JPS6114164B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to flexible polyester power transmission components. More specifically, the present invention relates to a power transmission part made of a random copolyester comprising a terephthalic acid component, a decanedicarboxylic acid component, and a tetramethylene glycol component. In recent years, soft resins that can be molded by melt molding methods such as injection molding have been in the spotlight, and for example, block polyether esters obtained from terephthalic acid, tetramethylene glycol, and polytetramethylene glycol have been attracting attention. however,
The thermoplastic soft resins currently in use generally have low heat resistance; some soften at 100°C, and others require the use of large amounts of heat stabilizers. As a result of repeated studies to find a soft resin that does not have these drawbacks, the present inventors found that polybutylene terephthalate, which is made by randomly copolymerizing a specific amount of decanedicarboxylic acid, is soft, has high heat resistance, and is easy to mold. The present invention was based on the discovery that the resulting power transmission component is stable even when used in a high-temperature atmosphere, generates little noise, and has excellent mechanical properties. That is, the present invention is a random copolymerized polyester containing terephthalic acid and decanedicarboxylic acid as acid components and tetramethylene glycol as a glycol component, in which the decanedicarboxylic acid component is contained in an amount of 10 to 50 mol% based on the total dicarboxylic acid component. The present invention relates to a soft polyester power transmission part made by melt-molding a polyester having a reduced viscosity (measured in ochlorophenol at 35° C. at a concentration of 1.2 g/100 ml) of 1.0 or more. The soft polyester referred to in the present invention is a polyester whose constituent components are terephthalic acid, tetramethylene glycol, and decanedicarboxylic acid.
This polyester may contain other components such as aromatic dicarboxylic acids such as isophthalic acid, phthalic acid, naphthalenedicarboxylic acids, diphenoxyethanedicarboxylic acids, diphenyldicarboxylic acids, etc.; adipic acid, sebacic acid, azelaic acid, cyclohexanedicarboxylic acid, etc. Aliphatic or alicyclic dicarboxylic acids such as; aliphatic diols such as ethylene glycol, trimethylene glycol, hexamethylene glycol, etc.; aromatic diols such as hydroquinone, bisphenols and their glycol adducts; oxycaproic acid, It may be copolymerized with oxycarboxylic acid such as oxybenzoic acid in an amount of 20 mol% or less, preferably 10 mol% or less. These polyesters can be produced by conventional methods, for example melt polymerization methods. For example, a method in which terephthalic acid or a lower alkyl ester thereof, decanedicarboxylic acid or a lower alkyl ester thereof, and tetramethylene glycol are subjected to an esterification or transesterification reaction, and then the reaction product is melt-polymerized under reduced pressure, or the above-mentioned melt polymerization After carrying out this process, it can be produced by further solid phase polymerization. The above-mentioned soft polyester needs to be copolymerized with decanedicarboxylic acid in an amount of 10 to 50 mol%, preferably 20 to 40 mol%. Although it is possible to obtain a soft polyester by copolymerizing components other than decanedicarboxylic acid, for example aliphatic dicarboxylic acids such as azelaic acid and sebacic acid, in this case, if the object of the present invention is not achieved, the softening point The decrease becomes significant, which is not preferable. Furthermore, if the copolymerization ratio of decanedicarboxylic acid is less than 10 mol%, it is insufficient to make the polymer soft, while if the ratio exceeds 50 mol%, the crystallization rate during molding will be slow and the softening point will be low. So I don't like it. The soft polyester of the present invention preferably has a reduced viscosity of 1.0 or more, preferably 1.0 to 3.0. If the reduced viscosity is lower than this, the mechanical properties such as tensile strength of the molded article will be low, and the heat resistance will also be low, which is not preferable. In the present invention, such a soft polyester is melt-molded to form a power transmission part, and injection molding can be used as the molding method. These molding conditions may be, for example, that the temperature of the cylinder part of the melting zone is 170 to 240°C, and the cooling temperature of the mold etc. is room temperature to 120°C. It is also important to dry the polyester before melt molding, and the moisture concentration in the polyester should be reduced to 0.1wt%.
It is preferable to do the following. The soft polyester power transmission parts molded in this manner are, for example, gears, joints, and cams.
The soft polyester of the present invention is extremely useful as a molding material for these materials, and power transmission parts molded from the polyester have the following features. (a) It is soft, generates less noise, and has a higher elastic modulus than the above-mentioned polyether ester when the surface hardness is the same, so it deforms less. (b) It is flexible even at low temperatures. (c) High heat resistance. (d) Highly resistant to gasoline, lubricating oil, grease, etc. (e) Good light resistance. The present invention will be explained in detail with reference to Examples below. Note that "parts" in the examples are "parts by weight." Example 1 136 parts of terephthalic acid, 69 parts of decanedicarboxylic acid (30 mol%), 190 parts of tetramethylene glycol, and a catalytic amount of titanium tetrabutoxide were charged into a reactor, and an esterification reaction was carried out at a temperature of 240°C. After distilling off about 70 parts of water, heat at 240°C.
The pressure in the reactor was gradually reduced to 0.2 mmHg and polycondensation was carried out for 3 hours to obtain a polyester with a reduced viscosity of 1.35. This polyester was dried at 140°C for 4 hours to obtain dry chips with a moisture content of 0.02%. Using this dry chip, the cylinder temperature is 200.
The following molded product was obtained by injection molding at a mold temperature of 60°C. (1) JIS No. 3 dumbbell for tensile testing. (2) 1/4 inch thick bar for bending test. (3) Gear with a diameter of 1cm and a thickness of 1.5mm. The results of tests conducted using these molded bodies are shown in the table below. Polytetramethylene terephthalate copolymerized with 30% by weight of polytetramethylene glycol is also listed in the table as a comparative example. 【table】

Claims (1)

[Claims] 1 A random copolymerized polyester containing terephthalic acid and decanedicarboxylic acid as acid components and tetramethylene glycol as a glycol component, wherein the decanedicarboxylic acid component is 10% per total acid component.
It contains ~50 mol% and has a reduced viscosity (1.2
A power transmission part made by melt-molding polyester having a value of 1.0 or more (measured in ochlorophenol at 35°C at a concentration of g/100ml).