JP4884300B2 - Plastic mechanical parts - Google Patents

Description

  The present invention relates to a resin mechanical component that is used by being intermittently given a lock torque from a drive source.

  Conventionally, resin mechanical parts have been widely used for power transmission parts of office automation equipment such as copiers and printers, VTR tape drive mechanisms, and laser disk player loading mechanisms. In these resin mechanical parts, demands for low noise performance and high speed performance have been increasing. In order to meet this requirement, for example, in the case of gears, attempts have been made to increase the meshing rate or use helical gears.

  Recently, when designing such plastic mechanical parts, transmission errors are considered in addition to high initial accuracy in fatigue strength, transmission efficiency, friction, wear characteristics, strength / rigidity, shape and dimensions of each element, etc. (For example, Patent Documents 1 and 2). In general, the motor that is the driving source momentarily takes a starting torque larger than the rated torque during operation, but since the subsequent operating range is operation near the rated torque, the above-mentioned accuracy and slidability are emphasized. The problem was often solved by the designed design.

  However, according to the spread of usage of resin mechanical parts, it is necessary to apply a lock torque that deviates from the vicinity of the rated torque, maintain the load for several seconds or sometimes several hours, and then re-activate it later. There are cases where it is used in situations where it is repeated.

  Polyacetal resins, on the other hand, have high mechanical strength and rigidity, are excellent in oil resistance and organic solvent resistance, are well balanced in a wide temperature range, and are easy to process. Plastics are mainly used for electrical equipment, mechanical parts of electrical equipment, automobile parts, and other mechanical parts. In particular, it is known that a polyacetal homopolymer is superior in rigidity and toughness and has a high heat distortion temperature compared to a polyacetal copolymer.

  So far, various crystal nucleation agents have been studied as a formulation for improving the physical properties of polyacetal homopolymers. Productivity improvement due to high dimensional accuracy and low warpage due to addition, improvement in shear strength and impact resistance, hardness And improvement of productivity, improvement of shrinkage rate and productivity, and the like (for example, Patent Documents 3, 4, 5, and 6).

  However, these are all studies where the addition amount of the crystal nucleating agent is outside the scope of the present invention, and there has been no study or description regarding use under severe conditions as in the present invention.

  Therefore, there has been a demand for a mechanical component that ensures good operating durability and maintains low noise even when operating with a lock torque applied intermittently.

JP 2001-323991 A Japanese Patent Laid-Open No. 2002-3213 JP-A 51-97652 JP-A-5-279551 JP-A-57-94036 Special Table 2002-200266 gazette

  SUMMARY OF THE INVENTION An object of the present invention is to provide a resin-made mechanical component that is excellent in operation durability and quietness when used by intermittently applying a lock torque from a drive source.

  As a result of intensive studies to achieve the above-mentioned problems, the present inventors have found that the above-described problems can be solved by using a composition containing a specific amount of polyacetal homopolymer and crystal nucleation inorganic particles, thereby completing the present invention. It came to.

  That is, the resin mechanical component of the present invention is a resin mechanical component that is used by being intermittently applied with a lock torque from a drive source having a lock torque of 12 N · m or less, and the resin is a polyacetal homopolymer. It is a resin composition containing 10 to 90 ppm of crystal nucleation inorganic particles having an average particle size of 0.1 to 10 μm.

  The resin mechanical part of the present invention has the same quality and thermal stability as a conventional mechanical part made of polyacetal homopolymer, and is durable when operated with a lock torque intermittently applied from a driving source. Excellent in performance and silence.

  Hereinafter, the resin mechanical component of the present invention will be described.

≪Resin mechanical parts≫
The resin mechanical component of the present invention is used by being intermittently given a lock torque from a drive source having a lock torque of 12 N · m or less. When the lock torque exceeds 12 N · m, it becomes difficult to maintain the durability of the resin mechanical parts.

  An example of the driving source is a motor. The rotation speed of the motor becomes maximum when there is no load torque, and gradually decreases as the load is applied. The lock torque in the motor means a torque when a load is applied to the rotating motor and the rotation stops. The rated operating speed and operating torque in normal operation are often set in an efficient region in the characteristics of the motor, and the lock torque may take 1.5 to 5 times the rated operating torque because of its performance. Many. In the present invention, it is preferable that the motor substantially connected to the resin-made mechanism component has an operation speed of 15000 rpm or less. If this is exceeded, it may be difficult for the resin-made mechanical parts to exhibit quietness.

  Examples of resin mechanical parts include gears, cams, sliders, levers, arms, clutches, felt clutches, idler gears, pulleys, rollers, rollers, key stems, key tops, shutters, reels, shafts, joints, shafts, bearings, etc. Examples include guides. In addition, resin parts for outsert molding, resin parts for insert molding, chassis, trays, side plates and the like can be mentioned.

  Of these, gears are preferred. Here, the gear is, for example, a helical gear, a spur gear, an internal gear, a rack gear, a helical gear, a straight bevel gear, a helical bevel gear, a helical bevel gear, a crown gear, a face gear, or a screw gear. , Worm gear, worm wheel gear, hypoid gear, novikov gear and the like. Further, these helical gears and spur gears may be a single gear, a two-stage gear, or a combination gear having a structure that reduces the rotational unevenness by combining the drive motor in multiple stages. . The resin gear preferably has a pitch circle equivalent diameter of 12 cm or less. If it exceeds this, not only productivity will be lowered, but it will be difficult to obtain a stable molded product, which may make it difficult to maintain durability.

