Resin composition, pellet, and molded article

Abstract

To provide a resin composition with excellent softness and low mold release resistance during molding, and a pellet and a molded article.SOLUTION: The resin composition comprises a polyacetal resin, a core-shell polymer, and a polyalkylene glycol, wherein the number average molecular weight of the polyalkylene glycol is 200 to 30,000, and a value obtained by multiplying the number average molecular weight of the polyalkylene glycol by its content in the resin composition (unit: mass%) is 1,000 to 17,000.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a resin composition, a pellet, and a molded article, and in particular to a resin composition containing a polyacetal resin as a main component. [Background technology]

[0002] Polyacetal resin is a plastic having excellent mechanical properties, electrical properties, and chemical properties such as chemical resistance, and is used in a wide range of applications. In order to impart flexibility to polyacetal resin, it has been considered to blend an elastomer therein. For example, Patent Document 1 describes a resin composition containing a polyacetal resin and a core-shell polymer, the resin composition being molded into a 4 mm thick multipurpose test piece, which has a flexural modulus of 1700 MPa or less when measured according to ISO178, and the resin composition being molded into a 1.6 mm thick test piece having a weld in the center, which has a weld elongation of 20% or more when stretched at 10 mm / min according to ASTM D638. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-011562 Summary of the Invention [Problem to be solved by the invention]

[0004] A molded article obtained from the resin composition containing the polyacetal resin and the core-shell polymer described in the above Patent Document 1 has excellent flexibility. However, when a core-shell polymer is blended with a polyacetal resin, the mold release resistance during molding tends to increase. The present invention has an object to solve the above-mentioned problems, and to provide a resin composition having excellent flexibility and low mold release resistance during molding, as well as pellets and molded articles. [Means for solving the problem]

[0005] In view of the above problems, the present inventors have conducted research and found that the above problems can be solved by blending a polyalkylene glycol that satisfies certain conditions into a resin composition containing a polyacetal resin and a core-shell polymer. Specifically, the above problems were solved by the following means. <1> A resin composition comprising a polyacetal resin, a core-shell polymer, and a polyalkylene glycol, wherein the polyalkylene glycol has a number average molecular weight of 200 to 30,000, and a value obtained by multiplying the number average molecular weight of the polyalkylene glycol by its content (unit: mass %) in the resin composition is 1,000 to 17,000. <2> The polyalkylene glycol comprises polyethylene glycol. <1> The resin composition according to claim 1. <3> The core-shell polymer is contained in an amount of 5 to 50 parts by mass relative to 100 parts by mass of the polyacetal resin. <1> or <2> The resin composition according to claim 1. <4> The polyalkylene glycol is contained in an amount of 0.3 to 10 parts by mass relative to 100 parts by mass of the polyacetal resin. <1> ~ <3> 10. The resin composition according to claim 9 . <5> Further, the composition contains 0.01 to 0.4 parts by mass of a formaldehyde scavenger relative to 100 parts by mass of the polyacetal resin. <1> ~ <4> 10. The resin composition according to claim 9 . <6> Further, the composition contains 0.01 to 3 parts by mass of a hindered phenol-based antioxidant relative to 100 parts by mass of the polyacetal resin. <1> ~ <5> 10. The resin composition according to claim 9 . <7> Further, paraffin wax is included. <1> ~ <6> 10. The resin composition according to claim 9 . <8> the polyalkylene glycol comprises polyethylene glycol, The core-shell polymer is contained in an amount of 5 to 50 parts by mass relative to 100 parts by mass of polyacetal resin, The polyalkylene glycol is contained in an amount of 0.3 to 10 parts by mass relative to 100 parts by mass of the polyacetal resin, Further, the composition contains 0.01 to 0.4 parts by mass of a formaldehyde scavenger relative to 100 parts by mass of the polyacetal resin, Further, the composition contains 0.01 to 3 parts by mass of a hindered phenol-based antioxidant relative to 100 parts by mass of the polyacetal resin. <1> ~ <7> 10. The resin composition according to claim 9 . <9> Further, paraffin wax is included. <8> The resin composition according to claim 1. <10> <1> ~ <9> A pellet formed from the resin composition according to any one of claims 1 to 5. <11> <1> ~ <9> 2. A molded article formed from the resin composition according to claim 1. <12> <10> A molded article formed from the pellets according to claim 1. Effect of the Invention

[0006] According to the present invention, it is possible to provide a resin composition having excellent flexibility and low mold release resistance during molding, as well as pellets and molded articles. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] Hereinafter, an embodiment of the present invention (hereinafter, simply referred to as "the present embodiment") will be described in detail. Note that the present embodiment is an example for explaining the present invention, and the present invention is not limited to the present embodiment. In this specification, the use of "to" means that the numerical values ​​before and after it are included as the lower limit and upper limit. In this specification, various physical properties and characteristic values ​​are those at 23° C. unless otherwise specified. If the measurement methods, etc. described in the standards shown in this specification vary from year to year, they will be based on the standards as of January 1, 2023, unless otherwise stated.

