JPH09131837A - Polyprolylene laminated film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film having a relatively low cost, excellent film manufacturing properties, transparency, heat resistance, flexibility and impact resistance at low temperatures using syndiotactic polypropylene. SOLUTION: The polypropylene laminated film is obtained by laminating a base material layer of crystalline polypropylene of copolymer of single polymer of propylene having syndiotactic pentade fraction of 0.6 or more or propylene and a small quantity of other olefin, and isotactic polypropylenes on both the surfaces of the base material layer in such a manner that the thickness of the base material layer to the thickness of the entire layer is 50 to 95%. Or, the polypropylene laminated film is obtained by laminating isotactic polypropylenes each having a ratio of weight-average-molecular weight(Mw)/ number-average-molecular weight(Mn) of 4.5 or less on both the surfaces of the base material layer as resin composition containing ethylene-octene copolymer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polypropylene laminated film, more specifically, film-forming property, transparency, heat resistance,
It is a film with good flexibility, impact resistance, and anti-blocking properties. Especially when used for retort applications, it has good transparency and flexibility after retort processing, and it can be used favorably, and it can also be used as a chemical or daily sundries. In particular, the present invention relates to a polypropylene laminated film which has good impact resistance and can be suitably used even when stored at a low temperature in packaging, food packaging, etc., and can also be suitably used for fiber packaging applications because it has good flexibility.

[0002]

2. Description of the Related Art Generally, isotactic polypropylene is used in a wide variety of applications because it is relatively inexpensive and excellent in rigidity, heat resistance, appearance of molded products and moldability.
For example, in the field of film, it is widely used for non-food packaging such as food packaging and textiles, chemicals, daily sundries, paper products, shopping bags, etc. In particular, the retort packaging bag where impact resistance and heat resistance of the film are important In food packaging including fields,
Propylene-ethylene block copolymer films have been preferably used.

When a propylene-ethylene block copolymer is used, it is easy to take out the filler in the high temperature retort sterilization without fusion or deformation of the films. However, it is known that the propylene-ethylene block copolymer has remarkably poor transparency and poor flexibility.

Also, when a propylene-ethylene random copolymer is used, it is easy to take out the filling material and the transparency is good without the fusion and deformation of the films in the retort sterilization at high temperature. However, propylene-
In the case of an ethylene random copolymer, it is known that the Young's modulus after retort treatment largely increases and the flexibility is lost.

Further, especially in the case of drug solution packaging, daily sundries packaging and food packaging where transparency of the film, impact resistance at low temperature, anti-blocking property in heat treatment and summer are important, propylene homopolymer. Film and propylene
Ethylene random copolymer films have been used with preference. Recently, use as a soft polyolefin film, which substitutes for vinylon, whose physical properties change depending on the season, has been studied.

When a propylene homopolymer is used, it is inexpensive and excellent in moldability, especially in antiblocking property. However, it is known that a propylene homopolymer is not sufficiently transparent and has poor flexibility and impact resistance at low temperatures.

When a propylene-ethylene random copolymer is used, the transparency, flexibility and impact resistance improve as the ethylene content increases. However, even in the case of a propylene-ethylene random copolymer, the flexibility and impact resistance are insufficient, and by increasing the ethylene content or adding an elastomer, the flexibility,
Although the impact resistance is improved, there are problems that the anti-blocking property is lost at high temperatures such as in summer, and the transparency becomes poor.

On the other hand, the existence of syndiotactic polypropylene has been known for a long time, but the conventional method of low-temperature polymerization with a catalyst composed of a vanadium compound, an ether and an organic aluminum has a poor syndiotacticity and is syndiotactic. It was hard to say that the characteristics of tic polypropylene were exhibited.

On the other hand, J. A. EWEN et al. Have found that a catalyst comprising a transition metal catalyst component having an asymmetric ligand and an aluminoxane can also provide a polypropylene having a good tacticity such that the syndiotactic pentad fraction exceeds 0.7. J, Am.Ch
em. Soc., 1988, 110, 6255-6256).

