Polyacetal resin composition, molded article of the same and article

Abstract

To provide a polyacetal resin composition which suppresses lowering of impact resistance by a formaldehyde scavenger, has a small formaldehyde release amount, and scarcely causes mold contamination.SOLUTION: A polyacetal resin composition contains (A) a polyacetal resin, (B) thermoplastic polyurethane, (C) a cyclic urea compound having at least one urea unit-NHCONH- as a ring constituent unit, and (D) a polyamide resin, and with respect to 100 pts.mass of the total of (A) the polyacetal resin and (B) the thermoplastic polyurethane, 50 pts.mass or more and 95 pts.mass or less of (A) the polyacetal resin, 5 pts.mass or more and 50 pts.mass or less of (B) the thermoplastic polyurethane, 0.05 pts.mass or more and 0.2 pts.mass or less of (C) the cyclic urea compound, and 0.1 pts.mass or more and 5.0 pts.mass or less of (D) the polyamide resin.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a polyacetal resin composition, and a molded article and an article thereof. [Background technology]

[0002] Polyacetal resin is a crystalline resin and has excellent rigidity, strength, toughness, sliding properties, and creep properties, and therefore has been widely used as a material for mechanical parts such as automobile parts, electric and electronic parts, and industrial parts. In particular, there is an increasing demand for VOC performance and color characteristics in automobile parts. In addition, with the miniaturization and weight reduction of automobile parts, there is also an increasing demand for improved impact resistance. On the other hand, thermoplastic polyurethane has relatively good compatibility with polyacetal resin and can impart impact resistance to polyacetal resin. For this reason, compositions containing polyacetal resin and thermoplastic polyurethane are often used.

[0003] Known as such a composition is the one disclosed in the following Patent Document 1. Patent Document 1 discloses a polyacetal resin composition comprising 100 parts by mass of a polyacetal resin, 1 to 120 parts by mass of a thermoplastic polyurethane resin, and 0.01 to 5 parts by mass of a formaldehyde scavenger having formaldehyde-reactive nitrogen, in which the thermoplastic polyurethane resin has a residual isocyanate amount of 0.1% by mass or less, a moisture content of 3000 ppm by mass or less, and a melt viscosity of 200,000 poise or more at 180°C. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2013-057044 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, the composition described in Patent Document 1 has room for improvement in terms of the decrease in impact resistance caused by the addition of a formaldehyde scavenger. In polyacetal resins to which a formaldehyde scavenger is added, the addition of the formaldehyde scavenger decomposes the thermoplastic polyurethane resin, resulting in a decrease in impact resistance of the molded product. Another problem is mold contamination, which occurs when formaldehyde scavengers used to suppress formaldehyde released from molded articles accumulate in the mold during continuous molding.

[0006] Therefore, an object of the present invention is to provide a polyacetal resin composition which improves the decrease in impact resistance caused by a formaldehyde scavenger, emits a small amount of formaldehyde, and causes little mold contamination. [Means for solving the problem]

[0007] Means of the Invention The present inventors have conducted intensive research to solve the above-mentioned problems of the conventional technology, and as a result have found that the above-mentioned problems can be solved by the following means, thereby completing the present invention.

[0008] That is, the present invention is as follows.

[0009] [1] A polyacetal resin composition comprising: (A) a polyacetal resin; (B) thermoplastic polyurethane; (C) a cyclic urea compound having at least one urea unit -NHCONH- as a ring-constituting unit; (D) a polyamide resin, With respect to 100 parts by mass in total of the (A) polyacetal resin and the (B) thermoplastic polyurethane, The (A) polyacetal resin is 50 parts by mass or more and 95 parts by mass or less, The (B) thermoplastic polyurethane is 5 parts by mass or more and 50 parts by mass or less, 0.05 parts by mass or more and 0.2 parts by mass or less of the cyclic urea compound (C), and A polyacetal resin composition comprising the (D) polyamide resin in an amount of 0.1 parts by mass or more and 5.0 parts by mass or less. [2] The polyacetal resin composition according to [1], wherein the (C) cyclic urea compound is at least one compound selected from the group consisting of cyclic monoureido (cyclic monoureylene) and cyclic diureido (cyclic diureylene). [3] The polyacetal resin composition according to [1] or [2], wherein the (C) cyclic urea compound does not contain a -CONHNH2 group. [4] The polyacetal resin composition according to any one of [1] to [3], wherein the (C) cyclic urea compound is at least one compound selected from the group consisting of ethylene urea, hydantoin, and allantoin.

[0010] [5] The polyacetal resin composition according to any one of [1] to [4], wherein the (D) polyamide resin is an amorphous polyamide resin or a polyamide resin having a melting point of 180° C. or lower.

[0011] [6] The polyacetal resin composition according to any one of [1] to [5], wherein the (D) polyamide resin is polyamide 6I or a polyamide 6-66-610 copolymer having a melting point of 180° C. or lower.

