Resin composition and method for producing the same

Abstract

To provide a resin composition that is both high in strength and has a high biomass content. [Solution] The resin composition comprises a biomass filler containing an inorganic filler derived from biomass, and a thermoplastic resin.

Description

Technical Field

[0001] This disclosure relates to a resin composition excellent in strength and environmental harmony, and a method for producing the same, using biomass filler and thermoplastic resin as raw materials.

Background Art

[0002] Amid the deepening of global environmental problems such as climate warming and ocean pollution, the generation of energy by burning fossil fuels and the use of products such as plastics made from fossil fuels are being reexamined, and the realization of a decarbonized society has become a major challenge for society as a whole. Among them, reducing the use of plastics derived from fossil fuels and replacing them with bio-based resources as much as possible directly leads to reducing the use of fossil fuels, and if bio-based resources are decomposable in nature, they are expected to contribute to preventing ocean pollution and the like. Even when combustion treatment is carried out as the final disposal, if it is derived from living organisms, including carbon and other constituent elements, the material balance in the biosphere will not change, and the increase of greenhouse gases such as carbon dioxide in the atmosphere will also be suppressed.

[0003] Under such a background, the technology of incorporating bio-based fillers into plastics to reduce the use of fossil fuels will become an even more important technology in the future. For example, as a method of mixing highly hydrophobic polypropylene and cellulose having a hydrophilic surface, Patent Document 1 discloses a method of carboxymethylating cellulose fibers and compounding them with a polymer having an amino group or an acid-modified polyolefin resin.

[0004] Among thermoplastic resins, so-called engineering plastics such as polyamide, which are excellent in strength, have particularly poor wettability with cellulose and are difficult to compound. Patent Document 2 discloses that when polyamide and cellulose fibers are compounded, polyphenylene ether is added to promote homogeneous compounding and increase strength.

[0005] Furthermore, Patent Document 3 discloses a method for increasing the heat resistance of cellulose fiber fibers by acetylating the hydroxyl groups on the surface of cellulose fiber fibers, and increasing their strength by protecting them from damage caused by heating during composite formation.

[0006] Furthermore, as a biomass filler other than cellulose fiber, Patent Document 4 discloses a calcium-containing batch pellet that is safe and has excellent mechanical strength and water resistance, obtained by blending calcium carbonate obtained from seashells with polyolefin resin. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] WO2014 / 087767 issue [Patent Document 2] WO2021 / 080010 issue [Patent Document 3] Japanese Patent Publication No. 2021-187885 [Patent Document 4] Utility Model Registration No. 3230019 Gazette [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] Although the composite of cellulose fiber as a biomass material with resin is known, cellulose fiber is an organic fiber. Therefore, during the composite process with resin, the high-temperature process that melts the resin causes thermal degradation of the cellulose fiber, leading to a decrease in strength.

[0009] Furthermore, even when using biomass fillers whose main component is calcium carbonate obtained from seashells and other sources, there was a problem in that the strength of the composite resin was insufficient because the calcium carbonate powder is not fibrous.

[0010] In view of the above, this disclosure is the result of the inventors' diligent efforts and aims to provide a high-strength, high-biomass resin composition that combines a biomass filler resistant to thermal and oxidative degradation with a resin, while also providing sufficient strength. [Means for solving the problem]

[0011] The resin composition relating to this disclosure comprises a biomass filler containing an inorganic filler derived from biomass, and a thermoplastic resin.

[0012] The method for producing the resin composition according to this disclosure includes a step of stirring and kneading while heating and melting a powder mixture of a thermoplastic resin and a biomass filler containing an inorganic filler derived from biomass.

[0013] A method for producing a resin composition according to this disclosure includes the steps of: mixing a thermoplastic resin, a biomass filler containing an inorganic filler derived from biomass, and a maleic anhydride structure-containing additive to obtain a powder mixture; and stirring and kneading the powder mixture while heating and melting it. [Effects of the Invention]

[0014] The resin composition according to this disclosure can be made into a resin composition that is high in strength and has a high biomass content. [Brief explanation of the drawing]

[0015] [Figure 1] This figure shows an AFM image of the resin composition in Example 10. [Figure 2] This figure shows the AFM-IR measurement spectrum of the resin composition in Example 10. [Figure 3] Table 1 shows the parts by weight of each raw material and the evaluation results for Examples 1-13 and Comparative Examples 1-4. [Figure 4] Table 2 shows the parts by weight of each raw material and the evaluation results for Examples 1-13 and Comparative Examples 1-4.

