JPH071667A - Wrapping film and packing bag - Google Patents

Abstract

PURPOSE:To provide a wrapping film excellent in heat sealability, transparency and burst-resistant strength and capable of being subjected to sterilizing treatment by setting the outer and inner layers bonded to a polyvinylidene chloride layer to a specific wt. average mol. wt. and setting the elution amt. with respect to the total amt. of a polypropylene resin to a specific wt.% within a specific temp. range. CONSTITUTION:A non-stretched polypropylene resin composite film is consists of at least two or more layers and the wt. average mol. wt. of the outer layer bonded to a polyvinylidene layer is 80000-500000 and the elution amt. to the total amt. of a polypropylene resin due to a cross fractionation method is 40-70wt.% at 0-10 deg.C 8-30wt.% at 10-65 deg.C and 15-35wt.% at 65-115 deg.C. The inner layer bonded to the polyvinylidene chloride layer has a wt. average mol. of 80000-500000 and the elution amt. thereof to the total amt. of the polypropylene resin due to the cross fractionation method is below 5wt.% at 0-20 deg.C, 8-30wt.% at 20-70 deg.C and 70-95wt.% at 70-110 deg.C.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a packaging film and a packaging bag which are preferably used for sterilizing retort packaging of foods.

[0001]

2. Description of the Related Art Conventionally, a retort packaging film used for long-term storage of food has been required to have heat resistance, high oxygen barrier property, heat sealability, toughness, transparency and the like. As a material of, for example, JP-A-4-
As described in No. 82737, a polyvinylidene chloride layer of a polyamide resin film having a polyvinylidene chloride layer on one side is laminated on a non-stretched polypropylene (hereinafter, referred to as CPP) film via a solventless adhesive layer. There is proposed a laminated film for packaging and a packaging bag in which the laminated film for packaging has a CPP film inside.

[0002]

However, this laminated film for packaging and the packaging bag are capable of maintaining the oxygen barrier property after retort treatment and preventing the whitening phenomenon of the vinylidene chloride layer, which has heretofore been impossible. However, since a general-purpose CPP is used as the inner layer film when used as a packaging bag, it is used for retort packaging, especially when it is used as a liquid or fluid content. In addition, the strength of bag rupture, cold resistance, suitability for packaging when filling contents, ethylene-vinyl acetate copolymer (hereinafter referred to as EVA), low density polyethylene (hereinafter referred to as LDPE),
It is widely known that it is inferior to linear low-density polyethylene (hereinafter referred to as L-LDPE).

On the other hand, EVA, LDPE, L-LDPE
Has low heat resistance and cannot withstand high temperature retort treatment. In addition, after retort treatment, crystallization of polyethylene progresses, white turbidity occurs in appearance, further deterioration in quality such as becoming harder and brittle, and suitable as a retort packaging material that requires transparency, especially as a sealant film. The current situation is that there is no such thing.

The present invention solves the above-mentioned conventional problems and uses a specific unstretched PP resin composite film to withstand high temperature retort treatment, and also has transparency, bag-breaking strength and cold resistance. It is intended to provide a packaging film and a packaging bag which have excellent properties and suitability for packaging at the time of filling contents and do not deteriorate in quality of the film after retort treatment.

[0005]

MEANS FOR SOLVING THE PROBLEMS The first aspect of the present invention is that a polyvinylidene chloride layer of a polyamide resin film having a polyvinylidene chloride layer on one outer side has a non-stretched polypropylene resin through a solvent-free adhesive layer. A packaging film adhered to a composite film, wherein the unstretched polypropylene resin composite film is composed of at least two layers, and the outer layer adhered to the polyvinylidene chloride layer has a weight average molecular weight of 80 to 500,000. , The elution amount with respect to the total amount of polypropylene resin measured by the cross fractionation method is 0 to 10
40 to 70% by weight at ℃, 8 to 30 at 10 to 65 ℃
% By weight, 15 to 35% by weight at 65 to 115 ° C., the inner layer has a weight average molecular weight of 80 to 500,000, and the elution amount based on the total amount of polypropylene resin measured by the cross fractionation method is 0 to Less than 5 wt% at 20 ° C, 8-30 wt% at 20-70 ° C, 70-11
A packaging film comprising 70 to 95% by weight at 0 ° C.