[0012] [7] The polyacetal resin composition according to [1], wherein the (D) polyamide resin is polyamide 6I.

[0013] [8] The polyacetal resin composition according to any one of [1] to [7], wherein the (A) polyacetal resin has a melt flow rate (MFR) of 15 g / 10 min or less.

[0014] [9] The (D) polyamide resin is a polyamide 6-66-610 copolymer, The polyacetal resin composition according to any one of [1] to [8], wherein the mass ratio of (C) / (D) is in the range of 0.33 or more and 0.60 or less.

[0015]

[10] The (D) polyamide resin is polyamide 6I, The polyacetal resin composition according to any one of [1] to [9], wherein the mass ratio of (C) / (D) is in the range of 0.20 or more and 0.70 or less.

[0016]

[11] A molded article of the polyacetal resin composition according to any one of [1] to

[10] .

[12] An article comprising the molded article according to

[11] , the article being selected from the group consisting of a clip, a wiper, a sun visor, a seat belt, a height adjuster, and a shift knob. Effect of the Invention

[0017] According to the present invention, it is possible to provide a polyacetal resin composition which inhibits the decrease in impact resistance caused by a formaldehyde scavenger, emits a small amount of formaldehyde, and causes little mold contamination. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, an embodiment of the present invention (hereinafter, sometimes referred to as "the present embodiment") will be described in detail. It should be noted that the present invention is not limited to the following embodiment, and can be practiced in various modified forms within the scope of the invention.

[0019] In this specification, two or more embodiments may be combined in any combination.

[0020] The materials, components, compounds, resins, catalysts and solvents described in this specification may each be used alone or in combination of two or more, unless otherwise specified.

[0021] In this specification, (A) polyacetal resin, (B) thermoplastic polyurethane, (C) cyclic urea compound, and (D) polyamide resin may be referred to as component (A), component (B), component (C), and component (D), respectively.

[0022] In this embodiment, the melt flow rate (MFR) value of the (A) polyacetal resin (component (A)) refers to a value measured in accordance with ISO1133.

[0023] In this embodiment, "thermoplastic" means that the material has a reversible property of being meltable by heating at or below its decomposition temperature, exhibiting plastic flow while in a molten state, and solidifying upon cooling. Generally, polyurethane resins begin to decompose at temperatures of 230°C or higher.

[0024] (Polyacetal resin composition) The polyacetal resin composition of the present embodiment is (A) a polyacetal resin; (B) thermoplastic polyurethane; (C) a cyclic urea compound having at least one urea unit -NHCONH- as a ring-constituting unit; (D) a polyamide resin, With respect to 100 parts by mass of the polyacetal resin (A) and the thermoplastic polyurethane (B), The (A) polyacetal resin is 50 parts by mass or more and 95 parts by mass or less, The (B) thermoplastic polyurethane is 5 parts by mass or more and 50 parts by mass or less, 0.05 parts by mass or more and 0.2 parts by mass or less of the cyclic urea compound (C), and The polyacetal resin composition contains the (D) polyamide resin in an amount of 0.1 parts by mass or more and 5.0 parts by mass or less. The polyacetal resin composition improves the decrease in impact resistance caused by the formaldehyde scavenger, emits a small amount of formaldehyde, and causes little mold contamination caused by the formaldehyde scavenger during continuous molding.

[0025] First, components that may be contained in the polyacetal resin composition of the present embodiment will be described.

[0026] <(A) Polyacetal resin (Component A)> The polyacetal resin of this embodiment refers to a polymer having an oxymethylene group in the main chain. Examples of polyacetal resins include polyacetal copolymers obtained by copolymerizing a formaldehyde monomer or its cyclic oligomer with a cyclic ether or cyclic formal; branched polyacetal copolymers obtained by copolymerizing a formaldehyde monomer or its cyclic oligomer with a monofunctional glycidyl ether; and polyacetal copolymers having a crosslinked structure obtained by copolymerizing a formaldehyde monomer or its cyclic oligomer with a polyfunctional glycidyl ether. In addition, for example, polyacetal homopolymers and polyacetal copolymers described in JP 2020-143256 A, and compounds having functional groups such as hydroxyl groups at both ends or one end can also be used.

[0027] When the (A) polyacetal resin ((A) component) in this embodiment is a polyacetal copolymer, the content of the comonomer unit is not particularly limited, and when converted as the content per 1 mol of formaldehyde trimer (trioxane), the content of the comonomer unit is preferably 0.01 mol or more, more preferably 0.02 mol or more, and even more preferably 0.03 mol or more, and is preferably 0.10 mol or less, more preferably 0.07 mol or less, and even more preferably 0.05 mol or less.

[0028] As described above, the polyacetal resin (A) may be either a polyacetal homopolymer or a polyacetal copolymer, but from the viewpoint of thermal stability, the polyacetal copolymer is preferred.

