JP2014040547A - Polyoxymethylene resin composition for intermittent type slide component with metals and intermittent type slide component using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyoxymethylene resin composition for an intermittent type slide component having a small dimensional change when sliding intermittently with metals, excellent durability while securing practically sufficient productivity, and to provide a component using the same.SOLUTION: A polyoxymethylene resin composition for an intermittent type slide component with metals has a stiffness of 2500 MPa or more, impact resistance of 10 kJ/mor more, friction coefficient of 0.15 or less and contains polyoxymethylene containing 0 to 1.0 mol of a co-monomer unit based on 100 mol of an oxymethylene unit.

Description

  The present invention relates to a polyoxymethylene resin composition for intermittent sliding parts against metal and an intermittent sliding part using the same.

  Polyoxymethylene resin is a resin with high mechanical strength and rigidity, excellent oil resistance and organic solvent resistance, balanced in a wide temperature range, and easy to process. It is used for a wide range of applications centering on mechanical parts of automobiles, automobile parts and other mechanical parts. Polyoxymethylene resins are originally excellent in self-lubricating properties and are therefore used in various sliding parts and parts of sliding parts.

  In the sliding parts made of polyoxymethylene, the movement of the parts (continuous movement or reciprocating movement, etc.), the shape of various sliding parts (surface and surface, surface and line, surface and point, etc.), sliding Surface contact state (sliding surface is always constant (hereinafter also referred to as “continuous”) or updated (hereinafter also referred to as “discontinuous”)), sliding environment (temperature) , Humidity, presence or absence of grease, etc.), the friction resistance and wear resistance of the member change. In particular, with respect to the friction resistance and wear resistance in which the resin is interposed, a simple tendency for improving the friction resistance and wear resistance has not been derived, and many proposals have been made so far.

  About a polyoxymethylene resin composition, in order to improve friction resistance and abrasion resistance, various structures are mentioned. For example, a synthetic resin sliding member composition containing polyoxymethylene resin (POM), silicon carbide, and tetrafluoroethylene polymer resin (PTFE) is used for discontinuous contact / non-contact composed of a pin and stainless steel. It has been reported that the continuous movement is excellent in friction resistance and wear resistance (see, for example, Patent Document 1). Also, discontinuous contact / discontinuity between a member formed of a composition comprising polyoxymethylene resin (POM) and a fatty acid ester and a counterpart material formed with a specific Rockwell hardness other than polyoxymethylene resin. It has been reported that excellent slidability and quietness can be obtained when sliding in a smooth motion (see, for example, Patent Document 2).

  Various reports have been made on the combination of a member and a mating member of the member when sliding. For example, in a shaft slider for a window raising / lowering mechanism, by combining a spherical body made of polybutylene terephthalate (PBT) resin and a shaft made of polyoxymethylene resin, looseness and the like are generated in discontinuous contact and discontinuous movement. Has been reported to be improved (for example, see Patent Document 3). In addition, a friction-resistant connector for modular link type conveyor belts is superior in friction and wear resistance in continuous contact and discontinuous movement by combining a rod coated with polyester or polyamide and an acetal link. (For example, refer to Patent Document 4).

  Various studies have also been made on improving the dimensional accuracy of polyoxymethylene resins and molded articles thereof. For example, the inclusion of a polyoxymethylene having a branch composed of a specific oxyalkylene unit is excellent in the fluidity of the melt, so that it is possible to easily obtain a molded article excellent in appearance and dimensional stability. (For example, refer to Patent Document 5). Also, it has been proposed that a molded product obtained by filling a mold cavity with a specific crystalline resin and carbon dioxide can improve dimensional accuracy without limiting the molecular weight distribution and resin composition of the resin. (For example, refer to Patent Document 6).

JP-A-8-239682 JP 2011-252566 A JP-A-10-227176 Special table 2009-506962 gazette JP 2003-105048 A JP 2002-331554 A

  In recent years, there has been a demand for a polyoxymethylene intermittent sliding component capable of suppressing dimensional changes when repeatedly sliding. Of course, these polyoxymethylene intermittent sliding parts are required to have the same productivity and good durability as conventional ones.

  However, the various members using the polyoxymethylene resin disclosed in Patent Documents 1 to 6 still have room for improvement in terms of dimensional change when sliding and improvement in durability.

  Therefore, in the present invention, while ensuring sufficient productivity in practice, the dimensional change when sliding intermittently with a metal is small, and a poly-metal intermittent sliding part having excellent durability is provided. An object is to provide an oxymethylene resin composition and an intermittent sliding part using the same.

  As a result of intensive studies to solve the above problems, the present inventors have used a part formed using a specific polyoxymethylene resin composition, and thus when the metal slides intermittently with a metal. The inventors have found that an intermittent sliding part made of polyoxymethylene having a small dimensional change and excellent durability can be obtained, and the present invention has been completed.

That is, the present invention is as follows.
[1]
The rigidity is 2500 MPa or more, the impact resistance is 10 kJ / m ² or more, the friction coefficient is 0.15 or less,
A polyoxymethylene resin composition for an intermittent metal-to-metal sliding part, comprising polyoxymethylene containing 0 to 1.0 mol of a comonomer unit with respect to 100 mol of oxymethylene unit.
[2]
It has the member (I) formed using the polyoxymethylene resin composition for a metal-to-metal intermittent type sliding part according to the preceding item [1], and a metal counterpart (II), and the member (I ) And the mating material (II) are in contact with each other, an intermittent sliding part made of polyoxymethylene.
[3]
The polyoxymethylene intermittent sliding component according to item [2], wherein the polyoxymethylene resin composition has a rigidity of 2650 MPa or more.
[4]
The polyoxymethylene intermittent sliding component according to [2] or [3], wherein the impact resistance of the polyoxymethylene resin composition is 13 kJ / m ² or more.
[5]
The intermittent sliding part made of polyoxymethylene according to any one of [2] to [4], wherein the coefficient of friction of the polyoxymethylene resin composition is 0.12 or less.
[6]
The polyoxymethylene intermittent sliding component according to any one of [2] to [5], wherein the polyoxymethylene resin composition includes a polyoxymethylene homopolymer.
[7]
The polyoxymethylene intermittent sliding component according to any one of [2] to [6], wherein the polyoxymethylene resin composition contains a solid lubricant at room temperature.
[8]
The polyoxymethylene intermittent sliding component according to any one of [2] to [7], wherein the polyoxymethylene resin composition includes a fatty acid ester-based lubricant.
[9]
The intermittent sliding part made of polyoxymethylene according to any one of [2] to [8], wherein the polyoxymethylene resin composition contains a hydrazide compound.

  According to the present invention, polyoxy, which is a metal-to-metal intermittent-type sliding part having a small dimensional change when sliding intermittently with a metal and having excellent durability while ensuring practically sufficient productivity. A methylene resin composition and an intermittent sliding part made of polyoxymethylene are obtained.

It is the figure which showed an example (Example 1) of the polyoxymethylene-made intermittent sliding parts which concern on this embodiment. It is the figure which showed an example (example 2) of the polyoxymethylene intermittent slide parts which concern on this embodiment. It is the figure which showed an example (Example 3) of the polyoxymethylene intermittent slide parts which concern on this embodiment. It is the figure which showed an example (Example 4) of the polyoxymethylene intermittent slide parts which concern on this embodiment. It is the figure which showed an example (Example 5) of the polyoxymethylene intermittent slide parts which concern on this embodiment. It is a photograph of the test piece used for evaluation of the polyoxymethylene intermittent sliding part in a present Example. It is a dimension image figure of the test piece used for evaluation of the intermittent sliding part made from polyoxymethylene in a present Example. It is a photograph which shows the shape of the gear part of the test piece used for evaluation of the polyoxymethylene intermittent type | mold sliding component in a present Example. It is an image figure of the evaluation part of the evaluation apparatus used for evaluation of the polyoxymethylene intermittent sliding component in a present Example. It is a photograph which shows the evaluation part of the evaluation apparatus used for evaluation of the polyoxymethylene intermittent sliding component in a present Example.

  Hereinafter, modes for carrying out the present invention (hereinafter referred to as “the present embodiment”) will be described. The present invention is not limited to the following description, and various modifications can be made within the scope of the gist thereof.

  The usage aspect of the polyoxymethylene resin composition for intermittent metal type sliding parts, the polyoxymethylene intermittent type sliding parts, and the polyoxymethylene intermittent type sliding parts of this embodiment will be described in detail sequentially.

[Intermittent sliding parts made of polyoxymethylene]
The polyoxymethylene intermittent sliding part of this embodiment is
A member (I) formed using the polyoxymethylene resin composition, and a metal counterpart (II);
The member (I) and the counterpart material (II) are in contact with each other,
The polyoxymethylene resin composition has a rigidity of 2500 MPa or more, an impact resistance of 10 kJ / m ² or more, a friction coefficient of 0.15 or less, and 0 to 1.0 mol per 100 mol of oxymethylene units. Polyoxymethylene containing a comonomer unit of

[Parts of polyoxymethylene intermittent sliding parts (I)]
The polyoxymethylene intermittent sliding component of this embodiment has a member (I) formed using the polyoxymethylene resin composition for an intermittent metal sliding component.

[Polyoxymethylene resin composition]
The polyoxymethylene resin composition for intermittent metal-to-metal sliding parts used in the present embodiment contains the following polyoxymethylene (A) as a main component, has a rigidity of 2500 MPa or more, and has an impact resistance of 10 kJ / m ^2. The friction coefficient is 0.15 or less, and the polyoxymethylene (A) contained is not particularly limited as long as it contains 0 to 1.0 mol of a comonomer unit with respect to 100 mol of the oxymethylene unit. An agent may be included. The polyoxymethylene (A) that can be the main component is described below.

(Polyoxymethylene (A))
The polyoxymethylene (A) that can be used in the present embodiment is specifically a polyoxymethylene homopolymer (A-1) having only an oxymethylene group in the main chain, or preferably in the molecule. An example is a polyoxymethylene copolymer (A-2) having an oxyalkylene unit having 2 or more carbon atoms. In particular, the polyoxymethylene resin composition used in the present embodiment preferably contains a polyoxymethylene homopolymer (A-1). As a result, the intermittent sliding parts made of polyoxymethylene are smaller in dimensional change when sliding intermittently with metal while ensuring practically sufficient productivity, and more excellent durability is obtained. There is a tendency.

  The polyoxymethylene (A) contains 0 to 1.0 mol of comonomer units, preferably 0 to 0.8 mol, preferably 0 to 0.5 mol, per 100 mol of oxymethylene units. More preferably. Since the content of comonomer units other than oxymethylene units is within the preferred range, the polyoxymethylene intermittent sliding parts slid intermittently with the metal while ensuring practically sufficient productivity. There is a tendency that the dimensional change at the time is smaller and more excellent durability is obtained.

The quantification of the comonomer unit can be determined by the following procedure using ¹ H-NMR method. The obtained polyoxymethylene (A) was dissolved in hexafluoroisopropanol (HFIP) so as to have a concentration of 1.5% by mass over 24 hours, and ¹ H-NMR analysis was performed using this dissolved solution. From the ratio of the integral value of the assigned peak of the methylene unit and a comonomer unit other than the oxymethylene unit (for example, oxyalkylene unit), the mole ratio of the comonomer unit (b) to 100 mol (a) of the oxymethylene unit (b / A) can be determined.

  The polyoxymethylene homopolymer (A-1) and the polyoxymethylene copolymer (A-2) can be produced by the following polymerization process, terminal stabilization process and granulation process.

<Polyoxymethylene homopolymer (A-1)>
(1) Polymerization process The polyoxymethylene homopolymer (A-1) used in the present embodiment represents a polymer having an oxymethylene group in the main chain. Both ends of the polymer chain may be blocked with an ester group or an ether group. The polymerization mode in the production of the polyoxymethylene homopolymer (A-1) is carried out using a known slurry polymerization method (for example, the method described in Japanese Patent Publication No. 47-6420 or Japanese Patent Publication No. 47-10059). be able to. Thereby, the crude polyoxymethylene whose terminal is not stabilized can be obtained.

