Composite resin composition containing plant fillers and composite resin molded articles using the plant filler-containing composite resin composition

Abstract

This plant filler-containing composite resin composition comprises a main agent resin, a plant filler dispersed in the main agent resin, and a dispersant dispersed in the main agent resin. 50-97 mass% of the plant filler is a first plant filler containing less than 1 mass% triacylglycerol, and 3-50 mass% of the plant filler is a second plant filler containing 1-40 mass% triacylglycerol. The main agent resin is a crystalline resin.

Description

Technical Field

[0001] The present disclosure relates to a composite resin composition containing a plant filler and a molded article using the composite resin composition containing the plant filler. In particular, it relates to a composite resin composition containing a plant filler at a high concentration.

Background Art

[0002] So-called "general-purpose plastics" such as polyethylene (PE), polypropylene (PP), polystyrene (PS), and polyvinyl chloride (PVC) are relatively inexpensive, have a weight that is a fraction of that of metals or ceramics, and are easy to process such as molding. Therefore, general-purpose plastics are used as materials for various daily necessities such as bags, various packages, various containers, and sheets, as well as industrial parts such as automotive parts and electrical parts, and daily necessities and miscellaneous goods.

[0003] However, general-purpose plastics have drawbacks such as insufficient mechanical strength. Therefore, general-purpose plastics do not have sufficient properties required for materials used in various industrial products including mechanical products such as automobiles and electrical, electronic, and information products, and their scope of application is currently limited.

[0004] On the other hand, so-called "engineering plastics" such as polyacetal (POM), polyamide (PA), polycarbonate (PC), and fluororesin have excellent mechanical properties and are used in various industrial products including mechanical products such as automobiles and electrical, electronic, and information products. However, engineering plastics have problems such as being expensive, difficult to monomer recycle, and having a large environmental load.

[0005] Therefore, there is a demand for a significant improvement in the material properties (mechanical strength, etc.) of general-purpose plastics. One known method for improving the material properties of general-purpose plastics is to manufacture composite resins by blending two or more types of resins or additives such as fillers. In particular, fibrous fillers such as natural fibers, glass fibers, and carbon fibers are used with the aim of improving mechanical strength. Among these, organic fibrous fillers such as cellulose have attracted attention in recent years as reinforcing fibers because they are inexpensive and have excellent environmental impact when disposed of.

[0006] One application of composite resins is in components such as home appliance casings and automotive interior and exterior parts. Molding methods used to produce these components include injection molding and extrusion molding. While these molding methods allow for high-cycle production, the materials used must have high fluidity. However, as the amount of filler added increases, the mechanical strength, such as the elastic modulus, of the composite resin increases, while fluidity decreases. Therefore, composite resins with high concentrations of filler have low fluidity and are difficult to mold. Patent Document 1 describes how fluidity and moldability are improved by adding an ester-based plasticizer to a high-concentration filler composite resin. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2002-53758 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] A composite resin composition containing a plant filler according to one aspect of the present disclosure comprises a main resin, a plant filler dispersed in the main resin, and a dispersant dispersed in the main resin, wherein 50% to 97% by mass of the plant filler is a first plant filler containing less than 1% by mass of triacylglycerol, and 3% to 50% by mass of the plant filler is a second plant filler containing 1% to 40% by mass of triacylglycerol, and the main resin is a crystalline resin. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic diagram of a plant filler-containing composite resin composition according to Embodiment 1. [Figure 2] This figure shows the conditions and measurement results for Examples 1-4 and Comparative Examples 1-5. [Modes for carrying out the invention]

[0010] The composite resin described in Patent Document 1 uses an ester-based plasticizer, but because the plasticizer has significantly lower strength on its own compared to the main resin and filler, it presents the problem of reducing the mechanical strength, such as the elastic modulus, of the composite resin. In addition, because the plasticizer is a low molecular weight, there is also the problem of bleed-out, that is, the plasticizer additive rising to the surface of the pellet or molded product.

[0011] This disclosure aims to provide a plant filler composite resin that has high fluidity and high mechanical strength without the need to add plasticizers separately.