[0029] The melt flow rate (MFR) value of the (A) component may be appropriately adjusted, for example, from 0.1 g / 10 min to 100 g / 10 min. In a preferred embodiment, the (A) component has an MFR value of 0.5 g / 10 min or more, 1.0 g / 10 min or more, 2.0 g / 10 min or more, 2.5 g / 10 min or more, 3.0 g / 10 min or more, 4.0 g / 10 min or more, 5.0 g / 10 min or more, 6.0 g / 10 min or more, 7.0 g / 10 min or more, 8.0 g / 10 min or more, 9.0 g / 10 min or more, or 10.0 g / 10 min or more. In another preferred embodiment, the MFR value of the (A) component is 70 g / 10 min or less, 60 g / 10 min or less, 50 g / 10 min or less, 40 g / 10 min or less, 30 g / 10 min or less, 20 g / 10 min or less, 15.0 g / 10 min or less, 10.0 g / 10 min or less, 9.0 g / 10 min or less, 8.0 g / 10 min or less, 7.0 g / 10 min or less, 6.0 g / 10 min or less, 5.0 g / 10 min or less, or 4.0 g / 10 min or less. By setting the MFR value of the (A) polyacetal resin to 0.1 g / 10 min or more and 100 g / 10 min or less, a polyacetal resin with superior mechanical strength can be obtained. In addition, by setting the MFR value of the (A) polyacetal resin to 1.0 g / 10 min or more and 4.0 g / 10 min or less, a polyacetal resin with even superior mechanical strength can be obtained. The melt flow rate can be measured using MELT INDEXER F-F01 (manufactured by Toyo Seiki Co., Ltd.).

[0030] The content of the (A) component ((A) polyacetal resin) is 50 parts by mass or more and 95 parts by mass or less, based on 100 parts by mass of the total of the (A) component ((A) polyacetal resin) and the (B) component ((B) thermoplastic polyurethane). In a preferred embodiment, the content of the (A) component is preferably 60 parts by mass or more, more preferably 65 parts by mass or more, more preferably 70 parts by mass or more, more preferably 75 parts by mass or more, or more preferably 80 parts by mass or more, based on 100 parts by mass of the total of the (A) component and the (B) component. In another preferred embodiment, the content of the (A) component is preferably 90 parts by mass or less, 85 parts by mass or less, 80 parts by mass or less, 75 parts by mass or less, or 70 parts by mass or less, based on 100 parts by mass of the total of the (A) component and the (B) component. In another preferred embodiment, from the viewpoint of exhibiting excellent rigidity of the engineering resin, the content of the (A) component, relative to 100 parts by mass in total of the (A) component and the (B) component, is 50 parts by mass or more and 95 parts by mass or less, preferably 60 parts by mass or more and 90 parts by mass or less, and more preferably 70 parts by mass or more and 90 parts by mass or less.

[0031] The method for producing the component (A) is not particularly limited and can be a known method. For example, the method described in International Publication No. 2020 / 250895 can be used as the method for producing the component (A).

[0032] <(B) Thermoplastic polyurethane (component (B))> The thermoplastic polyurethane used is a polyurethane having thermoplastic properties, which can be obtained by reacting a diol with a diisocyanate.

[0033] Examples of the diol include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, and 1,4-butanediol.

[0034] Examples of the diisocyanate include aromatic diisocyanates, aliphatic diisocyanates, and alicyclic diisocyanates. These may be used alone or in combination of two or more.

[0035] Examples of the aromatic diisocyanate include 1,4-phenylene diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 2,2-methylene diphenylene diisocyanate, and naphthalene diisocyanate.

[0036] The aliphatic diisocyanate may, for example, be hexamethylene diisocyanate.

[0037] Examples of the alicyclic diisocyanate include isophorone diisocyanate, 4,4'-methylene-bis-(cyclohexyl isocyanate), 1,3-bis-(isocyanatemethyl)cyclohexane, and 1,4-bis-(isocyanatemethyl)cyclohexane.

[0038] The diisocyanate may be, for example, a dimer or trimer of the above-mentioned aromatic diisocyanate, aliphatic diisocyanate, and alicyclic diisocyanate (hereinafter sometimes referred to as "isocyanate compound"), a carbodiimide-modified product of these isocyanate compounds, a prepolymer of these isocyanate compounds and polyhydric alcohol, or a blocked isocyanate compound in which these isocyanate compounds are blocked with a blocking agent such as phenol, primary alcohol, caprolactam, or the like.

[0039] The content of the (B) thermoplastic polyurethane ((B) component) is 5 parts by mass or more and 50 parts by mass or less relative to 100 parts by mass of the total of the (A) component ((A) polyacetal resin) and the (B) component ((B) thermoplastic polyurethane). From the viewpoint of improving impact resistance, the content of the (B) thermoplastic polyurethane ((B) component) is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, and more preferably 20 parts by mass or more relative to 100 parts by mass of the total of the (A) component and the (B) component. In addition, the content of the (B) thermoplastic polyurethane ((B) component) is preferably 45 parts by mass or less, may be 40 parts by mass or less, may be 35 parts by mass or less, or may be 30 parts by mass or less.

