WO2010119826A1

WO2010119826A1 - Cellulose fiber-reinforced polyacetal resin composition

Info

Publication number: WO2010119826A1
Application number: PCT/JP2010/056496
Authority: WO
Inventors: 邦明川口; 一浩水口; 克利鈴木; 正人鈴木; 稔夫小邦
Original assignee: ポリプラスチックス株式会社; ダイセルポリマー株式会社
Priority date: 2009-04-15
Filing date: 2010-04-12
Publication date: 2010-10-21
Also published as: TW201041946A; JP2010265438A

Abstract

Disclosed is a polyacetal resin composition which exhibits excellent rigidity, heat conductivity, sliding properties and vibration damping properties, while having low specific gravity and low ash content. Specifically disclosed is a cellulose fiber-reinforced polyacetal resin composition which contains, per (a) 100 parts by weight of a polyacetal resin, (b) 10-150 parts by weight of fibrillated cellulose fibers, (c) 0.01-3 parts by weight of a hindered phenolic antioxidant, and (d) 0.01-3 parts by weight of at least one nitrogen-containing compound that is selected from among amino triazine compounds, guanamine compounds, hydrazide compounds and polyamides.

Description

Cellulose fiber reinforced polyacetal resin composition

The present invention is reinforced with cellulose fiber, has both high rigidity and excellent thermal conductivity, slidability, vibration damping, etc., and causes an increase in specific gravity and an increase in ash content like a reinforcing material by an inorganic filler. The present invention relates to a polyacetal resin composition that does not occur.
Background art

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.

For example, in order to improve the strength and rigidity of the polyacetal resin, a method of blending a reinforcing material such as a glass-based inorganic filler is generally used, but this method increases the specific gravity of the polyacetal resin composition obtained. There is a problem that a large amount of ash (incineration residue) remains after incineration. In addition, features such as slidability inherent in polyacetal resin are greatly impaired. Furthermore, in recent years, with the progress of precision of mechanical parts and the like, in addition to improvements in strength and rigidity, improvements in thermal conductivity and vibration damping properties may be required. It is difficult to meet this demand by the method of blending the reinforcing material.

In response to the above problems, Japanese Patent Application Laid-Open No. 3-217447 discloses a polyacetal resin composition in which pulp is blended with polyacetal resin, such as mechanical strength, heat resistance, and flammability (resin dripping during combustion). Improvements are shown. However, in this method, mixing of the polyacetal resin and the pulp tends to be insufficient, it is difficult to stably obtain excellent characteristics, and it is not suitable for practical use. Further, JP-A-3-217447 does not disclose anything about improvement of thermal conductivity, slidability, vibration damping and the like of the polyacetal resin composition.

Japanese Patent Application Laid-Open No. 2007-084713 provides a manufacturing method for obtaining a thermoplastic resin composition containing fibrillated cellulose fibers. This Japanese Patent Application Laid-Open No. 2007-084713 includes There is no specific description about the polyacetal resin composition, and not only the improvement in strength and rigidity but also the thermal conductivity, slidability, vibration damping, etc. are improved. Nothing is disclosed.

In the invention described in JP-A-3-28260, a small amount of a stabilizer selected from the group consisting of microcrystalline cellulose and fibrous cellulose is blended with the polyacetal resin to improve the thermal stability of the polyacetal resin. However, in this invention, none of the improvements in the rigidity, thermal conductivity, slidability, vibration damping and the like of the polyacetal resin composition has been achieved.
Summary of the Invention

Conventionally known techniques have not been able to obtain a polyacetal resin composition having rigidity, thermal conductivity, slidability, and vibration damping properties, and having a low specific gravity and a low ash content, as described above.

An object of the present invention is to solve these problems and to provide a polyacetal resin composition having excellent rigidity, thermal conductivity, slidability, vibration damping properties, low specific gravity and low ash content, and a molded product thereof. And

As a result of intensive studies to solve the above problems, the present inventors have formulated a polyacetal resin composition that can solve the above problems and achieve the object by combining a specific fiber filler and an additive with the polyacetal resin. The present inventors have found that a product and a molded product thereof can be obtained, and have completed the present invention.

That is, the present invention
(A) For 100 parts by weight of the polyacetal resin,
(B) 10 to 150 parts by weight of fibrillated cellulose fiber,
(C) 0.01 to 3 parts by weight of a hindered phenolic antioxidant and (d) 0.01 to 3 parts by weight of at least one nitrogen-containing compound selected from aminotriazine compounds, guanamine compounds, hydrazide compounds and polyamides. The present invention provides a cellulose fiber reinforced polyacetal resin composition and a molded product thereof.

The cellulose fiber reinforced polyacetal resin composition of the present invention is excellent in rigidity, low specific gravity, low ash content, thermal conductivity, slidability, vibration damping, and related to automobile parts, electrical / electronic parts, sundries, stationery, etc. Suitable for molded products.
BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the polyacetal resin composition of the present invention will be described in detail.

The main components constituting the polyacetal resin composition of the present invention are as described below.
<(A) Polyacetal resin>
The polyacetal resin of component (a) is a polymer compound having an oxymethylene group (—OCH ₂ —) as a main constituent unit, and includes a polyacetal homopolymer consisting essentially only of repeating oxymethylene units, in addition to oxymethylene units. Polyacetal copolymers containing other comonomer units are representative resins. Further, polyacetal resins include copolymers in which a branched structure or a crosslinked structure is introduced by copolymerizing a branch-forming component or a crosslinking-forming component, polymer units composed of repeating oxymethylene groups, and other polymer units. Also included are block copolymers, graft copolymers and the like. These polyacetal resins can be used alone or in combination of two or more.

