JP2024030285A - Thickener for polyester resin, master batch, molded body, and manufacturing method of these - Google Patents

Abstract

To provide a thickener for a polyester resin which enables production of a recycled polyester resin that suppresses odor, transparency and yellow discoloration and has good moldability.SOLUTION: A thickener for a polyester resin for a polymer including one or more monomer units selected from the group consisting of an epoxy group-containing monomer unit (X), an aromatic ring-containing monomer unit (Y) and other monomer unit (Z) (provided that an epoxy group and an aromatic ring are not contained) and having a weight average molecular weight of 6,000 or more, wherein the component having a weight average molecular weight of less than 1,000 in the thickener for the polyester resin is 0.001-3 mass%.SELECTED DRAWING: None

Description

The present invention is a modifier for polyester resin, and particularly relates to a thickener for polyester resin that can be used for recycling.

In recent years, countermeasures against plastic waste have become an important issue worldwide, and there is a need for the development of sustainable materials. For example, there is cascade recycling in which used PET bottles are crushed into flakes after being collected and used as a raw material to produce other products other than PET bottles, such as recycled fibers. There is also horizontal recycling (bottle-to-bottle) in which used PET bottles are returned to raw materials through chemical recycling or mechanical recycling to make PET bottles again. However, recycled polyester resins tend to have lower physical properties than virgin polyester resins. In particular, the molecular weight of the polyester resin decreases due to the thermal history during the recovery process and molding, resulting in a significant decrease in molding processability. As a result, recyclable resins are limited, high-quality molded products cannot be obtained, and applications are limited. Further, polyester resin is often molded using a single-screw extruder or a twin-screw extruder, but recycled polyester resin has the problem of being difficult to mold due to reasons such as a decrease in molecular weight.

Patent Document 1 describes a modifier for crystalline polyester resin containing an amorphous polyester resin, a reactive compound containing two or more glycidyl groups and/or isocyanate groups per molecule and having a weight average molecular weight of 200 to 500,000. is disclosed.

Japanese Patent Application Publication No. 2006-45477

However, since conventional thickeners for polyester resin are polymeric compounds with reactive groups such as epoxy groups, they contain unreacted substances during polymerization and low molecular weight components such as oligomers, making it difficult to produce recycled polyester resin. However, it is difficult to increase the molecular weight, resulting in insufficient moldability and processability, and there are also problems in that these low molecular weight components are mixed into the polyester resin, resulting in quality deterioration such as odor generation, yellowing, and decreased transparency.
In addition, when molded products using conventional polyester resin thickeners are mixed well using a twin-screw extruder, they generate a lot of heat and may suffer thermal deterioration (yellowing, etc.), while single-screw extrusion Although it is difficult to generate heat when using a machine, there was a problem in that it took time to mix, so it was necessary to use both depending on the composition, resulting in low versatility.

The present invention suppresses odor, decrease in transparency, and yellowing, improves molding processability of recycled polyester resin, and provides an additive for polyester resin that enables molding with a single-screw extruder and a twin-screw extruder. The purpose is to provide sticky agents.

The thickener for polyester resin of the present invention comprises an epoxy group-containing monomer unit (X), an aromatic ring-containing monomer unit (Y), and other monomer units (Z) (however, the epoxy group-containing monomer unit (Y) and other monomer units (Z) A thickener for a polyester resin of a polymer having a weight average molecular weight of 6,000 or more and containing one or more monomer units selected from the group consisting of
The content of the component having a weight average molecular weight of less than 1,000 in the thickener for polyester resin is 0.001 to 4.5% by mass.

According to the present invention, it is possible to suppress odor, decrease in transparency, and yellowing, improve molding processability of recycled polyester resin, and enable molding with a single-screw extruder and a twin-screw extruder. A thickener for polyester resin can be provided. Further, the present invention can provide a masterbatch for polyester resin and a molded article.

An example of an embodiment to which the present invention is applied will be described below. However, the present invention is not limited to the above embodiments and modifications. Furthermore, any modifications can be made within the range that can solve the problems of the present invention. Further, the numerical values "A to B" specified in this specification refer to a range that satisfies the numerical value A and a value larger than the numerical value A, and the numerical value B and a value smaller than the numerical value B. Note that the numerical values specified in this specification are values determined by the methods disclosed in the embodiments or examples. Further, the term "sheet" in this specification has the same meaning as "film" or "plate shape". Unless otherwise noted, the various components appearing in this specification may be used individually or in combination of two or more.
In this specification, a monomer is an unreacted compound, and a monomer unit refers to a state in which the monomer is polymerized to form a part of a polymer.

1. Thickener for polyester resin The thickener for polyester resin of the present invention contains an epoxy group-containing monomer unit (X), an aromatic ring-containing monomer unit (Y), and other monomer units (Z) (but A thickener for a polyester resin of a polymer having a weight average molecular weight of 6,000 or more and containing one or more monomer units selected from the group consisting of The content of components having a weight average molecular weight of less than 1,000 in the resin thickener is 0.001 to 4.5% by mass. The thickener for polyester resin of the present invention is preferably used for producing molded articles using recycled polyester resin.

The thickener for polyester resin of the present invention reacts with the polyester resin for dilution when creating a molded object, suppresses a decrease in molecular weight during melt-kneading, and suppresses a decrease in physical properties of a polyester resin molded object (also referred to as a molded object). ) Can be molded. The main reason for this is that the component with a weight average molecular weight of less than 1,000 contained in the thickener for polyester resin is 0.001 to 4.5% by mass. It is presumed that because the reaction proceeds appropriately between the two, it is possible to obtain a molded article with a molecular weight of just the right amount, which is not easily affected by odor, transparency, and yellowing, has good moldability, and has good moldability. As the polyester resin for dilution, it is preferable to use a general polyester resin or a recycled polyester resin.

<Epoxy group-containing monomer unit (X)>
The epoxy group of the epoxy group-containing monomer contributes to the reaction with the diluent polyester resin. Examples of the epoxy group-containing monomer include glycidyl methacrylate, 3,4-epoxycyclohexylmethyl methacrylate, and 4-hydroxybutyl acrylate glycidyl ether. Among these, glycidyl methacrylate is preferred.

