Resin composition, its manufacturing method, and method for improving strength of resin composition

Abstract

To provide a method for producing a resin composition which has enhanced strength and is blended with a plant-derived fiber, and a method for producing a resin composition which can eliminate a step of evaporating moisture of a plant-derived fiber.SOLUTION: A resin composition contains a plant extract residue, a plant-derived fiber, and a thermoplastic resin. A method for producing a resin composition includes mixing a plant extract residue, a plant-derived fiber, and a thermoplastic resin, drying an obtained mixture, molding the dried matter, and obtaining a molding, in which the plant extract residue is preferably in a hydrous state.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a resin composition having high strength obtained by blending a residue from a plant extract, and a method for producing the same. [Background technology]

[0002] Resin compositions (plastics) have the advantage of being easily moldable, but have the disadvantage of being brittle. To improve the mechanical strength of resin compositions, cellulose fibers such as cellulose nanofibers are blended into the resin.

[0003] For example, Patent Document 1 listed below discloses an invention of a resin molded body that is made of a cellulose fiber-dispersed resin composite material in which cellulose fibers are dispersed in a resin, and has a thickness of 0.1 mm or more, in which the cellulose fiber content is 1% by mass or more and less than 70% by mass, and in which, when the length-weighted average fiber length of the cellulose fibers measured under specified measurement conditions is LL and the number-average fiber length is LN, LL and LN satisfy a specified formula, and this resin molded body can achieve excellent mechanical properties despite having thin-walled portions.

[0004] Furthermore, Patent Document 2 below discloses an invention of nano-sized cellulose fibers obtained by defibrating a cellulose fiber-containing material derived from a plant or microorganism so that the average fiber diameter is 4 to 3000 nm, and further discloses that the nano-sized cellulose fibers are incorporated into a resin and the composition is molded into a resin-containing molded body. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2020-193263 A [Patent Document 2] Japanese Patent Publication No. 2020-116817 Summary of the Invention [Problem to be solved by the invention]

[0006] Cellulose nanofibers are produced by grinding plant-derived fibers such as pulp in water, but because they contain a high water content of over 95 wt%, the water must be evaporated before they can be mixed with resin, which places a burden on the manufacturing process. When plant-derived fibers are crushed in molten resin to eliminate the need to evaporate the water, the fibers can become entangled, and the resin can be adsorbed onto them, forming flake-like foreign matter.

[0007] Therefore, an object of the present invention is to provide a resin composition with increased strength, and further to provide a method for producing a resin composition containing plant-derived fibers, which can eliminate the step of evaporating the moisture from the plant-derived fibers. [Means for solving the problem]

[0008] A method for producing a resin composition according to one embodiment of the present invention is characterized in that a plant extract residue, plant-derived fibers, and a thermoplastic resin are mixed together, the resulting mixture is dried, and the dried product is molded to obtain a molded product.

[0009] In the above embodiment, it is preferable to dry the components while mixing them together, and it is also preferable to mix the components in a blending ratio of 2 to 20 mass% of the plant extract residue, 5 to 20 mass% of the plant-derived fiber, and 60 to 93 mass% of the thermoplastic resin.

[0010] In the above embodiment, the plant extract residue is preferably in a water-containing state, and specifically, the water content is preferably 50 to 85% by mass.

[0011] In the above embodiment, the plant extract residue preferably contains starch, and specifically, the starch content is preferably 2 to 50 mass %.

[0012] In the above embodiment, the plant extract residue is preferably green tea leaves or barley tea leaves.

[0013] In the above embodiment, the plant-derived fiber is preferably an insoluble dietary fiber, specifically, one or more types selected from the group consisting of cellulose, hemicellulose, lignin, chitin, and chitosan.

[0014] In the above embodiment, the plant-derived fiber preferably has a moisture content of 20% by mass or less.

[0015] In the above embodiment, the thermoplastic resin is preferably a resin that can be molded at 230°C or less, and specifically, is preferably one or more types selected from the group consisting of polystyrene resin, ABS resin, polyethylene resin, EVA resin, polypropylene resin, polyvinyl chloride resin, PVA resin, PBAT resin, PBS resin, PLA resin, PHBH resin, PHA resin, and thermoplastic elastomer.

[0016] In the above embodiment, it is preferable that a dispersion improver is further contained.

[0017] The present invention relates to a resin composition containing a plant extract residue, plant-derived fibers, and a thermoplastic resin.

[0018] The present invention can improve the strength of a resin composition by mixing plant extract residue, plant-derived fibers, and a thermoplastic resin, drying the resulting mixture, and molding the dried product to obtain a molded product. DETAILED DESCRIPTION OF THE INVENTION

[0019] A resin composition (hereinafter referred to as the present resin composition) as one embodiment of the present invention will be described below, although the present invention is not limited to this embodiment.