An extruded sheet, a film and an inflation film made of this syndiotactic polypropylene having excellent transparency have also been proposed (Japanese Patent Laid-Open No. 3-8112).
No. 8 and No. 3-81130), the use thereof is expected as a polypropylene excellent in transparency and heat resistance.

[0011]

However, the film obtained by molding the syndiotactic polypropylene obtained by the above-mentioned method by the T-die extrusion molding method or the tubular extrusion molding method is made of isotactic polypropylene. Compared to the resulting film, anti-blocking property is insufficient depending on tacticity,
Therefore, blocking may occur at high temperatures such as in summer. Also, syndiotactic polypropylene is formed into a film at a practical forming speed because the film sticks to the cooling roll and the winding roll during film formation, or the wound films stick to each other and become difficult to peel off. There was a problem that it was difficult.

Various nucleating agents are added to improve moldability and anti-blocking property at high temperature (Japanese Patent Laid-Open No. 3-54).
No. 238), and a study of laminating isotactic polypropylene and syndiotactic polypropylene in two layers to improve film forming property (Japanese Patent Laid-Open No. 5-200795).
However, it was insufficient in terms of film forming property and heat resistance.

The object of the present invention is to solve the above-mentioned problems and to provide a relatively inexpensive film-forming property, transparency, heat resistance, flexibility,
It is a film with good impact resistance at low temperatures, especially when used for retort applications, it is suitable because it has good transparency and flexibility after retort treatment, and anti-blocking at high temperatures such as summer An object of the present invention is to provide a polypropylene laminated film which has good properties and is suitable for use in drug solutions, general sundries, and food packaging, and also has good flexibility, and is therefore suitable for fiber packaging.

[0014]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to solve the above-mentioned problems, and as a result, by laminating isotactic polypropylene on both surfaces of a base material layer made of syndiotactic polypropylene, relatively Inexpensive, film forming, transparency, heat resistance, flexibility, impact resistance,
They have found that the film has good anti-blocking properties, and completed the present invention.

That is, according to the present invention, both surfaces of a base material layer made of a propylene homopolymer having a syndiotactic pentad fraction of 0.6 or more or a copolymer of propylene and a small amount of other olefins are provided. It is a polypropylene laminated film in which the thickness of the base material layer is 50 to 95% of the thickness of the entire layer formed by laminating isotactic polypropylene. The Young's modulus of the polypropylene laminated film before and after the retort treatment is 80 kg / mm.
A polypropylene laminated film having a number of ² or less. The present invention also relates to 100 parts by weight of crystalline polypropylene, which is a homopolymer of propylene having a syndiotactic pentad fraction of 0.6 or more, or a copolymer of propylene and a small amount of other olefin, and ethylene-octene copolymer. A polypropylene laminated film comprising a polypropylene resin composition comprising 10 to 100 parts by weight of a polymer as a base material layer, and isotactic polypropylene having Mw / Mn of 4.5 or less on both surfaces thereof. The thickness of the base material layer is 50 to 95% of the thickness of the polypropylene laminated film. Further, the polypropylene laminated film has a haze of 2.5% or less, a Young's modulus of 60 kg / mm ² or less, and an impact resistance at 5 ° C. of 50 kg · cm / mm or more.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a crystalline polypropylene having a high stereoregularity having a syndiotactic pentad fraction of 0.60 or more as measured by ¹³ C-NMR can be preferably used. Further, a mixture of isotactic polypropylene and syndiotactic polypropylene may be used. In this case, preferred crystalline polypropylene is syndiotactic polypropylene or a copolymer of syndiotactic polypropylene, or 0 to 200 parts by weight of isotactic polypropylene or isotactic polypropylene with respect to 100 parts by weight of the polymer. What mixed the copolymer of these is illustrated.

As the crystalline polypropylene, not only a propylene homopolymer having a syndiotactic polypropylene structure but also a copolymer of propylene and ethylene or an α-olefin having 4 or more carbon atoms can be used.
The content of ethylene or α-olefin having 4 or more carbon atoms as the other olefin in the copolymer is preferably 6 parts by weight or less.

