JP2624038B2 - Manufacturing method of material for liquid container - Google Patents

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 material for a liquid container, and more particularly, to a method for producing a material for a liquid container which is mainly made of paper and does not contain a metal foil and has a high gas barrier property.

[0002]

2. Description of the Related Art Conventionally, a liquid container material mainly composed of paper is made of a paper base material made of a laminate of paper and polyethylene resin, and is provided with water resistance (waterproofness) on the side in contact with the contents and the material. It has a polyethylene resin layer (sealant layer) for imparting thermal adhesiveness to the surface, and a polyethylene terephthalate film for shape retention is used. Further, it prevents oxidation deterioration of the contents. Laminated aluminum foil of about 9 μm is widely used as a gas barrier layer.

[0003] Since the above-mentioned liquid container uses a plastic film, it is difficult to reuse it industrially after it is used. Therefore, the liquid container is generally incinerated. When aluminum foil is used as the barrier layer, there is a problem that incineration is difficult. For this reason, in some European countries, the use of liquid paper containers using metal foil is regulated.

[0004] In addition, there has been a problem attributable to the use of metal foils, in which microwave heating desired in some cases is not possible in relation to contents.

It has been proposed to use a resin film having excellent oxygen barrier properties, such as an ethylene-vinyl alcohol copolymer or polyvinylidene chloride, instead of using a metal foil as a gas barrier layer. Resin films have remarkably inferior oxygen barrier properties as compared with aluminum foil, and have high moisture permeability. It is difficult to obtain an oxygen barrier property and a moisture-proof property equivalent to those of a metal foil using this film, and the thickness (30 μm) of a practical level is difficult.
m) or less, sufficient oxygen barrier properties and moisture-proof properties cannot be obtained.

As a technique for satisfying gas barrier properties without using a metal foil, Japanese Utility Model Application Laid-Open No. 1-96879 has been proposed.
A gazette is known. Here, a technique is disclosed in which a microwave-permeable sheet mainly composed of a plastic film provided with a silicon oxide thin film layer is used instead of a metal foil as a paper base material for a liquid container. According to this technique, sufficient oxygen barrier properties and moisture resistance can be obtained without using a metal foil.

The following is a comparison of oxygen barrier properties of aluminum foil, ethylene-vinyl alcohol copolymer, polyvinylidene chloride, and silicon oxide.

[0008]

[Table 1]

[0009]

Therefore, if the above techniques are combined and a silicon oxide thin film is used as a layer structure for a liquid container material, an excellent liquid container can be obtained which has solved the problems inherent in metal foil. .

In the production of such a material for a liquid container, as a means for laminating a paper substrate or a plastic sheet and another plastic film, a plastic film is formed into a film in advance and laminated by an adhesive ( Dry laminating method), a method of laminating by applying heat to both (thermal laminating method), or melting a resin on a paper base or plastic sheet and extruding it into a film,
A method of laminating at the same time as film formation (extrusion laminating method) is known.

However, a thin film layer of an inorganic compound such as silicon oxide generally has poor flexibility. When the base sheet expands or contracts due to heat, the thin film layer of the inorganic compound cannot follow the expansion and contraction, and cracks occur. It has been found that the inherent gas barrier properties are significantly reduced.

Therefore, when manufacturing a material for a liquid container having a thin film layer of the above-mentioned inorganic compound in the layer constitution, a method of applying heat to the substrate sheet on which the thin film layer of the inorganic compound is formed cannot be adopted as a laminating means. There was a problem.

[0013] For this reason, the dry lamination method must necessarily be adopted. However, lamination using only the dry lamination method is disadvantageous not only in cost because of using a large amount of adhesive, but also in disadvantageous cost. Since the film to be laminated is produced by the inflation method, the film surface is smooth, and the workability is inferior due to blocking during the winding operation during the production process. Since the surface of the liquid container blank sheet is also smooth, the blank sheets are blocked from each other, and there is a disadvantage that automatic supply to the assembling work in a box shape is not performed stably.

