JP4895139B2 - Polyacetal resin molding - Google Patents

Description

  The present invention relates to a molded article of polyacetal resin that has less formaldehyde generation, less warpage of a molded product, and excellent surface appearance.

  Polyacetal resin has a good balance of mechanical strength, chemical resistance and slidability and is easy to process. As typical engineering plastics, mechanical parts of electrical equipment and electrical equipment, mechanical parts of OA equipment It is widely used mainly for automobile parts and other mechanical parts.

  In recent years, the demand for the environment in the indoor and vehicle interiors has increased, and a polyacetal resin that emits less formaldehyde has been desired.

In response to such demands, a method of adding a hydrazide compound to a polyacetal resin has been proposed (see, for example, Patent Documents 1 to 3). However, in these techniques, there are cases where the surface of the molded product is roughened during molding, the size of the molded product is crumpled, and the mold maintenance is complicated. In addition, polyacetal resin generally has a tendency to be crumpled due to warping in the case of a thin molded product.
JP 2005-163019 A JP 2006-306944 A JP 2006-321880 A

  An object of the present invention is to provide a polyacetal resin molded article that has a small amount of formaldehyde released, reduces warping of a molded product, and has an excellent surface appearance.

As a result of intensive studies to achieve the above-mentioned problems, the present inventors have found that 0.01 to 0.5 parts by mass of the hydrazide compound (B) and talc having a specific particle diameter (100 parts by mass) with respect to 100 parts by mass of the polyacetal resin (A). C) A resin obtained by molding a polyacetal resin composition containing 0.001 to 0.03 parts by mass and alkylene glycol (D) 0 to 5 parts by mass at a mold temperature of 60 ° C or higher and a resin temperature of 200 ° C or higher and 220 ° C or lower. The present inventors have found that a molded body can solve the above problems and have completed the present invention. That is, the present invention is as follows.
[1] 0.01 to 0.5 parts by mass of the hydrazide compound (B) and 100 to parts by mass of the polyacetal resin (A), and talc (C) 0.001 to 0.000 having an average particle size of 10 μm to 20 μm. A polyacetal resin molded product obtained by molding a polyacetal resin composition containing 03 parts by mass and alkylene glycol (D) 0 to 5 parts by mass at a mold temperature of 60 ° C. or higher and a resin temperature of 200 ° C. or higher and 220 ° C. or lower;
[2] The polyacetal resin molded article according to the above [1], wherein the polyacetal resin (A) is a polyacetal copolymer;
[3] The polyacetal resin molded article according to the above [1] or [2], wherein the polyacetal resin (A) has a melting point of 167 ° C to 173 ° C.
[4] The polyacetal resin molded product according to any one of [1] to [3], wherein the hydrazide compound (B) is represented by the following general formula:
H ₂ NHNOC-R ⁵ -CONHNH ₂
(Wherein R ⁵ is a hydrocarbon having 2 to 20 carbon atoms);
[5] The above [1] to [4], wherein the hydrazide compound (B) is selected from the group consisting of sebacic acid dihydrazide, adipic acid dihydrazide, dodecanedioic acid dihydrazide, isophthalic acid dihydrazide, and 2,6-naphthalenedicarbodihydrazide. ] The polyacetal resin molded product according to any one of
[6] The polyacetal resin molded article according to any one of [1] to [5], wherein the talc (C) is not surface-treated;
[7] The polyacetal resin molded product according to any one of [1] to [6], wherein the alkylene glycol compound (D) is polyethylene glycol;
[8] The polyacetal resin composition comprises 100 parts by mass of the polyacetal resin (A), an antioxidant, a polymer or compound containing formaldehyde-reactive nitrogen, a formic acid supplement, a weathering (light) stabilizer, a release agent. The polyacetal resin molded article according to any one of the above [1] to [7], which contains 0.01 to 10 parts by mass of at least one (E) selected from the group consisting of an agent and a lubricant; And [9] The polyacetal resin molded body according to any one of the above [1] to [8], wherein an area of a thin portion of 1 mm or less of the polyacetal resin molded body is 2 cm ² or more.

  According to the present invention, it is possible to provide a polyacetal resin molded body that generates less formaldehyde, has less warpage of a molded product, and is excellent in surface appearance.

  Hereinafter, the present invention will be described in detail.

  The present invention relates to 100 parts by mass of polyacetal resin (A), 0.01 to 0.5 parts by mass of hydrazide compound (B), 0.001 to 0.03 parts by mass of talc (C) having predetermined properties, and alkylene glycol (D) The present invention relates to a polyacetal resin molded article obtained by molding a polyacetal resin composition containing 0 to 5 parts by mass at a mold temperature of 60 ° C or higher and a resin temperature of 200 ° C or higher and 220 ° C or lower.

