JP3312563B2 - Liquid packaging paper packaging material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a packaging material for liquid packaging paper used as a packaging material for box-shaped liquid packaging containers mainly made of paper.

[0002]

2. Description of the Related Art A conventional packaging material for liquid packaging paper used as a packaging material for a box-shaped liquid packaging container mainly made of paper includes:
As shown in FIG. 2, a polyethylene resin layer 2 is laminated on one side of a paper base material layer 1 as a main body, and an aluminum foil layer 4 is laminated on the other side with an adhesive resin layer 3 interposed therebetween. Is a sheet-like packaging material in which a polyethylene terephthalate resin layer 5 and a polyethylene resin layer 6 are laminated.

[0003] The polyethylene resin layer 2 of the above packaging material is the outermost resin layer, and the polyethylene resin layer 6 is a resin layer in contact with the contents (liquid).

When a liquid packaging paper container (carton container) of a goebel top type or a flat top type is made from the above-mentioned sheet-like packaging material, the polyethylene resin layer 2 of the packaging material is placed on the outer side, and the polyethylene resin layer is formed. The packaging material is bent into a rectangular prism through predetermined parallel vertical folds, with the polyethylene resin layer 2 on the outer surface and the polyethylene resin layer 6 on the inner surface at both ends of the packaging material. And, if necessary, of the two ends of the superimposed packaging material, the inner end side of the container is superimposed and the inner side is cut thinly and folded over to the inner side to form edge protection. hand,
The side body of the container is formed by joining and sealing by heat fusion.

[0005] Thereafter, a bottom-forming flap formed at a lower portion of the rectangular tube-shaped side body through a predetermined fold is bent, and the overlapped portion of the flaps is joined and sealed by heat fusion to seal the container. The bottom (bottom of the container) is formed and the contents are filled.

[0006] Thereafter, the upper forming flap formed on the upper side of the rectangular cylindrical side body through a predetermined fold is bent, and the overlapped portion of the flaps is joined and sealed by heat fusion to seal the container. Form the top (top of the container)
A liquid packaging container in which the liquid is hermetically sealed is formed.

[0007] As described above, the superposed surfaces of the outermost polyethylene resin layer 2 and the innermost polyethylene resin layer 6 of the liquid packaging container manufactured by heat fusion are formed of the same resin material. Therefore, a good adhesion seal can be obtained.

[0008]

By the way, in the case of a packaging material using a resin having a low melt flow rate (MFR value; melt index) as the innermost polyethylene resin layer 6 of the above packaging material, the heat melting point Because the flow of the resin in is not good, there is a tendency that it is difficult to accumulate resin in the butted portion of the joined top and bottom (the end of the overlapping area), and when filling with liquid, The liquid leaks easily from the joint seal portion. In addition, there is a problem that the allowable range of the sealing temperature condition of the bonding seal is narrow, and it is difficult to perform the bonding sealing operation by heat fusion.

On the other hand, a melt flow rate value (MFR value;
In the case of a packaging material using a resin having a high melt index), although the flow of the resin at the time of hot melting is good, the bonding strength of the top and bottom parts that have been bonded and sealed tends to be weak, and The innermost layer of the polyethylene resin layer 6 adsorbs a small amount of the content of the filled content, which may impair the taste of the content.

An object of the present invention is to eliminate the above-mentioned disadvantages in a liquid packaging paper packaging material used as a box packaging material for a box-shaped liquid packaging container mainly made of paper.

According to the present invention, an outer polyethylene resin layer 2 is provided on one side of a paper base layer 1 as a main component, and an adhesive resin layer 3 is provided on the other side.
In the liquid packaging paper packaging material in which the aluminum resin layer 5 is laminated on the aluminum foil layer 4 and the intermediate resin layer 5 and the inner layer polyethylene resin layer 6 are laminated on the aluminum foil layer 4, the inner layer polyethylene resin layer 6 The first polyethylene resin layer 7 having a high melt flow rate value M1 = 1.5 to 9.0 (g), which facilitates resin pooling at the time of joining and sealing, is sequentially provided on the intermediate resin layer 5 side without decreasing the joining sealing strength. The melt for preventing a decrease in taste due to the adsorption of components of the package contents
Melt flow rate value M2 lower than flow rate value M1
= 1.0 to 7.5 (g) , which is a two-layer structure in which a second polyethylene resin layer 8 is laminated.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The packaging material for liquid packaging paper of the present invention is
This will be described in detail below according to the embodiment shown in FIG.