[0040] <(C) Cyclic urea compounds> The polyacetal resin composition of the present embodiment contains a cyclic urea compound (C) from the viewpoint of capturing formaldehyde. By containing the cyclic urea compound (C), the decrease in impact resistance can be improved, and the polyacetal resin composition has less mold contamination. Here, the term "cyclic urea compound" refers to a compound having at least one urea unit -NHCONH- as a constituent unit of a ring. Each H bonded to the N atom in the urea unit is unsubstituted.

[0041] The cyclic urea compound may be at least one compound selected from the group consisting of cyclic monoureido (cyclic monoureylene) and cyclic diureido (cyclic diureylene). The cyclic monoureido (cyclic monoureylene) refers to a compound having one ureylene group (urea unit -NHCONH-) as a ring constituent unit, and the cyclic diureido (cyclic diureylene) refers to a compound having two ureylene groups (urea unit -NHCONH-) as ring constituent units. In one embodiment, the cyclic urea compound is a cyclic monoureido (cyclic monoureylene). The cyclic urea compound is preferably a cyclic monoureido compound, and from the viewpoint of capturing formaldehyde, is particularly preferably at least one compound selected from the group consisting of ethylene urea (also called 2-imidazolidinone), hydantoin, and allantoin. From the viewpoint of mold contamination, the cyclic monoureide (cyclic monoureylene) is more preferably ethyleneurea or hydantoin. When the cyclic urea compound is ethylene urea, the change in impact resistance over time can be suppressed. In addition, the cyclic urea compound preferably does not have a -CONHNH2 group.

[0042] The content of the (C) component is 0.05 parts by mass or more and 0.20 parts by mass or less, based on 100 parts by mass of the total of the (A) component and the (B) component. In a preferred embodiment, the content of the (C) component is preferably 0.06 parts by mass or more, preferably 0.07 parts by mass or more, preferably 0.075 parts by mass or more, preferably 0.08 parts by mass or more, preferably 0.10 parts by mass or more, preferably 0.12 parts by mass or more, and preferably 0.15 parts by mass or more, based on 100 parts by mass of the total of the (A) component and the (B) component. In another preferred embodiment, the content of the (C) component is preferably 0.18 parts by mass or less, preferably 0.16 parts by mass or less, preferably 0.15 parts by mass or less, preferably 0.12 parts by mass or less, and preferably 0.10 parts by mass or less, based on 100 parts by mass of the total of the (A) component and the (B) component. In another preferred embodiment, the content of the component (C) is preferably 0.10 parts by mass or more and 0.15 parts by mass or less relative to 100 parts by mass of the combined total of the components (A) and (B).

[0043] <(D) Polyamide resin (component (D))> The (D) polyamide resin (component (D)) is not particularly limited, and known polyamide resins can be used. Polyamide resin is a general term for polymers having an amide bond in the main chain. Polyamide resins are basically obtained by various reactions such as polycondensation of dibasic acid and diamine, polycondensation of aminocarboxylic acid, or ring-opening polymerization of lactam. The (D) component may be composed of one type of structural unit or two or more types of structural units. In the case of copolymerized polyamide resins, the ratio of structural units, copolymerization form (for example, random copolymer, block copolymer, crosslinked polymer), etc. can be selected arbitrarily.

[0044] Specific examples of polyamide resins include polycaproamide (polyamide 6), polytetramethylene adipamide (polyamide 46), polyhexamethylene adipamide (polyamide 66), polyhexamethylene sebacamide (polyamide 610), polyhexamethylene dodecamide (polyamide 612), polyundecane amide (polyamide 11), polydodecanamide (polyamide 12), polytrimethylhexamethylene terephthalamide (polyamide TMHT), polyhexamethylene terephthalamide (polyamide 6T), polyhexamethylene isophthalamide (polyamide 6I), polybis(4-aminocyclohexyl)methandodecamide (polyamide PACM12), polybis(3-methyl-4-aminocyclohexyl)methandodecamide (polyamide dimethyl PACM12), polymetaxylyleneadipamide (polyamide MXD6), polynonamethylene terephthalamide (polyamide 9T), polydecamethylene terephthalamide (polyamide 10T), polyundecamethylene terephthalamide (polyamide 11T), polyundecamethylene hexahydroterephthalamide (polyamide 11T(H)), dimer acid polyamide, etc. The polyamide resin may be a copolymer or a mixture of these polyamides, such as polyamide 6-66-610 copolymer, polyamide 6T / 6I.

