Method for producing polyester resin molded article, masterbatch, and method for producing the same

Abstract

To provide a masterbatch for polyester resin chain extension which is used in the production of a polyester resin molded article which exhibits excellent moldability and is capable of reducing deactivation even when a resin having a high flow initiation temperature such as a PET resin is used as a component of the masterbatch.SOLUTION: This masterbatch for extending the chain of a polyester resin (A) is obtained by dispersing a pulverized polyester resin (C) having a flow initiation temperature of 160°C or higher in a resin (B) having an epoxy group and a flow initiation temperature of 150°C or less.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a method for producing a polyester resin molded article, and also to a masterbatch having chain extendability for polyester resin used in producing the polyester resin molded article, and a method for producing the same. [Background technology]

[0002] Polyester resins have excellent heat resistance, strength, etc., and are therefore used in a wide range of fields, including synthetic fibers, films, PET bottles, machine parts, automobile parts, containers, electronic materials, etc. The market is in demand for polyester resins with better physical properties, including recycled polyester resins, and various proposals have been made. Meanwhile, the problem of plastic waste has become an important issue worldwide, and there is a demand for the development of recycling technologies. One recycling technology is cascade recycling, in which used PET bottles are collected, crushed into flakes, and used as raw material to produce other products from PET bottles, such as recycled fibers. There is also horizontal recycling (bottle-to-bottle), in which used PET bottles are chemically or mechanically recycled to return their raw materials and are then remade into PET bottle products.

[0003] The molecular weight of polyester resin is reduced by heat or moisture during the recovery process for recycling. This causes a significant decrease in the moldability of the recycled polyester resin, so a technology to improve the intrinsic viscosity (IV) value of the recycled polyester resin is required. As a method for improving the IV value, a method has been proposed in which a chain extender such as carbodiimide or epoxy resin is added directly or as a masterbatch to the polyester resin to be modified.

[0004] Patent Document 1 discloses a method for producing a polyester resin molded product by adding a masterbatch for promoting solid-phase polymerization to a polyester resin to be modified. This masterbatch contains a polyester resin (A) having a specific structural unit, and an ester polycondensation catalyst (B) containing a specific amount of at least one catalyst selected from a phosphorus-based catalyst, a titanium-based catalyst, and an antimony-based catalyst. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 7268230 Summary of the Invention [Problem to be solved by the invention]

[0006] By forming a masterbatch as in Patent Document 1, it is possible to improve the distribution to the recycled polyester resin to be modified. The masterbatch is produced, for example, by melt-kneading a chain extender and a polyester resin, but these components may react with moisture in the air during melt-kneading or react with each other, which may deactivate the IV improving function of the masterbatch. To reduce this deactivation, it is effective to select a polyester resin with a low flow initiation temperature.

[0007] Ideally, PET bottles should be recycled repeatedly. For this reason, it is desirable to use the same type of resin as the resin to be modified and the dispersing resin that disperses the chain extender used in the masterbatch. For example, in recycling PET bottles, it is desirable to use polyethylene terephthalate (PET) resin as the dispersing resin that disperses the chain extender in the masterbatch. However, since PET resin has a high flow initiation temperature, there is a problem that the chain extensibility is easily deactivated when melt-kneading the masterbatch in the masterbatch manufacturing process. For this reason, even in the case of a masterbatch that modifies recycled PET resin, for example, a resin with a relatively low flow initiation temperature is selected as the resin for the masterbatch, rather than PET resin.

[0008] Although the above describes the problems involved in recycling PET resin, similar problems can arise when recycling polyester resins in general whose physical properties need to be improved.

[0009] The present disclosure has been made in consideration of the above problems, and has an object to provide a method for producing a polyester resin molded product having excellent moldability, which can reduce deactivation even when a resin with a high flow initiation temperature, such as a PET resin, is used as a masterbatch component, and a masterbatch for chain extension of a polyester resin used in the production method, and a production method thereof. [Means for solving the problem]

[0010] As a result of extensive investigations, the present inventors have found that the problems of the present disclosure can be solved in the following aspect, and have thus completed the present disclosure. [1]: A masterbatch for chain extension of a polyester resin (A), A masterbatch for chain extension in which pulverized polyester resin (C) with a flow temperature of 160°C or higher is dispersed in resin (B) which has epoxy groups and a flow temperature of 150°C or lower. [2]: The masterbatch for chain extension according to [1], in which, in a cross-section of the masterbatch, the resin (B) forms a continuous phase, and the polyester resin (C) forms a dispersed phase. [3]: The masterbatch for chain extension according to [2], wherein, when a 2 mm × 2 mm area of ​​a cross section of the masterbatch is observed with an optical microscope, the average particle size of the polyester resin (C) is 10 to 1,000 μm as determined by image analysis of the dispersed phase. [4]: The masterbatch for chain extension according to any one of [1] to [3], wherein the content of the resin (B) in 100% by mass of the masterbatch is 40 to 95% by mass. [5]: The polyester resin (C) is a resin containing structural units derived from terephthalic acid or an ester-forming derivative thereof and / or isophthalic acid or an ester-forming derivative thereof, and containing 50 mol % or more of structural units derived from a linear glycol having 2 to 4 carbon atoms and / or a dehydration condensate of two molecules thereof relative to 100 mol % of structural units derived from a polyhydric alcohol. The masterbatch for chain extension according to any one of [1] to [4]. [6]: A masterbatch for chain extension according to any one of [1] to [5], having an epoxy value of 0.7 to 3.5 mmol / g before blending with resin (B). [7]: The masterbatch for chain extension according to any one of [1] to [6], wherein the resin (B) has a weight average molecular weight of 5,000 to 200,000. [8]: A method for producing a masterbatch for chain extension of a polyester resin (A), comprising the steps of: Resin (B) having an epoxy group and having a flow starting temperature of 150° C. or less and pulverized polyester resin (C) having a flow starting temperature of 160° C. or more are mixed at a temperature lower than the flow starting temperature of polyester resin (C) and higher than the flow starting temperature of resin (B); A method for producing a masterbatch for chain extension, comprising dispersing pulverized polyester resin (C) in resin (B). [9]: A step of obtaining a masterbatch in which a pulverized polyester resin (C) having a flow temperature of 160°C or higher is dispersed in a resin (B) having an epoxy group and a flow temperature of 150°C or lower; A mixing step of adding at least the masterbatch to a polyester resin (A) to be modified and mixing the masterbatch; A method for producing a polyester resin molded article, comprising the steps of: (a) mixing the mixture; and (b) molding the mixture simultaneously with or after the mixing. Effect of the Invention

