin film of this embodiment is preferably laminated by combining different resin compositions from the viewpoint of controlling retardation (Re) and improving gas permeability and mechanical properties. The preferred combination of different resin compositions is not particularly limited, and any of the resin compositions described above can be used.

  A reflective liquid crystal display device generally has a configuration of a lower substrate, a reflective electrode, a lower alignment film, a liquid crystal layer, an upper alignment film, a transparent electrode, an upper substrate, a λ / 4 plate, and a polarizing film in order from the bottom. . Among these, the film of the present invention can be used as a transparent electrode and / or an upper substrate. In the case of color display, it is preferable to further form a color filter layer between the reflective electrode and the lower alignment film, or between the upper alignment film and the transparent electrode.

  The transmissive liquid crystal display device includes, in order from the bottom, a backlight, a polarizing plate, a λ / 4 plate, a lower transparent electrode, a lower alignment film, a liquid crystal layer, an upper alignment film, an upper transparent electrode, an upper substrate, a λ / 4 plate, and It generally has a configuration of a polarizing film. Among these, the film of the present invention can be used as an upper transparent electrode and / or an upper substrate. In the case of color display, it is preferable to further provide a color filter layer between the lower transparent electrode and the lower alignment film, or between the upper alignment film and the transparent electrode.

  The type of liquid crystal layer (liquid crystal cell) is not particularly limited, but TN (Twisted Nematic), IPS (In-Plane Switching), FLC (Ferroelectric Liquid Crystal), AFLC (Anti-ferroelectric Liquid Crystal), OCB (Optically Compensated Bend) Various display modes such as STN (Super Twisted Nematic), VA (Vertically Aligned), and HAN (Hybrid Aligned Nematic) have been proposed. There has also been proposed a display mode in which the display mode is orientation-divided. The film of the present invention is also effective for use in a display mode liquid crystal display device. In addition, the present invention is effective when used in any of a transmissive, reflective, and transflective liquid crystal display device.

As for the liquid crystal cell and the liquid crystal display device, JP-A-2-176625, JP-B-7-69536, MVA (SID97, Digestof tech. Papers).
(Proceedings) 28 (1997) 845), SID99, Digest of tech. Papers (Proceedings) 30 (1999) 206), JP-A-11-258605, SURVAIVAL (Monthly Display, Vol. 6, No. 3 (1999) 14), PVA (Asia Display 98, Proc. Of the-18th). -Inter. Display res. Conf. (Preliminary Book) (1998) 383), Para-A (LCD / PDP International 99), DDVA (SID98, Digest of tech. Papers (Preliminary Book) 29 (1998) 838), EOC ( SID98, Digest of tech. Papers (Preliminary Collection) 29 (1998) 319), PSHA (SID98, Digestof tech. Papers (Preliminary Collection) 29 (1998) 1081), RFFMH. AsiaDisplay 98, Proc. Of the-18th-Inter.Displays.Conf. No. 123478, WO98 / 48320 pamphlet, Japanese Patent No. 3022477, WO00 / 65384 pamphlet and the like.

  The polyester resin film of this embodiment can be suitably used for organic EL display applications. The specific layer structure of the organic EL display device includes anode / light emitting layer / transparent cathode, anode / light emitting layer / electron transport layer / transparent cathode, anode / hole transport layer / light emitting layer / electron transport layer / transparent cathode, Anode / hole transport layer / light emitting layer / transparent cathode, anode / light emitting layer / electron transport layer / electron injection layer / transparent cathode, anode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection Examples include layer / transparent cathode. The organic EL display device that can use the polyester resin film of the present embodiment has a direct current (which may include an alternating current component if necessary) voltage (usually 2 to 40 V) or a direct current between the anode and the cathode. Light emission can be obtained by application. Regarding driving of these light emitting elements, for example, JP-A-2-148687, JP-A-6-301355, JP-A-5-290080, JP-A-7-134558, JP-A-8-234665, and JP-A-8-240447. US Pat. Nos. 5,828,429 and 6023308, Japanese Patent No. 2784615, and the like can be used.