[0045] A high ratio of amide bonds in component (D) leads to good compatibility with component (C), and the effect of suppressing the release of formaldehyde gas and the effect of suppressing the deterioration of physical properties are more pronounced.

[0046] When the concentration of amide bonds contained in the polyamide resin (D) of this embodiment is high, the compatibility with the ethylene urea (C) is good, and the effect of suppressing the release of formaldehyde gas and the effect of suppressing the deterioration of physical properties are more significantly improved.

[0047] The polyamide resin (D) of this embodiment is preferably an amorphous polyamide resin or a crystalline polyamide resin having a melting point of 180° C. or less. More preferably, it is a crystalline polyamide resin having a melting point of 180° C. or less. By using such a polyamide resin, the amount of formaldehyde gas released can be further suppressed. The melting point of the crystalline polyamide resin is, for example, 160° C. or more, 165° C. or more, 170° C. or more, or 175° C. or more.

[0048] Amorphous polyamide resins are those that do not show a clear melting peak when heated at 10°C / min in a differential scanning calorimeter (DSC) analysis according to JIS K7121, specifically, those that do not show a melting peak of 4 cal / g or more. The melting point of crystalline polyamide resins is the melting peak temperature according to JIS K7121 when the resin is kept at a temperature 30°C higher than the end of the melting peak for 10 minutes, cooled at 10°C / min, and then heated at 10°C / min. As the amorphous polyamide resin or the crystalline polyamide resin having a melting point of 180° C. or less in this embodiment, polyamide 6I or a polyamide 6-66-610 copolymer having a melting point of 180° C. or less is particularly preferred.

[0049] The polyamide resin (D) of this embodiment is, for example, preferably at least one of polyamide 6, polyamide 610, polyamide 612, polyamide 11, polyamide 12, polyamide TMHT, polyamide 6I, polyamide PACM12, polyamide dimethyl PACM12, polyamide MXD6, polyamide 6-66 copolymer, polyamide 6-66-610 copolymer, and polyamide 6T / 6I copolymer, more preferably at least one of polyamide TMHT, polyamide 6I, polyamide 6-66 copolymer, and polyamide 6-66-610 copolymer, and particularly preferably polyamide 6I or polyamide 6-66-610 copolymer.

[0050] The content of the (D) polyamide resin in this embodiment is 0.1 parts by mass or more, preferably 0.2 parts by mass or more, and more preferably 0.3 parts by mass or more, per 100 parts by mass of the polyacetal resin and the thermoplastic polyurethane in total. In another preferred embodiment, the content of the (D) component is 5.0 parts by mass or less, preferably 1.0 parts by mass or less, more preferably 0.6 parts by mass or less, and even more preferably 0.5 parts by mass or less, per 100 parts by mass of the (A) component and the (B) component in total. In another preferred embodiment, the content of the (D) component is 0.3 parts by mass or more and 0.5 parts by mass or less, per 100 parts by mass of the (A) component and the (B) component in total.

[0051] In the resin composition of this embodiment, the preferred mass ratio of the (C) cyclic urea compound to the (D) polyamide resin, i.e., the mass ratio of the (C) cyclic urea compound / (D) polyamide resin ((C) / (D)), is preferably 0.05 or more, more preferably 0.10 or more, even more preferably 0.20 or more, even more preferably 0.30 or more, and most preferably 0.32 or more. Meanwhile, the mass ratio of the (C) cyclic urea compound / (D) polyamide resin is preferably 2.0 or less, more preferably 1.5 or less, even more preferably 1.0 or less, even more preferably 0.70 or less, and most preferably 0.6 or less. The preferred mass ratio of (C) cyclic urea compound / (D) polyamide resin also varies depending on the type of (D) polyamide resin used. When a polyamide 6-66-610 copolymer is used as the (D) polyamide resin, the mass ratio is preferably 0.33 to 0.60, more preferably 0.33 to 0.55, and even more preferably 0.40 to 0.50. When polyamide 6I is used as the (D) polyamide resin, the mass ratio is preferably 0.20 to 0.70, more preferably 0.25 to 0.60, and even more preferably 0.30 to 0.50.

[0052] <(E) Other Ingredients ((E) Ingredients)> The polyacetal resin composition may further contain, in addition to the components (A) to (D), other components, for example, (E) other components (component (E)) such as known additives, such as a formaldehyde scavenger other than (C) a cyclic urea compound, an antioxidant, a formic acid scavenger, a weather resistance stabilizer, a release agent, a lubricant, a conductive agent, a dye or pigment, or an inorganic filler or an organic filler.

[0053] The content of (E) other components may be adjusted as appropriate. For example, it is preferably 50 parts by mass or less, preferably 30 parts by mass or less, preferably 10 parts by mass or less, preferably 5 parts by mass or less, or preferably 1 part by mass or less, relative to 100 parts by mass of the combined total of the (A) component and the (B) component.

