JPS62169610A - Manufacture of polyamide elastomer compression-molded form - Google Patents

Abstract

PURPOSE:To obtain a polyamide elastomer compression-molded form, excellent in resistance to abrasion and having large spring effect, by a method wherein a polyamide elastomer block is deformed by compression axially more than a specified ratio in the length thereof. CONSTITUTION:A polyamide elastomer, employed in this process, is preferable to be polyether ester amide consisting of amino-carboxylic acid or lactam, having 6 or more of number of carbon atoms, or (a) the salt of diamine, having 6 or more of number of carbon atoms, and dicarboxylic acid, (b) poly(alkylene oxide) glycol having the number-average molecular weight of 300-6,000 and (c) dicarboxylic acid having 4-20 number of carbon atoms. A block, obtained by a method wherein a block of polyamide elastomer is compressed at least 20% in a predetermined axial direction and a stress in the axial direction is removed, is machined into a molding used for the use of a spring, a cushion member, a pad, a shock absorbing member or the like while keeping the configuration thereof or so as to obtain a configuration suitable to the object of the spring, the cushion member, the pad, the shock absorbing member or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention is directed to a method for producing a polyamide elastomer compression molded article having excellent compression set properties and abrasion resistance.

More specifically, the present invention relates to a method for producing a compression molded polyamide elastomer product that has improved compression set properties and exhibits excellent elastic recovery and abrasion resistance when used in compression springs, compression cushion materials, and the like.

<Prior art> Polyether ester amide-based polyamide elastomer, which has polyamide repeating units, polyether repeating units, and ester bonds in the polymer main chain, is known as a polymer that exhibits rubber-like elasticity, and is used in sports equipment, precision mechanical parts, and machinery. Mechanical parts, electrical/electronic parts, automobile parts, textiles,
It is being expanded into various uses such as films.

On the other hand, when used in applications such as shock-absorbing cushioning materials and compression springs, materials with excellent compression set and abrasion resistance are used in addition to the general chemical and physical property balance. materials are required.

Elastomers have traditionally been widely used as compression springs. In particular, Japanese Unexamined Patent Publication No. 55-51542 proposes a method for producing a compression spring with improved compression set properties under large deformations by pre-compressing a polyester elastomer.

<Problems to be solved by the invention> The polyester elastomer used in the above-mentioned Japanese Patent Application Laid-Open No. 55-51542 has a relatively high melting point and excellent heat resistance, but has poor abrasion resistance and does not come into contact with metal. When used as a spring for large deformations, it may make strange noises,
There is a problem in that the spring becomes eccentric and loses its symmetry.

On the other hand, polyamide elastomer has excellent elastic recovery properties, light weight, transparency, and low-temperature impact resistance, and is also useful for the above-mentioned applications because it does not easily cause cracks, sink marks, etc. during molding, but when subjected to compression deformation of 10% or more Large permanent deformation occurs, which limits its use in applications that require spring action.

Therefore, an object of the present invention is to provide a method for producing a compression molded polyamide elastomer product that has excellent wear resistance and a large spring action.

Means for Solving the Problems〉 The present inventors have conducted intensive studies to improve the above-mentioned problems of polyamide elastomers, and have found that the problems of conventional polyester elastomers have been solved by pre-compressing polyamide elastomer blocks. The inventors have discovered that it is possible to obtain polyamide elastomer molded articles with excellent abrasion resistance and compression set properties, and have arrived at the present invention.

That is, the present invention provides a polyamide elastomer compression molded product characterized by applying sufficient axial stress to compressively deform a polyamide elastomer block by 20% or more in a predetermined axial length, and then removing this axial stress. A manufacturing method is provided.

The polyamide elastomer used in the present invention is an aminocarboxylic acid or lactam having 6 or more carbon atoms, or a salt of a diamine and dicarboxylic acid having 6 or more carbon atoms (a);
A polyether ester amide composed of a poly(alkylene oxide) glycol (b) having a number average molecular weight of 300 to 6,000 and a dicarboxylic acid (C) having 4 to 20 carbon atoms is preferred.

The above (a) constituting this polyether ester amide
Examples of aminocarboxylic acids or lactams having 6 or more carbon atoms, or salts of diamines and dicarboxylic acids having 6 or more carbon atoms include ω-aminocaproic acid, ω-aminoenantoic acid, ω-aminocaprylic acid, ω- Aminocarboxylic acids such as aminopelargonic acid, ω-aminocapric acid, 11-aminoundecanoic acid, 12-aminododecanoic acid, or lactams such as caprolactam, enantlactam, capryllactam, laurolactam, and hexamethylenediamine-adipate, hexa Salts of diamines and dicarboxylic acids such as methylenediamine-sebacate, hexamethylenediamine-isophthalate, and undecamethylenedipmine-adivate are mentioned. Among these, 11-aminoundecanoic acid and 12-aminododecanoic acid are preferably used because they have excellent properties such as the rubber properties of polyether esteramide.

