JP2013049790A - Master pellet of polyester resin composition and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin composition master pellet in which a biaxially oriented film excellent in hydrolysis resistance and tone can be obtained, and to provide a method of manufacturing a master pellet in which the master pellet can be manufactured with stability and at low production cost.SOLUTION: The master pellet of the polyester resin composition comprises performing melt kneading to a polyester resin and 0.5-25 mass% of two or more kinds of terminal blocking agents based on the polyester resin by an extruder, wherein the melt flow rate of the terminal blocking agent with the highest melting point and the terminal blocking agent with the lowest melting point is 2-30 g/10 minutes. The extruder includes: first-fourth barrels that are consecutive in this order; and screws included in the respective first-fourth barrels, both of the zone lengths of the second and third barrels are 15% or more of all zone length of the first-fourth barrels, and the temperatures of the first-fourth barrels fill a given range.

Description

  The present invention relates to a master pellet of a polyester resin composition for imparting hydrolysis resistance, which is blended during film formation in order to impart excellent hydrolysis resistance to a biaxially stretched polyester film, and a method for producing the same. Is.

  Generally, a solar cell module has a transparent filling material (hereinafter also referred to as a sealing material) / solar cell element / sealing material / back sheet (on a glass or front sheet on a light receiving surface side on which sunlight is incident). (Hereinafter also referred to as BS) has a structure in which they are stacked in this order. Specifically, the solar cell element is generally configured to be embedded in a resin (sealing material) such as EVA (ethylene-vinyl acetate copolymer) and further to be attached with a protective sheet for solar cell. The Moreover, as this protective sheet for solar cells, conventionally, a polyester film, particularly a polyethylene terephthalate (hereinafter referred to as PET) film has been used.

  However, the solar cell protective sheet, especially the solar cell backsheet (BS), which is the outermost layer, is expected to be placed in an environment exposed to outdoor wind and rain for a long period of time. Therefore, excellent weather resistance is required.

  Here, polyester films such as PET, which are also used as a back sheet for solar cells, have excellent heat resistance, mechanical properties, chemical resistance, and the like. There is still room for improvement from the viewpoint of hydrolyzability. Hydrolysis is known to be accelerated by the catalytic action of terminal carboxylic acids in the polyester, and as a technique for improving the hydrolysis resistance of the polyester film, for example, a terminal sealing material such as polycarbodiimide may be added to the polyester. The technique to mix | blend is proposed (for example, refer patent document 1).

  On the other hand, as a method of adding an additive to a resin when a polymer film such as a polyester film is melt-cast, a pellet (master pellet) once added with a large amount of additive in addition to a direct addition method directly added at the time of film formation ) Is prepared and diluted at the time of film formation to have an arbitrary blending amount. For example, Patent Document 2 discloses a method of melt kneading a resin and an additive under specific conditions using an extruder having a specific configuration. Patent Document 3 discloses a method of adding two kinds of additives from a plurality of raw material supply ports.

JP 2010-235824 A Japanese Patent No. 4572516 JP 2007-112858 A

  As a result of investigations by the present inventors, excellent hydrolysis resistance can be obtained by combining the film with a combination of at least two types of end-capping agents having very high viscosity and different melting points as end-capping agents. It was found that it can be granted. However, when using at least two kinds of end capping agents having very large viscosity and different melting points, in the direct addition method, the supply hopper of the extruder is contaminated with the end capping material, and blocking occurs. There was a problem that stable production was not possible. Further, if the supply port is soiled at the time of product switching, a loss occurs due to product number switching or the like, resulting in a problem that the manufacturing cost becomes high or the productivity deteriorates. Furthermore, even in the method of producing the master pellet, the method of continuously supplying the end sealing material in a starved state using a feeder from the supply port arranged on a general water-cooled cylinder when producing the master pellet The temperature of the barrel of the supply port becomes high due to heat transfer from the barrel downstream of the supply port heated to the melting temperature (280 ° C.) of the PET resin, and blocking (blocking the supply port with two types of additives having different melting points) Or bridge).

  Further, it has been found that depending on the temperature at which the polyester resin is melted, the end-capping agent is decomposed by heating, and there is a problem that coloring is largely generated in the obtained master pellet.

  That is, the problem to be solved by the present invention is to provide a master pellet of a polyester resin composition capable of obtaining a pellet of a resin composition excellent in hydrolysis resistance and color tone. Moreover, it is providing the manufacturing method of the master pellet of the polyester resin composition with low manufacturing cost which can manufacture the said master pellet stably.

  As a result of intensive studies to solve the above problems, the present inventors have found that a large amount of at least two kinds of end-capping agents having a very high viscosity at the time of melting and different melting points into the pellet at a time. When preparing the added master pellets, the barrel temperature should be sufficiently lower than the melting point of the additive so that it does not melt at the feed port, and the barrel temperature of the extruder is gradually increased to provide a low melting end-capping material and a high melting point. By melting the terminal sealing material and the polyester resin in this order, blocking at the supply port, deterioration of the additive itself and a decrease in the reactivity of the additive can be suppressed, and the barrel temperature when melting the polyester resin is also included. The inventors have found that coloring can be suppressed by suppressing the generation of shearing heat due to the end-capping agent having a high viscosity above a specific range, and the above problems can be solved.

The present invention which is a specific means for solving the above-mentioned problems is as follows.
[1] A polyester resin and 0.5 to 25% by mass of at least two end capping agents with respect to the polyester resin are melt-kneaded by an extruder, and the melting point is the highest among the end capping agents. The melt flow rate of the high end-capping agent and the end-capping agent having the lowest melting point is 2 to 30 g / 10 min as a value measured at a load of 2160 g at each melting point + 10 ° C., and the extruder is continuously in this order. The first barrel to the fourth barrel, and the screws respectively contained in the first barrel to the fourth barrel, and the zone lengths of the second barrel and the third barrel are both It is 15% or more of the total zone length of the first barrel to the fourth barrel, and the temperature of the first barrel to the fourth barrel satisfies the following formulas (1) to (4): Police Master pellet of tellurium resin composition.
Formula (1): T1 <= Tm1-10 degreeC
Formula (2): Tm1-10 ° C. ≦ T2 ≦ Tm2-10 ° C.
Formula (3): Tm2 + 20 ° C. <T3 ≦ Tm3 + 10 ° C.
Formula (4): Tm3 + 10 ° C. ≦ T4 ≦ Tm3 + 40 ° C.
(In the formulas (1) to (4), T1 represents the first barrel temperature (unit: ° C.) to which the end sealant and the polyester resin of the extruder are supplied, and Tm1 is the end of the lowest melting point. The melting point of the sealant (unit: ° C), T2 represents the second barrel temperature (unit: ° C), Tm2 represents the melting point (unit: ° C) of the end sealant with the highest melting point, T3 ( The third barrel temperature (unit: ° C) is represented, Tm3 represents the melting point (unit: ° C) of the polyester resin, and T4 represents the fourth barrel temperature (unit: ° C).
[2] In the master pellet of the polyester resin composition according to [1], the screw has kneading, and the zone lengths of the second barrel and the third barrel are both screws up to the kneading. The length is preferably 15% or more.
[3] In the master pellet of the polyester resin composition according to [1] or [2], it is preferable that the flight shape of the screw included in the first barrel of the extruder is a half-angle flight or a square flight.
[4] In the master pellet of the polyester resin composition according to any one of [1] to [3], the total zone length of the first barrel to the fourth barrel of the extruder is the diameter of the screw. It is preferable that it is at least 5-20D or more with respect to D.
[5] In the master pellet of the polyester resin composition according to any one of [1] to [4], the terminal blocking agent contains at least one of a carbodiimide compound, an epoxy compound, an oxazoline compound, and an isocyanate compound. It is preferable.
[6] In the master pellet of the polyester resin composition according to any one of [1] to [5], the two or more types of end capping agents have a weight average molecular weight of 8000 or more. And it is preferable to contain the terminal blocker whose weight average molecular weight is 1000-5000.
[7] In the master pellet of the polyester resin composition according to any one of [1] to [6], the two or more types of end-capping agents include a carbodiimide compound having a weight average molecular weight of 8000 or more, It is preferable that the carbodiimide compound whose weight average molecular weight is 1000-5000 is included.
[8] A first step of supplying a polyester resin and at least two types of end capping agents of 0.5 to 25% by mass to the polyester resin to the extruder, and the at least two types of end capping A second step of melting a part of the agent, a third step of melting all of the at least two types of end-capping agents, a fourth step of melting the polyester resin, and the molten end-capping A fifth step of melt-mixing the agent and the polyester resin, and the melt flow rate of the end-capping agent having the highest melting point and the end-capping agent having the lowest melting point among the end-capping agents is It is 2-30 g / 10 minutes as a value measured with a load of 2160 g at the melting point + 10 ° C., and the extruder is connected to the first barrel to the fourth barrel in this order, and the first barrel to the fourth barrel. Inside And the second barrel and the third barrel, each of which has a zone length of 15% or more of the total zone length of the first barrel to the fourth barrel. And the temperature of the first barrel to the fourth barrel is controlled so as to satisfy the following formulas (11) to (14): Method.
Formula (11): T1 <= Tm1-10 degreeC
Formula (12): Tm1-10 ° C. ≦ T2 ≦ Tm2-10 ° C.
Formula (13): Tm2 + 20 ° C. <T3 ≦ Tm3 + 10 ° C.
Formula (14): Tm3 + 10 ° C. ≦ T4 ≦ Tm3 + 40 ° C.
(In the formulas (11) to (14), T1 represents the barrel temperature (unit: ° C) of the first step, Tm1 represents the melting point (unit: ° C) of the end melting agent having the lowest melting point, and T2 represents the first step. Tm2 represents the melting point (unit: ° C) of the end sealant having the highest melting point, T3 represents the barrel temperature (unit: ° C) of the third step, and Tm3 Represents the melting point (unit: ° C) of the polyester resin, and T4 represents the barrel temperature (unit: ° C) in the fourth step.)

