JP5435629B2 - Method for producing polyoxymethylene resin composition - Google Patents

Description

  The present invention relates to a method for producing a polyoxymethylene resin composition that significantly reduces the amount of formaldehyde released, has excellent impact properties, and has excellent resistance to discoloration during molding residence.

Polyoxymethylene resin has an excellent balance of mechanical strength, chemical resistance and slidability, and its processability is easy, so it covers a wide range of electrical equipment, its mechanical parts, automotive parts and other mechanical parts. It is used.
In recent years, in the field of polyoxymethylene resins, there has been an increasing demand for miniaturization, thinning, and precision of molded products. Molding with pin gate molds, high cycle molding, or miniaturization using high-viscosity polyoxymethylene resins. Thin-walled and precision parts are being molded. In these moldings, in order to increase the shear rate and shorten the plasticizing time, the screw rotation speed and the molding temperature are often increased, and the polyoxymethylene resin is subject to a higher thermal history than conventional molding. Become. Even in general molding, when molding defects such as flow marks, weld lines, jetting, etc. occur, it is often the case that the resin temperature is raised, which also causes a thermal history. In addition, when a hot runner is used for the mold, the resin temperature rises due to partial stagnation of the resin, which contributes to the decomposition of the resin.

When polyoxymethylene resin is subjected to a thermal history, thermal decomposition, auto-oxidative decomposition, acid / alkali decomposition, main chain decomposition due to residual active catalyst, etc. are likely to occur, and the amount of formaldehyde released increases. Yes. Depending on the residence time at the time of molding, there is also a problem of a decrease in thermal stability, resulting in discoloration, a decrease in strength, and a decrease in impact properties.
In recent years, in the field of automobile interior parts, there has been an increasing demand for reducing the amount of volatile organic compounds (VOC) containing formaldehyde. However, since the polyoxymethylene resin which has received the heat history as described above easily releases formaldehyde due to decomposition of the main chain, it has been difficult to sufficiently satisfy the requirement for reducing the amount of release.

  Various methods have been proposed as means for reducing formaldehyde emission from polyoxymethylene resins. For example, addition of polyamide and hydrazine derivative (Patent Document 1), addition of hydrazide compound (Patent Document 2), addition of nitrogen compound selected from melamine and melamine derivatives and dicarboxylic acid hydrazide (Patent Document 3), addition of benzoguanamine ( Patent Document 4), a method of attaching a fatty acid partial ester of a polyhydric alcohol compound to the pellet surface (Patent Document 5), addition of mono N-substituted urea (Patent Document 6), and acid dissociation index of 3. Addition of 6 or more carboxyl group-containing compounds (Patent Document 7), addition of condensates of phenols, basic nitrogen-containing compounds and aldehydes (Patent Document 8), addition of hydantoin or imidazole (Patent Document 9), base The addition of a low molecular weight amino compound having a dissociation index of 2 to 8 (Patent Document 10) and the addition of a spiro compound having a triazine ring (Patent Document 11) have been proposed.

Japanese Patent Laid-Open No. 51-111857 JP-A-4-345648 JP-A-7-173369 JP-A-62-190248 JP-A-6-107900 JP-A-11-335519 JP 2000-239484 A JP 2002-212384 A JP-A-8-41288 International Publication No. 00/59993 Pamphlet US Pat. No. 6,673,405

On the other hand, a filler such as an inorganic filler is added to the polyoxymethylene resin for the purpose of improving rigidity. In that case, the addition of the filler not only causes an increase in the resin temperature, but also the decomposition of the polyoxymethylene resin by acid / alkali tends to occur due to the influence of the surface treatment agent of the filler. As a result, there was a problem that the amount of formaldehyde released from the polyoxymethylene resin increased compared to when no filler was added.
In the production methods disclosed in Patent Documents 1 to 11, all of the components are mixed and then melt-kneaded in a single stage using a single-screw or twin-screw extruder, and a polyoxymethylene containing a filler is used. In reducing the amount of formaldehyde released from the resin composition, it was not satisfactory.
Therefore, the problem to be solved by the present invention is not only to significantly reduce the amount of formaldehyde released from the polyoxymethylene resin composition containing a filler such as an inorganic filler, but also to polyoxymethylene having excellent impact and thermal discoloration. It is providing the manufacturing method of a methylene resin composition.

  As a result of intensive studies to achieve the above-mentioned problems, the present inventors have melt-kneaded the polyoxymethylene resin in advance to obtain a molten state, and then supply the hydrazide compound and filler from the side feed port to perform melt-kneading. Compared with the conventional method in which polyoxymethylene resin, hydrazide compound and filler are fed together and melt-kneaded, the amount of formaldehyde released is remarkably reduced, and impact and thermal discoloration such as Charpy impact strength and repeated impact strength are further reduced. The present inventors have found that an excellent resin composition can be obtained and completed the present invention. That is, the present invention is as follows.

[1] A method for producing a polyoxymethylene resin composition comprising (A) a polyoxymethylene resin, (B) a hydrazide compound, and (C) a filler, comprising: ( A) a polyoxymethylene resin; and (B) a hydrazide The compounding ratio of the compound and (C) filler is (A) polyoxymethylene resin 50 to 99 parts by mass, (C) filler 1 to 50 parts by mass, (A) polyoxymethylene resin and (C) filling (B) Extruder equipped with a screw configuration having 0.01 to 5 parts by mass of a hydrazide compound and a kneading zone having a kneading disk as an essential component with respect to 100 parts by mass of the total material The (A) polyoxymethylene resin is fed into the barrel from the main feed port of the extruder and melted in the melting zone, and then (B) the hydrazide compound and (C) filler are side-loaded. A method for producing a polyoxymethylene resin composition characterized by being fed from the same position of a feed port, kneaded in a kneading zone, and continuously extruded from a die of an extruder while degassing from a vent port.
[2] Both the melting zone and the kneading zone include a kneading disk, and the kneading disk has a structure in which the disks are alternately crossed with each other. On the other hand, it is the range of 0.3-2.0, The manufacturing method of the polyoxymethylene resin composition of Claim 1.
[3] The method for producing a polyoxymethylene resin composition according to the above 1 or 2, wherein the (B) hydrazide compound is represented by the following general formula (1).

_{H 2 NNHCO-R 1 -CONHNH 2} (1)
(Wherein R ₁ represents a hydrocarbon having 1 to 20 carbon atoms)

[4] The method for producing a polyoxymethylene resin composition according to any one of the above 1 to 3, wherein the filler (C) is at least one filler selected from fibrous, particulate, and plate-like fillers. .

  According to the present invention, it is possible to provide a polyoxymethylene resin composition that significantly reduces the amount of formaldehyde released and is excellent in impact properties and thermal discoloration.

