JP3695913B2 - Polyacetal resin composition and method for producing the same - Google Patents

Description

表より明らかなように、比較例に比べて、実施例の樹脂組成物は、ホルムアルデヒドの発生量が極めて小さく、金型への付着物や成形品からの滲出物の量が極めて少ない。そのため、作業環境を大きく改善できるとともに、成形性を向上できる。[0001]
BACKGROUND OF THE INVENTION
TECHNICAL FIELD The present invention relates to a polyacetal resin composition that is remarkably suppressed in formaldehyde generation during processing and has excellent processability, and a method for producing the same.
[0002]
[Prior art]
Polyacetal resin has excellent mechanical properties, fatigue resistance, friction and wear resistance, chemical resistance and moldability, so it can be used for automobile parts, electrical / electronic equipment parts, other precision machine parts, building materials / piping members, Widely used in fields such as daily life and cosmetic parts and medical parts. However, with the expansion and diversification of applications, the demand for quality has been increasing. The properties required for polyacetal resin are that the mechanical strength does not decrease during processing such as extrusion or molding, that there is no deposit on the mold (mold deposit), and long-term heating conditions (heat aging). For example, the mechanical properties do not deteriorate, and molding defects such as silver streaks and voids do not occur. One important factor in these phenomena is the degradation of the polymer upon heating.
[0003]
Because of its chemical structure, the polyacetal resin is easily easily decomposed under acidic and alkaline conditions in a heated oxidizing atmosphere. In order to stabilize chemically active terminals, homopolymers are esterified by polymerizing the polymer terminals by acetylation, etc., and copolymers are formed by adjacent carbon bonds such as trioxane, cyclic ether and cyclic formal during polymerization. A method is known in which an unstable terminal portion is decomposed and removed to form an inactive stable terminal after copolymerization with a monomer having the monomer. However, cracking also occurs in the main chain part of the polymer during heating, and the prevention cannot be dealt with by the above treatment alone, and the addition of antioxidants and other stabilizers is essential for practical use. .
[0004]
However, even if these stabilizers are blended, it is difficult to completely suppress the decomposition of the polyacetal resin. In practice, during the extrusion for preparing the composition and the melt processing in the molding process, an extruder or Under the action of heat and oxygen in the cylinder of the molding machine, formaldehyde is generated from the end of the main chain which is not sufficiently stabilized and is not sufficiently stabilized, deteriorating the working environment during extrusion molding. In addition, if molding is performed for a long time, fine powder and tar-like materials adhere to the mold (mold deposit), which is one of the greatest factors that reduce the work efficiency and the surface condition of the molded product. Yes. Furthermore, degradation of the polymer causes a decrease in mechanical strength and a color change of the resin. From such a point, with respect to the polyacetal resin, a great effort has been continued in search of a more effective stabilization formulation.
[0005]
As antioxidants added to polyacetal resins, sterically hindered phenolic compounds (hindered phenols) and sterically hindered amine compounds (hindered amines) are known. Other stabilizers include urea derivatives and melamine derivatives. Amidine compounds, alkali metal hydroxides, alkaline earth metal hydroxides, organic or inorganic acid salts, and the like are used. Usually, the antioxidant is 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.
[0006]
[Problems to be solved by the invention]
Accordingly, an object of the present invention is to provide a resin composition that can improve the stability of a polyacetal resin, in particular, the melt stability during molding, and a method for producing the same.
Another object of the present invention is to provide a polyacetal resin composition that can remarkably suppress the formation of formaldehyde with a small amount of addition and improve the working environment, and a method for producing the same.
Still another object of the present invention is to provide a polyacetal resin composition that can suppress the formation of formaldehyde, suppress the adhesion of decomposition products to the mold, improve the quality of the molded product, and improve the moldability. It is to provide a method.
