JP2001341256A - Synthetic resin sheet material for molding container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a synthetic resin sheet material for molding having excellent impact resistance, heat resistance and moldability suitable for a packaging container of food or the like. SOLUTION: The synthetic resin sheet material for molding comprises a coating layer 2 made of a polyolefin terephthalate resin or a copolyester resin covering one side surface or both side surfaces of an intermediate layer 1 made of a mixture of a polyolefin terephthalate resin and a cyclic olefin polymer obtained by copolymerizing an ethylene and a cyclic olefin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a synthetic resin sheet material used as a material for packaging tools such as side dishes and accessories, and more particularly to a synthetic resin sheet material excellent in heat resistance, large in mechanical strength, and sanitary and inexpensive.

[0002]

2. Description of the Related Art Packaging tools for such applications are manufactured by blow molding a synthetic resin sheet, and the material is polyethylene terephthalate resin (hereinafter abbreviated as PET) from the standpoint of price, environmental hygiene and recycling. It is heavily used.

[0003]

The above-mentioned PET is excellent in electrical properties and chemical resistance, but does not have sufficient impact strength and heat resistance required for packaging, and thus cracks or scratches due to insufficient impact strength. There is a drawback that it is easy to stick and loses its appearance and sometimes loses its function as a wrapper, and it is easy to be deformed due to low heat resistance, for example, exposure to high-temperature hot water or microwave heating. . It has been proposed to use a reinforced plastic filled with glass fiber in order to solve this drawback, but it cannot be used depending on the application because the transparency is poor, and it is said that there is a difficulty in recycling. It had problems to be solved.

Accordingly, the present inventor has proposed a property which is excellent in impact strength, heat resistance and moldability by using a combination of a polyolefin terephthalate resin such as PET as a main component and a copolymer having a high glass transition temperature including polyethylene. It is an object of the present invention to develop a synthetic resin sheet suitable for a packaging tool having the above, and to provide a synthetic resin sheet material for molding suitable for a packaging container for a product as described above.

[0005]

Means for Solving the Problems The synthetic resin sheet material for container molding of the present invention for achieving the above object will be described with reference to the same reference numerals as in the drawings of the embodiments. One or both surfaces of an intermediate layer 1 made of a mixture of a cycloolefin polymer obtained by copolymerizing ethylene and a cyclic olefin are covered with a coating layer 2 made of polyethylene terephthalate or a copolyester resin.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In carrying out the present invention,
The material of the intermediate layer 1 is generally composed of a polyolefin terephthalate resin such as PET or polybutylene terephthalate (hereinafter abbreviated as PBT) and a cycloolefin polymer.
It is composed of a mixed resin in which a cycloolefin polymer is mixed at a compounding ratio of 3 to 50%, and has a thickness of about 0.1 mm to 0.6 mm for container molding, depending on the use of the packaging tool. When the main raw material is PET, a recycled raw material may be used to reduce material costs. The cycloolefin polymer mixed for the purpose of improving the heat resistance of the raw material is a copolymer of ethylene and a cyclic olefin, and pentacyclopentadecenes or norbornenes are suitable as the cyclic olefin. Since the cycloolefin polymer has a high glass transition temperature of 140 ° C. and is completely hydrogenated, it has high transparency and heat stability, has a small water absorption, does not undergo moisture absorption deformation, and has a low dielectric loss tangent value. Furthermore, it is a raw material meeting the object of the present invention because of its low specific gravity and excellent chemical resistance. Also, since it contains ethylene, it is also advantageous that it has good mixing properties with a polyolefin terephthalate resin such as PET or PBT which is a main raw material.