Mode for Carrying Out the Invention

[0016] The resin composition according to the first aspect includes a biomass filler containing an inorganic filler derived from biomass and a thermoplastic resin.

[0017] The resin composition according to the second aspect may further include an additive containing a maleic anhydride structure in the first aspect.

[0018] The resin composition according to the third aspect has a chemical bond formed between the polymer chains of the thermoplastic resin in the first or second aspect, and a part of the chemical bond may be hydrophilic.

[0019] [[ID=1​​​​​​​​​​​​​​​​​​​​​​​In the resin composition according to the tenth embodiment, the polyamide may be at least one selected from the group consisting of nylon 6, nylon 66, a polyamide polymer of sebaciac acid and metaxylylenediamine, a polyamide polymer of sebaciac acid, metaxylylenediamine and paraxylylenediamine, a polyamide polymer of sebaciac acid, paraxylylenediamine and paraxylylenediamine, and polymetaxylylene adipamide.

[0026] A method for producing a resin composition according to the eleventh embodiment includes a step of stirring and kneading a powder mixture of a thermoplastic resin and a biomass filler containing an inorganic filler derived from biomass while heating and melting it.

[0027] A method for producing a resin composition according to the 12th embodiment includes the steps of: mixing a thermoplastic resin, a biomass filler containing an inorganic filler derived from biomass, and a maleic anhydride structure-containing additive to obtain a powder mixture; and stirring and kneading the powder mixture while heating and melting it.

[0028] The resin compositions and methods for producing the same according to embodiments of this disclosure will be described in detail below.

[0029] (Embodiment 1) <Resin composition> The resin composition according to Embodiment 1 comprises a biomass filler containing an inorganic filler derived from biomass, and a thermoplastic resin. It may also contain a maleic anhydride structure-containing additive. In the resin composition according to Embodiment 1, for example, terminal functional groups or a part of the skeletal structure of the thermoplastic resin react with the active site generated by ring-opening of the maleic anhydride structure. This causes the thermoplastic resin to bond with the maleic anhydride structure-containing material. Furthermore, a part of the ring-opened structure of the maleic anhydride structure interacts with the biomass filler, allowing for the incorporation of a cross-linked structure. This strengthens the interaction between the thermoplastic resin portion and the biomass filler, resulting in the stable dispersion of the biomass filler within the resin composition. As a result, a high-strength resin composition with fewer defects that could trigger fracture can be obtained.

[0030] <Raw materials> <Thermoplastic resin> The thermoplastic resin is not limited to any particular type; it should deform upon thermal melting by heating and be able to be mixed with the biomass filler. It may also be a mixture of multiple thermoplastic resins. Examples of thermoplastic resins include polyethylene, polyvinyl chloride, polypropylene, polystyrene, acrylonitrile butadiene styrene, acrylonitrile styrene, polymethyl methacrylate, polybutylene terephthalate, polyethylene terephthalate, polyamide, polyoxymethylene, polyvinyl alcohol, polyphenylene ether, polycarbonate, polyphenylene sulfide, aromatic polyether ketone, polyimide, polyamide polymer of sebaciac acid and metaxylylenediamine, polyamide polymer of sebaciac acid, metaxylylenediamine and paraxylylenediamine, poly(metaxylylene adipamide), etc. In particular, due to its ease of thermal melting during manufacturing and thermal stability during use, it is preferable that its softening temperature is between 150°C and 250°C.

