JP2015007195A - Polyacetal resin composition and molded body thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyacetal resin composition capable of improving abrasion wear properties in sliding with a minute load when a coloring agent is added, and also capable of suppressing sound squeak while having excellent abrasion wear properties in sliding at a high load.SOLUTION: A polyacetal resin composition includes, based on (A) 100 pts.mass of polyacetal resin, (B) 1-5 pts.mass of an aliphatic compound with a molecular weight of 10,000 or less and (C) 0.01-5 pts.mass of a coloring agent.

Description

  The present invention relates to a polyacetal resin composition and a molded body thereof.

  Polyacetal resin has a good balance of mechanical strength, chemical resistance, slidability, and wear resistance and is easy to process. And widely used in automobile parts and other mechanical parts. Polyacetal resin has been increasingly required for performance due to the expansion of its application fields.

  The polyacetal resin is inherently white, but is colored into various colors from the viewpoint of design and the like. In order to color the polyacetal resin, an organic inorganic pigment is generally used. These pigments do not significantly affect the sliding characteristics under a high load that has been conventionally performed. However, for example, in applications where sliding characteristics under a very small load are required, such as HDD internal parts. It has recently been found to have a serious adverse effect on its wear properties. In addition, in parts used in printer gears and the like that require sliding characteristics under high loads, suppression of rubbing noise and squeal generated during use is required. There is a demand from the world for materials that satisfy both the sliding characteristics under low loads and the sliding characteristics under high loads (especially the generation of sound).

  For example, Patent Document 1 discloses a technique in which a fluorine compound such as polytetrafluoroethylene (PTFE), a phosphazene lubricant, carnauba wax, polyethylene wax, metal soap, or the like is added as a lubricant to a polyacetal resin. Patent Documents 2 and 3 disclose techniques for adding polyolefin as a lubricant to polyacetal resin.

JP 2001-297548 A International Publication No. 2003/055945 JP 2011-208114 A

  The techniques described in Patent Documents 1 and 2 improve the sliding characteristics under a high load, but cannot solve the sliding characteristics under a minute load. In addition, in the technique described in Patent Document 3, the sliding characteristics under a minute load are examined, but the suppression of noise during high load sliding has not been solved, and further, when a colorant is blended The adverse effects on the wear characteristics during sliding under a minute load cannot be solved.

  From such a background, the present invention is a polyacetal resin that improves the wear characteristics at the time of microload sliding when blended with a colorant, and has excellent wear characteristics at the time of high load sliding and can suppress noise. It is an object to provide a composition.

  As a result of intensive studies to solve the above problems, the present inventors have found that a polyacetal resin composition containing a polyacetal resin, a specific aliphatic compound, and a colorant can solve the above problems, and the present invention. It came to complete.

That is, the present invention is as follows.
[1]
(A) The polyacetal resin composition containing 1 to 5 parts by mass of an aliphatic compound having a molecular weight of 10,000 or less and (C) 0.01 to 5 parts by mass of a colorant with respect to 100 parts by mass of the polyacetal resin. .
[2]
(A) The polyacetal resin composition according to [1], wherein the polyacetal resin contains a block polymer.
[3]
(A) The polyacetal resin composition according to [2], wherein the ratio of the block polymer in 100% by mass of the polyacetal resin is 50% by mass or more.
[4]
(A) The polyacetal resin composition in any one of [1]-[3] containing 0.5-5 mass parts of polyolefin resin with respect to 100 mass parts of polyacetal resin.
[5]
(D) Polyolefin resin is polyethylene; polypropylene; ethylene-α-olefin copolymer; ethylene acrylate copolymer having an acrylate unit content of 5 to 30% by weight; polyolefin (d1) block; A block polymer having a structure in which the block of the hydrophilic polymer (d2) is alternately and repeatedly bonded through at least one bond selected from the group consisting of an ester bond, an amide bond, an ether bond, a urethane bond and an imide bond; The polyacetal resin composition according to [4], which is at least one selected from the group consisting of these modified products.
[6]
The molded object containing the polyacetal resin composition in any one of [1]-[5].

  According to the present invention, it is possible to provide a polyacetal resin composition that improves wear characteristics during sliding under a minute load when a colorant is blended, and has excellent wear characteristics during high load sliding and can suppress noise. become.

  Hereinafter, although the form for implementing this invention (henceforth "this embodiment") is demonstrated in detail, this invention is not limited to the following description, In the range of the summary Various modifications can be made.

≪Polyacetal resin composition≫
In the polyacetal resin composition of the present embodiment, (B) 1 to 5 parts by mass of an aliphatic compound having a molecular weight of 10,000 or less, and (C) a colorant 0.01 to 100 parts by mass of (A) polyacetal resin. It is a resin composition containing 5 parts by mass.

<(A) polyacetal resin>
Here, the (A) polyacetal resin that can be used in the polyacetal resin composition of the present embodiment will be described in detail.

  Usable (A) polyacetal resins include polyacetal homopolymers and polyacetal copolymers.

  Specifically, a polyacetal homopolymer consisting essentially of oxymethylene units obtained by homopolymerizing formaldehyde monomer or a cyclic oligomer of formaldehyde such as trimer (trioxane) or tetramer (tetraoxane), Formaldehyde monomers or cyclic oligomers of formaldehyde such as trimer (trioxane) and tetramer (tetraoxane), ethylene oxide, propylene oxide, epichlorohydrin, 1,3-dioxolane, 1,4-butanediol formal, etc. Examples thereof include polyacetal copolymers obtained by copolymerizing a cyclic ether such as cyclic formal of glycol or diglycol or cyclic formal.

  In addition, as a polyacetal copolymer, a branched polyacetal copolymer obtained by copolymerizing a monomer of formaldehyde and / or a cyclic oligomer of formaldehyde and a monofunctional glycidyl ether, and a polyfunctional glycidyl ether are copolymerized. It is also possible to use a polyacetal copolymer having a crosslinked structure obtained in this way.

  Furthermore, a polyacetal homopolymer and a polyacetal copolymer having a block component composed of a compound having a functional group such as a hydroxyl group at both ends or one end (both are also referred to as “block polymer” hereinafter) can be used.

As a block component in the block polymer mentioned above, the block component represented by the following general formula (1), (2) or (3) is preferable.

In formulas (1) and (2), R ₁ , R ₂ and R ₃ are each independently one chemistry selected from the group consisting of a hydrogen atom, an alkyl group, a substituted alkyl group, an aryl group and a substituted aryl group. A seed is shown, and a plurality of R 1, R ₂ , and R ₃ may be the same or different. m shows the integer of 2-6, and the integer of 2-5 is preferable. n shows the integer of 1-1000, and the integer of 10-250 is preferable. The group represented by the general formula (1) is a residue obtained by eliminating a hydrogen atom from an alkylene oxide adduct of alcohol, and the group represented by the general formula (2) is an alkylene oxide addition of a carboxylic acid. It is a residue obtained by removing a hydrogen atom from a product. The polyacetal homopolymer having the block component can be prepared, for example, by the method described in JP-A-57-31918.

In Formula (3), R ₄ represents one chemical species selected from the group consisting of a hydrogen atom, an alkyl group, a substituted alkyl group, an aryl group, and a substituted aryl group, and the plurality of R ₄ are the same. May be different. P represents an integer of 2 to 6, and two ps may be the same or different. q and r each represent a positive number, q is 2 to 98 mol%, and r is 2 to 98 mol% with respect to a total of 100 mol% of q and r, and — (CH (CH ₂ CH ₃ ) The CH ₂ ) -unit and the-(CH ₂ CH ₂ CH ₂ CH ₂ ) -unit each exist in random or block form.

The above equation (1), the block component represented by formula (2) or Formula (3) may have the following unsaturated bond iodine value 20g-I ₂ / 100g. Although it does not specifically limit as an unsaturated bond, For example, a carbon-carbon double bond is mentioned.