[0008] The resin composition of the present embodiment is characterized in that it contains a polyacetal resin, a core-shell polymer, and a polyalkylene glycol, the number average molecular weight of the polyalkylene glycol being 200 to 30,000, and the value obtained by multiplying the number average molecular weight of the polyalkylene glycol by its content (unit: mass%) in the resin composition being 1,000 to 17,000.By adopting such a constitution, it is possible to provide a resin composition, pellets, and molded products that are excellent in flexibility and weld characteristics and have small mold release resistance during molding.

[0009] By blending a core-shell type elastomer into the polyacetal resin, softness can be achieved and the weld property can be improved. Here, polyalkylene glycol is blended to improve the mold release resistance without reducing the softness and weld property. However, if the molecular weight of the polyalkylene glycol is large, the dispersion diameter of the polyalkylene glycol dispersed in the polyacetal resin becomes large. In this case, when pulled, the polyalkylene glycol with a large dispersion diameter becomes the starting point of breakage. On the other hand, if the molecular weight of the polyalkylene glycol is small, the dispersion diameter of the polyalkylene glycol dispersed in the polyacetal resin can be small, and it is difficult to become the starting point of breakage when pulled. However, if the blending amount of the polyalkylene glycol is large, the number of dispersions that can become the starting point of breakage increases. In this embodiment, polyalkylene glycol with a number average molecular weight of 200 to 30,000 is used, and the value obtained by multiplying the number average molecular weight of polyalkylene glycol by the content (unit: mass%) in the resin composition is set to 1,000 to 17,000, so that the proportion of polyalkylene glycol with a large dispersion diameter is relatively small, and the amount of polyalkylene glycol dispersion is adjusted so that the number of polyalkylene glycol dispersions is not more than necessary, thereby presumably maintaining softness and reducing the release resistance. Furthermore, weld strength and weld elongation can be maintained at high levels.

[0010] <Polyacetal resin> The resin composition of the present embodiment contains a polyacetal resin. The polyacetal resin is not particularly limited, and may be a homopolymer containing only divalent oxymethylene groups as constituent units, or a copolymer containing divalent oxymethylene groups and divalent oxyalkylene groups having 2 to 6 carbon atoms as constituent units.

[0011] Examples of the oxyalkylene group having 2 to 6 carbon atoms include an oxyethylene group, an oxypropylene group, and an oxybutylene group.

[0012] In the polyacetal resin, the proportion of oxyalkylene groups having 2 to 6 carbon atoms in the total number of moles of oxymethylene groups and oxyalkylene groups having 2 to 6 carbon atoms is not particularly limited, and may be 0.5 to 10 mol %.

[0013] To produce the polyacetal resin, trioxane is usually used as a main raw material. To introduce an oxyalkylene group having 2 to 6 carbon atoms into the polyacetal resin, a cyclic formal or a cyclic ether can be used. Specific examples of the cyclic formal include 1,3-dioxolane, 1,3-dioxane, 1,3-dioxepane, 1,3-dioxocane, 1,3,5-trioxepane, and 1,3,6-trioxocane, and specific examples of the cyclic ether include ethylene oxide, propylene oxide, and butylene oxide. To introduce an oxyethylene group into the polyacetal resin, 1,3-dioxolane can be used as a main raw material. To introduce an oxypropylene group, 1,3-dioxane can be used as a main raw material. To introduce an oxybutylene group, 1,3-dioxepane can be used as a main raw material. In addition, in polyacetal resins, it is preferable that the amount of hemiformal end groups, formyl end groups, and end groups that are unstable to heat, acid, or base is small. Here, the hemiformal end group is represented by -OCH2OH, and the formyl end group is represented by -CHO.

[0014] The polyacetal resin used in this embodiment may be a recycled polyacetal resin product (including recovered products, material recycled products, chemical recycled products, etc.), a rejected product, or scraps generated when molding a molded product from a resin composition.

[0015] In addition to the above, the polyacetal resins that can be used include those described in paragraphs 0018 to 0043 of JP2015-074724A, the contents of which are incorporated herein by reference.

[0016] The resin composition of the present embodiment preferably contains 70% by mass or more of polyacetal resin in the resin composition, more preferably 75% by mass or more, even more preferably 80% by mass or more, and even more preferably 82% by mass or more. The upper limit is preferably 95% by mass or less, more preferably 92% by mass or less, and may be 88% by mass or less. The resin composition of the present embodiment may contain only one type of polyacetal resin, or may contain two or more types. When two or more types are contained, the total amount is preferably in the above range.

[0017] <Core-shell polymer> The resin composition of the present embodiment includes a core-shell polymer. By using the core-shell polymer, it is possible to impart flexibility to the obtained molded article. In addition, by using the core-shell polymer, it is possible to effectively suppress the decrease in weld elongation.

[0018] The average secondary particle diameter of the core-shell polymer in the polyacetal resin is preferably 10 to 250 nm. By setting the average secondary particle diameter of the core-shell polymer to 250 nm or less, the core-shell polymer is easily dispersed in the polyacetal resin, and the weld elongation can be increased. In addition, the interfacial force between the core-shell polymer and the polyacetal resin is also reduced, and the weld elongation can be increased. Such an average secondary particle diameter of the core-shell polymer in the polyacetal resin can be achieved by adjusting the selection of the type of core-shell polymer, the fluidity of the polyacetal resin, the melt-kneading conditions, etc.

