JP2000239484A - Polyacetal resin composition and molded article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the heat stability of a polyacetal resin and control the generation of formaldehyde. SOLUTION: A carboxylated compound having a pKa of 3.6 or higher is added to a polyacetal resin. Carboxylated compounds used include polymers made by using an α,β-ethylenically unsaturated carboxylic acid as a monomer unit (e.g. a copolymer of an α,β-ethylenically unsaturated carboxylic acid and an olefin). The polymer is added in at least an effective amount and less than 1 pt.wt. based on 100 pts.wt. polyacetal resin. An antioxicant, an alkali or alkaline earth metal compound, a stabilizer, a nitrogenous compound and the like may be added in addition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyacetal resin composition in which the amount of formaldehyde generated is remarkably suppressed and which has excellent moldability and a molded article.

[0002]

2. Description of the Related Art Polyacetal resins are excellent in mechanical properties, fatigue resistance, friction and abrasion resistance, chemical resistance and moldability, and are therefore used in automobile parts, electric and electronic equipment parts, other precision mechanical parts, It is widely used in the fields of building materials and piping parts, living and cosmetic parts, medical parts, and the like. However, with the expansion and diversification of applications, the demand for the quality thereof has been increasing. The characteristics required for the polyacetal resin include that the mechanical strength does not decrease in a processing step such as an extrusion or molding step, that no deposit (mold deposit) is generated on a mold,
The mechanical properties under long-term heating conditions (heat aging) do not decrease, and molding defects such as silver streaks and voids do not occur in molded products.
One of the important factors of these phenomena is decomposition of the polymer upon heating. In particular, the polyacetal resin is liable to be easily decomposed in a heated oxidizing atmosphere under acidic or alkaline conditions due to its chemical structure. Therefore, an essential problem of the polyacetal resin is that it has high thermal stability and suppresses the generation of formaldehyde from a molding process or a molded product. Formaldehyde is chemically active and becomes formic acid by oxidation, which adversely affects heat resistance.When used for parts of electric and electronic equipment, metal contact parts are corroded or discolored by the attachment of organic compounds, resulting in poor contact. Is generated. Furthermore, formaldehyde itself pollutes the working environment in the parts assembling process and the living environment around the use of the final product.

[0003] In order to stabilize the chemically active terminal, a homopolymer is obtained by esterifying the terminal of the polymer by acetylation or the like. For a copolymer, trioxane and a cyclic ether or cyclic formal are used during polymerization. After copolymerizing with a monomer having a carbon bond,
There is known a method of decomposing and removing an unstable terminal to make an inactive stable terminal. However, at the time of heating, cleavage and decomposition of the main chain portion of the polymer also occur, and the prevention cannot be dealt with only by the above treatment, and the addition of an antioxidant and other stabilizers is practically essential. .

However, even if these stabilizers are blended, it is difficult to completely suppress the decomposition of the polyacetal resin, and in fact, during the melt processing in the extrusion or molding step for preparing the composition, Under the action of heat or oxygen in a cylinder of an extruder or a molding machine, the main chain is decomposed or formaldehyde is generated from a terminal that is not sufficiently stabilized, thereby deteriorating the working environment during extrusion molding. In addition, when molding is performed for a long time, fine powders and tar-like substances adhere to the mold (mold deposit), reducing the work efficiency and
This is one of the biggest factors that lower the surface condition of the molded product. Furthermore, degradation of mechanical strength due to polymer decomposition,
Discoloration of the resin occurs. From such a point, great efforts have been made for polyacetal resins in search of more effective stabilizing formulations.

As antioxidants added to polyacetal resin, sterically hindered phenol compounds (hindered phenols) and sterically hindered amine compounds (hindered amines) are known. As other stabilizers, melamine derivatives Specific nitrogen-containing compounds such as polyamide, polyacrylamide, amidine compounds, alkali metal hydroxides and alkaline earth metal hydroxides, and organic or inorganic acid salts are used. Usually, antioxidants are used in combination with other stabilizers. However, even if such an additive is used, it is difficult to impart high stability to the polyacetal resin.

Japanese Patent Application Laid-Open No. 52-59646 discloses a polyacetal resin which is free from coloring by adding an antioxidant, an alkylene urethane, and urea to a polyacetal copolymer to improve the stability against heat and oxidizing atmosphere. A composition is disclosed. However, it is still difficult to significantly suppress the generation of formaldehyde only by adding an antioxidant and urea.

Japanese Unexamined Patent Publication (Kokai) No. 61-145245 discloses that, in order to improve the thermal stability of a polyacetal, the acetal polymer is made of an ionic copolymer of a low molecular weight copolymer of an α-olefin and an α, β-ethylenically unsaturated carboxylic acid. A molding composition containing a small amount of salt is disclosed. The content of the copolymer in the composition is from 0.1 to 2.5% by weight.
Is described.

JP-A-63-260949 discloses a polyacetal molding in which a hindered phenol, a metal salt of hydroxycarboxylic acid, a lubricant, a nitrogen-containing heat stabilizer, a nucleating agent, an antistatic agent and the like are added to a polyacetal resin. Compositions are disclosed. In this document, the additives improve the resistance to yellowing during heat aging, the mechanical properties, the suitability for processing, the stability to ultraviolet light, and the resistance to the accumulation of static electricity.

JP-A-59-204652 discloses that the rigidity, bending strength, impact resistance, heat resistance and moldability of polyacetal are improved and that the polyacetal is hardly peeled off in a layered form and is modified with respect to 100 parts by weight of polyacetal resin. A polyacetal-based resin composition containing an α-olefin-based polymer in a proportion of 1 to 200 parts by weight is disclosed, and the modified α-olefin-based polymer contains a base containing an α-olefin component unit as a main component ( (α-olefin polymer) 100 parts by weight of an unsaturated carboxylic acid or a derivative thereof in an amount of 0.0
It is described as a graft copolymer containing 1 to 10 parts by weight.

However, in these documents, although the thermal stability, mechanical properties, moldability and the like can be improved, it is difficult to significantly suppress the generation of formaldehyde.

[0011]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a resin composition capable of improving the thermal stability of a polyacetal resin, particularly the melt stability during molding, and to obtain a resin composition. It is to provide a molded article.

Another object of the present invention is to provide a polyacetal resin composition and a molded article which can significantly suppress the formation of formaldehyde by adding a small amount thereof and improve the working environment.

Still another object of the present invention is to suppress the formation of formaldehyde even under severe conditions, to adhere decomposed substances to a mold, to exude decomposed substances from a molded product, and to prevent the formation of a molded product. An object of the present invention is to provide a polyacetal resin composition capable of suppressing thermal degradation, improving the quality of a molded product, and improving moldability, and a molded product obtained by molding the resin composition.

[0014]

Means for Solving the Problems In order to achieve the above object, the present inventors conducted a search for a stabilizer for a polyacetal resin, and as a result, it was found that a specific compound was found to be a stabilizer for a polyacetal resin, especially for processing. The present inventors have found that they have a remarkable effect as a stabilizer, and have completed the present invention.

That is, the polyacetal resin composition of the present invention comprises a polyacetal resin and a carboxyl group-containing compound having a pKa of 3.6 or more. Also,
The polyacetal resin composition of the present invention contains a polymer having an α, β-ethylenically unsaturated carboxylic acid as a monomer unit in an effective amount or more and less than 1 part by weight based on 100 parts by weight of the polyacetal resin. . The polymer may be a copolymer of an α, β-ethylenically unsaturated carboxylic acid and an olefin. The resin composition may further include an antioxidant, an alkali or alkaline earth metal compound, a stabilizer, a nitrogen-containing compound, and the like.

The present invention also includes a polyacetal resin molded article composed of the polyacetal resin composition.

In this specification, pKa is 2
It is the logarithm of the reciprocal of the acid dissociation constant in an aqueous solution at 5 ° C. In the case of multistage dissociation, the dissociation constant of the first stage (ie, pK
It is used as a _1).

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION A polyacetal resin is a polymer compound having an oxymethylene group (—CH ₂ O—) as a main constituent unit, and is a polyacetal homopolymer (for example, trade name “Delrin” manufactured by DuPont, USA). Inc., manufactured by Asahi Kasei Corporation, trade name "Tenac 4010"), and polyacetal copolymers containing other comonomer units in addition to oxymethylene groups (for example, manufactured by Polyplastics Co., Ltd., trade name "Duracon"). It is. In the copolymer, the comonomer unit has 2 to 6 carbon atoms.
Oxyalkylene units (preferably about 2 to 4 carbon atoms) (for example, an oxyethylene group (—CH ₂ CH ₂ O)
-), An oxypropylene group, an oxytetramethylene group, etc.). The content of the comonomer unit is small, for example, 0.01 to 2 with respect to the entire polyacetal resin.
0 mol%, preferably 0.03 to 10 mol% (for example,
0.05 to 5 mol%), and more preferably from the range of about 0.1 to 5 mol%.