Also constituting the polyether ester amide of the present invention (
The poly(alkylene oxide) glycol having a number average molecular weight of 300 to 6,000 as component b) includes poly(ethylene oxide) glycol, poly(1,2- and 1,3-
Polypropylene oxide) glycol, poly(tetramethylene oxide) glycol, poly(hexamethylene oxide) glycol, block or random copolymers of ethylene oxide and propylene oxide, block or random copolymers of ethylene oxide and tetrahydrofuran, etc. can be used. Poly(tetramethylene oxide) glycol is particularly preferably used because of the properties of ether ester amide, such as water resistance, mechanical strength, and elastic recovery. The number average molecular weight of poly(alkylene oxide) glycol can be used within the range of 300 to 6000, but a molecular weight range that does not cause particularly coarse phase separation and has excellent low temperature properties and mechanical properties is selected. This optimum molecular weight range varies depending on the type of poly(alkylene oxide) glycol. For example, in the case of poly(tetramethylene oxide) glycol, it is 500 to 3000, particularly preferably 500 to 25
00 molecular weight range is used.

Examples of dicarboxylic acids having 4 to 20 carbon atoms as component (C) constituting the polyether ester amide include terephthalic acid, isophthalic acid, naphthalene-2,6-dicarboxylic acid, naphthalene-2,7-dicarboxylic acid, diphenyl Aromatic dicarboxylic acids such as -4,4-dicarboxylic acid, diphenoxyethane dicarboxylic acid, 3-sulfoisophthalic acid, fats such as succinic acid, oxalic acid, adipic acid, sebacic acid, dodecanedioic acid (decanedicarboxylic acid) and alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, and dicyclohexyl-4,4-dicarboxylic acid.

In order to exhibit the effects of the present invention most prominently, it is preferable that the copolymerization amount of the poly(alkylene oxide) glycol component in the polyether ester amide is 5 to 90% by weight. If the copolymerization amount is less than 5%, flexibility and elastic recovery properties are lost, whereas if it is more than 90% by weight, high temperature properties and mechanical properties are not sufficient, which is not preferable.

The method for polymerizing polyether ester amide is not particularly limited, and any known method can be used.

For example, an aminocarboxylic acid or lactam (component C) and a dicarboxylic acid (component C) are reacted to create a polyamide prepolymer having carboxyl groups at both end groups, and poly(alkylene oxide) glycol (component b) is added to this under reduced pressure. or the above (a), (b), (c)
) are charged into a reaction tank and reacted at high temperature in the presence or absence of water to produce a carboxyl-terminated polyamide prepolymer, and then polymerized under normal pressure or reduced pressure. a), (b), (c
) are simultaneously charged into a reaction tank, and after a preliminary reaction, polymerization is proceeded all at once under reduced pressure.

The polyamide elastomer compression molded product of the present invention compresses a polyamide elastomer block made of the above-mentioned polyether ester amide by at least 20% or more in a predetermined axial direction, then removes stress in the axial direction, and transforms the resulting block into a spring. , refers to molded products that are used in their original form for applications such as cushioning materials, pads, and shock absorbers, or molded products that are cut into the desired shape such as springs, cushion materials, pads, and shock absorbers. .

First, polyamide elastomer blocks are manufactured by injection molding polyamide elastomer into block-shaped bodies;
A method of cutting a rod-shaped body obtained by extrusion molding polyamide elastomer into a block-shaped body, a method of injecting molten polyamide elastomer polymer into a mold and cooling it to form a block-shaped body, or a method of molding polyamide elastomer into a metal mold. Methods such as inserting pellets into a mold, heating and pressurizing the mold to melt the polymer, and then cooling it to form a block are adopted, but from the viewpoint of productivity, injection molding methods and methods of cutting extrusion molded products are preferably used. be done.

The method of compressing the polyamide elastomer block obtained as described above by 20% or more in a predetermined axial direction is not particularly limited. A method of compressing the entire surface by applying stress in the axial direction, a method of compressing the center of one surface by applying stress in the axial direction, a method of applying stress in the axial direction to the outer periphery of one surface, When manufacturing a block by pouring molten polyamide elastomer polymer into a mold, methods such as applying external pressure to the outside of the polymer during the solidification process are used to compress it.

In the present invention, the effects of the present invention are further improved by heat-treating the polyamide elastomer block prior to compression. In other words, heat treatment alleviates the distortion remaining in the polyamide elastomer block during molding, increases the degree of crystallinity of the polyamide hard block that makes up the polyamide elastomer, and strengthens the physical crosslinking of the polyamide elastomer, making it compression permanent. It is thought that the rubber properties, typified by strain, are improved.