  The resin mechanical component of the present invention is preferably used by applying grease. As a result, the operating durability and quietness may be greatly improved.

  Production of the resin mechanical part of the present invention is not particularly limited, and known molding methods such as extrusion molding, injection molding, vacuum molding, blow molding, injection compression molding, decorative molding, other material molding, gas It can be molded by any one of molding methods such as assist injection molding, firing injection molding, low pressure molding, ultra thin injection molding (ultra high speed injection molding), and in-mold composite molding (insert molding, outsert molding). In particular, from the viewpoint of productivity, durability, and quality, a molding method in which injection molding, injection compression molding, or a combination of these and in-mold composite molding is preferable.

  The resin mechanical part of the present invention has the same quality and thermal stability as a conventional mechanical part made of polyacetal homopolymer, and is durable when operated with a lock torque intermittently applied from a driving source. Because of its excellent performance and quietness, it can be used for molded products for various purposes.

  Specific applications of the resin mechanical parts of the present invention include mechanical parts for office automation equipment, mechanical parts for cameras or video equipment, mechanical parts for music, video or information equipment, mechanical parts for communication equipment, mechanical parts for electrical equipment. , Mechanical parts for electronic equipment, mechanical parts for automobiles (door peripheral parts, seat peripheral parts, air conditioner peripheral parts), switch parts, stationery mechanism parts, housing equipment mechanism parts, vending machine mechanism parts, sports / leisure / Mechanical parts for recreational equipment, industrial parts for industrial equipment, and mechanical parts for medical supplies and nursing care products.

≪Resin composition≫
[Polyacetal homopolymer]
<Polymerization>
The polyacetal homopolymer of the present invention represents a polymer having an oxymethylene group in the main chain and having both ends of the polymer chain blocked with an ester group or an ether group. The polymerization form in the production of the polyacetal homopolymer can be carried out using a known slurry polymerization method (for example, Japanese Patent Publication No. 47-6420 and Japanese Patent Publication No. 47-10059). Thereby, the crude polyacetal whose terminal is not stabilized can be obtained.

<Monomer>
For example, formaldehyde can be used as the monomer. In order to continuously obtain a stable molecular weight resin, purified formaldehyde gas having a low impurity concentration and stable is used. As a purification method of formaldehyde, a known method (for example, Japanese Patent Publication No. 5-32374 and Japanese Patent Publication No. 2001-521916) can be used. As the formaldehyde gas in the present invention, a gas 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, is used. If these impurities are excessively present, the desired molecular weight product cannot be obtained due to an unexpected chain transfer reaction. In particular, water is preferably 100 ppm or less, and more preferably 50 ppm or less.

<Chain transfer agent>
As the chain transfer agent, alcohols and acid anhydrides can be generally used. In order to obtain a block polymer or a branched polymer, a polyol, a polyether polyol, or a polyether polyol / alkylene oxide may be used. Further, a chain transfer agent that does not contain impurities as much as possible is used. Among these, water is preferably 2000 ppm or less, more preferably 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 moisture content exceeding a specified amount is obtained, and this is bubbled with dry nitrogen, and an adsorbent such as activated carbon or zeolite. And a method of removing impurities and purifying them. The chain transfer agent used here may be used alone or in combination of two or more.

<Polymerization catalyst>
As the onium salt-based polymerization catalyst used in the polymerization reaction, those represented by the following general formula (1) can be used.
[R ₁ R ₂ R ₃ R ₄ M] ⁺ X ⁻ (1)
(Wherein 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 general 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.

<Reactor>
As a polymerization reactor, a batch type reaction vessel with a stirrer, a continuous type kneader, a twin screw type continuous extrusion kneader, a twin screw paddle type continuous mixer and the like can be used. The outer peripheries of these cylinders preferably have a structure capable of heating or cooling the reaction mixture.

<Terminal stabilization>
As a method for blocking the terminal stabilization of the crude polyacetal with an ether group, there is a method described in JP-B 63-452, and as a method for blocking with an acetyl group, US Pat. No. 3,459,709 is described. There are a method of using a large amount of acid anhydride in a slurry state and a method of performing gas phase using an acid anhydride gas described in US Pat. No. 3,172,736. Is not particularly specified.

  Etherifying agents used to block with ether groups include orthoesters, usually orthoesters of aliphatic or aromatic acids with aliphatic, alicyclic or aromatic alcohols such as methyl or ethyl orthoformate, Mention may be made of methyl or ethyl orthoacetate and methyl or ethyl orthobenzoate, and orthocarbonates such as ethyl orthocarbonate. The etherification reaction consists of 1 part by weight of a Lewis acid type catalyst such as p-toluenesulfonic acid, medium strength organic acids such as acetic acid and hydrobromic acid, medium strength mineral acids such as dimethyl and diethyl sulfate, etc. For example, by introducing 0.001 to 0.02 part by weight with respect to. Preferred solvents for the etherification reaction are organics such as low-boiling aliphatics such as pentane, hexane, cyclohexane and benzene, alicyclic and aromatic hydrocarbons, halogenated lower aliphatic compounds such as methylene chloride, chloroform and carbon tetrachloride. A solvent is mentioned.

