JPH06256622A - Polyacetal resin composition - Google Patents

Abstract

PURPOSE:To obtain the subject composition excellent in weather (light) resistance and improved in thermal stability especially during molding. CONSTITUTION:100 pts.wt. polyacetal resin is mixed with 0.01-0.50 pt.wt. n- octadecyl-3-[3,5-di-t-butyl-4-hydroxyphenyl[ propionate, 0.10-1.0 pt.wt. bis-[N- methyl-2,2,6,6=tetramethyl-4-piperidinyl] sebacate and 0.10-1.0 pt.wt. ultraviolet absorber, and the mixture is uniformly melt-compounded to give the objective polyacetal resin composition excellent in weather (light) resistance and improved in the thermal stability especially during molding.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a polyacetal resin composition having improved weather resistance and thermal stability. More specifically, the present invention provides a polyacetal resin with an antioxidant n-octadecyl-3- [3,5-di-t-butyl-4-hydroxyphenyl] propionate and a light stabilizer bis- [N-methyl- 2,2,6,6-Tetramethyl-4-piperidinyl] sebacate, and an ultraviolet absorber are added and blended and uniformly melt-mixed to obtain weather resistance (light) resistance and thermal stability, particularly molding. The present invention relates to a polyacetal resin composition having improved thermal stability during processing.

The polyacetal resin of the present invention has a weather resistance (light) without impairing the original properties of the polyacetal resin.
The heat resistance and thermal stability are highly improved and the mechanical properties are excellent, so it is used for a long time exposed to sunlight or indoor lights, especially where it is further exposed to wind and rain. It can be used as a part, for example, an out-handle of an automobile, a wheel cover, a front fender, a part of an electric device, or a material such as a building material or a packer of a vinyl house.

[0003]

2. Description of the Related Art Polyacetal resin compositions have physical properties such as friction and wear resistance, fatigue resistance, heat resistance and electrical properties, and chemical properties such as chemical resistance and water resistance. Because it is excellent, it is used as a component in the electric and electronic fields, the construction field, the automobile industry and the sundries field.

It is known that the polyacetal resin, which is the material of the polyacetal resin composition, has poor thermal stability and causes a thermal decomposition reaction in the melt-kneading operation carried out during its molding process. Therefore, various antioxidants and heat stabilizers are added to prevent the thermal decomposition reaction during the molding process. Further, when the polyacetal resin is exposed to sunlight or indoor light for a long time, particularly when it is further exposed to wind and rain, first, cracks are generated on the surface, the gloss is lost with the progress thereof, and the appearance is deteriorated. It is known that as the appearance deteriorates, the mechanical properties significantly decrease and lose the practicality and practical value. In order to prevent the deterioration due to light such as sunlight, a light stabilizer and an ultraviolet absorber are added.

The heat resistance is improved by adding an antioxidant or a heat stabilizer to a polymer material, that is, a synthetic resin, but the antioxidant added here sometimes acts as a photosensitizer. A photosensitizing effect is caused to deteriorate the weather resistance. Further, as a method of improving the weather resistance of the polymer material, a light stabilizer, for example, a method of adding a hindered amine type, an ultraviolet absorber, for example, a method of adding a benzotriazole type, a benzophenone type, a light stabilizer and an ultraviolet absorber. Although there is a method to use together, the weather resistance (light) is improved by adding a light stabilizer or an ultraviolet absorber alone without using an antioxidant, or by using a light stabilizer and an ultraviolet absorber together. There is no effect of improving sex. In particular, in the case of polyacetal resin, which has poor thermal stability among polymer materials, without an antioxidant, the thermal stability during molding is extremely poor, and silver appears on the product surface and around the cavity and core of the mold. Mold deposits are likely to occur.

However, in general, even if a polymeric material, particularly a polyacetal resin, is added with an antioxidant, a light stabilizer, an ultraviolet absorber, etc., depending on the selection, in other words, the combination thereof, an antagonistic action is obtained. Often occurs, the effect thereof, that is, the effect of improving weather resistance (light) resistance cannot be obtained, and the intended purpose is often not achieved. Therefore, in particular, the antioxidant, the light stabilizer, the ultraviolet absorber, etc. to be added / blended to the polyacetal resin must be experimentally confirmed and selected by trial and error to determine the effect.

