JP2018131568A - Polyoxymethylene resin composition and molded product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyoxymethylene resin composition which has excellent weather-resistant stability and reduces a formaldehyde emission amount and also reduces a formaldehyde emission amount during molding residence.SOLUTION: There is provided a polyoxymethylene resin composition which comprises 100 pts.mass of a polyoxymethylene resin homopolymer (A), 0.05 to 0.5 pt.mass of a nitrogen-containing compound having formaldehyde capturing performance (B), 0.1 to 0.5 pt.mass of an ultraviolet absorber (C), 0.1 to 0.5 pt.mass of a hindered amine-based light stabilizer (D), 0.01 to 0.05 pt.mass of an antioxidant (E), 0.01 to 0.1 pt.mass of a lubricant (F) and 0.1 to 1.0 pt.mass of a polyolefin resin (G), wherein the mass ratio between the lubricant (F) and the polyolefin resin (G) is 5/95 to 30/70.SELECTED DRAWING: None

Description

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

The polyoxymethylene resin is a crystalline resin and is a resin material excellent in rigidity, strength, toughness, slidability, and creep properties.
The use of polyoxymethylene resin is widespread as a resin material for various mechanical parts such as automobile parts, electric / electronic parts and industrial parts.

  However, polyoxymethylene resin is very weak against light energy such as sunlight and heat energy, and when exposed to the atmosphere for a long time, there is a problem that cracks occur on the surface of the molded product, causing a decrease in strength. ing. Therefore, when used in an environment exposed to sunlight or the like, it is general to add a weathering stabilizer such as a hindered amine compound.

By the way, in recent years, there has been an increasing demand for miniaturization, thinning, and precision in molded products of polyoxymethylene resin, and in order to satisfy these requirements, molding is performed under molding conditions that are more susceptible to thermal history than before. Tend to be performed.
Examples of such a molding method include molding by a pin gate mold and high cycle molding. In these molding methods, screw rotation or molding is performed in order to increase the shear rate or shorten the plasticizing time. In order to raise the temperature, the polyoxymethylene resin receives a higher thermal history than the conventional normal molding method.

Also in other general molding methods, when molding defects such as flow marks, weld lines, jetting, etc. occur, it is often the case that the resin temperature is raised. High thermal history is a factor for oxymethylene resins.
Further, when a hot runner is used in the mold in the molding step, the resin temperature further rises due to partial retention of the resin, and the resin may be decomposed.

And, as described above, when molding a polyoxymethylene resin by setting a molding method and molding conditions that require various heat histories, a weather stabilizer is added to the polyoxymethylene resin to improve its weather resistance stability. When added, there is a problem that it becomes difficult to achieve a good balance of properties in relation to thermal stability. That is, when a large amount of a weather stabilizer is added with an emphasis on weather stability, there is a problem that thermal stability is deteriorated and volatile organic compounds (VOC) containing formaldehyde are easily released from the resin.
In particular, in the field of automobile interior parts, there is an increasing demand for reducing the amount of volatile organic compounds released, and a resin composition having an excellent balance between weather resistance stability and thermal stability is required. Is the current situation.

By the way, in order to improve the weather resistance stability of the polyoxymethylene resin, various techniques have been conventionally proposed.
For example, a technique using a hindered amine light stabilizer and an oxalic acid anilide ultraviolet absorber (see Patent Document 1 below), a technique using a hindered amine light stabilizer and a benzophenone ultraviolet absorber (see Patent Document 2 below), benzo Technology that uses a triazole ultraviolet absorber and a hindered amine light stabilizer in combination (see Patent Document 3 below), Technology that uses various ultraviolet absorbers, fatty acid esters and hindered amine light stabilizers in combination (see Patent Document 4 below), and benzo The technique (refer patent document 5 below) etc. which use a triazole type ultraviolet absorber, a hindered amine type light stabilizer, and antioxidant together are mentioned.

  Moreover, as a technique for reducing the amount of formaldehyde released from a polyoxymethylene resin molded product, for example, a technique of adding a polyamide and a hydrazine derivative (see Patent Document 6 below), a technique of adding a hydrazide compound (see Patent Document 7 below) , A technique for adding a nitrogen compound selected from melamine and melamine derivatives and dicarboxylic acid hydrazide (see Patent Document 8 below), a technique for adding benzoguanamine (see Patent Document 9 below), a fatty acid part of a polyhydric alcohol compound on the pellet surface A method of attaching an ester (see Patent Document 10 below), a technique of adding mono N-substituted urea (see Patent Document 11 below), a technique of adding a carboxyl group-containing compound having an acid dissociation index of 3.6 or more (Patent Document below) Reference 12), phenols, basic nitrogen-containing compounds and aldehydes A technique for adding a condensate with a hydrazine (see Patent Document 13 below), a technique for adding hydantoin or imidazole (see Patent Document 14 below), and a technique for adding a low molecular weight amino compound having a base dissociation index of 2 to 8 ( The following patent document 15) etc. are proposed.

  In addition, as a technique for reducing weather stability and formaldehyde released from a molded article, a technique for adding a hydrazide compound such as a hindered amine light stabilizer having a specific structure, an ultraviolet absorber and an aromatic hydrazide compound (Patent Document 16 below) And a technology for adding a weathering agent (hindered amine light stabilizer and ultraviolet absorber) and a hydrazide compound to a polyoxymethylene resin in which the amount of formaldehyde generated is suppressed (see Patent Document 17 below).

