Molding material, molded body, and method for producing molded body

Abstract

Provided are: a molding material which contains a polyurethane, can be injection molded, has a high degree of freedom in molding, contains a polyurethane, has excellent impact strength and bending strength, and is capable of producing a molded article which contains a polyurethane and has excellent impact strength and bending strength; and a molded body having both excellent impact strength and bending strength. This molding material contains cellulose fibers, a resin that melts at 200 DEG C or less, and a polyurethane, and has a complex viscosity at 180 DEG C of from 3000 Pa * s to 147000 Pa * s (inclusive). The resin is preferably at least one selected from the group consisting of polypropylene and polylactic acid.

Description

Technical Field

[0001] The present invention relates to a molding material, a molded body, and a method for producing the molded body. Background Art

[0002] In recent years, the recycling of various plastic materials such as polyester has promoted the effective use of resources, waste reduction, and conservation of resources.

[0003] Patent Document 1 discloses a wood substitute material for packaging. The wood substitute material is a fiber block formed by entwining 100 parts by mass of recycled fiber and 30 to 50 parts by mass of thermoplastic resin fiber having a melting point lower than the temperature at which the recycled fiber deteriorates. The block is heated and compressed at a temperature higher than the melting point of the thermoplastic resin fiber but at a temperature at which the recycled fiber does not deteriorate. The density of the wood substitute material is 0.4 to 0.7 g / cm 3 .

[0004] Patent Document 1: Japanese Patent Application Laid-Open No. 2004-025857

[0005] However, polyurethane has excellent characteristics such as elasticity and flexibility and is used in various products such as clothing.

[0006] However, polyurethane produces toxic gases (including amino compounds) and odors during thermal decomposition, making it difficult to recycle. Furthermore, while Patent Document 1 discloses compression molding, it is not possible to obtain a molded product with sufficient mechanical strength when using recycled fibers containing polyurethane. Furthermore, the technology described in Patent Document 1 cannot perform injection molding when using recycled fibers containing polyurethane, resulting in a limited degree of molding flexibility. Summary of the Invention

[0007] The present invention has been made to solve the above-mentioned technical problems, and can be implemented as the following application examples.

[0008] The molding material according to the application example of the present invention contains cellulose fibers, a resin that melts at 200° C. or lower, and polyurethane.

[0009] The complex viscosity at 180° C. is 3000 Pa·s or more and 147000 Pa·s or less.

[0010] The molded body according to the application example of the present invention is composed of the molding material according to the application example of the present invention.

[0011] The method for producing a molded article according to the application example of the present invention can mold the molding material according to the application example of the present invention while heating it to a temperature at which the resin melts. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a table summarizing the composition of the molding material, the complex viscosity of the molding material at 180° C., and the evaluation results for each Example and each Comparative Example. DETAILED DESCRIPTION

[0013] Hereinafter, preferred embodiments of the present invention will be described in detail.

[0014] [1] Molding materials

[0015] First, the molding material of the present invention will be described.

[0016] The molding material of the present invention contains cellulose fibers, a resin that melts at 200° C. or lower, and polyurethane, and has a complex viscosity at 180° C. of 3,000 Pa·s or higher and 147,000 Pa·s or lower.

[0017] This structure provides a molding material containing polyurethane, capable of injection molding, and having a high degree of molding freedom. Furthermore, it provides a molding material suitable for producing molded articles exhibiting excellent mechanical strength, particularly both impact strength and flexural strength. Furthermore, since the moldability of the molded articles can be further improved, the productivity of the molded articles can also be increased. In particular, by containing a resin that melts at a temperature below 200°C, the molding material can be appropriately molded at a temperature that sufficiently prevents thermal decomposition of the polyurethane.

[0018] Furthermore, although polyurethane is present in large quantities in waste clothing and the like, it has been difficult to recycle and incinerate because it generates toxic gases upon thermal decomposition. However, the present invention makes it possible to appropriately reuse such polyurethane.

[0019] Furthermore, the inclusion of cellulose fibers, a natural and abundant material derived from plants, effectively addresses environmental issues and conserves natural resources. This is also advantageous from the perspectives of stable supply of molding materials and molded articles produced using these materials, and cost reduction. Furthermore, cellulose fibers are present in large quantities in waste paper, old cloth, and the like, in addition to virgin pulp, and are also advantageous from the perspective of promoting the effective recycling of resources.

[0020] On the other hand, if the above conditions are not met, satisfactory results cannot be obtained.

[0021] For example, even if a molding material contains a resin and polyurethane that melt at 200° C. or lower, if it does not contain cellulose fibers, the elastic modulus and shape retention of a molded article produced using the molding material will be significantly low.