On the other hand, when the terminal of the polymer is blocked with an ester group, examples of the organic acid anhydride used for esterification include organic acid anhydrides represented by the following general formula (2).
R ₁ COOCOR ₂ (2)
(In the formula, R ₁ and R ₂ each independently represent an alkyl group. R ₁ and R ₂ may be the same or different.)

  Among the organic acid anhydrides represented by the general 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 preferable. Particularly preferred. One organic acid anhydride may be used, but two or more organic acid anhydrides may be used.

  In addition, in the method of performing ester group blocking in the gas phase, if the onium salt-based polymerization catalyst remains in the polymer resin, the onium salt-based polymerization catalyst promotes the decomposition reaction of the polymer when end-blocking. As a result, the polymer yield in the stabilization reaction is remarkably lowered, and the problem of coloring the polymer appears particularly remarkably. Therefore, the terminal after the onium salt-based polymerization catalyst is removed by the method described in JP-A-11-92542 It is particularly preferred to perform the blocking.

The end of the polymer is preferably 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. If the concentration of the terminal hydroxyl group is more than 5 × 10 ⁻⁷ mol / g, the thermal stability may be impaired, and the quality of the original polyacetal resin may be lowered. More preferably, the concentration of the terminal hydroxyl group is 0.5 × 10 ⁻⁷ mol / g or less.

[Finishing process]
The polymer powder that has been end-stabilized is dried and then pelletized using an extruder for better handling. The resin composition of the present invention is obtained by mixing polyacetal homopolymer and crystal nucleating inorganic particles with a Henschel mixer, tumbler, V-shaped blender, etc., and then melt-kneading using a single-screw or multi-screw kneading extruder or the like. You can get things. In this case, a twin-screw extruder equipped with a decompression device is preferable. Moreover, it is also possible to obtain a resin composition by batch feeding or dividing the crystal nucleation inorganic particles with a quantitative feeder or the like and continuously feeding them to an extruder without mixing in advance. Moreover, a resin composition or a molded body can be obtained by preparing a high-concentration master batch composed of a polyacetal homopolymer and an additive component in advance and adding it to the polyacetal homopolymer during extrusion melt kneading or molding.

[MFR]
In order to maintain silence in the conventional usage, attempts have been made to obtain a molded product with high accuracy by having a large MFR value and good fluidity. However, in a mechanical component that is used by being intermittently given a lock torque from the driving source of the present invention, the resin composition preferably has a lower MFR of 1.5 g / 10 min or more. More preferably, it is 7 g / 10 min or more. If the MFR is less than 1.5 g / 10 min, it is difficult to produce a stable molded product, which may make it difficult to maintain silence. Moreover, it is preferable that the upper limit of MFR is 15.0 g / 10min or less, and it is more preferable that it is 9.0 g / 10min or less. When MFR is larger than 15.0 g / 10 min, a stable molded product can be obtained, but it may be difficult to maintain the operation durability.

[Crystal nucleation inorganic particles]
The crystal nucleation inorganic particles of the present invention have an average particle size of 0.1 to 10.0 μm, preferably 0.5 to 6.0 μm. When the average particle size is smaller than 0.1 μm, the quietness is lowered. On the other hand, if it is larger than 10.0 μm, the operation durability is lowered. The average particle diameter is measured by a known method. For example, by cutting out the obtained resin mechanical parts and decomposing the resin part, the remaining inorganic content is observed with a microscope (optical microscope, SEM, SEM-EDX), and by measuring the particle size of any particle, A method for deriving the average particle diameter is included.

  The crystal nucleation inorganic particles of the present invention are contained in the polyacetal homopolymer in an amount of 10 to 90 ppm, preferably 20 to 80 ppm. If it is less than 10 ppm, the quietness is lowered. On the other hand, if it exceeds 90 ppm, the operation durability is lowered. In order to quantify the crystal nucleation inorganic particles, for example, a method of hydrolyzing the obtained resin mechanical parts with hydrochloric acid or the like and a method of quantifying a metal component by high frequency inductively coupled plasma (ICP) emission analysis may be mentioned. .

  Crystal nucleation inorganic particles of the present invention include, for example, talc, silica, quartz powder, glass powder, calcium silicate, aluminum silicate, kaolin, phyllite, clay, diatomaceous earth, wollastonite and other silicates, iron oxide and oxide Metal oxides such as titanium and alumina, metal sulfates such as calcium sulfate and barium sulfate, carbonates such as calcium carbonate, magnesium carbonate and dolomite, and other polyacetal homopolymers such as silicon carbide, silicon nitride, boron nitride and various metal powders Any finely divided solid of a generally known crystal nucleation inorganic substance may be used. Among these crystal nucleation inorganic particles, boron nitride or talc is particularly preferable.

  A known surface treating agent can be used for the crystal nucleation inorganic particles of the present invention in order to improve the affinity and dispersibility with the resin. Examples of surface treatment agents include silane coupling agents such as amino silane and epoxy silane, titanate coupling agents, fatty acids (saturated fatty acids, unsaturated fatty acids), alicyclic carboxylic acids, resin acids, and metal soaps. it can. The addition amount of the surface treatment agent is preferably 3% by mass or less, more preferably 2% by mass or less, and most preferably, it is not substantially added.

