Composite resin composition and composite resin molded article

Abstract

The present invention relates to a composite resin composition containing a resin and a biomass dispersed in the resin, the biomass containing organic nitrogen, and the content of the biomass being 10-99% by mass (inclusive) when the total amount of the composite resin composition is 100% by mass.

Description

Technical Field

[0001] The present invention relates to a biomass-containing composite resin composition and a composite resin molded article that are excellent in mechanical properties and exhibit excellent biodegradability. Background Art

[0002] So-called "common-purpose plastics" such as polyethylene (PE), polypropylene (PP), polystyrene (PS), and polyvinyl chloride (PVC) are not only extremely inexpensive and easy to shape, but also weigh a fraction of what metals or ceramics do. Consequently, these plastics are widely used as materials for a wide variety of daily necessities, including bags, various packaging, containers, and sheet materials. They are also widely used in industrial components such as automotive and electrical parts, home appliances, construction products, and daily necessities and general merchandise.

[0003] Due to these circumstances, the amount of post-use plastic waste is increasing year by year. Because plastic waste is difficult to decompose, it accumulates in the natural environment, causing environmental damage and pollution. In recent years, as a solution to these numerous problems, biodegradable plastics, which decompose into water and carbon dioxide in the natural environment, have been proposed, with hopes of expanding their use as an alternative to general-purpose plastics made from petroleum-based raw materials.

[0004] However, biodegradable plastics have drawbacks such as insufficient mechanical strength compared to general-purpose plastics. Consequently, biodegradable plastics currently lack the properties required for use in mechanical products such as automobiles, as well as various industrial products such as electrical, electronic, and information technology products, limiting their scope of application.

[0005] Furthermore, the biodegradation rate of biodegradable plastics is significantly affected by the environment. For example, in environments with few microorganisms, such as the ocean, complete decomposition takes a considerable amount of time, preventing them from fully utilizing their biodegradability.

[0006] Furthermore, biodegradable plastics include resins derived from biomass and resins derived from petroleum. From the viewpoint of suppressing carbon dioxide emissions, there is a demand for reducing the amount of petroleum-derived resins used among these.

[0007] To solve such problems, biodegradation promoters composed of cellulose nanofibers and biomass have been disclosed (e.g., see Patent Document 1), or resin molded bodies composed of inorganic fillers such as talc having a degradation-promoting effect and biodegradable plastics (e.g., see Patent Document 2).

[0008] Prior art literature

[0009] Patent Literature

[0010] Patent Document 1: Japanese Patent Application Laid-Open No. 2022-151892

[0011] Patent Document 2: Japanese Patent Application Laid-Open No. 2017-132967 Summary of the Invention

[0012] The biodegradation accelerator described in Patent Document 1 requires a cellulose nanofiber preparation step, limiting the amount of biomass added to the product. Furthermore, the resin molded article described in Patent Document 2 incorporates an inorganic filler with a higher specific gravity than the resin alone, resulting in an increased specific gravity of the composite resin molded article.

[0013] The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to provide a composite resin composition that reduces the amount of petroleum-derived resin used and promotes biodegradation even in the ocean or soil.

[0014] A composite resin composition according to one embodiment of the present disclosure includes a resin and biomass dispersed in the resin. The biomass contains organic nitrogen, and the biomass content is 10% by mass or more and 99% by mass or less, based on 100% by mass of the entire composite resin composition.

[0015] A composite resin molded article according to one embodiment of the present invention is a molded article obtained by molding the above-mentioned composite resin composition.

[0016] According to the composite resin composition of the present invention, the amount of petroleum-derived resin used can be reduced, and biodegradation can be promoted even in the ocean or soil. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic cross-sectional view showing the cross-sectional structure of the composite resin molded body according to the first embodiment.

[0018] Figure 2 This is a schematic diagram of a process for producing a composite resin composition and a molded article thereof according to the first embodiment.

[0019] Figure 3 These are diagrams showing the configurations and measurement results of composite resin molded bodies in Examples and Comparative Examples in the embodiment. DETAILED DESCRIPTION

[0020] The composite resin composition according to the first embodiment is a composite resin composition comprising a resin and biomass dispersed in the resin, wherein the biomass contains organic nitrogen, and when the entire composite resin composition is taken as 100% by mass, the content of the biomass is 10% by mass or more and 99% by mass or less.

[0021] The composite resin composition according to the first aspect of the present invention can realize a composite resin molded body having high elastic modulus, high biodegradability, and a high ratio of biomass as a raw material, in addition to high elastic modulus compared to a resin alone.

[0022] In the composite resin composition according to the second embodiment, in the first embodiment, the resin may be at least one of polyhydroxyalkanoic acid, polybutylene succinate, polylactic acid, polybutylene adipate-co-terephthalate, polycaprolactone, polyamide, modified starch, and derivatives thereof.

[0023] In the composite resin composition according to the third embodiment, in the first or second embodiment, the resin may be a thermoplastic biodegradable resin having a flexural modulus of 100 MPa or more.

[0024] In the composite resin composition according to a fourth aspect, in any one of the first to third aspects, the element ratio of carbon C to nitrogen N in the biomass, that is, the C / N ratio, may be 120 or less.

[0025] In the composite resin composition according to a fifth aspect, in any one of the first to fourth aspects, the biomass may have a cellulose / lignin ratio of 2.5 or greater.

[0026] In the composite resin composition according to a sixth aspect, in any one of the first to fifth aspects, the biomass may be a waste mushroom bed used for mushroom cultivation.

[0027] A composite resin molded article according to a seventh aspect is obtained by molding the composite resin composition according to any one of the first to sixth aspects.

[0028] The composite resin molded article according to the eighth aspect, in the seventh aspect, can have a water absorption rate of 5% or more after 168 hours using a JIS K7139 Type A1 test piece according to the measurement method specified in JIS K7209:2000.

[0029] Hereinafter, a composite resin composition, a composite resin molded body, and a method for producing the same according to an embodiment will be described with reference to the accompanying drawings. In the following description, the same components are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

[0030] (Implementation 1)

[0031] Figure 1 This is a schematic cross-sectional view showing the cross-sectional structure of the composite resin composition 10 according to the first embodiment.

[0032] The composite resin composition 10 of the first embodiment is formed from a melt-kneaded product containing a resin 1, a biomass 2, and an additive 3 as needed. Figure 1As shown in the schematic cross-sectional view of FIG, the composite resin composition 10 comprises a biomass 2 and an additive 3 dispersed in a resin 1.

[0033] In addition, at least one biomass 2 is exposed on the surface of the composite resin molded body.

[0034] According to the composite resin composition 10 , at least one biomass 2 is exposed on the surface of the composite resin molded body, and a composite resin molded body having high elastic modulus, high water absorption, and excellent biodegradability in a humid environment can be realized.

[0035] Hereinafter, each member constituting the composite resin composition 10 will be described.

[0036] <Resin>

[0037] In the first embodiment, the resin 1 is preferably a biodegradable plastic selected from polyhydroxy acids such as polylactic acid, polyglycolic acid, and polycaprolactone, polyhydroxyalkanoates (PHAs) such as polyhydroxybutyrate and polyhydroxyvalerate, polyester resins such as polyalkylene dicarboxylates, polyadipate-co-butylene terephthalate, polyethylene succinate, and polybutylene succinate, polyamides, and modified starches. Furthermore, to ensure good formability and mechanical properties, a thermoplastic resin having a flexural modulus of 100 MPa or greater is preferred. These resins may be used alone or in combination of two or more. Furthermore, the resin 1 is not limited to the above materials as long as it is biodegradable.

[0038] In the first embodiment of the present invention, "biodegradable plastic" refers to "a resin that has the same function as conventional petroleum-derived resins when used, and is ultimately decomposed into water and carbon dioxide by microorganisms in the soil and ocean in nature after use". Specifically, there can be listed polyhydroxyalkanoic acids such as polyhydroxybutyrate and polyhydroxyvalerate, polyhydroxy acids such as polylactic acid, polyglycolic acid, and polycaprolactone, polyester resins such as polyalkylene dicarboxylates such as polyadipate-co-butylene terephthalate, polyethylene succinate, and polybutylene succinate, polyamides, modified starches or their derivatives. As polyester resins, in addition to homopolymers of polyester monomers, copolymers of polyester monomers such as poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and copolymers of polyester monomers with other copolymerizable monomers are also included. These polyester resins can be used alone or in combination of two or more.

[0039] <Additives>

[0040] Next, the additive 3 will be described. The additive 3 is not essential to the composite resin composition according to the first embodiment, but can be used as needed for the purpose of improving the affinity between the resin 1 and the biomass 2 .

[0041] <Biomass>

[0042] Next, the biomass 2 is described. The main purpose of using the biomass 2 contained in the composite resin composition in this embodiment is that the organic nitrogen contained in the biomass is absorbed as a nutrient source for microorganisms in the composite resin composition, activating the proliferation of microorganisms and enzyme production, thereby promoting biodegradation in soil and oceans. For this purpose, the biomass preferably contains wood powder, waste mushroom beds from mushroom cultivation, silk, hemp, wool, bean dregs, coffee grounds, tea leaves, tea shells, barley tea dregs, bean peels, citrus peels, beer residues, juice residues, wheat bran, rice bran, soybean residues or rapeseed residues, etc. containing organic nitrogen. Organic nitrogen refers to the presence of nitrogen in the form of proteins, amino acids, etc. As a form of nitrogen, in addition to organic nitrogen, there are also ammoniacal nitrogen as ammonium salts and nitrate nitrogen in the form of nitrogen oxides such as nitrate ions. Among them, from the viewpoint of promoting biodegradation, the element ratio of carbon C to nitrogen N, i.e., the C / N ratio, is preferably 120 or less. Specific examples include spent mushroom cultivation beds, silk, wool, bean dregs, coffee grounds, tea leaves, tea husks, bean peels, citrus peels, potato peels, beer residue, juice residue, wheat bran, rice bran, soybean residue, or rapeseed residue. The C / N ratio of biomass can be evaluated by elemental analysis, etc.

[0043] The second purpose of adding biomass is to improve dimensional stability by improving mechanical properties and reducing the linear expansion coefficient. For this purpose, the biomass 2 preferably has a higher elastic modulus than the resin 1. Specifically, wood powder, waste mushroom beds from mushroom cultivation, silk, hemp, wool, etc. can be listed. In addition, from the viewpoint of promoting biodegradation, it is preferred that the content of difficult-to-decompose lignin is small, and the cellulose / lignin ratio of the biomass 2 is preferably 2.5 or more. Specifically, waste mushroom beds from mushroom cultivation, silk, hemp, wool, etc. can be listed. The cellulose / lignin ratio of the biomass can be evaluated by fiber analysis such as the detergent method.

[0044] Furthermore, by using a raw material containing sugars as the biomass 2, sugars derived from the biomass 2 are carbonized during the production process of the composite resin composition 10, thereby obtaining a composite resin composition 10 that slowly releases natural aromatic components. Specific examples of the biomass containing sugars include spent mushroom cultivation beds, bean dregs, coffee grounds, citrus peels, beer residue, fruit juice residue, wheat bran, and rice bran.

[0045] Among them, waste mushroom beds used in mushroom cultivation are particularly preferred from the viewpoint of availability and resource recycling. Furthermore, the biomass 2 is not limited to the above materials as long as it contains organic nitrogen and can improve mechanical properties.

[0046] When the composite resin composition is set to 100% by mass, the content of biomass 2 is preferably 10% by mass or more and 99% by mass or less. If the content of biomass 2 is less than 10% by mass, it is difficult for biomass 2 to form contact points within the composite resin composition, and the composite resin composition does not have sufficient water absorption. On the other hand, if the content of biomass 2 is greater than 99% by mass, the proportion of resin 1 becomes smaller, thus eliminating the effect of bonding biomass 2 to each other and deteriorating formability. From the perspective of water absorption and formability, the content of biomass 2 is more preferably 30% by mass or more and 70% by mass or less.

[0047] The morphology of the biomass 2 in the composite resin molded body formed from the composite resin composition will be described. A larger interface between the biomass 2 and the resin 1 increases the area of ​​the resin 1 that can come into contact with microorganisms when the biomass 2 absorbs water and swells. Therefore, a larger specific surface area of ​​the biomass 2 is preferred. Furthermore, to improve the water absorption of the composite resin molded body, it is preferred that the biomass 2 be exposed on the surface of the composite resin molded body. When the biomass 2 is exposed on the surface of the composite resin molded body, water is absorbed from the exposed portion and then absorbed into the composite resin molded body through the capillary action of the fibers.

[0048] Next, the state of existence of the biomass 2 in the composite resin molded body is described. The composite resin molded body includes a surface layer and an internal layer located closer to the inside than the surface layer. By adjusting the molding conditions and accelerating the shrinkage rate during molding of the composite resin composition, the biomass 2 can be segregated near the surface of the composite resin molded body. As a result, compared with the internal layer of the composite resin molded body, more biomass 2 is present in the surface layer. In addition, when viewed as a molded body, when a large amount of biomass 2 is present in the surface layer of the composite resin molded body, the elastic modulus on the outside is high, and thus the rigidity of the molded body as a whole is increased. Therefore, the structure that segregates the biomass 2 near the surface of the molded body is also related to the improvement of rigidity. The segregation of the biomass 2 near the surface can be evaluated by SEM observation of a cross section of the composite resin molded body.

[0049] Next, the characteristics of biomass 2 are described. Regarding the types of resin 1 and biomass 2, as described above, when biomass 2 is too soft relative to resin 1, that is, when the elastic modulus is small, the elastic modulus of the composite resin molded body as a whole becomes smaller, resulting in a decrease in strength. On the other hand, if biomass 2 is too hard relative to resin 1, that is, when the elastic modulus is large, the shock wave generated during the impact does not propagate, and the impact is absorbed at the interface between resin 1 and biomass 2. Therefore, cracks or cracks are easily generated near the interface, resulting in a decrease in impact resistance. Therefore, regarding the relationship between the elastic moduli of resin 1 and biomass 2, it is preferred that the elastic modulus of biomass 2 is higher and the difference is as small as possible. Regarding the optimal relationship, according to the simulation results, the elastic modulus difference between resin 1 and biomass 2 is preferably within 20GPa.

[0050] The biomass 2 may be surface-treated for the purpose of improving adhesion to the resin 1 or dispersibility in the composite resin composition. However, if the water absorption of the biomass 2 is impaired by surface treatment, it is preferable not to perform surface treatment in advance.

[0051] <Method for Producing Composite Resin Composition>

[0052] Next, a method for producing the composite resin composition will be described. Figure 2 This is a flow chart illustrating a process for producing the composite resin composition in this embodiment.

[0053] (1) Resin 1, biomass 2, and additive 3 are placed in a melt-kneading apparatus and melt-kneaded therein. The resin 1 is thereby melted, and the biomass 2 and additive 3 are dispersed in the molten resin 1. Simultaneously, the shearing action of the apparatus promotes the defibration of agglomerated biomass 2, enabling the biomass 2 to be finely dispersed in the resin 1.

[0054] Conventionally, when natural fibers and the like are compounded with resins, fibers that have been defibrated in advance by pretreatment such as wet dispersion are used.

[0055] In contrast, in the composite resin composition production process of this embodiment, pretreatment using wet dispersion for the purpose of defibration of the biomass 2 is not performed, and instead, melt-kneading is performed along with the resin 1 and the additive 3 functioning as a dispersant (a fully dry process). This method, by not performing a wet dispersion treatment of the biomass, can suppress swelling of the biomass 2 during the production process, thereby increasing the water absorption expansion rate of the biomass 2 in the resin 1 of the composite resin composition. Furthermore, by drying the biomass 2 beforehand or during kneading to adjust the moisture content to 5% or less, the expansion rate of the resin 1 upon water absorption can be further increased.

[0056] In order to utilize the full dry method to make the biomass 2 of the present embodiment, it is preferred to apply high shear stress during mixing. As specific mixing methods, single screw mixer, twin screw mixer, roller mixer, Banbury mixer, and combinations thereof can be listed. From the viewpoint of easily applying high shear and high productivity, continuous twin screw mixer and continuous roller mixer are particularly preferred. As long as it is a method that can apply high shear stress, mixing methods other than those mentioned above may also be used.

[0057] <Method for Manufacturing Composite Resin Molded Body>

[0058] (2) The composite resin composition extruded from the melt-kneading device is cut into pellets using a pelletizer or the like. Examples of pelletizing methods include those that are performed immediately after the resin is melted, such as in-air thermal cutting, underwater thermal cutting, and strand cutting. Alternatively, there is also a pulverization method that pulverizes and cuts the composite resin composition after forming it into a primary molded body or sheet.

[0059] (3) By injection molding the pellets, injection molded articles as composite resin molded bodies can be produced. As described above, the biomass 2 in the pellets can be mixed with the resin 1 to obtain injection molded articles having excellent elastic modulus, impact resistance, and appearance.

[0060] The composite resin composition 10 according to one embodiment of the present invention can be molded into a pot shape and used as a plant pot. Plant pots formed from the composite resin composition are highly biodegradable and therefore decompose without inhibiting plant growth, thereby reducing transplanting labor. The composite resin molded article is not limited to a plant pot, as long as the application requires biodegradability.

[0061] Hereinafter, each Example and each Comparative Example in the experiments conducted by the inventors will be described.

[0062] (Example 1)

[0063] In Example 1, a shiitake mushroom waste fungal bed-composite polylactic acid resin molded body was produced by the following production method.

[0064] Waste mushroom beds used for shiitake mushroom cultivation were used as biomass. The waste mushroom beds were crushed to a particle size of 3 mm or less using a multi-purpose grinder (SF-1, manufactured by Sanriki Co., Ltd.). Polylactic acid (TE-2000, manufactured by Unitika Co., Ltd.) was used as the resin. The waste mushroom beds, previously dried to a moisture content of 5% or less, and the polylactic acid were weighed to a weight ratio of 45:55 and dry-mixed.

[0065] Then, the mixture was melt-kneaded using a twin-screw kneader (KRC kneader, manufactured by KRIMOTO Iron Works Co., Ltd.). The screw was a medium shear type. The melt-kneading conditions were set at a resin temperature of 200°C and a rotation speed of 50 min. -1 The composite resin composition discharged from the twin-screw kneader is thermally cut to produce shiitake mushroom waste bed composite polylactic acid resin pellets.

[0066] The prepared shiitake mushroom waste bed-composite polylactic acid pellets were used to produce test pieces of shiitake mushroom waste bed-composite polylactic acid resin molded articles using an injection molding machine (180AD, manufactured by The Japan Steel Works, Ltd.). The test piece production conditions were a resin temperature of 200°C, a mold temperature of 30°C, an injection speed of 100 mm / s, and a holding pressure of 100 Pa. The shape of the test pieces was modified according to the evaluation criteria described below, and dumbbell-shaped tensile test pieces of the size A1 specified in JIS K7139 were produced for elastic modulus measurement. The resulting test pieces of shiitake mushroom waste bed-composite polylactic acid resin molded articles were evaluated using the following method.

[0067] (Elastic modulus of composite resin molded article)

[0068] The obtained A1 dumbbell-shaped test piece was subjected to a bending test. Here, as a method for evaluating the elastic modulus, a value of less than 3.8 GPa was evaluated as C, a value of 3.8 GPa or more and less than 6.0 GPa was evaluated as B, and a value of 6.0 GPa or more was evaluated as A.

[0069] The elastic modulus of the test piece was 6.4 GPa, and the evaluation thereof was A.

[0070] (Evaluation of C / N ratio of biomass)

[0071] The C / N ratio of the biomass used as the raw material for the composite resin composition was analyzed. A microcoder (JM11, manufactured by J-Science Co., Ltd.) was used to analyze the C / N ratio, the elemental ratio of carbon (C) to nitrogen (N). Here, the C / N ratio was evaluated as A for values ​​of 120 or less, and C for values ​​greater than 120.

[0072] The C / N ratio of the spent mushroom bed was 62, and the evaluation was A.

[0073] (Evaluation of Cellulose / Lignin Ratio of Biomass)

[0074] The cellulose / lignin ratio of the biomass used as the raw material for the composite resin composition was analyzed. The cellulose / lignin ratio analysis was performed using a detergent analysis method. Here, the cellulose / lignin ratio was evaluated as A when the value was 2.5 or greater, and C when it was less than 2.5.

[0075] The cellulose / lignin ratio of the spent mushroom bed was 4.0, and the evaluation was A.

[0076] (Evaluation of Water Absorption of Composite Resin Molded Article)

[0077] The resulting A1 dumbbell-shaped test piece was used to measure water absorption using a method based on JIS K7209:2000. Specifically, the test piece was dried in a 50°C dryer for 24 hours, the weight was measured, and then the piece was immersed in 23°C distilled water for 168 hours. The surface moisture was wiped off and the weight was measured. The water absorption was evaluated as A for values ​​of 5% or greater, B for values ​​of 3% or greater but less than 5%, and C for values ​​less than 3%.

[0078] The water absorption of the test piece was 5.2%, and the evaluation was A.

[0079] (Evaluation of Biodegradability of Composite Resin Molded Articles)

[0080] Using rod-shaped test pieces formed from the resulting composite resin molded body, a biodegradation test was conducted using a method based on JIS K6953-1:2011. Specifically, 60 mL of compostable seed stock (Yakawa Bussan Co., Ltd. YK-12) was placed in a plastic container. A rod-shaped test piece measuring 20 mm in height, 10 mm in width, and 4 mm in thickness, whose weight had been previously measured, was embedded in the seed stock. The weight loss after one month was evaluated by maintaining the temperature at 58°C and the moisture content at 50%. The biodegradability rate was evaluated as A for values ​​above 10% and C for values ​​below 10%.

[0081] The biodegradation rate of the test piece was 15.6%, and the evaluation was A.

[0082] (Comparative Example 1)

[0083] In Comparative Example 1, a polylactic acid resin molded article was produced using polylactic acid as a raw material without biomass compounding, and other process conditions were the same as in Example 1. The same evaluation as in Example 1 was also performed.

[0084] (Comparative Example 2)

[0085] In Comparative Example 2, conifer pulp was used as the biomass instead of spent shiitake mushroom beds. Other material and process conditions were the same as in Example 1. Conifer pulp-composite polylactic acid resin pellets and composite resin molded articles were produced. Evaluations were also conducted in the same manner as in Example 1.

[0086] (Comparative Example 3)

[0087] In Comparative Example 3, cedar wood flour was used as biomass instead of spent shiitake mushroom beds. Material and process conditions were otherwise the same as in Example 1. Pellets of cedar wood flour composited with polylactic acid resin and composite resin molded articles were produced. Evaluations were also conducted in the same manner as in Example 1.

[0088] (Comparative Example 4)

[0089] In Comparative Example 4, coffee grounds were used as biomass instead of spent shiitake mushroom beds. Material and process conditions were otherwise the same as in Example 1 to produce coffee ground-composite polylactic acid resin pellets and composite resin molded articles. Evaluations were also conducted in the same manner as in Example 1.

[0090] (Example 2)

[0091] In Example 2, undried shiitake mushroom waste beds were used as biomass. Other material and process conditions were the same as in Example 1. Shiitake mushroom waste bed-composite polylactic acid resin pellets and composite resin molded articles were produced. Evaluations were also conducted in the same manner as in Example 1.

[0092] The structures and measurement results of the composite resin molded bodies in Example 1, Example 2 and Comparative Examples 1 to 4 are shown in FIG. Figure 3 .