JP 57-98545 A JP 59-133245 A JP 60-195155 A JP 61-47744 A Japanese Patent Laid-Open No. 6-157871 Japanese Patent Laid-Open No. 51-111857 JP-A-4-345648 Japanese Patent No. 3024802 JP-A-62-190248 JP-A-6-107900 JP-A-11-335519 JP 2000-239484 A JP 2002-212384 A Japanese Patent No. 3310467 Japanese translation of PCT publication No. 2002-541288 JP 2006-232937 A JP 2006-306944 A

However, the techniques disclosed in Patent Documents 1 to 5 all have improved weather resistance stability, but have a problem that the amount of formaldehyde released from the molded product of polyoxymethylene resin is not sufficiently reduced. .
Moreover, the techniques disclosed in Patent Documents 6 to 15 have a problem that the weather resistance stability is not sufficient.
Furthermore, although the techniques disclosed in Patent Documents 16 and 17 have improved effects with regard to weatherability stability and reduction of formaldehyde emission, the polyoxymethylene resin composition is retained in the molding machine cylinder during the molding process. There is room for improvement in reducing the amount of formaldehyde released from the molded product at the time, and in particular, there is a reduction in the amount of formaldehyde released from the molded product when the polyoxymethylene resin homopolymer composition is retained in the molding machine cylinder. Has the problem of not enough.

  Therefore, in the present invention, a polyoxymethylene resin composition having excellent weather resistance stability and reduced formaldehyde emission amount, and having reduced formaldehyde emission amount during molding processing residence and molded product The purpose is to provide.

As a result of intensive studies to solve the above problems, the present inventors have found that a polyoxymethylene resin homopolymer, a nitrogen-containing compound having formaldehyde scavenging ability, an ultraviolet absorber, a hindered amine light stabilizer, and an antioxidant. The present inventors have found that a polyoxymethylene resin composition containing a specific amount of a lubricant and a polyolefin-based resin can solve the conventional problems described above, and has completed the present invention.
That is, the present invention is as follows.

[1]
100 parts by mass of a polyoxymethylene resin homopolymer (A),
0.05 to 0.5 parts by mass of a nitrogen-containing compound (B) having formaldehyde capturing ability;
UV absorber (C) 0.1-0.5 parts by mass,
0.1 to 0.5 parts by mass of a hindered amine light stabilizer (D),
Antioxidant (E) 0.01-0.05 parts by mass;
Lubricant (F) 0.01-0.1 part by mass;
0.1 to 1.0 part by mass of polyolefin resin (G),
Containing,
The mass ratio of the (F) lubricant to the (G) polyolefin resin is (F) lubricant / (G) polyolefin resin = 5/95 to 30/70.
Polyoxymethylene resin composition.
[2]
In the above [1], the nitrogen-containing compound (B) having a formaldehyde scavenging ability is at least one selected from the group consisting of amino-substituted triazine compounds, urea derivatives, amide compounds, polyamides, and acrylamide copolymers. The polyoxymethylene resin composition described.
[3]
The molded object containing the polyoxymethylene resin composition as described in said [1] or [2].

  According to the present invention, it is possible to provide a polyoxymethylene resin composition that has excellent weather resistance stability and reduced formaldehyde emission amount, and also has reduced formaldehyde emission amount during residence in molding process. It is possible to provide a molded article excellent in continuous productivity.

Hereinafter, a mode for carrying out the present invention (hereinafter referred to as “the present embodiment”) will be described in detail.
In addition, the following this embodiment is an illustration for demonstrating this invention, and is not the meaning which limits this invention to the following content. The present invention can be implemented with various modifications within the scope of the gist.

[Polyoxymethylene resin composition]
The polyoxymethylene resin composition of the present embodiment is
100 parts by mass of a polyoxymethylene resin homopolymer (A),
0.05 to 0.5 parts by mass of a nitrogen-containing compound (B) having formaldehyde capturing ability;
UV absorber (C) 0.1-0.5 parts by mass,
0.1 to 0.5 parts by mass of a hindered amine light stabilizer (D),
Antioxidant (E) 0.01-0.05 parts by mass;
Lubricant (F) 0.01-0.1 part by mass;
0.1 to 1.0 part by mass of polyolefin resin (G),
Containing,
The mass ratio of the (F) lubricant to the (G) polyolefin resin is (F) lubricant / (G) polyolefin resin = 5/95 to 30/70.

(Polyoxymethylene resin homopolymer (A))
The polyoxymethylene resin composition of the present embodiment contains a polyoxymethylene resin homopolymer (A).
The polyoxymethylene resin homopolymer (A) refers to a polymer having an oxymethylene group in the main chain, and is particularly preferably a polyoxymethylene homopolymer in which both ends of a polymer chain are blocked with ester groups. .
The amount of formaldehyde generated in the polyoxymethylene resin homopolymer (A) at 230 ° C. under a nitrogen atmosphere is preferably 0.001 to 2.0% by mass. More preferably, the amount of formaldehyde generated is 0.001 to 1.0 mass%, and further preferably 0.001 to 0.8 mass%.
When the amount of formaldehyde generated from the polyoxymethylene resin homopolymer (A) is in the above range, the polyoxymethylene resin composition has a reduced amount of formaldehyde released, and the amount of formaldehyde released when the molding process remains is also reduced. The obtained polyoxymethylene resin composition can be obtained, and a molded article excellent in continuous productivity can be provided.
.

Formaldehyde generation amount of the polyoxymethylene resin homopolymer (A) at 230 ° C. under a nitrogen environment is mainly the amount of formaldehyde released from hydroxyl groups (—OH) which are unstable terminal groups, It can be quantified by the method shown below.
In a 230 ° C. oil bath, polyoxymethylene resin placed in a SUS container having piping is immersed for 90 minutes. Thereafter, nitrogen gas is allowed to flow through the pipe, formaldehyde gas generated by thermal decomposition is taken out, absorbed in an aqueous sodium sulfite solution, and titrated with sulfuric acid to determine the amount of formaldehyde generated.

