JP6151579B2 - Polyacetal resin composition - Google Patents

Description

  The present invention relates to a polyacetal resin composition.

  The polyacetal resin is a crystalline resin, and is a resin material excellent in rigidity, strength, toughness, slidability, and creep properties. Polyacetal resins are used over a wide range of materials for mechanical parts such as automobile parts, electric / electronic parts and industrial parts. However, deterioration of the polyacetal resin may be accelerated depending on the use environment. Furthermore, polyacetal resin is currently required to have higher performance as the application field expands.

  As such required properties, the high performance inherent in polyacetal resin, for example, improving the thermal stability and creep properties in harsh usage environments while having the excellent mechanical property balance as described above. May also be required. In recent years, with the increase in density of electric and electronic devices, polyacetal resins are increasingly used in a temperature range of 100 ° C. or more, and it is important to have a balance between thermal stability and high temperature creep characteristics. It has become to.

  In addition, polyacetal resin is poor in thermal stability, and formaldehyde gas is generated by thermal decomposition during molding processing, which deteriorates the working environment, and further, additives such as stabilizers contained in the generated formaldehyde and polyacetal resin Volatile components derived from the metal deposit on the mold surface to form a so-called mold deposit. As a result, the surface of the molded product is remarkably damaged, or the dimensional accuracy of the molded product is lowered. In addition, when mold deposits occur, the mold must be disassembled and cleaned each time the mold deposits are generated, which requires a lot of time and labor, resulting in a decrease in productivity. Have. Therefore, a method for solving such a problem is strongly desired.

  In order to solve the above problem, various proposals have been made so far. For example, for the purpose of reducing formaldehyde generated by thermal decomposition, a method of adding a polyamide to a polyacetal resin (for example, see Patent Document 1), a method of adding an amide oligomer or the like to a polyacetal resin (for example, see Patent Document 2), Alternatively, a method of adding a hindered phenol / carboxylic acid metal salt / polyamide to a polyacetal resin (see, for example, Patent Document 3) has been proposed.

  Moreover, the polyacetal resin composition which added the talc (for example, refer patent document 4) is disclosed from a viewpoint of improving a high temperature creep characteristic and a mechanical physical property.

Japanese Patent Publication No.34-5440 Japanese Patent Publication No.54-32658 Japanese Patent Laid-Open No. 3-14859 JP 2008-156628 A

  However, in the methods described in Patent Documents 1 to 3, since the obtained polyacetal resin composition is insufficiently stabilized, it can be satisfied in terms of thermal stability during molding processing and prevention of mold deposits. It is not a thing.

  In addition, in the method of adding talc as in Patent Document 4, the obtained polyacetal resin composition is highly effective in improving mechanical properties and creep resistance, but is resistant to changes in color tone due to aging and mold deposit resistance (hereinafter referred to as “amount deposit resistance”). Also referred to as “MD”.) Properties have not been studied.

  Therefore, the present invention has been made in view of the above-described problems of the prior art, and can prevent adhesion to a mold (mold deposit) during injection molding, and thermal stability (mechanical properties after thermal aging). Another object of the present invention is to provide a polyacetal resin composition having high creep characteristics and excellent weather resistance (color change due to aging).

  As a result of intensive studies to solve the above problems, the present inventors have obtained (A) 100 parts by mass of a polyacetal resin, and (B) 0.001 to 5 parts by mass of a chlorite group mineral as a specific inorganic filler. (C) It discovered that the polyacetal resin composition containing 0.1-5 mass parts of weathering stabilizers could solve the said subject, and came to complete this invention.

That is, the present invention is as follows.
[1]
A polyacetal resin composition containing (A) 100 parts by mass of a polyacetal resin, (B) 0.001 to 5 parts by mass of a chlorite group mineral, and (C) 0.1 to 5 parts by mass of a weather resistance stabilizer.
[2]
The polyacetal resin composition according to [1], wherein the content of the chlorite group mineral (B) is 0.001 to 1 part by mass.
[3]
The polyacetal resin composition according to [1] or [2] above, wherein the chlorite group mineral (B) is at least one selected from the group consisting of chlorite, cookite, and nanthite.
[4]
The polyacetal resin composition according to any one of [1] to [3], wherein the chlorite group mineral (B) has an average particle size of 0.01 to 100 μm.

  According to the present invention, adhesion (MD) to a mold during injection molding can be reliably prevented, thermal stability (mechanical properties after thermal aging), high creep characteristics, and weather resistance (due to aging). It is possible to provide a polyacetal resin composition excellent in (color tone change).

  Hereinafter, a mode for carrying out the present invention (hereinafter referred to as “the present embodiment”) will be described in detail. In addition, this invention is not limited to the following embodiment, It can implement by changing variously within the range of the summary.