<Aromatic ring-containing monomer unit (Y)>
The aromatic ring-containing monomer contributes to improving compatibility with aromatic ring-containing resins such as polyethylene terephthalate resin, for example. Examples of the aromatic ring-containing monomer include aromatic vinyl monomers and aromatic ring-containing (meth)acrylate monomers.
Aromatic vinyl monomers include, for example, styrene, α-methylstyrene, vinyl benzoate, methyl vinylbenzoate, vinyltoluene, dimethylstyrene, trimethylstyrene, ethylstyrene, isopropylstyrene, butylstyrene, p-tert-butylstyrene. , hydroxystyrene, methoxystyrene, butoxystyrene, acetoxystyrene, chlorostyrene, dichlorostyrene, bromostyrene, chloromethylstyrene, vinylnaphthalene, and the like.
Examples of aromatic ring-containing (meth)acrylate monomers include phenyl (meth)acrylate, benzyl (meth)acrylate, 3-phenoxy-2-hydroxypropyl (meth)acrylate, and β-phenoxyethoxy (meth)acrylate. Examples include ethyl, nonylphenoxypolyethylene glycol (meth)acrylate, tribromophenyl (meth)acrylate, and tribromophenyloxyethyl (meth)acrylate. Among these, styrene and benzyl methacrylate are preferred.

<Other monomers>
Other monomers are monomers other than epoxy group-containing monomers and aromatic ring-containing monomers, and include (meth)acrylate monomers and vinyl monomers that do not have epoxy groups or aromatic rings. Can be mentioned.

The (meth)acrylate monomer has an alkyl chain or a cycloalkyl chain.
Examples of (meth)acrylate monomers having an alkyl chain include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, and (meth)acrylate. n-butyl acid, isobutyl (meth)acrylate, t-butyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, t-octyl (meth)acrylate, meth) Acetoxyethyl acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, behenyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-(2-methoxyethoxy)ethyl (meth)acrylate, diethylene glycol monomethyl ether (meth)acrylate, diethylene glycol monoethyl ether (meth)acrylate, triacrylate (meth)acrylate Ethylene glycol monomethyl ether, (meth)acrylic acid triethylene glycol monoethyl ether, (meth)acrylic acid polyethylene glycol monomethyl ether, (meth)acrylic acid polyethylene glycol monoethyl ether, (meth)acrylic acid trifluoroethyl, (meth)acrylate Examples include octafluoropentyl acrylate and perfluorooctylethyl (meth)acrylate.
The (meth)acrylate monomer having a cycloalkyl chain has a monocyclic cycloalkyl chain or a polycyclic cycloalkyl chain.
Monocyclic cycloalkyl chain (meth)acrylate monomers include, for example, cyclohexyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, isobornyl (meth)acrylate, 2-methyl-2-adamantyl ( Examples include meth)acrylate, 2-ethyl-2-adamantyl(meth)acrylate, and the like.
Examples of the polycyclic cycloalkyl chain (meth)acrylate monomer include dicyclopentanyl (meth)acrylate and dicyclopentenyl (meth)acrylate.

Vinyl monomers include, for example, crotonate ester, vinyl ester, maleate diester, fumarate diester, itaconate diester, (meth)acrylamide, vinyl ether, (meth)acrylonitrile, acidic group-containing monomer, nitrogen-containing heterocycle Examples include monomers.

Examples of crotonate esters include butyl crotonate, hexyl crotonate, and the like.

Examples of the vinyl ester include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl methoxy acetate, and the like.

Examples of maleic acid diesters include dimethyl maleate, diethyl maleate, and dibutyl maleate.

Examples of fumaric acid diesters include dimethyl fumarate, diethyl fumarate, and dibutyl fumarate.

Examples of the itaconic acid diester include dimethyl itaconate, diethyl itaconate, and dibutyl itaconate.

(Meth)acrylamide is, for example, (meth)acrylamide, N-methyl (meth)acrylamide, N-ethyl (meth)acrylamide, N-propyl (meth)acrylamide, N-isopropyl (meth)acrylamide, Nn-butyl Acrylic (meth)amide, N-t-butyl (meth)acrylamide, N-cyclohexyl (meth)acrylamide, N-(2-methoxyethyl)(meth)acrylamide, N,N-dimethyl (meth)acrylamide, N,N -diethyl (meth)acrylamide, N-phenyl (meth)acrylamide, N-benzyl (meth)acrylamide, (meth)acryloylmorpholine, diacetone acrylamide and the like.

Examples of the vinyl ether include methyl vinyl ether, butyl vinyl ether, hexyl vinyl ether, and methoxyethyl vinyl ether.

Acidic group-containing monomers include, for example, unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, α-chloroacrylic acid, and cinnamic acid; maleic acid, maleic anhydride, fumaric acid, itaconic acid, and anhydride. Examples include unsaturated dicarboxylic acids such as itaconic acid, citraconic acid, citraconic anhydride, and mesaconic acid, or acid anhydrides thereof.

Examples of nitrogen-containing heterocyclic monomers include, for example, 4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine, 4-(meth)acryloylamino-2,2,6,6-tetra Methylpiperidine, pentamethylpiperidinyl methacrylate, pentamethylpiperidinyl acrylate, 4-(meth)acryloylamino-1,2,2,6,6-pentamethylpiperidine, 4-cyano-4-(meth)acryloylamino -2,2,6,6-tetramethylpiperidine, 4-crotonoyloxy-2,2,6,6-tetramethylpiperidine, 4-crotonoylamino-2,2,6,6-tetramethylpiperidine, etc. Can be mentioned.
Among other monomers, (meth)acrylate monomers having an alkyl chain of 1 to 8 carbon atoms and (meth)acrylate monomers having a cycloalkyl chain of 6 to 12 carbon atoms are preferred. (Meth)acrylate monomers having 1 to 8 alkyl chains are more preferred.

The thickener for polyester resin of the present invention contains an epoxy group-containing monomer unit (X), an aromatic ring-containing monomer unit (Y), and other monomer units (but does not contain an epoxy group or an aromatic ring). ) is a polymer containing one or more types of monomer units selected from the group consisting of:
The content of (X), (Y), and (Z) is such that (X) is 10 to 90% by mass, (Y) is 5 to 80% by mass, and (Z) is 1% by mass in all the monomer units. It is preferably 75% by mass.
More preferably (X) is 15 to 70% by mass, (Y) is 25 to 80% by mass, and (Z) is 1 to 50% by mass, and even more preferably (X) is 20 to 50% by mass, (Y) is 1 to 50% by mass. ) is 40 to 70% by mass, and (Z) is 1 to 35% by mass.
In the case of a polyester resin thickener containing (X) and (Y), it is preferable that (X) be 10 to 90% by mass and (Y) be 10 to 90% by mass. More preferably, (X) is 15 to 70% by mass, and (Y) is 30 to 85% by mass, and even more preferably (X) is 20 to 50% by mass, and (Y) is 50 to 80% by mass.
In the case of a polyester resin thickener containing (X) and (Z), it is preferable that (X) be 10 to 90% by mass and (Z) be 10 to 90% by mass. More preferably, (X) is 15 to 70% by mass, and (Z) is 30 to 85% by mass, and even more preferably (X) is 20 to 50% by mass, and (Z) is 50 to 80% by mass.
By having the monomer units in the thickener for polyester resin in the above ratio, it is possible to suppress odor, decrease in transparency, and yellowing, and to produce recycled polyester resin with good moldability. Acts as a thickener.