  First, the polyacetal resin (A) will be described.

  The polyacetal resin (A) used in the present invention is a polyoxymethylene homopolymer and a polyoxymethylene copolymer.

  The polyoxymethylene homopolymer has an oxymethylene group in the main chain, and both ends of the polymer are blocked with an ester group or an ether group. A known slurry method using formaldehyde and a known molecular weight regulator as a raw material, a known onium salt polymerization catalyst and a hydrocarbon as a solvent, for example, Japanese Patent Publication No. 47-6420 and Japanese Patent Publication No. 47-10059 The polymerization method can be used.

  The polyoxymethylene copolymer is a polyoxymethylene copolymer obtained by copolymerizing trioxane and cyclic ether and / or cyclic formal. Trioxane is a trimer of formaldehyde, generally obtained by reacting an aqueous formaldehyde solution in the presence of an acidic catalyst, and purified by a method such as distillation. Trioxane, cyclic ether, and cyclic formal need to be highly purified, and the content of impurities that induce hydroxyl groups in the polymer end groups such as water, methanol, formic acid, etc. is 30 mass ppm with respect to the total amount of monomers. Hereinafter, it is preferably 10 mass ppm or less, more preferably 3 mass ppm or less.

  As the polymerization method, conventionally known methods, for example, U.S. Pat. No. 3,027,352, U.S. Pat. No. 3,803,094, DE-C-11141421, DE-C-1495228, DE-C-1720358, DE-C-3018898, It can be carried out by the methods described in JP-A-58-98322 and JP-A-7-70267. Thereafter, the unstable end portion is removed by an extruder having a vent portion which can be melt kneaded to obtain a polyacetal copolymer in which the polymer end portion is stabilized.

  Cyclic ether and / or cyclic formal is ethylene oxide, propylene oxide, butylene oxide, epichlorohydrin, epibromohydrin, styrene oxide, oxetane, 1,3-dioxolane, ethylene glycol formal, propylene glycol formal, diethylene glycol formal, Examples include triethylene glycol formal, 1,4-butanediol formal, 1,5-pentanediol formal, 1,6-hexanediol formal, and among these, ethylene oxide and 1,3-dioxolane are preferred.

  In the present invention, a polyacetal copolymer is more preferable from the viewpoint of reducing the generation of formaldehyde. Moreover, it is preferable that the melting point of a polyacetal resin is high from a viewpoint of reducing curvature, for example, 167 degreeC-173 degreeC are suitable.

  Next, the hydrazide compound (B) used in the present invention will be described.

  The hydrazide compound used in the present invention is not particularly limited, but dicarboxylic acid dihydrazide represented by the following general formula (I) is preferable from the viewpoint of reducing the generation of formaldehyde.

^{_{H 2 NHNOC-R 5 -CONHNH 2}} (I)
(Wherein R ⁵ is a hydrocarbon having 2 to 20 carbon atoms)
Specifically, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, pimelic acid dihydrazide, superic acid dihydrazide, azelaic acid dihydrazide, sebacic acid dihydrazide, dodecanedioic acid dihydrazide, isophthalic acid dihydrazide, Examples include 2,6-naphthalenedicarbodihydrazide. Among these dicarboxylic acid dihydrazides, sebacic acid dihydrazide, adipic acid dihydrazide, dodecanedioic acid dihydrazide, isophthalic acid dihydrazide, and 2,6-naphthalenedicarbodihydrazide are more preferable from the viewpoint of the amount of formaldehyde released. Are adipic acid dihydrazide and sebacic acid dihydrazide. These hydrazide compounds may be used alone or in combination of two or more. The melting point of the hydrazide compound is preferably 160 ° C. or higher, and more preferably 170 ° C. or higher.

  Content of the hydrazide compound (B) in a polyacetal resin composition is 0.01-0.5 mass part with respect to 100 mass parts of polyacetal resin (A), Preferably 0.05-0.5 mass part, More preferably, it is 0.05-0.4 mass part. Within this range, the amount of formaldehyde released is small, and a resin molded article having an excellent surface appearance is obtained.

  Next, talc (C) used in the present invention will be described.

The chemical name of talc (C) is hydrous magnesium silicate, and generally contains about 60% SiO ₂ , about 30% MgO and 4.8% crystal water. The true specific gravity is 2.7 to 2.8, the whiteness is 93% or more according to JIS K-8123, and the PH is 9.0 to 10 according to JIS K-5101. A range is preferable. The 45 μm sieve residue has a value measured according to JIS K-5101 of 0.2% or less, preferably 0.1% or less, more preferably 0.08% or less.