Generally, a polyacetal homopolymer is produced by polymerization of anhydrous formaldehyde or trioxane (a cyclic trimer of formaldehyde), and is usually stabilized against thermal decomposition by esterifying its terminal.

On the other hand, polyacetal copolymers generally include formaldehyde or a cyclic oligomer of formaldehyde (for example, trioxane) represented by the general formula (CH ₂ O) _n [wherein n represents an integer of 3 or more] It is produced by copolymerizing with a comonomer such as cyclic ether or cyclic formal, and is usually stabilized against thermal decomposition by removing terminal unstable parts by hydrolysis.

Examples of the main raw material of the polyacetal copolymer include trioxane and tetraoxane, and trioxane is usually used.

The comonomer includes a cyclic ether, a glycidyl ether compound, a cyclic formal, a cyclic ester (eg, β-propiolactone), a vinyl compound (eg, styrene, vinyl ether, etc.), and the like.

Examples of the cyclic ether include ethylene oxide, propylene oxide, butylene oxide, cyclohexene oxide, epichlorohydrin, epibromohydrin, styrene oxide, oxetane, 3,3-bis (chloromethyl) oxetane, tetrahydrofuran, trioxepane, 1, Examples include 3-dioxane.

Examples of the glycidyl ether compound include alkyl or aryl glycidyl ethers (for example, methyl glycidyl ether, ethyl glycidyl ether, phenyl glycidyl ether, naphthyl glycidyl ether), alkylene or polyalkylene glycol diglycidyl ether (for example, ethylene glycol diglycidyl ether). , Triethylene glycol diglycidyl ether, butanediol diglycidyl ether), alkyl or aryl glycidyl alcohol, and the like.

Examples of the cyclic formal include 1,3-dioxolane, propylene glycol formal, diethylene glycol formal, triethylene glycol formal, 1,4-butanediol formal, 1,5-pentanediol formal, 1,6-hexanediol formal, and the like. Can be mentioned.

These comonomers can be used alone or in combination of two or more. Of these comonomers, cyclic ethers and / or cyclic formals are usually used, and cyclic ethers such as ethylene oxide, and cyclic formals such as 1,3-dioxolane, 1,4-butanediol formal, and diethylene glycol formal are preferred. .

The proportion of these comonomer (eg, cyclic ether and / or cyclic formal) units is generally in the range of 0.1 to 20% by weight, preferably 0.5 to 20% by weight, based on the total polyacetal resin. %, More preferably about 0.5 to 15% by weight (particularly 1 to 10% by weight).

The melt index of the polyacetal resin as component (a) is not particularly limited, but is preferably in the range of 1 to 100 g / 10 minutes, and particularly preferably in the range of 5 to 50 g / 10 minutes. 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) Cellulose fiber>
As the cellulose fiber (b), a cellulose fiber aggregate is used. Cellulose fiber aggregates are a combination of many cellulose fibers, which may be natural or industrial products, hemp fiber, bamboo fiber, cotton fiber, wood fiber, kenaf fiber, hemp fiber, jute fiber, banana Aggregates such as fibers and coconut fibers can be used.

The shape and size of the cellulose fiber aggregate are not particularly limited, and can be selected as long as the defibrating work can be performed smoothly. Among them, a cellulose fiber aggregate having a preferable shape includes a sheet-shaped pulp sheet. For example, the thickness is 0.1 to 5 mm, preferably 1 to 3 mm, the width is 1 to 50 cm, and the length is 3 to 100 cm. Those having a degree can be preferably used.

When a pulp sheet is used, a pulp sheet rolled into a cylindrical shape, crushed into an elongated plate, or folded into an elongated plate can be used. It is also possible to make the pulp sheet once cut. For example, a strip having a thickness of 0.1 to 5 mm, preferably 1 to 3 mm, a width of 2 mm to 1 cm, a length of about 3 mm to 3 cm, or a rectangular shape having a side of about 2 mm to 1 cm is used. You can also.

The water content of the cellulose fiber aggregate is preferably 20% by weight or less, more preferably 17% by weight or less, and still more preferably 15% by weight or less. When the water content is 20% by weight or less, it is preferable because the temperature rise due to generation of frictional heat is facilitated, and the cellulose fiber aggregate is easily defibrated and no aggregates remain. The moisture content is determined by measuring moisture using the Karl-Fuscher method.

The cellulose fibers forming the cellulose fiber aggregate are preferably those having a high α cellulose content, more preferably 80% by weight or more, still more preferably 85% by weight or more, from the viewpoint of high thermal stability. A weight percent or more is particularly preferred.

The average fiber diameter of the cellulose fibers in the cellulose fiber aggregate is preferably 0.1 to 1000 μm, more preferably 1 to 500 μm, still more preferably 5 to 200 μm, and particularly preferably 10 to 50 μm. The average fiber length of the cellulose fibers is preferably 0.01 to 100 mm, more preferably 0.01 to 50 mm, still more preferably 0.1 to 10 mm, and particularly preferably 0.1 to 5 mm. The aspect ratio (length / diameter) of the cellulose fiber is preferably 2 to 1000, more preferably 3 to 500, still more preferably 5 to 200, and particularly preferably 5 to 100. The cellulose fiber may be surface-treated with a coupling agent (a silane coupling agent having a functional group such as an amino group, a substituted amino group, an epoxy group, or a glycidyl group).