[0012] The first embodiment of the plant filler-containing composite resin composition comprises a main resin, a plant filler dispersed in the main resin, and a dispersant dispersed in the main resin, wherein 50% to 97% by mass of the plant filler is a first plant filler containing less than 1% by mass of triacylglycerol, and 3% to 50% by mass of the plant filler is a second plant filler containing 1% to 40% by mass of triacylglycerol, and the main resin is a crystalline resin.

[0013] In the second embodiment, the plant filler-containing composite resin composition may contain 50% by mass or more and 90% by mass or less when the total amount of the main resin, plant filler, and dispersant in the plant filler-containing composite resin composition is set to 100% by mass.

[0014] In the third embodiment, the plant filler-containing composite resin composition may, in the first or second embodiment, have a total amount of cellulose, hemicellulose, and lignin of 5% by mass or more and 50% by mass or less.

[0015] In the fourth embodiment, the plant filler-containing composite resin composition may, in any of the first to third embodiments described above, have a total amount of cellulose, hemicellulose, and lignin of 80% by mass or more of the first plant filler.

[0016] In the fifth embodiment, the plant filler-containing composite resin composition may have an average particle size of 100 nm or more and 3 mm or less of the plant filler, as described in any of the first to fourth embodiments.

[0017] In the sixth embodiment, the plant filler-containing composite resin composition may have a crystallinity of 30% or more of the main resin in any of the first to fifth embodiments described above.

[0018] The plant filler-containing composite resin composition according to the seventh embodiment, in any of the first to sixth embodiments, comprises a main resin including a first region around the plant filler and a second region away from the plant filler, wherein the degree of crystallinity of the main resin in the first region is 1.05 times or more than the degree of crystallinity of the main resin in the second region.

[0019] The composite resin molded article according to the eighth embodiment includes a plant filler-containing composite resin composition according to any of the first to seventh embodiments described above.

[0020] The plant filler-containing composite resin composition according to this disclosure contains 3% to 50% by mass of a second plant filler containing 1% to 40% by mass of triacylglycerol, relative to the total amount of plant filler. It also contains 50% to 97% by mass of a first plant filler containing less than 1% by mass of triacylglycerol. As a result, it can achieve high strength while maintaining high fluidity, and can be applied to high-cycle, high-volume molding methods such as injection molding and extrusion molding. Furthermore, because a crystalline resin is used as the main resin, the degree of crystallinity around the plant filler and the crystallinity of the entire resin are high, which can suppress the bleed-out of triacylglycerol. As a result, it can be used without problems as a molded article.

[0021] The plant filler-containing composite resin composition and its molded article in the embodiment will be described below with reference to the attached drawings. In the following description, the same reference numerals are used for the same components, and their descriptions are omitted as appropriate.

[0022] (Embodiment 1) The plant filler-containing composite resin composition 10 according to Embodiment 1 includes a main resin 1, a first plant filler 2 represented as a long black string in FIG. 1, a second plant filler 3 represented as an ellipse in FIG. 1, a triacylglycerol 4 represented as a rectangle in FIG. 1, and a dispersant 5 represented as a triangle in FIG. 1. The main resin 1 includes a matrix of an amorphous portion 11 and a crystalline portion 12. As shown in FIG. 1, in the plant filler-containing composite resin composition 10, the first plant filler 2, the second plant filler 3, the triacylglycerol 4, and the dispersant 5 are dispersed in the matrix of the main resin 1. The triacylglycerol 4 may be present on the surface or inside of the second plant filler 3, on the surface of the first plant filler 2, or in the matrix of the main resin 1, etc. The dispersant 5 may be present at the interface between the first plant filler 2 or the second plant filler 3 and the main resin 1, etc. In the first plant filler 2, 50% by mass or more and 97% by mass or less of the first and second plant fillers 2 and 3 contain less than 1% by mass of triacylglycerol. In the second plant filler 3, 3% by mass or more and 50% by mass or less of the first and second plant fillers 2 and 3 contain 1% by mass or more and 40% by mass or less of triacylglycerol 4. Further, the main resin 1 is a crystalline resin.

