WO2014119393A1

WO2014119393A1 - Polyacetal resin composition, and sulfur fuel contact provided with molded article of polyacetal resin composition

Info

Publication number: WO2014119393A1
Application number: PCT/JP2014/050835
Authority: WO
Inventors: 暁英霜田; 徳美中田; 晃弘宮崎
Original assignee: ポリプラスチックス株式会社
Priority date: 2013-02-01
Filing date: 2014-01-17
Publication date: 2014-08-07
Also published as: JP2014148626A

Abstract

　Provided is a polyacetal resin composition which, when made into a molded article, can maintain an excellent surface appearance for the molded article and can suppress the occurrence of cracks not just when brought into contact with a low-sulfur fuel but also when brought into contact with a high-sulfur fuel.　The polyacetal resin composition according to the present invention comprises: 100 parts by weight of straight-chain polyacetal resin (A1); 0.1-3.0 parts by weight of a polyacetal copolymer resin (A2) having a branched structure or a cross-linked structure; 0.1-1.0 parts by weight of a hindered phenol oxidation inhibitor (B); 0.1-2.0 parts by weight of a calcium organic acid salt (C); 0.01-0.3 parts by weight of a formaldehyde reactive nitrogen compound (D); and 0.01-0.5 parts by weight of a phosphorus-based antioxidant (E). The polyacetal resin composition according to the present invention can inhibit the number of cracks generated to either "0", "1" or "2" in the figure, even after the molded article has been immersed in a high-sulfur fuel, and thus can suppress the leakage of high-sulfur fuel.

Description

Polyacetal resin composition and sulfur fuel contact body provided with molded article of polyacetal resin composition

The present invention relates to a polyacetal resin composition and a sulfur fuel contact body provided with a molded article of the polyacetal resin composition.

Since polyacetal resin is excellent in chemical resistance, molded products made from polyacetal resin are widely used as automobile parts. For example, it is used as a large component such as a fuel transfer unit represented by a fuel pump module or the like that is in direct contact with fuel oil.

In recent years, in order to comply with the environmental regulations in each country, fuel sulfur has been reduced. However, since desulfurization facilities are very expensive, high sulfur fuel is still in circulation in some countries. These high sulfur fuels tend to deteriorate the polyacetal resin as compared with low sulfur fuels.

By the way, an injection molded product manufactured from polyacetal resin has residual stress inside the molded product due to cooling during injection molding. When high-sulfur fuel or the like comes into contact with this injection molded product, cracks are generated at a portion having a large residual stress, which may cause trouble such as fuel leakage. Therefore, for countries where high sulfur fuel is distributed, it is necessary to use a resin material having high resistance to high sulfur fuel as a raw material.

As a polyacetal resin composition having high acid resistance, (A) 100 parts by weight of a polyacetal resin, (B) 0.1 to 3.0 parts by weight of a hindered phenol antioxidant, and (C) a nitrogen-containing compound A polyacetal resin composition containing 001 to 3.0 parts by weight, (D) 0.1 to 3.0 parts by weight of a fatty acid calcium salt, and (E) a lubricant 0.1 to 3.0 parts by weight is proposed. (See Patent Document 1).

JP 2010-031200 A

However, it is preferable to provide a polyacetal resin composition having higher acid resistance.

The present invention provides a polyacetal resin composition capable of suppressing the occurrence of cracks and maintaining a good molded article surface appearance even when a high sulfur fuel is brought into contact with a low sulfur fuel when formed into a molded article. The purpose is to provide.

As a result of intensive research to solve the above problems, the present inventors have determined that the composition of the polyacetal resin composition is a specific composition, and even if a high-sulfur fuel is brought into contact with the molded product, The inventors have found that the occurrence of this can be suppressed, and have completed the present invention. Specifically, the present invention provides the following.

(1) The present invention comprises (A1) 100 parts by weight of a linear polyacetal resin, (A2) 0.1 to 3.0 parts by weight of a polyacetal copolymer resin having a branched / crosslinked structure, and (B) a hindered 0.1 to 1.0 parts by weight of a phenolic antioxidant, (C) 0.1 to 2.0 parts by weight of a calcium organic acid salt, and (D) 0.01 to 0.3 parts by weight of a formaldehyde-reactive nitrogen compound Part and (E) a phosphorus-based antioxidant 0.01 to 0.5 part by weight of a polyacetal resin composition.

