JPH10166527A - Polypropylene laminated non-oriented film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polypropylene laminated non-oriented film having low temperature heat sealability and impact resistance at a low temperature without lowering laminating characteristics at the time of laminating with other film even when the film is stored for a long period. SOLUTION: A laminated layer obtained by mixing 5 to 50 pts.wt. of ethylene block copolymerized polypropylene polymer with 100 pts.wt. of ethylene random copolymerized polypropylene polymer, an intermediate layer formed of ethylene random copolymerized polypropylene polymer and a sealing layer obtained by mixing 1 to 15 pts.wt. of polyolefin random copolymerized elastomer with 100 pts.wt. of ethylene random copolymerized polypropylene polymer are sequentially laminated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polypropylene-based laminated unstretched film, and more particularly, for example, when used in food packaging, has excellent low-temperature heat sealability and low-temperature impact resistance. And, for example, when used as a laminate with a polyamide film, suitable for use in a laminate that withstands severe treatment such as boiling water treatment or retort treatment, particularly extremely severe treatment such as aeration boil treatment. The present invention relates to a polypropylene-based laminated unstretched film in which lamination properties with other films do not deteriorate even when the laminated film is stored for a long period of time.

[0002]

2. Description of the Related Art Unstretched polypropylene-based films are used in various packaging materials such as food packaging because they have high rigidity among sealant films, good transparency, and are inexpensive. However, low-temperature heat sealability,
It has a drawback that it has poor impact resistance, particularly at low temperatures.

On the other hand, in recent years, the speed of bag making machines has been increased, and the market demand for low-temperature heat-sealing properties of polypropylene-based unstretched films has also increased. Also, with the spread of frozen foods and the like, there is an increasing demand for improved impact resistance at low temperatures. To meet these demands,
Various methods have been considered, but have not met the high market demands.

For example, in Japanese Patent Application Laid-Open No. 5-262900, an ethylene random copolymer polypropylene polymer and a binary copolymer of ethylene and propylene or butene-1, or a ternary copolymer of these with a non-conjugated diene are disclosed. There has been proposed a polypropylene-based unstretched film composed of a blended product. Certainly, the low-temperature heat sealability was improved by this method, but the effect of improving the impact resistance at low temperatures was insufficient.

[0005] In recent years, due to the improvement in food culture, the genuine product orientation has become stronger, and the switching from dry noodles to fresh noodles has also been promoted for instant noodles. In the case of the raw noodle type, heat sterilization is performed after the raw noodle is sealed and packaged. Since this heat sterilization treatment is performed in an air-containing state, a large stress is applied to the seal portion due to expansion of the air and water vapor inside the sealed body due to heat. For this reason, the sealing strength of the conventional packaging material alone is insufficient in characteristics, and a water-resistant sealing property that can withstand the internal pressure generated by the aerated boiling process is required.

[0006] In recent years, in order to meet high taste demands, the conditions of aerated boil have become more severe, and the development of sealant films that can meet these market demands has been desired.

For example, when the above-mentioned known polypropylene-based unstretched film is applied to this field, a copolymer of an ethylene-based random copolymer and ethylene and butene or a copolymer of ethylene and butene and a non-copolymer is used. Due to poor compatibility with the base copolymer, voids were formed at the interface between the two polymers, resulting in a decrease in seal strength and a failure to withstand the internal pressure generated by the aerated boil treatment. .

[0008]

SUMMARY OF THE INVENTION The above-mentioned Japanese Patent Application Laid-Open No. 5-262 is disclosed.
Although the conventional polypropylene-based unstretched film described in Japanese Patent Publication No. 900 has certainly improved the low-temperature heat sealability, the effect of improving the impact resistance at low temperatures was not sufficient.

Further, in the case of a conventionally known film, when the film is stored for a long period of time, particularly in a high temperature state, for example, a lubricant added to the film for imparting lubricity migrates to the surface of the film, and the film may become incompatible with other films. There was a disadvantage that the laminating characteristics when laminating were deteriorated.

