JP5612430B2 - Polyacetal resin composition and method for producing the same - Google Patents

Description

  The present invention relates to a polyacetal resin composition having excellent mechanical properties such as tensile strength, bending strength, impact strength, and excellent dispersibility of cellulose fiber powder, and a method for producing the same.

  Polyacetal resin has excellent properties in mechanical properties, thermal properties, electrical properties, slidability, moldability, etc., mainly as electrical materials, automotive parts, precision machine parts as structural materials and mechanical parts. Widely used in With the expansion of the field in which polyacetal resins are used, the required characteristics tend to become more sophisticated, complex and specialized. Among them, materials in which a cellulosic material and a polyacetal resin are combined are studied for the purpose of using renewable resources and improving characteristics.

  Patent Document 1 discloses a polyacetal resin composition in which pulp is blended with a polyacetal resin. Here, improvements in mechanical strength, heat resistance, flammability (resin dripping during combustion), etc. are shown. However, the method for adjusting the material generally disperses pulp uniformly and stably in the resin. It was difficult to make the material practical.

  Patent Document 2 discloses a polyacetal resin composition in which a polyacetal resin and a fibrous cellulosic material having a specific bulk density are blended. Here, since the fibrous cellulosic material is used, the aggregation of the fibrous cellulosic material is relatively suppressed, but the resulting material has a lower flexural modulus, The improvement of mechanical properties was insufficient. In addition, there has been no disclosure about improvement of physical properties such as tensile strength, bending strength, and impact strength.

JP-A-3-217447 JP 2010-150313 A

  As described above, in the conventionally known technique, it is difficult to achieve both improvement in mechanical properties and dispersibility of the cellulosic material, and further improvement has been desired. The present invention solves these problems and provides a polyacetal resin composition excellent in mechanical properties such as tensile strength, bending strength, impact strength, and dispersibility of cellulose fiber powder, and a method for producing the same. For the purpose.

  As a result of intensive studies to solve the above problems, the present inventors have used a specific selected polyacetal resin in combination as a base resin, blended with the specific selected cellulose fiber powder, and further hindered phenol The present inventors have found that a polyacetal resin composition capable of solving the above-mentioned problems and achieving the object can be obtained by combining and blending a system antioxidant and a specific nitrogen-containing compound, and the present invention has been completed.

  That is, the present invention relates to (a) 100 parts by weight of a linear polyacetal resin obtained by copolymerizing 99.9 to 90.0% by weight of trioxane and 0.1 to 10.0% by weight of monofunctional cyclic ether. (B) Trioxane weight 99.89-89.0%, monofunctional cyclic ether weight 0.1-10.0%, polyfunctional glycidyl ether compound having 2-4 functional groups, 0.01-1.0% by weight 0.1 to 50 parts by weight of a branched polyacetal resin obtained by copolymerization, (c) 10 to 150 parts by weight of cellulose fiber powder having an aspect ratio of 5 to 25 and an average fiber length of 150 to 350 μm, (d) hindered phenol 0.01-3 parts by weight of a system antioxidant, (e) at least one nitrogen-containing compound selected from aminotriazine compounds, guanamine compounds, hydrazide compounds and polyamides 0 The present invention provides a polyacetal resin composition containing 0.01 to 3 parts by weight.

  The polyacetal resin composition of the present invention is excellent in mechanical properties such as tensile strength, bending strength, impact strength and the dispersibility of cellulose fiber powder, and is used for automobile parts, electric / electronic parts, miscellaneous goods, stationery. It can be suitably used for a molded product related to the like.

  Hereinafter, the polyacetal resin composition of the present invention and the production method thereof will be described in detail.

The main components constituting the polyacetal resin composition of the present invention are as described below.
<(A) Linear polyacetal resin>
The polyacetal resin of component (a) used in the present invention is a linear polyacetal resin obtained by copolymerizing 99.9 to 90.0% by weight of trioxane and 0.1 to 10.0% by weight of monofunctional cyclic ether. is there.

  The linear polyacetal resin of component (a) is produced by copolymerizing trioxane, which is a cyclic trimer of formaldehyde, and a monofunctional cyclic ether, and is usually heated by removing terminal unstable parts by hydrolysis. Stabilized against decomposition.

