JPH04314542A - Production of packaging material - Google Patents

Abstract

PURPOSE:To efficiently produce a packaging material having an improved layer-to-layer adhesive strength and pressure resistance without causing the lowering of transparency, the increasing of manufacturing costs and the reduction of workability. CONSTITUTION:A jet of an ozone-containing gas is directed toward the resin extruded in a molten state at least from a T-die 15 in the form of a thin film to form a second resin layer and/or the surface of a first resin layer 4 laminated on an anchor coat layer 3 provided on a supporting base material 2 to accelerate air oxidation of the surface laminated with at least the first resin layer 4 of the second resin layer forming resin, whereby the packaging material having an improved layer-to-layer adhesive strength and pressure resistance is efficiently produced without causing the lowering of transparency, the increasing of the manufacturing costs and the reduction of workability.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a method for manufacturing packaging materials.
In particular, production of packaging materials that can efficiently obtain packaging materials with improved interlayer adhesion strength and improved pressure resistance without reducing transparency, increasing production costs, or reducing processing suitability. Regarding the method.

0002

[Prior Art] Conventionally, for example, a packaging material for transparent liquids has a structure in which a first resin layer and a second resin layer are provided in this order from the support base material side with an anchor coating agent layer interposed on the support base material. packaging materials are known. Polyolefin resins are widely used for both the first resin layer and the second resin layer in this packaging material. Specifically, examples of the polyolefin resin forming the first resin layer include low density polyethylene resin (LDPE);
Examples of the resin forming the resin layer include low-density polyethylene resin (including those containing antistatic agents, lubricants, antifogging agents, etc.), ionomer resins, and ethylene-polyethylene resins.
Examples include thermoplastic resins such as methacrylic acid copolymer resin (EMMA), ethylene-acrylic acid copolymer resin (EAA resin), ethylene-vinyl acetate copolymer resin (EVA), and linear low-density polyethylene resin (LLDPE). .

0003

[Problems to be Solved by the Invention] However, in the conventional packaging material having the above structure, the adhesive strength between the polyolefin layer forming the first resin layer and the polyolefin layer forming the second resin layer is weak. However, this has been a practical problem in the field of packaging liquid soups and the like. by the way,
Such packaging materials, especially packaging materials for liquids, are required to have high pressure resistance and heat sealing strength, so when extrusion laminating the first resin layer and the second resin layer, It is necessary to increase the affinity between the resin layer and the second resin layer, or to increase the oxidation adhesive strength of the second resin layer.

Specifically, as a means of increasing the affinity between the first resin layer and the second resin layer, it is possible to improve the compatibility between the resin forming the first resin layer and the resin forming the second resin layer. adding a third component with a high Possible methods include adding a portion of the resin that forms the .

[0005] Further, as means for increasing the oxidation adhesion of the second resin layer, there are methods such as increasing the processing temperature of the second resin forming the second resin layer to increase air oxidation, or slowing down the processing speed. Alternatively, a method of increasing air oxidation by widening the die gap may be considered. however,
When adding a highly compatible third component to the resin forming the first resin layer and the resin forming the second resin layer in order to increase the affinity between the first resin layer and the second resin layer, and adding a part of the resin forming the second resin layer to the resin forming the first resin layer, or forming the first resin layer on the second resin forming the second resin layer. When a portion of the first resin is added, new problems arise such as a decrease in transparency and an increase in manufacturing cost.

On the other hand, if the processing temperature of the second resin forming the second resin layer is increased to increase air oxidation in order to increase the oxidation adhesion of the second resin layer, the heat sealing surface will also be oxidized.
Problems arise in that the heat seal strength and hot tack strength decrease and the resin deteriorates. Furthermore, if air oxidation is increased by slowing down the processing speed or widening the die gap, problems arise in that processing suitability, heat seal strength, and hot tack strength decrease.

[0007] Therefore, a packaging material with improved interlayer adhesion strength, pressure resistance strength, and heat sealing strength can be produced without causing a decrease in transparency, an increase in manufacturing costs, a decrease in hot tack strength, a decrease in processability, etc. There is a need for a method for manufacturing packaging materials that can be efficiently obtained. The present invention has been made based on the above circumstances, and an object of the present invention is to provide a packaging material with improved interlayer adhesive strength and excellent pressure resistance and heat sealing strength, while reducing transparency and manufacturing costs. It is an object of the present invention to provide a method for producing a packaging material that can be efficiently obtained without causing increase in the amount of water and a decrease in processing suitability.

