JPH0519887B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Application Field> The present invention relates to a method for manufacturing a polyamide elastomer compression molded article having excellent compression set properties and abrasion resistance.
More specifically, when the compression set property is improved and it is used for compression springs and compression cushion materials,
The present invention relates to a method for producing a compression molded polyamide elastomer product that exhibits excellent elastic recovery and wear resistance. <Prior Art> Polyether ester amide-based polyamide elastomers having polyamide repeating units, polyether repeating units, and ester bonds in the polymer main chain are known as polymers that exhibit rubber-like elasticity.
Applications are expanding to include sports equipment, precision machinery parts, mechanical mechanism parts, electrical/electronic parts, automobile parts, textiles, and foils. On the other hand, when used in applications such as cushioning materials for shock absorption or compression springs, materials with excellent compression set and abrasion resistance are generally used in addition to the balance of chemical and physical properties. is required. Elastomers have traditionally been widely used as compression springs. In particular, in Japanese Patent Application Laid-open No. 55-51542,
A method has been proposed 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 with a large deformation, there are problems such as making an abnormal noise or causing the spring to become eccentric and lose 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 burrs, sink marks, etc. during molding. Large permanent deformation occurs, which limits its use in applications that require spring action. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a method for manufacturing a compression molded polyamide elastomer product that has excellent abrasion resistance and a large spring action. <Means for Solving the Problems> As a result of intensive studies to improve the above-mentioned problems of polyamide elastomers, the present inventors have found that by pre-compressing polyamide elastomer blocks, the problems of conventional polyester elastomers can be solved. The inventors have discovered that it is possible to obtain a polyamide elastomer molded article with excellent abrasion resistance and compression set, 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 diamine and dicarboxylic acid having 6 or more carbon atoms (a), poly(alkylene oxide) having a number average molecular weight of 300 to 600. Preferred are polyetheresteramides composed of glycol (b) and dicarboxylic acid (c) having 4 to 20 carbon atoms. The aminocarboxylic acids or lactams having 6 or more carbon atoms, or the salts of diamines and dicarboxylic acids having 6 or more carbon atoms, which are the component (a) that constitutes this polyether ester amide, include ω-aminocaproic acid, ω- Aminoenanthic acid, ω-aminocaprylic acid, ω-aminopelargonic acid, ω-aminocapric acid, 11-aminoundecanoic acid, 12-
Aminocarboxylic acids such as aminododecanoic acid or lactams such as caprolactam, enantholactam, capryllactam, lacloractam, and hexamethylenediamine-adipate, hexamethylenediamine-sebacate, hexamethylenediamine-isophthalate, undecamethylene Examples include salts of diamines and dicarboxylic acids such as diamine-adipate salts. 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. Further, as the poly(alkylene oxide) glycol having a number average molecular weight of 300 to 6,000, which is the component (b) constituting the polyether ester amide of the present invention, poly(ethylene oxide) glycol, poly(1,
2- and 1,3-propylene 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. Poly(tetramethylene oxide) glycol is particularly preferably used because of the properties of polyether ester amide, such as water resistance, mechanical strength, and elastic recovery. The number average molecular weight of poly(alkylene oxide) glycol is 300
-6000, but a molecular weight range that does not cause coarse phase separation and has excellent low-temperature properties and mechanical properties is selected. This optimum molecular weight range differs depending on the type of poly(alkylene oxide) glycol. For example, in the case of poly(tetramethylene oxide) glycol, those having a molecular weight in the range of 500 to 3,000, particularly preferably 500 to 2,500 are used. (c) Constituting the above polyether ester amide
The component dicarboxylic acids having 4 to 20 carbon atoms include terephthalic acid, isophthalic acid, and naphthalene.
Aromatic dicarboxylic acids such as 2,6-dicarboxylic acid, naphthalene-2,7-dicarboxylic acid, diphenyl-4,4'-dicarboxylic acid, diphenoxyethanedicarboxylic acid, 3-sulfoisophthalic acid, succinic acid, sulfuric acid, etc. acids, aliphatic dicarboxylic acids such as adipic acid, sebacic acid, dodecanedioic acid (decanedicarboxylic acid), and 1,4-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, dicyclohexyl-4,4'-dicarboxylic acid. Alicyclic dicarboxylic acids can be mentioned. In order for the effects of the present invention to be most clearly demonstrated,
The amount of copolymerization of poly(alkylene oxide) glycol component in polyether ester amide is 5 to 90.