  As a full color display method of the organic EL display device, any method such as a color filter method, a three-color independent light emission method, and a color conversion method may be used.

[Example]
EXAMPLES Hereinafter, an Example is given and this invention is demonstrated in detail. 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.

(Polymer synthesis)
In a synthesis tank equipped with a stirrer, 3,3 ′, 5,5′-tetramethyl-4,4′-bishydroxybiphenyl 1.056 t, 3,3′-dimethyl-4,4′-bishydroxybiphenyl 0 .468t, bisphenol A 0.996t, hydrosulfite sodium 36Kg, tetra-n-butylammonium chloride 160Kg, methylene chloride 39m ³ , and water 45m ³ were added and stirred and dissolved under a nitrogen stream. A solution of terephthalic acid chloride 1.78 t and 2,6-naphthalenedicarboxylic acid chloride 0.536 t in methylene chloride 18 m ³ was added to the solution.

It was further added dropwise 2 mol / L sodium hydroxide aqueous solution of 11.4 m ³ and a mixture of water 3m ³ to over 1 hour at 15 to 20 ° C.. After stirring for 3 hours after completion of the dropping, the reaction solution was transferred to another synthesis tank, and 0.18 m ³ of acetic acid and 180 m ³ of ethyl acetate were slowly added. The obtained polymer powder was collected by filtration, washed successively with ethyl acetate 100 m ³ , water 100 m ³ and methanol 100 m ³ and dried to obtain 3.64 t of a polyester resin.

  As a result of measurement by GPC (THF solvent; polystyrene conversion (manufactured by Tosoh Corporation, HLC-8120GPC)), the weight average molecular weight was 105000. The obtained polymer was dissolved in methylene chloride and cast on a glass plate. Thereafter, the glass transition temperature of the film having a thickness of 100 μm obtained by drying was measured using a TMA8310 (manufactured by Rigaku Denki Co., Ltd., Thermo Plus series) and found to be 260 ° C.

(Film formation / heat treatment)
The synthesized polymer was kneaded for 10 minutes using a kneader set at 350 ° C., extruded into a noodle shape, and then formed into a cylindrical pellet having a diameter of 3 mm and a length of 5 mm. The obtained pellets were dried at 110 ° C. with a vacuum dryer, and the water content was adjusted to 0.1% or less.

  The pellet-shaped resin composition produced above is put into a melt extruder adjusted from 280 ° C. (inlet temperature) to 330 ° C. (outlet temperature), melted at 300 ° C., and then cast at 120 ° C. through a hanger die. It was melt extruded onto the drum. After cooling and solidifying on the casting drum, the film having a film thickness of 100 μm was peeled off and continuously conveyed to the stretching zone for stretching treatment. The both ends of the film carried into the stretching zone were gripped by clips, and the distance between the clips at both ends and the distance between adjacent clips were gradually opened as the film traveled, and the film was stretched simultaneously in the vertical and horizontal directions until the set stretching ratio was reached.

  The stretched film was further continuously conveyed to the heat treatment zone. In the first half of the heat treatment zone (first heat treatment region), both ends of the film were again held by clips, and the heat treatment was performed while the distance between the clips at both ends was made substantially constant. Further, in the latter half of the heat treatment zone (second heat treatment region), the sheet was conveyed by a guide roller without applying tension to both ends. The residence time in the heat treatment zone was about 15 minutes. The heat-treated film was wound up at a speed of about 10 m / min in the winding zone.

  About Tests 1-33, conditions, such as the temperature of an extending | stretching zone and a heat processing zone, were changed as shown in FIG. 5, and the polyester resin film was produced.

<Glass transition temperature (Tg)>
Using a differential scanning calorimeter (DSC6200, manufactured by Seiko Co., Ltd.), the Tg of the film sample was measured in nitrogen at a temperature rising temperature of 10 ° C./min. Tg was 260 ° C.