[0011] Effects of the Invention The present disclosure has the excellent effect of providing a method for producing a polyester resin molded product having excellent moldability, which can reduce deactivation even when a resin having a high flow initiation temperature, such as a PET resin, is used as a masterbatch component, and a masterbatch for chain extension of a polyester resin used in the production method and a production method thereof. [Brief description of the drawings]

[0012] [Figure 1] 1 is an optical microscope photograph of a cross-sectional view of a cut portion of the masterbatch of Example 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] An example of an embodiment to which the present disclosure is applied will be described below. However, the present disclosure is not limited to this embodiment, and other embodiments may fall within the scope of the present disclosure as long as they are consistent with the gist of the present disclosure. In addition, the numerical values ​​"A to B" specified in this specification refer to a range that satisfies numerical value A and a value greater than numerical value A, and numerical value B and a value smaller than numerical value B. The numerical values ​​specified in this specification are values ​​obtained by the method disclosed in the embodiment or example. In addition, the sheet in this specification is synonymous with film and plate-like. Unless otherwise noted, the various components appearing in this specification may be used independently alone or in combination of two or more types.

[0014] 1.Polyester resin molding The polyester resin molded body according to the present embodiment (hereinafter also referred to as the present molded body) is obtained by adding at least a master batch for chain extension (hereinafter also referred to as the present master batch) to the polyester resin (A) to be modified, and then melt-kneading and molding the same. The present master batch is mixed with the polyester resin (A) which is the main component at a specified ratio, and the polyester resin (A) is modified by chain extension. The present molded body is any molded product molded according to the application, and examples of the molded body include a film, a sheet, a plate, a net, a container such as a bottle, a cylindrical body, a thread-like body such as a filament, and a fiber such as a nonwoven fabric or a woven fabric. The surface of the molded body may be smooth or may have an uneven or complex shape. Each component will be described in detail below.

[0015] 1-1. Polyester resin (A) The polyester resin (A) is a resin that is the main component of the present molded body, and is a resin to be modified. The polyester resin (A) may be used alone or in a mixture of two or more types. The polyester resin (A) may be amorphous or crystalline. The polyester resin (A) may be linear or branched. In this specification, the main component refers to a component that accounts for 80 mass% or more of the non-volatile content of the molded body (100 mass%). The main component is preferably 90 mass% or more. Typical examples of the polyester resin (A) include polyester resins derived from diols and dicarboxylic acids, polyester resins derived from diols and hydroxycarboxylic acids, polyester resins derived from diols, dicarboxylic acids, and hydroxycarboxylic acids, or mixtures thereof.

[0016] Examples of the diol include aliphatic diols such as ethylene glycol, diethylene glycol, propanediol, butanediol, neopentyl glycol, and hexanediol, alicyclic diols such as 1,4-cyclohexanedimethanol, and aromatic diols. Examples of the dicarboxylic acid include aliphatic dicarboxylic acids such as adipic acid, sebacic acid, and azelaic acid; aromatic dicarboxylic acids such as terephthalic acid, naphthalenedicarboxylic acid, and isophthalic acid; alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid; and ester-forming derivatives thereof. Examples of the hydroxycarboxylic acid include lactic acid, hydroxybutyric acid, and polycaprolactone.

[0017] Specific examples of the polyester resin (A) include polyethylene terephthalate (PET), glycol-modified polyethylene terephthalate (PETG), polybutylene terephthalate (PBT), polylactic acid (PLA), polyglycolic acid (PGA), polyethylene adipate (PEA), polyhydroxyalkanoate (PHA), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), and polybutylene naphthalate (PBN). Polyethylene terephthalate (PET) is preferred because of its excellent transparency and ease of molding.

[0018] The polyester resin (A) may be a virgin polyester resin or a recycled polyester resin. By using this masterbatch, the polyester resin (A) can be chain-extended to increase its molecular weight, and the melt viscosity can be uniformly increased. Therefore, it is particularly suitable for recycled polyester resins with reduced molecular weights. It is also suitable for modifying polyester resins according to needs, regardless of the type of polyester resin. From the viewpoint of obtaining a polyester resin molded product of higher quality, it is preferable that the polyester resin (A) is a linear polyester resin.

[0019] The intrinsic viscosity (IV) of the polyester resin (A) is not limited, but is preferably 0.4 dL / g or more, more preferably 0.5 dL / g or more. There is no particular upper limit, but from the viewpoint of handling during molding in consideration of melt viscosity, 1.5 dL / g or less is preferable. In this specification, the intrinsic viscosity and melt viscosity refer to values ​​obtained from the examples described later.

[0020] 1-2. Chain extension masterbatch As described above, this master batch is a master batch for chain extension that promotes the chain extension of the polyester resin (A) and increases the molecular weight of the polyester resin (A). This master batch contains a pulverized polyester resin (C) (hereinafter referred to as polyester resin (C)) having a flow start temperature of 160°C or more, and a resin (B) (hereinafter also referred to as resin (B)) having an epoxy group and a flow start temperature of 150°C or less. Here, the "pulverized polyester resin (C) having a flow start temperature of 160°C or more" refers to a polyester resin pulverized into fine powder. In this master batch, at least the polyester resin (C) is dispersed in the resin (B). Each component can be used independently, either alone or in a mixture of two or more.

[0021] The flow starting temperature refers to the minimum temperature at which the melt viscosity of the polyester resin becomes 4800 Pa s or less under a pressure of 9.8 MPa in the evaluation of the melt viscosity using a flow tester, and is a value determined by the method in the Examples described later. Furthermore, the epoxy value, Mw, etc. in this specification refer to values ​​determined by the methods in the Examples described later.

[0022] By combining resin (B) with a flow starting temperature of 150°C or less with pulverized polyester resin (C) with a flow starting temperature of 160°C or more, kneading at a temperature equal to or higher than the flow starting temperature of resin (B) and lower than the flow starting temperature of polyester resin (C) becomes possible during the production of the masterbatch, and the deactivation of the epoxy groups of resin (B) at the masterbatch stage can be suppressed while the homogeneous dispersion of resin (B) and polyester resin (C) can be improved. Since the reaction between the epoxy groups of resin (B) and polyester resin (C) in the masterbatch can be suppressed, the reactivity with polyester resin (A) to be modified can be increased.

