WO2022168970A1

WO2022168970A1 - Resin composition and molded article

Info

Publication number: WO2022168970A1
Application number: PCT/JP2022/004608
Authority: WO
Inventors: 崇石井; 麻希子大島
Original assignee: 三菱エンジニアリングプラスチックス株式会社
Priority date: 2021-02-08
Filing date: 2022-02-07
Publication date: 2022-08-11
Also published as: CN117120541A; JPWO2022168970A1; KR20230144548A

Abstract

Provided are a resin composition and molded article having excellent slidability, high tensile fracture nominal strain, and excellent heat aging resistance. This resin composition includes, with respect to 100 parts by mass of polyacetal resin (A), 0.1-50 parts by mass of an acid-modified olefin polymer (B) having an acid value of 1.0-30.0 mgKOH/g, and 0.01-5 parts by mass of a compound (C) containing two or more primary amino groups and/or secondary amino groups in total, said compound being selected from a dihydrazone compound, dihydrazide compound, urea compound, and melamine compounds. The ratio (B)/(C) of the acid-modified olefin polymer (B) to the amino group-containing compound (C) is 20-200.

Description

Resin composition and molded product

The present invention relates to resin compositions and molded articles. In particular, the present invention relates to a resin composition and molded article containing a polyacetal resin and having excellent slidability.

Conventionally, the use of polyacetal resin for sliding members has been studied.
For example, Patent Document 1 discloses (A) 100 parts by mass of a polyacetal resin, (B) 0.01 parts by mass or more and 1 part by mass or less of a hindered phenolic antioxidant, and (C) 0.05 parts by mass of a nitrogen-containing compound. and (D) a modified olefin polymer obtained by modifying an olefin polymer with at least one selected from unsaturated carboxylic acids, acid anhydrides of unsaturated fatty acids, and derivatives thereof. 5 parts by mass or more and 10 parts by mass or less; and (F) 0.1 parts by mass or more of substantially cubic calcium carbonate having a BET specific surface area of 15 m ² /g or less, an average particle size of 50 nm or more and 200 nm or less, and an untreated surface. 20 parts by mass or less, (G) 0.1 parts by mass or more and 10 parts by mass or less of a partial ester of a polyhydric alcohol having a valence of 2 to 4, and (H) an alpha olefin oligomer of 0.1 parts by mass or more and 10 parts by mass or less. A polyacetal resin composition containing and is disclosed.

Further, in Patent Document 2, (A) polyacetal resin 100 parts by mass, (B) olefin polymer (B-1) unsaturated carboxylic acid and its acid anhydride and their derivatives (B-2) 0.5 to 100 parts by mass of a modified olefin polymer modified with at least one selected from the group consisting of (C) 0.1 to 20 parts by mass of an inorganic filler, blended and melt-kneaded into a polyacetal resin A composition is disclosed.

Furthermore, in Patent Document 3, (A) 100 parts by mass of polyacetal resin, (B) 0.1 to 50 parts by mass of olefin polymer, and (C) 0 polyethylene wax having an acid value of 1 mgKOH/g or more .1 to 15 parts by weight and (D) 0.05 to 20 parts by weight of calcium carbonate.

JP 2016-069451 A JP-A-10-130458 JP 2019-006974 A

As described above, a resin composition having excellent slidability using a polyacetal resin is known. However, in recent years, sliding members have diversified, and the required performance has also diversified, and a new resin composition having excellent slidability has been desired. In particular, depending on the application, high nominal strain at break and heat aging resistance are required.
An object of the present invention is to solve such problems, and an object thereof is to provide a resin composition and a molded article which are excellent in slidability, have a high nominal tensile strain at break, and are excellent in heat aging resistance. and

Based on the above-mentioned problems, the present inventors conducted studies and found that the above-mentioned problems can be solved by adjusting the amount of acid modification of the olefin polymer, using it in combination with a predetermined amine compound, and adjusting the ratio. I found
Specifically, the above problems have been solved by the following means.
<1> (A) For 100 parts by mass of polyacetal resin,
(B) 0.1 to 50 parts by mass of an acid-modified olefin polymer having an acid value of 1.0 to 30.0 mgKOH/g;
(C) 0.01 to 5 parts by mass of a compound containing a total of two or more primary amino groups and/or secondary amino groups selected from dihydrazone compounds, dihydrazide compounds, urea compounds, and melamine compounds;
The ratio (B)/(C) of the acid-modified olefin polymer (B) and the amino group-containing compound (C) is 20 to 200.
Resin composition.
<2> The resin composition according to <1>, further comprising (D) a hydrocarbon wax in an amount of 0.01 to 15.0 parts by mass with respect to 100 parts by mass of the polyacetal resin.
<3> The resin composition according to <2>, wherein the (D) hydrocarbon wax has a melt viscosity of 15 to 6000 mPa·s as measured at 140°C using a Brookfield viscometer.
<4> The resin composition according to any one of <1> to <3>, wherein the (B) acid-modified olefin polymer has a Vicat softening temperature according to JIS K7206 of 20° C. or higher.
<5> Any one of <1> to <4>, wherein the acid-modified olefin polymer (B) comprises an acid-modified olefin polymer modified with at least one of an unsaturated carboxylic acid and its anhydride. The described resin composition.
<6> The olefin polymer constituting the acid-modified olefin polymer (B) is selected from the group consisting of polyethylene, polypropylene, ethylene-propylene copolymer, and ethylene-butene copolymer, <1>- The resin composition according to any one of <5>.
<7> The resin composition according to any one of <1> to <5>, wherein the olefin polymer constituting (B) the acid-modified olefin polymer contains an ethylene-butene copolymer.
<8> 0.01 to 2 parts by mass of (C) a compound containing a total of two or more primary amino groups and/or secondary amino groups with respect to 100 parts by mass of the polyacetal resin, <1> to <7> The resin composition according to any one of 7>.
<9> The resin composition according to any one of <1> to <8>, which is used for forming a sliding member.
<10> A molded article formed from the resin composition according to any one of <1> to <9>.
<11> The molded article according to <10>, which is a sliding member.