The polyacetal copolymer may be a copolymer composed of two components, a terpolymer composed of three components, or the like. The polyacetal copolymer may be a random copolymer, a block copolymer, a graft copolymer, or the like. Further, the polyacetal resin may have a branched structure as well as a linear structure, and may have a crosslinked structure. Further, the terminal of the polyacetal resin may be stabilized, for example, by esterification with a carboxylic acid such as acetic acid or propionic acid or an anhydride thereof. The degree of polymerization, the degree of branching and the degree of crosslinking of the polyacetal are not particularly limited as long as they can be melt-molded.

The polyacetal resin includes, for example, aldehydes such as formaldehyde, paraformaldehyde and acetaldehyde, trioxane, ethylene oxide, propylene oxide, 1,3-dioxolan,
It can be produced by polymerizing a cyclic ether such as diethylene glycol formal and 1,4-butanediol formal or a cyclic formal.

A feature of the present invention is that, in the first embodiment, p
By adding a carboxyl group-containing compound having a Ka of 3.6 or more, the processing stability of the polyacetal resin is remarkably improved, and the generation of formaldehyde is remarkably suppressed.

As the carboxyl group-containing compound,
There is no particular limitation as long as the pKa is 3.6 or more, and various compounds having a free carboxyl group, for example, aliphatic carboxylic acids, alicyclic carboxylic acids, aromatic carboxylic acids, and the like can be used. Preferred p of the carboxyl group-containing compound
Ka is 3.8 or more, especially 3.9 or more.

As the aliphatic carboxylic acid, a saturated or unsaturated aliphatic mono- or dicarboxylic acid having 3 or more carbon atoms, for example, a saturated monocarboxylic acid [valeric acid, caproic acid, caprylic acid, capric acid, lauric acid, myristic acid , palmitic acid, stearic acid, arachidic acid, behenic acid, lignoceric acid, cerotic acid, montanic acid, melissic acid, Rakuseron acid, C _4-40 saturated monocarboxylic acids (preferably C _6-26 saturated monocarboxylic such Geda acid Acid, etc.)
Unsaturated monocarboxylic acid [propenoic acid such as acrylic acid,
Butenoic acid such as vinyl acetic acid, methacrylic acid, crotonic acid and isocrotonic acid, pentenoic acid such as propylidene acetic acid (ethacrylic acid), ethylidene propionic acid and allyl acetic acid, hexenoic acid such as hydrosorbic acid and isohydrosorbic acid, octenoic acid, Pelargonic acid, decenoic acid,
C _3-26 carboxylic acids such as lindelic acid, palmito oleic acid, oleic acid, elaidic acid, linoleic acid, linolenic acid, talilic acid, arachidonic acid, erucic acid, setreic acid (preferably C _3-20 carboxylic acid, etc.) Etc.), saturated dicarboxylic acids [C ₄ such as succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecandioic acid, dodecandioic acid, tetradecandioic acid, tapsiadic acid, octadecandioic acid, etc. _-30 alkandioic acid (preferably C _4-20 alkandioic acid or the like) or the like, an anhydride thereof, an unsaturated dicarboxylic acid [pentenedioic acid, hexenedioic acid, octenedioic acid, decenedioic acid, undecenedioic acid, C _5-30 alkenedioic acids (preferably C _5-30 ) such as dodecenedioic acid, tetradecenedioic acid, hexadecenedioic acid, octadecenedioic acid, etc.
_5-20 alkenedioic acid) and its anhydrides. Further, polycarboxylic acids such as tricarboxylic acids and tetracarboxylic acids or acid anhydrides thereof (including partially condensed ones) can also be used. Further, the aliphatic carboxylic acids, hydroxyl group, alkyl group (e.g., C _1-4 alkyl group such as methyl group, ethyl group), an acyl group (e.g., C _{2 -5} acyl group such as acetyl group), an alkoxy It may have a substituent such as a group (for example, a C _1-4 alkoxy group such as a methoxy group and an ethoxy group) and a halogen (eg, chlorine and bromine).

As the alicyclic carboxylic acid, a saturated or unsaturated alicyclic mono- or dicarboxylic acid can be used. Saturated alicyclic carboxylic acids include cyclobutanecarboxylic acid, cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, cycloheptanecarboxylic acid, cyclooctanecarboxylic acid,
_C3-20 cycloalkane-monocarboxylic acids (preferably _C4-10 cycloalkane-monocarboxylic acids and the like) such as cyclononanecarboxylic acid, cyclodecanecarboxylic acid, cycloundecanecarboxylic acid and cyclododecanecarboxylic acid; C _4-20 corresponding to alkane monocarboxylic acid
Cycloalkane-dicarboxylic acids (preferably C _5-12 cycloalkane-dicarboxylic acids and the like) or acid anhydrides thereof are included. Unsaturated alicyclic carboxylic acids include C such as cyclopentene carboxylic acid, cyclohexene carboxylic acid, cycloheptene carboxylic acid, and cyclooctene carboxylic acid.
_3-20 cycloalkene-carboxylic acids (preferably C _4-10 cycloalkene-carboxylic acids and the like), C _4-20 cycloalkene-dicarboxylic acids corresponding to these cycloalkene carboxylic acids (preferably C _5-12 cycloalkenes) -Dicarboxylic acid, etc.) or its acid anhydride. Not limited to the above mono- or dicarboxylic acids, alicyclic carboxylic acids such as cycloalkanetricarboxylic acid, cycloalkanetetracarboxylic acid, cycloalkenecarboxylic acid and cycloalkenedicarboxylic acid may be used.

As the aromatic carboxylic acid, an aromatic mono- or dicarboxylic acid can be used. The aromatic monocarboxylic acid, benzoic acid, (such as 2-naphthoic acid) naphthoic acid, C _7-15 aryl, such as biphenylcarboxylic acid, anthracene carboxylic acid - carboxylic acid (preferably C _7-11
Aryl-carboxylic acids), C _7-13 aralkyl carboxylic acids such as phenylacetic acid, and the like. Examples of aromatic dicarboxylic acids include benzenedicarboxylic acid, biphenyldicarboxylic acid, naphthalenedicarboxylic acid (such as naphthalic acid), and the like.
Anthracene dicarboxylic acid (1,2-, 1,5-, 2,
3- or 2,6-anthracene such as dicarboxylic acid) C _8-16 aryl, such as - dicarboxylic acid (preferably C _8-12 aryl - dicarboxylic acid) or their anhydrides can be exemplified.
Further, an aromatic polycarboxylic acid such as an aromatic tricarboxylic acid or an aromatic tetracarboxylic acid may be used.

The alicyclic carboxylic acid or aromatic carboxylic acid may be a heterocyclic carboxylic acid having a hetero atom selected from a nitrogen atom, an oxygen atom and a sulfur atom.

The carboxyl group-containing compound may have a substituent such as a hydroxyl group, an alkyl group, an acyl group, an alkoxy group and a halogen atom.

In the polyacetal resin composition of the present invention, the ratio of the carboxyl group-containing compound is preferably in an effective amount of 2 parts by weight or less (for example, 0.0001 to 2 parts by weight) based on 100 parts by weight of the polyacetal resin. Is 0.0001 to 1.5 parts by weight, more preferably 0.01 to 1.5 parts by weight.
It is about 01 to 1 part by weight. Especially if it is more than
Even a small amount of less than part by weight can significantly suppress the generation of formaldehyde. If the proportion of the carboxyl group-containing compound exceeds 2 parts by weight, the inherent properties of the polyacetal resin may be impaired. Also, 0.00
If the amount is less than 01 parts by weight, the generation of formaldehyde cannot be effectively suppressed.

The aliphatic, alicyclic, and aromatic polycarboxylic acids include dicarboxylic acid monoesters (eg, monoethyl maleate, monomethyl fumarate, monoethyl fumarate, etc.), tricarboxylic acid mono- or diesters, and tetracarboxylic acid mono-esters. As-, a di- or triester, a form having at least one carboxyl group can also be used.

Preferred carboxylic acids are aliphatic mono- or dicarboxylic acids [unsaturated aliphatic C _3-8 monocarboxylic acids such as (meth) acrylic acid, ethacrylic acid, crotonic acid; unsaturated aliphatic C _5-8 dicarboxylic acids Succinic acid, glutaric acid,
Saturated aliphatic C _4-10 dicarboxylic acids such as adipic acid and pimelic acid] and aromatic monocarboxylic acids [benzoic acid or a substituted derivative thereof (eg, o-, m- and p-methoxybenzoic acid and the like)].

