KR101496514B1 - Method of producing polyester film, polyester film for solar cell, and solar cell module - Google Patents

Abstract

A process for producing a polyester film having high hydrolysis resistance, a polyester film for solar cell having high hydrolysis resistance, and a solar cell module having excellent stability of power generation efficiency.
(1) A nonwoven fabric comprising 10 to 50 mass% of a fluff having a bulk density of 0.2 to 0.7, a water content of 20 to 100 ppm, an intrinsic viscosity of 0.70 dl / g to 1.2 dl / g, A raw material resin feeding step of feeding a polyester raw material resin having a temperature of 100 to 160 DEG C to a raw material feed port of a twin screw extruder; and a step of feeding the polyester raw material resin into a molten resin, A molten resin discharging step of discharging the resin at a temperature of Tm + 20 占 폚 to Tm + 30 占 폚 with respect to the melting point Tm of the polyester raw resin; and a molding step of molding the molten resin into a film form to be.

Description

TECHNICAL FIELD [0001] The present invention relates to a method for producing a polyester film, a polyester film for a solar cell, and a solar cell module,

The present invention relates to a production method of a polyester film, a polyester film for a solar cell, and a solar cell module.

In recent years, development of a polyester film having various properties and functionalities has been required to be applicable to various applications, depending on a synthesis method of a resin, a processing method, a film formation method and the like. For example, a resin film for use in a solar cell is required to have properties such as durability corresponding to the use environment of a solar cell exposed to rain, transparency not to hinder the power generation efficiency of the solar cell, . As a resin film for a solar cell, a solar cell encapsulant (simply referred to as "encapsulant") for encapsulating a solar cell element (cell) and a back sheet for a solar cell that protects the encapsulant from the outside are known have.

The polyester generally has a large number of carboxyl groups and hydroxyl groups on the surface thereof and tends to undergo hydrolysis in an environment in which water exists and tends to deteriorate with time. Therefore, it is required that the polyester used in a solar cell module or the like which is always placed in an environment exposed to weathering, such as outdoors, is suppressed in its hydrolysis ability.

In order to impart hydrolysis resistance to the polyester resin, it is conceivable to reduce the terminal COOH which is a catalyst of the hydrolysis reaction. Since the terminal COOH is generated by heating at the time of melting, in the case of forming a melt film by a plasticizing melt extruder, it is important to alleviate the heat generation at the time of melting.

To solve this problem, for example, in order to suppress heat generation and achieve mass production, a vent-type twin-screw extruder having an inner diameter of 140 mm or more is used and the ratio Q of the extrusion amount Q per unit time to the screw rotation number N / N is within a certain range (see, for example, Patent Document 1).

In the method for producing a polyester composition in which at least a part of polyester and a metal salt of an aliphatic carboxylic acid are independently added from a raw material feed port in order to drop the metal salt adhering to the surface of the pipe, And a bulk density of 0.6 or less (see, for example, Patent Document 2).

In the case of using polyethylene terephthalate (PET) as the polyester, in order to suppress the amount of acetaldehyde generated during the melt molding of PET, the water content in the polyester resin is adjusted to 60 to 500 ppm, A molding method of a polyester resin is known (see, for example, Patent Document 3).

Further, in order to suppress the deterioration due to the retention in the extruder and to produce a polytrimethylene terephthalate resin composition excellent in color tone, a facility for feeding the polytrimethylene terephthalate and the modifying material in advance was substituted with an inert gas And a process for producing polytrimethylene terephthalate is disclosed in which an inert gas having a supply amount (volume) or more of each of polytrimethylene terephthalate and modifier is continuously fed to the equipment See Patent Document 4).

Japanese Patent Publication No. 3577178 Japanese Patent Application Laid-Open No. 10-329188 Japanese Patent Application Laid-Open No. 07-205257 Japanese Laid-Open Patent Publication No. 2004-307552

However, in each of the production methods described in Patent Documents 1 to 4, it has been difficult to obtain a polyester film having weather resistance, particularly high hydrolysis resistance, which can withstand exposure to rain.

The object of the present invention is to provide a polyester film production method for producing a polyester film having high hydrolysis resistance, a polyester film for solar cell having high hydrolysis resistance, and a solar cell module excellent in stability of power generation efficiency .

In order to achieve the above object, the following invention is provided.

The present invention provides a process for producing a polyester resin composition, which comprises the steps of: (1) mixing 10 to 50 mass% of fluff having a bulk density of 0.2 to 0.7, having a water content of 20 ppm to 100 ppm and an intrinsic viscosity of 0.70 dl / g to 1.2 dl / A feedstock supply step of feeding a polyester raw material resin having a melting point of from -20 ° C to 160 ° C to a raw material feed port of a twin screw extruder, and a step of supplying a molten resin from a twin screw extruder, At a temperature of Tm + 20 占 폚 to Tm + 30 占 폚 with respect to the melting point Tm of the polyester raw material resin; and a molding step of molding the molten resin into a film.

The melting point Tm of the polyester raw material resin in the present invention refers to a value obtained by measurement of differential scanning calorimetry. When the polyester raw material resin is composed of plural kinds of polyester resins, , It indicates the highest melting point. Therefore, when a plurality of polyester raw material resins are used, Tm means the melting point of the high melting point component. For example, when polyethylene terephthalate (PET) and CHDM-based polyester resin (for example, polycyclohexanedimethylene terephthalate (PCT)) are used as the polyester raw material resin, the melting point of PET is 255 占 폚, and PCT Has a melting point of 278 캜. When a mixture of PET and PCT is used, the " melting point Tm of the polyester raw resin "

&Lt; 2 &gt; The twin screw extruder according to any one of claims 1 to 3, wherein the twin screw extruder is provided with at least one vent hole and a vent hole nearest to the raw material supply port, A method for producing a polyester film according to the above item <1>, comprising a first nitrogen gas supply port for supplying a nitrogen gas in a boat.

<3> The twin-screw extruder according to any one of <1> to <4>, wherein the twin screw extruder has a screw having a kneading portion for plasticizing the polyester material resin, and a second nitrogen gas supply port located in the kneading portion for supplying nitrogen gas to the polyester material resin Is the polyester film production method according to &lt; 1 &gt;

<4> The method for producing a polyester film according to <2> or <3>, wherein the feeding rate of the nitrogen gas in the nitrogen gas supply port is 2 m / min to 50 m / min.

<5> The kneading section, the shear rate in the kneading clearance 500 s ^-1 ~ 2000 s ^- is ^one of the <3> or polyester film production method according to the item <4>.

&Lt; 6 &gt; The method for producing a polyester raw material according to any one of &lt; 6 &gt; to &lt; 6 &gt;, wherein a cyclic carbodiimide compound having a cyclic structure in which one carbodiimide group and one of the carbodiimide groups, , And 0.05% by mass to 20% by mass, and melt-kneading the melted resin to obtain a polyester resin composition according to any one of <1> to <5>.

<7> A polyester film for a solar cell produced by the method for producing a polyester film according to any one of <1> to <6>.

&Lt; 8 &gt; The polyimide resin composition according to &lt; 8 &gt;, wherein the structure derived from 1,4-cyclohexanedimethanol is contained in an amount of 0.1 to 100 mol% based on the total amount of the structure derived from the diol compound &Gt;.

The layer containing the CHDM-based polyester preferably has a structure derived from 1,4-cyclohexane dimethanol in an amount of 0.1 mol% to 20 mol% or 80 mol% to 100 mol% based on the total amount of the structure derived from the diol compound % &Lt; / RTI &gt;

A solar cell module comprising: a front substrate having transparency to which sunlight is incident; a cell structure portion formed on the front substrate and having an encapsulating material for encapsulating the solar cell element and the solar cell element; Is a solar cell module comprising a polyester film for a solar cell according to any one of &lt; 7 &gt; to &lt; 9 &gt;

According to the present invention, it is possible to provide a polyester film production method for producing a polyester film having high hydrolysis resistance, a polyester film for a solar cell having high hydrolysis resistance, and a solar cell module having excellent stability of power generation efficiency.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a schematic view showing a configuration example of a twin-screw extruder for carrying out a production method of a polyester film according to the present invention. FIG.
Fig. 2 is a view showing an example of a flow for implementing the method for producing a polyester film according to the present invention. Fig.

Hereinafter, the method for producing the polyester film of the present invention will be described in detail. In the present specification, &quot; &quot; is used to mean that the numerical values described before and after the numerical value are included as a lower limit value and an upper limit value.

<Production method of polyester film>

The polyester film production method of the present invention comprises 10 to 50 mass% of fluff having a bulk density of 0.2 to 0.7, a water content of 20 ppm to 100 ppm, an intrinsic viscosity of 0.70 dl / g to 1.2 dl / g and a temperature of 100 ° C to 160 ° C to a raw material feed port of the twin screw extruder, and a step of feeding the raw material resin into a molten resin by melt-kneading the polyester raw material resin, A molten resin discharge step of discharging the molten resin from the twin screw extruder at a temperature of Tm + 20 ° C to Tm + 30 ° C relative to the melting point Tm of the polyester raw material resin; and a molding step of molding the molten resin into a film form .

A film excellent in weather resistance can be obtained by molding polyester by suppressing thermal deterioration of a polyester raw resin (hereinafter simply referred to as &quot; raw resin &quot;). The cause of thermal degradation of the raw material resin is hydrolysis or oxidative decomposition of polyester.

Therefore, it is important to reduce the amount of terminal COOH as a catalyst of the hydrolysis reaction while reducing the heat generation amount of the raw resin, or to reduce the amount of water or oxygen contained in the raw resin as much as possible. In particular, it is preferable that the difference ΔAV between the amount of terminal COOH of the raw resin and the amount of terminal COOH of the melt-extruded film is made small (for example, 3 eq / t (equivalent / ton;

However, when the water content of the raw resin is reduced to 100 ppm or less by drying, the heat of the raw resin in the biaxial extruder (hereinafter simply referred to as &quot; extruder &quot;) becomes large and the resin temperature may rise.

Therefore, if the raw material resin is excessively dried, thermal degradation of the raw material resin due to temperature rise tends to occur, and the? AV increases even if the water content of the raw material resin decreases.

On the other hand, when the temperature of the extruder is lowered, the temperature of the outlet (outlet) of the extruder for discharging the molten raw resin (molten resin) is lowered, but the heat generation in the plasticizing portion (kneading portion) So that the thermal degradation of the molten resin sometimes proceeds.

In the production of a polyester film, a raw material resin having an intrinsic viscosity of 0.70 dl / g or more and a high viscosity is generally used in order to suppress the hydrolysis of the raw material resin in the extruder. However, the larger the intrinsic viscosity of the raw material resin, the larger the molecular weight of the raw material resin. The higher the intrinsic viscosity, the greater the friction due to kneading in the extruder, and the raw material resin tends to generate heat.

Thus, even if the water content is lowered or the intrinsic viscosity is increased for the purpose of hydrolysis of the raw resin, AV of the raw resin tends to increase due to heat generation of the raw resin in the extruder.

Therefore, after decreasing the water content of the raw material resin or raising the intrinsic viscosity, it was further necessary to attain AV reduction or? AV decrease of the raw material resin.

To solve such a problem, in the method for producing a polyester film of the present invention, a specific amount of fluff having a predetermined bulk density is added to a polyester raw material resin, and the temperature of the polyester raw material resin when supplied to an extruder is adjusted to a specific temperature , It has been found that the friction of the molten resin in the extruder, particularly in the plasticizer, can be reduced to reduce the resin temperature.

That is, since the raw material resin contains fluff having a large volume, the friction of the raw resin in the extruder is reduced, and by heating the temperature of the raw resin to a predetermined temperature, the resin tends to be softened, The heat generation in the extruder can be suppressed.

On the other hand, the raw material resin is melted and kneaded in an extruder to become a molten resin and discharged to the outside from the discharge port of the extruder. At this time, by suppressing the heat generation of the raw resin, The raw material resin of cosmetic junk remains as a foreign substance. If the molten resin discharged from the extruder contains a foreign substance, there may be a case where the molten resin is unstretched due to the presence of a foreign substance when the film is formed into a film, particularly when the film is stretched.

Therefore, in the method for producing a polyester film of the present invention, it is possible to prevent such foreign matter from remaining in the molten resin by heating the molten resin to a predetermined temperature and discharging the molten resin from the extruder.

Therefore, by using the above-described constitution of the method for producing a polyester film of the present invention, a polyester film having high hydrolysis resistance can be produced.

First, the resin supplying step will be described.

[Feedstock supply step]

The raw material resin supplying step includes a step of supplying 10 to 50 mass% of fluff having a bulk density of 0.2 to 0.7, a water content of 20 ppm to 100 ppm, an intrinsic viscosity of 0.70 dl / g to 1.2 dl / g, And a polyester raw material resin having a temperature of 100 ° C to 160 ° C is supplied to a raw material feed port of the twin screw extruder.

That is, the polyester raw material resin to be fed to the raw material feed port of the twin screw extruder contains 10 to 50 mass% of fluff having a bulk density of 0.2 to 0.7, a water content of 20 to 100 ppm, The viscosity is 0.70 dl / g to 1.2 dl / g, and the temperature is 100 ° C to 160 ° C.

First, the fluff will be described, and then the polyester raw resin will be described.