[0007] The coating layer 2 is made of P from the viewpoint of the appearance of the surface in contact with the article to be packaged, the moldability as a container, and the sanitary viewpoint.
Use non-recycled raw materials that are not recycled, such as ET or copolyester resin. When the coating layer 2 is applied only to one surface of the intermediate layer 1, it goes without saying that care must be taken during production so that the inside of the container is coated. Both of these resins have high transparency, low haze, and excellent gloss. The glass transition temperature of PET is 69 ° C., and the glass transition temperature of the copolyester resin is 81 ° C., which is lower than that of the intermediate layer 1. However, when blow molding or vacuum molding is performed, the moldability of the intermediate layer 1 is hindered. Without lowering the productivity, and since it is more flexible, it has the effect of preventing the middle layer 1 from cracking or cracking. Suitably, the thickness of these coating layers 2 is between 15 and 20 microns. As a means for coating these resins on the surface of the intermediate layer 1 to a predetermined thickness, a thin film of PET or copolyester resin having a predetermined thickness may be thermocompression-bonded.
By extruding the upper and lower surfaces simultaneously with the extrusion, it is possible to increase the production efficiency.

The above-mentioned synthetic resin sheet material for container molding according to the present invention is used as a material of the intermediate layer 1 as a main component.
Since it is a mixed resin of a polyolefin terephthalate such as T and a cycloolefin polymer having a high glass transition temperature, it has a higher softening temperature than conventional polyolefin terephthalate simple resin and has excellent heat resistance as a packaging container. Incidentally, the softening temperature is increased by mixing the cycloolefin polymer, the rise in the softening temperature is within the range of the molding temperature commonly used in conventional blow molding and vacuum molding,
It does not impair moldability and container productivity. or,
Since the cycloolefin polymer is completely hydrogenated, it has high transparency and thermal stability, low water absorption, no deformation due to moisture absorption, and excellent chemical resistance. In addition, since the dielectric loss tangent value is low, heat generation is small even by, for example, heating in a microwave oven, and there is no thermal deformation. If recycled PET is used as the main raw material, polyolefin terephthalate, through resource recycling, it is possible to reduce material costs and to use PET.
The main feature is that it is recyclable and has environmentally beneficial properties.

The coating layer 2 made of PET or copolyester resin, which is a new raw material which is not a recycled raw material by recycling, does not impair moldability and prevents the intermediate layer 1 from cracking or cracking due to its flexibility. In addition, it has the effect of completely maintaining the appearance and sanitary condition of the surface in contact with the article to be packaged.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is an enlarged perspective view showing a cross section of a first embodiment of the present invention, FIG. 2 is an enlarged perspective view showing a cross section of the first embodiment, and FIG. 3 is an application example of a synthetic resin sheet material for container molding of the first embodiment. It is a perspective view of the lunch container of an open state shown as (1).

A first embodiment of the present invention shown in FIG. 1 is a synthetic resin sheet having a composite layer structure in which both surfaces of an intermediate layer 1 are coated with a coating layer 2 and mainly developed for blow molding and vacuum molding. Material. The middle layer 1 is composed of 90% PET and 10% cycloolefin polymer.
Of mixed resin. A cycloolefin polymer is a copolymer of ethylene and a cyclic olefin in which dicyclopentadiene is a starting material, a norbornene derivative is formed into a polymer by metathesis ring-opening polymerization, and the double bond of the polymer is completely eliminated by hydrogenation. . The coating layer 2 uses a copolyester resin containing cyclohexanedimethanol, ethylene glycol and terephthalic acid as raw materials. The thickness of the intermediate layer 1 is 0.2 mm, and the thickness of the coating layer 2 is 15 microns. The synthetic resin sheet material of this embodiment has heat resistance that can be used up to 120 ° C. Therefore, it is not deformed by hot water or microwave heating.

The second embodiment shown in FIG.
The raw materials of the coating layer 2 are the same as those of the first embodiment, but the coating layer 2 is formed on only one surface of the intermediate layer 1. The synthetic resin sheet material of such an embodiment is used such that the coating layer 2 is located inside the container.

The third embodiment is similar to the PET of the first embodiment.
Is replaced by PBT. It has a feature that the mechanical strength and the heat resistance are superior to those of the first embodiment. Since the layered structure is the same as that of the first embodiment, the illustration is omitted. still,
In each of the first to third embodiments, there is a modification in which the material of the coating layer 2 is PET.

FIG. 3 shows, as a reference example, a lunch container molded using the synthetic resin sheet material of the first embodiment. A lunch container having a well-known structure, in which a container body 3 and a partition 4 are integrally blow-molded and vacuum-molded, and are made of the same material by accommodating rice and side dishes in recesses of the arranged partitions 4. The covered body is placed on the container body 3 for packaging.