As the catalyst used for producing the syndiotactic polypropylene or the copolymer, in addition to the compounds described in the above-mentioned documents, JP-A-2-41303, JP-A-2-41305 and JP-A-3-41305 can be used. -1790
05, JP-A-3-179006, JP-A-4
Examples of the catalyst include a bridged transition metal compound having asymmetric ligands and a cocatalyst as described in JP-A-69394, but even if the catalyst has a different structure, ¹³ C- Any polypropylene can be used as long as it can produce polypropylene having a syndiotactic pentad fraction of 0.6 or more as measured by NMR.

The use ratio of aluminoxane to the transition metal catalyst is 10 to 1,000,000 mole times, usually 50.
５5000 mol times. The polymerization conditions are not particularly limited, and a solvent polymerization method using an inert medium, a bulk polymerization method in which substantially no inert medium exists, or a gas phase polymerization method can be used. The polymerization temperature is -100 to 200 ° C,
The polymerization pressure is generally atmospheric pressure to 100 kg / cm ² -G. Preferably 0 to 100 ° C, normal pressure to 5
0 kg / cm ² -G.

As for the molecular weight of these crystalline polypropylenes, the one having a relatively high molecular weight of 0.01 to 100, preferably 0.05 to 50, which has a relatively high molecular weight as measured at 230 ° C. In terms of

As the ethylene-octene copolymer in the present invention, a copolymer obtained by copolymerizing ethylene and octene can be used, and the octene content is preferably 15 to 40 wt%.

The ethylene-octene copolymer according to the present invention has a molecular weight of MI of 0.05 to 70 g / 10 m.
in is preferable, and more preferably 0.5 to 30.
g / 10 min. The density is 0.8
It is preferably 1 to 0.96 g / cm ³ , more preferably 0.85 to 0.93 g / cm ³ .

As the catalyst for producing the ethylene-octene copolymer in the present invention, those containing metallocene as a main component as described in US Pat. No. 5,278,272 can be used, and the kind of octene is particularly limited. Without doing, 1-octene, 2-octene, 3-octene, 4-
Both chain octene such as octene and other branched octenes can be used. Among them, 1-octene is preferable.

The addition ratio of the ethylene-octene copolymer in the present invention to 100 parts by weight of crystalline polypropylene containing syndiotactic polypropylene as a main component is 10 to 100 parts by weight, preferably 15 to 90 parts.
Parts by weight, more preferably 20 to 80 parts by weight. When the amount of the ethylene-octene copolymer added exceeds 100 parts by weight, the transparency is deteriorated, and when it is less than 10 parts by weight, the effect of improving flexibility and impact resistance at low temperature is insufficient.

As a method for obtaining a polypropylene resin composition comprising the above-mentioned ethylene-octene copolymer and crystalline polypropylene having syndiotactic polypropylene as a main component, it can be obtained by uniformly dispersing it by any known method. For example, there are an extrusion melt blending method and a Banbury blending method.

In the polypropylene resin composition used in the present invention, if necessary, known additives such as antiblocking agents, antistatic agents, lubricants, crystal nucleating agents, ultraviolet absorbers, heat stabilizers and weather resistance stabilizers. , Radiation resistant agents, pigments, dyes and the like may be added.

As the isotactic polypropylene used as the surface layer in the present invention, a known propylene homopolymer such as commercially available propylene homopolymer, ethylene-
Although both a propylene block copolymer and a crystalline ethylene-propylene random copolymer can be used, excellent transparency is obtained by using a crystalline ethylene-propylene random copolymer or a propylene homopolymer. It is possible to obtain a polypropylene laminate. More preferably, Mw / Mn, which is an index of the molecular weight distribution measured by GPC (gel permeation chromatography), is 4.5 or less. For example, JP-A-61-130314 and JP-A-3-13406 are disclosed. When using isotactic polypropylene having a molecular weight distribution narrowed by thermal degradation or the like, which is produced by using a catalyst containing a so-called metallocene compound as a main component as described in It is possible to obtain a polypropylene laminated film having excellent transparency and gloss.

Further, the isotactic polypropylene used as the surface layer has Mw / Mn of 4.5 or less, and when Mw / Mn exceeds 4.5, the transparency is not improved.

