JP2007161853A - Plastic molded product and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plastic molded product having high transfer properties, high strength and high heat resistance and prepared by using a principal material which is a plastic material made of biomass as a raw material. <P>SOLUTION: The plastic molded product 1 (an exterior finish part of OA equipment) is composed of the plastic material obtained by adding a plastic (polycarbonate) made of petroleum as the raw material to a plastic (polylactic acid) made of the biomass as the raw material and alloying the plastics. The molded product is manufactured by injection filling of a metal mold of a molding apparatus with the alloyed material. The surface layer part is a skin layer 4 and the central part is a core layer 5 containing holes 5a. Furthermore, the holes are formed by adding a foaming agent and the hole diameter can be controlled to a smaller diameter by adding a nucleating agent. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a plastic molded article and a method for producing the same, and more particularly relates to a plastic molded article using a biomass-based resin having high transferability, high strength, and high heat resistance, and a method for producing the same.

  Replacing plastic materials made from petroleum with plastic materials made from biomass can reduce the emission of carbon dioxide, which is a greenhouse gas, and prevent global warming. It also leads to resource saving of fossil resources that are depleted resources. For these reasons, research on plastic materials using biomass such as plant-derived resins and microorganism-derived resins as raw materials has been actively conducted. However, plastic materials made from biomass are limited in their range of use, such as plastic tableware, due to problems such as rigidity and heat resistance, and are particularly strong in the strength and heat resistance of home appliances and exterior parts of OA equipment. It was difficult to apply to applications that required high performance.

  As a technique for improving the strength and heat resistance of a molded product, it has been studied to crystallize polylactic acid by heat treatment during or after molding. However, since polylactic acid resin has a low crystallization rate, it has practical problems such as requiring a long molding cycle time and heat treatment after molding, and large deformation during molding and heat treatment.

  Therefore, in order to improve the strength and heat resistance of the molded product, there are a method of adding a plastic material made of petroleum to a plastic material made of biomass to alloy and blend, a method of adding a filler, etc. It has been studied.

  In the following Patent Document 1, an alloy resin in which a polycarbonate resin or an alicyclic amorphous polyolefin resin of a thermoplastic resin having a weighted deflection temperature of 120 ° C. or higher is dispersed in a polylactic acid resin that is a plastic material made from biomass. Use in an optical disk substrate improves heat resistance while maintaining necessary transparency. By using an alloy resin composed mainly of plant-derived raw material polylactic acid resin as an optical disk substrate, it is transparent to laser light for recording or reproducing signals, and is also stipulated in the CD and DVD standards. It is said that it is possible to obtain an optical disk with improved heat resistance that has heat resistance and is less deformed after a high temperature load test and can be reproduced by a player such as a reproducing apparatus or a recording / reproducing apparatus.

  Further, in Patent Document 2 below, a plastic molded product is obtained using a polylactic acid resin in which a crystalline polypropylene resin and an inorganic filler are blended. Inorganic fillers include particulate fillers such as talc, calcium carbonate, carbon black, magnesium hydroxide, whisker-like fillers such as potassium titanate and mossheid, plate-like fillers such as mica, fibers such as glass fibers, carbon fibers, and metal fibers. The filler is preferably glass fiber, carbon fiber, mica, talc and calcium carbonate. The filler not only improves the strength but also acts as a nucleating agent and promotes crystallization. By using these resins, it is said that a plastic molded article having excellent strength and heat resistance and good dispersibility can be obtained.

  Furthermore, in Patent Document 3 below, in order to obtain a plastic molded product having biodegradability and excellent impact resistance and heat resistance, a lactic acid-based resin, an aliphatic polyester other than the lactic acid-based resin, an aromatic A resin in which aliphatic polyester and an inorganic filler having an average particle diameter of 1 to 5 μm are blended is used. Examples of the inorganic filler include talc, mica, alumina, glass fiber, and metal powder. Since plastic molded products using these resins are excellent in impact resistance and heat resistance, they can be used as home appliances, automobile parts, and other general molded products.

