Resin composition, pellet, and molded article

Abstract

To provide a resin composition that exhibits enhanced tensile strength when formed into a molded article, while considering environmental preservation, as well as a pellet and a molded article.SOLUTION: The resin composition of the present disclosure contains 5-50 pts.mass of a pulverized plant-derived porous granular powder including a fatty acid relative to 100 pts.mass of a polyacetal resin, the porous granular powder having a moisture content of 1-50 mass%.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a resin composition, a pellet, and a molded article, and more particularly 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. One of the known uses of polyacetal resin is as a sliding member. Examples of the use of polyacetal resin as a sliding member include Patent Document 1 and Patent Document 2. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-214490 [Patent Document 2] International Publication No. 2018 / 230389 Summary of the Invention [Problem to be solved by the invention]

[0004] The resin compositions described in Patent Documents 1 and 2 are materials with excellent sliding properties. However, in recent years, from the perspective of environmental conservation, the use of biomass materials and the effective use of resources have become important issues. In other words, resin compositions with sliding properties that take environmental conservation into consideration are also required. Furthermore, depending on the application, there are cases where improvements in tensile strength are required. The present invention aims to solve these problems and to provide a resin composition, pellets, and molded articles that improve the tensile strength of molded articles and that are environmentally friendly. [Means for solving the problem]

[0005] In light of the above-mentioned problems, the present inventors have conducted research and found that an improvement in tensile strength can be achieved by using a plant-derived porous powder containing a predetermined amount of moisture and fatty acids for a polyacetal resin. [1] For 100 parts by mass of polyacetal resin, The composition comprises 5 to 50 parts by mass of a plant-derived pulverized porous powder containing fatty acids, A resin composition, wherein the porous powder or granule contains 1 to 50% by mass of water. [2] The resin composition according to [1], further comprising 0.1 to 3 parts by mass of a fatty acid metal salt relative to 100 parts by mass of the polyacetal resin. [3] The resin composition according to [1] or [2], wherein the porous powder is derived from coffee grounds. [4] Further, the composition contains 0.1 to 3 parts by mass of a fatty acid metal salt relative to 100 parts by mass of the polyacetal resin, The resin composition according to any one of [1] to [3], wherein the porous powder is derived from coffee grounds. [5] Pellets of the resin composition according to any one of [1] to [4]. [6] A molded article molded from the resin composition according to any one of [1] to [4]. [7] A molded article molded from the pellets described in [5]. [8] The molded product according to [6] or [7], which is a sliding member. [Effects of the Invention]

[0006] The present invention provides a resin composition, pellets, and molded articles which have improved tensile strength when molded into a molded article and which are environmentally friendly. DETAILED DESCRIPTION OF THE INVENTION

[0007] Hereinafter, an embodiment for carrying out 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 only this embodiment. In this specification, the symbol "to" is used to mean 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 differ from year to year, they will be based on the standards in effect as of January 1, 2023, unless otherwise stated.

[0008] The resin composition of the present embodiment is characterized in that it contains 5 to 50 parts by mass of pulverized porous powder or granules derived from plants containing fatty acids per 100 parts by mass of polyacetal resin, and the moisture content of the porous powder or granules is 1 to 50% by mass. The present inventors have disclosed in the specification of International Application No. PCT / JP2024 / 011564 that the sliding properties can be improved by blending plant-derived porous powder particles containing fatty acids into a polyacetal resin. Furthermore, the use of porous powders derived from plants makes it an environmentally friendly material. In particular, the use of waste materials such as coffee grounds makes it possible to recycle resources. Under these circumstances, the inventors have conducted research and found that increasing the moisture content of the porous powder particles improves the tensile strength of the molded product. The reason for this is presumably that the heat of vaporization of water during extrusion suppresses the temperature rise of the resin during melt-kneading, thereby suppressing decomposition of the resin.

[0009] Hereinafter, the embodiments of the present invention will be described in detail. However, the explanation of the constituent elements described below is an example of an embodiment of the present invention, and the present invention is not limited to these contents.