- Fluff -

Plufran refers to pulverized debris of a polyester film, in particular crushed debris of a film formed during film formation of a polyester film, and crushed debris of a used polyester film for recycling.

In the production method of the polyester film of the present invention, a fluff having a bulk density of 0.2 to 0.7 is used, and is contained in the raw resin in a range of 10% by mass to 50% by mass with respect to the total mass of the raw resin.

The bulk density refers to the density (mass per unit volume) obtained by dividing the mass of a powder in a predetermined shape by putting the powder in a constant volume in a constant volume container and dividing the mass by the volume at that time. The smaller the bulk density, . The bulk density of the fluff can be measured by a method according to JIS K 7365: 1999, "Method for Determining the Apparent Density of Materials Which Can Be Followed by a Plastic-Specified Funnel".

In the method for producing a polyester film according to the present invention, it is preferable that a polyester resin having a low water content and a high intrinsic viscosity and having a bulk density of 0.2 to 0.7 is contained in an amount of 10% by mass to 50% It is possible to suppress the heat generation in the extruder while maintaining the advantages of the raw material resin having a low water content and the high intrinsic viscosity.

If the bulk density of the fluff is less than 0.2, the raw material resin is clogged (also referred to as a bridge) in the raw material feed port of the extruder and the raw resin can not be melted. When the bulk density of the fluff exceeds 0.7, It is not possible to suppress the exothermic reaction of the resin.

The fluff having a bulk density of 0.2 to 0.7 is obtained by crushing the polyester film to be used. A crushed piece produced in the production of the polyester film may also be used.

The bulk density of the fluff is preferably 0.2 to 0.6 from the viewpoints of extrusion stability (bridge suppression) of the raw material resin and inhibition of shearing heat generation.

The fluff is contained in the raw resin in a range of 10% by mass to 50% by mass with respect to the total mass of the raw resin. If the content of the fluff is less than 10 mass%, the heat generation of the raw resin in the extruder can not be suppressed, and if it exceeds 50 mass%, the AV of the raw resin increases.

The content of the fluff in the raw material resin is preferably 20% by mass to 50% by mass from the viewpoint of decreasing? AV and 15% by mass to 40% by mass from the viewpoint of breaking elongation.

The size of the fluff is not particularly limited as long as the fluff has a bulk density within the above range, and the thickness is preferably 20 to 5000 占 퐉. Among them, a range of 100 to 1000 mu m, more preferably a range of 100 to 500 mu m, is more preferable from the viewpoint of avoiding excessive decrease in the bulk density and excessively decreasing the bulk density and avoiding insufficient melting.

Further, in order to further reduce the amount of terminal COOH of the polyester film to be formed, it is preferable that the variation of the size of the fluff is small. For example, as for the thickness of the pulverizing piece, the deviation is preferably within ± 100% More preferably within ± 50%, and further within ± 10%. In the case of using the pulverized pieces, the fluctuation of the amount of terminal COOH of the obtained polyester film can be suppressed to be low by suppressing the size deviation such as the thickness to be small.

- Polyester raw resin -

The polyester raw material resin (also simply referred to as raw material resin) used in the production method of the polyester film of the present invention contains the aforementioned fluff and has a water content of 20 ppm to 100 ppm and an intrinsic viscosity of 0.70 dl / g To 1.2 dl / g, and the temperature is 100 ° C to 160 ° C.

The raw resin is not particularly limited as long as it is polyester, and examples thereof include PET (polyethylene terephthalate) and PBT (polybutylene terephthalate).

First, physical properties of the raw resin such as water content and intrinsic viscosity will be described, and then the polyester resin constituting the raw resin will be described.

(Water content)

The raw material resin has a water content of 20 ppm to 100 ppm.

If the water content of the raw resin is less than 20 ppm, the heat generation of the raw resin in the extruder becomes large and the difference? AV between the terminal COOH amount of the raw resin and the terminal COOH amount of the melt extruded film increases. When the water content exceeds 100 ppm, &Lt; / RTI &gt;

The water content of the raw material resin is preferably 30 ppm to 70 ppm.

The water content of the raw resin can be adjusted by the drying temperature of the raw resin, the drying time, and the like.

(Intrinsic viscosity, IV)

The intrinsic viscosity (IV) of the raw material resin is 0.70 dl / g to 1.2 dl / g. If the IV of the raw material resin is less than 0.70, the hydrolysis resistance of the raw material resin is lowered, and if IV exceeds 1.2, heat generation can not be sufficiently suppressed.

Particularly when the raw material resin is polyethylene terephthalate (PET), the IV of the raw PET resin is preferably 0.70 dl / g to 0.85 dl / g, more preferably 0.70 dl / g to 0.80 dl / g.

The IV of the raw material resin can be adjusted by the polymerization method and the polymerization conditions of the polyester resin, and the solid phase polymerization is carried out after the liquid phase polymerization to obtain a polyester resin having an intrinsic viscosity IV of 0.70 dl / g to 1.2 dl / g, Can be obtained.

Further, the intrinsic viscosity (IV), the ratio η _r of the solution viscosity (η) and the solvent viscosity (η _0); boiling point of minus one (= η / η ₀ relative viscosity) is also (η _sp = η _r -1) The value divided by the concentration is the extrapolated value to the zero concentration state. IV is obtained by dissolving the polyester in a mixed solvent of 1,1,2,2-tetrachloroethane / phenol (= 2/3 [mass ratio]) using a Ubero's type viscometer and measuring the solution viscosity at 25 ° C .

(Crystallization temperature)

In addition, prior to solid-state polymerization to be described later, it is preferable to crystallize in order to prevent fusion of the raw material resin, and a preferable crystallization temperature at the time of crystallization is 140 ° C or more. More preferably 140 ° C or more and 175 ° C or less, and further preferably 140 ° C or more and 170 ° C or less. The crystallization time is preferably from 10 minutes to less than 10 hours, more preferably from 20 minutes to 8 hours, and still more preferably from 40 minutes to 7 hours. At this time, it is preferable to flow an inert gas such as nitrogen.

(Terminal COOH amount, AV)

The raw material resin preferably has an end COOH amount (Acid Value AV) of 25 eq / t (equivalent / ton) or less, more preferably 15 eq / t or less. When the raw material resin having the terminal COOH amount of 25 eq / t or less is used because the increase of the terminal COOH amount is suppressed to 3 eq / t or less when the raw material resin is melt-extruded by the method of the present invention, the terminal COOH A polyester film having a small amount and high hydrolysis resistance can be obtained. However, from the viewpoint of, for example, adhesion between the resin and the adherend, the amount of terminal COOH of the starting resin is preferably 2 eq / t or more. Also, &quot; eq / t &quot; represents the molar equivalent per tonne.

The amount of terminal COOH of the starting resin can be adjusted by the water content of the starting resin, the melting temperature in the extruder, the kneading time and the like.

The terminal COOH amount is a value measured by the following method. That is, after 0.1 g of the raw resin is dissolved in 10 ml of benzyl alcohol, chloroform is further added to obtain a mixed solution, and phenol red indicator is added dropwise thereto. This solution is titrated with a reference liquid (0.01 N, KOH-benzyl alcohol mixed solution), and the terminal carboxyl group amount is obtained from the drop amount.

When a plurality of kinds of resins are mixed and used, the amount of terminal COOH of the starting resin indicates the amount in the mixed state. For example, when one or more kinds of the pellets are mixed as a polyethylene terephthalate (PET), or a chip material, which is pulverized debris of a PET film, is mixed, the total amount of the terminal COOH amount of the pellet or the terminal COOH amount of the pellet, Of the total amount of COOH.

(Melting point, Tm)

The melting point Tm of the raw material resin is preferably in the range of 250 占 폚 to 290 占 폚. The melting point Tm is a value obtained by differential scanning calorimetry. Hereinafter, when a plurality of Tm are used by using a plurality of raw material resins, the highest melting point is referred to as a melting point Tm of the raw resin. When the raw resin is a mixture of plural resins, it is preferable that the average value of the melting points of the respective resins is within the above range.

(Bulk density)

The bulk density of the raw material resin is preferably 0.7 to 0.9 or less from the viewpoints of the extrusion stability of the raw material resin and the suppression of heat generation in the shearing. When the bulk density is 0.7 or more, extrusion can be carried out more stably. When the bulk density is 0.9 or less, local heat generation can be effectively suppressed.

(Resin temperature)

The raw resin is heated to 100 ° C to 160 ° C and supplied to a raw material feed port (extruder inlet) of the extruder.

That is, the temperature of the raw resin in the raw material feed port of the extruder is 100 ° C to 160 ° C. By setting the temperature of the raw material resin within the above range, it is possible to suppress the friction of the raw material resin and suppress heat generation in the extruder.

If the temperature of the raw material resin is less than 100 占 폚, the heat of friction during melting of the raw material resin increases, and when it exceeds 160 占 폚, decomposition reaction of the raw material proceeds.

The temperature of the raw resin is preferably 120 to 150 ° C.

Next, the polyester resin constituting the raw material resin will be described.

(Polyester resin)

The polyester resin constituting the raw material resin can be obtained by esterification reaction and / or transesterification reaction of a dicarboxylic acid or an ester derivative thereof with a diol compound by a known method.

Examples of the dicarboxylic acid or its ester derivatives include malonic acid, succinic acid, glutaric acid, adipic acid, suberic acid, sebacic acid, dodecanedioic acid, dimeric acid, , Aliphatic dicarboxylic acids such as azelaic acid, methylmalonic acid and ethylmalonic acid, adamantanedicarboxylic acid, norbornenedicarboxylic acid, isosorbide, cyclohexanedicarboxylic acid, decalindicarboxylic acid Aliphatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalene dicarboxylic acid, 1,5-naphthalene dicarboxylic acid, 2,6-naphthalene dicarboxylic acid, 1,8 Naphthalene dicarboxylic acid, 4,4'-diphenyldicarboxylic acid, 4,4'-diphenyl ether dicarboxylic acid, 5-sodium sulfoisophthalic acid, phenylindoxicarboxylic acid, anthracenedicarboxylic acid Aromatic dicarboxylic acids such as phenanthric acid, phenanthric dicarboxylic acid, and 9,9'-bis (4-carboxyphenyl) There may be mentioned a carboxylic acid or its ester derivative.

As the dicarboxylic acid, at least one of aromatic dicarboxylic acids is preferably used. More preferably, an aromatic dicarboxylic acid as a main component is contained in the dicarboxylic acid. Preferred aromatic dicarboxylic acids are terephthalic acid (TPA) and 2,6-naphthalene dicarboxylic acid (2,6-NDCA), and they are preferably the main components. The term &quot; main component &quot; means that the proportion of the aromatic dicarboxylic acid in the dicarboxylic acid component is 80 mass% or more, respectively.

In the synthesis of the polyester resin, dicarboxylic acid other than 2,6-NDCA and TPA may be contained. More preferred dicarboxylic acids are isophthalic acid (IPA) and the like. The amount of IPA to be added is preferably 0 mol% to 15 mol%, more preferably 0 mol% to 12 mol%, and still more preferably 0 mol% to 9 mol%, of the total dicarboxylic acid.

Examples of the diol compound include aliphatic diols such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,2-butanediol and 1,3- 1,3-benzene dimethanol, 1,4-benzene dimethanol, 9,9'-bis (4-tert-butylphenol) And aromatic diols such as hydroxyphenyl) fluorene.

As the diol compound, at least one of aliphatic diols is preferably used. The aliphatic diol is preferably ethylene glycol (EG) or 1,4-cyclohexanedimethanol (CHDM), and contains at least one of ethylene glycol and 1,4-cyclohexanedimethanol as main components.

Also, the main component means that the ratio of the sum of ethylene glycol and 1,4-cyclohexane dimethanol in the diol compound is 80 mass% or more.

For the esterification reaction and / or the transesterification reaction, conventionally known reaction catalysts can be used. Examples of the reaction catalyst include an alkali metal compound, an alkaline earth metal compound, a zinc compound, a lead compound, a manganese compound, a cobalt compound, an aluminum compound, an antimony compound, a titanium compound and a phosphorus compound. Usually, it is preferable to add an antimony compound, a germanium compound, and a titanium compound as polymerization catalysts at any stage before the production of the polyester is completed. With such a method, for example, when a germanium compound is taken as an example, it is preferable to add the germanium compound powder as it is.

Preferable polyesters are polyethylene terephthalate (PET), polyethylene-2,6-naphthalate (PEN), and more preferably PET. The PET is preferably polymerized using one or more kinds selected from a germanium (Ge) based catalyst, an antimony (Sb) based catalyst, an aluminum based catalyst and a titanium (Ti) Is a Ti-based catalyst.

-CHDM-based polyester resin-

From the viewpoint of increasing the mechanical strength of the polyester film and improving the heat resistance, it is preferable that the polyester resin is a CHDM-based polyester resin containing a structure derived from 1,4-cyclohexane dimethanol.

The CHDM-based polyester resin refers to a polyester resin using 1,4-cyclohexanedimethanol (CHDM) as a part or the whole of a diol compound used for obtaining a polyester resin, and 1,4-cyclo And a structure derived from hexane dimethanol. Specific examples thereof include polycyclohexanedimethylene terephthalate (PCT) and the like.

