JPH08224754A - Heat insulating tableware and manufacture thereof - Google Patents

Abstract

PURPOSE: To improve durability and to manufacture inexpensively by molding heat insulating tableware of resin moldings from three layers of a core layer and skin layers on both sides of the core layer with the use of a three-layer molding injection molding machine. CONSTITUTION: Heat insulating tableware molded by an injection molding machine 1 for molding three layers is composed of three layers of a core layer 2 and skin layers 3, 3 on both sides of the core layer 2, and the core layer 2 is enclosed by the skin layers 3, 3. The injection molding machine 1 has two cylinders 6a, 6b and a common nozzle 7, a skin material 9 is first injected from one cylinder 6a into the cavity 5 of a mold 4, a core material 10 is then injected from the other cylinder 6b, and next the skin material 9 is injected from the cylinder 6a so that heat insulating tableware A with three-layer structure is molded in which the core layer 2 of the core material 10 is enclosed with the skin layers 3, 3 of the skin material 9. A foamed resin, a recycled material of resin moldings, etc., are used for the core layer 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to heat-insulating tableware formed of a resin molded product and a method for producing the same.

[0002]

2. Description of the Related Art As tableware for resin molded products, preform is preformed between an outer surface member and an inner surface member formed of a resin molded product such as polypropylene (PP), polycarbonate (PC), polyphenylene ether (PPE) alloy. There is provided a heat-insulating tableware which is manufactured by friction welding an outer surface member and an inner surface member with a heat insulating material such as urethane foam resin sandwiched therebetween. However, in this one, after molding the outer surface member and the inner surface member respectively,
Since the heat insulating material is sandwiched and further welded,
There is a problem in productivity due to an increase in the number of manufacturing steps.Because the outer surface member and the inner surface member are bonded by friction welding in post-processing after molding, there is a point where they are bonded about one year after use. There is a risk of peeling, which is a serious problem in terms of durability.

In view of this, Japanese Patent Application Laid-Open No. 62-27119 provides a method for manufacturing heat-insulating tableware that does not require the step of laminating. That is, FIG. 4 shows a manufacturing method thereof. First, as shown in FIG. 4A, a thermosetting resin such as a melamine resin is molded into a cylindrical tablet to form the upper member 11a and the lower member 11b. Fabricate and make this upper member 1
A disc-shaped intermediate member 12 made of a thermoplastic resin such as foamed polyethylene is superposed between 1a and the lower member 11b, and the intermediate member 12 is first laminated and then compression-molded into a predetermined dish shape. Therefore, as shown in FIG.
It is possible to obtain the heat-insulating tableware A including the core layer 2 formed of the intermediate member 12, and the skin layer 3 formed of the upper member 11a and the lower member 11b laminated on the surfaces on both sides thereof.

[0004]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
In the case of the publication No. 119, since there is no need to carry out the bonding in a later step, there is no problem of peeling of the bonded part, but a tablet forming step, a laminating step and a compression molding step are required. However, the effect of reducing the number of steps is insufficient, it is not possible to increase productivity and manufacture the heat-insulating tableware at low cost, and the foamed polyethylene forming the core layer 2 is crushed during molding. There is also the problem that there are many cases.

The present invention has been made in view of the above points, and an object of the present invention is to provide a heat-retaining tableware which is excellent in durability and can be manufactured at low cost, and a manufacturing method thereof.

[0006]

The heat-insulating tableware of the present invention according to claim 1 is produced by molding with a three-layer injection molding machine 1, and a core layer 2 and skin layers on both sides of the core layer 2. 3,3
It is characterized by consisting of three layers. Claim 2
The invention according to (1) is characterized in that the core layer 2 is wrapped with a skin layer 3.

The invention according to claim 3 is characterized in that the core layer 2 is formed of a foamed resin. The invention according to claim 4 is characterized in that the core layer 2 is mixed with a low thermal conductive material. Claim 5
The invention according to (1) is characterized in that the core layer 2 is formed of a heat storage material.