  The average particle size in the resin molded body of talc (C) needs to be 10 μm or more from the viewpoint of improving thermal stability and 20 μm or less from the viewpoint of maintaining tensile elongation. Preferably it is 11-19 micrometers, More preferably, it is 12-18 micrometers.

  As the talc (C) used in the present invention, it is preferable to use a talc (C) that has not been surface-treated, but a surface treatment may be performed using a known surface treatment agent in order to improve the affinity with the resin. Examples of the surface treatment agent include silane coupling agents such as amino silane and epoxy silane, titanate coupling agents, fatty acids (saturated fatty acids and unsaturated fatty acids), alicyclic carboxylic acids, resin acids and metal soaps. Can do. The addition amount of the surface treatment agent is preferably 3% by mass or less, more preferably 2% by mass or less.

  Content of the talc (C) in a polyacetal resin composition is 0.001-0.03 mass part with respect to 100 mass parts of polyacetal resin (A), and 0.001 mass part or more from the point of thermal stability improvement. From the standpoint of maintaining the tensile elongation, it must be 0.03 parts by mass or less. Preferably it is 0.002-0.03 mass part, More preferably, it is 0.005-0.02 mass part.

  Next, the alkylene glycol (D) used in the present invention will be described.

  The alkylene glycol used in the present invention includes homopolymers, copolymers and derivatives of alkylene glycols having 2 to 6 carbon atoms. Specifically, polyalkylene glycols having 2 to 6 carbon atoms such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyoxyethylene-polyoxypropylene random or block copolymers, polyoxyethylene-polyoxypropylene Of glyceryl ether and polyoxyethylene-polyoxypropylene monobutyl ether. Among them, a polymer having an oxyethylene unit, for example, polyethylene glycol, polyoxyethylene-polyoxypropylene copolymer, and derivatives thereof are particularly preferable, and polyethylene glycol is particularly preferable. These alkylene glycols may be used alone or in combination of two or more.

  The content of alkylene glycol (D) in the polyacetal composition is preferably 0 to 5 parts by mass, more preferably 0 to 3 parts by mass, and still more preferably 0 to 0 parts by mass with respect to 100 parts by mass of the polyacetal resin (A). 2 parts by mass. When a small amount of alkylene glycol (D) is added, a resin molded article having an excellent surface appearance can be obtained.

  The resin molded body of the present invention can be made into a resin molded body excellent in thermal stability by blending an appropriate additive depending on the application. Specifically, at least 100 parts by mass of the polyacetal resin (E) an antioxidant, a polymer or compound containing formaldehyde-reactive nitrogen, a formic acid scavenger, a weather resistance (light) stabilizer, and a release (lubricant) agent One type can be contained in an amount of 0.01 to 10 parts by mass.

  As the antioxidant, a hindered phenol antioxidant is preferable. Specifically, for example, n-octadecyl-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) -propionate, n-octadecyl-3- (3′-methyl-5′-t -Butyl-4'-hydroxyphenyl) -propionate, n-tetradecyl-3- (3 ', 5'-di-t-butyl-4'-hydroxyphenyl) -propionate, 1,6-hexanediol-bis- [ 3- (3,5-di-tert-butyl-4-hydroxyphenyl) -propionate], 1,4-butanediol-bis- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) -Propionate], triethylene glycol-bis- [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) -propionate], pentaerythritol tetrakis [methylene- - (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.

  Examples of polymers or compounds 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 Examples thereof include nylon 6 / 6-6 / 6-10 and nylon 6 / 6-12. 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. Specific examples of the N-substituted urea include methylurea, alkylenebisurea, and aryl substituted urea substituted with a substituent such as an alkyl group, etc. Specific examples of the urea condensate include: 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 compound include dicarboxylic acid dihydrazide, and more specifically, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, pimelic acid dihydrazide, superic acid dihydrazide, azelaic acid dihydrazide, Examples include 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 formic 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 (II).
[(M ²⁺ ) _1-X (M ³⁺ ) _X (OH) ₂ ] _X ⁺ [(A ⁿ⁻ ) _{x / n} · mH ₂ O] _X ⁻ (II)
[ ^Wherein M ²⁺ represents a divalent metal, M ³⁺ represents a trivalent metal, An ⁻ represents an n-valent anion (n is an integer of 1 or more), and X is in the range of 0 <X ≦ 0.33. M is a positive number. ]
In formula (II), 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 CO ₃ ²⁻ and OH ⁻ . 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 A synthetic hydrotalcite represented by Al ₂ (OH) _12.6 CO ₃ or the like.