[Polyacetal resin composition]
The polyacetal resin composition of the present embodiment includes (A) 100 parts by mass of a polyacetal resin, (B) 0.001 to 5 parts by mass of a chlorite group mineral, and (C) 0.1 to 5 parts by mass of a weather resistance stabilizer. Is a polyacetal resin composition.

<(A) polyacetal resin>
The (A) polyacetal resin used in the present embodiment is not particularly limited. Specifically, a formaldehyde monomer or a cyclic oligomer of formaldehyde such as a trimer (trioxane) or a tetramer (tetraoxane) is used. Polyacetal homopolymer consisting essentially of oxymethylene units obtained by homopolymerization; formaldehyde monomer, cyclic oligomer of formaldehyde such as trimer (trioxane) or tetramer (tetraoxane), ethylene oxide, propylene Polyacetal copolymer obtained by copolymerization with glycol such as oxide, epichlorohydrin, 1,3-dioxolane, 1,4-butanediol formal, cyclic ether such as cyclic formal of diglycol, or cyclic formal; It can be mentioned polyacetal copolymer or the like having a multifunctional glycidyl ether is copolymerized to obtain crosslinked structure; polyacetal copolymer having a branched obtained by copolymerizing ether.

  Furthermore, the polyacetal resin (A) is not particularly limited, and specifically, a compound having a functional group such as a hydroxyl group at both ends or one end, for example, a polyalkylene glycol in the presence of a formaldehyde monomer or formaldehyde. Polyacetal homopolymer having a block component obtained by polymerizing a cyclic oligomer; a formaldehyde monomer or trimer thereof in the presence of a compound having functional groups such as hydroxyl groups at both ends or one end, for example, hydrogenated polybutadiene glycol Mention may also be made of polyacetal copolymers having a block component obtained by copolymerizing formaldehyde cyclic oligomers such as (trioxane) or tetramer (tetraoxane) with cyclic ethers or cyclic formals. As described above, in the present embodiment, both a polyacetal homopolymer and a polyacetal copolymer can be used. Among these, a polyacetal copolymer is preferable.

  In addition, in the illustration of the above-mentioned (A) polyacetal resin, the proportion of the comonomer such as 1,3-dioxolane is preferably 0.1 to 60 mol%, preferably 0.1 to 20 mol% with respect to 1 mol of trioxane. Is more preferable, and it is still more preferable that it is 0.13-10 mol%. If the ratio of a comonomer is the said range, the polyacetal resin composition which was more excellent in mechanical strength can be provided.

  Further, the polymerization catalyst in the polymerization of the exemplified polyacetal copolymer is not particularly limited, but specifically, a cationically active catalyst such as Lewis acid, proton acid and ester or anhydride thereof is preferable. Examples of the Lewis acid include, but are not limited to, boric acid, tin, titanium, phosphorus, arsenic, and antimony halides. Specifically, boron trifluoride, tin tetrachloride, titanium tetrachloride, and pentafluoride. And phosphorus complex, phosphorus pentachloride, antimony pentafluoride and complex compounds or salts thereof. Further, the protonic acid and its ester or anhydride are not particularly limited, and specifically, perchloric acid, trifluoromethanesulfonic acid, perchloric acid-tertiary butyl ester, acetyl perchlorate, trimethyloxonium hexafluorophosphate Etc. Among these, boron trifluoride; boron trifluoride hydrate; and a coordination complex compound of an organic compound containing an oxygen atom or a sulfur atom and boron trifluoride are preferable. Specifically, boron trifluoride diethyl Preferred examples include ether and boron trifluoride di-n-butyl ether.

  The method for polymerizing the polyacetal copolymer exemplified above is not particularly limited, but specifically, for example, it is carried out by bulk polymerization and can be either batch type or continuous type. Although it does not specifically limit as a polymerization apparatus used, For example, self-cleaning type extrusion kneaders, such as a kneader, a twin screw type continuous extrusion kneader, and a biaxial paddle type continuous mixer, are mentioned. Molten monomer is supplied to the polymerization machine, and solid agglomerated polyacetal copolymer is obtained as the polymerization proceeds.

In the polyacetal copolymer obtained by the above polymerization, there may be a thermally unstable terminal portion [-(OCH ₂ ) _n —OH group]. It is preferable to implement.

<(B) Chlorite group mineral>
The polyacetal resin composition of this embodiment contains (B) chlorite group mineral. Chlorite group mineral (B) is one of silicate minerals and has a layered structure. More specifically, the chlorite group mineral (B) is an oxide made of Mg, Fe, Mn or Ni, an oxide made of Al, Fe, Cr or Ti, or an oxide made of Si or Al. It is a mineral containing a predetermined oxide selected from. The crystal structure of the chlorite group mineral (B) includes a monoclinic system and an orthorhombic system. An example of the chemical formula of the chlorite group mineral (B) is (Mg, Fe, Al) ₆ (Si, Al) ₄ O ₁₀ (OH) ₈ , and among these, Mg ₃ (SiO ₅ ) ₂ (OH ) ₂ · 3Mg (OH) ₂ is preferred.