When the CHDM-based polyester resin has a structure derived from 1,4-cyclohexane dimethanol (also referred to as CHDM derived) in the molecular structure, it is possible to improve the weather resistance of the produced polyester film, and 1,4-cyclohexane If the ratio of the structure derived from dimethanol is in the following range, it is more excellent in weatherability.

The proportion of the structure derived from 1,4-cyclohexanedimethanol in the polyester resin is preferably from 0.1 to 100 mol%, more preferably from 0.1 to 20 mol%, or from 80 to 80 mol%, based on the total amount of the structural units derived from the diol compound. More preferably 100 mol%, still more preferably 0.5 mol% to 16 mol% or 83 mol% to 98 mol%, particularly preferably 1 mol% to 12 mol% or 86 mol% to 96 mol% .

In a more preferred embodiment, the presence of two regions having a low-structure (0.1 to 20 mol%) and a high (80 to 100 mol%) structure derived from CHDM is particularly likely to form crystals in this region, It is easy to form a &quot; tie chain &quot; In these two regions, the polyester resin is easy to take a crystal structure, and high mechanical strength and high heat resistance are easily exhibited.

Further, the presence of such a CHDM-derived structure in the molecular structure of the polyester resin increases the orientation of the polyester molecules, thereby promoting the production of tie chains. This is thought to be due to the following reasons.

Since CHDM has a ring structure, it is hard to bend like EG (ethylene glycol), and it is rigid. For this reason, polyester molecules are liable to be oriented by an external force applied to the polyester resin due to stretching of the polyester resin or the like. Since the oriented polyester molecules tend to form crystals, it is easy to form a tie chain.

In the synthesis of the CHDM-based polyester resin, at least 1,4-cyclohexanedimethanol (CHDM) is used as the diol compound, and a diol compound other than CHDM may be used. At this time, for the diol compounds other than CHDM, the aforementioned diol compounds can be mentioned. Of these, ethylene glycol is preferably used.

As the dicarboxylic acid used for synthesizing the CHDM-based polyester resin, the dicarboxylic acid or its ester derivative already described is used.

In the case of obtaining a CHDM-based polyester resin, it is preferable to use at least terephthalic acid as the dicarboxylic acid.

As the dicarboxylic acid, isophthalic acid (IPA) may be added in addition to terephthalic acid. The amount of IPA is preferably 0 mol% to 15 mol%, more preferably 0 mol% to 12 mol%, still more preferably 0 mol% to 9 mol%, of the total dicarboxylic acid.

CHDM generally has a melt viscosity higher than that of the PET resin and an intrinsic viscosity of 0.70 dl / g to 1.20 dl / g.

Polycyclohexanedimethylene terephthalate (PCT) containing a 1,4-cyclohexane dimethanol (CHDM) structure can be produced, for example, by using the method described in paragraphs [0089] to [0090], [0120] ] Can also be preferably used.

Further, the polyethylene-2,6-naphthalate (PEN) can be produced by using the method described in, for example, Japanese Patent Application Laid-Open No. 2011-153209, Japanese Patent Application Publication No. 2008-39803, paragraphs [0046] and [0060] The described method can also be preferably used.

The Ti-based catalyst has a high reaction activity and can lower the polymerization temperature. Therefore, it is possible to suppress the generation of COOH by thermally decomposing PET particularly during the polymerization reaction. In the present invention, it is preferable to adjust the terminal COOH amount of the polyester film to 30 eq / ton or less.

The production of Ti catalyst-based PET obtained by polymerization using a Ti-based catalyst is disclosed, for example, in Japanese Patent Application Laid-Open Nos. 2005-340616, 2005-239940, 2004-319444, JP-A No. 3436268, Japanese Patent Publication No. 3979866, Japanese Patent Publication No. 3780137, Japanese Patent Application Laid-Open No. 2007-204538, and the like.

It is preferable to carry out the polymerization by using the titanium (Ti) compound in an amount of 1 ppm or more and 30 ppm or less, more preferably 2 ppm or more and 20 ppm or less, and still more preferably 3 ppm or more and 15 ppm or less. In this case, the polyester film produced by the method of the present invention contains titanium of not less than 1 ppm and not more than 30 ppm.

When the amount of the Ti-based catalyst is 1 ppm or more, a preferable IV is obtained. When the amount is 30 ppm or less, the terminal COOH can be suppressed to a low level, which is advantageous for improving the hydrolysis resistance.

- Solid phase polymerization -

In the present invention, in addition to the esterification reaction and / or the transesterification reaction, the polyester may be further subjected to solid phase polymerization. The solid-state polymerization can be preferably carried out by using a polyester or a commercially available polyester polymerized by the above-described esterification reaction or the like in the form of small pieces such as pellets. Concretely, as solid state polymerization, there can be mentioned, for example, Japanese Patent Publication No. 2621563, Japanese Patent Publication No. 3121876, Japanese Patent Publication No. 3136774, Japanese Patent Publication No. 3603585, Japanese Patent Publication No. 3616522, Japanese Patent Publication No. 3617340, Japanese Patent Publication No. 3680523, Japanese Patent Publication No. 3717392, Japanese Patent Publication No. 4167159, and the like can be used.

The solid phase polymerization is carried out at a temperature of 150 ° C to 250 ° C, more preferably 170 ° C to 240 ° C, and further preferably 190 ° C to 230 ° C for 5 hours to 100 hours, more preferably 10 hours to 80 hours , More preferably not less than 15 hours and not more than 60 hours. The solid phase polymerization is preferably carried out in a vacuum or in a nitrogen (N ₂ ) stream. The polyhydric alcohol (ethylene glycol or the like) may be mixed at 1 ppm or more and 1% or less.

The solid-state polymerization may be carried out in a batch-wise manner (a method in which a resin is placed in a container and stirring is carried out while applying a predetermined time heat in the container), a continuous method (a resin is put in a heated tube, (A system in which the liquid is passed through the cylinder while being blown (flowed), and the liquid is sent out sequentially).

In the present invention, the degree of polymerization of the polyester to be used as the raw material resin can be suitably selected in accordance with the required characteristics of the use of the polyester. In general, polyester having 0.3? IV? 0.65 is obtained by melt polycondensation, It is preferable to increase the polyester obtained by the melt polycondensation to 0.70? IV? 0.85 by solid-phase polycondensation.

- End sealing agent -

It is preferable that the polyester film contains a terminal sealing agent.

The polyester film has a structure having a molecule (tie chain) bridging the polyester crystals, so that it has a strong structure and is excellent in weather resistance. Since the polyester film contains a terminal sealing agent, the tie chain is not excessively developed, and heat resistance can be improved while suppressing embrittlement. This also reduces the likelihood of adverse effects likely to occur when the film is formed.

Therefore, in the method for producing a polyester film of the present invention, it is preferable to produce a polyester film such that the end-capping agent is contained in the polyester film. The end sealing agent may be mixed with the polyester raw material resin before being fed to the raw material feed port of the twin screw extruder or may be mixed while melt-kneading the polyester raw resin with a twin screw extruder. It may be mixed with the molten resin after discharge.

Among the methods described above, as the method of adding the terminal endblock agent, the polyester raw material resin and the terminal endblock agent are melt-mixed in advance so as to be not less than 10 mass% and not more than 60 mass% with respect to the total amount to prepare master pellets, It is preferable to be used by being fed into an axial extruder.

An end encapsulant is an additive that reacts with the terminal carboxyl group of the polyester to reduce the terminal carboxyl group content of the polyester.

Examples of the terminal blocking agent include a carbodiimide compound, an oxazoline compound, an epoxy compound, and a carbonate compound. The polyester film of the present invention preferably contains at least one end-capping agent of an isocyanate compound, a carbodiimide compound and an epoxy compound, and preferably contains two kinds of carbodiimide compounds. The terminal sealing agent may be used alone or in combination.

The end-capping agent is preferably a cyclic carbodiimide compound having a cyclic structure in which a first nitrogen atom and a second nitrogen atom of the carbodiimide group are bonded by a bonding group desirable.

- cyclic carbodiimide compound -

The cyclic carbodiimide compound is a compound containing a cyclic structure in which one carbodiimide group is present and the first nitrogen and the second nitrogen of the carbodiimide group are bonded by a bonding group.

Here, the first nitrogen indicates one nitrogen atom among the two nitrogen atoms of the carbodiimide group (-N = C = N-), and the second nitrogen indicates the other nitrogen atom.

The cyclic carbodiimide compound contains the cyclic carbodiimide compound of the present invention in order to encapsulate the terminal carboxyl group of the polyester as a terminal endblock, thereby improving the weather resistance, especially the wet heat durability of the polyester film .

The use of the cyclic carbodiimide compound improves the weather resistance of the polyester film for the following reasons.

By making the carbodiimide compound into a cyclic structure, formation of a tie chain can be further promoted in the polyester as follows.

The cyclic carbodiimide is cleaved and reacts with the terminal carboxylic acid of the polyester (PET-1).

The other end of the resolved carbodiimide becomes an isocyanate group and reacts with the terminal hydroxyl group of another polyester (referred to as PET-2).

· Since the cyclic carbodiimide compound has a cyclic structure, a site reacted with a hydroxyl group and a site reacted with a carboxylic acid are connected. As a result, two PET molecule chains (PET-1 and PET-2) form a tie chain structure connected via a cyclic carbodiimide.

The cyclic carbodiimide compound is preferably used in a proportion of 0.05 mass% to 20 mass% with respect to the polyester raw resin.

Hereinafter, details of the cyclic carbodiimide compound will be described.

The cyclic carbodiimide compound preferably has a weight average molecular weight (Mw) of 400 or more, more preferably 500 to 1,500.

The cyclic carbodiimide compound may have a plurality of cyclic structures.

Specifically, the cyclic structure of the cyclic carbodiimide compound has one carbodiimide group (-N═C═N-), and the first nitrogen and the second nitrogen are bonded by a bonding group. In one ring structure, only one carbodiimide group is present. For example, in the case of having a plurality of ring structures in the molecule, such as a spiro ring, one carbodiimide group in each ring structure bonded to the spiro atom Needless to say, the compound having a mid group may have a plurality of carbodiimide groups as a compound. The number of atoms in the cyclic structure is preferably 8 to 50, more preferably 10 to 30, still more preferably 10 to 20, still more preferably 10 to 15.

Here, the number of atoms in the cyclic structure means the number of atoms constituting the cyclic structure directly. For example, when the cyclic structure is an eight-membered ring, the number of atoms is 50, If the number of atoms in the cyclic structure is less than 8, the stability of the cyclic carbodiimide compound is lowered, which may make storage and use difficult. From the viewpoint of reactivity, there is no particular limitation on the upper limit of the number of ring atoms, but the cyclic carbodiimide compound having an atomic number exceeding 50 is difficult to synthesize, and the cost may increase significantly. From this point of view, the number of atoms in the cyclic structure is preferably selected in the range of 10 to 30, more preferably 10 to 20, and particularly preferably 10 to 15.

The cyclic structure is preferably a structure represented by the following formula (1).

[Chemical Formula 1]

In formula (1), Q (hereinafter also referred to as a coupler Q) may be any two to four valence bond groups selected from an aliphatic group, an alicyclic group and an aromatic group, or two or more groups selected from aliphatic groups, alicyclic groups and aromatic groups Group, which is a combination of two or four groups. The combination of two or more groups may be a combination of groups of the same kind such as an aromatic group and an aromatic group.

The aliphatic group, alicyclic group and aromatic group constituting Q may each independently contain a hetero atom or a monovalent substituent. Hetero atoms in this case refer to O, N, S, P. Two of the valencies of the coupler are used to form a ring-like structure. When Q is a trivalent or tetravalent linking group, the cyclic structure is bonded to the polymer or other cyclic structure through a single bond, a double bond, an atom, or an atomic group.

The coupler Q is preferably an aliphatic group having 2 to 4 carbon atoms, an aliphatic group having 2 to 4 carbon atoms, an alicyclic group having 3 to 20 carbon atoms, or an aromatic group having 5 to 15 carbon atoms or a 2 to 4 carbon atom, , An alicyclic group having 2 to 4 carbon atoms, an alicyclic group having 3 to 20 carbon atoms, and an aromatic group having 2 to 4 carbon atoms and having 5 to 15 carbon atoms.

Examples of the combination of two or more groups selected from an aliphatic group, an alicyclic group and an aromatic group constituting the coupler Q include a structure such as an alkylene-arylene group in which an alkylene group and an arylene group are bonded.

The coupler Q is preferably a 2- to 4-valent bond group represented by the following formula (1-1), (1-2) or (1-3).

(2)

In the formula (1-1), Ar ¹ and Ar ² are each independently a 2- to 4-valent aromatic group having 5 to 15 carbon atoms. Ar ¹ and Ar ² each independently may further contain a hetero atom or a monovalent substituent.

Examples of the aromatic group represented by Ar ¹ or Ar ² include an arylene group having 5 to 15 carbon atoms, an arerentiyl group having 5 to 15 carbon atoms, and an arene tetrayl group having 5 to 15 carbon atoms. Examples of the arylene group (divalent group) include a phenylene group and a naphthalenediyl group. As the arethryl group (trivalent), a benzenetriyl group, a naphthalenetriyl group and the like can be given. Examples of the allenetetrayl group (tetravalent) include a benzenetetrayl group and a naphthalenetetrayl group. These aromatic groups may be substituted.