[0010] <Polyacetal resin> The resin composition of the present embodiment contains a polyacetal resin. The polyacetal resin is not particularly limited in terms of type, etc., 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 typically used as the main raw material. Furthermore, to introduce oxyalkylene groups having 2 to 6 carbon atoms into the polyacetal resin, cyclic formals or cyclic ethers can be used. Specific examples of cyclic formals include 1,3-dioxolane, 1,3-dioxane, 1,3-dioxepane, 1,3-dioxocane, 1,3,5-trioxepane, and 1,3,6-trioxocane. Specific examples of cyclic ethers include ethylene oxide, propylene oxide, and butylene oxide. To introduce oxyethylene groups into the polyacetal resin, 1,3-dioxolane can be used as the main raw material. To introduce oxypropylene groups, 1,3-dioxane can be used as the main raw material. To introduce oxybutylene groups, 1,3-dioxepane can be used as the main raw material. In addition, it is preferable that the amount of hemiformal terminal groups, formyl terminal groups, and terminal groups unstable to heat, acid, or base is small in polyacetal resins. Here, the hemiformal terminal group is represented by -OCHOH, and the formyl terminal group is represented by -CHO.

[0014] The polyacetal resin used in this embodiment has a melt volume rate (MVR) of 0.5 cm, measured at a temperature of 190°C and a load of 2.16 kg in accordance with ISO 1133. 3 / 10 minutes or more is preferable, and 0.6 cm 3 / 10 minutes or more is more preferable, and 0.8 cm 3 / 10 minutes or more is more preferable, and 1cm 3 / 10 minutes or more is more preferable, and 5cm 3 It is more preferable that the MVR is 20 cm / 10 minutes or more. By making the MVR equal to or more than the lower limit, the productivity of the resin composition tends to be further improved. 3 / 10 minutes or less is preferable, 18cm 3 / 10 minutes or less is more preferable, and 14cm 3 / 10 minutes or less is more preferable, and 10cm 3 / 10 minutes or less is more preferable, and 8cm 3 It is even more preferable that the time is 10 minutes or less.

[0015] In addition to the above, the polyacetal resins that can be used include those described in paragraphs 0018 to 0043 of JP-A No. 2015-074724, the contents of which are incorporated herein by reference.

[0016] The resin composition of this embodiment preferably contains polyacetal resin in a proportion of 60% by mass or more of the resin composition, more preferably 65% ​​by mass or more, and even more preferably 70% by mass or more, with the upper limit being the amount at which the total amount of the resin composition other than the plant-derived porous powder or granule containing fatty acid is polyacetal resin. 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] <Plant-derived porous powder containing fatty acids> The resin composition of this embodiment contains porous powders and granules derived from plants containing fatty acids, and the moisture content of the porous powders and granules is 1 to 50% by mass. By using porous powders and granules derived from plants, an environmentally friendly resin composition can be obtained. Furthermore, by using porous powders and granules containing fatty acids, the sliding properties of the resin composition can be improved. In particular, the use of porous powders and granules achieves an oil absorption effect and provides a sustained release effect, allowing the sliding properties to be maintained for a long time. Furthermore, by using porous powder or granules with a moisture content of 1 to 50 mass %, a molded product with improved tensile strength can be obtained. The moisture content in the porous powder or granule is preferably 2% by mass or more, more preferably 6% by mass or more, even more preferably 16% by mass or more, and even more preferably 23% by mass or more, and is preferably 45% by mass or less, more preferably 40% by mass or less, and even more preferably 35% by mass or less. By setting the moisture content at or above the lower limit, the tensile strength of the resulting molded product tends to be further improved. On the other hand, by setting the moisture content at or below the upper limit, the amount of water vapor generated during extrusion is reduced, improving feedability. Furthermore, the kneadability with polyacetal resin tends to be improved. The moisture content in this embodiment is the amount of moisture (unit: mass %) contained in the coffee grounds, and is calculated from the difference between the moisture content before drying and the moisture content after drying.

[0018] Examples of plant-derived porous powders containing fatty acids include coffee grounds (residue after coffee extraction), soybean pulp, and residues (grounds) left after extracting oils such as rapeseed oil, sesame oil, and camellia oil. Because these substances contain fatty acids and have a porous structure, they are environmentally friendly, achieve oil absorption effects, and maintain long-lasting sliding properties. In this embodiment, the use of coffee grounds allows a marble-like pattern to be formed on the molded product, achieving a design advantage. Furthermore, the porous powder particles derived from plants containing fatty acids are porous, and therefore effectively function as a filler. Such a porous structure is formed by, for example, including cellulose.

