JPH07246676A - Production of laminated packaging material - Google Patents

Abstract

PURPOSE:To laminate a thermoplastic resin layer in high close adhesiveness without generating a crack by pretreating the laminating surface of the thermoplastic resin layer with ozone before laminating the thermoplastic resin layer extruded within a specific temp. range to a silicon oxide layer. CONSTITUTION:A gas barrier film 3 is produced by forming a silicon oxide layer 2 for imparting gas barrier properties, especially, oxygen barrier properties and steam barrier properties to a laminated packaging material on a base material 1. l Subsequently, an anchor coat layer 4 is formed on the silicon oxide layer 2 of the gas barrier film 3 and a heat-sealable thermoplastic resin layer 5 is extruded from a T-die 8 to be passed through the nip between a cooling roll 6 and a pressure roll 7 to be bonded to the anchor coat layer 4 laminated to the gas barrier film 3. The extrusion temp. of the thermoplastic resin layer 5 is set to a temp. range from above 250 deg.C to 300 deg.C to enhance the close adhesiveness of the thermoplastic resin layer 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a laminated packaging material having a silicon oxide layer as a gas barrier layer and suitable for packaging pharmaceuticals, foods and the like. More specifically, it relates to a method for producing a laminated packaging material by laminating a thermoplastic resin layer to be a heat-sealing layer by an extrusion method so as not to generate cracks in the silicon oxide layer.

[0002]

2. Description of the Related Art Conventionally, a bag (pouch) -shaped container has been generally used as a form of a package for foods or pharmaceuticals, and a laminated packaging material having a plastic film as a base material is widely used as the material thereof.

By the way, laminated packaging materials are required to have various functions and performances depending on the contents to be packaged. Above all, a gas barrier property, particularly an oxygen barrier property, is provided in order to prevent oxidative deterioration and drying of the contents. Water vapor barrier properties are often required.

A method for imparting such oxygen barrier property and water vapor barrier property to a plastic film is as follows.
It is widely practiced to laminate an aluminum foil on a plastic film substrate. However, when incinerating a laminated packaging material having an aluminum foil as a gas barrier layer,
There is a problem that the oxide of aluminum foil remains as a lumpy residue. For this reason, recently, a vacuum deposition layer of a silicon oxide compound mainly composed of silicon monoxide (hereinafter referred to as a silicon oxide layer), which is easy to incinerate, excellent in transparency, and suitable for mass production in terms of cost, has been developed. Lamination on a plastic film substrate is performed.

As a conventional method for producing a laminated packaging material having such a silicon oxide layer, a gas barrier film is prepared by laminating a silicon oxide layer on a film substrate such as a flexible nylon film or polyethylene terephthalate by a vacuum deposition method. A method has been proposed in which a heat-sealable thermoplastic resin such as polyethylene is extrusion-coated on the silicon oxide layer of the gas barrier film, which is then subjected to an anchor treatment if necessary (Japanese Patent Publication No. 51-48511). No. 52-3418). In this case, the heat-sealable thermoplastic resin is
In order to obtain sufficient heat seal strength and prevent bag breakage, extrusion coating is usually performed at a resin temperature of 310 to 320 ° C. to a thickness of at least 50 μm or more.

However, since the silicon oxide layer formed as described above is a glassy layer which is prone to cracks, if a heat-sealing thermoplastic resin having a thickness of 50 μm or more is extrusion coated thereon. Due to the heat, the silicon oxide layer itself expands and contracts, and the base film expands and contracts, causing cracks, resulting in a decrease in oxygen barrier properties and water vapor barrier properties. In particular, the thinner the silicon oxide layer, the more remarkable the phenomenon.