Therefore, the present invention overcomes the problems of the dry laminating method which does not cause cracking of the inorganic compound when producing a liquid container material having a thin film layer of an inorganic compound in the layer structure. It is another object of the present invention to provide a material for a liquid container having excellent gas barrier properties.

[0015]

That is, the present invention provides the following:
Extruded film of a thermo-adhesive resin, a substrate sheet on which a thin film layer of an inorganic compound is formed, and a paper substrate, when manufacturing a material for a liquid container, a step of extruding the extruded film, and extruding the extruded film. A step of cooling the resin to a temperature at which the thin film layer of the inorganic compound is not broken, and to a temperature at which the thermal adhesiveness is not lost, and extruding the cooled extruded resin onto the base sheet on which the thin film layer of the inorganic compound is formed; Manufacturing a material for a liquid container, wherein a sheet having a configuration of a first heat-adhesive resin / inorganic compound-coated base sheet is formed by a laminating step, and then the sheet and a paper base are laminated. Is the way.

Further, in producing a material for a liquid container, which comprises an extruded film of a first heat-adhesive resin, a base sheet on which a thin film layer of an inorganic compound is formed, and a paper base, the extruded film is used. Extruding step, the step of cooling the extruded resin to a temperature at which the thin film layer of the inorganic compound does not crack, and the temperature at which the thermal adhesiveness is not lost, and the thin film layer of the inorganic compound is cooled. The step of laminating on the formed base sheet, and further, the melted and extruded second thermoadhesive resin is cooled to a temperature at which the thin film layer of the inorganic compound does not crack, and does not lose the thermoadhesiveness, The step of laminating on the substrate sheet on the side opposite to the side on which the extruded film is laminated produces a sheet having the structure of the first heat-adhesive resin / inorganic compound-coated substrate sheet / second heat-adhesive resin. And, then, characterized by laminating the said sheet and the paper substrate, a manufacturing method of the material for the liquid container.

Further, in producing a material for a liquid container, the extruded film is made of a first extruded film of a thermo-adhesive resin, a base sheet on which a thin film layer of an inorganic compound is formed, and a paper base. Extruding step, the step of cooling the extruded resin to a temperature at which the thin film layer of the inorganic compound does not crack, and the temperature at which the thermal adhesiveness is not lost, and the thin film layer of the inorganic compound is cooled. The step of laminating on the formed base sheet, and further, the melted and extruded second thermoadhesive resin is cooled to a temperature at which the thin film layer of the inorganic compound does not crack, and does not lose the thermoadhesiveness, Laminating on the substrate sheet on the side opposite to the side on which the extruded film is laminated, the sheet having the structure of the first heat-adhesive resin / inorganic compound-coated base sheet / second heat-adhesive resin A material for a liquid container, characterized in that a molten third heat-adhesive resin is sandwiched between a second heat-adhesive resin of the sheet and a paper substrate, and both are laminated. It is a manufacturing method of.

[0018]

According to the first aspect of the present invention, a base sheet having a thin film layer of an inorganic compound formed thereon is laminated with a first thermo-adhesive resin cooled within a range showing thermo-adhesive properties. The influence of heat on the thin film layer is prevented, and the occurrence of cracks in the thin film layer is prevented.

In the second invention of the present invention, the second heat cooled to the limit of the thermal adhesive property is provided on the opposite side of the base sheet on which the first thermal adhesive resin is laminated according to the first invention. Since the adhesive resin is laminated, the effect of heat on the thin film layer of the inorganic compound is prevented as in the above, and the occurrence of cracks in the thin film layer is prevented. Then, the second thermo-adhesive resin is further cooled after lamination, becomes a heat insulating layer, and makes it possible to use a lamination method to which heat is applied in bonding with the paper base material.