According to the present invention, it has become possible to provide a resin composition and a molded article that have excellent slidability, a high nominal tensile strain at break, and excellent heat aging resistance.

It is a figure which shows the sample of the measurement result using a surface roughness measuring machine.

EMBODIMENT OF THE INVENTION Hereinafter, the form (only henceforth "this embodiment") for implementing this invention is demonstrated in detail. In addition, the following embodiment is an example for explaining the present invention, and the present invention is not limited only to this embodiment.
In this specification, the term "~" is used to mean that the numerical values before and after it are included as the lower limit and the upper limit.
In this specification, various physical property values and characteristic values are at 23° C. unless otherwise specified.
In the present specification, the number average molecular weight is a polystyrene-equivalent value measured by GPC (gel permeation chromatography) unless otherwise specified.
If the standards shown in this specification differ from year to year in terms of measurement methods, etc., the standards as of January 1, 2021 shall be used unless otherwise specified.

The resin composition of the present embodiment comprises (A) 100 parts by mass of a polyacetal resin, and (B) 0.1 to 50 parts by mass of an acid-modified olefin polymer having an acid value of 1.0 to 30.0 mgKOH/g. , (C) a compound containing a total of two or more primary amino groups and/or secondary amino groups selected from dihydrazone compounds, dihydrazide compounds, urea compounds, and melamine compounds (herein, "predetermined amine 0.01 to 5 parts by mass, and the ratio (B)/(C) of the (B) acid-modified olefin polymer and (C) the amino group-containing compound is 20 to 200. It is characterized by With such a structure, a resin composition having excellent slidability, high nominal tensile strain at break, and excellent heat aging resistance can be obtained.
This is presumed to be due to the following mechanism. That is, it is presumed that the acid possessed by the olefin polymer forms a crosslinked structure with the predetermined amine compound. Therefore, it is presumed that by setting the acid value in the olefin polymer to a predetermined value or more, a predetermined amine compound and a sufficient crosslinked structure, that is, a hard structure, can be formed, and the wear amount of the molded product can be reduced. be. Furthermore, it is presumed that by setting the acid value in the olefin polymer to a predetermined value or less, it is possible to prevent the formation of a crosslinked structure more than necessary.
In particular, it is presumed that the nominal tensile strain at break can be further increased by setting the ratio of the predetermined amine compound to 2 parts by mass or less with respect to 100 parts by mass of the polyacetal resin.
Details of the present embodiment will be described below.

<(A) Polyacetal resin>
The resin composition of the present embodiment contains (A) a polyacetal resin. By containing the polyacetal resin, a molded article having excellent slidability and mechanical strength can be obtained.
The (A) polyacetal resin used in the present embodiment is a polymer having an acetal structure -(-O-CRH-) _n - (wherein R represents a hydrogen atom or an organic group) in a repeating structure. is an oxymethylene group (--CH ₂ O--), which is a hydrogen atom, as a main structural unit. The (A) polyacetal resin used in the present embodiment includes copolymers (including block copolymers) and terpolymers containing one or more structural units other than the oxymethylene group, in addition to the acetal homopolymer consisting only of this repeating structure. Furthermore, it may have not only a linear structure but also a branched or crosslinked structure.

Examples of structural units other _than the oxymethylene group include an oxyethylene group ₍ --CH.sub.2CH.sub.2O--), an oxypropylene group ₍ _{--CH.sub.2CH.sub.2CH.sub.2O--} ), and an _oxybutylene group ₍ _{--CH.sub.2CH.sub.2CH} . ₂ CH ₂ O—) and other optionally branched oxyalkylene groups having 2 to 10 carbon atoms, among which optionally branched oxyalkylene groups having 2 to 4 carbon atoms are preferred; An oxyethylene group is particularly preferred. In addition, the content of such oxyalkylene structural units other than oxymethylene groups is preferably 0.1 mol % or more and 20 mol % or less, and 0.1 mol % or more and 15 mol % or less in the polyacetal resin. is more preferable.

The (A) polyacetal resin used in the present embodiment may be produced by any method, and may be produced by any conventionally known method. For example, as a method for producing a polyacetal resin having an oxymethylene group and an oxyalkylene group having 2 to 4 carbon atoms as a structural unit, an oxymethylene group such as a trimer (trioxane) or a tetramer (tetraoxane) of formaldehyde and a cyclic oligomer containing an oxyalkylene group having 2 to 4 carbon atoms such as ethylene oxide, 1,3-dioxolane, 1,3,6-trioxocane, 1,3-dioxepane, etc. can be manufactured.