[0008]

[Means for Solving the Problems] The gist of the present invention for achieving the above object is to melt the anchor coating agent layer from a T-die to form a thin film on the anchor coating agent layer of the supporting base material provided with the anchor coating agent layer. After laminating the extruded first resin layer-forming resin to form a first resin layer, ozone-containing gas is injected from a T-die onto the second resin layer-forming resin that has been melted and extruded into a thin film. , a method for manufacturing a packaging material, characterized in that the first resin layer is laminated so that the ozone-containing gas sprayed surface of the second resin layer-forming resin in a molten state is in contact with the first resin layer, and the anchor coating agent layer After forming a first resin layer by laminating the first resin layer-forming resin melted and extruded into a thin film from a T-die on the anchor coating agent layer of the supporting base material provided with Ozone-containing gas is injected onto the layer surface and the second resin layer-forming resin melted and extruded into a thin film from the T-die, and then the first
This method of manufacturing a packaging material is characterized in that lamination is carried out so that the ozone-containing gas-spraying surface of the second resin layer-forming resin in a molten state is in contact with the ozone-containing gas-spraying surface of the resin layer.

[0009]

[Operation] The second melted and extruded thin film from the T-die.
The resin layer forming resin is laminated on the first resin layer laminated on the anchor coating agent layer provided on the support base material, and the first resin layer is melted from a T-die and extruded into a thin film. Before being laminated thereon, the surface of the second resin layer forming resin to be laminated with the first resin layer is oxidized by injection of ozone-containing gas. Therefore, the second resin layer is laminated to the first resin layer formed on the anchor coating agent layer with high interlayer adhesive strength, and a packaging material with excellent pressure resistance strength is manufactured.

[0010] Also, the surface of the first resin layer formed on the anchor coating agent layer provided on the supporting base material and the second resin layer forming resin melted and extruded into a thin film from the T-die are By performing oxidation treatment by spraying ozone-containing gas on both surfaces to be laminated to the surface of the first resin layer, the second resin layer was laminated to the first resin with even higher interlayer adhesion strength, and the high pressure resistance was further improved. Packaging material is manufactured.

[0011]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIGS. 1 and 2 are schematic diagrams of a tandem extrusion laminator that can be suitably used in the method of the present invention, and FIGS. 3 and 4 each show an example of a packaging material manufactured by the method of the present invention. It is a schematic sectional view.

In FIGS. 1 and 2, a tandem extrusion laminator 10 includes T-dies 11 and 15 for extruding the melted first resin layer-forming resin or second resin layer-forming resin into thin films, respectively, and the T-die. Cooling rolls 12a, 16a and nip rolls 12b for pressing and cooling the supplied sheet and the first resin layer forming resin or the second resin layer forming resin extruded in the form of a molten thin film from 11, 15, respectively, and laminating them. 16b, an unwinder 14 for supplying the supporting base sheet provided with the anchor coating agent layer between the cooling roll 12a and the nip roll 12b, and a winder 1 for winding up the formed packaging material.
3.

There are no particular restrictions on the T-dies 11 and 15, and ordinary T-dies for forming synthetic resin sheets can be used. The second resin layer forming resin extruded from the T-die 15 in the form of a molten thin film is on the way to the cooling roll 16a and the nip roll 16b. An injection nozzle 20b for injecting ozone-containing gas toward the target is provided, and an ozone generator 20a is connected to this injection nozzle 20b.

In addition, in the tandem extrusion laminator shown in FIG. 2, in addition to the injection nozzle 20b, a T
An injection nozzle 20c that injects ozone-containing gas toward the surface of the first resin layer formed by laminating the first resin forming resin extruded in the form of a molten thin film from the die 11 onto the anchor coating agent layer of the support base sheet. An ozone generator 20a is also connected to this injection nozzle 20c.

Next, a method for manufacturing a packaging material according to the present invention will be explained using the packaging material shown in FIG. 3 or 4 as an example. here,
The packaging material 1 shown in FIG. 3 or 4 includes a supporting base material 2, an anchor coating agent layer 3, a first resin layer 4, and a second resin layer 5.
Furthermore, the second resin layer 5 has an ozone-containing gas injection surface 5a. Moreover, in the packaging material 1 shown in FIG. 4, the first resin layer 4 further has an ozone-containing gas jetted surface 4a.

