JPH0520300B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] This invention relates to a container for microwave ovens, and more specifically, the present invention relates to a container for microwave ovens. Concerning microwave containers. [Prior art and its problems] Conventionally, containers that require high-temperature liquids close to 100°C, such as instant cup noodle containers, and beverages such as coffee, tea, etc.
Polystyrene foam, as a container for soup etc.
Alternatively, some are manufactured by molding a single material such as polyolefin resin or polystyrene resin. Polystyrene foam, polyolefin resin alone, polystyrene resin alone, etc. can be easily molded and mass production has begun, but they have the following drawbacks. In other words, polystyrene foam containers lack heat-resistant rigidity, so when boiling water is poured into the container, for example, when this container is used as an instant cup noodle container, the container deforms due to the heat and weight of the boiling water. Even if you try to hold a container containing hot water in your hand, the container easily deforms and you cannot hold the container securely in your hand. Additionally, this polystyrene foam container cannot be heated in a microwave oven to cook the contents or thaw frozen foods. This is because it lacks heat resistance and rigidity. Furthermore, when this used polystyrene foam is incinerated, the high calorie burn leads to damage to the incinerator. Therefore, difficult problems arise in the disposal of the waste polystyrene foam. Molded products made of polyolefin resin alone or resin compositions made of polystyrene resin alone and inorganic fillers lack heat retention, so even if they have excellent heat resistance and rigidity, for example, containers made of this resin composition cannot be kept warm. It cannot be used as a container. This means that it is not suitable for containers for instant noodles, which must be filled with boiling water for 5 minutes to promote the softening of the noodles. [Object of the Invention] This invention has been made based on the above circumstances. That is, an object of the present invention is to provide a microwave oven container that has excellent heat resistance and heat retention properties and does not easily deform even when heated in a microwave oven. [Means for achieving the above object] The gist of this invention for achieving the above object is as follows:
15 to 65% by weight of an inorganic filler and a polyolefin resin are applied to the inner and/or outer surface of the polystyrene foam container body, which has a shape capable of accommodating a liquid or solid substance, and is in contact with the liquid or solid substance. , thermoplastic polyester resins, and nylon resins in an amount of 85 to 35% by weight of any thermoplastic resin selected from the group consisting of thermoplastic resins. This is a unique microwave container. More specifically, the container body is made of polystyrene foam and has a shape capable of accommodating liquid or solid materials. The polystyrene foam itself is not particularly limited, but has a density of 0.05 to 0.5 g/cm ² , preferably 0.07 to 0.5 g/cm 2 .
Desirably, it is 0.3 g/cm ² . If the foaming conditions are limited, the foaming ratio should be 20 to 2, preferably 15.
-3 polystyrene foams are preferred. There is no particular restriction on the shape of the container body as long as it can accommodate liquid or solid matter; for example, it may have a deep dish shape 1 as shown in FIG. Examples include a bottomed cylindrical shape 4 whose diameter is slightly larger than the diameter of the bottom surface 3, a sake bottle shape 5 as shown in FIG. 6, and a bowl shape 6 as shown in FIG. The shapes shown in FIGS. 4 to 7 are just examples, and it goes without saying that the shape of the container body is not limited to the shapes shown in these figures. The thickness of the container body varies depending on what kind of liquid is put into the container and in what amount, but for example, a container that can hold 250 to 800 c.c. of instant noodles, retort food, etc. If there is, it is usually 1 to 5 mm, preferably 2 to 4 mm. The specific thermoplastic resin composition is a mixture of a specific thermoplastic resin and an inorganic filler. The specific thermoplastic resin is one selected from the group consisting of polyolefin resin, thermoplastic polyester resin, and nylon resin. As the polyolefin resin, for example,
High density polyethylene, medium and low density polyethylene,
Polyethylene such as linear low-density polyethylene,
Examples include polypropylene such as isotactic polypropylene, syndiotactic polypropylene, and atactic polypropylene, polybutene, and 4-methylpentene-1 resin. Polymer, ethylene-
Copolymers with olefins such as vinyl chloride copolymers and propylene-vinyl chloride copolymers can also be used. Examples of nylon resin include nylon-
6, Nylon-8, Nylon-11, Nylon-
66, nylon-610, etc. Examples of the thermoplastic polyester resin include polyethylene terephthalate and polypropylene terephthalate. Since the thermoplastic resin composition in this invention is subjected to molding, the specific thermoplastic resin may be selected from the various thermoplastic resins as long as it has a moldable molecular weight. can be used. The above various thermoplastic resins may be used alone, or two or more types may be mixed and used as a polymer blend. However, among the various thermoplastic resins mentioned above, preferred ones are:
These include high density polyethylene, low density polyethylene, linear low density polyethylene, polypropylene, polyethylene terephthalate, nylon-66 and nylon-6. Examples of the inorganic filler include carbonates such as calcium carbonate, magnesium carbonate, and dolomite, sulfates such as barium sulfate, calcium sulfate, and magnesium sulfate, sulfites such as calcium zincate, talc, clay, mica, asbestos, Silicates such as glass fiber, glass beads, calcium silicate, montmorillonite, bentonite,
Examples include metal powders such as iron, zinc, and aluminum, ceramics such as silicon carbide and silicon nitride, and their whiskers, carbon black, graphite, and carbon fibers, and these inorganic fillers may be used alone or in combination of two or more. The above inorganic fillers can be used in combination. Among the various inorganic fillers, carbonates, sulfates, silicates, etc. are preferred, and calcium carbonate, barium sulfate, talc, clay, mica, etc. are particularly preferred. The inorganic filler may be in the form of particles, plates, or fibers, but the particle size is 0.2 to 20μ.
It is desirable that it be within the range of m. Even if the particle size of this inorganic filler is smaller than 0.2 μm, the effect will be small depending on its formulation, and if the particle size is larger than 20 μm, it will not be possible to disperse it in the thermoplastic resin composition or after processing it into a sheet or film. The glossiness, smoothness, and smoothness after secondary processing all deteriorate. One of the important things about this invention is that this thermoplastic resin composition contains 85 to 35% by weight of a specific thermoplastic resin.
and 15 to 65% by weight of the inorganic filler. If the amount of the specific thermoplastic resin exceeds 85% by weight, the heat retaining properties will be reduced and the container will be thermally deformed when heated in a microwave oven, making it impossible to achieve the object of the present invention. In addition, if the amount of a specific thermoplastic resin is less than 35% by weight, the heat retention properties will decrease, and if the microwave container is not heated in the microwave or if a liquid substance is placed inside the container. If the container is heated in a microwave oven, the microwave container will undergo significant thermal deformation, making it unsuitable for practical use. In addition to the above-mentioned specific thermoplastic resin and inorganic filler, the thermoplastic resin composition in this invention also contains, as long as it does not impede the object of the invention,