[0054] As the formaldehyde scavenger other than the (C) cyclic urea compound, a basic nitrogen compound other than the (C) cyclic urea compound can be used. As the basic nitrogen compound other than the (C) cyclic urea compound, for example, the aminotriazine compound, guanidine compound, amino acid compound, amino alcohol compound, imide compound, and amide compound described in JP-A-2005-163019 can be mentioned. In one embodiment, the polyacetal resin composition does not contain a formaldehyde scavenger other than the (C) cyclic urea compound.

[0055] (Method for producing polyacetal resin composition) The polyacetal resin composition is not particularly limited, and can be produced, for example, by kneading the (A) component, the (B) component, the (C) component, and the (D) component, and, if necessary, other components.

[0056] The kneader is not particularly limited, and a known kneader can be used. For example, the kneader described in WO2020 / 250895 can be mentioned.

[0057] Kneading using an extruder equipped with a vent pressure reducing device is preferred from the viewpoints of thermal stability and productivity. In addition, a single-screw or twin-screw extruder is preferably used for mass-production of a polyacetal resin composition. When a single-screw or twin-screw extruder is used, a pelletized polyacetal resin composition (hereinafter sometimes referred to as "polyacetal resin pellets") can be obtained.

[0058] Alternatively, each component may be continuously fed into the extruder either individually or in batches of several components using a quantitative feeder or the like, without premixing.

[0059] Alternatively, a high-concentration master batch consisting of each component may be prepared in advance, and then diluted with the polyacetal resin during extrusion melt kneading.

[0060] The kneading temperature may be in accordance with the preferred processing temperature of the polyacetal resin used, and is generally in the range of 140 to 260°C, preferably 160 to 230°C.

[0061] (Molded article of polyacetal resin composition) The polyacetal resin composition of the present embodiment can be molded and used as a molded article.

[0062] The molding method of the polyacetal resin composition is not particularly limited, and a known molding method of the polyacetal resin composition can be used. For example, a molding method such as injection molding described in WO2020 / 250895 can be mentioned.

[0063] The molded article of the present embodiment is preferably a molded article made using the polyacetal resin composition of the present embodiment.

[0064] <Applications of molded products> The molded product of the present embodiment has excellent quality stability and can be used in various applications, such as mechanical parts (e.g., gears, cams, sliders, levers, shafts, bearings, and guides), resin parts for outsert molding, resin parts for insert molding (chassis, trays, side plate parts), printer parts, copier parts, digital camera parts, digital video equipment parts, music equipment parts, video equipment parts, information equipment parts, communication equipment parts, electrical equipment parts, and electronic equipment parts.

[0065] The molded product of the present embodiment is also suitable for use as automobile parts, such as interior parts, door surrounding parts, seat belt peripheral parts, combination switch parts, and switches. Examples of interior parts, door surrounding parts, seat belt peripheral parts, combination switch parts, and switches include inner handles, fuel trunk openers, seat belt buckles, assist wraps, various switches, knobs, levers, clips, etc. Furthermore, the molded product of the present embodiment can also be used suitably as industrial parts, such as housing equipment.

[0066] The article of this embodiment preferably includes the molded article of this embodiment.

[0067] In one embodiment, the article of the present embodiment preferably includes the molded article of the present embodiment, and the article is preferably selected from a clip, a wiper, a sun visor, a seat belt, a height adjuster, and a shift knob. EXAMPLES

[0068] Hereinafter, the present embodiment will be described with reference to examples and comparative examples, but the present embodiment is not limited to the following examples.

[0069] The measurement and evaluation methods used in the examples and comparative examples are shown below. <Evaluation of mechanical properties (impact resistance)> Using a Toshiba Machine Co., Ltd. EC100SX, test pieces were prepared with a cylinder temperature of 205°C, an injection time of 35 seconds, a cooling time of 15 seconds, and a mold temperature of 80°C to mold ISO dumbbell test pieces for evaluating physical properties. The test pieces were then subjected to the following tests. Charpy impact strength: evaluated on the day after molding and 30 days later based on ISO179 / 1eA. The evaluation results are shown in Tables 1 to 4 below. The Charpy impact strength of each Example and Comparative Example was evaluated as a Charpy impact improvement rate relative to the Charpy impact strength of Reference Examples (Reference Examples 1 to 11) having the same ratio of components (A) and (B). The Charpy impact improvement rate is preferably improved by 10% or more, and more preferably improved by 15% or more, compared to the Reference Example samples having the same ratio of components (A) and (B).

[0070] <Evaluation of formaldehyde gas emissions from molded products> [Creating flat test specimens] Using a Toshiba Machine IS-100GN injection molding machine, test pieces were prepared with a cylinder temperature of 200°C, an injection time of 15 seconds, a cooling time of 20 seconds, and a mold temperature of 77°C. Measurements were then conducted using the VDA275 method (conditions below) to determine the amount of formaldehyde released from the molded product.