  ADVANTAGE OF THE INVENTION According to this invention, the master pellet of the polyester resin composition which can obtain the pellet of the resin composition excellent in hydrolysis resistance and color tone can be provided. Moreover, the manufacturing method of the master pellet of the polyester resin composition of the low manufacturing cost which can manufacture the said master pellet stably can be provided.

It is the schematic explaining the structure of the biaxial kneader which is a kneading machine used for the manufacturing method of the master pellet of the polyester resin composition of this invention. It is explanatory drawing explaining a half-angle flight, FIG.2 (B) is the cross-sectional schematic along the 2-2 line of FIG. 2 (A). It is explanatory drawing explaining a corner flight, FIG.3 (B) is the cross-sectional schematic along the 3-3 line of FIG. 3 (A).

Hereinafter, the manufacturing method of the master pellet of the polyester resin composition of this invention and its manufacturing method are demonstrated in detail.
The description of the constituent elements described below may be made based on typical embodiments of the present invention, but the present invention is not limited to such embodiments. In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

[Master Pellet of Polyester Resin Composition and Method for Producing the Same]
The master pellet of the polyester resin composition (hereinafter also referred to as the master pellet of the present invention) is an extruder that includes a polyester resin and at least two types of terminal blockers of 0.5 to 25% by mass with respect to the polyester resin. The melt flow rate of the end-capping agent having the highest melting point and the end-capping agent having the lowest melting point among the end-capping agents is a value measured at a load of 2160 g at each melting point + 10 ° C. 2 to 30 g / 10 minutes, and the extruder has a first barrel to a fourth barrel which are continuous in this order, and a screw included in each of the first barrel to the fourth barrel, The zone lengths of the second barrel and the third barrel are both 15% or more of the total zone length of the first barrel to the fourth barrel, and the first barrel Temperature of Le to fourth barrels and satisfies the following equation (1) to (4).
Formula (1): T1 <= Tm1-10 degreeC
Formula (2): Tm1-10 ° C. ≦ T2 ≦ Tm2-10 ° C.
Formula (3): Tm2 + 20 ° C. <T3 ≦ Tm3 + 10 ° C.
Formula (4): Tm3 + 10 ° C. ≦ T4 ≦ Tm3 + 40 ° C.
(In the formulas (1) to (4), T1 represents the first barrel temperature (unit: ° C.) to which the end sealant and the polyester resin of the extruder are supplied, and Tm1 is the end of the lowest melting point. The melting point of the sealant (unit: ° C), T2 represents the second barrel temperature (unit: ° C), Tm2 represents the melting point (unit: ° C) of the end sealant with the highest melting point, T3 ( The third barrel temperature (unit: ° C) is represented, Tm3 represents the melting point (unit: ° C) of the polyester resin, and T4 represents the fourth barrel temperature (unit: ° C).
Moreover, the manufacturing method (henceforth the manufacturing method of this invention) of the master pellet of the polyester resin composition of this invention is at least 2 or more types of a polyester resin and 0.5-25 mass% with respect to the said polyester resin. A first step of supplying the end-capping agent to an extruder, a second step of melting a part of the at least two types of end-capping agents, and all of the at least two types of end-capping agents. A third step of melting, a fourth step of melting the polyester resin, and a fifth step of melting and mixing the molten end-capping agent and the polyester resin, of the end-capping agent The melt flow rate of the end-capping agent having the highest melting point and the end-capping agent having the lowest melting point is 2 to 30 g / 10 min as a value measured with a load of 2160 g at the respective melting points + 10 ° C. In the extruder, a first barrel to a fourth barrel that are continuous in this order, and a screw included in each of the first barrel to the fourth barrel are arranged, and the second barrel and the third barrel are arranged. Are arranged such that the zone length of each barrel is 15% or more of the total zone length of the first barrel to the fourth barrel, and the temperature of the first barrel to the fourth barrel is set. Control is performed so as to satisfy the following expressions (11) to (14).
Formula (11): T1 <= Tm1-10 degreeC
Formula (12): Tm1-10 ° C. ≦ T2 ≦ Tm2-10 ° C.
Formula (13): Tm2 + 20 ° C. <T3 ≦ Tm3 + 10 ° C.
Formula (14): Tm3 + 10 ° C. ≦ T4 ≦ Tm3 + 40 ° C.
(In the formulas (11) to (14), T1 represents the barrel temperature (unit: ° C) of the first step, Tm1 represents the melting point (unit: ° C) of the end melting agent having the lowest melting point, and T2 represents the first step. Tm2 represents the melting point (unit: ° C) of the end sealant having the highest melting point, T3 represents the barrel temperature (unit: ° C) of the third step, and Tm3 Represents the melting point (unit: ° C) of the polyester resin, and T4 represents the barrel temperature (unit: ° C) in the fourth step.)
Conventionally, the condition for producing a master pellet by melting and kneading a polyester resin and an additive is that the first barrel with the raw material supply port of the extruder is water-cooled, and the second barrel downstream of the first barrel is abrupt. The polyester resin and all of the additives were melted at the same time to prevent the back flow of the raw materials. Although not bound by any theory, a low melting point end-capping agent of at least two types of end-capping agents having different melting points under normal production conditions changes to a molten / viscous liquid, resulting in a high melting point. The end sealant becomes an entrainment ball and closes the hopper (so-called blocking). On the other hand, according to the manufacturing method of the present invention, blocking is suppressed by particularly controlling the temperature of the second barrel and the third barrel having a specific range of zone lengths to be within an appropriate range. Thus, the master pellet of the present invention, which is stable and has a high yield, is excellent in production cost. Moreover, the polyester resin composition and molded object (preferably polyester film) which are excellent in hydrolysis resistance and a color tone can be obtained by using the master pellet of this invention diluted with a polyester resin.

<Polyester resin>
The master pellet of the present invention contains a polyester resin.
The polyester resin may be obtained by synthesis and polymerization, or may be obtained commercially.
The polyester resin can be produced according to a conventionally known polyester production method. That is, it is produced by using a dialkyl ester as an acid component, transesterifying it with a diol component, and then heating the product of this reaction under reduced pressure to perform polycondensation while removing excess diol component. can do. Moreover, it can also manufacture by a conventionally well-known direct polymerization method, using dicarboxylic acid as an acid component. As the reaction catalyst, conventionally known titanium compounds, antimony compounds, germanium compounds, aluminum compounds and the like can be used. The polyester thus obtained can be further increased in the degree of polymerization by subjecting it to solid phase polymerization, and the carboxyl end group concentration can be reduced. The solid phase polymerization is preferably performed in a dryer at a temperature of 200 ° C. to 250 ° C. under a reduced pressure of 1 torr or less or under a nitrogen stream for 5 to 50 hours.

In the manufacturing method of the master pellet of the present invention, the IV of the polyester film using the master pellet is reduced only slightly, and the intrinsic viscosity IV is 0.68 dl / g or more. A biaxial kneader is used. Moreover, it is preferable to perform a solid phase polymerization process in ethylene glycol atmosphere.
Moreover, it is preferable that AV of the polyester film using this master pellet shall be 10 eq / ton or less.

Such an IV value can be adjusted by adjusting the polymerization time during liquid phase polymerization and / or by solid phase polymerization.
Adjustment to AV as described above can be performed by increasing the degree of vacuum during polymerization and suppressing oxidation due to residual oxygen. It is also preferable to perform solid phase polymerization.

  The method for producing a master pellet of the present invention includes an esterification step in which an esterification reaction and / or a transesterification reaction is performed to obtain a polyester film having an intrinsic viscosity IV of 0.68 dl / g or more using the master pellet. Is preferred.

-Esterification process-
In this invention, the esterification process which provides an esterification reaction and a polycondensation reaction and produces | generates polyester can be provided. In this esterification step, (a) an esterification reaction and (b) a polycondensation reaction in which an esterification reaction product produced by the esterification reaction is subjected to a polycondensation reaction can be provided.

(A) Esterification reaction The polyester that forms the polyester film of the present invention includes (A) malonic acid, succinic acid, glutaric acid, adipic acid, suberic acid, sebacic acid, dodecanedioic acid, dimer acid, eicosandioic acid, Aliphatic dicarboxylic acids such as pimelic acid, azelaic acid, methylmalonic acid and ethylmalonic acid, adamantane dicarboxylic acid, norbornene dicarboxylic acid, isosorbide, cyclohexanedicarboxylic acid, decalin dicarboxylic acid, terephthalic acid, isophthalic acid Acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 4,4′-diphenyldicarboxylic acid, 4,4 ′ -Diphenyl ether dicarboxylic acid, 5- A dicarboxylic acid such as thorium sulfoisophthalic acid, phenylendanedicarboxylic acid, anthracene dicarboxylic acid, phenanthrene dicarboxylic acid, aromatic dicarboxylic acid such as 9,9′-bis (4-carboxyphenyl) fluorenic acid, or an ester derivative thereof; Aliphatic diols such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,2-butanediol, 1,3-butanediol, cyclohexanedimethanol, spiroglycol , Cycloaliphatic diols such as isosorbide, aromatic diols such as bisphenol A, 1,3-benzenedimethanol, 1,4-benzenedimethanol, 9,9′-bis (4-hydroxyphenyl) fluorene, and the like The diol compound It can be obtained by an esterification reaction and / or a transesterification reaction.