This polyamide elastomer block is heat treated in air,
This may be carried out in either an inert gas atmosphere or a vacuum atmosphere, but the temperature and time to be employed vary depending on the polyamide elastomer used.
) In polyamide elastomers containing a relatively large amount of the polyamide component, for example, containing 50% by weight or more, the polyamide elastomer may be heated at any temperature within the temperature range of 60 to 180°C, and from 5 to 20°C.
For polyamide elastomers containing 50% by weight or less of the polyamide component (a), heat treatment for 5 to 150 hours at any temperature in the temperature range of 50 to 160°C is used. Any length of heat treatment may be employed.

The amide elastomer of the present invention may contain antioxidants such as hindered phenol compounds, phosphite compounds, and thioether compounds, and ultraviolet stabilizers such as benzophenone light absorbers and hindered amine light stabilizers, as long as they do not impair the purpose of the present invention. , hydrolysis resistance improvers, colorants such as pigments and dyes, antistatic agents, conductive agents, flame retardants, glass fibers,
Fibrous reinforcing agents such as carbon fiber, aramid fiber, potassium titanate fiber, wollastenite, asbestos, calcium carbonate, barium sulfate, clay, titanium oxide, silicon oxide,
Fillers such as glass peas, metal stearates, montanic acid waxes, lubricants such as ethylene bis stearylamide, mold release agents, nucleating agents such as talc, mica powder, metal carboxylates, plasticizers, adhesives, etc. can contain.

The polyamide elastomer compression molded product of the present invention has excellent friction/abrasion resistance and compression set, so it is used for applications such as springs, cushioning materials, pads, and shock absorbing materials.
Depending on the purpose, the polyamide elastomer compression molded product may be used alone or in combination, and there is no particular limitation.

Margin below <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 means 0.0% when 0-chlorophenol is used as a solvent.
This is a value measured at 25°C for a 5% polymer solution.

Polymerization of Reference Example Polyamide Elastomer (A-1') 81.9 parts of ω-aminododecanoic acid, 6.8 parts of dodecanedioic acid and 19.3 parts of poly(tetramethylene oxide) glycol having a number average molecular weight of 650 were mixed with Irganox 109B ( The mixture was charged into a reaction vessel equipped with a helical ribbon stirring blade together with 0.5 part of a hindered phenolic antioxidant (manufactured by Ciba Geigy), purged with nitrogen, and heated and stirred at 260°C for 1 hour under normal pressure to form a homogeneous transparent solution. Antimony trioxide catalyst 0.01
! 5 parts, monobutyl monohydroxytin oxide catalyst 0
．． 0.015 parts, and 0.005 parts of phosphoric acid as a color inhibitor.
0.6 m in 1 hour according to the vacuum program.
The pressure was set at mHg. After the reaction was carried out under these conditions for 3.0 hours, the reaction vessel was pressurized with nitrogen gas and discharged into water in a gut shape to obtain pellets.

The relative viscosity of the obtained polyamide elastomer (A-1) was 2.01, and the crystal melting point was 167°C as measured by differential scanning calorimeter (DSC).

Polymerization of polyamide elastomer (A-2) 49.1 parts of ω-aminododecanoic acid, 7.9 parts of terephthalic acid, 48.8 parts of poly(tetramethylene oxide) glycol having a number average molecular weight of 1020, Irganox 109B 0.5 part, antimony trioxide 0.015 part, monobutyl monohydroxytin oxide 0.015 part and phosphoric acid 0.00 part
Polyamide elastomer (A-2) having a relative viscosity of 2.11 and a crystal melting point of 154°C was obtained by polymerizing 5 parts under the same conditions as polyamide elastomer (A-1).

Polymerization of polyamide elastomer (A-3) 127.3 parts of ω-aminododecane, 5.7 parts of terephthalic acid, 70.5 parts of poly(tetramethylene oxide) glycol with a number average molecular weight of 2060, 0.5 parts of Irganox 1098 ,
0.015 parts of antimony trioxide, 0.015 parts of monobutyl monohydroxytin oxide, and 0.00 parts of phosphoric acid.
Polyamide elastomer (A-1') was polymerized from 5 parts under the same conditions as polyamide elastomer (A-1'), and the relative viscosity was 2.10. A polyamide elastomer (A-3) having a crystal melting point of 145°C was obtained.

