JP2013023266A - Container and container injection molding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly recyclable container having superior rigidity and shock resistance property.SOLUTION: The container A includes a bottom surface 1, a peripheral wall 2 extending upward from an outer periphery of the bottom surface 1, and a flange 3 extending outward from the peripheral wall 2. A remaining part excluding the flange 3 and the upper end of the peripheral wall 2 comprises a core 4 made of a first thermoplastic resin containing at least one type of a polyolefin resin and a chlorine-containing resin of 0.01 to 3.0 wt.%, and a skin layer 5 which is made of a second thermoplastic resin and covers the core 4. The flange 3 and the upper end 21 of the peripheral wall 2 are made of the second thermoplastic resin.

Description

  The present invention relates to a container having excellent rigidity and impact resistance and excellent recyclability, and an injection molding method thereof.

  The enforcement of the Containers and Packaging Recycling Law stipulates that plastic containers and packaging waste, which accounts for approximately 60% (volume ratio) of household waste, is collected and effectively used as resources. Plastic container packaging waste was washed, separated, and crushed and then separated by specific gravity to separate a mixture of polyolefin resins having a low specific gravity, such as polyethylene resins and polypropylene resins, and thus obtained. The mixture is also referred to as “container packaging recycling material” and is reused as a raw material for a new molded article (Patent Document 1). It is difficult to completely remove impurities in the separation process and the specific gravity separation process. Therefore, the container and packaging recycling materials usually contain a small amount of chlorine-containing resins such as polyvinyl chloride and polyvinylidene chloride in addition to polyolefin resins. .

  However, most of the polyolefin-based resins that are the main components of the above-described container packaging recycling materials are obtained from plastic bags contained in container packaging waste, packaging films for wrapping products, and the like. Since plastic bags and packaging films need to be thin but strong, these materials include high-density polyethylene resins, low-density polyethylene resins, linear low-density polyethylene resins, and polypropylene-based materials. A polyolefin resin having a high molecular weight such as a resin is used. These polyolefin resins having a high molecular weight have poor fluidity at the time of melting, and as a result, the fluidity of container and packaging recycling materials (melt flow rate (MFR) 0.1 to 3.0 g / 10 minutes) also deteriorates. Such a container and packaging recycle material has a problem that it is not suitable for manufacturing a molded article by injection molding.

  On the other hand, containers are widely used for transporting articles, and these containers are generally formed by injection molding. And since a container is used in order to transport goods, it is requested | required that it is excellent in rigidity and impact resistance.

  As mentioned above, recycling is being promoted from the viewpoint of protecting the global environment. However, recycled containers and packaging materials are not suitable for injection molding, and injection molded products obtained using recycled containers and packaging are rigid. In addition, since there is a problem that the impact resistance is insufficient, it is not possible to use a container / packaging recycle material for a container that may store and transport heavy objects.

  In addition, in order to improve the fluidity of the container and packaging recycle material, the high fluidity polypropylene resin (MFR: 80 to 150 g / 10 min) and the high fluidity polyethylene resin (MFR: 100 to 170 g / min) are used for the container and package recycle material. A means of adding 10 minutes) is also conceivable. However, even with these highly fluid resins, the fluidity of the container and packaging recycling material cannot be sufficiently improved. Furthermore, the high-fluidity resin is expensive, and as a result, the cost for recycling the container and packaging recycle material is increased, so the use of the high-fluidity resin is not practical.

Japanese Patent Laid-Open No. 2006-123412

  The present invention provides a container having excellent recyclability and excellent rigidity and impact resistance, and an injection molding method thereof.

  The container of the present invention is a container having a bottom surface portion, a peripheral wall portion extending upward from the outer peripheral edge portion of the bottom surface portion, and a flange portion extending outward from the peripheral wall portion. The remaining part except the upper part of the said collar part and the said surrounding wall part is comprised from the 1st thermoplastic resin containing at least 1 type of polyolefin resin and 0.01 to 3.0 weight% chlorine containing resin. The core portion is composed of a skin layer that covers the core portion and is made of the second thermoplastic resin, and the upper end portions of the flange portion and the peripheral wall portion are made of the second thermoplastic resin. It is characterized by that.

