Manufacturing method of molded products

Abstract

To provide a molding material that can be brought closer to carbon neutral and to provide a method for producing the molding material.SOLUTION: Provided is a molding material and a method for producing the same in which a mixture of a plant itself or processed material thereof powder by 70 to 80 mass%, a cornstarch powder by 10 to 30 mass%, and a cellulose or resin-mixed cellulose powder by 0 to 10 mass% is put into an extruder and heated, and thereby kneading the plant itself or processed material thereof powder and the cellulose or resin-mixed cellulose powder with the cornstarch as a binder, and the molding material extruded from the extruder is formed into pellet-shape.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a molding material made of plant-derived materials. Product It relates to a manufacturing method. [Background technology]

[0002] Conventionally, from the viewpoint of environmental protection, namely carbon neutrality, in which the emission and absorption of carbon dioxide cancel each other out, various molded products have been developed by mixing petroleum-based synthetic resins with plant-derived powders (e.g., powders of coffee grounds, bran, and soybean husks) (see, for example, Patent Documents 1 to 3).

[0003] By adopting this constitution, the amount of synthetic resin used in the molded product can be reduced, thereby contributing to environmental protection. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2012-224665 A [Patent Document 2] JP 2016-050210 A [Patent Document 3] JP 2020-059830 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, since the above molded products use synthetic resins, there is a limit to how carbon neutral they can be.

[0006] In addition, biomass plastics made from raw materials such as starch have also been developed as synthetic resins, but the process of producing such biomass plastics from starch and other raw materials is complicated and expensive.

[0007] The present invention has been made in view of the above-mentioned points, and its object is to provide a molding method that can approach carbon neutrality. Product The present invention aims to provide a manufacturing method thereof. [Means for solving the problem]

[0008] The inventors of the present application conducted various experiments with the aim of creating a molding material using only plant-derived materials as much as possible, without using synthetic resins (including biomass plastics) as binders. As a result, they discovered that a molding material can be constructed by using cornstarch directly as a substitute for synthetic resin (binder) and controlling the heating temperature, etc. That is, while there is a known technique for kneading cornstarch or the like with a synthetic resin and using the synthetic resin as a binder to create a molding material, in the present invention, a molding material is created using cornstarch itself as a binder without using a synthetic resin.

[0009] That is, according to the present invention The method for producing a molded product involves feeding a mixture of 70 to 80% by mass of a powder of a plant itself or a processed material thereof having a particle size of 150 μm or less, 10 to 30% by mass of a powder of cornstarch having a particle size of 50 μm or less, and 0 to 20% by mass of a powder of cellulose or resin-mixed cellulose having a particle size of 100 μm or less into an extruder and heating it to 180° C. to 190° C. to knead the other powders using the cornstarch as a binder, forming the molding material extruded from the extruder into pellets, feeding the molding material formed into pellets into an injection molding machine, melting it by heating, and injecting it into the cavity of a mold connected to the injection molding machine, and then removing the solidified molded product from the mold, and thus forming a pattern on the surface of the molded product according to the flow of the molten material during the heating and melting, which is made up of the powder of the plant itself or a processed material thereof, the powder of the cellulose or resin-mixed cellulose, and the cornstarch, as it is, as the surface pattern of the molded product. It is characterized by the following. There are various types of plants themselves or processed materials thereof, for example, wheat bran, bamboo, coffee grounds, rice bran, etc. The types of plants themselves or processed materials thereof to be mixed may be one type or multiple types. According to the present invention, the molding material is made of inexpensive cornstarch, which is a processed plant product, as a binder, and the cornstarch, a powder of a plant itself or a processed material thereof, and a powder of cellulose or resin-mixed cellulose. Therefore, a molding material derived from 100% plants (almost 100% when resin-mixed cellulose is used) can be produced inexpensively without using synthetic resins (including biomass plastics) (almost no synthetic resins are used when resin-mixed cellulose is used). Manufacturing It is possible. When resin-mixed cellulose is used, a small amount of synthetic resin is mixed in, but the amount is so small that the synthetic resin hardly functions as a binder. Furthermore, according to the present invention, since cellulose, which is a dietary fiber, is kneaded, the strength of the molding material, which is 100% plant-derived (almost 100% plant-derived when resin-mixed cellulose is used), can be effectively increased.

[0011] According to the present invention, molding Product It is possible to increase the proportion of the powder of the plant itself or its processed material that can be included in the composition, thereby achieving more effective environmental protection.