Examples of monomers used in the synthesis of thickeners for polyester resins include glycidyl methacrylate/styrene/methyl methacrylate copolymer, glycidyl methacrylate/styrene/butyl methacrylate copolymer, and 3,4-epoxycyclohexylmethyl methacrylate. /styrene/methyl methacrylate polymer, 4-hydroxybutyl acrylate glycidyl ether/styrene/methyl methacrylate polymer, and the like.

<Synthesis method>
The thickener for polyester resins of the present invention can be synthesized by known methods such as solution polymerization, emulsion polymerization, suspension polymerization, and bulk polymerization.
Examples of polymerization techniques include anionic polymerization, living anionic polymerization, cationic polymerization, living cationic polymerization, free radical polymerization, and living radical polymerization. Among these, free radical polymerization is preferred from the viewpoint of cost and productivity.

<Polymerization initiator>
It is preferable to use a polymerization initiator for polymerization. The polymerization initiator is preferably, for example, an azo compound or a peroxide. Examples of azo compounds include 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane-1-carbonitrile), 2, 2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethyl-4-methoxyvaleronitrile), dimethyl 2,2'-azobis(2-methylpropionate), 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis(2-hydroxymethylpropionitrile), or 2,2'-azobis[2-(2-imidazolin-2-yl) Propane], etc. Peroxides include, for example, benzoyl peroxide, t-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, di(2-ethoxyethyl)peroxydicarbonate. , t-butylperoxyneodecanoate, t-butylperoxy-2-ethylhexanoate, t-butylperoxybivalate, (3,5,5-trimethylhexanoyl)peroxide, dipropionyl peroxide, Or diacetyl peroxide etc. are mentioned.

The polymerization initiators can be used alone or in combination of two or more.

The amount of the polymerization initiator used is preferably 0.1 to 10 parts by weight, more preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the total amount of monomers. In addition, in the case of bulk polymerization, a polymerization initiator may not be used.

The polymerization temperature can be appropriately selected depending on the type of monomer and the desired molecular weight. The polymerization temperature is preferably about 40 to 150°C, more preferably 50 to 110°C. The reaction time is preferably about 3 to 30 hours, more preferably 5 to 20 hours.

<Thiol-based chain transfer agent>
In the polyester resin thickener of the present invention, a thiol-based chain transfer agent can be used to adjust the molecular weight during polymerization.

The thiol-based chain transfer agent preferably has one or more moieties selected from carboxyl groups, hydroxyl groups, and ester bonds in addition to thiol groups.
Examples of thiol-based chain transfer agents having a carboxyl group include α-mercaptopropionic acid, β-mercaptopropionic acid, 2,3-dimercaptopropionic acid, thioglycolic acid, thiolactic acid, o-mercaptobenzoic acid, and m-mercaptobenzoic acid. acid, thiomalic acid, o-thiocumaric acid, α-mercaptobutanoic acid, β-mercaptobutanoic acid, γ-mercaptobutanoic acid, 11-mercaptoundecanoic acid, and the like.
Examples of thiol-based chain transfer agents having a hydroxyl group include mercaptomethanol, 1-mercaptoethanol, 2-mercaptoethanol, 1-mercaptopropanol, 3-mercaptopropanol, 1-mercapto-2,3-propanediol, and 1-mercapto- 2-Butanol, 1-mercapto-2,3-butanediol, 1-mercapto-3,4-butanediol, 1-mercapto-3,4,4'-butanetriol, 2-mercapto-3-butanol, 2- Examples include mercapto-3,4-butanediol, 2-mercapto-3,4,4'-butanetriol, and thioglycerol.
Examples of thiol-based chain transfer agents having an ester bond include thioglycolic acid alkyl esters such as methyl thioglycolate, 2-ethylhexyl thioglycolate, octyl thioglycolate, and methoxybutyl thioglycolate, methyl mercaptopropionate, and mercaptopropion. Examples include mercaptopropionate alkyl esters such as octyl mercaptopropionate, methoxybutyl mercaptopropionate, and tridecyl mercaptopropionate.

Among these, thiol-based chain transfer agents having a primary thiol group are preferred because they have particularly high chain transfer effects and are easy to adjust the molecular weight. In particular, β-mercaptopropionic acid, thioglycerol, 2-ethylhexyl thioglycolate, octyl thioglycolate, methoxybutyl thioglycolate, octyl mercaptopropionate, and methoxybutyl mercaptopropionate are recommended for the balance between odor and ease of molecular weight adjustment. preferable.

Thiol chain transfer agents can be used alone or in combination of two or more.

The molecular weight of the thiol chain transfer agent is preferably 101 to 300, more preferably 150 to 250. By using a thiol-based chain transfer agent within this range, the volatility of the thiol-based chain transfer agent itself can be suppressed, and a chain transfer effect can be obtained by adding a small amount, so that molecular weight control becomes easy.

The content of the thiol-based chain transfer agent is preferably 0.01 to 5 parts by weight, preferably 0.05 to 4 parts by weight, and 0.1 to 3 parts by weight based on a total of 100 parts by weight of the monomers. More preferred. Note that the thiol-based chain transfer agent is not included in the total monomer units.

<Organic solvent>
Organic solvents can be used to synthesize the thickener for polyester resins of the present invention. Examples of organic solvents include ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, xylene, hexane, acetone, methyl ethyl ketone, cyclohexanone, diacetone alcohol, methanol, ethanol, isopropanol, propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether Examples include acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, and diethylene glycol monobutyl ether acetate.

The organic solvents can be used alone or in combination of two or more.

<Molecular weight>
The weight average molecular weight (Mw) of the polyester resin thickener of the present invention is preferably 6,000 to 100,000, more preferably 7,000 to 60,000, and even more preferably 8,000 to 20,000. When the weight average molecular weight is within the above range, the fluidity and compatibility during melt-kneading with the polyester resin can be improved, and the transparency and processability of the molded article can be improved.