Preferably, it is expressed as % by weight. If the copolymerization amount is less than 5%, flexibility and elastic recovery properties will be lost, and if it is more than 90% by weight, the high-humidity properties and mechanical properties will not be sufficient. 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 a) 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. Alternatively, each of the components (a), (b), and (c) above is charged into a reaction tank and reacted at high temperature in the presence or absence of water to produce a polyamide prepolymer with carboxyl terminal groups. A method in which the above components (a), (b), and (c) are simultaneously charged into a reaction tank and, after a preliminary reaction, the polymerization is proceeded all at once under reduced pressure. etc. will be adopted. The polyamide elastomer compression molded product of the present invention is
The polyamide elastomer block made of the aforementioned polyether ester amide is compressed by at least 20% or more in a predetermined axial direction, and then the stress is removed in this axial direction, and the resulting block is used as a spring, cushion material, batt, shock absorbing material, etc. This refers to molded products that are used in their original form for applications, or molded products that have been cut into the desired shape, such as springs, cushion materials, pads, and shock absorbing materials. First, the production of polyamide elastomer blocks is
A method of injection molding polyamide elastomer to form a block-like object, a method of extruding polyamide elastomer and cutting a rod-like object to form a block-like object, a method of injecting molten polyamide elastomer into a mold and then cooling it to form a block. method of making it into a shape,
Alternatively, a method is adopted in which polyamide elastomer pellets are placed in a metal mold, the mold is heated and pressurized, the polymer is melted, and then cooled to form a block-like body.However, from the viewpoint of productivity, injection molding, extrusion, etc. A method of cutting the molded article is preferably used.
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 applying stress in the axial direction to the center of one surface and compressing it, a method of applying stress in the axial direction to the outer periphery of one surface and compressing it. When polyamide elastomer polymer is poured into a mold to manufacture a block, methods such as applying external pressure to the outside of the polymer during the solidification process to compress it are employed. In the present invention, the effects of the present invention are further improved by heat-treating the polyamide elastomer block prior to compression. That is, 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 heat treatment of the polyamide elastomer block may be carried out in any atmosphere such as air, inert gas or vacuum, but the temperature and time employed will vary depending on the polyamide elastomer used. It contains a relatively large amount of the polyamide component (a) that constitutes the polyether ester amide that is the polyamide elastomer of the present invention. For example, for polyamide elastomers containing 50% by weight or more, heat treatment at any temperature in the temperature range of 60 to 180°C for any period of time from 5 to 200 hours is adopted; For the content of polyamide elastomer, heat treatment at any temperature in the temperature range of 50 to 160° C. and for any period of time from 5 to 150 hours is employed. The amide elastomer of the present invention includes 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, carbon fibers, aramid fibers, potassium titanate fibers, wollastenite, fibrous reinforcing agents such as asbestos, calcium carbonate, barium sulfate, clay, titanium oxide, silicon oxide, glass Fillers such as beads, 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. It can contain. The polyamide elastomer compression molded product of the present invention is
It has excellent friction/abrasion resistance and compression set, so
It is used for applications such as springs, cushion materials, pads, and shock absorbing materials. Depending on the purpose, polyamide elastomer compression molded products may be used alone or in combination, but there are no particular limitations. It's not a thing. <Example> The effects of the present invention will be explained below with reference to 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 o-chlorophenol as a solvent. Reference example Polymerization of polyamide elastomer (A-1) ω-aminododecanoic acid 81.9 parts, dodecanedioic acid
6.8 parts and 19.3 parts of poly(tetramethylene oxide) glycol with a number average molecular weight of 650 were charged together with 0.5 parts of Irganox 1098 (hindered phenolic antioxidant manufactured by Ciba Geigy) into a reaction vessel equipped with a helical ribbon stirring blade, and the mixture was purged with nitrogen. After heating and stirring for 1 hour at 260°C under normal pressure to obtain a homogeneous transparent solution, 0.015 parts of antimony trioxide catalyst, 0.015 parts of monobutyl monohydroxytin oxide catalyst,
and 0.005 part of phosphoric acid as a coloring inhibitor,
A pressure of 0.6 mmHg was achieved in 1 hour according to the vacuum program. After the reaction was carried out under these conditions for 3.0 hours, the reaction vessel was discharged and cut into water in a gut shape under pressure with nitrogen gas 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 calorimetry (DSC). Polymerization of polyamide elastomer (A-2) 49.1 parts of ω-aminododecanoic acid, terephthalic acid
Polyamide elastomer (A
Polyamide elastomer (A-2) polymerized under the same conditions as -1), with a relative viscosity of 2.11 and a crystalline melting point of 154°C.