1) Monomer As a monomer used for the production of polyoxymethylene homopolymer (A-1), cyclic oligomers such as formaldehyde or trioxane which is a trimer thereof or tetraoxane which is a tetramer can be used. At this time, in order to continuously obtain a polyoxymethylene homopolymer (A-1) having a stable molecular weight, it is preferable to use a formaldehyde gas which is purified and has a low impurity concentration and is stable. A known method (for example, a method described in Japanese Patent Publication No. 5-32374 and Japanese Patent Publication No. 2001-521916) can be used as a purification method of formaldehyde.

  The formaldehyde gas used in the present embodiment is preferably one that contains as little impurities as possible, such as water, methanol, formic acid, and the like, which has a polymerization termination and chain transfer action during the polymerization reaction. If these impurities are not contained as much as possible, an unexpected chain transfer reaction can be avoided and a polyoxymethylene homopolymer (A-1) having a target molecular weight can be easily obtained. In particular, the water content is preferably 100 ppm or less, and more preferably 50 ppm or less.

2) Chain transfer agent Although it does not specifically limit as a chain transfer agent used for manufacture of polyoxymethylene homopolymer (A-1), Specifically, generally alcohols and acid anhydrides can be used. In order to obtain a block polymer or a branched polymer, polyol, polyether polyol, or polyether polyol / alkylene oxide may be used.

  Moreover, it is preferable to use a chain transfer agent that does not contain impurities as much as possible. Especially about water, it is preferable that it is 2000 ppm or less, and it is more preferable that it is 1000 ppm or less. As a method for obtaining these chain transfer agents with a small amount of impurities, for example, a general-purpose chain transfer agent having a water content exceeding a specified amount is obtained, and this is bubbled with dry nitrogen, and an adsorbent such as activated carbon or zeolite. And the like, and the like. The chain transfer agent used here may be used alone or in combination of two or more.

3) Polymerization catalyst Although it does not specifically limit as a polymerization catalyst used for the polymerization reaction in manufacture of a polyoxymethylene homopolymer (A-1), Specifically, an onium salt type polymerization catalyst is mentioned. As the onium salt-based polymerization catalyst used for the polymerization reaction, for example, one represented by the following formula (1) can be used.
[R ₁ R ₂ R ₃ R ₄ M] ⁺ X ⁻ (1)

In the above formula (1), R ₁ , R ₂ , R ₃ and R ₄ each independently represents an alkyl group, M represents an element having a lone electron pair, and X represents a nucleophilic group.

  Among the onium salt polymerization catalysts represented by the above formula (1), quaternary ammonium salt compounds and quaternary phosphonium salt compounds are preferably used. More preferably, tetramethylammonium bromide, dimethyl distearyl ammonium acetate, tetraethylphosphonium iodide, or tributylethylphosphonium iodide is used.

4) Reactor The polymerization reactor in the production of the polyoxymethylene homopolymer (A-1) is not particularly limited. Specifically, the reaction tank is equipped with a batch type stirrer, a continuous type kneader, and a twin screw. A continuous extrusion kneader, a biaxial paddle type continuous mixer, or the like can be used. The outer peripheries of these cylinders preferably have a structure capable of heating or cooling the reaction mixture.

(2) Terminal stabilization step As a method for blocking the terminal stabilization of the crude polyoxymethylene with an ether group, there is a method described in JP-B 63-452, and a method for blocking with an acetyl group is the United States. A method of using a large amount of acid anhydride described in Japanese Patent No. 3,459,709 in a slurry state and an acid anhydride gas described in US Pat. No. 3,172,736 There is a method in the gas phase. In the present embodiment, any of the above methods can be adopted and is not particularly limited.

  The etherifying agent used for blocking the unstable terminal of the crude polyoxymethylene with an ether group is not particularly limited, and specific examples include orthoesters, usually an aliphatic acid or an aromatic acid, Orthoesters with aliphatic alcohols, alicyclic alcohols or aromatic alcohols can be mentioned. Specific examples of such orthoesters include methyl or ethyl orthoformate, methyl or ethyl orthoacetate, methyl or ethyl orthobenzoate, and orthocarbonates such as ethyl orthocarbonate.

  The etherification reaction is not particularly limited, and specific examples include medium-strength organic acids such as p-toluenesulfonic acid, acetic acid and hydrobromic acid, or medium-strength mineral acids such as dimethyl and diethyl sulfate. For example, the Lewis acid type catalyst may be introduced in an amount of 0.001 to 0.02 parts by mass with respect to 1 part by mass of the etherifying agent.

  Although it does not specifically limit as a preferable solvent used for etherification reaction, Specifically, low boiling point aliphatics, such as a pentane, hexane, a cyclohexane, and benzene; Alicyclic and aromatic hydrocarbons; Methylene chloride, chloroform, and four And organic solvents such as halogenated lower aliphatic compounds such as carbon chloride.

On the other hand, when the unstable terminal of the crude polyoxymethylene is blocked with an ester group, the organic acid anhydride used for esterification is not particularly limited, but specifically, an organic compound represented by the following formula (2) is used. An acid anhydride is mentioned.
R ₅ COOCOR ₆ (2)

In the above formula (2), _{R 5} and _{R 6} represents an alkyl group or an aryl group independently. R ₅ and R ₆ may be the same or different.

  Among the organic acid anhydrides represented by the above formula (2), propionic anhydride, benzoic anhydride, acetic anhydride, succinic anhydride, maleic anhydride, glutaric anhydride, phthalic anhydride and the like are preferable, and acetic anhydride is more preferable. preferable. An organic acid anhydride may be used individually by 1 type, and can also be used in combination of 2 or more type.

  Moreover, in the method of performing ester group blocking in the gas phase, it is preferable to perform terminal blocking after removing the onium salt polymerization catalyst by the method described in JP-A No. 11-92542. If the onium salt polymerization catalyst in the polyoxymethylene is removed, the polyoxymethylene decomposition reaction of the onium salt polymerization catalyst can be avoided when end-capping, and the polymer yield in the stabilization reaction can be reduced. While being able to make it favorable, coloring of polyoxymethylene can be suppressed.

It is preferable that the terminal of the polyoxymethylene homopolymer (A-1) is blocked with an ether group and / or an ester group so that the concentration of the terminal hydroxyl group is reduced to 5 × 10 ⁻⁷ mol / g or less. A terminal hydroxyl group concentration of 5 × 10 ⁻⁷ mol / g or less is preferred because it is excellent in thermal stability and tends to maintain the quality of the original polyoxymethylene resin. More preferably, the concentration of the terminal hydroxyl group is 0.5 × 10 ⁻⁷ mol / g or less, and more preferably 0.3 × 10 ⁻⁷ mol / g or less.

(3) Granulation step After the terminal stabilized polyoxymethylene homopolymer (A-1) powder is dried, it may be granulated using an extruder to improve the handleability. At this time, it is preferable to perform granulation by melt kneading while adding a known stabilizer that can be added to ordinary polyoxymethylene. When performing melt-kneading, it is preferable to carry out replacement with an inert gas and deaeration with single-stage and multistage vents in order to maintain the quality and working environment. The temperature at the time of melt-kneading is preferably not lower than the melting point of the polyoxymethylene homopolymer (A-1) and not higher than 250 ° C.

<Polyoxymethylene copolymer (A-2)>
(1) Polymerization step In the polymerization form in the production of the polyoxymethylene copolymer (A-2) used in the present embodiment, 1.0 mol or less of a comonomer unit other than the oxymethylene unit is contained with respect to 100 mol of the oxymethylene unit. , 0.8 mol or less is preferable, and 0.5 mol or less is more preferable.

Both ends of the polyoxymethylene copolymer (A-2) may be blocked with an ester group or an ether group. In the production of the polyoxymethylene copolymer (A-2), a known polymerization method (for example, US Pat. No. 30,273,352, US Pat. No. 3,803,094, German Patent No. 1161411, Patent method 1495228, German patent invention No. 1720358, German patent invention No. 3018898, Japanese Patent Laid-Open No. 58-98322, and Japanese Patent Laid-Open No. 7-70267) Can do. By such a polymerization process, a crude polymer in which the terminal of the polyoxymethylene copolymer is not stabilized is obtained.
Materials such as main monomers used in the polymerization step will be described below.

1) Main monomer As the main monomer used in the production of the polyoxymethylene copolymer (A-2), it is preferable to use formaldehyde, or a cyclic oligomer such as trioxane, which is a trimer thereof, or tetraoxane, which is a tetramer. Here, the “main monomer” in this specification refers to a monomer unit that is contained in an amount of 50% by mass or more based on the total amount of monomers.

2) Comonomer As the comonomer used for producing the polyoxymethylene copolymer (A-2), it is preferable to use a cyclic ether compound and / or a cyclic formal compound having an oxyalkylene unit having 2 or more carbon atoms in the molecule.

  Such a cyclic ether compound and a cyclic formal compound are not particularly limited. Specifically, ethylene oxide, propylene oxide, 1,3-dioxolane, 1,3-propanediol formal, 1,4-butanediol formal, 1,5-pentanediol formal, 1,6-hexanediol formal, diethylene glycol formal, 1,3,5-trioxepane, 1,3,6-trioxycan, and the resulting polymer may constitute a branched or crosslinked structure. One compound or a mixture of two or more selected from the group consisting of mono- or di-glycidyl compounds is preferred.

  When polymerizing the polyoxymethylene copolymer (A-2), a main monomer and a comonomer that do not contain impurities having a polymerization stopping action and a chain transfer action during the polymerization reaction such as water, methanol and formic acid are used as much as possible. It is preferable.

  By using a main monomer and a comonomer containing as little impurities as possible, an unexpected chain transfer reaction can be avoided, thereby obtaining a polymer having a desired molecular weight. In particular, the content of impurities that induce hydroxyl groups in the polymer end groups is preferably 30 ppm by mass or less, more preferably 10 ppm by mass or less, and even more preferably 3 ppm by mass or less with respect to the total monomer amount.

  As a method for obtaining a desired low-impurity main monomer and comonomer, a known method (for example, the main monomer is described in JP-A-3-123777 or JP-A-7-33761, the comonomer). Can be used as described in JP-A-49-62469 or JP-A-5-271217.

3) Chain transfer agent It is preferable to use a chain transfer agent in the polymerization step of the polyoxymethylene copolymer (A-2). Although it does not specifically limit as a chain transfer agent, Specifically, it is preferable to use lower aliphatic alcohols, such as dialkyl acetal of formaldehyde, its oligomer, and methanol, ethanol, propanol, isopropanol, and butanol. The alkyl group of the dialkyl acetal is preferably a lower aliphatic alkyl group such as methyl, ethyl, propyl, isopropyl and butyl.

  In order to obtain a long-chain branched polyoxymethylene copolymer (A-2), it is preferable to use a polyether polyol and an alkylene oxide adduct of the polyether polyol. Moreover, as a chain transfer agent other than the above, a polymer having one or more groups selected from the group consisting of a hydroxyl group, a carboxyl group, an amino group, an ester group, and an alkoxy group may be used.

  Furthermore, the said chain transfer agent may be used individually by 1 type, and may use 2 or more types. In any case, it is preferable to obtain a polyoxymethylene copolymer (A-2) having a small number of unstable terminals.

4) Polymerization catalyst The polymerization catalyst used in the polymerization step of the polyoxymethylene copolymer (A-2) is preferably a cationically active catalyst such as Lewis acid, protonic acid, and ester or anhydride of protonic acid.

  The Lewis acid is not particularly limited, and specific examples include boric acid, tin, titanium, phosphorus, arsenic and antimony halides. More specifically, boron trifluoride, tin tetrachloride, titanium tetrachloride, phosphorus pentafluoride, phosphorus pentachloride and antimony pentafluoride, and their complex compounds or salts can be mentioned. Among these, boron trifluoride; boron trifluoride hydrate; a coordination complex compound of an organic compound containing an oxygen atom or a sulfur atom and boron trifluoride is preferable, boron trifluoride diethyl ether, trifluoride Boron di-n-butyl ether is more preferred.