  The production method for pulverizing the chlorite group mineral (B) from the raw stone is not particularly limited. Specifically, for example, an axial flow mill method, an annular mill method, a roll mill method, a ball mill method, a jet mill method, In addition, a container rotation type compression shearing mill method or the like can be used. Further, the chlorite group mineral (B) after pulverization is classified by various classifiers, and the chlorite group mineral (B) having a uniform particle size distribution is preferable. The classifier is not particularly limited. Specifically, for example, an impactor type inertial force classifier (variable impactor, etc.), a Coanda effect type inertia classifier (elbow jet, etc.), and a centrifugal field classifier (multistage). Cyclone, microplex, dispersion separator, Accucut, turbo classifier, turboplex, micron separator, and super separator).

  The average particle size of the chlorite group mineral (B) is preferably 0.01 to 100 μm, more preferably 0.05 to 80 μm, and still more preferably 0.1 to 50 μm. From the viewpoint of imparting sufficient heat resistance and rigidity to the polyacetal resin composition, the average particle size of the chlorite group mineral (B) is preferably 0.01 μm or more, and sufficient dispersibility of the chlorite group mineral (B) is imparted. From this viewpoint, the average particle size of the chlorite group mineral (B) is preferably 100 μm or less. Here, the average particle diameter refers to the center particle diameter D50% of the particle size distribution obtained by measurement by a laser light diffraction measurement method (manufactured by Shimadzu Corporation: SALD-3100).

  The polyacetal resin composition of the present embodiment can effectively improve thermal stability and maintain mechanical properties by including (A) polyacetal resin and (B) chlorite group mineral. Become.

  In the polyacetal resin composition of the present embodiment, the (B) chlorite group mineral is contained in an amount of 0.001 to 5 parts by mass with respect to 100 parts by mass of the (A) polyacetal resin described above, and 0.001 to 1 mass. It is preferably contained in an amount of 0.001 to 0.5 parts by mass. (B) If content of chlorite group mineral is such a range, the polyacetal resin composition which was more excellent in thermal stability can be provided.

Especially, it is preferable that (B) chlorite group mineral is at least 1 sort (s) selected from the group which consists of a chlorite, a cookite, and a nanthite. These may be used alone or in combination of two or more. In particular, chlorite is preferable from the viewpoint of availability. As chlorite, chlorite represented by the chemical formula 5MgO.Al ₂ O ₃ .3SiO ₂ .4H ₂ O is preferable.

<(C) Weathering stabilizer>
The polyacetal resin composition of the present embodiment contains (C) a weather resistance stabilizer.

  The weathering stabilizer (C) used in this embodiment is preferably at least one selected from the group consisting of benzotriazole compounds, oxalic acid anilide compounds, and hindered amine light stabilizers.

  Although it does not specifically limit as a benzotriazole type compound, For example, 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] benzotriazole, 2- (2′-hydroxy-3,5-di-t-amylphenyl] Benzotriazole, 2- (2′-hydroxy-3,5-di-isoamyl-phenyl) benzotriazole, 2- [2′-hydroxy-3,5-bis- (α, α-dimethylbenzyl) phenyl] -2H -Benzotriazole, 2- (2'-hydroxy-4'-octoxyphenyl) benzotriazole, etc. These compounds include It Re may be used singly or may be used in combination of two or more.

  Although it does not specifically limit as an oxalic acid alinide type compound, For example, 2-ethoxy-2'-ethyl oxalic acid bisanilide, 2-ethoxy-5-t-butyl-2'-ethyl oxalic acid bisanilide, 2-Ethoxy-3′-dodecyl oxalic acid bisanilide and the like. These compounds may be used alone or in combination of two or more.