In the present invention 1, examples of the polyamide resin film include nylon-6 and nylon-6.
Examples thereof include films made of 6, nylon-11, nylon-12 and the like. A polyvinylidene chloride (hereinafter referred to as PVDC) layer is provided on at least one outer side of the polyamide resin film.

In the present invention 1, one-component moisture-curable polyurethane is preferably used as the solvent-free adhesive layer. For example, Dainippon Ink and Co .: trade name "Dick Dry SF102RA", Toyo Morton Co .: trade name. The name "ADCOAT N289" and the product name "Takunate A-280" manufactured by Takeda Pharmaceutical Co., Ltd. can be mentioned.

As the solventless adhesive layer, a two-component moisture-curable adhesive layer can be used. For example, aromatic isocyanate type polyether urethane and polyol, O
Examples thereof include H-terminated polyester type and NCO-terminated prepolymer type. However, the two-component moisture-curing type
Since the OH group and the NCO group of the isocyanate react with the epoxy group contained in the PVDC layer and other additives to cause the barrier property of the PVDC layer to be impaired, the one-component moisture-curing type is preferable.

In the present invention 1, it is necessary to use a specific unstretched polypropylene resin composite film. The unstretched polypropylene resin composite film is composed of at least two layers, and the outer layer adhered to the PVDC layer is
The weight average molecular weight is 80 to 500,000, and the elution amount of polypropylene (hereinafter referred to as PP) resin measured by the cross fractionation method is 40 to 70% by weight at 0 to 10 ° C and 10 to 65 ° C. 8 to 30% by weight, and 65
Of 15 to 35% by weight at ˜115 ° C., the inner layer has a weight average molecular weight of 80,000 to 500,000, and the elution amount relative to the total amount of PP resin measured by the cross fractionation method is 0 to 20.
Those which are less than 5% by weight at 0 ° C, 8 to 30% by weight at 20 to 70 ° C and 70 to 95% by weight at 70 to 110 ° C are used.

The amount of PP resin eluted by the cross fractionation method was measured as follows. First, PP resin 1
It is dissolved in o-dichlorobenzene at 40 ° C or a temperature at which the PP resin is completely dissolved. Next, this solution is cooled at a constant rate to form a thin polymer layer on the surface of an inert carrier prepared in advance. At this time, the PP resin component is formed as a polymer layer in the order of high crystallinity and in the order of high molecular weight.

After that, the temperature is raised continuously or stepwise, the concentration of the PP resin component eluted in sequence is detected, and the composition distribution (crystallinity distribution) is measured (temperature rising elution fractionation).
At the same time, the molecular weight and molecular weight distribution of the components eluted by high temperature GPC are measured. Elevated temperature elution fractionation (TREF = Temperature Rising E
rotation fractionation) part,
The high temperature GPC (for example, SEC = Sise Excel)
and a cross fractionation chromatograph (CF) having a system
C = T150A type: manufactured by Mitsubishi Petrochemical Co., Ltd.) was used to measure the elution amount of the PP resin.

The PP resin forming the outer layer of the unstretched PP resin composite film is PP measured by the cross fractionation method.
The elution amount with respect to the total amount of the system resin is 40 to 7 at 0 to 10 ° C.
It is preferably 0% by weight. When this elution amount is less than 40% by weight, the obtained composite film lacks flexibility and causes problems such as bag breakage. On the contrary, when it exceeds 70% by weight, the heat resistance of the obtained composite film is high. Lack of transparency and transparency.

Further, the PP resin forming the outer layer of the unstretched PP resin composite film has an elution amount of 10 to 65 ° C. with respect to the total amount of PP resin measured by the cross fractionation method.
It is preferably about 30% by weight. When the amount of this elution is less than 8% by weight, the resulting composite film has a problem that the transparency is lowered after the retort treatment.
If it exceeds 0% by weight, appearance defects such as unevenness occur during molding of the composite film.

The PP resin forming the outer layer of the unstretched PP resin composite film has an elution amount of 15 to 35% by weight at 65 to 115 ° C. with respect to the total amount of PP resin measured by the cross fractionation method. Is preferred. This elution amount is
When it is less than 15% by weight, the heat resistance of the obtained composite film is lowered, and the bag is liable to be broken during retort treatment. On the contrary, when it exceeds 35% by weight, the flexibility of the composite film is insufficient. , Problems such as bag breakage occur.