In a third aspect of the present invention, the second sheet of the second invention is provided with a second heat-adhesive resin laminated thereon.
By directly laminating the heat-adhesive resin and the paper base material with the melt-extruded resin interposed therebetween, there is no problem in the production only by the dry lamination method, and the material for a liquid container can be produced.

In the present invention, since the film to be laminated is formed by extrusion, the smoothness of the surface depends on the surface condition of the nip roll at the time of extrusion, and a matting process can be performed so as to have an appropriate sliding property.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings.

FIG. 1 is a cross-sectional view of a material for a liquid container according to the present invention, FIGS. 2 to 4 are explanatory views showing respective steps of a method for producing a material for a liquid container of the present invention, and FIGS. It is a top view showing an example of a blank sheet for manufacturing the liquid container concerning the present invention.

As shown in FIG. 1, the material for a liquid container according to the present invention comprises at least a paper substrate 1 and a thin film layer 2 of an inorganic compound.
2 is a laminate including a base sheet 2 on which an extruded film of the first heat-adhesive resin 3 is formed.

The paper base material 1 is necessary for forming a container shape on paper 11 such as bleached kraft paper having a basis weight of about 200 to 500 g / m ² , which is conventionally used for this kind of container material. A material comprising a sealing layer 12 made of a polyolefin resin for imparting a good sealing property can be used. The seal layer 12 can be formed by laminating a polyolefin resin having a thickness of about 17 to 25 μm on the paper 11 by an appropriate method.

The base sheet 2 is formed on a base film 21 made of a heat-resistant film such as polyethylene terephthalate, stretched nylon, stretched ethylene-vinyl alcohol copolymer or the like, and a gas barrier such as silicon oxide, magnesium oxide or the like. Inorganic Compound Thin Film Layer 22
Is formed by a method such as vacuum evaporation, plasma evaporation, sputtering, or ion plating. In particular, a thin film formed by vacuum deposition of silicon oxide is easy to manufacture and advantageous in cost.

The thickness of the base film 21 should be about 6 to 20 μm in consideration of the suitability for handling in the step of forming the inorganic compound thin film layer 22 and the subsequent processing steps. preferable.

The thickness of the inorganic compound thin film layer 22 is as follows when silicon oxide is used as the inorganic compound.
At least 500 °, preferably at least 600 °.

If the thickness of the thin film layer 22 is less than 500 °, sufficient gas barrier properties may not be obtained.
On the other hand, if the thickness is more than 2000 °, cracks in the thin film layer will be remarkably generated in a later step, and this is not practical.

As the first heat-adhesive resin 3, a resin having a heat-adhesive property such as low-density polyethylene can be used.

According to the present invention, the extruded film is extruded, cooled to an appropriate temperature, and placed on the base sheet 2 on which the inorganic compound thin film layer 22 is formed by utilizing the thermal adhesiveness of the extruded film. Laminated and integrated.

That is, as shown in FIG. 2, the first thermo-adhesive resin 3 is extruded from an extrusion die 61 and is cooled by a cooling means such as a chill roll 71 at a temperature at which the inorganic compound thin film layer 22 is not broken, and Then, the substrate is cooled to a temperature at which the thermal adhesiveness is not lost. Here, if necessary, the surface of the extruded film of the first heat-adhesive resin 3 may be subjected to a treatment for enhancing the adhesion to the base sheet 2, for example, a corona discharge treatment. The corona discharge treatment uses a well-known corona discharge treatment device 8 and may be the same treatment as that in the related art. If necessary, an adhesive anchor coat layer (not shown) may be formed on the laminated surface of the base sheet 2.

The upper limit of the cooling temperature of the extruded first thermo-adhesive resin 3 is limited to the material of the base film 21,
The thickness differs depending on the type of the inorganic compound and the thickness of the thin film layer 22, and the lower limit is further determined by the material of the first heat-adhesive resin 3, but may be in the range of 20 to 50 ° C. preferable.