It is preferable that at least one aromatic dicarboxylic acid is used as the dicarboxylic acid component. More preferably, the dicarboxylic acid component contains an aromatic dicarboxylic acid as a main component. The “main component” means that the proportion of aromatic dicarboxylic acid in the dicarboxylic acid component is 80% by mass or more. A dicarboxylic acid component other than the aromatic dicarboxylic acid may be included. Examples of such a dicarboxylic acid component include ester derivatives such as aromatic dicarboxylic acids.
Further, it is preferable that at least one aliphatic diol is used as the diol component. The aliphatic diol can contain ethylene glycol, and preferably contains ethylene glycol as a main component. The main component means that the proportion of ethylene glycol in the diol component is 80% by mass or more.

  The amount of the aliphatic diol (for example, ethylene glycol) used is in the range of 1.015 to 1.50 mol with respect to 1 mol of the aromatic dicarboxylic acid (for example, terephthalic acid) and, if necessary, its ester derivative. Is preferred. The amount used is more preferably in the range of 1.02 to 1.30 mol, and still more preferably in the range of 1.025 to 1.10 mol. If the amount used is in the range of 1.015 or more, the esterification reaction proceeds favorably, and if it is in the range of 1.50 mol or less, for example, by-production of diethylene glycol due to dimerization of ethylene glycol is suppressed, Many characteristics such as melting point, glass transition temperature, crystallinity, heat resistance, hydrolysis resistance, and weather resistance can be kept good.

  In the polyester resin, the proportion of the aromatic dicarboxylic acid constituent component in all the dicarboxylic acid constituent components in the ester is preferably 90 mol% or more and 100 mol% or less. More preferably, it is 95 mol% or more and 100 mol%. More preferably, it is 98 mol% or more and 100 mol% or less, particularly preferably 99 mol% or more and 100 mol% or less, and most preferably 100 mol%, that is, all of the dicarboxylic acid components should be aromatic carboxylic acid components. If it is less than 90 mol%, the heat and moisture resistance and heat resistance may decrease. By setting the ratio of the aromatic dicarboxylic acid constituent component in the total dicarboxylic acid constituent component in the polyester to 90 mol% or more and 100 mol% or less, it becomes possible to achieve both heat resistance and heat resistance.

  The main repeating unit mainly composed of a dicarboxylic acid component and a diol component in the polyester resin is ethylene terephthalate, ethylene-2,6-naphthalenedicarboxylate, propylene terephthalate, butylene terephthalate, 1,4-cyclohexyl. Those composed of range methylene terephthalate, ethylene-2,6-naphthalenedicarboxylate, and mixtures thereof are preferably used. The main repeating unit referred to here is such that the total of the above repeating units is 70 mol% or more, more preferably 80 mol% or more, still more preferably 90 mol% or more of all repeating units contained in the polyester.

  Furthermore, it is preferable that ethylene terephthalate, ethylene-2,6-naphthalenedicarboxylate, and a mixture thereof are main constituents in that they can be easily polymerized at low cost and have excellent heat resistance. . In this case, when more ethylene terephthalate is used as a structural unit, a cheap and versatile film having heat and heat resistance can be obtained, and more ethylene-2,6-naphthalenedicarboxylate is used as a structural unit. When used, the film can be made more excellent in heat and moisture resistance.

  As other copolymerization components, various dicarboxylic acids or ester-forming derivatives thereof and diols may be copolymerized. Examples of the copolymerizable dicarboxylic acid component include isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4′-diphenyldicarboxylic acid, 4,4'-diphenyl ether dicarboxylic acid, 4,4'-diphenylsulfone dicarboxylic acid and the like can be mentioned. Examples of the alicyclic dicarboxylic acid component that can be copolymerized include 1,4-cyclohexanedicarboxylic acid. Examples of the diol component include ethylene glycol, 1,2-propanediol, neopentyl glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, diethylene glycol, triethylene glycol, polyalkylene glycol, 2,2-bis (4′-β-hydroxyethoxyphenyl) propane, etc. And aliphatic, alicyclic, and aromatic diols. These components may be used alone or in combination of two or more.

  The PET may have different properties depending on the catalyst described later, and one or more selected from a germanium (Ge) catalyst, an antimony (Sb) catalyst, an aluminum (Al) catalyst, and a titanium (Ti) catalyst. PET that is polymerized using two or more types is preferred, and more preferably, a Ti-based catalyst is used.

  Conventionally known reaction catalysts can be used for the esterification reaction and / or the transesterification reaction. Examples of the reaction catalyst include alkali metal compounds, alkaline earth metal compounds, zinc compounds, lead compounds, manganese compounds, cobalt compounds, aluminum compounds, antimony compounds, titanium compounds, germanium compounds, and phosphorus compounds. Usually, it is preferable to add an antimony compound, a germanium compound, or a titanium compound as a polymerization catalyst at an arbitrary stage before the polyester production method is completed. As such a method, for example, when a germanium compound is taken as an example, it is preferable to add the germanium compound powder by dissolving it in ethylene glycol or the like.

It is preferable that the manufacturing method of the polyester film of this invention includes the process of preparing the said polyester resin used for melt film forming by the polycondensation reaction using a Ti-type catalyst.
A polyester film containing a polyester resin polycondensed using the Ti-based catalyst is preferable because weather resistance is hardly lowered. Although not bound by any theory, it is presumed that the reason is as follows. The decrease in weather resistance of the weather resistant polyester film depends to some extent on the hydrolysis of the polyester. The polymerization catalyst also promotes a hydrolysis reaction that is a reverse reaction of condensation, while a Ti catalyst has a low effect of the hydrolysis reaction that is a reverse reaction. Therefore, even if the esterification reaction catalyst remains in the polyester film after film formation to some extent, the polyester resin esterified using a Ti-based catalyst is a polycondensed polyester resin using another catalyst. The weather resistance can be made relatively higher than that.

  The Ti-based catalyst has a high reaction activity and can lower the polymerization temperature. Therefore, in particular, the thermal decomposition of PET during the polymerization reaction can be suppressed and the generation of COOH can be suppressed. In the polyester film of the present invention, the AV (terminal COOH amount) is adjusted to the above preferable range. Also suitable.

For the synthesis of Ti-based polyester using such a Ti compound, for example, Japanese Patent Publication No. 8-30119, Japanese Patent No. 2543624, Japanese Patent No. 3335683, Japanese Patent No. 3717380, Japanese Patent No. 397756, and Japanese Patent No. 396226 are disclosed. Japanese Patent No. 3997866, Japanese Patent No. 3996687, Japanese Patent No. 40000867, Japanese Patent No. 4053837, Japanese Patent No. 4127119, Japanese Patent No. 4134710, Japanese Patent No. 4159154, Japanese Patent No. 4269538, Japanese Patent No. The methods described in JP 2005-340616 A, JP 2005-239940 A, JP 2004-319444 A, JP 2007-204538 A, Japanese Patent No. 3436268, Japanese Patent No. 3780137, and the like can be applied.
As a result, coloring during polymerization and subsequent coloring during melt film formation are reduced, and yellowishness is reduced compared to conventional antimony (Sb) catalyst-based polyester resins, and germanium catalysts having a relatively high transparency are also obtained. It is possible to provide a polyester resin having a color tone and transparency comparable to a polyester resin and having excellent heat resistance. Further, a polyester resin having high transparency and less yellowness can be obtained without using a color tone adjusting material such as a cobalt compound or a pigment.

  This polyester resin can be used for applications requiring high transparency (for example, optical film, industrial squirrel, etc.), and it is not necessary to use an expensive germanium-based catalyst, so that the cost can be greatly reduced. In addition, since foreign matters caused by the catalyst that are likely to occur in the Sb catalyst system are also avoided, the occurrence of failures and quality defects in the film forming process can be reduced, and the cost can be reduced by improving the yield.

Moreover, it is preferable that the produced | generated polyester resin composition satisfy | fills the relationship represented by the following relational expression (i) further.
B value when pelletized after polycondensation ≦ 7.0 (i)
When the polyester resin obtained by polycondensation is pelletized and the b value of the pellet is 7.0 or less, yellowness is small and the transparency is excellent. When the b value is 3.0 or less, the color tone is comparable to that of a polyester resin polymerized with a Ge catalyst.

  The b value is an index representing the color and is a value measured using ND-101D (manufactured by Nippon Denshoku Industries Co., Ltd.).

  The melting point of the polyester used in the present invention is preferably 230 to 320 ° C, more preferably 235 to 310 ° C, and particularly preferably 235 to 300 ° C. Moreover, the thing of 250 degreeC or more is preferable on heat resistance, and the thing of 300 degrees C or less is preferable on productivity. If it is in this range, other components may be copolymerized or blended.

  The molecular weight and molecular weight distribution of the polyester resin are not particularly limited as long as they can be substantially processed, but the weight average molecular weight is usually 10,000 or more, preferably 40,000 or more, and further 80,000. The above is desirable. The weight average molecular weight here refers to the molecular weight in terms of polymethyl methacrylate (PMMA) measured by gel permeation chromatography.

  Various known additives such as an antioxidant, an antistatic agent, a crystal nucleating agent, inorganic particles, and organic particles may be added to the polyester. In particular, inorganic particles and organic particles are effective for imparting easy lubricity to the film surface and enhancing the handleability of the film.

<End sealant>
The master pellet of the present invention is obtained by melting and kneading at least two kinds of end capping agents of 0.5 to 25% by mass with respect to the polyester resin by an extruder, and has the highest melting point among the end capping agents. The melt flow rate of the high end-capping agent and the lowest end-capping agent is 2-30 g / 10 min as a value measured at a load of 2160 g at the respective melting point + 10 ° C.

The end-capping agent is an additive that reacts with the carboxyl group at the end of the polyester to reduce the amount of carboxyl end of the polyester.
Examples of the terminal blocking agent include carbodiimide compounds, oxazoline compounds, epoxy compounds, isocyanate compounds and the like. The master pellet of the present invention preferably contains at least one terminal blocker among an isocyanate compound, a carbodiimide compound and an epoxy compound, and preferably contains two types of carbodiimide compounds. “End-capping agents” may be used alone or in combination.