  In the present invention, as the monofunctional cyclic ether, compounds in which a cyclic structure is formed including a —C—O—C— unit are generically included, and a compound group called cyclic formal is also included. In the present invention, among such monofunctional cyclic ethers, a compound capable of introducing an oxyalkylene unit of about C2 to C6 into the molecule of (a) a linear polyacetal resin by copolymerization with trioxane is used. Ethylene oxide, propylene oxide, butylene oxide, cyclohexene oxide, epichlorohydrin, epibromohydrin, styrene oxide, oxetane, 3,3-bis (chloromethyl) oxetane, tetrahydrofuran, trioxepane, 1,3-dioxane, 1,3 -Dioxolane, propylene glycol formal, diethylene glycol formal, triethylene glycol formal, 1,4-butanediol formal, 1,5-pentanediol formal, 1,6-hexanediol formal, etc. Can be mentioned.

  These monofunctional cyclic ethers can be used alone or in combination of two or more. In particular, monofunctional cyclic ethers such as ethylene oxide, 1,3-dioxolane, 1,4-butanediol formal, and diethylene glycol formal are preferable.

  The copolymerization ratio of these monofunctional cyclic ethers is 0.1 to 10.0% by weight relative to 99.9 to 90.0% by weight of trioxane, and preferably 99.7 to 93.0% by weight of trioxane. 0.3 to 7.0% by weight based on the weight. The (a) linear polyacetal resin thus obtained preferably contains a unit derived from such a monofunctional cyclic ether in this proportion in the molecule. When the copolymerization ratio of the monofunctional cyclic ether is small, the thermal stability of the (a) linear polyacetal resin which is the substrate of the polyacetal resin composition of the present invention tends to be insufficient, and the monofunctional cyclic ether When the copolymerization ratio is large, the mechanical properties of (a) the linear polyacetal resin are insufficient.

The melt index of the polyacetal resin (a) is preferably in the range of 10 to 50 g / 10 min. When the melt index is too small or too large, the effects of the present invention may not be sufficiently obtained. The melt index is a value measured under conditions of 190 ° C. and 2.16 kgf (21.2 N) in accordance with ASTM-D1238.
<(B) Branched polyacetal resin>
The polyacetal resin of component (b) used in the present invention is a polyfunctional glycidyl ether having 99.89 to 89.0% by weight of trioxane, 0.1 to 10.0% by weight of monofunctional cyclic ether and 2 to 4 functional groups. A branched polyacetal resin obtained by copolymerizing 0.01 to 1.0% by weight of a compound.

  The branched polyacetal resin (b) is produced by copolymerizing trioxane, a monofunctional cyclic ether, and a polyfunctional glycidyl ether compound having 2 to 4 functional groups. Usually, the terminal unstable portion is removed by hydrolysis. Removed and stabilized against thermal decomposition.

  (B) As a monofunctional cyclic ether used for manufacture of the branched polyacetal resin of a component, the substance used for the polyacetal resin of the said (a) component can be used similarly. In particular, monofunctional cyclic ethers such as ethylene oxide, 1,3-dioxolane, 1,4-butanediol formal, and diethylene glycol formal are preferable.

  The polyfunctional glycidyl ether compound having 2 to 4 functional groups used for the production of the component (b) branched polyacetal resin is a compound having 2 to 4 glycidyl ether units in one molecule, ethylene glycol diglycidyl ether, Propylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, hexamethylene glycol diglycidyl ether, resorcinol diglycidyl ether, bisphenol A diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, polybutylene glycol di 3 such as bifunctional glycidyl ether compounds such as glycidyl ether, trimethylolpropane triglycidyl ether, glycerol triglycidyl ether Ability glycidyl ether compounds, one or more selected from the group consisting of tetrafunctional glycidyl ether compounds such as pentaerythritol tetraglycidyl ether. Among these, compounds having 3 to 4 glycidyl ether units in one molecule such as trimethylolpropane triglycidyl ether, glycerol triglycidyl ether, pentaerythritol tetraglycidyl ether are particularly preferable.

  In the present invention, the branched polyacetal resin used as the component (b) is 0.1 to 10.0% by weight of the monofunctional cyclic ether and 99 to 89% by weight of trioxane, and the polyfunctional glycidyl ether compound. In the proportion of 0.01 to 1.0% by weight, and preferably 0.3 to 7% of the monofunctional cyclic ether with respect to 99.67 to 92.3% by weight of trioxane. 0.0% by weight, and obtained by copolymerizing the polyfunctional glycidyl ether compound at a ratio of 0.03 to 0.7% by weight.