[0007]
[Means for Solving the Problems]
In order to achieve the above-mentioned object, the present inventors have conducted a search for a series of urea derivatives for a stabilizer of a polyacetal resin, and as a result, a glyoxydiureide compound having a specific chemical structure is a stabilizer of a polyacetal resin, In particular, the present invention has been found to have a remarkable effect as a stabilizer during processing, and the present invention has been completed.
That is, the polyacetal resin composition of the present invention is composed of a polyacetal resin and a glyoxydiureide compound. Examples of the glyoxydiureide compound include glyoxydiureide and glyoxydiureido metal salts. The usage-amount of a glyoxy diureido compound is about 0.01-10 weight part with respect to 100 weight part of polyacetal resin, for example. The composition may further contain an antioxidant.
[0008]
In the method of the present invention, a polyacetal resin composition with improved processing stability is produced by mixing a polyacetal resin and a glyoxydiureide compound.
[0009]
In the present specification, the “glyoxydiureide compound” is not limited to glyoxydiureide, but is used to include derivatives derived from glyoxydiureido.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The resin composition of the present invention is composed of a polyacetal resin and a glyoxydiureido compound.
The polyacetal resin is an oxymethylene group (—CH₂O-) as a main structural unit, a polyacetal homopolymer (for example, product name “Dellin” manufactured by Asahi Kasei Co., Ltd., product name “Tenac 4010”, etc., manufactured by DuPont, USA), oxymethylene group In addition, polyacetal copolymers containing other comonomer units (for example, trade name “Duracon” manufactured by Polyplastics Co., Ltd.) are included. In the copolymer, the comonomer unit includes an oxyalkylene unit (for example, an oxyethylene group (—CH 2) having about 2 to 6 carbon atoms (preferably about 2 to 4 carbon atoms).₂CH₂O-), an oxypropylene group, an oxytetramethylene group, and the like. The content of the comonomer unit is a small amount, for example, 0.01 to 20 mol%, preferably 0.03 to 10 mol% (for example, 0.05 to 5 mol%), more preferably, based on the whole polyacetal resin. It can select from the range of about 0.1-5 mol%.
[0011]
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. Moreover, 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 by esterification with a carboxylic acid such as acetic acid or propionic acid. The polymerization degree, branching degree, and crosslinking degree of the polyacetal are not particularly limited as long as it can be melt-molded.
[0012]
The polyacetal resin can be produced, for example, by polymerizing aldehydes such as formaldehyde, paraformaldehyde, acetaldehyde, cyclic ethers such as trioxane, ethylene oxide, propylene oxide, 1,3-dioxolane, and cyclic formal.
[0013]
The feature of the present invention is that by adding a glyoxydiureido compound, which is a specific urea derivative, the processing stability of the polyacetal resin is remarkably improved and the generation of formaldehyde is remarkably suppressed. When the glyoxydiureido compound is used, a stabilizing effect far surpassing that of conventional stabilizers is exhibited, and a polyacetal resin composition having excellent processability can be obtained.