  These formic 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 UV 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 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-tetramethyl). Piperidin-4-yl) amino) -triazin-2-yl) -4,7-diazadecane-1,10-diamine, dibutylamine, 1,3,5-triazine, N, N′-bis (2,2,2) A polycondensate of 6,6, tetramethyl-4-piperidyl-1,6-hexamethylenediamine and N- (2,2,6,6, tetramethyl-4-piperidyl) butylamine, 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-piperidyl) Mino}], a condensate of dimethyl succinate and 4-hydroxy-2,2,6,6, tetramethyl-1-piperidineethanol, bis (2,2,6,6-tetramethyl-1 (octyl) decanoate Oxy) -4-piperidinyl) ester, 1,1-dimethylethyl hydroperoxide and octane reaction product, 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, β ′, β ′,-tetra Examples thereof include condensates with methyl-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 and 1,2,2, Between 6,6-pentamethyl-4-piperidinol and β, β, β ′, β ′,-tetramethyl-3,9- [2,4,8,10-tetraoxaspiro (5,5) undecane] diethanol These hindered amine light stabilizers may be used alone or in combination of two or more.

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

  In the polyacetal resin composition of the present invention, a suitable known additive can be further blended as necessary within a range not impairing the object of the present invention. Specific examples include inorganic fillers, crystal nucleating agents, conductive materials, thermoplastic resins, thermoplastic elastomers, and pigments.

  As the inorganic filler, fibrous, powdery, plate-like and hollow fillers are used. Fiber fillers include glass fiber, carbon fiber, silicone fiber, silica / alumina fiber, zirconia fiber, boron nitride fiber, silicon nitride fiber, boron fiber, potassium titanate fiber, and stainless steel, aluminum, titanium, copper, brass. And inorganic fibers such as metal fibers. In addition, whiskers such as potassium titanate whisker and zinc oxide whisker having a short fiber length are included. A high melting point organic fibrous material such as an aromatic polyamide resin, a fluororesin, or an acrylic resin can also be used.

  Examples of powder particulate fillers include carbon black, silica, quartz powder, glass beads, glass powder, calcium silicate, aluminum silicate, kaolin, clay, diatomaceous earth, wollastonite, iron oxide, titanium oxide, and alumina. Examples thereof include metal oxides such as these, metal sulfates such as calcium sulfate and barium sulfate, carbonates such as magnesium carbonate and dolomite, silicon carbide, silicon nitride, boron nitride, and various metal powders.

  Examples of the plate-like filler include mica, glass flakes, and various metal foils. Examples of the hollow filler include glass balloons, silica balloons, shirasu balloons, and metal balloons. These fillers can be used alone or in combination of two or more. These fillers can be used either surface-treated or unsurface-treated, but in some cases it is preferable to use a surface-treated one in terms of smoothness of the molding surface and mechanical properties. is there. A conventionally well-known thing can be used as a surface treating agent. For example, various coupling treatment agents such as silane, titanate, aluminum, and zirconium can be used. Specifically, N- (2-aminoethyl) -3-aminopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, isopropyl trisstearoyl titanate, diisopropoxyammonium ethyl acetate, n-butyl zirconate, etc. Can be mentioned.

  Examples of the conductive agent include conductive carbon black, metal powder, or fiber.

  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. Since the addition ratio of the pigment varies greatly depending on the color tone, it is difficult to clarify, but generally it is used in the range of 0.05 to 5 parts by mass with respect to 100 parts by mass of the polyacetal resin.

The polyacetal resin composition of the present invention can be produced using a general extruder using the components described above. Examples of the extruder include a single-screw or multi-screw kneading extruder, and among them, a twin-screw extruder provided with a decompression device is preferable. As a method for producing the polyacetal resin composition,
<1> A method in which the polyacetal resin (A) is fed from the top of the extruder, and the hydrazide compound (B), talc (C) and alkylene glycol (D) are added from a side feed port by a quantitative feeder or the like and melt-kneaded;
<2> A part of the polyacetal resin (A) is fed from the top of the extruder, and the hydrazide compound (B), talc (C), alkylene glycol (D) and the remaining polyacetal resin (A) are side-fed with a quantitative feeder or the like. A method of adding from the mouth and melt-kneading;
<3> Polyacetal resin (A), hydrazide compound (B), talc (C) and alkylene glycol (D) are mixed together using a Henschel mixer, tumbler, V-shaped blender, etc., and then melt kneaded using an extruder. And the like.

  <1>, <2> Add hydrazide compound (B) and talc (C) to the melted state of polyacetal resin (A) from the viewpoint of thermal stability of the obtained polyacetal resin composition and reduction of formaldehyde emission. The production method is preferred. Further, when the component (E) is added, it may be fed simultaneously with the polyacetal resin (A) from the top of the extruder, or may be fed simultaneously with the hydrazide compound (B) and talc (C) from the side feed port.