  Examples of hindered amine light stabilizers include 4-acetoxy-2,2,6,6-tetramethylpiperidine, 4-stearoyloxy-2,2,6,6-tetramethylpiperidine, 4-acryloyloxy-2, 2,6,6-tetramethylpiperidine, 4- (phenylatoxy) -2,2,6,6-tetramethylpiperidine, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, 4-methoxy -2,2,6,6-tetramethylpiperidine, 4-stearyloxy-2,2,6,6-tetramethylpiperidine, 4-cyclohexyloxy-2,2,6,6-tetramethylpiperidine, 4-benzyl Oxy-2,2,6,6-tetramethylpiperidine, 4-phenoxy-2,2,6,6-tetramethylpiperidine, 4- (ethylcalp Moyloxy) -2,2,6,6-tetramethylpiperidine, 4- (cyclohexylcarbamoyloxy) -2,2,6,6-tetramethylpiperidine, 4- (phenylcarbamoyloxy) -2,2,6,6 -Tetramethylpiperidine, bis (2,2,6,6-tetramethyl-4-piperidyl) -carbonate, bis (2,2,6,6-tetramethyl-4-piperidyl) -oxalate, bis (2,2 , 6,6-tetramethyl-4-piperidyl) -malonate, bis (1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, bis- (N-methyl-2,2,6,6-) Tetramethyl-4-piperidinyl) sebacate, bis (2,2,6,6-tetramethyl-4-piperidyl) -sebacate, bis (2,2,6,6-tetramethyl) -4-piperidyl) -adipate, bis (2,2,6,6-tetramethyl-4-piperidyl) -terephthalate, 1,2-bis (2,2,6,6-tetramethyl-4-piperidyloxy) -Ethane, α, α'-bis (2,2,6,6-tetramethyl-4-piperidyloxy) -p-xylene, bis (2,2,6,6-tetramethyl-4-piperidyltolylene- 2,4-dicarbamate, bis (2,2,6,6-tetramethyl-4-piperidyl) -hexamethylene-1,6-dicarbamate, tris (2,2,6,6-tetramethyl-4- Piperidyl) -benzene-1,3,5-tricarboxylate, tris (2,2,6,6-tetramethyl-4-piperidyl) -benzene-1,3,4-tricarboxylate, 1- [2- {3- (3,5- -T-butyl-4-hydroxyphenyl) propionyloxy} butyl] -4- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy] 2,2,6,6-tetramethyl Piperidine, 1,2,3,4-butanetetracarboxylic acid and 1,2,2,6,6-pentamethyl-4-piperidinol and β, β, β ′, β ′,-tetramethyl-3,9- [ 2,4,8,10-tetraoxaspiro (5,5) undecane] condensate with diethanol, and the like. The hindered amine light stabilizers may be used alone or in combination of two or more.

  Among them, preferable weather stabilizer (C) is 2- [2′-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] benzotriazole, 2- (2′-hydroxy-3,5-di-). t-butylphenyl) benzotriazole, 2- (2′-hydroxy-3,5-di-t-amylphenyl] benzotriazole, bis (1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, Bis- (N-methyl-2,2,6,6-tetramethyl-4-piperidinyl) sebacate, bis (2,2,6,6-tetramethyl-4-piperidinyl) sebacate, 1,2,3,4 -Butanetetracarboxylic acid and 1,2,2,6,6-pentamethyl-4-piperidinol and β, β, β ′, β ′,-tetramethyl-3,9- [2,4,8,10-tetra Oxaspi (5,5) is a condensation product of undecane] diethanol.

  In the polyacetal resin composition of the present embodiment, the content of the (C) weathering stabilizer is 0.1 to 5 parts by mass, preferably 0.1 to 3 parts by mass with respect to 100 parts by mass of the (A) polyacetal resin. Part, more preferably 0.3 to 2 parts by mass.

  (A) The weather resistance of the polyacetal resin composition is improved by setting the content of the (C) weather stabilizer to 0.1 parts by mass or more with respect to 100 parts by mass of the polyacetal resin. By setting the content of the agent to 5 parts by mass or less, a polyacetal resin composition having excellent mechanical properties can be obtained.

<Other materials>
The polyacetal resin composition of this embodiment contains other inorganic fillers and organic fillers in addition to the above-mentioned (A) polyacetal resin, (B) chlorite group mineral, and (C) weathering stabilizer. Can do. These fillers may be surface-treated fillers.

  Although it does not specifically limit as an inorganic filler, For example, a fibrous, powder particle form, plate shape, and a hollow filler are used.

  The fibrous filler is not particularly limited. For example, glass fiber, carbon fiber, silicone fiber, silica / alumina fiber, zirconia fiber, boron nitride fiber, silicon nitride fiber, boron fiber, potassium titanate fiber, stainless steel, Examples thereof include inorganic fibers such as metal fibers such as aluminum, titanium, copper, and brass. In addition, whiskers such as potassium titanate whisker and zinc oxide whisker having a short fiber length are included.

  The powder particulate filler is not particularly limited. For example, silicic acid such as carbon black, silica, quartz powder, glass beads, glass powder, calcium silicate, magnesium silicate, aluminum silicate, kaolin, clay, diatomaceous earth, and wollastonite. Metal oxides such as iron oxide, titanium oxide, and alumina; metal sulfates such as calcium sulfate and barium sulfate; carbonates such as magnesium carbonate and dolomite; other silicon carbide, silicon nitride, boron nitride, various metal powders, etc. Can be mentioned.

  The plate-like filler is not particularly limited, and examples thereof include mica, glass flakes, and various metal foils.

  Although it does not specifically limit as a hollow filler, For example, a glass balloon, a silica balloon, a shirasu balloon, a metal balloon etc. are mentioned.

  Although it does not specifically limit as an organic filler, For example, high melting-point organic fibrous fillers, such as an aromatic polyamide resin, a fluororesin, and an acrylic resin, are mentioned.

  These fillers can be used alone or in combination of two or more.

  These fillers can be either surface-treated or non-surface-treated, but the use of surface-treated fillers in terms of the smoothness of the molding surface and mechanical properties. May be preferred. It does not specifically limit as a surface treating agent, A conventionally well-known surface treating agent can be used. The surface treatment agent is not particularly limited. For example, surfactants such as various coupling treatment agents such as silane, titanate, aluminum, and zirconium, resin acids, organic carboxylic acids, salts of organic carboxylic acids, and the like. Can be used. Although it does not specifically limit as a surface treating agent, Specifically, for example, N- (2-aminoethyl) -3-aminopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, isopropyl trisstearoyl titanate, Examples include diisopropoxyammonium ethyl acetate and n-butyl zirconate.

  Further, the polyacetal resin composition of the present embodiment is provided with other additives such as stabilizers such as antioxidants, thermal stabilizers and formic acid scavengers, mold release agents, and lubricants in order to impart further characteristics. A conductive agent, a thermoplastic resin, a thermoplastic elastomer, or a pigment may be added. These additives may be used alone or in combination of two or more. For example, (A) 0.01-10 mass parts of at least 1 sort (s) of each additive can be contained with respect to 100 mass parts of polyacetal resin.

  As the antioxidant, a hindered phenol antioxidant is preferable. Although it does not specifically limit as a hindered phenol type antioxidant, 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-t-butyl-4-hydroxyphenyl) -propionate], 1,4-butanediol-bis- [3- (3,5- Di-t-butyl-4-hydroxyphenyl) -propionate], triethyleneglycol-bis- [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) -propio Over preparative], 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.

  Although it does not specifically limit as a heat stabilizer, For example, polyamide resins, such as nylon 4-6, nylon 6, nylon 6-6, nylon 6-10, nylon 6-12, nylon 12, and these polymers (for example, , Nylon 6 / 6-6 / 6-10, nylon 6 / 6-12, etc.). The other heat stabilizer is not particularly limited, and examples thereof include acrylamide and derivatives thereof, and copolymers of acrylamide and derivatives thereof with other vinyl monomers. Specifically, for example, acrylamide and derivatives thereof. And a poly-β-alanine copolymer obtained by polymerizing styrene and other vinyl monomers in the presence of a metal alcoholate. Other heat stabilizers are not particularly limited. For example, 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, Examples thereof include hydrazine derivatives, imidazole compounds, and imide compounds.

  Specific examples of the amide compound are not particularly limited, and examples thereof include polyvalent carboxylic acid amides such as isophthalic acid diamide and anthranilamides. Specific examples of the amino-substituted triazine compound are not particularly limited. For example, 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 can be mentioned. Specific examples of the adduct of the amino-substituted triazine compound and formaldehyde are not particularly limited, and examples thereof include N-methylol melamine, N, N′-dimethylol melamine, and N, N ′, N ″ -trimethylol melamine. Specific examples of the condensate of amino-substituted triazine compound and formaldehyde are not particularly limited, and examples thereof include melamine-formaldehyde condensate, and examples of urea derivatives are not particularly limited, For example, N-substituted urea, urea condensate, ethylene urea, hydantoin compound, and ureido compound can be mentioned Specific examples of N-substituted urea are not particularly limited, but for example, a substituent such as an alkyl group is substituted. Listed methylureas, alkylenebisureas, and aryl substituted ureas Specific examples of the urea condensate are not particularly limited, and examples thereof include urea and formaldehyde condensates, etc. Specific examples of the hydantoin compound include, but are not particularly limited to, for example, hydantoin, 5,5- Examples include dimethyl hydantoin, 5,5-diphenylhydantoin, etc. Specific examples of the ureido compound include, but are not limited to, allantoin, etc. Examples of the hydrazine derivative include hydrazide compounds. Specific examples include, but are not limited to, for example, dicarboxylic acid dihydrazide, and more specifically, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, pimelic acid dihydrazide, speric acid dihydride. Examples thereof include dorazide, azelaic acid dihydrazide, sebacic acid dihydrazide, dodecanedioic acid dihydrazide, isophthalic acid dihydrazide, phthalic acid dihydrazide, 2,6-naphthalenedicarbodihydrazide, etc. Specific examples of the imide compound are not particularly limited. Examples thereof include succinimide, glutarimide, and phthalimide.