  Examples of the polyacetal copolymer having the block component include polyoxymethylene block copolymers disclosed in International Publication No. 01/09213, and can be prepared by the method described in the publication.

  As the (A) polyacetal resin contained in the polyacetal resin composition of the present embodiment, any of a polyacetal homopolymer having the above-described block component and a polyacetal copolymer having the above-described block component is used. Of course, these can also be used together. Moreover, (A) polyacetal resin may use together 2 or more types of polyacetal resin from which molecular weight differs, polyacetal copolymer from which the amount of comonomer differs, for example.

  The amount of the block component inserted into the block polymer is preferably at least 15%, more preferably 13% or more, and even more preferably 10% or more, assuming that the block polymer is 100%. Although the upper limit of the amount of block component insertion in the block polymer is not particularly limited, it is, for example, 30% or less.

  The molecular weight of the block component in the block polymer is preferably 10,000 or less, more preferably 8000 or less, and even more preferably 5000 or less.

Specific examples of the compound forming the block component of the block polymer is not particularly limited, for _{example, C 18 H 37 O (CH} 2 CH 2 O) 40 C 18 H 37, C 11 H 23 CO 2 (CH 2 CH ₂ O) ₃₀ H, C ₁₈ H ₃₇ O (CH ₂ CH ₂ O) ₇₀ H, C ₁₈ H ₃₇ O (CH ₂ CH ₂ O) ₄₀ H, hydrogenated polybutadiene, and the like.

  The polyacetal resin (A) preferably contains a block polymer. By using the polyacetal resin (A) containing a block polymer, there is a tendency that many block components exist in the amorphous part of the polyacetal resin.

  The ratio of the block polymer in the polyacetal resin (A) is preferably 50% by mass or more, more preferably 60% by mass or more, and still more preferably 65% by mass when the polyacetal resin (A) is 100% by mass. % Or more, particularly preferably 80% by mass or more. Although the upper limit of the ratio of the block polymer is not particularly limited, for example, it is 99% by mass or less.

  When the ratio of the block polymer is within the above range, it is preferable from the viewpoint of dispersibility of the aliphatic compound (B).

In the polyacetal resin composition of the present embodiment, the ratio of the block polymer can be measured by ¹ H-NMR, ¹³ C-NMR, or the like.

  As described above, as the (A) polyacetal resin contained in the polyacetal resin composition of the present embodiment, any of the above-mentioned polyacetal homopolymer and the above-mentioned polyacetal copolymer can be used. Of course, these can also be used together. Moreover, (A) polyacetal resin may use together 2 or more types of polyacetal resin from which molecular weight differs, polyacetal copolymer from which the amount of comonomer differs, for example.

<(B) Aliphatic compound having a molecular weight of 10,000 or less>
Next, (B) an aliphatic compound having a molecular weight of 10,000 or less that can be used in this embodiment will be described in detail. (B) When the molecular weight of the aliphatic compound is 10,000 or less, the polyacetal resin composition can sufficiently exhibit the wear performance during sliding under a minute load even when a colorant is blended. (B) The upper limit with more preferable molecular weight of an aliphatic compound is 9500, and a more preferable upper limit is 9000. (B) The lower limit of the molecular weight of the aliphatic compound is, for example, 50.

  In this embodiment, when the (B) aliphatic compound is a polymer, the molecular weight of the (B) aliphatic compound is a weight average molecular weight. The molecular weight of the (B) aliphatic compound is, for example, gel permeation chromatography (GPC), liquid chromatography / mass spectrometry (LC / MS), matrix-assisted laser desorption / ionization time-of-flight mass spectrometry ( It can be known by using a mass spectrometer such as MALDI-TOFMS. Those skilled in the art can easily measure these.

The aliphatic compound (B) used in the present embodiment is not limited to the following, but, for example, an aliphatic compound having a structure represented by the following general formulas (4), (5), and (6) Compounds.

Here, in the formulas (4), (5), and (6), R ₁₁ , R _12, and R ₁₃ are each independently an alkane residue having 1 to 30 carbon atoms or a substitution having 1 to 30 carbon atoms. Or an aralkyl group in which at least one hydrogen atom of an unsubstituted alkyl group is substituted with an aryl group having 6 to 20 carbon atoms, or at least one hydrogen atom in an aryl group having 6 to 20 carbon atoms is An alkylaryl group substituted with 30 substituted or unsubstituted alkyl groups. These groups may be groups containing alkene, alkyne, or cyclo ring.

In formula (4), A ₁ and A ₂ are each independently an ester bond, a thioester bond, an amide bond, a thioamide bond, an imide bond, a ureido bond, an imine bond, a urea bond, a ketoxime bond, an azo bond, An ether bond, a thioether bond, a urethane bond, a thiourethane bond, a sulfide bond, a disulfide bond, or a trisulfide bond.

In the formulas (5) and (6), A ₃ , A ₄ and A ₅ are each independently a hydroxyl group, acyl group, aldehyde group, carboxyl group, acetyl group, amino group, sulfo group or amidine group. , An azide group, a cyano group, a thiol group, a sulfenic acid group, an isocyanide group, a ketene group, an isocyanate group, a thioisocyanate group, a nitro group, or a thiol group.

  From the viewpoint of wear characteristics during sliding under a minute load which is an effect of the present embodiment, the structure represented by the general formulas (4), (5) and (6) in the aliphatic compound (B) is within the following range. It is preferable that

The number of carbon atoms in R _11, R _12, R ₁₃ is preferably 2 to 30, more preferably from 3 to 30, more preferably from 4 to 30.

  In formula (4), x represents an integer of 1 to 100, and an integer of 1 to 10 is preferable. y shows the integer of 1-1000, and the integer of 1-20 is preferable.

In formula (4), preferred A ₁ and A ₂ are each independently an ester bond, a thioester bond, an amide bond, an imide bond, a ureido bond, an imine bond, a urea bond, a ketoxime bond, an ether bond, or a urethane bond. More preferable A ₁ and A ₂ are each independently an ester bond, an amide bond, an imide bond, a ureido bond, an imine bond, a urea bond, a ketoxime bond, an ether bond, or a urethane bond.

In formulas (5) and (6), preferred A ₃ , A ₄ and A ₅ are each independently a hydroxyl group, acyl group, aldehyde group, carboxyl group, acetyl group, amino group, azide group, cyano group, A thiol group, an isocyanide group, a ketene group, an isocyanate group, and a thioisocyanate group, and more preferable A ₃ , A _4, and A ₅ are each independently a hydroxyl group, an acyl group, an aldehyde group, a carboxyl group, an acetyl group, An amino group, a cyano group, an isocyanide group, a ketene group, and an isocyanate group.

  Specific examples of the (B) aliphatic compound include, but are not limited to, amide, alcohol, fatty acid, ester of alcohol and fatty acid, ester of alcohol and dicarboxylic acid, polyoxyalkylene glycol And at least one selected from the group consisting of olefin compounds having an average degree of polymerization of 10 to 500.

  The amide may be a primary amide, a secondary amide, or a tertiary amide.

  Examples of primary amides include, but are not limited to, for example, acetamide, ethaneamide, propanamide, butanamide, pentanamide, hexaneamide, heptaneamide, octaneamide, nonaneamide, decanamide, undecanamide, laurylamide. , Laurylamide, tridecylamide, myristylamide, pentadecylamide, cetylamide, heptadecylamide, stearylamide, oleylamide, nonadecylamide, eicosylamide, serylamide, behenylamide, melylamide, hexyldecylamide, octyldodecylamide, benzamide olein Examples thereof include saturated or unsaturated amides such as acid amides and erucic acid amides.

