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JP-7856096-B2 - Polyester resin

JP7856096B2JP 7856096 B2JP7856096 B2JP 7856096B2JP-7856096-B2

Inventors

  • 佐々木 浩尚
  • 畑中 洋祐
  • 戸川 惠一朗

Assignees

  • 東洋紡株式会社

Dates

Publication Date
20260511
Application Date
20220922
Priority Date
20210927

Claims (4)

  1. The compound contains terephthalic acid as a dicarboxylic acid component, ethylene glycol, 1,4-butanediol, and a compound represented by the following formula (I) as alcohol components, wherein terephthalic acid is present in an amount of 85 to 100 mol% of the dicarboxylic acid component, and 1,4-butanediol is present in an amount of 85 to 100 mol% relative to the total amount of ethylene glycol and 1,4-butanediol. The compound represented by formula (I) contains the following copolymer components (M), (N), and (L) as constituent units, where R1 in copolymer component (M) represents an aromatic hydrocarbon group having 6 to 20 carbon atoms, R2 , R3 , and R4 in copolymer components (N) and (L) each represent a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and the number of copolymer components (M), (N), and (L) is represented by m, n, and l, respectively, where m and n represent 1 to 1000, and l represents 0 to 1000. The compound represented by formula (I) is a polyester resin characterized by being present in an amount of 0.001 to 5% by mass of the alcohol component in 100% by mass.
  2. The polyester resin according to claim 1, wherein the weight-average molecular weight of the compound represented by formula (I) is 275 or more and 500,000 or less.
  3. The polyester resin according to claim 1 or 2, wherein the melt tension is 15 mN or more at a temperature of 270°C, a draw speed of 100 m/min, and a shear speed of 243 s⁻¹ .
  4. The polyester resin according to claim 1 or 2, wherein the melt viscosity is 26,000 dPa·s or more at a temperature of 270°C and a shear rate of 30 s⁻¹ , and 6,500 dPa·s or less at a temperature of 270°C and a shear rate of 2,000 s⁻¹.

Description

This invention relates to a polyester resin that provides molded articles with excellent moldability, transparency, mechanical properties, heat resistance, heat oxidation stability, and chemical resistance. More specifically, this invention relates to a polyester resin that improves moldability in extrusion molding, shape extrusion molding, direct blow molding, inflation molding, injection blow molding, and calendering molding, which require high melt tension, as well as improving transparency, heat resistance, mechanical properties, heat oxidation stability, and chemical resistance. In recent years, there has been a trend to replace polyvinyl chloride resins with other materials, for example, due to environmental impact concerns. Among the many alternative materials, polyester resin is being considered as a promising option in terms of physical properties, environmental suitability, adhesive properties, and price. In particular, crystalline polyester resins such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene naphthalate (PEN) are used in a variety of melt-molded products, including heat-resistant parts produced by injection molding, films and sheets produced by extrusion molding, beverage bottles produced by blow molding, and fibers produced by melt spinning. However, improving the transparency and flexibility of molded products using these crystalline polyester resins requires various technologies, such as controlling cooling conditions during processing and stretching treatments. Furthermore, in shape extrusion molding, direct blow molding, and inflation molding, which require high melt tension, the drawdown phenomenon becomes significant, causing pre-molded or molded products to sag, resulting in uneven thickness and increased burrs in the molded products, which leads to problems such as a decrease in the yield rate and stability of continuous production. On the other hand, inventions have been disclosed that improve the moldability of direct blow molding, which requires high melt tension, by introducing a branched structure (branching agent) into the resin skeleton in order to solve the problem of the drawdown phenomenon (for example, Patent Documents 1 to 3). Patent No. 5931061Patent No. 5941843Japanese Patent Publication No. 2016-56384 1. Polyester Resin The polyester resin of the present invention contains terephthalic acid as a dicarboxylic acid component, ethylene glycol, 1,4-butanediol, and a compound represented by the following formula (I) as alcohol components, wherein terephthalic acid is present in an amount of 85 to 100 mol% of the dicarboxylic acid component, 1,4-butanediol is present in an amount of 85 to 100 mol% of the total amount of ethylene glycol and 1,4-butanediol, and the compound represented by the following formula (I) is present in an amount of 0.001 to 5% by mass of 100% by mass of the alcohol component. (In the formula, m and n are integers from 1 to 1000, each representing an integer from 0 to 1000, R1 represents an aromatic hydrocarbon group having 6 to 20 carbon atoms, and R2 , R3 , and R4 each represent a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. R5 represents a monool ( CH2CH2CH2CH2OH ) with 4 carbon atoms.) The polyester resin of the present invention is characterized in that it contains a polymer of a predetermined dicarboxylic acid component and an alcohol component, and the alcohol component has a predetermined content of a compound represented by formula (I). In the present invention, the compound represented by formula (I) is a branching agent for polyester resins and is used together with commonly used diol components. Furthermore, the compound represented by formula (I) has two or more functional groups (hydroxyl groups) per molecule that can react with the carboxyl group of the dicarboxylic acid component, and a branched structure can be partially introduced into the entire polyester resin. As described above, the polyester resin of the present invention uses a compound represented by formula (I), which suppresses gelation. During melt extrusion, the melt tension decreases as the temperature increases, and the melt viscosity decreases under high shear. As a result, melt fracture does not occur during molding, and the resin exhibits excellent moldability, surface smoothness, transparency, mechanical properties, heat resistance, heat oxidation stability, and chemical resistance. The compounds represented by formula (I) are as follows: (In the formula, m and n are integers from 1 to 1000, each representing an integer from 0 to 1000, R1 represents an aromatic hydrocarbon group having 6 to 20 carbon atoms, and R2 , R3 , and R4 each represent a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. R5 represents a monool ( CH2CH2CH2CH2OH ) with 4 carbon atoms.) R1 represents an aromatic hydrocarbon group having 6 to 20 carbon atoms. Aromatic hydrocarbon groups with 6 to 20 carbon atoms represented by R