Resin composition, pellets, and molded article

Abstract

Provided are: a resin composition that includes a polyacetal resin and a thermoplastic polyurethane and has excellent tensile characteristics; pellets; and a molded article. This resin composition includes a polyacetal resin and a thermoplastic polyurethane. The thermoplastic polyurethane content is 10–50 parts by mass per 100 total parts by mass of the polyacetal resin and the thermoplastic polyurethane. As measured at a temperature of 200°C, a capillary length of 30 mm, a capillary diameter of 1 mm, and a shear rate of 2.43×10-1 (1 / sec), the melt viscosity of the thermoplastic polyurethane is 4,000–100,000 Pa·s, and the melt viscosity of the polyacetal resin is 500–4,000 Pa·s.

Description

Resin compositions, pellets, and molded articles

[0001] This invention relates to resin compositions, pellets, and molded articles. In particular, it relates to resin compositions having polyacetal resin as a main component.

[0002] Polyacetal resin, an engineering plastic, possesses excellent mechanical properties, sliding characteristics, friction and wear characteristics, heat resistance, and moldability, and is widely used as a core component in automobiles, office automation equipment, and other applications. On the other hand, thermoplastic polyurethane exhibits excellent dispersibility in polyacetal resin and can impart impact resistance to the polyacetal resin. For this reason, resin compositions containing both polyacetal resin and thermoplastic polyurethane are used.

[0003] For example, Patent Document 1 discloses a polyacetal resin composition comprising 100 parts by mass of polyacetal resin (A), 1 to 120 parts by mass of thermoplastic polyurethane (B), and 0.01 to 5 parts by mass of a formaldehyde scavenger (C) having formaldehyde-reactive nitrogen, wherein the thermoplastic polyurethane contains 0.10% by mass or less of residual isocyanate, has a water content of 3000 ppm by mass or less, and exhibits a melt viscosity of 200,000 poise or more at 180°C. Patent Document 1 also states that the resin composition has excellent impact resistance and can sufficiently suppress the generation of formaldehyde.

[0004] Japanese Patent Publication No. 2013-057044

[0005] The resin composition described in Patent Document 1 is an excellent resin composition in terms of impact resistance and suppression of formaldehyde generation, but there is room for improvement in applications requiring tensile properties. The present invention aims to solve this problem and to provide a resin composition comprising a polyacetal resin and a thermoplastic polyurethane, which has excellent tensile properties, as well as pellets and molded articles.

[0006] Based on the above problems, the inventors conducted studies and found that the above problems can be solved by adjusting the melt viscosity of the polyacetal resin and thermoplastic polyurethane, and further adjusting the blending ratio. Specifically, the above problems were solved by the following means: [1] A material containing polyacetal resin and thermoplastic polyurethane, wherein the content of thermoplastic polyurethane is 10 to 50 parts by mass per 100 parts by mass of the total of polyacetal resin and thermoplastic polyurethane, at 200°C, with a capillary length of 30 mm, a capillary diameter of 1 mm, and a shear rate of 2.43 × 10⁻⁶ －１A resin composition wherein the melt viscosity of the thermoplastic polyurethane measured at (1 / sec) is 4,000 to 100,000 Pa·s, and the melt viscosity of the polyacetal resin is 500 to 4,000 Pa·s. [2] The resin composition according to [1], wherein the glass transition temperature of the thermoplastic polyurethane is -15 to -5°C. [3] The resin composition according to [1] or [2], wherein the thermoplastic polyurethane does not completely dissolve when subjected to ultrasonic treatment in N,N-dimethylformamide at a liquid temperature of 55°C for 60 minutes under the conditions of output 40 W and frequency 42 kHz, and the mass reduction rate after treatment compared to before ultrasonic treatment is 0% by mass or more and less than 10% by mass. [4] The resin composition according to any one of [1] to [3], wherein the resin composition is molded into a test piece specified in ISO 9988-2:1999, JIS K7139 Type A standard, and the tensile elongation measured according to ISO 527 standard is 90% or more and 500% or less. [5] The resin composition according to any one of [1] to [4], wherein the glass transition temperature of the thermoplastic polyurethane is -15 to -5°C, the thermoplastic polyurethane does not completely dissolve when subjected to ultrasonic treatment in N,N-dimethylformamide at a liquid temperature of 55°C for 60 minutes under the conditions of output 40W and frequency 42kHz, and the mass reduction rate after the ultrasonic treatment compared to before the ultrasonic treatment is 0% by mass or more and less than 10% by mass, the resin composition is molded into a test piece specified in ISO 9988-2:1999, JIS K7139 Type A standard, and the tensile elongation measured according to ISO 527 standard is 90% or more and 500% or less. [6] Pellets of the resin composition described in any one of [1] to [5]. [7] A molded article formed from the resin composition described in any one of [1] to [5]. [8] A molded article formed from the pellets described in [6].