  In other words, the presence of the end-capping agent has the effect of reacting with the carboxylic acid at the end of the polyester to make the AV value within the range of the present invention (that is, suppressing the hydrolysis of the polyester promoted by the terminal carboxylic acid and weathering resistance Can be kept high). Furthermore, the end-capping agent is bulky and suppresses the movement of the polyester molecules through the free volume. As a result, it also has an effect of suppressing thermal contraction accompanying the movement of molecules.

The master pellet of the present invention is obtained by melt-kneading 0.5 to 25% by mass of a terminal sealing agent with respect to the polyester resin. The addition amount of the terminal blocking agent is preferably 0.5 to 23% by mass, more preferably 1 to 23% by mass, and particularly preferably 1 to 20% by mass.
Moreover, when the master pellet of the present invention is diluted to produce a polyester film, the polyester film preferably contains the end-capping agent in an amount of 0.1% by mass to 5% by mass with respect to the polyester film. More preferably, they are 0.2 mass% or more and 3 mass% or less, More preferably, they are 0.3 mass% or more and 2 mass% or less. When the content is 0.1% by mass or more, the weather resistance can be improved due to the AV lowering effect and low heat shrinkability can be imparted. On the other hand, if it is 5 mass% or less, the addition of the end-capping agent can suppress the decrease in the glass transition temperature (Tg) of the polyester, thereby suppressing the decrease in weather resistance and the increase in thermal shrinkage. This is because the increase in hydrolyzability caused by the increase in the reactivity of the polyester relative to the decrease in the Tg is suppressed, or the mobility of the polyester molecules that increase due to the decrease in the Tg is likely to increase. This is to suppress the heat shrinkage that occurs in the process.

The master pellet of the present invention is obtained by melting and kneading two or more kinds of end capping agents with an extruder, and is composed of the end capping agent having the highest melting point and the end capping agent having the lowest melting point among the end capping agents. The melt flow rate is 2 to 30 g / 10 min as a value measured with a load of 2160 g at each melting point + 10 ° C.
Of the two or more types of end capping agents contained in the master pellet of the present invention, the end capping agent having the highest melting point is preferably 110 to 230 ° C, more preferably 110 to 200 ° C. Preferably, it is 110-180 degreeC.
Of the two or more types of end capping agents contained in the master pellet of the present invention, the melting point of the end capping agent having the lowest melting point is preferably 30 to 90 ° C, more preferably 40 to 90 ° C. It is preferably 45 to 85 ° C.
The difference between the melting point of the end capping agent having the highest melting point and the melting point of the end capping agent having the lowest melting point among the two or more types of end capping agents contained in the master pellet of the present invention is 20 to 200 ° C. It is preferably 20 to 160 ° C, more preferably 25 to 135 ° C. In addition, the end-capping agent having a low melting point and the end-capping agent having a high melting point may each be one kind or a plurality of kinds may be contained.

The melt flow rate (hereinafter also referred to as MFR) of the end capping agent having the highest melting point among the two or more types of end capping agents contained in the master pellet of the present invention is the melting point of the end capping agent +10. It is preferable that it is 2-30g as a value measured with the load of 2160g in ° C, it is more preferable that it is 2-25g, and it is especially preferable that it is 4-25g.
Among the two or more types of end capping agents contained in the master pellet of the present invention, the MFR of the end capping agent having the lowest melting point is 2 to 2 as a value measured at a melting point of the end capping agent + 10 ° C. at a load of 2160 g. It is preferably 30 g, more preferably 5 to 30 g, and particularly preferably 10 to 30 g.

The weight average molecular weight of the end-capping agent having the highest melting point among the two or more types of end-capping agents contained in the master pellet of the present invention is preferably 8,000 or more and 50,000 or less, and preferably 10,000 or more and 40,000. Or less, more preferably 15,000 or more and 30,000 or less. By setting it as such a range, the molecular weight of terminal blocker is large (long), and it has an effect which entangles with other polyester molecules and improves intermolecular interaction. In order to express such an effect, a high molecular weight of 10,000 or more is preferable. When the molecular weight is less than or equal to the upper limit of the molecular weight range, the mobility (reactivity) of the end-capping agent is improved, and it is easy to react (seal) with the polyester end. On the other hand, if the molecular weight range is equal to or more than the lower limit of the molecular weight range, the entanglement effect with other polyester molecules is easily exhibited, and the physical properties of the resin molded body using the obtained master pellet can be improved.
The weight average molecular weight of the end-capping agent having the lowest melting point among the two or more types of end-capping agents contained in the master pellet of the present invention is preferably 1000 or more and 5000 or less, and preferably 1500 or more and 5000 or less. Is more preferable, and particularly preferably 2000 or more and 5000 or less. The above-mentioned end-capping agent having a large molecular weight and a high melting point has a low end-capping ability and is difficult to sufficiently seal the polyester end. On the other hand, an end-capping agent having a small molecular weight and a low melting point has high reactivity and high sealing ability, but it is difficult to exhibit the entanglement effect with other polyester molecules as described above. Therefore, as two or more kinds of end capping agents, a combination of an end capping agent having a low molecular weight and a low melting point and a terminal capping agent having a high molecular weight and a high melting point can be used well after wet heat aging (hereinafter also referred to as thermo). The master pellet which can manufacture the polyester sheet which can obtain various physical properties can be manufactured. When the molecular weight of the end-capping agent having a low melting point is less than or equal to the upper limit of the above molecular weight range, the reactivity is improved, and it is easy to suppress a decrease in molecular weight with a thermo, and the bulkiness is reduced and intermolecular interaction is improved. However, the physical properties can be improved easily. On the other hand, when the molecular weight range is not less than the lower limit of the molecular weight range, it is difficult to volatilize during melt film formation, the sealing ability is improved, the molecular weight is less likely to be reduced by thermo, and the resin molded body using the obtained master pellets Easy to improve physical properties.
In addition, in this invention, although it is preferable that both the high molecular weight end-capping agent of the said range and low molecular weight end-capping agent are contained, other than these, sealing agents other than this invention (for example, molecular weight is 1000). Less than 10,000, less than 10,000, and more than 50,000).
The difference in weight average molecular weight between the melting point of the end-capping agent having the highest melting point and the end-capping agent having the lowest melting point among the two or more types of end-capping agents contained in the master pellet of the present invention is 3000 or more. It is preferably 5,000 or more, more preferably 10,000 or more.

  Moreover, the content ratio (mass ratio) of the end capping agent having the lowest melting point and the end capping agent having the highest melting point is preferably 1:10 to 10: 1, and more preferably 2:10 to 10. 10: 2, more preferably 3:10 to 10: 3. Within this range, the interaction between the two types of end-capping agents tends to be exhibited, which is preferable.

The master pellet of the present invention preferably uses two or more kinds of polycarbodiimide-based end capping agents.
Polycarbodiimide is a compound having a structure (carbodiimide group) represented by (—N═C═N—). For example, an organic isocyanate is heated in the presence of an appropriate catalyst to perform a decarboxylation reaction. Can be manufactured. The weight average molecular weight of polycarbodiimide is obtained by dissolving polycarbodiimide powder in a solvent selected from chloroform, tetrahydrofuran (THF), N-methyl-2-pyrrolidone (NMP) and hexafluoroisopropanol (HFIP), and using GPC By measuring the curve of the distribution curve, the weight average molecular weight obtained from the polystyrene standard can be used.

  The polycarbodiimide can be selected from compounds obtained by polymerizing aliphatic diisocyanates, alicyclic diisocyanates, aromatic diisocyanates and mixtures thereof. Specific examples of the polycarbodiimide include poly (1,6-hexamethylenecarbodiimide), poly (4,4′-methylenebiscyclohexylcarbodiimide), poly (1,3-cyclohexylenecarbodiimide), poly (1,4-cycloheximide). Silenecarbodiimide), poly (4,4′-dicyclohexylmethanecarbodiimide), poly (4,4′-diphenylmethanecarbodiimide), poly (3,3′-dimethyl-4,4′-diphenylmethanecarbodiimide), poly (naphthylenecarbodiimide) ), Poly (p-phenylenecarbodiimide), poly (m-phenylenecarbodiimide), poly (tolylcarbodiimide), poly (diisopropylcarbodiimide), poly (methyl-diisopropylphenylenecarbodiimide), poly (1,3,5- Polycarbodiimides such as (riisopropylbenzene) polycarbodiimide, poly (1,3,5-triisopropylbenzene and 1,5-diisopropylbenzene) polycarbodiimide, poly (triethylphenylenecarbodiimide), poly (triisopropylphenylenecarbodiimide), etc. be able to. Further, as a commercial product, “STABAXOL” manufactured by Rhein Chemie Japan Co., Ltd. can be used. Specifically, examples of the first polycarbodiimide include stabuxol P (molecular weight 3000 to 4000, manufactured by Rhein Chemie Japan), LA-1 (molecular weight about 2000, manufactured by Nisshinbo Chemical Co., Ltd.). Examples of the second polycarbodiimide include stavaxol P400 (molecular weight: about 20000, manufactured by Rhein Chemie Japan) and STABILIZER9000 (molecular weight: about 20000, manufactured by Rhein Chemie).

  The polycarbodiimide is preferably a compound obtained by polymerizing aromatic diisocyanate, and is preferably a polycarbodiimide having a unit structure represented by the following general formula (1).