  In the container, the second thermoplastic resin does not contain a chlorine-containing resin.

  The container injection molding method of the present invention is a container injection molding method in which a first thermoplastic resin and a second thermoplastic resin are injected and molded into a cavity of a mold, wherein the cavity has a bottom portion of the container. A bottom surface portion forming portion to be molded, a peripheral wall portion forming portion that is continuous with the outer peripheral edge portion of the bottom surface portion forming portion and forming the peripheral wall portion, and a collar that is continuous with the upper end portion of the peripheral wall portion forming portion and is formed with the flange portion At least one polyolefin-based resin through the gate port in the cavity after injecting the second thermoplastic resin through the gate port leading to the bottom surface forming unit in the cavity. And a first thermoplastic resin containing 0.01 to 3.0% by weight of chlorine-containing resin, and the first thermoplastic resin is the first thermoplastic resin and the second thermoplastic resin is the above-mentioned first thermoplastic resin. The inside of the cavity is made to flow in a state covered with two thermoplastic resins, and the end portions of the flange forming portion and the peripheral wall portion forming portion connected thereto are filled with the second thermoplastic resin, The remaining portion of the cavity excluding the flange forming portion and the end of the peripheral wall forming portion connected to the first thermoplastic resin and the second thermoplastic resin is used as the first thermoplastic resin. It is characterized by filling in a state covered with two thermoplastic resins.

  In the container injection molding method, the second thermoplastic resin does not contain a chlorine-containing resin.

  The container of the present invention has the above-described configuration, and the core portion of the remaining portion excluding the upper end portion of the flange portion and the peripheral wall portion includes at least one kind of polyolefin resin and 0.01 to 3.0% by weight. Since it is comprised from the 2nd thermoplastic resin containing chlorine containing resin and a container packaging recycling material can be used, it is excellent in recyclability.

  And since the container is lifted and moved by gripping its heel part, it is necessary that the outer part of the heel part and the peripheral wall part be easily applied with an external force that distorts the container, and is strong. It is not necessary to use the first thermoplastic resin for the upper part of the wall part and the peripheral wall part, and the upper end part of the collar part and the peripheral wall part is not damaged when a heavy object is stored and lifted or transported. The upper end portion of the flange portion and the peripheral wall portion has excellent rigidity and impact resistance.

  Further, the remaining portion excluding the flange portion and the upper end portion of the peripheral wall portion of the container is composed of a first thermoplastic resin containing at least one type of polyolefin resin and 0.01 to 3.0% by weight of chlorine-containing resin. The core portion and the skin layer that covers the core portion and is made of the second thermoplastic resin, although the first thermoplastic resin constituting the core portion has low rigidity and impact resistance, The core portion is covered and reinforced by a skin layer made of a second thermoplastic resin having excellent rigidity and impact resistance. Therefore, the remaining portion excluding the upper end portion of the container flange portion and the peripheral wall portion is Overall, it has excellent rigidity and impact resistance.

It is the perspective view which showed the container of this invention. It is the longitudinal cross-sectional view which showed the container of this invention. It is the schematic cross section which showed the molding point of the container of this invention. It is the schematic cross section which showed the molding point of the container of this invention. It is the schematic cross section which showed the molding point of the container of this invention.

  An example of the container of the present invention will be described with reference to the drawings. As shown in FIGS. 1 and 2, the container A includes a bottom surface portion 1 having a rectangular plane shape and a peripheral wall portion 2 having a rectangular frame shape extending upward from the four-side outer peripheral edge portion of the bottom surface portion 1. And a flange portion 3 extending outward from the upper end portion 21 of the peripheral wall portion 2.

  The remaining portion of the container A excluding the flange 3 and the upper end portion 21 of the peripheral wall portion 2, that is, the remaining portion of the peripheral wall portion 2 of the container A excluding the upper end portion 21 and the bottom surface portion 1 is the core portion 4. It is composed of a skin layer 5 covering the core portion 4. The core part 4 is comprised from the 1st thermoplastic resin containing at least 1 type of polyolefin resin and 0.01 to 3.0 weight% chlorine containing resin.