The above aliphatic, alicyclic and aromatic carboxylic acids can be used alone or in combination of two or more.

In another embodiment of the present invention, the polyacetal resin composition may be composed of a polyacetal resin and a polymer containing a carboxylic acid having a polymerizable unsaturated bond as a monomer unit.

As the carboxylic acid having a polymerizable unsaturated bond, the unsaturated carboxylic acids exemplified above can be used.
It is preferable to use a β-ethylenically unsaturated carboxylic acid, and in particular, polymerizable unsaturated monocarboxylic acids such as (meth) acrylic acid and ethacrylic acid, itaconic acid, maleic acid,
Polymerizable unsaturated polycarboxylic acids such as fumaric acid or anhydrides thereof, and monoesters of polycarboxylic acids (eg, dicarboxylic acid) (monoethyl maleate, monomethyl fumarate, monoethyl fumarate, etc.) are preferably used. Is done. Such unsaturated carboxylic acids may be used alone to form a homopolymer, or two or more may be used in combination to form a copolymer.

The polymer may be a copolymer of a polymerizable unsaturated carboxylic acid (α, β-ethylenically unsaturated carboxylic acid) and a copolymerizable monomer. Copolymerizable monomers include olefins (α-C _2-10 olefins such as ethylene, propylene and butene), (meth) acrylates [eg, methyl (meth) acrylate, ethyl (meth) acrylate, Alkyl esters such as butyl (meth) acrylate (especially C _1-10 alkyl esters), dicarboxylic acid di-C _1-6 alkyl esters such as dimethyl maleate and dimethyl fumarate, and the like. You may comprise a multicomponent copolymer with a saturated carboxylic acid. The polymer having a carboxyl group also includes an acid-modified polyolefin obtained by grafting a polymerizable unsaturated carboxylic acid to a polyolefin (eg, polyethylene, polypropylene, ethylene-propylene copolymer, etc.).

The preferred copolymer is ethylene-
Examples thereof include (meth) acrylic acid copolymer, propylene- (meth) acrylic acid copolymer, and ethylene-propylene- (meth) acrylic acid copolymer. Especially ethylene-
(Meth) acrylic acid copolymers are preferred.

Such an olefin-α, β-ethylenically unsaturated carboxylic acid copolymer is, for example, ACLYN
(Manufactured by Allied Signal Co., Ltd.) and Nuclell (manufactured by DuPont-Mitsui Polychemicals).

In the carboxyl group-containing copolymer, the content (modification rate) of the polymerizable unsaturated carboxylic acid (α, β-ethylenically unsaturated carboxylic acid) unit is not particularly limited. %, Preferably from 2 to 25% by weight, more preferably from about 3 to 20% by weight.

When a carboxyl group-containing polymer is used,
For 100 parts by weight of the polyacetal resin, the ratio of the polymer is not less than an effective amount and less than 1 part by weight (for example, 0.1% by weight).
0001 to 0.5 parts by weight, preferably 0.001 to 0.
1 part by weight), in particular, about 0.0001 to 0.05 part by weight (e.g., 0.001 to 0.05 part by weight) can effectively suppress formaldehyde generation. The carboxyl group-containing polymer may be used in combination with a compound having a pKa of 3.6 or more.

The polyacetal resin composition of the present invention may further contain an antioxidant, an alkali or alkaline earth metal compound, a stabilizer and the like.

Examples of the antioxidant include phenol-based (such as hindered phenols), amine-based, phosphorus-based,
Examples include sulfur-based, hydroquinone-based, and quinoline-based antioxidants.

The phenolic antioxidants include hindered phenols such as 2,2'-methylenebis (4-
Methyl-6-t-butylphenol), 4,4'-methylenebis (2,6-di-t-butylphenol), 4,
4'-butylidenebis (3-methyl-6-t-butylphenol), 2,6-di-t-butyl-p-cresol, 1,3,5-trimethyl-2,4,6-tris (3,5- Di-t-butyl-4-hydroxybenzyl)
Benzene, 1,6-hexanediol-bis [3-
(3,5-di-t-butyl-4-hydroxyphenyl)
Propionate], pentaerythritol tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxy) Phenyl) propionate], n-octadecyl-3
-(4 ', 5'-di-t-butylphenol) propionate, n-octadecyl-3- (4'-hydroxy-
3 ', 5'-di-tert-butylphenol) propionate, stearyl-2- (3,5-di-tert-butyl-4-)
(Hydroxyphenol) propionate, distearyl-3,5-di-t-butyl-4-hydroxybenzylphosphonate, 2-t-butyl-6- (3-t-butyl-
5-methyl-2-hydroxybenzyl) -4-methylphenyl acrylate, N, N'-hexamethylenebis (3,5-di-t-butyl-4-hydroxy-hydrocinnamamide), 3,9-bis {2- [3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy] -1,1-dimethylethyl} -2,4.
8,10-tetraoxaspiro [5,5] undecane,
4,4'-thiobis (3-methyl-6-t-butylphenol), 1,1,3-tris (2-methyl-4-hydroxy-5-t-butylphenol) butane and the like are included.

The amine-based antioxidants include hindered amines, for example, 4-methoxy-2,2,6,6-tetramethylpiperidine, 4-benzoyloxy-2,2,2.
6,6-tetramethylpiperidine, 4-phenoxy-
2,2,6,6-tetramethylpiperidine, bis-
(2,2,6,6-tetramethyl-4-piperidyl) oxalate, bis- (2,2,6,6-tetramethyl-
4-piperidyl) malonate, bis- (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 (2,2,6)
6-tetramethyl-4-piperidyl) terephthalate,
1,2-bis (2,2,6,6-tetramethyl-4-piperidyloxy) ethane, phenyl-1-naphthylamine, phenyl-2-naphthylamine, N, N′-diphenyl-1,4-phenylenediamine, N-phenyl-
N'-cyclohexyl-1,4-phenylenediamine and the like are included.

Examples of the phosphorus-based antioxidants include triisodecyl phosphite, triphenyl phosphite, trisnonyl phenyl phosphite, diphenyl isodecyl phosphite, phenyl diisodecyl phosphite,
2,2-methylenebis (4,6-di-t-butylphenyl) octyl phosphite, 4,4'-butylidenebis (3-methyl-6-t-butylphenyl) ditridecyl phosphite, tris (2,4- Di-t-butylphenyl) phosphite, tris (2-t-butyl-4-methylphenyl) phosphite, tris (2,4-di-t-
Amylphenyl) phosphite, tris (2-t-butylphenyl) phosphite, bis (2-t-butylphenyl) phenylphosphite, tris [2- (1,1-
Dimethylpropyl) -phenyl] phosphite, tris [2,4- (1,1-dimethylpropyl) -phenyl]
Phosphite, tris (2-cyclohexylphenyl)
Phosphite, tris (2-t-butyl-4-phenylphenyl) phosphite and the like.

Hydroquinone antioxidants include, for example,
2,5-di-t-butylhydroquinone and the like, and quinoline-based antioxidants include, for example, 6-ethoxy-2,
2,4-trimethyl-1,2-dihydroquinoline and the like, and the sulfur-based antioxidants include, for example, dilauryl thiodipropionate, distearyl thiodipropionate and the like.

These antioxidants can be used alone or in combination of two or more.

Preferred antioxidants include phenolic antioxidants (particularly, hindered phenols). Among the hindered phenols, particularly, for example, 1,6-hexanediol-bis [3- (3,5-
Di-t-butyl-4-hydroxyphenyl) propionate] and other C _2-10 alkylenediol-bis [3-
(3,5-di-branched C _3-6 alkyl-4-hydroxyphenyl) propionate]; for example, triethylene glycol-bis [3- (3-t-butyl-5-methyl-4)
- hydroxyphenyl) propionate] di- or Toriokishi C _2-4 alkylene diol such as - bis [3-
(3,5-di-branched C _3-6 alkyl-4-hydroxyphenyl) propionate]; for example, C such as glycerin tris [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] _3-8 alkylenetriol-bis [3- (3,5-di-branched C _3-6 alkyl-
4-hydroxyphenyl) propionate];
Pentaerythritol tetrakis [3- (3,5-di-
and C _4-8 alkylenetetraol tetrakis [3- (3,5-di-branched C _3-6 alkyl-4-hydroxyphenyl) propionate] such as [t-butyl-4-hydroxyphenyl) propionate].

These antioxidants can be used alone or in combination of two or more. The content of the antioxidant is, for example, from 0.01 to 5 parts by weight, preferably from 0.05 to 2.5 parts by weight, particularly from 0.1 to 5 parts by weight, based on 100 parts by weight of the polyacetal resin.
It can be selected from a range of about 1 part by weight.