[Other additives]
The resin composition of the present invention includes, as other additives, a heat stabilizer and an antioxidant, an acid scavenger, a weathering (light) stabilizer, a release agent / lubricant, a conductive material / antistatic agent, and a thermoplastic resin. In addition, a known additive that can be added to a normal polyacetal homopolymer, such as a thermoplastic elastomer and a pigment, in a range not impairing the object of the present invention, can be blended as necessary. As the method of addition, as with the crystal nucleation inorganic particles, the polyacetal homopolymer and other additives are mixed with a Henschel mixer, tumbler, V-shaped blender, etc., and then a single-screw or multi-screw kneading extruder is used. A resin composition can be obtained by melting and kneading. Among these, a twin screw extruder equipped with a decompression device is preferable. In addition, the composition may be obtained by mixing each component individually or in groups of several using a quantitative feeder or the like and continuously feeding them to an extruder without mixing in advance. Moreover, the resin composition of this invention can also be obtained by producing a high concentration masterbatch and diluting with a polyacetal homopolymer at the time of extrusion melt-kneading or shaping | molding.

<Thermal stabilizer and antioxidant>
The fat composition of the present invention preferably contains a heat stabilizer and an antioxidant. The heat stabilizer preferably contains formaldehyde-reactive nitrogen, and the antioxidant is preferably a hindered phenol type.

  Examples of heat stabilizers containing formaldehyde-reactive nitrogen include nylon 4-6, nylon 6, nylon 6-6, nylon 6-10, nylon 6-12, nylon 12 and other polyamide resins, and polymers thereof. For example, nylon 6 / 6-6 / 6-10, nylon 6 / 6-12, etc. can be mentioned. Other examples include acrylamide and its derivatives, and copolymers of acrylamide and its derivatives and other vinyl monomers, such as those obtained by polymerizing acrylamide and its derivatives and other vinyl monomers in the presence of a metal alcoholate. And poly-β-alanine copolymer. Other examples include amide compounds, amino-substituted triazine compounds, adducts of amino-substituted triazine compounds and formaldehyde, condensates of amino-substituted triazine compounds and formaldehyde, urea, urea derivatives, hydrazine derivatives, imidazole compounds, and imide compounds.

Specific examples of the amide compound include polycarboxylic acid amides such as isophthalic acid diamide and anthranilamides. Specific examples of the amino-substituted triazine compound include 2,4-diamino-sym-triazine, 2,4,6-triamino-sym-triazine, N-butylmelamine, N-phenylmelamine, N, N-diphenylmelamine, N , N-diallylmelamine, benzoguanamine (2,4-diamino-6-phenyl-sym-triazine), acetoguanamine (2,4-diamino-6-methyl-sym-triazine), 2,4-diamino-6-butyl -Sym-triazine and the like. Specific examples of the adduct of an amino-substituted triazine compound and formaldehyde include N-methylol melamine, N, N′-dimethylol melamine, and N, N ′, N ″ -trimethylol melamine. Specific examples of condensates of triazine compounds and formaldehyde include melamine / formaldehyde condensates, and examples of urea derivatives include N-substituted urea, urea condensate, ethylene urea, hydantoin compound, and ureido compound. .N may be mentioned ^- specific examples of the substituted urea, methyl urea substituent is substituted, such as alkyl groups, specific examples of alkylene bis urea, can be mentioned Ariru substituted urea urea condensates. And condensates of urea and formaldehyde, etc. Specific examples of hydantoin compounds Examples thereof include hydantoin, 5,5-dimethylhydantoin, 5,5-diphenylhydantoin, etc. Specific examples of ureido compounds include allantoin, etc. Examples of hydrazine derivatives include hydrazide compounds. Specific examples of the hydrazide compound include dicarboxylic acid dihydrazide. More specifically, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, pimelic acid dihydrazide, superic acid dihydrazide, and azelaic acid dihydrazide. And sebacic acid dihydrazide, dodecanedioic acid dihydrazide, isophthalic acid dihydrazide, phthalic acid dihydrazide, 2,6-naphthalenedicarbodihydrazide, etc. Specific examples of imide compounds. It can be mentioned succinimide, glutarimide, phthalimide.

  These polymers or compounds containing formaldehyde-reactive nitrogen atoms may be used alone or in combination of two or more.

  Examples of the hindered phenol antioxidant include n-octadecyl-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) -propionate, n-octadecyl-3- (3′- Methyl-5′-t-butyl-4′-hydroxyphenyl) -propionate, n-tetradecyl-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) -propionate, 1,6- Hexanediol-bis- [3- (3,5-di-t-butyl-4-hydroxyphenyl) -propionate], 1,4-butanediol-bis- [3- (3,5-di-t-butyl) -4-hydroxyphenyl) -propionate], triethylene glycol-bis- [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) -propionate], Pentaerythritol tetrakis [methylene-3- (3 ', 5'-di -t- butyl-4'-hydroxyphenyl) propionate] methane, and the like. Preferably, triethylene glycol-bis- [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) -propionate] and pentaerythritol tetrakis [methylene-3- (3 ′, 5′-di-t -Butyl-4'-hydroxyphenyl) propionate] methane.

  These antioxidants may be used alone or in combination of two or more.

  The mechanical component of the present invention may be used with grease applied in order to further improve the quietness. In this case, it is desired to maintain the same operation durability as that of the conventional mechanical parts even when grease is applied. For this reason, it is preferable that 0.1 to 1.5 parts by weight of a heat stabilizer containing formaldehyde-reactive nitrogen and a hindered phenol-based antioxidant are included per 100 parts by weight of the polyacetal homopolymer. If the amount is less than this, it may be difficult to maintain the resistance to grease.