  Further, the melt flow rate (based on ISO 1133 D) of the polyoxymethylene resin composition of the present embodiment is preferably 0.5 g / 10 min or more from the viewpoint of molding processability, and from the viewpoint of durability. It is preferably 10 g / 10 min or less, more preferably 1.0 g / 10 min to 7 g / 10 min, and even more preferably 1.5 g / 10 min to 4 g / 10 min.

(Production of polyoxymethylene resin homopolymer (A))
The polyoxymethylene resin homopolymer (A) can be produced, for example, by performing a polymerization step and a terminal stabilization step described later.

<(1) Polymerization step>
In the polymerization step, a monomer is produced using a chain transfer agent or a polymerization catalyst in a reactor by a known slurry polymerization method (for example, the method described in Japanese Patent Publication Nos. 47-6420 and 47-10059). To obtain a crude polyoxymethylene resin homopolymer whose terminal is not stabilized.
In addition, as the material of the polyoxymethylene resin composition of the present embodiment, the crude polyoxymethylene resin homopolymer itself can be used, but the terminal of the crude polyoxymethylene resin homopolymer is obtained by the terminal stabilization step described later. It is preferable to use a stabilized product.

[(1) Monomer]
Examples of the monomer used for the production of the polyoxymethylene resin homopolymer include formaldehyde.

In order to continuously obtain a polyoxymethylene resin homopolymer having a stable molecular weight in the polymerization step, it is preferable to use a purified formaldehyde gas which is purified and has a low impurity concentration.
As a purification method of formaldehyde, a known method (for example, a method described in Japanese Patent Publication No. 5-32374 and Japanese Patent Publication No. 2001-521916) can be applied.

When formaldehyde gas is used as a monomer in the polymerization step, it is preferable to use water, methanol, formic acid, or the like that does not contain impurities having a polymerization stopping action and a chain transfer action during the polymerization reaction as much as possible.
By using a formaldehyde gas with few impurities, an unexpected chain transfer reaction can be avoided, and a polyoxymethylene resin homopolymer having a target molecular weight can be obtained. In particular, the content of impurities that induce hydroxyl groups in the polymer end groups is preferably 100 ppm by mass or less, and more preferably 50 ppm by mass or less, based on the total amount of monomers.

[(2) Chain transfer agent]
Although it does not specifically limit as a chain transfer agent used for manufacture of a polyoxymethylene resin homopolymer, For example, alcohol and acid anhydride are mentioned.
As the chain transfer agent, it is preferable to use a material that contains as little impurities as possible, such as water, methanol, formic acid, and acetic acid, which have a polymerization stopping action and a chain transfer action during the polymerization reaction. As a method for obtaining a chain transfer agent with few impurities, for example, a chain transfer agent that is widely used and has an available water content exceeding a specified amount is bubbled with dry nitrogen, and the impurities are removed with an adsorbent such as activated carbon or zeolite. And a purification method.
A chain transfer agent may be used individually by 1 type, and may use 2 or more types together.

[(3) Polymerization catalyst]
Although it does not specifically limit as a polymerization catalyst used for manufacture of a polyoxymethylene resin homopolymer, For example, an onium salt type polymerization catalyst etc. are mentioned.
Examples of the onium salt-based polymerization catalyst include compounds represented by the following general formula (1).
[R ₁ R ₂ R ₃ R ₄ M] ⁺ X ⁻ (1)
(In the general formula (1), R ₁ , R ₂ , R ₃ and R ₄ each independently represents an alkyl group, M represents an element having a lone pair, and X represents a nucleophilic group. R ₁ , R ₂ , R ₃ and R ₄ may be the same or different.)

  Examples of the onium salt-based polymerization catalyst include, but are not limited to, quaternary ammonium salt compounds and quaternary phosphonium salt compounds, and particularly tetramethylammonium bromide and dimethyl distearyl. Ammonium acetate, tetraethylphosphonium iodide, and tributylethylphosphonium iodide are preferred.

[(4) Reactor]
The reactor used for the production of the polyoxymethylene resin homopolymer is not particularly limited. For example, a reaction tank with a batch type stirrer, a continuous type kneader, a twin screw type continuous extrusion kneader, a twin screw paddle type continuous A mixer etc. are mentioned.
It is preferable that the reactor has a structure on the outer periphery of the barrel that can heat or cool a reaction mixture such as a jacket.

<(2) Terminal stabilization step>
In the terminal stabilization step, the end of the crude polyoxymethylene resin homopolymer obtained in the polymerization step is converted into an ether group with an etherifying agent by a known method (for example, the method described in JP-B-63-452). And / or blocked with an ester group by an esterifying agent and stabilized.

  Although it does not specifically limit as an etherifying agent in the case of blocking with an ether group, For example, orthoester etc. are mentioned.

Examples of the orthoester include, but are not limited to, for example, orthoesters of aliphatic acid or aromatic acid and aliphatic alcohol, alicyclic alcohol, or aromatic alcohol. Include methyl or ethyl orthoformate, methyl or ethyl orthoacetate and methyl or ethyl orthobenzoate, and orthocarbonates such as ethyl orthocarbonate.
Only one etherifying agent may be used alone, or two or more etherifying agents may be used in combination.