Examples of the monovalent substituent which the aromatic group may have include an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 15 carbon atoms, a halogen atom, a nitro group, an amide group, a hydroxyl group, an ester group, an ether group and an aldehyde group have.

In formula (1-2), R ¹ and R ² are each independently an aliphatic group having 2 to 4 carbon atoms, an aliphatic group having 2 to 4 carbon atoms, an alicyclic group having 3 to 20 carbon atoms, or an alicyclic group having 2 to 4 carbon atoms A combination of an aliphatic group having 1 to 20 carbon atoms and an alicyclic group having 2 to 4 carbon atoms having 3 to 20 carbon atoms or an aliphatic group having 2 to 4 carbon atoms having 1 to 20 carbon atoms and an alicyclic group having 2 to 4 carbon atoms having 3 to 20 carbon atoms, Lt; / RTI &gt; to 15 aromatic groups. The aliphatic group, alicyclic group and aromatic group constituting R ¹ and R ² may each independently further contain a hetero atom or a monovalent substituent.

Examples of the aliphatic group represented by R ¹ or R ² include an alkylene group having 1 to 20 carbon atoms, an alkanetriyl group having 1 to 20 carbon atoms, and an alkanetetrayl group having 1 to 20 carbon atoms. Examples of the alkylene group include methylene, ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, nonylene, decylene, dodecylene and hexadecylene. Examples of the alkanetriyl group include a methanethiol group, an ethanethyryl group, a propanetriyl group, a butanetriyl group, a pentanetriyl group, a hexanetriyl group, a heptanetriyl group, an octanetriyl group, a nonanthryl group, a decanylthio group, a dodecanetriyl group, Decanyl group, and the like. Examples of the alkanetetrayl group include a methanetetrayl group, ethanetetrayl group, propanetetrayl group, butanetetrayl group, pentanetetrayl group, hexanetetrayl group, heptanetetrayl group, octanetetrayl group, nonanetetrayl group, decanetetrayl group, dodecanetetrayl group, Decanetetrayl group and the like. These aliphatic groups may be substituted.

Examples of the monovalent substituent which the aliphatic group may have include an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 15 carbon atoms, a halogen atom, a nitro group, an amide group, a hydroxyl group, an ester group, an ether group and an aldehyde group have.

Examples of the alicyclic group include a cycloalkylene group having 3 to 20 carbon atoms, a cycloalkanetriyl group having 3 to 20 carbon atoms, and a cycloalkanetetrayl group having 3 to 20 carbon atoms. Examples of the cycloalkylene group include a cyclopentylene group, a cyclobutylene group, a cyclopentylene group, a cyclohexylene group, a cycloheptylene group, a cyclooctylene group, a cyclononylene group, a cyclodecylene group, a cyclododecylene group, a cyclohexadecylene group, . Examples of the alkanetriyl group include a cyclopropanetriyl group, a cyclobutanetriyl group, a cyclopentanetriyl group, a cyclohexanetriyl group, a cycloheptanetriyl group, a cyclooctanetriyl group, a cyclononanetriyl group, a cyclododecanetriyl group, And a cyclohexadecanetriyl group. Examples of the alkane tetrayl group include a cyclopropane tetrayl group, a cyclobutane tetrayl group, a cyclopentanetetrayl group, a cyclohexanetetrayl group, a cycloheptanetetrayl group, a cyclooctanetetrayl group, a cyclononanetetrayl group, a cyclododecanetetrayl group, a cyclododecanetetrayl group, And a cyclohexadecanetetrayl group. These alicyclic groups may be substituted.

Examples of the monovalent substituent which the aliphatic group may have include an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 15 carbon atoms, a halogen atom, a nitro group, an amide group, a hydroxyl group, an ester group, an ether group and an aldehyde group have.

An aromatic group having 5 to 15 carbon atoms, an arenyl group having 5 to 15 carbon atoms, and an arene tetrayl group having 5 to 15 carbon atoms, each of which may contain a hetero atom and have a heterocyclic structure. Examples of the arylene group include a phenylene group and a naphthalenediyl group. As the arethryl group (trivalent), a benzenetriyl group, a naphthalenetriyl group and the like can be given. Examples of the allenetetrayl group (tetravalent) include a benzenetetrayl group and a naphthalenetetrayl group. These aromatic groups may be substituted.

Examples of the monovalent substituent which the aromatic group may have include an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 15 carbon atoms, a halogen atom, a nitro group, an amide group, a hydroxyl group, an ester group, an ether group and an aldehyde group have.

In the formulas (1-1) and (1-2), X ¹ and X ² each independently represent an aliphatic group having 2 to 4 carbon atoms, an aliphatic group having 2 to 4 carbon atoms, an alicyclic group having 3 to 20 carbon atoms, Or an aromatic group having 2 to 4 carbon atoms of 5 to 15 carbon atoms or an aliphatic group having 2 to 4 carbon atoms of 1 to 20 carbon atoms and an alicyclic group having 2 to 4 carbon atoms having 3 to 20 carbon atoms and an aromatic group having 2 to 4 carbon atoms and having 5 to 15 carbon atoms Lt; / RTI &gt; is a combination of two or more groups. The aliphatic group, alicyclic group and aromatic group constituting X ¹ and X ² may each independently further contain a hetero atom or a monovalent substituent.

Examples of the aliphatic group include an alkylene group of 1 to 20 carbon atoms, an alkanetriyl group of 1 to 20 carbon atoms, and an alkanetetrayl group of 1 to 20 carbon atoms. Examples of the alkylene group include methylene, ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, nonylene, decylene, dodecylene and hexadecylene. Examples of the alkanetriyl group include a methanethiol group, an ethanethyryl group, a propanetriyl group, a butanetriyl group, a pentanetriyl group, a hexanetriyl group, a heptanetriyl group, an octanetriyl group, a nonanthryl group, a decanylthio group, a dodecanetriyl group, Decanyl group, and the like. Examples of the alkanetetrayl group include a methanetetrayl group, ethanetetrayl group, propanetetrayl group, butanetetrayl group, pentanetetrayl group, hexanetetrayl group, heptanetetrayl group, octanetetrayl group, nonanetetrayl group, decanetetrayl group, dodecanetetrayl group, Decanetetrayl group and the like. These aliphatic groups may be substituted.

Examples of the monovalent substituent which the aliphatic group may have include an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 15 carbon atoms, a halogen atom, a nitro group, an amide group, a hydroxyl group, an ester group, an ether group and an aldehyde group have.

Examples of the alicyclic group include a cycloalkylene group having 3 to 20 carbon atoms, a cycloalkanetriyl group having 3 to 20 carbon atoms, and a cycloalkanetetrayl group having 3 to 20 carbon atoms. Examples of the cycloalkylene group include a cyclopentylene group, a cyclobutylene group, a cyclopentylene group, a cyclohexylene group, a cycloheptylene group, a cyclooctylene group, a cyclononylene group, a cyclodecylene group, a cyclododecylene group, a cyclohexadecylene group, . Examples of the alkanetriyl group include a cyclopropanetriyl group, a cyclobutanetriyl group, a cyclopentanetriyl group, a cyclohexanetriyl group, a cycloheptanetriyl group, a cyclooctanetriyl group, a cyclononanetriyl group, a cyclododecanetriyl group, And a cyclohexadecanetriyl group. Examples of the alkane tetrayl group include a cyclopropane tetrayl group, a cyclobutane tetrayl group, a cyclopentanetetrayl group, a cyclohexanetetrayl group, a cycloheptanetetrayl group, a cyclooctanetetrayl group, a cyclononanetetrayl group, a cyclododecanetetrayl group, a cyclododecanetetrayl group, And a cyclohexadecanetetrayl group. These alicyclic groups may be substituted.

Examples of the monovalent substituent which the alicyclic group may have include an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 15 carbon atoms, a halogen atom, a nitro group, an amide group, a hydroxyl group, an ester group, an ether group and an aldehyde group .

An aromatic group having 5 to 15 carbon atoms, an arenyl group having 5 to 15 carbon atoms, and an arene tetrayl group having 5 to 15 carbon atoms, each of which may contain a hetero atom and have a heterocyclic structure. Examples of the arylene group include a phenylene group and a naphthalenediyl group. As the arethryl group (trivalent), a benzenetriyl group, a naphthalenetriyl group and the like can be given. Examples of the allenetetrayl group (tetravalent) include a benzenetetrayl group and a naphthalenetetrayl group. These aromatic groups may be substituted.

Examples of the monovalent substituent which the aromatic group may have include an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 15 carbon atoms, a halogen atom, a nitro group, an amide group, a hydroxyl group, an ester group, an ether group and an aldehyde group have.

In the formulas (1-1) and (1-2), s and k are each independently an integer of 0 to 10, preferably an integer of 0 to 3, more preferably an integer of 0 to 1 to be.

When s and k are more than 10, the cyclic carbodiimide compound becomes difficult to synthesize, and the cost may increase remarkably. In this respect, the integer is preferably selected in the range of 0 to 3. When s or k is 2 or more, X ¹ or X ² as the repeating unit may be different from other X ¹ or X ² .

In the formula (1-3), X ³ represents an aliphatic group having 2 to 4 carbon atoms, an aliphatic group having 2 to 4 carbon atoms, an alicyclic group having 3 to 20 carbon atoms, or an aromatic group having 2 to 4 carbon atoms, Or a combination thereof.

The aliphatic group, alicyclic group and aromatic group constituting X ³ may each independently further contain a hetero atom or a monovalent substituent.

Examples of the aliphatic group include an alkylene group of 1 to 20 carbon atoms, an alkanetriyl group of 1 to 20 carbon atoms, and an alkanetetrayl group of 1 to 20 carbon atoms. Examples of the alkylene group include methylene, ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, nonylene, decylene, dodecylene and hexadecylene. Examples of the alkanetriyl group include a methanethiol group, an ethanethyryl group, a propanetriyl group, a butanetriyl group, a pentanetriyl group, a hexanetriyl group, a heptanetriyl group, an octanetriyl group, a nonanthryl group, a decanylthio group, a dodecanetriyl group, Decanyl group, and the like. Examples of the alkanetetrayl group include a methanetetrayl group, ethanetetrayl group, propanetetrayl group, butanetetrayl group, pentanetetrayl group, hexanetetrayl group, heptanetetrayl group, octanetetrayl group, nonanetetrayl group, decanetetrayl group, dodecanetetrayl group, Decanetetrayl group and the like. These aliphatic groups may contain a monovalent substituent.

Examples of the monovalent substituent which the aliphatic group may have include an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 15 carbon atoms, a halogen atom, a nitro group, an amide group, a hydroxyl group, an ester group, an ether group and an aldehyde group have.

Examples of the alicyclic group include a cycloalkylene group having 3 to 20 carbon atoms, a cycloalkanetriyl group having 3 to 20 carbon atoms, and a cycloalkanetetrayl group having 3 to 20 carbon atoms. Examples of the cycloalkylene group include a cyclopentylene group, a cyclobutylene group, a cyclopentylene group, a cyclohexylene group, a cycloheptylene group, a cyclooctylene group, a cyclononylene group, a cyclodecylene group, a cyclododecylene group, a cyclohexadecylene group, . Examples of the alkanetriyl group include a cyclopropanetriyl group, a cyclobutanetriyl group, a cyclopentanetriyl group, a cyclohexanetriyl group, a cycloheptanetriyl group, a cyclooctanetriyl group, a cyclononanetriyl group, a cyclododecanetriyl group, And a cyclohexadecanetriyl group. Examples of the alkane tetrayl group include a cyclopropane tetrayl group, a cyclobutane tetrayl group, a cyclopentanetetrayl group, a cyclohexanetetrayl group, a cycloheptanetetrayl group, a cyclooctanetetrayl group, a cyclononanetetrayl group, a cyclododecanetetrayl group, a cyclododecanetetrayl group, And a cyclohexadecanetetrayl group. These alicyclic groups may contain a monovalent substituent.

Examples of the monovalent substituent which the alicyclic group may have include an alkyl group having 1 to 20 carbon atoms, an arylene group having 6 to 15 carbon atoms, a halogen atom, a nitro group, an amide group, a hydroxyl group, an ester group, an ether group, .

An aromatic group having 5 to 15 carbon atoms, an arenyl group having 5 to 15 carbon atoms, and an arene tetrayl group having 5 to 15 carbon atoms, each of which may contain a hetero atom and have a heterocyclic structure. Examples of the arylene group include a phenylene group and a naphthalenediyl group. As the arethryl group (trivalent), a benzenetriyl group, a naphthalenetriyl group and the like can be given. Examples of the allenetetrayl group (tetravalent) include a benzenetetrayl group and a naphthalenetetrayl group. These aromatic groups may be substituted.

Examples of the monovalent substituent which the aromatic group may have include an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 15 carbon atoms, a halogen atom, a nitro group, an amide group, a hydroxyl group, an ester group, an ether group and an aldehyde group have.