(B) As a method of defibrating the cellulose fiber aggregate used for the cellulose fiber of the component, there may be mentioned a method using an apparatus such as a mixer having a rotating blade or a defibrating machine. For example, the cellulose fiber aggregate can be put into a mixer having rotating blades and fibrillated by stirring at high speed. The mixer only needs to have rotating blades as stirring means, and preferably has heating means. For example, a Henschel mixer manufactured by Mitsui Mining Co., Ltd., FM20C / I (capacity 20 L), ( A Kawata super mixer, SMV-20 (capacity 20 L), etc. can be used.

Rotating blades are usually composed of two blades, upper blades and lower blades, or three blades including upper blades, intermediate blades, and lower blades. It is preferable that the average peripheral speed of the rotating blades during stirring is in the range of 10 to 100 m / sec, more preferably the average peripheral speed is 10 to 90 m / sec, and further the average peripheral speed is 10 to 80 m / sec. It is preferable to do.

For the fibrillation of the cellulose fiber aggregate, for example, it is possible to end the treatment when it can be visually confirmed that the cellulose fiber aggregate has changed into a cotton-like shape. Since the average peripheral speed and stirring time of the rotating blades change depending on the type, shape, size, input amount, and the like of the cellulose fiber aggregate, the time point when it changes into a cotton shape as described above may be used as a reference. Is preferred.

The content of the fibrillated cellulose fiber of the component (b) is 10 to 150 parts by weight, more preferably 15 to 120 parts by weight, with respect to 100 parts by weight of the polyacetal resin of the component (a). If the content is too small or too large, the effects of the present invention cannot be obtained sufficiently, which is not preferable.
<(C) Hindered phenolic antioxidant>
The (c) hindered phenol compound used in the present invention contains a monocyclic hindered phenol compound (eg, 2,6-di-t-butyl-p-cresol), a hydrocarbon group or a sulfur atom. Group-linked polycyclic hindered phenol compounds (eg, 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-tert-butylphenyl) butane, 4,4′-butylidenebis (3-methyl-6-tert-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), etc.) Hindered phenol compounds having an ester group or 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], tri Ethylene 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-methylphenyl 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′-ethylene Bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionamide], N, N′-tetramethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) ) Pionamide], N, N′-hexamethylenebis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionamide], N, N′-ethylenebis [3- (3-t-butyl) -5-methyl-4-hydroxyphenyl) propionamide], N, N'-hexamethylenebis [3- (3-t-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-tert-butyl-4-hydroxybenzyl) isocyanurate, 1,3,5-tris (4-tert-butyl-3-hydroxy-2,6) - Etc. methylbenzyl) isocyanurate) and the like.

In the present invention, the (c) hindered phenol antioxidants 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) polyacetal resin. If the content is too small or too large, the effects of the present invention cannot be obtained sufficiently, which is not preferable.

In preparing the polyacetal resin composition of the present invention, (c) the hindered phenolic antioxidant can be mixed with (a) the polyacetal resin at any stage. Prior to mixing with the fiber, a method in which (c) a hindered phenol antioxidant is previously melt-mixed with (a) polyacetal resin by an extruder or the like is particularly preferable.
<(D) Nitrogen-containing compound>
In the polyacetal resin composition of the present invention, (d) at least one nitrogen-containing compound selected from an aminotriazine compound, a guanamine compound, a hydrazide compound and a polyamide is blended.

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 aralkylenguanamines, 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 the hydrazide compound include aliphatic carboxylic acid hydrazide compounds (such as stearic acid hydrazide, 12-hydroxystearic acid hydrazide, sebacic acid dihydrazide, dodecanedioic acid dihydrazide, and eicosanedioic acid 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 optionally a diamine and / or a dicarboxylic acid; 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 isophthalic acid) and an aliphatic diamine (eg, hexamethylenediamine), a polyamide, and an aliphatic dicarboxylic acid (eg, adipic acid) and an aromatic diamine (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.

(D) The 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) polyacetal resin. If the content is too small or too large, the effects of the present invention cannot be obtained sufficiently, which is not preferable.

In preparing the polyacetal resin composition of the present invention, (d) a nitrogen-containing compound selected from aminotriazine compounds, guanamine compounds, hydrazide compounds and polyamides may be mixed with (a) polyacetal resin at any stage. Although it is possible, (c) Like the hindered phenol antioxidant, (b) Prior to mixing with the cellulose fiber, (d) the nitrogen-containing compound is previously melted into the polyacetal resin (a) with an extruder or the like. A method of mixing is particularly preferable.
<(E) Metal compound>
The polyacetal resin composition of the present invention further contains (e) at least one metal compound selected from alkali metal or alkaline earth metal oxides, hydroxides, inorganic acid salts and carboxylate salts. Can do.

Examples of the alkali metal or alkaline earth metal oxide include CaO, MgO, and ZnO. Examples of the alkali metal or alkaline earth metal hydroxide include LiOH, Ca (OH) ₂ , and Mg (OH) ₂ . Examples of inorganic acid salts of alkali metals or alkaline earth metals include carbonates (Li ₂ CO ₃ , Na ₂ CO ₃ , K ₂ CO ₃ , CaCO ₃ , MgCO _3, etc.), borates, phosphates, and the like. .