<Others>
Examples of the acid scavenger include condensates of the above amino-substituted triazine compounds and amino-substituted triazine compounds with formaldehyde, such as melamine / formaldehyde condensates. Other formic acid scavengers include alkali metal or alkaline earth metal hydroxides, inorganic acid salts, carboxylate salts or alkoxides. For example, hydroxides such as sodium, potassium, magnesium, calcium or barium, carbonates, phosphates, silicates, borates, carboxylates, and layered double hydroxides of the above metals can be used. .

  The carboxylic acid of the carboxylate is preferably a saturated or unsaturated aliphatic carboxylic acid having 10 to 36 carbon atoms, and these carboxylic acids may be substituted with a hydroxyl group. Specific examples of saturated or unsaturated aliphatic carboxylates include calcium dimyristate, calcium dipalmitate, calcium distearate, (myristic acid-palmitic acid) calcium, (myristic acid-stearic acid) calcium, ( (Palmitic acid-stearic acid) calcium is mentioned, and among them, calcium dipalmitate and calcium distearate are preferable.

Examples of the layered double hydroxide include hydrotalcites represented by the following general formula (3).
[(M ²⁺ ) _1-X (M ³⁺ ) X (OH) ₂ ] _X ⁺ [(A ⁿ⁻ ) _{x / n} · mH ₂ O] _X ⁻ (3)
Wherein, M ²⁺ is a divalent metal, M ³⁺ represents an anion of 3-valent metal, A ^n-n-valent (n is an integer of 1 or more), X is in the range of 0 <X ≦ 0.33 M is a positive number. ]

In the general formula (1), Mg ²⁺ examples of ^{M 2+, Mn 2+, Fe 2+} , Co 2+, Ni 2+, Cu 2+, Zn 2+ , etc., as examples of M ³⁺ is ^{, Al 3+, Fe 3+, Cr} 3+, Co 3+, in 3+ , etc., as an example of a ^{n- is, OH -, F -, Cl} -, Br -, NO 3 -, CO 3 2- , SO ₄ ²⁻ , Fe (CN) ₆ ³⁻ , CH ₃ COO ⁻ , oxalate ion, salicylate ion, and the like. Particularly preferred examples include OH ⁻ and CO ₃ ²⁻ . Specific examples include natural hydrotalcite represented by Mg _0.75 Al _0.25 (OH) ₂ (CO ₃ ) _0.125 · 0.5H ₂ O, Mg _4.5 Al ₂ (OH) ₁₃ CO ₃ · 3.5H ₂ O, Mg _4.3 Synthetic hydrotalcite represented by Al ₂ (OH) _12.6 CO ₃ or the like.

  These acid scavengers may be used alone or in combination of two or more.

  The weather resistance (light) stabilizer is preferably one or more selected from benzotriazole-based, oxalic anilide-based ultraviolet absorbers and hindered amine-based light stabilizers.

  Examples of benzotriazole ultraviolet absorbers include 2- (2′-hydroxy-5′-methyl-phenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-t-butyl-phenyl). ) Benzotriazole, 2- [2′-hydroxy-3 ′, 5′-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2- [2′-hydroxy-3 ′, 5′-bis -(Α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2- (2′-hydroxy-4′-octoxyphenyl) benzotriazole and the like. Examples of the oxalic acid alinide ultraviolet absorbers include 2-ethoxy-2′-ethyloxalic acid bisanilide, 2-ethoxy-5-tert-butyl-2′-ethyloxalic acid bisanilide, and 2-ethoxy. -3'-dodecyl oxalic acid bisanilide and the like. Preferably, 2- [2′-hydroxy-3 ′, 5′-bis- (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di -T-butyl-phenyl) benzotriazole. These benzotriazole-based UV absorbers may be used alone or in combination of two or more.

  Examples of hindered amine light stabilizers include N, N ′, N ″, N ′ ″-tetrakis- (4,6-bis- (butyl- (N-methyl-2,2,6,6-tetra). Methylpiperidin-4-yl) amino) -triazin-2-yl) -4,7-diazadecane-1,10-diamine, dibutylamine 1,3,5-triazine N, N′-bis (2,2 , 6,6-tetramethyl-4-piperidyl-1,6-hexamethylenediamine and N- (2,2,6,6-tetramethyl-4-piperidyl) butylamine polycondensate, poly [{6- ( 1,1,3,3-tetramethylbutyl) amino-1,3,5-triazine-2,4-diyl} {(2,2,6,6-tetramethyl-4-piperidyl) imino} hexamethylene { (2,2,6,6-tetramethyl-4-pi Lysyl) imino}], dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol condensate, bis (2,2,6,6-tetramethyl-1) decanoate Reaction product of-(octyloxy) -4-piperidinyl) ester, 1,1-dimethylethyl hydroperoxide and octane, bis (1,2,2,6,6-pentamethyl-4-piperidyl) [[3,5 -Bis (1,1-dimethylethyl) -4-hydroxyphenyl] methyl] butyl malonate, methyl-1,2,2,6,6-pentamethyl-4-piperidyl sebacate, bis (2,2,6, 6-tetramethyl-4-piperidyl) -sebacate, 1,2,3,4-butanetetracarboxylic acid and 1,2,2,6,6-pentamethyl-4-piperidinol and β, β, Examples include condensates with ', β'-tetramethyl-3,9- [2,4,8,10-tetraoxaspiro (5,5) undecane] diethanol, etc., preferably bis (2,2,6 , 6-tetramethyl-4-piperidyl) -sebacate, bis- (N-methyl-2,2,6,6-tetramethyl-4-piperidinyl) sebacate, 1,2,3,4-butanetetracarboxylic acid 1,2,2,6,6-pentamethyl-4-piperidinol and β, β, β ′, β′-tetramethyl-3,9- [2,4,8,10-tetraoxaspiro (5,5) Undecane] is a condensate with diethanol, and these hindered amine light stabilizers may be used alone or in combination of two or more.