The number average molecular weight (Mn) of the polyester resin thickener of the present invention is preferably 1,200 to 100,000, more preferably 1,700 to 50,000, and even more preferably 2,600 to 17,000. When the number average molecular weight is within the above range, the fluidity and compatibility during melt-kneading with the polyester resin can be improved, and the transparency and processability of the molded article can be improved.

Mw The molecular weight distribution (Mw/Mn) of the thickener for polyester resin of the present invention is preferably 1 to 5, more preferably 1.2 to 4, from the viewpoint of uniformizing the reaction with the polyester resin. -3 is more preferred.

The component having a weight average molecular weight of less than 1,000 in the thickener for polyester resin of the present invention is preferably 0.001 to 4.5%, more preferably 0.001 to 4%, and 0.001 to 3.5%. % is more preferred. When the component having a weight average molecular weight of less than 1,000 is within the above range, odor and decrease in transparency are suppressed, yellowing is suppressed, and moldability is improved.
In addition, the component having a weight average molecular weight of less than 500 in the thickener for polyester resin is preferably 0.001 to 2.5%, more preferably 0.001 to 2%, and even more preferably 0.001 to 1.5%. preferable. When the component having a weight average molecular weight of less than 500 is within the above range, odor, reduction in transparency, and yellowing are suppressed, and moldability is further improved.

Weight average molecular weight (Mw) and number average molecular weight (Mn) can be measured by gel permeation chromatography (GPC) equipped with an RI detector. HLC-8320GPC (manufactured by Tosoh Corporation) was used as the equipment, two separation columns were connected in series, and the packing material for both was "TSK-GEL SUPER HZM-N" connected in two series, and the oven temperature was 40℃. , using a THF solution as an eluent and measuring at a flow rate of 0.35 ml/min. The sample is dissolved in a solvent consisting of 1% by mass of the above eluent, and 20 microliters is injected. All molecular weights are polystyrene equivalent values.
From the measured molecular weight distribution list, the ratio of components with a molecular weight of less than 1,000 and components with a molecular weight of less than 500 can be calculated from the area ratio. The analysis range was from the rise of the peak to just before the solvent peak appeared.

In order to control the content of components having a weight average molecular weight of less than 1,000 to 0.001 to 4.5% in the thickener for polyester resin of the present invention, a purification step is carried out after the synthesis step of the thickener for polyester resin of the present invention. It is preferable to do so. Examples of purification methods include reprecipitation. The thickener for polyester resin obtained by polymerization is added dropwise to a poor solvent and purified by reprecipitation, followed by filtration and drying to remove residual monomers and low-molecular compounds to a desired extent.

The poor solvent used for reprecipitation is preferably one that has low solubility in the thickener for polyester resin, has low cost and purity, and is easy to remove the solvent from the thickener for polyester resin. Examples include water, alcoholic solvents such as methanol, ethanol, propanol, and isopropanol, and nonpolar solvents such as hexane and heptane. Among these, methanol is preferred from the viewpoint of cost and ease of solvent removal. Impurities can be efficiently removed by using the poor solvent in an amount of 1 to 20 times the weight of the thickener for polyester resin. Moreover, the poor solvent can be used alone or in combination of two or more kinds.

<Epoxy value>
The epoxy group in the thickener for polyester resin of the present invention reacts with the carboxy group and/or hydroxyl group in the polyester resin to extend the chain of the polyester resin and increase its molecular weight. As a result, the melt viscosity of the polyester resin increases and moldability can be improved.

The epoxy value of the thickener for polyester resins of the present invention is preferably 0.4 to 6.5 mmol/g, more preferably 0.7 to 5 mmol/g, and even more preferably 0.9 to 3.6 mmol/g. When the epoxy value is within this range, the reactivity between the polyester resin thickener of the present invention and the polyester resin is improved, and the melt viscosity is increased, so that moldability is improved. Note that the epoxy value means the equivalent amount of epoxy per gram of resin (mmol/g).

The epoxy value of the thickener for polyester resin can be determined as follows. In accordance with JIS K 7236, 0.5 mg of a thickener for polyester resin was added to 50 g of a measurement solution [methyl ethyl ketone (MEK):acetic acid:tetraethylammonium bromide = 1000:1000:140] after stirring for 30 minutes, using an automatic titration device (trade name). The epoxy value of a thickener for polyester resin can be measured by adding 0.1 mol/L perchloric acid-acetic acid solution using GT-100 (manufactured by Mitsubishi Chemical Corporation).

The flow initiation temperature of the polyester resin thickener of the present invention is preferably 240°C or lower, more preferably 50 to 200°C, and even more preferably 60 to 140°C. From the viewpoint of more homogeneous kneading, it is preferable that the difference in flow start temperature between the polyester resin thickener of the present invention and the polyester resin (A) is less than 150°C. It is preferable that the difference in flow start temperature between the thickener for polyester resin of the present invention and the polyester resin for dilution is 200° C. or less. Note that the flow start temperature refers to the minimum temperature at which the melt viscosity of the resin becomes 4800 Pa·s or less under a pressure of 9.8 MPa in evaluating the melt viscosity using a flow tester.
The flow start temperature can be measured using "CFT-EX series" manufactured by Shimadzu Corporation. By using a flow tester to measure the minimum temperature at which the melt viscosity of the resin to be measured becomes 4800 Pa・s or less when 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. Seek.

2. Thickening masterbatch for polyester resin The thickening masterbatch for polyester resin of the present invention contains a reaction product of a thickener for polyester resin and a polyester resin (A). The thickening masterbatch for polyester resin is prepared by melt-kneading a thickener for polyester resin and polyester resin (A). At that time, the polyester resin thickener and a part of the polyester resin (A) react to obtain a reaction product (hereinafter referred to as chain-extended polyester resin (C)).

The content of the thickener for polyester resin in 100% by mass of non-volatile content of the thickening masterbatch for polyester resin of the present invention is preferably 35 to 60% by mass. By setting it within the above range, for example, chain extension of the recycled polyester resin is promoted, and by increasing the molecular weight, molding with a single-screw extruder and a twin-screw extruder becomes possible. This is because the reaction between the thickener for polyester resin and recycled polyester resin is efficient because the component with a weight average molecular weight of less than 1,000 in the thickener for polyester resin is 0.001 to 4.5% by mass. I am guessing that this is to move on. A more preferred range is 38 to 55% by weight, and an even more preferred range is 40 to 50% by weight. Since the uniform dispersibility of the masterbatch can be improved and the molecular weight of the recycled polyester resin can be uniformly increased, the MFR of the masterbatch is more preferably 10 to 300 g/min, and more preferably 20 to 100 g/min. preferable. The MFR in the present invention is a value measured according to JIS K-7210-1:2014.