The reaction of blocking with an etherifying agent, that is, the etherification reaction is a Lewis acid such as medium-strength organic acids such as p-toluenesulfonic acid, acetic acid and hydrobromic acid, and medium-strength mineral acids such as dimethyl and diethyl sulfate. The acid type catalyst may be introduced by introducing 0.001 to 0.02 parts by mass with respect to 1 part by mass of the etherifying agent.
In the etherification reaction, for example, but not limited to, low-boiling point aliphatics such as pentane, hexane, cyclohexane and benzene; alicyclic and aromatic hydrocarbons; halogenation such as methylene chloride, chloroform and carbon tetrachloride An organic solvent such as a lower aliphatic compound can be used.

  As a method for stabilizing the terminal by blocking the terminal of the crude polyoxymethylene resin homopolymer with an ester group, for example, a large amount of acid anhydride described in US Pat. No. 3,459,709 is used in a slurry state. And a method performed in a gas phase using an acid anhydride gas described in US Pat. No. 3,172,736.

  Although it does not specifically limit as an esterifying agent in the case of blocking with an ester group, For example, an organic acid anhydride etc. are mentioned.

Examples of the organic acid anhydride include organic acid anhydrides represented by the following general formula (2).
R ₅ COOCOR ₆ (2)
(In general formula (2), R ₅ and R ₆ each independently represents an alkyl group or a phenyl group. R ₅ and R ₆ may be the same or different.)

Examples of organic acid anhydrides include, but are not limited to, propionic anhydride, benzoic anhydride, acetic anhydride, succinic anhydride, maleic anhydride, glutaric anhydride, phthalic anhydride, and the like. Acetic anhydride is preferred.
An esterifying agent may be used individually by 1 type, and may use 2 or more types together.

  As a method for performing end-capping with an ester group in the gas phase, it is preferable to perform end-capping after removing the onium salt-based polymerization catalyst by, for example, the method described in JP-A-11-92542. By removing the onium salt-based polymerization catalyst in polyoxymethylene, it is possible to avoid the decomposition reaction of the polyoxymethylene resin homopolymer derived from the onium salt-based polymerization catalyst when end-capping, thus stabilizing the terminal. The polymer yield in the crystallization step can be improved, and coloring of the polyoxymethylene resin homopolymer can be suppressed.

It is preferable that the terminal of the polyoxymethylene resin homopolymer is blocked with an ether group and / or an ester group so that the concentration of the terminal hydroxyl group is reduced to 5 × 10 ⁻⁷ mol / g or less. When the concentration of the terminal hydroxyl group is 5 × 10 ⁻⁷ mol / g or less, the thermal stability is excellent and the quality of the original polyoxymethylene resin homopolymer can be maintained, which is preferable. From the same viewpoint, the concentration of the terminal hydroxyl group is more preferably 0.5 × 10 ⁻⁷ mol / g or less, and further preferably 0.3 × 10 ⁻⁷ mol / g or less.

(Nitrogen-containing compound having formaldehyde scavenging ability (B))
The polyoxymethylene resin composition of this embodiment contains a nitrogen-containing compound (B) having formaldehyde scavenging ability.
Examples of the nitrogen-containing compound (B) having formaldehyde scavenging ability include, but are not limited to, amino-substituted triazine compounds, urea derivatives, amide compounds, polyamides, and acrylamide copolymers.
These may be used alone or in combination of two or more.

The content of the nitrogen-containing compound (B) having formaldehyde scavenging ability is in the range of 0.05 to 0.5 parts by mass with respect to 100 parts by mass of the polyoxymethylene resin homopolymer (A), preferably 0.8. It is the range of 08-0.4 mass part, More preferably, it is the range of 0.1-0.3 mass part.
When the content of the nitrogen-containing compound (B) having formaldehyde scavenging ability is in the above range, the polyoxymethylene resin composition has a reduced formaldehyde emission amount, and the formaldehyde emission amount during the staying in the molding process is also reduced. A polyoxymethylene resin composition can be provided, and a molded article excellent in continuous productivity can be provided.

  Examples of the amino-substituted triazine compound include, but are not limited to, 2,4-diamino-sym-triazine, 2,4,6-triamino-sym-triazine, melamine, 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.

Examples of the urea derivative include, but are not limited to, N-substituted urea, urea condensate, ethylene urea, hydantoin compound, ureido compound, and the like.
Examples of the N-substituted urea include, but are not limited to, methylurea having a substituent such as an alkyl group, alkylenebisurea, and aryl-substituted urea.
Examples of the urea condensate include, but are not limited to, urea and formaldehyde condensates.
Examples of the hydantoin compound include, but are not limited to, hydantoin, 5,5-dimethylhydantoin, and 5,5-diphenylhydantoin.
Examples of the ureido compound include, but are not limited to, allantoin.

  Examples of the amide compound include, but are not limited to, polyvalent carboxylic acid amides such as isophthalic acid diamide, anthranilamides, and polyacrylamide copolymers.

  Examples of the polyamide include, but are not limited to, polyamide 4,6, polyamide 6, polyamide 66, polyamide 11, polyamide 12, polyamide 6,10, polyamide 6,11, polyamide 6,12, polyamide A terpolymer of 6,66,610 may be mentioned.

The acrylamide copolymer is preferably in the form of particles having a primary amide group content of 30 to 70 mol% and an average particle size of 0.1 to 10 μm.
A particularly preferred acrylamide copolymer is a crosslinked polyacrylamide having an average particle size of 10 μm or less. More preferably, it is a polyacrylamide having an average particle diameter of 5 μm or less, and even more preferably, it is a cross-linked polyacrylamide having an average particle diameter of 3 μm or less.

By using the polyamide and acrylamide copolymer in combination, the continuous productivity of the polyoxymethylene resin composition tends to be further improved.
Among the polyamides, polyamide 6/66/610 terpolymer having a melting point near the processing temperature of the polyacetal resin (melting point: 176 ° C.), polyamide 66 (melting point: 265 ° C.), polyamide 6 (melting point: 230 ° C.) ) Is preferred. A more preferable polyamide is a terpolymer of polyamide 6/66/610 (melting point: 176 ° C.).