Further, Ar ^1, Ar ^2, R ^1, R ^2, X ^1, X ² and X ³ is the time and may contain a hetero atom, and, Q is a divalent bonding date, Ar ^1, Ar ^2, R ^1, R ² , X ¹ , X ² and X ³ are all bivalent groups. When Q is a trivalent bonding group, one of Ar ¹ , Ar ² , R ¹ , R ² , X ¹ , X ² and X ³ is a trivalent group. When Q is a tetravalent linking group, one of Ar ¹ , Ar ² , R ¹ , R ² , X ¹ , X ² and X ³ is a tetravalent group or two are trivalent groups.

Examples of the cyclic carbodiimide compound include the following cyclic carbodiimide compounds (a) to cyclic carbodiimide compounds (c).

[Ring-shaped carbodiimide compound (a)]

The cyclic carbodiimide compound (a) is a compound represented by the following formula (2).

(3)

In formula (2), Q _a is _a divalent bonding group which is a combination of any one divalent bonding group selected from an aliphatic group, an alicyclic group and an aromatic group, or a combination of two or more groups selected from an aliphatic group, an alicyclic group and an aromatic group, May contain a hetero atom. The aliphatic group, alicyclic group and aromatic group are the same as those described in formula (1). However, in the compound of the formula (2), all of the aliphatic group, alicyclic group and aromatic group are divalent. Q _a is preferably a divalent bonding group represented by the following formula (2-1), (2-2) or (2-3).

[Chemical Formula 4]

Ar _a ¹ , Ar _a ² , R _a ¹ , R _a ² , X _a ¹ , X _a ² , X _a ³ , s and k in the formulas (2-1) to (2-3) Are the same as Ar ¹ , Ar ² , R ¹ , R ² , X ¹ , X ² , X ³ , s and k in formulas (1-1) However, all of them are divalent.

Examples of such a cyclic carbodiimide compound (a) include the following compounds.

[Chemical Formula 5]

[Ring-shaped carbodiimide compound (b)]

The cyclic carbodiimide compound (b) is a compound represented by the following formula (3).

[Chemical Formula 6]

In the formula (3), Q _b is a trivalent bonding group which is a combination of any one trivalent bonding group selected from an aliphatic group, an alicyclic group and an aromatic group, or two or more groups selected from an aliphatic group, an alicyclic group and an aromatic group, May contain a hetero atom. The aliphatic group, alicyclic group and aromatic group are the same as those described in formula (1). However, in the compound of the formula (3), one of the groups constituting Q _b is trivalent.

In the formula (3), Y is a carrier carrying a cyclic structure of a cyclic carbodiimide compound.

Q _b is preferably a trivalent bonding group represented by the following formula (3-1), (3-2), or (3-3).

(7)

Ar _b ¹ , Ar _b ² , R _b ¹ , R _b ² , X _b ¹ , X _b ² , X _b ³ , s and k in the formulas (3-1) to (3-3) Are the same as Ar ¹ , Ar ² , R ¹ , R ² , X ¹ , X ² , X ³ , s and k in formulas (1-1) to (1-3). Provided that one of these is a trivalent group.

Y is preferably a single bond, a double bond, an atom, an atomic group or a polymer. Y is a bonding portion, and a plurality of annular structures are bonded to each other through Y to form a structure represented by Formula (3).

Examples of such a cyclic carbodiimide compound (b) include the following compounds.

[Chemical Formula 8]

[Ring-shaped carbodiimide compound (c)]

The cyclic carbodiimide compound (c) is a compound represented by the following formula (4).

[Chemical Formula 9]

Wherein Q _c is a quadrivalent bonding group which is a combination of any one quadrivalent bonding group selected from an aliphatic group, an alicyclic group and an aromatic group or a combination of two or more groups selected from an aliphatic group, an alicyclic group and an aromatic group, and further includes a heteroatom . Z ¹ and Z ² are carriers each carrying a cyclic structure. Z ¹ and Z ² may be bonded to each other to form a cyclic structure.

The aliphatic group, alicyclic group and aromatic group are the same as those described in formula (1). However, in the compound of formula (4), Q _c is a tetravalent. Accordingly, one of these groups is a tetravalent group or two are trivalent groups.

Q _c is preferably a tetravalent linking group represented by the following formula (4-1), (4-2) or (4-3).

[Chemical formula 10]

Equation (4-1) to (4-3) of the formula, Ar ¹ _c, ² Ar _c, R _c ^1, R _c ^2, X ¹ _c, X ² _c, ³ _c X, s and k are, respectively, Are the same as Ar ¹ , Ar ² , R ¹ , R ² , X ¹ , X ² , X ³ , s and k in formulas (1-1) to (1-3). Provided that one of Ar _c ¹ , Ar _c ² , R _c ¹ , R _c ² , X _c ¹ , X _c ² and X _c ³ is a tetravalent group or two trivalent groups. Z ¹ and Z ² are each independently a single bond, a double bond, an atom, an atomic group or a polymer. Z ¹ and Z ² are bonding parts, and a plurality of ring-shaped structures are bonded through Z ¹ and Z ² to form a structure represented by formula (4).

Examples of such a cyclic carbodiimide compound (c) include the following compounds.

(11)

(Method for producing cyclic carbodiimide compound)

The cyclic carbodiimide compound can be synthesized based on the method described in paragraph [0075] of JP-A No. 2011-256337.

[Molten resin discharge step]

The molten resin discharging step is a step of discharging the molten resin from the twin screw extruder at a temperature ranging from Tm + 20 ° C to Tm + 30 ° C with respect to the melting point Tm of the polyester raw material resin by melting and kneading the polyester raw resin to obtain a molten resin .

As described above, the melting point Tm of the polyester raw material resin indicates the melting point when the melting point of the polyester raw material resin is 1, but when the polyester raw material resin has a plurality of melting points, The melting point Tm of the polyester raw material resin. More specifically, when a DSC curve in which the abscissa axis indicates temperature and the ordinate axis is calorific value when the polyester raw resin is subjected to differential scanning calorimetry (DSC) has one endothermic peak P1, the endothermic peak P1 The peak temperature is defined as the melting point of the polyester raw material resin. In the DSC curve, two or more endothermic peaks P2-1, P2-2, ... When having P2-n, the peak temperature of the endothermic peak generated at the highest temperature among the endothermic peaks P2-1 to P2-n is taken as the melting point of the polyester raw material resin.

The raw resin fed into the extruder by the raw resin feeding step is melted and kneaded to become a molten resin (melted) in the molten resin discharging step, and is discharged from the extruder at a predetermined temperature.

If the temperature of the molten resin at the outlet of the extruder is less than the melting point Tm + 20 占 폚 of the polyester raw material resin, the unfused foreign matters remain in the molten resin due to insufficient melting of the raw resin, Tm + 30 DEG C &quot;, the DELTA AV increases.

The temperature of the molten resin at the exit of the extruder can be adjusted by controlling the set temperature of the extruder outlet.

The temperature of the molten resin at the outlet of the extruder is preferably Tm + 20 ° C to Tm + 27 ° C with respect to the melting point Tm of the polyester raw material resin.

Next, details of the twin-screw extruder for supplying the raw material resin and melting and kneading the raw material resin will be described.

(Twin screw extruder)

First, the twin-screw extruder used in the present invention will be described.

The twin-screw extruder generally comprises a barrel (also referred to as a cylinder) for melting a raw resin supplied to an extruder and kneading the molten resin. The barrel has a raw material supply port for supplying the raw material resin and an outlet (discharge port) for discharging the molten resin, and a screw is provided in the barrel for kneading the molten resin. The extruder is largely divided into a single shaft having one screw and a multiple shaft having a plurality of screws. In the present invention, a twin screw extruder (twin screw extruder) is used. The biaxial extruder preferably includes a screw having a kneading portion for plasticizing the polyester raw material resin.

The kneading portion refers to a segment (position of the kneading disk) having a function of plasticizing the polyester raw material resin as a portion of the screw, and a region in which the polyester raw resin is plasticized as a region in the extruder Point. Therefore, the kneading portion of the screw is located in the plastic portion of the extruder.

Hereinafter, the structure of the extruder will be described with reference to Figs. 1 and 2. Fig.

Fig. 1 schematically shows a configuration example of an extruder.

Fig. 2 shows an example of a flow in which the method for producing a polyester film according to the present invention is carried out.

The extruder 100 shown in Fig. 1 is a twin screw extruder having two screws (two axes). The extruder 100 includes a barrel 10 (cylinder) having a supply port 12 and an extruder outlet 14, two screws 20A and 20B rotating in the barrel 10, And a temperature control means (30) arranged around the barrel (10) for controlling the temperature in the barrel (10). As shown in Fig. 2, a raw material supply device 46 is formed in front of the supply port 12. As shown in Fig. At the end of the extruder outlet 14, a gear pump 44, a filter 42 and a die 40 are formed. The material supply device 46 may be constituted by a plurality of material supply devices including at least a first material supply device for housing the first resin and a second material supply device for housing the second resin, Or may be a single material supply apparatus having a plurality of storage containers that can be individually stored.

- Barrel -

The barrel 10 has a feed port 12 for feeding the raw resin and an extruder outlet 14 for extruding the melted raw resin.

The inner wall surface of the barrel 10 needs to be made of a material which is excellent in heat resistance, abrasion resistance and corrosion resistance, and can ensure friction with the resin. Generally, a nitrided steel whose inner surface is nitrided is used, and chromium molybdenum steel, nickel chromium molybdenum steel, and stainless steel can be nitrided and used. Particularly in applications where abrasion resistance and corrosion resistance are required, it is possible to use a bimetallic barrel in which a corrosion resistant and wear resistant material alloy such as nickel, cobalt, chromium, and tungsten is lined by the centrifugal casting method on the inner wall surface of the barrel 10, It is effective to form a thermal spray coating.

Vents (16A, 16B) for evacuating the barrel (10) are also formed. By evacuating through the vents 16A and 16B, volatile components such as moisture in the resin in the barrel 10 can be efficiently removed. By appropriately arranging the vents 16A and 16B, raw materials (pellets, powder, flakes, etc.) in an undried state and pulverized debris (fluff) of the film produced during film formation can be used as raw material resins as they are.

The bents 16A and 16B are required to have a proper opening area and number of vents in relation to the degassing efficiency. The twin-screw extruder 100 used in the present invention preferably has at least one vent 16A, 16B. If the number of the vents 16A, 16B is excessively large, the molten resin may overflow from the vent, and there is a risk of an increase in deteriorated foreign matter. Therefore, it is preferable to form the vent at one point or two points.

Further, if the resin remaining on the wall surface in the vicinity of the vent or the volatilized components precipitated falls into the extruder 100 (barrel 10), there is a possibility that the volatile components present in the product are present as foreign substances. Regarding the stay, it is generally effective to optimize the shape of the vent lid, appropriate selection of the upper vent and side vent, and to prevent precipitation of volatile components by heating pipes and the like.

For example, when PET is extruded, inhibition of hydrolysis, pyrolysis, and oxidative decomposition greatly affects the quality of a product (film).

For example, oxidative decomposition can be suppressed by evacuating the resin supply port 12 or supplying nitrogen (also referred to as nitrogen purge) from a nitrogen gas supply port, which will be described later.

In order to suppress decomposition of the resin due to shearing heat generation, it is preferable that the segment such as the kneading portion is not formed as much as possible within a range in which extrusion and deaeration can be compatible.

Since the shear heat generation becomes larger as the pressure of the screw outlet (extruder outlet) 14 is increased, the pressure of the extruder outlet 14 is increased within a range in which the ventilation efficiency by the vents 16A and 16B and the stability of extrusion can be ensured. The pressure is preferably as low as possible.

- Screw-

In the barrel 10, two screws 20A and 20B which are rotated by a driving means 21 including a motor and a gear are formed.

In the polyester film production method of the present invention, when the diameter of the screw is D [mm], the extruder 100 preferably has a screw diameter D of 60 mm or more, more preferably 140 mm or more . By setting the screw diameter (D) to 60 mm or more, the retention of the molten resin in the extruder can be suppressed, and the productivity of the polyester film can be improved.

From the viewpoint of mass production, the screw diameter D is more preferably 160 mm or more. On the other hand, from the viewpoint of suppressing the uneven melting of the resin, the screw diameter D is preferably 200 mm or less.

Next, with reference to Figs. 1 and 2, preferred embodiments of the screw included in the extruder will be described.

The twin-screw extruder is largely distinguished from the engaging type of the two screws 20A and 20B and the non-engaging type, and the engaging type has a greater kneading effect than the non-engaged type. In the present invention, any of the engaging type and the non-engaging type may be used, but it is preferable to use the engaging type from the viewpoint of sufficiently kneading the raw resin and suppressing uneven melting.

The rotational directions of the two screws 20A and 20B are also divided into the same direction and the opposite direction. Since the bidirectional rotary screws 20A and 20B have a higher kneading effect than the co-rotating type, and the co-rotating type has the self-cleaning effect, it is effective for preventing stagnation in the extruder.

In addition, there is also a conical type shape which is used in the case where axial direction is also parallel and oblique, and strong shearing is given.

In the twin-screw extruder used in the present invention, various shapes of screw segments are used. As the shapes of the screws 20A and 20B, for example, a full flight screw in which a pair of helical flights 22 of equal value is formed is used.