[0007] The present invention makes it possible to provide a resin composition comprising a polyacetal resin and a thermoplastic polyurethane, which has excellent tensile properties, as well as pellets and molded articles.

[0008] Hereinafter, embodiments for carrying out the present invention (hereinafter simply referred to as "these embodiments") will be described in detail. These embodiments are illustrative examples for explaining the present invention, and the present invention is not limited to these embodiments. In this specification, "~" is used to mean that the numerical values ​​before and after it include the lower and upper limits. Furthermore, the upper and lower limits of numerical values ​​in this specification are given as examples of these embodiments, regardless of the combination of the upper and lower limits. In this specification, preferred combinations of embodiments are more preferred embodiments. In this specification, all physical properties and characteristic values ​​are given at 23°C unless otherwise specified.

[0009] If the measurement methods, etc., described in the standards shown in this specification differ from year to year, unless otherwise specified, the standards as of January 1, 2025 shall apply. If the measurement methods, etc., described in the standards shown in this specification are obsolete as of January 1, 2025, the standards in effect at the time of obsolete shall apply.

[0010] The resin composition of this embodiment comprises a polyacetal resin and a thermoplastic polyurethane, with the thermoplastic polyurethane content being 10 to 50 parts by mass per 100 parts by mass of the total of the polyacetal resin and thermoplastic polyurethane, and is based on a temperature of 200°C, a capillary length of 30 mm, a capillary diameter of 1 mm, and a shear rate of 2.43 × 10⁻⁶. －１ The thermoplastic polyurethane, measured at (1 / sec), is characterized by having a melt viscosity of 4,000 to 100,000 Pa·s, and the polyacetal resin has a melt viscosity of 500 to 4,000 Pa·s. This configuration provides a resin composition containing polyacetal resin and thermoplastic polyurethane, which exhibits excellent tensile properties. In other words, thermoplastic polyurethanes with high viscosity tend to have a high degree of crosslinking. Even if the thermoplastic polyurethane blended into the polyacetal resin decomposes, a high degree of crosslinking can suppress the decrease in molecular weight of the thermoplastic polyurethane, and it is presumed that high tensile elongation can be maintained.

[0011] The embodiments of the present invention will be described in detail below, but the description of the constituent elements described below is just one example of an embodiment of the present invention and is not limited to these.

[0012] <Polyacetal Resin> The resin composition of this embodiment includes a polyacetal resin. The polyacetal resin is not particularly limited as long as it satisfies the desired melt viscosity, and known polyacetal resins can be used.

[0013] The polyacetal resin used in this embodiment is subjected to a temperature of 200°C, a capillary length of 30 mm, a capillary diameter of 1 mm, and a shear rate of 2.43 × 10⁻⁶. －１ The melt viscosity measured at (1 / sec) is 500 to 4,000 Pa·s. Setting it above the lower limit tends to further improve the tensile elongation of the resulting molded product. Similarly, setting it below the upper limit also tends to further improve the tensile elongation of the resulting molded product. The melt viscosity is preferably 550 Pa·s or higher, more preferably 600 Pa·s or higher, even more preferably 650 Pa·s or higher, even more preferably 800 Pa·s or higher, even more preferably 900 Pa·s or higher, and also preferably 3,500 Pa·s or lower, more preferably 3,000 Pa·s or lower, even more preferably 2,500 Pa·s or lower, even more preferably 2,400 Pa·s or lower, and even more preferably 2,000 Pa·s or lower. When the resin composition of this embodiment contains two or more polyacetal resins, it is preferable that the melt viscosity of the mixture falls within the above range.