  However, in order to improve the rigidity and heat resistance of plastic molded products, the above method is a method of alloying and blending by adding plastic materials made from petroleum to plastic materials made from biomass, and adding fillers. Therefore, these resins have higher viscosity than plastic materials made from pure biomass that has not been alloyed or blended.

  Therefore, when injection molding is performed using these plastic materials, the flowability is reduced, so when trying to obtain a plastic molded product with a thick or uneven shape, or a complicated shape with ribs, etc. In addition, there is a drawback in that a molding defect called sink (the cavity shape of the mold cannot be accurately transferred) occurs. Below, an example when a molding defect occurs is given.

FIG. 8 is a cross-sectional view of a molded product having a target shape, that is, an exterior component 27 of an OA device having a rib shape. On the other hand, FIG. 9 is a cross-sectional view showing the shape of the molded product 28 actually obtained, and shows the problems of the prior art caused by the molding process. 8 and 9, reference numeral 2 is a rib, reference numeral 3 is a gate (corresponding portion), and reference numeral 4 is a skin layer.
[Raw material: Resin used]
(1) A plastic material using biomass as a raw material and a plastic material using petroleum as a raw material were mixed at the following ratio (% by weight) and alloyed.
(2) Plastic material made from biomass, polylactic acid (glass transition point = 60 ° C., melting point = 170 ° C., thermal decomposition point = 250 ° C.)
-Mixing ratio = 50% by weight
(3) Petroleum-based plastic material / polycarbonate (glass transition point = 145 ° C., melting point = 250 ° C., thermal decomposition point = 400 ° C.)
-Mixing ratio = 50% by weight
[Main molding conditions]
(1) Molding method = Injection molding method (2) Resin temperature = 220 ° C.
(3) Mold temperature = 130 ° C
(4) Holding pressure = 100 MPa

  In the production of the molded product, since a resin obtained by alloying polylactic acid and polycarbonate is used, the resin temperature must be set to 220 ° C., which is the thermal decomposition point of polylactic acid, of 250 ° C. or less. Since polycarbonate is an amorphous resin, it is soft when it is above the glass transition point, and is flowable, but it has a very high viscosity. As a result, the cooling proceeds while the resin is filled into the mold, and sinking occurs because the holding pressure does not work at a place away from the gate. In addition, since the molded product has a shape having ribs, the cooling of the resin at the base portion of the ribs is the slowest, and sink marks are likely to occur on the opposing surfaces of the ribs.

Japanese Patent Laid-Open No. 2005-196821 JP-A-2005-307128 JP 2004-323791 A

  The present invention has been made in order to solve the above-mentioned problems of the prior art, and has high transferability (property capable of transferring the cavity shape of the mold with high accuracy), high strength and high heat resistance, and main materials. As a manufacturing method of the above-mentioned molded product that can be applied effectively to home appliances and exterior parts of OA equipment, etc. It is to provide.

  The invention according to claim 1 is mainly made of a plastic material obtained by mixing a plastic material using biomass as a raw material (hereinafter referred to as biomass raw material plastic) and a plastic material using petroleum as a raw material (hereinafter referred to as petroleum raw material plastic). A molded product as a material, which is a plastic molded product comprising a skin layer forming a surface layer portion and a core layer forming a central portion, and pores are formed in the core layer .

  The invention according to claim 2 is a molded article composed of a skin layer forming a surface layer part and a core layer forming a center part, wherein the skin layer is mainly made of petroleum raw material plastic (petroleum raw material resin). The plastic molded product is characterized in that the core layer is formed using a biomass raw material plastic (biomass raw material resin) as a main material, and pores are formed in the core layer.

  The invention according to claim 3 is the plastic molded article according to claim 2, wherein the petroleum raw material plastic is an amorphous plastic, and the glass transition temperature thereof is lower than the melting temperature of the biomass raw material plastic.