  Examples of secondary amides include, but are not limited to, for example, N-methylbenzamide, N-oleyl palmitic acid amide, N-stearyl stearic acid amide, N-stearyl oleic acid amide, N-oleyl stearin Acid amide, N-stearyl erucic acid amide, methylene bis stearic acid amide, ethylene bis capric acid amide, ethylene bis lauric acid amide, ethylene bis stearic acid amide, ethylene bis behenic acid amide, ethylene bis oleic acid amide, ethylene bis erucic acid Saturated or unsaturated amides such as amide, hexamethylene bis stearic acid amide, hexamethylene bis behenic acid amide, hexamethylene bis oleic acid amide, m-xylylene bis stearic acid amide, m-xylylene bis lauric acid amide It is below.

  Examples of tertiary amides include, but are not limited to, N, N-distearyl adipic acid amide, N, N-distearyl sebacic acid amide, N, N-dioleyl adipic acid amide, Examples thereof include saturated or unsaturated amides such as N, N-dioleyl sebacic acid amide and N, N-distearylisophthalic acid amide.

  Among these, amides having 10 or more carbon atoms are preferable from the viewpoint of sliding efficiency. More preferred is an amide having 11 or more carbon atoms, and still more preferred is an amide having 13 or more carbon atoms. Particularly preferred among these are saturated aliphatic amides.

  The above amides may be used alone or in combination of two or more.

  As the alcohol, either a monohydric alcohol or a polyhydric alcohol may be used.

  Examples of monohydric alcohols include, but are not limited to, octyl alcohol, nonyl alcohol, decyl alcohol, undecyl alcohol, lauryl alcohol, tridecyl alcohol, myristyl alcohol, pentadecyl alcohol, cetyl alcohol, Saturated or saturated with heptadecyl alcohol, stearyl alcohol, oleyl alcohol, nonadecyl alcohol, eicosyl alcohol, ceryl alcohol, behenyl alcohol, melyl alcohol, hexyl decyl alcohol, octyldodecyl alcohol, decyl myristyl alcohol, decyl stearyl alcohol, unilin alcohol An unsaturated alcohol is mentioned.

  Examples of the polyhydric alcohol include, but are not limited to, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, butanediol, pentanediol, hexanediol, glycerin, diglycerin, and triglycerin. , Threitol, erythritol, pentaerythritol, arabitol, ribitol, xylitol, sorbite, sorbitan, sorbitol, mannitol.

  Among these, alcohols having 11 or more carbon atoms are preferable from the viewpoint of slidability efficiency. More preferred is an alcohol having 12 or more carbon atoms, and still more preferred is an alcohol having 13 or more carbon atoms. Particularly preferred among these are saturated alcohols.

  The said alcohol may be used individually by 1 type, and may be used in combination of 2 or more type.

  Examples of fatty acids include saturated fatty acids and unsaturated fatty acids. Specific examples of fatty acids include, but are not limited to, for example, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, undecyl acid, lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid Acid, pentadecylic acid, stearic acid, nanodecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptaconic acid, montanic acid, melicic acid, laccelic acid, undecylenic acid, oleic acid, elaidic acid, celetic acid, erucic acid, Examples include brassic acid, sorbic acid, linoleic acid, linolenic acid, arachidonic acid, propiolic acid, and stearic acid.

  Among these, fatty acids having 10 or more carbon atoms are preferable from the viewpoint of slidability efficiency. More preferred are fatty acids having 11 or more carbon atoms, and even more preferred are fatty acids having 12 or more carbon atoms. Of these, saturated fatty acids are particularly preferred.

  The said fatty acid may be used individually by 1 type, and may be used in combination of 2 or more type.

  Further, it may be a naturally occurring fatty acid containing these components or a mixture thereof. These fatty acids may be substituted with hydroxy groups, or may be synthetic fatty acids obtained by carboxyl-modifying the end of uniline alcohol, which is a synthetic aliphatic alcohol.

  Examples of the ester of alcohol and fatty acid include, but are not limited to, esters of alcohol and fatty acid shown below.

  As the alcohol, either a monohydric alcohol or a polyhydric alcohol may be used. Examples of monohydric alcohols include, but are not limited to, methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, amyl alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol, nonyl alcohol, decyl alcohol, Undecyl alcohol, lauryl alcohol, tridecyl alcohol, myristyl alcohol, pentadecyl alcohol, cetyl alcohol, heptadecyl alcohol, stearyl alcohol, oleyl alcohol, nonadecyl alcohol, eicosyl alcohol, ceryl alcohol, behenyl alcohol, melyl alcohol, hexyl decyl Alcohol, octyldodecyl alcohol, decyl myristyl alcohol, decyl stearyl alcohol, Uni Saturated or unsaturated alcohols such as emissions alcohol.

  Examples of the polyhydric alcohol include, but are not limited to, polyhydric alcohols containing 2 to 6 carbon atoms. Specific examples of such a polyhydric alcohol include, but are not limited to, for example, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, butanediol, pentanediol, hexanediol, and glycerin. , Diglycerol, triglycerol, pentaerythritol, arabitol, ribitol, xylitol, sorbite, sorbitan, sorbitol, mannitol and the like.

  Examples of fatty acids include, but are not limited to, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, undecylic acid, lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, pentadecyl acid Acid, stearic acid, nanodecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptaconic acid, montanic acid, melicic acid, laccellic acid, undecylenic acid, oleic acid, elaidic acid, celetic acid, erucic acid, brassic acid, Examples include sorbic acid, linoleic acid, linolenic acid, arachidonic acid, propiolic acid, and stearic acid. Further, it may be a naturally occurring fatty acid containing these components or a mixture thereof. These fatty acids may be substituted with a hydroxy group. Moreover, the synthetic fatty acid which carried out carboxyl modification | denaturation of the terminal of unilin alcohol which is a synthetic aliphatic alcohol may be sufficient. Among the above-described alcohol, fatty acid, and ester of alcohol and fatty acid, ester of fatty acid having 12 or more carbon atoms and alcohol is preferable, and ester of fatty acid having 12 or more carbon atoms and alcohol having 10 or more carbon atoms is more preferable. Further, an ester of a fatty acid having 12 to 30 carbon atoms and an alcohol having 10 to 30 carbon atoms is more preferable.

  The ester of the said alcohol and a fatty acid may be used individually by 1 type, and may be used in combination of 2 or more type.

  Examples of the ester of alcohol and dicarboxylic acid include, but are not limited to, octyl alcohol, nonyl alcohol, decyl alcohol, undecyl alcohol, lauryl alcohol, tridecyl alcohol, myristyl alcohol, pentadecyl alcohol, cetyl. Alcohol, heptadecyl alcohol, stearyl alcohol, oleyl alcohol, nonadecyl alcohol, eicosyl alcohol, ceryl alcohol, behenyl alcohol, melyl alcohol, hexyl decyl alcohol, octyldodecyl alcohol, decyl myristyl alcohol, decyl stearyl alcohol, unilin alcohol, etc. Saturated or unsaturated primary alcohol and oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimeline , Suberic acid, azelaic acid, sebacic acid, Undekanin acid, Burashirin acid, maleic acid, fumaric acid, monoesters of dicarboxylic acids such as glutaconic acid, diesters and mixtures thereof. Among these esters of alcohol and dicarboxylic acid, esters of alcohol having 10 or more carbon atoms and dicarboxylic acid are preferable.

  The ester of the said alcohol and dicarboxylic acid may be used individually by 1 type, and may be used in combination of 2 or more type.

