JP6146086B2 - Paper base sheet for half clear pack and half clear pack - Google Patents

Description

  The present invention provides a paper base sheet excellent in adhesion between paper and resin and oil resistance, and using this sheet, a half clear pack excellent in heat sealability and curl resistance with a transparent film The purpose is to provide.

In recent years, as a packaging material used for over-the-counter sales of food side dishes such as croquettes and fried chicken, a transparent film is layered on a paper base sheet instead of the traditional polystyrene food pack. Half-clear packs that are sealed by heat-sealing the sides and opened in a bag shape with one side open are beginning to be used.
The half clear pack has the advantage that the front side is transparent film, so that the contents can be clearly seen, it is lightweight, and the back side is made of paper, so it can be printed, and also helps to reduce dust.

Conventionally, as a material of such a half clear pack, a heat-sealable OPP is used as a transparent film on the front side, and a paper itself or a resin that does not allow oil to pass through (oil resistance) as a paper base sheet on the back side. A paper base sheet having a layer laminated to paper is used.
As heat-sealable OPP used as a transparent film, a heat-sealable layer containing a low-melting resin such as random polypropylene or ethylene / α-olefin copolymer is laminated on a base layer made of homopolypropylene, and biaxial A stretched one is known.

However, in the half clear pack, since three sides are heat-sealed and one side is opened, a curling phenomenon caused by shrinkage of the heat-sealed portion is caused, and the half-clear pack is deformed and becomes bulky when a bag is stocked. There was a problem.
Further, since the compatibility between the oil-resistant paper base sheet and the heat-sealable OPP, which are generally used in the past, is poor, the heat-sealing performance is weak and there is a problem that it is easily peeled off during use.

As a paper base sheet obtained by laminating and laminating a resin on a paper base material, a polypropylene resin having high pinhole resistance and low oil permeability is used in order to impart oil resistance to paper. In this connection, a multilayer film composed of a polyethylene polymer and a propylene polymer excellent in adhesiveness with a paper base material is provided. (Patent Documents 1 and 2) Adhesion between a paper base material and a resin There is room for improvement.

Therefore, as a result of various studies on the composition of the laminate resin used in the paper base sheet constituting the half clear pack, the present inventors have adopted a specific resin composition, and the paper base sheet and the transparent film A half-clear pack paper base sheet that guarantees heat sealability, has good adhesion between the paper base and resin, does not impair the oil resistance of the paper base sheet, and does not cause curl even when three-way heat-sealed. The present invention has been found and obtained.

JP 2010-5851 JP2011-20372A

The object of the present invention is to solve the above-mentioned conventional problems, ensure the adhesion between the paper substrate and the resin, provide a paper substrate sheet having oil resistance, and heat sealability with a transparent film, The object is to provide a half clear pack that does not cause a curl phenomenon.

As a result of intensive studies to achieve the above object, the present inventors have adopted a specific resin composition, which has good adhesiveness to the resin that is laminated on the paper substrate, and improves the oil resistance of the paper substrate sheet. The present inventors have found that a half clear pack paper base sheet having good heat sealability between the paper base sheet and the transparent film and not causing a curl phenomenon can be obtained even during three-way heat sealing without damaging.

That is, according to the first invention, the paper base material sheet 2 in which at least the adhesive resin layer 2c is laminated between the paper base material layer 2a and the surface resin layer 2b, the surface resin layer 2b is
(A) 55 wt% or more and 95 wt% or less of polypropylene resin or polyethylene resin having a melting point of 100 ° C or higher,
as well as,
(B) A polyethylene resin having a density of 0.920 g / cm ³ or less and a melting point of 110 ° C. or less is 5 wt% or more and 45 wt% or less,
The adhesive resin layer 2c
(C) 55 wt% or more and 95 wt% or less of polypropylene resin or polyethylene resin having a melting point of 100 ° C. or higher,
as well as,
(D) A polyethylene resin having a density of 0.920 g / cm ³ or less and a melting point of 110 ° C. or less is 5 wt% or more and 45 wt% or less,
Provided is a paper base sheet characterized by containing.

According to the second invention, in the first invention, the surface resin layer 2c is
(C) 55 wt% or more and 95 wt% or less of a polyethylene resin having a melting point of 100 ° C. or higher,
as well as,
(D ′) a polyethylene resin having a density of 0.920 g / cm ³ or less and a melting point of 110 ° C. or less of 5% by weight to 45% by weight;
A paper base sheet is provided according to claim 1.