The raw material resin can be more reliably melted by using a segment for giving a shearing action, such as a kneading disk or a rotor, to the plastic portion for plasticizing the polyester raw material resin. Also, by using the reverse screw or the sealing ring, the resin can be sealed to form a melt seal when the vents 16A and 16B are discharged. For example, as shown in Fig. 1, kneading portions (kneading portions) 24A and 24B for promoting melting of the raw resin as described above can be formed in the vicinity of the vents 16A and 16B.

Of the area of the screw, kneading with a kneading disk section is formed, the shear rate in the kneading clearance 500 s ^-1 ~ 2000 s ^- is preferably ^1.

The knitting clearance is the distance between adjacent knitting disks.

Since the shear rate is 500 s ^-1 or higher, the remaining unhardened foreign matter due to insufficient melting of the raw resin can be suppressed, and the shear rate is 2000 s ^-1 or less, thereby suppressing the increase of ΔAV due to heat generation of the raw resin can do.

Shear rate in the kneading clearance is, 500 s ^-1 ~ 1500 s ^{- 1,} and more preferably, 500 ~ 800 s ^-1 s ^{- 1} that are especially preferred.

In the latter half of the extruder 100, a temperature zone (cooling section) for cooling the molten resin is effective. In the case where the heat transfer efficiency of the barrel 10 is higher than the shearing heat generation, the speed of movement of the resin on the wall surface of the barrel 10 is increased by forming the screw 28 having a short pitch in the temperature zone (cooling portion) have. From the viewpoint of enhancing the cooling effect, it is preferable that the pitch of the screw 28 located in the cooling section is 0.5 D to 0.8 D with respect to the screw diameter D.

- Nitrogen gas inlet -

The extruder 100 is provided with a first nitrogen gas supply port for supplying nitrogen gas of 1.1 to 10.0 times the supply amount of the polyester raw material resin at a position closer to the raw material supply port than the vent hole closest to the raw material supply port .

"Nitrogen gas of 1.1 times to 10.0 times the supply amount of the polyester raw resin" means that when the supply amount of the polyester raw resin is Q [L / min], the supply amount of the nitrogen gas is 1.1 Q [L / min] To 10.0 Q [L / min].

1, a nitrogen gas supply port is provided at a position nearer to the supply port 12 of the raw resin than the vent 16A, and from the nitrogen gas supply port, the supply amount of the polyester raw resin is 1.1 to 10.0 times Of nitrogen gas.

In the barrel 10, the raw material resin is melted and kneaded from the raw material supply port 12 on the upstream side to the extruder outlet 14 on the downstream side. The first nitrogen gas supply port is located upstream of the vent 16A closest to the raw material supply port 12.

Conventionally, in order to suppress the oxidative decomposition of the molten resin in the extruder, nitrogen gas is supplied from the barrel 10 to the screw 20A or 20B, From the driving means 21 of the driving means. However, in order to suppress the oxidative decomposition of the raw resin in the extruder, it is necessary to replace the molten raw resin itself with nitrogen. In the method of supplying nitrogen gas from the barrel 10 or supplying it from the driving means 21, Nitrogen gas was not supplied to the resin, and the oxidative decomposition of the molten resin could not be suppressed.

Therefore, by providing the first nitrogen gas supply port at a position closer to the raw material supply port than the vent hole closest to the raw material supply port, nitrogen gas can be supplied to the raw resin in the extruder.

For example, in Fig. 1, it is preferable to form a nitrogen gas supply port at the position of N1 or N2.

In particular, when the nitrogen gas supply amount is at least 1.1 times as large as the supply amount of the polyester raw material resin, the oxidation of the raw material resin can be sufficiently suppressed, and if it is 10.0 times or less, the raw material resin located in the raw material supply port is hardly blown away, It is possible to suppress the supply failure of the raw resin. The supply amount of the nitrogen gas is preferably 1.1 to 8.0 times the supply amount of the polyester raw material resin.

The extruder 100 is located in the kneading portions 24A and 24B of the screws 20A and 20B of the extruder 100 and is provided with a second nitrogen gas It is preferable that a supply port is provided.

Oxidative decomposition and pyrolysis of the raw material resin are likely to occur during the period from the start of melting of the raw material resin to the middle of being melted, and it is preferable to supply nitrogen gas to the raw material resin when the raw material resin is in this state. Since the raw material resin is likely to be thermally decomposed by melting in the kneading portion for kneading the raw material, it is preferable that the kneading portion is provided with a nitrogen gas feed port so as to easily supply nitrogen gas directly to such raw resin Do.

Since the thermal decomposition of the raw resin is apt to occur particularly at the stage of starting melting, the second nitrogen gas supply port is located at the center of the kneading portions 24A and 24B (N2 in FIG. 1 in the kneading portion 24A) (N1 in Fig. 1 in the kneading portion 24A) upstream of the kneading portion.

1, the kneading portion has 24A located on the upstream side of the direction of the feedstock resin and 24B located on the downstream side. In the present invention, the number of the second nitrogen gas supply port located at the kneading portion is one Or may be two or more. That is, in FIG. 1, the second nitrogen gas supply port may be provided in at least one of the position of the kneading portion 24A and the kneading portion 24B.

The supply rate of the nitrogen gas in the first nitrogen gas supply port and the second nitrogen gas supply port is preferably 2 m / minute to 50 m / minute. The feed rate of the nitrogen gas is 2 m / min or more to sufficiently inhibit the oxidation of the raw material resin. By setting the feed rate to 50 m / min or less, the decrease of the resin temperature of the raw material resin can be suppressed, Can be suppressed.

It is more preferable that the feeding rate of the nitrogen gas is 3 m / min to 45 m / min.

- Temperature control means -

A temperature control means (30) is formed around the barrel (10). In the extruder 100 shown in Fig. 1, the heating / cooling devices C1 to C9 divided into nine pieces in the longitudinal direction from the raw material supply port 12 to the extruder outlet 14 constitute the temperature control means 30 have. As described above, the heating / cooling apparatuses C1 to C9, which are divided and disposed around the barrel 10, are used for heating the respective regions (zones) of the firing portions C1 to C7 and the cooling portions C8 and C9 So that the inside of the barrel 10 can be controlled at a desired temperature for each region.

For heating, a band heater or a sheath aluminum injection heater is usually used, but the present invention is not limited thereto, and for example, a heat circulation heating method can also be used. On the other hand, air cooling by a blower is generally carried out, but there is also a method in which water or oil flows through a pipe wound around the barrel 10.

- melt kneading of raw resin -

The extruder 100 heats the barrel 10 by the temperature control means 30 and rotates the screw to supply the raw material resin from the supply port 12. In addition, it is preferable that the supply port 12 be cooled as heat prevention so as to prevent pellets or the like of the raw material resin from being heated and fused, and to protect a screw driving facility such as a motor.

The raw resin supplied into the barrel can be heated by the temperature control means 30 as well as the friction between the resins accompanied by the rotation of the screws 20A and 20B and the friction between the resin and the screws 20A and 20B and the barrel 10 And is gradually moved toward the extruder outlet 14 with the rotation of the screw.

If the resin temperature is too low, the melt at the time of melt extrusion may be insufficient and the resin may be difficult to discharge from the die 40. If the resin temperature is excessively high The end COOH is remarkably increased by thermal decomposition and the hydrolysis resistance may be deteriorated. Further, as described above, the melting point Tm of the raw material resin refers to the highest melting point when a plurality of Tm are used by using a plurality of raw material resins.

From these viewpoints, by adjusting the heating temperature by the temperature control means 30 and the number of revolutions of the screws 20A and 20B, the maximum resin temperature Tmax in the longitudinal direction in the twin screw extruder is set to (Tm + 40) (Tm + 60) ° C, more preferably (Tm + 40) ° C to (Tm + 55) ° C, Do.

The maximum resin temperature Tmax in the longitudinal direction in the twin screw extruder is the temperature of the raw resin heated in the barrel in which the screws 20A and 20B of the twin screw extruder 100 are arranged, And a local high-temperature portion due to heat. Tmax is obtained by measuring the resin temperature in the barrel. In the relation of Tm and Tmax, in the case of PET resin, Tmax [占 폚] is preferably 290 占 폚 or lower, more preferably 280 占 폚 or lower, from the viewpoint of suppressing the increase of terminal COOH. The lower limit temperature of Tmax is preferably set to 260 deg. C from the viewpoint of preventing insufficient melting of the resin.

- Vent pressure -

By evacuating through the vents 16A and 16B, volatile components such as moisture in the resin in the barrel can be efficiently removed. If the vent pressure is excessively low, the molten resin may overflow out of the barrel 10. If the vent pressure is excessively high, the removal of the volatile components may be insufficient, and the obtained film may be easily hydrolyzed. From the viewpoint of preventing the molten resin from overflowing from the vents 16A and 16B and selectively removing the volatile components, the vent pressure is preferably 0.01 Torr to 5 Torr (1.333 Pa to 666.5 Pa), and 0.01 Torr To 4 Torr (1.333 Pa to 533.2 Pa).

- Average residence time -

The average residence time from the die 40 to the extrusion of the film from the die 40 is 10 minutes to 20 minutes after the raw resin is heated and melted in the barrel and exits the extruder outlet 14. [ The unhardened resin tends to remain when the average residence time from the die 40 to the extrusion of the extruder 100 through the extruder outlet 14 of the extruder 100 after heating and melting the raw resin is less than 10 minutes, Min, the amount of terminal COOH is increased by pyrolysis and the hydrolysis resistance is lowered. From this point of view, the average residence time after the raw material resin is melted by heating and extruded from the extruder outlet 14 is preferably 10 minutes to 20 minutes, more preferably 10 minutes to 15 minutes.

Here, the average residence time is defined by the following formula.

Average residence time (sec) = Volume of downstream pipe (mm 3) of extruder × Density of melt (g / cm 3) × 3600/1000 ÷ Amount of extrusion (kg / hr)

-Cooling-

The raw material resin is heated and melted in the barrel and the inner wall of the barrel 10 on the side of the extruder outlet 14 side is heated to a temperature lower than the melting point Tm (占 폚) of the polyester resin (raw material resin) As shown in Fig. If the inner wall of the barrel 10 on the side of the extruder outlet 14 is controlled to be the melting point Tm (占 폚) or less of the raw material resin as the cooling portion, the resin is excessively heated and the increase in the amount of terminal COOH can be suppressed. (Tm - 50) ° C to (Tm - 10) ° C, more preferably in the range of (Tm -100) ° C to Tm ° C, Is more preferable.

The length of the cooling section is preferably 4 D to 11 D with respect to the screw diameter (D). When the length of the cooling portion is 4 D or more, the melt-heated resin is effectively cooled to suppress the increase of the terminal COOH. On the other hand, when the length of the cooling portion is 11 D or less, the resin is excessively cooled to prevent the resin from solidifying, and melt extrusion can be smoothly performed.

The resin temperature at the extruder outlet 14 is set at Tm + 20 ° C to Tm + 30 ° C with respect to the melting point Tm of the polyester raw material resin, as described above.

[Molding process]

The method for producing a polyester film of the present invention has a molding step of forming a molten resin extruded from an extruder into a film.

In the method for producing a polyester film of the present invention, the molten resin extruded from an extruder is formed into a film after passing through the resin supplying step of the above-described constitution.

The molten resin extruded from the extruder is discharged from the die 40 through the gear pump 44 and the filter 42 as shown in Fig. Since the opening of the die 40 has a wide elongated shape, the molten resin discharged from the die 40 is processed into a film.

-die-

A die 40 (FIG. 2) for discharging the molten resin extruded from the extruder outlet 14 into a film (strip) is formed in the extruder outlet 14 of the barrel 10 shown in FIG. Between the extruder outlet 14 of the barrel 10 and the die 40 is formed a filter 42 for preventing unmelted water or foreign matter from entering the film.

- Gear Pump -

In order to improve the thickness accuracy, it is important to minimize the variation of the extrusion amount. A gear pump 44 may be provided between the extruder 100 and the die 40 in order to reduce the variation of the extrusion amount as much as possible. By supplying a certain amount of resin from the gear pump 44, the thickness precision can be improved. In particular, in the case of using a biaxial screw extruder, since the pressure increasing ability of the extruder itself is low, it is desirable to stabilize extrusion by the gear pump 44. [

By using the gear pump 44, the pressure fluctuation of the secondary side of the gear pump 44 can be reduced to 1/5 or less of the primary side, and the fluctuation range of the resin pressure can be made within +/- 1%. Other advantages include prevention of increase in resin temperature, improvement in transport efficiency, and reduction in residence time in the extruder because filtration by a filter is possible without increasing the pressure at the tip of the screw. It is also possible to prevent the resin amount supplied from the screw from fluctuating over time due to the increase in the filtration pressure of the filter. However, when the gear pump 44 is provided, depending on the selection method of the equipment, the length of the equipment becomes longer, the residence time of the resin becomes longer, and the molecular chain breaks due to the shear stress of the gear pump unit You need to be careful.

When the difference between the primary pressure (inlet pressure) and the secondary pressure (outlet pressure) is excessively increased, the gear pump 44 increases the load on the gear pump 44 and the shear heat generation becomes large. Therefore, the differential pressure at the time of operation is set to 20 MPa or less, preferably 15 MPa or less, more preferably 10 MPa or less. It is also effective to control the screw rotation of the extruder or use a pressure regulating valve in order to make the primary pressure of the gear pump 44 constant, in order to make the film thickness uniform.