(2) Moreover, this invention is the polyacetal resin composition as described in (1) whose (A1) linear polyacetal resin is a linear polyacetal copolymer resin.

(3) Further, in the present invention, the linear polyacetal copolymer resin may comprise a compound selected from (a) trioxane as a main monomer and (b) a cyclic ether compound having no substituent and a cyclic formal compound. The polyacetal resin composition according to (2), which is a copolymer.

(4) Moreover, the present invention provides the polyacetal according to any one of (1) to (3), wherein (A2) the polyacetal copolymer resin having a branched structure / or a crosslinked structure is a polyacetal copolymer resin having a branched structure. It is a resin composition.

(5) Moreover, the present invention provides the polyacetal copolymer resin having a branched structure, wherein (a) trioxane, (b) a compound selected from a cyclic ether compound having no substituent and a cyclic formal compound, and (c) The polyacetal resin composition according to (4), which is a copolymer with a monofunctional glycidyl compound having a substituent.

(6) Moreover, this invention is a sulfur fuel contact body provided with the molded article of the polyacetal resin composition in any one of (1) to (5).

According to the present invention, when formed into a molded product, not only low sulfur fuel but also high sulfur fuel can be brought into contact with each other to suppress the generation of cracks and maintain a good molded product surface appearance.

It is a figure which shows the evaluation criteria when evaluating the surface state of a test piece, after immersing the test piece which concerns on an Example and a comparative example in a high sulfur fuel.

Hereinafter, specific embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and may be implemented with appropriate modifications within the scope of the object of the present invention. can do.

<Polyacetal resin composition>
The polyacetal resin composition of the present invention comprises (A1) 100 parts by weight of a linear polyacetal resin, (A2) 0.1 to 3.0 parts by weight of a polyacetal copolymer resin having a branched / crosslinked structure, and (B) 0.1 to 1.0 part by weight of a hindered phenolic antioxidant, (C) 0.1 to 2.0 parts by weight of a calcium organic acid salt, and (D) 0.01 to 0. 3 parts by weight and (E) 0.01 to 0.5 parts by weight of a phosphorus-based antioxidant. Hereinafter, (A1) a linear polyacetal resin is also referred to as component (A1), (A2) a polyacetal copolymer resin having a branched structure / or a crosslinked structure is also referred to as component (A2), and (B) a hindered phenol antioxidant. Is also referred to as (B) component, (C) calcium organic acid salt is also referred to as (C) component, (D) formaldehyde-reactive nitrogen compound is also referred to as (D) component, and (E) phosphorus antioxidant (E ) Also called ingredient.

[(A1) linear polyacetal resin]
The (A1) linear polyacetal resin used in the present invention refers to a polymer compound having a linear molecular structure having an oxymethylene group (—CH ₂ O—) as a main structural unit, and is a polyacetal homopolymer. Alternatively, it may be a polyacetal copolymer (including a block copolymer) having a small amount of other structural units in addition to the oxymethylene group. Further, if necessary, two or more kinds of polyacetal resins having different characteristics can be blended and used. However, from the viewpoint of moldability, thermal stability, and the like, the (A1) linear polyacetal resin is preferably a linear polyacetal copolymer.

When the component (A1) is a linear polyacetal copolymer, the linear polyacetal copolymer includes (a) 99.95 to 80.0% by weight of trioxane and (b) a cyclic ether compound having no substituent and a cyclic formal. Those obtained by copolymerizing 0.05 to 20.0% by weight of a compound selected from the above compounds are preferred, and the above (a) 99.9 to 90.0% by weight and (b) 0.1 to 10% are preferred. What is obtained by copolymerizing 0.0 wt% is more preferable.

Examples of the component (b) include ethylene oxide, 1,3-dioxolane, diethylene glycol formal, 1,4-butanediol formal, 1,3-dioxane, propylene oxide and the like, and particularly ethylene oxide, 1,3-dioxolane, Examples thereof include one or more selected from the group consisting of 1,4-butanediol formal and diethylene glycol formal. (A1) The preparation method of a component is not specifically limited, It can prepare by a well-known method.