[0019] The plant-derived porous powder containing fatty acids of this embodiment is preferably heated before use. When the porous powder is a dried product, it functions better as a filler. The drying temperature for the porous powder or granule is preferably less than 150° C., more preferably 140° C. or less, more preferably 125° C. or less, even more preferably 105° C. or less, still more preferably 90° C. or less, even more preferably 75° C. or less, and may further be 70° C. or less, 65° C. or less, 60° C. or less, or 55° C. The lower limit of the drying temperature for the porous powder or granule is, for example, 45° C. or more. By heating under such low temperature conditions, the sliding properties of the resulting molded product can be further improved, presumably because the deterioration and carbonization of the fatty acids contained in the porous powder or granules can be more effectively suppressed. The drying time for drying the porous powder or granule is preferably 30 minutes or more, more preferably 1 hour or more, more preferably 5 hours or more, or may be 10 hours or more, and is preferably 1 week or less, more preferably 3 days or less. Moreover, the porous powder or granule is usually water-insoluble.

[0020] The type of fatty acid contained in the porous powder or granule depends on the type of plant used, but when the porous powder or granule is heated at 280°C for 10 minutes and the gas generated is analyzed by GC-MS, the fatty acids detected include unsaturated fatty acids and / or saturated fatty acids, and preferably at least unsaturated fatty acids. The unsaturated fatty acid may be a monounsaturated fatty acid or a polyunsaturated fatty acid, and preferably contains at least a polyunsaturated fatty acid. Specific examples of unsaturated fatty acids include linoleic acid, oleic acid, linolenic acid, eicosapentaenoic acid, docosapentaenoic acid, docosahexaenoic acid, and arachidonic acid. Examples of saturated fatty acids include myristic acid, pentadecylic acid, palmitic acid, margaric acid, stearic acid, arachidic acid, heneicosylic acid, behenic acid, lignoceric acid, cerotic acid, and montanic acid.

[0021] The porous powder used in this embodiment preferably has a fatty acid content of 500 μg / g or more, more preferably 700 μg / g or more, even more preferably 1000 μg / g or more, even more preferably 1500 μg / g or more, and even more preferably 2500 μg / g or more, in decane equivalent, when the gas generated by heating at 280°C for 10 minutes is analyzed by GC-MS. By setting the content to be above the lower limit, the sliding properties of the resin composition tend to be further improved. Furthermore, the fatty acid content of the porous powder used in this embodiment, when analyzed by GC-MS, is preferably 10000 μg / g or less, more preferably 8000 μg / g or less, even more preferably 7000 μg / g or less, even more preferably 6000 μg / g or less, and even more preferably 5000 μg / g or less, in decane equivalent, when the content is below the upper limit, tends to be further improved.

[0022] The porous powder or granule used in this embodiment may contain only one type of fatty acid, but typically contains two or more types. When the porous powder or granule contains two or more types of fatty acids, the total amount is preferably within the above range.

[0023] The content of the porous powder or granules in the resin composition of this embodiment is 5 parts by mass or more, preferably 3 parts by mass or more, more preferably 8 parts by mass or more, even more preferably 12 parts by mass or more, even more preferably 15 parts by mass or more, and even more preferably 18 parts by mass or more, relative to 100 parts by mass of the polyacetal resin. By setting the content at or above the lower limit, the tensile elongation of the obtained molded article tends to be further improved. Furthermore, the upper limit of the content of the porous powder or granules is 50 parts by mass or less, preferably 40 parts by mass or less, more preferably 35 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 22 parts by mass or less, relative to 100 parts by mass of the polyacetal resin. By setting the content at or below the upper limit, high mechanical properties tend to be maintained. The resin composition of the present embodiment may contain only one type of porous powder or particle, or may contain two or more types. When two or more types are contained, the total amount is preferably in the above range.

[0024] <Fatty acid metal salts> The resin composition of the present embodiment preferably contains a fatty acid metal salt, which effectively prevents fatty acids derived from the porous powder or granule from appearing on the surface of the molded body, thereby shortening the molding time. In this embodiment, it is particularly preferred that the fatty acid of the plant-derived porous powder or grain containing fatty acid contains an unsaturated fatty acid, and the fatty acid constituting the fatty acid metal salt contains a saturated fatty acid. By adopting such a configuration, the effects of the present invention tend to be more effectively exhibited.