[0023] The plant filler-containing composite resin composition 10 according to Embodiment 1 contains 3% by mass or more and 50% by mass or less of the second plant filler 3 containing 1% by mass or more and 40% by mass or less of triacylglycerol 4 with respect to the total amount of the first and second plant fillers 2 and 3. Further, it contains 50% by mass or more and 97% by mass or less of the first plant filler 2 containing less than 1% by mass of triacylglycerol 4. Therefore, the plant filler-containing composite resin composition 10 can have high fluidity while having high strength, and can be applied to high-cycle and highly productive molding methods such as injection molding and extrusion molding. Further, since a crystalline resin is used for the main resin 1, the crystallinity around the first and second plant fillers 2 and 3 and the crystallinity of the entire resin increase, and the bleed-out of triacylglycerol 4 can be suppressed. Therefore, it can be used without problems as a molded body.

[0024] The following describes each component constituting this plant filler-containing composite resin composition.

[0025] <Base resin> As the base resin 1 in the embodiment, it is preferably a crystalline resin in order to suppress the bleed-out of triacyl glycerol, and more preferably a thermoplastic resin in order to ensure good moldability. Examples of the crystalline resin include olefin resins (including cyclic olefin resins), polyamide resins, polyphenylene ether resins (such as polymers of 2,6-xylenol), crystalline polyester resins, halogen-containing resins, liquid crystal polymer resins, and the like. The above resins may be used alone or in combination of two or more. Note that the resin is not limited to the above materials as long as it has crystallinity. Also, when using two or more resins, at least one resin needs to have crystallinity.

[0026] Among these crystalline resins, the base resin is preferably an olefin resin with a relatively low melting point. The olefin resin includes not only homopolymers of olefin monomers but also copolymers of olefin monomers and copolymers of olefin monomers and other copolymerizable monomers. Examples of the olefin monomer include linear olefins (such as α-C2-20 olefins like ethylene, propylene, 1-butene, isobutene, 1-pentene, 4-methyl-1-pentene, 1-octene, etc.) and cyclic olefins. These olefin monomers may be used alone or in combination of two or more. Among the above olefin monomers, linear olefins such as ethylene and propylene are preferred. Specific examples of the olefin resin include copolymers of linear olefins (especially α-C2-4 olefins) such as polyethylene (low density, medium density, high density or linear low density polyethylene, etc.), polypropylene, ethylene-propylene copolymer, and terpolymers such as ethylene-propylene-butene-1.

[0027] The main resin 1 is preferably a crystalline resin. The crystalline portion 12 has a denser structure than the amorphous portion 11. Therefore, the diffusion rate of liquids and gases is significantly lower in the crystalline portion 12 compared to the amorphous portion 11. Since triacylglycerol diffuses in the composite resin as a liquid component, the diffusion rate is greatly reduced in the crystalline portion 12 compared to the amorphous portion 11. The presence of the crystalline portion 12 in the resin reduces the diffusion rate of liquids, thereby suppressing the bleed-out of triacylglycerol from the composite resin composition. For this reason, the main resin 1 is preferably a crystalline resin.

[0028] The crystallinity of the main resin 1 is preferably 30% or higher, and more preferably 60% or higher. If the crystallinity of the main resin 1 is less than 30%, the proportion of amorphous parts is large, and therefore the bleed-out of triacylglycerol cannot be suppressed very well. For this reason, it is preferable that the crystallinity of the main resin 1 be within the above range.

[0029] The main resin 1 may include a first region around the plant filler and a second region away from the plant filler. Preferably, the crystallinity of the main resin 1 in the first region is 1.05 times or more, and more preferably 1.10 times or more, than the crystallinity of the main resin 1 in the second region. If the crystallinity of the main resin in the first region is too low, the resin around the plant filler cannot form a dense structure. In other words, triacylglycerol cannot be maintained around the plant filler, and bleed-out to the composite resin surface cannot be suppressed. Therefore, it is preferable that the crystallinity of the main resin 1 in the first region is within the above range compared to the crystallinity of the main resin 1 in the second region.