Organic carboxylic acids that form carboxylates with alkali metals or alkaline earth metals include saturated monocarboxylic acids (acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, isovaleric acid, pivalic acid, caproic acid, Caprylic acid, etc.), saturated dicarboxylic acids (oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, corkic acid, azelaic acid, etc.) and oxyacids thereof (glycolic acid, lactic acid, glyceric acid, hydroxy) Butyric acid, citric acid, etc.), unsaturated monocarboxylic acids [(meth) acrylic acid, crotonic acid, isocrotonic acid, etc.], unsaturated dicarboxylic acids (maleic acid, fumaric acid, etc.), and oxyacids thereof (propiolic acid, etc.) , Polymerizable unsaturated carboxylic acids [polymerizable unsaturated monocarboxylic acids such as (meth) acrylic acid, polymerizable unsaturated poly Copolymerization of carboxylic acids (such as itaconic acid, maleic acid and fumaric acid), polyhydric carboxylic acid anhydrides or monoesters (such as monoalkyl esters such as monoethyl maleate)] and olefins (such as ethylene and propylene) Examples of carboxylic acid metal salts formed include alkali metal organic carboxylates (lithium citrate, potassium citrate, sodium citrate, lithium stearate, lithium 12-hydroxystearate, etc.), alkaline earth Metal organic carboxylates (magnesium acetate, calcium acetate, magnesium citrate, calcium citrate, calcium stearate, magnesium stearate, 12-hydroxy magnesium stearate, 12-hydroxy calcium stearate, etc.), Io Mer resins and the like (at least part of the polymerizable unsaturated polycarboxylic acid and carboxyl groups contained in the copolymer of olefin resins which are neutralized by the metal ions).

Among these (e) metal compounds, alkaline earth metal oxides, hydroxides, carbonates and carboxylates are particularly preferred.

These metal compounds selected from (e) alkali metal or alkaline earth metal oxides, hydroxides, inorganic acid salts and carboxylates can be used alone or in combination of two or more.

The preferable blending ratio is 0.01 to 3 parts by weight, particularly preferably 0.02 to 1 part by weight, based on 100 parts by weight of the (a) polyacetal resin. When the content is too small, (e) the effect on the heat resistance stability due to the compounding of the metal compound is not sufficiently exhibited. On the other hand, when the content is excessive, the characteristics such as rigidity intended by the present invention may be impaired. This is not preferable. In the present invention, when the (e) metal compound is blended, the (e) metal compound can be mixed with the (a) polyacetal resin at any stage, but (b) for mixing with the cellulose fiber. A method in which (e) a metal compound is previously melt-mixed with (a) polyacetal resin by an extruder or the like in advance is particularly preferable.
<(F) Processing aid>
The polyacetal resin composition of the present invention may further contain (f) at least one compound selected from long-chain fatty acids, long-chain fatty acid derivatives, polyoxyalkylene glycols and silicone compounds as processing aids. .

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.

Long chain fatty acid derivatives 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, glycerin mono-tribehenic acid ester, glycerin mono-trimontanic acid ester, pentaerythritol mono-tetrapalmitic acid ester, pentaerythritol mono-tetrastearic acid ester, pentaerythritol mono-tetratetrahenic acid ester, pentaerythritol mono-ester To tetramontanic acid ester, polyglyceryl tristearate, tri Tyrolpropane 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 diolate, mono or dilinoleate, etc. are 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 Jieruka 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 may be exemplified.

Examples of the polyoxyalkylene glycol include homo- or copolymers of alkylene glycol (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 .

The silicone compound includes (poly) organosiloxane and the like. 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, a hydroxyl group, an alkoxy group, a carboxyl group, an amino group or a substituted amino group (such as a dialkylamino group), an ether group, a vinyl group, ) Modified (poly) organosiloxane having a substituent such as acryloyl group is also included.

In the present invention, when (f) a processing aid is blended, compounds selected from the above-mentioned long chain fatty acids, derivatives of long chain fatty acids, polyoxyalkylene glycols and silicone compounds can be used alone or in combination of two or more. The preferable blending ratio is 0.01 to 3 parts by weight, particularly preferably 0.02 to 1 part by weight based on 100 parts by weight of the (a) polyacetal resin. When the content is too small, the effect as a processing aid cannot be obtained. Conversely, when the content is too large, the processability may be impaired, or the effect originally intended by the present invention may be impaired.