Further, according to the third invention, in the first or second invention, the surface resin layer 2b is
(A ′) 55 wt% or more and 95 wt% or less of polypropylene resin,
as well as,
(B) A polyethylene resin having a density of 0.920 g / cm ³ or less and a melting point of 110 ° C. or less is 5 wt% or more and 45 wt% or less,
It contains, The paper base material sheet of Claim 1 or 2 characterized by the above-mentioned is provided.

According to a fourth invention, in any one of the first to third inventions, the polyethylene resin according to (A) or (D) having a density of 0.920 g / cm ³ or less and a melting point of 110 ° C. or less. Is produced from a metallocene catalyst. A paper base sheet is provided.

Further, according to a fifth invention, in any one of the first to fourth inventions, a transparent biaxially stretched polypropylene film 1 provided with a heat-sealable layer 1b on the outermost surface of the polypropylene-based substrate 1a is used as a surface resin. Provided is a paper base sheet characterized in that it is used in a half-clear pack formed by stacking layers 2b and heat-sealable layer 1b so that they face each other and heat-sealing the three sides to form a bag Is done.

According to a sixth invention, according to any one of the first to fifth inventions, a transparent biaxially stretched polypropylene film 1 having a heat-sealable layer 1b provided on the outermost surface of a polypropylene-based substrate 1a, A half clear pack is provided in which the resin layer 2b and the heat-sealable layer 1b are overlapped so as to face each other, and the three sides are heat-sealed to form a bag shape.

According to the present invention, it is possible to provide a paper base sheet having oil resistance while ensuring adhesion between the paper base and the resin. By using this paper base sheet, it is possible to provide a half clear pack that has good heat sealability with a transparent film and does not cause a curl phenomenon.

Sectional drawing which shows the layer structure of the half clear pack which concerns on this invention The figure which shows the half clear pack which concerns on this invention

Hereinafter, the present invention will be described in detail.

1. 1 is a cross-sectional view of a paper base sheet and a half clear pack according to the present invention. The paper base sheet of the present invention comprises a paper base layer 2a, an adhesive resin layer 2b made of a specific resin composition, and a surface resin 2c mainly composed of polypropylene.
The transparent film 1 is a transparent biaxially stretched polypropylene film that is biaxially stretched by providing a heat-weldable heat-sealable layer 1b on the surface of the polypropylene-based substrate 1a.
FIG. 2 shows a half clear pack according to the present invention. The half clear pack of the present invention comprises the paper base sheet 2 and the transparent film 1 so that the back surface is the paper base sheet 2 and the front surface is the transparent film 1, and the three end portions (3 Side) is heat sealed (part 3).

2. Paper base sheet (1) Surface resin layer 2b
As a resin composition constituting the surface resin layer 2b which is the outermost surface of the paper base sheet 2 in the present invention,
(A) 55 wt% or more and 95 wt% or less of polypropylene resin or polyethylene resin having a melting point of 100 ° C or higher,
as well as,
(B) A polyethylene resin having a density of 0.920 g / cm ³ or less and a melting point of 110 ° C. or less is 5 wt% or more and 45 wt% or less,
It is characterized by containing.

Component (A) The component (A) is a polypropylene resin or a polyethylene resin having a melting point of 100 ° C. or higher, and is a component that imparts oil-impervious properties (oil resistance) to the paper base sheet.
The melting point in the present invention is a peak top temperature (Tm) on the highest temperature side in a DSC melting curve, which is measured using a differential scanning calorimeter in accordance with JIS-K7121.

Examples of the polypropylene resin used in the present invention include those containing 20 to 100% by weight of propylene units, and need to contain 0 to 20% by weight of ethylene / units and / or butene units.
Here, propylene units and ethylene and / or butene units are values measured by Fourier transform infrared analysis.
In the polypropylene resin used in the present invention, comonomer components other than ethylene and butene may be copolymerized with propylene. Examples of the comonomer include an α-olefin having 5 to 20 carbon atoms. Examples of the α-olefin having 5 to 20 carbon atoms include 1-hexene and 1-octene. One or more α-olefins copolymerized with propylene may be used. The comonomer copolymerized with propylene is preferably ethylene or 1-butene, more preferably ethylene.
That is, the polypropylene resin is a propylene homopolymer, a random copolymer of propylene and ethylene and / or butene, and specifically, a propylene homopolymer, a propylene / ethylene random copolymer, and a propylene butene random copolymer. Examples thereof include a polymer and a propylene / ethylene / butene ternary random copolymer. Of these, propylene / ethylene random copolymers are preferred.
Use of a polypropylene resin is preferable for improving the oil resistance of the half clear pack. As such a polypropylene resin, one having a melting point in the range of 120 ° C. to 180 ° C. is usually used. It is difficult to produce a polypropylene resin having a melting point exceeding 180 ° C., and if it is less than 120 ° C., the pinhole resistance is inferior, and the oil resistance is impaired.