[0014]
Glyoxydiureido compounds include glyoxydiureido (ie, allantoin) and glyoxydiureido derivatives. For glyoxydiureido derivatives, the document “DICTIONARY OF ORGANIC COMPOUNDS Vol.1, p60 (1965 EYRE & SPOTTISWOODE-PUBLISHERS-LTD) ”. Examples of the glyoxydiureido derivative include substituted glyoxydiureide 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-methyl, 1,3-dimethyl, 1,6-dimethyl, 1,8-dimethyl, 3,8-dimethyl, 1,3,6-trimethyl, 1,3,8- Mono-, di- or tri-C such as trimethyl_1-4Alkyl-substituted products, aryl-substituted products such as 5-phenyl compounds, etc.), salts of glyoxydiureides and metals [alkali metal salts such as Li, Na, K (group 1A metal salts of the periodic table), Mg, Ca, Sr Alkaline earth metal salts (Group 2A metal salts) such as Ba, Ba, salts with Group 1B metals such as Cu and Ag, salts with Group 2B metals such as Zn, Al, Ga, In, etc. Of the periodic table group 3B metal, periodic table 4 such as Sn, Pb, salt with the group 4B metal, salt with periodic group 8 metal such as Fe, Co, Ni, Pd, Pt, etc.], glyoxydiureide Product of nitrogen and a nitrogen-containing compound (amino group or imino group-containing compound) [for example, a compound (salt, molecular compound (complex), etc.) with 2-pyrrolidone-5-carboxylate, a basic amino acid (arginine) , Lysine, ornithine, etc.) Compounds (salts, molecular compounds (complexes), etc.), and compounds (salts, molecular compounds (complexes), etc.) of glyoxydiureido and imidazole compounds.glyoxydiureido and 2-pyrrolidone-5-carboxylic acid JP-A-51-36453 can be referred to for the compound with the salt, and JP-A-52-102412 and JP-A-52-25771 for the reaction product of glyoxydiureide and a basic amino acid. No. 5, No. 52-25772, No. 52-310107, No. 51-19771, etc. The compound of glyoxydiureide and an imidazole compound can be referred to. No. 57-118569, etc. The three-dimensional structure of glyoxydiureido and its derivatives is not particularly limited, and d-form, l-form and It may be any of the dl form. These glyoxylate Ji-laid and its derivatives may be used singly or in combination.
[0015]
Preferred glyoxydiureido compounds include glyoxydiureide, glyoxydiureide metal salts [alkali metal salts, alkaline earth metal salts, periodic table group 1B metal salts, periodic table group 2B metal salts, periodic table group 3B. Metal salts, periodic table group 4B metal salts, periodic table group 8 metal salts and the like, especially polyvalent metal salts of about 2 to 4 valences], reaction products of glyoxydiureide and amino group or imino group-containing compounds, etc. included. Specific examples of glyoxydiureide metal salts include allantoin dihydroxyaluminum and allantoin chlorohydroxyaluminum (produced by Kawaken Fine Chemical Co., Ltd.), and examples of reaction products with amino group or imino group-containing compounds. And allantoinsodium-dl pyrrolidone carboxylate (manufactured by Kawaken Fine Chemical Co., Ltd.).
[0016]
The addition amount of the glyoxydiureido compound is, for example, 0.01 to 10 parts by weight, preferably about 0.03 to 5 parts by weight, and 0.05 to 2.5 parts by weight with respect to 100 parts by weight of the polyacetal resin. Even so, the formation of formaldehyde can be remarkably suppressed. If the added amount of the glyoxydiureido compound is less than 0.01 parts by weight, it is difficult to effectively reduce the amount of formaldehyde generated, and if it exceeds 10 parts by weight, the moldability and the hue are lowered, and the bleeding phenomenon is caused. It tends to occur.
[0017]
The glyoxydiureide compound may be used alone or can provide significant stability to the polyacetal resin, but may be used in combination with an antioxidant, a nitrogen-containing compound, or the like.
[0018]
Antioxidants include, for example, phenolic (such as hindered phenols), amine, phosphorus, sulfur, hydroquinone, and quinoline antioxidants.
[0019]
Phenol 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-tert-butylphenol), 2,6-di-tert-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-tert-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-tert-butyl-5-methyl-4) Hydroxyphenyl) propionate], n-octadecyl-3- (4 ′, 5′-di-t-butylphenol) propionate, n-octadecyl-3- (4′-hydroxy-3 ′, 5′-di-t-butylphenol) ) Propionate, stearyl-2- (3,5-di-t-butyl-4-hydroxyphenol) propionate, distearyl-3,5-di-t-butyl-4-hydroxybenzylphosphonate, 2-t-butyl- 6- (3-tert-butyl-5-methyl-2-hydroxybenzyl) -4-methylphenyl acrylate, N, N'-hexamethylenebis (3,5-di-tert-butyl-4-hydroxy-hydrocin Namamide), 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-tert-butylphenol), 1,1, 3-tris (2-methyl-4-hydroxy-5-tert-butylphenol) butane and the like are included.