  The resin molded body of the present invention is a known molding method of the polyacetal resin composition, for example, extrusion molding, injection molding, vacuum molding, blow molding, injection compression molding, decorative molding, other material molding, gas assist injection molding, It can be obtained by molding by firing injection molding, low pressure molding, ultra thin injection molding (ultra high speed injection molding), in-mold composite molding (insert molding, outsert molding) or the like.

  In the present invention, the resin temperature during molding needs to be 200 ° C. or higher and 220 ° C. or lower. By setting it within this range, a resin molded body having an excellent surface appearance is obtained. Preferably it is 205 to 210 degreeC.

  Moreover, the mold temperature at the time of shaping | molding needs to be 60 degreeC or more. Preferably it is 70 degreeC or more, More preferably, it is 80 degreeC or more. When the mold temperature is lowered, the gasified component tends to be mold deposit, but if it is 60 ° C. or higher, the mold deposit is difficult to adhere. Most preferably, it is 80 to 100 ° C.

The effect of the present invention is more prominent when the area of the thin portion of the resin molded body is larger, and is remarkable when the area of the thin portion of 1 mm or less of the resin molded body is 2 cm ² or more.

  In the present invention, the polyacetal resin (A), hydrazide compound (B), talc (C), and alkylene glycol (D) are defined by the content in the polyacetal resin composition. Even in the body, the content is substantially equal. That is, the polyacetal resin molding according to the present invention is a talc having a hydrazide compound (B) of 0.01 to 0.5 parts by mass and an average particle size of 10 μm to 20 μm with respect to 100 parts by mass of the polyacetal resin (A). (C) 0.001-0.03 mass part and alkylene glycol (D) 0-5 mass part are included.

  The content of these components in the polyacetal resin molded body can be measured by those skilled in the art using a known method and various similar methods. For example, the content of the hydrazide compound in the polyacetal resin molded body The content can be measured by dissolving the molded article in hexafluoroisopropanol (HFIP), adding methanol to the solution to precipitate the polymer component, and quantifying the soluble content by gas chromatography.

  Moreover, the average particle diameter of the talc in the polyacetal resin molding can be measured by a microscopic method. Specifically, the resin molded body of the present invention was prepared by, for example, creating a thin film with a press machine or the like that can be heated to a melting point of polyacetal or higher, observing and photographing a particle image using a polarizing microscope, and selecting at random. The average particle size can be determined by measuring the maximum particle size and the number of at least 100 talcs. Further, in order to quantify the talc content in the molded article of polyacetal resin of the present invention, it is caused by talc by hydrolyzing with hydrochloric acid or the like to quantify talc or by high frequency inductively coupled plasma (ICP) emission analysis. A method for quantifying metallic components (Si, Mg) can be mentioned.

  In addition, for example, in the case of polyethylene glycol, the content of alkylene glycol in the polyacetal resin molded body is Soxhlet extracted from the molded product with chloroform solvent, filtered the extract, and then evaporated to dryness and vacuum dried. To do. After being dissolved in deuterated chloroform containing DMSO as an internal standard, it can be measured and quantified by H-NMR.

  The resin molded body of the present invention has excellent thermal stability, less formaldehyde generation, excellent mold deposit resistance, little warpage, and excellent surface appearance, so it can be used for molded products for various applications. Is possible. For example, gears, cams, sliders, levers, arms, clutches, felt clutches, idler gears, pulleys, rollers, rollers, key stems, key tops, shutters, reels, shafts, joints, shafts, bearings, guides, etc. Mechanical parts, resin parts for outsert molding, resin parts for insert molding, chassis, trays, side plates, parts for office automation equipment such as printers and copiers, VTRs, video movies, digital video cameras, cameras, and digital cameras Or video equipment parts, cassette player, DAT, LD (Laser Disk), MD (Mini Disk), CD [CD-ROM (Read Only Memory), CD-R (Recordable), CD-RW (Including Rewritable)], DVD (including DVD-ROM, DVD-R, DVD + R, DVD-RW, DVD + RW, DVD-R DL, DVD + R DL, DVD-RAM (including Random Access Memory), DVD-Audio), Blu- Ray Disc, HD-DVD, other optical disk drives, MFD, MO, navigation systems and music, video or information equipment represented by mobile personal computers, parts for communication equipment represented by mobile phones and facsimiles, parts for electrical equipment , Fuel tank parts such as gasoline tanks, fuel pump modules, valves, gasoline tank flanges, door locks, door handles, window regulators, speakers, etc. Door parts represented by grills, seat belt slip rings, seat belt peripheral parts represented by press buttons, combination switch parts, switches and clip parts, mechanical pencil nib and sharp Mechanical parts for putting in and out the pencil core, wash basin, drain outlet, drain valve opening / closing mechanism parts, vending machine opening / closing part locking mechanism, product discharge mechanism parts, clothing cord stopper, adjuster, button, watering Nozzles and sprinkling hose connection joints, stair handrails and building materials that support floor materials, disposable cameras, toys, fasteners, chains, conveyors, buckles, sports equipment, vending machines, furniture, musical instruments, It can be suitably used as an industrial part typified by residential equipment.