If the temperature is higher than 90 ° C., there is a high possibility that cracks will occur in the inorganic compound thin film layer 22.
When the temperature is lower than 15 ° C., the adhesive strength between the first heat-adhesive resin 3 and the base sheet 2 becomes insufficient, and the first heat-adhesive resin 3 is easily peeled off and cannot be used as a packaging material.

The extruded film of the first thermo-adhesive resin 3 is laminated on the base sheet 2 on the thin film layer 22 side.
Any side of the base film 21 may be used.

The obtained sheet can be laminated on the paper substrate 1 by a method that does not apply heat, such as a dry lamination method.

Here, the second invention of the present invention relates to a method of forming a second heat-adhesive resin on the base sheet 2 on the side opposite to the side on which the extruded film of the first heat-adhesive resin 3 is laminated. The resin 4 is cooled to a temperature at which the inorganic compound thin film layer 22 does not crack and does not lose its thermal adhesiveness, and the non-adsorbent resin / first thermal adhesive resin / inorganic compound-coated base sheet / second resin A sheet having the structure of the heat-adhesive resin described above.

That is, as described above, laminating the sheet composed of the base sheet 2 and the co-extruded film 3 and the paper substrate 1 by the dry lamination method has the problems of slipperiness and cost as described above. It still exists. Therefore, it is desirable that the second thermo-adhesive resin 4 be cooled to a predetermined temperature and directly laminated on the base sheet 2.

The second heat-adhesive resin 4 is laminated by extruding the second heat-adhesive resin 4 from the extrusion die 62 in the same manner as the above-described lamination of the first heat-adhesive resin 3. This is cooled by a cooling means such as a chill roll 72 to a temperature at which the thin film layer 22 of the inorganic compound is not broken and at which the thermal adhesiveness is not lost, and then the first thermal adhesive resin of the base sheet 2 is cooled. The extruded film No. 3 is laminated on the side opposite to the side on which the extruded films are laminated, and is pressed and laminated (see FIG. 3). As described above, corona discharge treatment and an adhesive anchor coat layer can be applied as necessary.

As the second thermo-adhesive resin 4, a resin similar to the above-mentioned first thermo-adhesive resin 3 can be used.

As described above, in the sheet on which the second heat-adhesive resin 4 is laminated, the second heat-adhesive resin 4 functions as a heat insulating layer, so that the base sheet 2 no longer receives extreme heat. Absent. Therefore, a known laminating means using heat can be applied to the above-mentioned bonding between the sheet and the paper substrate 1.

In order for the second thermo-adhesive resin 4 to sufficiently function as a heat insulating layer, it is necessary that the second thermo-adhesive resin 4
Is preferably 15 μm or more.

The order of laminating the extruded film of the first thermo-adhesive resin 3 and the second thermo-adhesive resin 4 on the base sheet 2 is not particularly limited.

The above-described lamination of the sheet on which the second thermo-adhesive resin 4 is laminated and the paper substrate 1 may utilize heat as described above. The third extruded third heat-adhesive resin 5 is sandwiched between the paper substrate 1 and the sheet having the constitution of / inorganic compound-coated base sheet 2 / second heat-adhesive resin 4, and both are pressed. They can be stacked (see FIG. 4).

The third thermal adhesive resin 5 is not particularly limited as long as it has adhesiveness to both the second thermal adhesive resin 4 and the paper substrate 1. It is preferable to use the same resin because the adhesiveness can be improved.
It is sufficient that the thickness of the third thermo-adhesive resin 5 is 10 μm.

Note that a heat-adhesive resin such as polyethylene is provided on the side of the paper substrate 1 which is in contact with the second heat-adhesive resin 4, and the second heat-adhesive resin 4 and the heat-adhesive resin are combined. A so-called thermal lamination method of heating and laminating is also conceivable, but heat cannot be applied from the base sheet 2 side (a large amount of heat is applied to the base sheet 2 and cracks occur in the thin film layer). Will be put on paper 1
Because of the high thermal insulation of (1), the thermal efficiency is extremely poor, and this method is difficult to adopt.