The flexural modulus of the outer layer of the unstretched PP resin composite film is preferably 4,500 kg / cm ² or less. If the elastic modulus exceeds 4,500 kg / cm ² , the bag tear resistance and cold resistance are insufficient.

The PP resin forming the inner layer of the unstretched PP resin composite film is PP measured by the cross fractionation method.
The elution amount with respect to the total amount of the base resin is 5% by weight at 0 to 20 ° C.
The following is preferable. If this amount of elution exceeds 5% by weight, the transparency is lowered due to the influence of the amorphous part in the composite film.

The PP-based resin forming the inner layer of the unstretched PP-based resin composite film has an elution amount of 20 to 70 ° C. with respect to the total amount of the PP-based resin measured by the cross fractionation method.
It is preferably about 30% by weight. When the amount of this elution is less than 8% by weight or more than 30% by weight, a problem occurs in the transparency of the obtained composite film.

The PP resin forming the outer layer of the unstretched PP resin composite film has an elution amount of 70 to 95% by weight at 70 to 110 ° C. with respect to the total amount of PP resin measured by the cross fractionation method. Is preferred. This elution amount is
If it is less than 70% by weight, the heat resistance of the composite film will be problematic, and if it exceeds 95% by weight, the packaging film and the packaging bag obtained will have problems in packaging suitability and transparency.

The flexural modulus of the inner layer of the unstretched PP resin composite film is preferably 5,500 to 7,000 kg / cm ² . When the elastic modulus is less than 5,500 kg / cm ² , the transparency of the obtained packaging film is impaired, and conversely, when it exceeds 7,000 kg / cm ² ,
The heat-sealing property of the obtained packaging film tends to be poor.

This unstretched PP resin composite film can be produced by the existing coextrusion inflation method or T-die method. Furthermore, a layer made of the same reactor blend PP resin as the inner layer was provided outside the outer layer.
It may have a layered structure.

In a second aspect of the present invention, the polyamide resin film of the first aspect of the present invention has a polyvinylidene chloride layer on the outside as well, and a solventless adhesive layer is provided on the other polyvinylidene chloride layer on the outside. It is a packaging film in which a stretched polyolefin-based resin film or a stretched polyester-based resin film is adhered via.

In the present invention 2, a polyamide resin film having vinylidene chloride layers on both outer sides is used. As the polyamide resin film and the PVDC layer provided on both outer sides thereof, the same ones as those of the first invention are used.

In the present invention 2, as the stretched polyolefin resin film or the stretched polyester resin film, a film obtained by using a polyolefin resin or a polyester resin and stretched is used. The stretching method may be a uniaxial stretching method or a biaxial stretching method, and may be a tenter method or a rolling method. Any material that can be used can be appropriately used.

In the present invention 2, the same solventless adhesive as in Example 1 is used.

The present invention 3 is a packaging bag in which the unstretched PP-based resin composite film of the present invention 1 or the invention 2 is formed inside.

As a bag-making method, a method in which the non-stretched PP composite film is faced to the inside and heat-sealed can be adopted. In the case of retort packaging, the contents are usually filled in a bag whose three sides are heat-sealed, and then the opening is heat-sealed.

[0027]

The packaging film of the present invention 1 is a non-stretched PP resin composite film in which a polyvinylidene chloride layer of a polyamide resin film having a polyvinylidene chloride layer on one outer side is interposed by a solventless adhesive layer. In the packaging film adhered to the non-stretched PP resin composite film, the outer layer composed of at least two layers is not a conventional general-purpose CPP, and the outer layer adhered to the polyvinylidene chloride layer has a weight average molecular weight. Is 80 to 500,000, and the amount eluted with respect to the total amount of the PP resin measured by the cross fractionation method is 40 to 70% by weight at 0 to 10 ° C and 8 to 30% by weight at 10 to 65 ° C. It is composed of 15 to 35% by weight at 65 to 115 ° C., the inner layer has a weight average molecular weight of 80 to 500,000, and the elution amount based on the total amount of PP resin measured by the cross fractionation method is 0 to 20 ° C. Less than wt%, 20 to 70 ° C.
8 to 30% by weight, and 70 to 95 at 70 to 110 ° C.
By using the one consisting of the material of which the content is% by weight, the inner layer is excellent in heat sealability and heat resistance, and the outer layer is also excellent in bag-breaking strength and cold resistance and also serves as a reinforcing layer for the inner layer. As it achieves excellent heat sealability, it can withstand high temperature retort treatment well, and it has excellent transparency, bag puncture resistance, cold resistance, packaging suitability when filling contents, and deterioration of film quality after retort treatment. Absent.