(Ultraviolet absorber (C))
The polyoxymethylene resin composition of this embodiment contains an ultraviolet absorber (C).
Examples of the ultraviolet absorber (C) include, but are not limited to, benzotriazole-based ultraviolet absorbers and oxalic anilide-based ultraviolet absorbers.
These may be used alone or in combination of two or more.

Content of a ultraviolet absorber (C) is the range of 0.1-0.5 mass part with respect to 100 mass parts of polyoxymethylene resin homopolymer (A), Preferably it is 0.15-0.4. It is the range of a mass part, More preferably, it is the range of 0.2-0.35 mass part.
When the content of the ultraviolet absorber (C) is in the above range, it is possible to provide a polyoxymethylene resin composition in which the amount of formaldehyde released during molding processing retention is reduced, and to provide a molded article excellent in continuous productivity. it can.

Examples of the benzotriazole-based ultraviolet absorber include, but are not limited to, 2- (2′-hydroxy-5′-methyl-phenyl) benzotriazole and 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 the oxalic acid alinide-based ultraviolet absorber include, but are not limited to, 2-ethoxy-2′-ethyloxalic acid bisanilide, 2-ethoxy-5-tert-butyl-2′-ethyloxalic, for example. Acid bisanilide, 2-ethoxy-3'-dodecyl oxalic acid bisanilide, etc. are mentioned.

(Hindered amine light stabilizer (D))
The polyoxymethylene resin composition of the present embodiment contains a hindered amine light stabilizer (D).
Examples of the hindered amine light stabilizer (D) include, but are not limited to, 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, dibutylamine, 1,3,5-triazine, N , N′-bis (2,2,6,6-tetramethyl-4-piperidyl-1,6-hexamethylenediamine and N- (2,2,6,6-tetramethyl-4-piperidyl) butylamine Condensate, 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-piperidyl) imino}], a condensation product of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol, bis (2,2,6, decanoic acid) Reaction product of 6-tetramethyl-1 (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-pipe Jinoru and β, β, β ', β'- tetramethyl-3,9 [2,4,8,10-tetra oxa spiro (5,5) undecane] condensates of diethanol, and the like.
These may be used alone or in combination of two or more.

The content of the hindered amine light stabilizer (D) is in the range of 0.1 to 0.5 parts by mass, preferably 0.15 to 0 with respect to 100 parts by mass of the polyoxymethylene resin homopolymer (A). .4 parts by mass, and more preferably 0.2 to 0.35 parts by mass.
When the content of the hindered amine light stabilizer (D) is in the above range, it is possible to provide a polyoxymethylene resin composition in which the amount of formaldehyde released during molding processing retention is reduced, and to provide a molded product excellent in continuous productivity. be able to.

(Antioxidant (E))
The polyoxymethylene resin composition of this embodiment contains an antioxidant (E).
Examples of the antioxidant (E) include, but are not limited to, n-octadecyl-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) -propionate, n-octadecyl-3. -(3'-methyl-5-t-butyl-4'-hydroxyphenyl) -propionate, n-tetradecyl-3- (3 ', 5'-di-t-butyl-4'-hydroxyphenyl) -propionate, 1,6-hexanediol-bis- (3- (3,5-di-t-butyl-4-hydroxyphenyl) -propionate), 1,4-butanediol-bis- (3- (3,5-di-t -Butyl-4-hydroxyphenyl) -propionate), triethylene glycol bis- (3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) -propionate), tet Kis- (methylene-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionate methane, 3,9-bis (2- (3- (3-t-butyl-4 -Hydroxy-5-methylphenyl) propionyloxy) -1,1-dimethylethyl) 2,4,8,10-tetraoxaspiro (5,5) undecane, N, N'-bis-3- (3 ', 5'-di-t-butyl-4-hydroxyphenol) priionyl hexamethylenediamine, N, N'-tetramethylenebis-3- (3'-methyl-5'-t-butyl-4-hydroxyphenol) Propionyldiamine, N, N′-bis- (3- (3,5-di-t-butyl-4-hydroxyphenol) propionyl) hydrazine, N-salicyloyl-N′-salicylidenehydrazine, 3- (N— Salicyloyl ) Amino-1,2,4-triazole, N, N′-bis (2- (3- (3,5-di-butyl-4-hydroxyphenyl) propionyloxy) ethyl) oxyamide and the like.
Among the antioxidants, triethylene glycol bis- (3- (3-t-butyl-5-methyl-4-hydroxyphenyl) -propionate) and tetrakis- (methylene-3- (3 ′, 5 ′) -Di-t-butyl-4'-hydroxyphenyl) propionate methane is preferred.
These may be used alone or in combination of two or more.

Content of antioxidant (E) is the range of 0.01-0.05 mass part with respect to 100 mass parts of polyoxymethylene resin homopolymer (A), Preferably it is 0.015-0.045. It is the range of a mass part, More preferably, it is the range of 0.02-0.04 mass part.
When content of antioxidant (E) exists in the said range, the polyoxymethylene resin homopolymer composition excellent in a weather resistance can be provided.

