JP2008221708A - Laminated body, its manufacturing method, and paper-made container using laminated body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminated body superior in gas barrier property at low cost. <P>SOLUTION: The laminated body is formed by laminating a polyolefinic resin layer, a paper base material layer, a gas barrier layer containing a polyolefinic resin, a gas barrier resin and an inorganic layered compound, and an overcoat layer containing an alkyd resin and a urethane resin, in this order. Here, the mass ratio of the gas barrier resin to the inorganic layered compound is preferably 30:70-70:30, and the mass ratio of the alkyd resin to the urethane resin is preferably 4:1-1:1. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a laminate excellent in gas barrier properties for preventing permeation of oxygen and the like, a method for producing the laminate, and a paper container using the laminate.

A laminate in which a polyolefin-based resin layer such as polyethylene is laminated on the surface of a paper substrate is widely used as a packaging material. Among these, the laminate used in the paper container for filling and packaging liquid foods and drinks such as alcoholic beverages and juices has excellent gas barrier properties as well as ensuring strength when used as a container. Therefore, a laminate in which an aluminum foil is interposed is generally used. However, a laminate with an aluminum foil interposed therebetween is expensive due to its complicated manufacturing process, and has a problem that the load on the environment is large when discarded after being used as a packaging material. is there.
Therefore, as a laminate provided with gas barrier properties without using an aluminum foil, a polyolefin resin layer, a paper base layer, and a barrier layer composed of a coating film made of a resin composition containing a resin and an inorganic layered compound, The thing in which the polyolefin resin layer was laminated | stacked one by one is proposed (for example, refer patent document 1).

JP 2004-17993 A

However, the actual situation is that the laminate described in Patent Document 1 does not have sufficient gas barrier properties, and development of a low-cost laminate having better gas barrier properties is desired.
Therefore, this invention is made | formed in view of the said situation, and it aims at providing the laminated body excellent in gas-barrier property at low cost.

A first invention for achieving the above object includes a polyolefin resin layer, a paper base layer, a polyolefin resin layer, a gas barrier layer containing a gas barrier resin and an inorganic layered compound, an alkyd resin, and a urethane resin. And an overcoat layer including the layers are laminated in this order.
Here, the mass ratio between the gas barrier resin and the inorganic layered compound is preferably 30:70 to 70:30, and the mass ratio between the alkyd resin and the urethane resin is 4: 1 to 1: 1. Preferably there is.

  2nd invention is a paper container characterized by processing the said laminated body so that an overcoat layer may become an outer surface.

  A third invention includes a step of extrusion-coating a polyolefin resin on both sides of a paper substrate to form a polyolefin resin layer, and a gas barrier containing a gas barrier resin and an inorganic layered compound on one surface of the polyolefin resin layer. A laminate comprising: a step of forming a gas barrier layer by applying the composition; and a step of forming an overcoat layer by applying an overcoat composition containing an alkyd resin and a urethane resin on the gas barrier layer. It is a manufacturing method of a body.

  ADVANTAGE OF THE INVENTION According to this invention, the laminated body excellent in gas barrier property can be provided at low cost.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a schematic cross-sectional view of a laminate according to the present embodiment. As shown in FIG. 1, the laminate according to the present embodiment includes a polyolefin resin layer 1a, a paper base layer 2, a polyolefin resin layer 1b, a gas barrier layer 3 containing a gas barrier resin and an inorganic layered compound. And the overcoat layer 4 containing an alkyd resin and a urethane resin is laminated | stacked in this order. The laminate according to the present embodiment is characterized in that an overcoat layer 4 containing a specific resin is laminated on the gas barrier layer 3. This overcoat layer 4 plays a role of preventing the gas barrier layer 3 from being peeled off due to ruled lines or folding during processing of the laminate into a paper container, and also improving the gas barrier property itself.
In addition, in order to improve the aesthetics of the paper container using a laminated body, you may provide a pattern layer between the polyolefin-type resin layer 1b and the gas barrier layer 3. FIG.

Examples of the olefin resin constituting the polyolefin resin layers 1a and 1b include polypropylene, medium density polyethylene, high density polyethylene, high pressure method low density polyethylene, Ziegler low density polyethylene, and linear polyethylene. From the viewpoint of low-temperature sealing properties, transparency, and processability, it is preferable to use high-pressure low-density polyethylene as the olefin resin. The polyolefin resin layer 1a that is the innermost layer of the paper container is preferably formed with a thickness in the range of, for example, 20 μm to 60 μm, and the polyolefin resin layer 1b has a thickness in the range of 10 μm to 20 μm. It is preferable to form.
In addition, although it is desirable not to add an additive to the polyolefin-type resin layer 1a used as an innermost layer from a sanitary viewpoint with respect to the content, it is the range which does not impair the effect of this invention to the polyolefin-type resin layer 1b. Antioxidants, ultraviolet absorbers, antistatic agents, antiblocking agents, flame retardants, dyes, pigments, and the like may be added as appropriate.

