JP-7856005-B2 - Polyester elastomer resin composition and cable covering material made therefrom

Inventors

• 玉城 勇気
• 赤石 卓也
• 原田 伸治

Assignees

• 東洋紡エムシー株式会社

Dates

Publication Date

20260511

Application Date

20220317

Priority Date

20210323

Claims (9)

1. A polyester elastomer resin composition comprising 50 to 90 parts by mass of a polyester elastomer (A) comprising a hard segment made of a polyester composed of an aromatic dicarboxylic acid and an aliphatic and/or alicyclic diol, and a soft segment selected from aliphatic polyester and aliphatic polycarbonate, 10 to 50 parts by mass of an unmodified olefin-based elastomer (B), and further comprising 0.1 to 5 parts by mass of an acid end-canceling agent (C) per 100 parts by mass of the total of the polyester elastomer (A) and the unmodified olefin-based elastomer (B), characterized in that the carboxyl group concentration in the resin composition is 10 eq/ton or less , the erosion depth in an acid resistance test is 1.2 mm or less, the heat resistance elongation half-life at 170°C is 500 hours or more, and the hard segment of the polyester elastomer (A) does not contain isophthalic acid as a component .
2. The polyester elastomer resin composition according to claim 1, further containing 1 to 10 parts by mass of epoxy group-containing polyolefin (D) per 100 parts by mass of polyester elastomer (A) and unmodified olefin-based elastomer (B).
3. The polyester elastomer resin composition according to claim 1 or 2 , wherein the unmodified olefin-based elastomer (B) is an elastomer containing styrene as a copolymer component.
4. The polyester elastomer resin composition according to any one of claims 1 to 3, wherein the polyester elastomer (A) is a copolymer having a melting point of 150 to 230°C , with terephthalic acid, 1,4-butanediol, and aliphatic polycarbonate diol as the main components.
5. A polyester elastomer resin composition according to any one of claims 1 to 4, further containing 5 to 30 parts by mass of a brominated flame retardant (E) and a flame retardant aid (F) per 100 parts by mass of a total of polyester elastomer (A) and unmodified olefin-based elastomer (B).
6. A polyester elastomer resin composition according to any one of claims 1 to 4, further containing 5 to 50 parts by mass of a phosphorus-based flame retardant (G) per 100 parts by mass of a total of polyester elastomer (A) and unmodified olefin-based elastomer (B).
7. The polyester elastomer resin composition according to claim 6, wherein the phosphorus-based flame retardant (G) has an average particle size D50 of 20 μm or less and a phosphorus concentration of 15% by mass or more.
8. A polyester elastomer resin composition according to any one of claims 1 to 7 , for use as a cable sheath.
9. A cable covering material comprising the polyester elastomer resin composition described in any one of claims 1 to 7.

Description

This invention relates to a polyester elastomer composition suitable for extrusion molding, exhibiting excellent acid resistance and heat aging resistance. Thermoplastic polyester elastomers have long been known and put into practical use in which crystalline polyesters such as polybutylene terephthalate (PBT) and polybutylene naphthalate (PBN) are used as hard segments, and polyoxyalkylene glycols such as polytetramethylene glycol (PTMG) and/or aliphatic polyesters such as polycaprolactone (PCL) and polybutylene adipate (PBA) are used as soft segments. However, it is known that polyester polyether-type elastomers using polyoxyalkylene glycols in the soft segment have excellent water resistance and low-temperature properties but poor heat aging resistance, while polyester-polyester-type elastomers using aliphatic polyesters in the soft segment have slightly inferior water resistance and low-temperature properties but excellent heat aging resistance. To address the above drawbacks, polyester polycarbonate elastomers using polycarbonate in the soft segment have been proposed (see, for example, Patent Documents 1 to 5). As a result, the above-mentioned problems are solved, and the polyester polycarbonate elastomers disclosed in these patent documents are used in applications requiring high heat aging resistance, such as components around automobile engines, taking advantage of their excellent characteristics. In the future of the automotive industry, electric vehicles are expected to become the mainstream, replacing conventional gasoline-powered vehicles. This will lead to an increase in the number of in-vehicle cables, and the aforementioned polyester polycarbonate elastomer is expected to be a promising material for next-generation in-vehicle cable sheathing due to its high heat aging resistance and flexibility. However, a crucial requirement for this application is passing a battery fluid (sulfuric acid) drop test, and conventional polyester elastomers have not been able to achieve this. There was a need to improve acid resistance while maintaining its high heat aging resistance and flexibility. Special Publication No. 7-39480Japanese Patent Application Publication No. 10-182782Japanese Patent Publication No. 2001-206939Japanese Patent Publication No. 2001-240663Patent No. 4244067 [Polyester elastomer (A)] The polyester elastomer (A) used in the present invention consists of a hard segment and a soft segment. The hard segment is made of polyester. The aromatic dicarboxylic acid constituting the polyester of the hard segment is not particularly limited, and a wide range of ordinary aromatic dicarboxylic acids are widely used, but it is desirable that the main aromatic dicarboxylic acid be terephthalic acid or naphthalenedicarboxylic acid (among the isomers, 2,6-naphthalenedicarboxylic acid is preferred). Of the total dicarboxylic acids constituting the polyester of the hard segment, terephthalic acid or naphthalenedicarboxylic acid is preferably 70 mol% or more, and more preferably 80 mol% or more. Other dicarboxylic acid components include aromatic dicarboxylic acids such as diphenyl dicarboxylic acid, isophthalic acid, and 5-sodium sulfisoisophthalic acid; alicyclic dicarboxylic acids such as cyclohexane dicarboxylic acid and tetrahydrophthalic anhydride; and aliphatic dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, dimer acid, and hydrogenated dimer acid. These are used within a range that does not significantly lower the melting point of the polyester elastomer (A), and their amount is preferably 30 mol% or less of the total acid component, and more preferably 20 mol% or less. Furthermore, in the polyester elastomer (A) used in the present invention, the aliphatic or alicyclic diol constituting the polyester of the hard segment is not particularly limited, and a wide variety of general aliphatic or alicyclic diols are widely used, but it is desirable that it be mainly alkylene glycols having 2 to 8 carbon atoms. Specifically, examples include ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, and 1,4-cyclohexanedimethanol. Among these, ethylene glycol or 1,4-butanediol is preferred for imparting heat resistance. As for the components constituting the polyester of the hard segment described above, those consisting of butylene terephthalate units (units consisting of terephthalic acid and 1,4-butanediol) or butylene naphthalate units (units consisting of 2,6-naphthalenedicarboxylic acid and 1,4-butanediol) are preferred in terms of physical properties, moldability, and cost performance. Furthermore, when an aromatic polyester suitable for constituting the hard segment of the polyester elastomer (A) used in the present invention is manufactured in advance and then copolymerized with the soft segment component, the aromatic polyester can be easily obtained according to the usual method for manufacturing polyester. It is