[0023] The masterbatch may be, for example, in the form of pellets or granules. In a cross section of a cut portion of a solid masterbatch, it is preferable that the resin (B) forms a continuous phase and the polyester resin (C) forms a dispersed phase. In other words, it is preferable that the cross section of the masterbatch forms a sea-island structure (resin (B) (sea phase), polyester resin (C) (island phase)).

[0024] When a 2 mm x 2 mm region of the cut cross section of the solid master batch was observed with an optical microscope (magnification 120 times), the dispersed phase of the polyester resin (C) was image-analyzed to determine the average particle size. If the average particle size of the pulverized polyester resin (C) is 10 to 1000 μm, the master batch distribution property and IV improvement effect are excellent. It is more preferably 20 to 500 μm, and even more preferably 50 to 300 μm.

[0025] The master batch may contain optional components other than the resin (B) and the polyester resin (C), such as resins other than those mentioned above, antioxidants, antistatic agents, surfactants, flame retardants, ultraviolet absorbers, and fillers.

[0026] 1-2-1.Resin (B) Resin (B) has an epoxy group and has a flow initiation temperature of 150° C. or less. By adding a masterbatch having resin (B) having an epoxy group to polyester resin (A) to be modified, the epoxy group reacts with the carboxyl group and / or hydroxyl group of polyester resin (A) to extend the chain.

[0027] The epoxy groups of the resin (B) are preferably 2 or more on average. By making the number 2 or more, it is possible to promote chain extension of the polyester resin (A) to be modified, increase the melt viscosity, and improve the moldability. From the viewpoint of enhancing the effect of improving the IV value, it is more preferable that the epoxy groups are 3 or more on average, and even more preferable that the epoxy groups are 4 or more on average. By having an average of 2 or more epoxy groups, it is possible to promote high molecular weight. In addition, by having an average of 4 or more epoxy groups, the number of reaction points with the polyester resin (A) increases, and therefore it is possible to effectively suppress a decrease in molecular weight. The upper limit of the epoxy groups is preferably 50 on average from the viewpoint of maintaining good moldability.

[0028] The epoxy groups in resin (B) react with the carboxyl groups and / or hydroxyl groups in polyester resin (C) used as a compounding component of the masterbatch and polyester resin (A) used as a compounding component of the polyester resin molded article, causing the polyester resin to undergo chain elongation and increase in molecular weight.

[0029] The epoxy value before the blending of the resin (B) is preferably 0.7 to 3.5 mmol / g. By making it 0.7 mmol / g or more, the spinnability becomes excellent. Also, by making it 3.5 mmol / g or less, the film smoothness becomes excellent. A more preferable range is 0.8 to 3.4 mmol / g, and an even more preferable range is 0.9 to 3.3 mmol / g.

[0030] From the viewpoints of IV improvement effect and moldability, the number of epoxy groups before blending with resin (B) is preferably 1 to 50.

[0031] Resin (B) may have an epoxy group and have a flow initiation temperature of 150° C. or less. By setting the flow initiation temperature to 150° C. or less, the reaction between polyester resin (C) and resin (B) at the masterbatch stage is suppressed, and the chain extension properties are improved when the masterbatch is added to polyester resin (A) to be modified.

[0032] Suitable examples of the resin (B) include acrylic resins and copolymers of monomers containing a (meth)acrylate monomer and a styrene monomer. The copolymer may be a random copolymer or a block copolymer, but a random copolymer is preferred. Specific examples include an acrylic acid ester-butadiene-styrene copolymer having an epoxy group, and a styrene-glycidyl acrylate copolymer. From the viewpoint of compatibility with the polyester resin (A), acrylic resins and styrene-glycidyl acrylate copolymers are more preferred. The various monomers can be used alone or in combination of two or more.

[0033] The (meth)acrylate monomer preferably contains glycidyl (meth)acrylate. Any monomer, such as alkyl (meth)acrylate having 1 to 10 carbon atoms, may be used as long as it contains these monomers. Suitable examples include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, and ethylhexyl (meth)acrylate. Among these, methyl (meth)acrylate is particularly suitable. The constituent unit derived from the monomer of glycidyl (meth)acrylate is preferably contained in an amount of 3 to 40 mass%, more preferably 5 to 35 mass%, and even more preferably 10 to 30 mass% in 100 mass% of the resin (B). By containing 3 to 40 mass%, the spinnability and the smoothness of the film can be more effectively improved.

[0034] Examples of the styrene-based monomer include styrene and styrene which may be substituted with one or more groups selected from the group consisting of an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, and a halogen. Examples include styrene derivatives such as styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, vinylxylene, ethylstyrene, dimethylstyrene, p-tert-butylstyrene, vinylnaphthalene, methoxystyrene, monobromostyrene, dibromostyrene, fluorostyrene, and tribromostyrene.

[0035] Suitable examples of the styrene-glycidyl acrylate copolymer include styrene / methyl methacrylate / glycidyl methacrylate copolymer, styrene / butyl methacrylate / glycidyl methacrylate copolymer, styrene / butadiene / glycidyl methacrylate copolymer, and styrene / isoprene / glycidyl methacrylate copolymer.

[0036] In the case of a styrene-glycidyl acrylate copolymer, the resin (B) is preferably one in which the structural unit derived from the styrene monomer is 60 to 75% by mass, the structural unit derived from the acrylic monomer is 25 to 40% by mass, and the epoxy value is within the above range. By making the structural unit derived from the styrene monomer fall within the above range, the compatibility with the polyester resin (C) can be improved. In addition, by making the structural unit derived from the acrylate monomer fall within the above range, the chain extension reaction of the polyester resin (C) can be more appropriately controlled. The content of glycidyl (meth)acrylate in the acrylic monomer is not particularly limited as long as it satisfies the above epoxy value, but for example, 1 to 100% by mass of glycidyl (meth)acrylate is used for 100% by mass of the structural unit derived from the acrylate monomer.

[0037] From the viewpoint of more effectively preventing yellowing, it is preferable that the resin (B) does not contain a carbodiimide group, and it is more preferable that the resin (B) is a resin that does not contain a nitrogen atom.

[0038] The upper limit of the flow starting temperature of the resin (B) is more preferably 140° C., and even more preferably 130° C. The lower limit of the flow starting temperature of the resin (B) is preferably 50° C., and even more preferably 55° C., from the viewpoint of the handleability of the master batch.

[0039] The weight average molecular weight (Mw) of the resin (B) is appropriately selected depending on the application of the present molded article. From the viewpoint of quickly dispersing the pulverized polyester resin (C) and providing excellent heat resistance, the Mw of the resin (B) is preferably 5,000 to 200,000, more preferably 5,500 to 180,000, and even more preferably 6,000 to 150,000.