[0014] The polyacetal resin used in this embodiment 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.

[0015] Examples of oxyalkylene groups having 2 to 6 carbon atoms include oxyethylene groups, oxypropylene groups, and oxybutylene groups.

[0016] In the polyacetal resin, the ratio of the oxyalkylene group having 2 to 6 carbon atoms to the total molar number of the oxymethylene group and the oxyalkylene group having 2 to 6 carbon atoms is not particularly limited and may be 0.5 to 10 mol%.

[0017] To produce the above polyacetal resin, trioxane is usually used as the main raw material. Further, to introduce an oxyalkylene group having 2 to 6 carbon atoms into the polyacetal resin, cyclic formal or 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, 1,3,6-trioxocane, etc., 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 may be used as the main raw material, to introduce an oxypropylene group, 1,3-dioxane may be used as the main raw material, and to introduce an oxybutylene group, 1,3-dioxepane may be used as the main raw material. In the polyacetal resin, it is preferable that the amount of hemi-formal end groups, the amount of formyl end groups, and the amount of end groups unstable to heat, acid, and base are small. Here, the hemi-formal end group is represented by -OCH ２ OH, and the formyl end group is represented by -CHO.

[0018] The polyacetal resin used in the present embodiment has a melt volume rate (MVR) measured according to ISO 1133 under the conditions of a temperature of 190 ° C and a load of 2.16 kg of 0.5 cm ３ / 10 min or more, preferably 0.6 cm ３ / 10 min or more, more preferably 0.8 cm ３ / 10 min or more, still more preferably 1 cm ３ / 10 min or more, even more preferably 5 cm ３ / 10 min or more. By setting it to be not less than the above lower limit value, the productivity of the resin composition tends to be further improved. Further, the MVR of the polyacetal resin is 20 cm３ / Preferably 10 minutes or less, 18 cm ３ / More preferably 10 minutes or less, 14 cm ３ / More preferably 10 minutes or less, and 10 cm ３ / More preferably 10 minutes or less, 8 cm ３ It is even more preferable if it is 10 minutes or less.

[0019] The polyacetal resin used in this embodiment may be recycled (including recovered products, material recycled products, chemical recycled products, etc.), rejected products, or scraps from thermoplastic resin molding.

[0020] In addition to the above, polyacetal resins described in paragraphs 0018 to 0043 of Japanese Patent Application Publication No. 2015-074724 can be used as polyacetal resins, and these contents are incorporated herein by reference.

[0021] The resin composition of this embodiment preferably contains polyacetal resin in a proportion of 60% by mass or more, more preferably 65% ​​by mass or more, even more preferably 70% by mass or more, preferably 85% by mass or less, and more preferably 80% by mass or less. The resin composition of this embodiment may contain only one type of polyacetal resin, or it may contain two or more types. If it contains two or more types, it is preferable that the total amount is within the above range.

[0022] <Thermoplastic Polyurethane> In this embodiment, any known thermoplastic polyurethane can be used, as long as it satisfies the desired melt viscosity.

[0023] The thermoplastic polyurethane used in this embodiment is 200°C, with a capillary length of 30 mm, a capillary diameter of 1 mm, and a shear rate of 2.43 × 10⁻⁶. －１The melt viscosity measured at (1 / sec) is 4,000 to 100,000 Pa·s. Setting it above the lower limit tends to further improve the tensile elongation of the resulting molded product. Conversely, setting it below the upper limit also tends to further improve the tensile elongation of the resulting molded product. The melt viscosity is preferably 4,500 Pa·s or more, more preferably 5,000 Pa·s or more, even more preferably 5,500 Pa·s or more, even more preferably 6,000 Pa·s or more, even more preferably 6,500 Pa·s or more, and also preferably 70,000 Pa·s or less, more preferably 50,000 Pa·s or less, even more preferably 30,000 Pa·s or less, even more preferably less than 20,000 Pa·s, even more preferably 15,000 or less, even more preferably 10,000 Pa·s or less, and further preferably 8,000 Pa·s or less and 7,500 Pa·s or less. When the resin composition of this embodiment contains two or more thermoplastic polyurethanes, it is preferable that the melt viscosity of the mixture falls within the above range.