  The polyoxyalkylene glycol is not limited to the following, and examples thereof include the following three types. The first polyoxyalkylene glycol is a polycondensate having alkylene glycol as a monomer. Examples of such polycondensates include, but are not limited to, polyethylene glycol, polypropylene glycol, block polymers of ethylene glycol and propylene glycol, and the like. The preferable range of the polymerization degree of these polycondensates is 5 to 1000, and the more preferable range is 10 to 500. The second polyoxyalkylene glycol is an ether compound of the polycondensate mentioned in the first polyoxyalkylene glycol and an aliphatic alcohol. Examples of such ether compounds include, but are not limited to, polyethylene glycol oleyl ether (ethylene oxide polymerization degree 5-50), polyethylene glycol cetyl ether (ethylene oxide polymerization degree 5-50), polyethylene glycol, and the like. Stearyl ether (ethylene oxide polymerization degree 5-30), polyethylene glycol lauryl ether (ethylene oxide polymerization degree 5-30), polyethylene glycol tridecyl ether (ethylene oxide polymerization degree 5-30), polyethylene glycol nonylphenyl ether (ethylene oxide polymerization) Degree 2-100), polyethylene glycol octyl phenyl ether (ethylene oxide polymerization degree 4-50), etc. are mentioned. The third polyoxyalkylene glycol is an ester compound of the polycondensate mentioned in the first polyoxyalkylene glycol and a higher fatty acid. Examples of such ester compounds include, but are not limited to, polyethylene glycol monolaurate (ethylene oxide polymerization degree 2 to 30), polyethylene glycol monostearate (ethylene oxide polymerization degree 2 to 50), Examples include polyethylene glycol monooleate (ethylene oxide polymerization degree 2 to 50).

  The said polyoxyalkylene glycol may be used individually by 1 type, and may be used in combination of 2 or more type.

  The olefin compound having an average degree of polymerization of 10 to 500 is not particularly limited, and examples thereof include shrack wax, beeswax, whale wax, shellac wax, wool wax, carbana wax, wood wax, rice wax, candelilla wax, These include wax wax, paraffin wax, microcrystalline wax, montan wax, Fischer-Tropsch wax, polyethylene wax, polypropylene wax, and their high-density polymerization type, low-density polymerization type, oxidation type, acid-modified type, and special monomer-modified type. It is done.

  The said olefin compound may be used individually by 1 type, and may be used in combination of 2 or more type.

  The content of the aliphatic compound (B) having a molecular weight of 10,000 or less used in the present embodiment is 1 to 5 parts by mass with respect to 100 parts by mass of (A) polyacetal. (B) By setting the content of the aliphatic compound having a molecular weight of 10,000 or less to 1 part by mass or more, the polyacetal resin composition has a wear characteristic during sliding under a minute load even when a colorant is blended. Can be improved. (B) The lower limit of the content of the aliphatic compound having a molecular weight of 10,000 or less is more preferably 1.3 parts by mass, and even more preferably 1.5 parts by mass. On the other hand, by setting the content of the aliphatic compound having a molecular weight of 10,000 or less (B) to 5 parts by mass or less, it is possible to suppress a decrease in rigidity of the polyacetal resin composition and maintain applicability to gears and the like. . (B) The upper limit of the content of the aliphatic compound having a molecular weight of 10,000 or less is preferably 4.5 parts by mass, more preferably 4.3 parts by mass, and even more preferably 4.0 parts by mass.

  The polyacetal resin composition of the present embodiment improves the wear characteristics during sliding under a minute load when a colorant is blended by strictly controlling the content range of the (B) aliphatic compound as described above. In addition, when sliding at a high load, the wear characteristics are excellent, and the noise can be suppressed.

<(C) Colorant>
Next, the colorant (C) that can be used in this embodiment will be described in detail.

  Examples of the colorant (C) include, but are not limited to, inorganic pigments and organic dyes and pigments.

  Examples of the inorganic pigment include inorganic pigments generally used for coloring a resin. Specific examples of the inorganic pigment include, but are not limited to, zinc sulfide, titanium oxide, zinc oxide, iron oxide, barium sulfate, titanium dioxide, barium sulfate, hydrous chromium oxide, chromium oxide, and aluminum. Cobalt acid, barite powder, 1 type of zinc yellow, 2 types of zinc yellow, ferric ferric cyanide kalykaline, titanium yellow, cobalt blue, ultramarine blue, cadmium, nickel titanium, lithopone, strontium, amber, senna, azurite, malachite, azuro Malachite, opiment, real gar, cinnabar, turquoise, chalcopyrite, yellow ocher, tail belt, rhosenna, rhomber, cassel earth, chalk, plaster, burnt senna, burnt amber, lapis lazuli, azurite, malachite, coral powder, white mica , Baltic Blue, Cerulean Blue, Cobalt Violet, Cobalt Green, Zinc White, Titanium White, Light Red, Chrome Oxide Green, Mars Black, Billijan, Yellow Ocher, Alumina White, Cadmium Yellow, Cadmium Red, Vermilion, Talc, White Carbon, Clay, mineral bio red, rose cobalt violet, silver white, gold powder, bronze powder, aluminum powder, Prussian blue, aureolin, titanium mica, carbon black, acetylene black, lamp black, furnace black, vegetable black, bone charcoal, calcium carbonate, Examples include bitumen.

  In order to further improve the wear characteristics during sliding under a minute load, it is preferable to use an inorganic pigment having a Mohs hardness of 6 or less. Specific examples of such an inorganic pigment include, but are not limited to, zinc oxide, titanium yellow, cobalt blue, and carbonate.

  In the present embodiment, the Mohs hardness can be measured by a Mohs hardness meter.

  Examples of organic dyes include, but are not limited to, for example, condensed azo, quinone, furotacyanine, monoazo, diazo, polyazo, anthraquinone, heterocyclic, pennon, quinacridone Organic dyes such as thioindico, berylene, dioxazine, and phthalocyanine.

  From the viewpoint of the thermal stability of the polyacetal resin composition, the organic dyes and pigments include condensed azo, quinone, furacocyanin, anthraquinone, heterocyclic, pennon, quinacridone, thioindico, berylene, dioxazine. Or organic dyes of phthalocyanine type are preferred. More preferred are condensed azo, quinone, furothocyanin, anthraquinone, heterocyclic, pennon, quinacridone, berylene, or phthalocyanine organic dyes. More preferred are organic dyes of quinone, furothocyanin, anthraquinone, heterocyclic, quinacridone, berylene, or phthalocyanine.

  (C) Content of a coloring agent is the range of 0.01-5 mass parts with respect to 100 mass parts of (A) polyacetal resin.

  (C) By making content of a coloring agent 5 mass parts or less, even if it is a case where a coloring agent is mix | blended, the polyacetal resin composition can improve the abrasion characteristic at the time of a micro load sliding. (C) The upper limit of the content of the colorant is more preferably 4.5 parts by mass, still more preferably 4.0 parts by mass, and particularly preferably 3.5 parts by mass.

  On the other hand, by setting the content of (C) the colorant to 0.01 parts by mass or more, the polyacetal resin composition can maintain sufficient colorability. (C) The minimum of content of a coloring agent becomes like this. Preferably it is 0.03 mass part, More preferably, it is 0.05 mass part, More preferably, it is 0.1 mass part.

  The polyacetal resin composition of the present embodiment improves the wear characteristics at the time of minute load sliding by strictly controlling the content range of (C) the colorant as described above, and further at the time of high load sliding. In this case, the wear characteristics are excellent and the noise can be suppressed.

  (C) The colorant is preferably a particle.

  From the viewpoint of improving wear characteristics during sliding under a minute load, the particle size of the colorant (C) is preferably 500 nm or less, more preferably 300 nm or less, and even more preferably 100 nm or less. (C) As a method for measuring the particle size of the colorant, a method using a powder image analysis apparatus such as PITA-3 may be mentioned. Those skilled in the art can easily measure these. In the case of a fine colorant (C) having a particle size in the above range, even inorganic pigments having a Mohs hardness or higher can be used because they have little adverse effect on wear characteristics.

<(D) Polyolefin resin>
Next, the (D) polyolefin resin that can be used in this embodiment will be described in detail.