[0020] The resin composition contains a plant extract residue, plant-derived fibers, and a thermoplastic resin.

[0021] (Plant extraction residue) The plant extraction residue is the residue remaining after extraction or squeezing of the leaves, stems, etc. of a plant using water, alcohol, or the like as a solvent, and it is preferable to use the extraction residue discarded in the production of beverages, etc. More specific examples include tea leaf residues (so-called used tea leaves) of green tea, oolong tea, black tea, etc., coffee bean residues (so-called coffee grounds) of coffee, etc., barley residues (so-called barley tea leaves) of barley tea, etc., brown rice residues (so-called brown rice tea leaves) of brown rice tea, etc., buckwheat residues (so-called brewer's lees) of beer, etc., apple pomace, potato pomace, grape pomace, etc.

[0022] The plant extract residue is preferably in a hydrous state, specifically, a moisture content of 50 to 85% by mass, particularly 60 to 85% by mass, and even more preferably 65 to 80% by mass. Extraction residue discarded in the production of beverages and the like often contains a high moisture content of 85% by mass or more, so it is preferable to adjust the moisture content to the above range by hot air drying, dehydration, or the like. Adjusting the moisture content of the plant extract residue in advance has the advantages of facilitating production and shortening production time in the production method described below, making the plant extract residue easier to store and handle, and ensuring uniform quality of the molded product. The plant extract residue preferably contains starch, and the starch content is preferably 2 to 50 mass%, particularly 4 to 45 mass%, and even more preferably 10 to 40 mass% in terms of dry solid content.The starch content in the resin composition is preferably 0.2 to 15 mass%, particularly 0.5 to 10 mass%, and even more preferably 1 to 5 mass% in terms of dry solid content. Starch refers to polysaccharides, for example, those with 10 or more sugars. The starch content can be adjusted, for example, by adding starch or changing the type and location of the plant extract residue. The starch content can also be measured by known methods, such as enzymatic methods. The sample is treated with α-amylase and glucoamylase to break it down into glucose, which is then quantified.

[0023] As the starch-containing plant extraction residue, barley tea leaves, brown rice tea leaves, buckwheat residue, brewer's lees, and potato pomace are preferred from the viewpoints of moisture content and starch content.

[0024] (Plant-derived fiber) Plant-derived fibers are fibers derived from plants such as vegetables and trees, and are found in, for example, grains, vegetables, beans, mushrooms, fruits, seaweed, wood, straw, bamboo, hemp, kenaf, and climbing plants. As the plant-derived fiber, insoluble dietary fiber is preferred, and insoluble dietary fiber includes wood, straw, bamboo, hemp, etc., as well as pulp or recycled pulp obtained therefrom. More specifically, the insoluble dietary fiber includes cellulose, hemicellulose, lignin, chitin, chitosan, etc., and one or more types selected from these are preferred.

[0025] The plant-derived fiber preferably has a low moisture content, specifically, a moisture content of 20% by mass or less, particularly 19% by mass or less, and even more preferably 18% by mass or less. The lower limit is not particularly limited, but is preferably 5% by mass or more. Furthermore, the difference in moisture content between the plant extract residue and the plant-derived fiber is preferably 30 to 90% by mass, particularly 40 to 85% by mass, and even more preferably 45 to 80% by mass.

[0026] (thermoplastic resin) The thermoplastic resin is a resin that can be melted and molded by applying heat, and is preferably a resin that can be molded at, for example, 230° C. or less, particularly 220° C. or less, and even more preferably 210° C. or less. Specific examples include polystyrene resin, ABS resin, polyethylene resin, EVA resin, polypropylene resin, polyvinyl chloride resin, PVA resin, PBAT resin, PBS resin, PLA resin, PHBH resin, PHA resin, and thermoplastic elastomer, and one or more types selected from these are preferred.

[0027] (Other ingredients) The resin composition may optionally contain components other than the plant extract residue, plant-derived fibers, and thermoplastic resin, such as one or more additives including a dispersion improver, plasticizer, compatibilizer, stabilizer, antioxidant, light stabilizer, UV absorber, curing agent, crosslinking agent, lubricant, and antistatic agent. Colorants such as dyes and pigments may also be added.

[0028] The blending ratio of these is not particularly limited, and can be appropriately adjusted depending on the application. The dispersion improver used here improves the dispersibility of the plant extract residue and plant-derived fibers in the thermoplastic resin and increases the strength of the resin, and examples of suitable dispersion improvers include titanium dioxide and calcium carbonate.