In the present invention, when the (f) processing aid is blended, the (f) processing aid can be mixed with the (a) polyacetal resin at any stage, but the (b) cellulose fiber Prior to mixing, a method in which (f) a processing aid is melt-mixed in advance with an extruder or the like in (a) polyacetal resin is particularly preferable.
<(G) Sliding property improving agent>
The polyacetal resin composition of the present invention further includes a modified olefin polymer, primary or secondary amino modified with at least one selected from the group consisting of unsaturated carboxylic acids and acid anhydrides and derivatives thereof. A compound selected from an alkylene glycol polymer having a group, an α-olefin oligomer, a surface-treated inorganic filler, and the like can be blended as a sliding property improving agent. The long-chain fatty acids, derivatives of long-chain fatty acids, polyoxyalkylene glycols, and silicone compounds described above also have a slidability improving function and can be blended as a slidability improving agent.
A modified olefin polymer modified with at least one selected from the group consisting of an unsaturated carboxylic acid and its acid anhydride and derivatives thereof, an olefin polymer is converted into an unsaturated carboxylic acid and its acid anhydride and their This is a general term for those modified with at least one selected from the group consisting of derivatives. Examples of the olefin polymer used here include single weights of α-olefins such as ethylene, propylene, 1-butene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-dodecene and the like. Copolymers, copolymers composed of two or more of these, and α-olefins thereof and α, β-unsaturated acids such as acrylic acid and methacrylic acid or methyl acrylate, ethyl acrylate, propyl acrylate, acrylic Α, β-unsaturated carboxylic acid esters such as butyl acrylate, 2-ethylhexyl acrylate, hydroxyethyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, hydroxyethyl methacrylate,
Non-conjugated dienes such as 1,4-hexadiene, dicyclopentadiene, 5-ethylidene-2-norbornene and 2,5-norbonadiene, conjugated diene components such as butadiene, isoprene and piperylene, and aromatic vinyl compounds such as α-methylstyrene And random, block or graft copolymers comprising at least one of comonomer components such as vinyl ethers such as vinyl methyl ether and derivatives of these vinyl compounds.
The modified olefin copolymer is obtained by modifying the olefin polymer with at least one selected from the group consisting of unsaturated carboxylic acids, acid anhydrides and derivatives thereof. Specific examples of preferred modified olefin copolymers include polyethylene, polypropylene, ethylene-propylene copolymer, ethylene ethyl acrylate copolymer, ethylene methyl acrylate copolymer, ethylene methacrylic acid modified with maleic anhydride. Examples thereof include an ethyl copolymer and an ethylene methyl methacrylate copolymer.
The alkylene glycol polymer having a primary or secondary amino group is a homopolymer or copolymer of ethylene glycol, propylene glycol, or tetramethylene glycol, and has a primary or secondary amino group in the terminal or molecular chain. It is a polymer having. Further, it may be a polymer having some modification such as forming an ester with a fatty acid or an ether with an aliphatic alcohol. Examples thereof include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and copolymers composed of these structural units and having at least one aminopropyl group and aminooctyl group.
The α-olefin oligomer mainly includes aliphatic hydrocarbons having a structure in which a C6 to C20 α-olefin is used alone or ethylene and a C3 to C20 α-olefin are copolymerized.
As the surface-treated inorganic filler, at least one selected from calcium carbonate, potassium titanate, barium carbonate, talc, wollastonite, mica, zinc oxide and the like is subjected to surface treatment with a fatty acid ester, a silane compound, or the like. Those subjected to surface treatment are preferably used, and more preferably, at least one selected from calcium carbonate, potassium titanate, barium carbonate and zinc oxide is subjected to a surface treatment with a fatty acid ester. Such an inorganic filler does not depend on the shape such as the particle shape, fiber shape, aspect ratio, and the like, and any inorganic filler can be used as long as it is included in the group.
In the present invention, when (g) a slidability improving agent is blended, a modified olefin polymer modified with at least one selected from the group consisting of the unsaturated carboxylic acid and its acid anhydride and derivatives thereof, A compound selected from an alkylene glycol polymer having a primary or secondary amino group, an α-olefin oligomer, an inorganic filler subjected to surface treatment, and the like can be used alone or in combination of two or more. The preferable blending ratio is 0.01 to 10 parts by weight, particularly preferably 0.02 to 8 parts by weight, based on 100 parts by weight of the (a) polyacetal resin.
In the present invention, when (g) the slidability improving agent is blended, (g) the slidability improving agent can be mixed with (a) the polyacetal resin at any stage, but (b) Prior to mixing with cellulose fibers, a method in which (g) a sliding property improving agent is melt-mixed in advance with (a) polyacetal resin by an extruder or the like is particularly preferable.
<Preparation method of polyacetal resin composition>
The polyacetal resin composition of the present invention comprises (b) 10 to 150 parts by weight of fibrillated cellulose fibers and (c) a hindered phenol-based antioxidant in an amount of 0.1 to 100 parts by weight of the above-mentioned (a) polyacetal resin. By adding 0.01 to 3 parts by weight of (d) at least one nitrogen-containing compound selected from (d) aminotriazine compounds, guanamine compounds, hydrazide compounds and polyamides, it is preferable that (e) ) 0.01-3 parts by weight of at least one metal compound selected from oxides, hydroxides, inorganic acid salts and carboxylates of alkali metals or alkaline earth metals, and / or (f) long chains At least one processing aid selected from fatty acids, derivatives of long chain fatty acids, polyoxyalkylene glycols and silicone compounds 0.0 To 3 parts by weight, and / or is prepared by containing a (g) sliding property improving agent 0.01-10 parts by weight.

In the present invention, the specific embodiment of the method for preparing the polyacetal resin composition is not particularly limited, and can be generally prepared by a known equipment and method as a method for preparing a synthetic resin composition or a molded product thereof. That is, necessary components can be mixed and kneaded using a single or twin screw extruder or other melt kneader to prepare pellets for molding. A plurality of extruders or other melt kneaders may be used.

In preparing the polyacetal resin composition of the present invention, (b) compounding components other than cellulose fibers, that is, (c) hindered phenol-based antioxidant, (d) nitrogen-containing compound, (e) metal compound which is a preferred compounding component (F) One or more selected from (f) processing aids and (g) slidability improvers are previously melt-mixed in (a) polyacetal resin, and then this molten mixture is (b) The method of preparing the target composition by mixing with cellulose fibers and the remaining components constituting the composition, and melt-kneading is particularly preferred.

As a method for preparing the polyacetal resin composition of the present invention, the cellulose fiber aggregate is defibrated in a mixer having rotating blades, and (b) the polyacetal resin and other components are added to the defibrated cellulose fiber. A method of additionally adding and mixing, defibrating the cellulose fiber aggregate with a mixer or defibrator having a rotating blade, (b) transferring the defibrated cellulose fiber to another mixer, (a) polyacetal resin and other Examples thereof include a method of adding and mixing the components, or a method of mixing (b) the fibrillated cellulose fiber, (a) the polyacetal resin and other components with an extruder.