I got it. Polymerization of polyamide elastomer (A-3) 27.3 parts of ω-aminododecanoic acid, terephthalic acid
Polyamide elastomer (A
Polyamide elastomer (A-3) polymerized under the same conditions as -1), with a relative viscosity of 2.10 and a crystal melting point of 145°C.
I got it. Polymerization of polyamide elastomer (A-4) Undecamethylenediamine-adipate 44.9
12.8 parts of terephthalic acid, 50.0 parts of poly(tetramethylene oxide) glycol with a number average molecular weight of 650.
part, Irganox 1098, 0.5 part, antimony trioxide 0.015 part, monobutyl monohydroxytin oxide 0.015 part and phosphoric acid 0.005 part under the same conditions as polyamide elastomer (A-1),
A polyamide elastomer (A-4) having a relative viscosity of 1.98 and a crystal melting point of 209°C was obtained. Example 1 Polyamide elastomer A obtained in Reference Example
1. A-2, A-3, and A-4 were molded using an injection molding machine with an injection capacity of 5 ounces, and the molding temperature was set to the crystal melting point of each amide elastomer +25°C and the mold temperature to 40°C.
°C, injection/cooling time set to 20/30 seconds, ASTM
A test piece for compression set measurement as described in the 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 compression set measurement test piece subjected to this heat treatment was compressed by 30% using a press machine, held for 2 minutes, and then the stress was removed. Each of the resulting amide elastomer compression molded articles was then tested according to the ASTM
The compression set was measured according to the D395 method, and the specific wear amount was measured using a Suzuki abrasion tester under the following conditions. Load: 10Kg Surface pressure: 10Kg/ ^cm 2Sliding speed: 27m/2 minutes Swivel distance: 1.6Km Mating material: Steel S-45C Circumferential distance: 6.8cm Contact area: 1cm ² Specific wear amount = Wear amount ( mg)/load (Kg) x wear distance (
Km) The hardness of each test piece was also measured according to ASTM 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 properties and wear resistance.

[Table] Example 2 Polyamide elastomer A- obtained in Example 1
Samples were prepared by compressing the heat-treated test piece for compression set measurement in Example 1 by 5, 10, 20, 40, and 60% in the same manner as in Example 1, and the compression set and specific wear were measured in the same manner as in Example 1. The amount was measured. 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.

[Table] Example 3 Polyamide elastomer A- obtained in Example 1
The test piece for compression set measurement in Example 2 was placed in an oven at 120°C, heat treated in air for 10, 30, 80, and 150 hours, and then compressed by 30% in the same manner as in Example 1. The amount of wear was 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.

[Table] Example 4 Using an extrusion molding machine with a screw of 40 mmφ, polyamide elastomer A-
3 was extrusion molded 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. Results of measurement of compression set and specific wear amount. , compression set (25% deformation, 70
℃ x 22 hours) 26%, and the specific wear amount was 1.7 mg/Km・Kg, which were good values. Example 5 Inner diameter heated to 200℃ with an aluminum heater
Polyamide elastomer A-2 in a 100mmφ cylinder
Put about 320g of this cylinder, and the outer diameter is 100mmφ from both sides of this cylinder.
The mixture was compressed into a disc with a pressure of 200 kg/cm ² , and then cooled and cast into a disc of 100 mmφ x 4 cmt. The obtained disk was heat treated in the same manner as in Example 1, and the compression set of the compressed molded product (25% deformation, 70℃ x 22
time) was 25% and the specific wear amount was 2.4mg/Km・Kg, showing good results. Comparative Example 1 Polyester elastomer “Hytrel” 4056 sold by DuPont was molded at a temperature of 200°C.
However, the compression set (25% deformation, 70℃ x 22 hours) of the molded product that was molded in the same manner as in Example 1, heat treated, and compressed was 39%, and the specific wear amount was 9.1 mg/
Km·Kg, and compared with the polyamide elastomer A-2 of the present invention having the same hardness (see Table 1), results were obtained that were inferior in both compression set and specific wear amount. <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] 1. A method for producing a polyamide elastomer compression molded product, 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 this axial stress.