JPH03229752A - Polyester elastomer composition - Google Patents

Abstract

PURPOSE:To obtain the title composition excellent in injection moldability, sliding properties and molding appearance and useful for mechanical parts, etc., by mixing a polyester elastomer based on an aromatic dicarboxylic acid, an aliphatic diol and a poly(alkylene oxide) glycol with a specified component. CONSTITUTION:100 pts.wt. polyester elastomer [comprising an aromatic dicarboxylic acid and its esterifiable derivative (a), an aliphatic diol and its esterifiable derivative (b) and a poly(alkylene oxide) glycol (c) (of a number- average mol.wt. of 500-6000) and having a component (c) content of 10-80wt.%] is mixed with 0.01-5 pts.wt. polyethylene wax and 0.01-5 pts.wt. polyethylene terephthalate and/or talc to obtain a polyester elastomer composition useful for mechanical parts such as gears, cams and rollers.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Field of Application> The present invention relates to a polyester elastomer composition that has excellent injection moldability, slidability, and molded product appearance.

<Prior art> A polyether ester block copolymer mainly composed of polybutylene terephthalate as a hard segment and poly(alkylene oxide) glycol as a soft segment is used as a polyester elastomer with rubber-like elasticity in electrical and electronic parts, automobile parts, and textiles. , and its use is expanding to include films, etc. On the other hand, the use of elastomers is limited, especially in mechanical parts such as gear cams and rollers, due to insufficient injection moldability and sliding properties.

Conventionally, a method of adding a lubricant is known as a method of imparting injection moldability to a polyester elastomer. In particular, Japanese Patent Publication No. Sho 58-58380 proposes adding a lubricant of Na salt of montanic acid wax as a release property improving agent. Furthermore, as a method for imparting sliding properties, a method of adding a sliding property improving material is known. In particular, JP-A-61-195154 proposes adding silicone oil as a sliding properties improving material.

<Problems to be Solved by the Invention> In the aforementioned Japanese Patent Publication No. 58-58380, when a large amount of Na salt of montanic acid wax was added, white powder was generated on the surface of a polyester elastomer molded product. Therefore, injection moldability was also unsatisfactory since the amount added could not be increased. Furthermore, when a large amount of silicone oil is added as shown in JP-A-81-195154, the compatibility between the polyester elastomer and the silicone oil is poor, causing delamination on the surface of the molded product, resulting in unsatisfactory sliding properties and appearance of the molded product. It wasn't something I could do easily.

Accordingly, an object of the present invention is to provide a polyester elastomer composition that has excellent injection moldability represented by mold releasability and slidability, as well as excellent appearance of molded products.

<Means for Solving the Problems> As a result of intensive studies by the present inventors to solve the problems in injection moldability and sliding properties of polyester elastomers,
The inventors have discovered that injection moldability, sliding properties, and appearance of molded products can be significantly improved by using polyethylene wax in combination with polyethylene terephthalate and/or talc, and have thus arrived at the present invention.

That is, the present invention provides: (a) aromatic dicarboxylic acids and ester-forming derivatives thereof; (b) aliphatic diols and ester-forming derivatives thereof;

(c) three main constituents are poly(alkylene oxide) glycol having a number average molecular weight of 500 to 6,000,
0.01 to 5 parts by weight of polyethylene wax and 0.01 to 5 parts by weight of polyethylene phthalate and/or talc to 100 parts by weight of polyester elastomer in which component (c) accounts for 10 to 80% by weight in the total copolymer. The object of the present invention is to provide a polyester elastomer composition comprising:

The polyester elastomer used in the present invention is composed of short chain polyester hard segments and long chain polyester soft segments made of poly(alkylene oxide) glycol and dicarboxylic acid. The polyester constituting this short chain polyester hard segment is preferably (a) terephthalic acid and/or dimethyl terephthalate, (b) polybutylene terephthalate derived from 1,4-butanediol, but isophthalic acid, phthalic acid , naphthalene-2,8-dicarboxylic acid, naphthalene-2,7-dicarboxylic acid, diphenyl-4,4
-dicarboxylic acid, diphenoxyethanedicarboxylic acid, 5
- dicarboxylic acid components other than terephthalic acid, such as sulfoisophthalic acid, 1,4-cyclohexanedicarboxylic acid, succinic acid, oxalic acid, adipic acid, sebacic acid, dodecanniic acid, dimic acid, etc., and ester-forming derivatives thereof; , and diols with a molecular weight of 300 or less, such as ethylene glycol, trimethylene glycol, pentamethylene glycol, hexamethylene glycol,
Aliphatic diols such as neopentyl glycol and decamethylene glycol, and ester-forming derivatives thereof, 1.1-cyclohexane dimetatool, 1.
Alicyclic diols such as 4-cyclohexane dimetatool and tricyclodecane dimetatool, and their ester-forming derivatives, xylylene glycol, bis(
p-hydroxy)diphenyl, bis(p-hydroxyphenyl)propane, 2,2-bis[4-(2-hydroxyethoxy)phenylcopropane, bis[4(2-hydroxy)phenyl]sulfone, 1゜1-bis [4-(
1, such as 2-hydroxyethoxy)phenylcocyclohexane, and their ester-forming derivatives.
, 3-diol component other than 4-butanediol is the acid component
Polyester elastomers copolymerized within 0 mol% can also be used.

The poly(alkylene oxide) glycol of component (c) constituting the long chain polyester soft segment of the polyester elastomer of the present invention includes poly(ethylene oxide) glycol, poly(propylene oxide) glycol, poly(tetramethylene oxide) glycol,
Examples include poly(hexamethylene oxide) glycol, a copolymer of ethylene oxide and propylene oxide, an ethylene oxide addition polymer of poly(propylene oxide) glycol, and a copolymer of ethylene oxide and tetrahydrofuran. Among these, ethylene oxide addition polymers of poly(tetramethylene oxide) glycol and poly(propylene oxide) glycol are particularly excellent in terms of mechanical strength and moldability as molded articles. (
The optimum number average molecular weight of component c) poly(alkylene oxide) glycol varies depending on its chemical structure, type of short-chain polyester had segment, and copolymerization ratio, but is more preferably 500 to 65.
It is 0-4000. If the number average molecular weight is too small, the heat resistance and molding processability will be poor, and if it is too large, the polymer will become emulsified due to coarse phase separation during polymerization, which is not preferable, since it will give only a non-transparent product.

Furthermore, the copolymerized amount of poly(alkylene oxide) glycol, component (c), must be in the range of 10 to 80% by weight, preferably 15 to 75% by weight, for the reasons described above. In particular, if it is less than 10% by weight, the flexibility and rubber-like elasticity will be insufficient, and if it is more than 80% by weight, the crystallinity will be low and the moldability will be poor, making it impossible to use it.

The polyester elastomer of the present invention comprising the above-mentioned components can be produced by a known method. For example, a method in which a lower alcohol diester of a dicarboxylic acid, an excess amount of a low molecular weight glycol, and a poly(oxyalkylene) glycol are transesterified in the presence of a catalyst, and the resulting reaction product is polycondensed. Alternatively, a method in which dicarboxylic acid, glycol, and poly(oxyalkylene) glycol are subjected to an esterification reaction in the presence of a catalyst, and the resulting product is polycondensed. Alternatively, you can make polybutylene terephthalate in advance and add other dicarboxylic acids, diols, and poly(oxyalkylene) glycol to it.
Alternatively, any method may be used, such as adding another copolymerized polyester and randomizing it by transesterification.

Titanium catalysts give good results as common catalysts for transesterification or esterification reactions and polycondensation reactions. Particularly preferred are tetraalkyl titanates such as tetrabutyl titanate and tetramethyl titanate, and metal salts of titanium oxalate such as potassium titanium oxalate.