Schematic diagram of the extruder employed in production method A employed in the examples Schematic diagram of the extruder employed in production method B employed in the examples Schematic diagram of the extruder employed in production method C employed in the examples Schematic diagram of the extruder employed in production method D employed in the examples

Hereinafter, the present invention will be specifically described.
(A) The polyoxymethylene resin consists essentially of oxymethylene units obtained by homopolymerizing formaldehyde monomers or cyclic oligomers of formaldehyde such as trimers (trioxane) and tetramers (tetraoxane). Cyclic oligomers of formaldehyde such as polyoxymethylene homopolymers, formaldehyde monomers or their trimers (trioxane) and tetramers (tetraoxane), ethylene oxide, propylene oxide, epichlorohydrin, 1,3-dioxolane and 1,4 -Representative examples include polyoxymethylene copolymers obtained by copolymerizing glycols such as butanediol formal, cyclic ethers such as cyclic formal of diglycol, and cyclic formal. Moreover, the polyoxymethylene copolymer which has a branch obtained by copolymerizing monofunctional glycidyl ether, and the polyoxymethylene copolymer which has a crosslinked structure obtained by copolymerizing polyfunctional glycidyl ether can also be used.

Further, a polyoxymethylene homopolymer having a block component obtained by polymerizing a formaldehyde monomer or a cyclic oligomer of formaldehyde in the presence of a compound having a functional group such as a hydroxyl group at both ends or one end, for example, polyalkylene glycol, In the presence of a compound having a functional group such as a hydroxyl group at both ends or one end, for example, hydrogenated polybutadiene glycol, formaldehyde monomer or cyclic formaldehyde such as trimer (trioxane) or tetramer (tetraoxane). A polyoxymethylene copolymer having a block component obtained by copolymerizing an oligomer with cyclic ether or cyclic formal can also be used. As described above, in the present invention, both polyoxymethylene homopolymers and copolymers can be used. Preference is given to polyoxymethylene copolymers.
In general, the amount of comonomer such as 1,3-dioxolane is preferably 0.1 to 60 mol%, more preferably 0.1 to 20 mol%, still more preferably 0.13 to 10 mol% with respect to 1 mol of trioxane. .

  As the polymerization catalyst in the polymerization of the polyoxymethylene copolymer, a cationically active catalyst such as a Lewis acid, a protonic acid and an ester or anhydride thereof is preferable. Examples of the Lewis acid include boric acid, tin, titanium, phosphorus, arsenic and antimony halides. Specifically, boron trifluoride, tin tetrachloride, titanium tetrachloride, phosphorus pentafluoride, pentachloride. Examples thereof include phosphorus, antimony pentafluoride, and complex compounds or salts thereof. Specific examples of the protonic acid, its ester or anhydride include perchloric acid, trifluoromethanesulfonic acid, perchloric acid-tertiary butyl ester, acetyl perchlorate, trimethyloxonium hexafluorophosphate, and the like. Among these, boron trifluoride; boron trifluoride hydrate; and a coordination complex compound of an organic compound containing an oxygen atom or a sulfur atom and boron trifluoride are preferable. Specifically, boron trifluoride diethyl ether is used. Boron trifluoride di-n-butyl ether can be mentioned as a preferred example.

The polymerization method of the polyoxymethylene copolymer is generally carried out by bulk polymerization, and can be either batch type or continuous type. As a polymerization apparatus to be used, a self-cleaning type extrusion kneader such as a kneader, a twin-screw continuous extrusion kneader, or a twin-screw paddle type continuous mixer is used, and a molten monomer is supplied to the polymerization machine. A solid lump polyoxymethylene copolymer is obtained as the polymerization proceeds.
Since the polyoxymethylene copolymer obtained by the polymerization method described above has a thermally unstable terminal [-(OCH ₂ ) _n —OH group], it cannot be put into practical use as it is. Therefore, it is necessary to carry out the decomposition and removal processing of the unstable end portion, and it is preferable to perform the following decomposition and removal processing of the specific unstable end portion.
The specific process for decomposing and removing unstable terminals is a temperature of not less than the melting point of the polyoxymethylene copolymer and not more than 260 ° C. in the presence of at least one quaternary ammonium compound represented by the following general formula (2): It heat-processes in the state which melted the polyoxymethylene copolymer.

_{[R 2 R 3 R 4 R} 5 N +] n X -n formula (2)
(In the formula, R ₂ , R ₃ , R ₄ and R ₅ are each independently an unsubstituted alkyl group or substituted alkyl group having 1 to 30 carbon atoms; an aryl group having 6 to 20 carbon atoms; An aralkyl group having 30 unsubstituted alkyl groups or substituted alkyl groups substituted with at least one aryl group having 6 to 20 carbon atoms; or an aryl group having 6 to 20 carbon atoms having at least one carbon atom having 1 to 30 carbon atoms Represents an unsubstituted alkyl group or an alkylaryl group substituted with a substituted alkyl group, wherein the unsubstituted alkyl group or substituted alkyl group is linear, branched, or cyclic. An aldehyde group, a carboxyl group, an amino group, or an amide group, and the above-mentioned unsubstituted alkyl group, aryl group, aralkyl group, and alkylaryl group have a hydrogen atom as a halogen atom. N represents an integer of 1 to 3. X is a hydroxyl group, a carboxylic acid having 1 to 20 carbon atoms, a hydrogen acid other than hydrogen halide, an oxo acid, an inorganic thioacid, or a carbon number of 1. Represents an acid residue of ˜20 organic thioacids.)

The quaternary ammonium compound is not particularly limited as long as it is represented by the general formula (2), but R ₂ , R ₃ , R ₄ , and R ₅ in the general formula (2) are each independently , An alkyl group having 1 to 5 carbon atoms or a hydroxyalkyl group having 2 to 4 carbon atoms, and among them, at least one of R ₂ , R ₃ , R ₄ , and R ₅ is a hydroxyethyl group. Some are particularly preferred. Specifically, tetramethylammonium, tetoethylammonium, tetrapropylammonium, tetra-n-butylammonium, cetyltrimethylammonium, tetradecyltrimethylammonium, 1,6-hexamethylenebis (trimethylammonium), decamethylene-bis- ( Trimethylammonium), trimethyl-3-chloro-2-hydroxypropylammonium, trimethyl (2-hydroxyethyl) ammonium, triethyl (2-hydroxyethyl) ammonium, tripropyl (2-hydroxyethyl) ammonium, tri-n-butyl ( 2-hydroxyethyl) ammonium, trimethylbenzylammonium, triethylbenzylammonium, tripropylbenzylammonium, tri-n-butylbenzene Zirammonium, trimethylphenylammonium, triethylphenylammonium, trimethyl-2-oxyethylammonium, monomethyltrihydroxyethylammonium, monoethyltrihydroxyethylammonium, okdadecyltri (2-hydroxyethyl) ammonium, tetrakis (hydroxyethyl) ammonium, etc. Hydroxides of hydrochloric acid, odorous acid, hydrofluoric acid, etc .; sulfuric acid, nitric acid, phosphoric acid, carbonic acid, boric acid, chloric acid, iodic acid, silicic acid, perchloric acid, chlorous acid, hypochlorous acid Oxo acid salts such as chlorosulfuric acid, amidosulfuric acid, disulfuric acid, tripolyphosphoric acid; thioic acid salts such as thiosulfuric acid; formic acid, acetic acid, propionic acid, butanoic acid, isobutyric acid, pentanoic acid, caproic acid, caprylic acid, capric acid Carboxylic acid salts such as benzoic acid and oxalic acid. It is.