In order to solve this problem, a thermoplastic resin layer having a heat-sealing property is formed so that a thermoplastic resin layer can be laminated thereon by an extrusion coating method without causing a crack in the silicon oxide layer of the gas barrier film. It has been proposed to set the layer thickness to 30 μm or less to reduce its heat content (Japanese Patent Laid-Open No. 5-178362). In addition, the heat sealable thermoplastic resin is 250
The surface of the thermoplastic resin layer may be subjected to ozone treatment in advance in order to compensate for the decrease in the adhesive strength between the thermoplastic resin layer and the silicon oxide layer due to extrusion at a resin temperature of ℃ or less and lowering the resin temperature. Proposed (JP-A-5-577)
No. 382).

[0008]

However, as described in JP-A-5-178362, a heat-sealable thermoplastic resin layer is extruded on a silicon oxide layer of a gas barrier film in a thickness of 30 μm or less. In that case, there is a problem that a practical level of seal strength cannot be obtained.

To solve this problem, it is conceivable to secure the thickness of the heat-sealing layer by simultaneously laminating the heat-sealing resin film by sand lamination during extrusion. However, in this case, a heat-sealable resin film has to be separately prepared and prepared, and moreover, it is difficult to condition the conditions for the sand lamination as compared with the extrusion coating, resulting in a problem that the manufacturing cost increases.

On the other hand, as described in JP-A-5-573782, when the temperature of the extruded resin is set to 250 ° C. or lower, a low density polyethylene or a linear material generally used as a heat-sealable thermoplastic resin layer. When low density polyethylene is used, the appropriate extrusion temperature range for these resins is a relatively high temperature of 310 ° C. to 320 ° C., so that extrusion cannot be efficiently performed by an extrusion die, and the adhesion is also low. There is a problem that it is not enough.

The present invention is intended to solve the above-mentioned problems of the prior art, in which a heat-sealable thermoplastic resin composed of low density polyethylene or linear low density polyethylene is used as a gas barrier film of silicon oxide. 3 on a layer
Even when extruded with a relatively thick layer thickness exceeding 0 μm,
It is an object of the present invention to enable stacking with high adhesion without causing cracks in the silicon oxide layer.

[0012]

[Means for Solving the Problems] The present inventors set the resin temperature at the time of extrusion of a heat-sealable thermoplastic resin layer made of low-density polyethylene or linear low-density polyethylene at a temperature at which the thermoplastic resin can be extruded. And at a temperature at which a crack does not occur in the silicon oxide layer, and further, before laminating the extruded thermoplastic resin layer on the silicon oxide layer, by subjecting the laminated surface of the thermoplastic resin layer to ozone treatment in advance, The inventors have found that the object can be achieved, and have completed the present invention.

That is, according to the present invention, a gas barrier film comprising a substrate and a silicon oxide layer formed on one surface thereof is provided on the silicon oxide layer via an anchor coat layer.
In a method for producing a laminated packaging material by laminating a thermoplastic resin layer made of low density polyethylene or linear low density polyethylene by an extrusion method, the thermoplastic resin layer is 250
Laminated by extruding at a temperature of more than 300 ° C and below 300 ° C, and before laminating the extruded thermoplastic resin layer on the silicon oxide layer, the laminated surface of the thermoplastic resin layer is subjected to ozone treatment in advance. A method for manufacturing a packaging material is provided.

The present invention will be described below in detail with reference to the drawings. In the drawings, the same numbers indicate the same or equivalent components.

FIG. 1 is an explanatory view of the manufacturing process of the laminated packaging material of the present invention.

First, the base material 1 as the base material of the laminated packaging material.
(FIG. 1A) is prepared. As such a substrate 1, a flexible resin film of polyethylene, polypropylene, polyester, nylon or the like, preferably a polyethylene terephthalate film can be used.
The thickness of the substrate 1 is not particularly limited and can be appropriately selected according to the purpose of use.