Among these, from the viewpoint of the effect, workability and economy of the present invention, in particular, (b) polyacetal resin and other components are additionally added to and mixed with cellulose fiber (b) defibrated in a mixer having rotating blades. Is preferred. In the above method, the cellulose fiber aggregate is defibrated in a mixer, and a required amount of (a) polyacetal resin and other components are added thereto and stirred at a high speed, whereby frictional heat is generated and the inside of the mixer is Since the temperature is raised, the polyacetal resin melts and adheres to the fibrillated cellulose fibers, so that a mixture of the cellulose fibers, the polyacetal resin and other components can be obtained directly.

(B) In the case where (a) polyacetal resin and other components are additionally added to the fibrillated cellulose fiber and mixed, it is preferable that the average peripheral speed of the rotating blades during stirring is in the range of 10 to 100 m / sec. More preferably, the stirring is carried out at an average peripheral speed of 10 to 90 m / sec, and more preferably at an average peripheral speed of 10 to 80 m / sec. If stirring is continued, the temperature in the mixer rises and the power of the motor rises. It is preferable to reduce the rotational speed by gradually or rapidly decelerating the stirring speed according to the increase in power and the temperature in the mixer so that the average peripheral speed falls within the above range. Moreover, in order to assist the temperature rise in the mixer and facilitate the production of a mixture of cellulose fibers and polyacetal resin, the mixer can be heated by a heating means.

Further, the obtained mixture can be solidified by cooling. Examples of the cooling method include a method of cooling in the mixer, a method of discharging the mixture to another mixer connected to the mixer, and a method of cooling. In particular, a method in which the mixture is discharged to another mixer connected to the mixer and cooled while stirring is preferable. It is preferable to stir in the range of the average peripheral speed of the rotating blades during cooling in the range of 1 to 30 m / second, more preferably the average peripheral speed is 2 to 25 m / second, and still more preferably the average peripheral speed is 3 to 25 m / second. Stir.

By such treatment, a polyacetal resin composition containing (a) polyacetal resin and (b) fibrillated cellulose fiber and other components is obtained. The obtained composition can be used as it is, but can also be used after granulation with a pulverizer and / or melt kneading and granulation with an extruder or the like.

In preparation of the polyacetal resin composition of the present invention, a substance that improves the adhesion between (a) the polyacetal resin and (b) the fibrillated cellulose fiber can be used. Here, as a substance for improving adhesion, an isocyanate compound represented by the general formula O = C = NRN = C = O (R: divalent group), S = C = NRN = C = S
Isothiocyanate compounds represented by (R: divalent group), and their modified isocyanate compounds, thermoplastic polyurethane resins, polymers of acid anhydrides of α, β-monoolefinic unsaturated carboxylic acids and copolymers Examples include coalescence.

Examples of isocyanate compounds include 4,4'-methylenebis (phenylisocyanate), 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, xylene diisocyanate, 1,6-hexamethylene diisocyanate, isophorone diisocyanate, 1, 5-Naphthalene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, and as an example of an isothiothionate compound, diisothionate corresponding to the above isocyanate compound is used as a modified product. These include dimers and trimers of these isocyanate compounds or isothiocyanate compounds, and compounds in which the isocyanate group is protected in some form, and these are all effective. However, in consideration of various properties such as discoloration such as melting treatment or safety in handling, 4,4′-methylenebis (phenyl isocyanate), isophorone diisocyanate, 1,5
-Naphthalene diisocyanate, 1,6-hexamethylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate and modified products (or derivatives) such as dimers and trimers thereof are preferred.

Examples of the thermoplastic polyurethane resin include (i) a diisocyanate compound, (ii) a high molecular weight polyol having a molecular weight of 500 to 5000, and (iii) a low molecular weight polyol having a molecular weight of 60 to 500 and / or a polyamine. Reaction products to be used.

Further, examples of acid anhydride polymers and copolymers of α, β-monoolefinic unsaturated carboxylic acids include polymers of unsaturated carboxylic acid anhydrides such as maleic anhydride, styrene monomers Copolymer (eg, styrene, vinyltoluene, α-methylstyrene, chlorostyrene, etc.) and an anhydride of an unsaturated carboxylic acid such as maleic anhydride, ethylene and / or propylene monomer, etc. And a copolymer with an anhydride of an unsaturated carboxylic acid such as maleic acid.

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.

Further, the above-mentioned stabilizers, additives and the like may be added at any stage, for example, (a) once added to the polyacetal resin or at the time of adjusting the resin composition, or immediately before obtaining the final molded product. It is also possible to add and mix.
<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. 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, parts or members of toys, 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.
Example