[0040] The content of resin (B) in the master batch (non-volatile content) is sufficient as long as polyester resin (C) is dispersed in resin (B), and can be appropriately adjusted according to the needs of the target molded product and the properties of the polyester resin (A) to be modified. From the viewpoint of excellent chain extension and improving homogeneity to the polyester resin (A) to be modified while excellent processability during master batch production, the content of resin (B) in 100% by mass of master batch (non-volatile content) is preferably 40 to 95% by mass. It is more preferably 43 to 90% by mass, and even more preferably 45 to 85% by mass.

[0041] During the production of the masterbatch, resin (B) is kneaded at a temperature equal to or higher than the flow initiation temperature of resin (B) in order to homogeneously mix polyester resin (C) with resin (B). By using resin (B) whose flow initiation temperature is 150°C or lower, the kneading temperature during the production of the masterbatch can be set low, and the deactivation of epoxy groups in resin (B) due to reaction with polyester resin (C) during the production of the masterbatch can be significantly reduced.

[0042] In the case of melt-kneading resin (B) and polyester resin (C) in a masterbatch, there is a restriction that the difference in their flow initiation temperatures must be, for example, less than 150° C. On the other hand, according to the masterbatch of the present disclosure, the pulverized polyester resin (C) is dispersed in resin (B), and therefore there is an advantage that the flow initiation temperature of the polyester resin (C) does not need to be considered when producing the masterbatch. This allows for a significantly wider range of options for the polyester resin (C).

[0043] Conventionally, polyester resin products are molded by various molding methods including uniaxial molding and biaxial molding. However, for example, when polyester resin is biaxially molded, the polyester resin is easily hydrolyzed by shearing force. Even in molding of recycled polyester resin to which a chain extender has been added, the polyester resin is hydrolyzed by shearing simultaneously with the chain extension reaction, which makes it impossible to mold the product, or even if it can be molded, it is difficult to obtain a high-quality polyester resin molded product.

[0044] In order to obtain a master batch in which a chain extender and a polyester resin are melt-kneaded, it has been difficult to select a polyester resin (C) with a high flow start temperature in order to prevent the chain extension property of the master batch from being deactivated. On the other hand, according to the master batch of the present disclosure, a master batch in which a pulverized polyester resin (C) is dispersed in a resin (B) is used, so that the reaction between the resin (B) and the polyester resin (C) at the stage of the master batch is suppressed, and as a result, the deactivation of the chain extension property of the resin (B) can be significantly prevented. As a result, a polyester resin (C) suitable for the polyester resin (A) to be modified can be selected. For example, a PET resin with a high flow start temperature can be selected as the polyester resin (C), so that the problem of the ratio of the PET resin decreasing as the number of recycling times increases can be improved. As a result, the recycling rate of PET bottles can be increased. In other words, according to the master batch of the present disclosure, the options for the polyester resin (C) can be significantly increased, such as by selecting the same type of resin as the polyester resin (A). Since a polyester resin (C) with high compatibility with the polyester resin (A) can be selected, it is possible to achieve the chain extension of the polyester resin (A) homogeneously. Furthermore, since the resin (B) can be blended at a high concentration, it has the advantage of being able to enhance chain extension. As a result, regardless of the various molding methods, including uniaxial molding and biaxial molding, it is possible to obtain polyester resin molded products of excellent quality that are excellent in moldability and processability and that are suppressed from yellowing or clouding, and that can be processed by general-purpose processing methods.

[0045] The solubility parameter (SP value) of the resin (B) is preferably 9 to 11, and more preferably 9.5 to 10.5. By adjusting the SP value to 9 to 11, the compatibility with the polyester resin (C) can be improved. The SP value in the present disclosure is a value determined by the method described in the examples described later.

[0046] 1-2-2. Polyester resin (C) The polyester resin (C) is used in the form of pulverized particles. In the masterbatch, the pulverized polyester resin (C) is dispersed in the resin (B). The pulverized polyester resin (C) particles preferably have an average particle size of 10 to 1000 μm, more preferably 20 to 500 μm, and even more preferably 30 to 300 μm. By making the particle size 10 to 1000 μm, it is possible to suppress the reaction with the resin (B) and prevent gelation, while improving dispersibility (processability) during the production of the masterbatch.

[0047] The polyester resin (C) is a polyester resin having a flow-initiation temperature of 160° C. or more. A suitable polyester resin (C) is a thermoplastic resin composed of a saturated dicarboxylic acid and a saturated dihydric alcohol. As the saturated dicarboxylic acid, aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, naphthalene-1,4- or 2,6-dicarboxylic acid, diphenyl ether-4,4'-dicarboxylic acid, diphenyl dicarboxylic acids, diphenoxyethane diethane dicarboxylic acids, etc., aliphatic dicarboxylic acids such as adipic acid, sebacic acid, azelaic acid, decane-1,10-dicarboxylic acid, etc., alicyclic dicarboxylic acids such as cyclohexane dicarboxylic acid, etc., can be used.

[0048] In addition, examples of the saturated dihydric alcohol that can be used include aliphatic glycols such as ethylene glycol, propylene glycol, trimethylene glycol, tetramethylene glycol, diethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, hexamethylene glycol, dodecamethylene glycol, and neopentyl glycol; alicyclic glycols such as cyclohexanedimethanol; 2,2-bis(4'-β-hydroxyethoxyphenyl)propane; and other aromatic diols.

[0049] It is preferable to use a resin that contains 50 mol % or more of a structural unit derived from a linear glycol having 2 to 4 carbon atoms and / or a dehydration condensate of two molecules of such a linear glycol in 100 mol % of polyhydric alcohol, and also contains a structural unit derived from terephthalic acid or an ester-forming derivative thereof and / or isophthalic acid or an ester-forming derivative thereof. Ethylene glycol may be used at 100 mol %. By using 50 mol % or more of ethylene glycol, the compatibility when the polyester resin (A) to be modified and the master batch are mixed is improved, and the smoothness of the film surface is improved.

[0050] Preferred examples of the polyester resin (C) include PET, PET-G, I-PET, PBT and PCT.

[0051] The upper limit of the flow start temperature of the polyester resin (C) is not particularly limited. From the viewpoint of heat resistance and distributability of the masterbatch, it is preferable that the difference in flow start temperature between the polyester resin (A) to be modified and the polyester resin (C) of the masterbatch is within the range of ±60°C. The Mw of the polyester resin (C) is not particularly limited as long as the flow start temperature is within the above range.