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

  The formic acid scavenger is not particularly limited, and examples thereof include condensates of amino-substituted triazine compounds and amino-substituted triazine compounds with formaldehyde, such as melamine / formaldehyde condensate. Other formic acid scavengers include alkali metal or alkaline earth metal hydroxides, inorganic acid salts, carboxylate salts or alkoxides. One formic acid scavenger may be used, or two or more may be used in combination.

  As the release agent and lubricant, alcohol, fatty acid and fatty acid ester thereof, an olefin compound having an average polymerization degree of 10 to 500, and silicone are preferably used. One type of release agent and lubricant may be used, or two or more types may be used in combination.

  Although it does not specifically limit as a electrically conductive agent, For example, electroconductive carbon black, a metal powder, or a fiber is mentioned. One type of conductive agent may be used, or two or more types may be used in combination.

  Although it does not specifically limit as a thermoplastic resin, For example, polyolefin resin, an acrylic resin, a styrene resin, a polycarbonate resin, an uncured epoxy resin is mentioned. These modified products are also included. A thermoplastic resin may be used by 1 type and may be used in combination of 2 or more types.

  Although it does not specifically limit as a thermoplastic elastomer, For example, a polyurethane-type elastomer, a polyester-type elastomer, a polystyrene-type elastomer, and a polyamide-type elastomer are mentioned. One type of thermoplastic elastomer may be used, or two or more types may be used in combination.

  Although it does not specifically limit as a pigment, For example, an inorganic pigment, an organic pigment, a metallic pigment, a fluorescent pigment etc. are mentioned. Inorganic pigments refer to pigments commonly used for resin coloring, such as zinc sulfide, titanium oxide, barium sulfate, titanium yellow, cobalt blue, combustion pigments, carbonates, phosphates, Examples thereof include acetate, carbon black, acetylene black, lamp black and the like. The organic pigment is not particularly limited. And pigments such as phthalocyanines, dioxazines and phthalocyanines. Although the addition ratio of the pigment varies greatly depending on the color tone, it is difficult to clarify, but in general, it is used in the range of 0.05 to 5 parts by mass with respect to 100 parts by mass of the (A) polyacetal resin. One type of pigment may be used, or two or more types may be used in combination.

<Method for producing polyacetal resin composition>
The polyacetal resin composition of the present embodiment is obtained by mixing the above-described components and kneading using a kneader such as an extruder, a heating roll, a kneader, or a Banbury mixer. In particular, kneading with an extruder is preferable from the viewpoint of productivity. The kneading temperature may be in accordance with a preferable processing temperature of the base resin, and as a guideline, a range of 140 to 260 ° C, preferably a range of 180 to 230 ° C is often used. In order to stably produce a large amount of the polyacetal resin composition of this embodiment, a single-screw or twin-screw extruder is preferably used.

<Application>
The polyacetal resin composition obtained by the present embodiment has a mechanical balance, is excellent in thermal stability, mold deposit resistance, creep resistance, and weather resistance. Therefore, it can be used for molded articles for various purposes.

  Examples include mechanical parts such as gears, cams, sliders, levers, shafts, bearings, and guides, outsert molded resin parts, insert molded resin parts, chassis, trays, side plates, printers, and copiers. Digital video camera, camera and camera typified by digital camera, parts for video equipment, cassette player, music, video or information equipment, parts for communication equipment, parts for electric equipment, parts for electronic equipment. In addition, fuel parts such as gasoline tanks, fuel pump modules, valves, gasoline tank flanges, door parts, seat belt peripheral parts, combination switch parts, and switches are preferably used as automotive parts. The Furthermore, it can be suitably used as an industrial part typified by housing equipment.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention more concretely, this invention is not limited at all by these. In addition, the term and measurement method in an Example and a comparative example are as follows.

≪Measurement method≫
<Mechanical properties after thermal aging>
Using an IS-100GN injection molding machine manufactured by Toshiba Machine Co., Ltd., ISO test pieces were produced from the polyacetal resin compositions obtained in the examples and comparative examples. The prepared test piece was charged into a Tabai gear oven and subjected to aging treatment at 140 ° C. for one month. The test piece after heat aging was taken out from the gear oven and left in a thermostatic chamber maintained at 23 ° C. and 50% humidity for 24 hours. The test piece after being left was subjected to a tensile test under the following conditions to measure the tensile strength. The average value of three measurements (n = 3) was taken as the tensile strength of the test piece after thermal aging. The greater the tensile strength, the higher the thermal stability.
Tensile tester: AG-IS manufactured by Shimadzu Corporation
Tensile speed: 5 mm / min