[0030] <First plant filler> Examples of raw materials for the first plant filler 2 containing less than a certain amount of triacylglycerol in the embodiment include natural materials such as pulp, wood (coniferous trees, hardwoods), cotton linters, kenaf, Manila hemp (abaca), sisal hemp, jute, sabagrass, esparto grass, and bagasse. Alternatively, natural materials modified with functional monomers containing acids, amines, epoxy, etc., may also be used. The first plant filler 2 is preferably in the form of fibers or particles obtained by crushing the above natural materials.

[0031] The total amount of cellulose, hemicellulose, and lignin in the first plant filler 2, which contains less than 1% by mass of triacylglycerol, is preferably 80% by mass or more, and more preferably 90% or more. Cellulose, hemicellulose, and lignin are components that form the skeleton of plants, and the strength of the plant largely depends on the amounts of these three components. If the total amount of cellulose, hemicellulose, and lignin in the first plant filler 2 is less than 80% by mass, the strength of the first plant filler will be low, and therefore the strength of the composite resin will also be low. For this reason, it is preferable that the total amount of cellulose, hemicellulose, and lignin in the first plant filler 2 be within the above range.

[0032] <Second plant filler> In this embodiment, the raw materials for the second plant filler 3 containing a certain amount or more of triacylglycerol include natural materials such as beans, wheat, barley, rice, and coffee beans. From an environmental and cost perspective, plant waste materials that are discarded after commercial use, such as coffee grounds after coffee extraction, may also be used. The second plant filler 3 is preferably in the form of fibers or particles obtained by crushing the above materials.

[0033] The second plant filler 3 preferably has a triacylglycerol content of 1% by mass or more and 40% by mass or less, and more preferably 3% by mass or more and 30% by mass or less. If the triacylglycerol content is less than 1% by mass, the amount of triacylglycerol is too small, and the fluidity of the composite resin composition cannot be improved. If the triacylglycerol content is greater than 40% by mass, the amount of triacylglycerol, which has low strength properties, is too large, and the strength properties of the plant filler decrease, resulting in a significant decrease in the mechanical strength of the plant filler-containing composite resin composition. For this reason, the second plant filler 3 preferably has a triacylglycerol content of 1% by mass or more and 40% by mass or less, and more preferably 3% by mass or more and 30% by mass or less.

[0034] The amount of the second plant filler 3 is preferably 3% by mass or more and 50% by mass or less, and more preferably 5% by mass or more and 30% by mass or less, relative to the total amount of the first plant filler 2 and the second plant filler 3. If the amount of the second plant filler 3 is less than 3% by mass relative to the total amount of plant fillers, the amount of triacylglycerol becomes too small, and the fluidity cannot be sufficiently improved. If it is greater than 50% by mass, the amount of the second plant filler 3, which is weaker in strength than the first plant filler 2, is large, so the reinforcing effect of the plant fillers is reduced, and the mechanical strength of the composite resin composition decreases. For this reason, the amount of the second plant filler 3 is preferably 3% by mass or more and 50% by mass or less, and more preferably 5% by mass or more and 30% by mass or less, relative to the total amount of the first plant filler 2 and the second plant filler 3.

[0035] The combined amount of the first and second plant fillers 2 and 3 in the composite resin composition is preferably 50% by mass or more and 90% by mass or less, and more preferably 55% by mass or more and 85% by mass or less. As shown in Figure 1, the composite resin composition according to this embodiment comprises a main resin 1, a first plant filler 2, a second plant filler 3, triacylglycerol 4, and a dispersant 5. The mechanical strength increases as the amount of plant filler added increases. In addition, the bio-level increases as the amount of plant-derived material components increases, which is effective in reducing environmental burden such as carbon neutrality. If the amount of plant filler is less than 50% by mass, the reinforcing effect of the plant filler on the resin decreases, and the mechanical strength of the composite resin decreases. Also, the bio-level decreases, so the effect of reducing environmental burden decreases. If the amount of plant filler is greater than 90% by mass, the amount of resin is too small, so the fluidity of the composite resin decreases significantly, and mixing and molding cannot be carried out stably. Furthermore, if the amount of resin is too small compared to the amount of plant filler, the first plant filler 2 and the second plant filler 3 cannot be encapsulated in the main resin 1, and a large amount of the first and second plant fillers are exposed on the resin surface, making it impossible to suppress the bleed-out of triacylglycerol. For this reason, it is preferable that the amount of plant filler in the composite resin composition be within the aforementioned range.