As shown in FIG. 1, an outer polyethylene resin layer 2 is laminated and adhered to one surface of a paper substrate 1 such as paper or paperboard, as shown in FIG. An aluminum foil layer 4 is laminated and adhered to the other surface via an adhesive resin layer 3.

As the adhesive resin layer 3, ethylene-acrylic acid resin (EAA) and ethylene-methacrylic acid resin (EMA) exhibiting good adhesiveness to paper and metal foil.
A), an ionomer resin obtained by crosslinking EMAA with metal ions (Zn, Na), a polyethylene terephthalate resin, or the like is used.

An inner polyethylene resin layer 6 having a two-layer structure is laminated and adhered to the surface of the aluminum foil layer 4 via an intermediate resin layer 5 made of, for example, polyethylene terephthalate resin or polyethylene resin.

The inner polyethylene resin layer 6 having a two-layer structure comprises:
A first polyethylene resin layer 7 laminated and adhered to the intermediate resin layer 5 side, and a second polyethylene resin layer 8 contacting the innermost layer of the container laminated and adhered to the surface of the first polyethylene resin layer 7 It consists of.

For the first polyethylene resin layer 7, a polyethylene resin having a higher melt flow rate value M (MFR value) than that of the second polyethylene resin layer 8 is used.

Further, in the packaging material of the present invention, the first material
As the polyethylene resin layer 7 and the second polyethylene resin layer 8, it is preferable to use a low-density polyethylene resin.

In general, when the resin is melted under the same heating temperature condition, the higher the M value of the resin, the lower the viscosity and the better the flowability (flow) of the resin.
It melts in a state of high viscosity and poor fluidity.

The melt flow rate value M is defined by JIS.
It is defined by K7210 (Japanese Industrial Standards), and is represented by the following general formula: M = 600 × m / t.

The above melt flow rate value (M value) is J
Under test conditions according to IS K7210, the molten plastic was passed through a die having a length of 8 mm and an inner diameter of 2 mm.
The extrusion weight (unit: g) of the molten plastic when extruded for a minute (600 seconds).

Here, m is the extrusion weight (unit; g) of the molten plastic when the molten plastic is extruded through a die having a length of 8 mm and an inner diameter of 2 mm under the test conditions according to JIS K7210. t is JIS K721
Extrusion elapsed time (unit: seconds) when the molten plastic was extruded through a die having a length of 8 mm and an inner diameter of 2 mm under test conditions according to 0. m / t is the extrusion speed.

In the first polyethylene resin layer 7 of the present invention, the melt flow rate value (M value) is, for example, M =
A polyethylene resin having a range of 1.5 to 9.0, preferably 4.0 to 9.0 can be selected and used, and the second polyethylene resin layer 8 has a melt flow rate value. For example, a polyethylene resin having an M value in the range of M = 1.0 to 7.5, preferably 1.0 to 5.0 can be selected and used.

However, in the present invention, the melt flow rate value is not particularly limited. For example, the M value of the first polyethylene resin layer 7 is M1 and the M value of the second polyethylene resin layer 8 is M2. In this case, the first and second polyethylene resin layers 7 and 8 may be set so that at least M1> M2.

[0025]

EXAMPLES Specific examples of the packaging material for liquid packaging paper of the present invention will be described below.

<Example 1> A paperboard having a thickness of 400 g / m ² was used as a paper substrate 1, and one side (the outer surface side of the packaging material) had a thickness of 2 g / m 2.
An outer polyethylene resin layer 2 was formed by laminating a 5 μm polyethylene resin film while heating.

Subsequently, an ethylene-methacrylate resin having a thickness of 25 μm is applied as an adhesive resin layer 3 to the other surface of the paper base material 1, and then a thickness of 7 μm is applied through the adhesive resin layer 3.
An aluminum foil layer 4 was formed by laminating a μm aluminum foil.

Subsequently, on the surface of the aluminum foil layer 4,
A polyethylene terephthalate resin film having a thickness of 12 μm was laminated while heating to form a polyethylene terephthalate resin layer 5.

Next, as the first polyethylene resin layer 7, a low density polyethylene resin film having an M value (MFR value) of M = 7, a thickness of 30 μm and a high melt flow rate, and a second polyethylene resin layer 8. As the M value (MFR
A low-density polyethylene resin film having a low melt flow rate value of M = 2 having a thickness of 30 μm and having a low melt flow rate is laminated while heating, and comprises a first polyethylene resin layer 7 and a second polyethylene resin layer 8. An inner polyethylene resin layer 6 was formed.