[0022] Furthermore, even if the molding material contains cellulose fibers and a resin that melts at 200° C. or lower, if it does not contain polyurethane, there arises a problem in that the impact strength is reduced.

[0023] Furthermore, even if the molding material contains cellulose fibers and polyurethane, if it does not contain a resin that melts at 200°C or below, injection molding cannot be performed, significantly reducing the moldability of the molded article. Furthermore, this reduced moldability also deteriorates the mechanical strength of the resulting molded article.

[0024] Furthermore, when a molding material uses a resin with a melting point exceeding 200°C instead of a resin that melts below 200°C, the degree of molding freedom cannot be fully improved, and, for example, injection molding cannot be performed. Furthermore, the mechanical strength of a molded body produced using such a molding material deteriorates.

[0025] On the other hand, if the complex viscosity of the molding material at 180° C. is lower than the lower limit, problems such as metering failure during injection molding, burrs on the molded article, and the generation of bubbles in the molded article may occur.

[0026] On the other hand, if the complex viscosity of the molding material at 180° C. exceeds the upper limit, there arises a problem that a short shot of the molded body or damage to the injection molding machine and the mold is likely to occur.

[0027] In the present invention, complex viscosity refers to the dynamic viscoelasticity measured using a rheometer. Complex viscosity can be determined under the following conditions: starting temperature: 100°C, step temperature: 1°C, ending temperature: 200°C, heating rate: 5°C / min, strain control: 0.1 degree, frequency: 1 Hz, automatic control: on, waveform: sine wave, continuous excitation: on, averaging times: 3, and weighting control: off. The lower plate is vibrated with a 1 mm thick sample sandwiched between parallel plates. Complex viscosity can be determined, for example, using a Pheosol-G3000 (manufactured by UBM).

[0028] As mentioned above, the complex viscosity of the molding material of the present invention at 180°C only needs to be 3000 Pa·s or more and 147000 Pa·s or less, but is preferably 4000 Pa·s or more and 140000 Pa·s or less, more preferably 5000 Pa·s or more and 90000 Pa·s or less, and even more preferably 7000 Pa·s or more and 40000 Pa·s or less.

[0029] Thereby, the aforementioned effects are more significantly exhibited.

[0030] [1-1] Cellulose fiber

[0031] The molding material of the present invention contains cellulose fibers.

[0032] Cellulose fibers are components that greatly contribute to the maintenance of the shape of the molded article produced using the molding material of the present invention and have a significant influence on the properties such as the strength of the molded article.

[0033] Cellulose is an abundant natural material derived from plants. Therefore, the use of cellulose fibers effectively addresses environmental issues and conserves natural resources. It is also preferred from the perspectives of stable supply of molding materials and molded articles produced using them, as well as cost reduction. Furthermore, cellulose fibers have the highest theoretical strength among all fibers, which is also advantageous from the perspective of improving the strength of molded articles.

[0034] As cellulose fibers, virgin pulp can be used, or waste paper, old cloth, etc. can be recycled.

[0035] Cellulose fibers are generally composed mainly of cellulose, but may contain components other than cellulose. Examples of such components include hemicellulose and lignin.

[0036] Furthermore, as the cellulose fibers, cellulose fibers subjected to treatments such as bleaching may also be used.

[0037] Examples of the cellulose fibers include cotton, linen, rayon, and cupra.

[0038] The average length of the cellulose fibers is not particularly limited, but is preferably 50 μm or more and less than 3 mm, more preferably 70 μm or more and less than 500 μm, and further preferably 100 μm or more and less than 400 μm.

[0039] This allows for improved shape stability and strength in molded articles produced using the molding material. Furthermore, dust generation in molded articles produced using the molding material can be more effectively prevented and suppressed. Furthermore, undesirable surface irregularities on molded articles produced using the molding material can be more effectively prevented. Fiber length was determined using a method based on ISO 16065-2:2007.

[0040] The average diameter of the cellulose fibers is not particularly limited, but is preferably 3 μm or more and less than 100 μm, more preferably 4 μm or more and less than 50 μm, and even more preferably 5 μm or more and less than 20 μm.

[0041] This makes it possible to further improve the shape stability, strength, etc. of the molded body produced using the molding material. In addition, it is possible to more effectively prevent the formation of undesirable irregularities on the surface of the molded body produced using the molding material.

[0042] The average aspect ratio of the cellulose fibers, that is, the average length relative to the average diameter, is not particularly limited, but is preferably 10 or more and 1000 or less, and more preferably 15 or more and 100 or less.