[0020]
Amine-based antioxidants include hindered amines such as 4-methoxy-2,2,6,6-tetramethylpiperidine, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, 4-phenoxy- 2,2,6,6-tetramethylpiperidine, bis- (2,2,6,6-tetramethyl-4-piperidyl) ogisalate, 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-tetra Til-4-piperidyloxy) ethane, phenyl-1-naphthylamine, phenyl-2-naphthylamine, N, N′-diphenyl-1,4-phenylenediamine, N-phenyl-N′-cyclohexyl-1,4-phenylenediamine Etc. are included.
[0021]
Examples of phosphorus 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-tert-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, tris (2-t-phenylphenyl) ) Phosphite, Tris [2- (1,1-dimethylpropyl) -phenyl] phos And tris [2,4- (1,1-dimethylpropyl) -phenyl] phosphite, tris (2-cyclohexylphenyl) phosphite, tris (2-t-butyl-4-phenylphenyl) phosphite, etc. It is.
[0022]
Examples of the hydroquinone antioxidant include 2,5-di-t-butylhydroquinone, and examples of the quinoline antioxidant include 6-ethoxy-2,2,4-trimethyl-1,2. -Dihydroquinoline and the like are included, and sulfur-based antioxidants include, for example, dilauryl thiodipropionate, distearyl thiodipropionate, and the like.
[0023]
These antioxidants can be used alone or in combination of two or more. Preferred antioxidants include phenolic antioxidants (particularly hindered phenols). Among hindered phenols, in particular, C such as 1,6-hexanediol-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], for example._2-10Alkylenediol-bis [3- (3,5-di-branched C_3-6  Alkyl-4-hydroxyphenyl) propionate]; di- or trioxy C such as, for example, triethylene glycol-bis [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate]_2-4Alkylenediol-bis [3- (3,5-di-branched C_3-6Alkyl-4-hydroxyphenyl) propionate]; for example, glycerol tris [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate]_3-8Alkylenetriol-bis [3- (3,5-di-branched C_3-6Alkyl-4-hydroxyphenyl) propionate]; for example C such as pentaerythritol tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate]_4-8Alkylenetetraol tetrakis [3- (3,5-di-branched C_3-6Alkyl-4-hydroxyphenyl) propionate] and the like.
[0024]
These antioxidants can be used alone or in combination of two or more. The content of the antioxidant is, for example, in the range of 0.01 to 5 parts by weight, preferably 0.05 to 2.5 parts by weight, particularly about 0.1 to 1 part by weight with respect to 100 parts by weight of the polyacetal resin. You can choose from.
[0025]
Nitrogen-containing compounds include, for example, nitrogen-containing resins (polyamide, polyamideimide, polyesteramide, etc.), secondary or tertiary amines (such as aromatic amines), hydrazines (hydrazine derivatives such as hydrazine, hydrazone and hydrazide). ), Uracil or derivatives thereof, cytosine or derivatives thereof, guanidine or derivatives thereof, ureas (urea, thiourea or derivatives thereof), benzoguanamines, polyaminotriazoles (melamine or derivatives thereof), polyaminothioethers, and the like.
These nitrogen-containing compounds can be used alone or in combination of two or more. The amount of nitrogen-containing compound used is, for example, 0.01-5 parts by weight, preferably 0.05-2. It can be selected from a range of about 5 parts by weight (particularly 0.1 to 1 part by weight).
The antioxidant and the nitrogen-containing compound may be used in combination.
[0026]
Furthermore, the ratio (weight ratio) between the glyoxydiureido compound (A) and the antioxidant and / or the nitrogen-containing compound (B) is, for example, the former (A) / the latter (B) = 0.1 to 10 , Preferably 0.2 to 10, more preferably about 0.5 to 7 (especially 1 to 7). In particular, when the proportion of the glyoxydiureido compound is increased, the amount of formaldehyde produced can be greatly improved. Therefore, the ratio (weight ratio) of both is preferably the former (A) / the latter (B) = 1.0 to 10, preferably 1.2 to 10, more preferably 1.5 to 5, particularly 1.7 to. About 5 (for example, 2 to 5).