The invention according to claim 6 is characterized in that the core layer 2 is blended with a recycled material of a resin molded product. The method for manufacturing heat-insulating tableware of the present invention according to claim 7 uses a three-layer injection molding machine 1 including two cylinders 6a, 6b and one nozzle 7 and uses a cavity 5 of a molding die 4.
The skin material 9 is injected by first injecting the skin material 9 from one cylinder 6a, then injecting the core material 10 from the other cylinder 6b, and then injecting the skin material 9 from the one cylinder 6a. The heat-insulating tableware A having a three-layer structure in which the core layer 2 of the core material 10 is wrapped in the layer 3 is formed.

The invention according to claim 8 is characterized in that, as the molding die 4 of the above-mentioned injection molding machine for three-layer molding, one having a gate 8 provided near the center of a cavity 5 is used. It is a thing. Hereinafter, the present invention will be described in detail. The injection molding machine 1 for three-layer molding, as shown in FIG.
It is formed by including two cylinders 6a, 6b and one nozzle 7 shared by both cylinders 6a, 6b. One cylinder 6a is provided with a skin material 9 from a hopper 16a and the other cylinder 6a. The core material 10 is supplied to the 6b from the hopper 16b. Screws 17a and 17b are provided in the cylinders 6a and 6b, respectively.
a, the skin material 9 and the core material 10 supplied from the hopper 16b are melted while being kneaded by the rotation of the screws 17a and 17b and sent forward, and the screw 17a,
By advancing 17b, the melted skin material 9 and core material 10 are injected from the nozzle 7.
Further, the nozzle 7 is a resin outflow passage 1 of one cylinder 6a.
The other cylinder 6b is provided in the nozzle chamber 19 through which 8 is communicated.
The resin outflow passage 20 is formed so as to have the tip thereof introduced, and the tip of the nozzle 7 is opened as a nozzle port 21.

Here, as the skin material 9, polypropylene resin (PP), polycarbonate resin (P
C), a polybutylene terephthalate resin (PBT), a polyethylene terephthalate resin (PET), a thermoplastic resin such as a polyester elastomer, or a thermosetting resin can be used. Further, as the core material 10, PP, PE
T, polyethylene (PE), polyamide resin (PA),
Thermoplastic resins and thermosetting resins such as polystyrene (PS), ethylene-propylene copolymer resin (EP), and polyester elastomer can be used. Further, it is preferable to select and use a resin having a difference in softening temperature of 0 to 80 ° C. for the skin material 9 and the core material 10.

In order to obtain the core layer 2 having a high heat insulating property, it is preferable to use, as the core material 10, a mixture of the above resin with a foaming agent or a resin having foamability. Further, the core layer 2 having a high heat insulating property can also be obtained by mixing the core material 10 with a low thermal conductive material such as cork powder, glass balloon, and cotton powder, which has a lower thermal conductivity than the core material 10. .

Further, by using the above-mentioned resin mixed with a heat storage material as the core material 10, it becomes possible to produce heat-retaining tableware having an improved heat-retaining or cold-retaining performance due to the heat storage effect of this heat-storage material. Is. As this heat storage material,
Inorganic hydration of sodium carbonate (10 hydrate), sodium sulfate (10 hydrate), calcium chloride (6 hydrate), sodium acetate (3 hydrate), etc. in a microcapsule of fluororesin or silicone resin It is possible to use, for example, a substance encapsulated in an amount of 10 to 50% by weight with respect to the resin, paraffins, or polyhydric alcohols such as polyethylene glycol and polypropylene glycol. The heat storage material preferably has a melting temperature of 45 to 70 ° C.

Further, as the core material 10, it is also possible to use the above resin mixed with a recycled material of a resin molded product. Since the core layer 2 formed from the core material 10 is not exposed on the surface, it is inexpensive, and even if a recycled material that is preferably reused for resource saving is used, there is no problem in appearance. is there. As such a recycled material, sprues, runners, burrs, and other discarded materials of the molded product can be crushed and used, and the content is within 60% by weight with respect to the core material 10. can do.