Among them, hydroxide (OH ⁻ ), sulfuric acid (HSO ₄ ⁻ , SO ₄ ²⁻ ), carbonic acid (HCO ₃ ⁻ , CO ₃ ²⁻ ), boric acid (B (OH) ₄ ⁻ ), and carboxylic acid salts are included. preferable. Of the carboxylic acids, formic acid, acetic acid, and propionic acid are particularly preferred. These quaternary ammonium compounds may be used alone or in combination of two or more. Further, in addition to the quaternary ammonium compound, there may be used any known amines such as ammonia and triethylamine which are known decomposition accelerators for unstable terminals.
The amount of the quaternary ammonium compound is in the range of 0.05 mass ppm to 50 mass ppm.
When the addition amount of the quaternary ammonium compound is less than 0.05 mass ppm, the degradation removal rate of the unstable terminal portion decreases, and when it exceeds 50 mass ppm, the color tone of the polyoxymethylene copolymer after decomposition removal of the unstable terminal portion Gets worse.

  The decomposition and removal treatment of the unstable terminal portion of the polyoxymethylene resin is achieved by heat treatment in a state where the polyoxymethylene copolymer is melted at a temperature of the melting point or higher and 260 ° C. or lower. Although there is no restriction | limiting in particular in the apparatus to be used, It is suitable to heat-process using an extruder, a kneader, etc. In addition, formaldehyde generated by decomposition is removed under reduced pressure. There are no particular restrictions on the method of adding the quaternary ammonium compound, and there are a method of adding it as an aqueous solution in the step of deactivating the polymerization catalyst, a method of spraying the polyoxymethylene copolymer powder produced by the polymerization, and the like. Whichever method is used, it is sufficient that the polyoxymethylene copolymer is added in the heat treatment step, and it can be poured into an extruder or blended with fillers and pigments using an extruder or the like. For example, the compound may be attached to the resin pellet, and the unstable terminal removal operation may be performed in the subsequent blending step.

The unstable terminal removal operation can be performed after the polymerization catalyst in the polyoxymethylene copolymer obtained by polymerization is deactivated, or can be performed without deactivating the polymerization catalyst. A typical example of the deactivation operation of the polymerization catalyst is a method of neutralizing and deactivating the polymerization catalyst in a basic aqueous solution such as amines. It is also effective to perform this unstable terminal removal operation after heating in an inert gas atmosphere at a temperature below the melting point without deactivating the polymerization catalyst to reduce the volatilization of the polymerization catalyst. .
By the above-mentioned specific unstable terminal decomposition and removal treatment, it is possible to obtain a polyoxymethylene copolymer with very few unstable terminals and excellent in thermal stability.

Next, (B) the hydrazide compound will be described.
Examples of the hydrazide compound include monocarboxylic acid monohydrazide and dicarboxylic acid dihydrazide, and dicarboxylic acid dihydrazide represented by the following general formula (1) is preferable.

_{H 2 NNHCO-R 1 -CONHNH 2} (1)
(Wherein R ₁ represents a hydrocarbon having 1 to 20 carbon atoms)

  Among these, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, pimelic acid dihydrazide, suberic acid dihydrazide, azelaic acid dihydrazide, sebacic acid dihydrazide, dodecanedioic acid dihydrazide, isophthalic acid dihydrazide, , 6-naphthalenedicarboxylic acid dihydrazide and the like, still more preferably sebacic acid dihydrazide, dodecanedioic acid dihydrazide, adipic acid dihydrazide, isophthalic acid dihydrazide, 2,6-naphthalenedicarboxylic acid dihydrazide, most preferably sebacic acid dihydrazide. Adipic acid dihydrazide. The blending ratio of the hydrazide compound is preferably 0.01 to 5 parts by mass, more preferably 0.03 to 3 parts by mass, and particularly preferably 0 to 0.1 parts by mass with respect to 100 parts by mass of the polyoxymethylene resin. 0 5 to 1 part by mass. By being within the range of 0.01 to 5 parts by mass, a polyoxymethylene resin composition having a balance between reduction of formaldehyde emission and impact and discoloration can be obtained. These hydrazide compounds may be used alone or in combination of two or more.

Next, (C) the filler will be described.
(C) As the filler, a fibrous, particulate, plate-like, or needle-like filler is used.
Examples of the fibrous filler include glass fiber, asbestos fiber, carbon fiber, silicon fiber, silica / alumina fiber, zirconia fiber, boron nitride fiber, silicon nitride fiber, boron fiber, potassium titanate fiber, stainless steel, aluminum, titanium, Examples thereof include inorganic fibers such as copper and brass. Also included are whiskers such as short titanic acid whisker and zinc oxide whisker. A high melting point organic fibrous material such as an aromatic polyamide resin, a fluororesin, or an acrylic resin can also be used.

As powder filler, carbon black, silica, quartz powder, glass beads, glass powder, calcium silicate, aluminum silicate, kaolin, talc, clay, diatomaceous earth, wollastonite, iron oxide, titanium oxide, Examples thereof include metal oxides such as alumina, metal sulfates such as calcium sulfate and barium sulfate, carbonates such as calcium carbonate, magnesium carbonate and dolomite, silicon carbide, silicon nitride, boron nitride, various metal powders and the like.
Examples of the plate-like filler include mica, glass flakes, various metal foils and the like. These fillers can be used alone or in combination of two or more.
These fillers can be either surface-treated or unsurface-treated, and conventionally known materials can be used as the surface treatment agent. For example, various coupling treatment agents such as silane, titanate, aluminum, and zirconium can be used. Specifically, N- (2-aminoethyl) -3-aminopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, isopropyl trisstearoyl titanate, diisopropoxyammonium ethyl acetate, n-butyl zirconate, etc. Can be mentioned.

(C) Although the particle diameter of the filler is not particularly specified, the volume average particle diameter is preferably 0.1 to 100 μm, more preferably 0.3 to 50 μm. By using a material having a volume average particle diameter in the range of 0.1 to 100 μm, a molded article having excellent surface appearance and slidability can be obtained. If it is less than 0.1 μm, the melt viscosity in the resin processing step tends to increase significantly.
(C) The blending ratio of the filler is preferably 1 to 50 parts by mass and more preferably 2 to 40 parts by mass with respect to 100 parts by mass of the total amount of the polyoxymethylene resin and the filler. When the filler is 1 to 50 parts by mass, a reinforcing effect and easy moldability are possible. With 2 to 40 parts by mass, the reinforcing effect and the impact property are balanced, and a molded product with a good surface appearance can be obtained. It becomes.

Of these (C) fillers, wollastonite is preferably used. Wollastonite is usually a finely pulverized natural wollastonite or synthetic wollastonite, and in the course of this pulverization, slender needles and particles (short rods to particles) are obtained. These wollastonites may be acicular, particulate, or a combination thereof, and the particle diameter is preferably 0.5 to 40 μm, more preferably 1 to 30 μm in terms of volume average particle diameter. When the volume average particle size is 0.5 to 40 μm, surface appearance and rigidity can be improved. When the volume average particle diameter is 1 to 30 μm, the balance between slidability and rigidity is excellent, and the molding process is good.
The wollastonite particulate form preferably has an aspect ratio of 2 to 7, more preferably 3 to 5. When the aspect ratio is less than 2, the effect of improving the rigidity decreases, and when it exceeds 7, the warp tends to increase. The needle-shaped one preferably has an aspect ratio of 10 to 30, and more preferably 10 to 25. If the aspect ratio is less than 10, the rigidity improving effect is reduced, and if it exceeds 30, the warp tends to increase.

  The polyoxymethylene resin composition obtained by the production method of the present invention can further contain an appropriate additive in order to improve the thermal stability. Suitable additives include antioxidants, polymers or compounds containing formaldehyde-reactive nitrogen, formic acid scavengers, weathering (light) stabilizers, mold release (lubricants), and these are polyoxymethylene resins 100. It is preferable to mix | blend 0.01-10 mass parts with respect to a mass part.

  As the antioxidant, a hindered phenol antioxidant is preferable. Specifically, for example, n-octadecyl-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) -propionate, n-octadecyl-3- (3′-methyl-5′-t -Butyl-4'-hydroxyphenyl) -propionate, n-tetradecyl-3- (3 ', 5'-di-t-butyl-4'-hydroxyphenyl) -propionate, 1,6-hexanediol-bis- [ 3- (3,5-di-tert-butyl-4-hydroxyphenyl) -propionate], 1,4-butanediol-bis- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) -Propionate], triethylene glycol-bis- [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) -propionate], pentaerythritol tetrakis Methylene-3- (3 ', 5'-di -t- butyl-4'-hydroxyphenyl) propionate] methane, and the like. Preferably, triethylene glycol-bis- [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) -propionate] and pentaerythritol tetrakis [methylene-3- (3 ′, 5′-di-t -Butyl-4'-hydroxyphenyl) propionate] methane. These antioxidants may be used alone or in combination of two or more.

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

  Specific examples of the amide compound include polycarboxylic acid amides such as isophthalic acid diamide and anthranilamides. Specific examples of the amino-substituted triazine compound include 2,4-diamino-sym-triazine, 2,4,6-triamino-sym-triazine, N-butylmelamine, N-phenylmelamine, N, N-diphenylmelamine, N , N-diallylmelamine, benzoguanamine (2,4-diamino-6-phenyl-sym-triazine), acetoguanamine (2,4-diamino-6-methyl-sym-triazine), 2,4-diamino-6-butyl -Sym-triazine and the like. Specific examples of the adduct of an amino-substituted triazine compound and formaldehyde include N-methylol melamine, N, N′-dimethylol melamine, and N, N ′, N ″ -trimethylol melamine.

  Specific examples of condensates of amino-substituted triazine compounds and formaldehyde include melamine / formaldehyde condensates. Examples of the urea derivative include N-substituted urea, urea condensate, ethylene urea, hydantoin compound, and ureido compound. Specific examples of the N-substituted urea include methylurea, alkylenebisurea, and aryl substituted urea substituted with a substituent such as an alkyl group. Specific examples of the urea condensate include urea and formaldehyde condensates. Specific examples of the hydantoin compound include hydantoin, 5,5-dimethylhydantoin, 5,5-diphenylhydantoin and the like. Specific examples of the ureido compound include allantoin. Specific examples of the imide compound include succinimide, glutarimide, and phthalimide. These polymers or compounds containing formaldehyde-reactive nitrogen atoms may be used alone or in combination of two or more.

Examples of the formic acid scavenger include condensates of the above amino-substituted triazine compounds and amino-substituted triazine compounds with formaldehyde, such as melamine / formaldehyde condensates. Other formic acid scavengers include alkali metal or alkaline earth metal hydroxides, inorganic acid salts, carboxylate salts or alkoxides. For example, hydroxides such as sodium, potassium, magnesium, calcium or barium, carbonates, phosphates, silicates, borates, carboxylates, and layered double hydroxides of the above metals can be used. .
The carboxylic acid of the carboxylate is preferably a saturated or unsaturated aliphatic carboxylic acid having 10 to 36 carbon atoms, and these carboxylic acids may be substituted with a hydroxyl group. Specific examples of saturated or unsaturated aliphatic carboxylates include calcium dimyristate, calcium dipalmitate, calcium distearate, (myristic acid-palmitic acid) calcium, (myristic acid-stearic acid) calcium, ( (Palmitic acid-stearic acid) calcium is mentioned, and among them, calcium dipalmitate and calcium distearate are preferable.

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

In the general formula (1), examples of M ²⁺ include Mg ²⁺ , Mn ²⁺ , Fe ²⁺ , Co ²⁺ , Ni ²⁺ , Cu ²⁺ , Zn ^2+, etc. Examples of M ³⁺ include Al ³⁺ , Fe ³⁺ , Cr ³⁺ , ^Co 3+, ^{an in 3+, etc.,} as an example of ^{a n- is, OH -, F -, Cl} -, Br -, NO 3 -, CO 3 2-, SO 4 2-, Fe (CN) 6 3-, CH ₃ COO ⁻ , oxalate ion, salicylate ion and the like can be mentioned. Particularly preferred examples include CO ₃ ²⁻ and OH ⁻ . As a specific example, natural hydrotalcite represented by Mg _0.75 Al _0.25 (OH) ₂ (CO ₃ ) _0.125 · 0.5H ₂ O, Mg _4.5 Al ₂ (OH) ₁₃ CO ₃ · 3.5 H _{2 O,} may be mentioned synthetic hydrotalcite represented by _{Mg 4.3 Al 2 (OH) 12.6} CO 3 or the like.
These formic acid scavengers may be used alone or in combination of two or more.

The weather resistance (light) stabilizer is preferably one or more selected from benzotriazole-based, oxalic anilide-based UV absorbers and hindered amine-based light stabilizers.
Examples of benzotriazole ultraviolet absorbers include 2- (2′-hydroxy-5′-methyl-phenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-t-butyl-phenyl). ) Benzotriazole, 2- [2′-hydroxy-3 ′, 5′-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2- [2′-hydroxy-3 ′, 5′-bis -(Α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2- (2′-hydroxy-4′-octoxyphenyl) benzotriazole and the like. Examples of oxalic acid alinide ultraviolet absorbers include 2-ethoxy-2′-ethyloxalic acid bisanilide, 2-ethoxy-5-tert-butyl-2′-ethyloxalic acid bisanilide, and 2-ethoxy. -3'-dodecyl oxalic acid bisanilide and the like. Preferably 2- [2′-hydroxy-3 ′, 5′-bis- (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di- t-butyl-phenyl) benzotriazole. These benzotriazole-based UV absorbers may be used alone or in combination of two or more.

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

Examples of the release (lubricating) agent include alcohols, fatty acids and esters thereof, polyoxyalkylene glycols, olefin compounds having an average polymerization degree of 10 to 500, and silicone. Of these, ethylene glycol dipalmitate and ethylene glycol diheptadecylate derived from fatty acids having 12 to 22 carbon atoms are preferred.
In the present invention, a suitable known additive can be further blended as necessary within a range not impairing the object of the present invention. Specifically, polyolefin resin, a sliding agent, a pigment, etc. can be mentioned.
The polyolefin resin is a homopolymer or copolymer of an olefinically unsaturated compound represented by the general formula (4), or a modified product thereof.

H ₂ C═C—R ₆ (4)
｜
R ₇
[Wherein R ₆ is a hydrogen atom or a methyl group, R ₇ is a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, a carboxyl group, an alkylated carboxy group containing 2 to 5 carbon atoms, 2 to 5 An acyloxy group having one carbon atom or a vinyl group is represented. ]

  Specifically, polyethylene (high density polyethylene, medium density polyethylene, high pressure method low density polyethylene, linear low density polyethylene, ultra low density polyethylene), polypropylene, ethylene-propylene copolymer, ethylene-butene copolymer, Polypropylene-butene copolymer, polybutene, hydrogenated polybutadiene, ethylene-acrylic acid ester copolymer, ethylene-methacrylic acid ester copolymer, ethylene-acrylic acid copolymer, ethylene-vinyl acetate copolymer, Etc.

  Examples of these modified products include graft copolymers obtained by grafting one or more other vinyl compounds. Among these, polyethylene (high pressure method low density polyethylene, linear low density polyethylene, ultra low density polyethylene), ethylene-propylene copolymer, and ethylene-butene copolymer are preferable. The molecular weight of these polyolefin resins is not particularly limited, but is preferably in the range of 10,000 to 300,000 in terms of weight average molecular weight, more preferably 10,000 to 100,000, and even more preferably 15,000. ~ 80,000. When the molecular weight is less than 10,000, the frictional wear property between the own materials is deteriorated, and when the weight average molecular weight exceeds 300,000, the frictional wear property with the polyoxymethylene resin is deteriorated. The blending ratio of the polyolefin polymer is preferably 0.1 to 10 parts by mass, more preferably 0.2 to 5 parts by mass with respect to 100 parts by mass of the resin comprising (A) polyoxymethylene resin and (B) filler. is there. When the polyolefin resin is 0.1 to 10 parts by mass, the slidability, impact property, and rigidity are balanced, and a molding process with good surface appearance is possible.

Examples of the sliding agent include alcohol and fatty acid esters, alcohol and dicarboxylic acid esters, and polyoxyalkylene glycol compounds.
The ester of alcohol and fatty acid is an ester of alcohol and fatty acid shown below. Alcohols are monohydric alcohols and polyhydric alcohols, and examples of monohydric alcohols include methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, amyl alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol, nonyl alcohol, Decyl alcohol, undecyl alcohol, lauryl alcohol, tridecyl alcohol, myristyl alcohol, pentadecyl alcohol, cetyl alcohol, heptadecyl alcohol, stearyl alcohol, oleyl alcohol, nonadecyl alcohol, eicosyl alcohol, seryl alcohol, behenyl alcohol, melyl alcohol , Hexyl decyl alcohol, octyl decyl alcohol, decyl myristyl alcohol, decyl Allyl alcohol, saturated or unsaturated alcohols such as.
Polyhydric alcohols are, for example, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, butanediol, pentanediol, hexanediol, glycerin, diglycerin, triglycerin, pentaerythritol, arabitol, ribitol, xylitol, sorbite Sorbitan, sorbitol, mannitol, and the like.

  Examples of fatty acids include caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, undecylic acid, lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, pentadecylic acid, stearic acid, nanodecanoic acid, arachidic acid, behenic acid Acid, lignoceric acid, serotic acid, heptaconic acid, montanic acid, melissic acid, lacteric acid, undecylenic acid, oleic acid, elaidic acid, cetreic acid, erucic acid, brassic acid, sorbic acid, linoleic acid, linolenic acid, arachidonic acid, Examples include propiolic acid, stearolic acid, and the like, and naturally occurring fatty acids containing such components or mixtures thereof. These fatty acids may be substituted with a hydroxy group. Among these esters of alcohol and fatty acid, esters of fatty acids and alcohols having 10 or more carbon atoms are preferable from the viewpoint of improving friction and wear performance, and fatty acids having 12 or more carbon atoms and alcohols having 10 or more carbon atoms and Ester is more preferable, and ester of a fatty acid having 12 to 30 carbon atoms and an alcohol having 10 to 20 carbon atoms is more preferable.

  Examples of esters of alcohol and dicarboxylic acid include octyl alcohol, nonyl alcohol, decyl alcohol, undecyl alcohol, lauryl alcohol, tridecyl alcohol, myristyl alcohol, pentadecyl alcohol, cetyl alcohol, heptadecyl alcohol, stearyl alcohol, oleyl alcohol, nona Saturated or unsaturated primary alcohols such as decyl alcohol, eicosyl alcohol, ceryl alcohol, behenyl alcohol, melyl alcohol, hexyl decyl alcohol, octyldodecyl alcohol, decyl myristyl alcohol, decyl stearyl alcohol, and oxalic acid, malonic acid, succinic acid Acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, maleic acid, Lumpur acid, monoesters of dicarboxylic acids such as, diesters, and mixtures thereof. Among these esters of alcohol and dicarboxylic acid, esters of alcohol having 10 or more carbon atoms and dicarboxylic acid are preferable.

  As the polyoxyalkylene glycol compound, three kinds of compounds may be mentioned. Examples of the first group of compounds include polycondensates having alkylene glycol as a monomer. For example, polyethylene glycol, polypropylene glycol, block polymer of ethylene glycol and propylene glycol, and the like can be mentioned. A preferable range of the degree of polymerization is 5 to 1,000, and a more preferable range is 10 to 500. The second group is an etherified product of a compound of the first group and an aliphatic alcohol. For example, polyethylene glycol oleyl ether (ethylene oxide polymerization degree 5-50), polyethylene glycol cetyl ether (ethylene oxide polymerization degree 5-50), polyethylene glycol stearyl ether (ethylene oxide polymerization degree 5-30), polyethylene glycol lauryl ether (ethylene Oxide polymerization degree 5-30), polyethylene glycol tridecyl ether (ethylene oxide polymerization degree 5-30), polyethylene glycol nonylphenyl ether (ethylene oxide polymerization degree 2-100), polyethylene glycol octylphenyl ether (ethylene oxide polymerization degree 4-4) 50), and the like. The third group of compounds is an esterified product of the first group of compounds and a higher fatty acid. For example, polyethylene glycol monolaurate (ethylene oxide polymerization degree 2-30), polyethylene glycol monostearate (ethylene oxide polymerization degree 2-50), polyethylene glycol monooleate (ethylene oxide polymerization degree 2-50), and the like. .

  Examples of the pigment include inorganic pigments, organic pigments, metallic pigments, fluorescent pigments, and the like. Inorganic pigments are those commonly used for resin coloring, such as zinc sulfide, titanium oxide, barium sulfate, titanium yellow, cobalt blue, combustion pigments, carbonates, phosphates, acetic acid. It refers to salt, carbon black, acetylene black, lamp black and the like. Organic pigments include condensed azo, inone, furothocyanin, monoazo, diazo, polyazo, anthraquinone, heterocyclic, pennon, quinacridone, thioindico, berylene, dioxazine, phthalocyanine, etc. Or other pigments. The ratio of the pigment to be added varies greatly depending on the color tone, so it is difficult to clarify, but generally it is used in the range of 0.05 to 5 parts by mass with respect to 100 parts by mass of the polyoxymethylene resin.

Next, the manufacturing method of a polyoxymethylene resin composition is demonstrated.
In the production method of the present invention, (A) polyoxymethylene resin is fed into the barrel from the main feed port of the extruder using an extruder having a screw configuration having a melting zone including a kneading disk and a kneading zone. Then, after being melted in the melting zone, (B) the hydrazide compound and (C) filler are supplied from the side feed port, kneaded in the kneading zone, and further degassed from the vent port and continuously from the die of the extruder. Must be extruded.
As the extruder, a generally used extruder can be used. Specific examples include a kneader, a roll mill, a single-screw extruder, a twin-screw extruder, and a multi-screw extruder.

  As the screw configuration of the extruder, (A) a polyoxymethylene resin or the like supplied from the main feed port was melted in a zone formed by a kneading disk block, and then supplied from the side feed port. It is necessary to have a kneading zone for kneading in a zone composed of kneading disk blocks for melt kneading the (B) hydrazide compound and (C) filler with the molten polyoxymethylene resin. That is, after (A) the polyoxymethylene resin is melted in the melting zone, (B) the hydrazide compound and (C) filler are supplied and melt-kneaded in the kneading zone. By supplying the (B) hydrazide compound or the (C) filler to the molten (A) polyoxymethylene resin, the dispersibility is improved, and the formaldehyde emission amount is reduced and the impact and discoloration are improved.

  Both the melting and kneading zones need to contain a kneading disk. By including a kneading disk, (A) the polyoxymethylene resin can be melted and (B) the hydrazide compound and (C) the filler can be finely dispersed. Here, the kneading disk has a high kneading ability because the disks mutually cross each other. There are two types of kneading discs: progressive type, non-feed type, and reverse type. Progressive type kneading discs have 2 to 10 blades, and the twist angle between the blades and the blades is 10 to 60 degrees. The length is in the range of 0.3 to 2.0 of the major axis of the screw. The feedless kneading disk has 2 to 10 blades, a twist angle of the blades of 70 to 110 degrees, and a length in the range of 0.3 to 2.0 of the major axis of the screw. The reverse feed type kneading disc is a disc having 2 to 10 blades, a twist angle between the blades and the blades of 10 to 60 degrees, and a length in the range of 0.3 to 2.0 of the major axis of the screw. I mean.

The number and type of kneading discs, the number of blocks constituted by the kneading discs, and the positions thereof can be determined as necessary within a range not impairing the object of the present invention. The screw is composed of blocks composed of kneading disk progressive, non-feed, and reverse and flight disks such as forward and reverse, but the number and type of flight disks should be determined as necessary. Can do.
Furthermore, the extruder must have a vent port. By degassing formaldehyde generated due to heat history or the like from the vent, it is possible to reduce the amount of formaldehyde released from the polyoxymethylene resin composition. The position of the vent port is preferably located after the kneading of the melting zone and the kneading zone by the kneading disk, and it is preferable to deaerate under reduced pressure at -0.06 to -0.1 MPa. Depending on the length of the barrel, a deaeration vent and an open vent can be provided between the melting zone and the kneading zone. The vent port located between the melting zone and the kneading zone may be used in an open vent for degassing the air bite generated when side-feeding a filler or the like, or for confirming the molten state.
The processing temperature for melt kneading is preferably 180 to 240 ° C., and replacement with an inert gas is also preferable for maintaining the quality and working environment.

In the present invention, the main feed port is a feed port at the top of the extruder, and the side feed port is a feed port located between the feed port at the top of the extruder and the die.
(B) The method of supplying the hydrazide compound and (C) filler to the side feed port may be supplied at the same position or at different positions. It is preferable to supply the position. When supplying to the same position, each component may be supplied separately, or may be supplied by blending in advance with a Henschel mixer or the like.
The (B) hydrazide compound can be supplied as a mixture or a masterbatch with a part of the (A) polyoxymethylene resin. For example, (A) polyoxymethylene resin pellets or pulverized powder and (B) hydrazide compound blended with a Henschel mixer to make a mixture, (A) polyoxymethylene resin pellets or pulverized powder and (B) hydrazide compound And blending with a Henschel mixer or the like, then melt-kneading and pelletizing to obtain a master batch.

The following is mentioned as a specific example of a manufacture example.
1. (A) Polyoxymethylene resin is supplied from the main feed port of the extruder, and (B) hydrazide compound and (C) filler are supplied from the side feed port at the same position to the melted state, and further melted. Kneading method.
2. (A) Polyoxymethylene resin is supplied from the main feed port of the extruder, and (B) hydrazide compound and (C) filler are supplied from the side feed ports at different positions to the melted state. Melting and kneading method.
3, (A) Polyoxymethylene resin is supplied from the main feed port of the extruder, and after being previously blended with (B) hydrazide compound and (C) filler in the molten state, supplied from the side feed port, Further melt-kneading method.

4. (A) A part of polyoxymethylene resin (pellet or pulverized powder) and (B) hydrazide compound were previously blended to form a mixture, and then the remaining part of (A) polyoxymethylene resin was fed from the main feed port of the extruder. A method in which the mixture and the filler (C) are supplied from the side feed ports at the same position or at different positions, and further melted and kneaded in the melted state.
5, (A) Polyoxymethylene resin (pellet or pulverized powder) and (B) hydrazide compound are pre-blended and melt-kneaded using an extruder to form a master batch, and then (A) polyoxymethylene A method in which the remainder of the resin is supplied from the main feed port of the extruder and the master batch and the filler (C) are supplied from the side feed port at the same position or at different positions in the melted state, and further melt kneaded. .

Among these production examples, one example is preferable from the viewpoints of reduced formaldehyde emission, impact properties, discoloration, and cost.
The method for molding the polyoxymethylene resin composition obtained by the production method of the present invention is not particularly limited, and known molding methods such as extrusion molding, injection molding, vacuum molding, blow molding, injection compression molding, Molding methods such as decorative molding, molding of other materials, gas-assisted injection molding, firing injection molding, low pressure molding, ultra-thin injection molding (ultra-high-speed injection molding), in-mold composite molding (insert molding, outsert molding) It can shape | mold by either.

