Resin composition and molded article

Abstract

To provide a resin composition capable of yielding a molded article with excellent appearance even when using a plant-derived filler.SOLUTION: Provided is a resin composition comprising a polyester resin, a plant-derived filler, and a polymer having an acid value of 10 mg KOH / g or more.SELECTED DRAWING: None

Description

[Technical field]

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

[0002] Conventionally, molded articles of resin compositions have excellent physical and chemical properties and are inexpensive, and therefore have been used in various applications such as machinery, electrical and electronic equipment, office automation equipment, automotive interior and exterior materials, and electric vehicles. In general, fillers are blended into resin compositions to increase the mechanical strength of the molded articles. Furthermore, attempts to increase the proportion of bio-based raw materials in the resulting molded articles by using plant-derived materials in the resin compositions have also been considered.

[0003] Known examples of such resin compositions include a resin composition containing a polyolefin resin, cellulose fibers, and an α-olefin copolymer having good compatibility with the polyolefin resin (see, for example, Patent Document 1). Alternatively, known examples of the resin compositions include a resin composition containing a polyester resin, an inorganic filler, and a polymer having a specific melt viscosity (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-183022 A [Patent Document 2] International Publication No. 2018 / 070424 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when a plant-derived material such as cellulose fiber is used as a filler, the filler may aggregate in the resin composition, which may result in a poor appearance of the molded article.

[0006] Therefore, an object of the present invention is to provide a resin composition which can give a molded article having excellent appearance even when a plant-derived filler is used. [Means for solving the problem]

[0007] In order to achieve the above object, the present inventors have conducted extensive research and have found that when a filler derived from a specific plant is used in combination with a polyester resin, the above problem can be solved by further using a polymer having a specific acid value in combination, and have thus completed the present invention.

[0008] [1] A resin composition comprising a polyester resin, a plant-derived filler, and a polymer having an acid value of 10 mg KOH / g or more. [2] The resin composition according to [1], wherein the polymer has a structural unit derived from an unsaturated carboxylic acid. [3] The resin composition according to [2], wherein the unsaturated carboxylic acid is a dicarboxylic acid anhydride. [4] The resin composition according to [2], wherein the polymer has a structural unit derived from the unsaturated carboxylic acid in a main chain of the polymer. [5] The resin composition according to any one of [1] to [4], wherein the polymer contains a structural unit derived from an α-olefin having 10 or more carbon atoms. [6] The resin composition according to any one of [1] to [5], wherein the acid value of the polymer is 300 mg KOH / g or less. [7] The resin composition according to any one of [1] to [6], wherein the polymer has a mass average molecular weight of 5,000 or more and 200,000 or less. [8] The resin composition according to any one of [1] to [7], wherein the ratio of the plant-derived filler to 100 parts by mass of the polyester-based resin is 5 parts by mass or more and 400 parts by mass or less. [9] The resin composition according to any one of [1] to [8], wherein the ratio of the polymer to 100 parts by mass of the plant-derived filler is 1 part by mass or more and 100 parts by mass or less.

[10] A molded article comprising the resin composition according to any one of [1] to [9]. Effect of the Invention

[0009] According to the present invention, it is possible to provide a resin composition which can give a molded article having excellent appearance even when a plant-derived filler is used. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, the embodiments of the present invention will be described in detail, but the present invention is not limited to the following embodiments as long as it does not deviate from the purpose. In this specification, "to" includes the lower limit and the upper limit. In addition, for each preferred range, the upper limit and the lower limit can be used in any combination.

[0011] <1.Resin composition> A resin composition according to one embodiment of the present invention contains a polyester resin (hereinafter sometimes referred to as polyester resin (A)), a plant-derived filler (hereinafter sometimes referred to as plant-derived filler (B)), and a polymer having an acid value of 10 mg KOH / g or more (hereinafter sometimes referred to as polymer (C)). By containing these components in the resin composition, it is possible to obtain a molded article with excellent appearance while using a recyclable plant-derived filler. The reason for this is not clear, but the following reasons are thought to be the cause.