  Further, the protonic acid, its ester or anhydride is not particularly limited, and specifically, perchloric acid, perchloric anhydride, trifluoromethanesulfonic acid, trifluoromethanesulfonic anhydride, perchloric acid-tertiary butyl ester. , Acetyl perchlorate, and trimethyloxonium hexafluorophosphate. Moreover, you may use together the catalyst which reduces the production | generation of the terminal formate group described in Unexamined-Japanese-Patent No. 05-05017, for example as needed.

For example, when using a trioxane and a cyclic ether compound and / or a cyclic formal compound, the amount of the polymerization catalyst is preferably 1 × 10 ⁻⁶ to 1 × 10 ⁻³ mol with respect to 1 mol of the total amount of monomers, and 5 × 10. ⁻⁶ to 1 × 10 ⁻⁴ mol is more preferable. When the usage-amount of a polymerization catalyst is in the said range, the reaction stability at the time of superposition | polymerization and the thermal stability of the molded object obtained will improve more.

  The polymerization catalyst is deactivated by introducing a polymer into an aqueous solution or an organic solvent solution containing a catalyst neutralization deactivator after the polymerization step, and generally stirring for several minutes to several hours in a slurry state. be able to.

  Such a catalyst neutralization deactivator is not particularly limited. Specifically, amines such as ammonia, triethylamine and tri-n-butylamine; hydroxides of alkali metals and alkaline earth metals; inorganic acids A salt; and one or more selected from the group consisting of organic acid salts.

  Also, a method of deactivating the polymerization catalyst by contacting a vapor such as ammonia or triethylamine with polyoxymethylene, at least one selected from the group consisting of hindered amines, triphenylphosphine and calcium hydroxide, and polyoxymethylene A method of deactivating the catalyst by bringing them into contact with a mixer can also be used.

(2) Terminal Stabilization Step and Granulation Step By decomposing and removing unstable terminal portions contained in the crude polymer of the polyoxymethylene copolymer (A-2) obtained by the polymerization step described above, the thermal stability is improved. A high polyoxymethylene copolymer (A-2) is obtained.

  The method for decomposing and removing the unstable terminal portion contained in the crude polymer is not particularly limited. For example, a known basic substance can be obtained using a vented single-screw extruder or a vented twin-screw extruder. In the presence of a decomposition / removal agent to be described later, there is a method in which the crude polymer is melted to decompose and remove unstable terminal portions.

  When performing melt-kneading for terminal stabilization, it is preferable to perform replacement with an inert gas and deaeration with a single-stage or multistage vent in order to maintain the quality and working environment.

  The temperature at the time of melt-kneading is preferably not lower than the melting point of the polyoxymethylene copolymer (A-2) and not higher than 260 ° C.

  Furthermore, it is preferable to perform granulation by melt mixing while adding a known stabilizer that can be added to ordinary polyoxymethylene.

1) Decomposition remover The decomposition remover used for decomposing and removing the unstable terminal portion contained in the crude polymer of the polyoxymethylene copolymer (A-2) is not particularly limited. Specifically, ammonia, triethylamine and trioxyamine are used. Examples include known basic substances such as aliphatic amines such as butylamine; alkali metal or alkaline earth metal hydroxides such as calcium hydroxide; inorganic weak acid salts; and organic weak acid salts.

Among the decomposition and removal agents, those containing at least one quaternary ammonium compound represented by the following formula (3) are preferable. Such a quaternary ammonium compound can be suitably used in a method for treating a thermally unstable terminal.
[R ₇ R ₈ R ₉ R ₁₀ N ⁺ ] _n Y ⁿ⁻ (3)
In said formula (3), R < ₇ >, R <_8> , R < ₉ > and R < ₁₀ > are respectively independently a C1-C30 unsubstituted alkyl group or substituted alkyl group; C6-C20 aryl group; Carbon An aralkyl group in which an unsubstituted alkyl group having 1 to 30 or a substituted alkyl group is substituted with at least one aryl group having 6 to 20 carbon atoms; and an aryl group having 6 to 20 carbon atoms having at least one carbon atom It represents either one selected from the group consisting of -30 unsubstituted alkyl groups or alkylaryl groups substituted with substituted alkyl groups. The unsubstituted alkyl group or the substituted alkyl group may be linear, branched, or cyclic. In the above unsubstituted alkyl group, aryl group, aralkyl group, and alkylaryl group, a hydrogen atom may be substituted with a halogen. n represents an integer of 1 to 3. Y represents any acid residue selected from the group consisting of a hydroxyl group, a carboxylic acid having 1 to 20 carbon atoms, a hydrogen acid, an oxo acid inorganic thioacid, and an organic thioacid having 1 to 20 carbon atoms.

  The quaternary ammonium compound is not particularly limited. Specifically, tetramethylammonium, tetraethylammonium, tetrapropylammonium, tetra-n-butylammonium, cetyltrimethylammonium, tetradecyltrimethylammonium, 1,6- Hexamethylenebis (trimethylammonium), decamethylene-bis- (trimethylammonium), trimethyl-3-chloro-2-hydroxypropylammonium, trimethyl (2-hydroxyethyl) ammonium, triethyl (2-hydroxyethyl) ammonium, tripropyl ( 2-hydroxyethyl) ammonium, tri-n-butyl (2-hydroxyethyl) ammonium, trimethylbenzylammonium, triethylbenzylammo , Tripropylbenzylammonium, tri-n-butylbenzylammonium, trimethylphenylammonium, triethylphenylammonium, trimethyl-2-oxyethylammonium, monomethyltrihydroxyethylammonium, monoethyltrihydroxyethylammonium, okdadecyltri (2- And hydroxides such as hydroxyethyl) ammonium and tetrakis (hydroxyethyl) ammonium.

  Other examples of quaternary ammonium compounds include hydrogenates other than halogenated compounds such as hydrogen azide; sulfuric acid, nitric acid, phosphoric acid, carbonic acid, boric acid, chloric acid, iodic acid, silicic acid, perchloric acid Oxo acid salts such as chlorous acid, hypochlorous acid, chlorosulfuric acid, amidosulfuric acid, disulfuric acid and tripolyphosphoric acid; thioic acid salts such as thiosulfuric acid; formic acid, acetic acid, propionic acid, butanoic acid, isobutyric acid, pentanoic acid Also included are carboxylates such as caproic acid, caprylic acid, caprylic acid, benzoic acid and oxalic acid.

Among these, hydroxide (OH ⁻ ), sulfuric acid (HSO ⁴⁻ , SO ₄ ²⁻ ), carbonic acid (HCO ₃ ⁻ , CO ₃ ²⁻ ), boric acid (B (OH) ₄ ⁻ ), and carboxylic acid The salt of is preferred. Among such carboxylic acids, formic acid, acetic acid, and propionic acid are more preferable.

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

The addition amount of the quaternary ammonium compound is 0.05 to 50 mass ppm in terms of the amount of nitrogen derived from the quaternary ammonium compound represented by the following formula (α) with respect to the crude polymer. Is preferred.
Addition amount of quaternary ammonium compound = P × 14 / Q (α)

  In the above formula (α), P represents the concentration (mass ppm) of the quaternary ammonium compound relative to the crude polymer, “14” represents the atomic weight of nitrogen, and Q represents the molecular weight of the quaternary ammonium compound.

  A decomposition removing agent such as a quaternary ammonium compound may be added in advance before the crude polymer is melted, or may be added to the melted crude polymer.

  The decomposition / removal agent may be a combination of ammonia, triethylamine and boric acid compounds, which are known decomposition / removal agents, and a quaternary ammonium compound.

(Additive)
The polyoxymethylene resin composition used for forming the polyoxymethylene intermittent sliding part of the present embodiment may contain an additive. In particular, it is preferable that the lubricant (B) contains a specific amount. In addition, it is preferable to contain a specific amount of formaldehyde scavenger (C). Moreover, the other additive (D) may be included. In the present embodiment, “room temperature” means 23 ° C.

<Lubricant (B)>
The polyoxymethylene resin composition used for forming the polyoxymethylene intermittent sliding component of the present embodiment preferably contains a specific amount of the lubricant (B) as an additive.

  In the polyoxymethylene resin composition, the content of the lubricant (B) is preferably 0.01 parts by mass or more and less than 5 parts by mass, and 0.05 parts by mass or more and less than 2 parts by mass with respect to 100 parts by mass of (A). It is more preferable that it is 0.1 mass part or more and less than 1 mass part. By making the content of the lubricant (B) within a preferable range, the polyoxymethylene intermittent sliding component including the member (I) formed using the polyoxymethylene resin composition is practically sufficient production. There is a tendency that the dimensional change when sliding with the metal intermittently is smaller and better durability is obtained while securing the properties.

  The lubricant (B) is preferably solid at room temperature, more preferably has a melting point of 40 ° C. or higher, and further preferably 50 ° C. or higher. By setting the melting point of the lubricant (B) to the above preferred range, the polyoxymethylene intermittent-type sliding component including the member (I) formed using the polyoxymethylene resin composition is practically sufficiently produced. There is a tendency that the dimensional change when sliding with the metal intermittently is smaller and better durability is obtained while securing the properties. In general, the melting point refers to the temperature at which a solid melts and liquefies, but in addition to this, the melting point in this embodiment refers to a softening point in the case of an amorphous substance and a decomposition point in the case of a thermosetting resin. And Moreover, in this embodiment, melting | fusing point can be measured by the method as described in the below-mentioned Example.

  In the polyoxymethylene resin composition, the dispersed state of the lubricant (B) is preferably uniform, but depending on the type of the lubricant, it may be unevenly distributed on the surface.

  Although it does not specifically limit as a lubricant (B), Specifically, hydrocarbon type lubricants (paraffin wax, olefin wax, etc.), higher fatty acid type lubricants (stearic acid, palmitic acid, etc.) or these higher fatty acid Salt, higher alcohol lubricant (stearyl alcohol, behenyl alcohol, etc.), fatty acid amide lubricant (oleic acid amide, stearic acid amide, etc.), ester lubricant (fatty acid ester, aromatic ester, etc.), synthetic resin lubricant (Polyolefin, fluororesin), boron nitride, graphite, molybdenum disulfide and the like.

  As the lubricant (B) used in the present embodiment, a fatty acid ester lubricant is particularly preferable. As a result, the polyoxymethylene intermittent-type sliding component including the member (I) formed using the polyoxymethylene resin composition is intermittently slid with the metal while ensuring practically sufficient productivity. There is a tendency that the dimensional change at the time of the process is smaller, and more excellent durability is obtained.

  In this embodiment, the fatty acid ester lubricant refers to a compound in which a hydroxyl group of an aliphatic alcohol and a carboxyl group of a fatty acid are ester-bonded.

  The term “aliphatic alcohol” as used herein refers to a compound having a form in which a hydrogen atom of an aliphatic hydrocarbon is substituted with a hydroxyl group. Examples of such forms include monovalent, divalent and higher polyhydric alcohols depending on the number of hydroxyl groups, saturated alcohols and double bonds due to intramolecular bonds, unsaturated alcohols having triple bonds, and hydroxyl group bonds. There are primary alcohols, secondary alcohols, and tertiary alcohols depending on the carbon atoms. Examples of such aliphatic alcohols include, but are not limited to, methyl alcohol, ethyl alcohol, propyl alcohol, n-butyl alcohol, isobutyl alcohol, tert-butyl alcohol, n-amyl alcohol, 2-pentanol. , N-peptyl alcohol, n-octyl alcohol, n-nonyl alcohol, lauryl alcohol, myristyl alcohol, cetyl alcohol, vinyl alcohol, allyl alcohol, crotyl alcohol, methyl vinyl carbinol, allyl carbinol, etc. Monoalcohol: ethylene glycol, propylene glycol, trimethylene glycol, 1,4-butanediol, β-butylene glycol, 2,4-pentanediol, 2-methyl-2,4-butanedi , Γ-pentylene glycol, 1,4-hexanediol, 2,5-hexanediol, pentamethylene glycol, hexamethylene glycol, glycerin, 1,2,3-butanetriol, 1,2,3-pentanetriol 2,3,4-hexanetriol, 2-methyl-2-oxymethyl-1,3-propanediol, 2-isopropyl-2-oxymethyl-1,3-propanediol, trimethylolpropane, erythritol, 1, Examples thereof include aliphatic polyhydric alcohols such as 2,3,4-pentanetetrol, adnit, and alit. Among these, aliphatic saturated hydrocarbon-based polyhydric alcohols are preferable.