[0031] Furthermore, it is preferable that the thermoplastic resin has reactivity with the chemically active site generated by ring-opening of maleic anhydride. From this viewpoint, it is preferable that it has amino groups, hydroxyl groups, carboxyl groups, thiol groups, or ester structures, amide structures, urea structures, amine structures, or cyano structures. From the above viewpoint, polyamides and polyesters are particularly preferred as thermoplastic resins. Particularly preferred specific examples include the polyamides nylon 6, nylon 66, and poly(metaxylylene adipamide). Also, from the viewpoint that the thermoplastic resin itself contains naturally derived sebacic acid as a raw material, examples include polyamide polymers of sebacic acid and metaxylenediamine, polyamide polymers of sebacic acid, metaxylenediamine and paraxylenediamine, and polyamide polymers of sebacic acid, paraxylenediamine and paraxylenediamine. Moreover, as a polyamide, it is preferable to select one with a high glass transition temperature, as this can suppress the decrease in strength under high-temperature environments. Specifically, those with a glass transition temperature exceeding 50°C are preferred. Therefore, polyamide polymers of sebaciac acid and metaxylylenediamine, polyamide polymers of sebaciac acid, metaxylylenediamine and paraxylylenemine, sebaciac acid, paraxylylenediamine and paraxylylenemine, and poly(metaxylylene adipamide) can be suitably used because their glass transition temperatures are 60°C, 63°C, 73°C, 75°C, and 85°C, respectively. Among these, poly(metaxylylene adipamide) can be particularly suitably used from the viewpoint of having a glass transition temperature exceeding 80°C.

[0032] <Biomass Filler> The biomass filler is not limited to any specific type, and for example, the following known naturally derived materials can be used. Specifically, calcium carbonate powder obtained by crushing shellfish such as scallops, surf clams, and oysters, coral shells, or eggshells, or calcium oxide powder obtained by calcining and crushing these materials can be used.

[0033] Furthermore, the longest part length of a single particle of these biomass filler powders can be, for example, approximately 50 nm to 500 μm. If it is smaller than 50 nm, aggregation becomes severe, making dispersion difficult during heating, melting, and kneading. If it is larger than 500 μm, it is prone to clogging in the mold channels during molding, reducing fluidity and making molding difficult. From the viewpoint of achieving both suppression of aggregation and suppression of fluidity reduction, a length of 100 nm to 100 μm is preferable. In addition, the biomass filler may be pre-coated with fatty acids, resin acids, cationic surfactants, lignin, etc. If it is coated, it is preferable from the viewpoint of improving compatibility with the thermoplastic resin mentioned above and facilitating uniform dispersion.

[0034] The amount of biomass filler added can be between 20% and 90% by weight. If it is less than 20% by weight, the effect of increasing strength cannot be sufficiently achieved, and if it is greater than 90% by weight, the ratio of resin components becomes too low, which is undesirable as it causes a decrease in fluidity due to aggregation of biomass fillers. From the viewpoint of ensuring high strength and fluidity, an amount of 40% to 60% by weight is even more preferable.

[0035] Furthermore, the biomass filler may be surface-treated as appropriate. Taking a commonly used silane coupling agent as an example of a surface treatment agent, ordinary calcium carbonate does not have hydroxyl groups that react with the silanol groups produced by the hydrolysis of the alkoxy groups of the silane coupling agent. In contrast, by using a biomass filler, the hydroxyl groups present in proteins such as conchiolin contained as impurities, or in the chitin that forms the outer shell, can react with the silanol groups produced by the hydrolysis of the alkoxy groups of the silane coupling agent through dehydration condensation. As a result, a resin composition with higher strength can be obtained than when an untreated biomass filler is used.

[0036] Furthermore, the organic components of the biomass filler, such as conchiolin and chitin, can react with the terminal structure of the composite resin. For example, if the resin is a polyamide, the terminal carboxyl groups and amino groups can react with the polyamide, potentially improving the strength compared to when ordinary calcium carbonate is used.

[0037] Compared to calcium carbonate obtained by conventional inorganic synthesis, biomass fillers contain carboxyl and amino groups derived from proteins, as described above. Therefore, when atomic absorption spectrometry is performed, carbon and nitrogen derived from these functional groups are detected. In particular, in the case of biomass fillers obtained from scallop shells, the cross-section forms an inner layer with a leaf-like structure, an intermediate layer with a cross-lamellar structure, and an outer layer, and such layered structures can sometimes be observed in biomass fillers. The protein described above has a structure in which columnar calcium carbonate crystals of calcite, which constitute the inner layer, are arranged, and the protein is continuously inserted between these crystals.

