Molding material and method for producing same

Abstract

Provided are: a molding material with which it is possible to minimize the amount of starch as an edible component in conventional materials and maximize the content of pulp; and a method for producing same. This molding material contains pulp, starch, and polysaccharides extracted from seaweed.

Description

Molding material and its manufacturing method

[0001] The present invention relates to a molding material used in molding biodegradable molded articles and a method for producing the same.

[0002] The applicant has previously held technology for injection molding materials primarily composed of pulp and starch-based binders, such as that disclosed in Patent No. 2951933 (Patent Document 1). Products (containers, etc.) molded from the molding material disclosed in Patent Document 1 (hereinafter referred to as the "conventional material") have been well-received for their environmental friendliness.

[0003] Recently, the issue of food waste has come into the spotlight, and there is a strong desire to reduce edible components, particularly in Europe and the United States. From this perspective, there is a strong demand to reduce the amount of starch, an edible component, in conventional materials (the starch content in conventional materials is approximately 30% by mass).

[0004] Furthermore, containers molded from conventional materials can be used as paper packaging containers in the paper recycling process if the pulp content is 51% by mass or more, but from a sustainability perspective, there is also a demand to increase the pulp content as much as possible (for example, 70% by mass or more).

[0005] Patent No. 2951933

[0006] The present invention has been made to meet the above-mentioned demands, and aims to provide a molding material and a manufacturing method thereof that can reduce the amount of starch, an edible component in conventional materials, as much as possible and increase the pulp content as much as possible.

[0007] The gist of the present invention will be described.

[0008] A first aspect of the present invention relates to a molding material characterized by containing pulp, starch, and polysaccharides extracted from seaweed.

[0009] A second aspect of the present invention relates to a molding material comprising pulp, starch, and agar.

[0010] A third aspect of the present invention relates to the molding material of the second aspect, characterized in that it contains, as components other than water, 70% by mass or more of pulp, 10% by mass or less of starch, and 1% by mass or more of agar.

[0011] A fourth aspect of the present invention relates to the molding material of the third aspect, characterized in that it contains, as components other than water, 70% by mass or more and 80% by mass or less of pulp, 8% by mass or more and 10% by mass or less of starch, and 1% by mass or more and 12% by mass or less of agar.

[0012] A fifth aspect of the present invention relates to the molding material of the fourth aspect, which contains 8% by mass or more and 10% by mass or less of polyvinyl alcohol.

[0013] A sixth aspect of the present invention relates to the molding material according to any one of the second to fifth aspects, characterized in that the moisture content is 30% by mass or more and 60% by mass or less.

[0014] A seventh aspect of the present invention relates to a method for producing a molding material containing pulp, starch, and polysaccharides extracted from seaweed, characterized in that the pulp, starch, the polysaccharides, and water are mixed and kneaded.

[0015] An eighth aspect of the present invention relates to a method for producing a molding material containing pulp, starch, and agar, characterized in that the pulp, starch, agar, and water are mixed and kneaded.

[0016] A ninth aspect of the present invention relates to a method for producing a molding material according to the eighth aspect, characterized in that the molding material contains, as components other than water, 70% by mass or more of pulp, 10% by mass or less of starch, and 1% by mass or more of agar.

[0017] A tenth aspect of the present invention relates to a method for producing a molding material according to the eighth aspect, characterized in that the molding material contains, as components other than water, 70% by mass or more and 80% by mass or less of pulp, 8% by mass or more and 10% by mass or less of starch, and 1% by mass or more and 10% by mass or less of agar.

[0018] An eleventh aspect of the present invention relates to the method for producing a molding material according to the tenth aspect, characterized in that the molding material contains 8% by mass or more and 10% by mass or less of polyvinyl alcohol.

[0019] A twelfth aspect of the present invention relates to a method for producing a molding material according to any one of the eighth to eleventh aspects, characterized in that water is added and kneaded so that the moisture content is 30% by mass or more and 60% by mass or less.

[0020] Since the present invention is configured as described above, it provides a molding material and a manufacturing method thereof that has the same strength and water resistance after molding as conventional materials, but has a lower starch content and a higher pulp content than conventional materials.

[0021] A preferred embodiment of the present invention will be briefly described below, showing the operation of the present invention.

[0022] The inventors conducted various experiments to determine what would be the best auxiliary material to use in molding materials used to mold biodegradable molded articles, in order to reduce the starch content while increasing the pulp content as much as possible, and found that polysaccharides extracted from seaweed (such as agar) are preferable.