  Since the molded product of the polyoxymethylene resin composition obtained by the production method of the present invention has a reduced formaldehyde emission amount and is excellent in impact and thermal discoloration, it is used in molded products for various applications. It is possible. For example, gears, cams, sliders, levers, arms, clutches, felt clutches, idler gears, pulleys, rollers, rollers, key stems, key tops, shutters, reels, shafts, joints, shafts, bearings, guides, etc. Mechanical parts, resin parts for outsert molding, resin parts for insert molding, chassis, trays, side plates, parts for office automation equipment such as printers and copiers, video tape recorders (VTRs), video movies, digital video cameras, Cameras and cameras represented by digital cameras, or parts for video equipment, cassette players, DAT, LD (Laser Disk), MD (Mini Disk), CD (Compact Disk) [CD-ROM (Read Including only memory), CD-R (recordable), CD-RW (rewriteable)], DVD (digital video disk) [DVD-ROM, DVD-R, DVD + R, DVD-RW, DVD + RW, DVD-R DL, DVD + R DL, DVD-RAM (including Random Access Memory), DVD-Audio), Blu-ray Disc, HD-DVD, other optical disk drives, MFD, MO, navigation systems, and music, video represented by mobile personal computers or Components for communication equipment such as information equipment, mobile phones and facsimile machines, parts for electrical equipment, parts for electronic equipment, parts for automobiles, gasoline tanks, fuel pump modules, valves Fuel-related parts such as gasoline tank flanges, door-lock parts such as door locks, door handles, window regulators, speaker grills, seat belt peripheral parts such as seat belt slip rings, press buttons, etc. , Combination switch parts, switches and clip parts, mechanical pencil pen tips and mechanical pencil core parts, wash basins, drain outlets and drain plug opening and closing mechanism parts, vending machine Opening / closing part locking mechanism and product discharge mechanism parts, cord stopper for clothing, adjuster and button, nozzle for watering, sprinkling hose connection joint, stair railing part and building article as a support for flooring, disposable camera , Toys, fasteners, chains, conveyors, buckles, sports It can be suitably used as industrial parts typified by articles, vending machines, furniture, musical instruments and housing equipment.

  Hereinafter, the present invention will be described specifically by way of examples. The contents of components used in Examples and Comparative Examples and evaluation methods are shown below.

[Contents of ingredients used]
<(A) Polyoxymethylene resin>
A: Polyoxymethylene copolymer containing 4 mol% of ethylene oxide as a comonomer having a melt index of 30 g / 10 min (ASTM D-1238-57T) (polyamide 66: 0.05 parts by mass as a stabilizer, calcium stearate: 0. 1 part by mass, containing triethylene glycol-bis- (3- (3-t-butyl-5-methyl-4-hydroxyphenyl) -propionate): 0.4 part by mass)
<(B) hydrazide compound>
B-1: Sebacic acid dihydrazide (manufactured by Nippon Finechem Industry Co., Ltd.)
B-2: Adipic acid dihydrazide (manufactured by Nippon Finechem Industry Co., Ltd.)
<(C) Filler>
C-1: Particle-shaped surface untreated wollastonite having a volume average particle diameter of 3 μm and an aspect ratio of 3 measured by a laser particle size measuring apparatus.
C-2: Untreated surface talc in the form of particles having a volume average particle diameter of 6 μm and an aspect ratio of 5 as measured with a laser particle size measuring apparatus.
C-3: Surface-treated potassium titanate whisker in the form of particles having a minor axis of 0.15 μm and a major axis of 20 μm as measured with a scanning electron microscope.

[Evaluation method]
(1) Amount of formaldehyde released from molded product Using an IS-100GN injection molding machine manufactured by Toshiba Machine Co., Ltd., cylinder temperature: 200 ° C., injection pressure: (primary pressure / secondary pressure = 63.7 MPa / 50 0.0 MPa) Injection time: 15 seconds, cooling time: 20 seconds, mold temperature: 77 ° C., a test piece was prepared and measured by the VDA275 method to determine the amount of formaldehyde released from the molded product.
<VDA275 method>
Put a test piece (length: 100 mm x width: 40 mm x thickness: 3 mm) of 50 mL of distilled water in a 1 L polyethylene container, seal it, heat it at 60 ° C for 3 hours, and then dissolve the formaldehyde in distilled water in the presence of ammonium ions. The reaction product was reacted with acetylacetone and the absorption peak at 412 nm was measured with a UV spectrometer to determine the amount of formaldehyde released (mg / kg).

(2) Color tone (b)
After drying the polyoxymethylene resin composition pellets at 80 ° C. for 3 hours, the polyoxymethylene resin composition melted in the molding machine at a cylinder temperature of 200 ° C. is retained for a predetermined time using an injection molding machine manufactured by ARBURG. Thereafter, injection molding was performed, and the color tone of the injection-molded molded article was measured using a Minolta color difference meter CR-200.
(3) Charpy impact strength IS-100GN manufactured by Toshiba Machine Co., Ltd., cylinder temperature: 205 ° C., injection pressure: (primary pressure = 65 MPa) injection time: 35 seconds, cooling time: 15 seconds Mold temperature: ISO tensile test piece was prepared at a setting of 90 ° C. A Charpy impact test piece was prepared from this ISO tensile test piece using NOTCHING TOOL A-4 manufactured by Toyo Seiki Co., Ltd., and measured according to JIS K7111 (ISO 179 / 1eA) to determine the impact strength.
(4) Repetitive impact strength Using an SH-75 injection molding machine manufactured by Sumitomo Metal Industries, cylinder temperature: 200 ° C., injection pressure: (primary pressure = 54 MPa) Injection time: 25 seconds, cooling time: 15 An ASTM test piece was prepared at a setting of seconds, mold temperature; 70 ° C. A test piece for Izod impact strength (prepared based on ASTM D256) was prepared using a notching machine manufactured by Tester Sangyo Co., Ltd., and this test piece was loaded with a repeated impact tester manufactured by Toyo Seiki Co., Ltd. The number of times until a fracture was applied by repeated impact under the conditions of 160 g, a drop height of 20 mm, and a drop speed of 35 times / minute was determined.

[Example 1]
Manufacturing method: A
A block composed of kneading disk forward feed, no feed, and reverse feed to a twin screw extruder (model name: TEM-58SS manufactured by Toshiba Machine Co., Ltd.) with L / D = 53.8 set to 200 ° C. , Cylinder block NO. 6 (melting zone), cylinder block No. No. 11 (kneading zone) Using a screw configured to be located at two locations, the A component: 80 parts by mass of the polyoxymethylene copolymer was transferred from the main feeder (SF-3) to the main feed port (NO.1). B component: 0.1 parts by mass of B-1 hydrazide compound and C component: 20 parts by mass of C-1 filler are located at the same position from each side feeder (SF, SF-2). (NO.10) and kneading was performed at a screw rotation speed of 150 rpm. The ratio between the main feed and the side feed was adjusted so as to be the respective mass ratios, and the final discharge rate was adjusted to 150 kg / hr. In addition, it confirmed that the polyoxymethylene resin was fuse | melted from the open vent port (V-1). The deaeration vent (V-2) was sucked at -0.1 MPa. The extruded resin was pelletized with a strand cutter and evaluated using the obtained pellet. The results are shown in Table 1.