Polyamide elastomer (44°9 parts of polymerized undecamethylene diamine adipate of A-0,
12.8 parts of terephthalic acid, 50.0 parts of poly(tetramethylene oxide) glycol with a number average molecular weight of 650, 5 parts of Irganox 1098 0°, 0 antimony trioxide
．． 015 parts, monobutyl monohydroxytin oxide 0
．． Polyamide elastomer (A-1) was polymerized from 0.015 parts of phosphoric acid and 0.005 parts of phosphoric acid under the same conditions as polyamide elastomer (A-1), and the relative viscosity was 1.
゜981. Polyamide elastomer with crystal melting point of 209℃ (
A-4) was obtained.

Example 1 Polyamide elastomer A-1, A-2 obtained in Reference Example
, A-3, and A-4 using an injection molding machine with an injection capacity of 5 ounces, the molding temperature was set to the crystal melting point of each amide elastomer +25°C, the mold temperature was 40°C, and the injection/cooling time was 20/
A test piece for compression set measurement as described in ASTM D395 method was molded.

The compression set measurement test pieces of each of the obtained amide elastomers were heat treated in air at a temperature of 100° C. for 60 hours. The heat-treated compression set measurement test piece was compressed by 30% using a press, held for 2 minutes, and then the stress was removed. Next, for each of the obtained amide elastomer compression molded products, the compression set was measured according to the ASTM 0395 method, and the specific wear amount was measured using a precious wood type abrasion tester under the following conditions.

Load: 10Kg Surface pressure: 10Kg/cm2 Sliding speed: 27m/2 minutes Sliding distance: 1.6Km Mating material = fJ4 material S-45C Circumferential distance: 6.8cm Contact area: 1cm2 In addition, the hardness of each test piece was determined by ASTM Measured according to D2240.

The results are shown in Table 1, which also shows the measurement results of samples that were not subjected to compression for comparison.

It is clear from Table 1 that the compression molded products of the present invention have excellent compression set and wear resistance.

Example 2 A heat-treated test piece for compression set measurement of polyamide elastomer 8-1 obtained in Example 1 was heated in the same manner as in Example 1.
．． Samples compressed by 10, 20, 40, and 60% were prepared, and the compression set and specific wear amount were measured in the same manner as in Example 1.

The results are shown in Table 2.

It is clear from Table 2 that the compression molded products of the present invention have excellent compression set properties and abrasion resistance.

191 Example 3 A test piece for compression set measurement of the polyamide elastomer A-2 obtained in Example 1 was placed in an oven at 120°C and heat treated in air for 10,30,80,150 hours. , and compressed by 30% in the same manner as in Example 1, and the compression set and specific wear amount were measured. The results are shown in Table 3.

It is clear from Table 3 that the effects of the present invention are further improved by heat treatment.

Example 4 Polyamide elastomer A-3 was extruded at a temperature of 150° C. using an extrusion molding machine having a 40 mm screw to form a round bar with a diameter of 40 mmφ. This round bar was cut into a length of 3 cm to create a disk-shaped test piece.

The obtained test piece was heat treated in an air oven set at 80°C for 50 hours, and then compressed into a compression molded product in the same manner as in Example 1, and the compression set property and specific wear amount were measured. Result, compression set (25% deformation, 70°C x 22 hours)
26%, and the specific wear amount was 1.7 mg/Km-Kg, which were good values.

Example 5 Inner diameter 100 heated to 200°C with an aluminum block heater
Approximately 32 mm of polyamide elastomer A-2 is placed in a cylinder of mmφ.
0g was poured into the cylinder, compressed from both sides of the cylinder into a disk with an outer diameter of 100mmφ at a pressure of 200kg/cm2, and cooled to 1.
A disc of 00 mm x 4 amt was cast.

After heat treating the obtained disc in the same manner as in Example 1, the compression set of the compressed molded product (25% deformation, 70°C x 22 hours) was 25%, and the specific wear amount was 2.4 mg/Km・Kg, which was good. The results were shown.

Comparative Example 1 Polyester elastomer "Hytrel" 4056 sold by DuPont was molded in the same manner as in Example 1, except that the molding temperature was changed to 200°C, and after heat treatment, the compression set of the molded product (25 % deformation, 70°C x 22 hours) was 39%, and the specific wear amount was 9.1 mg/Km◆Kg, and compared to the polyamide elastomer A-2 of the present invention with the same hardness (see Table 1), the compression set was 39%. However, results were obtained in which both the specific wear amount and the specific wear amount were inferior.

<Effects of the Invention> As seen in Examples 1 to 5, it is clear that the polyamide elastomer compression molded product of the present invention exhibits excellent elastic recovery properties and abrasion resistance.

Claims (1)

[Claims] A method for manufacturing a polyamide elastomer compression molded article, which comprises applying sufficient axial stress to compressively deform a polyamide elastomer block by 20% or more in a predetermined axial length, and then removing the axial stress.