[0036] The average particle size of the first and second plant fillers is preferably between 100 nm and 3 mm. If the average particle size is less than 100 nm, the size of the first and second plant fillers is small, and the surface area of ​​each filler is too large, causing the viscosity of the composite resin to become too high and the fluidity to decrease too much, making it impossible to add more than 50%. If it is greater than 3 mm, the plant fillers cannot be uniformly dispersed in the resin, the variation in strength within the composite resin composition becomes large, and the quality is unstable. For this reason, it is preferable that the average particle size of the plant fillers be within the above range.

[0037] <Triacylglycerol> In the embodiment, the triacylglycerol 4 is preferably a component derived from natural materials or a component generated when a component derived from natural materials is altered during the manufacturing process of the material. Examples of triacylglycerols include tripalmitin and 1-linoleoyl-2-palmitoleoyl-3-stearoylglycerol. However, the triacylglycerol is not limited to the above components as long as it is a component contained in the plant filler.

[0038] It is preferable that the triacylglycerol 4 is derived from the aforementioned plant filler. If triacylglycerol is added separately, all of the triacylglycerol will be present in the resin from the initial stage of kneading the raw materials, resulting in low viscosity and making it difficult to apply strong shear stress, thus hindering the proper dispersion and defibration of the plant filler. For this reason, it is preferable that the triacylglycerol 4 in this disclosure is derived from the aforementioned plant filler.

[0039] The main resin 1, the first plant filler 2, the second plant filler 3, and the dispersant 5 in the composite resin composition are in amounts totaling 100% by mass. Triacylglycerol 4 is contained in the first plant filler 2 and the second plant filler 3, and therefore is included in the amounts of the first plant filler 2 and the second plant filler 3.

[0040] <Dispersant> Examples of the dispersant 5 in the embodiment include various titanate coupling agents, silane coupling agents, unsaturated carboxylic acids, maleic acid, maleic anhydride, or modified polyolefins grafted with the anhydride, fatty acids, fatty acid metal salts, and fatty acid esters. The silane coupling agent is preferably an unsaturated hydrocarbon or epoxy type. The surface of the dispersant may be treated with a thermosetting or thermoplastic polymer component for modification. The dispersant 5 is appropriately selected by a combination of the main resin 1, the first plant filler 2, and the second plant filler 3.

[0041] <Method for producing composite resin compositions> In the method for producing the composite resin composition according to Embodiment 1, a main resin, a first plant filler, a second plant filler, and a dispersant are prepared in a predetermined mass ratio, and then kneaded to obtain the composite resin composition.

[0042] Preferred kneading equipment for the manufacturing method of this composite resin composition includes a kneader, a Banbury mixer, an extruder, and a roll kneader. Among these, a twin-screw kneader and a roll kneader are more preferred. However, the kneading equipment is not limited to the above-mentioned equipment as long as it has a rotating body as a kneading means. Furthermore, since the components in the plant filler include components that are easily decomposed by heat and volatile components, it is preferable to knead at the lowest possible temperature. [Examples]

[0043] Figure 2 shows the conditions and measurement results for Examples 1-4 and Comparative Examples 1-5.

[0044] A plant filler-containing composite resin composition was produced by the following manufacturing method. As mentioned above, kneaders, Banbury mixers, extruders, roll kneaders, etc. can be used as the kneading equipment, but in this example, a twin-screw kneader was used.