Next, the inner polyethylene resin layer 6 is
The first polyethylene resin layer 7 was laminated on the surface of the polyethylene terephthalate resin layer 5 on the side of the paper substrate 1 while heating, to produce a packaging material for liquid packaging paper of the present invention.

<Example 2> As the first polyethylene resin layer 7, a low-density polyethylene resin in a heat-melted state having an M value (MFR value) of M = 7 and a high melt flow rate value of 30 μm in thickness was used. The second polyethylene resin layer 8 is applied and laminated by an extruder method on the surface of a low-density polyethylene resin film having an M value (MFR value) of M = 2 and a low melt flow rate having a thickness of 30 μm and the first layer is laminated. A liquid packaging paper-made packaging material of the present invention was produced in the same manner as in Example 1 except that an inner polyethylene resin layer 6 comprising a polyethylene resin layer 7 and a second polyethylene resin layer 8 was formed.

Example 3 As the first polyethylene resin layer 7, a low-density polyethylene resin in a heat-melted state having an M value (MFR value) of M = 7 and a high melt flow rate with a thickness of 30 μm was used. The surface of the polyethylene terephthalate resin layer 5 on the side of the paper substrate 1 is applied and laminated by an extruder method, and subsequently, the second polyethylene resin layer 7 has a thickness of M = 7 (MFR value). 30
A low-density polyethylene resin in a heated and molten state having a high melt flow rate value of μm is applied to the surface of the first polyethylene resin layer 7 by an extruder method and laminated, and the first polyethylene resin layer 7 and the A packaging material for liquid packaging paper of the present invention was produced in the same manner as in Example 1 except that an inner polyethylene resin layer 6 composed of the polyethylene resin layer 8 of Example 2 was formed.

[0033]

The packaging material for liquid packaging paper according to the present invention has a melt flow rate (MF) as an inner polyethylene resin layer.
An inner polyethylene resin layer having a two-layer structure of a first polyethylene resin layer having a high R value (melt index) and a second polyethylene resin having a low R value is used, and among the inner polyethylene resin layers having the two-layer structure, packaging is performed. A second polyethylene resin layer having a low melt flow rate is used on the innermost layer side in contact with the contents.

Therefore, in the case where a liquid packaging container, such as a carton container for liquid packaging, is bonded and sealed by heat melting using the packaging material for liquid packaging paper of the present invention,
The first polyethylene resin layer having a high melt flow rate improves the flow of the molten resin at the time of heat melting, and the resin is formed at the butted portions of the joined top and bottom portions (ends of the overlap region). There is a tendency for accumulation to occur, so that when filled with liquid, it has the effect of making it difficult for liquid to leak from the joint seal part, and the allowable range in the seal temperature condition of the joint seal is widened, and Good effects such as facilitating the joining and sealing work by fusion are obtained.

On the other hand, the innermost second polyethylene resin layer having a low melt flow rate value tends to increase the bonding strength at the top and bottom portions which are bonded and sealed. This has the effect of eliminating the fear of impairing the taste of the contents by adsorbing the components of the contents.

[Brief description of the drawings]

FIG. 1 is a sectional side view illustrating a packaging material for liquid packaging paper of the present invention.

FIG. 2 is a cross-sectional side view illustrating a conventional packaging material for liquid packaging paper.

[Explanation of symbols]

1: paper base material 2: outer polyethylene resin layer (outermost layer)
3 ... adhesive resin layer 4 ... aluminum foil layer 5 ... intermediate resin layer 6 ... inner polyethylene resin layer 7 ... first polyethylene resin layer 8 ... second polyethylene resin layer (innermost layer)

Claims (2)

(57) [Claims] An aluminum foil layer is laminated on an outer polyethylene resin layer on one side of a paper base layer as a main body and an adhesive resin layer on the other side. In the packaging material made of liquid packaging paper in which the intermediate resin layer 5 and the inner polyethylene resin layer 6 are laminated, the inner polyethylene resin layer 6 is sequentially formed on the intermediate resin layer 5 side by a high melt which facilitates resin pooling at the time of joining and sealing. Flow rate value M1
= 1.5 to 9.0 (g) and the above melt flow tray for preventing a decrease in taste due to the adsorption of the components of the package contents without lowering the bonding strength with the first polyethylene resin layer 7.
Lower melt flow than the preparative value M1 rate value M2 = 1.0 to
A packaging material made of liquid packaging paper, which has a two-layer structure in which a second polyethylene resin layer 8 having a thickness of 7.5 (g) is laminated. 2. The packaging material according to claim 1, wherein the first polyethylene resin layer 7 and the second polyethylene resin layer 8 are made of low-density polyethylene.