[0043] This allows for improved shape stability and strength of molded articles produced using the molding material. Furthermore, it is possible to more effectively prevent and suppress the generation of dust in molded articles produced using the molding material. Furthermore, it is possible to more effectively prevent the generation of undesirable surface irregularities on molded articles produced using the molding material.

[0044] The content of the cellulose fibers in the molding material of the present invention is preferably 2.0% by mass to 40.0% by mass, more preferably 3.0% by mass to 35.0% by mass, and even more preferably 5.0% by mass to 30.0% by mass.

[0045] This makes it easy to adjust the complex viscosity of the molding material at 180° C. to a more preferred range, and the effects of the present invention described above can be more significantly exhibited.

[0046] [1-2] Resins that melt below 200°C

[0047] The molding material of the present invention contains a resin that melts at 200° C. or lower, that is, a resin having a melting point of 200° C. or lower. However, the resin does not contain polyurethane.

[0048] By containing such a resin, the toughness of the molded body produced using the molding material of the present invention can be improved, and the impact resistance of the molded body can be made sufficiently excellent.

[0049] The melting point of the resin only needs to be 200°C or lower, preferably 115°C or higher and 185°C or lower, and more preferably 145°C or higher and 180°C or lower.

[0050] The resin may be meltable at 200° C. or lower by itself, but is preferably compatible with polyurethane at 200° C. or lower.

[0051] This allows for a higher degree of freedom in molding and further improves the mechanical strength of the produced molded body.

[0052] Examples of the resin include polyolefins such as polyethylene and polypropylene, and polyesters such as aliphatic polyesters and aromatic polyesters. One or more selected from these can be used in combination, and at least one selected from the group consisting of polypropylene and polylactic acid is preferred.

[0053] This further improves the compatibility between the resin and polyurethane, and enables the aforementioned effects to be more significantly exhibited.

[0054] In particular, the use of polylactic acid derived from biomass raw materials can more appropriately reduce the consumption of landfill resources.

[0055] Furthermore, the present invention achieves the aforementioned excellent effects even when using recycled polypropylene. More specifically, recycled polypropylene typically undergoes thermal decomposition during regeneration, resulting in a decrease in molecular weight, a decrease in viscosity, and a decrease in moldability. However, the present invention ensures excellent injection moldability even when using recycled polypropylene.

[0056] Aliphatic polyesters are polyesters that do not have an aromatic chemical structure, and are composed entirely of monomers that do not have an aromatic chemical structure. Examples of aliphatic polyesters include those in which both the polycarboxylic acid component and the polyol component as constituent monomers have aliphatic alkylene groups. Alternatively, aliphatic polyesters may be composed of monomers containing hydroxyl and carboxyl groups within the molecule. Examples of aliphatic polyesters composed of monomers containing hydroxyl and carboxyl groups within the molecule include polylactic acid.

[0057] When the aliphatic polyester has a chemical structure in which a polycarboxylic acid component having an aliphatic alkylene group and a polyol component having an aliphatic alkylene group are polymerized, the aliphatic polyester preferably has a chemical structure in which an alkylene dicarboxylic acid having an alkylene group having a carbon chain length of 2 to 6 is condensed with an alkylene glycol having an alkylene group having a carbon chain length of 2 to 8.

[0058] Thereby, the aforementioned effects are more significantly exhibited, and the compatibility with polyurethane can be further improved, thereby further significantly exhibiting the aforementioned effects.

[0059] The carbon chain length of the alkylene group of the alkylenedicarboxylic acid is preferably 2 or more and 6 or less, more preferably 2 or more and 5 or less, and even more preferably 2 or more and 4 or less.

[0060] Thereby, the aforementioned effects are more significantly exhibited.

[0061] The alkylene group of the alkylenedicarboxylic acid may have a branched structure, but is preferably a linear structure.

[0062] Thereby, the aforementioned effects are more significantly exhibited.

[0063] Examples of the alkylene dicarboxylic acid include succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid, and one or more selected from these can be used in combination.

[0064] The carbon chain length of the alkylene group of the alkylene glycol is preferably 2 or more and 8 or less, more preferably 2 or more and 6 or less, and even more preferably 3 or more and 5 or less.

[0065] Thereby, the aforementioned effects are more significantly exhibited.

[0066] The alkylene group of the alkylene glycol may have a branched structure, but is preferably a linear structure.

[0067] Thereby, the aforementioned effects are more significantly exhibited.

[0068] Examples of the alkylene glycol include 1,2-ethylene glycol, 1,3-propylene glycol, 1,4-butylene glycol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, and 1,8-octanediol. One or more selected from these can be used in combination.