[0038] Furthermore, when the biomass filler is eggshell, it contains a cuticle layer made of polysaccharides that covered the outside of the egg, pores, outer eggshell membrane, inner eggshell membrane, papillary segments adjacent to the outer eggshell membrane, and papillary nuclei at the tips of the papillary segments. A columnar structure of calcium carbonate deposits can be observed starting from the papillary nuclei. Among these, the eggshell membrane is composed of protein, and the amino groups, carboxyl groups, and hydroxyl groups contained in these proteins react with silane coupling agents, thereby treating the surface of the biomass filler.

[0039] <Maleic anhydride structure-containing additive> The maleic anhydride structure-containing additive is not limited to any particular type, as long as it contains at least one maleic anhydride structure per molecule. The maleic anhydride structure undergoes ring-opening, and the open-ring structure reacts with the thermoplastic resin. On the other hand, another maleic anhydride structure contained within the same molecule as the maleic anhydride structure undergoes ring-opening, and since the open-ring structure exhibits hydrophilicity, it readily interacts with calcium carbonate, the main component of the biomass filler. As a result, the wettability between the biomass filler and the resin improves, and dispersion becomes easier. Furthermore, if the thermoplastic resin is a polyamide, the amino group at the end of the polyamide polymer chain undergoes ring-opening of the maleic anhydride, and the open-ring structure reacts with the carboxyl group at the end of another polymer chain, forming a cross-linked structure between polymer chains, which enables the resin composition to be strengthened. Examples of maleic anhydride structure-containing materials that function in this way include maleic anhydride-styrene copolymer, maleic anhydride-vinyl acetate copolymer, maleic anhydride-vinyl benzoate copolymer, poly(ethylene-alt-maleic anhydride), polypropylene-graft-maleic anhydride, poly(isobutylene-alt-maleic anhydride), poly(methyl vinyl ether-alt-maleic anhydride), polystyrene-block-poly(ethylene-lan-butylene)-block-polystyrene-graft-maleic anhydride, (-)-2,3-bis[(2R,5R)-2,5-dimethylphosphoranone]maleic anhydride, citraconic anhydride, and cyclobutane-1,2,3,4-tetracarboxylic dianhydride.

[0040] Furthermore, the amount of maleic anhydride structure-containing material added can be 0.5% by weight or more and 7% by weight or less of the total weight of the resin composition. If the amount is less than 0.5% by weight, a sufficient effect on improving the strength as described above cannot be obtained. On the other hand, if the amount is more than 7% by weight, a large amount of maleic anhydride structure will be included that does not form a ring-open structure and does not react with some of the organic fiber filler or thermoplastic resin, resulting in a non-functional foreign substance that can act as a starting point for cracking, which is undesirable. Moreover, from the viewpoint of ensuring that the maleic anhydride structure reacts with the thermoplastic resin without excess or deficiency, and that its ring-open structure contributes to improved interaction with the biomass filler, an amount of 1.25% by weight or more and 5% by weight or less is even more preferable.

[0041] <Method for producing resin compositions> The method for producing the resin composition according to Embodiment 1 includes the step of heating and melting a powder mixture of a thermoplastic resin and a biomass filler containing an inorganic filler derived from biomass, while stirring and kneading. Furthermore, the method for producing the resin composition according to another example includes the step of mixing a thermoplastic resin, a biomass filler containing an inorganic filler derived from biomass, and a maleic anhydride structure-containing additive to obtain a powder mixture, and the step of heating and melting the powder mixture, while stirring and kneading.

[0042] The following describes the process of obtaining a powder mixture and the process of heating and melting the powder mixture while stirring and kneading to obtain a resin composition.

[0043] <Process for obtaining the powder mixture> A powder mixture can be obtained by mixing a thermoplastic resin with a biomass filler containing biomass-derived inorganic fillers. In another example, a powder mixture can be obtained by mixing a thermoplastic resin with a biomass filler containing biomass-derived inorganic fillers and a maleic anhydride structure-containing additive. First, to mix the materials, the raw materials of each composition may be weighed into containers or bags and mixed manually using a spatula or a rod-shaped jig that can be used for stirring. Alternatively, a rotary mixer, such as a Henschel mixer, may be used to mix the materials almost uniformly. From the viewpoint of ease of the above mixing process, the thermoplastic resin and maleic acid structure-containing material are preferably in powder or pellet form.