[0029] (mixing ratio) The blending ratio of each component is preferably 2 to 20 mass% plant extract residue, 5 to 20 mass% plant-derived fiber, and 60 to 93 mass% thermoplastic resin on an bone-dry basis, more preferably 2 to 15 mass% plant extract residue, 6 to 17 mass% plant-derived fiber, and 65 to 92 mass% thermoplastic resin, and particularly preferably 2 to 10 mass% plant extract residue, 7 to 15 mass% plant-derived fiber, and 70 to 91 mass% thermoplastic resin.

[0030] <Method of manufacturing resin composition> The method for producing a resin composition (hereinafter referred to as the present production method) is a production method characterized by mixing a plant extract residue, plant-derived fibers, and a thermoplastic resin, drying the resulting mixture, and molding the dried product to obtain a molded product.

[0031] (Mixing process) In this production method, first, the above components are mixed to obtain a mixture. This mixing can be carried out by simply blending the plant extract residue, plant-derived fibers, thermoplastic resin, and, if necessary, other components in appropriate proportions, and can be carried out by mechanical kneading, although the method is not particularly limited. For example, this can be done using a single-screw extruder, twin-screw extruder, Henschel mixer, Banbury mixer, kneader mixer, Brabender mixer, calendar roll, etc. It is preferable to mix the components while pulverizing them.

[0032] The preferred mixing ratio of each component in this mixture is the same as the mixing ratio of the present resin composition described above.

[0033] (drying process) The mixture is then dried to obtain a dry product. This drying may be carried out in any manner as long as it is possible to evaporate the water content from the mixture. It is preferable to carry out the drying while the above-mentioned mixing is being carried out, that is, the mixing step and the drying step are carried out simultaneously. To dry the components while mixing, for example, a Banbury mixer is used, the temperature inside the mixer is set to 100°C or higher, preferably in the range of 100 to 180°C, and the mixer is operated, whereby the components are dried and mixed while being pulverized. After drying, the dried product is kneaded to form a clay-like substance, i.e., a mochi-like substance, until the moisture content is preferably 5% by mass or less, more preferably 3% by mass or less, and particularly preferably 1% by mass or less.

[0034] (molding process) Finally, the clay is molded. For example, the clay material can be put into an extruder, kneaded, and extruded from a nozzle in the form of a wire, which can then be cut to an appropriate length and made into pellets. Other known molding methods can be used, such as extrusion molding, injection molding, blow molding, press molding, calendar molding, T-die molding, inflation molding, compression molding, pipe extrusion molding, vacuum molding, etc. These molding methods can be used with the clay itself, or with crushed clay or molded into pellets.

[0035] (Application) Since the resin composition contains plant extract residue, plant-derived fibers, and thermoplastic resin, it becomes a high-strength resin with increased strength and can be suitably used for applications requiring strength. Furthermore, if the plant extract residue contains starch, the strength will be further increased due to the effect of the starch. In this manufacturing method, if the plant extract residue is in a hydrated state, when it is mixed with the plant-derived fiber and thermoplastic resin, the water contained in the plant extract residue will loosen the plant-derived fiber appropriately while mixing, eliminating the need to crush the plant-derived fiber in water beforehand and simplifying the manufacturing process by eliminating the manufacturing step of crushing the fiber in water.

[0036] The resin composition can be molded into pellets, for example, which can then be melted and poured into a mold to form a resin molded article. The resin molded article can be suitably used for, for example, transport materials, construction and furniture materials, and housing applications. Examples of applications for transport materials include pallets, containers, dollies, trays, and other transport materials. Examples of applications for construction and furniture materials include interior and exterior wall materials, roofing materials, tiles, doors, and other residential building materials, as well as furniture such as desks and chairs. Examples of applications for housings include housings for electronic devices, home appliances, and other electrical products, as well as containers and packaging for food and miscellaneous goods.

[0037] In this specification, when the expression "X to Y" (X and Y are any numbers) is used, it includes the meaning of "X or more and Y or less", as well as "preferably larger than X" and "preferably smaller than Y", unless otherwise specified. [Example]

[0038] Examples of the present invention will be described below, but the present invention is not limited to these examples.

[0039] (Strength evaluation test) The following components were blended in the appropriate proportions shown in Table 1, and resin compositions of Examples 1 to 4 and Comparative Examples 1 and 2 were prepared by the manufacturing method described below.