[0069] Specific examples of the aliphatic polyester containing an alkylene dicarboxylic acid and an alkylene glycol satisfying the above conditions as monomer components include polybutylene succinate, polybutylene succinate adipate, and polyethylene adipate. One or more selected from these can be used in combination.

[0070] These are biodegradable materials that can more appropriately reduce the environmental burden of molded articles. Furthermore, these materials are relatively inexpensive and readily and stably available. Therefore, they are advantageous from the perspectives of stable supply of molding materials and molded articles, and cost reduction.

[0071] The content of the resin in the molding material of the present invention is not particularly limited, but is preferably 15.0% by mass to 90.0% by mass, more preferably 25.0% by mass to 85.0% by mass, and even more preferably 45.0% by mass to 80.0% by mass.

[0072] This makes it easy to adjust the complex viscosity of the molding material at 180° C. to a more preferred range, and the effects of the present invention described above can be more significantly exhibited.

[0073] When the content of the cellulose fiber in the molding material of the present invention is XC [mass %] and the content of the resin is XR [mass %], the relationship of 0.03 ≤ XC / XR ≤ 0.60 is preferably satisfied, the relationship of 0.04 ≤ XC / XR ≤ 0.50 is more preferably satisfied, and the relationship of 0.07 ≤ XC / XR ≤ 0.45 is further preferably satisfied.

[0074] This makes it easy to adjust the complex viscosity of the molding material at 180° C. to a more preferred range, and the effects of the present invention described above can be more significantly exhibited.

[0075] [1-3] Polyurethane

[0076] The molding material of the present invention contains polyurethane.

[0077] Polyurethane is generally a component having excellent affinity with both cellulose fibers and the above-mentioned resins.

[0078] The polyurethane is generally compatible with the resin during the production process of a molded body using the molding material of the present invention, particularly during the heat treatment during molding.

[0079] This can improve the bending strength of the molded body produced using the molding material of the present invention.

[0080] The number average molecular weight of the polyurethane is preferably 20,000 or more and 300,000 or less, more preferably 30,000 or more and 200,000 or less, and even more preferably 40,000 or more and 150,000 or less.

[0081] This can further improve the affinity of the polyurethane for the cellulose fibers and the resin, and further improve the impact strength and flexural strength of a molded article produced using the molding material.

[0082] The polyurethane may be contained in the molding material in any form such as powder, and may also be contained in the form of fibers.

[0083] This makes it possible to appropriately use polyurethane derived from, for example, waste clothing.

[0084] The content of polyurethane in the molding material of the present invention is preferably 0.3 mass % to 6.0 mass %, more preferably 0.5 mass % to 5.0 mass %, and even more preferably 1.0 mass % to 3.2 mass %.

[0085] This makes it easy to adjust the complex viscosity of the molding material at 180° C. to a more preferred range, and the effects of the present invention described above can be more significantly exhibited.

[0086] The sum of the content of the resin and the content of the polyurethane in the molding material of the present invention is preferably 25.0 mass % to 91.0 mass %, more preferably 30.0 mass % to 88.0 mass %, and even more preferably 45.0 mass % to 80.0 mass %.

[0087] This makes it easy to adjust the complex viscosity of the molding material at 180° C. to a more preferred range, and the effects of the present invention described above can be more significantly exhibited.

[0088] When the content of the resin in the molding material of the present invention is set to XR [mass %] and the content of the polyurethane is set to XU [mass %], it is preferred to satisfy the relationship of 0.01≤XU / XR≤0.30, more preferably to satisfy the relationship of 0.02≤XU / XR≤0.20, and even more preferably to satisfy the relationship of 0.03≤XU / XR≤0.10.

[0089] This makes it easier to adjust the complex viscosity of the molding material at 180°C to a more preferred range, more significantly demonstrating the effects of the present invention. In particular, the impact strength and flexural strength of a molded article produced using the molding material can be further improved.

[0090] When the content of cellulose fibers in the molding material of the present invention is XC [mass %] and the content of polyurethane is XU [mass %], the relationship of 0.01≤XU / XC≤3.0 is preferably satisfied, the relationship of 0.02≤XU / XC≤1.6 is more preferably satisfied, and the relationship of 0.03≤XU / XC≤0.6 is further preferably satisfied.

[0091] This makes it easier to adjust the complex viscosity of the molding material at 180°C to a more preferred range, more significantly demonstrating the effects of the present invention. In particular, the impact strength and flexural strength of a molded article produced using the molding material can be further improved.

[0092] [1-4] Other fibers

[0093] The molding material of the present invention may further contain fibers other than the above-mentioned cellulose fibers, resins, and polyurethanes. Hereinafter, such fibers are also referred to as "other fibers."

[0094] By including other fibers, for example, the strength of the molded body can be further increased.