[0012] That is, plant-derived fillers are generally prone to aggregation in the matrix of polyester resins, and even when a dispersant is used in combination, many dispersants make it difficult to disperse the fillers appropriately in the matrix. However, by using a polymer having an acid value of 10 mg·KOH / g or more in combination as in the present embodiment, the polymer functions as an excellent dispersant for the filler and exhibits a surfactant-like action that shows affinity for both the polyester resin and the plant-derived filler. As a result, the plant-derived filler is well dispersed in the resin composition, and it is considered that the molded article obtained from the resin composition has a good appearance.

[0013] Furthermore, in the molded body according to this embodiment, the plant-derived filler is well dispersed without agglomeration, and therefore in the combination of the polyester-based resin and the plant-derived filler, good mechanical properties are exhibited due to the resin composition containing the filler, and as a result, good releasability from metal surfaces during processing can be exhibited.

[0014] In addition, when a resin composition is obtained by adding a plant-derived filler having an elongated shape (cotton-like) such as an average fiber length of 300 μm or more and an average fiber diameter of less than 50 μm to a polyester-based resin, the plant-derived filler is likely to clog the raw material inlet or outlet of the extruder during the production of the resin composition, i.e., when melt-kneading with an extruder or the like, due to its cotton-like shape, and the processability tends to decrease. Therefore, it is necessary to devise ways to uniformly mix the plant-derived filler with the polyester-based resin or to improve the bite of the plant-derived filler into the rotating body. Here, with many dispersants, the cotton-like plant-derived filler is not uniformly mixed, and sufficient effects cannot be expected, but by using the polymer (C) so that the polymer (C) functions as a dispersant as described later in detail as in this embodiment, it is expected that the clogging at the raw material inlet or outlet of the extruder can be suppressed and good processability can be obtained by exerting a surfactant-like action that shows affinity to both the polyester-based resin and the plant-derived filler.

[0015] <1-1. Polyester resin (A)> As described above, the resin composition according to the present embodiment includes a polyester resin. The "polyester resin" in the present embodiment may be a resin including a molecular structure in which a dicarboxylic acid component and a diol component are condensed and polymerized. Of the dicarboxylic acid component and the diol component, one or both of the components may be a single compound or a mixture of two or more kinds. The quantitative ratio of the above components in the mixture may be appropriately selected.

[0016] Examples of the above "dicarboxylic acid component" include terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, oxalic acid, malonic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, neopentyl acid, isophthalic acid, naphthalenedicarboxylic acid, diphenyl ether dicarboxylic acid, and p-oxybenzoic acid. Among these, aromatic dicarboxylic acid components are preferred from the viewpoint of heat resistance or mechanical properties. Examples of aromatic dicarboxylic acid components include terephthalic acid, isophthalic acid, and naphthalenedicarboxylic acid.

[0017] Examples of the above "diol component" include ethylene glycol, 1,2-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 3-methylpentadiol, 1,3-hexanediol, 1,6-hexanediol, hydrogenated bisphenol A, diethylene glycol, 1,4-cyclohexanedimethanol, triethylene glycol, polyethylene glycol, dipropylene glycol, polypropylene glycol and polytetramethylene glycol.

[0018] Alternatively, the polyester resin in this embodiment may be a polyester resin containing a molecular structure of a polymer of an oxyacid or a copolymer of an oxyacid. Examples of the oxyacid include lactic acid, ε-caprolactone, and p-β-hydroxyethoxybenzoic acid.

[0019] The polyester resin according to the present embodiment may contain a molecular structure in which a trifunctional or higher carboxylic acid component such as trimellitic acid or pyromellitic acid, or a trifunctional or higher polyol component such as trimethylolpropane pentaerythritol, is copolymerized in small amounts, from the viewpoint of improving physical properties such as adjusting crystallinity.

[0020] The polyester resin according to the present embodiment may contain recycled resin regenerated from plastic waste or scraps. The recycling method for obtaining the recycled resin is not limited, and may be, for example, chemical recycling in which used resin is chemically converted and then regenerated, or material recycling in which used resin is sorted, impurities are removed, and then the resin is pulverized, washed, granulated, and the like. Furthermore, the polyester resin according to the present embodiment may be a mixture of recycled resin and virgin resin.