Thus, the injection molding machine 1 for three-layer molding described above.
When the heat-insulating tableware A is formed by using the mold, as shown in FIG. 1, a forming die 4 including a fixed die 4a and a movable die 4b.
The gate 8 and the nozzle opening 21 of the nozzle 7 of the three-layer injection molding machine 1 are connected. Then, first, the valve of the resin outflow passage 18 of the cylinder 6a is opened and the valve of the resin outflow passage 20 of the cylinder 6b is closed, and the screw 17a of the cylinder 6a is moved forward as shown in FIG. Is injected into the cavity 5 of the molding die 4. Next, the valve of the resin outflow passage 18 of the cylinder 6a is closed and the valve of the resin outflow passage 20 of the cylinder 6b is opened.
As shown in (b), the screw 17b of the cylinder 6b is advanced to eject the core material 10 from the nozzle into the cavity 5. The core material 10 is injected into the cavity 5 so as to be submerged in the skin material 9 previously injected into the cavity 5, and the skin material 9 is injected by the core material 10.
The core material 10 and the skin material 9 are filled in most of the space in the cavity 5 so as to spread the. When a foamable resin or a resin containing a foaming agent is used as the core material 10, the core material 10 starts foaming. After that, the valve of the resin outflow passage 18 of the cylinder 6a is opened again and the valve of the resin outflow passage 20 of the cylinder 6b is closed, and the screw 17a of the cylinder 6a is further advanced to remove the skin material 9 as shown in FIG. 1 (c). From the nozzle 7 to the cavity 5 of the molding die 4
By injecting into the inside, the portion of the gate 8 of the molding die 4 is filled with the skin material 9 to completely wrap the core material 10 with the skin material 9 and to completely fill the inside of the cavity 5 with the core material 10.
And the skin material 9 is filled. When a foamable resin or a resin mixed with a foaming agent is used as the core material 10, the core material 10 continues to foam. After the foaming of the core material 10 is completed, the core 4 is cooled and the molding die 4 is opened to obtain the rice bowl as shown in FIG. 2 or the heat-insulating tableware A used as a bowl, a plate or the like.

Heat-insulating tableware A molded as described above
Is formed in a three-layer structure in which the core layer 2 made of the core material 10 is wrapped with the skin layer 3 made of the skin material 9,
When the core layer 2 is formed of a foamed resin or a low heat conductive material, high heat retention can be obtained by the heat insulation effect of the core layer 2, and when the core layer 2 is formed of a heat storage material. The heat storage effect of the heat storage material makes it possible to obtain high performance of heat retention and cold retention. Further, as described above, the heat-insulating tableware A having a structure in which the skin layers 3 on both outer surfaces and the core layer 2 are sandwiched between the skin layers 3 on both outer surfaces can be produced in one step of the injection molding as described above. It is possible to reduce the production cost by doubling the cost. Furthermore, since the skin layer 3 is formed so as to wrap around the core layer 2, there is no need to perform pasting in a later step, and there is no peeling of the pasted portion, and boiling resistance is improved. It is possible to improve the durability including the resistance to boiling and drying and the like, and to eliminate the problem of the external appearance such as when the bonded joint appears in the external appearance. The heat-insulating tableware A is preferably formed to have a uniform wall thickness, and the wall thickness is preferably set to about 2 to 12 mm.