The total amount of components (A) and (B) in such a proportion is usually 0.1 to 5 parts by weight, preferably 0.2 to 3 parts by weight, more preferably 0.8 parts per 100 parts by weight of the polyacetal resin. It is about 5 to 2 parts by weight (particularly 0.5 to 1.5 parts by weight).
[0027]
In the resin composition of the present invention, various additives, for example, colorants including dyes and pigments, mold release agents, nucleating agents, antistatic agents, flame retardants, surfactants, various polymers, and fillers are used as necessary. These may be added singly or in combination of two or more.
[0028]
The polyacetal resin composition of the present invention may be a granular mixture or a molten mixture, and can be prepared by mixing a polyacetal resin, a glyoxydiureide compound, and, if necessary, other additives by a conventional method. . For example, (1) mixing each component, kneading with a uniaxial or biaxial extruder and extruding to prepare pellets, and (2) once preparing pellets (master batch) with different compositions , A method in which the pellets are mixed (diluted) in a predetermined amount and subjected to molding to obtain a molded product having a predetermined composition. (3) After the glyoxydiureide compound is adhered to the pellets of the polyacetal resin by spraying or the like, the molding is performed. A method for obtaining a molded product having a predetermined composition can be employed. Further, in the preparation of a composition used for a molded article, a granular material of a polyacetal resin as a substrate (for example, a granular material obtained by pulverizing part or all of a polyacetal resin) and other components (glyoxydiureide compound, etc.) ) And melt kneading is advantageous for improving the dispersion of the additive.
The resin composition of the present invention can remarkably suppress the formation of formaldehyde due to oxidation or thermal decomposition of a polyacetal resin in a molding process (particularly melt molding process), and can improve the working environment. In addition, adhesion of decomposition products to the mold (mold deposit) and leaching of decomposition products from molded products can be remarkably suppressed, heat aging properties can be greatly improved, and various problems during molding can be improved. Therefore, the resin composition of the present invention forms various molded products by a conventional molding method such as injection molding, extrusion molding, compression molding, blow molding, vacuum molding, foam molding, and rotational molding. Useful for.
[0029]
【The invention's effect】
Since the polyacetal resin composition of the present invention contains a glyoxydiureide compound, the stability of the polyacetal resin (particularly, the melt stability during molding) can be improved. Moreover, the formation of formaldehyde can be remarkably suppressed with a small amount of addition, and the working environment can be greatly improved. Furthermore, adhesion of the decomposition product to the mold (mold deposit) and leaching of the decomposition product from the molded product can be suppressed, and the quality and moldability of the molded product can be improved.
[0030]
【Example】
Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.
In Examples and Comparative Examples, the amount of formaldehyde generated from the melt, moldability, odor of molding environment, and heat aging were evaluated as follows.
[0031]
[Formaldehyde generation amount from melt]
5 g of pellets are accurately weighed and held in a metal container at 200 ° C. for 5 minutes, and then 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 (formaldehyde term) and calculated as the amount of formaldehyde gas (ppm) generated from the pellets.
[0032]
[Moldability (quantity of mold deposits) and environmental odor during molding]
Using an injection molding machine, the sample polyacetal resin composition was continuously molded (24 hours) into a molded product of a specific shape under the following conditions. Formaldehyde odor around the molding machine during continuous molding and the mold after 24 hours The amount of deposits was evaluated as follows.
[0033]
(Molding condition)
Injection molding machine: Toshiba IS30 EPN [manufactured by Toshiba Machine Co., Ltd.]