[0021] Examples of the polyester resin according to the present embodiment include aromatic polyester resin, aliphatic polyester resin, oxyacid polymer, and polyester elastomer. Examples of aromatic polyester resin include polyethylene terephthalate resin, polypropylene terephthalate resin, polybutylene terephthalate resin, polyethylene isophthalate resin, polyethylene naphthalate resin, polybutylene naphthalate resin, and polytrimethylene terephthalate resin. Examples of aliphatic polyester resin include polyethylene succinate resin and polybutylene succinate resin. Examples of oxyacid polymer include polylactic acid resin and polycaprolactone resin. Examples of polyester elastomer include elastomers obtained by copolymerizing aromatic polyester with polyalkylene glycol.

[0022] The polyester resin may be a homopolymer or a copolymer of any combination. The polyester resin in this embodiment may be a mixture of one type or two or more types. The ratio of the resins in the mixture may be appropriately selected. From the viewpoint of heat resistance or moldability at low temperature, the polyester resin in this embodiment is preferably a polyethylene terephthalate resin, a polybutylene terephthalate resin, a polytrimethylene terephthalate resin, or a polyester elastomer.

[0023] From the viewpoint of mechanical strength of the molded product, the polyester resin according to the present embodiment may be a mixture of an amorphous polyester resin and another polyester resin.

[0024] The amorphous polyester resin may be, for example, a resin containing a molecular structure of a condensation polymer having terephthalic acid as the main component of the acid component and ethylene glycol as the main component of the diol component. Examples of the amorphous polyester resin include glycol-modified polyethylene terephthalate resin (PETG) and isophthalic acid copolymerized polyethylene terephthalate resin (IPA-PET). Examples of commercially available amorphous polyester resins include the "SKYGREEN (registered trademark)" series manufactured by SK Chemicals, the "EastarCopolyester (registered trademark)" series and the "TRITAN (registered trademark)" series manufactured by Eastman Chemical, and the "ALTESTER (registered trademark)" series manufactured by Mitsubishi Gas Chemical Company, Inc.

[0025] The aforementioned "other polyester resin" may be a polyester resin other than the amorphous polyester resin. The other polyester resin is preferably a resin having compatibility with the amorphous polyester resin. For example, among the resins exemplified as the polyester resin, the other polyester resin is preferably a polyethylene terephthalate resin, a polybutylene terephthalate resin, a polytrimethylene terephthalate resin or a polyester elastomer from the viewpoint of compatibility with the amorphous polyester resin, more preferably a polybutylene terephthalate resin or a polyester elastomer, and even more preferably a polybutylene terephthalate resin. Examples of commercially available products of the other polyester resin include the "NovaDuran (registered trademark)" series manufactured by Mitsubishi Engineering Plastics Corporation, the "Duranex (registered trademark)" series manufactured by Polyplastics Co., Ltd., the "Vylon (registered trademark)" series manufactured by Toyobo Co., Ltd., and the "Tefabloc" series manufactured by Mitsubishi Chemical Corporation.

[0026] <1-2. Plant-derived filler (B)> As described above, the resin composition according to the present embodiment contains a plant-derived filler. The presence of the plant-derived filler and the polymer (C) described below can improve the appearance of the molded article. In the present invention, the plant-derived filler means a substance obtained by subjecting an organ of an organism belonging to the plant kingdom in biological classification to a process such as crushing, or a substance composed of components extracted from the organ. There is no particular restriction on the plant-derived filler, as long as it can be mixed with a polyester resin to obtain a molded article. In other words, any plant-derived filler can be used as long as it is solid.

[0027] Examples of the plant-derived filler include pulp, bagasse, rice husks, tea leaves, wood flour, bamboo flour, straw powder, reed powder, cellulose powder, paper powder, starch, grain flour, and hemp.

[0028] The average fiber length of the plant-derived filler is not particularly limited, but in order to improve mechanical properties, it is preferably 300 μm or more, more preferably 400 μm or more, and particularly preferably 500 μm or more.On the other hand, in order to improve dispersibility, it is preferably 10,000 μm or less, more preferably 7,500 μm or less, more preferably 5,000 μm or less, more preferably 3,000 μm or less, more preferably 2,000 μm or less, and particularly preferably less than 1,000 μm.