  The invention according to claim 4 is the plastic molded article according to claim 2, wherein the petroleum raw material plastic is a crystalline plastic, and the softening temperature thereof is lower than the melting temperature of the biomass raw material plastic.

  The invention according to claim 5 is the plastic molded article according to any one of claims 1 to 4, characterized in that the plastic molded article is an exterior part of an electric product (home appliance, OA device, etc.).

  In the invention according to claim 6, when producing the molded article according to claim 1, a plastic material obtained by mixing a biomass raw material plastic, a petroleum raw material plastic, and a foaming agent into an alloy is injected and filled in a mold, It is a method for producing a plastic molded product, wherein the molded product is produced by an injection molding method in which a molded product is taken out from the die after cooling the mold.

  In the invention according to claim 7, when the molded article according to claim 1 is manufactured, a plastic material obtained by mixing biomass raw material plastic and petroleum raw material plastic and alloying is impregnated with a supercritical fluid. A method for producing a plastic molded product comprising producing by a injection molding method in which a mold is injected and filled, and after cooling the mold, the molded product is taken out from the mold.

  In the invention according to claim 8, when the molded product according to any one of claims 2 to 4 is manufactured, the petroleum raw material plastic for forming the skin layer is injected and filled into the mold, and then the core layer is formed. It is a method of manufacturing a plastic molded product characterized in that it is manufactured by a sandwich molding method in which a biomass raw material plastic to which a foaming agent is added is injected and filled into a mold, and after cooling, the molded product is taken out from the mold. is there.

  In the invention according to claim 9, when the molded article according to any one of claims 2 to 4 is manufactured, a petroleum raw material plastic for forming a skin layer and a foaming agent for forming a core layer are added. A method for producing a plastic molded product is characterized in that a biomass raw material plastic is simultaneously injected into a mold, cooled, and then manufactured by a sandwich molding method in which the molded product is taken out of the mold.

In the invention according to claim 10, when the molded article according to any one of claims 2 to 4 is manufactured, a petroleum raw material plastic for forming a skin layer is injected and filled into a mold, and then a core layer is formed. Biomass raw material plastic impregnated with supercritical fluid (carbon dioxide (CO ₂ ), nitrogen gas (N ₂ ), etc.) is injected and filled into the mold, and after cooling, the molded product is molded into the mold It is a manufacturing method of a plastic molded product, characterized in that it is manufactured by a sandwich molding method to be taken out from

  The invention according to claim 11 is impregnated with a petroleum raw material plastic for forming a skin layer and a supercritical fluid for forming a core layer when the molded article according to any one of claims 2 to 4 is manufactured. This is a method for producing a plastic molded product, characterized in that the biomass raw material plastic is simultaneously injected into a mold, cooled and then manufactured by a sandwich molding method in which the molded product is taken out from the mold.

According to the first aspect of the present invention, a plastic molded article having high transferability, high strength, and high heat resistance using a biomass raw material plastic is provided. According to the second aspect of the present invention, a plastic molded article having higher transferability, higher strength, and higher heat resistance using a biomass raw material plastic is provided.
When the molded product according to the invention of claim 3 and claim 4 is manufactured by the sandwich molding method, when the biomass raw material plastic for forming the core layer is expanded and expanded, the petroleum raw material plastic for forming the skin layer is softened. Therefore, as a result of efficiently pressing the petroleum raw plastic against the mold cavity surface, molding defects such as sink marks are less likely to occur in the molded product.
According to the invention of claim 5, a high transferability, high strength and high heat resistance exterior part using a biomass raw material plastic is provided.

In the inventions of claim 6 and claim 7, since a general-purpose injection molding machine can be used, the equipment cost is reduced, and a high-transfer, high-strength, high-heat-resistant plastic molded product using biomass raw material plastic is inexpensive. Can be provided.
According to the inventions of claims 8 and 9, it is possible to obtain a plastic molded article having high transferability, high strength, and high heat resistance by using biomass raw material plastic as described in any one of claims 2 to 4. .
The method for producing a plastic molded product according to the inventions of claims 10 and 11 uses the supercritical fluid as a material for foaming the plastic so that it does not adversely affect the environment. It is.