  When the proportion of the monofunctional cyclic ether is small, the thermal stability of the (b) branched polyacetal resin tends to be insufficient, and when the proportion of the monofunctional cyclic ether is large, the mechanical properties of the (b) branched polyacetal resin. Is insufficient. Further, when the copolymerization ratio of the polyfunctional glycidyl ether compound is small, the degree to which the obtained (b) branched polyacetal resin contributes to the improvement of the mechanical properties of the polyacetal resin composition becomes insufficient. When the copolymerization ratio of the ether compound is large, the flowability of the obtained (b) branched polyacetal resin becomes insufficient, which is not preferable because it adversely affects the dispersibility of the cellulose fiber powder.

  In the present invention, the melt index of the branched polyacetal resin (b) is preferably in the range of 0.01 to 10 g / 10 min. When the melt index is too small or too large, the effects of the present invention may not be sufficiently obtained. The melt index is a value measured under conditions of 190 ° C. and 2.16 kgf (21.2 N) in accordance with ASTM-D1238.

In the present invention, the blending amount of the branched polyacetal resin as the component (b) is 0.1 to 50 parts by weight, preferably 0.5 to 20 parts by weight with respect to 100 parts by weight of the linear polyacetal resin as the component (a). Parts, more preferably 1 to 10 parts by weight. When the blending amount of the branched polyacetal resin (b) is less than 0.1 parts by weight, the improvement of the mechanical properties of the polyacetal resin composition is insufficient, and when it exceeds 50 parts by weight, the cellulose fiber powder Since the dispersibility of is deteriorated, it is not preferable.
<(C) Cellulose fiber powder>
(C) Cellulose fiber powder used in the present invention is made from a refined pulp and made into a powder form, and its aspect ratio is 5 to 25. In particular, the preferred aspect ratio is 7-20. (C) When the aspect ratio of the cellulose fiber powder is less than 5, the improvement of the mechanical properties of the polyacetal resin composition is insufficient, and when it exceeds 25, the dispersibility of the cellulose fiber powder is deteriorated. Absent. The aspect ratio can be measured by observation with an SEM or an optical microscope.

  Moreover, the average fiber length of (c) cellulose fiber powder is 150-350 micrometers, and 180-320 micrometers is especially preferable. (C) When the average fiber length of the cellulose fiber powder is less than 150 μm, the improvement of the mechanical properties of the polyacetal resin composition is insufficient, and when it exceeds 350 μm, the dispersibility of the cellulose fiber powder is deteriorated, Moreover, since decomposition | disassembly of a polyacetal resin composition may advance, it is unpreferable. The average fiber length can be measured by observation with an SEM or an optical microscope.

  In addition, the (c) cellulose fiber powder used in the present invention preferably has an α cellulose purity of 98 to 100%, particularly preferably an α cellulose purity in the range of 99 to 100%. Thus, the polyacetal resin composition excellent also in heat stability etc. can be obtained by using cellulose fiber powder with high (alpha) cellulose purity. When cellulose fiber powder with insufficient α cellulose purity is used, the resulting polyacetal resin composition has insufficient stability, and it may be difficult to produce due to decomposition of the resin.