<Linear thermal expansion coefficient>
A film sample (19 mm × 5 mm) was prepared and measured using TMA (manufactured by Rigaku Corporation, TMA8310). The measurement speed was 3 ° C./min. Three samples were measured and the average value was used. The measurement was performed in a temperature range of 25 ° C. to 300 ° C., and the linear thermal expansion coefficient was calculated in the range of 25 ° C. to 200 ° C. at the time of temperature increase.

<Heat shrinkage>
A film sample (19 mm × 5 mm) was prepared and measured using TMA (manufactured by Rigaku Corporation, TMA8310). The measurement speed was 3 ° C./min. Three samples were measured and the average value was used. In the measurement, the temperature was raised from 25 ° C. to 200 ° C., held at 200 ° C. for 60 minutes, and the amount of shrinkage occurring during that time was calculated.

<Break etc.>
The film sample was visually checked for cracks and the like. Cracking means that the film has been in the day, and curl means that when the cut film is placed on a horizontal base, the entire surface is not in contact with the horizontal base, or a surface that is not in contact with it is generated. To do.

<Evaluation>
A linear thermal expansion coefficient of 20 ppm / K or less was rated as 、, 30 ppm / K or less as ○, and a value greater than 30 ppm / K as x. When the thermal shrinkage rate was 200 ° C. and 60 minutes, 20 ppm or less was rated as “◎”, 30 ppm or less as “◯”, and a value larger than 30 ppm as “x”. When no cracks occurred, the linear expansion coefficient was 係数, and the thermal shrinkage was ◎, the evaluation was ◎. When no cracks or the like occurred, the linear expansion coefficient was ◎, and the thermal shrinkage was ◯, the evaluation was ◯. When no cracks occurred, the linear expansion coefficient was ◯, and the thermal shrinkage was ◎, the evaluation was ◯. When the occurrence of cracks or the like, the linear expansion coefficient was x, and the thermal contraction rate was x, the evaluation was x.

<Evaluation results>
The results obtained for tests 1 to 33 are listed in the table of FIG. For tests 1 to 12, the stretching temperature is in the temperature range of (Tg−20 ° C.) or more and (Tg + 35 ° C.) or less, the stretching ratio is in the range of 1.15 to 1.3 times, and the tension is in the range of 10 to 80 Mpa. The first heat treatment temperature is in the temperature range of (Tg-30 ° C) to (Tg-10 ° C) and the second heat treatment temperature is (Tg-50 ° C) to (Tg-30 ° C). Since the temperature range was satisfied, an evaluation of ◯ or higher was obtained. In particular, tests 1 to 4 in which the stretching temperature is in the temperature range of (Tg + 10 ° C.) to (Tg + 25 ° C.), the stretching ratio is in the range of 1.20 to 1.25 times, and the tension is in the range of 20 to 50 Mpa. A rating of ◎ was obtained.

  In Tests 13 and 14, since the draw ratio exceeded 1.30, the thermal shrinkage rate exceeded 30 (ppm) and was evaluated as x. In Test 15, since the tension exceeded 80 Mpa, the thermal shrinkage rate exceeded 30 (ppm) and was evaluated as x. In Test 16, since the tension was smaller than 10 Mpa, the coefficient of linear thermal expansion exceeded 30 (ppm / K) and was evaluated as x. In Test 17, since the stretching temperature was lower than (Tg−20 ° C.) and the tension exceeded 80 Mpa, the heat shrinkage rate exceeded 30 (ppm) and was evaluated as x. In Test 18, since the stretching temperature was lower than (Tg−20 ° C.) and the stretching ratio was smaller than 1.15, the heat shrinkage rate exceeded 30 (ppm), and the evaluation was x. In Tests 19 and 20, since the draw ratio was smaller than 1.15, the linear thermal expansion coefficient exceeded 30 (ppm / K) and was evaluated as x.