Examples of the alkali or alkaline earth metal compound include aliphatic carboxylic acids (eg, acetic acid, propionic acid, succinic acid, adipic acid) and aromatic carboxylic acids (eg, benzoic acid, phthalic acid, phenylacetic acid, etc.). ,
Monobasic, dibasic or tribasic oxycarboxylic acids (eg,
C such as lactic acid, mandelic acid, malic acid, citric acid)
Sodium _{1-10-carboxylic} acid, calcium, magnesium metal salt; CaO, metal oxides such as MgO; Ca (O
H) ₂ , metal hydroxides such as Mg (OH) ₂ ; CaC
Examples thereof include metal carbonates such as O ₃ and MgCO ₃ .

The alkali or alkaline earth metal compounds can be used alone or in combination of two or more kinds. The proportion thereof is 0.0 to 100 parts by weight of the polyacetal resin.
It can be selected from the range of about 01 to 10 parts by weight, preferably about 0.001 to 5 parts by weight (particularly 0.001 to 2 parts by weight).

Examples of the stabilizer include a processing stabilizer and a weather (light) stabilizer.

As the processing stabilizer, at least one selected from polyalkylene glycols, fatty acid esters, fatty acid amides and fatty acid metal salts can be used.

The above-mentioned polyalkylene glycols include
Kilen glycol (for example, ethylene glycol, professional
C such as pyrene glycol and tetramethylene glycol
_2-6Alkylene glycol (preferably C_2-4Alkylene
Glycol), etc.) homopolymers, copolymers, and the like
And derivatives thereof. A specific example is poly
Ethylene glycol, polypropylene glycol, poly
Poly C such as tetramethylene glycol_2-6Alkylene
Glycol (preferably poly C_2-4Alkylene glycol
), Polyoxyethylene-polyoxypropylene copolymer
Coalescence (random or block copolymer, etc.), polyoxo
Siethylene polyoxypropylene glyceryl ether,
Polyoxyethylene polyoxypropylene monobutyl ether
And copolymers such as polyester. Preferred Poria
Luylene glycol is a heavy chain having oxyethylene units.
Coalescence, for example, polyethylene glycol, polyoxye
Tylene polyoxypropylene copolymers and their derivatives
Body. In addition, the polyalkylene glycol
Means that the number average molecular weight is 1 × 10^Three~ 1 × 10⁶(For example, 1
× 10^Three~ 5 × 10^Five), Preferably 2 × 10^Three~ 1 × 1
0^Five(For example, 2 × 10 ^Three~ 5 × 10^Four).

The structure of the fatty acid ester is not particularly limited, and any of a linear or branched fatty acid ester can be used. The fatty acid constituting the ester may be a saturated fatty acid or an unsaturated fatty acid. There may be. In addition, those in which some hydrogen atoms are substituted with a substituent such as a hydroxyl group can also be used. As the fatty acid constituting the fatty acid ester, among the fatty acids exemplified above, those having 10 carbon atoms
The above monovalent or divalent fatty acids, for example, monovalent saturated fatty acids [C _10-34 such as capric acid, lauric acid, myristic acid, pentadecylic acid, palmitic acid, stearic acid, arachinic acid, behenic acid, montanic acid, etc. Saturated fatty acids (preferably C _10-26 saturated fatty acids), etc.]
Polyunsaturated fatty acids [C _10-34 unsaturated fatty acids such as oleic acid, linoleic acid, linolenic acid, arachidonic acid, erucic acid and the like (preferably C _10-26 saturated fatty acids), etc.]
0 or more divalent fatty acid (dibasic fatty acid) [a divalent C _10-30 saturated fatty acid such as sebacic acid, dodecandioic acid, tetradecandioic acid, and thapsitic acid (preferably divalent C _10-20
Divalent _C10-30 unsaturated fatty acids (preferably divalent _C10-20 unsaturated fatty acids) such as saturated fatty acids), decenedioic acid and dodecenedioic acid. These fatty acids can be used alone or in combination of two or more. The fatty acids also include fatty acids having one or more hydroxyl groups in the molecule.

The type of the alcohol constituting the fatty acid ester is not particularly limited, but a polyhydric alcohol is preferred. The polyhydric alcohol has 2 carbon atoms.
About 8 to about 8, preferably about 2 to 6 polyhydric alcohols or polymers thereof, for example, alkylene glycols (for example,
_Diols such as C _2-8 alkylene glycol (preferably C _2-6 alkylene glycol) such as ethylene glycol, diethylene glycol and propylene glycol; triols such as glycerin, trimethylolpropane or derivatives thereof, pentaerythritol, and sorbitan Or tetraols such as derivatives thereof, and homo- or copolymers of these polyhydric alcohols (for example, homo- or copolymers of polyoxyalkylene glycols such as polyethylene glycol and polypropylene glycol, polyglycerin and the like). Can be illustrated. The average polymerization degree of the polyalkylene glycol is 2 or more (for example, 2 to 500), preferably about 2 to 400 (for example, 2 to 300), and the average polymerization degree is 16 or more (for example, about 20 to 200). Such a polyalkylene glycol is suitably used as an ester with a fatty acid having 12 or more carbon atoms. Preferred polyhydric alcohols are polyalkylene glycols having an average degree of polymerization of 2 or more. These polyhydric alcohols can be used alone or in combination of two or more.

The fatty acid ester is composed of the fatty acid and the alcohol, and may have one or more ester bonds such as a monoester, a diester, and a triester. Examples of the fatty acid ester include ethylene glycol distearate, glycerin monostearate, glycerin tripalmitate, polyglycerin tristearate, trimethylolpropane monopalmitate, pentaerythritol monoundecylate, and sorbitan monoester. Monostearate, monolaurate of polyalkylene glycol (polyethylene glycol, polypropylene glycol, etc.), monopalmitate, monostearate, dilaurate, dipalmitate, distearate,
Examples include dibehenate, dimontanate, diolate, and dilinoleate. Among fatty acid esters composed of a fatty acid and a polyhydric alcohol, those having at least one free hydroxyl group derived from the polyhydric alcohol, that is, those in which the hydroxyl group remains in the ester without being esterified are particularly preferable.

As the fatty acid amide, an acid amide (monoamide, bisamide, etc.) of the monovalent or divalent fatty acid exemplified in the section of the fatty acid ester and an amine (monoamine, diamine, polyamine, etc.) can be used. Examples of the monoamide include, for example, primary acid amides of saturated fatty acids such as capric acid amide, lauric acid amide, myristic acid amide, palmitic acid amide, stearic acid amide, arachidic acid amide, behenic acid amide, and oleic acid amide. Secondary acid amides of saturated and / or unsaturated fatty acids such as primary acid amides of saturated fatty acids, stearyl stearic acid amides, and stearyl oleic acid amides and monoamines can be exemplified. The preferred fatty acid amide is bisamide. The bisamide includes a bisamide of a C _1-6 alkylenediamine (particularly, a C _1-2 alkylenediamine) and the fatty acid, and specific examples thereof include:
Ethylenediamine-distearic acid amide, hexamethylenediamine-distearic acid amide, ethylenediamine-dioleic acid amide, ethylenediamine-dierucamide, and the like.
(Stearic acid amide) A bisamide having a structure in which a different acyl group is bonded to an amine moiety of an alkylenediamine such as oleic acid amide can also be used. In the acid amide, the fatty acid constituting the acid amide is preferably a saturated fatty acid.

As the fatty acid metal salt, the above-mentioned salts of a fatty acid having 10 or more carbon atoms and a metal can be used. The metal preferably has a valence of 1 to 4 (particularly 1 to 2), and usually, an alkaline earth metal (Mg, Ca, etc.) salt is preferably used. Examples of fatty acid metal salts include:
Magnesium stearate, calcium stearate,
Examples include zinc stearate and calcium 12-hydroxystearate.

The above-mentioned processing stabilizers can be used alone or in combination of two or more.

The proportion of the processing stabilizer as described above is 0.01 to 10 parts by weight, preferably 0.03 to 5 parts by weight (for example, 0.03 to 5 parts by weight) based on 100 parts by weight of the polyacetal resin.
5 to 3 parts by weight), particularly about 0.05 to 2 parts by weight.