In this invention, the compounding quantity of (c) cellulose fiber powder is 10-150 weight part with respect to 100 weight part of (a) linear polyacetal resin, Preferably it is 10-150 weight part. (C) When the blending amount of the cellulose fiber powder is less than 10 parts by weight, the improvement of the mechanical properties of the polyacetal resin composition is insufficient, and when it exceeds 150 parts by weight, the dispersibility of the cellulose fiber powder is deteriorated. Therefore, it is not preferable.
<(D) Hindered phenolic antioxidant>
The polyacetal resin composition of the present invention can stably improve mechanical properties by using (d) a hindered phenol compound. (D) As the hindered phenol compound, it is connected with a monocyclic hindered phenol compound (for example, 2,6-di-t-butyl-p-cresol), a hydrocarbon group or a group containing a sulfur atom. Polycyclic hindered phenol compounds (for example, 2,2′-methylenebis (4-methyl-6-tert-butylphenol), 4,4′-methylenebis (2,6-di-tert-butylphenol), 1,1, 3-tris (2-methyl-4-hydroxy-5-t-butylphenyl) butane, 4,4′-butylidenebis (3-methyl-6-t-butylphenol), 1,3,5-trimethyl-2,4 , 6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, 4,4′-thiobis (3-methyl-6-tert-butylphenol)), ester group or A hindered phenol compound having an amide group (for example, n-octadecyl-3- (4′-hydroxy-3 ′, 5′-di-t-butylphenyl) propionate, n-octadecyl-2- (4′-hydroxy-) 3 ′, 5′-di-t-butylphenyl) propionate, 1,6-hexanediol-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate], pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 3.9 -Bis {2- [3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy] -1,1-dimethylethyl -2,4,8,10-tetraoxaspiro [5.5] undecane, 2-t-butyl-6- (3'-t-butyl-5'-methyl-2'-hydroxybenzyl) -4-methyl Phenyl acrylate, 2- [1- (2-hydroxy-3,5-di-t-pentylphenyl) ethyl] -4,6-di-t-pentylphenyl acrylate, di-n-octadecyl-3,5-di -T-butyl-4-hydroxybenzylphosphonate, N, N'-hexamethylenebis (3,5-di-t-butyl-4-hydroxy-dihydrocinnamamide, N, N'-ethylenebis [3- ( 3,5-di-t-butyl-4-hydroxyphenyl) propionamide], N, N′-tetramethylenebis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionamide], N N′-hexamethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionamide], N, N′-ethylenebis [3- (3-tert-butyl-5-methyl-) 4-hydroxyphenyl) propionamide], N, N′-hexamethylenebis [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionamide], N, N′-bis [3- ( 3,5-di-tert-butyl-4-hydroxyphenyl) propionyl] hydrazine, N, N′-bis [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionyl] hydrazine, 1, 3,5-tris (3,5-di-t-butyl-4-hydroxybenzyl) isocyanurate, 1,3,5-tris (4-t-butyl-3-hydroxy-2,6-dimethylbenzyl) i Cyanurate, etc.) and the like.

In this invention, (d) hindered phenolic antioxidant can be used individually or in combination of 2 or more types. The blending ratio is 0.01 to 3 parts by weight, preferably 0.02 to 1 part by weight, based on 100 parts by weight of the (a) linear polyacetal resin.
<(E) Nitrogen-containing compound>
By using at least one nitrogen-containing compound selected from (e) an aminotriazine compound, a guanamine compound, a hydrazide compound and a polyamide, the polyacetal resin composition of the present invention can be obtained stably with improved mechanical properties, Melt stability is also improved.

  Examples of aminotriazine compounds include melamine or derivatives thereof [melamine, melamine condensates (melam, melem, melon, etc.)], guanamine or derivatives thereof, and aminotriazine resins [melamine co-condensation resins (melamine-formaldehyde resin, phenol-melamine). Resin, melamine-phenol-formaldehyde resin, benzoguanamine-melamine resin, aromatic polyamine-melamine resin, etc.), co-condensation resin of guanamine, etc.].

  Guanamine compounds include aliphatic guanamine compounds (monoguanamines, alkylenebisguanamines, etc.), alicyclic guanamine compounds (monoguanamines, etc.), aromatic guanamine compounds [monoguanamines (benzoguanamine and its functional group substitution) ), Α- or β-naphthoguanamine and their functional group-substituted derivatives, polyguanamines, aralkyl or aralkylenamines, etc.], heteroatom-containing guanamine compounds [acetal group-containing guanamines, tetraoxospiro ring-containing Guanamines (CTU-guanamine, CMTU-guanamine, etc.), isocyanuric ring-containing guanamines, imidazole ring-containing guanamines, etc.]. Moreover, the compound etc. which the alkoxymethyl group of said melamine, a melamine derivative, and a guanamine type compound substituted by the amino group are also contained.

Examples of hydrazide compounds include aliphatic carboxylic acid hydrazide compounds (such as stearic acid hydrazide, 12-hydroxystearic acid hydrazide, sebacic acid dihydrazide, dodecanedioic acid dihydrazide, eicosane diacid dihydrazide), alicyclic carboxylic acid hydrazide compounds (1 , 3-bis (hydrazinocarbonoethyl) -5-isopropylhydantoin), aromatic carboxylic acid hydrazide compounds (4-hydroxy-3,5-di-t-butylphenylbenzoic acid hydrazide, 1-naphthoic acid hydrazide) 2-naphthoic acid hydrazide, isophthalic acid dihydrazide, 2,6-naphthalenedicarboxylic acid dihydrazide, etc.), heteroatom-containing carboxylic acid hydrazide compounds, polymer-type carboxylic acid hydrazide compounds, and the like.