  For Tests 21 to 33, the stretching temperature was 270 ° C., the stretching ratio was 1.25 times, the tension was 50 Mpa, and the first heat treatment temperature and the second heat treatment temperature were changed. For Tests 21 to 27, the second heat treatment temperature is set lower than the first heat treatment temperature, the first heat treatment temperature is set to a temperature range of (Tg-30 ° C) to (Tg-10 ° C), and the second heat treatment temperature is set to (Tg Since it was set to −50 ° C.) or more and (Tg−30 ° C.) or less, evaluation of ◯ or more was obtained.

  For Tests 28 and 29, the first heat treatment temperature and the second heat treatment temperature were the same, so curling occurred and the evaluation was x. In Tests 30 to 32, the second heat treatment temperature was higher than the first heat treatment temperature, so curling occurred and the evaluation was x. For Test 33, since the first heat treatment temperature exceeded (Tg-10 ° C), cracks occurred and the evaluation was x.

  DESCRIPTION OF SYMBOLS 10 ... Production line, 20 ... Melt extruder, 22 ... Die, 24 ... Casting drum, 50 ... Longitudinal drawing apparatus, 60 ... Lateral drawing apparatus, 90 ... Heat treatment apparatus, 92 ... First heat treatment area, 94 ... Second Heat treatment area

Claims (24)

Preparing a polyester resin containing the structure represented by the general formula (1) and the structure represented by the general formula (2);
A biaxial stretching step in which the polyester resin is stretched at a temperature range of (Tg−20 ° C.) or more and (Tg + 35 ° C.) or less in a longitudinal direction and a transverse direction by 1.15 times or more and 1.30 times or less, respectively;
A heat treatment step of heat treating the stretched polyester resin;
A first heat treatment in which the heat treatment step is performed in a temperature range of (Tg-30 ° C.) or more and (Tg-10 ° C.) or less while holding both ends in the transverse direction of the stretched polyester resin at regular intervals. And a stretched polyester resin having a temperature lower than that of the first heat treatment step and in a temperature range of (Tg-50 ° C.) to (Tg-30 ° C.) following the step and the first heat treatment step. A method for producing a polyester resin film, comprising: a second heat treatment step in which heat treatment is performed without gripping the lateral ends of the resin.
(Tg: Glass transition temperature of polyester resin)

(In general formula (1), R _{11 to} R ₁₄ each independently represents a hydrogen atom or a substituent, and R _{15 to} R ₁₈ each independently represents a substituent.)

(In the general formula (2), R _{21 to} R ₂₆ each independently represents a hydrogen atom or a substituent, and at least one of the R _{21 to} R ₂₆ represents a substituent.) In the general formula (1), wherein R ¹⁵ to R ¹⁸ are each independently a halogen atom, an alkyl group, method for producing a polyester resin film according to claim 1 is an aryl group or an alkoxy group. 2. The polyester according to claim 1, wherein in the general formula (1), R ^{15 to} R ¹⁸ are each independently a fluorine atom, a chlorine atom, a bromine atom, an alkyl group having 1 to 4 carbon atoms, a phenyl group, or a methoxy group. A method for producing a resin film. In the general formula (2), wherein R ²¹ to R ²⁶ are each independently a hydrogen atom, a manufacturing method of a halogen atom, an alkyl group, a polyester resin film according any one of claims 1 an aryl group or an alkoxy group having 3 . In the general formula (2), R ^{21 to} R ²⁶ are each independently a hydrogen atom, a fluorine atom, a bromine atom, a chlorine atom, an alkyl group having 1 to 4 carbon atoms, a phenyl group, or a methoxy group. 4. The method for producing a polyester resin film according to any one of 3 above. The manufacturing method of the polyester resin film in any one of Claim 1 to 5 containing the structure represented by following General formula (3).