[0024] The glass transition temperature of the thermoplastic polyurethane used in this embodiment is preferably -15°C or higher, more preferably -14°C or higher, even more preferably -13°C or higher, even more preferably -12°C or higher, and also preferably -5°C or lower, more preferably -6°C or lower, even more preferably -7°C or lower, even more preferably -8°C or lower, and even more preferably -9°C or lower. Setting it above the lower limit tends to further improve the tensile elongation of the molded product. Also, setting it below the upper limit tends to further improve the tensile elongation of the molded product.

[0025] The thermoplastic polyurethane used in this embodiment is preferably one that does not completely dissolve when subjected to ultrasonic treatment in N,N-dimethylformamide at a liquid temperature of 55°C for 60 minutes under the conditions of output 40W and frequency 42kHz, and preferably has a mass reduction rate of 0% by mass or more and less than 10% by mass compared to the mass before ultrasonic treatment. By keeping it within this range, the degree of crosslinking of the thermoplastic polyurethane can be increased. The mass reduction rate is preferably less than 9% by mass, more preferably less than 8% by mass, even more preferably less than 7% by mass, and even more preferably less than 6% by mass. Furthermore, even if the lower limit of the mass reduction rate is 1% by mass or more, the required performance can still be sufficiently met.

[0026] On the other hand, thermoplastic polyurethanes are preferably obtained by reacting a diol with a diisocyanate. Examples of diols include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, and 1,4-butanediol. Examples of diisocyanates include aromatic diisocyanates, aliphatic diisocyanates, and alicyclic diisocyanates. These can be used alone or in combination of two or more. Examples of aromatic diisocyanates include 1,4-phenylenediisocyanate, 2,4-toluenediisocyanate, 2,6-toluenediisocyanate, 2,2-methylenediphenylenediisocyanate, and naphthalenediisocyanate. Examples of aliphatic diisocyanates include hexamethylenediisocyanate. Examples of the above-mentioned alicyclic diisocyanates include isophorone diisocyanate, 4,4'-methylene-bis-(cyclohexyl isocyanate), 1,3-bis-(isocyanate-methyl)cyclohexane, and 1,4-bis-(isocyanate-methyl)cyclohexane. The diisocyanate may be 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 version of these isocyanate compounds, a prepolymer of these isocyanate compounds and polyhydric alcohols, or a blocked isocyanate compound obtained by encapsulating these isocyanate compounds with a blocking agent such as phenol, primary alcohol, or caprolactam.

[0027] Thermoplastic polyurethanes are commercially available. Examples of commercially available products include Clamiron U (manufactured by Kuraray), Esten (manufactured by Kyowa Hakko Kogyo), Miractran (manufactured by Nippon Polyurethane Industry), Peresen (manufactured by Dow Chemical), Isoplast (manufactured by Dow Chemical), Elastran (manufactured by BASF), Pandex (manufactured by Bayer), Desmopan (manufactured by Bayer), and Texin (manufactured by Bayer). These can be used individually or in combination of two or more types.

[0028] The thermoplastic polyurethane used in this embodiment may be recycled products (including recovered products, material recycled products, chemical recycled products, etc.), rejected products, or scraps from thermoplastic resin molding.

[0029] The content of thermoplastic polyurethane in the resin composition of this embodiment is 10 parts by mass or more, preferably 15 parts by mass or more, more preferably 20 parts by mass or more, and also 50 parts by mass or less, preferably 45 parts by mass or less, more preferably 40 parts by mass or less, even more preferably 35 parts by mass or less, and even more preferably 30 parts by mass or less, based on 100 parts by mass of the total of polyacetal resin and thermoplastic polyurethane. Setting the content above the lower limit tends to further improve the tensile elongation of the resulting molded article. Setting the content below the upper limit tends to further improve the rigidity and tensile strength of the resulting molded article. The resin composition of this embodiment may contain only one type of thermoplastic polyurethane, or it may contain two or more types. When two or more types are included, it is preferable that the total amount is within the above range.