Further, it has been known that the improvement of the weather (light) resistance of the polyacetal resin is considerably effective by adding a hindered amine light stabilizer alone or in combination with an ultraviolet absorber. It is not always satisfactory depending on the purpose of use. For example, when a high molecular weight hindered amine-based light stabilizer is used, its migration property is poor. Therefore, in order to obtain sufficient weather (light) resistance, a very large amount must be added, which results in mechanical properties of the product. Is not practical because it causes problems such as a decrease in power consumption and an increase in cost. On the other hand, when a low molecular weight hindered amine-based light stabilizer is used, problems such as poor appearance of the product due to bleeding out of the additive occur despite the small amount of addition.
Further, since the amount of the additive volatilized during molding is large, increasing the amount added does not lead to improvement in weather resistance.

[0008]

DISCLOSURE OF THE INVENTION In order to solve the above-mentioned problems, the inventors of the present invention conducted extensive studies on polyacetal resin compositions, and as a result, identified polyacetal resins as specific hindered phenol compounds. Addition and blending of hindered amine compounds and UV absorbers such as benzotriazole, and by uniformly kneading and mixing, the original polyacetal resin has excellent friction and wear resistance and fatigue resistance. , And, without impairing the chemical resistance and electrical properties, thermal stability during molding, and obtain the finding that it is possible to obtain a polyacetal resin composition having excellent weather (light) resistance, Further, technical improvement and reproducibility confirmation experiments were conducted to complete the present invention.

[0009]

DISCLOSURE OF THE INVENTION The present invention comprises a polyacetal resin and an antioxidant n-octadecyl-3- [3,3].
5-di-t-butyl-4-hydroxyphenyl] propionate and light stabilizer bis- [N-methyl-2,2,6,6]
6-Tetramethyl-4-piperidinyl] sebacate, and a polyacetal resin composition with improved weather resistance (light) resistance and thermal stability obtained by adding and blending an ultraviolet absorber and uniformly kneading and mixing Regarding things. More specifically, according to the present invention, n-octadecyl-3- [3,5-di-t is added to 100 parts by weight of the polyacetal resin (A).
-Butyl-4-hydroxyphenyl] propionate (B) 0.01 to 0.50 parts by weight and bis- [N-methyl-2,2,6,6-tetramethyl-4-piperidinyl]
Weather resistance obtained by adding and blending 0.10 to 1.0 part by weight of sebacate (C) and 0.10 to 1.0 part by weight of ultraviolet absorber (C), and uniformly kneading and mixing. , A polyacetal resin composition having improved thermal stability.

In the present invention, the polyacetal resin (A) means a polyacetal (polyoxymethylene) and a polyacetal copolymer which are already commercially available. More specifically, for example, formaldehyde or its trimer (trioxane),
And an oxymethylene homopolymer substantially composed of an oxymethylene unit structure produced from the tetramer (tetraoxane) as a raw material, and / or formaldehyde, or a trimer thereof (trioxane), and its quaternary amount Body (tetraoxane) and ethylene oxide, epichlorohydrin, 1,3-dioxolane, 1,
Oxygen containing 0.1 to 20% by weight of an oxyalkylene unit structure produced from a cyclic ether having 2 to 8 carbon atoms such as 3,5-trioxepane, glycol formal, diglycol formal, and diglycol formal. Methylene copolymer, and / or oxymethylene homopolymer, or block structure other than oxymethylene unit structure having oxymethylene copolymer as a main structure, or oxymethylene block copolymer having a terminal structure, or oxymethylene graft polymer, or It means a known oxymethylene crosslinked polymer having a crosslinked structure.

The antioxidant (B) added / blended in the present invention has the following general formula:

[0012]

[Chemical 1]

[Wherein R ₁ and R ₂ represent a hydrogen atom, a linear lower alkyl group or a branched lower alkyl group, and R ₃ represents a linear higher alkyl group or a branched higher alkyl group. n is
Means an integer. ] Higher alkyl-3- represented by
Among [3,5-di-substituted-4-hydroxyphenyl] alkylcarbolates, R1 and R2 are t-butyl groups, R3 is n-octadecyl, and n is 2 n-octadecyl-3- [ 3,5-di-t-butyl-4-hydroxyphenyl] propionate (B), that is, a specific hindered phenol compound.

The light stabilizer (C) added / blended in the present invention has the following formula:

[0015]

[Chemical 2] Is a bis- [N-methyl-2,2,6,6-tetramethyl-4-piperidinyl] sebacate (C) represented by, that is, a specific hindered amine compound.