[Ｒ₁、Ｒ₂、Ｒ₃、Ｒ₄は、それぞれ独立に、炭素数１〜７のアルキル基あるいは水素原子を表す。ｎは繰返し単位数を示す。]

[R ₁ , R ₂ , R ₃ and R ₄ each independently represents an alkyl group having 1 to 7 carbon atoms or a hydrogen atom. n represents the number of repeating units. ]

  Examples of the polycarbodiimide having a unit structure represented by the general formula (1) obtained by polymerizing aromatic diisocyanate include poly (1,3,5-triisopropylphenylene-2,4-carbodiimide), poly (1 , 5-diisopropylphenylene-2,4-carbodiimide) and copolymers thereof can be preferably used.

  The first polycarbodiimide and the second polycarbodiimide include diisocyanate (for example, 2,4,6-triisopropylphenyl 1,3-diisocyanate) and phospholene oxide (for example, 3-methyl-1-phenyl-2). -Phospholene oxide) can be synthesized by heating. The weight average molecular weight of polycarbodiimide can be controlled by selecting the amount of each material added and the reaction time.

  Preferred examples of the epoxy compound include glycidyl ester compounds and glycidyl ether compounds.

  Specific examples of the glycidyl ester compound include benzoic acid glycidyl ester, t-Bu-benzoic acid glycidyl ester, P-toluic acid glycidyl ester, cyclohexanecarboxylic acid glycidyl ester, pelargonic acid glycidyl ester, stearic acid glycidyl ester, and lauric acid glycidyl ester. , Glycidyl palmitate, glycidyl behenate, glycidyl versatate, glycidyl oleate, glycidyl linoleate, glycidyl linolein, glycidyl behenol, glycidyl stearol, diglycidyl terephthalate, isophthalic acid Diglycidyl ester, phthalic acid diglycidyl ester, naphthalenedicarboxylic acid diglycidyl ester Ter, methylterephthalic acid diglycidyl ester, hexahydrophthalic acid diglycidyl ester, tetrahydrophthalic acid diglycidyl ester, cyclohexanedicarboxylic acid diglycidyl ester, adipic acid diglycidyl ester, succinic acid diglycidyl ester, sebacic acid diglycidyl ester, dodecane Examples thereof include diglycidyl diacid, octadecanedicarboxylic acid diglycidyl ester, trimellitic acid triglycidyl ester, and pyromellitic acid tetraglycidyl ester. These may be used alone or in combination of two or more.

  Specific examples of the glycidyl ether compound include phenyl glycidyl ether, O-phenyl glycidyl ether, 1,4-bis (β, γ-epoxypropoxy) butane, 1,6-bis (β, γ- Epoxypropoxy) hexane, 1,4-bis (β, γ-epoxypropoxy) benzene, 1- (β, γ-epoxypropoxy) -2-ethoxyethane, 1- (β, γ-epoxypropoxy) -2-benzyl Oxyethane, 2,2-bis- [р- (β, γ-epoxypropoxy) phenyl] propane and 2,2-bis- (4-hydroxyphenyl) propane and 2,2-bis- (4-hydroxyphenyl) Examples include bisglycidyl polyether obtained by reaction of bisphenol such as methane and epichlorohydrin, and these include one or more. It can be used.

  The oxazoline compound is preferably a bisoxazoline compound, specifically 2,2,2′-bis (2-oxazoline), 2,2′-bis (4-methyl-2-oxazoline), 2,2 ′. -Bis (4,4-dimethyl-2-oxazoline), 2,2'-bis (4-ethyl-2-oxazoline), 2,2'-bis (4,4'-diethyl-2-oxazoline), 2 , 2′-bis (4-propyl-2-oxazoline), 2,2′-bis (4-butyl-2-oxazoline), 2,2′-bis (4-hexyl-2-oxazoline), 2,2 '-Bis (4-phenyl-2-oxazoline), 2,2'-bis (4-cyclohexyl-2-oxazoline), 2,2'-bis (4-benzyl-2-oxazoline), 2,2'- p-phenylenebis (2-oxazoline), 2,2 ' m-phenylenebis (2-oxazoline), 2,2′-o-phenylenebis (2-oxazoline), 2,2′-p-phenylenebis (4-methyl-2-oxazoline), 2,2′-p -Phenylenebis (4,4-dimethyl-2-oxazoline), 2,2'-m-phenylenebis (4-methyl-2-oxazoline), 2,2'-m-phenylenebis (4,4-dimethyl- 2-oxazoline), 2,2′-ethylenebis (2-oxazoline), 2,2′-tetramethylenebis (2-oxazoline), 2,2′-hexamethylenebis (2-oxazoline), 2,2 ′ -Octamethylenebis (2-oxazoline), 2,2'-decamethylenebis (2-oxazoline), 2,2'-ethylenebis (4-methyl-2-oxazoline), 2,2'-tetramethylenebis ( 4, 4-dimethyl-2-oxazoline), 2,2′-9,9′-diphenoxyethanebis (2-oxazoline), 2,2′-cyclohexylenebis (2-oxazoline) and 2,2′-diphenylene Examples thereof include bis (2-oxazoline).

<Other additives>
(Additive for sealant / stabilizer: phosphorus compound)

In the present invention, in addition to the above end-capping agent, it is also preferable to add a compound that suppresses hydrolysis decomposition in the film. In particular, it is preferable to contain a phosphorus compound. Therefore, in this invention, it is preferable that the amount of phosphorus atoms in the polyester film when measured by fluorescent X-ray is 30 ppm or more. More preferably, it is 50 ppm or more, More preferably, it is 60 ppm or more. As the phosphorus compound, it is preferable to use one or more phosphorus compounds selected from the group consisting of phosphoric acid, phosphorous acid, phosphonic acid, methyl esters, ethyl esters, phenyl esters, half esters and other derivatives thereof. In the present invention, phosphoric acid, phosphorous acid, phosphonic acid methyl ester, ethyl ester, and phenyl ester are particularly preferable. Moreover, as a method of containing the phosphorus compound, it is preferable to add the phosphorus compound when manufacturing the polyester raw material chip.
If the phosphorus atom is less than the above range, the hydrolysis inhibiting effect is not exhibited, the molecular weight of the polyester film after thermostating tends to decrease, and the tear strength retention rate decreases accordingly, which is not preferable. On the other hand, if the above range is exceeded, phosphoric acid is generated by the decomposition of the phosphorus compound itself, and the resulting H ⁺ promotes the hydrolysis of the polyester, which tends to lower the molecular weight of the polyester film, resulting in a decrease in tear strength retention. It is not preferable.

  Furthermore, various additives such as compatibilizers, plasticizers, weathering agents, antioxidants, thermal stabilizers, lubricants, antistatic agents, whitening agents, coloring, as long as the effects of the present invention are not impaired. Agents, conductive agents, ultraviolet absorbers, flame retardants, flame retardant aids, pigments and dyes may be added.

<Manufacture of master pellets by melt kneading>
The production method of the present invention includes a polyester resin, a first step of supplying 0.5 to 25% by mass of at least two kinds of end-capping agents to the extruder, and the at least two kinds of the resin. A second step of melting a part of the end-capping agent, a third step of melting all of the at least two types of end-capping agents, a fourth step of melting the polyester resin, and And a fifth step of melt-mixing the terminal sealing agent and the polyester resin.
In order to incorporate the terminal blocking agent and the other additives in the polyester resin, the terminal sealing agent is mixed with a polyester resin (for example, polyester resin pellets) and heated to a specific temperature in the production method of the present invention. Using a shaft kneading extruder, it is kneaded into a polyester resin to form a high concentration master pellet. A master pellet is a pellet in which an additive (sealing agent) is dispersed at a high concentration (3 to 100 times the concentration in a film after film formation), and when this is extruded, the sealing agent is used. By diluting with pellets that have not been added, the feed port (hopper) of the extruder is contaminated with the end sealant compared to the direct addition method, and loss is less likely to occur when switching the product number. Productivity of the polyester resin composition in which the sealant and the like are dispersed and the molded body (for example, a film) is increased.

In the manufacturing method of the present invention, the extruder is provided with first to fourth barrels that are successively arranged in this order, and screws included in the first to fourth barrels, respectively, and the second barrel. And the third barrel are arranged so that the zone length of each barrel is 15% or more of the total zone length of the first to fourth barrels. By arrange | positioning in this way, it can suppress that the temperature of a said 1st barrel rises by heat transfer from a high temperature 4th barrel. The zone length of each barrel of the second barrel and the third barrel is preferably 15-30% of the total zone length of the first barrel to the fourth barrel, and is 25%. It is more preferable.
Moreover, although the said extruder can use what has at least 4 barrels of the 1st barrel-the 4th barrel, you may arrange | position another barrel downstream of the said 4th barrel. The extruder preferably has, for example, 6 or more barrels, and more preferably 8 or more barrels. As a particularly preferred embodiment, there can be mentioned an extruder in which the extruder is provided with first to eighth barrels at equal intervals (biaxial kneading).

  The ratio (L / D) of the screw length (L) and screw diameter (D) of the extruder is not particularly limited, but is preferably 20 to 80 from the viewpoint of the dispersibility of the end-capping agent. -70 are preferable, 30-60 are more preferable, and 30-50 are especially preferable.

  As the extruder, any of a single-screw extruder, a twin-screw extruder, a multi-screw extruder, or a combined extruder such as a combined twin / single-screw combined extruder can be used. However, the operability and cleaning during operation are easy, the dispersibility of the end-capping agent can be improved, and the heat resistance and mechanical properties are improved. A twin-screw / multi-screw extruder is preferable, and a twin-screw / single-screw hybrid extruder is more preferable because the resin temperature is easily controlled.

  When using an extruder having a plurality of screws of two or more axes, such as a twin screw extruder, a multi screw extruder, a twin screw / single screw combined type extruder, etc., the rotational direction of each screw is Either the same direction or different directions may be used.