[0052] The content of the polyester resin (C) in 100% by mass of the nonvolatile content of the present masterbatch can be, for example, 20 to 64.5% by mass. By setting it in this range, the processability during the production of the masterbatch is improved.

[0053] 2.Masterbatch manufacturing method An example of a method for producing the present masterbatch will be described below, but the method for producing the present masterbatch is not limited to this method.

[0054] The polyester resin (C) is pulverized in a pulverizer. The pulverization may be a known method such as dry pulverization or wet pulverization. Examples of wet pulverization include bead mill pulverization or ball mill pulverization. Examples of dry pulverization include airflow pulverization, cutter pulverization, or a combination thereof. Examples of airflow pulverization include pulverization using an airflow pulverizer such as a cyclone mill, a jet mill, or the like. In the airflow pulverization using a cyclone mill, an airflow is generated by the rotation of a rotor, and the resin introduced into the airflow is dry-pulverized to produce fine particles. In the airflow pulverization using a jet mill, an object is collided with a collision plate to dry-pulverize the resin to produce fine particles. Examples of cutter pulverization include pulverization using a crusher mill, a pin mill, a cutter mill, a hammer mill, an axial flow mill, or the like. It is preferable to separate coarse particles of 3 mm or more and fine particles of 300 nm or less using a classifier or the like to adjust the particle size distribution.

[0055] Next, the pulverized polyester resin (C) and resin (B) are weighed and charged into a masterbatch production device to disperse the polyester resin (C) in the resin (B). Examples of the masterbatch production device include a single-screw extruder, a twin-screw extruder, and a kneader-ruder.

[0056] In the mixing step, the resin (B) is heated at a temperature equal to or higher than the flow initiation temperature so as to obtain a uniform dispersion. The temperature is, for example, +0 to +80°C relative to the flow initiation temperature of the resin (B). The heating time is, for example, 30 to 300 seconds. The pressure is, for example, normal pressure. The charge rate of the resin (B) can be, for example, 40 to 95% by mass with respect to 100% by mass of the total of the polyester resin (C) and the resin (B).

[0057] The average temperature of the composition in the extruder may be, for example, 100 to 170° C., and the kneading time may be 30 seconds to 10 minutes. In order to suppress the reaction between the resin (B) and the polyester resin (C), the temperature is preferably lower than the flow initiation temperature of the polyester resin (C).

[0058] After kneading, the mixture is extruded from a masterbatch production device such as a die, cooled, and cut into pellets to obtain a masterbatch. In addition to pelletization, the mixture may be pulverized to obtain a powder.

[0059] 3. Manufacturing method of polyester resin molded body

[0060] The amount of the masterbatch for chain extension added to the polyester resin (A) is not particularly limited and can be appropriately designed according to the application. For example, 0.1 to 10 parts by mass of the masterbatch for chain extension can be added to 100 parts by mass of the polyester resin (C).

[0061] From the viewpoint of compatibility and distributability of the master batch with respect to the polyester resin (A), it is preferable that the flow start temperatures of the polyester resin (A) and the polyester resin (C) are close to each other. Specifically, the difference in flow start temperature between the two is preferably 70°C or less, more preferably 60°C or less. Also, from the viewpoint of compatibility, it is preferable that the structures of the polyester resin (A) and the polyester resin (C) are similar. Specifically, it is preferable that the structure derived from a common monomer is 30% or more, more preferably 50% or more. From the viewpoint of compatibility and distributability, and from the viewpoint of repeated recycling, it is preferable that the polyester resin (A) and the polyester resin (C) are the same type of resin. For example, when recycling PET resin as the polyester resin (A), it is preferable to use PET resin as the polyester resin (C).

[0062] A polyester resin molded article can be obtained from a mixture of only the polyester resin (A) and the masterbatch for chain extension. A polyester resin molded article can also be obtained from a mixture of the polyester resin (A) and the masterbatch for chain extension to which an optional component is added. As the optional additive, within the scope of the gist of the present disclosure, examples include resins other than the polyester resin (A) and the components of the masterbatch, antioxidants, antistatic agents, surfactants, flame retardants, ultraviolet absorbers, fillers, lubricants, catalysts, etc. The method for producing a polyester resin molded body includes a mixing step of adding at least a master batch for chain extension of the polyester resin to the polyester resin (A) to be modified and mixing the mixture, and a molding step of molding the mixture simultaneously with or after the mixing step. In the mixing step, the polyester resin (A) and the polyester resin (C) are mixed at a temperature 0 to 30°C higher than the flow start temperature of the resin having a higher flow start temperature, so that the master batch becomes homogeneous. By mixing the polyester resin (A) and the polyester resin (C) homogeneously at the melting temperature, the reaction between the polyester resin (A) and the resin (B), as well as between the polyester resin (A) and the resin (B), is promoted, and the melt viscosity increases. In addition, the resin (B) reacts with the polyester resin (A) and the polyester resin (C), and the melt viscosity increases. As a result, the polyester resin (A) to be modified becomes high molecular weight, and the melt viscosity of the melt-kneaded product increases.

[0063] The degree of increase in melt viscosity of the polyester resin (A) after adding and mixing the masterbatch is preferably 5 to 40%, more preferably 7 to 30%, and even more preferably 10 to 25% relative to the melt viscosity of the polyester resin (A) before processing. When the rate of increase in melt viscosity is within the above range, the physical properties of the polyester resin (A) can be improved without affecting moldability. In this specification, the melt viscosity of the polyester resin (A) is measured according to JIS K7199 at 280°C and a shear rate of 1.2×10 3 sec -1 The values ​​are those measured at .

[0064] The method includes a molding step of adding at least a masterbatch for chain extension of polyester resin (A) to polyester resin (A), mixing the mixture, and molding the mixture. Examples of the molding step include single-screw or twin-screw extrusion molding, injection molding, blow molding, etc. The molding method may involve producing pellets of polyester resin (A) and the masterbatch, and obtaining a molded product from the pellets, or directly producing a molded product from a mixture of polyester resin (A) and the masterbatch.

[0065] The kneading step includes a step of melt-kneading at a temperature that is equal to or higher than the flow initiation temperature of the polyester resin (A) and that promotes the reaction of the epoxy groups of the resin (B) of the masterbatch with the polyester resin (A) and the polyester resin (A) to increase the melt viscosity. EXAMPLES

[0066] Hereinafter, the present disclosure will be described in more detail based on examples, but the present disclosure is not limited to the examples. Unless otherwise specified, in the examples, "parts" and "%" represent "parts by mass" and "% by mass", respectively.