The present invention solves the problem that no conventional propylene-based unstretched film has both low-temperature heat sealability and low-temperature impact resistance, and is used, for example, as a laminate with a polyamide film. When improved, improved heat-resistant water sealability to withstand severe treatments such as boiling water treatment and retort treatment, especially extremely severe treatments such as boiled boil treatment, and even if the film is stored for a long time, other An object of the present invention is to improve the storage stability in which the lamination characteristics when laminated with a film are not reduced.

[0011]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have reached the present invention.

In order to achieve the above object, the polypropylene-based laminated unstretched film of the present invention has an ethylene content of 2 to 2.
The ethylene content is 5 to 15 with respect to 100 parts by weight of the ethylene random copolymerized polypropylene polymer which is 8% by weight.
Laminated layer containing 5 to 50 parts by weight of an ethylene block copolymerized polypropylene polymer of 2% by weight, an intermediate layer of an ethylene random copolymerized polypropylene polymer having an ethylene content of 2 to 8% by weight, and an ethylene content of 2
It is characterized in that a seal layer in which 1 to 15 parts by weight of a polyolefin-based random copolymer elastomer is blended in order with 100 parts by weight of an ethylene random copolymerized polypropylene polymer of about 8% by weight is sequentially laminated.

[0013] The polypropylene-based laminated unstretched film having the above-mentioned structure has low-temperature heat sealability, low-temperature impact resistance, and even when stored for a long period of time, when laminated with another film. It has storage stability that does not lower the laminating properties.

In this case, the intermediate layer contains 1 to 15 parts by weight of a polyolefin random copolymer elastomer based on 100 parts by weight of an ethylene random copolymerized polypropylene polymer having an ethylene content of 2 to 8% by weight. It can be a blended polymer mixture.

[0015] The polypropylene-based laminated unstretched film having the above-mentioned structure has improved water-sealing resistance, which can improve heat-sealing properties at low temperatures and impact resistance at low temperatures, and can withstand extremely severe processing.

Further, in the polypropylene-based laminated unstretched film, the polyolefin-based random copolymer elastomer can be a copolymer of ethylene, propylene and butene.

The polypropylene-based laminated unstretched film having the above-mentioned structure has a water-resistant sealing property that can withstand severe treatments such as a boiling water treatment and a retort treatment, in particular, extremely severe treatments such as an aerated boil treatment.

As the polypropylene-based laminated unstretched film, a polyolefin-based random copolymer elastomer having a Vicat softening point of 70 ° C. or less and a surface hardness of 80 or less can be used.

The polypropylene-based laminated unstretched film having the above-mentioned structure has improved heat-sealing properties at low temperatures and impact resistance at low temperatures.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an embodiment of a polypropylene-based laminated unstretched film of the present invention will be described.

The ethylene random copolymer polypropylene polymer used in the present invention has an ethylene content of 2
８8% by weight. Particularly, the ethylene content is preferably 3 to 7% by weight.

If the ethylene content is less than 2% by weight, the low-temperature heat sealability and impact resistance of the film are undesirably reduced. Conversely, if it exceeds 8% by weight, the blocking resistance of the film is undesirably reduced. In addition, there is a problem that the rigidity and heat resistance of the film decrease.

The method for producing the ethylene random copolymerized polypropylene polymer is not particularly limited.
The liquid phase method may be used. The catalyst is also not limited, and may be a Ziegler-Natta catalyst or a metallocene catalyst.

It is preferable to use the ethylene random copolymerized polypropylene polymer which has been deodorized by, for example, a reduced pressure treatment. The melt flow rate (M) measured at 230 ° C. in accordance with JIS-K-7210
It is preferred to use I) for 3 to 15 g / 10 minutes.

The polyolefin random copolymer elastomer used in the present invention includes ethylene-propylene, ethylene-butene or propylene-butene binary copolymer, ethylene-propylene-butene ternary copolymer or copolymer thereof. Polymers can be used. Further, a copolymer obtained by further copolymerizing another monomer may be used as long as its properties are not impaired.

In particular, use of a ternary copolymer is preferred.
Further, it is preferable to use one having a Vicat softening point of 70 ° C. or less and a surface hardness of 80 or less.