In the packaging film of the present invention 2, the polyamide resin film of the present invention 1 has a polyvinylidene chloride layer on the outside as well, and the other polyvinylidene chloride layer on the other side is solvent-free. By adhering a stretched polyolefin resin film or a stretched polyester resin film via an adhesive layer, the function of the present invention 1 can be obtained, and in addition to those having many protrusions or those having a sharp shape as contents. The practical puncture resistance is further improved.

Since the packaging bag of the present invention 3 is formed so that the unstretched PP resin composite film of the present inventions 1 and 2 is on the inside, the packaging bag of the present inventions 1 and 2 is excellent. It is a packaging bag with performance.

[0030]

EXAMPLES The present invention will be described below with reference to examples. Example 1 A surface of nylon-6 film having a thickness of 15 μm is coated with PVDC on one surface.
A layer (thickness 3 μm) is provided, and a one-component moisture-curable polyurethane adhesive (manufactured by Dainippon Ink and Co., product name “Dick Dry SF102RA”) is applied to the PVDC layer surface in the range of 80 to 100.
It is heated to ℃ and coated with steam heating to about 1.5 g / m ^2, and a film of unstretched PP resin composite film with a thickness of 60 μm is stuck as it is.
Aging was performed at 0 ° C. for 3 days to obtain a packaging film.

As the unstretched PP resin composite film, a three-layer structure having an inner layer of 40 μm and an outer layer of 10 μm provided on both surfaces was used. The inner layer has a weight average molecular weight of 3
53,000, the elution amount with respect to the total amount of PP resin measured by the cross fractionation method was 53.6% by weight at 0 to 10 ° C., 1
13.9 wt% at 0-65 ° C, 32. at 65-115 ° C.
5% by weight of PP resin (manufactured by Highmont, trade name "Cataloy KS-052"), the outer layer has a weight average molecular weight of 250,000, the elution amount of the PP resin measured by the cross fractionation method with respect to the total amount. , 2.5 wt% at 0 to 20 ° C., 11.0 wt% at 20 to 70 ° C., 86.5 wt% at 70 to 110 ° C. (manufactured by Himont, trade name “Cataloy KT-011”) ) Was used.

The transparency (haze), heat seal strength and oxygen permeability of the obtained packaging film which was not retort treated and those which were retort treated at 105 ° C. for 30 minutes were measured. The results are shown in Table 1. The transparency (haze) was evaluated by measuring the haze value according to JIS K6714. The heat seal strength was measured according to JIS Z1707. The oxygen permeability was measured according to the gas permeability test method of JIS Z1707.

In addition, the obtained unwrapped PP resin composite film and the unwrapped PP film composite film for 30 minutes at 105 ° C. were used. Heat-sealing the three sides so that the film is on the inside, width 140 mm, length 1
A bag of 90 mm was prepared, 200 cc of water was filled in the bag, the opening of which was heat-sealed was left still on concrete, and 20% of the bag was broken when a 2 kg load plate was dropped from the bag. The bag breaking strength was measured. The results are shown in Table 1.
Are also shown.

Further, the obtained packaging film is at 105 ° C.
Unstretched PP using retort treated for 30 minutes at
Heat-sealed three sides with the resin composite film on the inside to produce a bag having a width of 140 mm and a length of 190 mm, filled with 250 cc of water therein, and then heat-sealed at the opening to seal the bag. A drop bag test was conducted in which the bag was dropped onto a concrete surface from a height of 1.2 m to measure the drop bag rate. The results are also shown in Table 1.

Comparative Example 1 A packaging film was obtained in the same manner as in Example 1 except that CPP having a thickness of 60 μm was used instead of the unstretched PP resin composite film. Transparency (haze), heat seal strength, oxygen permeability, bag breaking strength were measured, and a drop bag test was conducted. The results are also shown in Table 1.