A gas barrier film 3 is produced by forming a silicon oxide layer 2 on the base material 1 for imparting a gas barrier property, particularly an oxygen barrier property and a water vapor barrier property to a laminated packaging material (FIG. 1 (b). )). The silicon oxide layer 2 can be formed by a dry process such as a vacuum vapor deposition method, an ion plating method, a sputtering method, a plasma vapor deposition method or a CVD method. Among them, the vacuum deposition method is preferable in terms of manufacturing cost.

The composition of the silicon oxide layer 2 is represented by the general formula Si _x O.
_It is a mixture of silicon compounds represented by _y (x = 1,2, y = 0,1,2,3) and mainly composed of silicon monoxide. The thickness of the silicon oxide layer can be appropriately determined according to the purpose of use. For example, when used in a retort pouch, it is 1000-1500 angstroms,
If transparency and flexibility are especially important, 20
The thickness is about 0 to 800 angstroms.

Next, an anchor coat layer 4 is formed on the silicon oxide layer 2 of the gas barrier film 3 (see FIG. 1).
(C)). The anchor coat layer 4 is a layer for enhancing the adhesiveness of a heat-sealing thermoplastic resin layer described later.

The anchor coat layer 4 is formed by using a gravure plate as an anchor coat agent and using a coater.
It can be carried out by applying the composition to and drying it. As such an anchor coating agent, a 2-liquid type urethane anchor coating agent or a 1-liquid type polybutadiene-based or polyethyleneimine-based aqueous anchor coating agent can be used. When a urethane-based anchor coating agent is used, the amount thereof is preferably 1.5 to 3.0 g / m ² , although it varies depending on the type and the like. When the water-based anchor coating agent is used, the amount used varies depending on the type and the like, but is preferably 4 × 10 ^{−3 to} 5 × 1.
It is 0 ⁻² g / m ² . Therefore, compared to urethane-based anchor coating agents, using water-based anchor coating agents
It is advantageous that the amount used can be made extremely small and the material cost can be kept low, and the one-liquid type can simplify the forming operation.

Subsequently, as shown in FIG. 1D, the heat sealable thermoplastic resin layer 5 is extruded from the T die 8 onto the anchor coat layer 4 laminated on the gas barrier film 3 to cool the roll 6. And pressure roll 7
And then crimp it. As a result, FIG.
A laminated packaging material as shown in is obtained.

In the present invention, low density polyethylene or linear low density polyethylene is used as the heat sealable thermoplastic resin layer 5.

The low density polyethylene or linear low density polyethylene used in the present invention is usually
Although it is extruded at a relatively high temperature of 310 to 320 ° C., the gas barrier film 3 is extruded at this temperature.
The possibility that cracks will occur in the silicon oxide layer 2 is increased. On the contrary, if the temperature is 250 ° C. or lower, it cannot be efficiently extruded. Therefore, in the present invention, the temperature of the thermoplastic resin layer 5 is more than 250 ° C. and not more than 300 ° C., preferably 270 to 295 ° C., more preferably 280 to 2 ° C.
Extrude at a temperature of 90 ° C.

Further, the extrusion temperature of the thermoplastic resin layer 5 is changed from the usual 310 to 320 ° C. to over 250 ° C. to 300 ° C.
With the following, the adhesiveness between the thermoplastic resin layer 5 and the silicon oxide layer 2 decreases. Therefore, in the present invention, before laminating the thermoplastic resin layer 5 on the silicon oxide layer 2, the laminating surface 5a is subjected to ozone treatment in advance. As a result, the laminated surface 5a of the thermoplastic resin layer 5 can be modified to enhance its adhesiveness. Here, as the ozone treatment, as shown in FIG. 1D, ozone gas can be blown onto the extruded laminated surface 5a of the thermoplastic resin layer 5 as indicated by an arrow in the figure. in this case,
If the concentration of ozone in the ozone gas used is too low, the degree of surface oxidation tends to be inadequate, so it is preferably 10 to 60 g / N · m ³ or more, and if the flow rate is too high. The resin film tends to move and become non-uniform, and when it is too small, the degree of oxidation tends to be inadequate. Therefore, the amount is preferably ³ to 8 N · m ³ .