As the polyethylene resin having a melting point of 100 ° C. or higher used as the component (A), a resin having a melting point of 100 ° C. or higher can be selected from ethylene homopolymers or ethylene / α-olefin copolymers. . When the melting point of polyethylene is less than 100 ° C., the heat resistance and pinhole resistance are inferior, so that the oil resistance is impaired.
Examples of the ethylene homopolymer or ethylene / α-olefin copolymer include branched low density polyethylene (LDPE) and linear low density polyethylene (L-LDPE) obtained by a high-pressure method, and among them, metallocene catalysts. Known metallocene polyethylene (m-LLDPE), high-density polyethylene (HDPE), and the like are known, and such ordinary polyethylene resins generally have a melting point of 100 ° C. or higher. Examples include high pressure low density polyethylene or linear polyethylene low density polyethylene, preferably linear polyethylene low density polyethylene obtained from a metallocene catalyst. An example of such a polyethylene resin is the Harmolex series made by Nippon Polyethylene.

The melt flow rate (MFR), which is an index of the molecular weight of the polyolefin resin, is not particularly limited, but it is necessary that kneading, laminating and the like be performed stably.
The MFR of the polypropylene resin used for the component (A) is 1 to 100 g / 10 minutes, preferably 5 to 75 g / 10 minutes, and more preferably 10 to 50 g / 10 minutes. If the MFR exceeds 100 g / 10 min, the heat resistance and pinhole property are inferior, so that the oil resistance is impaired. When the MFR is less than 1 g / 10 min, the extrusion load increases and the processability is inferior.
The MFR of the polyethylene resin used for the component (A) is 1 to 50 g / 10 minutes, preferably 2 to 35 g / 10 minutes, and more preferably 5 to 25 g / 10 minutes. If the MFR exceeds 50 g / 10 min, the heat resistance and pinhole property are poor, and the oil resistance is impaired. When the MFR is less than 1 g / 10 min, the extrusion load increases and the processability is inferior.
Here, MFR is a value measured according to “Testing method for melt flow rate (MFR) and melt volume flow rate (MVR) of plastic-thermoplastic plastic” in JIS K7210-1999.

(B) Component The polyethylene resin having a density of 0.920 g / cm ³ or less and a melting point of less than 110 ° C. used as the component (B) of the present invention is called a so-called ultra-low density polyethylene or polyethylene elastomer among polyethylene resins. Polyethylene resin belonging to a special grade having an extremely low melting point, preferably an ethylene / α-olefin copolymer. Here, the density is measured according to JIS K-7112.
A polyethylene resin obtained from a metallocene catalyst is preferred from the viewpoint that it has a low molecular weight and does not contain a low crystalline component, has a small solvent extraction component, and has a low odor and is a clean polyethylene material.
For example, a resin having a density of 0.920 g / cm ³ or less and a melting point of 110 ° C. or less can be selected and used from Kernel (registered trademark) series manufactured by Japan Polyethylene Corporation.
The density is preferably 0.860 g / cm ³ or more and 0.920 g / cm ³ or less, and more preferably 0.880 g / cm ³ or more and 0.910 g / cm ³ or less. When the density exceeds 0.920, the adhesion of the adhesive resin layer 2c is deteriorated, and it is extremely difficult to produce a polyethylene resin having a density of less than 0.860.

The melt flow rate (MFR) of the polyethylene resin used as the component (B) is 2 to 100 g / 10 minutes, and preferably 5 to 50 g / 10 minutes. When the MFR exceeds 100 g / 10 min, it is difficult to handle the resin due to stickiness, and when the MFR is less than 2 g / 10 min, the average molecular weight is large, so stable operation is performed during kneading or laminating. I can't.

In addition, it is also possible to use 2 or more types of (A) component and / or 2 or more types of (B) component for the resin layer 2b, and also the 3rd resin component is resin of the surface resin layer 2b. In addition, it can be used within a range not exceeding the main component of the component.