[0044] <Heating, melting, stirring, and kneading process of powder mixture> To heat, melt, and knead the powder mixture, the substantially uniformly mixed powder mixture can be processed using a single-screw kneader, twin-screw kneader, roll kneader, kneader, Banbury mixer, etc. Furthermore, a combination of these methods can be used for both heating, melting, and kneading. After heating, melting, and kneading, the mixture can be cooled to a temperature at which pulverization is possible to obtain a resin composition. Additionally, other additives such as pigments and flame retardants can be added to the mixture during heating, melting, and kneading, depending on the application.

[0045] According to the method for producing the resin composition of Embodiment 1, in the heating and melting step, the active site generated by the ring-opening of the maleic anhydride structure reacts with, for example, terminal functional groups or a part of the skeletal structure of the thermoplastic resin, thereby bonding the resin and the maleic anhydride structure-containing material. Furthermore, a part of the ring-opened structure of the maleic anhydride structure interacts with the biomass filler, strengthening the interaction between the thermoplastic resin portion and the biomass filler, resulting in the stable dispersion of the biomass filler in the resin composition. As a result, a high-strength resin composition with fewer defects that trigger fracture can be obtained.

[0046] When the resin composition produced in this way is molded and applied, for example, to industrial parts, the biomass content is higher than that of conventional resin molded articles due to the inclusion of biomass fillers, contributing to a reduction in environmental impact. At the same time, the biomass fillers and thermoplastic resin interact through hydrophilic functional groups generated by the ring-opening structure of the maleic anhydride, resulting in high strength. This allows for the creation of an excellent molded article that achieves both environmental friendliness and high strength.

[0047] The following describes specific examples.

[0048] (Example 1) (1) As a thermoplastic resin, 60 parts by weight of poly(metaxylylene adipamide) (Mitsubishi Gas Chemical Co., Ltd., Nylon MXD6, hereinafter referred to as Nylon MXD6), a type of polyamide, and as a biomass filler, 40 parts by weight of scallop biomass filler (Tomoe Kogyo Co., Ltd. (Scallop Biomass Filler K)), which is made by dry-pulverizing scallop shells, were prepared. (2) These were placed into a polyethylene bag and the bag was shaken by hand for 5 minutes to mix them. (3) The mixture was then sequentially added to the hopper of a twin-screw kneader set to 260°C, and heated, melted, and kneaded while being extruded at a shaft rotation speed of 100 rpm. The molten mixture was then collected from the discharge port to obtain the resin composition of this embodiment.

[0049] The resin composition in this Example 1 was injection molded. The resin composition was crushed in a pulverizer to obtain a powder, and then dumbbell test specimens of the resin composition were prepared using an injection molding machine (Japan Steel Works 180AD) with the prepared powder. The conditions for preparing the dumbbell test specimens were a resin temperature of 240°C, a mold temperature of 80°C, an injection speed of 60 mm / s, and a holding pressure of 100 MPa. For measuring the elastic modulus and elongation at the breaking point, a multi-purpose dumbbell test specimen of JIS K7139 Type A1 was prepared.

[0050] (Example 2) This method is the same as Example 1, except that it uses biomass filler made from dry-milled oyster shells.

[0051] (Example 3) This method is the same as Example 1, except that a biomass filler made from dry-ground eggshells was used as the biomass filler.

[0052] (Comparative Example 1) This is the same as Example 1, except that 40 parts by weight of cellulose fiber (Nippon Paper Industries Co., Ltd. (KC Floc (W-100GK))), an organic fiber filler, was prepared instead of biomass filler.