[0012] According to the present invention, molding Product The blending ratio of corn starch contained in the food product is low, and this allows the blending ratio of the powder of the plant itself or its processed material to be increased, thereby achieving more effective environmental protection.

[0014] The heat melting temperature of cornstarch 180℃~190℃ By setting the temperature within this range, the cornstarch can be melted to have the desired fluidity (fluidity suitable for uniformly kneading the powder of the plant itself or its processed material with the powder of cellulose or resin-mixed cellulose), and the powder of the plant itself or its processed material is not burned, resulting in good molding. Product can be obtained.

[0015] the above According to the manufacturing method, the surface pattern of the molded product produced by using powder of the plant itself or its processed material, powder of cellulose or resin-mixed cellulose, and cornstarch can be made different for each molded product, thereby giving each molded product a distinctive (individual) design. Effect of the Invention

[0016] According to the present invention, it is possible to provide a molding material which is 100% or nearly 100% plant-derived and can approach carbon neutrality without using any or almost no synthetic resin. [Brief description of the drawings]

[0017] [Figure 1]FIG. 1 is a flow chart showing a manufacturing process for a molding material according to Example 1A. [Diagram 2] FIG. 2 is a schematic diagram showing a molding material manufacturing apparatus. [Diagram 3] FIG. 1 is a diagram showing the blending ratio of raw materials of a molding material according to Example 1A. [Figure 4] FIG. 1B is a diagram showing the blending ratio of raw materials of a molding material according to Example 1B. [Diagram 5] FIG. 1C is a flow diagram showing a manufacturing process for a molding material according to Example 1C. [Figure 6] FIG. 11 is a flow chart showing a manufacturing process of a molding material according to a second embodiment. [Figure 7] FIG. 11 is a flow chart showing a manufacturing process of a molding material according to a third embodiment. [Figure 8] FIG. 11 is a diagram showing the blending ratio of raw materials of a molding material according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. [First embodiment] The molded material in the first embodiment is produced by mixing powder of a plant itself or its processed material with powder of resin-mixed cellulose and powder of cornstarch, and then heating and melting this mixture using the cornstarch as a binder and molding it into pellets.

[0019] As the powder of the plant itself, for example, wheat bran powder, bamboo powder, etc., can be considered. As the powder of the processed plant material, rice bran, etc. can be considered. In either case, it is preferable to dry the material and reduce the particle size to 150 μm or less in the following mixing and molding steps.

[0020] The resin-mixed cellulose is a powder made by mixing cellulose (e.g., 40% by weight) which is a plant fiber, and polypropylene (e.g., 60% by weight). It is preferable that the particle size of this resin-mixed cellulose is 100 μm or less in the following mixing and molding processes.

[0021] Cornstarch is a powdered starch made from corn, and it is preferable for the particle size to be 50 μm or less in the mixing and molding steps described below.

[0022] The mixture of these powders is then fed into an extruder, where it is heated, kneaded and melted, and a pellet-like molding material is taken out.

[0023] The above molding materials do not use synthetic resins (including biomass plastics) (although they do contain small amounts of synthetic resins when resin-mixed cellulose is used) and are composed entirely of plant-derived materials, so they are almost completely biodegradable. In addition, there is no need to use expensive materials such as biomass plastics, so they can be produced inexpensively and are almost completely carbon neutral.

[0024] In addition, in this embodiment, since the molding material contains cellulose, which is a vegetable fiber, the mechanical strength of the molded product produced using this molding material can be improved.

[0025] (Example 1A) Fig. 1 is a flow diagram of a manufacturing process of a molded material according to Example 1A, and Fig. 2 is a schematic diagram showing a manufacturing apparatus for a molded material according to Example 1A.

[0026] To manufacture the molding material, wheat bran powder (particle size 100-150 μm), cornstarch powder (particle size 50 μm), and resin-mixed cellulose powder (particle size 100 μm) are prepared (steps 1-1, 1-2, 1-3) as shown in Fig. 1. The blending ratio of each raw material in this example is as shown in Fig. 3, that is, 70 mass% bran, 10 mass% resin-mixed cellulose, and 20 mass% cornstarch. All materials are used in powder form that has been thoroughly dried.

[0027] Next, the bran, corn starch, and resin-mixed cellulose in the above-mentioned mixing ratio are charged into the stirring mixer 10 shown in FIG. 2, and mixed and stirred by the stirring member 11 (step 2).

[0028] Next, the mixture mixed in the mixer 10 is introduced into the extruder 20, and the screw 25 with the helical ridge 23 is heated by the heater 27 while rotating in the cylinder 21, so that the cornstarch in the mixture is melted and the bran and resin-mixed cellulose are evenly kneaded with the melted cornstarch (step 3). The heating temperature at this time was found to be 180°C to 190°C, which is the temperature at which the cornstarch is melted to have the desired fluidity (fluidity suitable for evenly kneading the bran and resin-mixed cellulose). That is, according to various experiments by the inventors of the present application, if the melting temperature is 180°C or lower, sufficient melting is not performed, and the resin after molding does not become pellet-shaped and becomes crumbled. If the melting temperature is 190°C or higher, the cornstarch and bran are burned, and good pellets cannot be obtained.

[0029] Incidentally, the extruder 20 shown in FIG. 2 is a single-screw extruder having one screw 25. However, if a twin-screw extruder having two screws arranged in parallel and intermeshing with each other is used, the bran and resin-mixed cellulose can be more effectively kneaded evenly into the molten cornstarch (the same applies to each of the following examples).

[0030] The rod-shaped molded material is then discharged from a nozzle (not shown) provided near the extrusion end of the extruder 20, cut into short lengths with a cutter (not shown), and hardened to obtain pellet-shaped molded material (step 4). Through the above steps, the pellet-shaped molded material 30 according to the first embodiment is completed.

[0031] The molding material (pellets) 30 manufactured in the above manner is, for example, placed in an injection molding machine, heated and melted, and then injected into the cavity of a mold connected to the injection molding machine. It is then cooled and solidified, and a molded product formed into the shape (final shape) of various products is removed.

[0032] In this embodiment, the pattern that appears on the surface of the molded product formed according to the flow of the molten material injected into the cavity of the mold, which is made of the bran powder, the resin-mixed cellulose powder, and the cornstarch, is used as the surface pattern of the molded product. This makes it possible to make the surface pattern of the molded product that is made of the bran powder, the resin-mixed cellulose powder, and the cornstarch different for each molded product, and to give each molded product a unique (individual) design (the same applies to each of the following embodiments).

[0033] (Example 1B) The molded material of Example 1B is a molded material in which the mixing ratio of each raw material constituting the molded material of Example 1A has been changed, and the molding method is the same as that of Example 1A, so its explanation is omitted.

[0034] Fig. 4 is a diagram showing the blending ratio of bran powder (particle size 100-150 μm), resin-mixed cellulose powder (particle size 100 μm), and cornstarch powder (particle size 50 μm) used in Example 1B. As shown in the figure, the blending ratio of each raw material in Example 1B is 70 mass% bran, 20 mass% resin-mixed cellulose, and 10 mass% cornstarch. All materials are used in the form of powder that has been thoroughly dried.

[0035] In this embodiment, the blending ratio of cornstarch as a binder is reduced from 20% to 10% compared to the 1A embodiment, but the inventors' experiments confirmed that cornstarch can fully exert its effect as a binder if its blending ratio is 10% or more. If the blending ratio is less than this blending ratio, the effect as a binder decreases, and the molded product made using the manufactured pellets was not good. On the other hand, when the blending ratio of cornstarch is 30%, a good molded product was obtained. Therefore, it was confirmed by actually manufacturing a molded product that the blending ratio of cornstarch is preferably 10% or more, and more preferably in the range of 10% to 30%. It is considered that a good molded product can be obtained even if the blending ratio of cornstarch is 30% or more, but blending more cornstarch than necessary reduces the blending ratio of bran powder, which is not preferable for the purpose of making effective use of bran.

[0036] (Example 1C) 5 is a flow diagram of the manufacturing process of the molding material according to Example 1C. In this example, the manufacturing device for the molding material used is the same as the manufacturing device shown in FIG.

[0037] This embodiment differs from the above-mentioned 1A and 1B embodiments in that rice bran, which is a powder of processed plant material, is used instead of bran, which is a powder of the plant itself. To manufacture the molding material, rice bran powder (particle size 100 to 150 μm), resin-mixed cellulose powder (particle size 100 μm), and corn starch powder (particle size 50 μm) are prepared (steps 1-1, 1-2, 1-3). The blending ratio of each raw material in this embodiment is 70 mass% rice bran, 10 mass% resin-mixed cellulose, and 20 mass% corn starch. All materials are used in powder form that has been thoroughly dried.