[0095] Examples of other fibers include fibers made of resin materials, more specifically polyester fibers, acrylic fibers, nylon fibers, acetate fibers, etc. However, these other fibers are made of a material that does not melt at 200°C, and when the molding material is heated to 200°C, they become fibrous.

[0096] The average length of the other fibers is not particularly limited, but is preferably less than 3 mm, more preferably 50 μm or more and less than 500 μm, and even more preferably 100 μm or more and less than 400 μm.

[0097] This makes it possible to further improve the impact strength and bending strength of a molded body produced using the molding material.

[0098] The average diameter of the other fibers is not particularly limited, but is preferably less than 100 μm, more preferably 3 μm or more and less than 50 μm, and even more preferably 5 μm or more and less than 20 μm.

[0099] This makes it possible to further improve the impact strength and bending strength of a molded body produced using the molding material.

[0100] The average aspect ratio of the other fibers, that is, the average length relative to the average diameter, is not particularly limited, but is preferably 10 or more and 1000 or less, and more preferably 15 or more and 100 or less.

[0101] This makes it possible to further improve the impact strength and bending strength of a molded body produced using the molding material.

[0102] The content of other fibers in the molding material of the present invention is preferably 1.0 mass % to 30.0 mass %, more preferably 2.0 mass % to 25.0 mass %, and even more preferably 3.0 mass % to 20.0 mass %.

[0103] This makes it possible to further improve the impact strength and bending strength of a molded body produced using the molding material.

[0104] When the content of the resin in the molding material of the present invention is set to XR [mass %] and the content of other fibers is set to XO [mass %], the relationship of 0.03≤XO / XR≤3.0 is preferably satisfied, the relationship of 0.05≤XO / XR≤2.0 is more preferably satisfied, and the relationship of 0.10≤XO / XR≤0.80 is further preferably satisfied.

[0105] This makes it possible to further improve the impact strength and bending strength of a molded body produced using the molding material.

[0106] When the content of cellulose fibers in the molding material of the present invention is represented by XC [mass %] and the content of other fibers is represented by XO [mass %], the relationship 0.1 ≤ XO / XC ≤ 3.8 is preferably satisfied, the relationship 0.2 ≤ XO / XC ≤ 2.1 is more preferably satisfied, and the relationship 0.3 ≤ XO / XC ≤ 1.7 is further preferably satisfied.

[0107] This makes it possible to further improve the impact strength and bending strength of a molded body produced using the molding material.

[0108] [1-5] Flame retardants

[0109] The molding material of the present invention may further contain a flame retardant.

[0110] Examples of the flame retardant include inorganic flame retardants such as antimony compounds, metal hydroxides, nitrogen compounds, and boron compounds; and organic flame retardants such as bromine compounds and phosphorus compounds.

[0111] When the molding material contains a flame retardant, the content of the flame retardant can be 1.0 part by mass or more and 20.0 parts by mass or less, based on 100.0 parts by mass of the total content of the cellulose fibers, the resin, and the polyurethane.

[0112] This allows the aforementioned effects of the present invention to be more effectively exhibited, and at the same time, the flame retardancy of a molded article produced using the molding material of the present invention to be further improved.

[0113] [1-6] Other ingredients

[0114] The molding material of the present invention may contain components other than those mentioned above. Hereinafter, such components are also referred to as "other components" in this term.

[0115] Examples of other components include colorants, insect repellents, mildew preventers, antioxidants, ultraviolet absorbers, aggregation inhibitors, release agents, and resin materials other than those mentioned above.

[0116] However, the content of other components in the molding material of the present invention is preferably 10.0% by mass or less, more preferably 5.0% by mass or less, and even more preferably 3.0% by mass or less.

[0117] [2] Method for manufacturing molding materials

[0118] Next, the method for producing the molding material of the present invention will be described.

[0119] The molding material of the present invention can be produced, for example, by mixing the above-mentioned components. In this case, the timing of mixing the components may be the same or different.

[0120] The molding material of the present invention can also be produced by kneading the above-mentioned components, for example.

[0121] The components can be kneaded using, for example, a single-screw kneader or a twin-screw kneader.

[0122] The material temperature during kneading is preferably lower than 200°C, more preferably 120°C to 190°C, and even more preferably 150°C to 180°C.

[0123] The strand-shaped molding material obtained by kneading can be granulated using a granulator such as a stranding method or a water ring heat cutting method to obtain a pellet-shaped molding material.