(Lubricant (F))
The polyoxymethylene resin composition of the present embodiment contains a lubricant (F).
Although a lubricant (F) is not limited to the following, For example, the polyalkylene glycol and the aliphatic compound which has an amide group are mentioned.
These may be used alone or in combination of two or more.
Examples of the polyalkylene glycol include, but are not limited to, polyethylene glycol and polypropylene glycol. The molecular weight of the polyalkylene glycol can be selected according to the purpose, and generally a polyalkylene glycol having a molecular weight of 500 to 20000 can be used.
Examples of the aliphatic compound having an amide group include, but are not limited to, ethylene bispaltimic acid amide, ethylene bisstearic acid amide, ethylene bislauric acid amide, ethylene bisoleic acid amide, and ethylene biseruka Examples include acid amides.

The content of the lubricant (F) is in the range of 0.01 to 0.1 parts by mass, preferably 0.015 to 0.07 parts by mass with respect to 100 parts by mass of the polyoxymethylene resin homopolymer (A). More preferably, it is the range of 0.02-0.05 mass part.
When the content of the lubricant (F) is in the above range, it is a polyoxymethylene resin composition having weather resistance stability and reduced amount of formaldehyde released, and the amount of formaldehyde released at the time of molding processing residence is also reduced. In addition, a polyoxymethylene resin composition can be provided, and a molded article excellent in continuous productivity can be provided.

(Polyolefin resin (G))
The polyoxymethylene resin composition of the present embodiment contains a polyolefin resin (G).
The polyolefin resin (G) is not limited to the following. For example, polyethylene (high density polyethylene, medium density polyethylene, low density polyethylene, linear low density polyethylene, ultra low density polyethylene), polypropylene, ethylene -Propylene copolymer, ethylene-butene copolymer, ethylene-octene copolymer, polypropylene-butene copolymer, polybutene, polybutadiene hydrogenated product, ethylene-acrylic acid ester copolymer, ethylene-methacrylic acid ester Examples thereof include a copolymer and an ethylene-acrylic acid copolymer.
Further, the copolymer is not limited to the following, but, for example, a graft copolymer obtained by grafting one or more of other vinyl compounds, more specifically, polyethylene-g-polystyrene, ethylene Glycidyl methacrylate copolymer-g-polystyrene, low-density polyethylene-g-acrylonitrile styrene copolymer, polypropylene-g-acrylonitrile styrene copolymer, ethylene glycidyl methacrylate copolymer-g-acrylonitrile styrene copolymer, ethylene An ethyl acrylate copolymer-g-acrylonitrile styrene copolymer is mentioned.

Among these, polyethylene (high density polyethylene, medium density polyethylene, low density polyethylene, linear low density polyethylene, and ultra low density polyethylene) is preferable.
These polyolefin resins are not particularly limited, but the melt flow rate (based on JIS K7210-4) is preferably 0.01 g / 10 min to 150 g / 10 min, more preferably 0.1 g / 10 min to 120 g. / 10 minutes, more preferably 0.5 g / 10 minutes to 100 g / 10 minutes.
When the melt flow rate is 0.01 g / 10 min or more, the dispersibility in the molded product of the polyoxymethylene resin composition becomes good, and when the melt flow rate is 150 g / 10 min or less, the molded product hardly peels off.

Content of polyolefin resin (G) is the range of 0.1-1.0 mass part with respect to 100 mass parts of polyoxymethylene resin homopolymer (A), Preferably it is 0.15-0.5. It is the range of a mass part, More preferably, it is the range of 0.15-0.3 mass part.
When the content of the polyolefin resin (G) is within the above range, the polyoxymethylene resin composition has a reduced formaldehyde emission amount, and the polyoxymethylene resin composition also has a reduced formaldehyde emission amount during a molding process residence. Articles can be provided, and a molded article excellent in continuous productivity can be provided.

(Mass ratio of ((F) lubricant / (G) polyolefin resin))
In the polyoxymethylene resin composition of the present embodiment, the mass ratio of the lubricant (F) to the polyolefin resin (G), that is, the mass ratio of the lubricant (F) / olefin resin (G) is 5 / 95-30 / 70.
Moreover, 7 / 93-25 / 75 is preferable, More preferably, it is 10 / 90-20 / 80.
By setting the mass ratio within the above range, it is possible to provide a polyoxymethylene resin composition in which the amount of formaldehyde released is reduced and the amount of formaldehyde released at the time of molding processing residence is also reduced. It is possible to provide a molded article excellent in continuous productivity.

(Other ingredients)
Various additives such as pigments, dyes and various reinforcing materials can be further added to the polyoxymethylene resin composition of the present embodiment as long as the properties of the polyoxymethylene resin homopolymer are not impaired.

(Production method of polyoxymethylene resin composition)
The polyoxymethylene resin composition of the present embodiment can be produced by melting and kneading the above-described components (A) to (G) using, for example, a single screw extruder or a twin screw extruder, It can be obtained as products in various forms such as strands and pellets.

[Molded body]
The molded body of the present embodiment includes the polyoxymethylene resin composition of the present embodiment described above, and a desired molded body can be molded using the pellet-shaped product obtained as described above. .
The method for producing the molded body is not particularly limited, and a commonly used injection molding method or extrusion molding method can be applied.

Hereinafter, although a specific Example and a comparative example are given and this embodiment is described, this embodiment is not limited to the Example mentioned later.
Hereinafter, the evaluation method will be described.

〔Evaluation method〕
((1) Determination of formaldehyde generated from the molded product of polyoxymethylene resin composition (measurement of VDA275 value); before residence (average value of n = 3))
The pellets of the polyoxymethylene resin compositions obtained in the examples and comparative examples were injected into a cylinder set temperature of 220 ° C. injection molding machine (mold temperature: 80 ° C., gate size: 3 * 3 mm side gate) (Toshiba Machine) A test piece with a size of 100 * 40 * 3 mm was obtained using IS-100GN).
The molding cycle was 40 seconds / cycle for both injection and cooling.
The obtained molded body was left for one day in a thermostatic chamber adjusted to 50% humidity at 23 ° C.
After that, according to the method (conditions) stipulated by the German Automobile Manufacturers Association, VDA275 value (100 * 40mm flat plate test piece is hung in a 1 liter container, 50 ml of water is put in, sealed, heat-treated, The value obtained by quantifying formaldehyde gas absorbed in the water by chemical analysis was measured.
The heat treatment conditions were 60 ° C. for 3 hours, and the specimen size was 100 * 40 * 3 mm.