The thickness of the thermoplastic resin layer 5 is preferably more than 30 μm from the viewpoint of ensuring the sealing strength. More preferably, the thickness is 40 μm or more.

A printing layer may be provided on the silicon oxide layer 2 prior to the formation of the anchor coat layer 4 by using an ink usually used for packaging materials.

The laminated packaging material obtained as described above can be formed into an appropriate form, for example, a bag shape, and can be used as in the conventional case.

[0028]

In the method of manufacturing the laminated packaging material of the present invention,
A thermoplastic resin layer made of low-density polyethylene or linear low-density polyethylene is extruded at a temperature higher than 250 ° C and lower than 300 ° C. Therefore, it is possible to prevent the silicon oxide layer from cracking. Further, in the present invention, before laminating the extruded thermoplastic resin layer on the silicon oxide layer, the laminated surface of the thermoplastic resin layer is subjected to ozone treatment in advance. Therefore, it is possible to improve the adhesiveness of the thermoplastic resin and the sealing strength.

[0029]

EXAMPLES The present invention will be specifically described below with reference to examples.

Example 1 A gas barrier was formed by forming a silicon oxide layer having a thickness of 400 angstroms on one side of a polyethylene terephthalate film (trade name NS, manufactured by Teijin Ltd.) having a thickness of 12 μm as a substrate by a vacuum deposition method. I got a film.

A urethane adhesive (trade name: AD980, manufactured by Toyo Morton Co., Ltd.) was applied to the surface of the gas barrier film on the side of the silicon oxide layer at a rate of ² g / m ² (dry coating amount) to provide an anchor coat layer. Was formed.

On the anchor coat layer of the gas barrier film thus produced, a linear low density polyethylene (trade name UZ15100C, manufactured by Mitsui Petrochemical Industry Co., Ltd.) was formed as a heat-sealable thermoplastic resin layer having a thickness of 15 μm. Is extruded from the T-die at a temperature of 290 to 295 ° C,
And on the laminated surface of the extruded linear low density polyethylene,
Air containing ozone at a concentration of 30-40 g / Nm ²
Laminating was performed while spraying at a flow rate of ˜5 N · m ³ to obtain the laminated packaging material of the present invention.

Example 2 A laminated packaging material was obtained in the same manner as in Example 1 except that the thickness of the heat-sealing thermoplastic resin layer was 30 μm.

Example 3 A laminated packaging material was obtained in the same manner as in Example 1 except that the thickness of the heat-sealing thermoplastic resin layer was 40 μm.

Comparative Example 1 A laminated packaging material was obtained in the same manner as in Example 1 except that the laminated surface of the heat sealable thermoplastic resin layer was not treated with ozone.

Comparative Example 2 A laminated packaging material was obtained in the same manner as in Example 2 except that the laminated surface of the heat sealable thermoplastic resin layer was not treated with ozone.

Comparative Example 3 A laminated packaging material was obtained in the same manner as in Example 3 except that the laminated surface of the heat sealable thermoplastic resin layer was not treated with ozone.

Example 4 In place of the urethane adhesive, a polybutadiene adhesive (trade name EC451, manufactured by Toyo Morton Co., Ltd.) was used as an aqueous anchor coating agent at 0.04 g / m ² (dry coating amount).
A laminated packaging material was obtained in the same manner as in Example 3 except that the coating was carried out at the ratio of. Upon application, the polybutadiene-based adhesive used was diluted with a mixed solvent of methanol / water (8/1 (v / v)) so that the solid content was about 1%.

Example 5 Instead of the urethane adhesive, a polyethyleneimine adhesive (trade name P-1000, as an aqueous anchor coating agent,
A laminated packaging material was obtained in the same manner as in Example 3 except that 8 × 10 ⁻³ g / m ² (dry coating amount) of Nippon Shokubai Chemical Co., Ltd. was applied. In addition, at the time of application, as a polyethyleneimine-based adhesive, methanol / water (7/1 (v
/ V)) diluted with a mixed solvent such that the solid content becomes about 0.2%.