  The first thermoplastic resin generally contains a small amount of chlorine-containing resin in addition to the polyolefin resin as a main component.

  Examples of polyolefin resins include low density polyethylene resins, medium density polyethylene resins, high density polyethylene resins, linear low density polyethylene resins, linear medium density polyethylene resins, and linear high density polyethylene resins. And polyethylene resins such as copolymers of ethylene and other olefins, and polypropylene resins such as propylene homopolymers and copolymers of propylene and other olefins. In addition, polyolefin resin may be used independently or 2 or more types may be used together.

  Examples of the olefin copolymerized with ethylene include α-olefins such as propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-nonene and 1-decene. Etc.

  Examples of the olefin copolymerized with propylene include α-olefins such as ethylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-nonene and 1-decene. Etc.

  The polyethylene resin means an ethylene homopolymer and a copolymer containing more than 50% by weight of an ethylene component. Moreover, a polypropylene resin means the copolymer containing a propylene homopolymer and a propylene component exceeding 50 weight%.

  As described above, since the synthetic resin film used for packaging is required to be thin but strong, a polyolefin resin having a relatively high molecular weight and a low melt flow rate as a raw material for the synthetic resin film Is used. Therefore, the molecular weight of the polyolefin resin, which is the main component of the container and packaging recycling material, is also high. Specifically, the viscosity average molecular weight Mv of the polyethylene resin contained as the polyolefin resin in the container and packaging recycling material is usually 100,000 to The viscosity average molecular weight Mv of the polypropylene resin contained in the container and packaging recycling material as the polyolefin resin is usually 100,000 to 1,000,000, particularly 100,000 to 500,000. .

  In the present invention, the viscosity average molecular weight of the polyolefin resin is a value calculated based on the universal method by measuring the viscosity of the polyolefin resin by a method based on JIS K7367-3 (1991). For example, it can be measured using the following method. In addition, the viscosity average molecular weight of the non-modified polypropylene wax described later can also be measured in the same manner.

A polyolefin resin is dissolved in decahydronaphthalene (135 ° C.) to prepare a solution having a concentration (C) of 6.0 g / L. Using a Ubbelohde capillary viscometer with a decahydronaphthalene flow-down time (t ₀ ) of 130 seconds, the flow-down time (t) of the sample solution is measured in a constant temperature water bath set at 25 ° C. Using the measured flow-down time (t), the viscosity average molecular weight Mv is calculated by the following formula.
Mv = 1.03 × 10 ⁻⁴ × η ^0.78
a = 0.438 × η _sp +1
b = 100 × η _sp / C
Where η _{sp is the} intrinsic viscosity
η _sp = t / t ₀ −1
C = 6.0 (g / L)
η = b / a

  In addition, the melt flow rate of the polyolefin resin that is the main component of the first thermoplastic resin is specifically preferably 5.0 g / 10 min or less, and more preferably 1.0 to 3.0 g / 10 min. The melt flow rate of the polyolefin resin means a value measured at 220 ° C. and a load of 2.16 kgf (21.18 N) in accordance with JIS K7210.

  The content of the polyolefin resin in the first thermoplastic resin is usually 50% by weight or more, preferably 90% by weight or more, more preferably 95%, based on the total amount of the resin components of the first thermoplastic resin. ˜99.99% by weight.

  The first thermoplastic resin also includes chlorine-containing resins containing chlorine atoms in the molecule, such as polyvinyl chloride and polyvinylidene chloride. The content of the chlorine-containing resin in the first thermoplastic resin is generally 0.01 to 3.0% by weight with respect to the total amount of the resin components of the first thermoplastic resin.

  The first thermoplastic resin may contain inevitable impurities that are difficult to remove completely, in addition to the above-described polyolefin-based resin and chlorine-containing resin. Inevitable impurities include thermoplastic resins such as polystyrene resins, polyester resins (for example, polyethylene terephthalate), polyamide resins, and inorganic substances (for example, metals). The content of inevitable impurities in the first thermoplastic resin is generally 0 to 5% by weight, particularly 0 to 2% by weight, based on the total amount of the first thermoplastic resin.