In the isotactic polypropylene used in the present invention, if necessary, known additives such as antiblocking agents, antistatic agents, lubricants, crystal nucleating agents, ultraviolet absorbers, heat stabilizers and weathering stabilizers. , Anti-radiation agent, pigment,
A dye or the like may be added.

The polypropylene laminated film of the present invention comprises
By using syndiotactic polypropylene in the center layer of a certain specific thickness, a film having excellent film-forming properties, transparency, heat resistance, and flexibility can be obtained, and even when a retort is used, a retort treatment ( Young's modulus of 80 kg / mm ² before and after pressurized hot water sterilization)
The following flexibility can be maintained: On the other hand, a general isotactic polypropylene film is inferior in transparency even if the Young's modulus is 80 kg / mm ² or less before the retort treatment, and the Young's modulus is 100 kg / mm ² due to crystallization after the retort treatment. It becomes close and cannot maintain flexibility.

Further, 100 parts by weight of syndiotactic polypropylene and ethylene-octene copolymer 10 to 1
By using a polypropylene resin composition consisting of 100 parts by weight for the central layer of a certain specific thickness, a film having good transparency, flexibility and impact resistance at low temperature can be obtained, and the molecular weight distribution in the surface layer is high. By using the isotactic polypropylene specified above, it has excellent heat resistance such as anti-blocking property at high temperature and has a haze of 2.5 or less and Young's modulus of 60 kg / mm ² or less, 5 ° C.
A polypropylene laminated film having impact resistance of 50 kg · cm / mm or more. On the other hand, in the case of a general isotactic polypropylene film, if the anti-blocking property at high temperature is maintained, the transparency is poor due to an increase in the amount of the AB agent, and if the flexibility and impact resistance are to be maintained,
The transparency and anti-blocking property at high temperature cannot be maintained.

The polypropylene laminated film of the present invention comprises
It can be obtained by a known film production method such as a T-die method or a tubular method, and the following lamination methods are possible. (1) Syndiotactic polypropylene base layer,
A method in which isotactic polypropylene is used as a surface layer and a two-kind three-layer film is formed by intra-die or outside-die adhesive type two-kind three-layer coextrusion die, and if necessary, at least uniaxially or biaxially stretched. (2) First, isotactic polypropylene is extruded and laminated in a molten state on one side surface of a syndiotactic polypropylene film which is a base material layer, and isotactic polypropylene is extruded and laminated in a molten state on the opposite side surface. A method of using a seed trilayer film. (3) A method of forming a two-kind three-layer film by laminating an isotactic polypropylene film on both side surfaces of a syndiotactic polypropylene film which is a base material layer with an adhesive.

In particular, in the method (1), the film adheres to a cooling roll or a winding roll during film formation, or the wound films stick to each other and are difficult to peel off.
The problem that roll marks are generated by the wrinkle removing roll can be solved, and the moldability is excellent, which is preferable.

The thickness of the laminated film of the present invention is defined up to the range of the thickness of general sheets and films, and is 2 to
It is generally in the range of 0.001 mm, the syndiotactic polypropylene layer is 50% or more to 95% or less, preferably 60% to 95% or less, and more preferably 70% or more of the total layer. ~ 95% or less.

When the ratio of the thickness of the syndiotactic polypropylene layer to the total layers is less than 50%, there is no effect of improving flexibility before and after retort treatment and impact resistance at low temperature.

The upper limit of the ratio of the thickness of the syndiotactic polypropylene layer to all layers depends on the temperature conditions for the retort sterilization treatment, the temperature conditions requiring antiblocking property, the required flexibility and the impact resistance at low temperature. Although it is determined, the larger the flexibility and the impact resistance, the better as long as the heat resistance and the anti-blocking property are not lost, but it is usually 95% or less. Specifically, when the total thickness of the isotactic polypropylene layer in the three-layer laminated film is 3 μm or more, it is preferable in terms of moldability and antiblocking property.