[0045] Polypropylene was used as the main resin, crushed pulp and coffee grounds as plant fillers, and maleic anhydride-modified polypropylene as a dispersant. These materials were weighed in a mass ratio of 27:60:10:3 and dry-blended. Softwood pulp (manufactured by Mitsubishi Paper Mills Ltd., product name: NBKP Celgar) was used as the starting material for the crushed pulp. This softwood pulp was crushed in a pulverizer to obtain fibrous filler as crushed pulp. The filler size was adjusted during the crushing process.

[0046] The mixture was melt-mixed and dispersed using a twin-screw kneader (KRC kneader manufactured by Kurimoto Iron Works Co., Ltd.). The shear force could be changed by altering the screw configuration of the twin-screw kneader, and in Example 1, a low-shear type specification was used. The composite resin discharged from the twin-screw kneader was hot-cut to produce composite resin pellets containing plant fillers.

[0047] Test specimens of composite resin molded products were prepared using injection molding machines (Japan Steel Works 180AD) with plant filler-containing composite resin pellets. The conditions for preparing the dumbbell test specimens were a resin temperature of 200°C, a mold temperature of 40°C, an injection speed of 60 mm / s, and a holding pressure of 100 MPa. The pellets were fed into the molding machine's screw via a hopper, and the rate of penetration was measured by the amount of pellets lost per unit time, confirming that it was constant. The shape of the test specimens was changed according to the evaluation items described below, and a No. 1 size dumbbell test specimen was prepared for elastic modulus measurement. In addition, a spiral flow test specimen was prepared for fluidity evaluation. The obtained test specimens of plant filler-containing composite resin molded products were evaluated by the following method.

[0048] [Evaluation criteria for composite resin molded products] (Elastic modulus of composite resin molded articles) A three-point bending test was performed using the obtained dumbbell-shaped specimen (No. 1). Here, the elastic modulus was evaluated as follows: a value less than 3.0 GPa was designated D, 3.0 GPa or more and less than 3.5 GPa was designated C, 3.5 GPa or more and less than 5.0 GPa was designated B, and 5.0 GPa or more was designated A. The elastic modulus of this specimen was 6.0 GPa, and its evaluation was A.

[0049] (Evaluation of the fluidity of composite resins) The length of the obtained spiral flow specimen was measured. A rating was given if the filled length was less than 30% of the total spiral flow length, a rating of C if it was between 30% and 50%, a rating of B if it was between 50% and 70%, and an rating of A if it was 70% or more. The length of the specimen was 63%, and its rating was B.

[0050] (Degree of crystallinity of composite resins) The melting (crystallization) peak was measured using differential scanning calorimeter (DSC) and the heat of fusion was calculated. The degree of crystallinity was calculated using the following formula. Crystallinity = (Measured heat of fusion / Heat of fusion of perfect crystal) × 100 Here, the degree of crystallinity was evaluated as follows: less than 30% was classified as D, 30% to less than 60% as B, and 60% or more as A. The composite resin had a crystallinity of 61%, and its evaluation was A.

[0051] (Degree of crystallinity around the fiber) A portion of the obtained dumbbell-shaped specimen (No. 1) was cut out and observed using Raman spectroscopy. Specimens where the degree of crystallinity of the resin around the plant filler was less than 1.05 times that of the crystalline portion were classified as D, and those where it was 1.05 times or more were classified as B. The crystallinity of this specimen was 1.13 times, and its evaluation was B.

[0052] (Results of triacylglycerol bleed-out evaluation) A triacylglycerol bleed-out evaluation test was conducted using the obtained dumbbell-shaped test specimen No. 1. While normally left at room temperature, the specimen was placed in a small hot air dryer at 60°C to perform an accelerated test, and the surface of the specimen was checked for stickiness every 24 hours. For specimens that became sticky, the specimen was immersed in a solvent capable of dissolving triacylglycerol, and the solvent's components were analyzed to confirm that the bled-out component was triacylglycerol. The test in an environment with 60°C hot air is approximately 50 times more accelerated than a test in a normal atmosphere at room temperature. Specimens that bled out in less than 48 hours were classified as D, those that bled out between 48 and 72 hours as C, those that bled out between 72 and 96 hours as B, and those that bled out after 96 hours as A. The evaluation of this specimen was B.

[0053] (Example 2) In Example 2, the amount of plant filler was reduced, and the mass ratio of main resin:crushed pulp:coffee grounds:dispersant was changed to 43:45:10:2. Plant fiber-containing composite resin pellets and molded articles were produced under the same conditions as in Example 1. The evaluation was also carried out in the same manner as in Example 1.

[0054] (Example 3) In Example 3, pulverized pulp with an average particle size of 2 mm, which is larger than that used in Example 1, was used as the plant fiber. Cellulose fiber-containing composite resin pellets and molded articles were produced using the same material and process conditions as in Example 1. The evaluation was also performed in the same manner as in Example 1.

[0055] (Example 4) In Example 4, the injection molding conditions were changed to increase the mold temperature during injection molding compared to Example 1. All other material and process conditions were the same as in Example 1 to produce cellulose fiber-containing composite resin pellets and molded articles. The evaluation was also performed in the same manner as in Example 1.

[0056] (Comparative Example 1) In Comparative Example 1, only coffee grounds were used as the plant filler, and the mass ratio of main resin:pulp:coffee grounds:dispersant was changed to 27:0:70:3. Composite resin pellets and molded articles were produced under the same material and process conditions as in Example 1. The evaluation was also carried out in the same manner as in Example 1.

[0057] (Comparative Example 2) In Comparative Example 2, only pulp was used as the plant filler, and the mass ratio of main resin:pulp:coffee grounds:dispersant was changed to 27:70:0:3. Composite resin pellets and molded articles were produced under the same material and process conditions as in Example 1. The evaluation was also carried out in the same manner as in Example 1.

[0058] (Comparative Example 3) In Comparative Example 3, an amorphous resin, PS, was used as the main resin component. Cellulose fiber-containing composite resin pellets and molded articles were produced under the same material and process conditions as in Example 1. The evaluation was also carried out in the same manner as in Example 1.

[0059] (Comparative Example 4) In Comparative Example 4, the amount of plant fiber was reduced compared to Example 1, and the mass ratio of main resin:pulp:coffee grounds:dispersant was changed to 79:15:5:1. Plant fiber-containing composite resin pellets and molded articles were produced under the same material and process conditions as in Example 1. The evaluation was also carried out in the same manner as in Example 1.

[0060] (Comparative Example 5) In Comparative Example 5, the amount of plant filler was increased compared to Example 1, and the weight ratio of main resin:pulp:coffee grounds:dispersant was changed to 2.5:70:25:2.5. For all other material and process conditions, the plant filler-containing composite resin pellets and molded articles were produced in the same manner as in Example 1. The evaluation was also carried out in the same manner as in Example 1.

[0061] The measurement results for each of Examples 1-4 and Comparative Examples 1-5 are shown in the table in Figure 3.

[0062] In Example 2, where the amount of plant filler was reduced, the reinforcing effect of the plant filler was reduced compared to Example 1, resulting in an elastic modulus of 5.3 GPa. The degree of crystallinity also decreased due to the reduction in the amount of plant filler, reaching 56%.

[0063] In Example 3, which used crushed pulp with an average particle size of 2 mm, the particle size was larger and the surface area was reduced compared to Example 1, resulting in a decreased reinforcing effect, an elastic modulus of 3.7, and an evaluation result of B.

[0064] In Example 4, where the mold temperature during injection molding was increased, the composite resin was cooled more slowly compared to Example 1, resulting in an increased degree of crystallinity to 66%, and the evaluation result was A.

[0065] In Comparative Example 1, where only coffee grounds were used as the plant filler, the reinforcing effect of the plant filler on the resin was small, resulting in an elastic modulus of 2.4 GPa and an evaluation result of D.

[0066] In Comparative Example 2, where only pulp was used as the plant filler, the fluidity was low, and the fluidity evaluation result was D.

[0067] In Comparative Example 3, which used PS, an amorphous resin, as the main resin component, the bleed-out of triacylglycerol could not be suppressed because the resin lacked crystalline components, resulting in a bleed-out evaluation result of D.