  Moreover, a container packaging recycling material can be used as a 1st thermoplastic resin. Recycled containers and packaging materials can be obtained by pretreatment such as separation, washing, crushing, and specific gravity separation of plastic waste collected by the local government, and further pelleting, volume reduction (crushing) by performing a granulation process The product may be used as a raw material after being molded into a predetermined shape such as compression and solidification.

  Further, the first thermoplastic resin may contain non-modified polypropylene wax. Non-modified polypropylene wax is polypropylene having a viscosity average molecular weight of 5,000 to 30,000 obtained by polymerizing propylene, and such polypropylene is generally referred to as polypropylene wax. Non-modified polypropylene wax is not modified with an acid monomer such as maleic acid, acrylic acid, methacrylic acid or maleic anhydride and is not oxidatively modified. Therefore, a carbonyl group (> C = O), carboxyl group (—COOH), and hydroxyl group (—OH) are not included.

  Non-modified polypropylene wax is manufactured as a new product, and is not obtained from molded products, but is a so-called unused one that is used by being molded into a container or packaging even once. It is different from the polyolefin-based resin made and the container / packaging recycling material containing the same.

  The viscosity average molecular weight of the polypropylene constituting the unmodified polypropylene wax is preferably 5,000 to 20,000, and more preferably 5,000 to 10,000. Non-modified polypropylene wax made of polypropylene having a viscosity-average molecular weight that is too high not only has low compatibility with polyolefin resins, but may not sufficiently improve the fluidity of the first thermoplastic resin when melted. . Further, unmodified polypropylene wax made of polypropylene having a viscosity average molecular weight that is too low may bleed out on the surface of the obtained container.

  Examples of the non-modified polypropylene wax include a propylene homopolymer and a copolymer of propylene and another olefin containing 50% by weight or more of a propylene component. Examples of propylene and other olefins include α-olefins such as ethylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-nonene, and 1-decene. Is mentioned. The copolymer of propylene and another monomer may be a block copolymer or a random copolymer.

  Among these, as the non-modified polypropylene wax, a copolymer of propylene and ethylene is preferably exemplified. According to the copolymer of propylene and ethylene, the fluidity at the time of melting of the first thermoplastic resin can be improved.

  The non-modified polypropylene wax is preferably used in an amount of 1 to 10 parts by weight, more preferably 3 to 10 parts by weight, and particularly preferably 3 to 6 parts by weight with respect to 100 parts by weight of the total amount of polyolefin resin and chlorine-containing resin. By using the unmodified polypropylene wax in such an amount, a container excellent in mechanical strength can be provided, and a first thermoplastic resin excellent in fluidity at the time of melting can be obtained.

  The softening point of the unmodified polypropylene wax is preferably 140 to 160 ° C, and more preferably 148 to 158 ° C. If the softening point of the unmodified polypropylene wax is too high, the fluidity at the time of melting of the first thermoplastic resin may not be sufficiently improved. If the softening point of the unmodified polypropylene wax is too low, the wax may bleed out on the surface of the container.

  The softening point of the unmodified polypropylene wax is a value measured according to JIS K2207.

  The unmodified polypropylene wax is preferably obtained by thermally decomposing a high molecular weight polypropylene having a weight average molecular weight of 50,000 to 150,000 produced using a Ziegler catalyst in an inert gas at 300 to 450 ° C. It is done. According to the non-modified polypropylene wax obtained by pyrolysis, it is possible to provide a first thermoplastic resin that is excellent in fluidity at the time of melting and can improve the mechanical strength of the resulting container. In addition, as the non-modified polypropylene wax, a metallocene polypropylene wax produced using a metallocene catalyst may be used. Conventionally, non-modified polypropylene waxes are generally used as toner materials for electrostatic copying, paper quality improvers, ink wear resistance improvers, hot melt adhesive additives, etc. It is not used for improving the fluidity at the time of melting of the first thermoplastic resin as in the invention.

  Commercially available products can be used as the non-modified polypropylene wax described above. For example, (product name) Viscol 330-P, Viscol 550-P, Viscol 660-P, manufactured by Sanyo Chemical Industries, Ltd., Mitsui Chemicals, Inc. (Product name) Mitsui High Wax NP055, Mitsui High Wax NP105, Mitsui High Wax NP805, and (Product Name) Hoechst Wax PP230 manufactured by Hoechst.

  The skin layer 5 is made of a second thermoplastic resin. The second thermoplastic resin may be a new product or may be obtained from a molded product as a raw material, but since a suitable thermoplastic resin for injection molding can be selected, the new product It is preferable that it is manufactured as.

  The second thermoplastic resin produced as the above-mentioned new product is not a product obtained from a molded product as a raw material, but a so-called unused one, and heat used by being molded into a molded product even once. Plastic resin is excluded.

  The second thermoplastic resin is not particularly limited as long as it is a thermoplastic resin conventionally used for sandwich injection molding, and examples thereof include polyolefin resins, polyamide resins, polystyrene resins, polyester resins, and the like. Polyolefin resins are preferred. In addition, a thermoplastic resin may be used independently or 2 or more types may be used together. Since the polyolefin resin is the same as described above, the description thereof is omitted.

  The second thermoplastic resin preferably does not contain a chlorine-containing resin both when the second thermoplastic resin is produced as a new product and when it is obtained from a molded product. Examples of such a chlorine-containing resin include thermoplastic resins containing chlorine atoms in the molecule, such as polyvinyl chloride and polyvinylidene chloride.

  If the melt flow rate (MFR) of the second thermoplastic resin is small, the second thermoplastic resin may stay in the cavity and a good molded product may not be obtained. May occur, 5 to 80 g / 10 min is preferable, and 10 to 30 g / 10 min is more preferable. The melt flow rate of the second thermoplastic resin is a value measured in accordance with JIS K7210: 1999.

  As described above, in the container A of the present invention, the remaining portion excluding the upper end portion 21 and the bottom surface portion 1 of the peripheral wall portion 2 are the core portion 4 made of the first thermoplastic resin, and the core portion 4. And the core layer 4 can be made of a recycled material such as a container and packaging recycle material, and is excellent in recyclability, and the skin layer 5 made of the second thermoplastic resin. The skin layer 5 covering the core portion 4 compensates for the decrease in rigidity and impact resistance of the core portion 4.

  When the container A is used, unlike the flange 3 and the upper end portion 21 of the peripheral wall portion 2, the remaining portion excluding the upper end portion 21 of the peripheral wall portion 2 and the bottom surface portion 1 have so much external force that distorts them. It is not added, and the use of the container A can be sufficiently endured by covering the core portion 4 with the skin layer 5 and complementing the rigidity and impact resistance.

  The flange 3 and the upper end 21 of the peripheral wall 2 of the container A of the present invention are entirely composed of the second thermoplastic resin described above, and the remaining portion excluding the upper end 21 of the flange 3 and the peripheral wall 2. The core layer is the same as the skin layer 5 in FIG. 1 and there is no core portion in the remaining portion excluding the flange portion 3 and the upper end portion 21 of the peripheral wall portion 2.

  When the container A is used, the collar part 3 of the container A is gripped and lifted. At this time, strain stress is applied to the collar part 3 and the upper end part 21 of the peripheral wall part 2 continuous to the collar part 3. As described above, the second thermoplastic resin constituting them has excellent rigidity and impact resistance, so it is not easily damaged, and the container A should be used stably. Can do.