[0023] That is, by adding seaweed-extracted polysaccharides such as agar, even if the pulp content is, for example, about 70% by mass or more and the starch content is 10% by mass or less, the molded product of the present invention exhibits the same strength and water resistance as molded products made from conventional materials and is not harmful to the environment.In addition, although algae-extracted polysaccharides (agar) are an edible component, they contain almost no sugars (carbohydrates excluding dietary fiber), and are therefore unrelated to food waste that causes starvation.

[0024] Therefore, according to the present invention, it is possible to realize an environmentally friendly molding material that has the same strength and water resistance after molding as conventional materials, but has a low starch content, which can address the food waste problem, and has as high a pulp content as possible.

[0025] A specific example of the present invention will now be described.

[0026] This example is a molding material to be molded into a container or the like, and contains pulp, starch, and polysaccharides extracted from seaweed.

[0027] Specifically, pulp, starch, the polysaccharide, and water are mixed and kneaded, and then molded into a predetermined shape (for example, pellets or tablets).

[0028] As the pulp, natural fibers can be used. Examples include wood pulps such as paper pulp, dissolving pulp, mercerized pulp, and fluff pulp; non-wood pulps obtained from cotton, linter, flax, Manila hemp, sisal, bagasse, kenaf, straw, and the like; waste paper pulp obtained from waste paper; and crushed plant materials such as rice husks and wood flour. In addition, lyocell fibers obtained by refining natural cellulose and rayon fibers obtained by regenerating natural cellulose can also be used as natural fibers.

[0029] In this embodiment, wood pulp is used. In this embodiment, softwood pulp is used. However, hardwood pulp or a mixture of hardwood pulp and softwood pulp in a predetermined ratio may also be used. When hardwood pulp and softwood pulp are mixed, the ratio is set to 20:80 to 80:20. Preferably, it is 50:50.

[0030] As the starch, corn starch, potato starch, rice flour, etc. can be used. In this example, corn starch is used.

[0031] As the polysaccharide extracted from seaweed, agar, carrageenan, alginic acid, etc. can be suitably used, and those capable of gelling are particularly preferred. In this example, agar is used.

[0032] In this example, the ingredients other than water include 70% to 80% by mass of pulp, 8% to 10% by mass of starch, and 1% to 10% by mass of agar. In this example, to smooth the surface, the ingredients further include 8% to 10% by mass of polyvinyl alcohol.

[0033] In this embodiment, the moisture content is set to 30% by mass or more and 60% by mass or less.

[0034] The molding material of this embodiment can be obtained by adding water to a mixture of wood pulp, starch, agar, and polyvinyl alcohol and kneading (while heating) it until the moisture content is 30% by mass or more and 60% by mass or less.

[0035] If the moisture content (ratio of moisture to the total material) of the kneaded molding material (including pellets and tablets) is less than 30% by mass, the fluidity of the molding material will be significantly reduced, making molding difficult, which is not preferred. On the other hand, if the moisture content exceeds 60% by mass, molding will be difficult due to the low viscosity, and degassing and releasing water vapor during injection molding will take a long time, which will result in a long molding time and a decrease in production efficiency, which is also not preferred.

[0036] The molding material is filled into a heated injection mold or compression mold, and the added water is evaporated to remove the material, which is then dried and solidified, and the material is then removed to produce a molded product.

[0037] Since this embodiment is configured as described above, it is possible to realize an environmentally friendly molding material that has the same strength and water resistance after molding as conventional materials, but has a low starch content that can address the food waste problem, and has as high a pulp content as possible.

[0038] An experimental example that supports the effect of this embodiment will be described.

[0039] Experimental Example 1 As shown in Table 1, a molding material was prepared by blending predetermined amounts of agar, starch (corn starch), polyvinyl alcohol (PVA), and pulp (N for softwood pulp, L for hardwood pulp) to a predetermined moisture content (about 40%). The molding material was placed in an injection molding machine (NEX5000 manufactured by Nissei Plastic Industrial Co., Ltd.) to produce a JIS No. 1 test piece with a width of 10 mm and a thickness of 1 mm, as specified in JIS K7113. The tensile strength was evaluated using the test piece.

[0040] The tensile strength was measured at a pulling rate of 50 mm / min in accordance with JIS K 7113. The results of the tensile test are shown in the tensile stress and elongation columns of Table 1.

[0041]

[0042] The comparative example uses a molding material that does not contain agar, and is composed of 10% by mass of starch (corn starch), 10% by mass of PVA, and 80% by mass of softwood pulp (N wood). Experimental Examples 1, 2, and 3 are examples in which the agar content is 1.3%, 6.3%, and 10.7% by mass, respectively. Experimental Examples 4 and 5 are examples in which the type of agar is different from that of Experimental Example 2. Experimental Example 6 is an example in which hardwood pulp (L wood) is used as the pulp.

[0043] In addition, the agar used in all cases was Ina Agar from Ina Food Industry Co., Ltd. S-7 had a jelly strength (1.5% concentration (g / cm ３ ) is an edible agar with a jelly strength of 700 to 760, UP-37 is an edible agar (instant-dissolving agar) with a jelly strength of 670 to 730, and SL-700 is an industrial agar.

[0044] It was confirmed from Table 1 that the addition of agar improved the tensile stress compared to the comparative example. Note that there is no problem in use as long as the tensile stress is 15 MPa or more and the elongation is 1.5% or less. Therefore, it was confirmed that each of Experimental Examples 1 to 6 is a molding material that can realize molded products with sufficient strength, a low starch content as much as possible, and a high pulp content.

[0045] From the above, it was confirmed that a molding material (molded product) containing, as components other than water, 71.4% by mass or more and 78.9% by mass or less of pulp, 8.9% by mass or more and 9.9% by mass or less of starch, 1.3% by mass or more and 10.7% by mass or less of agar, and 8.9% by mass or more and 9.9% by mass or less of PVA is desirable.

[0046] [Experimental Example 2] Using the same test pieces as those in Comparative Example and Experimental Examples 1 to 3 in Table 1 (three samples for each example), water solubility was evaluated.

[0047] The water solubility was evaluated by stirring a test piece immersed in water for three days with a stirrer (MIXER SM-11 manufactured by Masuda Rika Kogyo Co., Ltd.), and measuring the amount separated by stirring (weight loss and rate of loss) from the weights before and after stirring (both weights after drying). The stirring speed was 20 rpm, the stirrer diameter was 8 mm, the stirrer length was 38 mm, and the water temperature was 25°C.

[0048] The results are shown in Table 2.

[0049]

[0050] From Table 2, it was confirmed that the decay rates of Experimental Examples 1 to 3 containing agar were equivalent to those of the Comparative Example not containing agar, and that the inclusion of agar did not impair water solubility and allowed for good decomposition.

[0051] From the above, it was confirmed that this example makes it possible to improve strength without deteriorating water solubility by including agar.

Claims

1. A molding material characterized by containing pulp, starch, and polysaccharides extracted from seaweed.

2. A molding material comprising pulp, starch, and agar.

3. The molding material according to claim 2, characterized in that it contains, as components other than water, 70% by mass or more of pulp, 10% by mass or less of starch, and 1% by mass or more of agar.

4. The molding material according to claim 3, characterized in that the components other than water are 70% by mass or more and 80% by mass or less of pulp, 8% by mass or more and 10% by mass or less of starch, and 1% by mass or more and 12% by mass or less of agar.

5. The molding material according to claim 4, characterized in that it contains 8% by mass or more and 10% by mass or less of polyvinyl alcohol.

6. The molding material according to any one of claims 2 to 5, characterized in that the moisture content is 30% by mass or more and 60% by mass or less.

7. A method for producing a molding material containing pulp, starch, and polysaccharides extracted from seaweed, characterized in that the pulp, starch, the polysaccharides, and water are mixed and kneaded.

8. A method for producing a molding material containing pulp, starch, and agar, characterized in that the pulp, starch, agar, and water are mixed and kneaded.

9. A method for producing a molding material according to claim 8, characterized in that the components other than water include 70% by mass or more of pulp, 10% by mass or less of starch, and 1% by mass or more of agar.

10. A method for producing a molding material according to claim 8, characterized in that the components other than water include 70% by mass or more and 80% by mass or less of pulp, 8% by mass or more and 10% by mass or less of starch, and 1% by mass or more and 10% by mass or less of agar.

11. The method for producing a molding material according to claim 10, characterized in that the molding material contains 8% by mass or more and 10% by mass or less of polyvinyl alcohol.

12. A method for producing a molding material according to any one of claims 8 to 11, characterized in that water is added and kneaded so that the moisture content is 30% by mass or more and 60% by mass or less.

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