The laminated film of the present invention can be widely used for non-food packaging such as food packaging and textiles, chemicals, daily sundries, paper products, shopping bags, etc., and particularly, impact resistance and heat resistance of the film. Retort food packaging bags and medical infusion bags, where importance is attached to the product, as well as food packaging bags and drug solutions bags where daily transparency and impact resistance at low temperatures are important, daily sundries packages, and flexibility. It can also be used for fiber packaging where

[0038]

The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto. In the examples, each measurement item was measured based on the following method. (1) Melt flow index: ASTM-D123
Compliant with 8. (2) Film-forming property: At the time of film-forming, adhesion to a cooling roll, blocking after film-forming, and post-shrinkage were evaluated as ○, and in some cases as ×. (3) Haze: According to ASTM-D1003. (4) Young's modulus: According to ASTM-D882. (5) Yield point stress: According to ASTM-D882. (6) Heat shrinkage rate: It was kept in an atmosphere of 120 ° C. for 30 minutes and conformed to JIS-K6782. (7) Retort sterilization process: Laminated body 10 cm x 20 cm
After cutting, retort treatment in pressurized water at 120 ° C for 30 minutes, and cooling, ○: No blocking between roll surface and roll surface, or between non-roll surface and non-roll surface of film; Is x. Also,
The haze, Young's modulus, and yield stress after the treatment were measured by the methods (3), (4), and (5). (8) Impact resistance: According to ASTM-D3420 at 5 ° C. (9) Anti-blocking property: Two roll surfaces and a non-roll surface of a film cut into a predetermined size are overlapped, a load of 20 g / cm ^{2 is} applied, and the film is left in a thermostatic chamber at 50 ° C. The film was taken out and the contact area ratio of the film was visually determined.

Reference Example Obtained by substituting an autoclave having an internal volume of 200 liters with propylene, lithiating isopropylpentadienyl-1-fluorene synthesized according to a conventional method, reacting it with zirconium tetrachloride and recrystallizing it. Isopropyl (cyclopentadienyl-1
0.2 g of fluorenyl) zirconium dichloride and methylaminoxan (manufactured by Tosoh Akzo Co., Ltd.)
6.1) Charge 30 g and then add 40 g of liquid propylene
Then, the temperature was raised to 60 ° C., polymerization was carried out at that temperature for 1 hour, then 1 kg of methanol was charged to demineralize, then unreacted propylene was purged and filtered to obtain 20.0 kg.
Of syndiotactic polypropylene was obtained. According to ¹³ C-NMR, this polypropylene has a syndiotactic pentad fraction of 0.793 and a melt flow index (hereinafter referred to as MI) of 4.5 g / 10.
The ratio of the weight average molecular weight to the number average molecular weight measured with 1,2,4 trichlorobenzene (hereinafter referred to as Mw / Mn) was 2.4.

Example 1 Syndiotactic polypropylene 10 obtained in Reference Example
Pellets containing 0.20 parts by weight of a phenolic antioxidant and 0.05 parts by weight of calcium stearate (hereinafter abbreviated as SPP-1) with respect to 0 parts by weight are melted with an extruder of 50 mmφ and the resin temperature is 230 ° C. Then, it was fed to the in-die adhesive type 2 type 3 layer coextrusion die. On the other hand, using another 40 mmφ extruder, isotactic polypropylene homopolymer (MI
= 4.6, Tm = 160.4 ° C., Mitsui Toatsu Chemical Co., Ltd. trade name Mitsui Noblen JH-G, hereinafter abbreviated as IPP-1) was melted and supplied to the die at a resin temperature of 230 ° C. . A mirror surface roll was used for film formation, but a laminated film having a thickness ratio of IPP-1 layer / SPP-1 layer / IPP-1 layer of 1/8/1 and a thickness of 60 μm was used without any problem in film formation. Obtained. Table 1 shows the physical properties of the film.

Example 2 IPP-1 layer / SPP-1 layer / IPP-1 in Example 1
Example 1 except that the thickness ratio of the layers was 0.5 / 9 / 0.5
And a laminated film was obtained without any problems in film formation. Table 1 shows the physical properties of the film.

Example 3 IPP-1 layer / SPP-1 layer / IPP-1 in Example 1
The same procedure as in Example 1 was carried out except that the layer thickness ratio was changed to 1/2/1 to obtain a laminated film without any problems in film formation. Table 1 shows the physical properties of the film.