[0025] The fatty acid metal salt used in this embodiment is preferably a calcium salt and / or a magnesium salt, and preferably contains at least a calcium salt. The fatty acid metal salt used in this embodiment preferably has an aliphatic group having 10 to 50 carbon atoms. The number of carbon atoms in the fatty acid metal salt is preferably 12 or more, more preferably 14 or more, and is preferably 36 or less, more preferably 28 or less, even more preferably 25 or less, and even more preferably 20 or less. The aliphatic group is preferably a straight-chain aliphatic group. The aliphatic group may have a hydroxyl group as a substituent. By having a hydroxyl group as a substituent, the weighing time during molding of the resulting resin composition tends to be shorter. The aliphatic group may be a saturated aliphatic group or an unsaturated aliphatic group, but a saturated aliphatic group is preferred. More specifically, examples of fatty acids that constitute fatty acid metal salts include myristic acid, pentadecylic acid, palmitic acid, margaric acid, stearic acid, arachidic acid, heneicosylic acid, behenic acid, lignoceric acid, cerotic acid, and montanic acid, as well as fatty acids in which one of the hydrogen atoms in the aliphatic chain of these fatty acids has been substituted with a hydroxyl group, with stearic acid and hydroxystearic acid being preferred. In this embodiment, the fatty acid metal salt is preferably calcium stearate, magnesium stearate, calcium hydroxystearate, or magnesium hydroxystearate, more preferably calcium hydroxystearate or calcium stearate.

[0026] The content of the fatty acid metal salt in the resin composition of this embodiment is typically 0.1 parts by mass or more, preferably 0.3 parts by mass or more, more preferably 0.5 parts by mass or more, and may be 0.6 parts by mass or more, or even 0.9 parts by mass or more, or even 1.1 parts by mass or more, per 100 parts by mass of the polyacetal resin. By ensuring that the content is equal to or greater than the lower limit, the effect of suppressing slipping during molding tends to be more improved. Furthermore, the content of the fatty acid metal salt is typically 3 parts by mass or less, preferably 2.5 parts by mass or less, and more preferably 2.0 parts by mass or less, per 100 parts by mass of the polyacetal resin. By ensuring that the content is equal to or less than the upper limit, the effect of suppressing discoloration when the molded product is heated tends to be more improved. The resin composition of the present embodiment may contain only one fatty acid metal salt, or may contain two or more fatty acid metal salts. When two or more fatty acid metal salts are contained, the total amount is preferably in the above range.

[0027] <Other ingredients> The resin composition of this embodiment may contain known additives and fillers within the scope of the present invention. Examples of the additives and fillers that can be used in this embodiment include known thermoplastic polymers other than polyacetal resins (such as acid-modified polymers), weathering agents, formaldehyde scavengers, inorganic particles, antioxidants (hindered amines, hindered phenols), heat stabilizers, colorants, nucleating agents, plasticizers, fluorescent brighteners, mold release agents (such as silicon compounds), antistatic agents, ultraviolet absorbers (such as benzotriazoles or benzophenones), flame retardants, and flame retardant aids, which may be added as needed. The resin composition of this embodiment is prepared so that the total of the polyacetal resin, the plant-derived porous powder and granules containing fatty acids, and other components blended as necessary, is 100% by mass. In the resin composition of this embodiment, the total of the polyacetal resin and the plant-derived porous powder and granules containing fatty acids preferably accounts for 85% by mass or more of the resin composition, more preferably 90% by mass or more, even more preferably 95% by mass or more, and may even account for 98% by mass or more. In the resin composition of the present embodiment, the plant-derived porous powder or granule containing the polyacetal resin and fatty acid, and optionally a thermoplastic polymer other than the polyacetal resin, a weathering agent, a formaldehyde scavenger, inorganic particles, an antioxidant, a heat stabilizer, a colorant, a nucleating agent, a plasticizer, a fluorescent brightener, a release agent, an antistatic agent, an ultraviolet absorber, a flame retardant, and a flame retardant aid, are preferably contained in a total amount of 90% by mass or more of the resin composition, more preferably 95% by mass or more, even more preferably 97% by mass or more, even more preferably 98% by mass or more, even more preferably 99% by mass or more, and even more preferably 100% by mass. More preferably, in the resin composition of the present embodiment, the polyacetal resin, the plant-derived porous powder or granule containing fatty acid, and the weathering agent, formaldehyde scavenger, antioxidant, heat stabilizer, colorant, nucleating agent, plasticizer, fluorescent brightener, release agent, antistatic agent, ultraviolet absorber, flame retardant, and flame retardant aid, which are blended as needed, together account for 95% by mass or more of the resin composition, preferably 90% by mass or more, even more preferably 97% by mass or more, still more preferably 98% by mass or more, even more preferably 99% by mass or more, and still more preferably 100% by mass.