Among them, the polyacetal resin (A) used in the present embodiment is preferably a copolymer of a cyclic oligomer such as trioxane or tetraoxane and ethylene oxide and/or 1,3-dioxolane, particularly trioxane and 1,3-dioxolane. - preferably a copolymer with dioxolane. In this case, the total content of ethylene oxide and/or 1,3-dioxolane is preferably 1 to 20% by mass with respect to 80 to 99% by mass of the cyclic oligomer.
(A) The melt flow rate (MFR) of the polyacetal resin is arbitrary, but according to ASTM-D1238, the value measured at 190° C. under a load of 2.16 kg is usually 0.01 to 150 g/10 minutes, and 0.01 to 150 g/10 minutes. It is preferably 1 to 100 g/10 minutes, more preferably 1 to 70 g/10 minutes, even more preferably 1 to 40 g/10 minutes, and even more preferably 1 to 30 g/10 minutes. .

The resin composition of the present embodiment preferably contains (A) a polyacetal resin in a proportion of 80% by mass or more of the resin composition, more preferably 85% by mass or more, and more preferably 90% by mass or more. It is more preferable to include in The upper limit is the case where the total amount other than the acid-modified olefin polymer and the predetermined amine compound is (A) the polyacetal resin.
The resin composition of the present embodiment may contain only one type of (A) polyacetal resin, or may contain two or more types. When two or more kinds are included, the total amount is preferably within the above range.

<(B) Acid-modified olefin polymer>
The resin composition of the present embodiment comprises (A) 100 parts by mass of polyacetal resin, and (B) 0.1 to 50 parts by mass of an acid-modified olefin polymer having an acid value of 1.0 to 30.0 mgKOH/g. include. By containing the acid-modified olefin polymer, a molded article having excellent slidability and mechanical strength can be obtained.
The acid value of the acid-modified olefin polymer (B) is preferably 2.0 mgKOH/g or more, more preferably 5.0 mgKOH/g or more, and even more preferably 8.0 mgKOH/g or more. , more preferably 10.0 mgKOH/g or more, and even more preferably 12.0 mgKOH/g or more. By making it more than the said lower limit, there exists a tendency for slidability to improve more. In addition, the acid value of (B) the acid-modified olefin polymer is preferably 25.0 mgKOH/g or less, more preferably 20.0 mgKOH/g or less. By making it equal to or less than the above upper limit, there is a tendency that the nominal tensile strain at break tends to be further improved.
When two or more kinds of olefin polymers are included, the acid value here is the sum of the values obtained by multiplying the acid value of each olefin polymer by the blending amount (mass) fraction of each olefin polymer. The same applies to molecular weight and melt flow rate (MFR), which will be described later.

A known olefin polymer can be used as the olefin polymer constituting (B) the acid-modified olefin polymer used in the present embodiment. The olefin polymer is preferably selected from the group consisting of polyethylene, polypropylene, ethylene-propylene copolymer and ethylene-butene copolymer, and more preferably contains ethylene-butene copolymer.
The acid-modified olefin polymer (B) in the present embodiment preferably has a number average molecular weight of 1×10 ⁴ or more, more preferably 2×10 ⁴ or more, and 50×10 ⁴ or less. is preferred. By using one having a number average molecular weight equal to or higher than the lower limit, a harder molded article can be formed, and the slidability of the resulting molded article can be further improved. Further, by using one having a number average molecular weight of not more than the above upper limit, it is possible to disperse uniformly by shearing during kneading, and there is a tendency that deterioration of mechanical properties can be suppressed.
Further, according to ASTM-D1238, the melt flow rate (MFR) measured at 190 ° C. and a load of 2.16 kg is preferably 30 g / 10 minutes or less, more preferably 20 g / 10 minutes or less, and 15 g / 10 minutes or less, and may be 10 g/10 minutes or less, or 5 g/10 minutes or less. By making it equal to or less than the above upper limit, a harder molded article can be formed, and the slidability of the obtained molded article tends to be further improved. The lower limit of the melt flow rate (MFR) can be, for example, 0.1 g/10 minutes or more. When the content is at least the above lower limit, uniform dispersion can be achieved by shearing during kneading, and deterioration of mechanical properties can be effectively suppressed.

The olefin polymer in the present embodiment is preferably an acid-modified olefin polymer modified with at least one unsaturated carboxylic acid and its anhydride, and at least one unsaturated carboxylic anhydride (preferably anhydrous More preferably, it is an acid-modified olefin polymer modified with maleic acid). Examples of unsaturated carboxylic acids include maleic acid, acrylic acid, methacrylic acid, maleic acid, citraconic acid, itaconic acid, tetrahydrophthalic acid, nadic acid, methylnadic acid, and allylsuccinic acid, with maleic acid being preferred.
Details of the modified olefin polymer modified with at least one of an unsaturated carboxylic acid and its anhydride can be referred to paragraph 0005 of JP-A-10-130458, the contents of which are incorporated herein.