[0040] <Plant extraction residue> Barley tea leaves, which are the extraction residue from the production of "Healthy Mineral Barley Tea" (manufactured by Ito En Co., Ltd.), were used as the plant extraction residue. The moisture content of these barley tea leaves was 75% by mass, and the starch content was 30% by mass in terms of dry solid content. The moisture content was measured using an infrared moisture meter (Kett Electric Laboratory Co., Ltd.), and the starch content was measured using a total starch analysis kit (AA / AMG) (manufactured by Megazyme Co., Ltd.).

[0041] <Plant-derived fiber> Pulp (manufactured by PT TEL Co., Ltd.) was crushed to 7 mm or less using a mixer to prepare the plant-derived fiber. The moisture content of this pulp was 7.5% by mass. The moisture content was measured using an infrared moisture meter (Kett Electric Laboratory Co., Ltd.).

[0042] <Thermoplastic resin> As the thermoplastic resin, polypropylene resin (manufactured by SunAllomer Co., Ltd.) was used.

[0043] <Manufacturing method> The plant extract residue, plant-derived resin, and thermoplastic resin were mixed in the proportions shown in Table 1, and then placed in a kneader mixer (manufactured by Toshin Corporation) with the internal temperature set to 120°C. The mixture was pulverized and dried while being mixed. The thermoplastic resin was then melted by the heat generated during mixing, and the mixture was kneaded into a mochi-like shape. The kneaded material was charged into the hopper of a twin-screw extruder, and while being kneaded, it was extruded from the nozzle in the form of a wire, which was then cut into pellets to produce a resin composition in the form of pellets. This resin composition was melted at 180°C and poured into a mold to prepare a dumbbell-shaped test piece. In addition, Comparative Example 1 could not be molded.

[0044] <Flexural modulus measurement> Using test pieces of the resin compositions of Examples 1 to 4 and Comparative Example 2, the flexural modulus was measured in accordance with JIS K7171. From the measurement results of the flexural modulus, strength was evaluated using the following five-level index. The results are shown in Table 1. Note that Reference Example 1 shows the flexural modulus in the case of using only the thermoplastic resin. 1: Flexural modulus is 929 or less or cannot be measured 2: Flexural modulus 930-939 3: Flexural modulus 940-949 4: Flexural modulus 950-959 5: Flexural modulus of 960 or more

[0045] [Table 1]

[0046] (Strength evaluation test results) The results of the strength evaluation test showed that Examples 1 to 4 had a strength rating of 3 or higher, which was good. These examples had a plant extract residue blending ratio of 2 to 20% by mass and a plant-derived fiber blending ratio of 5 to 20% by mass, and it was found that blending ratios within these ranges were suitable. Examples 2 and 3 received high ratings in the strength evaluation test.

[0047] (Comprehensive evaluation test) The blending ratio of each component in Example 2 was fixed, and Examples 5 to 15 were prepared by varying the water content, the starch content in the resin composition, and the type of plant extract residue, and a comprehensive evaluation test was performed on the resin compositions.

[0048] (Moisture content change) Examples 5 to 9 were produced by changing the moisture content of the barley tea leaves used in Example 2 to the ratios shown in Table 2. The moisture content of the barley tea leaves was measured using an infrared moisture meter (Kett Electric Laboratory Co., Ltd.), and the moisture content was changed by evaporating the water using a hot air dryer.

[0049] (Starch content changed) Examples 10 to 13 were produced by changing the starch content of the barley tea leaves used in Example 2 so that the starch content in the resin composition would be as shown in Table 2. The starch content of the barley tea leaves was measured using a total starch analysis kit (AA / AMG) (manufactured by Megazyme Co., Ltd.). The starch content was also changed by changing the part of the barley tea leaves or adding "starch, corn-derived" (manufactured by Fujifilm Wako Pure Chemical Corporation).

[0050] (Plant extract residue change) Examples 14 and 15 were produced by replacing the barley tea leaves used in Example 2 with green tea leaves, which are the extraction residue from the production of "Oi Ocha Green Tea" (manufactured by Ito En Co., Ltd.). The water content of these green tea leaves was 75% by mass. The starch content in the resin composition is as shown in Table 2. The starch content was changed by adding "starch, corn-derived" (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.).

[0051] (comprehensive evaluation) Examples 5 to 15 were comprehensively evaluated in terms of "moldability," "uniformity of resin composition," and "light resistance (color loss)."