[0028] The resin composition in this embodiment may be configured to be substantially free of lubricating oil. "Substantially free" means that the lubricating oil content is less than 1% by mass of the resin composition, preferably less than 0.1% by mass, more preferably less than 0.01% by mass, and even more preferably less than 0.001% by mass. The resin composition in this embodiment may be configured to be substantially free of glass. "Substantially free of glass" means that the glass content in the resin composition is less than 15% by mass, preferably less than 10% by mass, more preferably less than 7% by mass, even more preferably less than 5% by mass, even more preferably less than 3% by mass, and even more preferably less than 1% by mass. The resin composition of this embodiment preferably does not substantially contain any filler other than the porous powder or granule derived from a plant containing a fatty acid. Specifically, the content of filler other than the porous powder or granule derived from a plant containing a fatty acid in the resin composition is preferably less than 10% by mass of the content of the porous powder or granule derived from a plant containing a fatty acid, more preferably less than 7% by mass, even more preferably less than 5% by mass, even more preferably less than 3% by mass, and even more preferably less than 1% by mass.

[0029] <Method of manufacturing resin composition> The resin composition of this embodiment can be easily prepared by a known method commonly used for preparing conventional thermoplastic resin compositions. For example, (1) a method in which all components constituting the resin composition are mixed, fed into an extruder, and melt-kneaded to obtain a pellet-shaped resin composition, (2) a method in which some of the components constituting the resin composition are fed through a main feed port of an extruder and the remaining components are fed through a side feed port, and melt-kneaded to obtain a pellet-shaped resin composition, or (3) a method in which pellets of different compositions are prepared by extrusion or the like, and the pellets are mixed to obtain a resin composition having a predetermined composition, etc., can be employed. Examples of the kneading machine include a kneader, a Banbury mixer, an extruder, etc. There are no particular limitations on the various conditions and devices for mixing and kneading, and they may be appropriately selected from any conventionally known conditions. Kneading is preferably carried out at a temperature above the melting point of the polyacetal resin, specifically above the melting point of the polyacetal resin (generally 180°C or higher).

[0030] <Molded products> The molded article of this embodiment is formed from the resin composition or pellets of this embodiment. The pellets obtained by pelletizing the resin composition of this embodiment can be molded into a molded article using various molding methods. Alternatively, a resin composition melt-kneaded in an extruder can be directly molded into a molded article without going through pelletization. An example of a molded article formed from the resin composition of this embodiment is an injection-molded article. Since injection-molded articles are formed in a mold, welds are formed. That is, an example of a molded article of this embodiment is a molded article having welds. The shape of the molded article is not particularly limited and can be appropriately selected depending on the application and purpose of the molded article. Examples 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, and panel-like shapes. The molded article of this embodiment may be a finished product or a part.

[0031] The method for molding the molded article 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, blow molding, gas-assisted blow molding, blow molding, extrusion blow molding, IMC (in-mold coating molding), rotational molding, multilayer molding, two-color molding, insert molding, sandwich molding, foam molding, and pressure molding.

[0032] The resin composition of this embodiment is preferably used for forming a sliding member, and therefore, a molded article formed from the resin composition of this embodiment is preferably used as a sliding member (sliding part). Specific examples of sliding members include gears, rotating shafts, bearings, various gears, cams, end face materials for mechanical seals, valve seats for valves, sealing members such as V-rings, rod packings, piston rings, and rider rings, as well as sliding members such as rotating shafts, rotating sleeves, pistons, impellers, and rollers for compressors, all of which are intended to meet the high quality demands of electrical and electronic equipment, office equipment, vehicles (automobiles), industrial equipment, and the like.

[0033] The sliding member of this embodiment can be used as a sliding member in combination with not only another sliding member of this embodiment but also other resin sliding members, fiber-reinforced resin sliding members, and ceramic or metal sliding members. [Example]

[0034] The present invention will be explained in more detail below with reference to examples. The materials, amounts used, ratios, processing details, 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.

[0035] 1.Raw materials The raw materials shown in Table 1 were used.

[0036] [Table 1]

[0037] The coffee grounds were dried completely at 100°C for 24 hours in a hot air drying oven. After drying, the moisture content was 0.5% by mass. The coffee grounds were then allowed to absorb pure water so that the moisture content (% by mass) in the coffee grounds was the amount shown in Table 2 below.

[0038] In Table 1 above, 1 g of coffee grounds was heated at 280°C for 10 minutes using a thermal desorption-gas chromatograph / mass spectrometer, and the gas evolved during heating was analyzed by GC-MS. The fatty acids detected were, in descending order of abundance, palmitic acid, a mixture of linoleic acid and oleic acid, stearic acid, and arachidic acid. The coffee grounds were heated at 280°C for 10 minutes, and the gas evolved was analyzed by GC-MS. The amount of fatty acids, calculated as decane, was found to be in the range of 500 μg / g to 10,000 μg / g.