[0067] (A)Measurement method a-1. Weight average molecular weight (Mw) Mw was measured by gel permeation chromatography (GPC) and calculated as a molecular weight converted using polymethyl methacrylate as a standard substance. GPC was measured under the following conditions. Standard material: Polymethylmethacrylate Equipment: Waters LC system Column: Showa Denko HFIP-806M x 2 Mobile phase: Sodium trifluoroacetate 10mmol / L in hexafluoroisopropanol ·Flow rate: 1.0ml / min Detection: Differential Refractometer Column temperature: 30℃

[0068] a-2. Measurement of epoxy value (EV) of resin (B) In accordance with JIS K 7236, 1 g of resin (B) was stirred in 50 g of measurement solvent (methyl ethyl ketone (MEK): acetic acid: tetraethylammonium bromide = 100: 100: 14) for 30 minutes, and then an automatic titrator (product name GT-100, manufactured by Mitsubishi Chemical Corporation) was used to add 0.1 mol / L perchloric acid-acetic acid solution to measure the epoxy value [mmol / g] per 1 g of resin (B). The results are shown in Table 1.

[0069] a-3. Measurement of the epoxy value (EV) of resin (B) in the masterbatch In accordance with JIS K 7236, 1 g of the nonvolatile content of the master batch was stirred in 50 g of a measurement solvent (methyl ethyl ketone (MEK): acetic acid: tetraethylammonium bromide = 100: 100: 14) for 30 minutes, and then an automatic titrator (product name GT-100, manufactured by Mitsubishi Chemical Corporation) was used to add a 0.1 mol / L perchloric acid-acetic acid solution to measure the epoxy value [mmol / g] of resin (B) per 1 g of the nonvolatile content of the master batch. The results are shown in Table 2.

[0070] a-4. Measurement of flow start temperature Using a flow tester, the minimum temperature at which the melt viscosity of polyester resin (A) and resin (B) became 4800 Pa s or less was measured when they were passed through a capillary with a die hole diameter of φ1 mm and a die length of 1 mm under a pressure of 9.8 MPa. The flow starting temperature can be measured using a Shimadzu Corporation "CFT-EX series" or the like.

[0071] a-5. Intrinsic viscosity (IV) The solvent was phenol / 1,1,2,2-tetrachloroethane = 1 / 1, and the measurement was performed using an automatic viscosity measuring device "SS-600-L2" manufactured by Shibayama Scientific Instruments Manufacturing Co., Ltd. according to JIS K7367-5.

[0072] a-6.SP value The calculation was performed according to the method of Fedor. Specifically, the calculation was performed according to the following formula (1) in accordance with the description in Polym. Eng. Sci., vol. 14, p. 147 (1974). Equation (1): SP value = √(Ev / v) = √(ΣΔei / ΣΔvi) (Wherein, Ev: evaporation energy (cal / mol), v: molar volume (cm 3 / mol), Δei: evaporation energy of each atom or atomic group, Δvi: molar volume of each atom or atomic group)

[0073] a-7. Average particle size of polyester resin (C) The polyester resin (C) was placed on a preparation, and an area of ​​2 mm×2 mm was observed under an optical microscope to determine the average particle size of the polyester resin (C) in that area.

[0074] a-8. Average particle size of polyester resin (C) on cross section of masterbatch A 2 mm×2 mm area of ​​the cross section of each master batch was observed under an optical microscope, and the average particle size of the polyester resin (C) in that area was determined.

[0075] (B) Raw materials etc. The raw materials used in the examples are shown below. b-1. Polyester resin (A) The polyester resin (A) to be modified is shown in Table 1.

[0076] [Table 1]

[0077] b-2.Resin (B) The resin type used, such as resin (B), epoxy value, number of epoxy groups in one molecule, mass% of structural units derived from resin monomers, flow initiation temperature, and SP value are shown in Table 2. In the table, St represents a structural unit derived from a styrene-based monomer, Et represents a structural unit derived from an ethylene-based monomer, MMA represents a structural unit derived from a methyl methacrylate monomer, BMA represents a structural unit derived from a butyl methacrylate, and GMA represents a structural unit derived from a glycidyl (meth)acrylate monomer.

[0078] [Table 2]

[0079] <Resin B-5: Synthesis example 3> 44.9 parts of methyl ethyl ketone was charged, and the mixture was stirred for 30 minutes under nitrogen gas flow and heated. Separately, 25 parts of glycidyl methacrylate, 70 parts of styrene as an aromatic ring-containing monomer, 5 parts of methyl methacrylate, and 1.8 parts of 2-ethylhexyl thioglycolate as a thiol chain transfer agent were charged in a dropping funnel to prepare a dropping monomer solution. The dropping monomer solution and 18 parts of a 10% methyl ethyl ketone solution of 2,2'-azobis(isobutyronitrile) were dropped uniformly over 3 hours to initiate a polymerization reaction under reflux. After the dropping was completed, the reaction was continued for 5 hours while maintaining reflux. After that, sampling was performed to confirm that the conversion rate was 98% or more, and after cooling, the mixture was diluted with methyl ethyl ketone to produce a resin solution with a non-volatile content of 50%. Next, 500 parts of methanol was charged into a 1L beaker, and the resin solution was dropped over 1 hour while stirring at 1,000 rpm using a disperser. After that, the mixture was vacuum sucked using qualitative filter paper (manufactured by ADVANTEC, product name No. 2) in a 150mm diameter Buchner funnel, and the resulting white precipitate was filtered. The resulting white precipitate was dried in a vacuum dryer at 50°C for 12 hours to produce Resin B-5.

[0080] <Resin B-6: Synthesis example 4> Resin B-6 was obtained by the same production method as in Synthesis Example 3, except that 10 parts of glycidyl methacrylate, 85 parts of styrene as aromatic ring-containing monomers, and 5 parts of methyl methacrylate were used.

[0081] <Resin B-7: Synthesis example 5> Resin B-7 was obtained by the same production method as in Synthesis Example 3, except that 5 parts of glycidyl methacrylate, 90 parts of styrene as aromatic ring-containing monomers, and 5 parts of methyl methacrylate were used.