  Next, a method for forming the container A will be described. As a manufacturing method of the container A, for example, as shown in FIG. 3, in the cavity 7 of the mold 6, the bottom part 1 of the container A, preferably the part that forms the central part of the bottom part 1 of the container A is used. The remaining skin layer 5 excluding the flange 3 and the upper end 21 of the peripheral wall 2 and the second thermoplastic resin T2 constituting the flange 3 and the upper end 21 of the peripheral wall 2 were injected through the communicating gate port. Thereafter, the first thermoplastic resin T1 constituting the remaining core portion 4 excluding the flange portion 3 and the upper end portion 21 of the peripheral wall portion 2 is injected into the cavity 7 through the gate port, and the second thermoplastic resin is injected. The container A can be formed by causing the resin T2 and the first thermoplastic resin T1 to flow in layers in the cavity 7. In this molding process, the first thermoplastic resin T1 flows in the cavity 7 of the mold 6 while being covered with the second thermoplastic resin T2. When the second thermoplastic resin T2 does not contain a chlorine-containing resin, the chlorine-containing resin does not contact the mold, and the chlorine-containing resin decomposes when the chlorine-containing resin contacts the mold. The generated chlorine can prevent the problem of corrosion of the mold. As shown in FIG. 3, the cavity 7 of the mold 6 includes a bottom surface portion forming portion 71 for molding the bottom surface portion 1 of the container A, and an outer peripheral edge portion of the bottom surface portion forming portion 71 and a peripheral wall portion. 2 has a peripheral wall portion forming portion 72 for forming 2, and a flange portion forming portion 73 for forming the flange portion 3 that is continuous with the upper end portion of the peripheral wall portion forming portion 72.

  In the manufacturing method of the container A, a general-purpose sandwich injection molding machine is used. As a sandwich injection molding machine, for example, two extruders are connected to the same mold and a thermoplastic resin can be separately injected from these extruders into the mold cavity and filled. An injection molding machine is mentioned.

  Specifically, first, the second thermoplastic resin is supplied to one extruder of the sandwich injection molding machine and melt-kneaded, and then the bottom surface portion 1 of the container A is inserted into the cavity 7 of the mold 6 from the extruder. Preferably, the second thermoplastic resin T2 is injected and filled through the gate port 7a leading to the portion forming the center of the bottom surface 1 of the container A (see FIG. 3). Since the first thermoplastic resin T1 is subsequently injected and filled in the cavity 7 of the mold 6 from the other extruder, the second thermoplastic resin T2 is completely contained in the cavity 7. It is injected and filled to the extent that it is not filled. The filling of the thermoplastic resin into the cavity 7 of the mold 6 is performed from the center of the bottom surface forming part 71 of the cavity 7.

  And when the 2nd thermoplastic resin T2 is what was manufactured as a new product, it has the fluidity | liquidity which was especially excellent in the molten state, and it mentions in the cavity 7 of the metal mold | die 6 so that it may mention later. When the first thermoplastic resin T1 is injected and filled, the second thermoplastic resin T2 does not stay in the cavity 7, flows smoothly along the shape of the cavity 7, and has no gap in the cavity 7. As a result, the container A having an excellent appearance can be obtained.

  Next, after the first thermoplastic resin T1 is supplied to the other extruder of the sandwich injection molding machine and melt-kneaded, the gate is placed in the cavity 7 of the mold 6 that is already filled with the second thermoplastic resin T2. The first thermoplastic resin T1 is injected and filled from the extruder through the mouth (see FIG. 4).

  Then, as the first thermoplastic resin T1 is injected into the cavity 7 and filled, the second thermoplastic resin T2 is pushed into the cavity 7, but as described above, the second thermoplastic resin T2 flows in the molten state. Since it is excellent in properties, it can flow along the shape of the cavity 7 without staying in the cavity 7 to fill the gap in the cavity 7, and the second thermoplastic resin T2 is the same as the first thermoplastic resin T1. Almost no mixing occurs, and the first thermoplastic resin T1 and the second thermoplastic resin T2 flow while forming layers with each other (see FIGS. 4 and 5).

  Since the first thermoplastic resin T1 has relatively poor fluidity as described above, the first thermoplastic resin T1 does not reach the entire inside of the cavity 7 of the mold 6, and the bottom surface portion forming portion 71 of the cavity 7 has an overall structure. However, the upper end portion of the peripheral wall portion forming portion 72 cannot be sufficiently extended, and the upper end portion of the peripheral wall portion forming portion 72 and the flange portion forming portion 73 of the cavity 7 are filled only with the second thermoplastic resin T2. It will be in the state. On the other hand, the remaining portion of the cavity except for the upper end portion of the peripheral wall portion forming portion 72 and the flange forming portion 73 of the cavity 7 is filled with the first thermoplastic resin T1 and the second thermoplastic resin T2, and The one thermoplastic resin T1 is covered with the second thermoplastic resin T2, the core portion 4 is formed by the first thermoplastic resin T1, and the core portion 4 is covered by the second thermoplastic resin T2. A skin layer 5 is formed.