(First step of supplying two or more kinds of end capping agents to the extruder)
In the manufacturing method of the present invention, in the first step, in the first barrel, the polyester resin and 0.5 to 25% by mass of at least two kinds of end capping agents with respect to the polyester resin are supplied to the extruder. . The temperature of the first barrel is controlled so as to satisfy the following formula (1).
Formula (1): T1 <= Tm1-10 degreeC
The formula (1) more preferably satisfies the following formula (1 ′).
Formula (1 ′): T1 ≦ Tm1−20 ° C.
In addition, the preferable range of Formula (1) is the same as the preferable range of Formula (11).

In the manufacturing method of this invention, it is preferable that the flight shape of the screw contained in the 1st barrel of the said extruder is a half angle flight or a square flight.
If the screw shape of the first barrel (especially the raw material supply port) of the extruder is ball flight, the space volume between the barrel and the barrel may be small, which may promote blockage. For this reason, it is preferable to avoid the blockage by increasing the space volume by using half-angle or angular flight. Further, excessive shear can be reduced, and an increase in temperature due to shearing heat generation near the supply port can be avoided. In particular, in the production method of the present invention, since the temperature is lowered (T1) so that blocking does not occur in the first barrel (particularly the raw material supply port), the barrel temperature can be lowered, and shear heat generation can be suppressed. Preferably, flights or corner flights are used.

  In the present invention, as a method of supplying raw materials to the extruder, a method of directly supplying each raw material individually, a method of supplying all raw materials in a lump after mixing in advance, a high speed mixer such as a Henschel mixer is used. Any method can be used such as supplying the raw material after making it a bean-sized agglomerate, but from the viewpoint of operability and dispersibility of the end-capping agent, each method of supplying each raw material individually, all A method in which the raw materials are mixed in advance and then fed together is preferable. Moreover, it is preferable to supply a raw material using a weight feeder from the point of extrusion stability.

(Second step of melting a part of at least two kinds of end-capping agents)
In the production method of the present invention, in the second step, a part of the at least two kinds of end sealants is melted in the second barrel. At this time, the temperature of the second barrel is controlled so as to satisfy the following expression (2).
Formula (2): Tm1-10 ° C. ≦ T2 ≦ Tm2-10 ° C.
Specifically, in the second step of the production method of the present invention, two types of end-capping agents having different melting points are used, the end-capping agent having the lower melting point is melted, and the end-capping having a higher melting point is performed. It is preferable to control the second barrel temperature so that the agent does not melt.
The formula (2) more preferably satisfies the following formula (2 ′).
Formula (2 ′): Tm1-20 ° C. ≦ T2 ≦ Tm2-20 ° C.
In addition, the preferable range of Formula (2) is the same as the preferable range of Formula (12).

  In the second step, since the end sealant starts to melt, it is preferable to perform forced raw material transfer by self-cleaning from the viewpoint of suppressing backflow, and for that purpose, the screw shape is preferably a ball flight.

(Third step of melting all of at least two kinds of end-capping agents)
In the manufacturing method of the present invention, in the third step, all of the at least two types of end-capping agents are melted in the third barrel. At this time, the temperature of the third barrel is controlled so as to satisfy the following expression (3).
Formula (3): Tm2 + 20 ° C. <T3 ≦ Tm3 + 10 ° C.
The formula (3) more preferably satisfies the following formula (3 ′).
Formula (3 ′): Tm2 + 10 ° C. ≦ T3 ≦ Tm3 + 10 ° C.
In addition, the preferable range of Formula (3) is the same as the preferable range of Formula (13).

(Fourth step of melting the polyester resin)
In the production method of the present invention, in the fourth step, the polyester resin is melted in the fourth barrel. At this time, the temperature of the fourth barrel is controlled so as to satisfy the following expression (4).
Formula (4): Tm3 + 10 ° C. ≦ T4 ≦ Tm3 + 40 ° C.
The formula (4) more preferably satisfies the following formula (4 ′).
Formula (4 ′): Tm3 + 10 ° C. <T4 ≦ Tm3 + 30 ° C.
In addition, the preferable range of Formula (4) is the same as the preferable range of Formula (14).

(Fifth step of melting and mixing the melted end-capping agent and the polyester resin)
In the production method of the present invention, in the fifth step, the molten end-capping agent and the polyester resin are melt-mixed.
In the case of using a composite type extruder such as a twin screw extruder, a multi screw extruder, or a combined twin / single screw type combined extruder as the extruder, a kneading segment is used as a kneading section. Alternatively, it is preferable to have a screw configuration such as a kneading rotor.
If the kneading zone is close to the additive supply port, additives with a large difference in melt viscosity from the base material (polyester resin) (the additive is smaller) are less likely to mix during kneading and separate from the molten base material. Then, the vicinity of the supply port is blocked to return to the supply side. In the production method of the present invention, the total zone length of the first to fourth barrels of the extruder is preferably at least 5 to 20 D or more with respect to the diameter D of the screw, and is 5 to 17 D. Is more preferable, and 5 to 15D is particularly preferable. As described above, the kneading is arranged at a certain distance from the supply port of the first barrel to stabilize the separation state and to prevent the supply port from being blocked. The kneading is preferably at least contained in the fifth barrel immediately downstream of the fourth barrel, i.e. optionally arranged in the fifth barrel.

  When the extruder has a kneading part, the ratio of the minimum gap distance between the screw of the kneading part and the cylinder inner wall and the diameter of the screw can be sufficiently dispersed from the end sealant. A range of 0.001 to 0.1 is preferable.

  In the production method of the present invention, the temperature of the molten resin that has undergone the fifth step is 270 to 300 ° C, more preferably 275 to 300 ° C, more preferably 275 to 300 ° C in that a stable and good color tone is obtained. More preferred is 295 ° C. Here, the molten resin temperature is a resin temperature after melting, and is an actually measured value of the resin temperature in the cylinder after the fourth barrel of the extruder, preferably at least one or more attached to the cylinder This is the resin temperature in the vicinity of the cylinder inner wall that can be measured by the temperature sensor. When measuring by a plurality of temperature sensors, it is preferable that both the lowest resin temperature and the highest resin temperature are included in the temperature range. If the maximum resin temperature is higher than the above temperature range, discoloration due to burning increases, and if the minimum resin temperature is lower than the above temperature range, the dispersibility of the naturally-derived organic filler deteriorates.

  In the present invention, it is preferable to introduce an inert gas such as nitrogen or melt knead under reduced pressure from the viewpoint that a resin composition having a stable and good color tone can be obtained.

(Use)
By using the master pellet of the resin composition of the present invention, a resin composition or a molded product can be obtained directly or indirectly.

The master pellet of the resin composition of the present invention obtained by melt-kneading by the above-described method for producing a resin composition is granulated or pulverized into a pellet or powder form, and the pellet or powder is converted into a polyester resin or the like. The desired molded product can be obtained by diluting into a molding machine in which another mold having a desired shape is placed.
Among the molded products, a polyester film is preferable, and a polyester film for a back sheet of a solar cell module is more preferable. The polyester film is preferably produced, for example, as follows. First, a raw fabric (unstretched) polyester sheet constituting the polyester film is produced. In order to produce the raw polyester sheet, for example, the polyester pellets prepared above and the master pellet of the present invention containing the end sealant were melted using an extruder and discharged from a die. Then, it cools and solidifies and shape | molds in a sheet form.
When laminating films, a plurality of different polymers are melt laminated using two or more extruders and manifolds or merging blocks.
The melt (melt) extruded from the extruder in this way is solidified on a casting (cooling) roll to obtain an original fabric (unstretched film). The temperature of the cooling roll is preferably 10 ° C. or more and 60 ° C. or less, more preferably 15 ° C. or more and 55 ° C. or less, and further preferably 20 ° C. or more and 50 ° C. or less. At this time, in order to improve the adhesion between the melt and the cooling roll, an electrostatic application method, an air knife method, a method of forming a water film on the cooling roll, or the like can be preferably used.
Further, when extruding the melt into a cast roll, the linear velocity of the cast roll is preferably 10 m / min or more, more preferably 15 / min to 50 m / min, and even more preferably 18 m / min to 40 m / min. It is. Above the lower limit of this range, the residence time of the resin in the extruder is not excessively long, and the end-capping agent is difficult to thermally decompose, which is preferable. On the other hand, if it is below the upper limit of the above range, the shear rate in the extruder is reduced, thereby reducing the heat generation and making the sealant difficult to thermally decompose, which is preferable.

  At this time, it is preferable to use various types of filters, for example, filters made of materials such as sintered metal, porous ceramic, sand and wire mesh, in order to remove foreign substances and denatured polymers. Moreover, you may provide a gear pump as needed in order to improve fixed_quantity | feed_rate supply property.

  This raw fabric (unstretched) polyester sheet is preheated above its glass transition temperature, and then stretched 2 to 4 times (longitudinal stretching) between two rolls having different rotational speeds, and then cooled to form a uniaxially stretched film. obtain.

  The above uniaxially stretched film is continuously gripped at both ends of the film, preheated with hot air, stretched 3 to 5 times in the direction perpendicular to the uniaxial stretch at a temperature not lower than the glass transition temperature and lower than the crystallization temperature, Heat and crystallize at a temperature above the crystallization temperature. Thereafter, the residual stress is released by heating at the same temperature or higher, and cooled to obtain a biaxially stretched film.

  You may provide an easily bonding layer, an antistatic layer, and an easily slipping layer by apply | coating various additives to the surface of the obtained biaxially stretched film as needed.

  The present invention will be described more specifically with reference to the following examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the examples shown below. Unless otherwise specified, “part” is based on mass.

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

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

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

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

Subsequently, the reaction product obtained by the transesterification reaction is further transferred from the second double condensation reaction tank to the third triple condensation reaction tank. In this reaction tank, the reaction tank temperature is 278 ° C. and the reaction tank pressure is 1. While stirring at 5 torr (2.0 × 10 ⁻⁴ MPa), the reaction (transesterification reaction) was carried out under the condition of a residence time of 1.5 hours. Carboxylic acid value: 24 eq / ton, IV (intrinsic viscosity): 0.63 dl / G reaction product (polyethylene terephthalate) was obtained.