As the paper substrate constituting the paper substrate layer 2, known paper such as coated paper, card paper, ivory paper, manila ball or the like, milk carton base paper, cup base paper, kraft paper, high-quality paper or the like is used. it can. The basis weight of the paper substrate may be suitably determined depending on the form of the paper container with laminate, preferably ^{250g / m 2 ~500g / m 2} .
Further, the corona discharge treatment may be applied to the surface of the paper substrate before the olefin resin layers 1a and 1b are laminated on the paper substrate. By performing corona discharge treatment, the adhesive strength between the layers can be improved. The corona discharge treatment can be performed by using a known corona discharge treatment device and passing the paper substrate through the generated corona atmosphere. The corona discharge output at this time is preferably 3 kW to 4.5 kW.

The gas barrier layer 3 is formed by applying a gas barrier composition containing a gas barrier resin, an inorganic layered compound, a solvent such as water or an organic solvent on the olefin-based resin layer 1b. The thickness of the gas barrier layer 3 is preferably a dry film is ^{0.2g / m 2 ~3.0g / m 2} . If the thickness of the gas barrier layer 3 is less than 0.2 g / m ² as a dry film, the target gas barrier property may not be obtained. On the other hand, it is troublesome to apply an amount exceeding 3.0 g / m ^2. (In particular, it is difficult to apply by gravure printing). The thickness of the gas barrier layer 3 is more preferably as a dry film is ^{0.3g / m 2 ~2.0g / m 2} .

  In the gas barrier composition, the inorganic layered compound and the gas barrier resin are preferably contained in a total amount of 1% by mass to 30% by mass. If the total of the inorganic layered compound and the gas barrier resin is less than 1% by mass, it may be difficult to form the gas barrier layer 3 having an appropriate film thickness, whereas if it exceeds 30% by mass, In some cases, the fluidity of the gas barrier composition is lowered, making application difficult.

  Examples of the inorganic layered compound include kaolinite having a 1: 1 structure of montmorillonite and phyllosilicate, dickite, nacrite, halloysite, antigolite, chrysotile, pyrophyllite, beidellite, and the like. In addition, two or more kinds may be used in combination. Among these, montmorillonite is preferable from the viewpoint of excellent gas barrier performance and application suitability when used in a gas barrier composition.

  Examples of the gas barrier resin include a highly crystalline resin such as polyvinyl alcohol resin, ethylene-vinyl alcohol copolymer resin (ethylene-vinyl alcohol resin), polyacrylonitrile resin, polyamide resin, polyester resin, polyurethane resin, Examples thereof include polyacrylic resins, and these may be used alone or in combination of two or more. Among these, an ethylene-vinyl alcohol resin is preferable from the viewpoint of excellent gas barrier performance.

  Among the gas barrier compositions described above, it is preferable to use an aqueous solution or an organic solvent in which a gas barrier resin is dissolved, in which a cleaved inorganic layered compound is dispersed. Such a gas barrier composition is, for example, It is commercially available from Sakata Inx Corporation under the trade name Ecostage (registered trademark) GB.

  The mass ratio of the gas barrier resin and the inorganic layered compound contained in the gas barrier layer 3 is preferably 30:70 to 70:30. If the amount of the inorganic layered compound is too small, the gas barrier property may be lowered. On the other hand, if the amount of the inorganic layered compound is too large, the film strength of the gas barrier layer 3 is undesirably lowered. The gas barrier layer 3 may contain components other than the inorganic layered compound and the gas barrier resin, but most of them are preferably composed of the inorganic layered compound and the gas barrier resin.

The overcoat layer 4 is formed by applying an overcoat composition in which an alkyd resin and a urethane resin are dissolved in an organic solvent or the like on the gas barrier layer 3. The thickness of the overcoat layer 4 is preferably as a dry film is ^{0.1g / m 2 ~2.0g / m 2} . When the thickness of the overcoat layer 4 is less than 0.1 g / m ² as a dry film, may not be able to prevent the peeling of the gas barrier layer 3 by ruled lines insertion and folding, while the 2.0 g / m ² It is troublesome to apply an excessive amount (particularly, it is difficult to apply by gravure printing).

  The overcoat composition preferably contains 5% by mass to 50% by mass of the total (solid content) of the alkyd resin and the urethane resin. When the resin solid content is less than 5% by mass, it may be difficult to form the overcoat layer 4 having an appropriate film thickness. On the other hand, when the resin solid content exceeds 50% by mass, the flow of the overcoat composition may be difficult. It may be difficult to apply due to a decrease in properties.