Comparative Example 4 Instead of linear low density polyethylene, low density polyethylene (trade name M-14P, manufactured by Mitsui Petrochemical Industry Co., Ltd.) was used, and the extrusion temperature was adjusted to 310 to 320 ° C., and ozone treatment was carried out. A laminated packaging material was obtained in the same manner as in Example 1 except that it was omitted.

Comparative Example 5 Instead of linear low-density polyethylene, low-density polyethylene (trade name M-14P, manufactured by Mitsui Petrochemical Industry Co., Ltd.) was used, the extrusion temperature was 310 to 320 ° C., and ozone treatment was carried out. A laminated packaging material was obtained in the same manner as in Example 2 except that it was omitted.

Comparative Example 6 Instead of linear low-density polyethylene, low-density polyethylene (trade name M-14P, manufactured by Mitsui Petrochemical Co., Ltd.) was used, the extrusion temperature was 310 to 320 ° C., and ozone treatment was not performed. A laminated packaging material was obtained in the same manner as in Example 3 except for the above.

(Evaluation) Regarding the laminated packaging materials obtained in Examples 1 to 5 and Comparative Examples 1 to 6, oxygen barrier property (oxygen permeability), water vapor barrier property (moisture permeability) or thermoplasticity under the following conditions. The adhesive strength of the resin layer was measured.
The results obtained are shown in Table 1.

The moisture vapor permeability (WVTR, g / m ² · day) is measured by a moisture vapor permeability tester (PERMATRAN-WTWI).
N, MODERN CONTROLS, INC) was used under the conditions of 40 ° C. and 100% RH under atmospheric pressure. Oxygen permeability (O ₂ TR, cc / m ² · day) is measured by an oxygen permeability tester (OX-TRAN10 / 50A).
(Manufactured by MODERN CONTROLS, INC) under atmospheric pressure at 25 ° C. and 100% RH. For the obtained laminated packaging material, the adhesion strength between layers was evaluated by a 180 degree peel test as an index showing the effect of ozone treatment. The larger this value is, the higher the adhesive strength is. When this value is small, delamination is likely to occur when the bag is dropped, which causes a problem of poor appearance and bag breakage.

[0045]

[Table 1] Extrusion temperature O ₃ Layer thickness O ₂ TR WVTR Adhesive strength ℃ Treatment μm cc / m ²・ day g / m ²・ day g / 15mm Example 1 290 to 295 ○ 15 1.0 to 2.0 1.0 to 2.0 300> Comparative Example 1 290 to 295 × 15 1.0 to 2.0 1.0 to 2.0 to 0 Comparative Example 4 310 to 320 × 15 1.0 to 2.0 1.0 to 2.0 300> Example 2 290 to 295 ○ 30 1.9 to 2.2 2.2 to 3.0 300> Comparative Example 2 290 to 295 × 30 1.9 to 2.2 2.2 to 3.0 to 0 Comparative Example 5 310 to 320 × 30 4.0 to 7.0 6.0 to 7.0 300> Example 3 290 ~ 295 ○ 40 2.5 ~ 2.2 2.1 ~ 2.7 300> Comparative Example 3 290 ~ 295 × 40 2.5 ~ 2.2 2.1 ~ 2.7 ~ 0 Comparative Example 6 310 ~ 320 × 40 40 ~ 50 7.0 ~ 10 300> Example 4 290 ~ 295 O 40 2.5-2.2 2.1-2.7 300> Example 5 290-295 o 40 2.5-2.2 2.1-2.7 280 From the results in Table 1, low-density polyethylene was added to 310-320.
When extruded at a temperature of ° C, when the thickness is 15 µm (Comparative Example 4), the gas barrier property of the laminated packaging material is good, but when it is 30 µm or more (Comparative Example 5 and Comparative Example 6), the gas barrier property is large. It can be seen that it will decrease.