Embodiments of the present invention will be described with reference to the drawings.
[First embodiment]
FIG. 1 is a cross-sectional view showing the shape of a plastic molded article 1 (an exterior part of an OA device) of the present invention. The molded product 1 is manufactured by injection molding a plastic material obtained by mixing a biomass raw material plastic and a petroleum raw material plastic into an alloy. In the present embodiment, polylactic acid is used as the biomass raw material plastic, and polycarbonate is used as the petroleum raw material plastic. That is, the molded product 1 has a skin layer 4 in the surface layer portion and a core layer 5 containing the pores 5a in the central portion. These pores are formed by adding a foaming agent, but the pore diameter is the addition of a nucleating agent Can be controlled to a smaller one.
The reason why the voids are controlled to be small is to prevent the voids from growing large and reaching the surface of the molded product, thereby generating recesses.

[Example 1]
A molding example of the molded product will be described.
[Raw material: Resin used]
(1) A biomass raw material plastic and a petroleum raw material plastic mixed at the following ratio (weight%) and alloyed were used.
(2) Biomass plastic / polylactic acid (glass transition point = 60 ° C., melting point = 170 ° C., thermal decomposition point = 250 ° C.)
-Mixing ratio = 50% by weight
(3) Petroleum raw material plastic / polycarbonate (glass transition point = 145 ° C., melting point = 250 ° C., thermal decomposition point = 400 ° C.)
-Mixing ratio = 50% by weight
[Foaming agent]
Azodicarbonamide (ADCA)
[Nuclear agent]
talc
[Main molding conditions]
(1) Molding method = Injection molding method (2) Resin temperature = 220 ° C.
(3) Mold temperature = 130 ° C
(4) Holding pressure = 60 MPa

  FIG. 2 is an explanatory view showing a method of manufacturing the plastic molded article 1 by the injection molding method in the order of steps. In this figure, the alloyed plastic material is injected and injected from a gate 3 into a mold cavity 3A maintained at a constant temperature by a temperature control means (not shown) (FIG. 2 (a)). As the plastic material is filled, the foaming agent foams, and the plastic material is pressed against the cavity surface of the mold by the foaming force (FIG. 2B). Therefore, molding defects such as sink marks do not occur even when viscosity is increased and fluidity is decreased by alloying polycarbonate. As a result, as shown in FIG. 1, the skin layer 4 that forms the surface layer portion without pores and the core layer 5 that forms the central portion where the pores 5a are formed, A plastic molded product having high strength and high heat resistance can be obtained.

[Second Embodiment]
FIG. 3 is a cross-sectional view showing the shape of a plastic molded product 6 (exterior part for OA equipment) according to the present invention. The plastic molded product 6 is composed of a skin layer 4 that forms a surface layer portion and a core layer 5 that forms a central portion. The main material of the skin layer 4 is petroleum raw material plastic, and the core layer 5 in which pores 5a are present. The main material is composed of biomass plastic. In the present embodiment, polycarbonate is used as the petroleum raw material plastic, and polylactic acid is used as the biomass raw material plastic. Further, the biomass raw material plastic is mixed with a foaming agent for forming pores in the core layer and a nucleating agent for controlling the pores to be small.

[Example 2]
A molding example of the molded product will be described.
[Raw material: Resin used]
(1) Skin layer forming material: Petroleum raw material plastic / polycarbonate (glass transition point = 145 ° C., melting point = 250 ° C., thermal decomposition point = 400 ° C.)
(2) Core layer forming material: Biomass raw material plastic / polylactic acid (glass transition point = 60 ° C., melting point = 170 ° C., thermal decomposition point = 250 ° C.)
[Foaming agent]
Azodicarbonamide (ADCA)
[Nuclear agent]
talc
[Main molding conditions]
(1) Molding method = sandwich molding method (2) Resin temperature / polycarbonate: 290 ° C
・ Polylactic acid: 220 ° C
(3) Mold temperature = 130 ° C
(4) Holding pressure = 60 MPa

4 (a), 4 (b), and 4 (c) are explanatory views showing a method of manufacturing the plastic molded product 6 by the sandwich molding method in the order of steps. A pair of molds 17 constituting the cavity 16 is prepared. The mold 17 is maintained at a constant temperature by temperature control means (not shown). Here, there are two flow paths 7 and 8 inside the nozzle of the injection molding machine. That is, the first flow path 7 through which the polycarbonate 11 that forms the skin layer is connected to the first injection unit 9 and the polylactic acid 12 that is connected to the second injection unit 10 and forms the core layer are provided. The flowing second flow path 8 and the discharge port 13 are provided, and the two kinds of plastic materials are joined before the discharge port 13.
Reference numeral 14 indicates an injection of petroleum raw material plastic, and reference numeral 15 indicates an injection of biomass raw material plastic. Moreover, regarding the sandwich molding method, for example, there are those disclosed in JP-A-10-21633 and JP-A-2001-260173.

  Next, the molding process of the sandwich molding method will be described. In FIG. 4, first, polycarbonate for forming a skin layer is injected from the first injection unit 9 into the cavity 16 of the mold 17 from the discharge port 13 through the first flow path 7. Thereby, the skin layer 4 is formed. After injecting a predetermined amount of polycarbonate for the skin layer 4, the polylactic acid forming the core layer is passed from the second injection unit 10 through the second flow path 8 while continuing to inject the polycarbonate forming the skin layer. Injection and filling into the cavity 16 of the mold 17 from the discharge port 13 is performed.

  Since polylactic acid contains a foaming agent, the foaming agent foams together with injection filling, and the foaming power causes the biomass raw material plastic to form the core layer to expand, and further the petroleum raw material to form the skin layer. Press the plastic against the cavity surface of the mold. Thereafter, when the temperature of the molded product is cooled to a temperature not higher than the glass transition point of the polycarbonate forming the skin layer 4, the molded product is taken out from the mold 17. As a result, as shown in FIG. 3, a skin layer 4 that forms a surface layer portion without pores formed of polycarbonate, and a core layer 5 that forms a central portion where pores formed of polylactic acid exist. A plastic molded article having a high transfer property, high strength, and high heat resistance can be obtained.

[Third embodiment]
FIG. 5 is a cross-sectional view showing the shape of a plastic molded product 18 (exterior part of home appliance) according to the present invention. The plastic molded product 18 includes a skin layer 4 that forms a surface layer portion and a core layer 5 that forms a central portion. The skin layer 4 is made of petroleum raw material plastic, and the core layer 5 in which pores 5a are present is biomass. It is composed of raw plastic. In this embodiment, ABS (acrylonitrile butadiene styrene) is used as the petroleum raw material plastic, and polylactic acid is used as the biomass raw material plastic. In addition, the biomass raw material plastic is mixed with a foaming agent for forming pores in the core layer of the plastic molded product and a nucleating agent for controlling the pore diameter to be small.

[Example 3]
A molding example of the molded product will be described.
[Raw material: Resin used]
(1) Petroleum raw material plastics / ABS (glass transition point = 120 ° C., melting point = 180 ° C., thermal decomposition point = 400 ° C.)
(2) Biomass plastic / polylactic acid (glass transition point = 60 ° C., melting point = 170 ° C., thermal decomposition point = 250 ° C.)
[Foaming agent]
Azodicarbonamide (ADCA)
[Nuclear agent]
talc
[Main molding conditions]
(1) Molding method = Sandwich molding method (2) Resin temperature / ABS: 260 ° C
・ Polylactic acid: 220 ° C
(3) Mold temperature = 80 ° C
(4) Holding pressure = 80 MPa

Next, the molding process of the sandwich molding method in this embodiment will be described. In FIG. 4, ABS for forming a skin layer is injected from the first injection unit 9 into the cavity 16 of the mold 17 from the discharge port 13 through the first flow path 7. Thereby, the skin layer 4 is formed. In addition, polylactic acid forming the core layer is injected and filled from the second injection unit 10 through the second flow path 8 into the cavity 16 of the mold 17 through the discharge port 13. In this embodiment, ABS for forming the skin layer and polylactic acid mixed with a foaming agent for forming the core layer are simultaneously injected and filled into the mold. Since polylactic acid contains a foaming agent, the foaming agent foams with injection filling, and the biomass raw material plastic that should form the core layer expands due to the foaming force, and further the petroleum raw material that should form the skin layer Press the plastic against the cavity surface of the mold. Then, after cooling in a metal mold | die, a plastic molded product is taken out from a metal mold | die.
As a result, as shown in FIG. 5, the skin layer 4 that forms the surface layer portion without pores formed of ABS, and the core layer 5 that forms the central portion where the pores 5 a formed of polylactic acid are present, A plastic molded article 18 having high transferability, high strength, and high heat resistance is obtained.

  The biomass raw material plastic in the present invention is not particularly limited as long as it is a plastic manufactured using raw materials extracted from plants or microorganisms without using petroleum as a raw material, and the plastic used in the examples of the present invention. In addition to lactic acid, polyglycolic acid, polycaproic acid, copolymers of these resins, microbial raw materials such as polyhydroxyalkanoate (PHA), polybutylene succinate (PBS), polyethylene adipate, copolymers of these resins (poly Butylene succinate / adipate), cellulose derivatives, starch-based polymers such as chitin and chitosan, and the like.

  On the other hand, the petroleum raw material plastic is not particularly limited as long as it has strength and heat resistance. It is particularly good if the softening temperature is high. Further, it can be used regardless of whether it is amorphous or crystalline.

  When the petroleum raw material plastic for forming the skin layer is an amorphous plastic, the glass transition temperature is preferably lower than the melting temperature of the biomass raw material plastic for forming the core layer. This is because when the sandwich molding method is used, when the biomass raw material plastic expands and expands, the petroleum raw material plastic is in a softened state. This is because sink marks or the like that are less likely to occur.

  In addition, when the petroleum raw material plastic for forming the skin layer is a crystalline plastic, the softening temperature is preferably lower than the melting temperature of the biomass raw material plastic for forming the core layer. Similarly to the case of using amorphous plastic, when the biomass raw material plastic expands and expands, the petroleum raw material plastic is in a softened state, so that the force pressing efficiently on the mold cavity surface is propagated. This is because sink marks or the like that are poorly formed are less likely to occur.

  Moreover, the flame retardance of the molded article using biomass raw material plastics can be improved by adding a conventionally well-known flame retardant to the petroleum raw material plastics which should form a skin layer.

As the blowing agent, in addition to azodicarbonamide (ADCA) used in the examples of the present invention, inorganic blowing agents (sodium hydrogen carbonate, ammonium carbonate, ammonium hydrogen carbonate, etc.) and organic blowing agents (azobisisobutyro) Nitrile, barium azodicarboxylate, etc.) can be used.
On the other hand, as the nucleating agent, silica, clay, alumina or the like can be used in addition to talc.

  FIG. 6 is a diagram illustrating a method of mixing the foaming agent 31 or the foaming gas 31a. Examples of the foaming agent 31 include a method of putting it together with a plastic material from the hopper 20 and a method of putting it into the injection cylinder 19. It is also possible to inject the foaming gas 31a from the nozzle 21. As a method for introducing the foaming gas from the nozzle 21, there is a method in which the flow path of the plastic material in the nozzle 21 is made of a porous sintered material and high pressure gas is mixed from the sintered material.

[Fourth Embodiment]
Hereinafter, the structure of the molding apparatus shown in FIG. 7 and the method for producing the foam molded product according to the structure will be described. This molding apparatus is roughly divided into a hopper 30, an injection device 40, a mold 50, a gas cylinder 60, a supercritical fluid generator 70, a control device (not shown), and the like. The injection device 40 is an inline screw injection molding machine including a cylinder 41, a screw 47, and the like. A heater 42 is provided on the outer periphery of the cylinder 41, a molten resin injection port 43 is formed at the tip of the cylinder 41, and a nozzle 44 that can be opened and closed is provided at the injection port 43. The cylinder 41 is further provided with a supercritical fluid injection portion 81 and an injection device 82 having a flow control valve. Further, a staying cavity 45 in which the molten resin before injection stays is formed between the screw head 47 b that is the tip of the screw 47 and the nozzle 44. The mold 50 has a cavity 53 formed by abutment of the fixed mold 51 and the movable mold 52. The gas cylinder 60 is filled with a gas used as a foaming agent (incombustible gas such as carbon dioxide and nitrogen). The supercritical fluid generator 70 is for changing the gas from the gas cylinder 60 to a supercritical state and supplying it to the injection device 40 as a supercritical fluid. In FIG. 7, reference numeral 47a is a low-pressure section, and 71 is a pipe. . Symbol Ga is a resin material, and Gb is a molten resin.

  In the production of the foam molded product, the pellet-shaped resin material Ga is put into the hopper 30. The resin material Ga supplied into the cylinder 41 is melted while being transferred toward the screw head 47b through the cylinder 41 by the rotation of the screw 47. The molten resin material Ga, that is, the molten resin Gb is mixed with the supercritical fluid in the low pressure portion 47 a of the screw 47. In this case, the supercritical fluid from the supercritical fluid generator 70 is injected into the cylinder 41 via the injection device 82, and the supercritical fluid is transferred to the screw head 47b while the molten resin Gb is further transferred toward the screw head 47b. The molten resin Gb is uniformly mixed and impregnated.

  The molten resin Gb is accumulated in the cavity 45. When the pressure in the cavity 45 reaches a predetermined value, the nozzle 44 is opened, whereby the molten resin Gb in the cavity 45 is injected and filled into the cavity 53 of the mold 50. At this time, the internal temperature and the internal pressure of the molten resin Gb rapidly decrease, and as a result, the state of the supercritical fluid in the molten resin Gb changes to a gas, and fine foam cells are grown and formed in the resin material. The final degree of growth of each foam cell, that is, the diameter of each foam cell, is determined by the temperature difference and pressure difference before and after injection in the resin material, and the temperature decrease rate and pressure decrease rate during injection.

  The foamed molded product manufacturing method as shown in FIG. 7 can be effectively applied to the plastic molded product manufacturing method described in claim 10 or 11.

  In the molded product thus molded, fine foam cells in which the nonflammable gas is sealed are densely dispersed. Therefore, this molded product shows good flame retardancy. Moreover, since nonflammable gas is utilized as a flame retardant, no harmful substances derived from the flame retardant are generated during combustion. In addition, since the foamed cells are formed with a large occupation ratio, it is lightweight, and such a flame-retardant foam molding exhibits an excellent function as an exterior part of home appliances, OA equipment and the like.

It is a figure which shows the exterior component cross-sectional shape of the OA apparatus by this invention (1st Embodiment). It is a figure which shows the manufacturing method of the plastic molded product of this invention by the injection molding method. It is a figure which shows the exterior components cross-sectional shape of OA apparatus by this invention (2nd Embodiment). It is a figure which shows the manufacturing method of the plastic molded product of this invention by a sandwich molding method. It is a figure which shows the exterior components cross-sectional shape of the household appliances by this invention (3rd Embodiment). It is a figure which shows the mixing method of a foaming agent. It is a figure which shows the shaping | molding apparatus which uses a supercritical fluid as a foaming material (4th Embodiment). It is a figure which shows the exterior components cross-sectional shape of the target OA apparatus. It is a figure which shows the problem of the prior art which arises when shape | molding the exterior components of OA apparatus.