  As the polyamide, a polyamide derived from a diamine and a dicarboxylic acid; an aminocarboxylic acid, a polyamide obtained by using a diamine and / or a dicarboxylic acid in combination; a lactam; and a diamine and / or a dicarboxylic acid as needed Polyamide derived by the combined use of Also included are copolyamides formed from two or more different polyamide-forming components.

  Specific examples of polyamides include polyamide 3, polyamide 4, polyamide 46, polyamide 6, polyamide 66, polyamide 610, polyamide 612, polyamide 11, polyamide 12, and other aliphatic polyamides, aromatic dicarboxylic acids (for example, terephthalic acid). And / or polyamides obtained from isophthalic acid) and aliphatic diamines (eg hexamethylenediamine), polyamides obtained from aliphatic dicarboxylic acids (eg adipic acid) and aromatic diamines (eg metaxylylenediamine) And polyamides obtained from aromatic and aliphatic dicarboxylic acids (for example, terephthalic acid and adipic acid) and aliphatic diamines (for example, hexamethylenediamine), and copolymers thereof. It is also possible to use a polyamide-based block copolymer in which a polyamide hard segment and another soft segment such as a polyether component are combined.

(E) Nitrogen-containing compounds selected from aminotriazine compounds, guanamine compounds, hydrazide compounds and polyamides can be used alone or in combination of two or more. The blending ratio is 0.01 to 3 parts by weight, preferably 0.02 to 1 part by weight, based on 100 parts by weight of the (a) linear polyacetal resin.
<(F) Processing aid>
The polyacetal resin composition of the present invention comprises (f) at least one processing aid selected from long chain fatty acids, derivatives of long chain fatty acids, long chain fatty alcohols, polyoxyalkylene glycols, olefin waxes, and silicone compounds. By using it, improvement of mechanical properties can be stably obtained, and melt processability is also improved. Therefore, it is preferable to add (f) a processing aid.

  The long chain fatty acid may be a saturated fatty acid or an unsaturated fatty acid. Also, those in which some of the hydrogen atoms are substituted with a substituent such as a hydroxyl group can be used. Examples of such long-chain fatty acids include monovalent or divalent fatty acids having 10 or more carbon atoms, monovalent unsaturated fatty acids having 10 or more carbon atoms, and divalent fatty acids (dibasic fatty acids) having 10 or more carbon atoms. Illustrated. The fatty acid also includes a fatty acid having one or more hydroxyl groups in the molecule.

  Derivatives of long chain fatty acids include fatty acid esters and fatty acid amides.

  Examples of the fatty acid ester include esters of the long-chain fatty acid and alcohol. The structure is not particularly limited, and either a linear or branched fatty acid ester can be used. Specific examples of fatty acid esters include ethylene glycol mono or dipalmitate, ethylene glycol mono or distearate, ethylene glycol mono or dibehenate, ethylene glycol mono or dimtanate, glycerin mono to tripalmitate, glycerin. Mono-tristearic acid ester, glycerol mono-tribehenic acid ester, glycerin mono-trimontanic acid ester, pentaerythritol mono-tetrapalmitic acid ester, pentaerythritol mono-tetrastearic acid ester, pentaerythritol mono-tetrabehenic acid ester, pentaerythritol mono-ester Thru tetramontanate ester, polyglycerol tristearate ester, trimethylo Propane monopalmitate, pentaerythritol monoundecylate, sorbitan monostearate, polyalkylene glycol (polyethylene glycol, polypropylene glycol, etc.) mono or dilaurate, mono or dipalmitate, mono or distearate, mono or dibehenate, mono or Dimontanate, mono or dioleate, mono or dilinoleate and the like can be mentioned.

Examples of fatty acid amides include capric acid amides, lauric acid amides, myristic acid amides, palmitic acid amides, stearic acid amides, arachidic acid amides, behenic acid amides, primary fatty acid amides, olein Primary acid amides of unsaturated fatty acids such as acid amides, secondary acid amides of saturated and / or unsaturated fatty acids and monoamines such as stearyl stearic acid amide, stearyl oleic acid amide, ethylenediamine-dipalmitic acid amide, ethylenediamine -Distearic acid amide (ethylene bisstearyl amide), hexamethylenediamine-distearic acid amide, ethylenediamine-dibehenic acid amide, ethylenediamine-dimantanoic acid amide, ethylenediamine-dioleic acid amide, ethylenediamine- Such as erucic acid amide and the like, further ethylenediamine - such as a bisamide in which different species of acyl groups to amine sites of an alkylenediamine is bound, such as (stearic acid amide) oleic acid amide can be exemplified.