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.
In addition, the detail of the component and test method which were used in the Example and the comparative example is as follows.
[Use ingredients]
(A) Polyacetal resin: manufactured by Polyplastics Co., Ltd. (a-1) Melt index = 9 g / 10 min (a-2) Melt index = 27 g / 10 min (a-3) Melt index = 45 g / 10 min ( b) Cellulose fiber aggregate (used after defibration)
(B-1) Wood pulp sheet (manufactured by Nippon Paper Group)
(C) Hindered phenol antioxidant (c-1) Pentaerythritol tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate]
(D) Nitrogen-containing compound (d-1) Melamine (e) Metal compound (e-1) 12-hydroxycalcium stearate (e-2) Calcium stearate (e-3) Magnesium oxide (e-4) Zinc oxide (e -5) Calcium carbonate (f) Processing aid (f-1) Ethylene bisstearylamide (f-2) Glycerin monostearate (g) Sliding property improver (g-1) Amine-modified polyethylene glycol (g-2) ) Maleic anhydride modified polyolefin (g-3) Ethylene propylene copolymer (g-4) Calcium carbonate surface-treated with fatty acid ester [Test method]
(1) Rigidity (flexural modulus)
The flexural modulus (MPa) was measured according to ISO178.
(2) Specific gravity The specific gravity was calculated from the volume of the test piece (measured by the increase in immersion in water) and the weight of the test piece.
(3) Ash content The sample put in the crucible was burned in an electric furnace at 600 ° C. for 2 hours, and the ash content (wt%) after combustion was measured.
(4) Thermal conductivity (thermal conductivity)
The thermal conductivity (W / m · K) was measured by a hot disk method. A higher thermal conductivity indicates better thermal conductivity.
(5) Sliding property (amount of wear)
In accordance with JIS K7218, using a rotary friction and wear tester, a hollow cylindrical test piece designated by the method A of the same standard was slid with steel (S45C), and the amount of wear (g) of S45C was measured. The test was performed under the conditions that the resin side was fixed, the S45C side was rotated, the rotational speed was 150 rpm, the load was 20 kgf, and the test time was 24 hours. For Example 23 and Comparative Example 5, the test was performed at a rotational speed of 300 rpm, and the friction coefficient between the resin side and S45C, the wear amount (g) of S45C, and the wear amount (g) on the resin side were measured. . The lower the coefficient of friction and the smaller the amount of wear, the better the slidability.
(6) Vibration control (loss factor)
The loss factor (%) at a frequency of 1 × 102 Hz was measured based on the JIS G0602 center support steady excitation method. A higher loss factor indicates better vibration damping.

Examples 1-7
In advance, (a) polyacetal resin was added to (c) hindered phenol antioxidant, (d) nitrogen-containing compound, (e) metal compound, and (f) processing aid in the proportions of Examples 1 to 7 in Table 1. They were mixed and melt-kneaded with an extruder to prepare (b) polyacetal resin compositions containing components other than cellulose fibers.

A heater mixer (with heater and thermometer, capacity 200 L) having rotating blades was heated to 100 ° C. or higher, (b) a cellulose fiber aggregate (wood pulp sheet) was added, and stirred at an average peripheral speed of 50 m / sec. . At about 2 minutes, the cellulose fibers changed to cotton.

Subsequently, the polyacetal resin composition prepared in advance from the hopper in the heater mixer was put into the mixer and stirred at an average peripheral speed of 50 m / sec. The mixer temperature rose to 160-190 ° C., and stirring was continued in this state.

After that, the average peripheral speed was lowered to a low speed of 25 m / sec and stirring was continued, and then the outlet of the mixer was opened and connected to a cooling mixer [with water cooling means and thermometer by cooling water (20 ° C.), capacity 500 L] Then, the mixture was discharged and stirred at an average peripheral speed of 10 m / sec in a cooling mixer for cooling. Thereafter, the mixture was solidified to obtain a solidified product.

The solidified product was pulverized with a pulverizer and then melt-kneaded with an extruder to prepare a pellet-like cellulose fiber reinforced polyacetal resin composition. Using the obtained pellets, a predetermined test piece was molded by an injection molding machine and subjected to test evaluation. The results are shown in Table 1.

Comparative Example 1
(B) A polyacetal resin composition containing no cellulose fibers (mixed by melt mixing with an extruder in the composition of Comparative Example 1 in Table 1) was evaluated in the same manner as in the Examples. In Comparative Example 1, when the polyacetal resin (a-1) was replaced with (a-2) or (a-3), no substantial difference in physical properties occurred. The results are shown in Table 1. From the comparison of the results in Table 1, the cellulose fiber reinforced polyacetal resin composition of the present invention has rigidity (bending elastic modulus) and thermal conductivity while suppressing an increase in specific gravity / ash content and a decrease in sliding / vibration damping properties. It turns out that it is improving significantly rather than the non-reinforced polyacetal resin composition (comparative example 1).

Comparative Examples 2-3
Conventionally, polyacetal resin compositions containing glass fibers that have been used as means for improving strength and rigidity were prepared and evaluated. The prepared compositions are as shown in Comparative Examples 2 and 3 in Table 1, and (b′-2) alumina borosilicate E glass was used as the glass fiber. In the comparative example 3, it was set as the composition which considered stability and workability at the time of mix | blending glass fiber. The results are shown in Table 1. By comparing the examples shown in Table 1 with Comparative Examples 2 to 3 (and Comparative Example 1), the cellulose fiber reinforced polyacetal resin composition of the present invention is a glass fiber reinforced polyacetal resin composition (Comparative Examples 2 to 3). It can be seen that this is extremely effective as means for improving rigidity and thermal conductivity without causing an increase in specific gravity, ash content, and a decrease in slidability and vibration damping.

Comparative Example 4
In advance, (a) a polyacetal resin was mixed with (c) a hindered phenol antioxidant, (d) a nitrogen-containing compound, (e) a metal compound, and (f) a processing aid in the ratio of Comparative Example 4 in Table 1. (B) A polyacetal resin composition containing no cellulose fiber was prepared by melt kneading with an extruder.

The polyacetal resin composition and undefibrated (b) cellulose fiber aggregate (wood pulp sheet) were melt-mixed in a small kneader-type melt kneader (labor plast mill, manufactured by Toyo Seiki Co., Ltd.). Since poor dispersion of cellulose fibers was observed in the polyacetal resin, the subsequent evaluation was not performed.