Examples of the weather (light) stabilizer include (a) a benzotriazole compound, (b) a benzophenone compound, (c) an aromatic benzoate compound, (d) a cyanoacrylate compound, and (e) oxalic anilide. And (f) a hindered amine compound. For example, (a) the benzotriazole-based compound includes 2- (2'-hydroxy-5'-methylphenyl)
Benzotriazole, 2- (2'-hydroxy-3 ',
5'-di-t-butylphenyl) benzotriazole,
2- (3,5-di-t-amyl-2-hydroxyphenyl) benzotriazole, 2- (2'-hydroxy-
3 ', 5'-di-isoamylphenyl) benzotriazole, 2- [2-hydroxy-3,5-bis (α, α-
Dimethylbenzyl) phenyl] benzotriazole, 2
Examples of hydroxyl group-containing benzotriazoles such as-(2'-hydroxy-4'-octoxyphenyl) benzotriazole, and (b) benzophenone-based compounds include
2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-
Octoxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2,2'-dihydroxy-
Hydroxyl group-containing benzophenones such as 4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone and 2-hydroxy-4-oxybenzylbenzophenone; (C) Alkyl phenyl salicylates such as pt-butylphenyl salicylate and p-octylphenyl salicylate as aromatic benzoate-based compounds, and 2-ethylhexyl-2-cyano-3 as (d) cyanoacrylate-based compound. , 3-diphenyl acrylate, ethyl-2-
Examples of cyano group-containing diphenyl acrylates such as cyano-3,3-diphenyl acrylate, and (e) oxalic anilide-based compounds include N- (2-ethylphenyl)-
N '-(2-ethoxy-5-t-butylphenyl) oxalic acid diamide, N- (2-ethylphenyl) -N'-
Examples of oxalic acid diamides having a phenyl group which may be substituted on a nitrogen atom, such as (2-ethoxy-phenyl) oxalic acid diamide, and (f) hindered amine compounds include piperidine derivatives having a sterically hindered group ( 4-acetoxy-2,2,6,6-tetramethylpiperidine, 4-stearoyloxy-2,2,6,6-tetramethylpiperidine, 4-acryloyloxy-2,
2,6,6-tetramethylpiperidine, 4-methoxy-
2,2,6,6-tetramethylpiperidine, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, 4-cyclohexyloxy-2,2,6,6-tetramethylpiperidine, 4-phenoxy- 2,2,6,6
-Tetramethylpiperidine, 4-benzyloxy-2,
2,6,6-tetramethylpiperidine, 4- (phenylcarbamoyloxy) -2,2,6,6-tetramethylpiperidine, bis (2,2,6,6-tetramethyl-4
-Piperidyl) oxalate, bis (2,2,6,6-
Tetramethyl-4-piperidyl) malonate, bis (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 (2,2,6,6-tetramethyl-4-piperidyl) terephthalate, 1,2-bis (2,2,6,6-tetramethyl-4-piperidyloxy) ethane , Screw (2,
2,6,6-tetramethyl-4-piperidyl) hexamethylene-1,6-dicarbamate, bis (1-methyl-
2,2,6,6-tetramethyl-4-piperidyl) adipate, tris (2,2,6,6-tetramethyl-4-)
2,2,6,6-tetramethylpiperidines such as piperidyl) benzene-1,3,5-tricarboxylate or a high-molecular-weight piperidine derivative polycondensate (dimethyl-1- (2-hydroxyethyl succinate) ) -4-hydroxy-2,2,6,6-tetramethylpiperidine polycondensate).

The above-mentioned weather (light) stabilizers may be used alone, but are preferably used alone or in combination of two or more. (A) a benzotriazole compound, (b) benzophenone Compounds, (c) aromatic benzoate compounds, (d) cyanoacrylate compounds,
And / or (e) a weather (light) stabilizer of an oxalic anilide compound and (f) a hindered amine compound are preferably used in combination.

By adding a weather (light) stabilizer,
In addition to suppressing the generation of formaldehyde, the polyacetal resin can be given weather resistance (light), and can improve not only thermal stability but also stability against light and the like.

The amount of the weather (light) stabilizer added is, for example, 0.01 to 5 parts by weight (for example, 0.01 to 3 parts by weight), preferably 0.1 to 3 parts by weight, per 100 parts by weight of the polyacetal resin.
It is about 0.1 to 2 parts by weight, more preferably about 0.1 to 2 parts by weight (for example, about 0.1 to 1.5 parts by weight).

The antioxidant, alkali or alkaline earth metal compound and stabilizer may be used alone or in combination of two or more, if necessary.

[0065] The polyacetal resin composition of the present invention may further contain a nitrogen-containing compound. Nitrogen-containing compounds include low-molecular compounds and high-molecular compounds (nitrogen-containing resins)
Is included. Examples of the nitrogen-containing low-molecular compound include, for example,
Aliphatic amines such as monoethanolamine and diethanolamine, aromatic amines (aromatic secondary or tertiary amines such as o-toluidine, p-toluidine, p-phenylenediamine), amide compounds (malonamide, isophthalic acid) Polycarboxylic acid amides such as diamide, p-aminobenzamide, etc.), urea or derivatives thereof (urea, mono-N-substituted ureas such as N-methylurea, condensates with aldehydes, etc.), hydrazine or derivatives thereof (hydrazine, Hydrazones, hydrazides such as polyhydric carboxylic acid hydrazides, etc.), amidine derivatives [polyaminotriazines (guanamines such as guanamine, acetoguanamine, benzoguanamine or derivatives thereof, melamine or derivatives thereof), guanidine or derivatives thereof (creatinine or derivatives thereof) Conductor etc.)], uracil or a derivative thereof (uracil, uridine, etc.), etc. cytosine or a derivative thereof (cytosine, cytidine, etc.) can be exemplified.

Examples of the nitrogen-containing resin include amino resins (condensation resins such as guanamine resin, melamine resin, and guanidine resin, phenol-melamine resin, benzoguanamine-melamine resin, and aromatic polyamine) formed by reaction with formaldehyde. A co-condensation resin such as a melamine resin), an aromatic amine-formaldehyde resin (such as an aniline resin), a polyamide resin (for example,
Nylon 3, Nylon 6, Nylon 66, Nylon 1
1, nylon 12, nylon MXD6, nylon 4-
6, nylon 6-10, nylon 6-11, nylon 6
-12, Nylon 6-66-610, etc., homo- or copolymerized polyamides, substituted polyamides having a methylol group or an alkoxymethyl group, etc.), polyesteramides, polyamideimides, polyacrylamides, polyaminothioethers and the like.

Preferred nitrogen-containing compounds include urea or its derivatives, amidine derivatives and the like.

The urea derivative only needs to have at least one amino group (particularly at least two amino groups), and such a urea derivative includes a mono-N-substituted urea, a urea condensate and the like. As mono N-substituted ureas,
For example, mono-N-alkyl-substituted ureas (for example, mono-NC _1-6 alkyl-substituted ureas such as N-methyl and N-ethyl), alkylenebisureas (for example, ethylene, propylene, butylene, hexamethylene and the like) C _2-8 bis urea alkylene group), mono N- cycloalkyl-substituted urea (e.g., N- cyclobutyl body, mono- N-C _3-10 cycloalkyl substituted ureas, such as N- cyclohexyl body),
Mono N-hydrocarbon group substituted ureas such as mono N-aryl substituted ureas (for example, mono _{NC 6-12} aryl substituted ureas such as phenyl) and the like. Examples of the urea condensate include a cyclic or acyclic condensate of urea and an aldehyde such as formaldehyde, acetaldehyde, and isobutyraldehyde.

Examples of these urea condensates include multimers having a plurality of urea units (or urea residues) (for example, dimers of urea (for example, biuret, biurea, etc.)) and non-polymers of urea and isobutyraldehyde. Cyclic condensates (for example, isobutylidene diurea), condensates of urea and acetaldehyde [for example, 2-oxo-4-methyl-6-ureidohexahydropyrimidine (clotilidene diurea) and the like], and urea and formaldehyde Acyclic condensates (e.g., ureaform, form nitrogen, etc.) and urea resins (urea-formaldehyde resins) can be exemplified. In the acyclic condensate of urea and formaldehyde, one or more urea units may be condensed, and (n + 1) urea units (n is 1) via n methylene chains.
(The above integers) may be condensed. The urea derivatives can be used alone or in combination of two or more. The urea resin may be soluble or insoluble in warm water at about 40 to 100 ° C (particularly 50 to 80 ° C). The urea resin can be obtained by reacting at least urea, thiourea, and, if necessary, a co-condensation component (a phenol compound, melamine, guanamine, etc.) with formaldehyde. Good.
Further, it may be a methylol urea resin having a methylol group, or an alkoxymethyl urea resin in which at least a part of the methylol group is etherified with an alcohol (for example, methanol, ethanol, propanol, isopropanol, butanol, etc.). You may. The urea resin may be a water-soluble urea resin, but is preferably a water-insoluble urea resin.

Preferred urea derivatives include ureide derivatives (for example, monoureide and diureide or derivatives thereof). Further, urea derivatives include acyclic ureides or cyclic ureides.