In the above-described (A1) linear polyacetal resin, particularly linear polyacetal copolymer, the degree of polymerization is not particularly limited, and the degree of polymerization can be adjusted according to the purpose of use and molding means. However, from the viewpoint of achieving both acid resistance and moldability, the melt index (MI) measured at a temperature of 190 ° C. and a load of 2.16 kg is preferably 1 to 50 g / 10 minutes, preferably 5 to 30 g / 10 minutes. More preferably.

[(A2) Polyacetal Copolymer Resin Having Branched Structure / or Crosslinked Structure]
The polyacetal copolymer resin (A2) having a branched structure / or a crosslinked structure used in the present invention refers to a polymer compound having a branch having an oxymethylene group (—CH ₂ O—) as a main structural unit.

When the polyacetal copolymer resin having a branched structure is copolymerized with the component (a) and the component (b), (c) a monofunctional glycidyl compound having a substituent (for example, phenyl glycidyl ether, butyl glycidyl ether, etc.) Is further obtained by copolymerization.

The polyacetal copolymer resin having a crosslinked structure is obtained by further adding (d) a polyfunctional glycidyl ether compound for copolymerization of the component (a) and the component (b).

Examples of the component (b) are the same as those described in the description of the component (A1), but from the viewpoint of fuel stability, particularly ethylene oxide, 1,3-dioxolane, 1,4-butanediol formal. And at least one selected from the group consisting of diethylene glycol formal.

As the component (c), those having 3 to 4 glycidyl ether groups in one molecule are particularly preferable, and specific examples include trimethylolpropane triglycidyl ether, glycerol triglycidyl ether, and pentaerythritol tetraglycidyl ether. It is done.

From the viewpoint of improving mechanical properties, the component (A2) is preferably a polyacetal copolymer resin having a branched structure. The component (A2) comprises 99.89 to 88.0% by weight of the component (a), 0.1 to 10.0% by weight of the component (b), and 0.01 to 2.0 of the component (c). A copolymer containing% by weight is preferred. And (a) 99.28 to 96.50% by weight, (b) component 0.7 to 3.0% by weight, and (c) component 0.02 to 0.5% by weight. More preferably, it is a copolymer.

In the above component (A2), the degree of polymerization and the like are not particularly limited, and the degree of polymerization and the like can be adjusted according to the purpose of use and molding means. Therefore, the melt index (MI) measured at a temperature of 190 ° C. and a load of 2.16 kg is preferably 0.1 to 10 g / 10 minutes, more preferably 0.5 to 3 g / 10 minutes.

(A2) The preparation method of a component is not specifically limited, It can prepare by a well-known method similarly to preparation of (A1) component.

The blending amount of the component (A2) is 0.1 to 3% by weight with respect to 100% by weight of the component (A1). When the blending amount of the component (A2) is small, the improvement of mechanical properties is insufficient, which is not preferable. Moreover, when there are too many compounding quantities of (A2) component, a moldability, an impact physical property, etc. will become inferior, and a mechanical characteristic will also become inadequate as a result.

[(B) hindered phenolic antioxidant]

Examples of the (B) hindered phenol antioxidant used in the present invention include 2,2′-methylenebis (4-methyl-6-t-butylphenol), hexamethylene glycol-bis (3,5-di-t). -Butyl-4-hydroxyhydrocinnamate), tetrakis [methylene (3,5-di-t-butyl-4-hydroxyhydrocinnamate)] methane, triethylene glycol-bis-3- (3-t-butyl- 4-hydroxy-5-methylphenyl) propionate, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxy-benzyl) benzene, n-octadecyl-3 -(4'-hydroxy-3 ', 5'-di-tert-butylphenol) propionate, 4,4'-methylenebis (2,6-di-tert-butyl) Ruphenol), 4,4′-butylidene-bis- (6-tert-butyl-3-methyl-phenol), di-stearyl-3,5-di-tert-butyl-4-hydroxybenzylphosphonate, 2-t -Butyl-6- (3-t-butyl-5-methyl-2-hydroxybenzyl) -4-methylphenyl acrylate, 3,9-bis {2- [3- (3-t-butyl-4-hydroxy- And 5-methylphenyl) propionyloxy] -1,1-dimethylethyl} -2,4,8,10-tetraoxaspiro [5,5] undecane.

In the present invention, at least one or two or more selected from these antioxidants can be used.