[0082] <Resin B-8: Synthesis example 6> Resin B-8 was obtained by the same production method as in Synthesis Example 3, except that 35 parts of glycidyl methacrylate, 60 parts of styrene as aromatic ring-containing monomers, and 5 parts of methyl methacrylate were used.

[0083] <Resin B-9: Synthesis Example 7> Resin B-9 was obtained by the same production method as in Synthesis Example 3, except that 15 parts of glycidyl methacrylate, 80 parts of styrene as the aromatic ring-containing monomer, and 5 parts of methyl methacrylate were used.

[0084] <Resin B-10: Synthesis Example 8> Resin B-10 was obtained in the same manner as in Synthesis Example 5, except that 5 parts of glycidyl methacrylate, 69 parts of styrene, and 26 parts of butyl methacrylate were used.

[0085] b-2. Polyester resin (C) The types of resins used, such as polyester resin (C), the mass percentage of structural units derived from the resin monomers, and the flow initiation temperature are shown.

[0086] [Table 3]

[0087] <Polyester resin (C-6): Synthesis example 1> 100 parts by mass of dimethyl terephthalate, 51.8 parts by mass of ethylene glycol, 12.1 parts by mass of cyclohexane dimethanol glycol, 0.06 parts by mass of magnesium acetate, and 0.03 parts by mass of antimony trioxide were melted at 150°C under a nitrogen atmosphere. Then, the mixture was heated to 230°C over 3 hours while stirring, and methanol was distilled off to terminate the transesterification reaction. After the transesterification reaction was completed, an ethylene glycol solution (PH 5.0) in which 0.019 parts by mass of phosphoric acid and 0.027 parts by mass of sodium dihydrogen phosphate dihydrate were dissolved in 0.5 parts by mass of ethylene glycol was added to the reaction product. Then, the polymerization reaction was carried out at a final temperature of 285°C and a vacuum degree of 0.1 Torr to obtain a polyester resin with an intrinsic viscosity of 0.54. Next, the obtained polyester resin was dried and crystallized at 160°C for 5 hours. Next, solid-phase polymerization was carried out at 220°C, a vacuum degree of 0.3 Torr, and 6 hours to obtain a polyester resin (C-6) with a flow start temperature of 228°C.

[0088] <Polyester resin (C'-8): Synthesis example 2> 100 parts by mass of dimethyl terephthalate, 55 parts by mass of ethylene glycol, 16 parts by mass of neopentyl glycol, and 0.04 parts by mass of tetrabutyl titanate were added and melted at 170°C in a nitrogen atmosphere. After that, the temperature was raised to 270°C, and the pressure in the system was slowly reduced to 500 Pa over 60 minutes. Then, a polycondensation reaction was carried out at 130 Pa or less for 55 minutes to obtain a polyester resin (C'-8). The flow initiation temperature of the polyester resin (C'-8) was 140°C.

[0089] (C) Manufacturing of master batches <Example 1: Masterbatch 1> 50 parts of polyester resin (C-1) and 50 parts of resin (B-1) were weighed out and fed into a Japan Steel Works, Ltd. co-rotating twin screw extruder "TEX-54α3" (L / D=52.5, output rate: 350 kg / hr, 3 vent holes) and mixed at 130°C. The mixture was then extruded from the vent holes while being suctioned and degassed under high vacuum, and cut with a pelletizer to obtain master batch 1. Figure 1 shows an optical microscope photograph of the cross section of the cut part of master batch 1. As shown in the figure, it was confirmed that the pulverized polyester resin (C) ((C) in the figure) was dispersed in the resin (B) ((B) in the figure).

[0090] <Examples 2 to 39 and Comparative Examples 1 to 3 (Production of Masterbatches 2 to 42)> Thermoplastic resin compositions were obtained in the same manner as masterbatch 1, except that the materials, blending amounts (parts by mass), and production temperatures were changed as shown in Tables 4 and 5. The amounts of raw materials used for each masterbatch, the mixing temperature for the masterbatch, the processability of the masterbatch, the average particle size of the resin (B) in the masterbatch, and the spinnability are shown in Tables 4 and 5.

[0091] [Table 4]

[0092] [Table 5]

[0093] (D) Masterbatch Evaluation d-1. Processability of master batches The processability of each masterbatch was evaluated according to the following criteria. +++: No strand breakage occurs when the masterbatch is produced continuously for 1 hour. ++: Strand breakage occurs 1 or more times and 5 or less times during continuous production of master batch for 1 hour. +: When the master batch is continuously produced for 1 hour, strand breakage occurs more than 5 times and less than 10 times. NG: None of the above evaluations apply, or master batches cannot be produced.

[0094] d-2. Spinnability (Masterbatch and Dilution Resin (Polyester Resin (A)) One part of the master batch and 100 parts of the recycled homo PET resin A-1 were weighed out, and 20 m of the material was spun at a processing temperature of 280°C using a spinning machine manufactured by Aiki Linotech Co., Ltd., and the number of times the yarn broke was evaluated. The evaluation criteria were as follows. ++++: No thread breakage occurs even once. +++: Thread breaks 1 to 2 times. ++: Thread breaks 3 to 5 times. +: The thread breaks 6 to 10 times. NG: The thread breaks 11 or more times.

[0095] (E) Production of polyester resin molded products [Reference example 1] Using a single-screw extruder (Dalmage screw) with a screw diameter of 40 mm manufactured by Nippon Placon Co., Ltd., 100 parts of polyester resin A-1 were extruded at a screw rotation speed of 90 rpm, a processing temperature of 280°C, and a discharge rate of 20 kg / h to produce recycled polyester resin pellets.

[0096] [Example 101] 100 parts of polyester resin A-1 and 1 part of master batch (1) were tumbled and extruded in a single-screw extruder (Dalmage screw) with a screw diameter of 40 mm manufactured by Nippon Placon Co., Ltd. at a screw rotation speed of 90 rpm, a processing temperature of 280°C, and a discharge rate of 20 kg / h to obtain recycled polyester resin pellets 101.

[0097] [Examples 102 to 154, Comparative Examples 101 to 104] Recycled polyester resin pellets and the like were obtained in the same manner as in Example 101, except that the materials and blending amounts (parts by mass) were changed to those shown in Tables 6 to 8, respectively.