The packaging material 1 as described above is manufactured by the method of the present invention as follows. First, the first resin layer-forming resin is melted and extruded into a thin film from the T-die 11, and the support base sheet 21 on which the anchor coating agent layer 3 is provided is supplied from the unwinder 14, and then the cooling roll 12a and the nip roll. 12b and is pressed and cooled to form the first resin layer 4 on the anchor coating agent layer 3 of the supporting base sheet 21, forming the base sheet 22. Next, from the T-die 15,
The resin layer-forming resin is melted into a thin film and extruded, and ozone-containing gas supplied from the ozone generator 20a is injected from the injection nozzle 20b onto the molten second resin layer-forming resin. The purpose of spraying the ozone-containing gas onto the molten resin for forming the second resin layer is to oxidize the surface of the resin for forming the second resin layer. and,
As a measure of this surface oxidation, the interfacial surface tension of the ozone-containing gas sprayed surface of the second resin layer forming resin is set to be 32 dyn/cm or more, preferably 35 dyn/cm or more. In order to perform such surface oxidation, the ozone-containing gas is a mixed gas that uses air as a base gas and has an ozone concentration of 1 g/m@3 or more, preferably about 2 to 40 g/m@3. Such ozone-containing gas may also contain an inert gas such as nitrogen gas. Further, the ozone-containing gas is preferably injected at a flow rate of 1 to 5 Nm3/min. Furthermore, the ozone-containing gas may be injected in a preheated state in the range of room temperature to 80°C. On the other hand, the first resin layer 4
The above-mentioned base sheet 22 on which is formed is the cooling roll 16a.
and the nip roll 16b to form the packaging material 1 having the laminated structure shown in FIG.

Furthermore, the packaging material 1 having the laminated structure shown in FIG. 4 is manufactured using the tandem extrusion laminator shown in FIG. 2 in the following manner. That is, the ozone-containing resin is applied to the surface of the first resin layer 4 constituting the base sheet 22 formed in the same manner as described above and the second resin layer forming resin melted and extruded into a thin film from the T-die 15. Gas is injected respectively. Specifically, the ozone-containing gas supplied from the ozone generator 20a is injected from the injection nozzle 20c onto the surface of the first resin layer 4 constituting the base sheet 22, and the T-die 15 Ozone-containing gas supplied from the ozone generator 20a is injected from the injection nozzle 20b onto the second resin layer-forming resin which has been melted and extruded into a thin film. After such ozone-containing gas injection, the interfacial surface tension of the ozone-containing gas sprayed surface of the second resin layer forming resin is the same as above, and the ozone concentration, flow rate, etc. of the ozone-containing gas are also the same as above. be. Note that the ozone-containing gas is injected onto the surface of the first resin layer when the interfacial surface tension of the ozone-containing gas-injected surface of the first resin layer after the ozone-containing gas is injected is 3.
It should be 0 dyn/cm or more, preferably 35 dyn/cm or more.

As described above, the base sheet 22 having the first resin layer 4 onto which the ozone-containing gas has been injected and the second resin layer-forming resin are placed between the cooling roll 16a and the nip roll in such a direction that the surfaces to which the ozone-containing gas is injected are in contact with each other. 16b, the packaging material 1 having the laminated structure shown in FIG. 4 is formed and wound up by the winder 13. The thickness of the supporting base material 2 in such a packaging material 1 is usually about 10 to 100 μm. The thickness of the supporting base material 2 is less than 10 μm,
Printability may be poor or costs may increase. On the other hand, if it exceeds 100 μm, the cost may increase. As the material for forming the supporting base material 2, any material that can be laminated, such as metal foil, paper, or plastic film, can be suitably used.