Examples of the acyclic monoureide include ureido acid of C _2-6 dicarboxylic acid [eg, ureic acid of oxalic acid (oxalic acid), ureido acid of malonic acid (malonulic acid) and the like] or derivatives thereof (eg, ureide) Acid amide) or a carboxylic acid having a ureido group [for example, ureido group-containing C _1-6 monocarboxylic acid such as ureido formic acid and ureido acetic acid, and carbamide group-containing C ₂ such as ureido succinic acid (carbamyl aspartic acid). _-6
Dicarboxylic acids] or acid amides containing these carbamide groups (such as allophanoic anilide and allophanoic amide)
And carbamide group-containing esters (such as allophanoic acid esters). As acyclic diureides,
Examples thereof include diureido of C _2-6 carboxylic acid [for example, diureide of acetic acid (allantoic acid) and the like].

Examples of the cyclic monoureide include cyclic condensates of urea and acetaldehyde (for example, clotilidene diurea), allantoin, and derivatives thereof.

Monoureides or diureides, particularly cyclic ureide derivatives, are metal salts, for example, alkali metal salts (metal salts of Group 1A of the periodic table such as Li, Na, and K) and alkaline earth metal salts (Mg, Ca, Sr, Periodic table 2 such as Ba
Group A metal salts), Periodic Table 1B metal salts (salts with Cu, Ag, etc.), Periodic Table 2B metal salts (salts with Zn, etc.), Periodic Table 3B metal salts (Al, Ga, In, etc.) Metal salts (eg, salts with Sn, Pb, etc.) and Group 8 metal salts (eg, salts with Fe, Co, Ni, Pd, Pt, etc.) in the periodic table. Metal salts).

Particularly preferred cyclic ureido derivatives include allantoin and its derivatives. For allantoin derivatives, refer to “DICTIONARY OF ORGANIC COMPOUND”.
S Vol.1, p60 (1965 EYRE & SPOTTISWOODE-PUBLISHERS
-LTD) ". As allantoin derivatives,
For example, substituted allantoin derivatives substituted with various substituents such as an alkyl group, a cycloalkyl group, and an aryl group (for example, 1-methyl, 3-methyl, 3-ethyl, 5-ethyl, 1,3- Dimethyl form, 1,6-dimethyl form, 1,8-dimethyl form, 3,8-dimethyl form,
Mono-, di- or tri-C _1-4 alkyl-substituted products such as 1,3,6-trimethyl product and 1,3,8-trimethyl product;
An aryl-substituted product such as -phenyl, etc.) and a metal salt thereof (alkali metal salt (metal salt of Group 1A of the periodic table), alkaline earth metal salt (metal salt of Group 2A of the periodic table), and metal of Group 1B of the periodic table Salts, salts with metals in the periodic table 2B, salts with metals in the periodic table 3B, salts with metals in the periodic table 4B, salts with metals in the periodic table 8], reaction products of allantoin and aldehyde compounds [ For example, allantoin-formaldehyde adduct or its alcohol-modified form (alkoxymethyl form, etc.)
And a reaction product of allantoin with a nitrogen-containing compound (such as an amino- or imino-group-containing compound) [eg, 2
Compounds with -pyrrolidone-5-carboxylate (salts, molecular compounds (complexes, etc.), compounds of allantoin and imidazole compounds (salts, molecular compounds (complexes, etc.)), and organic acid salts can also be used. Specific examples of metal salts of allantoin, allantoin dihydroxy aluminum,
Allantoinchlorohydroxyaluminum and the like can be exemplified, and as a reaction product with an amino group or imino group-containing compound, allantoindium-dlpyrrolidonecarboxylate and the like can be exemplified.

The compound of allantoin and 2-pyrrolidone-5-carboxylate is disclosed in JP-A-51-3645.
3 can be referred to, and for the reaction product of allantoin and a basic amino acid, see JP-A-52-102412, JP-A-52-25771, and JP-A-52-2.
Reference can be made to JP-A-5772, JP-A-52-31072, JP-A-51-19771, and the like. For the compound of allantoin and an imidazole compound, reference can be made to JP-A-57-118569. The three-dimensional structures of allantoin and its derivatives are not particularly limited.
It may be any of a body, an l body and a dl body. These allantoin and its derivatives can be used alone or in combination of two or more.

Amidine derivatives include RC (= NH) NH
₂ (R represents a hydrogen atom, an alkyl group, or an acyl group.)
And an amidine containing a structural unit represented by the formula: The structure of the amidine derivative may be acyclic or cyclic amidine. Amidine derivatives also include guanidines in which R is an amino group (guanidine or a derivative thereof), and the structure of guanidines may be acyclic or cyclic. The acyclic amidine includes, for example, amidine or a derivative thereof. Preferred amidines are guanidines, and acyclic guanidines include, for example, glycosamine, guanoline, creatine, or derivatives thereof. Amidine derivatives further include aminotriazines (eg, 3-amino-1,2,3-triazine, 4-amino-1,2,3-triazine, 3-amino-benzo-1,2,3-triazine and the like) Amino-
1,2,3-triazines, 3-amino-1,2,4-
1,2,4-triazines such as triazine, 3-amino-benzo-1,2,4-triazine, 2-amino-
1,3,5-triazine, 4-amino-1,3,5-triazine, 2,4-diamino-1,3,5-triazine, 2,4,6-triamino-1,3,5-triazine ( Melamine), melam, melem, cyanuric acid amides such as cyanuric acid monoamide or cyanuric acid diamide).

Preferred guanidines are cyclic guanidines
Kind. Cyclic guanidine is -R ¹NC (= NH) N
R^Two− (R¹And R^TwoAre the same or different and are a hydrogen atom,
It represents an alkyl group or an acyl group. ) Is the constituent unit of the ring
And it is not affected by the size of the ring.
However, a 5- or 6-membered ring compound is preferred. In the above formula,
R¹And R^TwoThe alkyl group represented by_1-4A
As a alkyl group, especially a methyl group or an ethyl group, an acyl group
Is C_1-4Alkyl group, especially formyl group, acetyl group,
Or a propionyl group, and a hydrogen atom is particularly preferable.
Good.

Preferred cyclic guanidines include, as the 5-membered ring nitrogen-containing compound, glycosiamidine or a derivative thereof (for example, glycosiamidine, thioglyciamidine,
Creatinine, 4-methylglycocyanidin, 4,4-
Glycosiamidine, etc.), oxalylguanidine or a cyclic guanidine having a structure similar to that thereof (eg, oxalylguanidine, 2,4-diiminoparabanic acid, 2,4,5-
At least one oxo group (= O) of the two oxo groups (= O) of urazole.
O) substituted with an imino group (（NH) (for example,
Iminourazole, iminothiourazole, guanazine, etc.). Preferred 6-membered nitrogen-containing compounds include, for example, isocyanuric imide or a derivative thereof (eg, isoammelide, isoammeline, or an N-substituted product thereof), cyclic guanidine such as malonylguanidine, tartronylguanidine, or a derivative thereof, A cyclic guanidine compound such as xalylguanidine can be exemplified.

Among the guanidines, glycosiamidine or a derivative thereof (eg, creatinine) is particularly preferred.

The triazines include not only polyaminotriazines (melamine or derivatives thereof) but also resins containing these (amino resins such as melamine resins, etc.).
Polyamide resin) can also be used. Preferred resins include amino resins (such as melamine resins) and polyamide resins, and among them, amino resins, among which cross-linked amino resins are preferred. Further, a melamine resin (melamine-formaldehyde resin), particularly a crosslinked melamine resin, is preferred.

Among the amidine derivatives, melamine or a derivative thereof, guanamine or a derivative thereof, and creatinine or a derivative thereof are particularly preferable.

The urea or urea derivative or amidine derivative may be used alone or in combination of two or more.

The proportion of the nitrogen-containing compound is, for example, 0.01 to 10 parts by weight (for example, 0.01 to 5 parts by weight), preferably 0.0 to 10 parts by weight, per 100 parts by weight of the polyacetal resin.
It is about 2 to 5 parts by weight, more preferably about 0.02 to 2.5 parts by weight, and even at about 0.02 to 1.5 parts by weight, the formation of formaldehyde can be remarkably suppressed.

Further, a coloring agent can be further mixed with the polyacetal resin composition of the present invention. Various dyes or pigments can be used as the colorant. The dye is preferably a solvent dye, and examples thereof include an azo dye, an anthraquinone dye, a phthalocyanine dye, and a naphthoquinone dye. As the pigment, any of an inorganic pigment and an organic pigment can be used. As inorganic pigments, titanium-based pigments, zinc-based pigments, carbon black (furnace black, channel black, acetylene black,
Ketjen black), iron-based pigments, molybdenum-based pigments, cadmium-based pigments, lead-based pigments, cobalt-based pigments, aluminum-based pigments, and the like. Examples of organic pigments include azo-based pigments, anthraquinone-based pigments, and phthalocyanine. Pigments, quinacridone pigments, perylene pigments, perinone pigments, isoindoline pigments, dioxazine pigments, and sulene pigments. The colorants as described above may be used alone, or a plurality of colorants may be used in combination. When a colorant having a high light shielding effect such as carbon black or titanium white (titanium oxide) is used, weather resistance (light) can be improved.