The polyolefin random copolymer elastomer has an MI of 23 (based on JIS-K-7210,
(Melt flow rate measured at 0 ° C.) 3 to 15 g / 1
It is preferable to use one for 0 minutes.

The method for producing the polyolefin-based random copolymer elastomer is also not particularly limited, but may be produced using a Ziegler-Natta catalyst, particularly a catalyst comprising a vanadium oxytrichloride / vanadium tetrachloride compound and an organoaluminum compound. It is preferable to use one that has been used.

The ethylene block copolymerized polypropylene polymer used in the present invention has an ethylene content of 5%.
１５15% by weight must be used. Particularly, the ethylene content is preferably 7 to 13% by weight. If the ethylene content is less than 5% by weight, the impact resistance, the aerated boil-puncture resistance and the storage stability are undesirably deteriorated. Conversely, 15
If the amount is more than 10% by weight, the effect of improving the storage stability is saturated, and the transparency and the resistance to aerated boil-puncture are undesirably reduced. The ethylene block copolymer elastomer preferably has an MI (melt flow rate measured at 230 ° C. in accordance with JIS-K-7210) of 1 to 10 g / 10 minutes.

The method for producing the block copolymer is not particularly limited, and may be a liquid phase method or a gas phase method.

In the present invention, the function of each layer is divided into a laminated film divided into a seal layer, an intermediate layer and a laminate layer, and by changing the mixing ratio of the above-mentioned three types of polymers in each layer. The most characteristic feature is that the quality characteristics of the various films are balanced.

That is, the seal layer is made of a polyolefin random copolymer elastomer in an amount of 1 to 15 parts by weight per 100 parts by weight of the ethylene random copolymerized polypropylene polymer.
By blending parts by weight, a high heat-resistant water sealing strength is imparted, and for example, when used as a laminate with a polyamide film, a property of withstanding an extremely severe boiled boil treatment can be obtained. In addition, it is inevitable to mix any other polymer into the sealing layer as long as the original properties of the film of the present invention are not impaired. A particularly preferred polymer composition of the seal layer is that 2 to 13 parts by weight of the olefin random copolymer elastomer is blended. If the blending amount of the olefin random copolymer elastomer is less than 1 part by weight, the low-temperature heat sealability of the film, the impact resistance and the resistance to aerated boil puncture will decrease, and if it exceeds 15 parts by weight, the blocking resistance will increase. It is not preferable because the strength of the hot water seal decreases and the resistance to aerated boil puncture deteriorates.

The intermediate layer is formed by blending 5 to 20 parts by weight of an ethylene random copolymerized polypropylene polymer or a polyolefin random copolymer elastomer with 100 parts by weight of an ethylene random copolymerized polypropylene polymer. Provides low-temperature heat sealability and impact resistance.

If the amount exceeds 15 parts by weight, the transparency of the film is undesirably reduced. Further, the rigidity, heat resistance, blocking resistance and the like of the film are undesirably reduced.

The laminate layer has a function of improving long-term storage stability without deteriorating the above-mentioned properties, that is,
Ethylene random copolymerized polypropylene polymer 1 has a function of preventing deterioration of lamination characteristics such as a decrease in lamination strength upon lamination with another film due to migration of a lubricant which occurs when the film is stored for a long period of time.
It is necessary to blend 5 to 50 parts by weight of the ethylene block copolymerized polypropylene polymer with respect to 00 parts by weight. In particular, the blending amount of the ethylene block copolymerized polypropylene polymer is preferably 10 to 40 parts by weight. If the amount of the polymer is less than 5 parts by weight, the effect of improving long-term storage stability and the impact resistance are undesirably reduced.

Conversely, if the amount of the ethylene block copolymerized polypropylene polymer exceeds 50 parts by weight, the effect of improving long-term storage stability is saturated, and the transparency and the resistance to aerated boil-punk are reduced. Not preferred.

The thickness composition ratio of the seal layer, the intermediate layer and the laminate layer of the polypropylene-based laminated unstretched film of the present invention is as follows: seal layer / intermediate layer / laminate layer = 0.05-0.
The range of 2 / 0.9 to 0.4 / 0.05 to 0.4 is preferred.