  The fatty acid here is a compound in a form in which a part of the aliphatic hydrocarbon is substituted with a carboxyl group. Such forms include, for example, saturated fatty acids (saturated aliphatic monocarboxylic acids, saturated aliphatic dicarboxylic acids, saturated aliphatic tricarboxylic acids, or branched ones), and unsaturated fatty acids. The saturated aliphatic monocarboxylic acid is not particularly limited. Specifically, formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, isovaleric acid, pivalic acid, caproic acid, octanoic acid, decanoic acid, Examples thereof include lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, and lignoceric acid. The saturated aliphatic dicarboxylic acid is not particularly limited, and specific examples include succinic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid and the like. Furthermore, the saturated aliphatic tricarboxylic acid is not particularly limited, and specific examples include 1,2,3-propanetricarboxylic acid, 1,3,5-pentanetricarboxylic acid, citric acid and isocitric acid. Furthermore, the unsaturated fatty acid is not particularly limited, and specific examples include acrylic acid, propiolic acid, methacrylic acid, crotonic acid, isocrotonic acid, oleic acid, ricinolenic acid, fumaric acid, maleic acid and the like. Among these, an aliphatic hydrocarbon fatty acid having 4 to 18 carbon atoms is preferable. The said lubricant (B) may be used individually by 1 type, or may use 2 or more types together.

<Formaldehyde scavenger (C)>
The polyoxymethylene resin composition used for forming the polyoxymethylene intermittent sliding part of this embodiment preferably contains a specific amount of a formaldehyde scavenger (C) as an additive. By including the formaldehyde scavenger (C), the polyoxymethylene intermittent sliding part including the member (I) formed using the polyoxymethylene resin composition is improved in productivity and intermittent with the metal. There is a tendency that the dimensional change when sliding is smaller and more excellent durability can be obtained.

  In the polyoxymethylene resin composition, the content of the formaldehyde scavenger (C) is preferably 0.01 parts by weight or more and less than 5 parts by weight, and 0.03 parts by weight or more and 2 parts by weight with respect to 100 parts by weight of (A). More preferably, it is more preferably 0.05 parts by mass or more and less than 1 part by mass.

  The formaldehyde scavenger (C) is not particularly limited, and specific examples include aminotriazine compounds, guanamine compounds, urea compounds, and hydrazide compounds. One of these formaldehyde scavengers (C) may be used alone, or two or more thereof may be used in combination.

  Although it does not specifically limit as an aminotriazine type compound, Specifically, melamine; Melamine condensates, such as melam, melem, and melon; Melamine resins, such as melamine formaldehyde resin; N, N ', N' '-mono, bis , Tris, tetrakis, pentakis, or hexakis (o-, m- or p-hydroxyphenylmethyl) melamine, and the like.

  Although it does not specifically limit as a guanamine type compound, Specifically, aliphatic guanamine type compounds, such as valerologamine, caproguanamine, heptanoguanamine, capriloganamin, stealoganamin; succinoguanamine, glutaloganamin, Alkylene bisguanamines such as adipoguanamine, pimeloganamin, suboguanamine, azeroguanamine, sebacoguanamine; cyclohexanecarboguanamine, norbornenecarboguanamine, cyclohexenecarboguanamine, norbornanecarboguanamine, and functional group-substituted derivatives thereof Aromatic guanamine compounds such as benzoguanamine, α- or β-naphthoguanamine and their functional group-substituted derivatives; phthaloguanamine, isophthalologamine , Terephthalologamine, naphthalenediguanamine, polyphenyleneamines such as biphenylenediguanamine; aralkyl or aralkyleneguanamines such as phenylacetoguanamine, β-phenylpropioguanamine, o-, m- or p-xylylenebisguanamine; acetal Examples include heteroatom-containing guanamine compounds such as group-containing guanamines, dioxane ring-containing guanamines, tetraoxospiro ring-containing guanamines, and isocyanuric ring-containing guanamines.

  The functional group-substituted derivative in the alicyclic guanamine-based compound is not particularly limited, and specifically includes an alkyl group, a hydroxy group, an amino group, an acetamino group, a nitrile group, a carboxy group, an alkoxycarbonyl group, a carbamoyl group, an alkoxy group. And derivatives in which 1 to 3 functional groups such as a phenyl group, a cumyl group, and a hydroxyphenyl group are substituted with a cycloalkane residue. In addition, the functional group-substituted derivative in the aromatic guanamine compound is not particularly limited, and specifically, an alkyl group, a hydroxy group, an amino group, an acetamino group, a nitrile group, a carboxy group, an alkoxycarbonyl group, a carbamoyl group, Derivatives in which 1 to 5 functional groups such as an alkoxy group, a phenyl group, a cumyl group, and a hydroxyphenyl group are substituted with a phenyl residue of benzoguanamine or a naphthyl residue of naphthoguanamine are exemplified. For example, o-, m-, or p -Tolguanamine, o-, m- or p-xyloganamine, o-, m- or p-phenylbenzoguanamine, o-, m- or p-hydroxybenzoguanamine, 4- (4'-hydroxyphenyl) benzoguanamine, o- , M- or p-nitrile benzoguanamine, 3,5-dimethyl-4- Mud carboxymethyl benzoguanamine, 3,5-di -t- butyl-4-hydroxy benzoguanamine are exemplified.

  The acetal group-containing guanamines are not particularly limited, and specific examples include 2,4-diamino-6- (3,3-dimethoxypropyl-s-triazine. Further, examples of the dioxane ring-containing guanamines Although not specifically limited, [2- (4′-6′-diamino-s-triazin-2′-yl) ethyl] -1,3-dioxane, [2- (4′-6 ′) -Diamino-s-triazin-2'-yl) ethyl] -4-ethyl-4-hydroxymethyl-1,3-dioxane, and tetraoxospiro ring-containing guanamines are not particularly limited, Specifically, CTU-guanamine (3,9-bis [2- (3,5-diamino-2,4,6- 卜 riazaphenyl) ethyl] -2,4,8,10-tetraoxaspi [5,5] undecane), CMTU-guanamine (3,9-bis [1- (3,5-diamino-2,4,6-triazaphenyl) methyl] -2,4,8,10-tetraoxa Spiro [5,5] undecane) Further, the isocyanuric ring-containing guanamines are not particularly limited, but specifically, 1,3,5-tris [2- (4 ′, 6′- Diamino-s-triazin-2′-yl) ethyl] isocyanurate, 1,3,5-tris [3- (4 ′, 6′-diamino-s-triazin-2′-yl) propyl] isocyanurate It is done.

  Examples of the urea compound include a chain urea compound and a cyclic urea compound. Although it does not specifically limit as a chain | strand-shaped urea type compound, Specifically, polyalkylene or arylene ureas, such as condensates of urea, such as biurea, biuret, form nitrogen, and formaldehyde; and polynonamethylene urea are mentioned. Although it does not specifically limit as cyclic urea type compound, Specifically, mono, di, tri, or tetraalkoxymethyl glycol, such as hydantoins, chlorotylidene diurea, acetylene urea, mono, di, tri, or tetramethoxymethyl glycoluril Examples include uril, cyanuric acid, isocyanuric acid, uric acid, and urazole. Of these, hydantoins are not particularly limited, but specific examples include hydantoin, 5-methylhydantoin, 5-ethylhydantoin, 5-isopropylhydantoin, 5-phenylhydantoin, 5-benzylhydantoin, 5,5- Dimethylhydantoin, 5,5-pentamethylenehydantoin, 5-methyl-5-phenylhydantoin, 5,5-diphenylhydantoin, 5- (o-, m- or p-hydroxyphenyl) hydantoin, 5- (o-, m -Or p-aminophenyl) hydantoin, allantoin, 5-methylallantoin, and metal salts such as Al salts of Allandin such as allantoin dihydroxyaluminum salts.

  Examples of the hydrazide compounds include aliphatic carboxylic acid hydrazide compounds, alicyclic carboxylic acid hydrazide compounds, and aromatic carboxylic acid hydrazide compounds. The aliphatic carboxylic acid hydrazide compound is not particularly limited, and specific examples thereof include lauric acid hydrazide, stearic acid hydrazide, 12-hydroxystearic acid hydrazide, 1,2,3,4-butanetetracarboxylic acid hydrazide and the like. Monocarboxylic acid hydrazides; succinic acid mono or dihydrazide, glutaric acid mono or dihydrazide, adipic acid mono or dihydrazide, pimelic acid mono or dihydrazide, suberic acid mono or dihydrazide, azelaic acid mono or dihydrazide, sebacic acid mono or dihydrazide, dodecane Polycarboxylic acid hydrazides such as acid mono or dihydrazide, hexadecanedioic acid mono or dihydrazide, eicosane diacid mono or dihydrazide, 7,11-octadecadien-1,18-dicarbohydrazide It is. Although it does not specifically limit as an alicyclic carboxylic acid hydrazide type compound, Specifically, monocarboxylic acid hydrazides, such as cyclohexane carboxylic acid hydrazide; Dimer acid mono or dihydrazide, trimer acid mono, di or trihydrazide, 1, Examples thereof include polycarboxylic acid hydrazides such as 2-, 1,3- or 1,4-cyclohexanedicarboxylic acid mono- or dihydrazide, cyclohexanetricarboxylic acid mono-, di- or trihydrazide. The aromatic carboxylic acid hydrazide compound is not particularly limited. Specifically, monocarboxylic acids such as benzoic hydrazide and functional group-substituted derivatives thereof, α- or β-naphthoic acid hydrazide and functional group-substituted derivatives thereof, and the like. Hydrazides; isophthalic acid mono- or dihydrazide, terephthalic acid mono- or dihydrazide, 1,4- or 2,6-naphthalenedicarboxylic acid mono- or dihydrazide, 3,3'-, 3,4'- or 4,4'-diphenyldicarboxylic acid Acid mono or dihydrazide, diphenyl ether dicarboxylic acid mono or dihydrazide, diphenylmethane dicarboxylic acid mono or dihydrazide, diphenylethane dicarboxylic acid mono or dihydrazide, diphenoxyethane dicarboxylic acid mono or dihydrazide, diphenylsulfone dicarboxylic acid mono or di Hydrazide, diphenyl ketone dicarboxylic acid mono or dihydrazide, 4,4 ″ -terphenyl dicarboxylic acid mono or dihydrazide, 4,4 ′ ″-quarterphenyl dicarboxylic acid mono or dihydrazide, 1,2,4-benzenetricarboxylic acid mono, Examples thereof include polycarboxylic acid hydrazides such as di- or trihydrazide, pyromellitic acid mono, di, tri, or tetrahydrazide, 1,4,5,8-naphthoic acid mono, di, tri, or tetrahydrazide. The benzoic acid hydrazide and functional group-substituted derivatives thereof are not particularly limited, and specifically, o-, m- or p-methylbenzoic acid hydrazide, 2,4-, 3,4-, 3,5- or 2,5-dimethylbenzoic acid hydrazide, o-, m- or p-hydroxybenzoic acid hydrazide, o-, m- or p-acetoxybenzoic acid hydrazide, 4-hydroxy-3-phenylbenzoic acid hydrazide, 4-acetoxy- 3-phenylbenzoic acid hydrazide, 4-phenylbenzoic acid hydrazide, 4- (4′-phenyl) benzoic acid hydrazide, 4-hydroxy-3,5-dimethylbenzoic acid hydrazide, 4-hydroxy-3,5-di-t -Alkyl group, hydroxy group, acetoxy group, amino group, acetamino group, nitrile group, carboxy group, such as butylbenzoic acid hydrazide Alkoxycarbonyl group, a carbamoyl group, an alkoxy group, a phenyl group, a benzyl group, cumyl group, a functional group such as a hydroxyphenyl group is 1-5 substituted derivatives phenyl residues benzoguanamine. Examples of α- or β-naphthoic acid hydrazide and functional group-substituted derivatives thereof include 3-hydroxy-2-naphthoic acid hydrazide and 6-hydroxy-2-naphthoic acid hydrazide.