  It is preferable that the polyacetal resin composition of this embodiment contains 0.5-5 mass parts of (D) polyolefin resin with respect to 100 mass parts of (A) polyacetal resin.

  (D) As for content of polyolefin resin, it is more preferred that it is 0.5-4.5 mass parts, and it is still more preferred that it is 1.0-4.0 mass parts.

The (D) polyolefin resin used in the present embodiment is a homopolymer of an olefinic compound represented by the following general formula (7) and a co-polymer having a main monomer of the olefinic compound represented by the following general formula (7). One or more polyolefin resins selected from the group consisting of coalesced and modified products thereof are preferred.

In the formula (7), R ₂₁ is a hydrogen atom or a methyl group, R ₂₂ is a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, a carboxyl group, an alkylated carboxy group containing 2 to 5 carbon atoms, An acyloxy group having 2 to 5 carbon atoms or a vinyl group is represented.

  Other monomers can be appropriately selected from monomers polymerizable with the olefinic compound represented by the above general formula (7).

  (D) polyolefin resin used for this embodiment is polyethylene; polypropylene; ethylene-α-olefin copolymer; ethylene acrylate copolymer having an acrylate unit content of 5 to 30% by weight; polyolefin ( A structure in which the block of d1) and the block of the hydrophilic polymer (d2) are repeatedly bonded alternately through at least one bond selected from the group consisting of an ester bond, an amide bond, an ether bond, a urethane bond and an imide bond. It is preferable that it is 1 or more types chosen from the group which consists of block polymer which has these;

  Specific examples of the polyolefin (d1) are not limited to the following, and examples thereof include polyethylene, polypropylene, polybutadiene, and the like. Specific examples of the hydrophilic polymer (d2) are not limited to the following, and examples thereof include polyvinyl acetate, polymethyl methacrylate, and polylactic acid.

  The (D) polyolefin resin that can be used in the present embodiment is not limited to the following, and examples thereof include polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-butene copolymer, and polypropylene-butene copolymer. Examples thereof include a polymer, polybutene, hydrogenated polybutadiene, ethylene-acrylic acid ester copolymer, ethylene-methacrylic acid ester copolymer, ethylene-acrylic acid copolymer, and ethylene-vinyl acetate copolymer.

  (D) A modified polyolefin resin (modified product) can be used without any problem as the polyolefin resin. The modified product includes a graft copolymer obtained by grafting one or more vinyl compounds different from the polymer forming the olefin resin; α, β-unsaturated carboxylic acid (acrylic acid, methacrylic acid, maleic acid) Acid, fumaric acid, itaconic acid, citraconic acid, nadic acid, etc.) or modified with an acid anhydride (with a peroxide if necessary); copolymerized olefinic compound and acid anhydride It is done.

  These (D) polyolefin resins described above can be used alone or in a mixture.

  Among these, as (D) polyolefin resin, polyethylene (high pressure method low density polyethylene, linear low density polyethylene, ultra low density polyethylene), ethylene-propylene copolymer, ethylene-butene copolymer, ethylene-octene A copolymer is preferred.

  The (D) polyolefin resin used in the present embodiment preferably has a melt flow rate (hereinafter also referred to as “MFR”) of 0.01 to 50 g / 10 min at 190 ° C. and a load of 2.16 kg.

  (D) By setting the MFR of the polyolefin resin within this range, it is possible to suppress the deterioration of the friction and wear characteristics under a minute load condition, and to suppress the generation of squeal.

  (D) The lower limit of the MFR of the polyolefin resin is more preferably 0.02 g / 10 minutes, still more preferably 0.05 g / 10 minutes, and particularly preferably 0.07 g / 10 minutes.

  Further, the upper limit of the MFR of the (D) polyolefin resin is more preferably 40 g / 10 minutes, further preferably 30 g / 10 minutes, and particularly preferably 2.5 g / 10 minutes.

  The melting point of the (D) polyolefin resin is not particularly limited, but is preferably in the range of 30 to 230 ° C, more preferably in the range of 50 to 200 ° C, and particularly preferably in the range of 90 to 170 ° C. .

<Other ingredients>
The polyacetal resin composition of the present embodiment can contain various stabilizers that have been used in conventional polyacetal resin compositions as long as the object of the present invention is not impaired. Examples of the stabilizer include, but are not limited to, the following antioxidants, formaldehyde and formic acid scavengers. These may be used alone or in combination of two or more.

  The antioxidant is preferably a hindered phenol antioxidant from the viewpoint of improving the thermal stability of the polyacetal resin composition.

  Examples of the hindered phenol antioxidant include, but are not limited to, n-octadecyl-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) -propionate, n-octadecyl-3- (3′-methyl-5′-t-butyl-4′-hydroxyphenyl) -propionate, n-tetradecyl-3- (3 ′, 5′-di-t-butyl-4′- Hydroxyphenyl) -propionate, 1,6-hexanediol-bis- (3- (3,5-di-tert-butyl-4-hydroxyphenyl) -propionate), 1,4-butanediol-bis- (3- (3,5-di-t-butyl-4-hydroxyphenyl) -propionate), triethylene glycol-bis- (3- (3-t-butyl-5-methyl-4-hydroxy) Phenyl) - propionate) and the like.

  In addition, the hindered phenol-based antioxidant is not limited to the following. For example, tetrakis- (methylene-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) pro Pionate methane, 3,9-bis (2- (3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy) -1,1-dimethylethyl) -2,4,8,10 -Tetraoxaspiro (5,5) undecane, N, N'-bis-3- (3 ', 5'-di-t-butyl-4-hydroxyphenol) priionyl hexamethylenediamine, N, N'- Tetramethylenebis-3- (3′-methyl-5′-t-butyl-4-hydroxyphenol) propionyldiamine, N, N′-bis- (3- (3,5-di-t-butyl-4- Hydroxy Enol) propionyl) hydrazine, N-salicyloyl-N′-salicylidenehydrazine, 3- (N-salicyloyl) amino-1,2,4-triazole, N, N′-bis (2- (3- (3 Mention may also be made of 5-di-butyl-4-hydroxyphenyl) propionyloxy) ethyl) oxyamide.

  Among the hindered phenol-based antioxidants described above, from the viewpoint of improving the thermal stability of the polyacetal resin composition, triethylene glycol-bis- (3- (3-t-butyl-5-methyl-4-hydroxyphenyl) -Propionate), tetrakis- (methylene-3- (3 ', 5'-di-tert-butyl-4'-hydroxyphenyl) propionate) methane.

  Formaldehyde and formic acid scavengers are not limited to, for example, compounds containing formaldehyde reactive nitrogen and polymers thereof, alkali metal or alkaline earth metal hydroxides, inorganic acid salts, and Examples include carboxylates.

  The compound containing formaldehyde-reactive nitrogen and the polymer thereof are not limited to the following, but examples thereof include dicyandiamide, melamine, a co-condensate of melamine and formaldehyde, nylon 4-6, nylon 6, and nylon 6 -6, nylon 6-10, nylon 6-12, nylon 12, nylon 6 / 6-6, nylon 6 / 6-6 / 6-10, nylon 6 / 6-12 and other polyamide resins, poly-β-alanine And polyacrylamide. Among these, co-condensates of melamine and formaldehyde, polyamide resins, poly-β-alanine and polyacrylamide are mentioned. From the viewpoint of improving the thermal stability of the polyacetal resin composition, the polyamide resin and poly-β-alanine are included. Is more preferable.

  Examples of the alkali metal or alkaline earth metal hydroxide, inorganic acid salt, and carboxylate include, but are not limited to, hydroxides such as sodium, potassium, magnesium, calcium, and barium. And carbonates, phosphates, silicates, borates and carboxylates of the above metals. From the viewpoint of improving the thermal stability of the polyacetal resin composition, a calcium salt is specifically preferable, and the calcium salt is not limited to the following, but examples thereof include calcium hydroxide, calcium carbonate, calcium phosphate, and silicic acid. Calcium, calcium borate, and fatty acid calcium salts (calcium stearate, calcium myristate, etc.) can be mentioned. These fatty acids may be substituted with a hydroxyl group. Among these, fatty acid calcium salts (calcium stearate, calcium myristate, etc.) are more preferable from the viewpoint of improving the thermal stability of the polyacetal resin composition.