((2) Determination of formaldehyde generated from the molded product of polyoxymethylene resin composition (measurement of VDA275 value); after residence (average value of n = 3))
The pellets of the polyoxymethylene resin compositions obtained in the examples and comparative examples were injected into a cylinder set temperature of 220 ° C. injection molding machine (mold temperature: 80 ° C., gate size: 3 * 3 mm side gate) (Toshiba Machine) Made by using IS-100GN), and a test piece having a size of 100 * 40 * 3 mm was obtained.
The molding cycle was 40 seconds / cycle for both injection and cooling. The obtained molded body was left for one day in a thermostatic chamber adjusted to 50% humidity at 23 ° C.
After that, according to the method (conditions) stipulated by the German Automobile Manufacturers Association, VDA275 value (100 * 40mm flat plate test piece is hung in a 1 liter container, 50 ml of water is put in, sealed, heat-treated, The value obtained by quantifying formaldehyde gas absorbed in the water by chemical analysis was measured.
The heat treatment conditions were 60 ° C. for 3 hours, and the specimen size was 100 * 40 * 3 mm.

((3) Weather resistance)
The pellets of the polyoxymethylene resin compositions obtained in Examples and Comparative Examples were injected using an injection molding machine (Toshiki Machine, IS-100GN) with a cylinder set temperature of 215 ° C., injection pressure 72 MPa, injection time: 15 A test piece (ISO dumbbell piece) was obtained under the conditions of second, cooling time: 20 seconds, mold temperature: 90 ° C. Using the obtained test piece, a weather resistance test evaluation was performed.
A weather resistance tester (Sunshine Weather Meter S80 manufactured by Suga Test Instruments Co., Ltd.) was used, and the weather resistance test was performed under the conditions of a black panel temperature of 83 ° C., no rain, and an exposure time of 2000 hours.
Further, the tensile strength before and after the weather resistance test was measured according to ISO 527 (tensile tester: AG-IS manufactured by Shimadzu Corporation), and the tensile strength retention rate (%) was determined as an average value of n = 3.
Tensile strength retention (%) = tensile strength after weathering test / tensile strength before weathering test × 100
If the tensile strength retention was 95% or more, it was judged as practically good.

((4) Continuous productivity)
The pellets of the polyoxymethylene resin compositions obtained in Examples and Comparative Examples were injected using an injection molding machine (Toshiki Machine, IS-100GN) with a cylinder set temperature of 215 ° C., injection pressure 72 MPa, injection time: 15 The ISO dumbbell pieces were continuously injection molded under the conditions of seconds, cooling time: 20 seconds, mold temperature: 90 ° C.
The number of continuous molding was 5000 times, and the number of foreign dust particles of the ISO dumbbell from the last 4500 times to 5000 times was measured to obtain continuous productivity.
In this case, the foreign matter dust was assumed to be visible by 0.1 mm or more.
In addition, the relationship between the foreign dust and the continuous productivity was evaluated as follows.
I: Foreign matter dust is less than 20 per 500 dumbbell pieces, and the continuous productivity is very good.
II: There are 21 to 40 foreign dust pieces per 500 dumbbell pieces, and the continuous productivity is good.
III: Foreign matter dust is 41 or more per 500 dumbbell pieces, and the continuous productivity is poor.

[Ingredients used in Examples and Comparative Examples]
((A) polyoxymethylene resin homopolymer)
A formaldehyde homopolymer having an MFR value of 3 g / 10 min, an amount of formaldehyde generated of 0.6%, and a terminal group stabilized by acetylation was used.

((A ′) polyoxymethylene resin copolymer)
A twin-screw self-cleaning type polymerization machine (L / D = 8) with a jacket capable of passing a heat medium is adjusted to 80 ° C., 4 kg / hr of trioxane is added thereto, and 1,3-dioxolane is used as a comonomer. 8 g / h (0.013 mol with respect to 1 mol of trioxane), the addition amount of methylal as a chain transfer agent was adjusted so that the melt flow rate based on JIS K7210 of the polyacetal resin after polymerization was 3 g / 10 min.
Further, polymerization was performed by continuously adding boron trifluoride di-n-butyl etherate as a polymerization catalyst in an amount of 1.5 × 10 ⁻⁵ mol with respect to 1 mol of trioxane.
The polyacetal copolymer discharged from the polymerization machine was put into a 0.1% aqueous solution of triethylamine to deactivate the polymerization catalyst.
After filtering the polyacetal copolymer having deactivated the polymerization catalyst with a centrifuge, 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.
The dried polyacetal copolymer is supplied to a vented twin screw extruder, and 0.5 parts by mass of water is added to 100 parts by mass of the melted polyacetal copolymer in the extruder, and the extruder set temperature is 200 ° C. The unstable end portion was decomposed and removed under the condition of a residence time of 7 minutes in the extruder.
The polyacetal copolymer that had been subjected to the decomposition and removal treatment of the unstable end portion was devolatilized under the condition of a vent vacuum of 20 Torr, extruded as a strand from the die portion of the extruder, and pelletized.
The melting point of the pellet was 171 ° C. (DSC method).