  As the release agent / lubricant, alcohol, fatty acid and fatty acid ester thereof, polyoxyalkylene glycol, olefin compound having an average polymerization degree of 10 to 500, and silicone are preferably used.

  Examples of the conductive agent include conductive carbon black, carbon nanotubes or nanofibers or nanoparticles, metal powder or fibers. Antistatic agents include aliphatic polyethers (excluding compounds with terminal fatty acid esters), aliphatic polyethers with terminal fatty acid esters, and free hydroxyl groups derived from fatty acids and polyhydric alcohols. Fatty acid fatty acid ester, boric acid ester of glycerin monofatty acid ester, ethylene oxide adduct of amine compound, basic carbonate or anion exchanger thereof as a base, polyalkylene polyol or alkali metal salt-dissolved polyalkylene polyol And an antistatic agent in which is encapsulated.

  Examples of the thermoplastic resin include polyolefin resin, acrylic resin, styrene resin, polycarbonate resin, and uncured epoxy resin. These modified products are also included. Examples of the thermoplastic elastomer include polyurethane elastomers, polyester elastomers, polystyrene elastomers, and polyamide elastomers.

  Examples of the pigment include inorganic pigments, organic pigments, metallic pigments, fluorescent pigments, and the like. Inorganic pigments are those commonly used for resin coloring, such as zinc sulfide, titanium oxide, barium sulfate, titanium yellow, cobalt blue, combustion pigments, carbonates, phosphates, acetic acid. It refers to salt, carbon black, acetylene black, lamp black and the like. Organic pigments include condensed azo, inone, furothocyanin, monoazo, diazo, polyazo, anthraquinone, heterocyclic, pennon, quinacridone, thioindico, berylene, dioxazine, phthalocyanine, etc. Or other pigments.

  Hereinafter, the present invention will be described in more detail by way of examples and comparative examples using a motor and gears as representatives of drive sources and mechanism parts. The present invention is not limited by these.

[Evaluation sample]
<Collecting polyacetal homopolymer>
Polyacetal homopolymers P1 to P4 were produced using a jacketed 5 L tank polymerizer equipped with a stirrer as shown in FIG.

  In FIG. 1, (a) is a stirring motor with a stirring blade, (b) is a reactor with a jacket, (c) is a slurry circulation pump, (1) is a supply of formaldehyde gas, (2) is a chain transfer agent and polymerization. Supply of solvent, (3) is supply of polymerization catalyst, and (4) is slurry collection.

  The jacketed reactor (b) is filled with 2 L of n-hexane and a circulation line is provided. The length of the line is 6φ × 2.5 m, and it is circulated at 20 L / hr by the slurry circulation pump (c). Into this, 200 g / hr of dehydrated formaldehyde gas is directly supplied (1). The catalyst (dimethyl distearyl ammonium acetate) is supplied to the circulation line immediately before the reactor (3), and the chain transfer agent (acetic anhydride) is added to hexane to supplement the slurry to be extracted in the next step, and continuously. While feeding (2), polymerization was carried out at 58 ° C. to obtain a polymerization slurry containing a crude polymer. The polymerization catalyst and chain transfer agent to be added were adjusted according to the MFR of the composition as the final product.

  Stabilization is performed by reacting the obtained 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, depressurized to 2 mmHg or less, and dried for 3 hours with a vacuum dryer set at 80 ° C. to obtain a polyacetal homopolymer powder.

<Preparation of pellet sample>
After mixing the polyacetal homopolymer powder and additives in the ratio shown in Table 1 for 1 minute with a Henschel mixer, a screw type twin screw extruder with a vent set to 200 ° C. (BT-30 manufactured by Plastic Industry Co., Ltd.) L / D = 44), the screw speed was 100 rpm, and melt kneading was performed at 24 amps to obtain sample pellets of the resin composition. From raw material input to pellet collection, the operation was performed while avoiding oxygen contamination as much as possible.

<Gear shaping>
The pellets of the resin composition were set to a cylinder temperature of 210 ° C. and a mold temperature of 80 ° C. using an injection molding machine (ROBOSHOT α-50iA manufactured by FANUC CORPORATION) and molded using a helical gear mold shown in Table 2. The tooth gap error JIS 3-5 grade test gear was obtained.

[Evaluation methods]
<Evaluation of resin composition>
1. MFR of resin composition
After the obtained pellet sample was dried at 80 ° C. for 3 hours, MFR (based on ASTM D-1238-57T) was measured at a load of 2.16 kg and a cylinder temperature of 190 ° C. In general, when this value is large, the fluidity is high and it is an indicator that the moldability is excellent. The results are shown in Table 1.