Cylinder temperature: 200 ° C
Injection pressure: 750kg / cm²
Injection time: 4 seconds
Cooling time: 3 seconds
Mold temperature: 30 ℃
(Evaluation of formaldehyde odor around the molding machine during continuous molding)
A: Almost no formaldehyde odor
B: Slightly formaldehyde smell
C: Equivalent formaldehyde odor, irritating throat and eyes
D: The formaldehyde odor is very intense and I cannot stay there
(Evaluation of mold deposits during continuous molding)
A: Slight deposits are observed
B: The amount of deposits is small
C: Although the amount of deposits is large, it does not adhere to the entire surface of the mold
D: There are many deposits and it has adhered to the whole surface of a metal mold | die.
[Heat aging property (evaluation of exudate on the surface of molded product)]
The molded product is allowed to stand for 3 days in an environment at a temperature of 70 ° C. and a relative humidity of 80% RH, and further left at a temperature of 120 ° C. for a whole day and night. Then, the following four grades were evaluated.
A: No exudate
B: Exudate is partially recognized
C: Exudate is slightly observed on the entire surface
D: Exudate oozes over the entire surface
Examples 1-7 and Comparative Examples 1-7
After mixing an antioxidant and a glyoxydiureide compound in the ratio shown in Table 1 with the polyacetal resin, it was melt-mixed by a twin screw extruder to prepare a pellet-shaped composition. Next, using the pellets, a molded product having a specific shape was continuously molded (24 hours) with an injection molding machine, and the above evaluation was performed. The results are shown in Table 1.
For comparison, an example in which the glyoxydiureide compound was not added and an example in which a normal stabilizer was added to the polyacetal resin were evaluated in the same manner as described above.
[0034]
The polyacetal resin, antioxidant, glyoxydiureide compound, and other stabilizers used in Examples and Comparative Examples are as follows.
1. Polyacetal resin
(A): Polyacetal resin copolymer
(“Duracon” manufactured by Polyplastics Co., Ltd.)
(B): Polyacetal resin homopolymer
("Tenac 4010" manufactured by Asahi Kasei Corporation)
2. Antioxidant
(C): Pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate]
3. Glyoxydiureido compounds
(D): Glyoxydiureido
(E): Allantoin dihydroxyaluminum
(Kawaken Fine Chemical Co., Ltd.)
4). Other stabilizers
(F): Ethylene urea
(G): Melamine
(H): Hydantoin
(I): 5,5, -dimethylhydantoin
[0035]
[Table 1]

As is clear from the table, the resin compositions of the examples have a very small amount of formaldehyde generated and a very small amount of deposits on the mold and exudates from the molded product compared to the comparative examples. Therefore, the work environment can be greatly improved and the moldability can be improved.

Claims (9)

A polyacetal resin composition comprising a polyacetal resin and a glyoxydiureido compound. The polyacetal resin composition according to claim 1, wherein the glyoxydiureido compound is glyoxydiureide. The polyacetal resin composition according to claim 1, wherein the glyoxydiureide compound is a salt of glyoxydiureide and a metal. The glyoxydiureide compound is glyoxydiureide, alkali metal, alkaline earth metal, periodic table group 1B metal, periodic table group 2B metal, periodic table group 3B metal, periodic table group 4B metal, periodic table group 8 metal The polyacetal resin composition according to claim 1, which is a salt with at least one metal selected from the group consisting of: The polyacetal resin composition according to claim 1, wherein the glyoxydiureido compound is allantoin dihydroxyaluminum. The polyacetal resin composition according to claim 1, wherein the amount of the glyoxydiureido compound used is 0.01 to 10 parts by weight with respect to 100 parts by weight of the polyacetal resin. Furthermore, the polyacetal resin composition of Claim 1 containing antioxidant. The polyacetal resin composition of Claim 7 whose ratio (weight ratio) of a glyoxy diureido compound and antioxidant is the former / latter = 1.0-10. A method for producing a polyacetal resin composition comprising mixing a polyacetal resin and a glyoxydiureido compound.