  Furthermore, although the first thermoplastic resin T1 is relatively poor in fluidity, the first thermoplastic resin T1 is covered with the second thermoplastic resin T2 in the cavity 7, so that the core of the container A The part 4 is not visually recognized from the outside and does not affect the appearance of the container A. Therefore, the container A having an excellent appearance can be easily manufactured while recycling.

  The container A molded in this manner has no core portion formed on the flange portion 3 and the upper end portion 21 of the peripheral wall portion 2, and is composed of only the second thermoplastic resin T2, and the flange portion 3 The upper end portion 21 of the peripheral wall portion 2 has excellent rigidity and impact resistance, and when the container A is used, a strain stress is applied to the flange portion 3 and the upper end portion 21 of the peripheral wall portion 2. The container A can be used stably after the desired article is stored in the container A.

  And the container A is excellent in recyclability because it can use a recycle raw material such as a container and packaging recycle material in the core portion in the remaining portion excluding the flange portion 3 and the upper end portion 21 of the peripheral wall portion 2. The core portion 4 is covered with the skin layer 5 and the lack of rigidity and impact resistance of the core portion 4 is complemented by the skin layer 5 so as to have the rigidity and impact resistance necessary for the container as a whole. A has excellent recyclability and has rigidity and impact resistance necessary for the container as a whole.

  Next, examples of the present invention will be described, but the present invention is not limited to the following examples.

Example 1
A sandwich injection molding machine in which two extruders were connected to the same mold 6 was prepared. As shown in FIG. 3, the cavity 7 of the mold 6 is continuous with the bottom surface portion forming portion 71 having a flat rectangular shape for forming the bottom surface portion 1 of the container A, and the outer peripheral edge of the bottom surface portion forming portion 71. A peripheral wall portion forming portion 72 having a rectangular frame shape for forming the peripheral wall portion 2, and a square frame-shaped flange portion forming portion 73 for forming the flange portion 3 that is continuous with the upper end portion of the peripheral wall portion forming portion 72. ing. In the cavity 7, a gate port 7 a for injecting and filling the thermoplastic resin into the cavity 7 is formed at the center of the bottom surface portion forming portion 71, and the thermoplastic resin enters the cavity 7 from the gate port 7 a. It was configured to be injection and filling.

  As a second thermoplastic resin, 100 parts by weight of a polypropylene resin that is manufactured as a new product and does not contain a chlorine-containing resin (trade name “BC3LS” manufactured by Nippon Polypro Co., Ltd., melt flow rate: 10 g / 10 min) is used as a sandwich injection molding machine. The second thermoplastic resin T2 was injected into the cavity 7 of the mold 6 through the gate port 7a and filled. The injection conditions were a resin temperature in the extruder of 220 ° C., a mold 6 temperature of 30 ° C., an injection speed of 50 mm / second, an injection pressure of 100 MPa, and an injection time of 4 seconds.

  Next, as a first thermoplastic resin, a container and packaging recycle material (melt flow rate: 1.7 g / 10 min, composition: polyethylene resin 55% by weight, polypropylene resin 43% by weight, polyvinyl chloride 0.3% by weight, And 30 parts by weight of inevitable impurities (1.7% by weight) are supplied to the other extruder of the sandwich injection molding machine and melt-kneaded, and the first thermoplastic resin T1 is put into the cavity 7 of the mold 6 through the gate port 7a. Injection and filling. The injection conditions were a resin temperature in the extruder of 220 ° C., a mold 6 temperature of 30 ° C., an injection speed of 50 mm / second, an injection pressure of 100 MPa, and an injection time of 4 seconds.

  Then, the second thermoplastic resin T2 previously filled in the cavity 7 of the mold 6 is subsequently injected into the cavity 7 and injected into the cavity 7 by the injection of the first thermoplastic resin T1 and the filling pressure. 7 is pushed into the cavity 7 and flows along the shape of the cavity 7 to fill the cavity 7 without gaps, and the first thermoplastic resin T1 is entirely covered with the second thermoplastic resin T2 in the cavity. 7, the cavity 7 of the mold 6 was filled with the second thermoplastic resin T2 and the first thermoplastic resin T1 without any gaps while forming a layer. In the cavity 7 of the mold 6, the first thermoplastic resin T1 was flowing in a state of being entirely covered with the second thermoplastic resin T2.