The mixing ratio of the component (A) and the component (B) in the resin layer 2b is (A) 55 to 95% by weight and (B) 45 to 45% with respect to 100% by weight of the total amount of (A) and (B). 5% by weight, preferably (A) 65-95% by weight and (B) 35-5% by weight, more preferably (A) 75-95% by weight and (B) 25-5% by weight.
When the mixing ratio of component (A) is less than 55% by weight, the heat resistance and pinhole resistance are inferior, so that the oil resistance is impaired. On the other hand, when the mixing ratio of the component (A) exceeds 95% by weight, both the sealing strength to the transparent film 1 and the adhesive strength to the adhesive resin layer 2c are impaired.

(2) Adhesive resin layer 2c
The paper base sheet 2 of the present invention needs to have a configuration of three or more layers in which at least the adhesive resin layer 2c is added between the two layers of the paper base layer 2a and the surface resin layer 2b.
In that case, as a resin composition used for the intermediate resin layer 2c,
(C) 55 wt% or more and 95 wt% or less of polypropylene resin or polyethylene resin having a melting point of 100 ° C. or more, and (D) 5 wt% or more of polyethylene resin having a density of 0.920 g / cm ³ or less and a melting point of less than 110 ° C. It contains 45 wt% or less.

Component (C) The component (C) is the same polypropylene resin as the component (A) or a polyethylene resin having a melting point of 100 ° C. or higher. However, as the component (C), a polyethylene resin having a melting point of 100 ° C. or higher is preferable from the viewpoint of improving the adhesion between the paper base layer (2a) and the surface resin layer (2b). A linear polyethylene low density polyethylene obtained from a metallocene catalyst is preferable. An example of such a polyethylene resin is the Harmolex series made by Nippon Polyethylene.

(D) Component (D) A component is the polyethylene resin similar to (B) component.

The mixing ratio of the component (C) and the component (D) in the resin layer 2c is (C) 55 to 95% by weight and (D) 45 to 45% with respect to 100% by weight of the total amount of (C) and (D). 5% by weight, preferably (C) 65 to 95% by weight and (D) 35 to 5% by weight, more preferably (C) 75 to 95% by weight and (D) 25 to 5% by weight.
If the mixing ratio of the component (C) is less than 55% by weight, the moldability is inferior and draw resonance occurs, so that stable molding cannot be performed. On the other hand, when the mixing ratio of the component (C) exceeds 95% by weight, the adhesive strength to the paper base material layer 2a is impaired.

  When the adhesive resin layer 2c and the surface resin layer 2b are compared, the resin type to be used is a different resin, or the content ratio of the resin is changed to change between the paper substrate layer 2a and the surface resin layer 2b. The resin layer 2c can be given the property of improving adhesion. Specifically, the melting point of the resin composition constituting the adhesive resin layer 2c is preferably lower than the melting point of the surface resin layer 2c.

(3) Paper base layer 2a
Examples of the paper substrate of the present invention include fine paper, thin paper, glassine paper and the like, and those having a weight of 5 to 50 g / m ² , preferably 10 to 30 g / m ² are used. If the weight is less than the lower limit, the strength decreases, and if the weight exceeds the upper limit, it is not suitable for a packaging material. The paper base layer is preferably subjected to surface treatment such as corona discharge treatment, ozone treatment, and low temperature plasma treatment.

(4) Laminating method As a method for producing a paper base sheet by laminating the resin layers 2c and 2b on the paper base layer 2a, a single laminating method, a tandem laminating method, a sandwich laminating method, a co-pressing laminating method, and a dry laminating method are used. A known method such as a method can be used. Although the thickness of a paper base material layer is influenced also by the use of a packaging material, it is 5-100 micrometers normally, Preferably it is 10-50 micrometers. The thickness of the surface resin layer 2b is usually 5 to 30 μm, preferably 10 to 20 μm. The thickness of the adhesive resin layer is usually 5 to 30 μm, preferably 10 to 20 μm.

3. Half clear pack (1) Transparent film 1
As a transparent film used in the half clear pack of the present invention, a heat-sealable layer containing a low melting point resin such as random polypropylene or ethylene α-olefin copolymer is laminated on a base layer made of homopolypropylene, A commercially available heat-sealable OPP that has been axially stretched can be used.