[0019] The average secondary particle size of the core-shell polymer is preferably 240 nm or less, more preferably 210 nm or less, even more preferably 180 nm or less, even more preferably 150 nm or less, even more preferably 120 nm or less, and more preferably 30 nm or more, even more preferably 50 nm or more, even more preferably 80 nm or more, even more preferably 100 nm or more.

[0020] The type of the core-shell polymer used in this embodiment is not particularly limited, but the core is preferably a rubber-based polymer. The rubber-based polymer preferably contains at least one selected from butadiene-containing rubber, butyl acrylate-containing rubber, 2-ethylhexyl acrylate-containing rubber, and silicone-based rubber, and more preferably contains butadiene-containing rubber. The shell is preferably a polymer of one or more monomers such as (meth)acrylic acid ester and aromatic vinyl compound, and more preferably a polymer (acrylic resin) in which units derived from (meth)acrylic acid ester account for 50 mass% or more of the total. The core-shell polymer used in the present embodiment preferably has a core containing a rubber-based polymer and a shell containing an acrylic resin. When such a core-shell polymer is used, the effects of the present invention tend to be more effectively exhibited.

[0021] The content of the core-shell polymer in the resin composition of this embodiment is preferably 5 parts by mass or more, more preferably 7 parts by mass or more, even more preferably 10 parts by mass or more, even more preferably 13 parts by mass or more, even more preferably 15 parts by mass or more, and preferably 50 parts by mass or less, more preferably 40 parts by mass or less, even more preferably 30 parts by mass or less, even more preferably 25 parts by mass or less, and even more preferably 20 parts by mass or less, relative to 100 parts by mass of the polyacetal resin. By making it equal to or more than the lower limit, the softness of the obtained molded product tends to be improved. Also, by making it equal to or less than the upper limit, the effects of the present invention tend to be more effectively exhibited. The resin composition of the present embodiment may contain only one type of core-shell polymer, or may contain two or more types. When two or more types are contained, the total amount is preferably in the above range.

[0022] <Polyalkylene glycol> The resin composition of the present embodiment contains polyalkylene glycol. The polyalkylene glycol is preferably polyethylene glycol, polypropylene glycol, or polyethylene / polyalkylene glycol, and more preferably polyethylene glycol.

[0023] In this embodiment, the number average molecular weight of the polyalkylene glycol is 30,000, preferably 25,000 or less, more preferably 22,000 or less, and more preferably 200 or more, preferably 500 or more, and more preferably 800 or more. By making it equal to or less than the upper limit, the amount of formaldehyde generated from the molded product tends to be suppressed. Also, by making it equal to or more than the lower limit, the handling property becomes better. When the resin composition of the present embodiment contains two or more types of polyalkylene glycols, the mixture preferably falls within the above range.

[0024] In this embodiment, the value obtained by multiplying the number average molecular weight of the polyalkylene glycol by the content (unit: mass%) in the resin composition is 1,000 to 17,000. By making it equal to or less than the upper limit, the weld elongation and weld strength tend to be kept high. Also, by making it equal to or more than the lower limit, the releasability tends to be further improved. Here, the content of polyalkylene glycol in the resin composition is the content (mass %) of polyalkylene glycol in 100 mass % of the resin composition. The value obtained by multiplying the number average molecular weight of the polyalkylene glycol by the content (unit: mass%) in the resin composition is preferably 1500 or more, and may be 2000 or more, 4000 or more, 5000 or more, or 7000 or more depending on the application, etc., and may be 16000 or less, 13000 or less, 11000 or less, 8000 or less, or 5000 or less depending on the application, etc. By making it equal to or more than the lower limit, or by making it equal to or less than the upper limit, the effects of the present invention tend to be further improved.

[0025] The content of polyalkylene glycol in the resin composition of this embodiment is preferably 0.2% by mass or more, more preferably 0.4% by mass or more, and more preferably 5% by mass or less, more preferably 4% by mass or less, even more preferably 3% by mass or less, and even more preferably 2.5% by mass or less. By making it equal to or more than the lower limit, the mold releasability tends to be improved. Also, by making it equal to or less than the upper limit, the mold releasability tends to be improved while maintaining the weld elongation.

[0026] The content of polyalkylene glycol in the resin composition of this embodiment is preferably 0.3 parts by mass or more relative to 100 parts by mass of polyacetal resin, and may be 0.4 parts by mass or more, 0.6 parts by mass or more, 0.8 parts by mass or more, or 1 part by mass or more depending on the application, etc., and is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and even more preferably 4 parts by mass or less, and may be 3 parts by mass or less, 2 parts by mass or less, or 1 part by mass or less depending on the application, etc. The resin composition of the present embodiment may contain only one type of polyalkylene glycol, or may contain two or more types. When two or more types are contained, the total amount is preferably in the above range.