<High temperature creep characteristics>
Using an IS-100GN injection molding machine manufactured by Toshiba Machine Co., Ltd., obtained in Examples and Comparative Examples at a cylinder temperature of 200 ° C., an injection pressure of 60 MPa, an injection time of 25 seconds, a cooling time of 15 seconds, and a mold temperature of 80 ° C. From the obtained polyacetal resin composition, strip-shaped test pieces having dimensions of 110 mm × 6.5 mm × 3 mm were prepared. Using a creep tester manufactured by Toyo Seimitsu Seisakusho Co., Ltd., the high temperature creep characteristics of the prepared test pieces were measured as follows. First, the test piece was hung on a creep test machine set at 80 ° C., loaded with a tensile stress of 20 MPa, and the time until the test piece was broken in air was measured. The high temperature creep characteristic of the test piece was evaluated by an average value of two measurements (n = 2). It was evaluated that the longer the time until the specimen was broken, the better the high temperature creep characteristics.

<MD characteristics>
Using a Ti-30G injection molding machine manufactured by Toyo Machine Metal Co., Ltd., a cylinder temperature of 200 ° C., an injection speed of 100 mm / s, an injection pressure of 100 kg · f, and a cycle timer of 15 sec, a polyacetal resin composition obtained in Examples and Comparative Examples The injection molding was repeated. The 10,000 shot molding was performed, the deposit | attachment adhering to a 30 degreeC low temperature metal mold | die was observed, and MD characteristics were evaluated by the following references | standards.
(Evaluation criteria for MD characteristics)
1: The deposit was observed in the range of 80% or more of the mold 2: The deposit was observed in the range of 30% or more and less than 80% of the mold 3: The deposit was 10% or more and 30% of the mold Observed in a range of less than 4: 4: Adhered material was observed in a range of less than 10% of the mold 5: No adhered material

<Evaluation of weather resistance test>
Using an IS-100GN injection molding machine manufactured by Toshiba Machine Co., Ltd., cylinder temperature: 200 ° C., injection pressure: 60 MPa, injection time: 25 seconds, cooling time: 15 seconds, mold temperature: 80 ° C. A test piece was prepared from the polyacetal resin composition obtained in the comparative example. A weather resistance test was performed under the following conditions using the prepared test piece. Further, the color difference (ΔE) of the test piece after the weather resistance test was measured as follows. The smaller the color difference (ΔE), the better the weather resistance.
Tester: Suga Tester Xenon Weather Meter Weathering Tester EL-2WL Black Panel Temperature: 89 ° C
Humidity: 50% R · H
Exposure time: 1000 hours (measurement of color difference (ΔE))
This was carried out using a Minolta color difference meter CR-200.

≪Raw ingredient≫
The following components were used in Examples and Comparative Examples.

<(A) polyacetal resin>
A twin-screw self-cleaning type polymerization machine with a jacket through which a heat medium can pass (L / D = 8 (L: distance (m) from the raw material supply port to the discharge port of the polymerization reactor, D: of the polymerization reactor) The inner diameter (m), the same applies hereinafter))) was adjusted to 80 ° C. 4 kg / hr of trioxane, 128.3 g / h of 1,3-dioxolane as a comonomer (3.9 mol% with respect to 1 mol of trioxane), methylal as a chain transfer agent (0.20 × 10 ^{−3 with} respect to 1 mol of trioxane) mol) was continuously added to the polymerizer. Furthermore, boron trifluoride di-n-butyl etherate (1.5 × 10 ⁻⁵ mol with respect to 1 mol of trioxane) was continuously added to the polymerization machine as a polymerization catalyst to carry out polymerization. The polyacetal copolymer discharged from the polymerization machine was put into a 0.1% aqueous triethylamine solution to deactivate the polymerization catalyst. The deactivated polyacetal copolymer was filtered with a centrifuge and then dried. The dried polyacetal copolymer was fed into a vented twin screw extruder. 0.5 parts by weight of water was added to 100 parts by weight of the melted polyacetal copolymer in the extruder, and the unstable terminal portion of the polyacetal copolymer was removed at a preset temperature of the extruder of 200 ° C. and a residence time of 7 minutes in the extruder. Decomposition and removal were performed. The polyacetal copolymer in which the unstable terminal portion was decomposed was devolatilized under the condition of a vent vacuum of 20 Torr, extruded as a strand from the extruder die, and pelletized. The pelletized polyacetal copolymer was used as (A) polyacetal resin.