In the present invention, the antioxidant is limited to n-octadecyl-3- [3,5-di-t-butyl-4-hydroxyphenyl] propionate because of the synthesis and availability of the compound. However, it is not based on the action and effect as an antioxidant. That is, the selection and limitation are based on the fact that the effect of the compound as an antioxidant has not been experimentally confirmed. Therefore, in the near future, n-octadecyl-3
Compounds other than-[3,5-di-t-butyl-4-hydroxyphenyl] propionate, that is, several kinds of compounds represented by the above general formula have been synthesized and subjected to experiments and evaluation tests. It is expected and expected that it will be confirmed as an experimental fact that it has the same effect.

In the present invention, the antioxidant is n-
Limited to octadecyl-3- [3,5-di-t-butyl-4-hydroxyphenyl] propionate is
Deterioration of the effect of improving weather resistance (light) due to an antagonistic action with a light stabilizer or an ultraviolet absorber which is used in combination with the compound,
It is based on the experimental results that it is practically small.

The polymeric material, especially the antagonistic action between the antioxidant and the light stabilizer in the polyacetal resin composition, and the ultraviolet absorber, in other words, the desired weather resistance (light) resistance and heat stability. In order to clarify the reason why it cannot be obtained and the mechanism of action, it is necessary to wait for future detailed research results. From the experimental results obtained so far, it is inferred that the operation of adding / blending a hindered phenolic antioxidant and an ultraviolet absorber and / or a light stabilizer to the polyacetal resin, more specifically, melting It can be said that the ultraviolet absorber and / or the light stabilizer and the antioxidant are consumed by a chemical reaction during kneading.

The antioxidant of the present invention exerts an excellent effect of improving weather resistance (light resistance), that is, an ultraviolet absorber which is used in combination under the melt-kneading condition, and / or
It is considered that it hardly reacts with the light stabilizer, in other words, it hardly reacts and is hardly consumed, that is, the mutual antagonistic action is extremely small. Further, the antioxidant of the present invention, that is, n-octadecyl-3- [3,5-di-
t-butyl-4-hydroxyphenyl] propionate, an ultraviolet absorber to which a combined use / addition of, and / or
It is difficult for the light stabilizer to react with the antioxidant of the present invention, that is, n-octadecyl-3- [3,5-di-t-butyl-4-hydroxyphenyl] propionate has in its molecular structure. In one phenol group, the steric hindrance of the t-butyl group at the 2 and 6-positions and the steric effect of the residue containing the sterically bulky aliphatic long-chain alkyl group at the 4-position, more specifically, from the antioxidant It is considered to shield and stabilize the phenol radicals and carbon radicals generated in the phenol ring.

Further, in the present invention, the light stabilizer is bis- [N-methyl-2,2,6,6-tetramethyl-4-
What is limited to piperidinyl] sebacate is the weather resistance (light) of the polyacetal resin composition by the addition of the compound.
It is based on the experimental results that the effect of improving the property is great, and that problems such as defective appearance of the product due to volatilization of the additive and bleed-out of the additive do not occur during the molding process.

The reason why the light stabilizer of the present invention is excellent is that it is hardly consumed by the antioxidant n-octadecyl-3- [3,5-di-t-butyl-4-hydroxyphenyl] propionate. It is considered that the molecular weight is appropriate. For example, bis- [N-methyl-2,2,6,6-
When a hindered amine-based light stabilizer having a larger molecular weight than tetramethyl-4-piperidinyl] sebacate is used, its migration property is poor. Therefore, if sufficient weather resistance (light) resistance is to be obtained, a very large amount must be added. I won't. On the other hand, when a hindered amine-based light stabilizer having a smaller molecular weight than bis- [N-methyl-2,2,6,6-tetramethyl-4-piperidinyl] sebacate is used, the addition amount is small, regardless of the addition amount. Problems such as poor appearance of the product occur due to bleeding out of the agent, and since the amount of the additive volatilized during molding is large, increasing the amount added does not lead to improvement in weather resistance.

