Synthetic resin composition, synthetic resin molded article, and helmet

Abstract

The objective is to effectively utilize seashells as a resource while obtaining synthetic resin compositions and molded synthetic resin products that possess a unique texture and excellent strength. [Solution] The synthetic resin composition according to the present invention is a synthetic resin composition comprising a synthetic resin and crushed seashells in a mass ratio of 98:2 to 25:75, wherein the crushed seashells comprise finely crushed seashells with an average particle size of 1 μm or more and less than 100 μm, and coarsely crushed seashells with an average particle size of 100 μm or more and 3000 μm or less, in a mass ratio of 97:3 to 40:60. The synthetic resin molded article according to the present invention is formed by molding the synthetic resin composition into a predetermined shape.

Description

Technical Field

[0001] The present invention relates to a synthetic resin composition, a synthetic resin molded article, and a helmet.

Background Art

[0002] A large amount of shells are generated as waste from shellfish such as scallops, oysters, and akoya pearls, which are fishery resources. These shells are piled up on land while waiting for disposal by landfill or the like, but securing a deposition site and the impact on the environment are problems.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] As a measure for utilizing shells as resources, it has been proposed to obtain a synthetic resin molded article having excellent strength by adding ground scallop shells to a synthetic resin (see, for example, Patent Document 1). However, such a conventional synthetic resin molded article containing ground scallop shells exhibits the same texture as a normal synthetic resin molded article and does not have a unique texture in terms of appearance and touch.

[0005] The problem to be solved by the present invention is to effectively utilize shells as resources and obtain a synthetic resin molded article having a unique texture and excellent strength.

Means for Solving the Problems

[0006] The synthetic resin composition according to the present invention made to solve the above problems is a synthetic resin composition containing a synthetic resin and ground shells in a mass ratio of 98:2 to 25:75, The aforementioned crushed seashell material contains finely crushed seashell material with an average particle size of 1 μm or more and less than 100 μm, and coarsely crushed seashell material with an average particle size of 100 μm or more and 3000 μm or less, in a mass ratio of 97:3 to 40:60.

[0007] Here, average particle size refers to the volume-average diameter. The volume-average diameter is measured, for example, by laser diffraction / scattering. [Effects of the Invention]

[0008] By using the synthetic resin composition of the present invention having the above configuration, it is possible to effectively utilize seashells as a resource and obtain a synthetic resin molded product that has a unique texture and excellent strength. [Brief explanation of the drawing]

[0009] [Figure 1] A flowchart showing the manufacturing process of a synthetic resin composition according to one embodiment of the present invention. [Figure 2] A perspective view showing a helmet according to one embodiment of the present invention. [Modes for carrying out the invention]

[0010] The inventors of the present invention have conducted extensive research to solve the above problems and have discovered that by adding two types of crushed seashells with different particle sizes to a synthetic resin in a predetermined ratio, a synthetic resin composition with a unique texture and excellent strength can be obtained, leading to the present invention.

[0011] In other words, a synthetic resin composition according to one embodiment of the present invention is a synthetic resin composition comprising a synthetic resin and crushed seashells in a mass ratio of 98:2 to 25:75 (preferably 97:3 to 45:55), wherein the crushed seashells comprises finely crushed seashells with an average particle size of 1 μm or more and less than 100 μm (preferably 10 μm or more and 30 μm or less) and coarsely crushed seashells with an average particle size of 100 μm or more and 3000 μm or less, in a mass ratio of 97:3 to 40:60 (preferably 90:10 to 70:30).

[0012] Furthermore, in the synthetic resin composition according to one embodiment of the present invention, the coarsely ground seashell material preferably consists of a first coarsely ground material having an average particle size of 100 μm or more and less than 1000 μm, and a second coarsely ground material having an average particle size of 1000 μm or more and 3000 μm or less, and the mass ratio of the first coarsely ground material to the second coarsely ground material is preferably 1:99 to 99:1.

[0013] The synthetic resin composition according to this embodiment can be manufactured by a manufacturing method that includes a shell crushing step to obtain fine shell crushing and coarse shell crushing by crushing seashells, and a synthetic resin composition manufacturing step to obtain a synthetic resin composition by adding and mixing the fine shell crushing and coarse shell crushing to a molten synthetic resin (Figure 1).