-Step (C)-
The resin was dried at 170 ° C. for 5 hours. Thereafter, the pellets were transferred to a solid phase polymerization tank, and solid phase polymerization was performed at 210 ° C. while flowing N ₂ gas containing 200 ppm of water vapor into the solid phase polymerization tank at a flow rate of 1 Nm ³ / hr per kg of resin. By changing the solid state polymerization time and the ethylene glycol (EG) gas concentration blown into the N ₂ gas, an intrinsic viscosity of 0.78 dl / g, a carboxylic acid value of 12 eq / ton, and a melting point of 257 ° C. polyester resin were obtained.
The obtained polyester resin was designated as polyester 1.
Note that the AV decreases and the IV increases by increasing the solid phase polymerization time. Moreover, AV can be reduced by increasing EG gas. Note that IV is not affected.

[Production Example 2]
(Synthesis of polyester 2 / Sb series)
To a mixture of 100 parts by mass of dimethyl terephthalate and 60 parts by mass of ethylene glycol, 0.08 parts by mass of calcium acetate and 0.03 parts by mass of antimony trioxide are added, and the mixture is heated and heated by a conventional method to perform a transesterification reaction. It was. Next, the transesterification product is added to 0.16 parts by mass of lithium acetate and 0.14 parts by mass of trimethyl phosphate, and then transferred to a polymerization reaction tank. Next, the reaction system was gradually depressurized while being heated and heated, and polymerization was performed at 290 ° C. under a reduced pressure of 1 mmHg by a conventional method to obtain a polyester (polyethylene terephthalate) having an intrinsic viscosity [η] of 0.52. The polyester is cut into a rectangular parallelepiped of 2 mm × 4 mm × 4 mm on each side, and the heat treatment time is adjusted at 230 ° C. under a reduced pressure of 0.5 mmHg using a rotary vacuum polymerization apparatus, and the intrinsic viscosity is 0.80 dl / g. A polyester resin having an acid value of 14 eq / ton and a melting point of 257 ° C. was obtained.
The obtained polyester resin was designated as polyester 2.

[Example 1]
Production of master pellets-extrusion molding (synthesis process, film formation process)-
For 98.5 parts by mass of the polyester 1 solid-phase polymerized by the above method, the end capping agent shown in Table 1 is the end capping agent 1 (Stavaxol P (carbodiimide compound having a weight average molecular weight of 3500, manufactured by Rhein Chemie Japan)). 0.5 part by mass and 1.0 part by mass of end-capping agent 3 (Stavaxol P400 (carbodiimide compound having a weight average molecular weight of about 20,000, manufactured by Rhein Chemie Japan)) were mixed to prepare a master pellet.

上記表１中、ＴｍはＪＩＳ Ｋ７１９６に従って測定した融点を表す。ＭＦＲはＪＩＳ Ｋ７２１０に従って測定した値メルトフローレートを表し、それぞれの末端封止剤の融点（＝Ｔｍ）＋１０℃における荷重２１６０ｇで測定した値を表す。
カルボジイミドＬＡ−１は日清紡ケミカル（株）製の重量平均分子量約２０００のカルボジイミド化合物であり、スタバクゾールＰ１００はラインケミージャパン製の重量平均分子量約１００００のカルボジイミド化合物である。

In Table 1 above, Tm represents the melting point measured according to JIS K7196. MFR represents the value melt flow rate measured according to JIS K7210, and represents the value measured at a melting point (= Tm) of each end-capping agent + load of 2160 g at 10 ° C.
Carbodiimide LA-1 is a carbodiimide compound having a weight average molecular weight of approximately 2000 manufactured by Nisshinbo Chemical Co., Ltd., and Stavaxol P100 is a carbodiimide compound having a weight average molecular weight of approximately 10,000 manufactured by Rhein Chemie Japan.

The master pellet was prepared using the twin-screw kneading extruder shown in FIG. That is, PET resin is added from the hopper, and the powder end-capping agent is added from the hopper while metering, and the liquid end-capping agent is added from the port provided in the twin-screw kneading extruder using a metering pump. Kneaded. The kneaded composition was extruded into a strand shape, then cooled with water and cut to prepare master pellets of the polyester resin composition of Example 1.
In the biaxial kneading extruder used in Example 1, the first barrel to the eighth barrel were installed at equal intervals.
A biaxial screw having a total length L = 1200 mm and a diameter D = 40 mm was installed in the first to eighth barrels. The screw shape in the first barrel is the half-angle flight shown in FIG. 2, the kneading is arranged in the fifth barrel, the screw shape in the second to fourth barrels is the ball flight, and the screw configuration Was screw 1. At this time, the total zone length of each of the first barrel to the fourth barrel is 15D, and the zone lengths of the second barrel and the third barrel are all the lengths of the first barrel to the fourth barrel. This is 25% of the zone length.
Further, the temperature T1 of the first barrel to which the end sealant and the polyester resin of the extruder are supplied is 30 ° C., the second barrel temperature T2 is 80 ° C., the third barrel temperature T3 is 230 ° C., The fourth barrel temperature T4 was 290 ° C. The temperature of the fifth barrel to the eighth barrel was the same as the fourth barrel temperature, and then melted and extruded from the eighth barrel at a molten resin temperature of 287 ° C. At this time, the current value of the extruder was 62 A, and no blocking occurred.
The temperature of each barrel is a value measured by a temperature sensor attached in the vicinity of the inner wall of the cylinder at the central portion of the zone length of each barrel. The molten resin temperature is a value obtained by measuring the extruded molten resin with a contact thermometer at the strand die outlet.

  The pellet color of the obtained master pellet was measured by the following method. The results are shown in Table 2 below.

-Measurement of physical properties of resin composition pellets-

(Pellet color)
Using ND-101D (manufactured by Nippon Denshoku Industries Co., Ltd.), the pellet color (b value) of the target master pellet was measured by the following method.
The pellet color (b value) needs to be 7 or less.

<3> Formation of polyester film substrate (biaxially stretched film) After drying the obtained master pellet of the polyester resin composition of Example 1 to a moisture content of 100 ppm or less, the resin composition as a whole is a low-temperature type. Using the same polyester 1 as in the preparation of the master pellet so that the content of the end-capping agent 1 is 0.1% by mass and the content of the high-temperature type end-capping agent 3 is 0.2% by mass. Extrusion was performed while mixing to obtain an unstretched film. In addition, the addition amount of sealing agent here points out the mass% with respect to a polyester resin. For extrusion, a twin-screw extruder was used and melted and kneaded at 280 ° C. in a nitrogen stream, and this melt (melt) was extruded through a gear pump, a filter and a die onto a chill roll to produce an unstretched film with a thickness of 2585 μm. did.
After heating this unstretched film with a radiant heater until the film surface temperature reaches about 85 ° C., it is 3.4 times in the length direction, then sent to the tenter and heated until the film surface temperature reaches about 140 ° C. A biaxially stretched film having a thickness of 188 μm was obtained by stretching 4.2 times in the direction.

  The intrinsic viscosity IV and carboxyl group content AV of the obtained biaxially stretched film were measured by the following method, and the film color was measured by the following method. Moreover, the hydrolysis resistance was measured by the following method. The results are shown in Table 2 below.

-Measurement of physical properties of stretched film-
(Intrinsic viscosity)
After crushing the target biaxially stretched film, it is dissolved in 0.01 g / ml using a 1,2,2-tetrachloroethane / phenol (= 2/3 [mass ratio]) mixed solvent to obtain an Ubbelohde type. It measured at the temperature of 25 degreeC using the viscometer (AVL-6C, Asahi Kasei Technosystem company). The following formula was used as a formula for calculating the intrinsic viscosity, and the sample was dissolved at 120 ° C. for 30 minutes.
ηsp / C = [η] + K [η] ² · C
Here, ηsp = (solution viscosity / solvent viscosity) −1, C is the dissolved polymer weight per 100 ml of solvent (in this measurement, 1 g / 100 ml), and K is the Huggins constant (0.343). ).
The intrinsic viscosity IV needs to be 0.68 dl / g or more.

(Terminal carboxyl group content)
The terminal carboxyl group content (AV) was determined according to H. A. Pohl, Anal. Chem. 26 (1954) 2145, and the measurement was performed. Specifically, the target biaxially stretched film is pulverized and dried in a vacuum dryer at 60 ° C. for 30 minutes. Next, 0.1000 g of the polyester immediately after drying is weighed, 5 ml of benzyl alcohol is added, and then dissolved by stirring with heating at 205 ° C. for 2 minutes. After cooling, the solution is completely dissolved in a mixed solution of 15 ml / chloroform (= 2/3; volume ratio), phenol red is used as an indicator, and an alkaline standard solution (0.0125N KOH-benzyl alcohol methanol mixture). The solution was titrated to the neutralization point (pH = 7.3 ± 0.1) and calculated from the appropriate amount.
The terminal carboxyl group content (AV) needs to be 10 or less.

(Film color)
Using ND-101D (manufactured by Nippon Denshoku Industries Co., Ltd.), the film color (b value) of the target biaxially stretched film was measured by the following method.
The film color (b value) needs to be 2 or less at a thickness of 180 to 200 μm.

(Hydrolysis resistance (PCT test))
When wet heat treatment (thermo-treatment) is performed at 120 ° C. and relative humidity of 100%, the case where the tensile fracture elongation retention before and after the treatment is 50% is less than 125 hours, x is 125 hours or more Was marked with ◯, and when crushed over 130 hours, marked with ◎. The tensile test was in accordance with JIS K 7127.
Breaking elongation retention [%] = (breaking elongation after thermo treatment) / (breaking elongation before thermo treatment) × 100

  The obtained master pellet has a pellet color b value of 7 or less, and the biaxially stretched film prepared by diluting the master pellet has IV and AV values within the range. As a result, the resulting film color, water resistance Degradability was satisfied.

