JP2000044768A - Highly slidable polyacetal resin composition and highly slidable molded article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a highly slidable resin compsn. which can give a molded article capable of retaining high friction and abrasion characteristics against both to metals and to resins for a long time by compounding a polyacetal resin with a specified amt. of zeolite. SOLUTION: This compsn. is prepd. by compounding 100 pts.wt. polyacetal resin with 0.1-20 pts.wt. zeolite and pref. further contains 0.01-5 pts.wt. sliding agent. The sliding agent further improves the friction and abrasion characteristics. Examples of the sliding agent are paraffin wax, polyethylene wax, an organosiloxane, a higher fatty acid ester, and a higher fatty acid metal salt. Both natural zeolite and synthetic zeolite can be used, examples being faujasite, mordenite, zeolite L, and zeolite Y. When the sliding agent is added to the compsn., the agent is pref. impregnated into zeolite before being mixed into a polyacetal resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a highly slidable polyacetal resin composition and a highly slidable molded product. More specifically, a high slidable polyacetal resin composition suitable as a raw material for molding a molded article that comes into contact with a metal or a resin and slid simultaneously with each other, and for both the metal and the resin, The present invention relates to a highly slidable polyacetal resin molded product that maintains high friction and wear characteristics for a long time.

[0002]

2. Description of the Related Art Polyacetal resin has excellent mechanical strength, fatigue resistance, and electrical characteristics. Therefore, it is used as an engineering resin for molding gears, bearings, other mechanical parts, automobile parts, home electric parts, etc. Is widely used as a raw material resin. In addition, polyacetal resin is also excellent in friction and wear characteristics, and there are many uses where the characteristics are utilized. However, recently, applications of polyacetal resins have been diversified, and higher functions have been demanded as compared with conventional ones.

[0003] The required high performance is, for example, in electric parts and the like, low friction and low resistance to both metal and resin.
It is desired to have a property that the low wear property can be maintained for a longer time than before. These characteristics are
The friction and wear characteristics inherent in the polyacetal resin are not sufficient, and the addition of a general additive to the polyacetal resin cannot cope with the situation.

[0004] As an example of improving the low friction and low wear characteristics of a polyacetal resin, a technique described in Japanese Patent Application Laid-Open No. 63-297453 has been proposed. According to this publication, a method is employed in which a silicone oil and a lubricant are added to a polyacetal resin. However,
According to experiments by the inventors, according to this method, when sliding performance capable of simultaneously withstanding metal and resin is required, it is insufficient to satisfy both simultaneously, and when sliding is used for a long time, It was found that there was a problem that the dynamic characteristics were reduced.

[0005]

SUMMARY OF THE INVENTION In view of the above situation, the present inventors have developed a highly slidable polyacetal resin which maintains high friction and wear characteristics over a long period of time for both metals and resins. As a result of intensive studies for the purpose of providing a composition and a molded article having high slidability, the present invention has been achieved. The objects of the present invention are as follows. 1. An object of the present invention is to provide a highly slidable polyacetal resin composition capable of obtaining a molded article having high friction and wear characteristics over a long period of time for both metals and resins. 2. To provide a high slidability molded product that maintains high friction and wear characteristics for both metal and resin for a long time.

[0006]

In order to solve the above-mentioned problems, the present invention is characterized in that 0.1 to 20 parts by weight of zeolite is blended with respect to 100 parts by weight of a polyacetal resin. Water soluble polyacetal resin composition,
In addition, the present invention provides a molded article made of a highly slidable polyacetal resin, characterized by being molded from such a polyacetal resin composition.

Further, according to the present invention, the polyacetal resin 1
A high-sliding polyacetal resin composition, characterized in that 0.1 to 20 parts by weight of zeolite and 0.01 to 5 parts by weight of a sliding agent are compounded with respect to 00 parts by weight. A highly slidable polyacetal resin molded article characterized by being molded from a polyacetal resin composition.

In the present invention, the polyacetal resin is
A high molecular compound having an oxymethylene group (—CH ₂ O—) as a main structural unit, a polyoxymethylene homopolymer, a copolymer containing a small amount of another structural unit other than the oxymethylene group (including a block copolymer), and And terpolymers, and may have a branched or crosslinked structure. The molecular weight of these polymers is not particularly limited as long as it can be used as a molding material.

Zeolite has the following general formula:
^{l (M 1, M 2)} O · Al 2 O 3 · nSiO 2 · mH 2 O,
(Wherein, M ¹ represents an alkali metal and M ² represents an alkaline earth metal), which is a stable porous crystal three-dimensionally bonded to natural aluminosilicate. There are zeolites and synthetic zeolites. The zeolite that can be used in the present invention may be any of a natural zeolite and a synthetic zeolite, and some or all of the ion-exchangeable metal ions represented by the above general formula are replaced with other metal ions and / or ammonium. Also includes zeolites that have been exchanged for ions. Specific examples include faujasite, mordenite, ferrierite, erionite, zeolite β, zeolite L, zeolite Y, zeolite Ω, offretite, MFI zeolite, and the like.

The amount of these zeolites to be added to the base resin is selected from the range of 0.1 to 20 parts by weight based on 100 parts by weight of the polyacetal resin as the base resin. If the amount of zeolite is less than 0.1 part by weight, the molded article cannot exhibit a favorable sliding effect, and if it exceeds 20 parts by weight, on the contrary, the wear resistance of the molded article decreases. Any of these is not preferred because thermal stability is reduced.

The highly slidable polyacetal resin composition according to the present invention has excellent friction and abrasion characteristics, and for the purpose of further improving these characteristics, the above-mentioned highly slidable polyacetal resin mixed with zeolite. A sliding agent can be further added to the composition. The sliding agent that can be blended is a sliding agent generally used for polyacetal resins, and examples thereof include paraffin wax, polyethylene wax, organosiloxane, higher fatty acid ester, and higher fatty acid metal salt.

The paraffin wax as a sliding agent has n
-A petroleum wax containing paraffin as a main component, and among them, those having a melt viscosity at a temperature of 100 ° C of 0.1 poise or less and a melting point of 50 to 70 ° C are preferable.

[0013] Polyethylene wax as a sliding agent,
A low-molecular-weight polyethylene having an OH group at the end and having a wax-like appearance and having a molecular weight intermediate between paraffin and polyethylene for molding. Specific examples include low-molecular-weight polyethylene, low-molecular-weight polyethylene copolymer, and modified polyethylene wax of a type in which a polar group is introduced by oxidatively or acid-modifying them. Its number average molecular weight is preferably 500-1500
0, more preferably 1,000 to 10,000.

Organosiloxanes as sliding agents include:
Examples thereof include silicone oil having properties such as oil, rubber, and resin, silicone rubber, and silicone resin, and further include silicone grease to which metal soap or the like is added. Specific examples of the organosiloxane include, for example, polydimethylsiloxane, an organosiloxane in which a part of the methyl group of the polydimethylsiloxane is substituted with a phenyl group, and a part of the methyl group of the polydimethylsiloxane in which hydrogen or C2 or more is used. An organosiloxane substituted with an alkyl group,
Organosiloxane in which part of the methyl group in polydimethylsiloxane is substituted with a halogenated phenyl group, organosiloxane in which part of the methyl group in polydimethylsiloxane is substituted with a fluoroester group, epoxy-modified organosiloxane, amino-modified organosiloxane , An alcohol-modified organosiloxane, an alkylaralkylorganosiloxane, a polyether-modified organosiloxane, and the like.

The higher fatty acid esters as sliding agents include higher fatty acids such as stearic acid, oleic acid, octanoic acid, lauric acid, ricinoleic acid, behenic acid, octyl alcohol, myristyl alcohol, stearyl alcohol, behenyl alcohol, glycols and the like. , Glycerin, pentaerythritol and the like and esters with monohydric or polyhydric alcohols. Among them, stearyl stearate and behenic acid monoglyceride are preferably used.

The metal salts of higher fatty acids as sliding agents include higher fatty acids such as stearic acid, 12-hydroxystearic acid, oleic acid, octanoic acid, lauric acid, behenic acid, ricinoleic acid, zinc and calcium. , Magnesium, nickel, copper and the like.

These sliding agents can be used alone or in combination of two or more. The blending amount of the sliding agent in the polyacetal resin of the substrate is preferably selected in the range of 0.01 to 5 parts by weight based on 100 parts by weight of the resin of the substrate.
If the amount is less than 0.01 part by weight, the sliding effect cannot be further improved.If the amount is more than 5 parts by weight, bleed-out from the molded article is liable to occur, causing mold contamination. Not preferred.

In preparing the highly slidable polyacetal resin composition according to the present invention, the compounds are directly compounded and added to the base polyacetal resin, melt-kneaded and uniformly dispersed in the base resin. By doing so, the desired effect can be exhibited. The method of kneading the compounds into the base resin can be a conventionally known method.
The polyacetal resin can be prepared by adding the above-mentioned substances to the polyacetal resin, and if necessary, adding other components, and then heating and melting and kneading. For example, after the base polyacetal resin and the compounds are uniformly mixed in advance by a mixer such as a tumbler or a Henschel mixer, the mixture is supplied to a single-screw or twin-screw extruder, melt-kneaded, and produced as pellets. . At this time, the compounds may be added simultaneously or separately.

When a composition is prepared by further adding a sliding agent to the above-mentioned highly slidable polyacetal resin composition containing zeolite, the sliding agent is impregnated in the zeolite in advance, and then the polyacetal of the substrate is prepared. According to the method of kneading with the resin, the desired effect can be more remarkably exhibited. The method of impregnating the zeolite with the above-mentioned sliding agent includes: (a) a method of impregnating a desired amount of the sliding agent and zeolite by heating to a temperature equal to or higher than the melting point of the sliding agent, and (b) a good solvent of the sliding agent. A method in which the above-mentioned sliding agent and zeolite are mixed and kneaded into a polyacetal resin, (c) the above-mentioned sliding agent and zeolite are mixed in a good solvent for the sliding agent, and the solvent is removed by evaporation. And a method of kneading with the polyacetal resin of the base.

The highly slidable polyacetal resin composition according to the present invention may contain various known resin additives which impart desired properties according to the purpose, such as heat stabilizers, antioxidants, dyes, pigments, and the like. Flame retardant, release agent, weathering agent, ultraviolet absorber, antistatic agent, conductive agent, nucleating agent, filler, such as glass fiber, glass beads, glass flake, talc, calcium carbonate, mica, carbon fiber, etc. can do.

In order to produce a highly slidable molded article from the highly slidable polyacetal resin composition according to the present invention, a molding method conventionally known as a thermoplastic resin molding technique may be used. Specific examples include an injection molding method, an extrusion molding method, a blow molding method, a compression molding method, and a transfer molding method. Examples of the molded article include mechanical parts, automobile parts, home electric parts and the like, and among them, sliding parts such as gears and bearings are preferable.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following description unless it exceeds the gist.

[0023]

EXAMPLES The polyacetal resin of the substrate used in the examples described below was a polyacetal copolymer (produced by Mitsubishi Engineering-Plastics Corporation, trade name: Iupital F2)
0-03, hereinafter abbreviated as "F20-03"), and polyacetal homopolymer (manufactured by Asahi Kasei Corporation, trade name: Tenac 4010, hereinafter abbreviated as "4010"). The zeolites used are zeolite L (trade name: HSZ-500, hereinafter abbreviated as “L”) and zeolite Y (trade name: HSZ-300, abbreviated as “Y”) manufactured by Tosoh Corporation. The paraffin wax used was manufactured by Nippon Seiro Co., Ltd. (trade name: 155), the polyethylene wax was manufactured by Mitsui Chemicals, Inc. (trade name: High Wax 800P), and the organosiloxane was manufactured by Shin-Etsu Chemical Co., Ltd. (trade name) : Shin-Etsu Silicone KF96)

Examples 1 to 8 Zeolites of the type shown in Table 1 were weighed against the base polyacetal resin in the amounts shown in the table and mixed with a tumbler type blender. Next, the obtained mixture was 30 mmφ.
The mixture was melt-kneaded with a twin-screw extruder and pelletized to obtain pellets of a desired highly slidable polyacetal resin composition.
Using the obtained pellet as a raw material, a test ring for evaluating slidability (outer diameter 25.6 mm, inner diameter 20.0
mm, height 15.0 mm).

With respect to the obtained test ring for evaluating slidability,
Using a thrust-type (Suzuki-type) friction / abrasion tester (EFM-3-E type, manufactured by Orientec) under the following conditions, that is, the load was 3 kg, the number of revolutions was 250 rpm, and (i) When the mating material is resin for friction and wear, F20-
In the case of using a molded product made of No. 03 and (ii) when the mating material is used for friction and wear, a method using a cutting steel ring (S45C) whose sliding surface is polished with an abrasive of # 1200 is used. Under these conditions, the friction coefficient and the wear amount of the above-described ring for evaluating slidability were measured.

The coefficient of friction and the amount of wear of the test ring for evaluating slidability were evaluated by the following methods. (a) Coefficient of friction (hereinafter abbreviated as μ): The coefficient of friction (continuously slid under the above-mentioned conditions) at each point in time after 1 minute, 1 hour, 24 hours, 2 weeks μ) was calculated from the following equation: μ = F / N.
In this equation, F is a friction force (unit: kgf), and N is a load (unit: kgf). (b) Abrasion amount: After sliding continuously for two weeks under the above conditions, the weight change of the test ring for evaluating slidability was measured. The amount of wear was calculated from the weight before the test minus the weight after the test, and the evaluation results are shown in Table 1.

[0027]

[Table 1]

[Examples 9 to 18] Pellets were formed in the same manner as in Example 1. Using the obtained pellets as a raw material, a slidability evaluation test ring (having the same shape as that of the example) was formed by an injection molding machine in the same manner as in Example 1, and the slidability evaluation test ring was obtained. The coefficient of friction and the amount of wear were measured in the same manner as in the examples. The evaluation results are shown in Table-2.

[0029]

[Table 2]

[Examples 19 to 27] After impregnating 5 parts by weight of zeolite L with the sliding agents described in Table 3 in an amount shown in the same table with respect to 100 parts by weight of polyacetal resin, 5 parts by weight of the sliding agent-impregnated zeolite L was mixed with 100 parts by weight of a polyacetal resin (F20-03), and pelletized in the same manner as in Example 1.
Using the obtained pellets as a raw material, a slidability evaluation test ring (having the same shape as that of the example) was formed by an injection molding machine in the same manner as in Example 1, and the slidability evaluation test ring was obtained. The coefficient of friction and the amount of wear were measured in the same manner as in the examples. Table 3 shows the evaluation results.

[0031]

[Table 3]

[Comparative Examples 1 to 11] The base polyacetal resin used in the comparative example was F20-03. No zeolite was added to this base resin, and only the sliding agents shown in Table 4 were used. The amounts shown in the same table were blended, and pelletized in the same manner as in the examples. Using the obtained pellets as a raw material, a test ring for evaluating slidability (the shape is the same as that of the example) was formed by an injection molding machine in the same manner as in the example. The coefficient of friction and the amount of wear were measured in the same manner as in the examples. The evaluation results are shown in Table-4.

[0033]

[Table 4]

The following is clear from Tables 1 to 4. (1) Compositions in which only zeolite was blended with the base polyacetal resin (see Examples 1 to 8) were those containing only the polyacetal resin (Comparative Example 1) and those containing only the sliding agent in the polyacetal resin ( Comparative Examples 2 to 11)
In comparison with the above, it exhibits high friction and wear characteristics over a long period of time. (2) In the case where zeolite and a sliding agent are mixed and used in combination with the base polyacetal resin (see Examples 9 to 18),
Higher friction and wear characteristics are remarkably exhibited over a long time than those obtained by blending only zeolite with polyacetal resin. (3) When a sliding agent is blended with the polyacetal resin of the base, the one prepared by impregnating the sliding agent into zeolite in advance (see Examples 19 to 27) is used.
It exhibits even higher friction and wear characteristics than the case of Example 18.

[0035]

The present invention has been described in detail above, has the following advantageous effects, and is extremely valuable in industrial use. 1. A polyacetal resin composition containing only zeolite with a polyacetal resin is an excellent resin composition that can provide a molded product that maintains high friction and wear properties for a long time with respect to both metal and resin. is there. Although the mechanism for exhibiting this characteristic is not clear, it is assumed that the presence of zeolite increases the surface hardness and thereby improves the abrasion. 2. A polyacetal resin composition in which zeolite and a sliding agent are used in combination with a polyacetal resin exhibits remarkably high friction and wear properties over a longer period of time than when only a polyacetal resin is used. Although the mechanism of exhibiting this property is not clear, the specific adsorption property of zeolite adsorbs and retains the sliding agent, and the molded product obtained from the resin composition containing the same has significantly improved friction and wear properties. It is presumed that this characteristic is maintained for a long time. 3. When a zeolite and a sliding agent are mixed and used together with the polyacetal resin, if the zeolite is impregnated with the sliding agent and then mixed, the friction and wear characteristics of the molded product are further remarkably improved. 4. The high slidability polyacetal resin molded product according to the present invention has a small friction coefficient when used as a sliding part,
Moreover, the amount of wear is small, and it is extremely useful as a mechanical part, an automobile part, a home electric appliance part and the like.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 91:06) (C08L 59/00 23:04) (C08L 59/00 83:04) (72) Invention Person Toshikatsu Kawada 5-6-2 Higashi-Hachiman, Hiratsuka-shi, Kanagawa Prefecture Inside the Engineering Center of Mitsubishi Engineering-Plastics Co., Ltd. (72) Inventor Hiroaki Sato 5-6-1-2 Higashi-Hachiman, Hiratsuka-shi, Kanagawa Prefecture Mitsubishi Engineering-Plastics Corporation F-term in the Technical Center of the company (reference) 4J002 AE042 BB032 CB001 CP032 DJ006 EG027 EG037 EH037 FD016

Claims (8)

[Claims] 1. A highly slidable polyacetal resin composition comprising 0.1 to 20 parts by weight of zeolite with respect to 100 parts by weight of a polyacetal resin. 2. A polyacetal resin of 100 parts by weight, zeolite of 0.1 to 20 parts by weight and a sliding agent of 0.02 parts by weight.
A highly slidable polyacetal resin composition characterized by being mixed with 1 to 5 parts by weight. 3. The highly slidable polyacetal according to claim 2, wherein the sliding agent is at least one selected from the group consisting of paraffin wax, polyethylene wax, organosiloxane, higher fatty acid ester, and higher fatty acid metal salt. Resin composition. 4. The highly slidable polyacetal resin composition according to claim 2, wherein a part or all of the sliding agent is impregnated with zeolite and blended. 5. A highly slidable polyacetal resin, characterized by being molded from a polyacetal resin composition containing 0.1 to 20 parts by weight of zeolite with respect to 100 parts by weight of the polyacetal resin. Molding. 6. A polyacetal resin of 100 parts by weight, 0.1 to 20 parts by weight of zeolite and 0.02 parts by weight of a sliding agent.
A molded article made of a highly slidable polyacetal resin, characterized in that it is molded from a polyacetal resin composition containing 1 to 5 parts by weight. 7. The highly slidable polyacetal according to claim 6, wherein the sliding agent is at least one selected from the group consisting of paraffin wax, polyethylene wax, organosiloxane, higher fatty acid ester, and higher fatty acid metal salt. Molded product made of resin composition. 8. The molded article made of a highly slidable polyacetal resin composition according to claim 6, wherein a part or all of the sliding agent is impregnated into zeolite and blended.