[0027] <Formaldehyde Scavenger> The resin composition of the present embodiment may contain a formaldehyde scavenger. By containing a formaldehyde scavenger, it is possible to effectively suppress the generation of formaldehyde from the obtained molded article. The formaldehyde scavenger preferably contains at least one selected from the group consisting of hydrazide compounds, hydrazones of hydrazine compounds, guanamine compounds, and urea compounds, and more preferably a hydrazide compound and / or a urea compound.

[0028] <<Hydrazide compounds>> The hydrazide compound is preferably a hydrazide compound having two or more hydrazide groups. Examples of the dihydrazide compound include an aliphatic dihydrazide compound and an aromatic dihydrazide compound.

[0029] Examples of the aliphatic dihydrazide compounds include carbodihydrazide, oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, azelaic acid dihydrazide, sebacic acid dihydrazide, dodecanedioic acid dihydrazide (1,12-dodecanedicarbohydrazide), 1,18-octadecanedicarbohydrazide, stearic acid dihydrazide, maleic acid dihydrazide, fumaric acid dihydrazide, and 7,11-octadecadiene-1,18-dicarbohydrazide.

[0030] Examples of the aromatic dihydrazide compound include isophthalic acid dihydrazide, terephthalic acid dihydrazide, 1,5-naphthalenedicarbohydrazide, 1,8-naphthalenedicarbohydrazide, 2,6-naphthalenedicarbohydrazide, 4,4'-oxybisbenzenesulfonylhydrazide, and 1,5-diphenylcarbonohydrazide.

[0031] The hydrazide compound used in the present invention is preferably represented by the following formula (1). Formula (1) [ka] In the above formula, R 11 represents an aliphatic hydrocarbon group having 2 to 18 carbon atoms, an alicyclic hydrocarbon group having 6 to 10 carbon atoms, or an aromatic hydrocarbon group having 6 to 10 carbon atoms; R 12 ~R 15 each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms; R 12 and R 13 , and R 14 and R 15 may be bonded to each other to form a ring.

[0032] In formula (1), R 11 represents an aliphatic hydrocarbon group having 2 to 18 carbon atoms, an alicyclic hydrocarbon group having 6 to 10 carbon atoms, or an aromatic hydrocarbon group having 6 to 10 carbon atoms, with an aliphatic hydrocarbon group having 2 to 18 carbon atoms being preferred. The number of carbon atoms in the aliphatic hydrocarbon group having 2 to 18 carbon atoms is preferably 4 or more, preferably 6 or more, and more preferably 8 or more. Furthermore, the number of carbon atoms in the aliphatic hydrocarbon group having 2 to 18 carbon atoms is preferably 16 or less, more preferably 14 or less, and even more preferably 12 or less. The aliphatic hydrocarbon group may be saturated or unsaturated, and may be linear or branched. Specific examples of the aliphatic hydrocarbon group include alkylene groups such as butylene, pentylene, hexylene, heptylene, octylene, nonylene, decylene, undecylene, dodecylene, tridecylene, tetradecylene, pentadecylene, hexadecylene, heptadecylene, octadecylene, and nonadecylene.

[0033] The alicyclic hydrocarbon group may be saturated or unsaturated. Examples of the alicyclic hydrocarbon group include a cycloalkylene group having a carbon number of 6 to 10. Examples of the cycloalkylene group include a cyclohexylene group.

[0034] The aromatic hydrocarbon group includes arylene groups such as a phenylene group and a naphthylene group. At least some of the carbon atoms of the aromatic hydrocarbon group may be bonded with a substituent, such as a halogen group, a nitro group, or an alkyl group having 1 to 20 carbon atoms.

[0035] In formula (1), R 12 ~R 15 are each independently preferably a hydrogen atom, a methyl group or an ethyl group, more preferably a hydrogen atom.

[0036] <<Hydrazone derivatives of hydrazine compounds>> The hydrazone derivative of a hydrazine compound is preferably at least one hydrazone derivative selected from the group consisting of compounds represented by the following formula (2) and compounds represented by the following formula (3). Formula (2) [ka] (In formula (2), R 1 R represents an aliphatic hydrocarbon group having 4 to 20 carbon atoms, an alicyclic hydrocarbon group having 6 to 10 carbon atoms, or an aromatic hydrocarbon group having 6 to 10 carbon atoms. 2 ~R 5 each independently represents a hydrogen atom or an alkyl group having 1 or 2 carbon atoms; R 2 and R 3 At least one of R represents an alkyl group having 1 or 2 carbon atoms; 4 and R 5 At least one of the groups represents an alkyl group having 1 or 2 carbon atoms.