(2) Heat-sealing method The heat-sealing method between the transparent film 1 and the following base material sheet 2 is produced by following a known method. The paper base sheet and the transparent film may have exactly the same shape, but in order to simplify the taking in and out of the food to be put in, the paper base sheet is more transparent than the transparent film at the end portion that is not heat-sealed. A shape that is several centimeters long and forms a chamfer is preferred. The main use of this half clear pack is for food packaging such as croquettes and fried foods, but it can also be used for other purposes.

In the present invention, a base resin suitable as an adhesive resin layer and a surface layer resin is conceived, and an appropriate amount of low-melting polyethylene is blended so that the paper base material 2a and the adhesive resin layer 2b are bonded together. The adhesion strength between each layer between the surface resin layer 2c and the transparent film 1 could be maintained between 2c. Furthermore, curling resistance is also achieved by enabling low-temperature sealing between the paper base sheet 2 and the transparent film 1.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not construed as being limited to these examples.
In Examples and Comparative Examples, various physical properties of the constituent components were measured and evaluated according to the following evaluation methods, and the following resins were used.

1. Evaluation method (1) Melt flow rate (MFR):
The MFR of the polyethylene resin was measured at 190 ° C. and a load of 2.16 kg according to JIS K6922-2 (2005). In addition, about polypropylene resin, measurement temperature was performed at 230 degreeC. The unit is g / 10 minutes.
(2) Density: Measured according to JIS K-7112.
(3) Melting point: Measured using a differential scanning calorimeter in accordance with JIS-K7121, and the peak top temperature (Tm) on the highest temperature side in the DSC melting curve was taken as the melting point.
(4) Adhesive strength:
The obtained paper base sheet was cut into a 15 mm wide test piece, peeled off from the interface between the paper base and the resin layer on the paper base, and the sample was rotated at an angle of 90 degrees with a tensile tester manufactured by Toyo Seiki Co., Ltd. Was pulled at a tensile speed of 300 mm / min, and the tensile strength at that time was measured.

(5) Heat sealability:
The cut pieces are combined into a 15 mm wide test piece, and the paper base sheet and the transparent film heat-sealable OPP) are overlapped so that the resin layer 2b of the paper base sheet and the heat-sealable layer 1b of the transparent film face each other. Toyo Seiki Co., Ltd. manufactured by Toyo Seiki Co., Ltd., with the upper seal bar of the upper sealer of the heat tester type heat sealer manufactured by the laminated tester industry set at 110 ° C. and the lower seal bar set at 30 ° C., with a seal pressure of 2 kg / cm ² and a seal time of 1 second. The tensile strength of the heat seal part was measured with a tensile tester at a tensile speed of 300 mm / min.

(6) Curl property:
The paper base sheet and transparent film (heat-sealable OPP) are cut into a size of 10 cm in length and 15 cm in width and overlapped so that the resin layer 2b of the paper base sheet and the heat-sealable layer 1b of the transparent film face each other. The three sides of the transparent film were heat-sealed by a tester industry hot plate type upper heat sealer with a width of 5 mm at 110 ° C. and a lower seal bar at 30 ° C., and 10 samples were heat sealed with a sealing pressure of 2 kg / cm ² and a sealing time of 1 second. .
Ten prepared samples were overlapped, and the height from the floor surface to the uppermost sample was measured, and the degree of curling was evaluated based on the height.
○: 5 mm or less from the floor surface Δ: 5 to 10 mm or less from the floor surface ×: 10 mm or more from the floor surface

(7) Oil resistance:
The paper base sheet and transparent film (heat-sealable OPP) are cut into a size of 10 cm in length and 15 cm in width and overlapped so that the resin layer 2b of the paper base sheet and the heat-sealable layer 1b of the transparent film face each other. The three sides of the transparent film were heat-sealed by a tester industry, with an upper heat sealer width of 5 mm at 130 ° C. and a lower seal bar at 30 ° C., and 9 samples were heat sealed with a sealing pressure of 2 kg / cm ² and a sealing time of 1 second. .
30 samples of edible oil were put into 9 prepared samples, one side was heat-sealed under the above conditions, and placed in a gear oven 50 ° C. manufactured by Suga Test Instruments Co., Ltd. Each sheet was taken out, and the paper sheet surface was directed to the upper surface, and the degree of oil penetration was observed and evaluated.
○: Oil leakage is not confirmed after 24 hours. Δ: Oil leakage is confirmed after 5 hours. ×: Oil leakage is confirmed after 1 hour.