Other catalysts include tin compounds such as dibutyltin oxide and dibutyltin laurate, and lead compounds such as lead acetate. Further, in the process of producing the polyester elastomer, a polyfunctional carboxylic acid component, a polyoxyacid component, a polyfunctional hydroxyl component, etc. can be copolymerized in an amount of 3 mol % or less each.

These are useful for shortening polymerization time and obtaining high viscosity polymers necessary for extrusion molding and the like.

The polyethylene wax used in the present invention is a polyethylene wax with a molecular weight of 5000 or less obtained by a high-pressure method or a low-pressure method, and carboxylic acid groups and hydroxyl groups can be introduced into the molecule by a method such as oxidation. Furthermore, acid-modified polyethylene wax containing maleic anhydride can also be used.

If the molecular weight of the polyethylene wax exceeds 5,000, the compatibility with the polyester elastomer will be poor and the effect of improving moldability will be small, which is not preferable. In addition, the amount of polyethylene wax added is 10% of the polyester elastomer.
0.01 to 5 parts by weight, preferably 0.01 to 5 parts by weight.
02 to 3 parts by weight. If it is less than 0.01 part by weight, injection moldability will not be sufficient, and if it is more than 5 parts by weight, delamination will occur on the surface of the polyester elastomer molded product, which will impair the appearance of the molded product, which is not preferred.

The polyethylene terephthalate used in the present invention contains terephthalic acid and ethylene glycol as essential components, and can also be used even if it contains small amounts of other dicarboxylic acids and/or other diols. The amount of polyethylene terephthalate added is 0.01 to 5 parts by weight, preferably 0.02 to 1.5 parts by weight, based on 7100 parts by weight of the polyester elastomer. If it is less than 0.01 part by weight, the sliding properties will not be sufficient. , 5 parts by weight or more is not preferable because the flexibility of the polyester elastomer is impaired.

The talc used in the present invention is S i O2 and M g O
An inorganic fine powder whose main component is 40 μm or less is preferable. The amount of talc added is 100% of polyester elastomer.
0.01 to 5 parts by weight, preferably 0.0 parts by weight
It is 2 to 2 parts by weight. If the amount is less than 0.01 parts by weight, the sliding properties will not be sufficient, and if it is more than 5 parts by weight, the mechanical properties of the polyester elastomer will be impaired, which is not preferable.

The heat resistance, especially the thermochromic property, of the composition of the present invention is improved by adding a stabilizer. These stabilizers include phosphorus compounds such as phosphoric acid, phosphorous acid, hypophosphorous acid derivatives, phenylphosphonic acid, phenylphosphinic acid, diphenylphosphonic acid, polyphosphonates, dialkylpentaerythritol diphosphite, and dialkylbisphenol A diphosphite. Sulfur-containing compounds such as , hindered phenol compounds, thioethers, dithioate salts, mercaptobenzimidazoles, thiocarbanilides, and thiodipropionic acid esters, and tin-based compounds such as stanmalate and dibutyltin monoxide can be used.

The amount of these stabilizers added is as follows: polyester elastomer 1
The amount is preferably 0.01 to 2 parts by weight per 00 parts by weight.

In addition, for the composition of the present invention, dyes, pigments, inorganic reinforcing materials,
Plasticizer, hindered amine light stabilizer, ultraviolet absorber,
Known additives such as blowing agents, thickeners such as epoxy compounds and isocyanate compounds can be added.

The composition of the present invention is generally produced by a known method.

For example, polyester elastomer, polyethylene wax, polyethylene terephthalate and/or talc, and other necessary additives may be melt-mixed in an extruder or kneader, or the particles may be homogeneously mechanically mixed together and then directly mixed. Examples include a method of mixing and molding simultaneously with an injection molding machine. Further, the order of addition at this time may be arbitrary.