The (B) acid-modified olefin polymer in the present embodiment preferably has a Vicat softening temperature according to JIS K7206 of 20°C or higher, more preferably 23°C or higher. The Vicat softening temperature is a measure of the temperature at which a thermoplastic begins to soften rapidly, and is an indicator of short-term heat resistance. In this embodiment, by using such an acid-modified olefin resin, the crosslinked structure formed by reacting with a predetermined amine compound has excellent heat resistance during sliding. In the present embodiment, the Vicat softening temperature is the Vicat softening temperature at a load of 50 N and a heating rate of 50° C./hour. Although the upper limit of the Vicat softening temperature is not particularly defined, it is usually lower than the melting point of the polyacetal resin, preferably 150° C. or lower.

The content of the (B) acid-modified olefin polymer in the resin composition of the present embodiment is 0.1 parts by mass or more and 0.5 parts by mass or more with respect to 100 parts by mass of the (A) polyacetal resin. is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and even more preferably 3 parts by mass or more. By making it more than the said lower limit, there exists a tendency for the molded article obtained to be more excellent in slidability. In addition, the content of the (B) acid-modified olefin polymer in the resin composition of the present embodiment is 50 parts by mass or less, preferably 40 parts by mass or less, relative to 100 parts by mass of the (A) polyacetal resin. , 30 parts by mass or less, more preferably 20 parts by mass or less, even more preferably 10 parts by mass or less, and even more preferably 7 parts by mass or less. By making it equal to or less than the above upper limit, there is a tendency that the nominal strain at break of the resulting molded product is further improved.
The resin composition of the present embodiment may contain only one type of (B) acid-modified olefin polymer, or may contain two or more types. When two or more types are included, the total amount is preferably within the above range.

<(C) Compound Containing a Total of Two or More Primary Amino Groups and/or Secondary Amino Groups>
The resin composition of the present embodiment contains (A) 100 parts by mass of polyacetal resin, (C) primary amino groups and/or secondary amino groups selected from dihydrazone compounds, dihydrazide compounds, urea compounds, and melamine compounds. 0.01 to 5 parts by mass of a compound containing a total of two or more groups (predetermined amine compound). (C) The prescribed amine compound forms a crosslinked structure with the acid-modified olefin polymer, and a molded article having excellent slidability can be obtained. In addition, molded articles having excellent resistance to heat aging can be obtained.
In this embodiment, it is presumed that the primary amine and/or secondary amine of the (C) predetermined amine compound reacts with the acid of the acid-modified olefin polymer. (C) Since the predetermined amine compound has two or more primary amines and/or secondary amines in one molecule, it is presumed that a crosslinked structure is formed between the acid-modified olefin polymers. Therefore, the hardness of the obtained molded article is increased, and the wear resistance of the molded article is improved.

(C) The given amine compound contains primary amino groups and/or secondary amino groups, more preferably at least primary amines. By containing a primary amine, it tends to form a crosslinked structure more easily with the acid-modified olefin polymer.
(C) The predetermined amine compound contains two or more primary amino groups and/or secondary amino groups in one molecule, preferably two to five, more preferably two or three, and even more preferably two.
Although the molecular weight of the predetermined amine compound (C) is not particularly defined, it is preferably 80 to 500, more preferably 80 to 300, from the viewpoint of ease of forming a crosslinked structure.

In this embodiment, (C) the predetermined amine compound is selected from dihydrazone compounds, dihydrazide compounds, urea compounds, and melamine compounds, and is at least selected from compounds including dihydrazide compounds, urea compounds, and melamine compounds. One type is preferred, and a dihydrazide compound is more preferred.

Regarding the dihydrazone compound, the description in paragraphs 0015 to 0023 of JP-A-2022-015084 can be referred to, and the contents thereof are incorporated herein.

The hydrazide compound is not particularly defined as long as it has two or more hydrazide groups. The hydrazide compound preferably has a molecular weight of 200-1000. Also, the hydrazide compound is preferably a dihydrazide compound or a trihydrazide compound, more preferably a dihydrazide compound.
Examples of dihydrazide compounds include aliphatic dihydrazide compounds and aromatic dihydrazide compounds.

Examples of aliphatic dihydrazide compounds include carbodihydrazide, oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, azelaic acid dihydrazide, sebacic acid dihydrazide, dodecanedioic acid dihydrazide (1,12-dodecanedicarb hydrazide), 1,18-octadecanedicarbohydrazide, stearic acid dihydrazide, maleic acid dihydrazide, fumaric acid dihydrazide, 7,11-octadecadien-1,18-dicarbohydrazide and the like.

Examples of aromatic dihydrazide compounds include isophthalic acid dihydrazide, terephthalic acid dihydrazide, 1,5-naphthalenedicarbohydrazide, 1,8-naphthalenedicarbohydrazide, 2,6-naphthalenedicarbohydrazide, 4,4′-oxybis benzenesulfonyl hydrazide and 1,5-diphenylcarbonohydrazide.

The hydrazide compound used in this embodiment is preferably represented by the following formula (1).
formula (1)

In the above formula (1), R ¹ represents an aliphatic hydrocarbon group having 2 to 18 carbon atoms, an alicyclic hydrocarbon group having 6 to 10 carbon atoms or an aromatic hydrocarbon group having 6 to 10 carbon atoms; R ² to R ⁵ each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms; R ² and R ³ and R ⁴ and R ⁵ are bonded to form a ring; may

In formula (1), R ¹ represents an aliphatic hydrocarbon group having 2 to 18 carbon atoms, an alicyclic hydrocarbon group having 6 to 10 carbon atoms or an aromatic hydrocarbon group having 6 to 10 carbon atoms, and It is preferably an aliphatic hydrocarbon group having 4 to 18 carbon atoms, more preferably an aliphatic hydrocarbon group having 8 to 12 carbon atoms.
The aliphatic hydrocarbon group may be saturated or unsaturated, and linear or branched. Aliphatic hydrocarbon groups include, for example, butylene, pentylene, hexylene, heptylene, octylene, nonylene, decylene, undecylene, dodecylene, tridecylene, tetradecylene, pentadecylene, hexadecylene, and heptadecylene. and alkylene groups such as octadecylene and nonadecylene groups.

The alicyclic hydrocarbon groups may be saturated or unsaturated.
Alicyclic hydrocarbon groups include cycloalkylene groups having 6 to 10 carbon atoms. The cycloalkylene group includes, for example, a cyclohexylene group.

Aromatic hydrocarbon groups include, for example, phenylene groups and arylene groups such as naphthylene groups.
A substituent may be bonded to at least part of the carbon atoms of the aromatic hydrocarbon group. Examples of this substituent include a halogen group, a nitro group, an alkyl group having 1 to 20 carbon atoms, and the like.

In formula (1), R ² to R ⁵ are each independently preferably a hydrogen atom, a methyl group or an ethyl group, more preferably a hydrogen atom.

The urea compound used in this embodiment means a compound having a —(HN) ₂ C(═O) structure, and its type is not particularly limited.
The urea compound used in this embodiment preferably contains a compound having a skeleton represented by formula (N). By having such a structure, when the polyacetal resin is allowed to stay in the molding machine for a long period of time, the generation of formaldehyde can be suppressed more remarkably.

Here, the compound having a skeleton represented by the formula (N) includes the compound represented by the formula (N) (ethylene urea), nitrogen atoms forming the cyclic structure of the formula (N) and /or is intended to include compounds having structures in which a hydrogen atom bonded to a carbon atom is replaced by a substituent. When having a substituent, it is preferred that a hydrogen atom bonded to a carbon atom is replaced by a substituent. Examples of substituents include an oxygen atom (=O), a urea group, and a (methyl group).

The molecular weight of the urea compound used in this embodiment is preferably 60 or more, more preferably 86 or more. Also, the upper limit is preferably 500 or less, more preferably 300 or less, and even more preferably 200 or less.
Examples of urea compounds include urea, ethylene urea, allantoin, and biurea, preferably ethylene urea and/or allantoin, and more preferably ethylene urea.

The melamine compound used in the present embodiment is a compound (melamine) having a triazine ring in the center of the structure and three amino groups around it (melamine) or a derivative thereof, and includes melamine, melamine cyanurate, acetoguanamine, benzoguanamine, and melamine condensates ( melam, melem, melon), methylolmelamine and the like, and among them, melamine is preferred.

The content of the (C) predetermined amine compound in the resin composition of the present embodiment is 0.01 parts by mass or more, and may be 0.02 parts by mass or more with respect to 100 parts by mass of the (A) polyacetal resin. It is preferably at least 0.03 parts by mass, and even more preferably at least 0.04 parts by mass. By making it more than the said lower limit, there exists a tendency for the molded article obtained to be more excellent in slidability. In addition, the content of the (C) predetermined amine compound in the resin composition of the present embodiment is 5 parts by mass or less, preferably 3 parts by mass or less, relative to 100 parts by mass of the (A) polyacetal resin. It is more preferably 2 parts by mass or less, even more preferably 1 part by mass or less, still more preferably 0.7 parts by mass or less, and even more preferably 0.3 parts by mass or less. When the amount is not more than the above upper limit, particularly not more than 2 parts by mass, the tensile fracture nominal strain of the resulting molded article tends to be further improved.
The resin composition of the present embodiment may contain only one type of (C) the predetermined amine compound, or may contain two or more types. When two or more types are included, the total amount is preferably within the above range.

In the present embodiment, the ratio (B)/(C) of (B) the acid-modified olefin polymer and (C) the amino group-containing compound is 20-200. By setting it as the said range, there exists a tendency for slidability to improve more.
The ratio (B)/(C) is preferably 23 or more, more preferably 28 or more, and preferably 180 or less, and may be 150 or less.

<(D) Hydrocarbon wax>
The resin composition of the present embodiment preferably contains (D) hydrocarbon wax in an amount of 0.1 to 15 parts by mass based on 100 parts by mass of (A) polyacetal resin. By including (D) a hydrocarbon wax, the slidability of the obtained molded article tends to be further improved. Among the (D) hydrocarbon waxes, if they can also correspond to the above acid-modified olefin polymers, those having a Vicat softening temperature of 20° C. or higher are considered to correspond to the above-mentioned (B) acid-modified olefin polymers. Those for which the Vicat softening temperature cannot be measured shall correspond to (D) hydrocarbon waxes. Examples of those for which the Vicat softening temperature cannot be measured include those for which a test piece for measuring the Vicat softening temperature cannot be molded. (D) Hydrocarbon waxes usually cannot produce test pieces for measuring the Vicat softening temperature.
(D) The hydrocarbon wax is a wax containing a hydrocarbon as a main component, and may have a functional group such as an acid group.

The (D) hydrocarbon wax used in the present embodiment preferably has a melt viscosity of 15 mPa s or more, preferably 20 mPa s or more, and preferably 80 mPa s or more, as measured using a Brookfield viscometer. It is more preferable that the viscosity is 100 mPa·s or more. When the content is at least the above lower limit, it is possible to more effectively prevent the occurrence of bleeding out onto the surface of the molded article. The melt viscosity is preferably 6000 mPa·s or less, more preferably 5000 mPa·s or less, and may be 4000 mPa·s or less. By setting the content to the upper limit value or less, the friction and wear characteristics, moldability, and the like can be further improved.
The measurement of the molecular weight by the viscosity method is taken as the value measured at 140°C using a Brookfield viscometer.

(D) Hydrocarbon waxes include paraffin waxes, polyolefin waxes, and Fischer-Tropsch waxes. In the present embodiment, polyolefin wax is preferred, and polyethylene wax is more preferred.
Examples of (D) hydrocarbon waxes include FT-100 and FT-0070 sold by Nippon Seiro, and Paraflint manufactured by SASOL.
In particular, polyolefin waxes include Hiwax (manufactured by Mitsui Chemicals), Sanwax (manufactured by Sanyo Chemical Industries), Epolen (manufactured by Eastman Chemical), and Allied Wax (manufactured by Allied Signals).

The (D) polyethylene wax used in this embodiment is preferably a modified polyethylene wax obtained by acid-modifying a low-molecular-weight polyethylene or a low-molecular-weight polyethylene copolymer. The acid modification treatment may be carried out by treating the wax with an inorganic acid, an organic acid, an unsaturated carboxylic acid, or the like in the presence of peroxide or oxygen, if necessary, to introduce a polar group such as a carboxyl group or a sulfonic acid group.

These polyethylene waxes are commercially available under the names of medium-acid-value polyethylene wax, high-acid-value polyethylene wax, acid-modified polyethylene wax, and the like, and are readily available on the market.
The polyethylene wax used in the present embodiment preferably has an acid value of 5 mgKOH/g or more, more preferably 10 mgKOH/g or more, and may be 26 mgKOH/g or more. The upper limit of the acid value of the polyethylene wax is preferably 60 mgKOH/g or less, more preferably 50 mgKOH/g or less, further preferably 40 mgKOH/g or less, and 37 mgKOH/g or less. More preferably, it may be 35 mgKOH/g or less, or 30 mgKOH/g or less. By setting it as such a range, high frictional characteristics and wear resistance can be achieved.
The acid value is measured according to the description in the examples below.

The content of the (D) hydrocarbon wax in the resin composition of the present embodiment is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, relative to 100 parts by mass of the (A) polyacetal resin. More preferably, it is 0.3 parts by mass or more, more preferably 0.8 parts by mass or more, and particularly 1.2 parts by mass or more. By making it more than the said lower limit, it tends to be more excellent in slidability. Further, the content of (D) hydrocarbon wax in the resin composition of the present embodiment is preferably 15.0 parts by mass or less, and 10.0 parts by mass or less with respect to 100 parts by mass of (A) polyacetal resin. is more preferably 5.0 parts by mass or less, and even more preferably 3.0 parts by mass or less. A reduction in mechanical strength can be effectively suppressed by setting the content to be equal to or less than the upper limit.
The resin composition of the present embodiment may contain only one type of (D) hydrocarbon wax, or may contain two or more types. When two or more types are included, the total amount is preferably within the above range.

<Other ingredients>
In addition to the above, the resin composition of the present embodiment includes waxes other than the above, inorganic particles such as calcium carbonate, antioxidants (hindered amines, hindered phenols), heat stabilizers, colorants, nucleating agents, plasticizers. Additives such as agents, fluorescent brighteners, release agents (fatty acid ester compounds, silicon compounds, etc.), antistatic agents, UV absorbers (benzotriazole-based or benzophenone-based compounds, etc.) as necessary. You may
The resin composition of the present embodiment contains (A) a polyacetal resin, (B) an acid-modified olefin polymer, (C) a predetermined amine compound, and other components that are optionally blended so that the total amount is 100% by mass. adjusted to In the resin composition of the present embodiment, the total of (A) polyacetal resin, (B) acid-modified olefin polymer, (C) predetermined amine compound and polyethylene wax preferably accounts for 85% by mass or more of the resin composition. , more preferably 90% by mass or more, more preferably 95% by mass or more, and even more preferably 98% by mass or more.