<Polyester resin (A)>
The polyester resin (A) is preferably a polyester resin having a flow start temperature of 180°C or higher and 240°C or lower. The polyester resin (A) is preferably a resin obtained by synthesizing a saturated dicarboxylic acid and a saturated dihydric alcohol, for example. Saturated dicarboxylic acids include, for example, terephthalic acid, isophthalic acid, phthalic acid, naphthalene-1,4- or 2,6-dicarboxylic acid, diphenyl ether-4,4'-dicarboxylic acid, diphenyldicarboxylic acids, diphenoxyethane diethanedicarboxylic acid, etc. Examples include aromatic dicarboxylic acids such as acids, aliphatic dicarboxylic acids such as adipic acid, sebacic acid, azelaic acid, decane-1,10-dicarboxylic acid, and alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid.
Saturated dihydric alcohols include, for example, aliphatic alcohols such as ethylene glycol, propylene glycol, trimethylene glycol, tetramethylene glycol, diethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, hexamethylene glycol, dodecamethylene glycol, neopentyl glycol, etc. Examples include glycols, alicyclic glycols such as cyclohexanedimethanol, 2,2-bis(4'-β-hydroxyethoxyphenyl)propane, and other aromatic diols. Among these, preferred are glycol-modified polyethylene terephthalate (PET-G), isophthalic acid copolymerized polyethylene terephthalate (I-PET), polybutylene terephthalate (PBT) and polycyclohexylene dimethylene terephthalate (PCT).

A more preferable range of the flow initiation temperature of the polyester resin (A) is 220 to 240°C. The weight average molecular weight of the polyester resin (A) may be such that the flow start temperature is within the above range.

From the viewpoint of improving uniform dispersibility of the masterbatch, the melt flow rate (МFR) of the polyester resin (A) is preferably 5 to 100 g/min, more preferably 10 to 50 g/min. From the viewpoint of compatibility, when the recycled polyester resin is an aromatic polyester resin, the polyester resin (A) is preferably an aromatic polyester. When the recycled polyester resin is an aliphatic polyester resin, the polyester resin (A) is preferably an aliphatic polyester resin.

The content of the polyester resin (A) is preferably 20 to 64.5% by mass based on 100% by mass of the nonvolatile content of the masterbatch. By setting it as this range, the processability at the time of masterbatch production improves more.

<Chain extended polyester resin (C)>
The chain-extended polyester resin (C) is a reaction product in which the polyester resin (A) and a polyester resin thickener partially reacted during melt-kneading. When producing a thickening masterbatch for polyester resin, the content of chain-extended polyester resin (C) can be adjusted by adjusting the kneading conditions of polyester resin (A) and thickener for polyester resin. . In addition, when producing a thickening masterbatch for polyester resin, all or part of a chain-extended polyester resin (C) which has been reacted with a polyester resin (A) and a thickener for polyester resin in advance may be added to the master batch. The content of the chain-extended polyester resin (C) relative to 100% by mass of the nonvolatile content of the batch may be adjusted.

The content of the chain-extended polyester resin (C) in 100% by mass of nonvolatile content of the thickening masterbatch for polyester resin is preferably 1.5 to 20% by mass. A more preferred range is 2 to 15% by weight, and an even more preferred range is 2.5 to 10% by weight. By being within the above range, the compatibility between the thickening masterbatch for polyester resin and the recycled polyester resin is improved, a decrease in transparency and yellowing can be suppressed, and moldability is improved. The reason for this is presumed to be that the chain-extended polyester resin (C) has the function of a compatibilizer. Therefore, a molded article better than a masterbatch obtained by simply kneading the polyester resin (A) and a polyester resin thickener can be obtained.

The contents of the polyester resin (A), the thickener for polyester resin, and the chain-extended polyester resin (C) in 100% by mass of the nonvolatile content of the masterbatch can be calculated by the following GPC measurement. In addition, the number average molecular weight (Mn) and weight average molecular weight (Mw) were determined by GPC measurement as a converted molecular weight using polymethyl methacrylate as a standard substance.
First, the molecular weight distribution (Mw/Mn) of the polyester resin (A) and resin (B) is determined by GPC measurement. Subsequently, the molecular weight distribution of the masterbatch is measured by GPC, and the area of the obtained differential molecular weight distribution curve is taken as 100%. Then, when this differential molecular weight distribution curve is taken as 100% by mass (total mass), the ratio to the area of the polyester resin (A), the thickener for polyester resin, and the chain-extended polyester resin (C) in the master batch. (abundance ratio) can be determined as each mass %. Note that the peak observed on the higher molecular weight side than the polyester resin (A) and the polyester resin thickener was defined as the peak of the chain-extended polyester resin (C). GPC was measured under the following conditions.
・Standard substance: Polymethyl methacrylate ・Apparatus: LC system manufactured by Waters Co., Ltd. ・Column: HFIP-806M x 2, manufactured by Showa Denko K.K. ・Mobile phase: Sodium trifluoroacetate 10 mmol/L hexafluoroisopropanol solution ・Flow rate: 1. 0ml/min
・Detection: Differential refractometer ・Column temperature: 30℃

<Epoxy value>
The epoxy value of the thickener for polyester resin per gram of nonvolatile content of the thickening masterbatch for polyester resin of the present invention is preferably 0.4 to 3.6 mmol/g. By setting it as this range, it is excellent in the reactivity with recycled polyester resin, and the molecular weight fall of recycled polyester resin can be suppressed effectively. Note that the epoxy value is preferably 0.5 to 2.8 mmol/g, more preferably 0.7 to 2.5.

The epoxy value of the thickener for polyester resin in the thickening masterbatch for polyester resin can be determined as follows.
In accordance with JIS K 7236, 0.5 mg of a thickening masterbatch for polyester resin was added to 50 g of a measurement solution [methyl ethyl ketone (MEK): acetic acid: tetraethylammonium bromide = 1000:1000:140] after stirring for 30 minutes, and the mixture was added to an automatic titration device (product Measure the epoxy value of the thickener for polyester resin per 1 g of thickening masterbatch for polyester resin by adding 0.1 mol/L perchloric acid-acetic acid solution can. In addition, the thickening masterbatch for polyester resin contains chain-extended polyester resin (C), which is a reaction product of polyester resin (A) and a thickener for polyester resin, and there may be cases where epoxy groups remain. However, since the chain-extended polyester resin (C) does not dissolve in MEK, the measured value is the epoxy value of the thickener for polyester resin.