[0038] Next, the rice bran, resin-mixed cellulose, and corn starch in the above-mentioned mixing ratio are charged into the stirring mixer 10 shown in FIG. 2, and mixed and stirred by the stirring member 11 (step 2).

[0039] Next, the mixture mixed in the mixer 10 is introduced into the extruder 20, and in the same manner as in the above-mentioned embodiment 1A, the rice bran and resin-mixed cellulose are evenly kneaded with the molten corn starch while melting the corn starch in the mixture (step 3). As described above, the heating temperature at this time is preferably 180°C to 190°C as a temperature at which the corn starch is melted to have the desired fluidity (fluidity suitable for evenly kneading the rice bran and resin-mixed cellulose). In addition, the extruder 20 shown in FIG. 2 is a single-screw type, but as described above, if a twin-screw type extruder is used, the rice bran and resin-mixed cellulose can be evenly kneaded with the molten corn starch more effectively.

[0040] Then, the rod-shaped molded material is extruded from the extruder 20 and cut to take out pellet-shaped molded material (Step 4). Through the above steps, the pellet-shaped molded material 30 according to Example 1C is completed.

[0041] The molding material (pellets) 30 produced as described above is also molded into a molded product using, for example, an injection molding machine, as described above.

[0042] Second Embodiment The molded material in the second embodiment is produced by mixing powder of the plant itself or its processed material with powder of cellulose and powder of cornstarch, and then heating and melting this mixture using the cornstarch as a binder and molding it into pellets.

[0043] In this embodiment, cellulose powder is used instead of the resin-mixed cellulose powder used in the first embodiment. Since cellulose powder is a plant fiber, it has the effect of improving the strength of the molded product, and it is effective to mix it.

[0044] As in the first embodiment, it is preferable to dry any of the materials and set the particle size to 150 μm or less in the mixing and molding processes. The specific particle size is the same as in the first embodiment, and the cellulose powder has the same particle size (100 μm or less) as the resin-mixed cellulose powder.

[0045] The mixture of these powders is then fed into an extruder, where it is heated, kneaded and melted, and a pellet-like molding material is taken out.

[0046] The molding material produced in this way does not use any synthetic resins (including biomass plastics) and is composed entirely of plant-derived materials, so it is completely biodegradable. In addition, there is no need to use expensive materials such as biomass plastics, so it can be produced inexpensively and is completely carbon neutral.

[0047] In addition, in this embodiment, since the molding material contains cellulose, which is a vegetable fiber, the mechanical strength of the molded product produced using this molding material can be improved.

[0048] (Second Example) Fig. 6 is a manufacturing process flow diagram of a molding material according to the second embodiment. In this embodiment, bran powder (particle size 100-150 μm), cellulose powder (particle size 100 μm), and cornstarch powder (particle size 50 μm) are prepared (steps 1-1, 1-2, 1-3). The blending ratio of each raw material in this embodiment is 70% by mass bran, 10% by mass cellulose, and 20% by mass cornstarch, or 70% by mass bran, 20% by mass cellulose, and 10% by mass cornstarch. All materials are used in the form of powder that has been thoroughly dried.

[0049] Next, the bran, cellulose and cornstarch in the above-mentioned blending ratio are put into the stirring mixer 10 shown in Fig. 2 and mixed and stirred by the stirring member 11 (step 2), and the mixed and stirred mixture is introduced into the extruder 20, and while melting the cornstarch in the mixture as described above, the bran and cellulose are uniformly kneaded into the melted cornstarch (step 3). The heating temperature at this time is preferably 180°C to 190°C, as in the first embodiment.

[0050] Then, the rod-shaped molding material discharged from the extruder 20 is cut into pellets, hardened, and removed (step 4). Through the above steps, the pellet-shaped molding material 30 according to the second embodiment is completed. The molding material (pellets) 30 manufactured as described above is molded into various product shapes (final shapes) by, for example, an injection molding machine.

[0051] Third Embodiment The molded material according to the third embodiment is made by mixing a powder of a plant itself or a processed material thereof with a powder of cornstarch, and then heating and melting the mixture using the cornstarch as a binder to mold it into a pellet shape. The powder of the plant itself or a processed material thereof and the powder of cornstarch are the same as those in the first embodiment.