[0093] Depend on Figure 3 As can be seen, in Example 1, in which a waste shiitake mushroom bed as biomass is composited with polylactic acid as a resin, the elastic modulus is also as high as 6.4 GPa. Furthermore, due to the water absorption of the waste shiitake mushroom bed and the organic nitrogen contained in it, the biodegradation rate is also improved compared to the polylactic acid resin molded article of Comparative Example 1. This confirms that by composited with a biomass having a high cellulose / lignin ratio and containing organic nitrogen, with the biomass exposed on the surface of the composite resin molded article, a composite resin with a high elastic modulus and high biodegradability can be obtained.

[0094] In Comparative Example 2 in which softwood pulp was compounded as biomass, since organic nitrogen was not contained, the biodegradation rate was lower than that of Example 1, being 5.1%, and was evaluated as C.

[0095] In Comparative Example 3 in which cedar wood flour was compounded as biomass, the organic nitrogen content was low and the lignin ratio was high. Therefore, the biodegradation rate was lower than that of Example 1, being 7.6%, and was evaluated as C.

[0096] In Comparative Example 4 in which coffee grounds were compounded as biomass, the coffee grounds contained a large amount of oil and had a low elastic modulus. Therefore, the elastic modulus was lower than that of Example 1, being 3.5 GPa, and the evaluation was C.

[0097] In Example 2, in which the waste shiitake mushroom bed was composited without prior drying, the elastic modulus decreased compared to Example 1, reaching 3.9 GPa and receiving a rating of B. Furthermore, the water absorption rate also decreased, reaching 4.0%, receiving a rating of B. This is believed to be due to the hydrolysis of the resin during kneading and molding.

[0098] The above evaluation confirmed that by using biomass containing organic nitrogen and having a high cellulose / lignin ratio and a biodegradable plastic and pre-drying the biomass, a composite resin molded article having a high elastic modulus and high biodegradability can be obtained.

[0099] Furthermore, the present disclosure includes a case where any of the various embodiments and / or examples described above are appropriately combined, and the effects possessed by the respective embodiments and / or examples can be achieved.

[0100] Industrial Applicability

[0101] The composite resin composition disclosed herein can provide a molded article with superior mechanical strength and biodegradability compared to conventional biodegradable plastics. The disclosed resin improves its properties, making it suitable for use as a substitute for general-purpose petroleum-derived plastics. Consequently, the environmental impact of various industrial products or household items made from general-purpose petroleum-derived plastics can be significantly reduced. Furthermore, it can be used in packaging materials, daily necessities, appliance housings, building materials, and the like.

[0102] Reference numerals

[0103] 1. Resin

[0104] 2 Biomass

[0105] 3 Additives

[0106] 10 Composite resin composition

Claims

1. A composite resin composition comprising a resin and a biomass dispersed in the resin, The biomass contains organic nitrogen, When the entire composite resin composition is taken as 100 mass %, the content of the biomass is 10 mass % or more and 99 mass % or less.

2. The composite resin composition according to claim 1, wherein The resin comprises at least one of polyhydroxyalkanoic acid, polybutylene succinate, polylactic acid, polybutylene adipate-co-terephthalate, polycaprolactone, polyamide, modified starch and derivatives thereof.

3. The composite resin composition according to claim 1, wherein The resin is a thermoplastic biodegradable resin having a flexural elastic modulus of 100 MPa or more.

4. The composite resin composition according to claim 1, wherein The biomass has an element ratio of carbon C to nitrogen N, that is, a C / N ratio of 120 or less.

5. The composite resin composition according to claim 1, wherein The biomass has a cellulose / lignin ratio of 2.5 or greater. The composite resin composition according to claim 1 , wherein The biomass is a waste mushroom bed used for mushroom cultivation. 7 . A composite resin molded article obtained by molding the composite resin composition according to claim 1 .

8. The composite resin molded article according to claim 7, wherein When a test piece of JIS K7139 type A1 is used, the water absorption after 168 hours is 5% or more according to the measurement method specified in JIS K7209:2000.

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