Examples of alkyd resins include polyesters synthesized from polybasic acids and polyhydric alcohols. Examples of the urethane resin include those synthesized from ester-based or ether-based polyols and isocyanates.
Such an overcoat composition is commercially available, for example, from Showa Ink Industry Co., Ltd. under the trade name SL-A OP Varnish.

  Moreover, it is preferable that the mass ratio of alkyd resin and urethane resin contained in the overcoat layer 4 is 4: 1 to 1: 1. If the amount of alkyd resin is too small, the adhesion to the gas barrier layer 3 may be reduced. On the other hand, if the amount of alkyd resin is too large, the heat resistance may be reduced.

Below, the manufacturing method of the paper container which concerns on this Embodiment is demonstrated.
First, polyolefin resin is extrusion coated on both sides of a paper substrate to form polyolefin resin layers 1a and 1b. As processing conditions for extrusion coating, for example, when polyethylene is used as the olefin resin, the extrusion temperature is set to 300 ° C. to 350 ° C., and the line speed (feeding speed) is set to a range of 80 to 250 m / min. Good.

Next, the gas barrier layer 3 is formed by applying a gas barrier composition containing a gas barrier resin and an inorganic layered compound on one of the polyolefin resin layers 1a and 1b formed on both surfaces of the paper substrate layer 2. To do. The coating amount of the gas barrier composition may be suitably set so that the thickness of the gas barrier layers 3 is 0.2g / m ² ~3.0g / m ² as dry film. Here, when a picture layer is provided between the polyolefin resin layer 1b and the gas barrier layer 3, a known ink composition is added to the polyolefin resin layer 1b before or at the same time as the gas barrier layer 3 is formed. What is necessary is just to apply | coat and form a pattern.

Finally, a laminate is obtained by applying an overcoat composition containing an alkyd resin and a urethane resin on the gas barrier layer 3 to form the overcoat layer 4. The coating amount of the overcoat composition may be appropriately set so that the thickness of the overcoat layer 4 is 0.1g / m ² ~2.0g / m ² as a dry film.
In addition, in order to avoid that the inorganic stratiform compound contained in the gas barrier layer 3 comes into contact with the contents filled in the paper container, the gas barrier layer is included in the heat seal portion that is heat-sealed when processed into the paper container. 3 and the overcoat layer 4 are preferably not provided.

  As a method for applying the gas barrier composition, the ink composition, and the overcoat composition, known gravure printing, planographic printing, letterpress printing, screen printing, and the like can be used. Among these, it is preferable to employ gravure printing because the coating amount is stable and productivity is high.

  By processing the laminate obtained by the above manufacturing method, paper containers having various shapes such as a gable top type and a brick type can be manufactured. Specifically, as shown in FIG. 2, first, a blank sheet 7 for a paper container having a body-sealed heat seal portion 6 is prepared by providing ruled lines 5 at necessary portions simultaneously with punching out the laminate. Next, in the gable top type paper container 8 as shown in FIG. 3, a material obtained by bonding the body part and the body-sealed heat seal part 6 with a frame seal or hot air seal is supplied to the filling machine, It can be produced by a known method of forming, filling and sealing on a filling machine. In addition, in a brick-type paper container, the laminate is often supplied in a roll form to a molding and filling machine, and molding, filling, and sealing are continuously performed. When processing a laminated body, it is preferable to process so that the overcoat layer 4 may become an outer surface.

  The use of the paper container produced in this way is not particularly limited. For example, various detergents such as car detergents, floor detergents, kitchen detergents, laundry detergents, shampoos, For toiletries such as rinses, perm liquids, chemicals such as mold removers, developers, agricultural chemicals, sake, shochu, wine, milk, juice drinks, green tea, tea, oolong tea, soy sauce, miso, dressing and other food and drink Can be used as a container. In particular, since the paper container according to the present embodiment has an excellent gas barrier property, it is suitable as a container for food and drink that is circulated and has a short shelf life.

Hereinafter, the present invention will be described in more detail with reference to examples. However, these are merely examples and do not limit the present invention.
<Example 1>
Corona discharge treatment was performed on both sides of a paper substrate having a basis weight of 313 g / m ² with an output of 4.5 kW. Next, by extrusion coating, 37 μm of high-pressure low-density polyethylene is laminated as a polyolefin-based resin layer 1a on one side of a paper base material, and 17 μm of high-pressure low-density polyethylene is laminated as a polyolefin-based resin layer 1b on the other side. I let you. The extrusion coating processing conditions at this time were set at an extrusion temperature of 330 ° C. and a line speed of 150 m / min. Subsequently, a gas barrier composition (Ecostage (registered trademark) GB, manufactured by Sakata Inx Corporation) containing montmorillonite and ethylene-vinyl alcohol copolymer resin is printed on the polyolefin resin layer 1b by gravure printing and dried. A gas barrier layer 3 was formed. The coating amount of the gas barrier composition at this time was such an amount that the thickness of the gas barrier layer 3 was 0.3 g / m ² as a dry film. Furthermore, an overcoat composition containing an alkyd resin and a urethane resin on the gas barrier layer 3 (SL-A OP varnish, alkyd resin: urethane resin = 2: 1, solid content 30% by mass, manufactured by Showa Ink Industries, Ltd.) Was printed by gravure printing and dried to form an overcoat layer 4 to obtain a laminate of Example 1. The coating amount of the overcoat composition at this time was such that the thickness of the overcoat layer 4 was 0.3 g / m ² as a dry film.

  The obtained laminate was punched into a shape as shown in FIG. 2 and simultaneously provided with ruled lines (dotted lines in FIG. 2) to obtain a blank sheet for a gable-top type paper container. Next, the body portion of the blank sheet and the body-sealed heat seal portion 6 are bonded together by a frame seal, and this is supplied to a filling machine. As shown in FIG. 3, the length 70 mm × width 70 mm × height 234 mm (gable) A gable-top type paper container having a top portion height of 39 mm) was produced. During the processing, no peeling of the gas barrier layer 3 and the overcoat layer 4 was observed.

<Examples 2 to 4>
Except for changing the thickness of the gas barrier layer to 0.5 g / m ² in Example ² , 1.0 g / m ² in Example 3, and 2.0 g / m ² in Example 4 as a dry film, Similarly, a gable top type paper container was prepared. During the processing, no peeling of the gas barrier layer 3 and the overcoat layer 4 was observed.

<Comparative Example 1>
A gable-top paper container was prepared in the same manner as in Example 1 except that no overcoat layer was formed. In addition, peeling of the gas barrier layer 3 was seen in part in the ruled line part of the blank sheet pasted on the cylinder.

<Evaluation of gas barrier properties>
The gas barrier property was evaluated according to the following method for the case-bonded blank sheets of Examples 1 to 4 and Comparative Example 1.
Under conditions of a temperature of 23 ° C. and a humidity of 90% RH, the oxygen permeability in the ruled line portion of the blank sheet pasted on a cylinder was measured using OX-TRAN 100 manufactured by MOCON. In the measurement, the side of the overcoat layer 4 (the gas barrier layer 3 in Comparative Example 1) that is the innermost layer of the paper container is in an oxygen saturated state, and the polyolefin resin layer 1a side that is the innermost layer of the paper container is saturated with nitrogen. Went as a state. The measurement was performed 5 times, and the arithmetic average was defined as oxygen permeability.

As can be seen from Table 1, Examples 1 to 4 oxygen while permeability is excellent below the gas barrier ^{20cc / m 2 · day · atm} , Comparative Example 1 is the degree of oxygen permeation is 34cc / m ² · It was inferior to day · atm and gas barrier property.

It is a schematic cross section of the laminated body which concerns on embodiment. It is a model top view of the blank sheet for gable top type paper containers formed by processing the layered product concerning an embodiment. It is a perspective view of the gable top type paper container formed by processing the blank sheet shown in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1a, 1b Polyolefin-type resin layer, 2 Paper base material layer, 3 Gas barrier layer, 4 Overcoat layer, 5 Ruled line, 6 Body sticking heat seal part, 7 Blank sheet for paper containers, 8 Gable top type paper containers.

Claims (5)

  A laminate in which a polyolefin resin layer, a paper substrate layer, a polyolefin resin layer, a gas barrier layer containing a gas barrier resin and an inorganic layered compound, and an overcoat layer containing an alkyd resin and a urethane resin are laminated in this order. .   2. The laminate according to claim 1, wherein a mass ratio of the gas barrier resin to the inorganic layered compound is 30:70 to 70:30.   The laminate according to claim 1 or 2, wherein a mass ratio of the alkyd resin to the urethane resin is 4: 1 to 1: 1.   A paper container obtained by processing the laminate according to any one of claims 1 to 3 so that the overcoat layer is an outer surface.   A process of forming a polyolefin resin layer by extrusion coating a polyolefin resin on both sides of a paper substrate, and applying a gas barrier composition containing a gas barrier resin and an inorganic layered compound to one surface of the polyolefin resin layer The manufacturing method of the laminated body characterized by including the process of forming a gas barrier layer, and the process of apply | coating the overcoat composition containing an alkyd resin and a urethane resin on a gas barrier layer, and forming an overcoat layer.

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