[0071] [VDA275 Law] The amount of formaldehyde generated from the test piece was measured according to VDA275 as follows. First, 50 mL of distilled water and the prepared test piece were placed in a polyethylene container and sealed. Next, the polyethylene container was heated at 60°C for 3 hours, and the formaldehyde generated in the distilled water was reacted with acetylacetone in the presence of ammonium ions. The absorption peak at a wavelength of 412 nm was measured using a UV spectrometer for the obtained reaction product, and the amount of formaldehyde generated per 1 kg of the test piece (mg / kg) was determined. The smaller the value of the formaldehyde release amount, the more preferable. The value of the formaldehyde release amount is preferably 2.0 mg / kg or less, and more preferably 1.5 mg / kg or less.

[0072] <Mold Contamination> Using a mold made by Toyo Machine Metal Co., Ltd. with the product name "Si-30V", the mold surface mold deposit after 1000 consecutive shots of a 30 mm × 12 mm × 2 mm ribbed mold was confirmed under the conditions of a mold setting temperature of 60°C, a cylinder temperature of 200°C, an injection pressure of 34 MPa, an injection time of 20 seconds, and a cooling time of 15 seconds. The presence or absence of mold deposit was observed from the vertical direction with respect to the surface on the fixed side of the mold and evaluated according to the following evaluation criteria. Evaluation A is considered qualified, while evaluations B and C are unqualified. A: No mold deposit is observed at all. B: A colorless mold deposit is observed. C: An interference color (interference fringes) presumed to be a mold deposit with a thickness of about 200 nm or more is generated.

[0073] 〔Raw Material Components〕 The raw material components used in the examples and comparative examples are shown below.

[0074] <(A) Polyacetal Resin> (A1) Polyacetal copolymer (MFR: 2.5 g / 10 min): (Product name: TENAC-C 3510, manufactured by Asahi Kasei) (A2) Polyacetal copolymer (MFR: 9.0 g / 10 min): (Product name: TENAC-C 4520, manufactured by Asahi Kasei) (A3) Polyacetal homopolymer (MFR: 5.0 g / 10 min): (Obtained by anionic polymerization of formaldehyde in the presence of a catalyst)

[0075] <(B) Polyurethane Resin> (B1) Polyurethane elastomer (Product name: WHT-1180K, manufactured by Wanhua Chemical Group Co., Ltd.) (B2) Polyurethane elastomer (Product name: WHT-1185F, manufactured by Wanhua Chemical Group Co., Ltd.)

[0076] <Component C> (C-1) Hydantoin (manufactured by Tokyo Chemical Industry Co., Ltd.) (C-2) Allantoin (manufactured by Tokyo Chemical Industry Co., Ltd.) (C-3) Ethylene urea (manufactured by Tokyo Chemical Industry Co., Ltd.)

[0077] <(D) Polyamide resin> (D-1) Polyamide 6-66-610 (melting point 175°C): Obtained by copolymerizing ε-caprolactam, adipic acid, and hexamethylenediamine. Equivalent to a crystalline polyamide resin with a melting point of 180°C or less. (D-2) Polyamide 6I (number average molecular weight Mn = 9.760) (amorphous): Obtained by copolymerizing isophthalic acid and hexamethylenediamine. Equivalent to an amorphous polyamide resin.

[0078] <Other ingredients> (E-1) Benzoguanamine (Tokyo Chemical Industry Co., Ltd.) (E-2) Adipic dihydrazide (Tokyo Chemical Industry Co., Ltd.) (E-3) Dodecanedioic acid dihydrazide (Tokyo Chemical Industry Co., Ltd.) (E-4) 4-(1-methylethyl)-2,5-dioxo-1,3-imidazolidinedipropanoic acid dihydrazide, Amicure VDH (manufactured by Ajinomoto Fine-Techno) The above (E-1) to (E-4) are formaldehyde scavengers other than the (C) cyclic urea compounds.

[0079] (Production of polyacetal resin composition and molded products thereof) According to the formulations shown in Tables 1 to 4, a twin-screw extruder (TEM-26SS extruder (L / D48, vented) manufactured by Toshiba Machine Co., Ltd.) was used. The cylinder temperatures were all set to 200°C, and components (A) to (E) were fed from a fixed amount feeder into the main throat of the extruder. The resin mixture was extruded into a strand shape at an extrusion rate of 20 kg / hour and a screw rotation speed of 200 rpm. The extrusion was quenched in a strand bath and cut with a strand cutter to obtain pellets of the resin composition of each Example, Reference Example, and Comparative Example. Using each of the obtained resin compositions, molded articles of each Example, Reference Example, and Comparative Example were produced according to the measurement and evaluation methods described above, and the physical properties were evaluated.

[0080] The blend amounts, evaluation results, etc. are shown in Tables 1 to 4.