  A preferred combination of the various stabilizers described above is particularly triethylene glycol-bis- (3- (3-tert-butyl-5-methyl-4-hydroxyphenyl)-from the viewpoint of improving the thermal stability of the polyacetal resin composition. Propionate) or tetrakis- (methylene-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionate) hindered phenolic antioxidants represented by methane, especially polyamide resins and poly A combination of a polymer containing formaldehyde-reactive nitrogen typified by β-alanine and a fatty acid salt of an alkaline earth metal typified by a fatty acid calcium salt.

  The amount of each of the stabilizers mentioned above is 0.1 to 2 parts by mass of an antioxidant, for example, a hindered phenol-based antioxidant, and a formaldehyde or formic acid scavenger for 100 parts by mass of the polyacetal resin (A). For example, the polymer containing formaldehyde-reactive nitrogen is preferably 0.1 to 3 parts by mass, and the alkaline earth metal fatty acid salt is preferably 0.1 to 1 part by mass.

≪Method for producing polyacetal resin composition≫
In the polyacetal resin composition of the present embodiment, (B) 1 to 5 parts by mass of an aliphatic compound having a molecular weight of 10,000 or less and (C) a colorant 0. It can manufacture by melt-kneading the raw material component containing 01-5 mass parts.

  As a device for producing the polyacetal resin composition of the present embodiment, a kneader that is generally used can be applied. The kneading machine is not limited to the following, and for example, a uniaxial or multi-axial kneading extruder, a roll, a Banbury mixer or the like may be used. Among these, a twin-screw extruder equipped with a decompression device and side feeder equipment is particularly preferable.

≪Molded body≫
The molded product of the present embodiment includes the above-described polyacetal resin composition.

  The molded product of the present embodiment can be obtained by molding the polyacetal resin composition described above.

  The method for molding the polyacetal resin composition is not particularly limited, and a known molding method can be applied. For example, extrusion molding, injection molding, vacuum molding, blow molding, injection compression molding, decorative molding, other material molding, gas assist injection molding, foam injection molding, low pressure molding, ultra thin injection molding (ultra high speed injection molding), Molding can be performed by any of molding methods such as in-mold composite molding (insert molding, outsert molding).

  As a use of the molded product of this embodiment obtained from the above-mentioned polyacetal resin composition, a use requiring dimensional accuracy and high durability is preferable.

Although it does not limit to the following as a use of the molded object of this embodiment, For example, the use of a general polyacetal resin is mentioned. Specific examples of such applications include, but are not limited to, for example, cams, sliders, levers, arms, clutches, felt clutches, idler gears, pulleys, rollers, rollers, key stems, key tops, shutters. , Reels, shafts, joints, shafts, bearings, mechanical parts represented by guides, etc .; outsert molded resin parts, insert molded resin parts, chassis, trays, side plates, printers, and copiers Components for automation equipment; VTR (Video Tape Recorder), video movies, digital video cameras, cameras, and parts for cameras or video equipment represented by digital cameras; cassette players, DAT, LD (Laser Disk), MD (Mini Disk ), CD (Compact Disk) [CD-ROM (Read Only Memory), Including D-R (Recordable), CD-RW (Rewritable)], DVD (Digital Video Disk) [DVD-ROM, DVD-R, DVD + R, DVD-RW, DVD + RW, DVD-R DL, DVD + R DL, DVD- RAM (Random Access Memory, including DVD-Audio), Blu-ray (registered trademark) Disc, HD-DVD, and other optical disk drives; MFD, MO, navigation system, and music and video represented by mobile personal computers Or parts for communication equipment represented by information equipment, mobile phones and facsimiles; parts for electrical equipment; parts for electronic equipment. In addition, the molded body of the present embodiment includes fuel-related parts represented by gasoline tanks, fuel pump modules, valves, gasoline tank flanges, etc. as automobile parts; door locks, door handles, window regulators, speaker grills, etc. Parts around doors represented by: Seat belt peripheral parts represented by slip rings for seat belts, press buttons, etc .; parts such as combination switch parts, switches, clips, etc .; Mechanical parts for taking in and out; wash basin, drain outlet, and drain valve opening / closing mechanism parts; vending machine opening / closing part locking mechanism, product discharge mechanism parts; clothing cord stopper, adjuster, button; sprinkling nozzle, sprinkling hose Connecting joints; stair railing and floor support Built supplies; disposable camera, toys, fasteners, chains, conveyors, buckle, sports equipment, vending machines, furniture, musical instruments, can also be suitably used as industrial parts typified by the housing equipment.
In addition, since wear characteristics during sliding with a minute load are improved, it can be suitably used for HDD internal parts (for example, lamps, latches, etc.) and watch internal parts (gears, balances, ankles, escape wheels).
The polyacetal resin composition of the present embodiment can be applied to a molded body with a high load as described above and a molded body with a minute load, and exhibits excellent sliding characteristics in any molded body. It is an excellent polyacetal resin composition that can be used.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to the Example mentioned later.

  Evaluation items for the polyacetal resin compositions and molded articles of Examples and Comparative Examples are shown below.

1) Physical property evaluation
[1] Sliding test at minute load Using an EC-75NII molding machine manufactured by Toshiba Machine Co., Ltd., setting the cylinder temperature to 205 ° C and mold temperature 120 ° C, injection time 35 seconds, cooling time 15 seconds A multi-purpose test piece based on ISO294-1 was obtained by molding the polyacetal resin compositions obtained in the examples and comparative examples under the injection conditions described above. This test piece was dried in an atmosphere of 80 ° C. for 60 minutes to obtain a sliding test measurement sample. About the obtained sample, Nanotribometer 2 (CTX Instruments Co., Ltd. product TTX-NTR2 type) was used in an environment of 23 ° C. and 50% humidity, load 100 mN, sliding speed 200 mm / sec, reciprocating distance 200 μm, reciprocating. The sliding test was conducted under the condition of 500,000 times. As a counterpart material, a SUJ2 test piece (sphere having a diameter of 1.5 mm) was used.

[2] Sliding test at high load Using an EC-75NII molding machine manufactured by Toshiba Machine Co., Ltd., the cylinder temperature is set to 205 ° C, the mold temperature is set to 120 ° C, the injection time is 35 seconds, and the cooling time is 15 seconds. A molded product was obtained by molding the polyacetal resin compositions obtained in the examples and comparative examples under the injection conditions described above. This molded product was dried in an atmosphere of 80 ° C. for 60 minutes to obtain a sliding test measurement sample. About the obtained sample, load 19.6N, linear velocity 30mm / sec, reciprocating distance 20mm, reciprocating frequency 5,000 times, using a reciprocating friction and wear tester (Toyo Seimitsu Co., Ltd. AFT-15MS type) The sliding test was carried out at 23 ° C. and a humidity of 50%. As the counterpart material, a SUS304 test piece (sphere having a diameter of 5 mm) was used.