<Physical properties of the resin composition>
The resin composition of the present embodiment preferably has a high nominal strain at break. Specifically, the resin composition is molded into a test piece specified in the ISO9988-2 standard, and the tensile fracture nominal strain measured according to the ISO527 standard is preferably 5% or more, and preferably 10% or more. More preferably, it is 13% or more, and even more preferably 15% or more. Although the upper limit of the nominal strain at break is not particularly defined, 50% or less is practical, and even 40% or less sufficiently satisfies the required performance.
The resin composition of the present embodiment preferably has excellent slidability. Specifically, the resin composition is molded into a test piece specified in the ISO9988-2 standard and a pin-type test piece with a tip of 10 mmφ and a height of 30 mm, a load of 200 gf, a linear velocity of 1200 mm / min, a moving distance of 10 mm, and the number of reciprocations. After contacting the pin type test piece and the test piece specified in the ISO9988-2 standard under the condition of 8000 times, and performing a reciprocating sliding test, the wear groove formed in the test piece specified in the ISO9988-2 standard. The wear area obtained by measuring the width and depth and measuring the area enclosed by the width and depth as the wear groove area is preferably 15,000 μm ² or less, more preferably 10,000 μm ² or less. It is more preferably 8,000 μm ² or less, even more preferably 5,000 μm ² or less, and even more preferably 4,000 μm ² or less. Although the lower limit of the wear area in the reciprocating sliding test is not particularly defined, it is practically 100 μm ² or more, and even 700 μm ² or more sufficiently satisfies the required performance.
The resin composition of the present embodiment preferably has excellent heat aging resistance. Specifically, the resin composition of the present embodiment is molded into a test piece (a test piece defined in the ISO9988-2 standard) before and after treatment at 80 ° C. for 500 hours. ΔE is preferably 1.5 or less. , is more preferably less than 1.0. The ideal lower limit is 0, but even if it is 0.1 or more, the required performance is sufficiently satisfied.

<Method for producing resin composition>
The resin composition of the present embodiment is easily prepared by a known method generally used as a method for preparing conventional thermoplastic resin compositions. For example, (1) a method of mixing all the components that make up the composition, feeding this to an extruder and melt-kneading to obtain a pellet-like composition, (2) a method of obtaining a pellet-like composition, A method of obtaining a composition in the form of pellets by supplying the remaining components from the main feed port of the extruder and melt-kneading them from the side feed port. It is also possible to adopt a method of adjusting the composition to a predetermined composition.

Examples of kneaders include kneaders, Banbury mixers, and extruders. Various conditions and devices for mixing and kneading are not particularly limited, and may be determined by appropriately selecting from conventionally known arbitrary conditions. The kneading is preferably carried out at a temperature higher than the melting temperature of the polyacetal resin, specifically at a temperature higher than the melting temperature of the polyacetal resin (generally 180° C. or higher).

<Molded product>
The molded article of this embodiment is formed from the resin composition of this embodiment. Pellets obtained by pelletizing the resin composition of the present embodiment are molded by various molding methods to obtain molded articles. Alternatively, the resin composition melted and kneaded by an extruder can be directly molded into a molded product without going through pellets.
The shape of the molded product is not particularly limited and can be appropriately selected according to the use and purpose of the molded product. Circular, elliptical, gear-shaped, polygonal, odd-shaped, hollow, frame-shaped, box-shaped, panel-shaped and the like can be mentioned. The molded product of this embodiment may be a finished product or a part.

The method for molding the molded article is not particularly limited, and conventionally known molding methods can be employed, such as injection molding, injection compression molding, extrusion molding, profile extrusion, transfer molding, blow molding, Gas-assisted blow molding, blow molding, extrusion blow molding, IMC (in-mold coating molding) molding, rotational molding, multi-layer molding, two-color molding, insert molding, sandwich molding, foam molding, additive A compression molding method and the like can be mentioned.

The resin composition of the present embodiment is preferably used for forming sliding members. Therefore, the molded article formed from the resin composition of this embodiment is preferably used as a sliding member (sliding part).
Specific examples of sliding members include gears, rotary shafts, bearings, gears, End face materials for cams and mechanical seals, valve seats for valves, sealing members such as V-rings, rod packings, piston rings and rider rings, rotating shafts for compressors, rotating sleeves, pistons, impellers, rollers and other sliding members mentioned.

The sliding member of the present embodiment can be used not only with the sliding members of the present embodiment, but also with other resin sliding members, fiber-reinforced resin sliding members, ceramics, and metal sliding members. It can also be applied as a member.

EXAMPLES The present invention will be described more specifically with reference to examples below. The materials, usage amounts, ratios, processing details, processing procedures, etc. shown in the following examples can be changed as appropriate without departing from the gist of the present invention. Accordingly, the scope of the present invention is not limited to the specific examples shown below.
If the measuring instruments and the like used in the examples are discontinued and difficult to obtain, other instruments having equivalent performance can be used for measurement.

1. Raw Materials Raw materials shown in Table 1 below were used.

ethylene urea

melamine

<Measurement of acid value>
The mass of potassium hydroxide required for neutralizing 1 g of a sample (acid-modified olefin polymer, polyethylene wax, etc.) was measured and taken as the acid value.
Specifically, it was measured by neutralization titration according to JIS K0070. 1 g of the sample was precisely weighed and dissolved in 100 mL of xylene with stirring at about 120°C. After complete dissolution, a phenolphthalein solution was added, and neutralization titration was performed using a 0.1 mol/L potassium hydroxide ethanol solution whose exact concentration had been determined in advance. The amount of dropping (T), the factor (f) of 0.1 mol / L potassium hydroxide ethanol solution, 1/10 (5.611) of the formula weight of potassium hydroxide 56.11, and the mass (S) of the sample, the following formula The acid value was calculated by
Acid value = T x f x 5.611/S
Units are given as mgKOH/g.

