JPS6013634Y2 - High barrier polypropylene resin laminated sheet - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a polypropylene resin laminate sheet that has excellent barrier properties and moldability and is deep drawable.

Traditionally, polypropylene sheets have been used to heat them and form them using thermoforming methods such as vacuum acid forming or pressure forming to produce molded products such as containers. The sheets used for this purpose are unstretched polypropylene sheets or biaxially oriented polypropylene sheets, and both of these sheets are permeable to gases such as oxygen and have poor barrier properties, so these sheets are used to form containers and use them as food containers. However, there was a drawback that the food did not have long shelf life.

Furthermore, when an unstretched polypropylene sheet that has not been subjected to stretching treatment is used as a molding sheet, the sheet sag when heated (this is called a drawdown phenomenon), causing wrinkles in the molded product, making molding difficult. Met.

In addition, when a biaxially oriented polypropylene sheet stretched in two directions, vertical and horizontal, is used as a molding sheet,
Although the drawdown phenomenon can be prevented, deep drawing is difficult due to the large heat shrinkage force, making it unsuitable for manufacturing containers with deep bottoms.

The present invention solves the above-mentioned conventional drawbacks, and aims to provide a high-barrier polypropylene resin laminated sheet that has excellent barrier properties, does not sag during heating, can be deep drawn, and has excellent moldability. This is the purpose.

That is, the gist of the present invention is a high-barrier polypropylene resin laminate sheet characterized by being formed by integrally laminating a biaxially oriented polypropylene resin sheet layer, an unoriented polypropylene resin sheet layer, and a single barrier layer. .

Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 shows a first embodiment of the present invention, in which 1 is a laminated sheet of the present invention, and this laminated sheet 1 has a barrier layer 4 attached to a biaxially oriented polypropylene resin sheet layer 2 via an adhesive 3.
are laminated, and an unstretched polypropylene resin sheet layer 5 is further laminated on the barrier layer 4 via an adhesive 3.

The biaxially oriented polypropylene resin sheet layer 2 is obtained by melt-extruding a sheet in an extruder and stretching it in two directions, vertical and horizontal, and has the property of shrinking in the two directions when heated. have.

The stretching process may be performed in both longitudinal and lateral directions at the same time,
Alternatively, so-called two-stage stretching may be performed, in which the film is first stretched, for example, in the longitudinal direction and then in the transverse direction.

The unstretched polypropylene resin sheet layer 5 was also a biaxially stretched polypropylene resin sheet layer.

The present invention solves the above-mentioned conventional drawbacks, and aims to provide a high-barrier polypropylene resin laminated sheet that has excellent barrier properties, does not sag during heating, can be deep drawn, and has excellent moldability. This is the purpose.

That is, the gist of the present invention is a high barrier polypropylene resin laminate sheet characterized by being formed by laminating and integrating a biaxially oriented polypropylene resin sheet layer, an unoriented polypropylene resin sheet layer, and a single barrier layer. .

Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 shows a first embodiment of the present invention, in which 1 is a laminated sheet of the present invention, and this laminated sheet 1 has a barrier layer 4 attached to a biaxially oriented polypropylene resin sheet layer 2 via an adhesive 3.
are laminated, and an unstretched polypropylene resin sheet layer 5 is further laminated on the barrier layer 4 via an adhesive 3.

The biaxially oriented polypropylene resin sheet layer 2 is obtained by melt-extruding a sheet into a sheet shape using an extruder and stretching it in two directions, the vertical direction and the horizontal direction, and has the property of shrinking in the two directions when heated. have.

The stretching process may be performed in both longitudinal and lateral directions at the same time,
Alternatively, so-called two-stage stretching may be performed, in which the film is first stretched, for example, in the longitudinal direction and then in the transverse direction.

Like the biaxially oriented polypropylene resin sheet layer 2, the unstretched polypropylene resin sheet layer 5 is manufactured by melt-extruding it into a sheet shape using an extruder, and is not subjected to stretching treatment. The unstretched polypropylene resin sheet layer 5 referred to herein also includes a material that causes the drawdown phenomenon even if it is drawn.

The barrier layer 4 is of such a nature that it can prevent the permeation of gases such as oxygen.

As the material for the biaxially oriented polypropylene resin sheet layer 2 and the non-oriented polypropylene resin sheet layer 5, polypropylene and a copolymer of propylene and other monomers can be used.

As the material for the barrier layer 4, a saponified product of ethylene-vinyl acetate copolymer can be used.

For example, modified polypropylene can be used as the adhesive.