[0098] (F) Evaluation of polyester resin molded products f-1. Intrinsic viscosity (IV) evaluation Each of the polyester resin pellets prepared was dissolved in a phenol / 1,1,2,2-tetrachloroethane = 1 / 1 solution, and the IV of the polyester resin pellets was measured according to JIS K7367-5 using an automatic viscosity measuring device "SS-600-L2" manufactured by Shibayama Scientific Instruments Manufacturing Co., Ltd. The IV of each Example was designated as IVX, and the IV of Reference Example 1 was designated as IV1, and the increase in intrinsic viscosity was evaluated according to the following evaluation criteria. +++:(IVX / IV1)×100-100≧15 ++:10≦(IVX / IV1)×100-100<15 +:5≦(IVX / IV1)×100-100<10 NG:(IVX / IV1)×100-100<5

[0099] f-2. Yellowness (YI value) The polyester resin pellets thus prepared were injection molded at 280°C using an injection molding machine (Toshiba Machine Co., Ltd., IS-100F type) to prepare rectangular parallelepiped test pieces measuring 30 mm in length, 40 mm in width, and 3 mm in height. Then, using a Kurabo Corporation image spectrophotometer AU Color COLOR7x, the L value (brightness), a value, and b value of the test pieces were measured using a D-65(10) standard light source, and the YI value was calculated according to JIS K7373 to measure the yellowness. The yellowing was evaluated according to the following criteria. +++:0≦YI<5 ++:5≦YI<10 +: 10≦YI<20 NG:20≦YI

[0100] f-3.White turbidity The haze of the test piece for evaluating the yellowness index (YI value) was measured using HazeGuard Plus (Gardner Co., Ltd.) in accordance with JIS K7136, and the white turbidity was evaluated according to the following criteria. +++: Haze ≦ 10% ++:10<Haze≦15% +: 15<Haze≦20% NG: Haze > 20%

[0101] f-4. Spinnability The spinnability was evaluated by producing 20 m of yarn at a processing temperature of 280° C. using a spinning machine manufactured by Aiki Linotech Co., Ltd., and evaluating the number of yarn breaks during the production. The evaluation criteria were as follows: ++++: No thread breakage occurs even once. +++: Thread breaks 1 to 2 times. ++: Thread breaks 3 to 5 times. +: The thread breaks 6 to 10 times. NG: The thread breaks 11 or more times.

[0102] f-5. Film smoothness The friction coefficient (μx) of a 100 μm thick film prepared by adding the master batch to polyester resin (A) was measured. The friction coefficient (μ1) of a 100 μm thick film prepared using polyester resin (A) without adding the master batch was used, and it was evaluated according to the following criteria. +++:μx / μ1≧90 ++:80≦μx / μ1<90 +:70≦μx / μ1<80 NG:μx / μ1<70

[0103] [Table 6]

[0104] [Table 7]

[0105] [Table 8]

[0106] In Comparative Example 101, in which the flow-start temperature of the polyester resin (C) is less than 160°C, poor results were confirmed in the IV value, yellowing, white turbidity, and spinnability. In addition, in the case of a resin other than a polyester resin, poor results were confirmed in the yellowing, white turbidity, spinnability, and film smoothness, as shown in Comparative Example 102, in which the flow-start temperature was 160°C or higher. In Comparative Example 103, in which the resin (B) does not have an epoxy group, poor results were confirmed in the yellowing. In Comparative Example 104, in which the resin B-1 was directly added, poor results were confirmed in the white turbidity and spinnability. On the other hand, in Examples 101 to 154, in which a masterbatch for chain extension was used in which pulverized polyester resin (C) having a flow starting temperature of 160°C or higher was dispersed in resin (B) having epoxy groups and a flow starting temperature of 150°C or lower for polyester resin (A), the IV value, yellowing, white turbidity, spinnability, and film smoothness were all confirmed to be excellent.

[0107] [Industrial Applicability] The manufacturing method of the present molded article has excellent moldability and can provide a high-quality molded article by a general-purpose processing method, and is therefore suitable for recycling used plastic products such as used PET bottles and fibers, or plastic products generated during production processes. In addition, because the molded article has excellent quality, it can be used as a high-performance resin material in a wide range of applications, such as fibers, films, sheets, foams, containers, electronic materials, building materials, automobile parts, and various industrial parts and products.

Claims

1. A masterbatch for chain extension of a polyester resin (A), comprising: A masterbatch for chain extension, comprising a resin (B) having an epoxy group and a flow starting temperature of 150°C or less, and a pulverized polyester resin (C) having a flow starting temperature of 160°C or more dispersed in the resin (B).

2. 2. The masterbatch for chain extension according to claim 1, wherein in a cross section of the masterbatch, the resin (B) forms a continuous phase and the polyester resin (C) forms a dispersed phase.

3. When a 2 mm x 2 mm area of ​​the cross section of the master batch was observed with an optical microscope, The masterbatch for chain extension according to claim 2, wherein the average particle size of the polyester resin (C) as determined by image analysis of the dispersed phase is 10 to 1000 μm.

4. The masterbatch for chain extension according to claim 1, wherein the content of the resin (B) in 100% by mass of the masterbatch is 40 to 95% by mass.

5. The polyester resin (C) is a resin containing structural units derived from terephthalic acid or an ester-forming derivative thereof and / or isophthalic acid or an ester-forming derivative thereof, and containing 50 mol % or more of structural units derived from a linear glycol having 2 to 4 carbon atoms and / or a dehydration condensate of two molecules thereof relative to 100 mol % of structural units derived from a polyhydric alcohol. The masterbatch for chain extension according to claim 1.

6. 2. The masterbatch for chain extension according to claim 1, wherein the epoxy value before blending with the resin (B) is 0.7 to 3.5 mmol / g.

7. 2. The masterbatch for chain extension according to claim 1, wherein the resin (B) has a weight average molecular weight of 5,000 to 200,000.

8. A method for producing a masterbatch for chain extension of a polyester resin (A), comprising the steps of: Resin (B) having an epoxy group and having a flow starting temperature of 150° C. or less and pulverized polyester resin (C) having a flow starting temperature of 160° C. or more are mixed at a temperature lower than the flow starting temperature of polyester resin (C) and higher than the flow starting temperature of resin (B); A method for producing a masterbatch for chain extension, comprising dispersing pulverized polyester resin (C) in resin (B).

9. obtaining a master batch in which pulverized polyester resin (C) having a flow starting temperature of 160° C. or more is dispersed in resin (B) having an epoxy group and having a flow starting temperature of 150° C. or less; A mixing step of adding at least the masterbatch to a polyester resin (A) to be modified and mixing the masterbatch; A method for producing a polyester resin molded article, comprising the steps of: (a) mixing the mixture; and (b) molding the mixture simultaneously with or after the mixing.

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