((B) Nitrogen-containing compound having formaldehyde scavenging ability)
<B-1>: Polyamide 6/66/610 terpolymer <B-2>: Polyacrylamide compound
[Production method of B-2]
To a batch type 5 L reactor equipped with a stirrer, 2400 g of acrylamide, 267 g of methylenebisacrylamide and 0.54 g of zirconium tetraisopropoxide (1/10000 mol with respect to acrylamide) as a catalyst were added and stirred while stirring in an N2 stream. The reaction was carried out at 4 ° C for 4 hours.
After completion of the reaction, the solid was pulverized with a jet mill pulverizer and washed with acetone.
Thereafter, it was dried under reduced pressure at 120 ° C. for 20 hours at a reduced pressure of −700 mmHg. The content of primary amide group was 44.7 mol%, and the average particle size was 5.0 μm. The average particle size of the acrylamide copolymer <B-2> was measured with a laser diffraction particle size distribution analyzer.
<B-3>: Hydantoin <B-4>: Melamine

((B ′) heat stabilizer composed of other than nitrogen-containing compound)
<B′-5>: Calcium stearate <B′-6>: Calcium citrate

((C) UV absorber)
2- [2′-Hydroxy-3 ′, 5′-bis (α, α-dimethylbenzyl) phenyl] benzotriazole

((D) hindered amine light stabilizer)
1,2,3,4-butanetetracarboxylic acid, 1,2,2,6,6-pentamethyl-4-piperidinol, β, β, β ′, β′-tetramethyl-3,9- (2 , 4,8,10-tetraoxaspiro [5,5] undecane) -diethanol

((E) Antioxidant)
Triethylene glycol-bis- (3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) -propionate)

((F) lubricant)
<F-1>: Ethylene bis stearic acid amide (EBS) (manufactured by NOF Corporation)
<F-2>: Polyethylene glycol (PEG) (manufactured by NOF Corporation: number average molecular weight 6,000)

((G) polyolefin resin)
<G-1>: Suntech LD L-1850A (LDPE) [Vicat softening point 87 ° C., MFR 6.7 g / 10 min] (manufactured by Asahi Kasei Chemicals)
<G-2>: Suntech HD J-320 (HDPE) [Vicat softening point 123 ° C., MFR 12.0 g / 10 min] (manufactured by Asahi Kasei Chemicals)

[Example 1]
100 parts by mass of polyoxymethylene resin homopolymer (A), 0.05 part by mass of nitrogen-containing compound (B-1), 0.3 part by mass of ultraviolet absorber (C), hindered amine light stabilizer (D) 0. 2 parts by mass, 0.03 parts by mass of antioxidant (E), 0.02 parts by mass of lubricant (F-1), 0.18 parts by mass of olefin resin (G-1) (F-1 / G-1 = 10/90) was uniformly mixed using a Henschel mixer to obtain a mixture.
The mixture was melt-kneaded with a 30φ single-screw extruder, extruded into a strand, cooled, and pelletized to obtain resin composition pellets composed of a polyoxymethylene resin homopolymer composition.
The obtained resin composition pellets were dried at 80 ° C. for 4 hours.
Using the dried resin composition pellets, <(1) and (2) determination of formaldehyde released from the molded body; before residence, after residence>, <(3) weather resistance>, <(4) continuous productivity > Was evaluated by the various evaluation methods.
The evaluation results are shown in Table 1.
The extrusion conditions were as follows: the cylinder set temperature was 200 ° C., the discharge rate was 5 kg / hr, the screw rotation speed was 50 rpm, and the vent pressure reduction was −720 mmHg.

[Examples 2 to 16]
The composition was changed as described in Table 1 or Table 2. Other conditions were the same as in [Example 1].
The evaluation results are shown in Tables 1 and 2.

[Comparative Examples 1-16]
The composition was changed as described in Table 1 or Table 2. Other conditions were the same as in [Example 1].
The evaluation results are shown in Tables 1 and 2.

  As is apparent from the evaluation results in Tables 1 and 2, the polyoxymethylene resin homopolymer (A), the nitrogen-containing compound (B) having formaldehyde scavenging ability, the ultraviolet absorber (C), and hindered amine light The stabilizer (D), the antioxidant (E), the lubricant (F), and the polyolefin resin (G) have a predetermined content, and the mass ratio of the lubricant (F) / olefin resin (G) is In the examples within the scope of the present invention, a polyoxymethylene resin composition having excellent weather resistance stability, reduced formaldehyde emission amount, and reduced formaldehyde emission amount during the retention of molding process was obtained.

  The polyoxymethylene resin composition of the present invention has industrial applicability as automobile parts, various electric / electronic equipment parts, and other various industrial parts.

Claims (3)

100 parts by mass of a polyoxymethylene resin homopolymer (A),
0.05 to 0.5 parts by mass of a nitrogen-containing compound (B) having formaldehyde capturing ability;
UV absorber (C) 0.1-0.5 parts by mass,
0.1 to 0.5 parts by mass of a hindered amine light stabilizer (D),
Antioxidant (E) 0.01-0.05 parts by mass;
Lubricant (F) 0.01-0.1 part by mass;
0.1 to 1.0 part by mass of polyolefin resin (G),
Containing,
The mass ratio of the (F) lubricant to the (G) polyolefin resin is (F) lubricant / (G) polyolefin resin = 5/95 to 30/70.
Polyoxymethylene resin composition.   The nitrogen-containing compound (B) having the formaldehyde scavenging ability is at least one selected from the group consisting of amino-substituted triazine compounds, urea derivatives, amide compounds, polyamides, and acrylamide copolymers. Polyoxymethylene resin composition.   The molded object containing the polyoxymethylene resin composition of Claim 1 or 2.