In the present invention, the content of the (B) hindered phenol antioxidant is 0.1 to 1.0 part by weight with respect to 100 parts by weight of the component (A1). When the blending amount of the antioxidant (B) is small, not only the antioxidant property which is the original purpose becomes insufficient, but also the fuel resistance which is the object of the present invention is inferior. When the blending amount of (B) antioxidant is excessive, undesirable effects such as mechanical properties and moldability of the resin composition occur.

[(C) Calcium organic acid salt]
The organic acid constituting the (C) calcium organic acid salt used in the present invention is preferably a fatty acid such as a saturated fatty acid or an unsaturated fatty acid. Also, those in which some hydrogen atoms are substituted with a substituent such as a hydroxyl group can be used.

Examples of such fatty acids include monovalent or divalent fatty acids having 10 or more carbon atoms, such as monovalent saturated fatty acids having 10 or more carbon atoms [capric acid, lauric acid, myristic acid, pentadecylic acid, palmitic acid, stearic acid. _C10-34 saturated fatty acids such as arachidic acid, behenic acid, montanic acid, etc.], monovalent unsaturated fatty acids having 10 or more carbon atoms [C such as oleic acid, linoleic acid, linolenic acid, arachidonic acid, erucic acid, etc. _10-34 unsaturated fatty acids, etc.], divalent fatty acids having 10 or more carbon atoms (dibasic fatty acids) [divalent C _10-30 saturated fatty acids such as sebacic acid, dodecanoic acid, tetradecanoic acid, and tapsia acid, And divalent C _10-30 unsaturated fatty acid such as acid and dodecenedioic acid]. The fatty acids also include fatty acids having one or more hydroxyl groups in the molecule (eg, hydroxy saturated C _10-26 fatty acids such as 12-hydroxystearic acid).

In the present invention, the amount of (C) calcium organic acid salt added is 0.1 to 2.0 parts by weight per 100 parts by weight of component (A1). The proportion of the component (C) greatly contributes to the improvement of acid resistance. When the content of the component (C) is less than 0.1 parts by weight, it is not preferable because the intended fuel resistance cannot be obtained. If the content of component (C) exceeds 2.0 parts by weight, the mechanical properties, hue, etc. are impaired, which is not preferable.

[(D) Formaldehyde-reactive nitrogen compound]
Examples of (D) formaldehyde-reactive nitrogen compounds used in the present invention include melamine and derivatives thereof (including guanamine and derivatives thereof), melamine formaldehyde resins, hydrazide compounds, polyamides and polyacrylamides.

First, melamine and its derivatives include melamine (2,4,6-triamino-sym-triazine), melem, melam, melon, N-butylmelamine, N-phenylmelamine, N, N-diphenylmelamine, N, N Diallyl melamine, N, N ″, N ″ -trimethylolmelamine, benzoguanamine (2,4-diamino-6-phenyl-sym-triazine), 2,4-diamino-6-methyl-sym-triazine, 2, , 4-diamino-6-butyl-sym-triazine, 2,4-diamino-6-benzyloxy-sym-triazine, 2,4-diamino-6-butoxy-sym-triazine, 2,4-diamino-6- Cyclohexyl-sym-triazine, 2,4-diamino-6-chloro-sym-triazine, 2,4-diamino 6-mercapto-sym-triazine, 2,4-dioxy-6-mercapto-sym-triazine, 2,4-dioxy-6-amino-sym-triazine (Amelide), 2-oxy-4,6-diamino-sym -Triazine (Ameline), N, N, N ', N'-tetracyanoethylbenzoguanamine and the like are used.

As the melamine formaldehyde resin, a water-insoluble melamine-formaldehyde polycondensate produced from melamine and formaldehyde in a molar ratio of 1: 0.8 to 1: 10.0 is used.

Examples of the hydrazide compound include adipic acid hydrazide and sebacic acid hydrazide.

In the present invention, the content of the (D) formaldehyde reactive nitrogen compound is 0.01 to 0.3 parts by weight with respect to 100 parts by weight of the (A) polyacetal resin. (D) When there are few compounding quantities of a formaldehyde reactive nitrogen compound, the fuel resistance which is the objective of this invention will be inferior. (D) When the compounding amount of the formaldehyde-reactive nitrogen compound is excessive, undesirable effects such as formaldehyde and unreacted nitrogen compound ooze out from the molded product to the surface.