[0037] In formula (2), R 1 represents an aliphatic hydrocarbon group having 4 to 20 carbon atoms, an alicyclic hydrocarbon group having 6 to 10 carbon atoms, or an aromatic hydrocarbon group having 6 to 10 carbon atoms. The aliphatic hydrocarbon group may be saturated or unsaturated, and may be linear or branched. Specific examples of the aliphatic hydrocarbon group include alkylene groups such as butylene, pentylene, hexylene, heptylene, octylene, nonylene, decylene, undecylene, dodecylene, tridecylene, tetradecylene, pentadecylene, hexadecylene, heptadecylene, octadecylene, nonadecylene, and icosylene. The aliphatic hydrocarbon group is preferably an aliphatic hydrocarbon group having 6 to 12 carbon atoms. In this case, the reactivity of the hydrazone of the hydrazine compound with formaldehyde is increased, and the generation of formaldehyde is more effectively suppressed. In addition, the contamination of the mold during molding can be more sufficiently suppressed. The alicyclic hydrocarbon group may be saturated or unsaturated. Examples of the alicyclic hydrocarbon group include a cycloalkylene group having a carbon number of 6 to 10. Examples of the cycloalkylene group include a cyclohexylene group. The aromatic hydrocarbon group includes arylene groups such as a phenylene group and a naphthylene group. At least some of the carbon atoms of the aromatic hydrocarbon group may be bonded with a substituent, such as a halogen group, a nitro group, or an alkyl group having 1 to 20 carbon atoms. In formula (2), R 2 ~R 5 each independently represents a hydrogen atom or an alkyl group having 1 or 2 carbon atoms; R 2 and R 3 At least one of R represents an alkyl group having 1 or 2 carbon atoms; 4 and R 5 At least one of these represents an alkyl group having 1 or 2 carbon atoms. Here, in formula (2), R 2 and R 4 When is an ethyl group, R 3 and R 5 is a hydrogen atom, and R 2 and R 4 When is a methyl group, R 3 and R 5 is preferably a hydrogen atom or a methyl group. In this case, the reactivity of the hydrazone of the hydrazine compound with formaldehyde becomes higher, and the generation of formaldehyde is more effectively suppressed.

[0038] Specific examples of the compound represented by the above formula (2) include 1,12-bis[2-(1-methylethylidene)hydrazino]]-1,12-dodecanedione, 1,12-bis(2-ethylidenehydrazino)-1,12-dodecanedione, 1,12-bis(2-propylidenehydrazino)-1,12-dodecanedione, 1,12-bis[2-(1-methylpropylidene)hydrazino]-1,12-dodecanedione, 1,12-bis[2-(1-ethylpropylidene)hydrazino]-1,12-dodecanedione, 1,10-bis[2-(1-methylethylidene)hydrazino]]-1,10-decanedione, 1,10-bis(2-propylidenehydrazino)-1,10-decanedione, 1,10-bis( 2-propylidenehydrazino)-1,10-decanedione, 1,10-bis[2-(1-methylpropylidene)hydrazino]-1,10-decanedione, 1,10-bis[2-(1-ethylpropylidene)hydrazino]-1,10-decanedione, 1,6-bis[2-(1-methylethylidene)hydrazino]-1,6-hexanedione, 1,6-bis(2-ethylidenehydrazino)-1,6-hexanedione, 1,6-bis(2-propylidenehydrazino)-1,6-hexanedione, 1,6-bis[2-(1-methylpropylidene)hydrazino]-1,6-hexanedione, 1,6-bis[2-(1-ethylpropylidene)hydrazino]-1,6-hexanedione, and the like.

[0039] Formula (3) [ka] (In formula (3), R 8 R represents an aliphatic hydrocarbon group having 4 to 20 carbon atoms, an alicyclic hydrocarbon group having 6 to 10 carbon atoms, or an aromatic hydrocarbon group having 6 to 10 carbon atoms. 6 and R 7 each independently represents an alicyclic hydrocarbon group having 3 to 12 carbon atoms.

[0040] In formula (3), R 8 is R 1 The same applies to the preferred range. R 6 and R 7 each independently represents an alicyclic hydrocarbon group having 3 to 12 carbon atoms. Examples of the alicyclic hydrocarbon group having 3 to 12 carbon atoms include a cyclohexylene group. Specific examples of the compound represented by the above formula (3) include 1,12-bis(2-cyclohexylidenehydrazino)-1,12-dodecanedione, 1,10-bis(2-cyclohexylidenehydrazino)-1,10-decanedione, and 1,6-bis(2-cyclohexylidenehydrazino)-1,6-hexanedione.

[0041] <<Guanamine compounds>> Examples of the guanamine compound include benzoguanamine and N-methylol benzoguanamine.

[0042] <<Urea compounds>> Examples of the urea compound include ethylene urea, dimethylethylene urea, propylene urea, and tetrabutyl urea.

[0043] When the resin composition of the present embodiment contains a formaldehyde scavenger, the content thereof is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, and even more preferably 0.1 parts by mass or more, and is preferably 0.4 parts by mass or less, and more preferably 0.3 parts by mass or less, relative to 100 parts by mass of the polyacetal resin. By making the content equal to or more than the lower limit, the generation of formaldehyde can be effectively suppressed, and by making the content equal to or less than the upper limit, the mold fouling can be effectively suppressed. The resin composition of the present embodiment may contain only one type of formaldehyde scavenger, or may contain two or more types. When two or more types are contained, the total amount is preferably in the above range.