[0014] The finely ground seashell material and the coarsely ground seashell material may be obtained in the seashell material production process by crushing the seashells separately, or the coarsely ground seashell material may be obtained by roughly crushing the seashells, and then the finely ground seashell material may be obtained by further crushing a portion of the coarsely ground seashell material. The coarsely ground seashell material can be obtained by crushing the seashells, for example, with a hammer crusher or jaw crusher, and the finely ground seashell material can be obtained by crushing the seashells or the coarsely ground seashell material, for example, with a roller mill or vibro mill, but is not limited to these. Alternatively, in the seashell material production process, seashell material of various particle sizes may be obtained by crushing the seashells with predetermined means, and the finely ground seashell material and the coarsely ground seashell material may be obtained by grouping (i.e., classifying) them based on their size.

[0015] The type of seashells used is not limited to those of other shells, but for example, scallop, oyster, clam, abalone, or pearl oyster shells can be used, and it is particularly desirable to use scallop shells, which produce a large amount of shell waste.

[0016] Furthermore, if the seashells are derived from marine mollusks, it is desirable to obtain the crushed seashell material by immersing the seashells in fresh water for a predetermined period (e.g., 1 to 3 years) to remove the salt, and then crushing them. It is also desirable to disinfect the seashells by boiling or other means before crushing them.

[0017] In the process of producing the crushed seashell material, the seashells may be crushed after calcination, but it is preferable to obtain the finely crushed seashell material and the coarsely crushed seashell material by crushing uncalcined seashells. This makes it possible to effectively utilize organic components (e.g., proteins) attached to the seashells as constituent components of the synthetic resin composition according to this embodiment.

[0018] The finely ground seashell material contained in the synthetic resin composition according to this embodiment mainly functions as a reinforcing material to improve the mechanical properties (e.g., flexural modulus) of the synthetic resin molded product obtained from the synthetic resin composition, while the coarsely ground seashell material mainly functions as a design-enhancing material that affects the appearance, texture, and feel of the molded product. In the synthetic resin composition according to this embodiment, by adding the finely ground seashell material and the coarsely ground seashell material to the synthetic resin in the above-mentioned ratio, it is possible to obtain a synthetic resin molded product that has a matte appearance and a smooth (or rough) feel that mimics the texture of seashells, while also having appropriate mechanical properties (e.g., flexural modulus).

[0019] Also, the higher the proportion of finely ground shell in the ground shell material (finely ground shell + coarsely ground shell) contained in the synthetic resin composition, the higher the strength of the synthetic resin molded product. The higher the proportion of coarsely ground shell, the closer the appearance and texture of the synthetic resin molded product can be to the texture of shellfish. Therefore, in order to obtain a synthetic resin molded product with required strength, it is advisable to increase the proportion of finely ground shell in the ground shell material (finely ground shell + coarsely ground shell) contained in the synthetic resin composition. On the other hand, in order to obtain a synthetic resin molded product with a texture and feel closer to that of shell, it is advisable to increase the proportion of coarsely ground shell in the ground shell material contained in the synthetic resin composition. In short, the proportions of the finely ground shell and the coarsely ground shell in the synthetic resin composition should be adjusted according to the properties required for the molded product (such as strength, appearance, or texture), the shape and size of the molded product, or the type of synthetic resin contained in the synthetic resin composition.

[0020] The type of the synthetic resin is not particularly limited. However, for example, it is desirable to use thermoplastic resins such as polypropylene (PP), polyethylene (PE), polyvinyl chloride (PVC), polystyrene (PS), ABS resin, polyamide (PA), polycarbonate (PC), polylactic acid (PLA), polyacetal (POM), polybutylene terephthalate (PBT), or polyethylene terephthalate (PET). Also, as the synthetic resin, it is desirable to use waste plastics (recycled plastics) recovered from discarded household appliances and the like. Thereby, the synthetic resin composition according to the present embodiment can be made of almost all raw materials from waste, contributing to the reduction of carbon dioxide emissions and the reduction of waste in the environment.