The anchor coating agent layer 3 formed on the supporting substrate 2 contains an anchor coating agent such as an imine anchor coating agent, an organic titanium anchor coating agent, or a urethane anchor coating agent in an amount of 0.1 to 1. It is formed by coating with a coating amount of 0 g/m2. The first resin layer-forming resin melted and extruded into a thin film from the T-die 11 includes:
Examples include acid copolymers (EAA, EMAA, etc.), general-purpose low density polyethylene resin (LDPE), etc.
Generally, general-purpose low density polyethylene resin (LDPE) is preferably used. The thickness of the first resin layer 4 formed from such a first resin layer forming resin is usually 10 to 50 mm.
μm, preferably 15 to 30 μm. This thickness is 1
If it is less than 0 μm, adhesion may become unstable. On the other hand, if the thickness exceeds 50 μm, the cost may increase.

The second resin layer-forming resin melted and extruded into a thin film from the T-die 15 includes, for example, general-purpose low-density polyethylene resin (LDPE), linear low-density polyethylene resin (LLDPE), polypropylene resin ( PP), ionomer resin, ethylene-vinyl acetate copolymer resin (EVA), polyvinyl alcohol resin, polyester resin, ethylene-acrylic acid ester copolymer resin (EEA), ethylene-acrylic acid copolymer resin (EA)
A), ethylene-methacrylic acid copolymer resin (EMAA)
Thermoplastic resins such as, and mixtures of these resins are used. Further, the second resin layer forming resin may contain additives such as a lubricant, an antistatic agent, and an antifogging agent.

The thickness of the second resin layer 5 formed using such a second resin layer forming resin is usually 10 to 80 μm.
, preferably 20 to 60 μm. This thickness is 10μ
If it is less than m, heat seal strength and lamination strength may become unstable. On the other hand, if it exceeds 80 μm,
It can be costly. In the method of the present invention,
As described above, ozone-containing gas is injected onto the molten second resin layer forming resin or the first resin layer 4 to perform surface oxidation, and in this state, the second resin layer 5 and the first resin layer 4 are
Since these are laminated, the adhesive strength between the first resin layer 4 and the second resin layer 5 is improved.

Next, the present invention will be explained in more detail with reference to experimental examples. (Experimental Example 1) In the tandem extrusion laminator shown in FIG. 1, extrusion lamination was performed using the following materials under the following extrusion conditions to produce a packaging material with a laminated structure shown in FIG. 3 in one step.

Supporting base material: Biaxially stretched nylon having a coating film of vinylidene chloride on the surface [thickness 25 μm, "Eblem DCK" manufactured by Unitika Co., Ltd.] Anchor coating agent: Urethane anchor coating agent [coating amount 0.2 g /m2 (dry weight), "A515/A12" manufactured by Takeda Pharmaceutical Co., Ltd.] First resin layer forming resin: Low density polyethylene [M-11P manufactured by Mitsui Petrochemical Co., Ltd.] Second resin layer forming resin : Linear low-density polyethylene [Mitsui Petrochemical Co., Ltd. "UZ2080C"] Extrusion conditions for the first resin layer forming resin Screw L/D = 28 Cylinder temperature: C1 = 230°C, C2 = 260°C
, C3 = 290°C, C4 = 320°C Adapter temperature = 340°C T-die temperature: D1 to D5 = 335°C Laminate thickness = 20 μm Cooling roll temperature = 4°C Extrusion conditions for second resin layer forming resin Screw L/D = 28 Cylinder temperature: C1 = 230℃, C2 = 260℃
, C3 = 270℃, C4 = 280℃ Adapter temperature = 280℃ T die temperature: D1 ~ D5 = 300℃ Laminate thickness = 30μm Cooling roll temperature = 4℃ Injection conditions of ozone-containing gas Base gas = air Ozone concentration = 16g/ m3 Flow rate = 2.0 Nm3 /min Interfacial surface tension of second resin layer forming resin = 35 dyn/c
The interlayer adhesive strength and compressive strength of the obtained packaging material were examined. The results are shown in Table 1.

[0024]

[Table 1]

On the other hand, for comparison, a packaging material was manufactured under the same conditions as in the experimental example described above, except that the ozone-containing gas was not injected, and the interlayer adhesive strength and pressure resistance strength of the resulting packaging material were examined. . The results are shown in Table 1. (Experimental Example 2) In Experimental Example 1, an ionomer resin [UZ2080C] manufactured by Mitsui Petrochemicals Co., Ltd. was used instead of linear low-density polyethylene [UZ2080C] manufactured by Mitsui Petrochemical Co., Ltd. as the resin for forming the second resin layer.
A packaging material was manufactured under the same conditions as in Experimental Example 1, except that "Surlyn #1652" manufactured by Mitsui Petrochemicals, Ltd. was used, and the interlayer adhesive strength and pressure resistance strength of the resulting packaging material were examined. The results are shown in Table 1.

