Synthetic resin molded article and method for manufacturing synthetic resin molded article

Abstract

To suppress an emission degree of sulfur smell or the like from a molded article when obtaining a molded article by injection molding by using a molding material made by kneading eggshell powders into a polypropylene resin and pelletized, to improve merchantability of the molded article blended with egg shell powders.SOLUTION: A molding material 4 made of pellets obtained by kneading eggshell powders 2 with a polypropylene resin 1, and a powder deodorant 5 are mixed. A mixed molding material 6 made by mixing the molding material 4 and the powder deodorant 5 are molten-kneaded and injection molded to mold a molded article.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a synthetic resin molded article containing eggshell powder and a method for manufacturing the synthetic resin molded article.

Background Art

[0002] In recent years, as shown in Patent Document 1, for products made of petroleum-derived chemically synthesized resins, incineration treatment and landfill treatment at the time of disposal of these products are cited as factors contributing to global warming and soil pollution, and awareness of environmental improvement is increasing. Attention has been focused on reducing the proportion of chemically synthesized resins by using biologically derived substances that have conventionally been disposed of as waste, specifically substances such as eggshells and seashells.

[0003] Patent Document 1 shows that calcium hydroxide fine powder obtained by high-temperature firing of eggshells or seashells and adding water, calcium carbonate fine powder of eggshells or seashells, or fine powder of fibrous materials such as wood chips and paper are mixed and kneaded with a resin composition (thermoplastic resin, thermosetting resin) at a predetermined ratio to produce a powder-containing resin composition. And it has been proposed to manufacture antibacterial foods such as chopsticks and spoons using this powder-containing resin composition as a material.

[0004] Patent Document 2 also shows a method for removing proteins from biologically derived calcareous substances and a resin composition containing solid calcium carbonate obtained by this method. And it shows the point of mixing a resin base material (resin matrix) composed of one or both of a thermoplastic resin and a thermosetting resin with ground eggshells which are calcium carbonate.

[0005] In this Patent Document 2, when separating eggs, egg white and eggshell membrane remain on the eggshell, and when this eggshell is used as a filler for resin or the like, thermal decomposition products of the remaining proteins are generated as by-products, and it is explained that they have an unpleasant odor derived from sulfur compounds such as hydrogen sulfide. In the process of producing calcium carbonate, a device has been proposed to remove the cause of generating unpleasant odors. A method is shown in which a biologically derived calcium-containing substance mainly composed of calcium carbonate is immersed in an alkaline hydroxide aqueous solution of 2.5 mol / L or more to hydrolyze and remove the protein in the calcium-containing substance. Also, as a method for removing the eggshell membrane, it is shown that the eggshell membrane is decomposed using a 0.5 mol / L sodium hydroxide aqueous solution at 90 °C.

[0006] Furthermore, a technique related to calcium-containing batch pellets and a molded body using these pellets is shown in Patent Document 3. In this Patent Document 3, as a pellet-shaped product, there is mentioned a melt-kneaded product containing calcium carbonate powder obtained by pulverizing and selected from eggshells, seashells, and coral shells, or calcium oxide powder obtained by firing and then pulverizing and selected from eggshells, seashells, and coral shells, and a thermoplastic resin.

[0007] On the other hand, in addition to the above-mentioned unpleasant odor of hydrogen sulfide, technologies related to deodorants and the like have been proposed for various malodorous gases such as ammonia, amines, and mercaptans in Patent Document 4. As shown in Patent Document 4, as a product for removing the malodorous gas, there is a white deodorant which is a white fine powder composed of adhered conjugate particles of zinc oxide (ZnO), aluminum oxide, and / or silicon oxide (silicon dioxide SiO2). And it has been shown that this white deodorant is thermally stable up to about 400 °C and can also be added to plastics.

[0008] Also, Patent Document 5 shows a deodorizing device. It includes a deodorizing device body made of an injection-molded body of a synthetic resin in which a deodorant mainly composed of silicon dioxide and zinc oxide is blended. And it is described as a deodorizing device for removing malodorous gases as described above. It is shown that the adsorption site of the base derived from zinc oxide adsorbs acidic malodorous substances such as hydrogen sulfide and methyl mercaptan, and the adsorption site of the acid derived from silicon dioxide can adsorb basic malodorous substances such as ammonia and trimethylamine.

Prior Art Documents

Patent Documents

[0009] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-062579 [Patent Document 2] Japanese Patent Application Laid-Open No. 2011-184269 [Patent Document 3] Utility Model Registration Gazette No. 3230019 [Patent Document 4] Japanese Patent Application Laid-Open No. 63-246167 [Patent Document 5] Utility Model Registration Gazette No. 3156575 [Summary of the Invention] [Problems to be Solved by the Invention]

[0010] In the production of synthetic resin molded products, adding eggshell powder obtained by finely pulverizing eggshells to a synthetic resin material to mold various molded products is in line with the purpose of suppressing the use ratio of petroleum-derived chemical synthetic resins, is useful in suppressing the depletion of petroleum resources, reduces CO2 generated during the production of petroleum-based materials, and is useful in reducing the amount of CO2 generated during incineration disposal.

[0011] Therefore, as shown in Patent Documents 1, 2, 3, etc., it has been proposed to produce synthetic resin molded products using a synthetic resin material and eggshell powder as main molding materials. As a specific example of the manufacturing method, a molding material composed of pellets obtained by kneading eggshell powder into a thermoplastic resin is prepared in advance. When continuously manufacturing a molded product, this molding material is put into an injection molding machine, melted in a heating cylinder equipped with an in-line screw, and the melted molding material is injected to injection-mold the molded product.

[0012] By the way, regarding eggshell powder, a great deal of effort is required to ensure that protein components such as eggshell membranes and egg whites are completely removed during the manufacturing process of this eggshell powder. And at present, although not all eggshell powder products, it is highly likely that eggshell powder combined with synthetic resin materials for pellets contains fine powder with remaining protein components mixed in.

[0013] Therefore, when injection molding is performed using the pelletized molding material, there is a problem that molded products with a sulfurous odor are produced.

[0014] However, at present, no measures such as adding a deodorant to the molding material side to solve the problem of the molded product emitting a bad odor are known.

[0015] In view of the above circumstances, an object of the present invention is to suppress the degree of sulfurous odor and the like emitted from a molded product when obtaining a molded product by injection molding using a molding material obtained by kneading eggshell powder with polypropylene resin and pelletizing it, and to enhance the marketability of the molded product containing eggshell powder.

Means for Solving the Problems

[0016] The present invention has been made in consideration of the above problems, and provides a synthetic resin molded product characterized by containing polypropylene resin, eggshell powder, and a powder deodorant, and the eggshell powder and the powder deodorant being mixed in the polypropylene resin, thereby solving the above problems.

[0017] And in the above invention, the powder deodorant can be a mixture of amorphous silica powder and zinc oxide powder.

[0018] Another invention provides a method for manufacturing a synthetic resin molded article, which solves the above problems by mixing a granular molding material composed of pellets obtained by kneading eggshell powder with polypropylene resin and a powder deodorant, melt-kneading the mixed molding material obtained by mixing the granular molding material and the powder deodorant, and injecting the mixed molding material in a state where the eggshell powder and the powder deodorant are mixed in the polypropylene resin melted by the melt-kneading to perform injection molding of the molded article.

[0019] In the present invention, the powder deodorant can be a mixture of amorphous silica powder and zinc oxide powder.

[0020] In the present invention, it is preferable that the powder deodorant is blended at a ratio of 1% by weight with respect to 100% by weight of the granular molding material in the mixed molding material.

[0021] In the present invention, in the blending of the eggshell powder and the polypropylene resin in the granular molding material, it is preferable that the blending ratio of the polypropylene resin is at least 40% by weight with respect to 100% by weight of the granular molding material.

Effects of the Invention

[0022] According to the present invention, since the eggshell powder and the powder deodorant are mixed in the polypropylene resin of the synthetic resin molded article, even if there are substances that cause bad odors such as sulfur odor due to the inclusion of the eggshell powder, the generation of bad odors can be suppressed.

[0023] According to another invention, even when a general-purpose pellet having a blending ratio of 60% by weight of eggshell powder and 40% by weight of polypropylene resin with respect to 100% by weight of the molding material is adopted, a molded article with suppressed generation of bad odors such as sulfur odor can be obtained, which has an excellent effect.

Brief Description of the Drawings

[0024]

Figure 1

Figure 2

Figure 3

Mode for Carrying Out the Invention

[0025] Next, the present invention will be described in detail based on the embodiments shown in FIGS. 1 to 3. The following is a molded article molded by the method of the embodiment of the present invention. Briefly explaining this embodiment, first, a forming material 4 composed of pellets 3 obtained by kneading eggshell powder 2 into polypropylene resin 1 and a powder deodorant 5 are prepared. Then, the forming material 4 and the powder deodorant 5 are mixed to create a mixed forming material 6. After that, the mixed forming material 6 is put into an injection molding machine to be melted and kneaded, and a product (molded article) is injection molded by this injection molding machine.

[0026] FIG. 1 represents one grain of the pellet 3 which is the forming material 4 and schematically shows the components of the forming material. This forming material 4 is obtained by kneading eggshell powder 2 into polypropylene resin 1 and extrusion molding it with an extrusion molding machine into a granular form. Regarding the blending ratio of polypropylene resin 1 and eggshell powder 2, the blending ratio of polypropylene resin 1 is 40% by weight when the forming material 4 is 100% by weight. That is, the eggshell powder 2 is 60% by weight and the polypropylene resin 1 is 40% by weight.

[0027] An additive may be added when the forming material 4 is extrusion molded, but in that case, the amount of the additive is small and does not reach the amount until the above blending ratio of polypropylene resin 1 and eggshell powder 2 in the forming material 4 changes.

[0028] The eggshell powder 2 is obtained by washing eggshells, removing the eggshell membranes and egg whites, drying them, and then finely pulverizing them into a powder after drying. Then, the polypropylene resin 1 and the eggshell powder 2 are mixed and put into an extrusion molding machine as described above, and the molten polypropylene resin 1 and the eggshell powder 2 are kneaded together and extrusion molded into pellets.

[0029] Normally, the eggshell powder 2 is collected from eggshells discarded from food factories and the like, and it is only necessary to simply remove protein components such as eggshell membranes and egg whites from the eggshells. However, in the case of pellets containing eggshell powder currently on the market, there is a possibility that eggshell powder with incomplete removal of protein components is mixed in. In the present invention, even when molding is performed using pellets containing eggshell powder in a state where such protein components are not completely removed, measures are taken to suppress the generation of a sulfurous odor from the molded product.

[0030] (Step A for preparing the mixed molding material) Therefore, in the present invention, when obtaining a molded product by injection molding using the molding material 4, first, there is a step (Step A for preparing the mixed molding material) of mixing the molding material 4 and the powder deodorant 5. Then, as shown in FIG. 2, it is followed by a step B of melting and kneading the mixed molding material 6 prepared by mixing the molding material 4 and the powder deodorant 5.

[0031] (Step B of melting and kneading the mixed molding material) When melting and kneading the mixed molding material 6 that has passed through Step A for preparing the mixed molding material, the mixed molding material 6 is filled into an injection molding machine 7, and the molding material 4 and the powder deodorant 5 of the mixed molding material 6 are melted and kneaded at the part of the heating cylinder (heating cylinder equipped with a screw) in this injection molding machine 7.

[0032] (Step C of injecting the mixed molding material) The mixed molding material 6 that has passed through Step B of melting and kneading the mixed molding material continues with Step C of injecting the mixed molding material in this injection molding machine 7, and the melted and kneaded mixed molding material 6 is injected to injection mold the molded product. The molded product thus formed contains polypropylene resin 1, eggshell powder 2, and powder deodorant 5, and the eggshell powder 2 and the powder deodorant 5 are mixed in the polypropylene resin 1.

[0033] The powder deodorant 5 is a mixture of powdered amorphous silica (SiO2) and powdered zinc oxide (ZnO). The particle size was set to 10 μm or less. Also, when the molding material 4 is 100% by weight, it is preferable that the powder deodorant 5 is mixed at a blending ratio of 1% by weight.

[0034] In the above mixing and molding material mixing step A, the molding material 4 and the powder deodorant 5 are mixed using a tumbler and mixed for about 30 to 40 minutes.

[0035] In this embodiment, the mixed molding material 6 obtained by mixing is put into an injection molding machine 7, and a tray is molded by injection molding.

[0036] In the present invention, the mixed molding material melting and kneading step B of melting and kneading the mixed molding material 6 obtained by mixing with a tumbler is carried out using an injection molding machine as described above, but it is not limited to an in-line screw type injection molding machine.

[0037] When molding the molded product, through the mixed molding material mixing step A and the mixed molding material melting and kneading step B, and then obtaining the molded product by injection molding, in the molded tray, the mixed state of the eggshell powder 2 and the powder deodorant 5 in the polypropylene resin 1 becomes uniform as described above.

[0038] Therefore, even if particulate eggshell powder 2 that emits a sulfur odor is present in any part of the molded product, the powder deodorant 5 is located around it, and it is possible to suppress the intake of the components of the sulfur odor and the diffusion of the odor.

[0039] The uptake of malodorous components by the powder deodorant 5 is not limited to the sulfurous odor components released from the eggshell powder 2. Similar to the description of the white deodorant composed of silicon dioxide and zinc oxide in Patent Document 4, the adsorption sites of the base derived from zinc oxide can adsorb acidic malodorous substances such as hydrogen sulfide and methyl mercaptan, and the adsorption sites of the acid derived from silicon dioxide can adsorb basic malodorous substances such as ammonia and trimethylamine.

[0040] In the embodiment, the powder deodorant 5 was described as a mixture of amorphous silica powder and zinc oxide powder. However, the powder deodorant 5 is not limited to the mixture, and a deodorant component having an action of decomposing malodorous components may be released from the powder deodorant 5, and the malodorous components such as the sulfurous odor emitted from the eggshell powder may be decomposed by the action of the deodorant component.

[0041] When the molded product is a tray, an anti-slip sheet may be disposed on the bottom surface of the core mold of the molding die (corresponding to the portion where tableware etc. are placed), and injection molding may be performed by an in-mold molding method. In this case, a tray with the anti-slip sheet adhered can be molded.

[0042] When the blending ratio of the polypropylene resin 1 and the eggshell powder 2 in the molding material 4 is such that the molding material 4 is 100% by weight as described above, the eggshell powder 2 is 60% by weight and the polypropylene resin 1 is 40% by weight. If it is considered that the strength of the molded product injection-molded with the mixed molding material 6 using this blending ratio of the molding material 4 is insufficient, the blending ratio of the polypropylene resin component in the molded product may be increased. For example, it can be dealt with by preparing a molding material 4 in which the blending ratio on the polypropylene resin 1 side is increased for the blending ratio of the eggshell powder 2 and the polypropylene resin 1.

[0043] (Increase in polypropylene resin blending ratio) Further, in the present invention, while using the molding material 4 in which the eggshell powder 2 is 60% by weight and the polypropylene resin 1 is 40% by weight, it is possible to increase the blending ratio of the polypropylene resin 1 component in the molded product by the following method.

[0044] To increase the blending ratio of polypropylene resin 1 in the molded product, a pellet 8 (a molding material for adjusting the blending ratio) composed only of a molding material 4 (60% by weight of eggshell powder and 40% by weight of polypropylene resin), a powder deodorant 5, and polypropylene resin 1 is mixed to prepare a mixed molding material 6. Using this mixed molding material 6, through the above-mentioned steps of preparing the mixed molding material A, melt-kneading the mixed molding material B, and injecting the mixed molding material C, a molded product can be obtained.

[0045] In the above method, since the blending ratio of polypropylene resin 1 in the components of the molded product is increased, the degree of odor such as sulfur odor felt from the eggshell powder part can be further reduced. In this case, it is not necessary to prepare a new molding material 4 with a different blending ratio of eggshell powder 2 and polypropylene resin 1, and the reduction of odor such as sulfur odor can be easily implemented.

[0046] In cases where it is necessary to further reduce the degree of offensive odor such as sulfur odor, heat treatment is performed on the injection-molded product at a constant temperature for a certain period of time. Taking a specific example of this heat treatment, dozens of trays (an example of the above-mentioned molded product) are stacked alternately with gaps to allow hot air to pass through easily in a large dryer (box type) so that hot air blows over the entire tray, and then heat treatment is carried out. By heating the molded product after injection molding to a constant temperature for a certain period of time in this way, the problem of offensive odor such as sulfur odor being emitted can be further suppressed.

Explanation of symbols

[0047] 1... Polypropylene resin 2... Eggshell powder 3... Pellet (molding material) 4... Molding material 5... Powder deodorant 6... Mixed molding material 7... Injection molding machine 8... Pellet composed only of polypropylene resin A... Step of preparing the mixed molding material B…Mixing and melting stage of the mixed forming material C…Injection stage of the mixed forming material

Claims

1. comprising a polypropylene resin, eggshell powder, and a powder deodorant, wherein the eggshell powder and the powder deodorant are mixed in the polypropylene resin, and the powder deodorant is a mixture of amorphous silica powder and zinc oxide powder, and a synthetic resin molded article characterized thereby.

2. A granular molding material made of pellets obtained by kneading eggshell powder into a polypropylene resin and a powder deodorant are mixed, and the mixed molding material obtained by mixing the granular molding material and the powder deodorant is melt-kneaded. In a state where the eggshell powder and the powder deodorant are mixed in the polypropylene resin melted by the melt-kneading, the mixed molding material is injected to injection-mold a molded article, and the powder deodorant is a mixture of amorphous silica powder and zinc oxide powder, and a method for producing a synthetic resin molded article characterized thereby.

3. The method for producing a synthetic resin molded article according to claim 2, wherein the mixing ratio of the powder deodorant is 1% by weight with respect to 100% by weight of the granular molding material.

4. In the blending of the eggshell powder and the polypropylene resin in the granular molding material, the blending ratio of the polypropylene resin is at least 40% by weight with respect to 100% by weight of the granular molding material, and the method for producing a synthetic resin molded article according to claim 2 or 3.

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