The composition of the present invention is subsequently made into molded products by injection molding, extrusion molding, compression molding, etc., and these molded products have excellent injection moldability, sliding properties, and molded product appearance, so they can be used as mechanical parts and automobile parts. It is useful as

<Example> The present invention will be explained in detail below using Examples.

Note that all percentages and parts in the examples are based on weight.

Moreover, relative viscosity is a value measured at 25° C. of a 0.5% polymer solution using 0-chlorophenol as a solvent.

Reference Example Polymerization of polyester elastomer 45.3 parts of terephthalic acid, 20.0 parts of poly(tetramethylene oxide) glycol having a number average molecular weight of 1400 and 1. 49.0 parts of 4-butanediol and 0.01 part of titanium tetrabutoxide were charged into a reaction vessel equipped with a helical ribbon stirring blade, and the mixture was heated at 190 to 225°C for 3 hours to carry out an esterification reaction. Next, the temperature was raised to 245° C., and the pressure inside the system was reduced to 0.2 mmHH over 50 minutes, and polymerization was carried out under these conditions for 2 hours and 35 minutes. The obtained polymer was discharged into water in a slant shape and cut into pellets. This polymer is designated as A-1. Polymerization was carried out in the same manner to prepare A-2 having the composition shown in Table 1.

Table 1 Examples 1 to 5 The polyester elastomer obtained in the reference example was mixed with the polyethylene wax shown in Table 2 and polyethylene terephthalate and/or talc in a blender.
2θ using a twin screw extruder with a 5mmφ screw
The mixture was melt-kneaded at 0° C. and pelletized. 10 of these pellets
After vacuum drying at 0℃ for 5 hours, molding temperature of 240℃, 60℃
100mm long with 4 ejected bottles at a mold temperature of
The molded product was injection molded using a mold having the following dimensions: x width 60ax x height 24ux x thickness 2.5m.

The stress when ejecting the molded product from the movable side of the mold was detected by a load cell and used as the mold release force. In addition, after leaving the obtained molded product at room temperature for one month, the surface of the molded product was visually observed.
It was evaluated whether white powder was generated in the molded product.

In addition, a 3 mm thick thrust wear test piece was injection molded f! in the same manner as above. A 1 cm2 piece of 545C iron was used as a mating material, and the amount of wear was evaluated by sliding it for 1 hour under a load of 10 kg using a thrust abrasion tester.

Comparative Examples 1-B Polymers of Reference Examples to which polyethylene wax was not added and polymers of A-2 were added with Na salt of montanic acid wax shown in Table 2 and silicone oil in Examples 1-B.
A polymer blend obtained by melt-kneading in the same manner as in Example 5 was injection molded in the same manner as in Example. They were evaluated in the same manner as in the examples.

Margin below Table 2 Ma Ta, Mold release force of Examples and Comparative Examples, outside of molding Table 3 shows the appearance and amount of wear.

Table 3 From the results in Table 3, the composition of the present invention shows a significant reduction in mold release force and wear amount by adding a small proportion of polyethylene wax and polyethylene terephthalate and/or talc.
Furthermore, it is clear that the molded product has an excellent appearance and improved injection moldability and sliding properties.

<Effects of the Invention> The present invention provides a polyester elastomer that exhibits excellent injection moldability and slidability by blending polyethylene wax, polyethylene terephthalate, and/or talc with a polyester elastomer, and has a good molded product appearance. As a result, it is expected that polyester elastomers will be increasingly used for industrial applications that require injection moldability.

Claims (1)

Scope of Claims: (a) aromatic dicarboxylic acids and their ester-forming derivatives, (b) aliphatic diols and their ester-forming derivatives, and (c) poly(alkylene oxide) glycols having a number average molecular weight of 500 to 6,000. The three main components are
0.01 to 5 parts by weight of polyethylene wax and 0.01 to 5 parts by weight of polyethylene terephthalate and/or talc to 100 parts by weight of polyester elastomer in which component (c) accounts for 10 to 80% by weight in the total copolymer. A polyester elastomer composition comprising: