JP6563293B2 - Polyacetal resin composition and molded article thereof - Google Patents

Description

  The present invention relates to a polyacetal resin composition and a molded body thereof.

The polyacetal resin, for example, has an excellent balance of mechanical strength such as flexural modulus and tensile fracture stress, chemical resistance, slidability, and wear resistance, and is easy to process. For this reason, polyacetal resins are widely used as typical engineering plastics, such as mechanical parts for electrical equipment and automobile parts.
In particular, a polyacetal resin composition reinforced with an inorganic filler is used for automotive parts that require durability. The durability means, for example, a long fracture life under a constant stress, and is also called creep resistance.

In a reinforced polyacetal resin composition containing an inorganic filler, the polyacetal resin is increased in molecular weight and the end group of the polyacetal resin is controlled in order to improve strength and durability.
Patent Document 1 discloses a polyacetal resin composition containing a polyacetal resin and a glass-based inorganic filler for the purpose of achieving excellent mechanical strength, and 50 to 2000 mmol / mol in the molecule of the polyacetal resin. It is disclosed that a modified polyacetal resin having kg hydroxyl group is blended.
Patent Document 2 describes at least one polyoxymethylene having at least one terminal OH group having at least 15 mmol / kg and at least one coupling for the purpose of achieving excellent formaldehyde emission and low formaldehyde emission. A composition comprising an agent, at least one reinforcing fiber, and optionally at least one formaldehyde supplement is disclosed.

JP 2004-359791 A Special table 2013-539810 gazette

In recent years, there has been a demand for higher performance and easier handling of mechanical parts and automobile parts using polyacetal resin.
Specifically, improvement in mechanical performance includes improvement in mechanical strength, durability, and retention of slidability. Further, as durability, performance under higher load conditions is required. Specific examples of facilitating handling include molding fluidity.
However, even if the terminal hydroxyl group of the polyacetal resin is simply increased, mechanical strength that is a short-term evaluation can be obtained, but a dramatic improvement in durability that is a long-term evaluation is difficult to obtain.
The conventional polyacetal resin compositions as disclosed in Patent Documents 1 and 2 cannot satisfy the durability under a high load.
The problem to be solved by the present invention is to provide a resin composition capable of achieving both high performance (mechanical strength, durability under high load, slidability) and easy handling. is there.

  The present inventors diligently studied to solve the above problems. As a result, surprisingly, the above problem can be solved by forming a composition containing at least one acid component as a sizing agent in a polyacetal resin having a terminal OH group concentration exceeding 15 and not exceeding 100 mmol / kg. The present invention has been completed.

That is, the present invention is as follows.
[1]
(A) A polyacetal resin composition comprising 100 parts by mass of a polyacetal resin and (B) 10 to 100 parts by mass of a glass-based filler, wherein (A) the terminal OH group concentration of the polyacetal resin is 15. A polyacetal resin composition that exceeds 100 mmol / kg and contains at least one acid component as a sizing agent for the glass-based filler (B).
[2]
The polyacetal resin composition according to [1], wherein the acid component of the sizing agent of the (B) glass-based filler is a carboxylic acid.
[3]
The polyacetal resin composition according to [1] or [2], wherein the acid component of the sizing agent of the (B) glass-based filler is acrylic acid.
[4]
The polyacetal resin composition according to any one of [1] to [3], further including 0.01 to 5 parts by mass of a (C) formaldehyde scavenger with respect to 100 parts by mass of the (A) polyacetal resin.
[5]
The polyacetal resin composition according to any one of [1] to [4], further comprising (D) 0.01 to 5 parts by mass of a weathering agent with respect to 100 parts by mass of the (A) polyacetal resin.
[6]
The polyacetal resin composition according to any one of [1] to [5], wherein the (A) polyacetal resin contains a block component.
[7]
The polyacetal resin composition according to [6], wherein the block component is a hydrogenated polybutadiene component.
[8]
The molded object containing the polyacetal resin composition in any one of [1]-[7].

  According to the present invention, it is possible to provide a resin composition that can achieve both high durability and high quality.

  Hereinafter, modes for carrying out the present invention (hereinafter referred to as embodiments) will be described in detail. The following embodiments are examples for explaining the present invention, and the present invention is not limited to the following contents. The present invention can be implemented with various modifications within the scope of the gist.

[Polyacetal resin composition]
The polyacetal resin composition of the present embodiment is a polyacetal resin composition comprising (A) 100 parts by mass of a polyacetal resin and (B) 10 to 100 parts by mass of a glass-based filler. The polyacetal resin composition has a terminal OH group concentration of more than 15 and 100 mmol / kg or less, and includes (B) at least one acid component as a sizing agent for a glass-based filler.

The terminal OH group concentration of the (A) polyacetal resin in this embodiment is more than 15 and 100 mmol / kg or less. When the concentration exceeds 15, mechanical strength, durability, and molding fluidity are improved.
In addition, when the concentration is 100 or less, decomposition during molding can be suppressed, and it is possible to maintain a working environment by suppressing generation of gas and to improve the appearance of the molded body.
The lower limit is preferably 15.2, more preferably 15.4 mmol / kg. The upper limit is preferably 60, more preferably 50, still more preferably 40, and most preferably 30 mmol / kg.

Content of (B) glass-type filler in this embodiment is 10 mass parts or more and 100 mass parts or less with respect to 100 mass parts of (A) polyacetal resin.
When the content is 10 parts by mass or more, mechanical strength and durability are improved.
Moreover, when the content is 100 parts by mass or less, it is possible to suppress breakage of the glass filler due to contact between the glass fillers during molding. For this reason, mechanical strength and creep resistance are improved. Furthermore, when the content is 100 parts by mass or less, stable molding can be performed and appearance defects of the molded body can be suppressed.
The lower limit of the content is preferably 12 parts by mass, more preferably 15 parts by mass, still more preferably 20 parts by mass, and even more preferably 25 parts by mass.
The upper limit of the content is preferably 90 parts by mass, more preferably 80 parts by mass, still more preferably 75 parts by mass, and even more preferably 70 parts by mass.

(B) The sizing agent for the glass-based filler contains at least one acid component. By including an acid component, mechanical strength and durability can be improved.
By combining the (A) polyacetal resin having a desired terminal OH group concentration and a glass-based filler containing at least one acid component as a sizing agent, dramatic mechanical strength and durability that could not be achieved in the past The improvement of moldability and the moldability can be achieved at the same time.

<(A) polyacetal resin>
The (A) polyacetal resin (hereinafter sometimes referred to as the component (A)) that can be used in the polyacetal resin composition of the present embodiment will be described in detail below.
Examples of the polyacetal resin (A) that can be used in this embodiment include polyacetal homopolymers, polyacetal copolymers, polyacetal copolymers having a crosslinked structure, homopolymer-based block copolymers having a block component, and copolymer-based block copolymers having a block component Is mentioned.
(A) A polyacetal resin may be used individually by 1 type, or may be used in combination of 2 or more type.
As the (A) polyacetal resin, for example, combinations having different molecular weights, combinations of polyacetal copolymers having different comonomer amounts, and the like can be used as appropriate.
In this embodiment, it is preferable that a block copolymer is included as (A) polyacetal resin.

The (A) polyacetal resin of this embodiment has a terminal OH group of more than 15 and 100 mmol / kg or less. The terminal OH group is generated by using a hydroxyl group-containing substance as a chain transfer agent or a molecular weight modifier during the polymerization reaction. The terminal OH group concentration of the polyacetal resin can be adjusted by adjusting the amount of the substance containing a hydroxyl group.
Although it does not specifically limit as a substance containing a hydroxyl group, Water, alcohol, a polyhydric alcohol, diol, a triol, etc. are mentioned. Examples of the alcohol and polyhydric alcohol include methanol, ethanol, propanol, isopropanol, butanol, pentanol, hexanol, peptanol, octanol, lauryl alcohol, myristyl alcohol, cetyl alcohol, oleyl alcohol, and linolyl alcohol. Examples of the diol include ethylene glycol, propylene glycol, butylene glycol, and other polydiols.

  The terminal OH group of the polyacetal resin can be quantified by the method described in the examples described later. In the case of a polyacetal resin that cannot be dissolved in hexafluoroisopropyl alcohol (HFIP), it can be dissolved by appropriately mixing with other solvent such as chloroform or heating.

(A) As a polyacetal resin, specifically, substantially only an oxymethylene unit obtained by homopolymerizing a formaldehyde monomer or a cyclic oligomer of formaldehyde such as a trimer (trioxane) or a tetramer (tetraoxane). A polyacetal homopolymer comprising, a formaldehyde monomer or a cyclic oligomer of formaldehyde such as a trimer (trioxane) or a tetramer (tetraoxane), ethylene oxide, propylene oxide, epichlorohydrin, 1,3-dioxolane, 1, Examples thereof include polyacetal copolymers obtained by copolymerizing a cyclic ether such as a glycol such as 4-butanediol formal or a cyclic formal of diglycol or a cyclic formal.
As a polyacetal copolymer, obtained by copolymerizing formaldehyde monomer and / or cyclic oligomer of formaldehyde with monofunctional glycidyl ether and a branched polyacetal copolymer obtained by copolymerization, and polyfunctional glycidyl ether. It is also possible to use a polyacetal copolymer having a crosslinked structure.
The polyacetal copolymer may be a block copolymer having different types of blocks different from the repeating structural unit of the polyacetal.

  In the present embodiment, as the block copolymer, an acetal homopolymer or acetal copolymer having at least a block component represented by any one of the following formulas (1), (2), or (3) (hereinafter referred to as a block copolymer together) Is preferable.).

In formulas (1) and (2), R ₁ and R ₂ each independently represent one type selected from the group consisting of a hydrogen atom, an alkyl group, a substituted alkyl group, an aryl group, and a substituted aryl group, R ₁ and R ₂ may be the same or different.
R ₃ represents one selected from the group consisting of an alkyl group, a substituted alkyl group, an aryl group, and a substituted aryl group.
m shows the integer of 1-6, and the integer of 1-4 is preferable.
n shows the integer of 1-10000, and the integer of 10-2500 is preferable.
The block component represented by the above formula (1) is a residue obtained by eliminating a hydrogen atom from an alkylene oxide adduct of alcohol, and the block component represented by the above formula (2) is an alkylene oxide addition of a carboxylic acid. It is a residue obtained by removing a hydrogen atom from a product.
The polyacetal homopolymer having a block component represented by the formula (1) or (2) can be prepared, for example, by the method described in JP-A-57-31918.

In Formula (3), R ₄ represents one selected from the group consisting of a hydrogen atom, an alkyl group, a substituted alkyl group, an aryl group, and a substituted aryl group, and the plurality of R ₄ are the same or different. May be.
p represents an integer of 2 to 6, and two p's may be the same or different.
q and r each represent a positive number. When the total of q and r is 100 mol%, q is 2 to 100 mol%, r is 0 to 98 mol%, and — (CH (CH ₂ CH ₃₎ CH ₂₎ - units and _{- (CH 2 CH 2 CH 2} CH 2) - units are present in random or block respectively.

The block component represented by any of the following formulas (1), (2), or (3) is a compound that constitutes a block component having a functional group such as a hydroxyl group at both ends or one end, in the polymerization process of polyacetal. It can be inserted into the polyacetal resin by reacting with the terminal portion of the polyacetal.
The amount of the block component represented by the formula (1), (2) or (3) in the block copolymer is not particularly limited, but when the block copolymer is 100% by mass, for example, 0.001% by mass or more 30 It is below mass%.
From the viewpoint of not reducing the flexural modulus of the molded body, the amount of the block component inserted is preferably 30% by mass or less, and from the viewpoint of the tensile strength of the molded body, the amount of the block component inserted is 0.001% by mass or more. It is preferable that
The lower limit of the amount of the block component inserted is more preferably 0.01% by mass, still more preferably 0.1% by mass, and still more preferably 1% by mass.
The upper limit of the insertion amount of the block component is more preferably 15% by mass, further preferably 10% by mass, and still more preferably 8% by mass.

The molecular weight of the block component in the block copolymer is preferably 10,000 or less from the viewpoint of not reducing the flexural modulus of the molded product, more preferably 8000 or less, and even more preferably 5000 or less.
The lower limit of the molecular weight of the block component is not particularly limited, but is preferably 100 or more from the viewpoint of maintaining stable slidability.

Compound forming the block component in the block copolymer is not particularly limited, _{specifically, C 18 H 37 O (CH} 2 CH 2 O) 40 C 18 H 37, C 11 H 23 CO 2 (CH 2 CH 2 O) ₃₀ H, C ₁₈ H ₃₇ O (CH ₂ CH ₂ O) ₇₀ H, C ₁₈ H ₃₇ O (CH ₂ CH ₂ O) ₄₀ H, both-end hydroxyalkylated hydrogenated polybutadiene, and the like.

The block copolymer is preferably an ABA type block copolymer as a bonding form.
The ABA type block copolymer is a block copolymer having a block component represented by the formula (3). Specifically, the polyacetal segment A (hereinafter referred to as A) and both ends are hydroxyalkylated. It means a block copolymer in which hydrogenated polybutadiene segment B (hereinafter referred to as B) is constituted in the order of ABA.

Equation (1), the block component represented by formula (2) or Formula (3) may have the following unsaturated bond iodine value 20g-I ₂ / 100g. Although it does not specifically limit as an unsaturated bond, For example, a carbon-carbon double bond is mentioned.
Examples of the polyacetal copolymer having a block component represented by the formula (1), the formula (2), or the formula (3) include the polyacetal block copolymer disclosed in International Publication No. 2001/09213. It can be prepared by the method.
By using an ABA type block copolymer as the block copolymer, the adhesion to the surface of the (B) glass-based filler tends to be improved. As a result, it tends to be possible to increase the tensile fracture stress and the flexural modulus of the molded body.

The ratio of the block copolymer in the (A) polyacetal resin is preferably 5% by mass or more and 95% by mass or less when the total amount of the (A) polyacetal resin is 100% by mass.
The lower limit of the ratio of the block copolymer is more preferably 10% by mass, still more preferably 20% by mass, and still more preferably 25% by mass.
The upper limit of the ratio of the block copolymer is more preferably 90% by mass, still more preferably 80% by mass, and still more preferably 75% by mass.
The ratio of the block copolymer in the resin composition of the present embodiment can be measured by ¹ H-NMR, ¹³ C-NMR, or the like.

<(B) Glass-based filler>
Although it does not specifically limit as (B) glass-type filler (Hereinafter, it may be described as (B) component.) Which can be used in the polyacetal resin composition of this embodiment, Glass fiber, a glass bead, And glass flakes.
Examples of the glass fiber include chopped strand glass fiber, milled glass fiber, and glass fiber roving. Among these, chopped strand glass fibers are preferable from the viewpoints of handleability and mechanical strength of the molded body.
(B) A glass type filler may be used individually by 1 type, or may be used in combination of 2 or more type.

(B) The particle size, fiber diameter, fiber length and the like of the glass-based filler are not particularly limited, and any type of glass-based filler may be used. This increases the contact area and improves the creep resistance of the molded product.
In the case of chopped strand glass fibers, the average fiber diameter is, for example, 7 μm or more and 15 μm or less.
When the average fiber diameter is within the above range, the surface of the molded body becomes smooth, and deterioration of slidability can be suppressed. In addition, the creep resistance of the molded body can be enhanced, and the mold surface can be prevented from being scraped during molding.
The lower limit of the average fiber diameter is preferably 8 μm, more preferably 9 μm.
The upper limit of the average fiber diameter is preferably 14 μm, more preferably 12 μm.

In the present embodiment, the average fiber diameter is measured by incinerating the molded body at a sufficiently high temperature (400 ° C. or higher) to remove the resin component, and then observing the obtained ash with a scanning electron microscope. Can be easily measured. In order to eliminate an error, the diameter of at least 100 chopped strand glass fibers is measured, and the average value of the fiber diameters is calculated.
Two or more kinds of glass fibers having different fiber diameters may be blended and used.

(B) The glass-based filler is treated with a sizing agent and the surface is modified. The sizing agent is sometimes called a sizing agent, and is a substance having a function of modifying the surface of the filler.
Specifically, the sizing agent includes a sizing agent having at least one acid component.
Examples of the acid component include a copolymer containing a carboxylic acid-containing unsaturated vinyl monomer and an unsaturated vinyl monomer other than the carboxylic acid-containing unsaturated vinyl monomer as a constituent unit, and a carboxylic acid anhydride-containing component. Examples thereof include a copolymer containing an unsaturated vinyl monomer and an unsaturated vinyl monomer other than the carboxylic anhydride-containing unsaturated vinyl monomer as constituent units. Among these, it is more preferable to use a copolymer containing as constituent units a carboxylic acid-containing unsaturated vinyl monomer and an unsaturated vinyl monomer other than the carboxylic acid-containing unsaturated vinyl monomer.
A sizing agent may be used individually by 1 type, or may be used in combination of 2 or more type. Moreover, you may use together with common sizing agents, such as a urethane resin and an epoxy resin.

Specific examples of the carboxylic acid-containing unsaturated vinyl monomer include acrylic acid, methacrylic acid, fumaric acid, itaconic acid, maleic acid and the like, and acrylic acid is preferred.
In particular, mechanical strength and durability can be further improved by using acrylic acid as the carboxylic acid-containing unsaturated vinyl monomer.
A carboxylic acid containing unsaturated vinyl monomer may be used individually by 1 type, or may be used in combination of 2 or more type.
Specific examples of the carboxylic acid anhydride-containing unsaturated vinyl monomer include maleic acid or itaconic acid anhydride.
A carboxylic acid anhydride containing unsaturated vinyl monomer may be used individually by 1 type, or may be used in combination of 2 or more type.
In this embodiment, “(B) containing at least one acid component as a sizing agent for glass-based filler” means that (B) the surface of the glass-based filler is modified with at least one acid component. Means that

In the resin composition in the present embodiment, a component containing a resin is easily adhered to the surface of the glass-based filler. Therefore, a glass-based filler is obtained as a residue by dissolving the resin molded body in a 1/1 (volume ratio) mixed solvent of hexafluoroisopropyl alcohol (HFIP) and chloroform and removing the supernatant liquid. When the residual glass-based filler is analyzed by pyrolysis GC-MS at 600 ° C., the acid component can be detected.
It is to be noted that the acid component can be similarly detected using pellets after kneading extrusion of (A) polyacetal resin and (B) glass-based filler.

In the present embodiment, (B) the glass-based filler may be surface-modified with a coupling agent.
A coupling agent is not specifically limited, A well-known thing can be used.
Specific examples of the coupling agent include organic silane compounds, organic titanate compounds, and organic aluminate compounds.
A coupling agent may be used individually by 1 type, or may be used in combination of 2 or more type.

Specific examples of the organic silane compound include vinyltriethoxysilane, vinyl-tris- (2-methoxyethoxy) silane, γ-methacryloxypropylmethoxysilane, γ-aminopropyltrimethoxysilane, and γ-aminopropyltriethoxy. Silane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltriethoxysilane, γ-glycidoxypropylmethoxysilane, γ-mercaptopropyltrimethoxysilane Etc.
Among them, vinyltriethoxysilane, vinyl-tris- (2-methoxyethoxy) silane, γ-methacryloxypropylmethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, and γ-glycidoxy Propylmethoxysilane is preferred. Vinyltriethoxysilane, γ-glycidoxypropylmethoxysilane, and γ-aminopropyltriethoxysilane are preferred from the viewpoints of economy and thermal stability of the resin composition.

  Specific examples of the organic titanate compound include tetra-i-propyl titanate, tetra-n-butyl titanate, butyl titanate dimer, tetrastearyl titanate, triethanolamine titanate, titanium acetylacetonate, titanium lactate, and octylene bricol titanate. And isopropyl (N-aminoethylaminoethyl) titanate.

  Specific examples of the organic aluminate compound include acetoalkoxyaluminum diisopropylate.

  By using a glass-based filler surface-treated with a coupling agent, the creep resistance of the molded body tends to be further increased, and the thermal stability of the molded body tends to be further improved.

<(C) Formaldehyde scavenger>
The polyacetal resin composition of the present embodiment preferably includes (C) a formaldehyde scavenger. (C) Specific examples of formaldehyde scavengers include compounds containing formaldehyde-reactive nitrogen, such as melamine and polyamide resins, and polymers thereof, alkali metal or alkaline earth metal hydroxides, inorganic acid salts, carvone And acid salts and hydrazide compounds.
More specifically, the compound containing formaldehyde-reactive nitrogen and the polymer thereof are a polymer or compound (monomer) having a nitrogen atom capable of reacting with formaldehyde in the molecule.

For example, polyamide resins such as nylon 4-6, nylon 6, nylon 6-6, nylon 6-10, nylon 6-12, nylon 12, and polymers thereof, such as nylon 6 / 6-6 / 6-10 Nylon 6 / 6-12.
Examples of the compound containing formaldehyde-reactive nitrogen and the polymer thereof include acrylamide and derivatives thereof, and copolymers of acrylamide and derivatives thereof with other vinyl monomers. Examples thereof include poly-β-alanine copolymers obtained by polymerizing acrylamide and its derivatives and other vinyl monomers in the presence of metal alcoholate.
Further, the polymer or compound having formaldehyde-reactive nitrogen includes amide compounds, amino-substituted triazine compounds, adducts of amino-substituted triazine compounds and formaldehyde, condensates of amino-substituted triazine compounds and formaldehyde, urea, urea derivatives, Examples thereof include 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- And butyl-sym-triazine.
Specific examples of the adduct of the amino-substituted triazine compound and formaldehyde include N-methylol melamine, N, N′-dimethylol melamine, and N, N ′, N ″ -trimethylol melamine.
Specific examples of the condensate of the amino-substituted triazine compound and formaldehyde include melamine / formaldehyde condensate.

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 substituted with a substituent such as an alkyl group, alkylenebisurea, and aryl-substituted urea.
Specific examples of the urea condensate include a condensate of urea and formaldehyde.
Specific examples of the hydantoin compound include hydantoin, 5,5-dimethylhydantoin, and 5,5-diphenylhydantoin.
A specific example of the ureido compound is allantoin.
Specific examples of the imide compound include succinimide, glutarimide, and phthalimide.
These polymers or compounds having formaldehyde-reactive nitrogen may be used alone or in combination of two or more.

(C) The addition amount of the formaldehyde scavenger is preferably 0.01-5 parts by mass with respect to 100 parts by mass of the (A) polyacetal resin, and is a polymer containing formaldehyde-reactive nitrogen. In the case of 0.01 mass part-3 mass parts and the alkaline earth metal fatty acid salt, it is more preferable in the range of 0.01 mass part-1 mass part.
As a hydrazide compound, if it has a hydrazine structure (NN) which has a single bond between nitrogen atoms, it will not specifically limit, A well-known thing can be used.
For example, hydrazine; hydrazine hydrate; succinic acid monohydrazide, glutaric acid monohydrazide, adipic acid monohydrazide, pimelic acid monohydrazide, speric acid monohydrazide, azelaic acid monohydrazide, sebacic acid monohydrazide, etc .; Succinic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, pimelic acid dihydrazide, superic acid dihydrazide, azelaic acid dihydrazide, sebacic acid dihydrazide, dodecanedioic acid dihydrazide dihydrazide
Monoolefinic unsaturated dicarboxylic acid dihydrazide such as maleic acid dihydrazide, fumaric acid dihydrazide, itaconic acid dihydrazide; aromatic carboxylic acid dihydrazide such as isophthalic acid dihydrazide, phthalic acid dihydrazide, 2,6-naphthalenedicarbodihydrazide; pyromellitic acid Trihydrazides such as trimer acid trihydrazide, cyclohexanetricarboxylic acid trihydrazide, benzenetricarboxylic acid trihydrazide, nitrilotriacetic acid trihydrazide, citric acid trihydrazide;
Tetrahydrazide such as pyromellitic acid tetrahydrazide, naphthoic acid tetrahydrazide, ethylenediaminetetraacetic acid tetrahydrazide, 1,4,5,8-naphthoic acid tetrahydrazide; low polymer having a carboxylic acid lower alkyl ester group as hydrazine or hydrazine water A polyhydrazide such as polyhydrazide obtained by reacting with a compound (hydrazine hydrate);
Carbonic acid dihydrazide; bissemicarbazide; diisocyanates such as hexamethylene diisocyanate and isophorone diisocyanate and polyisocyanate compounds derived therefrom are excessively reacted with N, N-substituted hydrazines such as N, N-dimethylhydrazine and / or hydrazides exemplified above. A polyfunctional semicarbazide obtained by
It is obtained by excessively reacting any of the above dihydrazides with an isocyanate group in a reaction product of the polyisocyanate compound and an active hydrogen compound containing a hydrophilic group such as polyether polyols or polyethylene glycol monoalkyl ethers. Aqueous polyfunctional semicarbazide; a mixture of the above polyfunctional semicarbazide and the above aqueous polyfunctional semicarbazide; bisacetyldihydrazone and the like.

As a hydrazide compound which comprises the polyacetal resin composition of this embodiment, it is preferable that it is a carboxylic acid hydrazide, and it is more preferable that it is a saturated aliphatic carboxylic acid hydrazide.
Examples of the saturated aliphatic carboxylic acid hydrazide include succinic acid monohydrazide, glutaric acid monohydrazide, adipic acid monohydrazide, pimelic acid monohydrazide, speric acid monohydrazide, azelaic acid monohydrazide, sebacic acid monohydrazide and the like. Hydrazides; carboxylic acid dihydrazides such as succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, pimelic acid dihydrazide, superic acid dihydrazide, azelaic acid dihydrazide, sebacic acid dihydrazide, dodecanedioic acid dihydrazide and the like.

Content of the hydrazide compound which comprises a polyacetal resin composition is 0.01-5 mass parts with respect to 100 mass parts of polyacetal homopolymer mentioned above.
If the amount is less than 0.01 parts by mass, the amount of formaldehyde released tends to increase. If the amount exceeds 5 parts by mass, mold deposits in the mold tend to be easily generated in the production of automobile parts. is there.
The hydrazide compound is preferably 0.015 to 0.3 parts by mass, more preferably 0.02 to 0.2 parts by mass, with respect to 100 parts by mass of the polyacetal resin. More preferably, it is 0.1 mass part.
In addition, in the obtained polyacetal resin composition, the reaction product from carboxylic acid dihydrazide may be contained. Examples of such a reaction product include a reaction product of carboxylic acid dihydrazide and formaldehyde.

<(D) Weathering agent>
The polyacetal resin composition of the present embodiment preferably contains (D) a weathering agent. Specific examples of (D) weathering agents include hindered amine stabilizers and ultraviolet absorbers.
The polyacetal resin composition of the present embodiment preferably further includes 0.01 to 5 parts by mass of a hindered amine stabilizer and / or 0.01 to 5 parts by mass of an ultraviolet absorber with respect to 100 parts by mass of the polyacetal resin. .

<Hindered amine stabilizer>
It is preferable that the polyacetal resin composition of this embodiment contains 0.01-5 mass parts hindered amine stabilizer with respect to 100 mass parts of polyacetal resin. Although it does not specifically limit as a hindered amine stabilizer, For example, the piperidine derivative which has a sterically hindered group is mentioned. The piperidine derivative having a sterically hindered group is not particularly limited, and examples thereof include an ester group-containing piperidine derivative, an ether group-containing piperidine derivative, and an amide group-containing piperidine derivative. The polyacetal resin composition of the present embodiment is excellent in mechanical properties such as fluidity, impact resistance of the molded article, and weather resistance (light stability) by including a specific amount of a hindered amine stabilizer. It will be a thing.

The ester group-containing piperidine derivative is not particularly limited, and examples thereof include aliphatic acyloxypiperidine, aromatic acyloxypiperidine, aliphatic di- or tricarboxylic acid-bis or tripiperidyl ester, and aromatic di-, tri-, or tetracarboxylic acid-bis. , Tris or tetrakispiperidyl esters.
Specific examples of the aliphatic acyloxypiperidine are not particularly limited. For example, 4-acetoxy-2,2,6,6-tetramethylpiperidine, 4-stearoyloxy-2,2,6,6-tetramethylpiperidine, C2-20 aliphatic acyloxy-tetramethylpiperidine such as 4-acryloyloxy-2,2,6,6-tetramethylpiperidine.
Specific examples of the aromatic acyloxypiperidine are not particularly limited, and examples thereof include C7-11 aromatic acyloxytetramethylpiperidine such as 4-benzoyloxy-2,2,6,6-tetramethylpiperidine.

  Specific examples of the aliphatic di- or tricarboxylic acid-bis or tripiperidyl ester are not particularly limited, and examples thereof include bis (2,2,6,6-tetramethyl-4-piperidyl) oxalate, bis (2,2, 6,6-tetramethyl-4-piperidyl) malonate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) [[3,5-bis (1,1-dimethylethyl) -4-hydroxy Phenyl] methyl] butyl malonate, bis (2,2,6,6-tetramethyl-4-piperidyl) adipate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) adipate, bis (1 -Methyl-2,2,6,6-tetramethyl-4-piperidyl) adipate, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1 2,2,6,6-pentamethyl-4-piperidyl) sebacate, bis (1-octyloxy-2,2,6,6-tetramethyl-4-piperidyl sepacate, bis (2,2,6) decanedioate , 6-tetramethyl-1- (octyloxy) -4-piperidinyl) ester and the like C2-20 aliphatic dicarboxylic acid-bispiperidyl ester.

Specific examples of the aromatic di-, tri- or tetracarboxylic acid-bis, tris or tetrakispiperidyl ester are not particularly limited, and examples thereof include bis (2,2,6,6-tetramethyl-4-piperidyl) terephthalate and tris. Aromatic di- or tricarboxylic acid-bis or tripiperidyl esters such as (2,2,6,6-tetramethyl-4-piperidyl) benzene-1,3,5-tricarboxylate. In addition to the above, tetrakis (1,2,2,6,6-pentamethyl-4-piperidyl) 1,2,3,4-butanetetracarboxylate is also exemplified as an ester group-containing biperidine derivative.
In the present specification, “Ca-b” means that the carbon number is a to b (a and b are integers), for example, “C 2-20” has 2 to 20 carbon atoms. Means that.

The ether group-containing piperidine derivative is not particularly limited, and examples thereof include C1-10 alkoxypiperidine, C5-8 cycloalkyloxypiperidine, C6-10 aryloxypiperidine, C6-10 aryl-C1-4 alkyloxypiperidine, and alkyl. Range oxybispiperidine. Specific examples of C1-10 alkoxypiperidine are not particularly limited, and examples thereof include C1-6 alkoxy-tetramethylpiperidine such as 4-methoxy-2,2,6,6-tetramethylpiperidine.
Specific examples of C5-8 cycloalkyloxypiperidine are not particularly limited, and examples thereof include 4-cyclohexyloxy-2,2,6,6-tetramethylpiperidine. Specific examples of C6-10 aryloxypiperidine are not particularly limited, and examples thereof include 4-phenoxy-2,2,6,6-tetramethylpiperidine. Specific examples of the C6-10 aryl-C1-4 alkyloxypiperidine are not particularly limited, and examples thereof include 4-benzyloxy-2,2,6,6-tetramethylpiperidine.
Specific examples of the alkylenedioxybispiperidine are not particularly limited, but examples thereof include C1-10 alkylenedioxybis such as 1,2-bis (2,2,6,6-tetramethyl-4-piperidyloxy) ethane. And piperidine.

  The amide group-containing piperidine derivative is not particularly limited. For example, carbamoyloxypiperidine such as 4- (phenylcarbamoyloxy) -2,2,6,6-tetramethylpiperidine, bis (2,2,6,6- And carbamoyloxy-substituted alkylenedioxy-bispiperidine such as tetramethyl-4-piperidyl) hexamethylene-1,6-dicarbamate.

  Further, the hindered amine stabilizer is not particularly limited. For example, dimethyl-1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine polycondensate of succinate, 1,2 , 3,4-Butanetetracarboxylic acid, 1,2,2,6,6-pentamethyl-4-piperidinol and tridecyl alcohol, and 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 High molecular weight piperidine derivative polycondensates such as condensates with) -diethanol can also be used.

  In addition, the hindered amine stabilizer is not particularly limited. For example, N, N ′, N ″, N ″ -tetrakis- (4,6-bis- (butyl- (N-methyl-2,2) , 6,6-tetramethylpiperidin-4-yl) amino) -triazin-2-yl) -4,7-diazadecane-1,10-diamine, 1- [2- {3- (3,5-di-) t-butyl-4-hydroxyphenyl) propionyloxy} ethyl] -4- {3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy} -2,2,6,6- Tetramethylpiperidine, a reaction product of peroxidized 4-butylamino-2,2,6,6-tetramethylpiperidine and 2,4,6-trichloro-1,3,5-triazine and cyclohexane The reaction product of , N'- ethane-1,2-diyl bis (the 1,3-propane diamine), include the reaction product of.

  A hindered amine stabilizer is used individually by 1 type or in combination of 2 or more types. In the polyacetal resin composition of the present embodiment, the content of the hindered amine stabilizer is preferably 0.01 to 5 parts by mass, more preferably 0.1 to 2 parts by mass with respect to 100 parts by mass of the polyacetal resin. More preferably, it is 0.1 to 1.5 parts by mass. By adjusting the content of the hindered amine stabilizer to the above range, a molded product (for example, an automobile part) obtained from the polyacetal resin composition can maintain an even better appearance.

<Ultraviolet absorber>
It is preferable that the polyacetal resin composition of this embodiment contains 0.01-5 mass parts ultraviolet absorber with respect to 100 mass parts of polyacetal resins. By containing the specific amount of the ultraviolet absorber, a molded article (for example, an automobile part) obtained from the polyacetal resin composition has improved weather resistance (light stability). Although it does not specifically limit as a ultraviolet absorber, For example, a benzotriazole type compound, a benzophenone type compound, an oxalic acid anilide type compound, and a hydroxyphenyl-1,3,5-triazine type compound are mentioned.

Although it does not specifically limit as a benzotriazole type compound, For example, 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-t-butyl) Phenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-t-amylphenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-diisoamylphenyl) benzotriazole, etc. Benzotriazoles having a hydroxyl group and an alkyl group (preferably a C1-6 alkyl group) substituted aryl group;
Benzotriazoles having a hydroxyl group and an aralkyl group or an aryl group-substituted aryl group, such as 2- [2′-hydroxy-3 ′, 5′-bis (α, α-dimethylbenzyl) phenyl] benzotriazole; 2- ( Benzotriazoles having a hydroxyl group and an alkoxy group (preferably a C1-12 alkoxy group) substituted aryl group such as 2′-hydroxy-4′-octoxyphenyl) benzotriazole are exemplified.
Among the benzotriazole compounds, among the above, benzotriazoles having a hydroxyl group and a C3-6 alkyl group-substituted C6-10 aryl group (particularly a phenyl group), and a hydroxyl group and C6-10 aryl-C1-6 Benzotriazoles having an alkyl group (particularly a phenyl C1-4 alkyl group) and a substituted aryl group are preferred.

The benzophenone-based compound is not particularly limited, and examples thereof include benzophenones having a plurality of hydroxyl groups; benzophenones having a hydroxyl group and an alkoxy group (preferably a C1-16 alkoxy group). Specific examples of benzophenones having a plurality of hydroxyl groups include, but are not limited to, for example, di-, tri- or tetrahydroxybenzophenones such as 2,4-dihydroxybenzophenone; hydroxyl groups such as 2-hydroxy-4-benzyloxybenzophenone And benzophenones having a hydroxyl-substituted aryl or aralkyl group.
Further, specific examples of benzophenones having a hydroxyl group and an alkoxy group are not particularly limited. For example, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4- Examples include dodecyloxybenzophenone, 2,2′-dihydroxy-4-methoxybenzophenone, 2,2′-dihydroxy-4,4′-dimethoxybenzophenone, and 2-hydroxy-4-methoxy-5-sulfobenzophenone.

Among the above, benzophenone compounds include benzophenones having a hydroxyl group and a hydroxyl group-substituted C6-10 aryl group or a C6-10 aryl-C1-4 alkyl group, particularly a hydroxyl group and a hydroxyl group-substituted phenyl C1-2. Benzophenones having an alkyl group are preferred.
Although it does not specifically limit as an oxalic acid anilide type compound, For example, N- (2-ethylphenyl) -N '-(2-ethoxy-5-t-butylphenyl) oxalic acid diamide, N- (2-ethylphenyl) ) -N ′-(2-ethoxy-phenyl) oxalic acid diamide.

  The hydroxyphenyl-1,3,5-triazine compound is not particularly limited. For example, 2,4-diphenyl-6- (2-hydroxyphenyl) -1,3,5-triazine, 2,4-diphenyl -6- (2,4-dihydroxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy-4-methoxyphenyl) -1,3,5-triazine, 2,4 -Diphenyl-6- (2-hydroxy-4-ethoxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy-4-propoxyphenyl) -1,3,5-triazine 2,4-diphenyl-6- (2-hydroxy-4-butoxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy-4-hexyloxy) Phenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy-4-octyloxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2- Hydroxy-4-dodecyloxyphenyl) -1,3,5-triazine.

  In the polyacetal resin composition of the present embodiment, the content of the ultraviolet absorber is preferably 0.01 to 5 parts by mass, more preferably 0.1 to 2 parts by mass with respect to 100 parts by mass of the polyacetal resin. Yes, more preferably 0.1 to 1.5 parts by mass.

  Among the above, as the hindered amine stabilizer, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (2,2,6,6-tetramethyl-4-piperidyl) -sebacate, 1,2,3,4-butanetetracarboxylic acid, 1,2,2,6,6-pentamethyl-4-piperidinol and β, β, β ′, β′-tetramethyl-3,9- (2,4 , 8,10-tetraoxabis [5,5 ′] undecane) diethanol is particularly preferred, and the UV absorber is more preferably a benzotriazole compound, and 2- [2′-hydroxy-3 ′, 5′-bis (α, α-dimethylbenzyl) phenyl] benzotriazole is particularly preferred.

  The polyacetal resin composition of this embodiment preferably contains an ultraviolet absorber and a hindered amine stabilizer. In this case, the ratio of the hindered amine stabilizer and the ultraviolet absorber is preferably 10/90 to 80/20, more preferably 10/90 to 70/30, and still more preferably 20/20 in terms of the former / the latter (mass ratio). It is in the range of 80-60 / 40.

<Stabilizer>
The polyacetal resin composition of the present embodiment may contain various stabilizers that are usually used in the polyacetal resin composition as long as the object of the present invention is not impaired.
The stabilizer is not particularly limited, and specific examples include an antioxidant and a formic acid scavenger.
A stabilizer may be used individually by 1 type, or may be used in combination of 2 or more type.
As the antioxidant, a hindered phenol antioxidant is preferable from the viewpoint of improving the thermal stability of the molded article. It does not specifically limit as a hindered phenolic antioxidant, A well-known thing can be used suitably.
The addition amount of the antioxidant is preferably 0.1 parts by mass or more and 2 parts by mass or less with respect to 100 parts by mass of the (A) polyacetal resin.

Specific examples of the formic acid scavenger include alkali metal or alkaline earth metal hydroxides, inorganic acid salts, and carboxylate salts.
More specifically, calcium hydroxide, calcium carbonate, calcium phosphate, calcium silicate, calcium borate, fatty acid calcium salts (calcium stearate, calcium myristate, etc.) and the like can be mentioned. These fatty acids may be substituted with hydroxyl groups.
The amount of formic acid scavenger added is 0.1 to 3 parts by mass of a polymer containing formaldehyde and formic acid scavenger formaldehyde-reactive nitrogen with respect to 100 parts by mass of the polyacetal resin (A). The earth metal fatty acid salt is preferably in the range of 0.1 to 1 part by mass.

<Other ingredients>
The molded product of the polyacetal resin of the present embodiment is a filler other than a known glass-based filler (talc, wollastonite, mica, and the like conventionally used in polyacetal resin compositions, as long as the object of the present invention is not impaired. , Calcium carbonate, etc.), conductivity imparting agents (carbon black, graphite, carbon nanotubes, etc.), colorants (titanium oxide, zinc oxide, iron oxide, aluminum oxide, organic dyes, etc.), slide imparting agents (various ester compounds) , Organic acid metal salts, etc.), ultraviolet absorbers, light stabilizers, and various stabilizers such as a lubricant.
The addition amount of the other components is preferably 30% by mass or less when the polyacetal resin is 100% by mass for the filler other than glass fiber, the conductivity imparting agent, and the colorant. About an ultraviolet absorber, a light stabilizer, and a lubricating material, Preferably it is 5 mass% or less with respect to 100 mass% of polyacetal resins.
Other components may be used alone or in combination of two or more.

<Method for producing molded body>
The molded body of this embodiment can be produced by a known method. Specifically, it can be produced by mixing, melt-kneading and molding the raw material components with a uniaxial or multi-axial kneading extruder, roll, Banbury mixer or the like as follows. Among these, a twin-screw extruder equipped with a decompression device and a side feeder facility can be preferably used.
A method for mixing and melt-kneading the raw material components is not particularly limited, and methods known to those skilled in the art can be used. Specifically, component (A) and component (B) are premixed with a super mixer, tumbler, V-shaped blender, etc., and melt melt-kneaded with a twin screw extruder, and component (A) is twin screw extruded. Examples include a method of adding the component (B) from the middle of the extruder while being supplied to the machine main throat and melt-kneaded. Any of these can be used, but in order to improve the mechanical properties of the molded article of the present embodiment, the component (A) is supplied to the main throat part of the twin-screw extruder and melt-kneaded, from the middle of the extruder ( A method of adding the component B) is preferred. Since the optimum conditions vary depending on the size of the extruder, it is preferable to appropriately adjust the conditions within a range that can be adjusted by those skilled in the art. More preferably, the screw design of the extruder is adjusted in various ways within a range adjustable by those skilled in the art.

  The molding method for obtaining the molded body in the present embodiment is not particularly limited, and a known molding method can be used. Specifically, extrusion molding, injection molding, vacuum molding, blow molding, injection compression molding, decorative molding, other material molding, gas assist injection molding, foam injection molding, low pressure molding, ultra-thin injection molding (ultra-high-speed injection) Molding), in-mold composite molding (insert molding, outsert molding), or any other molding method.

[Usage]
The polyacetal resin composition of the present embodiment can be used as a raw material for a molded product that requires mechanical strength and durability.
The molded body of the present embodiment can be suitably used as a part for automobiles, and can be particularly suitably used for a part that plays a role as a gear or pulley that comes into contact with other members.
Besides these, it can be applied to known uses as a use of polyacetal resin. Specific examples include cams, sliders, levers, arms, clutches, felt clutches, idler gears, rollers, rollers, key stems, key tops, shutters, reels, shafts, joints, shafts, bearings, doors, guides, etc. Mechanical parts: resin parts for outsert molding, resin parts for insert molding, chassis, trays, side plates, automobile parts such as door locks, door handles, window regulators, window regulator wire drums, speaker grills, glass holders, etc. Parts around the door; seat belt peripheral parts such as slip rings for seat belts, press buttons, etc .; parts such as combination switch parts, switches, clips, etc. Instead of gasoline tanks, fuel pump modules, valves, gasoline tank flanges, etc. Parts for office automation equipment represented by fuel-related parts, printers and copiers; parts for video equipment such as digital video cameras and digital cameras; CDs, DVDs, Blu-ray (registered trademark) Discs, and other optical discs It can be applied to music, video or information equipment represented by navigation systems and mobile personal computers, parts for communication equipment represented by mobile phones and facsimiles, parts for electrical equipment, parts for electronic equipment, and the like. In addition, as pens and pens for writing utensils, other mechanical parts; wash basins, drain outlets, drain plug opening / closing mechanism parts; cord stoppers for clothes, adjusters, buttons; nozzles for sprinkling, sprinkling hose connection joints; stairs Building supplies that support railings and floor materials; toys, fasteners, chains, conveyors, buckles, sporting goods, vending machines (opening / closing part locking mechanism, product discharge mechanism parts), furniture, musical instruments, housing equipment parts Etc.

Hereinafter, the present embodiment will be specifically described by way of examples and comparative examples. However, the present embodiment is not limited to these examples and comparative examples as long as the gist thereof is not exceeded.
The production conditions and evaluation items of the polyacetal resin compositions and molded bodies used in Examples and Comparative Examples are as follows.

(1) Extrusion Ratio of screw length L to screw diameter D (L / D) = 48 (barrel number 12), side feeders are provided in the sixth barrel and the eighth barrel, and a vacuum vent is provided in the eleventh barrel. The same direction rotating twin screw extruder (TEM-48SS extruder manufactured by Toshiba Machine Co., Ltd.) was used. The first barrel was water cooled, the second to fifth barrels were set to 210 ° C, and the sixth to twelfth barrels were set to 180 ° C.
The screw used for extrusion was designed as follows. Two kneading discs (hereinafter abbreviated as RKD), which have a flight screw (hereinafter abbreviated as FS) at the positions of the first to fourth barrels and have a feeding capacity at the position of the fifth barrel, have no feeding capacity Two kneading discs (hereinafter abbreviated as NKD) and one kneading disc (hereinafter abbreviated as LKD) capable of feeding in the reverse direction were arranged in this order. FS was arranged at the positions of the sixth to eighth barrels, RKD and NKD were arranged one by one at the position of the ninth barrel in this order, and FS was arranged at the positions of the tenth to eleventh barrels.
The glass-based filler was supplied from the side feeder of the sixth barrel, and the extrusion was performed at a screw rotation speed of 150 rpm and a total extrusion amount of 70 kg / h.

(2) Creation of compact molded body in the shape of a small tensile test piece Using an injection molding machine (EC-75NII, manufactured by Toshiba Machine Co., Ltd.), the cylinder temperature was set to 205 ° C., the injection time was 35 seconds, and the cooling time was 15 By molding under the second injection conditions, a compact body in the form of a small tensile test piece conforming to ISO294-2 was obtained. The mold temperature was 90 ° C. A compact in the form of a small tensile test piece conforming to ISO294-2 was used in the following measurements (3) and (8).
As a specimen for a creep resistance test used for the following (4) measurement of creep rupture time, a compact molded specimen having a shape of a small tensile specimen in accordance with JIS K7139-5A was obtained. The mold temperature was 90 ° C. Further, a flat plate having a length of 60 mm × width of 60 mm × thickness of 5 mm was similarly formed and used in the measurement of (8) below.

(3) Tensile Fracture Stress Using the molded body obtained in (2) above, a tensile test was performed at a tensile speed of 5 mm / min in accordance with ISO 527-1 to measure the tensile fracture stress.

(4) Creep resistance Using a molded body which is a test piece for creep resistance test obtained in (2) above, using a creep tester (manufactured by Toyo Seiki Seisakusho Co., Ltd.) in an 80 ° C. environment, A creep test was performed by applying a load of 30 MPa, and the time until breaking was measured. The measurement was performed three times, and the average was taken as the creep rupture time. The larger the value, the better the creep resistance.

(5) SFD (Spiral Flow Distance)
Using an injection molding machine (ROBOSHOT α-50iA manufactured by FANUC CORPORATION), the cylinder temperature is set to 200 ° C., the mold temperature is set to 80 ° C., and the SFD of each composition with an injection pressure of 80 MPa is set using a 2 mm thick SFD mold. evaluated. The longer the SFD value, the better the fluidity.

(6) Molding machine limit residence time Using an injection molding machine (EC5P, manufactured by Toshiba Machine Co., Ltd.), it was retained in the injection molding machine under the following conditions, and the time when silver streak occurred was measured. Evaluation was performed.
(A) Molding conditions Cylinder set temperature: 230 ° C
Mold temperature: 80 ℃
Molding cycle: Injection / cooling = 30 seconds / 15 seconds Test piece: 127 mm × 12.7 mm × 3 mm
(B) Thermal stability measurement and evaluation method The polyacetal resin composition was plasticized and melted in an injection molding machine set to the above molding conditions, and the molten resin was retained in the injection molding machine.
Thereafter, the molten resin retained in the injection molding machine is injection molded at regular intervals, the surface state of the obtained molded product is visually observed, and the thermal stability is evaluated with the occurrence of silver streak or discolored residence time. Went.
If the residence time was 30 minutes or longer, it was judged that the thermal stability was excellent.

(7) Amount of formaldehyde released from the molded body Using an injection molding machine (IS-100GN, manufactured by Toshiba Machine Co., Ltd.), cylinder temperature: condition 1 = 200 ° C., condition 2 = 220 ° C., injection pressure 70 MPa, injection Specimens with dimensions specified from the polyacetal resin compositions obtained in Examples and Comparative Examples described later under the conditions of time: 15 seconds, cooling time: 20 seconds, mold temperature: 80 ° C. (length 100 mm × width 40 mm) × Thickness 3 mm) was molded.
The amount of formaldehyde released from the obtained test piece was measured according to the following VDA275 method, and the amount of formaldehyde released from the molded article was determined.
In the VDA275 method, first, 50 mL of distilled water and the test piece were accommodated in a polyethylene container and sealed. Next, after heating the container at 60 ° C. for 3 hours, formaldehyde in distilled water is reacted with acetylacetone in the presence of ammonium ions, and the absorption peak at a wavelength of 412 nm is measured with a UV spectrometer for the reaction product. The amount of formaldehyde released (mg / kg) was determined.

(8) Weather resistance Using the molded product obtained in the above (2), a weather resistance acceleration test was performed by Sunshine Super Long Life Weather Meter, manufactured by Suga Test Instruments Co., Ltd. The accelerated test was performed by irradiating the molded product with ultraviolet rays in an environment of 63 ° C. Further, water was sprayed onto the molded product for a time corresponding to 20% of the irradiation time. The molded product was removed from the weather meter after 58 days, and the surface irradiated with ultraviolet rays was observed. The number of cracks was counted. The smaller the number of cracks, the better the weather resistance.

(9) Measurement of terminal OH group concentration 10 mg of polyacetal resin pellets were placed in a mixed solvent of 0.5 mL of pexafluoroisopropyl alcohol (HFIP) and 0.5 mL of chloroform and left overnight. Subsequently, the solution was heated at 40 ° C. for 4 hours, 0.2 mL of N, O-bis (trimethylsilyl) trifluoroacetamide (BSTFA) was added and heated for 2.5 hours. Thereafter, the solvent was air-dried overnight, and the solvent was completely removed by vacuum drying at 80 ° C.
This sample was dissolved in deuterated hexafluoroisopropyl alcohol (HFIP-d ₁ ) 0.4 mL and deuterated chloroform (CDCl ₃ ) 0.4 mL and heated to 55 ° C. To this, 20 μm of deuterated pyridine was added to prepare a sample for ¹ H-NMR measurement. ¹ H-NMR measurement was performed using ECA500 manufactured by JEOL.
The concentration of the terminal OH group is based on the integral value of 4.95 ppm derived from methoxy of the main chain of the polyacetal resin, and the end of hemiformal terminal (0.228 ppm), ethylene glycol terminal (0.172 ppm), other chain transfer agent-derived terminal It was calculated from the integrated value of OH (in the case of A7 in the example, 0.203 ppm). The obtained value was divided by 30 g / mol of main chain methoxy to obtain a terminal OH group concentration (mmol / kg).

The raw material components of the polyacetal resin compositions and molded bodies used in Examples and Comparative Examples will be described below.
(A1)
A biaxial self-cleaning type polymerization machine with a jacket through which a heat medium can pass (L / D = 8 (L: distance (m) from raw material supply port to discharge port of polymerization machine, D: inner diameter of polymerization machine ( m) The same applies hereinafter))) to 80 ° C. In the polymerizer, trioxane is 4 kg / hour, 1,3-dioxolane is 128.3 g / hour as a comonomer (3.9 mol% with respect to 1 mol of trioxane), ethylene glycol is used as a chain transfer agent with respect to 1 mol of trioxane, 1 × 10 ⁻³ mol.
Further, boron trifluoride di-n-butyl etherate as a polymerization catalyst was continuously added to the polymerizer at 1.5 × 10 ⁻⁵ mol with respect to 1 mol of trioxane, and polymerization was performed.
The polyacetal copolymer discharged from the polymerization machine was put into a 0.1% aqueous solution of triethylamine to deactivate the polymerization catalyst.
The polyacetal copolymer having deactivated the polymerization catalyst was filtered with a centrifuge, and choline hydroxide formate (triethyl-2-hydroxyethylammonium formate) as a quaternary ammonium compound with respect to 100 parts by mass of the polyacetal copolymer. After adding 1 part by mass of an aqueous solution containing bismuth and mixing uniformly, it was dried at 120 ° C. Here, the addition amount of the hydroxycholine formate was 20 mass ppm in terms of the nitrogen amount. In addition, adjustment of the addition amount of the hydroxy choline formate was performed by adjusting the density | concentration of the hydroxy choline formate in the aqueous solution containing the hydroxy choline formate to add.

The dried polyacetal copolymer was fed into a vented twin screw extruder. 0.5 parts by weight of water was added to 100 parts by weight of the melted polyacetal copolymer in the extruder, and the unstable terminal portion of the polyacetal copolymer was removed at a preset temperature of the extruder of 200 ° C. and a residence time of 7 minutes in the extruder. Decomposition and removal were performed.
0.3 parts by mass of triethylene glycol-bis- [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) -propionate] as an antioxidant was added to the polyacetal copolymer with the unstable terminal portion decomposed. It was added and extruded as a strand from the die section of the extruder while being devolatilized under a condition of a vacuum of 20 Torr with an extruder equipped with a vent, and pelletized.
In this way, polyacetal resin (A1) was obtained. Moreover, MFR based on JISK7210 (190 degreeC, 2.16kg conditions) of a polyacetal resin (A1) was 10 g / 10min, and the density | concentration of the terminal OH group was 4.3 mmol / kg.

(A2)
With the method (A1), the chain transfer agent ethylene glycol was 3 × 10 ⁻³ mol per 1 mol of trioxane. In this way, polyacetal resin (A2) was obtained. Moreover, MFR based on JISK7210 (190 degreeC, 2.16kg conditions) of a polyacetal resin (A2) was 35 g / 10min, and the density | concentration of the terminal OH group was 14.5 mmol / kg.

(A3)
By the method (A1), the chain transfer agent ethylene glycol was adjusted to 3.5 × 10 ⁻³ mol with respect to 1 mol of trioxane. In this way, polyacetal resin (A3) was obtained. Moreover, MFR based on JISK7210 (190 degreeC, 2.16kg conditions) of a polyacetal resin (A3) was 40 g / 10min, and the density | concentration of the terminal OH group was 15.5 mmol / kg.

(A4)
By the method (A1), the chain transfer agent ethylene glycol was adjusted to 1.0 × 10 ⁻² mol per 1 mol of trioxane. In this way, polyacetal resin (A4) was obtained. Moreover, MFR based on JISK7210 (190 degreeC, 2.16kg conditions) of a polyacetal resin (A4) was 60 g / 10min, and the density | concentration of the terminal OH group was 60.0 mmol / kg.

(A5)
In the method (A1), ethylene glycol was used as a chain transfer agent, and the amount was 2.0 × 10 ⁻² mol with respect to 1 mol of trioxane. In this way, polyacetal resin (A5) was obtained. Moreover, MFR based on JISK7210 (190 degreeC, 2.16kg conditions) of a polyacetal resin (A5) was 100 g / 10min, and the density | concentration of the terminal OH group was 120.0 mmol / kg.

(A6)
The polyacetal block copolymer was prepared as follows. A twin-screw paddle type continuous polymerization machine with a jacket through which a heat medium can pass was adjusted to 80 ° C. Boron trifluoride di-n-butyl etherate dissolved in cyclohexane as a formal catalyst was dissolved in cyclohexane as a formal, and 3 × 10 ^{− An} amount of ⁵ moles, a hydrogenated polybutadiene (number average molecular weight Mn = 2,330) represented by the following formula (5) as a chain transfer agent is 3.5 × 10 ⁻³ moles per mole of trioxane. In such an amount, polymerization was carried out by continuously supplying the polymerizer.

Next, the polymer discharged from the polymerization machine was put into a 1% aqueous solution of triethylamine to completely deactivate the polymerization catalyst, and then the polymer was filtered and washed to obtain a crude polyacetal block copolymer.
To 100 parts by mass of the obtained crude polyacetal block copolymer, 1 part by mass of an aqueous solution containing a quaternary ammonium compound (described in Japanese Patent No. 3087912) was added and mixed uniformly. The amount of the quaternary ammonium compound added was 20 mass ppm in terms of nitrogen. This was supplied to a twin screw extruder with a vent, and 0.5 parts by mass of water was added to 100 parts by mass of the melted polyacetal block copolymer in the extruder. The unstable terminal portion of the polyacetal block copolymer was decomposed and removed at an extruder set temperature of 200 ° C. and a residence time of 7 minutes in the extruder.

To the polyacetal block copolymer in which the unstable terminal portion is decomposed, 0.3 parts by mass of triethylene glycol-bis- [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) -propionate] as an antioxidant Was extruded as a strand from the extruder die and pelletized while devolatilizing under a condition of a vacuum of 20 Torr with an extruder equipped with a vent.
The polyacetal block copolymer thus obtained was used as (A3) polyacetal block copolymer. This block copolymer was an ABA type block copolymer, MFR based on JIS K7210 (190 degreeC, 2.16kg conditions) was 45 g / 10min, and the density | concentration of the terminal OH group was 15.9 mmol / kg.

(B) The following were used for the glass-based filler.
(B1) Glass fiber treated with a sizing agent (containing a copolymer of acrylic acid and methyl acrylate) described in Production Example 1 of Japanese Patent No. 4060831.
(B2) Glass fiber treated with polymethyl acrylate alone as a sizing agent using the method described in Production Example 1 of Japanese Patent No. 4060831.
(B3) Glass fiber treated with polymaleic acid alone as a sizing agent using the method described in Production Example 1 of Japanese Patent No. 4060831.
(B4) Sample No. of Japanese Unexamined Patent Publication No. 2009-7179. A glass fiber treated with the sizing agent according to 1 (containing no acid).

(C) Formaldehyde scavenger (C1) Nippon Finechem Co., Ltd. SDH (Sebacic acid dihydrazide)
(C2) Melamine (D) weathering agent manufactured by Nissan Chemical Industries, Ltd. (D1) Sanol LS770 manufactured by Sankyo Lifetech Co., Ltd.
(E) Others (E1) Methylenediphenyl-4,4′-diisocyanate (MDI)

[Examples 1-9, Comparative Examples 1-6]
Extrusion was performed so that each component had a ratio described in Table 1 or Table 2, and a resin composition was produced. Using the obtained resin composition, molding was performed under the above conditions to produce a molded body. The results of evaluating each physical property are shown in Tables 1 and 2.

Examples 1 to 9 were found to be compositions having high tensile fracture stress and excellent tensile creep properties, which are static durability indicators. In addition, the molding fluidity is good, and expansion to molding of large products is expected. Furthermore, even if it is retained in a molding machine, it is a high-quality composition that is unlikely to cause silver streaks or discoloration.
When comparing Examples 1 to 4 and Comparative Examples 1 to 3, (A) The higher the terminal OH group concentration of the polyacetal resin, the higher the tensile fracture stress, but the tensile creep has an optimum region of terminal OH group concentration. I found out. Also, when the terminal OH group concentration of the (A) polyacetal resin is low, the fluidity during molding is poor. On the other hand, when the terminal OH group concentration is high, retention during molding tends to cause silver streak and discoloration. I found out that
When Examples 1 and 9 are compared with Comparative Examples 4 and 5, (B) as a sizing agent for the glass-based filler, polyacrylic acid or polymaleic acid, which are acid components, is contained, so that tensile fracture stress and tensile creep are included. It was found that the performance can be improved. In particular, the effect was obtained most when polyacrylic acid-containing material was used.

  Comparing Examples 1 and 7 and Comparative Example 3, it was found that the value of VDA275, which is an index of VOC properties, was lowered by adding a formaldehyde scavenger. Moreover, not only the VOC property but also the effect of improving the tensile creep property, which is durability, and extending the residence time of the molding machine were also seen. On the other hand, when the terminal OH group concentration of the (A) polyacetal resin exceeded the desired range, a significant decrease in VOC properties was observed.

When Examples 1 and 8 and Comparative Example 3 were compared, the weather resistance was improved by adding a weathering agent. Moreover, not only the weather resistance, but also the effects of improving the tensile creep property and extending the molding machine residence time were observed. On the other hand, when the terminal OH group concentration of the (A) polyacetal resin exceeded the desired range, a significant decrease in weather resistance was observed.
In contrast to Examples 1 and 5, even if the terminal OH groups of the polyacetal resin are at substantially the same concentration, by adding a specific block component in the polyacetal resin, the tensile creep property can be improved and the molding fluidity can be improved. The effect of improvement and extension of molding machine residence time was also obtained.
In the evaluation of the molding machine residence time of Comparative Example 6, since the color change started in about 10 minutes and became brown in 15 minutes, the test was stopped.

  The polyacetal resin composition and molded article of the present invention have industrial applicability in various fields in which the polyacetal resin is suitably used, particularly in the field of automobile mechanism parts that require durability and high quality.

Claims (8)

A polyacetal resin composition comprising (A) 100 parts by mass of a polyacetal resin and (B) 10 to 100 parts by mass of a glass-based filler,
(A) The polyacetal resin composition in which the terminal OH group concentration of the polyacetal resin exceeds 15 and is 100 mmol / kg or less, and (B) contains at least one acid component as a sizing agent for the glass-based filler.   The polyacetal resin composition of Claim 1 whose acid component of the sizing agent of the said (B) glass-type filler is carboxylic acid.   The polyacetal resin composition according to claim 1 or 2, wherein an acid component of the sizing agent of the (B) glass-based filler is acrylic acid.   The polyacetal resin composition according to any one of claims 1 to 3, further comprising 0.01 to 5 parts by mass of (C) a formaldehyde scavenger with respect to 100 parts by mass of the (A) polyacetal resin.   The polyacetal resin composition of any one of Claims 1-4 which contains 0.01-5 mass parts of (D) weathering agents further with respect to 100 mass parts of said (A) polyacetal resin.   The polyacetal resin composition according to any one of claims 1 to 5, wherein the (A) polyacetal resin contains a block component.   The polyacetal resin composition according to claim 6, wherein the block component is a hydrogenated polybutadiene component.   The molded object containing the polyacetal resin composition of any one of Claims 1-7.