[0021] The synthetic resin molded article according to an embodiment of the present invention is formed by molding the above synthetic resin composition into a predetermined shape. The predetermined shape may be a planar shape (for example, sheet-like) or a three-dimensional shape. As described above, by appropriately adjusting the ratio of the crushed shell material contained in the synthetic resin composition, as well as the ratio of the finely crushed shell material and the coarsely crushed shell material, a synthetic resin molded article having excellent strength, a texture, appearance, and touch similar to those of a shell can be obtained. In particular, by making the synthetic resin molded article exhibit a matte appearance and a smooth (or rough) touch, the user can be made aware that the molded article contains a shell, and an enlightenment effect on the waste problem can be expected.

[0022] The molding method of the synthetic resin molded article according to this embodiment is not particularly limited. For example, injection molding can be preferably used.

[0023] The synthetic resin molded article according to this embodiment can be any article. For example, it can be an article that requires strength, such as furniture like a chair or a bench, a housing of an electrical product such as a personal computer, an automobile or an automobile part, or a helmet.

[0024] FIG. 2 shows a helmet which is an example of the synthetic resin molded article according to this embodiment. This helmet includes a main body portion 10 that covers the user's head and a chin strap 20 attached to the main body portion 10, and the main body portion 10 is made of the above synthetic resin composition.

[0025] On the surface of the main body portion 10, a plurality of ribs (protrusions) 11 extending in the front-rear direction are provided. This rib 11 mimics the structure of a scallop shell and serves to improve the strength of the main body portion 10. Also, with such a structure incorporating biomimicry (biological mimicry) and a matte texture reminiscent of a shell, it is possible to strongly appeal to the user that the helmet utilizes a shell.

Example

[0026] The synthetic resin composition and synthetic resin molded article according to the present invention will be described in detail below with reference to examples, but this is not intended to limit the present invention, and various changes and modifications can be made as long as they do not depart from the scope of the present invention.

[0027] [Experimental Example 1] Test specimens were prepared by injection molding using the synthetic resin compositions of Manufacturing Examples 1 to 5, and physical property (mechanical properties) evaluation tests were conducted on tensile yield stress, bending stress, flexural modulus, and impact strength. The results are shown in Table 1. In Table 1, "%" all represent "mass%". The same applies to Tables 2 to 4 described later.

[0028] [Table 1]

[0029] The synthetic resin composition of Production Example 1 consists solely of 100% by mass of polypropylene (indicated as "PP" in Table 1), the synthetic resin compositions of Production Examples 2-4 are a mixture of 80% by mass of polypropylene and 20% by mass of crushed scallop shells, and the synthetic resin composition of Production Example 5 is a mixture of 80% by mass of polypropylene and 20% by mass of calcium carbonate. The polypropylene used in the synthetic resin compositions of Production Examples 1-5 was a commercially available product that is generally available. The calcium carbonate used in the synthetic resin composition of Production Example 5 is a powder with an average particle size of 5 μm, and was a commercially available product that is generally available. On the other hand, the crushed scallop shells used in the synthetic resin compositions of Production Examples 2-4 were obtained from discarded scallop shells acquired from Sarufutsu Village, Hakodate City, and Monbetsu City in Hokkaido, and crushed to 30 μm, 15 μm, or 5 μm using a roller mill or vibro mill without calcination. The discarded scallop shells were selected and used after being left outdoors for 1-3 years after disposal to allow sufficient salt to be removed. In Experimental Examples 2 and 3, described later, the same polypropylene and crushed scallop shell material were used.

[0030] Table 1 shows the MFR (melt flow rate) and density of the synthetic resin compositions of Production Examples 2 to 5. As can be seen from Table 1, although the density of the synthetic resin composition of Production Example 1 is lower than that of the other production examples, there is no significant difference in MFR among Production Examples 1 to 5, confirming that the fluidity of the synthetic resin compositions during molding is equivalent.

[0031] Next, the synthetic resin compositions of Production Examples 1 to 5 were injection molded according to a well-known procedure, and test specimens were prepared and subjected to physical property evaluation tests. The results showed that, in terms of tensile yield stress and impact strength, Production Examples 2 to 4, which contained scallop shell powder, were inferior to Production Example 1, which contained only polypropylene, but superior to Production Example 5, which contained calcium carbonate. In terms of bending stress and flexural modulus, Production Examples 2 to 4 were superior to both Production Example 1 and Production Example 5. From these results, it was confirmed that scallop shell powder with average particle sizes of 5 μm, 15 μm, and 30 μm can function as a reinforcing material that contributes to improving the bending stress and flexural modulus of molded products.

[0032] [Experimental Example 2] Using the synthetic resin compositions of Comparative Example 1 and Examples 1-4, test specimens were prepared by injection molding in the same manner as in Experimental Example 1, and physical property evaluation tests were performed on tensile yield stress, bending stress, flexural modulus, and impact strength. The results are shown in Table 2.

[0033] [Table 2]

[0034] The synthetic resin composition of Comparative Example 1 consists solely of polypropylene. Furthermore, each of the synthetic resin compositions in Examples 1 to 4 consists of a mixture of polypropylene and scallop shell pulverized material with different average particle sizes. The ratio (mass%) of polypropylene and scallop shell pulverized material in each of the synthetic resin compositions in Examples 1 to 4 is shown in Table 2. Although not shown in Table 2, the synthetic resin composition of Example 4 contains 5% by mass of an elastomer additive.

[0035] In Table 2, "Coarse Scallop," "Medium Scallop," and "Fine Scallop" represent finely ground scallop shells with average particle sizes of 1000 μm to 3000 μm, 100 μm to less than 1000 μm, and 10 μm to 30 μm, respectively. "Coarse Scallop" and "Medium Scallop" correspond to the coarsely ground shells of the present invention, with "Coarse Scallop" specifically corresponding to the second coarsely ground shells and "Medium Scallop" corresponding to the first coarsely ground shells. "Fine Scallop" corresponds to the finely ground shells of the present invention.

[0036] As can be seen from the results in Table 2, while Examples 1-4 were inferior to Comparative Example 1 in terms of tensile yield stress and impact strength, their bending stress was equivalent to or slightly inferior to Comparative Example 1, and their flexural modulus was superior to that of Comparative Example 1. From this, it can be inferred that adding scallop shell powder to a synthetic resin composition can function as a reinforcing material that contributes to improving the flexural modulus, in particular, among the physical properties of synthetic resin molded products.

[0037] [Experimental Example 3] Test specimens were prepared by injection molding using the synthetic resin compositions of Production Examples 6 to 13, and the effect of the crushed seashells contained in the synthetic resin compositions on the design and strength of the synthetic resin molded products obtained from these compositions was investigated. The results are shown in Table 3.

[0038] [Table 3]

[0039] The synthetic resin compositions of Production Examples 6 to 12 consist of polypropylene and crushed scallop shells, while the synthetic resin composition of Production Example 13 contains polypropylene and crushed scallop shells, as well as 5% by mass of an elastomer additive.

[0040] In the "Strength" column of Table 3, "○" indicates strength suitable for use in disaster prevention helmets, "×" indicates strength suitable for molded products that are not subjected to impact under normal use, such as ornaments, and "△" indicates strength that is not sufficient for disaster prevention helmets but is better than "×". The ratio (mass%) of polypropylene to scallop shell pulverized material contained in the synthetic resin compositions of manufacturing examples 6 to 13 is as shown in Table 3. Similar to experimental example 2, in Table 3, "coarse scallop," "medium scallop," and "fine scallop" indicate finely pulverized scallop shells with average particle sizes of 1000 μm to 3000 μm, 100 μm to less than 1000 μm, and 10 μm to 30 μm, respectively.

[0041] As can be seen from Table 3, in production examples 6 and 7 of the synthetic resin composition consisting of "fine scallop" pulverized material and polypropylene, a matte appearance reminiscent of the texture of a seashell (represented as (graininess) in Table 3) was not observed on the surface of the molded product. On the other hand, in production examples 8 to 10 of the synthetic resin composition consisting of "coarse scallop" pulverized material and polypropylene, a coarse graininess was observed on the surface of the molded product, in production examples 11 and 12 of the synthetic resin composition consisting of "medium scallop" pulverized material and polypropylene, a fine graininess was observed, and in production example 13 of the synthetic resin composition consisting of both "coarse" and "medium" pulverized material and polypropylene, both coarse and fine graininess was observed on the surface of the molded product. From the above, it was found that if the total amount ratio of "coarse" and "medium" pulverized material to the synthetic resin composition is 3% by mass or more, a graininess is observed on the surface of the molded product, and these scallop shell pulverized materials are useful as design-enhancing materials.