<(B) Chlorite group mineral>
B-1: Chlorite having a chemical formula of 5MgO.Al ₂ O ₃ .3SiO ₂ .4H ₂ O and a volume average particle size of 13.2 μm (Fuji talc Kogyo Co., Ltd .: trade name “WL-13L”) )
B-2: Chlorite having a chemical formula of 5MgO.Al ₂ O ₃ .3SiO ₂ .4H ₂ O and a volume average particle size of 5.6 μm (manufactured by Fuji Talc Kogyo Co., Ltd .: trade name “WL-13J”) )

  Here, the volume average particle diameter was set to a central particle diameter D50% of a particle size distribution obtained by measurement by a laser light diffraction measurement method (manufactured by Shimadzu Corporation: SALD-3100).

<Other minerals>
B-3: Talc (Nippon Talc Co., Ltd. product name: “MS (untreated surface)”) average particle size 12.6 μm
B-4: Mica (Kuraray Co., Ltd. product name: “Szolite Mica 200-HK”)
B-5: Silica (Wako Pure Chemical Industries, Ltd .: Reagent name “Silica gel 60”)

  Here, the average particle diameter was set to a central particle diameter D50% of the particle size distribution obtained by measurement by a laser light diffraction measurement method (manufactured by Shimadzu Corporation: SALD-3100).

<(C) Weathering stabilizer>
C-1: 2- [2′-hydroxy-3 ′, 5′-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole C-2: Bis (2,2,6,6-tetramethyl -4-piperidinyl) sebacate C-3: 1,2,3,4-butanetetracarboxylic acid and 1,2,2,6,6-pentamethyl-4-piperidinol and β, β, β ′, β ′, − Condensate with tetramethyl-3,9- [2,4,8,10-tetraoxaspiro (5,5) undecane] diethanol

[Examples 1-7]
100 parts by mass of the prepared (A) polyacetal resin (melting point: 164.5 ° C.) and 0.15 parts by mass of calcium distearate as a formic acid scavenger were uniformly mixed using a Henschel mixer to obtain a mixture. This mixture was fed from the main feed port of a 30 mm vented twin-screw extruder with L / D = 30 set to 200 ° C., and the amount shown in Table 1 from the side feed port installed downstream of the main feed port. A polyacetal resin composition was obtained by feeding (B) a chlorite group mineral and (C) a weathering stabilizer and melt-kneading at a screw rotation speed of 100 rpm. The obtained physical properties of the polyacetal resin composition after thermal aging, high temperature creep characteristics, MD characteristics, and weather resistance were evaluated by the methods described above. The results are shown in Table 1.

[Comparative Example 1]
(B) A polyacetal resin composition was obtained in the same manner as in Example 2 except that no chlorite group mineral was used. The obtained physical properties of the polyacetal resin composition after thermal aging, high temperature creep characteristics, MD characteristics, and weather resistance were evaluated by the methods described above. The results are shown in Table 1.

[Comparative Example 2]
(B) A polyacetal resin composition was obtained in the same manner as in Example 5 except that the amount of chlorite group mineral used was changed to the amount shown in Table 1. The obtained physical properties of the polyacetal resin composition after thermal aging, high temperature creep characteristics, MD characteristics, and weather resistance were evaluated by the methods described above. The results are shown in Table 1.

[Comparative Examples 3 to 5]
(B) A polyacetal resin composition was obtained in the same manner as in Example 2 except that B-3 of other minerals was used instead of B-1 of the chlorite group mineral. The obtained physical properties of the polyacetal resin composition after thermal aging, high temperature creep characteristics, MD characteristics, and weather resistance were evaluated by the methods described above. The results are shown in Table 1.

  As shown in Table 1, the polyacetal resin compositions obtained in Examples 1 to 7 were confirmed to be excellent in thermal stability (mechanical properties after thermal aging), MD characteristics, high temperature creep characteristics, and weather resistance. It was done.

  On the other hand, it was confirmed that the polyacetal resin compositions obtained in Comparative Examples 1 to 5 were greatly reduced in thermal stability (mechanical properties after thermal aging), MD characteristics, high temperature creep characteristics, and weather resistance.

  The polyacetal resin composition of the present invention has the mechanical balance of the polyacetal resin, has excellent thermal stability and mold deposit resistance, and has excellent durability and weather resistance. It can be suitably used in a wide range of industries and the like.

Claims (4)

A polyacetal resin composition containing (A) 100 parts by mass of a polyacetal resin, (B) 0.001 to 5 parts by mass of a chlorite group mineral, and (C) 0.1 to 5 parts by mass of a weather resistance stabilizer. The polyacetal resin composition of Claim 1 whose content of the said chlorite group mineral (B) is 0.001-1 mass part. The polyacetal resin composition according to claim 1 or 2, wherein the chlorite group mineral (B) is at least one selected from the group consisting of chlorite, cookite, and nanthite. The polyacetal resin composition according to any one of claims 1 to 3, wherein an average particle size of the chlorite group mineral (B) is 0.01 to 100 µm.