The raw material composition for an unstretched film used in the present invention can be obtained by dry blending the above-mentioned polymer or by melt-kneading and pelletizing thereafter. For dry blending, a Henschel mixer, V-type mixer, ribbon-type blender, etc. can be used. For melt-kneading, a Banbury mixer, a continuous mixer, a mixing roll, an extruder, etc. can be used. . If necessary, an antiblocking agent, a heat stabilizer, an antioxidant, an ultraviolet absorber, other additives, and the like can be added to the above-mentioned raw material composition for a film. If it is a small amount, another olefin-based polymer may be blended.

As the antiblocking agent, it is preferable to use spherical fine particles. When spherical fine particles are used, the transparency, slipperiness and blocking resistance of the film can be easily balanced.

The polypropylene-based laminated unstretched film of the present invention is obtained by melt-extruding the above-mentioned polymer composition into a seal layer, an intermediate layer, and a laminate layer by using separate extruders.
It can be obtained by co-extrusion. For example, an inflation molding method using a circular die, a T die molding method using a T die, and the like are employed.

[0041]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited by the following examples, and may be appropriately modified within a range that can conform to the purpose of the preceding and the following. It is also possible to make changes to
All of them are included in the technical scope of the present invention.

The measurement and evaluation methods adopted in this specification are as follows.

[Haze] The haze was measured using a “Haze Tester J” manufactured by Toyo Seiki Seisakusho in accordance with JIS-K-6714.

[Seal start temperature] Using a thermal gradient heat sealer manufactured by Toyo Seiki Seisaku-sho, pressure 2 kg / cm ² ×
After heat sealing under the condition of 1.0 second, the strength was measured, and the temperature at which the value became 500 g / 15 mm was defined as the sealing start temperature.

[Blocking resistance] ASTM-D189
It was measured according to 3-67.

[Impact Resistance] The impact strength of the film was measured in an environment of 5 ° C. and 0 ° C. using an impact tester manufactured by Toyo Seiki Seisakusho [impact head: 12.7 mm (1 / 2φ)].

[Surface hardness of elastomer] JIS-K-
It was measured according to 6301.

[Vicat softening point of elastomer] AST
It measured according to MD1525.

[Aerated Boil Puncture Resistance of Polyamide Film Laminated Body] A 25 μm biaxially stretched polyamide film (harden film N, manufactured by Toyobo Co., Ltd.) which has been subjected to a water-resistant and easy-adhesion treatment.
7032AG) and a polypropylene-based composite unstretched film, using a polyester polyurethane-based adhesive (main agent: aromatic / aliphatic copolymerized polyester polyol having a secondary transition point (Tg) of -16 ° C, crosslinking agent: hexamethylene diisocyanate triplet) ) And the thickness of the adhesive layer is 2.5 g / m ^2.
Was dried in accordance with a conventional method to obtain a polyamide film laminate. The polyamide film laminate has an inner size of 13 cm x
The bag was formed into a 13 cm three-sided bag, filled with 200 cc of water and 200 cc of air, and then sealed. This sealed bag was boiled for 60 minutes, and the boil puncture rate at the sealed portion was calculated as follows. The long-term storage product was evaluated for the boil puncture rate of a laminate obtained by laminating a film stored in a roll at 40 ° C. for one month with a polyamide film, and a measure of long-term storage stability.

Boil puncture rate (%) = (number of torn bags / number of sealed bags tested) × 100

[Hot Water Seal Strength of Polyamide Film Laminate] The polyamide film laminate obtained by the above method was heat-sealed under the conditions of pressure of 2 kg / cm ² × 1.0 second at 180 ° C. I do. The sample was kept in hot water at 90 ° C.
Peel the mold. Measured at a pulling speed of 100 mm / min,
The longitudinal seal strength was determined.