The thickening masterbatch for polyester resin of the present invention may contain optional components other than the polyester resin (A), the thickener for polyester resin, and the chain-extended polyester resin (C). For example, resins other than those mentioned above, antioxidants, antistatic agents, surfactants, flame retardants, ultraviolet absorbers, fillers, etc. can be contained.

<Production method of thickening masterbatch for polyester resin>
An example of the method for producing the thickening masterbatch for polyester resin of the present invention will be described below, but the method for producing the masterbatch is not limited to this method.

The polyester resin (A) and the polyester resin thickener are weighed out, put into a masterbatch manufacturing device, and melt-kneaded to cause a portion of the polyester resin (A) and the polyester resin thickener to react.
In the kneading step, heating is performed to obtain a uniform kneaded product. At this time, part of the polyester resin (A) and part of the thickener for polyester resin react to obtain a chain-extended polyester resin (C). By adjusting conditions such as kneading temperature, mixture ratio, kneading time, etc., the content of each of the thickener for polyester resin and chain-extended polyester resin (C) in the masterbatch, and the epoxy value of the thickener for polyester resin can be adjusted. can be adjusted. It is preferable to knead at a temperature of, for example, +0 to 20° C. relative to the flow start temperature of the higher of the polyester resin (A) and the polyester resin thickener. The heating time is preferably, for example, 30 seconds to 300 seconds. The pressure may be normal pressure. The loading ratio of the thickener for polyester resin is preferably 40 to 65% by mass, for example, based on the total of 100% by mass of the polyester resin (A) and the thickener for polyester resin.

Preferably, the average temperature of the composition in the extruder is 180 to 280°C, and the kneading time is 30 seconds to 10 minutes. By adding a part of the chain-extended polyester resin (C) at the mixture stage, the content of the polyester resin thickener and chain-extended polyester resin (C) in the masterbatch, as well as the polyester resin thickener The epoxy value may be adjusted.

After kneading, it can be extruded from a masterbatch manufacturing device such as a die, cooled with water, and then cut to obtain a pelletized masterbatch. In addition to pelletizing, the mixture may be pulverized to form a powder.

3. Molded object The molded object of the present invention is formed by molding a polyester resin for dilution and a thickening masterbatch for polyester resin. Note that the molding is preferably performed after melt-kneading.

The molded article of the present invention can effectively suppress yellowing of a polyester resin molded article. The main reason for this is that the component with a weight average molecular weight of less than 1,000 contained in the thickener for polyester resin is 0.001 to 3% by mass, which improves molding processability and improves melt-kneading properties during polyester resin molding. It is presumed that impurities that cause yellowing that are generated during the process can be suppressed. Therefore, a high-quality molded article with good transparency and little yellowing and odor can be obtained.

According to the present molded product, a decrease in transparency of the polyester resin molded product can be suppressed. The main reason for this is thought to be that the component having a weight average molecular weight of less than 1,000 contained in the polyester resin thickener is 0.001 to 3% by mass. Thereby, inhibition of compatibility between the polyester resin and the thickener for polyester resin can be suppressed. It is also assumed that there is a synergistic effect due to the chain-extended polyester resin (C), which is a reaction product of the polyester resin (A) and the thickener for polyester resin. In addition, the chain-extended polyester resin (C) in the masterbatch increases the compatibility between the masterbatch for polyester resin and the polyester resin for dilution, increases uniformity during melt-kneading, and effectively suppresses deterioration in transparency. I guess it can be done.

According to the present molded product, it is possible to effectively suppress a decrease in the molecular weight of the polyester resin molded product. The main reason for this is thought to be that the component having a weight average molecular weight of less than 1,000 contained in the polyester resin thickener is 0.001 to 3% by mass. This makes it difficult for the reaction between the polyester resin and the thickener for polyester resin to be inhibited. In addition, the chain-extended polyester resin (C) in the masterbatch significantly improves the compatibility between the masterbatch for polyester resin and the polyester resin for dilution, and the proportion of the thickener for polyester resin that reacts with the polyester resin for dilution. is increased, and a local chain extension reaction does not occur, making it possible to effectively suppress a decrease in molecular weight.

In the present specification, a highly versatile molded product can be provided that can be applied to either uniaxial molding or biaxial molding to obtain an excellent molded product. The main reason for this is thought to be that the component having a weight average molecular weight of less than 1,000 contained in the polyester resin thickener is 0.001 to 3% by mass. As a result, the reaction between the polyester resin and the thickener for polyester resin is not inhibited, and a decrease in the molecular weight of the polyester resin can be suppressed even in biaxial molding where hydrolysis of the polyester resin tends to occur.

<Polyester resin for dilution>
The polyester resin for dilution is a resin that is the main component of the molded article and is a resin that is to be modified. The polyester resin for dilution may be amorphous or crystalline. Moreover, the polyester resin for dilution may be linear or branched. The polyester resin for dilution is preferably a recycled polyester resin.

As used herein, the term "main component" refers to the component with the highest content in the composition. The diluting polyester resin is typically a polyester resin derived from a diol and a dicarboxylic acid, a polyester resin derived from a diol and a hydroxycarboxylic acid, a polyester resin derived from a diol, a dicarboxylic acid and a hydroxycarboxylic acid, or a mixture thereof. can be exemplified.

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.
The dicarboxylic acids include, for example, fatty acid dicarboxylic acids such as adipic acid, sebacic acid, and azelaic acid; aromatic dicarboxylic acids such as terephthalic acid, naphthalene dicarboxylic acid, and isophthalic acid; and alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid. Examples include acids; or ester-forming derivatives thereof. Examples of the hydroxycarboxylic acid include lactic acid, hydroxybutyric acid, and polycaprolactone.

Examples of the polyester resin for dilution include polyethylene terephthalate (PET), glycol-modified polyethylene terephthalate (PET-G), polybutylene terephthalate (PBT), polylactic acid (PLA), polyglycolic acid (PGA), polyethylene adipate (PEA), Examples include polyhydroxyalkanoate (PHA), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), and polybutylene naphthalate (PBN). Polyethylene terephthalate (PET) is preferred because it has excellent transparency and is easy to mold.

The polyester resin for dilution may be a virgin polyester resin or a recycled polyester resin. According to the present invention, by using a polyester resin masterbatch, the diluent polyester resin can be chain-extended to have a high molecular weight, and further, the melt viscosity can be uniformly increased. Therefore, it is particularly suitable for recycled polyester resins with reduced molecular weights. From the viewpoint of obtaining a polyester resin molded article of higher quality, it is preferable that the polyester resin for dilution is a linear polyester resin.