On the other hand, for comparison, a packaging material was manufactured under the same conditions as in the experimental example described above, except that the ozone-containing gas was not injected, and the interlayer adhesion strength and pressure resistance strength of the resulting packaging material were examined. . The results are shown in Table 1. (Experimental Example 3) In Experimental Example 1, ethylene-vinyl acetate copolymer resin [Mitsui Petrochemical Co., Ltd., "UZ2080C"] was used instead of linear low-density polyethylene [Mitsui Petrochemical Co., Ltd. "UZ2080C"] as the second resin layer forming resin. "P1007L" manufactured by Co., Ltd.
] A packaging material was produced under the same conditions as in Experimental Example 1 above, and the interlayer adhesion strength and pressure resistance of the resulting packaging material were examined. The results are shown in Table 1.

On the other hand, for comparison, a packaging material was manufactured under the same conditions as in the experimental example described above, except that the ozone-containing gas was not injected, and the interlayer adhesive strength and pressure resistance strength of the resulting packaging material were examined. . The results are shown in Table 1. As is clear from Table 1, the packaging material obtained by the manufacturing method of the present invention, in which at least the second resin layer-forming resin is subjected to ozone treatment and then the second resin layer-forming resin is laminated onto the first resin layer. Compared to conventional packaging materials obtained by laminating the first resin layer and the second resin layer-forming resin without ozone treatment of the second resin layer-forming resin, the interlayer lamination strength and pressure resistance strength are lower. It was also confirmed that there was an improvement.

[0028]

Effects of the Invention As detailed above, according to the method of the present invention, at least the second resin layer forming resin melted and extruded from the T-die in the form of a thin film, or further the anchor provided on the supporting base material Injecting ozone-containing gas onto the surface of the first resin layer laminated with the coating agent layer to promote air oxidation of the laminated surfaces of the first resin layer and the second resin layer forming resin, thereby improving interlayer adhesive strength. Therefore, it is possible to provide a method for producing a packaging material that can efficiently obtain a packaging material with improved pressure resistance without reducing transparency, increasing manufacturing cost, reducing processing suitability, etc.

[Brief explanation of drawings]

FIG. 1 is a schematic explanatory diagram showing an example of the configuration of a tandem extrusion laminator that can be suitably used in the method of the present invention.

FIG. 2 is a schematic explanatory diagram showing another example of the configuration of a tandem extrusion laminator that can be suitably used in the method of the present invention.

FIG. 3 is a cross-sectional view showing an example of the layered structure of a packaging material manufactured by the method of the present invention.

FIG. 4 is a sectional view showing another example of the layered structure of a packaging material manufactured by the method of the present invention.

[Explanation of symbols]

1...Packaging material 2...Supporting base material 3...Anchor coat agent layer 4...First resin layer 5...Second resin layer 4a, 5a...Ozone-containing gas injection surface 11, 15...T die

Claims (2)

[Claims] 1. A first resin layer forming resin, which is melted and extruded into a thin film from a T-die, is laminated onto the anchor coating agent layer of the supporting base material provided with the anchor coating agent layer, thereby forming the first resin layer. After forming, an ozone-containing gas is injected onto the second resin layer forming resin which has been melted and extruded into a thin film form from a T-die, and then the second resin layer forming resin which is in a molten state is injected onto the first resin layer. A method for producing a packaging material, comprising laminating the resin so that the ozone-containing gas sprayed surface is in contact with the resin. 2. A first resin layer forming resin, which is melted and extruded into a thin film from a T-die, is laminated onto the anchor coating agent layer of the supporting base material provided with the anchor coating agent layer, thereby forming the first resin layer. After forming the ozone-containing gas, an ozone-containing gas is injected onto the surface of the first resin layer and the second resin layer-forming resin melted and extruded into a thin film from the T-die, and then the first resin layer is covered with the ozone-containing gas. A method for manufacturing a packaging material, comprising laminating the second resin layer forming resin in a molten state so that the ozone-containing gas sprayed surface of the resin is in contact with the spraying surface.