Hereinafter, the present invention will be described based on examples.
(1) Melting point measurement method of polyacetal resin Using a differential calorimeter (DSC-7, manufactured by Perkin Elmer), the sample once heated to 200 ° C. and cooled was cooled to 100 ° C. and again 2.5 ° C./min. The temperature of the peak of the exothermic spectrum generated in the process of raising the temperature at a rate of was defined as the melting point.
(2) Method for measuring amount of formaldehyde released from molded product Using IS-80A injection molding machine manufactured by Toshiba Corporation, cylinder temperature: 205 ° C., injection pressure: (primary pressure / secondary pressure = 63.7 MPa / 50.0 MPa) Injection time: 15 seconds, cooling time: 20 seconds, mold temperature: 77 ° C., a test piece (90 × 50 × 3 mm flat plate) was prepared, measured with a new Cosmos Electric Holtector, and from the molded product The amount of formaldehyde released was determined.

<Method for measuring Holtector>
The operation of putting the molded product in a 10 L Tedlar bag, injecting Air, and then removing Air with a decompression device is repeated twice. Fill the Tedlar bag with Air 7L, close the cock and heat at 80 ° C. for 1 hour. Thereafter, a formecter was connected to the cock of the Tedlar bag and measurement was performed to determine the amount of formaldehyde released (mg / m ³ ).
(3) Measuring method of resin temperature Using a CN-75 molding machine manufactured by Niigata Tekko, the temperature of the purge resin was measured for the third time when it was weighed to 50% of the measured value and purged three times. It was confirmed that the resin temperature was 210 ° C when the cylinder setting temperature of the molding machine was 205 ° C, the resin temperature was 220 ° C when the setting temperature was 215 ° C, and 190 ° C when the cylinder setting temperature was 185 ° C.
(4) Method for measuring mold deposit characteristics Using a CN-75 molding machine manufactured by Niigata Tekko, at a cylinder set temperature of 185 ° C., 205 ° C., 215 ° C., and a mold temperature of 80 ° C., a mold deposit mold (pentagonal short side 15 mm) , Long side 25 mm, thickness 2 mm), and the state of the mold deposit after 3000 shot molding was observed.
Evaluation method ○ There is no mold deposit.
△ Some mold deposits are attached.
X The mold deposit is clearly attached.
(5) surface roughness measurement methods (4) and the surface roughness R _max of the flow-terminal part of 3000 th of the molded article in the measuring method of mold deposit characteristic measured by Tokyo Seimitsu Co. Surfcom.
(6) Method for measuring warpage Using a CN-75 molding machine manufactured by Niigata Tekko Co., Ltd. at a cylinder set temperature of 185 ° C., 205 ° C., 215 ° C., and a mold temperature of 80 ° C. (regular square 60 mm on each side, thickness 1 mm, Film gate) was molded, and after adjusting the state for 24 hours in a constant temperature and humidity chamber of 23 ° C. × 50% Rh, the gate side was fixed and the amount of warpage was measured.
(7) Measuring method of tensile elongation ISO dumbbell test pieces were molded at a cylinder set temperature of 185 ° C., 205 ° C., 215 ° C., and a mold temperature of 80 ° C. using a SH100C molding machine manufactured by Sumitomo Heavy Industries. The tensile elongation was measured according to ISO 527-1 & 2 (93).
(8) Measuring method of talc average particle diameter A part of the resin molded body used for measurement of mold deposit characteristics was cut out, a thin film was created with a press machine set at 200 ° C., and a polarizing microscope (Nikon ECLIPSE E600WPOL) was used. The particle image is observed and photographed at a magnification of 400 times, the maximum particle diameter (maximum major axis) of 100 randomly selected talcs is measured one by one, and the average value of the 100 maximum particle diameters is measured. Was defined as the average particle size.
(9) Method of measuring talc content 200 batches of a resin molded body used in the measurement of mold deposit characteristics were mixed with 300 ml of 0.1N hydrochloric acid aqueous solution and charged in a glass pressure bottle, and 10 batches were prepared. After these were decomposed under pressure in a sterilizer at 130 ° C. for 6 to 10 hours, talc in the decomposition solution for 10 batches was filtered, and the filter residue was further washed and filtered with chloroform, etc. Additives other than were removed. The remaining talc was dried under reduced pressure and then weighed to obtain the talc content in the resin composition.

The following components were used in Examples and Comparative Examples.
<Polyacetal resin a-1>
A biaxial self-cleaning type polymerization machine (L / D = 8) with a jacket capable of passing a heat medium is adjusted to 80 ° C., 4 kg / hr of trioxane, 42.8 g / liter of 1,3-dioxolane as a comonomer h (1.3 mol% with respect to 1 mol of trioxane), methylal as a chain transfer agent was continuously added at 0.1 × 10 ⁻³ mol with respect to 1 mol of trioxane. Further, boron trifluoride di-n-butyl ether was continuously added as a polymerization catalyst at 1.5 × 10 ⁻⁵ mol with respect to 1 mol of trioxane to carry out polymerization. The polyacetal copolymer discharged from the polymerization machine was put into a 0.1% aqueous solution of triethylamine to deactivate the polymerization catalyst. An aqueous solution containing choline formate (triethyl-2-hydroxyethylammonium formate) as a quaternary ammonium compound with respect to 100 parts by mass of the polyacetal copolymer after filtering the deactivated polyacetal copolymer. 1 part by mass was added and mixed uniformly and then dried at 120 ° C. The addition amount of the hydroxycholine formate was adjusted by adjusting the concentration of the hydroxycholine formate in the aqueous solution containing the added choline formate, and was 20 mass ppm in terms of the amount of nitrogen. The dried polyacetal copolymer is supplied to a vented twin screw extruder, and 0.5 parts by mass of water is added to 100 parts by mass of the melted polyacetal copolymer in the extruder, and the extruder set temperature is 200 ° C. The unstable terminal portion was decomposed and removed in a residence time of 7 minutes in the extruder. The polyacetal copolymer whose unstable terminal portion was decomposed was devolatilized under a condition of a vent vacuum of 20 Torr, extruded as a strand from the extruder die, and pelletized. The melting point of the polyacetal resin (A) thus obtained was 169.5 ° C.
<Polyacetal resin a-2>
When polymerizing the polyacetal resin, the same as the production of the polyacetal resin (a-1) except that the continuous addition amount of 1,3-dioxolane was 128.3 g / h (3.9 mol% with respect to 1 mol of trioxane). Operation was performed to obtain a polyacetal resin (a-2). The polyacetal resin (a-2) thus obtained had a melting point of 164.5.
<Hydrazide compound (B)>
b-1: Adipic acid dihydrazide (Nippon Finechem Co., Ltd.)
b-2: Sebacic acid dihydrazide (Nihon Finechem Co., Ltd.)
<Talc (C)>
c-1: MS manufactured by Nippon Talc Co., Ltd. (untreated surface) Average particle diameter of 15.6 μm
c-2: (c-1) MS manufactured by Nippon Talc Co., Ltd. surface-treated with 1% aminopropyltriethoxysilane c-3: P-3 manufactured by Nihon Talc Co., Ltd. (untreated surface) Average particle size 1μm
c-4: MS-KY (Non-surface treated) manufactured by Nippon Talc Co., Ltd. Average particle size 24.5 μm
<Alkylene glycol (D)>
d-1: Polyethylene glycol [Example 1]
To 100 parts by mass of the polyacetal resin (a-1), 0.3 parts by mass of triethylene glycol-bis- [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) -propionate] as an antioxidant and As a formic acid scavenger, 0.15 parts by mass of calcium distearate, 0.1 part by mass of hydrazide compound (b-1) and 0.005 parts by mass of talc (c-1) were added, and a 30-φ vented single screw extruder Was melt kneaded. The obtained polyacetal resin composition was molded into a plate-shaped product at a resin temperature of 210 ° C. (cylinder setting temperature of 205 ° C.) and a mold temperature of 80 ° C. using an injection molding machine, and formaldehyde emission and warpage were evaluated. Moreover, 3000 shot molding was performed, the surface appearance of the 3000th shot was evaluated, and the mold deposit amount adhering to the mold was observed. Furthermore, the tensile elongation was measured by ISO 527-1 & 2 (93), and the results are shown in Table 1.
[Examples 2 and 3]
Except for the amount of talc (c-1) added, the same operations as in Example 1 were performed for evaluation. The results are shown in Table 1.
[Example 4]
The same operations as in Example 1 were carried out for evaluation except that talc (c-1) was changed to (c-2). The results are shown in Table 1.
[Example 5]
Except for the amount of talc (c-2) added, the same operations as in Example 4 were performed for evaluation. The results are shown in Table 1.
[Examples 6 and 7]
The same operations as in Example 1 were performed except for the addition amount of the hydrazide compound (b-1). The results are shown in Table 1.
[Example 8]
Evaluation was performed by performing the same operations as in Example 2 except that the hydrazide compound (b-1) was changed to (b-2). The results are shown in Table 1.
[Example 9]
Evaluation was performed by performing the same operations as in Example 1 except that the resin temperature during molding was 220 ° C. (cylinder setting temperature 215 ° C.). The results are shown in Table 1.
[Example 10]
The same operations as in Example 1 were carried out for evaluation except that the polyacetal resin (a-1) was changed to a polyacetal resin (a-2). The results are shown in Table 1.
[Example 11]
Evaluation was performed by performing the same operations as in Example 10 except that the hydrazide compound (b-1) was changed to (b-2). The results are shown in Table 1.
[Example 12]
The same operations as in Example 2 were carried out for evaluation except that polyethylene glycol (d-1) was added. The results are shown in Table 1.
[Example 13]
Except for the addition amount of polyethylene glycol (d-1), the same operations as in Example 12 were performed for evaluation. The results are shown in Table 1.
[Comparative Example 1]
Evaluation was performed by performing the same operations as in Example 1 except that the hydrazide compound (b-1) and talc (c-1) were not added. The results are shown in Table 2.
[Comparative Example 2]
Evaluation was performed by performing the same operations as in Example 1 except that talc (c-1) was not added. The results are shown in Table 2.
[Comparative Example 3]
Evaluation was performed by performing the same operations as in Example 1 except that the resin temperature at the time of molding was 190 ° C. (cylinder setting temperature 185 ° C.). The results are shown in Table 2.
[Comparative Example 4]
Evaluation was performed by performing the same operations as in Example 2 except that talc (c-1) was changed to (c-3). The results are shown in Table 2.
[Comparative Example 5]
Except for the amount of talc (c-1) added, the same operations as in Example 1 were performed for evaluation. The results are shown in Table 2.
[Comparative Example 6]
Evaluation was performed by performing the same operations as in Example 2 except that talc (c-1) was changed to (c-4). The results are shown in Table 2.
[Comparative Example 7]
Except for the addition amount of polyethylene glycol (d-1), the same operations as in Example 12 were performed for evaluation. The results are shown in Table 2.
[Comparative Example 8]
Evaluation was performed by performing the same operations as in Example 1 except that the mold temperature during molding was 50 ° C. The results are shown in Table 2.