[(E) Phosphorous antioxidant]
Examples of the (E) phosphorus antioxidant used in the present invention include tris (2,4-di-tert-butylphenyl) phosphite, bis (2,6-di-tert-butyl-4-methylphenyl) Examples include pentaerythritol diphosphite.

The content of (E) phosphorus antioxidant in the present invention is 0.01 to 0.5 parts by weight with respect to 100 parts by weight of (A) polyacetal resin. (E) When there are few compounding quantities of phosphorus antioxidant, the fuel resistance which is the objective of this invention will be inferior. (E) When the amount of the phosphorus antioxidant is excessive, undesirable effects such as acceleration of decomposition of the formaldehyde resin and increase of the generated gas occur.

<Sulfur fuel contact body>
The sulfur fuel contact body of the present invention includes a molded article of the polyacetal resin composition. This molded article is obtained by molding the polyacetal resin composition by a conventional molding method such as injection molding, extrusion molding, compression molding, blow molding, vacuum molding, foam molding, or rotational molding. be able to.

The sulfur fuel contact body of the present invention is not limited to low sulfur fuel, and high sulfur fuel may be contacted. Even if the high sulfur fuel is brought into contact, the occurrence of cracks can be suppressed and the good molded article surface appearance can be maintained, so that fuel leakage can be suppressed. In the present specification, “low sulfur fuel” means a fuel having a sulfur concentration of 50 ppm or less, and examples thereof include Japanese JIS No. 2 diesel oil and European EN590 diesel oil. On the other hand, “high sulfur fuel” refers to fuel having a sulfur concentration exceeding 50 ppm, and examples thereof include high sulfur diesel fuel distributed in China, India, and the like.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

(A1) component and (A2) component were prepared by the following method. A paddle was attached using a jacketed continuous mixing reactor having a barrel having a cross-sectional shape in which two circles partially overlap, a rotating shaft with a paddle, and a jacket for passing a heat (cold) medium provided on the outside. Trioxane, 1,3-dioxolane, and trimethylolpropane triglycidyl ether were added in the ratios shown in Table 1 while rotating the two rotating shafts at 150 rpm, respectively, and methylal was continuously supplied as a molecular weight regulator. Bulk polymerization was carried out by continuously adding and feeding boron trifluoride as a catalyst to trioxane. Table 1 also shows the amounts of methylal and boron trifluoride added. While rapidly passing the reaction product discharged from the polymerization machine through a crusher, the reaction product was added to a 60 ° C. aqueous solution containing 0.05 wt% of triethylamine to deactivate the catalyst. Furthermore, after separation, washing and drying, a crude polyacetal resin was obtained.

Next, 3% by weight of a 5% by weight aqueous solution of triethylamine and pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] are added to 100 parts by weight of the crude polyacetal resin. 0.3 wt% was added and melt kneaded at 210 ° C. with a twin-screw extruder to remove unstable parts to obtain a pellet-like polyacetal resin. The melt index (MI) of component (A1) measured at a temperature of 190 ° C. and a load of 2.16 kg was 9 g / 10 min, and the melt index (MI) of component (A2) was 1.5 g / 10 min. .

The various components in Table 2 are as follows.
(A1) Linear polyacetal resin Resin obtained in the above <Preparation of (A1) component and (A2) component> (A2) Polyacetal copolymer resin having a branched structure / or a crosslinked structure Above <(A1) component and (A2) Preparation of Ingredients> Resin (B) hindered phenol antioxidant triethylene glycol-bis [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate] (Product name: Irganox 245 (Made by BASF)
(C) Calcium organic acid salt Calcium stearate (Product name: SAK-CS-G, manufactured by Shinagawa Chemical Industries)
(D) Formaldehyde-reactive nitrogen compound Melamine (Mitsui Chemicals)
(E) Phosphorus antioxidant Tris (2,4-di-tert-butylphenyl) phosphite (Product name: Irgafos 168, manufactured by BASF)

As a comparative component, (C) magnesium stearate (product name: magnesium stearate G, manufactured by NOF Corporation) or zinc oxide (product name: one type of zinc oxide, Mitsui Mining & Smelting Co., Ltd.) instead of calcium organic acid salt Made).

<Examples and Comparative Examples>
(A1) linear polyacetal resin, (A2) branched polyacetal resin, (B) antioxidant, (C) calcium organic acid salt, (D) formaldehyde-reactive nitrogen compound, (E) phosphorus antioxidant Then, magnesium stearate and zinc oxide were added and mixed at a ratio shown in Table 2, and melt-kneaded with a twin-screw extruder to prepare a pellet-shaped composition.