[0053] (Example 4) (1) As a thermoplastic resin, 70 parts by weight of nylon MXD6, a type of polyamide, and as a biomass filler, 30 parts by weight of scallop biomass filler (Tomoe Kogyo Co., Ltd. (Scallop Biomass Filler K)), which is made by dry-pulverizing scallop shells, were prepared. (2) These were placed in a polyethylene container and mixed by hand using a spatula for 5 minutes. (3) Furthermore, the mixture was sequentially added to the hopper of a twin-screw kneader set to 260°C, and heated, melted, and kneaded while being extruded at a shaft rotation speed of 100 rpm. The molten mixture was then collected from the discharge port to obtain the resin composition of this embodiment.

[0054] The resin composition in this 4th example was injection molded. The resin composition was crushed into a powder using a pulverizer, and then dumbbell-shaped test specimens of the resin composition were prepared using a hand press machine (Imoto Seisakusho) with the prepared powder. The conditions for preparing the dumbbell-shaped test specimens were a resin temperature of 240°C and a mold temperature of 25°C. For measuring the elastic modulus and elongation at the breaking point, scaled-down test specimens of JIS K7139 dumbbell-shaped test specimen A12 were prepared.

[0055] (Example 5) This is the same as Example 4, except that 60 parts by weight of nylon MXD6, a type of polyamide, was prepared as the thermoplastic resin, and 40 parts by weight of scallop biomass filler (Tomoe Kogyo Co., Ltd. (Scallop Biomass Filler K)), which is made by dry-pulverizing scallop shells, was prepared as the biomass filler.

[0056] (Example 6) This is the same as Example 4, except that 50 parts by weight of nylon MXD6, a type of polyamide, was prepared as the thermoplastic resin, and 50 parts by weight of scallop biomass filler (Tomoe Kogyo Co., Ltd. (Scallop Biomass Filler K)), which is made by dry-pulverizing scallop shells, was prepared as the biomass filler.

[0057] (Example 7) This is the same as Example 4, except that 44.6 parts by weight of nylon MXD6, a type of polyamide, was prepared as the thermoplastic resin, and 55.4 parts by weight of scallop biomass filler (Tomoe Kogyo Co., Ltd. (Scallop Biomass Filler K)), which is made by dry-pulverizing scallop shells, was prepared as the biomass filler.

[0058] (Example 8) As a thermoplastic resin, 58.25 parts by weight of nylon MXD6, a type of polyamide, was prepared; as a biomass filler, 40 parts by weight of scallop biomass filler (Tomoe Kogyo Co., Ltd. (Scallop Biomass Filler K)), which is made from dry-ground scallop shells, was prepared; and as a maleic anhydride structure-containing additive, 1.75 parts by weight of polypropylene-graft-maleic anhydride was prepared. These were placed in a single polyethylene container and stirred and mixed manually for 5 minutes using a spatula, except that the procedure was the same as in Example 4.

[0059] (Example 9) As a thermoplastic resin, 57 parts by weight of nylon MXD6, a type of polyamide, was prepared; as a biomass filler, 40 parts by weight of scallop biomass filler (Tomoe Kogyo Co., Ltd. (Scallop Biomass Filler K)), which is made by dry-grinding scallop shells, was prepared; and as a maleic anhydride structure-containing additive, 3 parts by weight of polypropylene-graft-maleic anhydride was prepared. These were placed in a single polyethylene container and stirred and mixed manually for 5 minutes using a spatula, except that the procedure was the same as in Example 4.

[0060] (Example 10) As a thermoplastic resin, 57 parts by weight of nylon 6, a type of polyamide, was prepared; as a biomass filler, 40 parts by weight of scallop biomass filler (Tomoe Kogyo Co., Ltd. (Scallop Biomass Filler K)), which is made by dry-pulverizing scallop shells, was prepared; and as a maleic anhydride structure-containing additive, 3 parts by weight of polypropylene-graft-maleic anhydride was prepared. These were placed in a single polyethylene container and stirred and mixed manually for 5 minutes using a spatula, except that the procedure was the same as in Example 4.