[0029] The average fiber diameter of the plant-derived filler is not particularly limited, but in order to improve mechanical properties, it is preferably 0.1 μm or more, more preferably 0.3 μm or more, even more preferably 0.5 μm or more, even more preferably 5 μm or more, and particularly preferably 10 μm or more. On the other hand, in order to improve dispersibility, it is preferably less than 50 μm, more preferably 45 μm or less, and particularly preferably 40 μm or less. The average fiber length and average fiber diameter of the plant-derived filler can be measured using an optical microscope or an electron microscope.

[0030] There is no particular limitation on the water content of the plant-derived filler, but in order to improve processability, it is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and particularly preferably 30 parts by mass or less, with the lower limit being 0 parts by mass.

[0031] Although there is no particular limitation on the aspect ratio of the plant-derived filler, the dispersibility of the filler in the polyester resin tends to decrease as the aspect ratio increases. Therefore, the present invention is more effective when the aspect ratio of the filler is 1.1 or more, even more effective when it is 3.0 or more, and particularly effective when it is 5.0 or more. On the other hand, although there is no particular upper limit, it is usually 100,000 or less, preferably 150 or less, and more preferably 100 or less.

[0032] <1-3. Polymer (C)> The resin composition according to the present embodiment contains a polymer (C) having an acid value of 10 mg KOH / g or more. The acid value of the polymer (C) is 10 mg KOH / g or more, but in order to further improve the affinity with the plant-derived filler, it is more preferably 60 mg KOH / g or more, even more preferably 70 mg KOH / g or more, and even more preferably 75 mg KOH / g or more. On the other hand, in order to improve the processability, the acid value is preferably 300 mg KOH / g or less, more preferably 250 mg KOH / g or less, even more preferably 200 mg KOH / g or less, even more preferably 150 mg KOH / g or less, and particularly preferably 135 mg KOH / g or less. The acid value of the polymer (C) can be measured by titration with phenolphthalein as an indicator and potassium hydroxide as a titration reagent.

[0033] The polymer (C) in this embodiment may have a structural unit derived from an unsaturated carboxylic acid. It is preferable that the polymer (C) has a structural unit derived from an unsaturated carboxylic acid from the viewpoint of increasing the affinity with the filler component. Examples of the structural unit derived from an unsaturated carboxylic acid include a structural unit derived from an unsaturated carboxylic acid, a structural unit derived from an ester of an unsaturated carboxylic acid, a structural unit derived from an unsaturated carboxylic acid anhydride, and a structural unit derived from an imide of an unsaturated carboxylic acid.

[0034] Unsaturated carboxylic acids include (meth)acrylic acid, maleic acid, methylmaleic acid, fumaric acid, methylfumaric acid, tetrahydrophthalic acid, itaconic acid, citraconic acid, crotonic acid, isocrotonic acid, glutaconic acid, and norbornane-5-ene-2,3-dicarboxylic acid.

[0035] Examples of esters of unsaturated carboxylic acids include (meth)acrylic acid esters, specific examples of which include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and glycidyl (meth)acrylate. Examples of anhydrides of unsaturated carboxylic acids include maleic anhydride, itaconic anhydride, citraconic anhydride, and 5-norbornene-2,3-dicarboxylic anhydride. Examples of imides of unsaturated carboxylic acids include maleimide compounds, specific examples of which include maleimide, N-ethylmaleimide, and N-phenylmaleimide.

[0036] Among these, it is preferable that the unsaturated carboxylic acid is a dicarboxylic acid anhydride from the viewpoint of enhancing affinity with the filler component.

[0037] In addition, it is preferable that the polymer (C) in this embodiment has a structural unit derived from an unsaturated carboxylic acid in the main chain of the polymer (C) from the viewpoint of having affinity for the two components, the thermoplastic resin and the filler component.