[0044] <Antioxidants> The resin composition of the present embodiment may contain an antioxidant. By containing an antioxidant, the heat resistance of the obtained molded article tends to be improved. The type of antioxidant is not particularly limited, but a hindered amine antioxidant and / or a hindered phenol antioxidant is preferred, and a hindered phenol antioxidant is more preferred. For the antioxidant, reference can be made to the descriptions in paragraph 0046 of JP 2019-065221 A, paragraph 0063 of JP 2018-090677 A, and paragraph 0076 of JP 2018-188496 A, the contents of which are incorporated herein by reference.

[0045] When the resin composition of the present embodiment contains an antioxidant, the content thereof is preferably 0.01 parts by mass or more, more preferably 0.03 parts by mass or more, and even more preferably 0.05 parts by mass or more, and is preferably 3 parts by mass or less, more preferably 2 parts by mass or less, and even more preferably 1 part by mass or less, relative to 100 parts by mass of the polyacetal resin. By setting the content within the above range, the obtained molded product tends to have excellent thermal stability. The resin composition of the present embodiment may contain only one type of antioxidant, or may contain two or more types. When two or more types are contained, the total amount is preferably in the above range.

[0046] <Other ingredients> In addition to the above, the resin composition of the present embodiment may contain additives such as hydrocarbon wax, inorganic particles, stabilizers, colorants, nucleating agents, plasticizers, fluorescent brighteners, release agents (fatty acid ester compounds, silicon compounds, etc.), antistatic agents, and ultraviolet absorbers (benzotriazole or benzophenone compounds, etc.) as needed. The resin composition of this embodiment is adjusted so that the total of the polyacetal resin, the core-shell polymer, the polyalkylene glycol, and other components blended as necessary is 100% by mass. In the resin composition of this embodiment, the total of the polyacetal resin, the core-shell polymer, and the polyalkylene glycol preferably accounts for 85% by mass or more of the resin composition, more preferably accounts for 90% by mass or more, even more preferably accounts for 95% by mass or more, and even more preferably accounts for 98% by mass or more.

[0047] <<Hydrocarbon wax>> The resin composition of the present embodiment may contain a hydrocarbon wax. By including the hydrocarbon wax, there is a tendency for the mold releasability to be improved while maintaining the weld elongation and weld strength. The hydrocarbon wax is a wax containing a hydrocarbon as a main component, and may have a functional group such as an acid group.

[0048] The hydrocarbon wax used in this embodiment preferably has a melt viscosity measured using a B-type viscometer of 15 mPa·s or more, preferably 20 mPa·s or more, more preferably 80 mPa·s or more, and may be 100 mPa·s or more. By making the melt viscosity equal to or more than the lower limit, the occurrence of bleeding out onto the surface of the molded article can be more effectively prevented. The melt viscosity is preferably 6000 mPa·s or less, more preferably 5000 mPa·s or less, and may be 4000 mPa·s or less. By making the melt viscosity equal to or less than the upper limit, friction and wear properties and moldability can be further improved. The molecular weight is measured by the viscosimetry at 140° C. using a Brookfield type viscometer.

[0049] The hydrocarbon wax includes those called paraffin wax, polyolefin wax, and Fischer-Tropsch wax. In this embodiment, paraffin wax is preferred. Examples of hydrocarbon waxes include FT-100 and FT-0070 sold by Nippon Seiro, and Paraflint manufactured by SASOL. Particularly, examples of polyolefin waxes include Hiwax (manufactured by Mitsui Chemicals), Sanwax (manufactured by Sanyo Chemical Industries), Epolene (manufactured by Eastman Chemical), and Allied Wax (manufactured by Allied Signals).

[0050] When the resin composition of the present embodiment contains a hydrocarbon wax, the content thereof is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, even more preferably 0.3 parts by mass or more, and may be 0.8 parts by mass or more, and is preferably 15.0 parts by mass or less, more preferably 10.0 parts by mass or less, even more preferably 5.0 parts by mass or less, and even more preferably 3.0 parts by mass or less, relative to 100 parts by mass of the polyacetal resin. By making the content equal to or more than the lower limit, the mold releasability tends to be improved. Also, by making the content equal to or less than the upper limit, the mold releasability tends to be improved while maintaining the weld strength. The resin composition of the present embodiment may contain only one type of hydrocarbon wax, or may contain two or more types. When two or more types are contained, the total amount is preferably in the above range.

[0051] <Method of producing resin composition> The resin composition of the present embodiment can be easily prepared by a known method generally used for preparing conventional thermoplastic resin compositions. For example, (1) a method of mixing all the components constituting the composition, feeding the mixture into an extruder and melt-kneading the mixture to obtain a pellet-shaped composition, (2) a method of feeding a part of the components constituting the composition from the main feed port of an extruder and the remaining components from a side feed port, melt-kneading the mixture to obtain a pellet-shaped composition, or (3) a method of preparing pellets with different compositions by extrusion or the like, mixing the pellets to adjust the composition to a desired composition, etc. can be adopted.

[0052] Examples of the kneading machine include a kneader, a Banbury mixer, and an extruder. There are no particular limitations on the conditions and devices for mixing and kneading, and they may be appropriately selected from any conventionally known conditions. Kneading is preferably performed at a temperature at which the polyacetal resin melts or higher, specifically at the melting temperature of the polyacetal resin or higher (generally 180° C. or higher).