[0061] Figure 1 shows the AFM image of the resin composition in Example 10. Figure 2 shows the AFM-IR measurement spectrum of the resin composition in Example 10. In Example 10, molecular structure analysis of the resin composition was performed. AFM-IR measurement was used to analyze the molecular structure of the resin composition. While observing the resin composition fragments, which had been thinned using a microtome for TEM observation, with an optical microscope, an observation spot was determined, and the structure in the nanoscale region was analyzed by measuring the reflectance of the AFM image and infrared absorption spectrum at that spot. An example of an AFM image from Example 10 is shown in Figure 1. An example of a spectrum obtained by AFM-IR measurement is shown in Figure 2. First, in the AFM image, the boundary between the maleic anhydride structure-containing additive and the resin is unclear, indicating that the maleic anhydride structure-containing additive is chemically reacting. Furthermore, Figure 2 shows that a peak of carbonyl group not derived from the raw material resin, polyamide, can be observed in the resin phase. These characteristics are formed by the following mechanism. Specifically, during the heating, melting, and kneading processes, the ring-opening of the maleic anhydride structure in polypropylene-graft-maleic anhydride reacts with the amino group at the polyamide terminal, and the carboxyl group generated by the ring-opening improves the hydrophilicity of the resin portion. This resin portion with improved hydrophilicity has high wettability with calcium carbonate, the main component of biomass filler, and disperses the biomass filler well within the resin portion, resulting in a high-strength resin composition with few defects. In addition, the polymer chains of the polyamide also bond together, resulting in the effect of increasing the strength of the resin portion itself.

[0062] (Example 11) This is the same as Example 4, except that 60 parts by weight of nylon 6, a type of polyamide, was prepared as the thermoplastic resin, and 40 parts by weight of scallop biomass filler (Tomoe Kogyo Co., Ltd. (Scallop Biomass Filler K)), which is made by dry-pulverizing scallop shells, was prepared as the biomass filler.

[0063] (Example 12) This is the same as Example 4, except that 44.5 parts by weight of nylon 6, a type of polyamide, was prepared as the thermoplastic resin, and 55.5 parts by weight of scallop biomass filler (Tomoe Kogyo Co., Ltd. (Scallop Biomass Filler K)), which is made by dry-pulverizing scallop shells, was prepared as the biomass filler.

[0064] (Comparative Example 2) This is the same as Example 4, except that 40 parts by weight of cellulose fiber (Nippon Paper Industries Co., Ltd. (KC Floc (W-100GK))), an organic fiber filler, was prepared instead of biomass filler.

[0065] (Comparative Example 3) This example is the same as Example 11, except that 40 parts by weight of calcium carbonate were prepared instead of biomass filler.

[0066] (Example 13) The biomass filler is the same as in Example 5, except that 40 parts by weight of scallop biomass filler (Tomoe Kogyo Co., Ltd. (Scallop Biomass Filler K)), which is made by dry-pulverizing scallop shells, is treated with 0.5 parts by weight of 3-glycidoxypropyltrimethoxylan, a type of silane coupling agent. When surface-treating scallop biomass filler k with 3-glycidoxypropyl trimethoxylan, the following procedure was followed.

[0067] <Manufacturing of surface-treated biomass fillers> In this example, the surface treatment of the surface-treated biomass filler was carried out with 3-glycidoxypropyltrimethoxylan using the following method. (a) 40 parts by weight of scallop biomass filler (Tomoe Kogyo Co., Ltd. (Scallop Biomass Filler K)), which is obtained by dry-pulverizing scallop shells, was prepared as a biomass filler, and 0.5 parts by weight of 3-glycidoxypropyltrimethoxysilane (Shin-Etsu Chemical Co., Ltd. KBM403) was prepared as an epoxy group-containing alkoxysilane as a surface treatment agent. (b) Cellulose fiber was placed in a Henschel mixer, and 3-glycidoxypropyltrimethoxysilane was added to a syringe. (c) While stirring the cellulose fibers in the Henschel mixer at a rotation speed of 1000 rpm, the needle of a syringe was inserted through the syringe hole provided in the lid of the Henschel mixer, and 3-glycidoxypropyltrimethoxysilane was injected into the interior. After injection, rotation was continued for another 10 minutes, and after rotation was stopped, the epoxy-surface-modified biomass filler, i.e., epoxy-surface-modified scallop biomass filler in this example, was recovered from the Henschel mixer.

[0068] (Comparative Example 4) This is the same as Example 9, except that 40 parts by weight of calcium carbonate were prepared instead of biomass filler.