Next, an ASTM No. 4 dumbbell test piece having a thickness of 1 mm was produced by injection molding using the pellet.

<Evaluation>
In order to evaluate the fuel resistance of the polyacetal resin composition, the dumbbell test piece was immersed in a high sulfur fuel, and the subsequent surface condition, tensile strength and tensile elongation were evaluated.

[Surface condition]
The dumbbell test piece was immersed in light oil of 110 ° C. (sulfur content: 300 ppm, acid value: 0.04 mg KOH / g), the test piece was taken out after 500 hours, and the appearance of the surface of the test piece was visually observed. The evaluation criteria were as follows.
If no crack was found: “0”
If there are slight cracks in the vicinity: “1”
When cracks are observed all around: “2”
When cracks are found inside the test piece: “3”
When cracks are observed on the entire surface of the test piece, but the gloss of the test piece remains: "4"
When cracks are observed on the entire surface of the test piece, but no gloss remains on the test piece: “5”

The results are shown in Table 3. FIG. 1 illustrates the evaluation criteria.

[Tensile strength and tensile elongation]
About the test piece after observing the surface state, it was left to stand at 23 ° C. and 50% RH for 48 hours, and a tensile test according to ASTM D638 was performed to measure the tensile strength and the tensile elongation. Tensilon RTM-100 (manufactured by Orientec Co., Ltd.) was used as the tensile tester, and the tensile speed was 50 mm / min. The results are shown in Table 3.

(A1) 100 parts by weight of a linear polyacetal resin, (A2) 0.1 to 3.0 parts by weight of a polyacetal copolymer resin having a branched / crosslinked structure, and (B) a hindered phenol-based antioxidant. 1 to 1.0 parts by weight, (C) calcium organic acid salt 0.1 to 2.0 parts by weight, (D) formaldehyde-reactive nitrogen compound 0.01 to 0.3 parts by weight, and (E) phosphorus It has been confirmed that a resin molded product made from a polyacetal resin composition containing 0.01 to 0.5 parts by weight of an antioxidant is excellent in resistance to high sulfur fuel and can suppress the occurrence of cracks ( Examples 1 to 5). Moreover, since there were few cracks, it was confirmed that it is excellent in tensile strength and tensile strength even after being immersed in high sulfur fuel (same).

On the other hand, when any one of the above components (A2) to (E) is not included, it was confirmed that deterioration started from the surface layer of the test piece due to immersion of the high sulfur fuel and a large number of cracks were generated on the surface (comparison) Examples 1-7). When there were many cracks, good results were not obtained for tensile elongation and tensile strength.

Claims

(A1) 100 parts by weight of a linear polyacetal resin;
(A2) 0.1 to 3.0 parts by weight of a polyacetal copolymer resin having a branched structure / or a crosslinked structure;
(B) 0.1 to 1.0 part by weight of a hindered phenol antioxidant,
(C) 0.1 to 2.0 parts by weight of calcium organic acid salt;
(D) 0.01 to 0.3 parts by weight of a formaldehyde-reactive nitrogen compound;
(E) A polyacetal resin composition containing 0.01 to 0.5 parts by weight of a phosphorus-based antioxidant.
(A1) The polyacetal resin composition according to claim 1, wherein the linear polyacetal resin is a linear polyacetal copolymer resin.
The linear polyacetal copolymer resin is a copolymer having (a) trioxane as a main monomer and (b) a compound selected from a cyclic ether compound having no substituent and a cyclic formal compound as a comonomer. 2. The polyacetal resin composition according to 2.
The polyacetal resin composition according to any one of claims 1 to 3, wherein the polyacetal copolymer resin (A2) having a branched structure / or a crosslinked structure is a polyacetal copolymer resin having a branched structure.
The polyacetal copolymer resin having a branched structure includes (a) trioxane, (b) a compound selected from a cyclic ether compound having no substituent and a cyclic formal compound, and (c) a monofunctional glycidyl compound having a substituent. The polyacetal resin composition of Claim 4 which is a copolymer of these.
A sulfur fuel contact body comprising a molded article of the polyacetal resin composition according to any one of claims 1 to 5.