Examples 8-11
(A) A polyacetal resin was mixed with (c) a hindered phenolic antioxidant, (d) a nitrogen-containing compound, and (f) a processing aid in the proportions of Examples 8 to 11 in Table 2, and melt-kneaded with an extruder. Thus, (b) polyacetal resin compositions containing components other than cellulose fibers were prepared.
Subsequently, in the same manner as in Example 1, (b) the cellulose fiber aggregate (wood pulp sheet) was put into a heater mixer having rotating blades, and after the cellulose fibers changed to cotton, the polyacetal prepared in advance The resin composition was put into a heater mixer from a hopper, and after stirring, the mixture was discharged into a connected cooling mixer and cooled to obtain a solidified product. Further, the solidified product was pulverized with a pulverizer and then melt-kneaded with an extruder to prepare a pellet-like cellulose fiber reinforced polyacetal resin composition. Using the obtained pellets, a predetermined test piece was molded by an injection molding machine and subjected to test evaluation. The results of rigidity (flexural modulus) are shown in Table 2.

Examples 12-22
Polyacetal prepared in advance after (b) cellulose fiber aggregate (wood pulp sheet) was put into a heater mixer having rotating blades with the same composition as in Example 11 and the cellulose fibers changed to cotton-like. The resin composition was put into a heater mixer from a hopper, and after stirring, the mixture was discharged into a connected cooling mixer and cooled to obtain a solidified product. Further, the solidified product was pulverized with a pulverizer.
Subsequently, additional components shown in Examples 12 to 22 were added to the obtained pulverized product in a predetermined composition, and melt-kneaded with an extruder to prepare a pellet-like cellulose fiber reinforced polyacetal resin composition. . Using the obtained pellets, a predetermined test piece was molded by an injection molding machine and subjected to test evaluation. As the results of stiffness (flexural modulus) are shown in Tables 2-3, there was no effect on stiffness. On the other hand, it was confirmed by the sensory test that the generation of formaldehyde at the time of melt processing such as molding is reduced as compared with the case where no additional component is added.

Example 23
(A) Implementation of (c) hindered phenolic antioxidant, (d) nitrogen-containing compound, (e) metal compound, (f) processing aid, (g) slidability improver on polyacetal resin in Table 4 They were mixed in the ratio of Example 23 and melt-kneaded with an extruder to prepare (b) polyacetal resin compositions containing components other than cellulose fibers.
Subsequently, in the same manner as in Example 1, (b) the cellulose fiber aggregate (wood pulp sheet) was put into a heater mixer having rotating blades, and after the cellulose fibers changed to cotton, the polyacetal prepared in advance The resin composition was put into a heater mixer from a hopper, and after stirring, the mixture was discharged into a connected cooling mixer and cooled to obtain a solidified product. Further, the solidified product was pulverized with a pulverizer and then melt-kneaded with an extruder to prepare a pellet-like cellulose fiber reinforced polyacetal resin composition. Using the obtained pellets, a predetermined test piece was molded by an injection molding machine and subjected to test evaluation. The results are shown in Table 4.

Comparative Example 5
(B) A polyacetal resin composition containing no cellulose fiber (mixed by melt mixing with an extruder in the composition of Comparative Example 5 in Table 4) was evaluated in the same manner as in Example 23. The results are shown in Table 4. From the comparison of the results shown in Table 4, the cellulose fiber-reinforced polyacetal resin composition of the present invention has improved rigidity (flexural modulus) while suppressing a decrease in slidability (a significant increase in friction coefficient and wear amount). I understand that. In particular, it can be seen that the slidability is maintained at a constant level even under high rotation conditions.

Claims

(A) For 100 parts by weight of the polyacetal resin,
(B) 10 to 150 parts by weight of fibrillated cellulose fiber,
(C) 0.01 to 3 parts by weight of a hindered phenolic antioxidant and (d) 0.01 to 3 parts by weight of at least one nitrogen-containing compound selected from aminotriazine compounds, guanamine compounds, hydrazide compounds and polyamides. Cellulose fiber reinforced polyacetal resin composition to be contained.
(B) The cellulose fiber reinforced polyacetal resin composition according to claim 1, wherein the fibrillated cellulose fiber is obtained by defibrating the cellulose fiber aggregate with a mixer having a rotating blade or a defibrator.
And (e) 0.01 to 3 parts by weight of at least one metal compound selected from oxides, hydroxides, inorganic acid salts and carboxylates of alkali metals or alkaline earth metals. Item 3. The cellulose fiber-reinforced polyacetal resin composition according to Item 1 or 2.
Further, (f) 0.01 to 3 parts by weight of at least one processing aid selected from long chain fatty acids, derivatives of long chain fatty acids, polyoxyalkylene glycols and silicone compounds is contained. The cellulose fiber reinforced polyacetal resin composition according to any one of the above.
Further, (g) a modified olefin polymer modified with at least one selected from the group consisting of unsaturated carboxylic acids and acid anhydrides and derivatives thereof, alkylene glycol-based polymers having primary or secondary amino groups. 5. The method according to claim 1, further comprising 0.01 to 10 parts by weight of at least one sliding property improving agent selected from a coalescence, an α-olefin oligomer, and a surface-treated inorganic filler. Cellulose fiber reinforced polyacetal resin composition.
6. The composition according to any one of claims 1 to 5, wherein one or two or more selected from compounding components other than (b) cellulose fibers are previously blended by being melt-mixed with (a) polyacetal resin. Cellulose fiber reinforced polyacetal resin composition.
The cellulose fiber reinforced polyacetal resin composition according to any one of claims 1 to 6, wherein the melt index (according to ASTM-D1238, 190 ° C, 2.16 kgf) of the polyacetal resin is 5 to 50 g / 10 min. object.
A molded article obtained by molding the cellulose fiber-reinforced polyacetal resin composition according to any one of claims 1 to 7.