  The formaldehyde scavenger (C) is supported on a layered material or a porous material (hydrotalcite, montmorillonite, silica gel, alumina, titania, zirconia, sepiolite, smectite, palygorskite, imogolite, zeolite, activated carbon, etc.). Use in the form is also possible.

  Among the formaldehyde scavengers (C), aminotriazine compounds, guanamine compounds, particularly aromatic guanamine compounds; urea compounds, particularly cyclic urea compounds; carboxylic acid hydrazide compounds, particularly aliphatic carboxylic acid hydrazide compounds, and Aromatic carboxylic acid hydrazide compounds are preferably used. Among these, aliphatic carboxylic acid hydrazide compounds and aromatic carboxylic acid hydrazide compounds are particularly preferable. Among aliphatic carboxylic acid hydrazide compounds and aromatic carboxylic acid hydrazide compounds, dihydrazides such as adipic acid dihydrazide, sebacic acid dihydrazide, dodecadioic acid dihydrazide, isophthalic acid dihydrazide, and terephthalic acid dihydrazide are used in terms of formaldehyde scavenging effect. preferable.

<Other additives (D)>
The polyoxymethylene resin composition used in the present embodiment may contain other conventionally known additives (D) as necessary.

  Other additives (D) other than the above include, for example, antioxidants, heat stabilizers, formic acid neutralizers, weathering (light) agents, lubricants, various inorganic and organic fillers, crystal nucleating agents, mold release agents And appearance improvers such as pigments and dyes.

  The content of the additive (D) in the polyoxymethylene resin composition is preferably 20 parts by mass or less and more preferably 10 parts by mass or less with respect to 100 parts by mass of the polyoxymethylene (A). More preferably, it is 5 parts by mass or less.

  Although it does not specifically limit as antioxidant, Specifically, a hindered phenol type compound, a phosphorus type compound, a sulfur type compound, etc. are mentioned.

  Although it does not specifically limit as a heat stabilizer, Specifically, formaldehyde scavengers other than the above, a formic acid scavenger, etc. are mentioned.

  The neutralizing agent for formic acid is not particularly limited, and specific examples thereof include alkali metal or alkaline earth metal hydroxides, inorganic acid salts, carboxylate salts, and alkoxides.

  The weathering (light) agent is not particularly limited, and specifically, ethylene-2-cyano-3,3′-diphenyl acrylate, 2- (2′-hydroxy-5′-methylphenyl) benzotritriazole, 2- (2′-hydroxy-3′-t-butyl-5′-methylphenyl) 5-chlorobenzotriazole, 2-hydroxy-4-methoxybenzophenone, 2,2′-dihydroxy-4-methoxybenzophenone, etc. An ultraviolet absorber etc. are mentioned.

  The lubricant is not particularly limited, and specifically, fatty acid hydrocarbon lubricants such as ethylene bissteramide, butyl stearate, polyethylene wax, paraffin wax, higher fatty acid lubricants, fatty acid amide lubricants, fatty acid ester lubricants, etc. Is mentioned.

  Various inorganic / organic fillers are not particularly limited, and specifically, inorganic fillers such as fibrous, powder particle, plate and hollow fillers, and starch, oxidized starch, and modified starch, Organic fillers such as cellulose and carboxyl-modified cellulose, agar, xanthone and the like can be mentioned.

  Although it does not specifically limit as a crystal nucleating agent, Specifically, boron nitride etc. are mentioned.

  Although it does not specifically limit as a mold release agent, Specifically, alcohol, fatty acid and those fatty acid ester, polyoxyalkylene glycol, the olefin compound whose average degree of polymerization is 10-500, silicone, etc. are mentioned.

  The pigment / dye is not particularly limited, and specific examples include carbon black, phthalocyanine, quinacridone, indoline, azo pigments, and bengara.

(Production method of polyoxymethylene resin composition)
The polyoxymethylene resin composition is a component constituting the polyoxymethylene intermittent sliding part of the present embodiment, contains polyoxymethylene (A) as described above, and further lubricates as necessary. It contains an agent (B), a formaldehyde scavenger (C), and other additives (D). Below, the manufacturing method of the polyoxymethylene resin composition which contains all the polyoxymethylene (A), a lubricant (B), a formaldehyde scavenger (C), and other additives (D) is illustrated. .

  The above polyoxymethylene (A), lubricant (B), formaldehyde scavenger (C) and other additives (D) are mixed when the polyoxymethylene (A) is granulated. You may carry out by adding a component C) and a component (D), and melt-kneading.

  Moreover, after granulating (A) component, after mixing (A) component-(D) component using a Henschel mixer, a tumbler, and a V-shaped blender, a kneader, a roll mill, a single screw extruder, a twin screw extruder Alternatively, a polyoxymethylene resin composition can be obtained by melt-kneading using a multi-screw extruder.

  Moreover, in order to improve the dispersibility of (B) component-(D) component with respect to polyoxymethylene (A), after pulverizing and mixing beforehand the part or whole quantity of the pellet of polyoxymethylene (A) to mix, You may melt-mix. In this case, the dispersibility may be further increased by using a spreading agent. Such spreading agents are not particularly limited, and specific examples include aliphatic hydrocarbons and aromatic hydrocarbons, modified products and mixtures thereof, and fatty acid esters of polyols.

  It is preferable that the temperature of the said melt mixing is 180-230 degreeC. Further, from the viewpoint of maintaining the quality and working environment, it is preferable to perform deaeration by replacement with an inert gas or by one-stage or multistage vent.

  Furthermore, the polyoxymethylene resin composition used in the present embodiment may be obtained from a molded product. For example, the molded product may be pulverized, and the obtained flakes may be used instead of pellets. Moreover, you may mix a part of grind | pulverized flake with the pellet obtained from the above.

(Physical properties of polyoxymethylene resin composition)
As for the physical properties of the polyoxymethylene resin composition used in the present embodiment, the rigidity is 2500 MPa or more, the impact resistance is 10 kJ / m ² or more, and the friction coefficient in the reciprocating sliding test is 0.15 or less. The physical properties shown here are values measured at an environmental temperature of 23 ± 2 ° C. and a humidity of 50 ± 10%. By making the rigidity, impact resistance and coefficient of friction of the polyoxymethylene resin composition within the above ranges, the polyoxymethylene intermittent type sliding including the member (I) formed using the polyoxymethylene resin composition The parts have a small dimensional change when intermittently sliding with the metal while ensuring a practically sufficient productivity, and an excellent durability can be obtained.

  The physical property here may be the physical property of the test specimen for evaluation obtained from the pellet of the obtained polyoxymethylene resin composition, or obtained from the flakes obtained by pulverizing the intermittent sliding part made of polyoxymethylene of this embodiment. The physical property of the obtained test specimen for evaluation may be used.

<Rigidity>
The rigidity of the polyoxymethylene resin composition used in the present embodiment is 2500 MPa or more, preferably 2600 MPa or more, and more preferably 2650 MPa or more. When the rigidity is 2600 MPa or more, a polyoxymethylene intermittent sliding component having a smaller dimensional change when sliding intermittently with metal and having superior durability is obtained.

  The test piece for evaluation used for the measurement of rigidity is an ISO (multi-cavity) mold A type injection molded piece based on ISO3167. The test specimen for evaluation is confirmed to be free of short shots or burrs using, for example, a molding machine (Toshiba Machine; IS-100E, cylinder temperature 200 ° C., mold temperature 80 ° C., cooling time 30 seconds). Can be molded. Further, after molding, it can be left and adjusted for 16 hours or more at an environmental temperature of 23 ± 2 ° C. and a humidity of 50 ± 10%.

  The evaluation of rigidity can be performed in accordance with ISO 527-1 and -2. Specifically, using a test piece for evaluation, a tensile test is performed at a test speed of 1 mm / min using, for example, a universal testing machine (Shimadzu Corporation; Autograph AGS-X, equipped with an extensometer). The tensile modulus is measured by a slope of displacement of 0.05 to 0.25% and is defined as the rigidity of the polyoxymethylene resin composition. In more detail, it can be carried out according to the method described in the examples.

<Impact resistance>
Impact resistant polyoxymethylene resin composition used in the present embodiment is 10 kJ / ^{m 2} or more, preferably 11 kJ / ^{m 2} or more, more preferably 11.5kJ / ^{m 2} or more, More preferably, it is 13 kJ / m ² or more. When the impact resistance is 13 kJ / m ² or more, the dimensional change when sliding intermittently with a metal is smaller, and the polyoxymethylene intermittent sliding part has better durability. .

  As the test piece for evaluation used for impact resistance, a part having a cut-out notch is formed from the part between the marked lines of the test piece for evaluation used for the rigidity evaluation in accordance with ISO 179-1, and further formed. Thereafter, the same adjustment as described above was used. The impact resistance was evaluated according to ISO179-1. More specifically, a Charpy impact test is performed using, for example, an impact tester (Yasuda Seiki; pendulum impact tester No. 141) using the test specimen for evaluation, and the impact resistance of the polyoxymethylene resin composition did. In more detail, it can be carried out according to the method described in the examples.

<Friction coefficient>
The maximum coefficient of friction during reciprocating sliding of the polyoxymethylene resin composition used in the present embodiment is 0.15 or less, preferably 0.12 or less, and more preferably 0.1 or less. . As the test piece for evaluation used for the friction coefficient measurement, the portion between the marked lines of the test piece for evaluation used for the evaluation of the rigidity was used. When the friction coefficient is 0.12 or less, the dimensional change when intermittently sliding with the metal is smaller, and the polyoxymethylene intermittent-type sliding component having higher durability is obtained.

  Specifically, the evaluation of the friction coefficient is performed by using a SUS304 ball having a tip diameter of 5 mm using a test piece for evaluation, for example, using a reciprocating motion tester (AFT-15MS manufactured by Tokyu Seimitsu Co., Ltd.). The maximum friction coefficient when the reciprocating sliding is performed 1000 times in the flow direction at the time of molding the test piece under the conditions of a sliding speed of 30 cm / sec and a sliding distance of 20 mm under a load of 2 kgf at room temperature. The coefficient of friction of the polyoxymethylene resin composition was measured. In more detail, it can be carried out according to the method described in the examples.

[Manufacturing Method of Member (I)]
The member (I) used in this embodiment can be obtained by molding the polyoxymethylene resin composition described above.

  As a manufacturing method of member (I) used for this embodiment, the various well-known shaping | molding methods using the conventional polyoxymethylene resin composition used as a raw material are mentioned. The molding method is not particularly limited, and specifically, extrusion molding, injection molding, vacuum molding, blow molding, injection compression molding, decorative molding, multicolor molding, gas assist injection molding, foam injection molding, low pressure It can be molded by a molding method such as molding, ultra-thin injection molding (ultra-high-speed injection molding), or in-mold composite molding (insert molding, outsert molding). In particular, from the viewpoint of productivity, extrusion molding / injection molding / injection compression molding, or multicolor molding / in-mold composite molding in which different materials are combined is preferable.

  As the molding conditions, recommended conditions under which polyoxymethylene is usually molded are used. For example, it is preferable to perform molding at a resin temperature of 180 to 230 ° C. and a mold temperature of 60 to 120 ° C.

  Further, the surface state of the member (I) used in the present embodiment may be smooth or subjected to various embossing.