Explanation of symbols

1 OA equipment exterior parts (plastic moldings)
2 Rib 3 Gate 3A Cavity 4 Skin layer 5 Core layer 5a Air hole 6 Outer part of OA equipment (plastic molding)
7 1st flow path 8 2nd flow path 9 1st injection unit 10 2nd injection unit 11 Petroleum raw material plastic (polycarbonate)
12 Biomass raw material plastic (polylactic acid)
13 Discharge port 14 Petroleum raw material plastic injection 15 Biomass raw material plastic injection 16 Cavity 17 Mold 18 Exterior parts of home appliances (plastic molding)
19 Injection cylinder 20 Hopper 21 Nozzle 27 Exterior parts of OA equipment (molded product)
28 OA equipment exterior parts (molded products)
Reference Signs List 30 hopper 31 foaming agent 31a foaming gas 40 injection device 50 mold 60 gas cylinder 70 supercritical fluid generator

Claims (11)

  It is a molded product whose main material is a plastic material made by mixing a plastic material made of biomass (hereinafter referred to as biomass raw material plastic) and a plastic material made from petroleum (hereinafter referred to as petroleum raw material plastic). A plastic molded product comprising a skin layer forming a surface layer portion and a core layer forming a central portion, and pores are formed in the core layer.   A molded product comprising a skin layer forming a surface layer portion and a core layer forming a central portion, wherein the skin layer is formed from petroleum raw material plastic as a main material, and the core layer is formed from biomass raw material plastic as a main material. And a plastic molded product characterized in that pores are formed in the core layer.   The plastic molded article according to claim 2, wherein the petroleum raw material plastic is an amorphous plastic and has a glass transition temperature lower than a melting temperature of the biomass raw material plastic.   The plastic molded article according to claim 2, wherein the petroleum raw material plastic is a crystalline plastic, and a softening temperature thereof is lower than a melting temperature of the biomass raw material plastic.   The plastic molded article according to any one of claims 1 to 4, wherein the plastic molded article is an exterior part of an electrical product.   In manufacturing the molded product according to claim 1, after plastic material, which is made by mixing biomass raw material plastic, petroleum raw material plastic and foaming agent and alloyed, is injected and filled in the die, the die is cooled. A method for producing a plastic molded product, wherein the molded product is produced by an injection molding method in which the molded product is removed from a mold.   In producing the molded article according to claim 1, a plastic material obtained by mixing biomass raw material plastic and petroleum raw material plastic and impregnating the plastic material is impregnated with a supercritical fluid, and the plastic material is injected and filled in a mold, A method for producing a plastic molded product, wherein the molded product is produced by an injection molding method in which a molded product is taken out from the die after cooling the mold.   In manufacturing the molded article according to any one of claims 2 to 4, a foaming agent is added to inject and fill a petroleum raw material plastic to form a skin layer into a mold and then form a core layer. A method for producing a plastic molded product, characterized in that it is manufactured by a sandwich molding method in which a biomass raw material plastic is injected and filled into a mold, cooled, and then the molded product is taken out from the mold.   When producing the molded article according to any one of claims 2 to 4, a petroleum raw material plastic for forming a skin layer and a biomass raw material plastic to which a foaming agent is added to form a core layer are simultaneously molded. A method for producing a plastic molded product, characterized in that the molded product is produced by a sandwich molding method in which the molded product is injected and filled, cooled, and then taken out of a mold.   In producing the molded article according to any one of claims 2 to 4, a supercritical fluid to be formed by injection-filling a petroleum raw material plastic for forming a skin layer into a mold and then forming a core layer is impregnated. A method for producing a plastic molded article, wherein the biomass raw material plastic is injected and filled into a mold, cooled, and then molded by a sandwich molding method in which the molded article is taken out of the mold. In producing the molded article according to any one of claims 2 to 4, a petroleum raw material plastic for forming a skin layer and a biomass raw material plastic impregnated with a supercritical fluid for forming a core layer are simultaneously formed. A method for producing a plastic molded article, characterized by producing by a sandwich molding method in which a mold is injected and filled, cooled and then taken out of the mold.

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