The content of the coloring agent is, for example, 0 to 5 parts by weight (for example, 100 parts by weight of the polyacetal resin).
0.01 to 5 parts by weight), preferably 0.1 to 4 parts by weight,
More preferably, it is about 0.3 to 3 parts by weight.

If necessary, a resin having excellent weather (light) resistance, for example, an acrylic resin (a C _1-10 alkyl (meth) acrylate such as polymethyl methacrylate, alone or co-polymerized) may be added to the resin composition of the present invention. ), An acrylic core-shell polymer, a polycarbonate resin, or the like. In addition, by adding a surface modifier, appearance defects such as cracks can be suppressed.

The polyacetal resin composition of the present invention includes:
If necessary, various additives, for example, a release agent, a nucleating agent, an antistatic agent, a flame retardant, a surfactant, various polymers, a filler, and the like may be added alone or in combination of two or more.

The polyacetal resin composition of the present invention may be a powdery or granular mixture or a melt mixture. The polyacetal resin composition is prepared by mixing the polyacetal resin, the carboxyl group-containing compound and, if necessary, other additives with a conventional method. Can be prepared. For example, after mixing each component, kneading and extruding with a single-screw or twin-screw extruder to prepare pellets, a method of molding, once preparing pellets (master batch) having different compositions, and weighing the pellets in a predetermined amount A method of mixing (diluting) and subjecting to molding to obtain a molded article of a predetermined composition, a method of applying a suppressant to polyacetal resin pellets by spraying or the like, and then molding to obtain a molded article of a predetermined composition. Can be adopted. In addition, in the preparation of a composition used for a molded article, a powder of a polyacetal resin serving as a base (for example, a powder obtained by crushing a part or all of a polyacetal resin) and another component (a urea derivative or the like) are mixed. Melting and kneading are advantageous in improving the dispersion of additives.

The polyacetal resin composition of the present invention can remarkably suppress the generation of formaldehyde due to oxidation or thermal decomposition of the polyacetal resin in the molding (particularly, melt molding) process, and can improve the working environment.
Further, adhesion of a decomposed product or the like to a mold (mold deposit) and leaching of the decomposed product from a molded product are remarkably suppressed, heat aging properties can be largely improved, and problems during molding can be improved. Therefore, the resin composition of the present invention, a conventional molding method, for example, injection molding, extrusion molding, compression molding,
It is useful for molding various molded articles by methods such as blow molding, vacuum molding, foam molding, rotational molding, and gas injection molding.

The polyacetal resin molded article of the present invention composed of the above polyacetal resin composition contains a specific carboxyl group-containing compound, and generates very little formaldehyde. That is, a molded article made of the conventional polyacetal resin containing a stabilizer such as an antioxidant generates a relatively large amount of formaldehyde, and contaminates a living environment and a working environment in addition to corrosion and discoloration. For example, the amount of formaldehyde generated from a commercially available polyacetal resin molded product is about ^{2 to 5} μg per 1 cm ² of the surface area in a dry system (under a constant temperature and dry atmosphere), and the surface area of 1 c in a wet system (under a constant temperature and humid atmosphere).
It is about 3 to 6 μg per m ² . Further, even if the molding conditions are controlled, the surface area is 1 in a dry method (under a constant temperature dry atmosphere).
cm ² per 1.5μg less, in the wet (under constant-temperature wet atmosphere), it is difficult to obtain a surface area 1 cm ² per 2.5μg following moldings.

On the other hand, in the polyacetal resin molded article of the present invention, the amount of formaldehyde generated was 2.0 μg or less per 1 cm ² of surface area of the molded article (0 to
1.5 μg), preferably about 0 to 1 μg, more preferably about 0 to 0.8 μg, and usually 0.01 to
It is about 0.7 μg. Further, in the wet method, the amount of formaldehyde generated was 2.5% per 1 cm ² of surface area of the molded article.
μg or less (about 0 to 2 μg), preferably 0 to 1.7 μg
g, more preferably about 0 to 1.5 μg, and usually about 0.01 to 1.5 μg.

The polyacetal resin molded article of the present invention only needs to have the above-mentioned formaldehyde generation amount in either the dry type or the wet type, and usually has the formaldehyde generation amount in both the dry type and the wet type. I have.

The amount of formaldehyde generated in a dry system can be measured as follows.

After the polyacetal resin molded product is cut as necessary to measure the surface area, an appropriate amount of the molded product (for example, about 10 to 50 cm ² in surface area) is placed in a closed container (capacity: 20 ml), and the temperature is adjusted to 80 ° C. Leave at 24 ° C. for 24 hours. Thereafter, 5 ml of water is poured into the closed container, and the amount of formalin in the aqueous solution is quantified in accordance with JIS K0102, 29 (formaldehyde) to determine the amount of formaldehyde generated (μg / cm ² ) per surface area of the molded article.

Further, the amount of formaldehyde generated in a wet system can be measured as follows.

After the polyacetal resin molded product is cut as necessary to measure the surface area, an appropriate amount of the molded product (for example, about 10 to 100 cm ² in surface area) is placed in a closed container (volume: 1 liter) containing 50 ml of distilled water. ), Hang it on the lid and seal it, and leave it in a thermostat at 60 ° C for 3 hours. Thereafter, the mixture is left at room temperature for 1 hour, and the amount of formalin in the aqueous solution in the closed container is quantified according to JIS K0102, 29 (formaldehyde) to determine the amount of formaldehyde generated (μg / cm ² ) per surface area of the molded article.

In the present invention, the numerical specification of the amount of formaldehyde generated in the present invention relates to the molded product of the polyacetal resin composition containing additives (stabilizer, mold release agent, etc.) as long as it contains the polyacetal resin and the specific carboxyl group-containing compound. In addition, even in a molded article of a composition containing an inorganic filler and another polymer, a molded article in which most (for example, 50 to 100%) of the surface of the molded article is composed of a polyacetal resin (for example, Multicolor molded products and coated molded products) are also applicable.

The molded article of the present invention can be used in any application where formaldehyde is detrimental (for example, knobs and levers as bicycle parts), but it can be used for mechanical parts (active parts) in the automotive field or the electric / electronic field. Parts, passive parts, etc.), construction materials and plumbing, daily necessities (life), cosmetics,
And it is suitably used as a part / member in the medical field (medical / treatment field).

More specifically, the mechanical parts in the automotive field include inner handles, fuel trunk openers, seat belt buckles, assist wraps, interior parts such as various switches, knobs, levers, clips, and electric parts such as meters and connectors. System parts, in-vehicle electric and electronic parts such as audio equipment and car navigation equipment,
Parts that come into contact with metal typified by a carrier plate of a window regulator, door lock actuator parts, mirror parts, wiper motor system parts, and fuel system parts can be exemplified.

As mechanical parts in the electric and electronic fields, parts or members of equipment made of a polyacetal resin molded article and having many metal contacts [for example, audio equipment such as a cassette tape recorder, VTR (video tape recorder)] OA (Office Automation) equipment such as copiers, facsimile machines, word processors, computers, etc., as well as toys, telephones, computers, etc. that are driven by driving power such as motors and splicers. Keyboard etc.]. Specific examples include a chassis (base), gears, levers, cams, pulleys, bearings, and the like. Further, optical and magnetic media components at least partially composed of a polyacetal resin molded product (for example, a metal thin film magnetic tape cassette, a magnetic disk cartridge, a magneto-optical disk cartridge, etc.),
More specifically, the present invention can be applied to a metal tape cassette for music, a digital audio tape cassette, an 8 mm video tape cassette, a floppy disk cartridge, a mini disk cartridge, and the like. Specific examples of optical and magnetic media components include tape cassette components (tape cassette main body, reel, hub, guide, roller, stopper, lid, etc.), disk cartridge components (disk cartridge main body (case), shutter, clamping) Plate and the like).

Further, the polyacetal resin molded product of the present invention can be used for building materials and piping parts such as lighting fixtures, fittings, piping, cocks, faucets, toilet peripheral parts, stationery, lip cream / lipstick containers, washing machines, water purifiers, and the like. It is suitably used for a wide range of living-related parts, cosmetic-related parts, and medical-related parts such as spray nozzles, spray containers, aerosol containers, general containers, and injection needle holders.