2. Materials Used Materials (1) Material of the paper base sheet Paper base: 35 g of pure white paper resin a: Polypropylene resin “Product name PH943B manufactured by Sun Allomer Co., Ltd.”
Resin b: Polyethylene resin “Novatech LC607K manufactured by Nippon Polychem”
Resin c: Polyethylene resin “Nippon Polyethylene Kernel KS340T”
Resin d: Polyethylene resin “trade name NH745N manufactured by Nippon Polyethylene”
Resin e: Polyethylene resin “Kernel KF360T manufactured by Japan Polyethylene Corporation”
The physical properties of the resins a to e are summarized in Table 1.

[Example 1]
(1) Manufacture of paper base sheet 2 Resin at a molding temperature of 315 ° C. with a die width of 500 mm and a processing speed of 100 m / min using a 90 mmφ co-pressed single laminate molding machine manufactured by Modern Machinery Co., Ltd. 80 parts by weight of d and 20 parts by weight of resin c are mixed so that the resin composition is 7 μm, the molding temperature of the surface resin layer 2b is 285 ° C., 80 parts by weight of resin a and 20 parts by weight of resin e are mixed to 8 μm. A paper sheet was prepared by extrusion lamination to a paper substrate.
(2) Heat sealable OPP
Biaxially stretched heat-sealable OPP (biaxially stretched polypropylene film) “Transparent film 1”, trade name FOH-L, film thickness 20 μm, was used as transparent film 1.
(3) Manufacture of a half clear pack A heat-sealable OPP adhesive layer is stacked on a paper base sheet 2 cut to 15 cm × 10 cm, and a heat plate heat sealer manufactured by Tester Sangyo Co., Ltd. with a 5 mm wide seal bar. The upper seal bar was heat-sealed at 110 ° C., the lower seal bar was 30 ° C., the seal pressure was 2 kg / cm ² , and the seal time was 1 second to prepare a half clear pack.
Table 2 shows the evaluation results of the obtained half clear pack and paper base sheet.

[Example 2]
A laminate was obtained in the same manner as in Example 1 except that 70 parts by weight of the resin d and 30 parts by weight of the resin c were mixed to constitute the adhesive resin layer 2c in Example 1. The evaluation results of the obtained extrusion laminate are shown in Table 2.

[Example 3]
A laminate was obtained in the same manner as in Example 1 except that 60 parts by weight of resin d and 40 parts by weight of resin c were mixed as constituents of the adhesive resin layer 2c in Example 1. The evaluation results of the obtained extrusion laminate are shown in Table 2.

[Example 4]
A laminate was obtained in the same manner as in Example 1 except that 80 parts by weight of the resin b and 20 parts by weight of the resin c were mixed as constituting the adhesive resin layer 2c in Example 1. The evaluation results of the obtained extrusion laminate are shown in Table 2.

[Example 5]
A laminate was obtained in the same manner as in Example 1 except that 80 parts by weight of the resin d and 20 parts by weight of the resin e were mixed in the surface resin layer 2b in Example 1. The evaluation results of the obtained extrusion laminate are shown in Table 2.

[Example 6]
A laminate was obtained in the same manner as in Example 1 except that 60 parts by weight of resin d and 40 parts by weight of resin e were mixed as the surface resin layer 2b in Example 1. The evaluation results of the obtained extrusion laminate are shown in Table 2.

[Example 7]
In Example 1, 80 parts by weight of resin a and 20 parts by weight of resin e were mixed to constitute the surface resin layer 2b and the adhesive resin layer 2c, and a laminate was obtained in the same manner as in Example 1.

[Comparative Example 1]
In Example 1, except that 10 parts by weight of the resin d and 90 parts by weight of the resin c were mixed to constitute the adhesive resin layer 2c, a laminate was obtained in the same manner as in Example 1. As a result, a laminate could not be obtained.

[Comparative Example 2]
A laminate was obtained in the same manner as in Example 1 except that the resin d was changed to 100 parts by weight as the adhesive resin layer 2c in Example 1. The evaluation results of the obtained extrusion laminate are shown in Table 2.

[Comparative Example 3]
A laminate was obtained in the same manner as in Example 1 except that the adhesive resin layer 2c in Example 1 was composed of 100 parts by weight of resin b. The evaluation results of the obtained extrusion laminate are shown in Table 2.