Example 1 As a seal layer, 93 parts by weight of an ethylene random copolymerized polypropylene polymer (MI = 6.2) having an ethylene content of 5.5% by weight, a Vicat softening point of 38 ° C., and 7 parts by weight of a tertiary random copolymer elastomer (MI = 5.7) composed of ethylene, propylene and butene having a surface hardness of 68, and an average particle diameter of 4 μm
A composition comprising 0.1 part by weight of amorphous silica, 0.3 part by weight of spherical zeolite having an average particle size of 5 μm and 0.05 part by weight of erucamide was used as an intermediate layer to have an ethylene content of 5.5% by weight. Random copolymer polypropylene elastomer (MI = 6.2) of 96 parts by weight, a Vicat softening point of 38 ° C., and a surface hardness of 68, comprising a tertiary random copolymer elastomer 4 comprising ethylene, propylene and butene A composition consisting of 0.1 part by weight of amorphous silica having an average particle size of 4 μm and 0.05 part by weight of erucamide was added to a laminate layer having an ethylene content of 5.5% by weight.
Random copolymerized polypropylene polymer (MI
= 6.2) 70 parts by weight of ethylene block copolymer polypropylene polymer (MI
= 3.0) A composition comprising 30 parts by weight and 0.1 part by weight of amorphous silica having an average particle size of 4 μm was melt co-extruded using a separate extruder, and subjected to T-die casting to form a seal layer thickness. A polypropylene-based laminated unstretched film having a thickness of 10 µm, a base layer thickness of 25 µm, and a laminate layer thickness of 5 µm was obtained. Table 1 shows the properties of the obtained film.

The polypropylene-based laminated unstretched film obtained in this example was of high quality as shown in Table 1.

(Examples 2, 3, 4 and Comparative Examples 1, 2,
3) A polypropylene laminated unstretched film was obtained in the same manner as in Example 1 except that the mixing ratio of the resin in the intermediate layer and the sealing layer was changed. Table 1 shows the properties of the obtained film.

The films obtained in Examples 2, 3, and 4 were of high quality, but the film obtained in Comparative Example 1 was inferior in air-resistant boil puncture resistance, low-temperature heat sealability and impact resistance. The film obtained in Comparative Example 2 was inferior in air-resistant boil puncture resistance and blocking resistance, and the film obtained in Comparative Example 3 was inferior in air-resistant boil puncture resistance, blocking resistance and transparency, and was of low quality. Was.

Comparative Example 4 A polypropylene-based resin was prepared in the same manner as in Example 1 except that the same resin as the intermediate layer resin was used as the resin for the sealing layer and the resin for the laminate layer. A laminated unstretched film was obtained. Table 2 shows the properties of the obtained film.

The film obtained in this comparative example was inferior in long-term storage stability and of low quality.

(Comparative Example 5) A polypropylene-based unstretched film was produced in the same manner as in Example 1 except that the resin for the laminating layer was changed to have the same resin composition as the intermediate layer resin. Obtained. Table 2 shows the properties of the obtained film.

The film obtained in this comparative example was also inferior in long-term storage stability and of low quality.

(Comparative Examples 6 and 7) In the method of Example 1, the ethylene content of the ethylene random copolymer polypropylene polymer used for the seal layer, the intermediate layer and the laminate layer was 1.5% by weight, respectively. Except for (Comparative Example 6) and 9.0% by weight (Comparative Example 7), a polypropylene-based laminated unstretched film was obtained in the same manner as in Example 1. Table 2 shows the properties of the obtained film.

The film obtained in Comparative Example 6 was inferior in low-temperature heat-sealing properties, impact resistance and air-resistant boil-puncture resistance, and the film obtained in Comparative Example 7 had blocking resistance and long-term storage stability. Inferior, all films were of poor quality.

Comparative Examples 8 and 9 In the method of Example 1, the amounts of the ethylene random copolymerized polypropylene polymer and the ethylene block copolymerized polypropylene polymer in the laminate layer were 98 parts by weight / 2 parts by weight, respectively. Comparative Example 8) and 45 parts by weight / 55 parts by weight (Comparative Example 9)
A polypropylene-based laminated unstretched film was obtained in the same manner as in Example 1 except that the film was changed to. Table 1 shows the properties of the obtained film.