[3] Sounds when sliding on high-load gears FANUC Co., Ltd. injection molding machine (trade name “ROBOSHOTα-50iA”) was used under conditions of a cylinder temperature of 200 ° C. and a mold temperature of 80 ° C. By molding the polyacetal resin compositions obtained in the examples and comparative examples, a gear having a pitch circle diameter of 60 mm, module 1, number of teeth of 60, helix angle of 0 degree, tooth width of 5 mm, and web thickness of 2 mm was obtained. After this gear was left for 24 hours in an environment of 23 ° C. and 50 RH, it was set on the driven side of a gear durability tester manufactured by Toshiba, and a gear of the same shape made by Tenac C-45201 was set on the drive side. Next, the rotation speed on the pitch circle is set to 0.5 m / s and the torque is set to 4.5 kgf · cm, and the gear durability tester is operated, and continuously for 2.5 hours under conditions of 23 ° C. and humidity 50%. Drove. The loudness of the driven and driving gears during the operation was evaluated according to the following criteria as the squeal characteristics during high-load sliding. The evaluation is divided into an initial period (elapsed time: 0 to 0.5 hours), an intermediate period (elapsed time: 1.0 to 1.5 hours), and a late period (elapsed time: 2.0 to 2.5 hours). It was done.
A: Extremely small B: Small C: Standard D: Large E: Extremely large

[4] Wear amount
The wear amount (wear cross-sectional area) of the sample after the sliding test of [1] and [2] was measured using OPTELICS H1200 (manufactured by Lasertec). The wear cross-sectional area was the average of the values measured at n = 3, and was rounded off to two significant figures. Since this value is the wear cross-sectional area, it was evaluated that the lower the value, the better the wear characteristics.

2) Raw material components The raw material components of the polyacetal resin compositions and molded bodies used in Examples and Comparative Examples are described below.

(A) Polyacetal resin / polyacetal resin (A-1)
A polyacetal resin (A-1) was prepared as follows.
First, fully dehydrated and dried paraformaldehyde was thermally decomposed at 150 ° C. and passed several times through a cooling trap to obtain a formaldehyde gas having a purity of 99.9%. This formaldehyde gas, C ₁₈ H ₃₇ O (CH ₂ CH ₂ O) ₇₀ H (ethylene oxide adduct of stearyl alcohol) added with 2,6-di-t-butyl-p-cresol and tetrabutylammonium as a catalyst A toluene solution of acetate was simultaneously supplied to the polymerization machine at the same time for 3 hours to produce a polymer. The polymerization temperature at this time was maintained at 60 ° C. In addition, C ₁₈ H ₃₇ O (CH ₂ CH ₂ O) ₇₀ H (stearyl alcohol) with a small amount of 2,6-di-t-butyl-p-cresol added at 110 parts by mass of formaldehyde gas per hour The amount of the ethylene oxide adduct and the toluene solution of tetrabutylammonium acetate was 500 parts by mass per hour. The concentration of tetrabutylammonium acetate in toluene is 1.0 × 10 ⁻⁴ mol / L, and C ₁₈ H ₃₇ O (CH ₂ CH ₂ O with 2,6-di-t-butyl-p-cresol added thereto. ) The concentration of ₇₀ H was 5.0 × 10 ⁻³ mol / L. The obtained toluene solution containing the polymer was continuously withdrawn according to the supply amount, and the polymer was separated from the toluene solution by filtration. The polymer after filtration was sufficiently washed with acetone and then vacuum dried at 60 ° C. to obtain 289 parts by mass of a white polymer. 50 parts by mass of the polymer thus obtained was mixed with 500 parts by mass of acetic anhydride and 0.1 part by mass of potassium acetate, heated at 139 ° C. for 3 hours and cooled. Thereafter, the polymer was sufficiently washed with acetone in the same manner as described above, and dried in the same manner as above to recover 49 parts by mass of a polyacetal linear polymer. Triethylene glycol bis- (3- (3-t-butyl-5-methyl-4-hydroxyphenyl) -propionate) (Ciba Geigy), a hindered phenol antioxidant, with respect to 100 parts by mass of the recovered polymer (Trade name “IRGANOX245” manufactured by the company) 0.5 parts by mass and 0.5 parts by mass of poly-β-alanine are added and mixed, and then melt-kneaded with a single screw extruder with a vent, to obtain a polyacetal polymer. A composition was obtained. The obtained polyacetal polymer composition was designated as polyacetal resin (A-1). The polyacetal resin (A-1) had a flexural modulus of 2550 MPa and a melt flow rate of 22.0 g / 10 min (ISO-1133 condition D).

  In this example, the flexural modulus was measured by Autograph AG-I (ISO 178) manufactured by Shimadzu Corporation.

次に、前記重合機から排出されたポリマーを、トリエチルアミン１％水溶液中に投入し、重合触媒の失活を完全に行った後、そのポリマーを濾過、洗浄して、粗ポリアセタール共重合体を得た。
濾過洗浄後の粗ポリアセタール共重合体１質量部に対し、第４級アンモニウム化合物として、トリエチル（２−ヒドロキシエチル）アンモニウム蟻酸塩を窒素の量に換算して２０質量ｐｐｍになるよう添加し、それらを均一に混合した後、１２０℃で乾燥した。
このようにして得られたポリアセタールブロック共重合体を、ポリアセタール樹脂（Ａ−２）とした。ポリアセタール樹脂（Ａ−２）は、曲げ弾性率が２５５０ＭＰａであり、メルトフローレートが１０．０ｇ／１０分（ＩＳＯ−１１３３ 条件Ｄ）であった。 ・ Polyacetal resin (A-2)
A polyacetal resin (A-2) was prepared as follows.
A twin-screw paddle type continuous polymerization machine with a jacket through which a heat medium can pass was adjusted to 80 ° C. Boron trifluoride di-n-butyl etherate in which trioxane containing 4 ppm of water and formic acid is combined at 40 mol / hour, 1,3-dioxolane as cyclic formal is dissolved at 2 mol / hour in cyclohexane as a polymerization catalyst In an amount of 5 × 10 ⁻⁵ mol per mol of trioxane, and a hydroxylated hydrogenated polybutadiene (number average molecular weight Mn = 2330) represented by the following formula (8) as a chain transfer agent in 1 mol of trioxane: The polymerization was carried out by continuously feeding the polymerizer in an amount of 1 × 10 ⁻³ mol.

Next, the polymer discharged from the polymerizer is put into a 1% aqueous solution of triethylamine to completely deactivate the polymerization catalyst, and then the polymer is filtered and washed to obtain a crude polyacetal copolymer. It was.
Triethyl (2-hydroxyethyl) ammonium formate is added as a quaternary ammonium compound to 1 part by mass of the crude polyacetal copolymer after filtration and washing so that the amount of nitrogen is 20 ppm by mass. After mixing uniformly, it dried at 120 degreeC.
The polyacetal block copolymer thus obtained was designated as polyacetal resin (A-2). The polyacetal resin (A-2) had a flexural modulus of 2550 MPa and a melt flow rate of 10.0 g / 10 min (ISO-1133 condition D).

・ Polyacetal resin (A-3)
A polyacetal resin (A-3) was prepared as follows.
A biaxial self-cleaning type polymerization machine with a jacket through which a heat medium can pass (L / D = 8 (L: distance (m) from raw material supply port to discharge port of polymerization machine, D: inner diameter of polymerization machine ( m) The same applies hereinafter))) to 80 ° C. Continuously adding 0.25 × 10 ⁻³ mol of trioxane to 1 mol of trioxane, 4 kg / hr of trioxane, 128.3 g / hr of 1,3-dioxolane as a comonomer, and methylal as a chain transfer agent to the polymerizer. did.
Further, boron trifluoride di-n-butyl etherate as a polymerization catalyst was continuously added to the polymerization machine at 1.5 × 10 ⁻⁵ mol with respect to 1 mol of trioxane to carry out polymerization. The polyacetal copolymer discharged from the polymerization machine was put into a 0.1% aqueous solution of triethylamine to deactivate the polymerization catalyst.
An aqueous solution containing choline formate (triethyl-2-hydroxyethylammonium formate) as a quaternary ammonium compound with respect to 100 parts by mass of the polyacetal copolymer after filtering the deactivated polyacetal copolymer. After adding 1 part by mass and mixing uniformly, it was dried at 120 ° C. The amount of choline formate added was 20 mass ppm in terms of nitrogen. The addition amount of the choline formate was adjusted by adjusting the concentration of the choline formate in the aqueous solution containing the added choline formate. The dried polyacetal copolymer is supplied to a vented twin screw extruder, and 0.5 parts by mass of water is added to 100 parts by mass of the melted polyacetal copolymer in the extruder, and the extruder set temperature is 200 ° C. The unstable end portion of the polyacetal copolymer was decomposed and removed in a residence time of 7 minutes in the extruder.
0.3 parts by mass of triethylene glycol-bis- [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) -propionate] as an antioxidant is added to the polyacetal copolymer having the unstable terminal portion decomposed. It was added and extruded as a strand from the die section of the extruder while being devolatilized under a condition of a vacuum of 20 Torr with an extruder equipped with a vent, and pelletized.
The polyacetal block copolymer thus obtained was designated as polyacetal resin (A-3). The polyacetal resin (A-3) had a flexural modulus of 2600 MPa and a melt flow rate of 30.0 g / 10 min (ISO-1133 condition D).