[Comparative Example 4]
A laminated body was obtained in the same manner as in Example 1 except that the surface resin layer 2b and the adhesive resin layer 2c in Example 1 were constituted by 100 parts by weight of the resin a. The evaluation results of the obtained extrusion laminate are shown in Table 2.

As is clear from Examples 1 to 4, the paper base sheet comprising the paper base layer, the adhesive resin layer, and the surface resin layer of the present invention has good adhesion between the paper base and the adhesive resin layer. Moreover, it turns out that the clear pack obtained from this invention is excellent in the heat-sealing property of a paper base material sheet and a transparent film, and is excellent in curl resistance and oil resistance.
In Examples 5 and 6, since polypropylene is not included as the surface layer resin, oil leakage occurs during the oil resistance test due to a decrease in heat resistance and pinhole property, but there is no practical problem.
In Example 7, when a composition of a polypropylene resin and a polyethylene resin having a density of 0.920 or less is used as the adhesive resin layer, the adhesive strength with paper is slightly inferior, but it shows the same performance as the other examples.
On the other hand, in Comparative Example 1, draw resonance occurred because the moldability of the composition contained in the adhesive resin layer was significantly reduced due to the high content of polyethylene resin having a density of 0.920 or less.
In Comparative Examples 2 and 3, by not using a polyethylene resin having a density of 0.920 or less for the adhesive resin layer, the adhesive strength with the paper base material layer is impaired, and the clear pack curl also occurs significantly. It can be seen that the sealing strength between the layer and the OPP film is also impaired.
In Comparative Example 4, it can be seen that the adhesive strength with the paper base material layer is impaired and the sealing strength with the OPP film is also impaired because the adhesive layer resin and the surface layer resin are polypropylene resins.

Claims (5)

It is a paper base sheet for a half clear pack that is formed into a bag shape by overlapping three sides with a transparent biaxially oriented polypropylene film,
A paper base sheet 2 in which at least an adhesive resin layer 2c is laminated between the paper base layer 2a and the surface resin layer 2b,
The surface resin layer 2b is
(A) 55 wt% or more and 95 wt% or less of polypropylene resin or polyethylene resin having a melting point of 100 ° C or higher,
as well as,
(B) 5% by weight or more and 45% by weight or less of a polyethylene resin having a density of 0.920 g / cm ³ or less and a melting point of 110 ° C. or less (excluding 100 ° C. or more);
Containing
The adhesive resin layer 2c is
(C) 55 wt% or more and 95 wt% or less of polypropylene resin or polyethylene resin having a melting point of 100 ° C. or higher,
as well as,
(D) A polyethylene resin having a density of 0.920 g / cm ³ or less and a melting point of 110 ° C. or less (excluding 100 ° C. or more) is 5% by weight to 45% by weight,
And also it contains,
The melting point of the resin composition constituting the adhesive resin layer 2c is, the paper substrate sheet half clear pack, wherein <br/> lower than the melting point of the resin composition constituting the surface resin layer 2b. The adhesive resin layer 2c is
(C ′) 55 wt% or more and 95 wt% or less of a polyethylene resin having a melting point of 100 ° C. or higher,
as well as,
(D) A polyethylene resin having a density of 0.920 g / cm ³ or less and a melting point of 110 ° C. or less (excluding 100 ° C. or more) is 5% by weight to 45% by weight,
Half clear pack paper substrate sheet according to claim 1, characterized in that it contains. The surface resin layer 2b is
(A ′) 55 wt% or more and 95 wt% or less of polypropylene resin,
as well as,
(B) 5% by weight or more and 45% by weight or less of a polyethylene resin having a density of 0.920 g / cm ³ or less and a melting point of 110 ° C. or less (excluding 100 ° C. or more);
Half clear pack paper substrate sheet according to claim 1 or 2, characterized in that it contains. The polyethylene resin having a density of 0.920 g / cm ³ or less and a melting point of 110 ° C. or less (excluding 100 ° C. or more) described in (B) or (D) is a metallocene catalyst-based polyethylene resin. half clear pack paper base sheet according to any one of claims 1 to 3.   A transparent biaxially stretched polypropylene film 1 having a heat-sealable layer 1b provided on the outermost surface of a polypropylene-based substrate 1a faces the surface resin layer 2b of the paper substrate sheet 2 and the heat-sealable layer 1b. The half clear pack characterized by including the paper base material sheet in any one of Claims 1-4 formed by superposing so that it may heat-seal three sides, and forming in a bag shape.

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