Since the raw material resin having an intrinsic viscosity (IV) of 0.70 dl / g or more is used in the production process of the polyester film of the present invention, in the molding step, the raw resin is heated and melted in the barrel, (I) by controlling the screw rotation speed N (rpm) and the extrusion amount Q (kg / hr) in consideration of the screw diameter D through an average residence time of 10 minutes to 20 minutes after being extruded from the extruder It is preferable to carry out melt extrusion to the film under the conditions satisfying the following conditions.

6.0 x 10 ^-6 x D ³ ? Q / N? 1.1 x 10 ^-5 x D ³ ... The formula (i)

When the raw material resin having IV of 0.7 dl / g or more is melted, by lowering N, it is easy to simultaneously satisfy melting, deaeration and resin cooling. Further, by controlling the resin temperature at the extruder outlet 14 to be particularly 290 DEG C or less, there is a great effect for suppressing the increase of the terminal COOH due to the stay of the pipe downstream therefrom.

By setting Q / N to 6.0 x 10 ^-6 x D ³ or more, it is possible to suppress the overheating of the raw resin due to the high rotation of the screws 20A and 20B and to reduce the resin temperature at the extruder outlet 14 to 290 DEG C or lower It is easy to make ΔAV 3 eq / t or less. Further, when the Q / N ratio is 1.1 x 10 ^-5 x D ³ or less, the resin filling rate immediately below the vent hardly increases, the molten resin is hard to flow from the vents 16A and 16B, The hydrolysis of the resin in the extruder is difficult to proceed and the occurrence of terminal COOH can be suppressed easily. In addition, since the unmelted resin is less likely to be incorporated into the film, the strength of the polyester film can be prevented from lowering, and film breakage in the stretching process can be suppressed.

When the amount of the raw resin fed to the extruder is Q (kg / hr), the extruded amount in the extruder is Q (kg / hr), and the extruded amount in the extruder is Q [Kg / hr].

More preferably, the melt extrusion is carried out under the conditions shown in the following formula (ii) and more preferably under the conditions shown in the following formula (iii).

7 x 10 ^-6 x D ³ ? Q / N? 1 x 10 ^-5 x D ³ ... (Ii)

8 x 10 ^-6 x D ³ ? Q / N? 9 x 10 ^-6 x D ³ ... The formula (iii)

If the screw rotation speed N is too low, temperature unevenness is generated by the temperature control means 30 to cause unmelted resin, and if the screw rotation speed N is excessively high, excessive heat is generated to increase the amount of terminal COOH , The screw rotation number N is preferably 1.9 × 10 ² × D ^-0.5 rpm to 8.4 × 10 ² × D ^-0.5 rpm and more preferably 6.3 × 10 ² × D ^-0.5 rpm to 7.9 × 10 ² × D ^-0.5 rpm desirable.

In addition, since the extrusion output Q is too small it is likely to be excessively heated, is too high tend to result in unmelted resin occurs, extrusion output Q is ^{1.1 × 10 -3 × D 2 .5} ㎏ / hr ~ 7.6 × 10 - ³ × D ^{2 .5} kg / hr, and more preferably 3.8 × 10 ^-3 × D ^{2 .5} kg / hr to 7.1 × 10 ^-3 × D ^{2 .5} kg / hr.

The resin extruded from the extruder outlet 14 of the barrel 10 is passed through a filter 42 and extruded from a die 40 (for example, into a cooling roll) to form a film.

It is preferable to adjust the humidity to 5% RH to 60% RH during the time from the extrusion of the melt (molten resin) from the die 40 to the contact with the cooling roll (air gap) It is more preferable to adjust it to 50% RH. By setting the humidity in the air gap to the above range, it is possible to control the amount of COOH and the amount of OH on the surface of the film, and the amount of carboxylic acid on the surface of the film can be reduced by controlling the humidity at low humidity.

Further, according to the method of the present invention, it is possible to suppress the increase of the terminal COOH amount and to suppress the generation of unhulled foreign matter by raising the resin temperature once and then lowering the temperature at the cooling section, Is obtained. In particular, when a thick film is formed, haze tends to increase due to a shortage of cooling rate, and it can be used as a countermeasure method.

The film thickness is preferably from 2 mm to 8 mm, more preferably from 2.5 mm to 7 mm, and still more preferably from 3 mm to 6 mm. By making the thickness thicker, the time required until the extruded melt is cooled to the glass transition temperature (Tg) or less can be prolonged. In the meantime, the COOH group on the film surface can diffuse into the polyester to reduce the amount of surface COOH.

By this process, a polyester film having a difference ΔAV between the amount of terminal COOH of the starting resin and the amount of terminal COOH of the melt-extruded film can be 3 eq / t or less. For example, a terminal COOH amount of 25 eq / t ( Ton) or less is obtained. When the amount of terminal COOH is 25 eq / ton or less, the hydrolysis resistance is excellent and long-term durability is obtained. The amount of terminal COOH is preferably low on the hydrolysis surface, but is preferably 2 eq / ton or more from the viewpoint of improving the adhesion when the film is brought into close contact with the adherend. Among them, a range of 10 to 20 eq / ton is more preferable.

The measurement of the terminal COOH amount can be carried out in the same manner as described above.

&Lt; Polyester film for solar cell &

The polyester film for a solar cell of the present invention can be produced by the polyester film production method of the present invention described above.

Since the polyester film for solar cells of the present invention is produced by the method for producing a polyester film of the present invention, it can have high hydrolysis resistance.

The polyester film for a solar cell has a structure in which a structure containing 1,4-cyclohexane dimethanol is contained in an amount of 0.1 to 100 mol% based on the total amount of the structural units derived from the diol compound, By having at least one layer, the film weather resistance can be further improved.

The layer containing the CHDM based polyester resin may be a polyester film produced by the polyester film production method of the present invention and may be a layer obtained by extrusion molding on a polyester film produced by the polyester film production method of the present invention Or may be a film or a sheet-like member affixed to a polyester film produced by the method for producing a polyester film of the present invention.

Thus, the polyester film for a solar cell may have at least one layer containing a CHDM polyester resin, or may have a single layer or two or more layers.

In particular, when the CHDM-based polyester resin has a structure derived from CHDM of 80 mol% to 100 mol% based on the total amount of the structure derived from the diol compound, the polyester film for solar cells is preferably a laminated structure. This is because when the ratio of the structure derived from CHDM to the total amount of the structure derived from the diol compound in the CHDM-based polyester resin is high, the weather resistance (hydrolysis resistance) tends to be high with respect to polyethylene terephthalate (PET) It is easy to get rid of. For this reason, it can be complemented by lamination with another polyester (for example, PET), which is preferable.

The polyester film for a solar cell of the present invention is a laminate in which a layer containing a CHDM polyester resin (referred to as a P1 layer) and a layer containing a polyester mainly composed of polyethylene terephthalate (referred to as a P2 layer) desirable.

Further, the polyester film for a solar cell of the present invention may have two or more layers each of a P1 layer and a P2 layer.

The P2 layer contains a polyester resin containing 95 mol% or more of a structure derived from terephthalic acid in the structure derived from the dicarboxylic acid and containing 95 mol% or more of the structure derived from ethylene glycol in the structure derived from the diol compound Point.

The IV of the P2 layer is preferably 0.7 to 0.9, more preferably 0.72 to 0.85, and still more preferably 0.74 to 0.82. By thus increasing the IV of the P2 layer, it is possible to suppress decomposition (lowering of the molecular weight of the polyester resin) by the wet thermo and dry thermo.

In the polyester film for a solar cell of the present invention, the sum of the number of layers of the P1 layer and the P2 layer is preferably 2 layers or more, more preferably 2 layers or more and 5 layers or less, and still more preferably 2 layers or more and 4 layers or less . Among them, a three-layer structure in which both sides of the P2 layer are sandwiched between P1 layers, or a three-layer structure in which both sides of the P1 layer are sandwiched between P2 layers, and a two-layer structure in which a P2 layer and a P1 layer are laminated.

When the polyester film for a solar cell of the present invention is composed of two or more layers, the total thickness of the polyester film for a solar cell is preferably 5% to 40%, more preferably 7% % To 38%, and more preferably 10% to 35%. By setting this value at or below the lower limit value, high weather resistance can be exhibited, and when it is not more than the upper limit value, high mechanical strength is easily exhibited.

The thickness of each layer of the polyester film was measured by using a SIMS (Secondary Ion-microprobe Mass Spectrometer) and the characteristic fragment of the P1 layer and the characteristic fragment of the P2 layer .

The laminated structure of such a polyester film for a solar cell can be obtained by an ordinary method. For example, the polyester resin constituting the P1 layer may be supplied to any extruder, and the polyester resin constituting the P2 layer may be supplied to another extruder to melt the melt (resin melt) supplied from the plurality of extruders into the multi- A folding die, or a feed block die. Alternatively, a polyester resin constituting the other layer may be laminated on the polyester film which is one of the P1 layer and P2 layer prepared in advance, or the other layer may be laminated by lamination.

The polyester film for a solar cell produced by the method of the present invention may further contain additives such as a light stabilizer and an antioxidant.

When a light stabilizer is contained, ultraviolet deterioration can be prevented. Examples of the light stabilizer include a compound that absorbs light such as ultraviolet rays to convert it into heat energy, a material that absorbs light absorbed by the resin and captures a radical generated by decomposition, and suppresses decomposition chain reaction. The light stabilizer is preferably a compound which absorbs light rays such as ultraviolet rays and converts them into heat energy. By containing such a light stabilizer, it is possible to maintain the effect of improving the partial discharge voltage for a long time for a long time even when irradiated with ultraviolet rays continuously for a long period of time, or to prevent color tone change and strength deterioration caused by ultraviolet rays in the resin.

For example, the ultraviolet absorber may be any of organic-based ultraviolet absorber, inorganic-ultraviolet absorber, and combinations thereof insofar as other characteristics of the polyester are not impaired. On the other hand, it is desired that the ultraviolet absorbent is excellent in wet heat resistance and can be uniformly dispersed in a resin.

Examples of the ultraviolet absorber include organic ultraviolet absorbers such as salicylic acid-based, benzophenone-based, benzotriazole-based, and cyanoacrylate-based ultraviolet absorbers, and hindered amine-based ultraviolet light stabilizers. Specific examples thereof include salicylic acid pt-butylphenyl salicylate, p-octylphenyl salicylate, benzophenone-based 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxy Benzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, 2,2 ', 4,4'-tetrahydroxybenzophenone, bis (2-methoxy- Phenyl) methane, benzotriazole based 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2,2'- Bis [4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol], cyanoacrylate ethyl = alpha -cyano- (4,6-diphenyl-1,3,5-triazine-2-yl) -5 - [(hexyl) oxy] -phenol as a triazine type, bis 2,2,6,6-tetramethyl-4-piperidyl) sebacate, dimethyl succinate 占 1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiper Dean polycondensation Water, and in addition, nickel bis (octylphenyl) sulfide and 2,4-di-t-butylphenyl-3 ', 5'-di-t-butyl-4'-hydroxybenzoate.

Of these ultraviolet absorbers, a triazine-based ultraviolet absorber is more preferable because it is highly resistant to ultraviolet absorption repeatedly. These ultraviolet absorbers may be added to the film as a single layer of the ultraviolet absorber as described above, or may be introduced in the form of a copolymer of an organic conductive material or a monomer having an ultraviolet absorptive property to a water-insoluble resin.

The content of the light stabilizer in the polyester film is preferably from 0.1 mass% to 10 mass%, more preferably from 0.3 mass% to 7 mass%, and still more preferably from 0.3 mass% to 7 mass%, based on the total mass of the polyester film Is not less than 0.7 mass% and not more than 4 mass%. This makes it possible to suppress the decrease in the molecular weight of the polyester due to photo deterioration over a long period of time and to suppress the decrease in adhesion caused by the cohesive failure in the resulting film.

The polyester film of the present invention may contain additives such as a lubricating agent (fine particles), an ultraviolet absorber, a colorant, a nucleating agent (crystallizing agent), a flame retarding agent and the like in addition to the above- have.

<Back Sheet for Solar Cell>

The polyester film for a solar cell of the present invention is preferable for applications such as a back protection sheet (back sheet for a solar cell), a barrier film base, and the like, which are disposed on the back surface opposite to the solar light incidence side of the solar cell module.

<Solar cell module>

A solar cell module of the present invention includes: a transparent front substrate on which solar light is incident; a cell structure portion formed on the front substrate and having a sealing material for sealing the solar cell element and the solar cell element; (For example, a back sheet for a solar cell) of the present invention, which is formed on the opposite side of the side where the front substrate is located, and which is disposed adjacent to the sealing material.

The solar cell module is produced by, for example, encapsulating a power generation element (solar cell element) connected by a lead wiring for extracting electricity with an encapsulating material such as an ethylene-vinyl acetate copolymer (EVA) resin, And the polyester film (back sheet) obtained by the production method of the polyester film of the present invention.

Examples of the photovoltaic devices include silicon-based materials such as monocrystalline silicon, polycrystalline silicon and amorphous silicon, Group III-V materials such as copper-indium-gallium-selenium, copper-indium-selenium, cadmium-tellurium, gallium- VI group compound semiconductorsystem, and the like can be applied.