Although the embodiments which are considered to be representative of the present invention have been described above, the present invention is not necessarily limited to only the structures of these embodiments, but includes the structural requirements according to the present invention and refers to the present invention. The present invention can be implemented by appropriately modifying it within the range of achieving the object and having the following effects.

[0016]

As is clear from the above description, the present invention relates to a synthetic resin sheet material for molding a container, wherein the main material of the intermediate layer 1 is polyolefin terephthalate and cycloolefin having a high glass transition temperature. Since it is a mixed resin with a polymer, it has a higher softening temperature than a conventional polyolefin terephthalate simple resin and has excellent heat resistance as a packaging container. Since the increased softening temperature is within the range of the molding temperature commonly used in conventional blow molding and vacuum molding, the moldability is not impaired and the productivity does not decrease.
In addition, since the cycloolefin polymer is completely hydrogenated, it has high transparency and thermal stability, does not absorb moisture, is excellent in chemical resistance, and has a low dielectric loss tangent, so that it can be heated even in a microwave oven. No deformation occurs. In addition, if recycled PET is used as the main raw material, polyolefin terephthalate, through resource recycling, it is possible to reduce material costs in addition to the above effects, and because PET is mainly used, recycling is possible. It possesses environmentally beneficial attributes. In addition, since the coating layer 2 is made of non-recycled raw material PET or copolyester resin which is not a recycled material, the flexibility of the intermediate layer 1 is prevented from cracking or cracking without impairing the moldability, and the packaging This has the effect of maintaining the appearance and hygiene of the surface in contact with the article in a perfectly good state.

[Brief description of the drawings]

FIG. 1 is an enlarged perspective view showing a structural cross section of a first embodiment.

FIG. 2 is an enlarged perspective view showing a structural cross section of a second embodiment.

FIG. 3 is a reference perspective view showing an application example of a synthetic resin sheet material for container molding.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Intermediate layer 2 Coating layer 3 Container body

Continued on the front page F-term (reference) 3E033 AA10 BA17 BA18 BB08 CA03 CA07 DA08 DD01 DE12 EA10 FA03 FA04 4F100 AK02A AK04A AK41A AK42A AK42B AK42C AK62A AL01A AL01B AL01C AL05A BA02 BA03 E10B06 E06B46 E05B10 CF06W CF07W GG01

Claims (9)

[Claims] 1. A polyolefin terephthalate resin,
Synthesis for container molding in which one or both surfaces of an intermediate layer (1) composed of a mixture of a cycloolefin polymer obtained by copolymerizing ethylene and a cyclic olefin are covered with a coating layer (2) composed of polyethylene terephthalate or copolyester resin Resin sheet material. 2. The coating layer (2) having a thickness of 15 to
The synthetic resin sheet material for molding a container according to claim 1, which has a thickness of 20 microns. 3. The compounding ratio of the polyolefin terephthalate and the cycloolefin polymer forming the intermediate layer (1) is such that the polyolefin terephthalate is 50 to 97.
2. The synthetic resin sheet material for container molding according to claim 1, wherein the content of the cycloolefin polymer is 3 to 50%. 4. The synthetic resin sheet material for molding a container according to claim 1, wherein said polyolefin terephthalate is polyethylene terephthalate. 5. The synthetic resin sheet material for molding a container according to claim 1, wherein the polyolefin terephthalate is polybutylene terephthalate. 6. The synthetic resin sheet material for container molding according to claim 1, wherein said cycloolefin polymer is a copolymer of ethylene and pentacyclopentadecene. 7. The synthetic resin sheet material for molding a container according to claim 1, wherein the cycloolefin polymer is a copolymer of ethylene and norbornenes. 8. The synthetic resin sheet material for container molding according to claim 1, wherein said coating layer (2) is a polyethylene terephthalate resin as a non-recycled raw material. 9. The synthetic resin sheet material for container molding according to claim 1, wherein said coating layer (2) is a copolyester resin.