Although the intrinsic viscosity (IV) of the polyester resin for dilution is not limited, it is preferably 0.4 dl/g or more, more preferably 0.5 dl/g or more. The upper limit value is preferably 1.5 dl/g or less from the viewpoint of handleability during molding considering melt viscosity. Note that the intrinsic viscosity and melt viscosity in this specification refer to values determined by Examples described later.

The amount of the thickening masterbatch for polyester resin added to the polyester resin for dilution is preferably 0.1 to 10 parts by mass, more preferably 0.2 to 8 parts by mass, per 100 parts by mass of the polyester resin for dilution.

<Method for manufacturing molded body>
The manufacturing method of the molded object consists of a step of directly adding and mixing a thickener for polyester resin to a polyester resin for dilution, or a mixing step of adding and mixing a masterbatch for polyester resin, and a mixing step of adding and mixing a masterbatch for polyester resin to the polyester resin for dilution, and a step of mixing at the same time as this mixing step or mixing. It includes a molding step of molding after the step. In the mixing step, the masterbatch is mixed at a temperature 0 to 30° C. higher than the flow start temperature of the diluent polyester resin so that the masterbatch becomes homogeneous. By homogeneously mixing at a melting temperature, the reactions between the diluting polyester resin and the polyester resin thickener, as well as between the polyester resin (A) and the polyester resin thickener, are promoted, and the melt viscosity increases. When the chain-extended polyester resin (C) has an epoxy group, the diluent polyester resin and the chain-extended polyester resin (C), as well as the polyester resin (A) and the chain-extended polyester resin (C), also react to increase the molecular weight. do. Along with these, the melt viscosity of the melt-kneaded product increases.

Examples of the molding process include single-screw extrusion molding, twin-screw extrusion molding, injection molding, and blow molding.

It is preferable that the kneading step is performed at a temperature equal to or higher than the flow start temperature of the polyester resin for dilution. The kneading temperature is, for example, preferably 250 to 300°C, more preferably 250 to 280°C.

Examples of the shape of the molded body include a film, a sheet, a plate, a net, a container, a cylinder, a bottle, a thread such as a filament, and a fiber such as a nonwoven fabric and a woven fabric. The surface of the molded body may be smooth or may have irregularities or a complicated shape.

Applications of molded bodies include, for example, beverage bottles, clothing, packaging materials, foams, films, sheets, containers, electronic materials, building materials, automobile parts, and various industrial parts and products.

Hereinafter, the present invention will be explained in more detail based on Examples, but the present invention is not limited to the Examples. Unless otherwise specified, in the examples, "parts" represent "parts by mass" and "%" represent "% by mass."

<Manufacture of thickener for polyester resin>
(Example 1)
A four-neck separable flask equipped with a thermometer, stirrer, dropping funnel, and condenser was charged with 44.9 parts of methyl ethyl ketone, stirred for 30 minutes under a nitrogen atmosphere, and heated.
Separately, in a dropping funnel, add 30 parts of glycidyl methacrylate as an epoxy group-containing (meth)acrylate monomer, 65 parts of styrene as an aromatic ring-containing monomer, 5 parts of methyl methacrylate as other monomers, and thiol chain. 1.8 parts of 2-ethylhexyl thioglycolate was added as a transfer agent to form a dropwise monomer liquid.
The monomer solution and 18 parts of a 10% solution of 2,2'-azobis(isobutyronitrile) in methyl ethyl ketone were uniformly added dropwise over a period of 3 hours to initiate a polymerization reaction under reflux.
After the dropwise addition was completed, reflux was maintained and the reaction was continued for 5 hours. Thereafter, 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 nonvolatile content of 50%.
Next, 500 parts of methanol was placed in a 1 L beaker, and the mixture was stirred at 1,000 rpm using a disper, and the resin solution was added dropwise over 1 hour. Thereafter, vacuum suction was performed using a Buchner funnel with a diameter of 150 mm using qualitative filter paper (manufactured by ADVANTEC, product name No. 2), and the white precipitate formed was filtered. The obtained white precipitate was dried in a vacuum dryer at 50° C. for 12 hours to produce a thickener for polyester resin (P-1).

(Examples 2 to 15)
Examples 2 to 15 are thickeners for polyester resins in the same manner as in Example 1, except that the types and amounts of monomers, polymerization initiators, and chain transfer agents used were changed as shown in Table 1 below. Agents (P-2) to (P-15) were obtained.

(Comparative example 1)
As shown in Table 1 below, in Comparative Example 1, in addition to changing the types and amounts of monomers, polymerization initiators, and chain transfer agents used, a solution was taken out without reprecipitation process, and a fixed amount was collected using an evaporator. After removing the solvent, the resin was dried in a vacuum dryer at 50° C. for 12 hours to produce a resin (P-16) of Comparative Example 1.

The abbreviations in Table 1 are as follows.
AIBN: 2,2'-azobis(isobutyronitrile)
OTG: 2-ethylhexyl thioglycolate

The raw materials used in the examples are shown below.
<Polyester resin (A)>
A-1: GN001 (manufactured by Eastman Chemical Co., glycol-modified polyethylene terephthalate PET-G, flow start temperature 200°C)
A-2: PIFG30 (manufactured by Bell Polyester Products, isophthalic acid copolymerized polyethylene terephthalate I-PET, flow start temperature 224°C)

<Manufacture of masterbatch for polyester resin>
(Example 16)
50 parts of polyester resin (A-1) and 50 parts of polyester resin thickener (P-1) were added to a co-rotating twin-screw extruder "TEX-54α3" (L/D= 52.5, discharge rate: 350 kg/hr, 3 vent holes), extruded at 220°C while suctioning and degassing under high vacuum from the vent hole, and cutting with a pelletizer to create a thickening masterbatch for polyester resin. (M-1) was obtained.

(Examples 17 to 33), (Comparative Example 2)
Thickening masterbatches for polyester resin (M-2) to (M-19) were obtained in the same manner as thickening masterbatch for polyester resin (M-1) using materials and production temperatures having the compositions shown in Table 2.

[Odor evaluation]
10 g of the produced masterbatch for polyester resin was weighed out, placed in an aluminum vapor deposition bag, sealed, and allowed to stand at 40° C. for 24 hours. Afterwards, the odor was confirmed by five monitors.
◎: Almost no odor is observed (all monitors do not perceive any odor). Good.
○: Slight odor is observed. (1 to 3 monitors sense the odor). Practical.
×: Odor is clearly observed (4 or more monitors sense odor). Not practical.