The material for a liquid container of the present invention obtained as described above is punched into a blank 9 having a shape as shown in FIGS. 5 and 6, for example, and is a rectangular container or a block having a roof-type top. It can be assembled into a container in a shape. Further, it is also possible to form the obtained material into a cylindrical shape by forming the obtained material into a cylindrical shape and attaching appropriate lid members to the upper and lower openings.

The obtained container can be filled with various kinds of beverages as in the past, but the liquid container according to the present invention is particularly suitable for juices, sakes, spirits and teas in which the aroma of the contents needs to be valued. When used for filling contents such as coffee, other soft drinks, or bath agents, the effect is remarkable.

An embodiment of the present invention will be described below.

A bleached kraft paper having a basis weight of 320 g / m ² (SIE, manufactured by Shin Fuji Paper Co., Ltd., trade name: SIE) has a thickness of 20 μm on one side.
m of polyethylene film was laminated to prepare a paper substrate.

Separately from this, on one side of a biaxially stretched polyethylene terephthalate film (manufactured by Teijin Limited, trade name: NS) having a thickness of 12 μm, silicon oxide was provided as a thin film layer of an inorganic compound to a thickness of 1500 °, A base sheet was prepared.

Next, on the silicon oxide surface of the base sheet,
A polyethylene resin (trade name: M401PC, manufactured by Mitsui Petrochemical Industry Co., Ltd.) was extruded from an extrusion die to a thickness of 30 μm, cooled by a chill roll cooled to about 5 ° C., and subjected to corona discharge treatment (degree of treatment: 43 dyne wetness index). / Cm or more (according to JIS K6768))
They were pressed and laminated. At this time, the temperature of the extruded polyethylene resin was about 35 ° C. immediately before lamination.

Next, a polyethylene resin (trade name: M401PC, manufactured by Mitsui Petrochemical Industry Co., Ltd.) was extruded from an extrusion die, and the co-extruded resin (resin temperature: about 28)
0 ° C.), cooled with a chill roll cooled to about 5 ° C., and subjected to a corona discharge treatment (treatment degree: 43 dyne / cm or more (according to JIS K6768)). The sheets were laminated, pressed and laminated to form a sheet having a structure of first polyethylene / polyethylene terephthalate / silicon oxide thin film layer / second polyethylene.

Next, the second polyethylene of the above sheet and the paper base paper were faced to each other.
m of polyethylene resin was extruded from an extrusion die, and both were pressed, cooled and laminated to obtain a liquid container material of the present invention.

When the oxygen permeability and the moisture permeability of the obtained liquid container material were measured, the oxygen permeability was found to be 1 to 3 cc / m ^2.
・ 24hr ・ atm, moisture permeability 0.5 ~ 3g / m ²・ 2
It was 4 hr · atm (40 ° C., 90% RH) and had sufficient gas barrier properties.

For comparison, a resin was prepared in the same manner as described above except that the extruded resin was not cooled, and the gas barrier property was evaluated. The oxygen permeability was 10 cc / m ^2.
・ 24hr ・ atm, moisture permeability is 10g / m ²・ 24hr
Atm (40 ° C., 90% RH), and sufficient gas barrier properties could not be obtained. When this was decomposed and the state of the inorganic compound thin film layer was observed with a microscope, countless fine cracks were generated in the thin film layer.

When the material for a liquid container of the present invention and the material for a liquid container using a conventionally known aluminum foil as a gas barrier layer were respectively incinerated, the material of the present invention was completely burned and toxic gas was removed. Although it did not occur, the conventional one using aluminum foil had aluminum foil remaining without burning, and it was clear that the present invention was advantageous.

[0058]

As described above, according to the present invention, there is provided an excellent gas barrier property without causing cracks in a thin film layer of an inorganic compound, and an excellent solution to the problem of using a metal foil. A material for a liquid container can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a liquid container material according to the present invention.

FIG. 2 is an explanatory view showing a step of laminating a first extruded film of a thermo-adhesive resin in the method for producing a material for a liquid container of the present invention.

FIG. 3 is an explanatory view showing a step of laminating a second thermo-adhesive resin in the method for producing a material for a liquid container of the present invention.

FIG. 4 shows a method for producing a material for a liquid container of the present invention.
It is explanatory drawing which shows the lamination process of a lamination sheet and a paper base material using the 3rd thermoadhesive resin.

FIG. 5 is a plan view showing an example of a blank sheet for manufacturing the liquid container according to the present invention.

FIG. 6 is a plan view showing another example of a blank sheet for manufacturing the liquid container according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Paper base material 11 ... Paper 2 ... Base sheet 21 ... Base film 22 ... Inorganic compound thin film layer 3 ... 1st thermal adhesive resin 4 ... 2nd thermal adhesive resin 5 ... 3rd Extrusion dies 71, 72 ... Chill roll 9 ... Blank sheet

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location B32B 27/10 B32B 27/10 B65D 65/40 B65D 65 / 40F // B29L 9:00

Claims (3)

(57) [Claims] 1. A method for manufacturing a liquid container material comprising: a first heat-adhesive resin extruded film; a base sheet on which a thin film layer of an inorganic compound is formed; and a paper base. Extruding step, the step of cooling the extruded resin to a temperature at which the thin film layer of the inorganic compound does not crack, and the temperature at which the thermal adhesiveness is not lost, and the thin film layer of the inorganic compound is cooled. The step of laminating on the formed base sheet produces a sheet having the structure of the first heat-adhesive resin / inorganic compound-coated base sheet, and then laminating the sheet and the paper base. , A method for producing a material for a liquid container. 2. A method for manufacturing a material for a liquid container, comprising: an extruded film of a first heat-adhesive resin; a base sheet on which a thin film layer of an inorganic compound is formed; Extruding step, the step of cooling the extruded resin to a temperature at which the thin film layer of the inorganic compound does not crack, and the temperature at which the thermal adhesiveness is not lost, and the thin film layer of the inorganic compound is cooled. The step of laminating on the formed base sheet, and further, the melted and extruded second thermoadhesive resin is cooled to a temperature at which the thin film layer of the inorganic compound does not crack, and does not lose the thermoadhesiveness,
Laminating on the substrate sheet on the side opposite to the side on which the extruded film is laminated, the first heat-adhesive resin /
A method for producing a material for a liquid container, comprising: preparing a sheet having a constitution of an inorganic compound-coated substrate sheet / a second thermoadhesive resin, and then laminating the sheet and a paper substrate. 3. A liquid container material comprising a first extruded film of a thermo-adhesive resin, a base sheet on which a thin film layer of an inorganic compound is formed, and a paper base, wherein the extruded film is made of a material. Extruding step, the step of cooling the extruded resin to a temperature at which the thin film layer of the inorganic compound does not crack, and the temperature at which the thermal adhesiveness is not lost, and the thin film layer of the inorganic compound is cooled. The step of laminating on the formed base sheet, and further, the melted and extruded second thermoadhesive resin is cooled to a temperature at which the thin film layer of the inorganic compound does not crack, and does not lose the thermoadhesiveness,
Laminating on the substrate sheet on the side opposite to the side on which the extruded film is laminated, the first heat-adhesive resin /
A sheet having a composition of inorganic compound-coated base sheet / second heat-adhesive resin is prepared, and then a third heat-adhesive resin is melted between the second heat-adhesive resin of the sheet and the paper substrate. A method for producing a material for a liquid container, comprising sandwiching a resin and laminating the two.