(B) Aliphatic compound / aliphatic compound (B-1)
Ethylene bis-stearic acid amide: molecular weight 593 Kitahiro Chemical Co., Ltd.

・ Aliphatic compounds (B-2)
Ethylene glycol distearate: molecular weight 623 Kitahiro Chemical Co., Ltd.

・ Aliphatic compounds (B-3)
Cetyl myristate: molecular weight 453, manufactured by Kitahiro Chemical Co., Ltd.

・ Aliphatic compounds (B-4)
Polyethylene glycol distearate: weight average molecular weight (Mw) 12000 manufactured by Kao Chemical Co., Ltd.

  In this example, the molecular weight of the (B) aliphatic compound is measured by liquid chromatography / mass spectrometry when the molecular weight is 1000 or less, and by gel permeation chromatography when the molecular weight exceeds 1000. It was measured.

(C) Colorant / Colorant (C-1)
Titanium oxide (particle size: 150 nm, Mohs hardness: 7.3)

・ Coloring agent (C-2)
Zinc oxide (particle size: 200 nm, Mohs hardness: 4.5)

・ Colorant (C-3)
Iron oxide (particle size: 140 nm, Mohs hardness: 6)

  In this example, the particle size of the colorant (C) was measured with a powder image analyzer (PITA-3). Further, the Mohs hardness of the colorant (C) was measured with a Mohs hardness meter.

(D) Polyolefin resin / Polyolefin resin (D-1)
Polyethylene (melting point: 125 ° C., melt flow rate: 0.1 g / 10 min (ISO 1133 condition D) or less, density: 930 kg / m ³ ) (Sunfine SH810 manufactured by Asahi Kasei Chemicals Corporation)

・ Polyolefin resin (D-2)
Ethylene acrylate copolymer (ethyl acrylate content: 8% by weight, melting point: 105 ° C., melt flow rate (JIS K692-2 conditions): 0.8 g / 10 min) (NUC-6510, manufactured by Nihon Unicar Corporation)

・ Polyolefin resin (D-3)
Polyoxyethylene polypropylene glycol block polymer (polyoxyethylene polypropylene glycol: 99.9%, melting point: 59 ° C.) (Emalgen PP290, manufactured by Kao Corporation)

[Production of polyacetal resin composition]
A polyacetal resin composition was produced using a twin screw extruder.
In this example, a twin-screw extruder (TEM-26SS extruder manufactured by Toshiba Machine Co., Ltd. (L / D = 48, with a vent) was used. The cylinder temperature was set to 200 ° C., and the blended material was measured from a quantitative feeder. Then, extrusion was performed under the conditions of an extrusion rate of 15 kg / hour and a screw rotation speed of 150 rpm, to obtain a polyacetal resin composition.

[Examples 1 to 21]
Each component was mix | blended in the ratio shown in Table 1 and 2, and melt-kneading was performed by the above-mentioned manufacturing method.
The extruded polyacetal resin composition was pelletized with a strand cutter.
Using the obtained polyacetal resin composition pellets, a sliding test at a high load, measurement of noise, a sliding test at a minute load, and a measurement of wear were performed by the above-described methods. The measurement and evaluation results are shown in Tables 1 and 2.

[Comparative Examples 1-5]
Each component was mix | blended in the ratio shown in Table 1 and 2, and melt-kneading was performed by the above-mentioned manufacturing method.
The extruded polyacetal resin composition was pelletized with a strand cutter.
Using the obtained polyacetal resin composition pellets, a sliding characteristic test at high load, measurement of noise, sliding test at minute load, and measurement of wear were performed by the above-described methods. The measurement and evaluation results are shown in Tables 1 and 2.

  What changed the molecular weight of B component of Example 2 was made into the comparative example 1. FIG. Comparing the results of Example 2 and Comparative Example 1, both have excellent wear characteristics under high load sliding conditions, but the wear characteristics differ greatly under low load sliding conditions, and the molecular weight is 10,000 or less. It was found that the wear characteristics under the sliding condition with a minute load were further improved in Example 2 using the B component.

  Moreover, what changed the addition amount of B component of Example 2 was set as Comparative Examples 2 and 3. It was found that Comparative Example 2 with a small amount of B component was excellent in wear characteristics under high load sliding conditions, but the wear characteristics deteriorated and squealed under high load sliding conditions. It was found that in Comparative Example 3 in which the addition amount of the B component was excessively added, the wear characteristics were deteriorated both under high load sliding conditions and under minute load sliding conditions. On the other hand, in Example 2 in which the amount of B component added was controlled within an appropriate range, the wear characteristics under high load and minute load sliding conditions were further improved, and the noise during high load sliding was further suppressed. I understood that I could do it. Therefore, it turned out that it is effective to control the addition amount of B component to a specific range (for example, 1-5 mass parts) with respect to 100 mass parts of A component.

  What remove | excluded B component of Example 13 and 14 was made into Comparative Examples 5 and 4 in order. Comparing the results of Examples 13 and 14 with Comparative Examples 5 and 4, Examples 13 and 14 to which the B component was added showed wear characteristics and noise during sliding under high load, and sliding under minute load. It was found to have excellent wear characteristics at. Therefore, it turned out that addition of B component is effective.

  As shown in Tables 1 and 2, in Examples 1 to 21, polyacetal resin compositions having excellent wear characteristics and noise during high-load sliding and wear characteristics during micro-load sliding were obtained.

  The polyacetal resin composition of the present invention has industrial applicability as a material for gears, electronic device parts, and housing equipment.

Claims (6)

  (A) The polyacetal resin composition containing 1 to 5 parts by mass of an aliphatic compound having a molecular weight of 10,000 or less and (C) 0.01 to 5 parts by mass of a colorant with respect to 100 parts by mass of the polyacetal resin. .   (A) The polyacetal resin composition of Claim 1 in which a polyacetal resin contains a block polymer.   (A) The polyacetal resin composition of Claim 2 whose ratio of the block polymer in 100 mass% of polyacetal resins is 50 mass% or more.   The polyacetal resin composition as described in any one of Claims 1-3 containing 0.5-5 mass parts of (D) polyolefin resin with respect to 100 mass parts of (A) polyacetal resin.   (D) Polyolefin resin is polyethylene; polypropylene; ethylene-α-olefin copolymer; ethylene acrylate copolymer having an acrylate unit content of 5 to 30% by weight; polyolefin (d1) block; A block polymer having a structure in which the block of the hydrophilic polymer (d2) is alternately and repeatedly bonded through at least one bond selected from the group consisting of an ester bond, an amide bond, an ether bond, a urethane bond and an imide bond; Moreover, the polyacetal resin composition of Claim 4 which is 1 or more types chosen from the group which consists of these modified substances.   The molded object containing the polyacetal resin composition as described in any one of Claims 1-5.