Example

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples unless they depart from the spirit of the present invention.

[Examples 1 to 16 and Comparative Examples 1 to 11]

-2 axis extruder -

As shown in Fig. 1, the extruder is provided with a screw having the following constitution in a barrel in which a vent is formed at two points, and a heater capable of performing temperature control by dividing the barrel into nine zones in the longitudinal direction A twin-screw extruder having a double-vented co-rotating and engaging type was prepared.

Screw diameter (D): 110 mm

The length [mm] in which the ratio of the screw length (L) to the screw diameter (D) is 31.5 (L / D)

             (Width of one zone: 3.5 D)

Screw shape: plasticizing kneading part installed just before the first vent

             A deaeration accelerating kneading section is installed just before the second vent

The shearing speed of the plasticizing kneading portion was set to the speed [s ^-1 ] shown in Table 1.

Vent position: 1st vent ... The position of C5 in Fig. 1

           Second vent ... The position of C7 in Fig. 1

As shown in Fig. 2, a gear pump, a metal fiber filter and a die having the following constitutions were connected and the set temperature of the heater for heating the die was set to 280 DEG C and the average residence time was 10 Min.

Gear Pump: 2 Gear Type

Filter: Metal fiber sintered filter (pore diameter 20 탆)

- Raw resin -

Pellets of a polyethylene terephthalate resin (PET resin) having an AV of 13 eq / t and a fluff having AV of 15 eq / t and a bulk density shown in Table 1 were used as a raw resin. In Comparative Example 1 and Comparative Example 2, only PET pellets having no bulkiness and having a bulk density of 0.8 were used, and the raw material resin for AV shown in Table 1 was used. The melting point Tm of the raw resin was all 255 占 폚.

The content of fluff in the raw resin is the amount shown in Table 1. The content of the fluff shown in Table 1 is the ratio (by mass%) of fluff to the total mass of the raw resin.

In the extruder, the first zone C1 on the side of the supply port 12 in Fig. 1 is set at 70 占 폚, the second to eighth zones C2 to C8 are set at 270 占 폚, The temperature was set at 250 ° C.

The feed rate of the extruded product was set to 350 kg / cm 2 by feeding the raw material resin from the feed port 12 at a temperature [占 폚] shown in Table 1 "extruder inlet resin temperature" hr to perform melt extrusion.

For the raw resin in the extruder, a nitrogen gas supply port was formed at the position indicated by N1 in Fig. 1, and the supply amount Q [L / min] of the raw resin was changed to nitrogen Gas was supplied. For example, in Example 1, the supply amount Q of the raw resin is 0.5 times (0.5 Q) [L / min].

The feeding rate of the nitrogen gas was set to the speed shown in Table 1 [m / min].

The molten resin was extruded from the outlet of the extruder at a temperature [占 폚] shown in Table 1 "extruder outlet resin temperature", and the extruded melt (melt) was passed through a gear pump and a metal fiber filter , And extruded from the die into a cooled (cold) roll. The extruded melt was adhered to the cooling roll using an electrostatic application method. The cooling roll is made by using a hollow chilled roll, in which water can be passed through as a fruit to warm the product.

Further, the conveying station (air gap) from the die outlet to the cooling roll surrounds the conveying station, and humidifying air is introduced into the conveying station to adjust the humidity to 30% RH. By adjusting the extrusion amount of the extruder and the shape of the opening of the die in the above-described configuration, the melt thickness was made 3000 탆.

As described above, the production of each of the PET films of Examples 1 to 16 and Comparative Examples 1 to 12 was attempted.

&Lt; Evaluation of PET film &

The weather resistance of the PET film was evaluated based on the elongation at break and? AV of the PET film.

- Measurement of breaking elongation -

The PET film cooled by the cooling roll is subjected to biaxial stretching (3.4 x 3.8 times), and it is judged that the film after the biaxial stretching is half the elongation at break under the moist heat condition (120 占 폚 占 100 RH%). It is judged that it exhibits good weatherability (hydrolysis resistance) at 85 hours or more. The results are shown in Table 1.

Calculating -ΔAV -

The AV of the raw resin and the AV of the melt extruded film were measured to calculate? AV (| AV1-AV2 |) which is the difference between AV (AV1) of the raw resin and AV (AV2) of the melt extruded film. It was judged that the ΔAV was 3 eq / t or less, indicating a good weatherability. The results are shown in Table 1.

[Examples 17 to 22]

The following compounds were used in the respective examples as terminal endblocks.

1. A cyclic carbodiimide compound

1) cyclic carbodiimide compound (1) (&quot; cyclic &quot; in Table 2)

(C) of the above-described cyclic carbodiimide compound (weight average molecular weight Mw = 516) having the following structure was used. The cyclic carbodiimide compound (1) was synthesized with reference to the synthesis method described in Reference Example 1 of JP-A No. 2011-258641.

[Chemical Formula 12]

2. Non-cyclic carbodiimide compound

1) Linear carbodiimide (1) (&quot; Linear &quot; in Table 2)

Stabaxol P400 (manufactured by Rhee Kyume, weight average molecular weight Mw = about 2000) was used.

2) Monocarbodiimide (1) (&quot; Mono &quot; in Table 2)

Stabaxol I (manufactured by Rinkemisa, weight average molecular weight Mw = 362.5) was used.

The structures of these carbodiimide endblock agents are shown below.

[Chemical Formula 13]

- Preparation of PET pellets containing end caps -

The end sealant shown in Table 2 and a polyethylene terephthalate resin (PET resin) having an AV of 13 eq / t were previously melt-mixed and adjusted such that the concentration of the end sealant became 50% by mass of the total amount of the molten mixture Each of the master pellets (PET pellets containing end caps) used in Examples 17 to 22 was prepared.

- Preparation of PET film -

A PET film was produced in the same manner as in Example 1 except that each obtained master pellet was used in place of the pellet of the PET resin used in Example 1 in the production of the PET film of Example 1. [

&Lt; Evaluation of PET film &

The obtained PET films of Examples 17 to 22 were evaluated in the same manner as in the PET film of Example 1 by the breaking elongation and the weather resistance of the PET film from? AV. The evaluation results are shown in Table 2. Table 2 also shows the condition details and evaluation results of Example 1 for reference.

[Examples 23 to 30 and Comparative Example 12]

(1) Production of CHDM-based polyester resin (PCT resin)

First step

(IPA) and terephthalic acid (TPA) as the dicarboxylic acid compound, cyclohexanedimethanol (CHDM) and ethylene glycol (EG) as the diol compounds and using magnesium acetate and antimony trioxide as catalysts at 150 deg. , The mixture was heated to 230 DEG C over 3 hours with stirring and methanol was distilled off to complete the transesterification reaction. At this time, CHDM-based polyester resins (CHDM-1 to CHDM-9) having the compositions shown in Table 3 were obtained by changing the addition amounts of IPA, TPA, CHDM and EG.

· Second step

After completion of the ester exchange reaction, an ethylene glycol solution in which phosphoric acid was dissolved in ethylene glycol was added.

Third step

The polymerization reaction was carried out at a final temperature of 285 DEG C and a degree of vacuum of 0.1 Torr to obtain a polyester, which was then pelletized.

· Fourth step

The polyester pellets obtained above were dried and crystallized at 160 DEG C for 6 hours.

(2) Production of PET-based polyester resin (PET resin)

As shown in Table 3, a PET-based polyester resin (PET-1) was produced in the same manner as the CHDM-based polyester resin except that CHDM and IPA were not added.

The content of cyclohexane dimethanol (CHDM) in the diol compound and the content of isophthalic acid in the dicarboxylic acid compound were measured for the CHDM-based polyester resin obtained as described above by the following method.

(Composition measurement method)

The CHDM-based polyester pellets were dissolved in hexafluoroisopropanol (HFIP) and quantified by ¹ H-NMR. A sample (CHDM, terephthalic acid, EG and isophthalic acid) was measured in advance, and the signal was identified using this.

The amounts of the obtained isophthalic acid residues and the amounts of CHDM residues are shown in Table 3.

The content (mole%) of terephthalic acid (TPA) is 100 mol% - the content of isophthalic acid (IPA) is molar percentage and the molar percentage of CHDM is molar%.

As shown in Table 3, the respective polyester resins of CHDM-3, CHDM-7 and PET-1 were solid-phase-polymerized in a stream of nitrogen at 210 DEG C for 24 hours after drying.

IV and AV of these CHDM-based polyester pellets and PET-based polyester pellets were measured in the same manner as in the PET pellets used in Example 1, and are shown in Table 3

(3) Melting film

(3-1) Extrusion

PET-1 and CHDM-1 to CHDM-9 were dried and then melted and kneaded in a twin-screw extruder under vacuum. The temperature of the melt-kneading was 280 ° C for PET-1, 285 ° C for CHDM-1 to CHDM-4, 305 ° C for CHDM-5 to CHDM-8, and 305 ° C for CHDM-9.

The obtained molten resin was extruded on a casting drum at 25 캜 using a feed block die to produce a single-layer polyester film or a laminated polyester film having a layer structure shown in Table 4. The extruding conditions and the discharging conditions in the extruder for producing each polyester film are shown in Table 5.

The weather resistance of the obtained single-layer polyester film and laminated polyester film was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 5.

Further, the fluff was added in an amount (mass%) shown in Table 5 for all the PET components using the fluff of PET. In the production of the laminated polyester film, fluff was added only to an extruder in which PET-1 was melt-kneaded.

[Examples 31 to 60]

&Lt; Fabrication of solar cell module &gt;

Each of the polyester films of Examples 1 to 30 was used as a back sheet for a solar cell, and the solar cell modules of Examples 31 to 60 were fabricated as follows.

, An EVA sheet (SC50B, manufactured by Mitsui Chemicals, Inc.), a crystalline solar cell, an EVA sheet (SC50B, manufactured by Mitsui Chemicals, Inc.) and a polyester of Examples 1 to 30 One of the films was laminated in this order, and each member was bonded to the EVA sheet by hot pressing using a vacuum laminator (manufactured by Nisshinbo, vacuum laminating machine).

As a result of performing power generation operation for each solar cell module produced, all of the solar cells showed good power generation performance.

Claims (16)

And has a bulk density of 0.2 to 0.7, 10 to 50 mass%, a water content of 20 to 100 ppm, an intrinsic viscosity of 0.70 dl / g to 1.2 dl / g, a temperature of 100 to 160 Lt; 0 &gt; C to the raw material feed port of the twin screw extruder,
The molten resin discharged from the twin screw extruder at a temperature of Tm + 20 ° C to Tm + 30 ° C relative to the melting point Tm of the polyester raw resin is melted and kneaded to melt the polyester raw resin. The process,
And molding the molten resin into a film. The method according to claim 1,
Wherein the biaxial extruder comprises:
At least one vent hole,
A first nitrogen gas supply port for supplying nitrogen gas of 1.1 to 10.0 times the supply amount of the polyester raw material resin [L / min] to the raw material supply port at a position closer to the raw material supply port than the vent hole closest to the raw material supply port Wherein the polyester film is a polyester film. The method according to claim 1,
Wherein the biaxial extruder comprises:
A screw having a kneading portion for plasticizing the polyester raw material resin,
And a second nitrogen gas supply port located in the kneading section for supplying a nitrogen gas to the polyester raw material resin. 3. The method of claim 2,
Wherein the biaxial extruder comprises:
A screw having a kneading portion for plasticizing the polyester raw material resin,
And a second nitrogen gas supply port located in the kneading section for supplying a nitrogen gas to the polyester raw material resin. 3. The method of claim 2,
Wherein the feed rate of the nitrogen gas in the first nitrogen gas feed port is 2 m / min to 50 m / min. The method of claim 3,
Wherein the supply rate of the nitrogen gas in the second nitrogen gas supply port is 2 m / min to 50 m / min. 5. The method of claim 4,
Wherein the supply rate of the nitrogen gas in the first nitrogen gas supply port and the second nitrogen gas supply port is 2 m / min to 50 m / min. The method of claim 3,
The kneading portion, a shear rate of 500 s in the kneading clearance ^-1 ~ 2000 s ^-1 in the polyester film production method. 5. The method of claim 4,
The kneading portion, a shear rate of 500 s in the kneading clearance ^-1 ~ 2000 s ^-1 in the polyester film production method. The method according to claim 1,
A cyclic carbodiimide compound containing a cyclic structure in which one carbodiimide group is bonded to the first nitrogen and the second nitrogen of the carbodiimide group is bonded to the polyester raw resin, By mass to 0.05% by mass to 20% by mass, and melt-kneading the mixture to obtain a molten resin. 3. The method of claim 2,
A cyclic carbodiimide compound containing a cyclic structure in which one carbodiimide group is bonded to the first nitrogen and the second nitrogen of the carbodiimide group is bonded to the polyester raw resin, By mass to 0.05% by mass to 20% by mass, and melt-kneading the mixture to obtain a molten resin. The method of claim 3,
A cyclic carbodiimide compound containing a cyclic structure in which one carbodiimide group is bonded to the first nitrogen and the second nitrogen of the carbodiimide group is bonded to the polyester raw resin, By mass to 0.05% by mass to 20% by mass, and melt-kneading the mixture to obtain a molten resin. delete delete delete delete

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