Here, as the molding die, it is preferable to use one having a gate 8 provided at or near the center of the cavity 5 (for example, the center of the bottom surface of the heat-insulating tableware A). When the gate 8 is provided near the center of the cavity 5 in this way, the skin material 9 and the core material 10 injected into the cavity 5 are filled in the cavity 5 so as to spread from the vicinity of the center of the cavity 5 to the periphery. The core material 10
It becomes easy to fill the inside of the cavity 5 with the skin material 9 and to fill the cavity 5, and the heat-insulating tableware A is formed into a three-layer structure in which the core layer 2 of the core material 10 is wrapped with the skin layer 3 of the skin material 9. It will be easy to do. In this way, the gate 8 is placed near the center of the bottom of the heat-insulating tableware A.
When molding is performed using the molding die 5 provided with, the sprue 22 is formed on the bottom surface of the heat-retaining tableware A, and the gate mark 23 after removing the sprue 22 is the bottom surface of the heat-retaining tableware A which is not visible. Therefore, the heat-insulating tableware A does not impair the appearance. FIG. 2 shows an example in which the gate 8 is provided in a portion surrounded by the thread tail 24 so that the sprue 22 is formed at this portion of the heat-insulating tableware A. 3 (a) and 3 (b) show an example in which gates 8 are provided at three locations in the thread tail 24 so that the sprue 22 is formed at these locations on the heat-insulating tableware A.

[0017]

By performing injection molding of the skin material 9 and the core material 10 using the three-layer injection molding machine 1, the three skin layers 3, 3 on both sides of the core layer 2 and the core layer 2 are formed. The heat-insulating tableware can be obtained, and the heat-insulating tableware can be manufactured without the need for pasting in a later step, and the heat-insulating tableware can be manufactured in one step of injection molding.

[0018]

EXAMPLES The present invention will be further described with reference to examples. (Example 1) Polypropylene resin ("130MX" manufactured by Ube Industries, Ltd.) was used as the skin material 9, and 100 parts by weight of polypropylene resin (same as above) was used as the core material 10 with a foaming agent ("EE206" manufactured by Eiwa Chemical Industry Co., Ltd.). 80t for three-layer molding consisting of 2 cylinders 6a, 6b and 1 nozzle 7 as shown in FIG.
Molding was carried out using a biaxial injection molding machine 1 and a molding die 4 in which a gate 8 is provided in the center of a cavity 5 formed for rice bowl molding having a capacity of 300 cc.

That is, first, as shown in FIG. 1A, the skin material 9 was injected from the cylinder 6a into the cavity 5 of the molding die 4. The injection amount of the skin material 9 at this time was adjusted to be about 48% of the volume of the cavity 5. next,
As shown in FIG. 1B, the core material 10 was injected into the cavity 5 from the cylinder 6b. The injection amount of the core material 10 at this time was adjusted to be about 50% of the volume of the cavity 5. Further subsequently, the skin material 9 was injected into the cavity 5 from the cylinder 6a. The injection amount of the skin material 9 at this time was adjusted to be about 2% of the volume of the cavity 5. After that, by cooling and opening the molding die 4, heat-insulating tableware A used as a rice bowl as shown in FIG. 2 was obtained. This warm tableware A weighs 150 g and has a maximum wall thickness of 9 mm.
The volume ratio of the skin layer 3 and the core layer 2 was 1: 1.

The condition for this molding is that the injection time is 10
Seconds, cooling time 120 seconds, injection pressure 20 kg / cm ² , mold temperature of fixed mold 4a 55 ° C, mold temperature of movable mold 4b 55 ° C, temperature of cylinder 6a 200 ° C, temperature of cylinder 6b 20
It was 0 ° C. (Example 2) 100 parts by weight of polypropylene resin ("130MX" manufactured by Ube Industries, Ltd.) as the skin material 9 and 6 parts of nylon 6 ("1013B" manufactured by Ube Industries Ltd.) as the core material 10 were used as a foaming agent (produced by Eiwa Chemical Industry Co., Ltd.). 6% by weight of EE206 ") was used, and the heat-insulating tableware A was obtained in the same manner as in Example 1 by molding as shown in FIGS. 1 (a) to 1 (c).
The conditions for this molding are: injection time 10 seconds, cooling time 12
0 seconds, injection pressure 20 kg / cm ² , mold temperature 6 of fixed mold 4a
The temperature was 0 ° C., the mold temperature of the movable mold 4b was 60 ° C., the temperature of the cylinder 6a was 200 ° C., and the temperature of the cylinder 6b was 230 ° C.