  Thereafter, the second thermoplastic resin T2 and the first thermoplastic resin T1 are cooled and solidified in the mold 6 so as to face upward from the planar rectangular bottom surface 1 and the outer peripheral edge of the bottom surface 1. A container A having a peripheral wall portion 2 that is extended and a flange portion 3 that extends outward from the upper end of the peripheral wall portion 2 was obtained.

  In the obtained container A, the upper end portion 21 of the flange portion 3 and the peripheral wall portion 2 is composed only of the second thermoplastic resin T2, and the remaining portion excluding the upper end portion 21 of the flange portion 3 and the peripheral wall portion 2 is The core portion 4 is made of a first thermoplastic resin, and the skin layer 5 is entirely covered with the core portion 4 except for the portion corresponding to the gate port 7a.

(Comparative Example 1)
An injection molding machine in which an extruder is connected to the mold 6 was prepared. Container and packaging recycling materials (melt flow rate 1.7 g / 10 min, composition: 55% by weight of polyethylene resin, 43% by weight of polypropylene resin, 0.3% by weight of polyvinyl chloride, and 1.7% by weight of inevitable impurities) Was supplied to the extruder of the injection molding machine, melted and kneaded, and the container packaging recycling material was injected into the mold cavity and filled, and the mold was cooled to produce a container made of container packaging recycling material However, the container packaging recycling material stayed in the cavity, and the container could not be obtained. The injection conditions were such that the resin temperature in the extruder was 220 ° C., the temperature of the mold 6 was 30 ° C., the injection speed was 50 mm / second, the injection pressure was 100 MPa, and the injection time was 4 seconds.

1 Bottom part 2 Perimeter wall part
21 Upper end 3 ridge 4 core 5 skin layer 6 mold 7 cavity
7a Gate entrance
71 Bottom part forming part
72 Perimeter wall forming part
73 Ridge formation part

Claims (4)

In a container having a bottom surface portion, a peripheral wall portion extending upward from the outer peripheral edge portion of the bottom surface portion, and a flange portion extending outward from the peripheral wall portion, the flange portion and the peripheral wall The remaining part excluding the upper end of the part is composed of a first thermoplastic resin containing at least one polyolefin resin and 0.01 to 3.0% by weight of chlorine-containing resin, and the core And a skin layer made of a second thermoplastic resin, and the upper end portion of the flange portion and the peripheral wall portion is made of the second thermoplastic resin. . The container according to claim 1, wherein the second thermoplastic resin does not contain a chlorine-containing resin. In a container injection molding method for injecting and molding a first thermoplastic resin and a second thermoplastic resin into a cavity of a mold, the cavity includes a bottom surface portion forming portion for molding the bottom surface portion of the container, and the bottom surface A peripheral wall part forming part that is continuous with the outer peripheral edge part of the part forming part and molding the peripheral wall part, and a flange part forming part that is continuous with the upper end part of the peripheral wall part forming part and molds the flange part, After injecting the second thermoplastic resin into the cavity through the gate port leading to the bottom surface portion forming portion, 0.01% to 3.0% by weight with at least one polyolefin resin through the gate port into the cavity. A first thermoplastic resin containing a chlorine-containing resin, and the first thermoplastic resin and the second thermoplastic resin are coated with the second thermoplastic resin. In this state, the inside of the cavity is caused to flow, and the end portion of the flange forming portion and the peripheral wall portion forming portion connected thereto are filled with the second thermoplastic resin, and the flange forming portion and The first thermoplastic resin is covered with the second thermoplastic resin with the first thermoplastic resin and the second thermoplastic resin in the remaining part of the cavity except for the end of the peripheral wall portion forming portion that is connected. A container injection molding method characterized by filling a state. 4. The container injection molding method according to claim 3, wherein the second thermoplastic resin does not contain a chlorine-containing resin.

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