[0102]

According to the present invention, the polyacetal resin composition comprises:
Since the polyacetal resin contains a specific carboxyl group-containing compound, the thermal stability of the polyacetal resin (in particular, the melt stability during molding) can be greatly improved. Further, the amount of formaldehyde generated can be suppressed to an extremely low level by adding a small amount, and the working environment can be greatly improved. Furthermore, even under severe conditions, the formation of formaldehyde can be suppressed, the adhesion of decomposed products to molds (mold deposit), the leaching of decomposed products from molded products, and the thermal degradation of molded products can be suppressed. Product quality and moldability can be improved.

[0103]

EXAMPLES The present invention will be described below in more detail with reference to Examples, but the present invention is not limited to these Examples.

In the examples and comparative examples, the amount of formaldehyde generated from the melts, dry and wet molded products was evaluated as follows.

[Amount of Formaldehyde Generated from Melt]
5 g of pellets are accurately weighed and placed in a metal container.
After holding at 5 ° C. for 5 minutes, the atmosphere in the container is absorbed into distilled water. The amount of formaldehyde in this aqueous solution was determined according to JIS
K0102, 29. The amount was determined according to (formaldehyde) and the amount of formaldehyde gas (ppm) generated from the pellet was calculated.

[Amount of Formaldehyde Generated from Molded Product in Dry Type] Ten test pieces (2 mm × 2 mm × 50 mm) (total surface area: about 40 cm ² ) of resin samples were placed in a closed container (capacity: 20 m).
After heating in a constant temperature bath at a temperature of 80 ° C. for 24 hours, the mixture was air-cooled to room temperature, and 5 ml of distilled water was injected with a syringe. The amount of formaldehyde in this aqueous solution was determined according to JIS K
0102,29. (Formaldehyde), the amount of formaldehyde gas generated per surface area (μ
g / cm ² ).

[Amount of Formaldehyde Emitted from Wet Molded Article] Test piece (100 mm × 40 mm × 2 mm; total surface area 8) obtained by cutting four sides from a flat molded article (120 mm × 120 mm × 2 mm)
5.6 cm ² ) is hung on a lid of a polyethylene bottle (capacity: 1 L) containing 50 ml of distilled water, sealed tightly, and placed in a thermostat at a temperature of 6 cm ^2.
After leaving at 0 ° C. for 3 hours, it is left at room temperature for 1 hour. Determine the formalin content of the aqueous solution in the polyethylene bottle according to JIS K01.
02, 29. (Formaldehyde), the amount of formaldehyde generated per surface area (μg / c)
m ² ) was calculated.

Examples 1 to 20 and Comparative Examples 1 to 4 After 100 parts by weight of a polyacetal resin were mixed with a carboxyl group-containing compound, an antioxidant, a metal compound, a stabilizer and a nitrogen-containing compound in the proportions shown in Table 1, The mixture was melt-mixed with a twin-screw extruder to prepare a pellet-shaped composition. Using these pellets, the amount of formaldehyde generated from the melt was evaluated. Further, a test piece was molded by an injection molding machine, and the amount of formaldehyde generated from the test piece was measured. The results are shown in Tables 1 and 2.

For comparison, examples in which the carboxyl group-containing compound was not added and examples in which phthalic acid having a pKa of less than 3.6 was used as the carboxyl group-containing compound were as follows.
Evaluation was performed in the same manner as above.

The polyacetal resin, carboxyl group-containing compound, antioxidant, metal compound, stabilizer, and nitrogen-containing compound used in Examples and Comparative Examples are as follows.

[0111] 1. 1. Polyacetal resin (a): polyacetal resin copolymer “Duracon” manufactured by Polyplastics Co., Ltd. Carboxyl group-containing compound (b-1): Ethylene-acrylic acid copolymer Acrylic acid modification rate: 5% by weight "ALYN # 54" manufactured by Allied Signal Co., Ltd.
0 "(b-2): Ethylene-methacrylic acid copolymer Methacrylic acid modification rate: 5% by weight Mitsui-Dupont Polychemical Co., Ltd.," Nucrel A "
N4214C "(b-3): Ethylene-methacrylic acid copolymer Methacrylic acid modification ratio: 9% by weight Mitsui-DuPont Polychemical Co., Ltd.," Nucrel N "
0908C "(b-4): Ethylene-methacrylic acid copolymer Methacrylic acid modification rate: 12% by weight Mitsui-Dupont Polychemical Co., Ltd.," Nucrel A "
N1207C "(b-5): Ethylene-methacrylic acid copolymer Methacrylic acid modification rate: 15% by weight Mitsui-Dupont Polychemical Co., Ltd.," Nucrel A "
N1525 "(b-6): adipic acid (pKa ₁ = 4.26) (b-7): benzoic acid (pKa = 4.00) (b-8): stearic acid (pKa> 4) (b-9) ): 12-hydroxystearic acid (pKa>)
4) (b-10): cyclohexanecarboxylic acid (pKa =
4.70) (b-11): phthalic acid (pKa ₁ = 2.75) Antioxidant (c-1): pentaerythritol tetrakis [3-
(3,5-di-t-butyl-4-hydroxyphenyl)
Propionate] (c-2): Triethylene glycol bis [3- (3-
t-butyl-5-methyl-4-hydroxyphenyl) propionate] 4. Metal compound (d): magnesium oxide Stabilizer (e-1): glycerin monostearate (e-2): polyethylene glycol monostearate "Nonion S-40" manufactured by NOF Corporation (f-1): 2- [2-hydroxy- 3,5-bis (α, α-dimethylbenzyl) phenyl] benzotriazole (f-2): bis (2,2,6,6-tetramethyl-4
-Piperidyl) sebacate 6. Nitrogen-containing compound (g-1): melamine (g-2): melamine-formaldehyde resin Using 1.2 mol of formaldehyde with respect to 1 mol of melamine, a reaction is carried out in an aqueous solution at pH 8, at a temperature of 70 ° C., and the reaction system becomes cloudy. Without this, a water-soluble precondensate melamine-formaldehyde resin was produced. Next, the reaction system was adjusted to pH 6.5 with stirring, and stirring was continued to precipitate a melamine-formaldehyde resin, followed by drying to obtain a crude melamine-formaldehyde resin powder.
The powder was washed with warm water at 60 ° C. for 30 minutes, filtered, and the residue was washed with acetone and dried to obtain a purified melamine-formaldehyde resin as a white powder.

(G-3): Allantoin, manufactured by Kawaken Fine Chemical Co., Ltd. (g-4): Allantoin dihydroxyaluminum, manufactured by Kawaken Fine Chemical Co., Ltd., “ALDA” (g-5): Biurea (g-6): Form nitrogen 2 mol powder, manufactured by Mitsui Chemicals, Inc. (g-7): benzoguanamine (g-8): 2,4,8,10-tetraoxaspiro (5.5) undecane-3,9-bis (2 -Ethylguanamine) (g-9): creatinine

[0113]

[Table 1]

[0114]

[Table 2]

As is clear from the table, compared to the comparative example,
Since the amount of formaldehyde generated in the resin compositions of the examples is extremely small, the working environment can be greatly improved, and the quality and moldability of molded articles can be improved.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) // (C08L 59/00 33:06)

Claims (10)

[Claims] 1. A polyacetal resin having a pKa of 3.6.
A polyacetal resin composition containing the above carboxyl group-containing compound. 2. The polyacetal resin composition according to claim 1, wherein the carboxyl group-containing compound is at least one organic carboxylic acid selected from aliphatic carboxylic acids, alicyclic carboxylic acids, and aromatic carboxylic acids. 3. A polyacetal resin having at least α,
a polymer having a β-ethylenically unsaturated carboxylic acid as a monomer unit, the polymer being an effective amount or more and less than 1 part by weight based on 100 parts by weight of a polyacetal resin. A polyacetal resin composition containing: 4. The polyacetal resin composition according to claim 3, wherein the polymer is a copolymer of an α, β-ethylenically unsaturated carboxylic acid and an olefin. 5. The polyacetal resin composition according to claim 3, wherein the polymer is an ethylene- (meth) acrylic acid copolymer. 6. The polyacetal resin composition according to claim 3, wherein the content of the α, β-ethylenically unsaturated carboxylic acid unit in the polymer is 1 to 30% by weight. 7. The polyacetal resin composition according to claim 3, wherein the content of the α, β-ethylenically unsaturated carboxylic acid unit in the polymer is 2 to 25% by weight. 8. The polyacetal resin composition according to claim 1, further comprising at least one selected from an antioxidant, an alkali or alkaline earth metal compound and a stabilizer. 9. The method according to claim 1, further comprising at least one nitrogen-containing compound selected from urea, mono-N-substituted urea, urea condensate, melamine or a derivative thereof, guanamine or a derivative thereof, and creatinine or a derivative thereof. 3
Or the polyacetal resin composition according to 8. 10. A polyacetal resin molded article comprising the polyacetal resin composition according to claim 1.