  Examples of the long chain aliphatic alcohol include lauryl alcohol, myristyl alcohol, cetyl alcohol, oleyl alcohol, stearyl alcohol, and behenyl alcohol.

  Examples of the polyoxyalkylene glycol include homo- or copolymers of alkylene glycol (such as alkylene glycol such as ethylene glycol, propylene glycol, and tetramethylene glycol), and derivatives thereof.

Specific examples of the polyoxyalkylene glycol include polyoxyalkylene glycols such as polyethylene glycol, polypropylene glycol and polytetramethylene glycol, polyoxyethylene-polyoxypropylene copolymers (random or block copolymers, etc.), polyoxyethylene Examples include copolymers such as polyoxypropylene glyceryl ether and polyoxyethylene polyoxypropylene monobutyl ether. Of these, polymers having oxyethylene units, such as polyethylene glycol, polyoxyethylene polyoxypropylene copolymers, and derivatives thereof are preferable. The average molecular weight of the polyoxyalkylene glycol is about 3 × 10 ² to 1 × 10 ⁶ , preferably about 1 × 10 ³ to 1 × 10 ⁵ .

  Examples of the olefin wax include low molecular weight polyolefin (for example, low molecular weight polyethylene, low molecular weight polypropylene, low molecular weight copolymer of ethylene and α-olefin), and oxidized polyethylene wax.

  Examples of the silicone compound include (poly) organosiloxane. Examples of the (poly) organosiloxane include monoorganosiloxanes such as dialkylsiloxanes (such as dimethylsiloxane), alkylarylsiloxanes (such as phenylmethylsiloxane), diarylsiloxanes (such as diphenylsiloxane), and homopolymers thereof (polydimethylsiloxane, poly Examples thereof include phenylmethylsiloxane) and copolymers. The polyorganosiloxane may be an oligomer.

  In addition, (poly) organosiloxane has an epoxy group, hydroxyl group, alkoxy group, carboxyl group, amino group or substituted amino group (such as dialkylamino group), ether group, vinyl group, ) Modified (poly) organosiloxane having a substituent such as acryloyl group is also included.

In the present invention, it is not essential to add (f) at least one processing aid selected from long-chain fatty acids, long-chain fatty acid derivatives, long-chain aliphatic alcohols, polyoxyalkylene glycols, olefinic waxes, and silicone compounds. However, in order to impart good processability, and in order to achieve stable mechanical properties and excellent surface properties with good processability, it is preferable to add such a processing aid, and the above compound alone. Or it can be used in combination of two or more. The blending ratio in the case of blending the processing aid is preferably 0.01 to 3 parts by weight, particularly preferably 0.05 to 1 part by weight with respect to 100 parts by weight of the (a) linear polyacetal resin.
<Preparation method of polyacetal resin composition>
In this invention, the specific aspect of the preparation method of the said polyacetal resin composition is not specifically limited, Generally, it can prepare with a well-known equipment and method as a preparation method of a synthetic resin composition or its molded article. That is, necessary components can be mixed and kneaded using an extruder or other melt kneader to prepare pellets for molding. A plurality of extruders or other melt kneaders may be used. In particular, in the present invention, it is preferable to use a twin-screw extruder as the extruder from the viewpoint of improving both mechanical properties and dispersibility of the cellulose fiber powder. In particular, from the viewpoint of improving both mechanical properties and dispersibility of cellulose fiber powder, a twin-screw extruder capable of side-feeding is used, and (c) cellulose fiber powder is independent of other raw materials from the side of the extruder. A production method in which the mixture is melted and kneaded is preferable.

  In preparing the polyacetal resin composition of the present invention, a substance that improves the adhesion between the polyacetal resin and (c) cellulose fiber powder can be used. Here, the substances for improving the adhesion include isocyanate compounds, isothiocyanate compounds, and their modified isocyanate compounds, thermoplastic polyurethane resins, and acid anhydrides of α, β-monoolefinic unsaturated carboxylic acids. Examples thereof include a polymer, a copolymer, and a boric acid compound.