[Examples 2 to 8, Comparative Example 1]
Manufacturing method: A
Evaluation was performed using pellets obtained by operating in the same manner as in Example 1 except that the components A, B, and C were added in the proportions shown in Table 1. The results are shown in Table 1.

[ Reference Example 9]
Manufacturing method: B
A block composed of kneading disk forward feed, no feed, and reverse feed to a twin screw extruder (Toshiba Machine Co., Ltd. model name: TEM-58SS) set at 200 ° C. , Cylinder block NO. 6 (melting zone), cylinder block No. No. 11 (kneading zone) Using a screw configured to be located at two locations, the A component: 80 parts by mass of the polyoxymethylene copolymer was transferred from the main feeder (SF-3) to the main feed port (NO.1). The component B: 0.1 part by mass of the B-1 hydrazide compound and the component C: 20 parts by mass of the C-1 filler are separated from each side feeder (SF, SF-2) ( No. 8, NO. 10) and kneading was performed at a screw rotation speed of 150 rpm. The ratio between the main feed and the side feed was adjusted so as to be the respective mass ratios, and the final discharge rate was adjusted to 150 kg / hr. In addition, it confirmed that the polyoxymethylene resin was fuse | melted from the open vent port (V-1). The deaeration vent (V-2) was sucked at -0.1 MPa. The extruded resin was pelletized with a strand cutter and evaluated using the obtained pellet. The results are shown in Table 2.

[ Reference Examples 10 to 16]
Manufacturing method: B
Evaluation was performed using pellets obtained by extrusion in the same manner as in Reference Example 9 except that A component, B component, and C component were added in the proportions shown in Table 2. The results are shown in Table 2.

[ Reference Example 17]
Manufacturing method: C
A block composed of kneading disk forward feed, no feed, and reverse feed to a twin screw extruder (Toshiba Machine Co., Ltd. model name: TEM-58SS) set at 200 ° C. , Cylinder block NO. 6 (melting zone), cylinder block No. No. 11 (kneading zone) Using a screw configured to be located at two locations, the A component: 80 parts by mass of the polyoxymethylene copolymer was transferred from the main feeder (SF-3) to the main feed port (NO.1). The component B: 0.1 part by mass of the B-1 hydrazide compound and the component C: 20 parts by mass of the C-1 filler are supplied to each side feeder (SF-2, SF-1) (manufacturing method). The feed positions of the B component and the C component of B were reversed (NO. 8, NO. 10), and kneaded at a screw rotation speed of 150 rpm. The ratio between the main feed and the side feed was adjusted so as to be the respective mass ratios, and the final discharge rate was adjusted to 150 kg / hr. In addition, it confirmed that the polyoxymethylene resin was fuse | melted from the open vent port (V-1). The deaeration vent (V-2) was sucked at -0.1 MPa. The extruded resin was pelletized with a strand cutter and evaluated using the obtained pellet. The results are shown in Table 3.

[ Reference Examples 18-24]
Manufacturing method: C
Evaluation was performed using pellets obtained by extrusion in the same manner as in Reference Example 17 except that component A, component B and component C were added in the proportions shown in Table 3. The results are shown in Table 3.

[Comparative Example 2]
Manufacturing method: D
A block composed of kneading disk forward feed, no feed, and reverse feed to a twin screw extruder (model name: TEM-58SS manufactured by Toshiba Machine Co., Ltd.) with L / D = 53.8 set to 200 ° C. , Cylinder block NO. 6 (melting zone), cylinder block No. Using a screw constructed so as to be located at two locations near 11 (kneading zone), 80 parts by mass of A component: polyoxymethylene copolymer and 20 parts by mass of C component: C-1 filler were blended with a Henschel mixer. The material was fed from the feeder (S.F-3) to the main feed port (NO.1) and kneaded at a screw rotation speed of 150 rpm. The final discharge rate was adjusted to 150 kg / hr. It was confirmed that the polyoxymethylene resin was melted from the open vent port (V-1). The deaeration vent (V-2) was sucked at -0.1 MPa.
The extruded resin was pelletized with a strand cutter and evaluated using the obtained pellet. The results are shown in Table 4.

[Comparative Examples 3 to 10]
Manufacturing method: D
Evaluation was performed using pellets obtained by extrusion in the same manner as in Comparative Example 2 except that the A component, B component, and C component were added in the proportions shown in Table 4. The results are shown in Table 4.

The polyoxymethylene resin composition obtained by the production method of the present invention provides a molded article that significantly reduces the amount of formaldehyde released and further has excellent impact and thermal discoloration compared to conventional compositions. For example, parts used for OA equipment represented by printers and copiers, parts used for video equipment represented by video movies, navigation systems, and mobile personal computers Parts used for music, video, or information equipment, parts used for communication equipment typified by mobile phones and facsimile machines, parts used for automobile interior and exterior mechanism parts, and disposable cameras, toys, fasteners, It can be used for applications such as conveyors, buckles, and parts used in industrial goods represented by residential equipment.
Specifically, the parts used in the various devices mentioned above include gears, cams, sliders, levers, arms, clutches, joints, shafts, bearings, key stems, key tops, and other mechanical parts, and resin parts for outsert chassis. , Chassis, trays, and side plates.

1-12: Extruder Cylinder block M: Extruder motor D: Dice V-1: Open vent V-2: Degassing vent F-1: Fixed side feeder-1
S. F-2: Fixed side feeder-2
S. F-3: Quantitative feeder-3

Claims (4)

A method for producing a polyoxymethylene resin composition comprising (A) a polyoxymethylene resin, (B) a hydrazide compound, and (C) a filler, comprising: (A) a polyoxymethylene resin, (B) a hydrazide compound, and ( C) The mixing ratio of the filler is (A) 50 to 99 parts by mass of the polyoxymethylene resin, (C) 1 to 50 parts by mass of the filler, and the total of (A) the polyoxymethylene resin and (C) the filler. Using an extruder equipped with a screw configuration having 0.01 to 5 parts by mass of (B) hydrazide compound and having a kneading disk as an essential component and having a melting zone and a kneading zone with respect to 100 parts by mass of ( A) Polyoxymethylene resin is fed into the barrel from the main feed port of the extruder and melted in the melting zone, and then (B) the hydrazide compound and (C) filler are side fed. A method for producing a polyoxymethylene resin composition characterized by being fed from the same position of the mouth, kneaded in a kneading zone, and continuously extruded from a die of an extruder while degassing from a vent mouth. The melting zone and the kneading zone both include a kneading disk, and the kneading disk has a structure in which the disks alternate with each other. The method for producing a polyoxymethylene resin composition according to claim 1, which is in the range of 0.3 to 2.0. (B) The manufacturing method of the polyoxymethylene resin composition of Claim 1 or 2 whose hydrazide compound is following General formula (1).
_{H 2 NNHCO-R 1 -CONHNH 2} (1)
(Wherein R ₁ represents a hydrocarbon having 1 to 20 carbon atoms) (C) The method for producing a polyoxymethylene resin composition according to any one of claims 1 to 3, wherein the filler is at least one filler selected from fibrous, particulate, and plate-like fillers.

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