(Example 3) A polybutylene terephthalate resin (“KL273F” manufactured by Kuraray Co., Ltd.) was used as the skin material 9.
P ”) as the core material 10 in polyethylene terephthalate resin (“ KL236R ”manufactured by Kuraray Co., Ltd.) with an average particle size of 4
As shown in FIG. 1A to FIG. 1C, 25% by weight of a glass balloon of 5 μm and 15% by weight of crushed powder obtained by crushing runners and sprues generated during PET molding were uniformly mixed. The heat-insulating tableware A was obtained by molding as in c). The conditions for this molding are: injection time 12 seconds,
Cooling time 110 seconds, injection pressure 40 kg / cm ² , mold temperature of fixed mold 4a 80 ° C, mold temperature of movable mold 4b 80 ° C, temperature of cylinder 6a 240 ° C, temperature of cylinder 6b 290 ° C
Met.

Example 4 A polypropylene resin (“130MX” manufactured by Ube Industries, Ltd.) was used as the skin material 9 for the core material 1.
1 was used in the same manner as in Example 1 except that polypropylene resin (the same as above) was uniformly mixed with 40% by weight of cork powder having an average particle diameter of 100 μ or less.
The heat-insulating tableware A was obtained by molding as in (a) to (c). The conditions for this molding are: injection time 10 seconds, cooling time 120
Second, injection pressure 22 kg / cm ² , mold temperature 50 of fixed mold 4a
℃, mold temperature of movable mold 4b 50 ℃, temperature of cylinder 6a 2
The temperature was 00 ° C and the temperature of the cylinder 6b was 210 ° C.

(Example 5) Ethylene propylene copolymer resin (EP resin; manufactured by Mitsui Petrochemical Co., Ltd., "Tufmer P08"
80) 20 parts by weight and about 140 parts by weight of high-density polyethylene (HDPE; "BZ50U" manufactured by Mitsubishi Chemical Industry Co., Ltd.)
Liquid paraffin as a heat storage material (“Liquid Paraffin 155” manufactured by Nippon Seiro Co., Ltd .; melting point 69)
(.Degree. C.) 70 parts by weight were added and uniformly mixed, and the mixture was extruded with a uniaxial extruder, cooled with water, drained, and granulated with a pelletizer to prepare a core material 10 containing a heat storage material.

The core material 10 and polypropylene resin as the skin material 9 ("RF116 manufactured by Ube Industries, Ltd."
7 ”), and in the same manner as in Example 1, FIGS.
Molded as in (c), heat-insulating tableware A was obtained. This heat-insulating tableware A has a capacity of 300 cc, a maximum wall thickness of 12 mm, and a skin layer 3
And the volume ratio of the core layer 2 was 3: 2. The molding conditions are: injection time: 10 seconds, cooling time: 150 seconds, injection pressure: 50 kg / cm ² , mold temperature of fixed mold 4a: 40 ° C, mold temperature of movable mold 4b: 40 ° C, temperature of cylinder 6a: 200 ° C.
The temperature of the cylinder 6b was 130 ° C.

(Example 6) Liquid paraffin as a heat storage material ("liquid paraffin 115" manufactured by Nippon Seiro Co., Ltd .; melting point 47)
(C) was used, and a core material 10 containing a heat storage material was prepared in the same manner as in Example 5, and further heat insulating tableware A was obtained in the same manner as in Example 5. (Comparative Example) For comparison, tableware having a single-layer structure was produced only with polypropylene resin ("130MX" manufactured by Ube Industries, Ltd.).

Examples 1 to 6 obtained as described above
And the tableware of the comparative example was tested for heat retention. The heat retention was evaluated by preheating the above tableware with a lid at 80 ° C for 1 hour in advance, and then pouring hot water at 90 ° C into the tableware for 25 hours.
It was carried out by measuring the temperature of the hot water after 1 hour in a ℃ atmosphere. The results are shown in the table below.