On the other hand, the linear low density polyethylene is 290-290.
When extruded at 295 ° C., not only when the thickness is 15 μm (Example 1, Comparative Example 1) but also when 30 μm (Example 2, Comparative Example 2) and 40 μm (Example 3, Comparative Example 3) It can be seen that the gas barrier property is good.

However, if the linear low density polyethylene is 290
When extruded at ˜295 ° C. and laminated as they are (Comparative Example 1, Comparative Example 2 and Comparative Example 3), it can be seen that the adhesive strength is practically 0 g, which cannot be put to practical use.

On the other hand, the linear low density polyethylene is
It can be seen that when the layers are extruded at 90 to 295 ° C., treated with ozone, and then laminated (Example 1, Example 2 and Example 3), the adhesive strength is 280 g or more, which is sufficient for practical use.

From the above results, according to the present invention, a heat-sealable thermoplastic resin composed of low-density polyethylene or linear low-density polyethylene is provided on the silicon oxide layer of the gas barrier film in a relatively thick layer exceeding 30 μm. It can be seen that even if the silicon oxide layer is extruded with a large thickness, it can be laminated with high adhesion without causing cracks in the silicon oxide layer.

According to the results of Examples 4 and 5, even when the anchor coat layer was formed from the water-based anchor coating agent, the adhesive strength was the same as when the urethane-based adhesive was used (Examples 1 to 3). I also realized that

[0051]

According to the present invention, a heat-sealable thermoplastic resin composed of low-density polyethylene or linear low-density polyethylene is extruded onto a silicon oxide layer of a gas barrier film in a relatively thick layer thickness of more than 30 μm. Even in the case, the silicon oxide layer can be laminated with high adhesion without causing cracks. Therefore, it becomes possible to form a heat-sealing thermoplastic resin on the silicon oxide layer without lowering the oxygen barrier property and the water vapor barrier property.

[Brief description of drawings]

FIG. 1 is a manufacturing process diagram illustrating a method for manufacturing a laminated package material according to the present invention.

[Explanation of symbols]

 1 Base Material 2 Silicon Oxide Layer 3 Gas Barrier Film 4 Anchor Coat Layer 5 Heat Sealing Thermoplastic Resin Layer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location B32B 27/32 Z 8115-4F 31/12 7148-4F 31/30 7148-4F C08J 7/00 A 7310-4F // B29K 23:00 105: 20 B29L 9:00 C08L 23:00

Claims (6)

[Claims] 1. A low density polyethylene or a linear low density polyethylene via an anchor coat layer on a silicon oxide layer of a gas barrier film comprising a substrate and a silicon oxide layer formed on one surface thereof. A method for producing a laminated packaging material by laminating a thermoplastic resin layer by an extrusion method, comprising:
Manufacture of a laminated packaging material characterized by extruding a thermoplastic resin layer extruded at a temperature of ℃ or below and subjecting the laminated surface of the thermoplastic resin layer to ozone treatment in advance before laminating the extruded thermoplastic resin layer on the silicon oxide layer. Method. 2. A thermoplastic resin having a resin temperature of 270 to 295.
The manufacturing method according to claim 1, wherein extrusion is performed at a temperature of ° C. 3. A thermoplastic resin having a resin temperature of 280 to 290.
The manufacturing method according to claim 2, wherein extrusion is performed at a temperature of ℃. 4. The manufacturing method according to claim 1, wherein the thermoplastic resin layer is extruded to a thickness of more than 30 μm. 5. The method according to claim 4, wherein the thermoplastic resin layer is extruded with a thickness of 40 μm or more. 6. The method according to claim 1, wherein the anchor coat layer comprises a urethane adhesive or a water-based anchor agent.