[0030] In the resin composition of this embodiment, at 200°C, with a capillary length of 30 mm, a capillary diameter of 1 mm, and a shear rate of 2.43 × 10⁻¹⁴ －２ The ratio of the melt viscosity of thermoplastic polyurethane to the melt viscosity of polyacetal resin (TPU / POM), measured at (1 / sec), is preferably 0.1 or higher, more preferably 0.7 or higher, even more preferably 1.0 or higher, even more preferably 1.3 or higher, even more preferably 2.5 or higher, and also preferably 10.0 or lower, more preferably 9.0 or lower, even more preferably 7.0 or lower, even more preferably 6.0 or lower, and even more preferably 5.0 or lower. Setting it above the lower limit tends to further improve the tensile elongation of the molded product. Also, setting it below the upper limit tends to further improve the tensile elongation of the molded product.

[0031] <Other Components> The resin composition of this embodiment may contain other components, such as known additives and fillers, to the extent that they do not impair the objectives of the present invention. Other components that can be incorporated into the resin composition of this embodiment may include, for example, known thermoplastic polymers other than polyacetal resin and thermoplastic polyurethane (such as acid-modified polymers), weathering agents, formaldehyde scavengers, inorganic particles, antioxidants (hindered amine-based, hindered phenol-based), heat stabilizers, colorants, nucleating agents, plasticizers, fluorescent whitening agents, mold release agents (such as silicon compounds), antistatic agents, ultraviolet absorbers (such as benzotriazole-based or benzophenone-based compounds), flame retardants, flame retardant aids, and other additives as needed. The total amount of these other components is preferably less than 10% by mass of the resin composition, more preferably less than 7% by mass, even more preferably less than 5% by mass, even more preferably less than 3% by mass, and may be less than 1% by mass. The resin composition of this embodiment may also be substantially free of formaldehyde scavengers. Specifically, this means that the formaldehyde scavenging agent content is less than 0.01 parts by mass per 100 parts by mass of polyacetal resin, preferably less than 0.005 parts by mass, and more preferably less than 0.001 parts by mass.

[0032] The resin composition of this embodiment is prepared so that the total of the polyacetal resin, thermoplastic polyurethane, and other components added as needed is 100% by mass. Preferably, the total of the polyacetal resin and thermoplastic polyurethane in the resin composition of this embodiment is 85% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and may be 98% by mass or more.

[0033] <Method for Manufacturing the Resin Composition> The resin composition of this embodiment can be easily prepared by known methods commonly used for preparing conventional thermoplastic resin compositions. For example, (1) a method of mixing all the components constituting the resin composition, supplying it to an extruder for melt-kneading to obtain a pellet-shaped resin composition, (2) a method of supplying a portion of the components constituting the resin composition from the main feed port of an extruder and the remaining components from the side feed port for melt-kneading to obtain a pellet-shaped resin composition, (3) a method of preparing pellets with different compositions by extrusion or the like, and then mixing the pellets to adjust them into a resin composition having a predetermined composition. Examples of kneaders include kneaders, Banbury mixers, and extruders. There are no particular restrictions on the various conditions and equipment for mixing and kneading, and they can be appropriately selected and determined from any conventionally known conditions. Kneading is preferably carried out at a temperature above the melting temperature of the polyacetal resin, specifically above the melting temperature of the polyacetal resin (generally 180°C or higher).

[0034] <Physical Properties of the Resin Composition> The resin composition of this embodiment preferably has high tensile elongation and tensile strength. Specifically, when the resin composition of this embodiment is molded into a test piece specified in ISO 9988-2:1999, JIS K7139 Type A standard, and the tensile elongation measured according to ISO 527 standard is preferably 90% or more, more preferably 95% or more, even more preferably 100% or more, and even more preferably 110% or more. Furthermore, there is no particular upper limit for tensile elongation, but it is usually 500%. Specifically, when the resin composition of this embodiment is molded into a test piece specified in ISO 9988-2:1999, JIS K7139 Type A standard, and the tensile strength measured according to ISO 527 standard is preferably 25 MPa or more, more preferably 30 MPa or more, and even more preferably 35 MPa or more. Furthermore, there is no particular upper limit for tensile strength, but it is usually 100 MPa or less, and even 70 MPa or less is sufficient to meet the required performance. Tensile elongation and tensile strength are measured according to the examples described below.