[0039] 2. Examples 1 to 4, Comparative Example 1 <Compound> The components shown in Table 1 were compounded as shown in Table 2 (the units for each component in Table 2 are parts by mass), preblended in a Henschel mixer, and then fed into the main feed port of a 30 mm diameter twin-screw extruder equipped 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 rate = 10 kg / hr) to prepare a pelletized resin composition. The resulting resin compositions were evaluated as follows.

[0040] <Tensile strength> The resin composition obtained above was dried at 80°C for 3 hours and then molded into a test piece according to ISO9988-2 standard using an injection molding machine (Shibaura Machine Co., Ltd., "EC-100S") at a cylinder temperature of 195°C and a mold temperature of 90°C. The nominal tensile strain at break was measured according to ISO527 standard.

[0041] [Table 2]

[0042] The units of each component in Table 2 are parts by mass. The amount of coffee grounds in Table 2 indicates the amount of coffee grounds with a moisture content of 0.5% by mass after the above drying. The pure water in the composition indicates the amount of water absorbed by the coffee grounds. The amount of moisture in coffee grounds is the amount of moisture in 100% by mass of coffee grounds, and is expressed in mass %. In Example 1, 20 parts by weight of coffee grounds contained 0.5% by weight (0.1 parts by weight) of water, and 1 part by weight of water was absorbed. As a result, the moisture content of the coffee grounds was (0.1 + 1) / (20 + 1) = 5.2% by weight. The unit of tensile strength is MPa. As is clear from the above results, the molded articles formed from the resin composition of the present invention had excellent tensile strength (Examples 1 to 4). In contrast, when coffee grounds with a low moisture content were blended, the tensile strength was poor (Comparative Example 1). Furthermore, there was almost no difference in sliding properties between Examples 1 to 4 and Comparative Example 1.

[0043] 3.Reference examples A~D The coffee grounds were dried under the conditions shown in Table 3. After drying, the components were not pulverized but were compounded as shown in Table 3 (the units for each component in Table 3 are parts by mass), preblended in a Henschel mixer, and then charged into the main feed port of a 30 mm diameter twin-screw extruder equipped 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 rate = 10 kg / hr) to prepare a pelletized resin composition. The resulting resin compositions were evaluated as follows.

[0044] <Dynamic friction coefficient> The resin composition obtained above was dried at 80°C for 3 hours, and then molded into a cylindrical thrust test piece using an injection molding machine (Sumitomo Heavy Industries, Ltd., "SE-30DUZ") under conditions of a cylinder temperature of 195°C and a mold temperature of 90°C. The obtained cylindrical thrust test piece was subjected to a thrust friction and wear test against carbon steel S45C at a linear velocity of 10 cm / s, with the surface pressure increased every 3 minutes from 3 kg, 5 kg, and 10 kg, with the surface pressure increasing by 5 kg from 5 kg onwards. Focusing on the dynamic friction coefficient under high surface pressure (load 50 kg, surface pressure 4.9 MPa), where differences in the dynamic friction coefficient due to formulation are likely to occur, the average value of the dynamic friction coefficient over 3 minutes was recorded.

[0045] [Table 3]

[0046] Although the present invention has been described in detail with reference to specific embodiments, it will be apparent to those skilled in the art that various modifications can be made without departing from the spirit and scope of the invention.

Claims

1. For 100 parts by mass of polyacetal resin, The composition comprises 5 to 50 parts by mass of a plant-derived pulverized porous powder containing fatty acids, The resin composition, wherein the porous powder or granule contains 1 to 50% by mass of water.

2. The resin composition according to claim 1, further comprising a fatty acid metal salt in an amount of 0.1 to 3 parts by mass per 100 parts by mass of the polyacetal resin.

3. The resin composition according to claim 1 , wherein the porous powder is derived from coffee grounds.

4. Further, the composition contains 0.1 to 3 parts by mass of a fatty acid metal salt relative to 100 parts by mass of the polyacetal resin, The resin composition according to claim 1 , wherein the porous powder is derived from coffee grounds.

5. Pellets of the resin composition according to any one of claims 1 to 4.

6. A molded article molded from the resin composition according to any one of claims 1 to 4.

7. A molded article formed from the pellets according to claim 5.

8. The molded article according to claim 6, which is a sliding member.

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