2. Examples 1-7, Comparative Examples 1-9
Each component was blended as shown in Table 2 or Table 3 below (the unit of each component in Table 2 or Table 3 is parts by mass), preblended, and then a 30 mm diameter twin-screw extrusion having one vent port. (Extrusion conditions: L/D = 35, extrusion temperature = 190°C, screw speed = 120 rpm, vent vacuum pressure = -0.08 MPa, discharge rate = 10 kg/hr). , to prepare a resin composition in the form of pellets.
The following evaluation was performed using the obtained resin composition.

<Nominal tensile strain at break>
After drying the resin composition obtained above at 80 ° C. for 3 hours, using an injection molding machine ("EC-100S" manufactured by Shibaura Kikai Co., Ltd.), under the conditions of a cylinder temperature of 195 ° C. and a mold temperature of 90 ° C. It was molded into a test piece specified in the ISO9988-2 standard. Nominal tensile strain at break was measured according to the ISO527 standard.
The unit is %.

<Reciprocating sliding test>
Mold a pin-shaped test piece with a tip of 10 mmφ and a height of 30 mm as specified in the ISO9988-2 standard, contact the test piece and the pin-shaped test piece specified in the ISO9988-2 standard, load 200 gf, linear velocity Measure the width and depth of the wear groove of the test piece specified in the ISO9988-2 standard after testing under the conditions of 1200 mm / min, 10 mm travel distance, and 8000 reciprocations using a surface roughness measuring machine, The area enclosed by the width and depth was measured as the wear groove area. The unit is μm ² .
FIG. 1 is a sample of the measurement results using a surface roughness tester, and shows the area of the wear groove area. The shaded area in FIG. 1 is the wear groove area.
The abrasion test used a Tribogear surface property measuring instrument TYPE: 38 (manufactured by Shinto Kagaku Co., Ltd.), and the surface roughness measuring instrument used Surfcom 3000A (manufactured by ACCRETECH). The unit is μm ² .

<Heat resistance aging test>
Molded into a test piece specified in the ISO9988-2 standard, the obtained test piece was allowed to stand in an environment of 80 ° C. for 500 hours, and the color difference ΔE before and after that was measured by Nippon Denshoku Industries Co., Ltd. SE6000 type (light source : C/2, reflected light).

As is clear from the above results, the resin composition of the present invention had a small wear area in the reciprocating sliding test and was excellent in slidability. On the other hand, when the acid value of the olefin polymer (B) was low (Comparative Example 1), the wear area was large and the slidability was poor. Also, when the amine compound was not contained (Comparative Example 2), the wear area was large and the slidability was poor. When (B)/(C) was outside the range of the present invention (Comparative Examples 3 to 5), the nominal tensile strain was low and the wear resistance was poor. Even if an amine compound was contained, when (C) the prescribed amine compound was not contained (Comparative Examples 6 to 8), the heat aging resistance was poor. Further, when the acid value of the acid-modified olefin polymer (B) was outside the range of the present invention (Comparative Example 9), the tensile nominal strain was low.
Furthermore, by adjusting the content of the predetermined amine compound (C), the nominal tensile strain at break could be increased, and a resin composition excellent in balance between slidability and mechanical properties was obtained.

Claims

(A) for 100 parts by mass of polyacetal resin,
(B) 0.1 to 50 parts by mass of an acid-modified olefin polymer having an acid value of 1.0 to 30.0 mgKOH/g;
(C) 0.01 to 5 parts by mass of a compound containing a total of two or more primary amino groups and/or secondary amino groups selected from dihydrazone compounds, dihydrazide compounds, urea compounds, and melamine compounds;
The ratio (B)/(C) of the acid-modified olefin polymer (B) and the amino group-containing compound (C) is 20 to 200.
Resin composition.
The resin composition according to claim 1, further comprising (D) a hydrocarbon wax in an amount of 0.01 to 15.0 parts by mass with respect to 100 parts by mass of the polyacetal resin.
3. The resin composition according to claim 2, wherein the (D) hydrocarbon wax has a melt viscosity of 15 mPa·s or more and 6000 mPa·s or less measured at 140° C. using a Brookfield viscometer.
The resin composition according to any one of claims 1 to 3, wherein the acid-modified olefin polymer (B) has a Vicat softening temperature of 20°C or higher according to JIS K7206.
The resin composition according to any one of claims 1 to 4, wherein the acid-modified olefin polymer (B) comprises an acid-modified olefin polymer modified with at least one of an unsaturated carboxylic acid and its anhydride. .
6. Any one of claims 1 to 5, wherein the olefin polymer constituting the acid-modified olefin polymer (B) is selected from the group consisting of polyethylene, polypropylene, ethylene-propylene copolymers, and ethylene-butene copolymers. 1. The resin composition according to claim 1.
The resin composition according to any one of claims 1 to 5, wherein the olefin polymer constituting (B) the acid-modified olefin polymer comprises an ethylene-butene copolymer.
Any one of claims 1 to 7, wherein the (C) compound containing a total of two or more primary amino groups and/or secondary amino groups is contained in an amount of 0.01 to 2 parts by mass with respect to 100 parts by mass of the polyacetal resin. 1. The resin composition according to item 1.
The resin composition according to any one of claims 1 to 8, which is used for forming a sliding member.
A molded article formed from the resin composition according to any one of claims 1 to 9.
11. The molded article according to claim 10, which is a sliding member.