[0035] <Molded Product> The molded product 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 molded products by various molding methods. Also, without going through the pellets, the resin composition melt-kneaded by an extruder can be directly molded into a molded product.The shape of the molded product is not particularly limited and can be appropriately selected according to the use and purpose of the molded product. For example, plate-like, plate-shaped, rod-shaped, sheet-shaped, film-shaped, cylindrical, annular, circular, elliptical, gear-shaped, polygonal-shaped, irregular-shaped products, hollow products, frame-shaped, box-shaped, panel-shaped ones, etc. can be mentioned. The molded product of the present embodiment may be a finished product or a component.

[0036] As a method for molding the molded product, there is no particular limitation, and a conventionally known molding method can be adopted. For example, injection molding method, injection compression molding method, extrusion molding method, profile extrusion method, transfer molding method, blow molding method, gas assist blow molding method, blow molding method, extrusion blow molding, IMC (in-mold coating molding) molding method, rotational molding method, multi-layer molding method, two-color molding method, insert molding method, sandwich molding method, foam molding method, pressure molding method, etc. can be mentioned.

[0037] The application field of the molded product of the present embodiment is not particularly defined, and it can be widely used in transportation machine parts such as automobiles, general machine parts, precision machine parts, electronic and electrical equipment parts, OA equipment parts, building materials and housing-related parts, medical devices, leisure and sports goods, toys, defense and aerospace products, automotive parts such as trim clips and seat belt members, headrest guides, building materials parts, electrical and electronic parts, office equipment parts, daily sundry goods parts, and also in household appliances such as refrigerator packings, and in hose bands, packings, binding bands, sliding parts, etc.

[0038] The present invention will be described more specifically with reference to the following examples. The materials, amounts used, ratios, treatment contents, treatment procedures, etc. shown in the following examples can be appropriately changed as long as they do not depart from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below. When the measuring instruments, etc. used in the examples are difficult to obtain due to obsolescence, etc., measurements can be made using other devices having equivalent performance.

[0039] 1. Raw materials The following raw materials were used.

[0040] <Measurement of melt viscosity> The melt viscosities of thermoplastic polyurethane (TPU) and polyacetal resin (POM) were measured according to JIS K 7199:1999 at 200 °C, with a capillary length of 30 mm, a capillary diameter of 1 mm, and a shear rate of 2.43×10 －１ (1 / sec).

[0041] <Measurement of glass transition temperature> The glass transition temperature of thermoplastic polyurethane (TPU) was measured according to ISO 6721-11 using DMA, and the Tg was specified from the changes in storage modulus (E´), loss modulus (E´´), and loss tangent (tanδ) with temperature change.

[0042] <Mass reduction rate> For the above TPU1 and TPU2, when ultrasonic treatment was performed in N,N-dimethylformamide (DMF) at a liquid temperature of 55 °C for 60 minutes under the conditions of an output of 40 W and a frequency of 42 kHz, they did not completely dissolve. If they completely dissolved, a uniform polymer solution would be formed, and the molecular chains of TPU would disperse in DMF to form a viscous liquid. Next, thermoplastic polyurethane (TPU1 and TPU2) was subjected to ultrasonic treatment in N,N-dimethylformamide at a liquid temperature of 55 °C for 60 minutes under the conditions of an output of 40 W and a frequency of 42 kHz, and the mass reduction rate after treatment relative to before treatment was measured. Specifically, 20 mL of a DMF (dimethylformamide) solution was poured into a 100 mL Erlenmeyer flask, placed in an ultrasonic cleaner at 55 °C for about 3 hours to raise the temperature, 0.5 g of pellets was added thereto, the ultrasonic cleaner was started to dissolve for 60 minutes, then the resin was taken out, dried in an oven at 80 °C for 12 hours, and the mass was measured.