[0038] The mass average molecular weight of the polymer (C) in this embodiment may be 5,000 or more and 200,000 or less. The mass average molecular weight of the polymer (C) is not particularly limited, but is preferably 1,000 or more, more preferably 5,000 or more, and particularly preferably 7,500 or more in order to maintain mechanical properties. On the other hand, the mass average molecular weight of the polymer (C) is preferably 400,000 or less, more preferably 300,000 or less, even more preferably 200,000 or less, particularly preferably 100,000 or less, particularly preferably 50,000 or less, and even more preferably 20,000 or less, and most preferably 15,000 or less in order to improve processability. The mass average molecular weight of the polymer (C) preferably satisfies both the upper and lower limits described above, and may be, for example, from 1,000 to 400,000, from 5,000 to 200,000, or from 7,500 to 15,000. The mass average molecular weight of the polymer (C) is a value calculated in terms of standard polystyrene, measured by dissolving the polymer (C) in tetrahydrofuran (THF) and subjecting it to gel permeation chromatography.

[0039] The polymer (C) in this embodiment may contain a structural unit derived from an α-olefin having at least 10 carbon atoms. For example, the polymer (C) is preferably a copolymer of the above-mentioned unsaturated carboxylic acid and an α-olefin.

[0040] Although there is no particular limitation on the α-olefin, an α-olefin having 10 to 80 carbon atoms is preferred. If the α-olefin has 10 or more carbon atoms, it tends to be easier to handle (process) during processing, and if it has 80 or less carbon atoms, it tends to be more compatible with polyester resins. In particular, the number of carbon atoms in the α-olefin is preferably 15 or more, more preferably 20 or more, even more preferably 25 or more, and most preferably 30 or more. On the other hand, the number of carbon atoms in the α-olefin is preferably 70 or less, more preferably 60 or less, and particularly preferably 50 or less.

[0041] The number and content of carbon atoms of the α-olefin can be determined as follows: the polymer (C) is dissolved in THF, and the solution is subjected to pyrolysis GC-MS (gas chromatography mass spectrometer, using a non-polar column) to obtain the molecular weight, and the number and content of carbon atoms of the α-olefin can be calculated from the obtained molecular weight.

[0042] When polymer (C) has a molecular structure of a copolymer with an α-olefin containing a structural unit derived from the unsaturated carboxylic acid described above, the proportion of α-olefin units in 100 mol% of polymer (C) is not particularly limited, but in order to improve the dispersibility of the polyester resin and the plant-derived filler, it is preferably 20 mol% or more, and more preferably 30 mol% or more, while in order to improve the appearance of the molded article, it is preferably 80 mol% or less, and more preferably 70 mol% or less.

[0043] Furthermore, when polymer (C) has a molecular structure of a copolymer with an α-olefin, containing the above-mentioned structural units derived from an unsaturated carboxylic acid, the proportion of the structural units derived from a saturated carboxylic acid in 100 mol% of polymer (C) is not particularly limited, but in order to improve the dispersibility of the polyester resin and the plant-derived filler, it is preferably 20 mol% or more, and more preferably 30 mol% or more, while in order to improve the appearance of the molded article, it is preferably 80 mol% or less, and more preferably 70 mol% or less.

[0044] Examples of commercially available copolymers (C) include Lycorb (registered trademark) CE2 (manufactured by Clariant Japan KK) and Diacaluna (registered trademark) 30M (manufactured by Mitsubishi Chemical Corporation).

[0045] <1-4. Composition of Resin Composition> In the resin composition, the ratio of the plant-derived filler (B) to 100 parts by mass of the polyester resin (A) is not particularly limited, but in order to maintain the mechanical properties, it is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and particularly preferably 15 parts by mass or more, while in order to improve processability, it is preferably 400 parts by mass or less, more preferably 250 parts by mass or less, and particularly preferably 150 parts by mass or less.

[0046] In the resin composition, the ratio of the polymer (C) to 100 parts by mass of the plant-derived filler (B) is not particularly limited, but in order to maintain the mechanical properties, it is preferably 1 part by mass or more, more preferably 3 parts by mass or more, even more preferably 5 parts by mass or more, particularly preferably 10 parts by mass or more, and most preferably 15 parts by mass or more; on the other hand, in order to improve processability, it is preferably 100 parts by mass or less, more preferably 90 parts by mass or less, and particularly preferably 80 parts by mass or less.

[0047] The proportion of the polyester resin (A) in 100 parts by mass of the resin composition is not particularly limited, but in order to improve processability, it is preferably 20 parts by mass or more, more preferably 30 parts by mass or more, and particularly preferably 40 parts by mass or more, while in order to maintain mechanical properties, it is preferably 95 parts by mass or less, more preferably 92.5 parts by mass or less, and particularly preferably 90 parts by mass or less.