If this microwave container is to be used as a food container, antistatic agents, colorants, flame retardants, and antioxidants should be added as necessary, as long as they do not elute into high-temperature liquids and adversely affect the human body. , various additives such as plasticizers can be added and blended. Various surfactants can be used as the antistatic agent. Further, examples of the coloring agent include poorly soluble azo dyes, red coloring agents, cadmium yellow, cream yellow, titanium white, and the like. Examples of the flame retardant include inorganic antimony oxide, silcone oxide, etc., and organic phosphoric acid ester, tricresyl phosphate, etc. As the antioxidant, triazole-based, salicylic acid-based, and acrylonitrile-based antioxidants are used. Further, examples of the plasticizer include phthalic acid diester, butanol diester, phosphoric acid diester, and the like. Among the various additives, if the microwave container is used as a food container, it is best to select an appropriate additive by paying attention to the descriptions in the Japanese Pharmacopoeia. The blending amount of the additive is based on a total of 100 parts by weight of the specific thermoplastic resin and inorganic filler.
Usually 0.01 to 10 parts by weight, preferably 0.1 to 10 parts by weight
It is 5 parts by weight. The thermoplastic resin composition in the present invention can be produced by blending the specific thermoplastic resin, the inorganic filler, and, if necessary, the various additives described above. The blending method is not particularly limited, and may be carried out using a ribbon blender, tumble mixer, Henschel mixer, open mixer, Banbury mixer, single-screw extruder, twin-screw extruder, single-screw reciprocating screw kneader, etc. be able to. What is important in this invention is that in this microwave oven container, a sheet or film-like material of the thermoplastic resin composition is laminated on the container body made of polystyrene foam. As an embodiment of lamination, for example, as shown in FIGS. 1 to 3, a sheet-like material or a film-like material 8 may be laminated on the inner surface of the container body 7 that is in contact with the liquid or solid material, A sheet-like material or a film-like material 8 may be laminated on the outer surface of the container body 7, and a sheet-like material or a film-like material 8 may be laminated on the inner and outer surfaces of the container body 7 that are in contact with the liquid or solid material. Item 8 may be stacked. Which lamination state is better depends on what purpose the microwave oven container will be used for. The thickness of the sheet-like or film-like material of the thermoplastic resin composition to be laminated is usually 20 to 2000 μm,
Preferably, it is 30 to 500 μm. If this thickness is thinner than 20 μm, heat resistance and rigidity may be lacking, and if it is thicker than 2000 μm, there is not much merit from increasing the thickness. Further, the lamination can be performed by heat-sealing a sheet-like material or a film-like material to the container body, or by bonding with an adhesive. This microwave oven container formed as described above is suitably used as a food container for thawing frozen foods in a microwave, in particular, as a food container for storing semi-cooked foods. For example, a deep dish-shaped microwave oven container as shown in Figure 4 can be used to store semi-cooked curry, stew, hamburger steak, raw noodles, etc., and then seal the opening and use it as a retort food container. can. Further, a microwave container shaped as shown in FIGS. 5 and 7 can store raw noodles, instant noodles, rice, etc., and can be used as a retort food container by sealing the opening. This microwave container having the shape shown in Fig. 6 is
For example, it can be used to store alcoholic beverages and seal the opening, for example, as a one-cup sake container for a vending machine. Whichever microwave oven container you use, you can heat frozen foods, etc. together with the microwave oven container, for example, in a microwave oven.
Even when heated, the microwave oven container does not easily become deformed and cannot be held in the hand, and the food in the heated microwave oven container does not easily cool down. [Effects of the Invention] According to the present invention, (1) Since the container body is laminated with a sheet-like or film-like material of a thermoplastic resin composition, it does not easily deform even when heated in a microwave oven. Therefore, it can be heated in a microwave oven with the contents still in it, and because it has high heat resistance and rigidity, the microwave container will not be easily deformed even when heated. Since it is a container itself, it has great heat retention properties, can prevent the heated contents from cooling down quickly, and can be held in the hand even if the contents are heated to high temperatures. It is possible to provide a microwave container having excellent properties. [Examples] Next, the present invention will be explained in more detail by showing examples and comparative examples of the present invention. It goes without saying that this invention is not to be interpreted as being limited to the following examples. Moreover, below, a microwave oven container may be simply abbreviated as a container. Examples 1 to 18, Comparative Examples 1 to 4 A 60 μm thick film of a thermoplastic resin composition containing a thermoplastic resin and an inorganic filler of the type and proportion shown in Table 1 was placed in a bowl shown in FIG. Made of polystyrene foam (density: 0.105g/
cm ³ , expansion ratio: 10 times)) and a container body (opening diameter: 140 mm, height: 70 mm, thickness: 2.5 mm) was laminated on the inner surface. For Comparative Example 3, a bowl-shaped container (diameter and height dimensions are the same as above) was made from polystyrene foam, and for Comparative Example 4, 40% by weight of talc as an inorganic filler and thermoplastic A container with a thickness of 0.3 mm (diameter and height dimensions are the same as above) was prepared using only a thermoplastic resin composition containing 60% by weight of polyethylene as a resin. Each of the obtained containers was subjected to the following tests to evaluate its performance. {Dry cooking test (indicated as "Dry cooking" in Table 2)} Place the container without contents in a microwave oven [manufactured by Sharp Co., Ltd., R-528, rated voltage 100 V, high frequency output 500 W]. After heating for 20 minutes, check the surface condition of the inside of the container.
The state of discoloration and deformation were visually evaluated. The evaluation criteria are shown as notes next to Table 2. The results are shown in Table 2. {Heating test with contents (in Table 2,
(Displayed as "instant ramen")} Heat a container containing instant ramen and water for 20 minutes in a microwave [manufactured by Sharp Co., Ltd., R-528, rated voltage 100V, high frequency output 500W] for 20 minutes to bring the water to a boil. Thereafter, the surface condition, discoloration, and deformation of the inside of the container were visually evaluated. The evaluation criteria are shown as notes next to Table 2. The results are shown in Table 2.