Furthermore, various known additives can be blended in the composition of the present invention in order to improve its physical properties according to the intended use. Examples of additives include various colorants, lubricants, nucleating agents, surfactants, heterogeneous polymers, organic polymer modifiers, and inorganic, organic, metal and other fibrous, powdered, and plate-like fillers. 1 type or 2 types or more can be mixed and used.
<Method and application of polyacetal resin composition>
The polyacetal resin composition of the present invention can be molded by various known molding methods (for example, injection molding, extrusion molding, compression molding, blow molding, vacuum molding, foam molding, rotational molding, gas injection molding, etc.). The product can be molded. In particular, it is suitable for injection molding. These molded products can be used for various applications such as automobile parts, electrical / electronic parts, building materials, life-related parts, makeup-related parts, and medical-related parts.

  Specifically, automobile parts include inner handles, fael trunk openers, seat belt buckles, assist wraps, interior parts such as switches, knobs, levers and clips, electrical system parts such as meters and connectors, audio equipment and cars. In-vehicle electrical / electronic parts such as navigation equipment, parts that come into contact with metal, such as window regulator carrier plates, door lock actuator parts, mirror parts, wiper motor system parts, mechanical parts such as fuel system parts, etc. It is done.

  As electrical / electronic parts, parts or members of equipment composed of polyacetal resin molded products and having many metal contacts, such as audio equipment, video equipment, telephones, copiers, facsimiles, word processors, computers, etc. OA equipment, toy parts or members, specifically, chassis, gears, levers, cams, pulleys, bearings, and the like.

  In addition, lighting equipment, fittings, piping, faucets, faucets, toilet parts and other building materials and piping parts, fasteners, stationery, lip balm / lipstick containers, cleaning equipment, water purifiers, spray nozzles, spray containers, aerosol containers, It is suitably used for a wide range of life-related parts, makeup-related parts, and medical-related parts such as general containers and needle holders.

  Hereinafter, the present invention will be described more specifically based on examples, but the present invention is not limited to these examples.

Examples 1 and 2 and Comparative Examples 1 to 3
In the proportions shown in Table 1, (a) linear polyacetal resin, (b) branched polyacetal resin, (c) cellulose fiber powder, (d) hindered phenol antioxidant, (e) nitrogen-containing compound, and (f ) Processing aid was melt kneaded with a twin screw extruder to prepare a pellet-like polyacetal resin composition. In addition, (c) cellulose fiber powder was supplied and mixed from the feeder independently from the side of the twin-screw extruder. A predetermined test piece was molded by an injection molding machine using the obtained pellet, and the test evaluation was performed. The results are shown in Table 1.
[Use ingredients]
Details of the components used are as follows.
(A) Linear polyacetal resin (a-1) Linear polyacetal resin obtained by copolymerizing 96.5% by weight of trioxane and 3.5% by weight of 1,3-dioxolane, melt index = 27 g / 10 minutes (poly (Plastics Co., Ltd.)
(B) Branched polyacetal resin (b-1) Branched polyacetal resin obtained by copolymerizing 98.2% by weight of trioxane, 1.7% by weight of 1,3-dioxolane and 0.1% by weight of trimethylolpropane triglycidyl ether Melt index = 1.5 g / 10 min (manufactured by Polyplastics Co., Ltd.)
(C) Cellulose fiber powder (c-1) ARBOCEL BC 200, aspect ratio 15, average fiber length 300 μm, α cellulose purity 99.5%, bulk specific gravity 70-90 g / L (manufactured by Rettenmeier)
(C-2) KC floc W-200, aspect ratio of 2 or less, average fiber length of 50 μm or less, α cellulose purity of 99% or more, bulk specific gravity of 300 to 360 g / L (manufactured by Nippon Paper Chemicals Co., Ltd.)
(D) Hindered phenol antioxidant (d-1) Pentaerythritol tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate]
(E) Nitrogen-containing compound (e-1) Melamine (f) Processing aid (f-1) Ethylenebisstearylamide [extrusion conditions]
Extruder: TEX-30α (L / D = 38.5), screw speed manufactured by Nippon Steel Works: 129 rpm
Barrel temperature: C2 = 160 ° C., C3 to C11 · D = 200 ° C.
〔Molding condition〕
Molding machine: ROBOSHOT S2000i100B, screw diameter 28 mm, FANUC cylinder temperature: 200 ° C
Mold temperature: 90 ° C (water temperature control)
〔Test method〕
Details of the test method are as follows.
(1) Tensile strength, tensile elongation (fracture strain)
Tensile strength (MPa) and tensile elongation (%) were evaluated according to the evaluation criteria defined in ISO527-1,2.
(2) Flexural modulus and flexural strength Based on ISO178, flexural strength (MPa) and flexural modulus (MPa) were measured.
(3) Charpy impact strength (with notch)
Charpy impact strength (notched) (kJ / m ² ) was measured according to ISO 179 / 1eA.
(4) External appearance evaluation The external appearance of the bending test piece based on ISO178 was visually observed.