[0068] In Comparative Example 4, where the weight ratio of plant fibers to the total raw materials was reduced, the amount of plant filler was small, resulting in a reduced reinforcing effect of the filler on the composite resin, and the modulus of elasticity was 1.9 GPa.

[0069] In Comparative Example 5, where the weight ratio of plant fibers to the total raw materials was increased, the amount of plant filler was too high and the amount of resin was too low. This resulted in excessively high viscosity of the composite resin, placing a heavy load on the equipment and making stable mixing and molding impossible. Consequently, test specimens could not be prepared and evaluation could not be performed.

[0070] From the above evaluation, it was found that when only the second plant filler containing 1% to 40% by mass of triacylglycerol was used, the strength of the composite resin did not reach the required level. On the other hand, when only the first plant filler containing less than 1% by mass of triacylglycerol was used, the fluidity was low, and it was not possible to stably mold complex shapes such as product shapes. Furthermore, when an amorphous resin was used as the main resin, the bleed-out of triacylglycerol could not be suppressed. In addition, when the plant filler concentration was low, the reinforcing effect was small due to the small amount of plant filler, and the strength of the composite resin decreased. On the other hand, when the plant filler concentration was too high, it was not possible to stably knead and mold the resin. From the above, it was found that by using a plant filler containing triacylglycerol and a crystalline resin, and by setting the plant filler content to 50% to 90% by mass, the composite resin composition can be produced stably, with high mechanical strength and high fluidity.

[0071] Furthermore, this disclosure includes appropriately combining any embodiment and / or example from the various embodiments and / or examples described above, thereby achieving the effects of each embodiment and / or example. [Industrial applicability]

[0072] According to one aspect of this disclosure, a composite resin composition can be provided that offers superior mechanical strength compared to conventional general-purpose resins, has a high bio-content with a plant filler content of 50% by mass or more, and is environmentally friendly. Since the composite resin composition according to one aspect of this disclosure has high fluidity without the need for the addition of plasticizers, it is possible to obtain molded articles by high-cycle, high-volume molding methods such as injection molding and extrusion molding. Therefore, the composite resin molded articles according to one aspect of this disclosure can be used in home appliance casings, building materials, and automotive components that require excellent mechanical strength and high productivity. [Explanation of Symbols]

[0073] 1. Main resin 2. First plant filler 3. Second plant filler 4 Triacylglycerol 5. Dispersant 10. Composite resin composition containing plant fillers 11 Amorphous part 12 Crystal part

Claims

1. Main resin and Dispersed in the aforementioned main resin is a plant filler, Dispersing in the main resin is a dispersant, A composite resin composition containing plant fillers, comprising: The first plant filler contains 50% by mass or more and 97% by mass or less of triacylglycerol, The plant filler is a second plant filler in which 3% to 50% by mass of the plant filler is triacylglycerol in an amount of 1% to 40% by mass. The main resin is a crystalline resin, A plant filler-containing composite resin composition in which, when the total amount of the main resin, the plant filler, and the dispersant in the plant filler-containing composite resin composition is set to 100% by mass, the content of the plant filler is 50% by mass or more and 90% by mass or less.

2. The plant filler-containing composite resin composition according to claim 1, wherein the second plant filler has a total amount of cellulose, hemicellulose, and lignin of 5% by mass or more and 50% by mass or less.

3. The plant filler-containing composite resin composition according to claim 1 or 2, wherein the first plant filler comprises a total amount of cellulose, hemicellulose, and lignin of 80% by mass or more.

4. The plant filler-containing composite resin composition according to claim 1 or 2, wherein the average particle size of the plant filler is 100 nm or more and 3 mm or less.

5. The plant filler-containing composite resin composition according to claim 1 or 2, wherein the degree of crystallinity of the main resin is 30% or more.

6. The plant filler-containing composite resin composition according to claim 1 or 2, wherein the main resin comprises a first region around the plant filler and a second region away from the plant filler, and the degree of crystallinity of the main resin in the first region is 1.05 times or more than the degree of crystallinity of the main resin in the second region.

7. A composite resin molded article comprising the plant filler-containing composite resin composition according to claim 1 or 2.

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