[0027]

[Table 1]

[0028]

As described above, the heat-insulating tableware according to the present invention is
It is molded using a three-layer injection molding machine and consists of three layers, the core layer and the skin layers on both sides of the core layer.Therefore, the entire skin layer is formed by molding, and it is necessary to perform bonding in a later step. In addition to being able to obtain heat-resistant tableware with high durability, it is possible to produce heat-resistant tableware with high productivity in one step of injection molding, and it is possible to manufacture heat-resistant tableware at low cost. .

In this heat insulating tableware, the heat insulation of the core layer can be enhanced by forming the core layer from a foamed resin or by mixing the core layer with a low heat conductive material, and the heat insulating container having a good heat retaining property. Is what you can get.
Further, in this heat insulation container, by forming the core layer from a heat storage material, heat retention performance or cold insulation performance can be obtained by heat storage by the heat storage material, and a heat insulation container with good heat retention can be obtained. .

Further, in this heat insulation container, by blending the recycled material of the resin molded product in the core layer, the cost can be reduced by the inexpensive recycled material and the effect of resource saving can be obtained. Is. When manufacturing the above-mentioned heat retaining container, a three-layer injection molding machine consisting of two cylinders and one nozzle is used to first inject a skin material from one cylinder into a cavity of a molding die, and then the other cylinder. By injecting the core material from, then by injecting the skin material from the one of the cylinders, so as to form a three-layer heat-insulating tableware that wraps the core layer of the core material in the skin layer of the skin material, The core material is injected into the cavity so as to immerse into the skin material that has been previously injected into the cavity, and it is possible to perform molding by wrapping the core layer of the core material with the skin layer of the skin material. In addition, it is possible to produce heat-insulating tableware without the need to attach a skin layer in a later step, and heat-insulating tableware in one step of injection molding. Those that can be produced.

Further, as the molding die of the injection molding machine for three-layer molding, the one having the gate provided in the vicinity of the center of the cavity is used. Therefore, the skin material and core material injected into the cavity are It is filled so that it spreads from the vicinity of the center to the periphery, and it becomes easy to fill the core material into the cavity while wrapping it with the skin material. The heat-insulating tableware can be easily formed into a three-layer structure in which the layers are wrapped.

[Brief description of drawings]

FIG. 1 shows an example of molding performed in the present invention, in which (a), (b) and (c) are sectional views, respectively.

FIG. 2 is a cross-sectional view showing an example of the heat-insulating tableware obtained by the same as above.

FIG. 3 shows another example of the heat-insulating tableware obtained by the above, in which (a) is a cross-sectional view and (b) is a bottom view.

FIG. 4 shows a conventional example, (a) is a perspective view,
(B) is a partially cutaway perspective view.

[Explanation of symbols]

 1 injection molding machine for three-layer molding 2 core layer 3 skin layer 4 molding die 5 cavity 6a cylinder 6b cylinder 7 nozzle 8 gate 9 skin material 10 core material

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masanori Matsukawa 1048, Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Works Co., Ltd.

Claims (8)

[Claims] 1. A heat-insulating tableware, which is produced by molding with a three-layer injection molding machine and comprises three layers of a core layer and skin layers on both surfaces of the core layer. 2. The heat-insulating tableware according to claim 1, wherein the core layer is wrapped by a skin layer. 3. The heat-insulating tableware according to claim 1, wherein the core layer is made of foamed resin. 4. The heat-insulating tableware according to claim 1, wherein a low thermal conductive material is mixed in the core layer. 5. The heat-insulating tableware according to claim 1, wherein the core layer is made of a heat storage material. 6. The heat-insulating tableware according to claim 1, wherein the core layer contains a recycled material of a resin molded product. 7. A three-layer injection molding machine comprising two cylinders and one nozzle is used to first inject a skin material from one cylinder into a cavity of a molding die, and then inject a core material from the other cylinder. Then, a method of manufacturing a heat-insulating tableware, which comprises injecting a skin material from the one cylinder to form a heat-insulating tableware having a three-layer structure in which a core layer made of a core material is wrapped with a skin layer made of a skin material. 8. The method for producing heat-insulating tableware according to claim 7, wherein the molding die of the injection molding machine for three-layer molding is provided with a gate near the center of the cavity.