[0052] This molding material does not use synthetic resins (including biomass plastics), and is composed of inexpensive cornstarch, which is a processed product of plants, as a binder, and the cornstarch and powder of the plant itself or its processed material, so that a 100% plant-derived molding material can be obtained. In addition, since it is composed of only 100% plant-derived materials, it is completely biodegradable, and there is no need to use expensive materials such as biomass plastics, so it can be manufactured inexpensively and can be completely carbon neutral. Unlike the first and second embodiments, this molding material does not use resin-mixed cellulose or cellulose, so it is not reinforced with plant fibers, but if the molded product does not require high strength or has a shape that can maintain its strength by providing a thickness, the use of resin-mixed cellulose or cellulose can be omitted as in this embodiment. This allows more effective use of the plant itself or its processed material.

[0053] (Third Example) Fig. 7 is a manufacturing process flow diagram of the molded material according to the third embodiment. To manufacture the molded material, bran powder (particle size 100-150 μm) and cornstarch powder (particle size 50 μm) are prepared (steps 1-1, 1-2) as shown in Fig. 7. The blending ratio of each raw material in this embodiment is as shown in Fig. 8, that is, bran 80 mass % and cornstarch 20 mass %. Sufficiently dried powders are used for both materials.

[0054] Next, the bran and cornstarch in the above-mentioned blending ratio are put into the stirring mixer 10 shown in Fig. 2, and mixed and stirred by the stirring member 11 (Step 2). Next, the mixture mixed in the mixing mixer 10 is introduced into the extruder 20, and while melting the cornstarch in the mixture in the same manner as above, the bran is evenly kneaded into the molten cornstarch (Step 3). The heating temperature at this time is the same as in the case of the 1A embodiment.

[0055] The rod-shaped molding material is then discharged from the extruder 20 and cut to obtain pellet-shaped molding material, which is then hardened and removed (step 4). Through the above steps, the pellet-shaped molding material 30 according to the third embodiment is completed. The molding material (pellets) 30 produced as described above is molded into various product shapes (final shapes) by, for example, an injection molding machine.

[0056] According to each of the above examples (Examples 1A to 3), the mixing ratio of powder of the plant itself or its processed material could be set to 70 to 80 mass %, so that the mixing ratio of powder of the plant itself or its processed material that can be included in the molding material can be increased.

[0057] Furthermore, according to each of the above Examples (Examples 1A to 3), the blending ratio of cornstarch could be set to 10 to 30 mass %, so that the blending ratio of cornstarch contained in the molding material can be reduced.

[0058] Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible within the scope of the claims and the technical ideas described in the specification and drawings. Any shape, structure, or material not directly described in the specification and drawings is within the scope of the technical ideas of the present invention as long as it has the functions and effects of the present invention. For example, the molding material may be foamed. In the above example, the mixed melt extruded from the extruder 20 is made into a pellet-shaped molding material, and then the pellets are fed into an injection molding machine to mold the desired molded product, but the mixed melt extruded from the extruder 20 may be directly molded into the desired molded product.

[0059] In addition, the embodiments and examples shown in the above description and in each drawing can be combined with each other as long as there is no contradiction in the purpose, configuration, etc. In addition, even a part of the contents of the above description and each drawing can be an independent embodiment and example, and the embodiments and examples of the present invention are not limited to one embodiment and example that combines the above description and each drawing. [Explanation of symbols]

[0060] 10 Mixing stirrer 20 Extruder 30 Pellets (molding material)

Claims

[Claim 1] 70 to 80% by mass of powder of the plant itself or its processed material with a particle size of 150 μm or less, 10 to 30% by mass of cornstarch powder having a particle size of 50 μm or less; 0 to 20% by mass of cellulose or resin-mixed cellulose powder with a particle size of 100 μm or less; The mixture is put into an extruder and heated to 180°C to 190°C, whereby the other powders are kneaded with the cornstarch as a binder, The molding material extruded from the extruder is formed into pellets, The molding material formed into pellets is fed into an injection molding machine, heated and melted, and injected to fill the cavity of a mold connected to the injection molding machine, and then the solidified molded product is removed from the mold, and a pattern made of powder of the plant itself or its processed material, powder of the cellulose or resin-mixed cellulose, and corn starch, which appears on the surface of the molded product in accordance with the flow of the molten material during the heating and melting, is used as the surface pattern of the molded product.

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