[0124] In addition, the following method can also be applied as a manufacturing method for a molding material. That is, the kneaded product of the above-mentioned components can be formed into a sheet, and then, for example, a crushing device is used to cut it into a desired shape to form a granular molding material. The method for molding the kneaded product into a sheet is not particularly limited. For example, the kneaded product can be first piled up in the air as a sheet-like deposit, and the deposit is compressed by a calendering device to remove air and increase density. Next, a heating furnace is used to heat it in a non-contact manner, and then a method for hot pressing is performed by a hot pressing device. The shape and size of the particles obtained by cutting are not particularly limited. For example, it can be a roughly rectangular parallelepiped with a length of more than 2 mm and less than 5 mm.

[0125] The cellulose fibers used in the production of the molding material of the present invention may be previously subjected to a defibration treatment. In particular, a material obtained by defibration of a cellulose fiber source containing cellulose fibers, such as waste paper or old cloth, may be used.

[0126] In addition, when the molding material of the present invention contains fibrous polyurethane, i.e., polyurethane fibers, the polyurethane fibers used in the production of the molding material may be pre-fiberized. In particular, a material obtained by defibration of a polyurethane fiber source containing polyurethane fibers, such as old cloth, may be used.

[0127] Furthermore, when the molding material of the present invention contains other fibers, the other fibers used in the production of the molding material of the present invention may be subjected to a defibration treatment in advance. In particular, a material obtained by defibration of another fiber source containing other fibers, such as old cloth, may be used.

[0128] The fiber sources mentioned above, ie, cellulose fiber sources, polyurethane fiber sources, and other fiber sources may be coarsely pulverized before defibration.

[0129] The fiber source can be crushed into fragments using a crushing device equipped with crushing blades in an atmosphere such as air, etc. The fragments may be in the form of a roughly cubic or rectangular parallelepiped shape of several mm square.

[0130] The fiber source fragments are defibrated to become disentangled fibers. Here, defibration means to disentangle multiple fibers one by one from a state where the fibers are integrated.

[0131] Defibrination can be appropriately performed under dry conditions. Here, dry means not being performed in a liquid, but in a gas such as the atmosphere. In addition, in order to prevent static electricity, the fibers may be sprayed with water, for example.

[0132] Dry defibration can be suitably performed, for example, by air flow.

[0133] The fiber sources may be defibrated individually or in a mixed state of a plurality of fiber sources.

[0134] In addition, as a fiber source, a fiber source containing multiple types of fibers, more specifically two or more types of cellulose fibers, polyurethane fibers, and other fibers may be used. Examples of fiber sources containing two or more types of fibers include blended products.

[0135] The fiber source may be defibrated in a state where it contains components other than fibers, such as the resin, non-fibrous polyurethane, flame retardant, and other components.

[0136] [3] Molded body

[0137] Next, the molded article of the present invention will be described.

[0138] The molded article of the present invention is composed of the aforementioned molding material of the present invention.

[0139] With such a configuration, it is possible to provide a molded product containing polyurethane and having excellent both impact strength and flexural strength.

[0140] Furthermore, the inclusion of cellulose fibers, a natural and abundant material derived from plants, effectively addresses environmental issues and conserves landfill resources, and is also advantageous from the perspectives of stable supply of molded articles and cost reduction. Furthermore, cellulose fibers are present in large quantities in waste paper, old cloth, and the like, in addition to virgin pulp, and are also advantageous from the perspective of promoting the effective recycling of resources.

[0141] Furthermore, although polyurethane is present in large quantities in waste clothing, it is difficult to separate from other components when mixed with them, such as in blended products. Furthermore, it generates toxic gases during heat processing at temperatures above 200°C, making it difficult to reuse and incinerate it. However, according to the present invention, the polyurethane contained in waste clothing can be effectively reused.

[0142] Furthermore, the molded article of the present invention only needs to have a portion composed of the aforementioned molding material of the present invention, and may also have a portion composed of a material other than the molding material of the present invention.

[0143] The components constituting the molded body preferably satisfy the conditions described in [1-1] to [1-6] above.

[0144] The shape of the molded body is not particularly limited, and may be any shape such as a sheet, a block, a sphere, or a three-dimensional shape.

[0145] The molded article can be a component for any purpose, but is particularly suitable for use in environments where dust generation is a problem. More specifically, for example, components having a fluid flow path, components disposed around such components, ink cartridges, various containers, and various other items. Molded articles manufactured using conventional materials containing cellulose fibers and resins are prone to dust generation and are unsuitable for use in environments where dust generation is a problem. In contrast, the molded article of the present invention is less prone to dust generation. Therefore, when used in such applications, the effects of the present invention are more significantly exerted.

[0146] [4] Method for manufacturing a molded body

[0147] Next, the method for producing the molded article of the present invention will be described.

[0148] The method for producing a molded article is to mold the aforementioned molding material of the present invention while heating it to a temperature at which the resin melts.

[0149] Thus, it is possible to provide a method for producing a molded article that contains polyurethane and is excellent in both impact strength and flexural strength.

[0150] As the molding method, for example, compression molding, extrusion molding, etc. may be adopted, but injection molding is preferred.

[0151] Thus, even a molded body having a complex structure or a molded body having a microstructure can be appropriately manufactured.

[0152] The heating temperature of the molding material during molding is preferably lower than 200°C, more preferably 120°C to 190°C, and even more preferably 150°C to 180°C.

[0153] This can more appropriately prevent the thermal decomposition of polyurethane, improve moldability and molded product productivity, and further improve the mechanical strength of the produced molded product.

[0154] After the above-described molding, post-processing such as machining such as grinding and polishing, painting, plating, etc. may be performed.

[0155] As mentioned above, although the preferred embodiments of the present invention have been described, the present invention is not limited to these.

[0156] Example

[0157] Next, specific embodiments of the present invention will be described.

[0158] [5] Preparation of molding materials

[0159] Example 1

[0160] First, commercial clothing recycling containing cellulose fibers, polyurethane fibers, acrylic fibers, and polyester fibers was prepared as a fiber source.

[0161] The fiber source was chopped into roughly cubic shapes of several mm square in the atmosphere using a pulverizing device equipped with a coarse pulverizing blade, and then defibrated by blowing air.

[0162] The mass ratios of cellulose fiber, polyurethane fiber, acrylic fiber, and polyester fiber in the obtained defibrated material were 3.8:0.7:3.1:2.4.

[0163] 10.0 parts by mass of the defibrated material obtained above and 90.0 parts by mass of polypropylene (H700, manufactured by PRIME POLYMER), a resin molten at temperatures below 200°C, were weighed and then mixed in a twin-screw kneader (KZW15TW-45MG, manufactured by Technovel). The kneading conditions were a maximum heating temperature of 180°C and an extrusion rate of 1 kg / hr. The material was then processed into strands and passed through a pelletizer to form pellets for molding.

[0164] The cellulose fibers contained in the molding material had an average length of 1.5 mm and an average diameter of 15 μm. The polyurethane fibers had an average length of 1.5 mm and an average diameter of 50 μm. The number-average molecular weight of the polyurethane constituting the polyurethane fibers was 60,000. The melting point of the polypropylene (H700, manufactured by PRIME POLYMER) was 165°C.

[0165] Examples 2 to 6

[0166] If the composition of the molding material becomes Figure 1 As shown, a pelletized molding material was prepared in the same manner as in Example 1 except that the types and amounts of raw materials used were changed.

[0167] Comparative Examples 1 to 7

[0168] If the composition of the molding material becomes Figure 1 As shown, a pelletized molding material was prepared in the same manner as in Example 1 except that the types and amounts of raw materials used were changed.

[0169] [6] Manufacturing of molded bodies

[0170] The molding materials of each of the examples and comparative examples were injection molded using an injection molding machine (manufactured by Nissei Plastic Industry Co., Ltd., THX40-5V) to produce molded articles for Charpy impact strength evaluation, flexural strength evaluation, and flexural modulus evaluation, as described below. The heating temperature of the molding materials during injection molding was 180°C. The molded articles for Charpy impact strength evaluation were rectangular plates with long sides of 80 mm ± 2 mm, short sides of 4.0 mm ± 0.2 mm, and a thickness of 10.0 mm ± 0.2 mm. The molded articles for flexural strength evaluation and flexural modulus evaluation were rectangular plates with long sides of 80 mm ± 2 mm, short sides of 10.0 mm ± 0.2 mm, and a thickness of 4.0 mm ± 0.2 mm.

[0171] [7] Evaluation

[0172] The following evaluations were performed on the molded articles according to the aforementioned Examples and Comparative Examples.

[0173] [7-1] Formability

[0174] For each of the examples and comparative examples, as described in [6] above, 10 molded articles for evaluation of bending strength were manufactured and evaluated according to the following criteria. In addition, molded articles that met the conditions that the injection molding machine did not produce wire drawing (leakage) and that the molded articles had no burrs, short shots, voids, sink marks, silver streaks, flow marks, warpage, weld lines, cracks, spraying, or discoloration were considered acceptable, and molded articles that did not meet these conditions were considered unacceptable.

[0175] A: 10 out of 10 are qualified products.

[0176] B: 6 or more and 9 or less of 10 items were qualified.

[0177] C: The number of conforming products is 1 or more and 5 or less out of 10.

[0178] D: 0 out of 10 qualified products.