[Examples 2-5, 7, 8, Comparative Examples 1-8]
In Example 1, the master pellets were produced in the same manner as in Example 1 except that the types and addition amounts of the raw materials were changed to the ratios shown in Table 2 and melted and kneaded using the extruder and production conditions shown in Table 2 below. In the same manner as in Example 1, the master pellets were diluted to obtain resin composition pellets.

[Example 6]
For the screw described in the first embodiment, the screw shape in the first barrel is the square flight shown in FIG. 3, the kneading is arranged in the fifth barrel, and the screws in the second to fourth barrels. The shape was ball flight, and the screw configuration was screw 2.

  These results are shown in Table 2 below.

From the results of Table 2 above, it was found that the pellet color of the resin composition obtained was excellent by using the production method of the present invention. Moreover, it turned out that the terminal carboxyl group content of the biaxially stretched film obtained using this master pellet, an intrinsic viscosity, a color tone, and hydrolysis resistance are excellent. Moreover, it turned out that the usage-amount of a master pellet does not increase too much by making the compounding quantity of terminal blocker 0.5 mass% or more, and it is excellent also in manufacturing cost.
From the comparative example 1, when the compounding quantity of terminal blocker exceeded 20 mass%, it turned out that a pellet cannot be produced.
From the comparative example 2, when 1st barrel temperature T1 became higher than the upper limit of the range of this invention, it turned out that blocking generate | occur | produced and a pellet cannot be produced.
From Comparative Example 3, when the second barrel temperature T2 is lower than the lower limit of the range of the present invention, the shear heat generation becomes large, the resin temperature rises, the terminal sealing material itself is decomposed by the heat generation, and the AV at the time of dilution It was found that the value increased and colored. Moreover, it turned out that the intrinsic viscosity of the biaxially stretched film obtained by dilution also becomes low, and also the improvement effect of hydrolysis resistance becomes low.
From Comparative Example 4, when the second barrel temperature T2 is higher than the upper limit of the range of the present invention, the end sealing material melted in the barrel fills the barrel, and the amount of sealing material and the reactivity are also reduced. It was found that variation occurred and eventually deposited to the supply port, blocking occurred, and pellets could not be produced.
From Comparative Example 5, when the third barrel temperature T3 is lower than the lower limit of the range of the present invention, shear heat generation becomes large, the resin temperature rises, and the terminal sealing material itself is decomposed by heat generation, resulting in a master pellet. The color deteriorated. Moreover, it turned out that the biaxially stretched film color b value obtained by dilution, AV value is also high, and an intrinsic viscosity is also low, As a result, hydrolysis resistance performance also becomes low.
From Comparative Example 6, when the third barrel temperature T3 is higher than the upper limit of the range of the present invention, the sealing material melted in the barrel fills the barrel, and the blending amount and reactivity of the sealing material also vary. It finally turned out that it was deposited to the supply port, and blocking occurred over time, making it impossible to produce pellets.
From Comparative Example 7, when the fourth barrel temperature T4 is lower than the lower limit of the range of the present invention, shear heat generation becomes large, the resin temperature rises, and the terminal sealing material itself is decomposed by heat generation, resulting in a master pellet. The color deteriorated. Moreover, it turned out that the biaxially stretched film color b value and AV value which were obtained by dilution are also high, and an intrinsic viscosity is also low, As a result, hydrolysis resistance becomes low.
From the comparative example 8, when the 4th barrel temperature T4 was higher than the upper limit of the range of this invention, the color of the obtained master pellet deteriorated. Moreover, it turned out that the biaxially stretched film color b value and AV value which were obtained by dilution are also high, and an intrinsic viscosity is also low, As a result, hydrolysis resistance becomes low.
From Comparative Examples 5 and 7, when the molten resin temperature exceeded 310 ° C., the carbodiimide was decomposed, and the performance of the master pellet was decreased, and both IV and AV tended to deteriorate. As a result, even when the present master pellet was diluted, there was little improvement in the hydrolysis resistance of the obtained biaxially stretched film.
In addition, when the electric current value of the extruder was too large, it turned out that the load to an extruder is too large and stable production is difficult.

DESCRIPTION OF SYMBOLS 1 1st barrel 2 2nd barrel 3 3rd barrel 4 4th barrel 5 5th barrel 6 6th barrel 7 7th barrel 8 8th barrel 10 Kneader (biaxial kneader)
13-angle flight or half-angle flight element 13A Flight 13B Flight front 13C Flight rear 13D Screw groove 16 Raw material supply port 18 Hopper Z1 First barrel zone length Z2 Second barrel zone length Z3 Third barrel Zone length Z4 Zone length 4 of the fourth barrel L Screw length

Claims (8)

A polyester resin and 0.5 to 25% by mass of at least two kinds of end-capping agents based on the polyester resin are melt-kneaded by an extruder,
Among the above end-capping agents, the melt flow rate of the end-capping agent having the highest melting point and the end-capping agent having the lowest melting point is 2 to 30 g / 10 minutes as a value measured at a load of 2160 g at the respective melting points + 10 ° C. Yes,
The extruder has a first barrel to a fourth barrel which are continuous in this order, and a screw included in each of the first barrel to the fourth barrel,
The zone lengths of the second barrel and the third barrel are both 15% or more of the total zone length of the first barrel to the fourth barrel,
The master pellet of the polyester resin composition, wherein the temperature of the first barrel to the fourth barrel satisfies the following formulas (1) to (4).
Formula (1): T1 <= Tm1-10 degreeC
Formula (2): Tm1-10 ° C. ≦ T2 ≦ Tm2-10 ° C.
Formula (3): Tm2 + 20 ° C. <T3 ≦ Tm3 + 10 ° C.
Formula (4): Tm3 + 10 ° C. ≦ T4 ≦ Tm3 + 40 ° C.
(In the formulas (1) to (4), T1 represents the first barrel temperature (unit: ° C.) to which the end sealant and the polyester resin of the extruder are supplied, and Tm1 is the end of the lowest melting point. The melting point of the sealant (unit: ° C), T2 represents the second barrel temperature (unit: ° C), Tm2 represents the melting point (unit: ° C) of the end sealant with the highest melting point, T3 ( The third barrel temperature (unit: ° C) is represented, Tm3 represents the melting point (unit: ° C) of the polyester resin, and T4 represents the fourth barrel temperature (unit: ° C).   2. The screw according to claim 1, wherein the screw has kneading, and the zone lengths of the second barrel and the third barrel are both 15% or more of the length of the screw up to the kneading. Master pellets of the polyester resin composition described.   The master pellet of the polyester resin composition according to claim 1 or 2, wherein the flight shape of the screw contained in the first barrel of the extruder is a half-angle flight or a square flight.   The total zone length of the first barrel to the fourth barrel of the extruder is at least 5 to 20 D or more with respect to the diameter D of the screw. Master pellets of the polyester resin composition described.   The said terminal blocker contains at least 1 sort (s) of a carbodiimide compound, an epoxy compound, an oxazoline compound, and an isocyanate compound, The master pellet of the polyester resin composition as described in any one of Claims 1-4 characterized by the above-mentioned.   The two or more types of end capping agents include a terminal capping agent having a weight average molecular weight of 8000 or more and a terminal capping agent having a weight average molecular weight of 1000 to 5000. The master pellet of the polyester resin composition as described in any one of these.   The said 2 or more types of terminal blocker contains the carbodiimide compound whose weight average molecular weight is 8000 or more, and the carbodiimide compound whose weight average molecular weight is 1000-5000, The any one of Claims 1-6 characterized by the above-mentioned. A master pellet of the polyester resin composition according to Item. A first step of supplying a polyester resin and 0.5 to 25% by mass of at least two kinds of end-capping agents to the extruder with respect to the polyester resin;
A second step of melting a part of the at least two types of end-capping agents;
A third step of melting all of the at least two types of end-capping agents;
A fourth step of melting the polyester resin;
A fifth step of melt-mixing the molten end-capping agent and the polyester resin,
Among the above end-capping agents, the melt flow rate of the end-capping agent having the highest melting point and the end-capping agent having the lowest melting point is 2 to 30 g / 10 minutes as a value measured at a load of 2160 g at the respective melting points + 10 ° C. Yes,
In the extruder, the first barrel to the fourth barrel which are continuous in this order, and the screws respectively contained in the first barrel to the fourth barrel are arranged,
The second barrel and the third barrel are arranged so that the zone length of each barrel is 20% or more of the total zone length of the first barrel to the fourth barrel,
A method for producing a master pellet of a polyester resin composition, wherein the temperature of the first barrel to the fourth barrel is controlled to satisfy the following formulas (11) to (14).
Formula (11): T1 <= Tm1-10 degreeC
Formula (12): Tm1-10 ° C. ≦ T2 ≦ Tm2-10 ° C.
Formula (13): Tm2 + 20 ° C. <T3 ≦ Tm3 + 10 ° C.
Formula (14): Tm3 + 10 ° C. ≦ T4 ≦ Tm3 + 40 ° C.
(In the formulas (11) to (14), T1 represents the barrel temperature (unit: ° C) of the first step, Tm1 represents the melting point (unit: ° C) of the end melting agent having the lowest melting point, and T2 represents the first step. Tm2 represents the melting point (unit: ° C) of the end sealant having the highest melting point, T3 represents the barrel temperature (unit: ° C) of the third step, and Tm3 Represents the melting point (unit: ° C) of the polyester resin, and T4 represents the barrel temperature (unit: ° C) in the fourth step.)

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