In the present invention, the ultraviolet absorber (D) is one kind selected from the group of benzotriazole compounds, benzophenone compounds, aromatic benzoate compounds, cyanoacrylate compounds, and oxalic acid anilide compounds. The above compounds are meant. More specifically, for example, 2- (2'-hydroxy-5'-
Methyl-phenyl) benzotriazole, 2- (2'-
Hydroxy-3 ', 5'-di-t-butylphenyl) benzotriazole, 2- (2'-hydroxy-3',
5'-diisoamylphenyl) benzotriazole,
2- [2'-hydroxy-3 ', 5'-bis- (α, α
-Dimethylbenzyl) phenyl] benzotriazole,
2- (2'-hydroxy-4'-octoxyphenyl)
Benzotriazole, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone,
2-hydroxy-4-octoxybenzophenone, 2-
Hydroxy-4-dodecyloxybenzophenone, 2,
2'-dihydroxy-4-methoxybenzophenone,
2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2-hydroxy-4-oxybenzylbenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, p-t-butylphenyl salicylate, P-octylphenyl Salicylate, 2-ethylhexyl-2-cyano-3,3'-diphenyl acrylate, ethyl-2-cyano-3,3'-diphenyl acrylate, N- (2-ethoxy-5-t-butylphenyl) oxalic acid diamide, N -(2-Ethylphenyl) -N '
Examples thereof include-(2-ethoxyphenyl) oxalic acid diamide.

When the intended polyacetal resin composition is used for carrying out the present invention, it is not necessary to select a polyacetal resin having a special quality, and a powder is generally used. The objective can be sufficiently achieved by appropriately selecting from the polyacetal resins commercially available in the form of flakes or flakes in consideration of the application.

In the present invention, n-octadecyl-3
The blending amount of-[3,5-di-t-butyl-4-hydroxyphenyl] propionate, that is, the specific hindered phenolic compound (B) is the polyacetal resin 10
It is 0.01 to 0.50 parts by weight with respect to 0 parts by weight. n
-Octadecyl-3- [3,5-di-t-butyl-4-
If the blending amount of hydroxyphenyl] propionate (B) is less than 0.01 part by weight, sufficient heat resistance cannot be obtained. On the contrary, if the blending amount of the specific hindered phenol compound (B) is more than 0.50 parts by weight, the weather resistance (light) is lowered and it is economically disadvantageous, which is not preferable. Usually generally 0.20
It is preferable to select about 0.35 parts by weight.

When carrying out the present invention, the compounding amount of bis- [N-methyl-2,2,6,6-tetramethyl-4-piperidinyl] sebacate, that is, the specific hindered amine compound (C) is polyacetal. 0.10 to 1.0 part by weight, more preferably 100 parts by weight of the resin,
It is 0.10 to 0.50 parts by weight. When the content of the specific hindered amine compound (C) is less than 0.10 parts by weight, the synergistic effect with the ultraviolet absorber cannot be sufficiently exhibited, and conversely, the specific hindered amine compound (C) is used. If the compounding amount is more than 1.0 part by weight, the mechanical properties of the molded product may be deteriorated, which is not preferable.

When carrying out the present invention, the amount of the ultraviolet absorber (D) compounded is 0.1 to 1.0 part by weight based on 100 parts by weight of the polyacetal resin. If the blending amount of the ultraviolet absorber (D) is less than 0.1 part by weight, sufficient weather resistance (light) cannot be obtained. On the contrary, when the amount of the ultraviolet absorber (D) added is more than 1.0 part by weight,
Coloring of molded products and mechanical properties (physical properties) deteriorate, which is economically disadvantageous.

When carrying out the present invention, the polyacetal resin composition of the present invention may optionally further contain carbon black, a known filler, a pigment, a surfactant,
One or more kinds of antistatic agents, lubricants, nucleating agents and the like can be appropriately added within a range that does not impair the effects of the present invention. In particular, since the polyacetal resin composition of the present invention contains a hindered phenolic antioxidant, it is advantageous for improving the decrease in heat resistance of the resin due to the addition of carbon black.

When the present invention is carried out, the polyacetal resin composition of the present invention is a melt kneading apparatus which is generally known, more specifically, a single-screw or twin-screw extruder, a kneader, etc., and a pelletizer. Can be easily manufactured. More specifically explaining this,
The polyacetal resin composition of the present invention can be prepared by, for example, adding a predetermined amount of n-octadecyl-containing powder to a commercially available polyacetal resin powder (A) according to a generally known method.
3- [3,5-di-t-butyl-4-hydroxyphenyl] propionate (B) and bis- [N-methyl-2,2,6,6-tetramethyl-4-piperidinyl] sebacate (C ), Or, and the ultraviolet absorber (D) is added and blended and uniformly mixed using a super mixer, etc., and then melt-kneaded using a twin-screw extruder or the like, and subsequently pelletized. To be

Since the polyacetal composition of the present invention obtained here is excellent in thermal stability during injection molding, it is a generally known molding method, that is, an injection molding method, an extrusion molding method, a compression molding method, or a blow molding method. It can be easily molded by a molding method, a vacuum molding method, a foam molding method, or the like.