2. Molding of dumbbells The pellets of the resin composition were set to an injection molding machine (SH-75 manufactured by Sumitomo Heavy Industries, Ltd.) with a cylinder temperature of 200 ° C. and a mold temperature of 90 ° C., an injection pressure of 70 MPa, and an injection time of 60 seconds. Then, molding was performed using an ISO mold (based on ISO 527) under injection conditions of cooling for 15 seconds to obtain a dumbbell test piece for evaluation.

3. Average particle diameter of crystal nucleation inorganic particles The above dumbbell test piece was freeze-ground and mixed with a 0.1N hydrochloric acid aqueous solution to prepare a product prepared in a glass pressure bottle. This is decomposed under pressure in a sterilizer at 130 ° C. for 6 to 10 hours, and then the decomposition solution is filtered, and the filtration residue is further washed and filtered with formic acid and chloroform to add other than crystal nucleation inorganic particles The agent was removed.

  The remaining crystal nucleation inorganic particles were dried under reduced pressure, and then a particle image was observed and photographed using a digital microscope (VHX-200 / 100F 500-5000 times, manufactured by KEYENCE Corp.), arbitrarily selected 100 The maximum particle diameter (maximum major axis) of the individual crystal nucleation inorganic particles was measured, and the number average was taken as the average particle diameter. The results are shown in Table 1.

4). Content of crystal nucleation inorganic particles The dumbbell test piece was weighed after freeze-grinding, mixed with a 0.1N hydrochloric acid aqueous solution, and then 10 batches prepared in a glass pressure bottle were prepared. These were decomposed under pressure in a sterilizer at 130 ° C. for 6 to 10 hours, then 10 batches of decomposition solution were filtered, and the filtration residue was further washed and filtered with formic acid and chloroform to produce crystal nucleation inorganic Additives other than the particles were removed.

  The remaining crystal nucleation inorganic particles were dried under reduced pressure and weighed, and the content of crystal nucleation inorganic particles in the composition was expressed in mass%. The results are shown in Table 1.

<Evaluation of gears>
For the evaluation of the operation durability / silence, a power absorption type gear strength tester as shown in FIG. An appropriate drive motor and power absorbing device (powder clutch / brake) were selected according to the test conditions.

  In FIG. 2, (a1) is a drive motor, (a2) is a bearing support, (a3) is a tachometer, (b1) is a power absorber, (b2) is a bearing support, (b3) is a torque meter, c1) is a microphone, (c2) is a sound level meter, (d1) is a soundproof box, (A) is a metal gear, and (B) is a test gear.

  The test machine shown in FIG. 2 has a metal gear (A) (module: 0.8, pitch circle diameter: 20 mm, tooth width: 10 mm, helix angle: 20 degrees) via a shaft to a drive motor (a1). A tooth metal gear is installed so that it can be operated at an arbitrary rotational speed. The metal gear (A) and the test gear (B) are meshed with a backlash amount of 0.1 mm. The test gear (B) is connected to the power absorbing device (b1) via a shaft so that an arbitrary load torque can be applied.

◇ Test method in gear strength testing machine Rotating for 1 hour with operating torque (assumed) (Run 1) → Applying lock torque (assumed) for 10 seconds → Rotating again with operating torque for 1 hour (Run 2) → Re-locking torque Apply for 10 seconds → Re-rotate for 1 hour with operating torque (Run 3)

  Assuming characteristics of various motors, the lock torque here is set so that the operating torque is 25% of the lock torque, and the gear stop position is always the same when locking. In addition, in order to evaluate the performance of the test gear under various conditions when the drive source performs equivalent work, the output of the drive motor is constant (the product of the rotational speed (rpm) and the operating torque (N · m) is 200). As implemented. The test was performed in a constant temperature room at 23 ° C. and 50% humidity.

1. Operation Durability Regarding the operation durability, the operability just before the end of “Run 3” and the appearance of the gears before and after the test were evaluated according to the following criteria.
◎: Operability immediately before the end of “Run 3”, no problem with the appearance of the gear before and after the test ○: Change in the appearance of the gear before and after the test, but the operability just before the end of “Run 3” △: There is a problem with the operability just before the end of “Run 3”. ×: Malfunction due to tooth breakage or shaft hole deformation before reaching “Run 3”.

2. As shown in FIG. 2, a microphone (c1) is installed at a location 50 mm away from the shaft of the metal gear (A), as shown in FIG. The noise level was measured with a sound level meter (c2) (conforms to JIS C1502) at 1 minute (late noise) 30 minutes after the start of “operation 3” and evaluated based on the following criteria.
A: The maximum noise level is lower than 70 dB. O: The maximum noise level is 70 dB or more and less than 75 dB. Δ: The maximum noise level is 75 dB or more and less than 85 dB. X: The maximum noise level is more than 85 dB.

<Evaluation of grease resistance>
The above-mentioned dumbbell test piece was immersed in grease. As an evaluation grease, Martemp-D No. No. 2 (manufactured by Kyodo Mineral Co., Ltd.) was used as immersion conditions at a temperature of 100 ° C. and a time of 1000 hours. The evaluation was performed according to the following criteria by conducting a tensile test according to ISO 527.
A: Elongation retention before and after immersion is 90% or more. O: Elongation retention before and after immersion is 80% or more and less than 90%. Δ: Elongation retention before and after immersion is 70%. More than less than 80% x: elongation retention before and after immersion is less than 70%

[Examples 1-12, Comparative Examples 1-8]
Tables 3 and 4 show the samples used, the evaluation conditions, and the evaluation results.