【table】

【table】

【table】

[Table] In addition, in the container obtained in Example 1, add 20 g of olive oil.
ml and heated it in the microwave for 30 minutes, but there was no abnormality in the surface condition or color inside the container, and
After heating, the container was not deformed. On the other hand, put 20 ml of olive oil in the polystyrene foam container obtained in Comparative Example 3 and heat it in the microwave for 30 minutes.
After heating for a minute, the inner surface of the container had blisters and peeling, and the inner surface had turned slightly yellow, and furthermore, the container had softened and deformed after heating. Furthermore, olive oil was added to the container obtained in Example 1.
I added 20ml of water to the container and heated it in the microwave for 10 minutes until it reached the opening of the container, but there was no abnormality in the inner surface condition or color of the container. It wasn't deformed. On the other hand, when olive oil and water were similarly placed in the polystyrene foam container obtained in Comparative Example 3 and heated in the microwave for 10 minutes, blisters and peeling occurred on the inner surface of the container. The inner surface was slightly yellowed, and the container was softened and deformed after heating.

[Brief explanation of the drawing]

1 to 3 are longitudinal sectional views showing a container according to an embodiment of the present invention, and FIGS. 4 to 7 are front views showing various shapes of the container body. 1... deep dish shape, 4... bottomed cylinder shape, 5... sake bottle shape, 6... bowl shape, 7... container body, 8... sheet-like object or film-like object.

Claims (1)

[Scope of Claims] 1. On the inner and/or outer surface of a polystyrene foam container body having a shape capable of accommodating liquid or solid matter, which is in contact with the liquid,
A sheet of a thermoplastic resin composition comprising 15 to 65% by weight of an inorganic filler and 85 to 35% by weight of any thermoplastic resin selected from the group consisting of polyolefin resin, thermoplastic polyester resin, and nylon resin. A microwave oven container characterized by being made of a layered material or film-like material. 2 The thermoplastic resin is high density polyethylene,
The microwave oven container according to claim 1, which is any one selected from the group consisting of low density polyethylene, linear low density polyethylene, polypropylene, polyethylene terephthalate, nylon-66, and nylon-6. 3 The inorganic filler is talc, calcium carbonate,
The microwave oven container according to claim 1 or 2, which is any one selected from the group consisting of clay, mica, and barium sulfate. 4. The microwave oven container according to any one of claims 1 to 3, wherein the shape of the container body is any one of a deep dish shape, a bottomed cylindrical shape, a bowl shape, and a sake bottle shape. .