[0081] [Table 1]

[0082] [Table 2] [Table 3] [Table 4]

[0083] As shown in the table, the polyacetal resin compositions obtained in the Examples have improved Charpy impact strength compared to the Reference Examples, and are polyacetal resin compositions that emit less formaldehyde and cause less mold contamination. [Industrial Applicability]

[0084] According to the present invention, it is possible to provide a polyacetal resin composition which inhibits the decrease in impact resistance caused by a formaldehyde scavenger, emits a small amount of formaldehyde, and causes little mold contamination.

[0085] One aspect of the present invention is as follows. [1] A polyacetal resin composition comprising: (A) a polyacetal resin; (B) thermoplastic polyurethane; (C) a cyclic urea compound; (D) a polyamide resin, With respect to 100 parts by mass in total of the (A) polyacetal resin and the (B) thermoplastic polyurethane, The (A) polyacetal resin is 50 parts by mass or more and 95 parts by mass or less, The (B) thermoplastic polyurethane is 5 parts by mass or more and 50 parts by mass or less, 0.05 parts by mass or more and 0.2 parts by mass or less of the cyclic urea compound (C), and A polyacetal resin composition comprising the (D) polyamide resin in an amount of 0.1 part by mass or more and 1.0 part by mass or less. [2] The polyacetal resin composition according to [1], wherein the (D) polyamide resin is an amorphous polyamide or a polyamide having a melting point of 180°C or lower. [3] The polyacetal resin composition according to [1] or [2], wherein the (D) polyamide resin is polyamide 6I or a polyamide 6-66-610 copolymer having a melting point of 180°C or lower. [4] The polyacetal resin composition according to any one of [1] to [3], wherein the (D) polyamide resin is polyamide 6I. [5] The polyacetal resin composition according to any one of [1] to [4], wherein the (A) polyacetal resin has a melt flow rate (MFR) of 4 g / 10 min or less. [6] The (D) polyamide resin is a polyamide 6-66-610 copolymer, The polyacetal resin composition according to any one of [1] to [5], wherein the mass ratio of (C) / (D) is in the range of 0.33 or more and 0.60 or less. [7] The (D) polyamide resin is polyamide 6I, The polyacetal resin composition according to any one of [1] to [6], wherein the mass ratio of (C) / (D) is in the range of 0.20 or more and 0.70 or less. [8] A molded article made from the polyacetal resin composition according to any one of [1] to [7].

Claims

1. A polyacetal resin composition comprising: (A) a polyacetal resin; (B) a thermoplastic polyurethane; and (C) a cyclic urea compound having at least one urea unit -NHCONH- as a ring-constituting unit; (D) a polyamide resin, For a total of 100 parts by mass of the (A) polyacetal resin and the (B) thermoplastic polyurethane, The polyacetal resin (A) is 50 parts by mass or more and 95 parts by mass or less, The (B) thermoplastic polyurethane is 5 parts by mass or more and 50 parts by mass or less, 0.05 parts by mass or more and 0.2 parts by mass or less of the cyclic urea compound (C), and A polyacetal resin composition comprising the (D) polyamide resin in an amount of 0.1 parts by mass or more and 5.0 parts by mass or less.

2. The polyacetal resin composition according to claim 1, wherein the cyclic urea compound (C) is at least one compound selected from the group consisting of cyclic monoureido compounds and cyclic diureido compounds.

3. The (C) cyclic urea compound is -CONHNH ２ The polyacetal resin composition according to claim 1 , which does not contain any group.

4. 2. The polyacetal resin composition according to claim 1, wherein the cyclic urea compound (C) is at least one compound selected from the group consisting of ethylene urea, hydantoin, and allantoin.

5. 2. The polyacetal resin composition according to claim 1, wherein the (D) polyamide resin is an amorphous polyamide resin or a polyamide resin having a melting point of 180° C. or lower.

6. 2. The polyacetal resin composition according to claim 1, wherein the polyamide resin (D) is polyamide 6I or a polyamide 6-66-610 copolymer having a melting point of 180° C. or lower.

7. The polyacetal resin composition according to claim 1, wherein the polyamide resin (D) is polyamide 6I.

8. The polyacetal resin composition according to claim 1, wherein the polyacetal resin (A) has a melt flow rate (MFR) of 15 g / 10 min or less.

9. the (D) polyamide resin is a polyamide 6-66-610 copolymer, The polyacetal resin composition according to claim 1 , wherein the mass ratio of (C) / (D) is in the range of 0.33 or more and 0.60 or less.

10. The (D) polyamide resin is polyamide 6I, The polyacetal resin composition according to claim 1 , wherein the mass ratio of (C) / (D) is in the range of 0.20 or more and 0.70 or less.

11. A molded article made from the polyacetal resin composition according to any one of claims 1 to 10.

12. 12. An article comprising the molded article according to claim 11, wherein the article is selected from the group consisting of a clip, a wiper, a sun visor, a seat belt, a height adjuster, and a shift knob.

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