(In General Formula (3), R ^{31 to} R ³⁸ each independently represents a hydrogen atom or a substituent. X represents a linking group which may have a substituent and may be a part of a ring structure. In some cases, at least one of R ^{31 to} R ³⁴ may be bonded to form a ring structure.) The manufacturing method of the polyester resin film of Claim 6 which satisfy | fills following formula (A).
0.2 ≦ (a + b) / (a + b + c) ≦ 0.9
(In formula (A), a represents the content (unit: mol%) of the structure represented by the general formula (1) in the polyester resin, and b is represented by the general formula (2) in the polyester resin. The structure content (unit: mol%) is represented, and c represents the structure content (unit: mol%) represented by the general formula (3) in the polyester resin. The manufacturing method of the polyester resin film in any one of Claim 1 to 7 containing the structure represented by following General formula (4).

(In the general formula (4), R ⁴¹ each independently represents a substituent, and m represents an integer of 0 to 3.) The manufacturing method of the polyester resin film in any one of Claim 1 to 8 containing the structure represented by following General formula (5).

(In general formula (5), R ⁵¹ and R ⁵² each independently represent a substituent, and n and k each independently represent an integer of 0 to 3.)   The method for producing a polyester resin film according to any one of claims 1 to 9, wherein in the biaxial stretching step, the polyester resin is stretched in a longitudinal direction and a transverse direction with a tension of 10 Mpa or more and 80 Mpa.   In the biaxial stretching step, in the temperature range of (Tg + 10 ° C.) to (Tg + 25 ° C.), the polyester resin is stretched in the longitudinal direction and the transverse direction at a tension of 20 Mpa to 50 Mpa, respectively, 1.20 times to 1.25 times. The manufacturing method of the polyester resin film in any one of Claim 1 to 10 extended | stretched.   The method for producing a polyester resin film according to any one of claims 1 to 11, wherein in the biaxial stretching step, the polyester resin is stretched in the longitudinal direction and the transverse direction sequentially or simultaneously.   The method for producing a polyester resin film according to any one of claims 1 to 12, wherein in the first heat treatment step, a width direction of the stretched polyester resin is gripped using a tenter.   The heat treatment is performed according to any one of claims 1 to 13, wherein in the second heat treatment step, the stretched polyester resin is supported by a roller so that a heat treatment is performed without gripping a lateral end portion of the stretched polyester resin. Manufacturing method of polyester resin film.   The polyester resin film according to any one of claims 1 to 14, wherein in the second heat treatment step, the stretched polyester resin is floated by air to perform a heat treatment without gripping a width direction of the stretched polyester resin. Manufacturing method.   The method for producing a polyester resin film according to any one of claims 1 to 15, wherein in the step of preparing the polyester resin, the polyester resin is prepared by any one of a melt film forming method and a solution casting method.   The method for producing a polyester resin film according to any one of claims 1 to 16, wherein the polyester resin film that has undergone the heat treatment step has a linear thermal expansion coefficient of 30 ppm / K or less.   The manufacturing method of the polyester resin film of Claim 17 in which the polyester resin film which passed through the said heat processing process has a heat shrinkage rate of 30 ppm or less in 200 degreeC and 60 minutes.   The method for producing a polyester resin film according to claim 18, wherein the polyester resin film that has undergone the heat treatment step has a linear thermal expansion coefficient of 20 ppm / K or less and a thermal shrinkage of 20 ppm or less at 200 ° C for 60 minutes.   The method for producing a polyester resin film according to any one of claims 1 to 19, wherein, in the heat treatment step, the first heat treatment step is performed until the stress of the stretched polyester resin becomes substantially constant.   A polyester resin film manufactured by the method for manufacturing a polyester resin film according to claim 1, having a linear thermal expansion coefficient of 20 ppm / K or less and a thermal shrinkage of 20 ppm or less at 200 ° C. for 60 minutes. A polyester resin film having a visible light transmittance of 90% or more.   The polyester resin film according to claim 21, further comprising a gas barrier layer.   The polyester resin film according to claim 21 or 22, comprising a transparent conductive layer.   A solar cell provided with the polyester resin film in any one of Claims 21-23.

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