[0179] [7-2] Charpy impact strength

[0180] The Charpy impact strength of the molded articles for evaluation of the Charpy impact strength of each of the examples and comparative examples, manufactured as described in [6] above, was measured using an impact tester IT manufactured by Toyo Seiki Seisaku-sho, Ltd. in accordance with ISO 179 (JIS K7111). The Charpy impact strength was measured with a hammer weight of 4 J (WR 2.14 N / m), a lift angle of 150°, a notch remaining width of 8.0 mm ± 0.2 mm, and a notch angle of 45°.

[0181] [7-3] Bending strength

[0182] The flexural strength of the molded articles for evaluation of the bending strength of each of the examples and comparative examples, produced as described in [6] above, was measured using a 68TM-30 manufactured by INSTRON in accordance with ISO 178 (JIS K7171). The distance between the fulcrums was set to 64 mm during the flexural strength measurement.

[0183] [7-4] Flexural modulus

[0184] The flexural modulus of the molded articles for evaluation of the flexural modulus of each of the examples and comparative examples, produced as described in [6] above, was measured using a 68TM-30 manufactured by INSTRON in accordance with ISO 178 (JIS K7171). The flexural modulus was measured at a distance of 64 mm between support points.

[0185] These results are summarized together with the compositions of the molding materials obtained in the above-mentioned examples and comparative examples and the complex viscosities at 180°C. Figure 1 middle.

[0186] In addition, Figure 1 In the table, the numerical values ​​of the constituent components represent the content in the molding material, and the unit is mass %. In addition, polypropylene (H700 manufactured by PRIME POLYMER, melting point: 165°C) is represented as "polypropylene", and polylactic acid (TERRAMAC TE-2000 manufactured by Unitika, melting point: 160°C) is represented as "polylactic acid". Figure 1 The complex viscosity shown is the complex viscosity at 180°C and is determined by the following measurement. Specifically, the measurement was performed using Pheosol-G3000 (manufactured by UBM) under the following conditions: starting temperature: 100°C, step temperature: 1°C, ending temperature: 200°C, heating rate: 5°C / min, strain control: 0.1 degree, frequency: 1 Hz, automatic control: on, waveform: sine wave, continuous excitation: on, averaging times: 3, and weighting control: off. The lower plate was vibrated with a 1 mm thick sample sandwiched between the parallel plates. Furthermore, in the molded articles of each of the examples, polyurethane was included in a state compatible with polypropylene or polylactic acid. In other words, the polyurethane fibers used as the raw material for the molding material did not maintain a fibrous state in the molded articles of each of the examples due to their compatibility with polypropylene. In contrast, the cellulose fibers, acrylic fibers, and polyester fibers used as the raw materials for the molding materials in the molded articles of each of the examples maintained a fibrous state even in the produced molded articles.

[0187] according to Figure 1 It can be seen that excellent results were obtained in the examples, whereas no satisfactory results were obtained in the comparative examples.

[0188] Molding materials were produced in the same manner as in the aforementioned Examples, except that the average length of the cellulose fibers contained in the molding material was varied to be 50 μm to less than 3 mm, the average diameter of the cellulose fibers was varied to be 3 μm to less than 100 μm, the average length of the polyurethane fibers was varied to be 50 μm to less than 3 mm, the average diameter of the polyurethane fibers was varied to be 3 μm to less than 100 μm, and the number average molecular weight of the polyurethane constituting the polyurethane fibers was varied to be 20,000 to 300,000. These materials were evaluated in the same manner as above, and the same results as above were obtained.

Claims

1. A molding material, characterized in that: The molding material contains cellulose fibers, a resin that melts at 200° C. or less, and polyurethane. The complex viscosity of the molding material at 180° C. is 3000 Pa·s or more and 147000 Pa·s or less.

2. The molding material according to claim 1, characterized in that The resin is at least one selected from the group consisting of polypropylene and polylactic acid.

3. The molding material according to claim 1, characterized in that The sum of the content of the resin and the content of the polyurethane is 25.0% by mass or more and 91.0% by mass or less.

4. The molding material according to claim 1, characterized in that The average length of the cellulose fibers is 50 μm or more and less than 3 mm.

5. The molding material according to claim 1, characterized in that The average diameter of the cellulose fibers is 3 μm or more and less than 100 μm.

6. A molded body, characterized in that The molding material is composed of any one of claims 1 to 5.

7. A method for producing a molded body, characterized in that: The molding material according to any one of claims 1 to 5 is molded while being heated to a temperature at which the resin melts.

8. The method for producing a molded body according to claim 7, characterized in that: The heating temperature of the molding material is 120° C. or higher and 190° C. or lower.

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