[0043] 2. Examples 1-6, Comparative Examples 1-6 <Compounds> The components shown in Table 1 were blended as shown in Table 2 or Table 3 (the units for each component in Tables 2 and 3 are in mass%), blended in a tumbler, and then fed into the main feed port of a 30 mm diameter twin-screw extruder with one vent port for melt mixing (extrusion conditions: L / D = 35, extrusion temperature = 190°C, screw rotation speed = 120 rpm, vent vacuum pressure = -0.08 MPa, discharge volume = 10 kg / hr) to prepare pelletized resin compositions. The following evaluations were performed using the obtained resin compositions.

[0044] <Tensile Elongation and Tensile Strength> The resin composition obtained above was dried at 80°C for 3 hours, and then molded into test specimens specified in ISO 9988-2:1999 and JIS K7139 Type A standards using an injection molding machine (Shibaura Machine Co., Ltd. "EC-100S") under conditions of cylinder temperature 195°C and mold temperature 90°C. Tensile elongation (unit: %) and tensile strength (unit: MPa) were measured according to ISO 527 standards.

[0045]

[0046]

[0047] As is clear from the above results, the resin composition of the present invention exhibited excellent tensile elongation (Examples 1-6). In contrast, when the melt viscosity of the thermoplastic polyurethane was low (Comparative Examples 1-3), the tensile elongation was low. Similarly, when the melt viscosity of the polyacetal resin was low (Comparative Example 4), the tensile elongation was low. Furthermore, even when polyacetal resin and thermoplastic polyurethane with matching melt viscosities were blended, if the blending ratio was not appropriate (Comparative Examples 5 and 6), the tensile elongation was low or the tensile strength decreased (Comparative Examples 5 and 6).

[0048] Although the present invention has been described in detail using specific embodiments, it will be apparent to those skilled in the art that various modifications are possible without departing from the intent and scope of the invention.

Claims

1. Containing polyacetal resin and thermoplastic polyurethane, the thermoplastic polyurethane content is 10 to 50 parts by mass per 100 parts by mass of the total of polyacetal resin and thermoplastic polyurethane, and at 200°C, with a capillary length of 30 mm, a capillary diameter of 1 mm, and a shear rate of 2.43 × 10⁻⁶. －１ A resin composition in which the melt viscosity of the thermoplastic polyurethane, measured at (1 / sec), is 4,000 to 100,000 Pa·s, and the melt viscosity of the polyacetal resin is 500 to 4,000 Pa·s.

2. The resin composition according to claim 1, wherein the glass transition temperature of the thermoplastic polyurethane is -15 to -5°C.

3. The resin composition according to claim 1 or 2, wherein the thermoplastic polyurethane does not completely dissolve when subjected to ultrasonic treatment in N,N-dimethylformamide at a liquid temperature of 55°C for 60 minutes under the conditions of output 40W and frequency 42kHz, and the mass reduction rate after the ultrasonic treatment compared to before the ultrasonic treatment is 0% by mass or more and less than 10% by mass.

4. The resin composition according to claim 1 or 2, wherein the resin composition is molded into a test piece as specified in ISO 9988-2:1999 and JIS K7139 Type A, and the tensile elongation measured according to ISO 527 is 90% or more and 500% or less.

5. The resin composition according to claim 1, wherein the glass transition temperature of the thermoplastic polyurethane is -15 to -5°C, the thermoplastic polyurethane does not completely dissolve when subjected to ultrasonic treatment in N,N-dimethylformamide at a liquid temperature of 55°C for 60 minutes under the conditions of output 40W and frequency 42kHz, and the mass loss rate after the ultrasonic treatment compared to before the ultrasonic treatment is 0% by mass or more and less than 10% by mass, and the resin composition is molded into a test piece specified in ISO 9988-2:1999, JIS K7139 Type A standard, and the tensile elongation measured according to ISO 527 standard is 90% or more and 500% or less.

6. Pellets of the resin composition according to any one of claims 1, 2, or 5.

7. A molded article formed from the resin composition according to any one of claims 1, 2, or 5.

8. A molded article formed from the pellets described in claim 6.

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