[Partner material (II)]
The polyoxymethylene intermittent sliding component of the present embodiment has a counterpart material (II) in contact with the above-described member (I). The counterpart material (II) used in the present embodiment refers to a material that faces the member (I) when sliding.

  The counterpart material (II) used in the present embodiment is a metal. Although it does not specifically limit as a metal, Specifically, a steel system (carbon steel, alloy steel, cast iron, etc.) and a nonferrous metal system (copper, aluminum, nickel, a noble metal, a low melting metal, and those alloys etc.) are mentioned. It is done. In the present embodiment, the member (I) made of the polyoxymethylene resin composition and the counterpart material (II) that slides are metals. Since metals generally have higher surface hardness and better thermal conductivity than resin compositions, any metal often exhibits the same physical properties as long as it has a similar surface roughness. By using the counterpart material (II) as a metal, the polyoxymethylene intermittent sliding component including the member (I) formed using the polyoxymethylene resin composition can have excellent durability.

[Manufacturing method of counterpart material (II)]
A known metal processing method is mentioned as a manufacturing method of the other party material (II) used for this embodiment. For example, the processing method is not particularly limited, but includes casting (sand mold, die, die cast, precision casting, etc.) and plastic processing (rolling, drawing, extrusion, punching, etc.). Moreover, in order to raise surface hardness, you may give quenching, tempering, forging, etc. From the viewpoint of slidability, no matter what manufacturing method or processing method is used for the metal, it is possible to obtain a stable effect by having a smooth surface property with few burrs. The line average roughness Ra is preferably 25 μm or less, and more preferably 10 μm or less. Further, the metal as the counterpart material (II) may be subjected to a coating treatment for suppressing rust, improving design properties, or the like.

[Usage of intermittent sliding parts made of polyoxymethylene]
The sliding component made of polyoxymethylene of this embodiment is an intermittent sliding component. By making the movement at the time of sliding intermittent, the polyoxymethylene intermittent sliding part including the member (I) formed using the polyoxymethylene resin composition has excellent durability.

  The movement at the time of steady sliding of the member (I) or the counterpart material (II) of the polyoxymethylene intermittent sliding part is intermittent, intermittent, or reversible. For example, it can be moved manually up and down, left and right, or using a cam, clutch, electrical forward / reverse rotation, etc. during transmission from a power source, and repeatedly activated and stopped such as reciprocating motion, intermittent motion, reversible rotation, etc. It is a movement to do. The movement here is how the counterpart material (II) is moving as viewed from the member (I). For example, considering the case where the record needle slides, the record moves continuously when viewed from the record needle. The intermittent sliding parts made of polyoxymethylene according to the present embodiment, when the surface pressure and the speed are increased by continuous movement, the temperature of the sliding surface rises and the wear becomes intense, and the effect may not be obtained. Used as an intermittent sliding part.

  Moreover, it is preferable that the polyoxymethylene-made intermittent sliding component of this embodiment is used for the contact form in case the contact surface of member (I) and counterpart material (II) is a line or a surface. The contact surface refers to a shape that contacts the member (I) and the counterpart material (II) before or after sliding when viewed macroscopically. For example, considering the case where the record needle and the record slide as described above, the contact surface becomes a point. The polyoxymethylene intermittent sliding component of this embodiment is not a point but a line or surface, and the surface pressure is relatively small, so that wear due to scratching tends to be suppressed. is there.

  In addition, the sliding form of the contact surface of the polyoxymethylene intermittent-type sliding component is preferably used when contacting continuously / discontinuously, discontinuously / continuously, or continuously / continuously. The sliding form means a form in which the contact surface slides continuously or discontinuously. Here, “continuous” means a form in which the sliding surface is always constant, and “discontinuous” means a state in which the sliding surface is updated. For example, if the record needle and the record slide as described above, the record needle side slide surface slides continuously, but the record side slide surface slides discontinuously. The sliding form is continuous / discontinuous. The polyoxymethylene intermittent sliding parts of this embodiment are more effective in sliding forms that are continuous / discontinuous, discontinuous / continuous, or continuous / continuous, rather than discontinuous / discontinuous. It tends to be easier.

  The polyoxymethylene intermittent sliding parts of this embodiment may be all of the sliding parts of the apparatus, or may be a part including the sliding surface of the sliding parts.

  The polyoxymethylene intermittent sliding component of this embodiment may have a different material insert and / or a joint with a different material for the purpose of improving workability and functionality. The polyoxymethylene intermittent sliding part of this embodiment is molded into a complicated shape because the above-described polyoxymethylene resin composition has excellent productivity and excellent workability. Or post-processing, and the dimensional change and durability can be further improved.

  By adopting the above preferred form of use, the polyoxymethylene intermittent-type sliding part including the member (I) formed using the polyoxymethylene resin composition is made of a metal while ensuring practically sufficient productivity. When slid intermittently, the dimensional change is small, and excellent durability tends to be obtained.

  The example of the specific form of the polyoxymethylene intermittent sliding component of this embodiment is shown in FIGS. The member (I) may be either the member (x) or the member (y) in FIGS. That is, as long as it is a combination of the member (I) and the counterpart material (II), either the member (x) or the member (y) may be used. Further, in the figure, the sliding movement is reversibly described, but it may be intermittent or a complex movement thereof. Furthermore, the moving side may be replaced with the member (I) and the counterpart material (II). 1 to 5, the straight arrow indicates the facing direction of the member (x) and the member (y), and the curved arrow indicates the sliding direction of the member (x). FIG. 1 shows an example of shaft fixing in which the member (x) and the member (y) are opposed to the straight arrow, and FIG. 2 is an example of receiving fixation in which the member (x) and the member (y) are opposed to the linear arrow. 3 shows an example of hole fixing in which the member (x) and the member (y) are opposed to the straight arrow, and FIG. 4 is surface fixing in which the member (x) and the member (y) are opposed to the linear arrow, FIG. Shows an example of shaft pressing fixing in which the member (x) and the member (y) face the straight arrow.

  Specific uses of intermittent sliding parts made of polyoxymethylene are used in electrical equipment, automobile parts and other various mechanical parts, and some of the functions described above are used in containers, covers, cases, doors, etc. It may be used as a spare part. In particular, the parts are preferably used for shaft parts, bearing parts, shaft hole parts, roller parts, bush parts, washer parts, belt parts, etc., which perform intermittent sliding. Furthermore, it is preferably used for forward / reverse parts of levers and handles, and unwinding / rewinding parts of belts and tapes.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated, embodiment of this invention is not limited to a following example.

  First, the polyoxymethylene resin composition (P) and the counterpart material (II) forming the member (I) included in the polyoxymethylene intermittent sliding parts in Examples and Comparative Examples will be described.

[Polyoxymethylene resin composition (P) forming member (I)]
As a raw material for preparing the polyoxymethylene resin composition (P), the following polyoxymethylene (A) and, if necessary, a lubricant (B), (C), or (D) were used. .

(raw materials)
<Polyoxymethylene (A)>
As polyoxymethylene (A), polyoxymethylene homopolymer (A-1) and polyoxymethylene copolymer (A-2) obtained by the following procedure were used. Table 1 shows the polyoxymethylene (A) used and its melt flow rate.

・ Measurement of melt flow rate of polyoxymethylene (A)
The following polyoxymethylene (A) pellets were dried in an oven (GPH-102, manufactured by ESPEC Corporation) for 2 hours at 80 ° C. before measurement. The melt flow rate of the polyoxymethylene (A) pellets was measured using a melt indexer (F-W01, manufactured by Toyo Seiki Co., Ltd.) in accordance with ISO 1133 (condition D, temperature 190 ° C.).

-(A-1-1-1) Synthesis of polyoxymethylene homopolymer (polymerization step)
A polyoxymethylene homopolymer was prepared as follows. A 5 L tank polymerization vessel with a jacket attached with a stirrer was filled with 2 L of n-hexane, and a circulation line (inner diameter: 6 mm, length: 2.5 m) was provided. The n-hexane was circulated at 20 L / hr by a pump. 200 g / hr of dehydrated formaldehyde gas was directly supplied to this circulation line. Further, the catalyst (dimethyl distearyl ammonium acetate) was adjusted to a formaldehyde gas in a molar ratio of 1 × 10 ⁻⁵ to 1 × 10 ⁻⁴ and supplied to the circulation line immediately before the reactor. Furthermore, a chain transfer agent (acetic anhydride) is added to the supplied hexane to compensate for the decrease in the polymerization slurry sent to the terminal stabilization step, and adjustment is made in the range of 0.13 to 0.52 g / hr. , Feed continuously. In this state, polymerization was performed at 58 ° C. to obtain a polymerization slurry containing the crude polymer (A-1-1).

  Moreover, except having adjusted the melt flow rate as shown in Table 1, operation similar to the above was performed and the polymerization slurry containing the rough | crude polymer of (A-1-2-5) was also obtained, respectively. The melt flow rate was adjusted by controlling the amount of chain transfer agent or polymerization catalyst added. About the terminal stabilization process and the granulation process which followed, the process similar to the crude polymer of (A-1-1) was performed.

(Terminal stabilization process)
Stabilization was performed by reacting the obtained polymerization slurry in a 1: 1 mixture of hexane and acetic anhydride at 140 ° C. for 2 hours and acetylating the molecular ends. The polymer after the reaction was collected by filtration, and the polymer collected by filtration was decompressed to 2 mmHg or less and dried for 3 hours with a vacuum dryer set at 80 ° C. to obtain a polyoxymethylene homopolymer powder.

(Granulation process)
Furthermore, 100 parts by mass of this powder, 0.2 parts by mass of Irganox 245 (manufactured by Ciba Specialty Chemicals Co., Ltd.) and 0.2 parts by mass of H-3 (manufactured by Asahi Kasei Finechem Co., Ltd.) as stabilizers Mix for 1 minute with a Henschel mixer. Thereafter, the obtained mixture was screwed into a screw type twin screw extruder set at 200 ° C. (BT-30 manufactured by Plastic Industry Co., Ltd., L / D = 44, L: from the raw material supply port of the twin screw extruder) The distance to the discharge port (m), D: inner diameter (m) of the twin screw extruder, the same applies hereinafter), the screw rotation speed was 80 rpm, and melt-kneaded at 24 amps to polyoxymethylene homopolymer (A-1 -1-5) pellets were obtained. From raw material input to pellet collection, the operation was performed while avoiding oxygen contamination as much as possible.

(A-2-1-2) Synthesis of polyoxymethylene copolymer (polymerization step)
The polyoxymethylene copolymer was prepared as follows. First, a self-cleaning type biaxial paddle type continuous mixing reactor with a jacket through which a heating medium can pass (screw diameter 3 inches, length ratio to diameter (L / D) = 10) was adjusted to 80 ° C. . The above-mentioned continuous was prepared by adjusting 3750 g / hr of trioxane as a main monomer, 25 to 150 g / hr of 1,3-dioxolane as a comonomer, and 2.0 to 8.0 g / hr of a chain transfer agent (methylal). Continuously fed to the mixing reactor.

In addition, a 1% by mass cyclohexane solution of boron trifluoride di-n-butyl etherate as a polymerization catalyst was added to the continuous mixing reactor so that the catalyst was 2.0 × 10 ⁻⁵ mol with respect to 1 mol of trioxane. The polymerization flakes of (A-2-1) were obtained. Moreover, except having adjusted the melt flow rate as described in Table 1, operation similar to the above was performed and the polymerization flake of (A-2-2) was also obtained. The melt flow rate was adjusted by controlling the amount of chain transfer agent or polymerization catalyst added.

  After pulverizing the obtained polymerization flakes, the pulverized product was put into a 1% by mass aqueous solution of triethylamine and stirred to deactivate the polymerization catalyst. Thereafter, a 1% by mass aqueous solution of triethylamine containing polymer flakes was sequentially filtered, washed and dried to obtain a crude polymer.