  The polyacetal resin molded product of the present invention has a small amount of formaldehyde emission and warpage, and also has excellent surface appearance, so that it is required for automotive applications where reduction of formaldehyde emission amount is required, and electrical and electronic applications where high accuracy and good appearance are required. Etc. can be suitably used.

Claims (9)

  0.001-0.03 parts by mass of talc (C) having an average particle size of 10 to 20 μm with respect to 100 parts by mass of the polyacetal resin (A). And a polyacetal resin molded product obtained by molding a polyacetal resin composition containing 0 to 5 parts by mass of alkylene glycol (D) at a mold temperature of 60 ° C. or higher and a resin temperature of 200 ° C. or higher and 220 ° C. or lower.   The polyacetal resin molding of Claim 1 whose polyacetal resin (A) is a polyacetal copolymer.   The polyacetal resin molding according to claim 1 or 2, wherein the polyacetal resin (A) has a melting point of 167 ° C to 173 ° C. The polyacetal resin molded product according to any one of claims 1 to 3, wherein the hydrazide compound (B) is represented by the following general formula.
H ₂ NHNOC-R ⁵ -CONHNH ₂
(Wherein R ⁵ is a hydrocarbon having 2 to 20 carbon atoms)   The hydrazide compound (B) is selected from the group consisting of sebacic acid dihydrazide, adipic acid dihydrazide, dodecanedioic acid dihydrazide, isophthalic acid dihydrazide, and 2,6-naphthalenedicarbodihydrazide. The polyacetal resin molding as described in 2.   The polyacetal resin molded product according to any one of claims 1 to 5, wherein the talc (C) is not surface-treated.   The polyacetal resin molding as described in any one of Claims 1-6 whose alkylene glycol compound (D) is polyethyleneglycol.   The polyacetal resin composition is an antioxidant, a polymer or compound containing formaldehyde-reactive nitrogen, a formic acid scavenger, a weathering (light) stabilizer, a release agent, and 100 parts by mass of the polyacetal resin (A). The polyacetal resin molding as described in any one of Claims 1-7 which contains 0.01-10 mass parts of at least 1 sort (E) selected from the group which consists of a lubricant. The polyacetal resin molded product according to any one of claims 1 to 8, wherein an area of a thin portion of 1 mm or less of the polyacetal resin molded product is 2 cm ² or more.