[0052] <Moldability> The moldability was evaluated by pouring the resin composition into a flat mold having a thickness of 5 mm, cutting the composition into a piece having a square of 10 cm, and visually checking the number of lumps formed on the piece, and using the following index. 1: Much worse than Reference Example 1 (10 or more) 2: Worse than Reference Example 1 (5-9 pieces) 3: Slightly worse than Reference Example 1 (1-4 pieces) 4: Equivalent to or better than Reference Example 1 (no clumps formed)

[0053] <Uniformity of resin composition> The uniformity of the resin composition was evaluated by pouring the resin composition into a 5 mm thick flat mold, cutting it into a 10 cm square piece, and visually checking the number of irregularities that occurred on the piece, and using the following index. 1: Much worse than Reference Example 1 (10 or more) 2: Worse than Reference Example 1 (5-9 pieces) 3: Slightly worse than Reference Example 1 (1-4 pieces) 4: Equivalent to or better than Reference Example 1 (no unevenness formed)

[0054] <Lightfastness (color fading)> Light resistance (color fading) was evaluated visually using the following index after storing the sample under continuous irradiation of 10,000 lux for 14 days. 1: The color has faded significantly compared to immediately after production. 2: The color has faded compared to immediately after production. 3: The color has faded slightly compared to immediately after production. 4: Same as immediately after production or no color fading

[0055] [Table 2]

[0056] (Comprehensive evaluation test results) The strength score was added to the scores for moldability, uniformity of the resin composition, and light resistance, and a total was calculated. All of Examples 5 to 15 have strength and are practically acceptable, but Example 5, which has a low moisture content, and Example 9, which has a high moisture content, have poorer moldability. From this perspective, it can be said that the moisture content of the plant extract residue is preferably 50 to 85% by mass. Furthermore, the homogeneity of the resin composition was inferior to that of Example 10, which had a low starch content, or Example 13, which had a high starch content. From this viewpoint, it can be said that the starch content in the resin composition is preferably 0.2 to 15 mass%. Examples 14 and 15, which used used green tea leaves, were inferior in light resistance to those using used barley tea leaves.

[0057] (Addition of dispersion improver) The blending ratio of the thermoplastic resin in Example 2 was changed to 75% by mass, and calcium carbonate (manufactured by Calfine Corporation) as a dispersion improver was added so that the blending ratio became 10% by mass.

[0058] (Results of adding dispersion improver) As a result of changing the blending ratio of resin and adding a dispersion improver, the strength was over 960, and the strength was good even when a dispersion improver was added.

Claims

1. A method for producing a resin composition containing 0.2 to 15 mass% starch, comprising mixing 2 to 20 mass% of plant extract residue, which is green tea leaves or barley tea leaves, 5 to 20 mass% of plant-derived fiber, and 60 to 93 mass% of thermoplastic resin, drying the resulting mixture, and molding the dried product to obtain a molded product.

2. The method for producing a resin composition according to claim 1 , wherein the drying is carried out while the mixing is being carried out.

3. The method for producing a resin composition according to claim 1 or 2, wherein the plant extract residue is in a water-containing state.

4. The method for producing a resin composition according to claim 3, wherein the water content of the plant extract residue is 50 to 85% by mass.

5. The method for producing a resin composition according to any one of claims 1 to 4, wherein the plant extract residue contains starch.

6. The method for producing a resin composition according to claim 5, wherein the starch content of the plant extract residue is 2 to 50 mass% in terms of dry solid content.

7. The method for producing a resin composition according to any one of claims 1 to 6, wherein the plant-derived fiber is an insoluble dietary fiber.

8. 8. The method for producing a resin composition according to claim 7, wherein the insoluble dietary fiber is one or more selected from the group consisting of cellulose, hemicellulose, lignin, chitin, and chitosan.

9. The method for producing a resin composition according to any one of claims 1 to 8, wherein the plant-derived fiber has a moisture content of 20% by mass or less.

10. The method for producing a resin composition according to any one of claims 1 to 9, wherein the thermoplastic resin is a resin that can be molded at 230°C or less.

11. The thermoplastic resin is one or more selected from the group consisting of polystyrene resin, ABS resin, polyethylene resin, EVA resin, polypropylene resin, polyvinyl chloride resin, PVA resin, PBAT resin, PBS resin, PLA resin, PHBH resin, PHA resin and thermoplastic elastomer. The method for producing a resin composition according to claim 10.

12. The method for producing a resin composition according to any one of claims 1 to 11, further comprising a dispersion improver.

13. A resin composition containing 0.2 to 15 mass% starch, which comprises plant extract residue which is green tea leaves or barley tea leaves, plant-derived fibers, and a thermoplastic resin.

14. A method for improving the strength of a resin composition containing 0.2 to 15 mass% starch, comprising mixing 2 to 20 mass% of plant extract residue, which is green tea leaves or barley tea leaves, 5 to 20 mass% of plant-derived fiber, and 60 to 93 mass% of thermoplastic resin, drying the resulting mixture, and molding the dried product to obtain a molded product.

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