[0053] <Molded products> The molded article of the present embodiment is formed from the resin composition or pellets of the present embodiment. The pellets obtained by pelletizing the resin composition of the present embodiment are molded into a molded article by various molding methods. Alternatively, the resin composition melt-kneaded in an extruder can be directly molded into a molded article without going through pellets. The shape of the molded product is not particularly limited and can be appropriately selected depending on the application and purpose of the molded product, and examples thereof include plate-like, plate-like, rod-like, sheet-like, film-like, cylindrical, annular, circular, elliptical, gear-like, polygonal, irregularly shaped, hollow, frame-like, box-like, panel-like, etc. The molded product of this embodiment may be a finished product or a part.

[0054] The method for molding the molded product is not particularly limited, and any conventionally known molding method can be used, such as injection molding, injection compression molding, extrusion molding, profile extrusion, transfer molding, hollow molding, gas-assisted hollow molding, blow molding, extrusion blow molding, IMC (in-mold coating molding), rotational molding, multi-layer molding, two-color molding, insert molding, sandwich molding, foam molding, and pressure molding.

[0055] <Application> Examples of the resin composition of the present embodiment and molded articles formed from the resin composition include automobile parts such as trim clips, seat belt members, and headrest guides, building material parts, electric and electronic parts, office equipment parts, and daily necessities parts, as well as containers for frozen foods, beverages, and the like, home appliances such as refrigerator gaskets, hose bands, gaskets, and cable ties. In particular, the resin composition and molded article of this embodiment are suitable for use as a trim clip. EXAMPLES

[0056] The present invention will be described in more detail below with reference to examples. The materials, amounts, ratios, processing contents, processing procedures, etc. shown in the following examples can be appropriately changed without departing from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below. If the measuring instruments used in the examples are difficult to obtain due to discontinuation or the like, measurements can be made using other instruments with equivalent performance.

[0057] 1.Raw materials The following raw materials were used: [Table 1]

[0058] Ethylene Urea [ka]

[0059] <Measurement of number average molecular weight of polyalkylene glycol> The number average molecular weight of polyalkylene glycol is calculated from a hydroxyl value determined by a method in accordance with JIS K0070 and the following formula (1). Number average molecular weight = 56100 × 2 / (hydroxyl value) (1)

[0060] 2. Reference Examples, Examples 1 to 26, and Comparative Examples 1 to 13 <Production of Resin Composition Pellets> The components shown in Table 1 were mixed uniformly in the ratios (parts by mass) shown in Tables 2 to 8 using a Super Mixer manufactured by Kawada Manufacturing Co., Ltd. The resulting mixture was melt-kneaded using a twin-screw extruder (manufactured by Ikegai Corporation, PCM-30, screw diameter 30 mm) under conditions of a screw rotation speed of 120 rpm and a cylinder set temperature of 200°C, extruded into strands, and cut with a pelletizer to produce a resin composition (pellets).

[0061] <Improvement rate of release resistance> The pellets obtained above were subjected to a heat treatment in a hot air circulation dryer at a temperature of 80° C. for 4 hours. Next, the dried pellets were used in an injection molding machine with a cylinder temperature of 210°C, a mold temperature of 40°C, and a cooling time of 20 seconds to mold a box-shaped molded product with outer dimensions of 30 x 50 x 30 mm and a thickness of 1.5 mmt, and a rib with a width of 1.5 mmt in the center. The maximum demolding resistance value (unit: MPa) when the product was demolded by protruding an ejector pin was evaluated as the demolding resistance. The injection molding machine used was EC-100S manufactured by Shibaura Machine Co., Ltd. The improvement rate of the mold release resistance was expressed as a percentage by dividing the difference in mold release resistance between the material containing no polyalkylene glycol and the material containing polyalkylene glycol by the mold release resistance of the material containing no polyalkylene glycol. Examples 1 to 15 and 22 to 26 and Comparative Examples 1 to 8 and 13 are based on the Reference Example. Examples 16 to 18 and Comparative Example 10 are based on Comparative Example 9. For Examples 19 to 21 and Comparative Example 12, the improvement rates were calculated based on Comparative Example 11. The results are shown in the following Tables 2 to 8. The units are %.

[0062] <Weld strength retention rate> The pellets obtained above were subjected to a heat treatment in a hot air circulation dryer at a temperature of 80° C. for 4 hours. Next, the dried pellets were used in an injection molding machine with a cylinder temperature of 195°C and a mold temperature of 80°C to prepare ASTM tensile test pieces (thickness 1.6 mm) having a weld in the center. A tensile test was performed in accordance with ASTM D638 to measure the weld strength. The injection molding machine used was EC-100S manufactured by Shibaura Machine Co., Ltd. The weld strength retention was expressed as a percentage by dividing the weld strength of the material containing polyalkylene glycol by the weld strength of the material not containing polyalkylene glycol. Examples 1 to 15 and 22 to 26 and Comparative Examples 1 to 8 and 13 are based on the Reference Example. Examples 16 to 18 and Comparative Example 10 are based on Comparative Example 9. For Examples 19 to 21 and Comparative Example 12, the improvement rates were calculated based on Comparative Example 11. The results are shown in the following Tables 2 to 8. The units are %.