[0036]

[Table 1]

As is clear from Table 1, in the case of Example 1, the bag breaking strength is high and the bag breaking rate in the drop test is small, whereas in the case of Comparative Example 1, the bag breaking strength is high. Low,
The bag breakage rate in the drop test is high.

Example 2 A PVDC layer (thickness: 3 μm) was provided on both sides of a polyamide film having a thickness of 15 μm, and a one-component moisture-curable polyurethane adhesive (manufactured by Dainippon Ink and trade name “Dick Dry” was provided on the PVDC layer surface. SF10 ") is heated to 80 to 100 ° C. and is applied while heating with steam so that the amount becomes about 1.5 g / m ^2, and a polyester resin film having a thickness of 12 μm is attached to one surface thereof and the other surface The same unstretched PP-based resin composite film as that used in Example 3 having a thickness of 60 μm was laminated and aged at 40 ° C. for 3 days to obtain a packaging film.

The resulting packaging film was stored at 105 ° C. for 3 days.
Using the retort treated for 0 minutes, the non-stretched PP resin composite film was placed inside and heat-sealed on three sides to produce a bag having a width of 140 mm and a length of 165 mm.
After filling 150g of rice in it, the opening is heat-sealed and sealed.
Dropping from 0, 90 and 120 cm, a pinhole bag breaking test was conducted. The results are shown in Table 2. The pinhole bag breaking test was performed according to JIS Z0202.

Comparative Example 2 A pinhole bag breakage test was conducted in the same manner as in Example 2 except that the packaging film obtained in Comparative Example 1 was used. The results are also shown in Table 2.

[0041]

[Table 2]

As is clear from Table 2, in the case of Example 2, the resistance to bag breakage when filled with the filling having protrusions is excellent, while in the case of Comparative Example 2, It is inferior in bag puncture resistance when filled with protrusions.

[0043]

EFFECTS OF THE INVENTION The packaging film of the present invention 1 has the above-mentioned constitution, and therefore has excellent heat-sealing property, can well withstand high temperature retort treatment, and has transparency, bag-breaking strength and cold resistance. It has excellent properties and suitability for packaging when filling contents, has no deterioration in film quality after retort treatment, and can be subjected to high temperature retort sterilization treatment, and can be suitably used as a film for packaging retort treatment of foods and the like.

Since the packaging film of the present invention 2 has the above-mentioned constitution, in addition to the effect of the present invention 1,
Practical puncture resistance to those with many protrusions and sharp shapes as contents is further improved, and it can be suitably used as a film for retort packaging of foods with many protrusions and sharp shapes. it can.

Since the packaging bag of the present invention 3 is configured as described above, it provides the excellent performance of the packaging film of the present inventions 1 and 2 and can be subjected to high temperature retort sterilization treatment, and can be used for foods and the like. It can be suitably used as a retort treatment packaging bag.

Claims (3)

[Claims] 1. A polyvinylidene chloride layer of a polyamide resin film having a polyvinylidene chloride layer on one outer side,
A packaging film adhered to a non-stretched polypropylene resin composite film through a solventless adhesive layer,
The unstretched polypropylene-based resin composite film is composed of at least two layers, and the outer layer adhered to the polyvinylidene chloride layer has a weight average molecular weight of 80,000 to 500,000, based on the total amount of the polypropylene-based resin measured by the cross fractionation method. The elution amount is 40 to 70% by weight at 0 to 10 ° C.,
8 to 30% by weight at 10 to 65 ° C, 65 to 115 ° C
Of 15 to 35% by weight, the inner layer has a weight average molecular weight of 80 to 500,000, and the elution amount relative to the total amount of polypropylene resin measured by the cross fractionation method is 0 to 20%.
A film for packaging, characterized in that it is less than 5% by weight at 0 ° C, 8 to 30% by weight at 20 to 70 ° C, and 70 to 95% by weight at 70 to 110 ° C. 2. The polyamide resin film according to claim 1, which has a polyvinylidene chloride layer on the outside as well, and is stretched on the polyvinylidene chloride layer on the other side through a solventless adhesive layer. A packaging film comprising a polyolefin resin film or a stretched polyester resin film adhered thereto. 3. A packaging bag, wherein the unstretched polypropylene-based resin composite film according to claim 1 or 2 is formed so that it is on the inside. [0001]