Hereinafter, the present invention will be specifically and in detail described with reference to Examples and Comparative Examples, but the following examples are for concrete description. It is not intended to limit the embodiments of the invention or the scope of the invention.

[0031]

【Example】

Example 1 100 parts by weight of polyacetal resin [manufactured by Mitsubishi Gas Chemical Co., Inc., Iupital, melt index MI10 g / 10 min], n-octadecyl-3- [3,5-di-t-butyl-4-hydroxyphenyl] propionate 0.10 parts by weight Parts, 0.35 parts by weight of bis- [N-methyl-2,2,6,6-tetramethyl-4-piperidinyl] sebacate,
2- [2'-hydroxy-3 ', 5'-bis (α, α-
Dimethylbenzyl) phenyl] benzotriazole 0.
35 parts by weight, 0.20 part by weight of melamine, and 0.05 part by weight of calcium stearate were weighed and uniformly mixed using a super mixer [Kawata Manufacturing Co., Ltd.],
A twin-screw extruder [PCM-30, manufactured by Ikegai Tekko,
Screw diameter 30mm], screw rotation speed 5
The mixture was melt-kneaded under the conditions of 0 rpm and a cylinder setting temperature of 220 ° C., and then pelletized. The pellets obtained here were dried for 4 hours using a hot air dryer at a temperature of 80 ° C., and then strip-shaped test pieces were prepared using an injection molding machine (Sumitomo Heavy Industries, Ltd., SG125 type, theoretical injection capacity 163 ml). [For weather (light) resistance test, size 3.2 × 12.7 × 63.6 m
m] was prepared [operating conditions: mold temperature 80 ° C., cylinder set temperature 200 ° C., injection pressure 800 kg / cm ² , molding cycle 40 seconds]. Then, set the cylinder temperature to 23.
Change to 5 ° C and extend for 5 minutes each time 1 shot molding [molding cycle: 5 minutes, 10 minutes, 15 minutes, 20 minutes, ...
.] However, when the retention heat resistance test was performed by repeating the injection molding operation until silver was generated on the surface of the strip-shaped test piece, generation of silver was recognized in 25 minutes of the molding cycle. The strip-shaped test piece obtained here was attached to a predetermined position of a weather meter [manufactured by Suga Test Instruments Co., Ltd., WBL-SUN-HCH type], and the method A (black panel temperature 63 ° C, no rain spray) and method B, respectively. The treatment was carried out under the conditions of [black panel temperature 83 ° C., no rain spray]. In the case of method A, strip-shaped test pieces were taken out of the tester every 100 hours of processing time and observed for cracks and bleed-out. Called time]. Further, in the case of method B, strip-shaped test pieces were taken out of the tester at treatment time intervals of 50 hours and observed for cracks and for bleed-out. It should be noted that the surface of the test piece was evaluated as A without additive bleed-out, as B when slight bleed-out was observed, and as C where bleed-out was observed [see Table 1]. In addition, the pellets obtained here were dried with a hot air dryer at a temperature of 80 ° C.
Dry for 0 hours and 1500 shots molding using a drop mold [Injection molding machine: Sumitomo Heavy Industries, MINIMAT 8/7
A type, clamping force 7tf. Operating conditions: Mold temperature 35 ° C., cylinder set temperature 230 ° C., injection pressure 700 kg / cm ² , molding cycle 10 seconds], and then the mold deposit was observed. Regarding the degree of mold deposits, those that adhered slightly to the contour of the cavity were marked with ◯, and those that adhered completely white around the cavity were marked with * (see Table 1).

Example 2 In Example 1, n-octadecyl-3- [3,5-
Except that the compounding amount of di-t-butyl-4-hydroxyphenyl] propionate was changed from 0.10 part by weight to 0.50 part by weight, the same treatment as in Example 1 was carried out, and the results shown in Table 1 were obtained. Obtained.