The film obtained in Comparative Example 8 was inferior in impact resistance and long-term storage stability, and the film obtained in Comparative Example 9 was inferior in transparency, blocking resistance and air-containing boil puncture resistance. Both films were of poor quality.

(Comparative Example 10) In the method of Example 1,
All resin compositions of the seal layer, the intermediate layer and the laminate layer had an ethylene content of 3.7% by weight and an MI of 7.0.
Random copolymerized polypropylene polymer of 93 parts by weight, a Vicat softening point of 43 ° C., and a surface hardness of 77, an ethylene-butene-based binary copolymer elastomer having a weight of 10 parts by weight in the same manner as in Example 1. A non-stretched film was obtained. Table 2 shows the properties of the obtained film.

The film obtained in this comparative example was inferior in impact resistance, resistance to aerated boil and long-term storage stability, and was of low quality.

Example 5 The procedure of Example 1 was repeated, except that a ternary random copolymer elastomer having a Vicat softening point of 44 ° C., a surface hardness of 70, and MI = 6.0 was used. In the same manner as in Example 1, a polypropylene-based laminated unstretched film was obtained. Table 2 shows the properties of the obtained film. The film obtained in this example was also of high quality.

Example 6 The procedure of Example 1 was repeated, except that the ethylene content and MI of the ethylene random copolymerized polypropylene polymer were changed to 6.5% by weight and 5.5, respectively. With this, a polypropylene-based composite unstretched film was obtained. Table 2 shows the properties of the obtained film.
Shown in The film obtained in this example was also of high quality.

[0068]

[Table 1]

[0069]

[Table 2]

[0070]

The polypropylene-based laminated unstretched film according to claim 1 is excellent in low-temperature heat sealability and impact resistance, and can be stored for a long period of time.
There is little decrease in lamination characteristics when laminated with other films.

The polypropylene-based laminated unstretched film described in claim 2 is particularly excellent in low-temperature heat sealability, low-temperature impact resistance, and hot-water sealability.

The polypropylene-based laminated unstretched film according to the third aspect is excellent in heat-resistant water sealability that can withstand severe treatments such as a boiling water treatment and a retort treatment, particularly extremely severe treatments such as a boil treatment.

The polypropylene-based laminated unstretched film according to the fourth aspect is particularly excellent in low-temperature heat sealability and low-temperature impact resistance.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Katsuro Kuze 344 Maehata, Kizu-Cho, Inuyama, Aichi Prefecture Inside the Inuyama Plant of Toyobo Co., Ltd. (72) Inventor Satoshi Nori 10-24, Toyocho, Tsuruga-shi, Fukui Prefecture Tsuruga Film Co., Ltd.

Claims (4)

[Claims] 1. An ethylene block copolymerized polypropylene polymer having an ethylene content of 5 to 15% by weight based on 100 parts by weight of an ethylene random copolymerized polypropylene polymer having an ethylene content of 2 to 8% by weight. Layer containing 2 parts by weight, ethylene content is 2-8% by weight
1 to 15 parts by weight of a polyolefin-based random copolymer elastomer with respect to 100 parts by weight of an intermediate layer composed of an ethylene random copolymerized polypropylene polymer and 100 parts by weight of an ethylene random copolymerized polypropylene polymer having an ethylene content of 2 to 8% by weight. A laminated non-stretched polypropylene-based film, characterized by sequentially laminating a seal layer containing the same. 2. The method according to claim 1, wherein the intermediate layer has an ethylene content of 2 to 8.
2. A polypropylene mixture according to claim 1, wherein the mixture is a polymer mixture in which 1 to 15 parts by weight of a polyolefin random copolymer elastomer is blended with respect to 100 parts by weight of an ethylene random copolymerized polypropylene polymer which is 100% by weight. Laminated unstretched film. 3. The unstretched polypropylene-based film according to claim 1, wherein the polyolefin-based random copolymer elastomer is a copolymer composed of ethylene, propylene and butene. 4. The polyolefin random copolymer elastomer has a Vicat softening point of 70 ° C. or lower, and
A surface hardness of 80 or less,
4. The polypropylene-based laminated unstretched film according to 2 or 3.