<Manufacture and evaluation of molding pellets and molded bodies>
(Reference example 1)
100 parts of recycled homo PET resin (IV: 0.60 dl/g) was processed using a single screw extruder (Dulmage screw) manufactured by Nippon Placon Co., Ltd. with a screw diameter of 40 mm at a screw rotation speed of 90 rpm, a processing temperature of 270°C, and a discharge rate of 20 kg/h. Extrusion processing was performed to produce recycled polyester resin pellets.
(Reference example 2)
100 parts of recycled homo PET resin (IV: 0.60 dl/g) was processed using a twin screw extruder manufactured by Japan Steel Works, Ltd. with a screw diameter of 30 mm (L/D = 53.5) at a screw rotation speed of 200 rpm and a processing temperature of 270°C. Extrusion processing was performed to produce recycled polyester resin pellets.

(Example 34)
100 parts of recycled homo-PET resin (IV: 0.60 dl/g) and 1 part of thickening masterbatch for polyester resin (M-1) were tumbled (mixing the pellets together) and made into Nippon Placon Co., Ltd. Extrusion processing was performed using a single screw extruder (Dulmage screw) with a screw diameter of 40 mm at a screw rotation speed of 90 rpm, a processing temperature of 270° C., and a discharge rate of 20 kg/h to produce pellets for molding.

(Examples 35 to 51), (Comparative Example 3)
Molding pellets were produced in the same manner as in Example 34, except that the materials and blending amounts (parts by mass) shown in Table 3 were changed.

[Evaluation of intrinsic viscosity (IV)]
Each of the prepared pellets was dissolved in a solution of phenol/1,1,2,2-tetrachloroethane = 1/1, and measured using JIS K7367 using an automatic viscosity measuring device "SS-600-L2" manufactured by Shibayama Kagaku Kikai Seisakusho. -5, the IV of the pellet was measured. The IV of each Example was set as IV _P and the IV of Reference Example 1 was set as IV ₁ , and the increase in intrinsic viscosity was evaluated according to the following evaluation criteria.
◎: IV _P /IV ₁ ≧15 (extremely good)
〇: 10≦IV _P /IV ₁ <15 (Good)
△: 5≦IV _P /IV ₁ <10 (Practical)
×: IV _P /IV ₁ <5 (not practical)

[Yellowness (YI value)]
Each of the produced pellets was injection molded at 270° C. using an injection molding machine (manufactured by Toshiba Machine Co., Ltd., model IS-100F) to produce a rectangular parallelepiped plate measuring 30 mm long x 40 mm wide x 3 mm high. After that, the L value (lightness), a value, and b value of the test piece were measured using an image spectrophotometer AU Color COLOR7x manufactured by Kurabo Industries, Ltd. with a D-65 (10) standard light source, and the YI value was determined according to JIS K7373. The value was calculated and the degree of yellowness was measured. Yellowing was evaluated using the following criteria.
◎: 0≦YI<5 (extremely good)
○: 5≦YI<10 (good)
△: 10≦YI<20 (Practical)
×: 20≦YI (not practical)

[White turbidity]
The haze of the plate evaluated for yellowness (YI value) was measured using Haze Guard Plus (manufactured by Gardner) according to JIS K7136, and the white turbidity was evaluated according to the following criteria.
◎: Haze ≦10% (extremely good)
〇:10<Haze≦15% (Good)
△: 15<Haze≦20% (Practical)
×: Haze>20% (not practical)

[Impact strength evaluation]
The produced pellets were each blow-molded at 280° C. using a blow-molding machine to produce 50 PET bottles according to each example. The thickness of the plastic bottle was 1 mm. An impact test was conducted on 10 of the obtained PET bottles. Specifically, a plastic bottle was filled 80% with water and dropped from a height of 1 meter. The evaluation criteria were as follows, and moldability was confirmed.
◎: N=10, no deformation or holes were observed. (Extremely good)
○: N=10, no holes were found, but some deformation was observed. (Good)
△: One hole was observed and water spilled out. (Practical)
×: Two or more holes were observed. (Not practical)

(Example 52)
A tumbled product of 100 parts of recycled homo-PET resin (IV: 0.60 dl/g) and 1 part of thickening masterbatch for polyester resin (M-1) was prepared using a screw diameter of 30 mm (L/D) manufactured by Japan Steel Works. Extrusion processing was performed using a twin-screw extruder (=53.5) at a screw rotation speed of 200 rpm and a processing temperature of 270°C to produce pellets for molding.

(Examples 53 to 69), (Comparative Example 4)
Remolding pellets were produced in the same manner as in Example 52, except that the materials and blending amounts (parts by mass) shown in Table 4 were changed.

Evaluation of molded pellets and molded bodies produced using a twin-screw extruder was carried out in the same manner as those produced using a single-screw extruder. Note that the intrinsic viscosity (IV) is determined by replacing IV ₁ in Reference Example 1 with IV ₂ in Reference Example 2. Each evaluation criterion was the same as that for the single-screw extruder.

From the results in Tables 4-1 and 4-2, it is clear that the molded bodies obtained in the examples suppressed odor, decreased transparency, and yellowing by using a thickener for polyester resin, and were made from recycled polyester resin. It can be seen that the molding processability can be improved, and molding can be performed using a single-screw extruder and a twin-screw extruder.

Claims (7)

Selected from the group consisting of an epoxy group-containing monomer unit (X), an aromatic ring-containing monomer unit (Y), and other monomer units (Z) (but does not have an epoxy group or an aromatic ring) A thickener for polyester resin of a polymer having a weight average molecular weight of 6,000 or more and containing one or more types of monomer units,
A thickener for polyester resin, wherein the content of components having a weight average molecular weight of less than 1,000 in the thickener for polyester resin is 0.001 to 4.5% by mass. The thickener for polyester resin according to claim 1, wherein the content of the epoxy group-containing monomer unit (X) is 10 to 90% by mass based on the total monomer units of the polymer. The thickener for polyester resin according to claim 1, wherein the epoxy value of the polymer is 0.4 to 6.5 mmol/g. A thickening masterbatch for polyester resin, comprising a reaction product of the thickener for polyester resin according to any one of claims 1 to 3 and polyester resin (A). The thickening masterbatch for polyester resin according to claim 4, wherein the masterbatch has an epoxy value of 0.4 to 3.6 mmol/g. The thickening masterbatch for polyester resin according to claim 4, wherein the content of the thickening agent for polyester resin is 35 to 60% by mass in the thickening masterbatch for polyester resin. A molded article obtained by molding a polyester resin for dilution and a thickening masterbatch for polyester resin according to claim 4.