  From the comparison of the results shown in Table 1, the polyacetal resin compositions (Examples 1 and 2) that satisfy the requirements of the present invention are compared with the comparative example 1 in which the (b) branched polyacetal resin is not blended. It can be seen that the bending strength and impact strength are improved and each has a high value. In addition, from the comparison between Comparative Example 2 and Comparative Example 3, when the cellulose fiber powder does not satisfy the requirements of the present invention, even if (b) a branched polyacetal resin is blended, although an improvement in flexural modulus is seen, It can be seen that the values of tensile strength, bending strength and impact strength are low.

  In each example and comparative example, (f) a composition without a processing aid was prepared and evaluated in the same manner, but the mechanical properties (tensile properties) equivalent to the corresponding examples and comparative examples were evaluated. , Bending characteristics, impact characteristics, etc.) (not particularly shown in Table 1). In order to stabilize the melt processing and ensure the stability and uniformity of the quality of the molded product, it is desirable to add (f) a processing aid. Table 1 shows the composition of (f) a composition containing the processing aid. Although the results are shown, the effect of the present invention on the improvement of mechanical properties, in particular, the effect of (b) blending of the branched polyacetal resin and the selection of the cellulose fiber powder is clear from Table 1 as described above.

Claims (7)

(A) With respect to 100 parts by weight of a linear polyacetal resin obtained by copolymerizing 99.9 to 90.0% by weight of trioxane and 0.1 to 10.0% by weight of monofunctional cyclic ether,
(B) 99 to 89% by weight of trioxane, 0.1 to 10.0% by weight of a monofunctional cyclic ether and 0.01 to 1.0% by weight of a polyfunctional glycidyl ether compound having 2 to 4 functional groups. 0.1 to 50 parts by weight of a branched polyacetal resin obtained by copolymerization,
(C) 10 to 150 parts by weight of cellulose fiber powder having an aspect ratio of 5 to 25 and an average fiber length of 150 to 350 μm,
(D) 0.01-3 parts by weight of a hindered phenol-based antioxidant and 0.01-3 parts by weight of at least one nitrogen-containing compound selected from (e) an aminotriazine compound, a guanamine compound, a hydrazide compound and a polyamide. A polyacetal resin composition comprising the composition. (C) The polyacetal resin composition of Claim 1 whose (alpha) cellulose purity of a cellulose fiber powder is 98 to 100%. (B) The polyacetal resin composition according to claim 1 or 2, wherein the polyfunctional glycidyl ether compound used for forming the branched polyacetal resin is a compound having 3 to 4 glycidyl ether units in one molecule. The polyacetal resin composition according to any one of claims 1 to 3, wherein a melt index (based on ASTM-D1238, 190 ° C, 2.16 kgf) of the branched polyacetal resin (b) is 0.01 to 10 g / 10 min. object. (A) The polyacetal resin composition according to any one of claims 1 to 4, wherein the melt index (based on ASTM-D1238, 190 ° C, 2.16 kgf) of the linear polyacetal resin is 10 to 50 g / 10 min. . Further, (f) at least one processing aid selected from long-chain fatty acids, long-chain fatty acid derivatives, long-chain aliphatic alcohols, polyoxyalkylene glycols, olefinic waxes, and silicone compounds, (a) linear polyacetals The polyacetal resin composition according to any one of claims 1 to 5, which is contained in a proportion of 0.01 to 3 parts by weight with respect to 100 parts by weight of the resin. In producing the polyacetal resin composition according to any one of claims 1 to 6, a biaxial extruder capable of side feed is used, and (c) cellulose fiber powder is referred to as other raw material from the side of the extruder. A method for producing a polyacetal resin composition that is independently supplied and melt-kneaded.