Modified polypropylene refers to polypropylene modified by graft copolymerization of an unsaturated dicarboxylic acid or its anhydride.

The adhesive is used here because the adhesiveness between the barrier layer and the polypropylene layer is poor.

Each of the sheets 2, 4. The thickness of the sheet layer 2 can be selected arbitrarily, but for example, the thickness of the sheet layer 2 is 0.00'7 to 0.
．． 025mm, the thickness of the sheet layer 4 is 0.005~
0.05mm, the thickness of the sheet layer 5 is 0.05~
1.5rIrIIL is suitable.

The present invention is not limited to the three-layer structure as described above, but can also be a multi-layer structure of four or more layers.

For example, FIG. 2 shows a second embodiment of the present invention, in which a non-stretched sheet layer 5 is laminated on a biaxially stretched sheet layer 2, a barrier layer 4 is laminated thereon via an adhesive 3, and an adhesive 3 is further laminated thereon. It is formed by laminating non-stretched sheet layers 5 via.

FIG. 3 shows a third embodiment of the present invention, in which a barrier layer 4 is laminated on a biaxially stretched sheet layer 2 with an adhesive 3 interposed therebetween, and a non-stretched sheet layer 5 is laminated thereon with an adhesive 3 interposed therebetween. Furthermore, a two-wheel stretched sheet layer 2 is laminated.

Although the biaxially stretched sheet layer 2 is provided only on one side of the laminated sheet 1 in the first and second examples, it may be provided on both sides of the laminated sheet 1 as in the third example.

Although not shown, a structure may be adopted in which a single barrier layer is laminated on the non-stretched sheet layer via an adhesive, and a non-stretched sheet layer is laminated thereon to provide the non-stretched sheet layers on both the upper and lower surfaces.

However, providing a biaxially stretched sheet layer is superior to providing a non-stretched sheet layer on both the upper and lower surfaces in terms of moldability.

Furthermore, although not shown, a barrier layer may be provided as the outermost layer.

The laminated sheet 1 of the present invention is used for molding containers and the like.

FIG. 4 shows an example in which a container or the like is formed using the laminated sheet 1 in the first embodiment. Since the laminated sheet 1 has a barrier layer 4 that does not permeate gases such as oxygen, for example, When a food container 6 is manufactured using this laminated sheet 1, the container 6 blocks the permeation of gases such as oxygen and becomes extremely suitable for food preservation.

Further, in this molding, for example, a thermoforming method such as vacuum acid forming or pressure forming is employed.

When a container is manufactured using the laminated sheet of the present invention by this thermoforming method, the sheet does not sag during heating, so the molded product does not wrinkle, and can be deep drawn.

The reason why the sheet does not sag during heating is considered to be that the drawdown phenomenon of the unoriented polypropylene resin sheet layer 5 is appropriately offset by the heat shrinkage effect of the biaxially oriented polypropylene resin sheet layer 2.

Further, it is considered that the reason why deep drawing is possible is that the heat shrinkage force of the sheet 2 is moderately relaxed by the drawdown phenomenon of the sheet 5.

As explained above, according to the laminated sheet of the present invention, the permeation of gases such as oxygen can be prevented by providing a single barrier layer, so that, for example, when a food container is manufactured using the laminated sheet of the present invention, the container This makes it extremely suitable for food preservation.

Further, the following effects are exhibited by the interaction between the biaxially oriented polypropylene resin sheet and the unoriented polypropylene resin sheet.

That is, when the laminated sheet of the present invention is used for forming containers, etc.,
The sheet does not sag during heating and can be formed evenly.
A molded product with a good appearance and no wrinkles can be obtained.
Furthermore, it can be deep drawn and has extremely excellent formability.

In addition, the laminated sheet of this invention has heat resistance, cold resistance, impact resistance,
It also has excellent properties in terms of transparency, gloss, printing properties, etc.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a vertical sectional view showing the first embodiment of the present invention, and FIG.
FIG. 3 is a vertical cross-sectional view showing a third embodiment of the present invention, and FIG. 4 is a vertical cross-sectional view of a container molded using the laminated sheet in the first embodiment. 1... High barrier polypropylene resin laminate sheet, 2... Biaxially oriented polypropylene resin sheet layer, 4... Barrier single layer, propylene resin sheet layer. 5...Unstretched poly

Claims (1)

[Scope of utility model registration request] A high-barrier polypropylene resin laminate sheet characterized by being formed by laminating and integrating a biaxially oriented polypropylene resin sheet layer, an unoriented polypropylene resin sheet layer, and a barrier layer.