[0069] (Evaluation of elastic modulus) The obtained dumbbell specimens were subjected to a three-point bending test. In the three-point bending test, The modulus of elasticity is determined from the amount of strain and the slope of the bending stress. The elongation at the fracture point is the amount of strain that occurs before failure. The following were used as evaluation criteria. The evaluation of each criterion was as follows:

[0070] (Bending strength) For Examples 1, 2, 3 and Comparative Example 1, evaluated using JIS K7139 dumbbell-shaped test specimens, Type A1, specimens with a bending strength of 150 MPa or higher were marked with ◎ for particularly high strength, specimens with a bending strength of 140 MPa or higher but less than 150 MPa were marked with ○ for high strength, and specimens with a bending strength of less than 140 MPa were marked with △ for insufficient strength.

[0071] The parts by weight of each raw material and the evaluation results for each of Examples 1-13 and Comparative Examples 1-4 are shown in Table 1 of Figure 3 and Table 2 of Figure 4. The results from each example show that polyamides containing biomass fillers form resin compositions with excellent strength and colorability. Furthermore, a comparison of the examples and comparative examples shows that the product containing biomass filler exhibits superior colorability compared to the product containing organic fiber filler. A comparison of Example 11 with Comparative Example 2 shows that the material containing biomass filler has superior strength compared to the material containing organic fiber filler at the same volume. A comparison of Example 5 with Examples 8 and 9 shows that the material with the maleic anhydride structure-containing additive added has superior strength compared to the material without the additive.

[0072] The results from Examples 4, 5, 6, 10, and 11 show that a biomass filler content of at least 30% by weight and 55.5% by weight can suitably impart strength and colorability to the resin composition. A comparison of Example 11 and Comparative Example 3 shows that using biomass filler as the filler improves the strength.

[0073] A comparison of Example 9 and Example 13 shows that when a maleic anhydride structure-containing material is added and a surface-treated biomass filler is incorporated, the strength is further improved. A comparison of Example 9 and Comparative Example 4 shows that when a maleic anhydride structure-containing material is added, using a biomass filler improves the strength. [Industrial applicability]

[0074] As described above, the resin composition according to this embodiment has excellent strength and colorability and can be applied to a variety of industrial products that are in harmony with the environment.

Claims

1. Biomass filler containing biomass-derived inorganic fillers, Thermoplastic resin and A resin composition containing the following:

2. Furthermore, the resin composition according to claim 1 further comprises a maleic anhydride structure-containing additive.

3. The resin composition according to claim 1 or 2, wherein the thermoplastic resin has chemical bonds formed between polymer chains, and a portion of the chemical bonds is hydrophilic.

4. The resin composition according to claim 3, wherein the chemical bond comprises a carbonyl group.

5. The resin composition according to claim 4, wherein the carbonyl group is derived from a reaction induced by ring-opening of the maleic anhydride structure.

6. The resin composition according to claim 1, wherein the inorganic filler is calcium carbonate derived from seashells or eggshells.

7. The resin composition according to claim 6, wherein the seashell is a scallop or an oyster.

8. The resin composition according to claim 6, wherein the calcium carbonate content is 20% by weight or more and 70% by weight or less.

9. The resin composition according to claim 1, wherein the thermoplastic resin is a polyamide.

10. The resin composition according to claim 9, wherein the polyamide is at least one selected from the group consisting of nylon 6, nylon 66, a polyamide polymer of sebaciac acid and metaxylylenediamine, a polyamide polymer of sebaciac acid, metaxylylenediamine and paraxylylenediamine, a polyamide polymer of sebaciac acid, paraxylylenediamine and paraxylylenediamine, and polymetaxylylene adipamide.

11. The process includes heating and melting a powder mixture of thermoplastic resin and biomass filler containing biomass-derived inorganic fillers, while stirring and kneading the mixture. A method for producing a resin composition.

12. A process of mixing a thermoplastic resin, a biomass filler containing biomass-derived inorganic fillers, and a maleic anhydride structure-containing additive to obtain a powder mixture, The process involves heating and melting the aforementioned powder mixture while stirring and kneading it, A method for producing a resin composition containing [the specified element].

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