Examples 3 to 6 In Example 1, n-octadecyl-3- [3,5-
The compounding amount of di-t-butyl-4-hydroxyphenyl] propionate was changed from 0.10 part by weight to 0.30 part by weight, and bis- [N-methyl-2,2,6,6-tetramethyl was added. In Table 1, 0.35 parts by weight of -4-piperidinyl] sebacate and 0.35 parts by weight of 2- [2'-hydroxy-3 ', 5'-bis (α, α-dimethylbenzyl) phenyl] benzotriazole are shown in Table 1. All were processed in the same manner as in Example 1 except that the respective weight parts shown were changed to
The results shown in Table 1 were obtained.

Example 7 In Example 1, n-octadecyl-3- [3,5-
The amount of di-t-butyl-4-hydroxyphenyl] propionate added was changed from 0.10 part by weight to 0.30 part by weight,
2- [2'-hydroxy-3 ', 5'-bis (α, α-
Dimethylbenzyl) phenyl] benzotriazole 0.
Instead of 35 parts by weight, 2- (2'-hydroxy-3 ',
All were treated in the same manner as in Example 1 except that 0.35 part by weight of 5'-di-t-butylphenyl) benzotriazole was used, and the results shown in Table 1 were obtained.

Comparative Examples 1 to 4 In Example 1, n-octadecyl-3- [3,5-
Table 2 shows the blending amount of di-t-butyl-4-hydroxyphenyl] propionate and the blending amount of other additives.
All were treated in the same manner as in Example 1 except that the changes were made as shown in, and the results shown in Table 2 were obtained.

Comparative Examples 5-10 In Example 1, n-octadecyl-3- [3,5-
Instead of 0.10 part by weight of di-t-butyl-4-hydroxyphenyl] propionate, various hindered phenolic antioxidants shown in Table 3 were used, except that 0.30 part by weight of each was used. Do the same as in Example 1,
The results shown in Table 3 were obtained.

Comparative Examples 11 to 14 In Example 1, n-octadecyl-3- [3,5-
The amount of di-t-butyl-4-hydroxyphenyl] propionate added was changed from 0.10 part by weight to 0.30 part by weight,
Further, in place of 0.35 part by weight of bis- [N-methyl-2,2,6,6-tetramethyl-4-piperidinyl] sebacate, various hindered amine-based light stabilizers of the compounding amounts shown in Table 4 were added. The same treatment as in Example 1 was carried out except that 35 parts by weight was used, and the results shown in Table 4 were obtained.

[0038]

The polyacetal resin composition of the present invention comprises a polyacetal resin and n-octadecyl-3-
[3,5-di-t-butyl-4-hydroxyphenyl]
Propionate (B) and bis- [N-methyl-
2,2,6,6-Tetramethyl-4-piperidinyl] sebacate (C), or an ultraviolet absorber (D)
It is made by adding and blending and evenly melt-kneading, and has extremely excellent moldability and thermal stability, and weather resistance (light).
It is suitable for use as a material for various molded products that have excellent weatherability (light resistance), such as automobile outdoor handles, wheel covers, front fenders, electrical equipment parts, building materials, etc. be able to.

[0039]

[Table 1]

[0040]

[Table 2]

[0041]

[Table 3]

[0042]

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] July 23, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0042

[Correction method] Change

[Correction content]

[0042]

[Table 4]

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical indication location C08K 5/18 5/3435 5/3495 (72) Inventor Kenichi Shimizu 5-6 Higashihachiman, Hiratsuka-shi, Kanagawa No. 2 Sanritsu Gas Chemical Co., Ltd. Plastics Center (72) Inventor Toshiaki Okuzono 5-6-2 Higashihachiman, Hiratsuka City, Kanagawa Sanrishi Gas Chemical Co., Ltd. Plastics Center

Claims (2)

[Claims] 1. An antioxidant n-octadecyl-3- (B) relative to 100 parts by weight of (A) polyacetal resin.
[3,5-di-t-butyl-4-hydroxyphenyl]
0.01 to 0.50 parts by weight of propionate and (C) 0.10 to 1.0 part by weight of light stabilizer bis- [N-methyl-2,2,6,6-tetramethyl-4-piperidinyl] sebacate. (D) Weather resistance (light) resistance obtained by adding and blending 0.10 to 1.0 part by weight of an ultraviolet absorber and uniformly melt-kneading,
And a polyacetal resin composition having improved thermal stability. 2. The ultraviolet absorber is one or more compounds selected from a benzotriazole compound, a benzophenone compound, an aromatic benzoate compound, a cyanoacrylate compound, and an oxalic acid anilide compound. The polyacetal resin composition described.