(Terminal stabilization process)
Equivalent to an amount of 20 ppm when triethyl (2-hydroxyethyl) ammonium formate is converted into the amount of nitrogen using the following formula (α) as a quaternary ammonium compound with respect to 1 part by mass of the obtained crude polymer. Was added and mixed uniformly, followed by drying at 120 ° C. for 3 hours to obtain a dry polymer.
Addition amount of quaternary ammonium compound = P × 14 / Q (α)
(In the formula (α), P represents the concentration (mass ppm) of the quaternary ammonium compound relative to the crude polymer, “14” represents the atomic weight of nitrogen, and Q represents the molecular weight of the quaternary ammonium compound.)

  Next, terminal stabilization was performed as follows using the obtained dry polymer. The obtained dry polymer is added to the front part of a screw-type twin screw extruder with a vent (Plastic Industry Co., Ltd., BT-30, L / D = 44, set temperature 200 ° C., rotation speed 80 rpm), and further dried. 0.5 parts by mass of water was added to 100 parts by mass of the polymer, and vacuum degassing was performed while stabilizing the polymer terminal to obtain a dry polymer.

(Granulation process)
Next, with respect to 100 parts by mass of the dried polymer, 0.2 parts by mass of Irganox 245 (manufactured by Ciba Specialty Chemicals Co., Ltd.) and H-3 (manufactured by Asahi Kasei Finechem Co., Ltd.) 0.2 as stabilizers. Part by mass was previously mixed with a Henschel mixer for 1 minute. The obtained mixture was added from the side feeder in the latter part of the above twin screw extruder and a screw type twin screw extruder with a vent set to 200 ° C. (BT-30, L / D manufactured by Plastic Industry Co., Ltd.) = 44), the screw rotation speed was 80 rpm, and melt kneading was performed at 24 amps to obtain polyoxymethylene copolymer pellets. From raw material input to pellet collection, the operation was performed while avoiding oxygen contamination as much as possible.

  Table 1 shows the ratio of the oxyalkylene unit b (mol) to the oxymethylene unit a (100 mol) in the two types of polyoxymethylene copolymers obtained by adjusting the comonomer amount (hereinafter also referred to as “b / a”). It was.

  Here, (b / a) was obtained as follows. The obtained polyoxymethylene copolymer was dissolved in a solvent, hexafluoroisopropanol (HFIP) -d2 (D conversion rate 97%, Wako Pure Chemicals 98% assay) over 24 hours, to obtain a polyoxymethylene copolymer. A 1.5% by weight solution of was prepared. Using a 1.5% by mass solution of the above polyoxymethylene copolymer as a specimen, using a JEOL-400 nuclear magnetic resonance spectrometer (1H: 400 MHz), under conditions of 55 ° C. and 500 accumulations, oxymethylene unit a, The assigned peaks with the oxyalkylene unit b excluding the unit a were integrated. From the integrated value thus obtained, the ratio of the oxyalkylene unit b (mol) to the oxymethylene unit a (100 mol) was determined.

A-1-0 is Tenac 2010 (manufactured by Asahi Kasei Chemicals Corporation).

<Lubricant (B)>
The following (B-1) to (B-5) were used as the lubricant (B).
(B-1): Ester lubricant (ethylene glycol distearate, manufactured by NOF Corporation, melting point> 50 ° C.)
(B-2): Ester lubricant (cetyl myristate, manufactured by NOF Corporation, melting point> 50 ° C.)
(B-3): Ester lubricant (dibutyl sebacate, manufactured by Daihachi Chemical Industry Co., Ltd., liquid at room temperature, melting point <23 ° C.)
(B-4): Amide-based lubricant (ethylenebisstearylamide, manufactured by Nippon Oil & Fats Co., Ltd., melting point> 50 ° C.)
(B-5): Alcohol-based lubricant (PEG 6000, manufactured by Sanyo Chemical Co., Ltd., melting point> 50 ° C.)

  The melting point of the lubricant (B) was measured with a catalog value or a differential scanning calorimeter (DSC measuring device: manufactured by STA6000 Perkin Elmer). The measurement was carried out by raising the temperature of a solid lubricant at normal temperature from normal temperature to 200 ° C. at 2.5 ° C./min, and taking the exothermic peak when the horizontal axis represents temperature and the vertical axis represents heat flow as the melting point.

<Formaldehyde scavenger (C)>
(C-1): Hydrazide-based formaldehyde scavenger (Sebacic acid dihydrazide, manufactured by Nippon Finechem Co., Ltd.)
(C-2): Hydrazide-based formaldehyde scavenger (Dodecadioic acid dihydrazide, manufactured by Nippon Finechem Co., Ltd.)
(C-3): Urea-based formaldehyde scavenger (hydantoin, manufactured by Showa Denko KK)

<Other additives (D)>
GF: Glass fiber (ECS03T-851: manufactured by Nippon Electric Glass Co., Ltd.)

(Preparation of polyoxymethylene resin composition (P))
Said raw material (A) and, if necessary, (B), (C) or (D) were blended according to the composition shown in Table 2 and mixed uniformly using a Henschel mixer. The obtained mixture was melt-mixed using a screw-type twin screw extruder with a vent (Plastic Industry Co., Ltd., BT-30, L / D = 44, set temperature 200 ° C., rotation speed 80 rpm), and granulation was performed. Then, pellets of polyoxymethylene resin compositions (P1) to (P5) and (P7) to (P18) were obtained. Moreover, the polyoxymethylene resin composition (P6) was prepared by melting and granulating again without adding anything to (A-1-3). The polyoxymethylene resin composition (P19) was prepared by pulverizing a pulley molded using P3 with a pulverizer (manufactured by Hadano Sangyo Co., Ltd., pulverizer DD-2-3.7), and having a maximum 3 mm flake (P3 ') And made it. In addition, the polyoxymethylene resin composition (P0) is produced using A-1-0.

(Physical properties of polyoxymethylene resin composition (P))
The physical properties (rigidity, impact resistance, coefficient of friction) of the pellets (P0) to (P19) of the polyoxymethylene resin composition were measured by the following method. All measurements were performed five times, and the average value was used as each physical property value. The results are shown in Table 3.

<Rigidity>
Using a molding machine (Toshiba machine; IS-100E, cylinder temperature 200 ° C., mold temperature 80 ° C., cooling time 30 seconds) as a test piece used for evaluation of rigidity, pellets of the polyoxymethylene resin composition ( An ISO (multi-cavity) A type conforming to ISO 3167 is prepared from each of P0) to (P19). At this time, molding was performed while confirming that no short shots or burrs were generated. Further, after molding, it was left and adjusted for 16 hours or more at an environmental temperature of 23 ± 2 ° C. and a humidity of 50 ± 10%.

  For the evaluation of rigidity, in accordance with ISO 527-1 and ISO 527-2, for example, a universal tester (Shimadzu Corporation; Autograph AGS-X, equipped with extensometer) was subjected to a tensile test at a test speed of 1 mm / min, and 50 mm The tensile elastic modulus was measured by the slope of displacement of 0.05 to 0.25% between the marked lines, and the rigidity of each polyoxymethylene resin composition was determined. The physical properties shown here are values measured at an environmental temperature of 23 ± 2 ° C. and a humidity of 50 ± 10%.

<Impact resistance>
The test piece used for the impact resistance evaluation was prepared by adjusting the cutout notch in accordance with ISO 179-1 from the portion between the marked lines of the molded piece used for the rigidity evaluation. .

  As an evaluation of impact resistance, a Charpy impact test was conducted with an impact tester (Yasuda Seiki; pendulum impact tester No. 141) in accordance with ISO 179, and the impact resistance of the polyoxymethylene resin composition was determined. . The physical properties shown here are values measured at an environmental temperature of 23 ± 2 ° C. and a humidity of 50 ± 10%.

<Friction coefficient>
The test piece used for the evaluation of the friction coefficient was prepared by adjusting the portion between the marked lines of the molded piece used for the rigidity evaluation in the same manner as described above.

  The friction coefficient was evaluated by applying a load of 2 kgf to a SUS304 ball having a tip diameter of 5 mmφ using a reciprocating motion tester (AFT-15MS type manufactured by Tokyu Seimitsu Co., Ltd.) under a sliding speed of 30 cm / sec. The maximum friction coefficient when the reciprocating sliding was performed 1000 times in the flow direction at the time of molding of the test piece was measured and used as the friction coefficient of the polyoxymethylene resin composition.

[Metal that forms counterpart (II)]
The following was used as the metal for forming the counterpart material (II).
(B-1): Carbon steel (S45C-Q)
(B-2): Stainless steel (SUS416)
(B ′): A round bar of polyoxymethylene resin (manufactured by Asahi Kasei Chemicals Corporation, Tenac 2010).

[Production of polyoxymethylene intermittent sliding parts]
As a member (I) formed using the polyoxymethylene resin composition, a pulley (Ia) having a gear formed on the upper portion was produced as follows. Moreover, the shaft (IIb) which consists of said (b-1), (b-2), or (b ') was prepared as partner material (II) which contact | connects this member (I). Using the produced pulley (Ia) and shaft (IIb), it was confirmed that the shaft was inserted into the pulley and rotated without resistance.

(Production of pulley (Ia))
A pulley (Ia) as shown in FIG. 6-1 was produced by injection molding as follows using the prepared polyoxymethylene resin compositions (P0) to (P19). The injection molding should be sufficiently filled and free of burrs using an injection molding machine (TI30G-2, manufactured by Toyo Machine Metal Co., Ltd.) with a cylinder temperature of 200 ° C. and a mold temperature of 70 ° C. as a guide. It was carried out while confirming. The pulley (Ia) is injection-molded by a 0.3 mm diameter pin gate having a center 0.5 mm inside from the bottom end of the pulley at three equally spaced points on the circumference as shown in FIG. 6-2. . Hereinafter, this bottom portion (lower part of FIG. 6-2) is referred to as a gate side. The side having the gear (the upper part in FIG. 6-2) is referred to as an anti-gate side.

  The dimensions of the pulley (Ia) from the mold are as shown in FIG. 6B: the inner diameter of the pulley is 6.0 mm, the gear tip circle diameter is 12.4 mm, the bottom outer diameter is 20.0 mm, and the bottom height is 2. mm. The height was 0 mm and the pulley height was 17.0 mm. The shape of the gear portion conformed to P20MXL manufactured by Gates Unitta Co., Ltd. as shown in FIG. 6-3.

(Shaft (IIb))
A shaft made by Kurashiki Boring Co., Ltd., which was processed into a cylindrical shape with a diameter of 5.98 mm, a length of 60.0 mm, and a surface polish of ▽ = 4, was used. The processed shaft was degreased once with acetone before being inserted into the pulley to remove as much oil as possible from the surface. The same dimensions were cut from the polyoxymethylene resin round bar (b ') to form a shaft.

[Evaluation of intermittent sliding parts made of polyoxymethylene]
The polyoxymethylene intermittent sliding parts were evaluated as follows. The evaluation results are shown in Tables 4 and 5.

(Evaluation of productivity of intermittent sliding parts made of polyoxymethylene)
The productivity of the polyoxymethylene intermittent sliding parts was evaluated by the following productivity evaluation of the polyoxymethylene resin composition and the quality evaluation of the pulley (Ia).

<Productivity evaluation of polyoxymethylene resin composition>
The productivity evaluation of the polyoxymethylene resin composition is an average granulation amount per unit time of the polyoxymethylene resin composition when granulation is carried out by adjusting the extruder torque to be constant at 25 amps, It was performed comprehensively according to the state of the strands and the appearance and odor of the pellets.

  The evaluation criteria were defined as follows in comparison with the evaluation of productivity when a commercially available polyoxymethylene resin composition (P0) (resin composition comprising Tenac 2010) was passed through an extruder. . According to the following evaluation criteria, productivity evaluation of each polyoxymethylene resin composition was performed.