[0042] Furthermore, the results in Table 3 suggest that if the synthetic resin composition contains "fine scallop," "medium scallop," and "coarse scallop" scallop shell powder, and the total amount ratio of these three types of scallop shell powder is 10% by mass or less, a molded product with sufficient strength for use as a disaster prevention helmet can be obtained.

[0043] Furthermore, when the synthetic resin composition of manufacturing example 13 was injection molded to actually produce the helmet shown in Figure 2, it was confirmed that it possessed the physical properties required for a disaster prevention helmet.

[0044] Table 4 below summarizes the relationship between the ratio of synthetic resin and scallop shell pulverized material in a synthetic resin composition and the physical properties (mechanical characteristics) and design of the molded product, based on the results of Experimental Examples 1-3. In Table 4, the "Item" column indicates the name of the synthetic resin composition (for example, "Basic Fine" indicates a basic synthetic resin composition containing finely pulverized scallop shell pulverized material, and "Physical Properties-Focused 1" indicates a synthetic resin composition that yields molded products with excellent physical properties). In addition, each value in Table 4 indicates the ratio (mass%) of synthetic resin (PP) in the synthetic resin composition, or the ratio (mass%) of scallop shell pulverized material with an average particle size of "Fine," "Medium," and "Coarse." Note that "Fine," "Medium," and "Coarse" correspond to the aforementioned "Scallop Fine," "Scallop Medium," and "Scallop Coarse." From Table 4, it can be seen that by adjusting the ratio of synthetic resin and each type of scallop shell pulverized material contained in the synthetic resin composition, synthetic resin compositions suitable for molded products where physical properties are prioritized, and synthetic resin compositions suitable for molded products where design is prioritized, can be obtained.

[0045] [Table 4] [Explanation of symbols]

[0046] 10...Main body 11… Ribs 20... Chin strap

Claims

1. A synthetic resin composition comprising synthetic resin and crushed seashells in a mass ratio of 45:55 to 85:10, A synthetic resin composition wherein the crushed seashell material contains finely crushed seashell material with an average particle size of 1 μm or more and less than 100 μm, and coarsely crushed seashell material with an average particle size of 100 μm or more and 3000 μm or less, in a mass ratio of 7:3 to 46:

9.

2. The synthetic resin composition according to claim 1, wherein the average particle size of the finely ground seashell material is 10 μm or more and 30 μm or less.

3. A molded synthetic resin article obtained by molding the synthetic resin composition described in claim 1 or 2 into a predetermined shape.

4. A helmet made by molding a synthetic resin composition comprising a synthetic resin and crushed seashells in a mass ratio of 98:2 to 25:75, wherein the crushed seashells consist of finely crushed seashells with an average particle size of 1 μm or more and less than 100 μm, and coarsely crushed seashells with an average particle size of 100 μm or more and 3000 μm or less, in a mass ratio of 97:3 to 40:60, the helmet having a plurality of protrusions extending in the front-to-back direction on its outer surface.

5. A shell crushing process to obtain fine shell crushing material with an average particle size of 1 μm or more and less than 100 μm, and coarse shell crushing material with an average particle size of 100 μm or more and 3000 μm or less, by crushing seashells, A synthetic resin composition production step, which involves mixing the finely ground seashell material and the coarsely ground seashell material with a molten synthetic resin to obtain a synthetic resin composition, It has, In the synthetic resin composition production step, the ratio of the mass of the synthetic resin to the total mass of crushed seashells, which is the sum of the mass of the finely crushed seashells and the mass of the coarsely crushed seashells added to the synthetic resin, is 45:55 to 85:10, and the ratio of the mass of the finely crushed seashells to the mass of the coarsely crushed seashells in the total mass of crushed seashells is 7:3 to 46:

9. A method for producing a synthetic resin composition.

Images