[0063] <Weld elongation retention rate> The pellets obtained above were subjected to a heat treatment in a hot air circulation dryer at a temperature of 80° C. for 4 hours. Next, the dried pellets were used in an injection molding machine with a cylinder temperature set to 195°C and a mold temperature set to 80°C to prepare ASTM tensile test pieces (thickness 1.6 mm) with a weld portion in the center. A tensile test was performed in accordance with ASTM D638 to measure the weld elongation. The injection molding machine used was EC-100S manufactured by Shibaura Machine Co., Ltd. The weld elongation retention rate was expressed as a percentage by dividing the weld elongation of the material containing polyalkylene glycol by the weld elongation of the material not containing polyalkylene glycol. Examples 1 to 15 and 22 to 26 and Comparative Examples 1 to 8 and 13 are based on the Reference Example. Examples 16 to 18 and Comparative Example 10 are based on Comparative Example 9. For Examples 19 to 21 and Comparative Example 12, the improvement rates were calculated based on Comparative Example 11. The results are shown in the following Tables 2 to 8. The units are %.

[0064] <Amount of formaldehyde generated> The pellets obtained above were subjected to a heat treatment in a hot air circulation dryer at a temperature of 80° C. for 4 hours. Next, the dried pellets were used in an injection molding machine to prepare flat test pieces of 100 mm x 40 mm x 2 mm with a cylinder temperature set at 210° C. and a mold temperature set at 80° C. For these test pieces, the amount of formaldehyde generated per 1 g of polyacetal resin was measured by the following method in accordance with the method described in the German Automotive Industry Association standard VDA275 (Automobile interior parts - Quantitative determination of formaldehyde emission by the revised flask method). (i) 50 mL of distilled water was placed in a polyethylene container, and the flat test piece was suspended in the air. The container was then closed with the lid closed and heated at 60°C for 3 hours. (ii) After standing at room temperature for 60 minutes, the flat test specimen was taken out. (iii) The amount of formaldehyde absorbed in the distilled water in the polyethylene container was measured using a UV spectrometer by the acetylacetone colorimetric method, and the amount of formaldehyde generated was determined by dividing this amount of formaldehyde by the mass of the POM in the flat test piece. The unit is the amount of formaldehyde generated (μg) per 1 g of polyacetal resin, i.e., μg / g-POM.

[0065] [Table 2]

[0066] [Table 3]

[0067] [Table 4]

[0068] [Table 5]

[0069] [Table 6]

[0070] [Table 7]

[0071] [Table 8]

[0072] In the above table, the ratio of Mn×PEG means the value obtained by multiplying the number average molecular weight of polyalkylene glycol by the content (unit: mass %) in the resin composition. As is clear from the above results, the resin composition of the present invention has excellent mold release resistance. In addition, the molded article formed from the resin composition of the present embodiment has high retention of weld strength and weld elongation. In addition, by incorporating a formaldehyde scavenger, the amount of formaldehyde emitted (μg / g-POM) was reduced.

Claims

1. The composition includes a polyacetal resin, a core-shell polymer, and a polyalkylene glycol, The polyalkylene glycol has a number average molecular weight of 200 to 30,000, and the value obtained by multiplying the number average molecular weight of the polyalkylene glycol by its content (unit: mass%) in the resin composition is 1,000 to 17,000.

2. The resin composition according to claim 1 , wherein the polyalkylene glycol comprises polyethylene glycol.

3. The resin composition according to claim 1 or 2, comprising 5 to 50 parts by mass of the core-shell polymer relative to 100 parts by mass of the polyacetal resin.

4. The resin composition according to claim 1 or 2, comprising 0.3 to 10 parts by mass of the polyalkylene glycol per 100 parts by mass of the polyacetal resin.

5. The resin composition according to claim 1 or 2, further comprising 0.01 to 0.4 parts by mass of a formaldehyde scavenger relative to 100 parts by mass of the polyacetal resin.

6. The resin composition according to claim 1 or 2, further comprising 0.01 to 3 parts by mass of a hindered phenol-based antioxidant per 100 parts by mass of the polyacetal resin.

7. The resin composition according to claim 1 or 2, further comprising paraffin wax.

8. the polyalkylene glycol comprises polyethylene glycol, The core-shell polymer is contained in an amount of 5 to 50 parts by mass relative to 100 parts by mass of polyacetal resin, The polyalkylene glycol is contained in an amount of 0.3 to 10 parts by mass relative to 100 parts by mass of the polyacetal resin, Further, the composition contains 0.01 to 0.4 parts by mass of a formaldehyde scavenger relative to 100 parts by mass of the polyacetal resin, The resin composition according to claim 1, further comprising 0.01 to 3 parts by mass of a hindered phenol-based antioxidant per 100 parts by mass of the polyacetal resin.

9. The resin composition according to claim 8 , further comprising paraffin wax.

10. A pellet formed from the resin composition of claim 1, 2, 8 or 9.

11. A molded article formed from the resin composition according to claim 1, 2, 8 or 9.

12. A molded article formed from the pellets of claim 10.

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