Evaluation criteria ○: When it is better than the productivity evaluation of Tenac 2010 ◇: When it is the same level △: When it is slightly reduced ×: When it is clearly reduced

  In addition, said "good" means the state where the increase in the average granulation amount per unit time was 10% or more when compared with Tenac 2010. The above “slightly reduced” means that when compared with Tenac 2010, the average granulated amount per unit time is within 20% to 40%, and the obtained strand has no blistering or breakage and is stably wound. The obtained pellets have the appearance of some facets and have an odor but do not deteriorate the workability. The above “obviously reduced” means that, when compared with Tenac 2010, if the average granulated amount per unit time is lower than 40%, the winding is unstable due to biting failure or breakage of the strands. In some cases, the appearance (color and shape) of the pellet is poor, or the pellet has a strong odor, which affects workability.

<Quality evaluation of pulley (Ia)>
The quality evaluation of the pulley (Ia) produced using the polyoxymethylene resin composition is performed in a comprehensive manner in accordance with the following evaluation criteria by visually confirming the appearance (silver, flow mark, etc.) and coloring of the molded product. It was. In addition, evaluation took the average of five of the produced pulley (Ia).

Evaluation criteria ○: When the mold transferability is good and the appearance such as smoothness and glossiness is good ◇: When it is equivalent to the commercially available polyoxymethylene resin Tenac 2010 △: Some defects such as silver and flow mark are confirmed Case ×: When a clear defect is confirmed on the sliding surface

(Evaluation of dimensional change and durability of intermittent sliding parts made of polyoxymethylene)
The dimensional change and durability of the polyoxymethylene intermittent sliding parts were evaluated using a sliding part evaluation apparatus described later.

  The dimensional change was the change in the shaft hole diameter of the pulley before and after the following sliding test, and the durability was determined by observing the change in the mass of the pulley and the appearance of the pulley and the shaft before and after the following sliding and the following operability test. . All the evaluations were performed three times, and the average was taken as the evaluation value.

<Sliding part evaluation device>
For evaluation of the dimensional change and durability of the polyoxymethylene intermittent sliding parts, a sliding part evaluation apparatus (manufactured by Shinko Engineering Co., Ltd., resin small bearing friction and wear tester 158273) was used.

  FIG. 6-4 is a schematic diagram of a measurement unit of the sliding component evaluation apparatus. As shown in FIG. 6-5, this sliding component evaluation apparatus is provided with a pulley (Ia) and a shaft (IIb), and the pulley (Ia) has a load-applying driving belt B (gates, 12.7 mm). Intermittent rotation (for example, rotation for 5 seconds / stop for 1 second, etc.) can be performed via Unita Co., Ltd. (B166MXL), and an upper load (arrow F) is applied. The pulley (Ia) was intermittently rotated by moving the load applying drive belt B in the direction of the curved arrow.

<Sliding test>
The sliding test of the polyoxymethylene intermittent sliding parts was performed using the sliding part evaluation apparatus. In this test, the shaft (IIb) is inserted into the pulley (Ia), the pushing load of the pulley to the shaft is set to 4.5 kgf, the pulley is rotated for 5 seconds at 1260 rpm, and stopped by the clutch for 1 second. This was once and this number was 50000 times. The dimensional change and partial durability of the polyoxymethylene intermittent sliding parts were evaluated from the size and mass of the pulley at this time and the state of the pulley and shaft.

<Operability test>
In the operability test of the polyoxymethylene intermittent sliding parts, changes in operability and generation of sound were observed when sliding after applying a load. In the test, the pulley (Ia) was inserted into the shaft (IIb), the belt was applied with the pulley fixed, a load of 20 kgf was applied to the belt for 1 hour, and torque was applied to the pulley. Thereafter, as described above, the maximum rotation speed is 1260 rpm, the rotation is performed for 5 seconds, the clutch is stopped for 1 second, and the operation of the polyoxymethylene intermittent-type sliding component is obtained from the operability when the number of clutches is 50. A part of durability was evaluated.

<Evaluation criteria for dimensional change and durability>
The dimensional change and durability evaluation of the polyoxymethylene intermittent sliding parts were carried out according to the following evaluation criteria by carrying out the above test. The dimensional change on the gate side refers to a dimensional change in the diameter of the shaft hole on the bottom of the pulley in FIG.

(1) Dimensional change Dimensional change of the polyoxymethylene intermittent sliding part is determined by changing the dimension of the shaft hole on the side opposite to the pulley (Ia) before and after the sliding test to a microscope (VHX, manufactured by Keyence Corporation). -1000). The dimensional change was evaluated according to the following evaluation criteria. The commercially available polyoxymethylene resin Tenac 2010 was 350 μm.
Evaluation criteria ◎: When the difference in measured dimensions is less than 50 μm ○: When it is 50 μm or more and less than 200 μm ◇: When 200 μm or more and less than 400 μm ×: When it is 400 μm or more

(2) Durability Evaluation of durability (appearance change, mass change and operability after loading) of the polyoxymethylene intermittent sliding parts was performed according to the following evaluation criteria.
1) Appearance change before and after sliding ◎: When the pulley and shaft were visually observed before and after the above sliding test and were very good ○: When very good ◇: When good ×: Poor In addition, as an evaluation criterion, the above “very good” means a state in which almost no change was observed in the pulley and the shaft. The above “very good” means a state in which a small amount of powder is confirmed. The term “good” refers to a state in which the generation of powder is small and the shaft is not damaged. The term “defective” refers to a state in which a large amount of powder is generated and / or the shaft is scratched. Commercially available polyoxymethylene resin Tenac 2010 was good.

2) Mass change before and after sliding Mass change was measured using a precision balance (ATX-84, manufactured by Shimadzu Corporation) for the mass of the pulley before and after the sliding test. The commercially available polyoxymethylene resin Tenac 2010 was 40 mg.
Evaluation criteria for mass change ◎: When the measured mass difference is less than 10 mg ○: When 10 mg or more and less than 30 mg ◇: When 30 mg or more and less than 50 mg ×: When 50 mg or more

3) Evaluation of operability after loading The operability was evaluated by performing the above-described operability test and observing changes in operability and the occurrence of sound when sliding after applying a load. The generation of sound was evaluated by confirming the presence or absence of sound by hearing from a distance of 30 cm from the sliding part of the sliding part evaluation apparatus. Commercially available polyoxymethylene resin Tenac 2010 was ◇.
Evaluation criteria for operability ◎: When there is no backlash during rotation and no sound is generated ○: When there is no backlash during rotation but a slight amount of sound is confirmed ◇: There is no backlash during rotation but there is periodic sound When confirmed ×: When rotation is unstable and rattling occurs

[Examples 1 to 4, Comparative Examples 1 to 5]
Table 4 shows the evaluation results of the polyoxymethylene intermittent sliding parts of Examples 1 to 4 and Comparative Examples 1 to 5. From the evaluation results of Examples 1 to 4 and Comparative Examples 1 to 5, by making the rigidity, impact resistance, and coefficient of friction within the scope of the present invention, the polyoxymethylene intermittent sliding parts are practically sufficient production It was found that the dimensional change is small and excellent durability is obtained when sliding with the metal intermittently while securing the properties. In particular, when the filler (GF) was included in the polyoxymethylene resin composition, scratches were confirmed on the shaft after sliding.

[Example 5, Reference Examples 1 and 2]
The evaluation results of the polyoxymethylene intermittent sliding parts of Example 5 and Reference Examples 1 and 2 are shown in Table 4. From the evaluation results of Examples 2 and 5 and Reference Examples 1 and 2, when sliding intermittently with metal, the polyoxymethylene intermittent-type sliding component changes in dimensions while ensuring practically sufficient productivity. It was found that the durability was small and excellent durability was obtained. In particular, generation of a large amount of powder was confirmed when the counterpart material was made of resin or slid continuously.

[Examples 6 and 7]
The evaluation results of the polyoxymethylene intermittent sliding parts of Examples 6 and 7 are shown in Table 5. From the evaluation results of Examples 2, 6, and 7, the polyoxymethylene resin composition contains the addition amount of the preferred lubricant of the present invention, and the polyoxymethylene resin composition has the rigidity, impact resistance, and friction coefficient within the scope of the present invention. It was found that intermittent sliding parts made of methylene tend to have excellent durability and small dimensional change when sliding intermittently with metal while ensuring practically sufficient productivity. .

[Examples 8 to 11]
The evaluation results of the polyoxymethylene intermittent sliding parts of Examples 8 to 11 are shown in Table 5. From the evaluation results of Examples 2 and 8 to 11, the polyoxymethylene resin composition contains the preferable lubricant species of the present invention, and the rigidity, impact resistance, and friction coefficient within the scope of the present invention are obtained. It was found that the intermittent sliding parts manufactured have a tendency to have a small dimensional change and excellent durability when sliding intermittently with metal while ensuring practically sufficient productivity.

[Examples 12 to 14]
The evaluation results of the polyoxymethylene intermittent sliding parts of Examples 12 to 14 are shown in Table 5. From the evaluation results of Examples 2 and 12 to 14, the polyoxymethylene resin composition contains the preferred formaldehyde scavenger of the present invention, and the rigidity, impact resistance, and friction coefficient within the scope of the present invention are obtained. It has been found that the intermittent type sliding parts can improve practically sufficient productivity, have a small dimensional change when sliding intermittently with metal, and tend to have excellent durability.

[Example 15]
The evaluation results of the polyoxymethylene intermittent sliding parts of Example 15 are shown in Table 5. From the evaluation results of Examples 2 and 15, even if flakes obtained by pulverizing intermittent sliding parts molded with a polyoxymethylene resin composition are used as raw materials, they are the rigidity, impact resistance, and friction coefficient within the scope of the present invention. If this is the case, the polyoxymethylene intermittent-type sliding part will have a small dimensional change and excellent durability when sliding intermittently with metal while ensuring practically sufficient productivity. I understood it. Moreover, if the physical properties of the flakes obtained by pulverizing the intermittent sliding parts are within the scope of the present invention, the intermittent sliding parts before pulverization slide intermittently with the metal. It was found that the dimensional change was small and excellent durability was obtained.

  The present invention provides a sliding component that is small in dimensional change when intermittently sliding with a metal and has excellent durability while ensuring practically sufficient productivity. For various other sliding parts, selected from the group consisting of wheels, rollers, rollers, washers, spacers, bushes, rotors, pads, swivels, bearings, shaft holes, shafts, pulleys, gears and parts thereof. One or more kinds of polyoxymethylene intermittent sliding parts and parts thereof have industrial applicability.

(X): Member (y): Member (Ia): Pulley (IIb): Shaft B: Load-applying drive belt F: Load direction

Claims (9)

The rigidity is 2500 MPa or more, the impact resistance is 10 kJ / m ² or more, the friction coefficient is 0.15 or less,
A polyoxymethylene resin composition for an intermittent metal-to-metal sliding part, comprising polyoxymethylene containing 0 to 1.0 mol of a comonomer unit with respect to 100 mol of oxymethylene unit.   It has the member (I) formed using the polyoxymethylene resin composition for metal-to-metal intermittent type | mold sliding parts of Claim 1, and metal counterpart material (II), The said member (I) A polyoxymethylene intermittent sliding part in which the mating material (II) is in contact.   The intermittent sliding part made of polyoxymethylene according to claim 2, wherein the rigidity of the polyoxymethylene resin composition is 2650 MPa or more. 4. The polyoxymethylene intermittent sliding component according to claim ² , wherein the impact resistance of the polyoxymethylene resin composition is 13 kJ / m ² or more.   The intermittent sliding part made of polyoxymethylene according to any one of claims 2 to 4, wherein a coefficient of friction of the polyoxymethylene resin composition is 0.12 or less.   The polyoxymethylene intermittent sliding component according to any one of claims 2 to 5, wherein the polyoxymethylene resin composition contains a polyoxymethylene homopolymer.   The polyoxymethylene intermittent sliding component according to any one of claims 2 to 6, wherein the polyoxymethylene resin composition contains a solid lubricant at room temperature.   The polyoxymethylene intermittent sliding component according to any one of claims 2 to 7, wherein the polyoxymethylene resin composition contains a fatty acid ester lubricant.   The polyoxymethylene intermittent sliding component according to any one of claims 2 to 8, wherein the polyoxymethylene resin composition contains a hydrazide compound.