  From Examples 1-12, it turns out that the gear of this invention has the outstanding operation | movement durability and silence in various driving | running conditions from which torque and rotation speed differ.

  On the other hand, Comparative Examples 1 to 8 that do not contain crystal nucleating inorganic particles are inferior in operation durability or noise reduction compared to Examples 1 to 12 under various conditions.

[Comparative Examples 9 to 14]
Table 5 shows the samples used, the evaluation conditions, and the evaluation results.

  In Comparative Examples 9 to 11 in which the lock torque deviates from the scope of the present invention, the quietness and the operation durability are lowered as compared with Examples 1 to 3 that use the same resin composition and perform the same work.

  Moreover, it turns out that the comparative examples 12-14 from which a lock torque remove | deviates from the scope of the present invention have lower noise and operational durability than the first to third examples using the same sample, although the work is different.

[Examples 13-15, Comparative Examples 15-17]
Table 6 shows the samples used, the evaluation conditions, and the evaluation results.

  From Examples 13-15, it turns out that the gear of this invention has the outstanding operation | movement durability and silence.

  On the other hand, Comparative Examples 15 to 17 in which the particle size of the crystal nucleation inorganic particles deviated from the scope of the present invention were more durable in operation or quieter than Examples 13 to 15 and Examples 1, 2, and 4. Inferior.

[Examples 16 to 18, Comparative Examples 18 to 20]
Table 7 shows the samples used, the evaluation conditions, and the evaluation results.

  From Examples 16-18, it turns out that the gear of this invention has the outstanding operation | movement durability and silence.

  On the other hand, Comparative Examples 18 to 20 in which the addition amount of the crystal nucleation inorganic particles departs from the scope of the present invention, compared with Examples 16 to 18 and Examples 1, 2, 4, 13, and 14, the operation durability. Or it is inferior in silence.

[Examples 19 to 24]
Table 8 shows the samples used, the evaluation conditions, and the evaluation results.

  From Examples 19 to 21, it can be seen that as the number of rotations of Examples 4 to 6 that perform the same work is increased, the quietness gradually decreases. It can also be seen that there is no significant decrease in operating durability.

  Further, from comparison between Examples 22 to 24 and Examples 19 to 21, when the gear diameter is increased at the same operating torque / rotation speed, although the work is different, the torque of the teeth is reduced, but the remaining molding distortion is large. For this reason, it can be seen that the operating durability decreases.

[Examples 25 to 30]
Table 9 shows the samples used, the evaluation conditions, and the evaluation results.

  From Examples 25 to 30, it can be seen that when the MFR of the resin composition decreases or increases, the silence and the operation durability decrease. The improvement in fluidity and accuracy did not affect the evaluation of the present invention.

[Examples 31 to 34]
Table 10 shows the samples used, the evaluation conditions, and the evaluation results.

  From Examples 31 to 34, it can be seen that as the heat stabilizer / antioxidant of the resin composition increases, the quietness gradually decreases. It can also be seen that the grease resistance gradually decreases as the amount of heat stabilizer / antioxidant decreases.

  As described above, the resin mechanical component of the present invention is used when the lock torque is intermittently applied from the driving source and is excellent in operation durability and quietness. It can be suitably used in such fields.

1 is a schematic view around a homopolymer polymerization vessel. It is a schematic diagram of a gear strength tester used for evaluation.

Explanation of symbols

(A) ... Stirring blade-attached stirring motor (b) ... Jacketed reactor (c) ... Slurry circulation pump (1) ... Formaldehyde gas supply (2) ... Chain transfer agent And polymerization solvent supply (3) ... polymerization catalyst supply (4) ... slurry collection (a1) ... drive motor (a2) ... bearing support (a3) ... tachometer (b1 ) ... Power absorber (b2) ... Bearing support (b3) ... Torque meter (c1) ... Microphone (c2) ... Noise meter (d1) ... Soundproof box (A) ) ... Metal gear (B) ... Test gear

Claims (7)

  A resin mechanical component that is used by being intermittently given a lock torque from a drive source having a lock torque of 12 N · m or less, wherein the resin has a polyacetal homopolymer and an average particle size of 0.1 to 10 μm. A resin-made mechanical component, which is a resin composition containing 10 to 90 ppm of crystal nucleation inorganic particles.   2. The resin mechanical component according to claim 1, wherein the resin mechanical component is used by applying grease.   3. The resin mechanical component according to claim 1, wherein the drive source is a motor having an operation speed of 15000 rpm or less.   The resin mechanical component according to any one of claims 1 to 3, wherein the gear has a pitch circle diameter of 12 cm or less.   5. The resin mechanical component according to claim 1, wherein the MFR of the resin composition is 1.5 g / 10 min to 15.0 g / 10 min.   The resin-made mechanical component according to any one of claims 1 to 5, wherein the crystal nucleation inorganic particles contain either talc or boron nitride.   The resin composition includes 0.1 to 1.5 parts by weight of a heat stabilizer containing formaldehyde-reactive nitrogen and a hindered phenol antioxidant, respectively, with respect to 100 parts by weight of a polyacetal homopolymer. The resin-made mechanism component according to any one of claims 1 to 6.

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