[0048] The proportion of the plant-derived filler (B) in 100 parts by mass of the resin composition is not particularly limited, but in order to maintain the mechanical properties, it is preferably 5 parts by mass or more, more preferably 7.5 parts by mass or more, and particularly preferably 10 parts by mass or more, while in order to improve processability, it is preferably 80 parts by mass or less, more preferably 70 parts by mass or less, and particularly preferably 60 parts by mass or less.

[0049] The proportion of polymer (C) in 100 parts by mass of the resin composition is not particularly limited, but in order to maintain the mechanical properties, it is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and particularly preferably 1.5 parts by mass or more, while in order to improve processability, it is preferably 15 parts by mass or less, more preferably 12.5 parts by mass or less, and particularly preferably 10 parts by mass or less.

[0050] The resin composition may contain other components in addition to the polyester resin (A), the plant-derived filler (B) and the polymer (C).

[0051] The other components include resins other than polyesters, such as polyamides, polyesters, polycarbonates, polyvinyl chloride, polystyrene, and polyolefins.

[0052] Other components include a thermoplastic elastomer (D). Examples of the thermoplastic elastomer (D) include an olefin-based elastomer, a styrene-based elastomer, an amide-based elastomer, a urethane-based elastomer, and a dynamically crosslinked thermoplastic elastomer.

[0053] Among these, the thermoplastic elastomer (D) is preferably an olefin-based elastomer from the viewpoint of further improving the mechanical properties of the resin composition of the present invention.

[0054] The olefin-based elastomer is an olefin-based thermoplastic elastomer mainly composed of an olefin such as ethylene, propylene, or 1-butene. Examples of the olefin-based elastomer include a blend of polypropylene and ethylene-propylene copolymer rubber or a crosslinked product thereof, a blend of polyethylene and ethylene-propylene copolymer rubber or a crosslinked product thereof, a blend of polypropylene and ethylene-propylene-non-conjugated polyene copolymer rubber or a crosslinked product thereof, a blend of polyethylene and ethylene-propylene-non-conjugated polyene copolymer rubber or a crosslinked product thereof, a blend of polypropylene and ethylene-1-octene copolymer rubber or a crosslinked product thereof, a blend of polyethylene and ethylene-1-octene copolymer rubber or a crosslinked product thereof, and the like. Crosslinking can be carried out by a known method.

[0055] Commercially available olefin-based elastomers include, for example, "Milastomer" and "Toughmer" (both manufactured by Mitsui Chemicals, Inc.), "Santoprene" and "Vistamax" (both manufactured by ExxonMobil Japan, LLC), "Esprene EPDM" and "Esporex TPE" (both manufactured by Sumitomo Chemical Co., Ltd.), "Engage" (manufactured by The Dow Chemical Company), "Thermorun" (manufactured by Mitsubishi Chemical Corporation), "Modic" (manufactured by Mitsubishi Chemical Corporation), and "Prime TPO" (manufactured by Prime Polymer Co., Ltd.).

[0056] The proportion of the thermoplastic elastomer (D) in 100 parts by mass of the resin composition is not particularly limited, but in order to maintain the mechanical properties, it is preferably 1 part by mass or more, more preferably 5 parts by mass or more, and particularly preferably 10 parts by mass or more, while in order to improve processability, it is preferably 60 parts by mass or less, more preferably 55 parts by mass or less, and particularly preferably 50 parts by mass or less.

[0057] Further, as other components, various additives that do not fall under the category of plant-derived fillers can be mentioned. Examples of various additives include flame retardants (phosphorus-based, bromine-based, silicone-based, organic metal salt-based, etc.), drip prevention agents (e.g., fluorinated polyester, silicone and aramid fiber), lubricants (e.g., long-chain fatty acid metal salts such as magnesium stearate, etc.), release agents (e.g., pentaerythritol tetrastearate, etc.), nucleating agents, antistatic agents, stabilizers (e.g., phenol-based stabilizers, sulfur-based stabilizers, phosphorus-based stabilizers, ultraviolet absorbers, amine-based light stabilizers, etc.), plasticizers, dyes and pigments. Note that these other components can be well-known materials, and can be arbitrarily selected and used according to the application of the resin composition, and each other component in the resin composition can also be arbitrarily selected.

[0058] The proportion of other components in 100 parts by mass of the resin composition is not particularly limited, but is usually 0 parts by mass or more, preferably 10 parts by mass or less, and more preferably 5 parts by mass or less.

[0059] Any method may be used to produce the resin composition. For example, the polyester resin (A), the plant-derived filler (B), the polymer (C), and other components as required may be thoroughly mixed using a premixing means such as a V-type blender, a Henschel mixer, a mechanochemical device, or an extrusion mixer, and may be granulated using an extrusion granulator or a briquetting machine, and then melt-kneaded and extruded using a melt mixer.

[0060] Examples of the melt kneader include twin-screw extruders such as vented twin-screw extruders, Banbury mixers, kneading rolls, single-screw extruders, and multi-screw extruders having three or more screws. The temperature during melt kneading is, for example, 170 to 260° C. The resin composition extruded as described above is directly cut and pelletized by a device such as a pelletizer, or cooled to form strands, and then the strands are cut and pelletized by a device such as a pelletizer.

[0061] <2. Molded body> The resin composition can be molded to obtain a molded article. Examples of applications of the resin composition include molded articles obtained by recycling automobile, motorcycle, and ship parts, electrical and electronic parts, miscellaneous goods, films, and molded articles, and molded articles useful in other fields.

[0062] Furthermore, by using a polyester resin (A) having relatively high biodegradability such as polyethylene succinate resin, polybutylene succinate resin, or polylactic acid resin as the polyester resin (A) in the resin composition, the biodegradability of the resin composition and the molded article made therefrom is improved. As a result, the burden on the environment when the molded article is disposed of is further reduced. For example, by using such a biodegradable molded article as a molded article (e.g., agricultural film or material, etc.) used on the ground or underground, it is possible to reduce the work of collecting and disposing of the molded article after use.

[0063] The molded article contains the resin composition. That is, the molded article contains the polyester resin (A), the plant-derived filler (B), and the polymer (C), and may contain other components as necessary. The preferred ratio of each component in the molded article is the same as the preferred ratio described in the above-mentioned resin composition. The shape of the molded article is not particularly limited, and may take various shapes such as a resin plate, sheet, film, cable, or irregular shape.

[0064] The molded article can be obtained by molding the present resin composition. The molding method is not particularly limited, and examples thereof include extrusion processing, calendar processing, injection molding, rolling, compression molding, blow molding, etc. The temperature when molding the present resin composition is, for example, 170 to 260°C. EXAMPLES

[0065] The present invention will be specifically described below with reference to examples. However, the present invention is not limited to the following examples. In the following examples, % is by weight unless otherwise specified.

[0066] [Examples 1 to 6] The raw materials were blended in the ratios shown in Table 1 and mixed by hand blending. Then, using a kneading and extrudability tester (model name "4C-150", manufactured by Toyo Seiki Seisakusho Co., Ltd.), the mixture was melt-kneaded at a screw rotation speed of 30 rpm and a mixer temperature of 140 to 200°C to obtain resin compositions 1 to 6, respectively.

[0067] Each of the obtained resin compositions 1 to 6 was molded using a press molding machine (manufactured by Shoji Iron Works Co., Ltd.) at a molding temperature of 140 to 200° C. to obtain molded products 1 to 6 (sheet-like molded products having a thickness of 0.5 to 1.5 mm), respectively.

[0068] [Comparative Examples 1 to 3] Resin compositions 7 to 9 were each obtained in the same manner as in Example 1, except that the raw materials were mixed in the ratio shown in Table 1. Molded articles 7 to 9 were each obtained in the same manner as in Example 1.

[0069] [Raw materials] Details of each raw material shown in Table 1 are as follows. (Polyester resin) LX175: Polylactic acid (TotalEnergies Corbion, LX-175) FZ91: Polybutylene succinate resin (Mitsubishi Chemical Corporation, FZ91, melt mass flow rate 5.0g / 10min) (Plant-derived filler) BC1000: Cellulose fiber (ARBOCEL BC1000 manufactured by Rettenmaier Japan Co., Ltd., average fiber length 700 μm, average fiber diameter 20 μm, bulk density 0.066 g / mL, decomposition temperature approximately 180° C., moisture content 0.1 to 15% by mass) (Polymer) Diacaluna (registered trademark) 30M: Copolymer of α-olefin and maleic anhydride (manufactured by Mitsubishi Chemical Corporation, Diacaluna 30M, acid value 80 mg KOH / g, mass average molecular weight 12,000, melting point approximately 70 to 80°C)

[0070] [evaluation] The molded bodies were evaluated by the following methods.

[0071] (1) Dispersibility The clear portion of each of the molded bodies 1 to 9 was visually observed. The clear portion was judged as "satisfactory" (◯) when no aggregates were found, and was judged as "unsuitable" (×) when aggregates were found. The results are shown in Table 1.

[0072] (2) Peelability Each of the resin compositions 1 to 9 was melt-kneaded for 5 minutes using a kneading and extrudability tester (model name "4C-150", manufactured by Toyo Seiki Seisakusho Co., Ltd.) under the conditions of a filling amount of 35 g, a screw rotation speed of 30 rpm, and a mixer temperature of 200 ° C., and then the resin composition was recovered from the mixer section. When the "recoverable molded body" was 98% or more of the filling amount, it was judged as "suitable" (○), and when the "recoverable molded body" was less than 98%, it was judged as "unsuitable" (×). The "recoverable molded body" is the amount of the resin composition that easily peeled off by simply touching the mixer section after the above melt-kneading. In the production of a molded body from the resin composition, if the resin composition stuck to the mixer section is rubbed with a brush or the like when recovering it, foreign matter may be contained in the molded body. Therefore, only the resin composition that easily peels off as described above becomes a "recoverable molded body". The "recoverable molded body" refers to the ease of removal (i.e., releasability) of the resin composition from the mixer section of the kneading device after melt-kneading of the resin composition. The results are shown in Table 1. [formula] Recovery rate (%) = (recoverable compacts / filling amount) x 100

[0073] [Table 1]

[0074] [Consideration] When resin compositions 1 to 6 are molded, no filler aggregation is observed, and the resin compositions have excellent releasability. This is believed to be because resin compositions 1 to 6 each contain a polymer, and therefore the plant-derived filler is well dispersed in the resin composition. That is, the molded article is believed to have good appearance because the filler is dispersed without agglomeration in the resin composition. In addition, since the filler is dispersed without agglomeration in the molded article, the mechanical properties of the molded article are improved by such filler, and as a result, excellent releasability is believed to be exhibited.

[0075] In the resin compositions 7 to 9, the filler was found to aggregate when molded into a product, and the peelability was also insufficient. This is believed to be because the resin compositions did not contain a polymer, which resulted in insufficient dispersion of the plant-derived filler.

Claims

1. A resin composition comprising a polyester resin, a plant-derived filler, and a polymer having an acid value of 10 mg·KOH / g or more.

2. The resin composition according to claim 1 , wherein the polymer has a structural unit derived from an unsaturated carboxylic acid.

3. The resin composition according to claim 2 , wherein the unsaturated carboxylic acid is a dicarboxylic acid anhydride.

4. The resin composition according to claim 2 , wherein the polymer has a structural unit derived from the unsaturated carboxylic acid in a main chain of the polymer.

5. 2. The resin composition according to claim 1, wherein the polymer contains a structural unit derived from an α-olefin having 10 or more carbon atoms.

6. The resin composition according to claim 1 , wherein the acid value of the polymer is 300 mg·KOH / g or less.

7. The resin composition according to claim 1, wherein the polymer has a mass average molecular weight of 5,000 or more and 200,000 or less.

8. The resin composition according to claim 1 , wherein a ratio of the plant-derived filler to 100 parts by mass of the polyester-based resin is 5 parts by mass or more and 400 parts by mass or less.

9. The resin composition according to claim 1 , wherein a ratio of the polymer to 100 parts by mass of the plant-derived filler is 1 part by mass or more and 100 parts by mass or less.

10. A molded article comprising the resin composition according to any one of claims 1 to 9.

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