Comparative Example 1 In order to compare the film-forming properties with those of Examples 1 to 3, SPP-1 was melted and supplied to a single-layer film die at a resin temperature of 240 ° C. to form a film. In that case, the film could not be formed, and a 60 μm single layer film was formed using a satin roll. Adhesion of the film to the cooling roll was observed during film formation. Also, the film was sticking to each other after being wound up.
Table 1 shows the physical properties of the film.

Comparative Example 2 The SPP-1 used in Example 1 was melted by an extruder having a diameter of 50 mm and supplied to a die-externally bonded two-kind two-layer coextrusion die at a resin temperature of 230 ° C. On the other hand, IPP-1 in Example 1 was melted with another 40 mmφ extruder and supplied to the die at a resin temperature of 230 ° C. For film formation, a mirror-finished roll was used to obtain a laminated film having a thickness ratio of IPP-1 layer / SPP-1 layer of 2/8 and a thickness of 60 μm, but blocking and post-shrinkage were observed after film formation. Table 1 shows the physical properties of the film.

Comparative Example 3 IPP-1 layer / SPP-1 layer / IPP-1 in Example 1
Example 1 except that the thickness ratio of the layers was set to 3.5 / 3 / 3.5.
A laminated film was obtained in the same manner as above, without any problems in film formation, but had a high Young's modulus before and after the retort sterilization treatment, and the touch was not good. Table 1 shows the physical properties of the film.

Comparative Example 4 To compare the flexibility of Example 1 with that before and after the retort treatment,
Instead of SPP-1, isotactic ethylene-propylene binary polymer (MI = 8.0 g / 10 min, ethylene unit content 4.2 wt%, manufactured by Mitsui Toatsu Chemicals, Inc.)
Product name Mitsui Noblen EFL-560, hereinafter IPP-
(Abbreviated as 2) was performed in the same manner as in Example 1 to obtain a laminated film without any problems in film formation, but the Young's modulus after the retort sterilization treatment remarkably increased. Table 1 shows the physical properties of the film.

Example 4 A laminated film was obtained in the same manner as in Example 1 except that IPP-2 was used in place of IPP-1 in Example 1 without any problem in film formation. Table 1 shows the physical properties of the film.

Comparative Example 5 IPP-2 was used in place of IPP-1 in Example 1 and SP
A laminated film was obtained in the same manner as in Example 1 except that IPP-1 was used instead of P-1, but a Young's modulus was high, flexibility was impaired, and commercial value was obtained. There wasn't. Table 1 shows the physical properties of the film.

Example 5 Instead of SPP-1 in Example 1, 80 w of SPP-1 was used.
A laminated film was obtained in the same manner as in Example 1 except that a pellet mixture of 20% by weight of t% and 20% by weight of IPP-2 (hereinafter abbreviated as SPP-2) was used. Table 1 shows the physical properties of the film.

[0050]

[Table 1] Example 6 Syndiotactic polypropylene 10 obtained in Reference Example
Ethylene-octene copolymer (KC8852 manufactured by Dow Chemical Co., Ltd., MI = 3.0 (190
℃), density 0.875 g / cm ³ , octene content 2
2.0%) 50 parts by weight, phenolic antioxidant 0.0
Pellets containing 55 parts by weight and 0.1 parts by weight of a phosphorus-based antioxidant (hereinafter abbreviated as SPP-3) are melted with an extruder of 50 mmφ, and the resin temperature is 230 ° C. and the adhesive type in the die is two types and three layers simultaneously. It was fed to an extrusion die. On the other hand, using another 40 mmφ extruder, isotactic polypropylene homopolymer (MI
= 7.8, Tm = 158.7 ° C., Mw / Mn = 4.2)
100 parts by weight, 0.1 parts by weight of phenolic antioxidant,
A pellet (hereinafter abbreviated as IPP-3) containing 0.04 part by weight of a phosphorus-based antioxidant and 0.2 part by weight of spherical silica (SO-C5 manufactured by Admatechs Co., Ltd.) was melted, and the resin temperature was 230 ° C. To the die. Although a mirror surface roll was used for film formation, there was no problem in film formation and IPP-3 layer / SPP was used.
-3 layer / IPP-3 layer thickness ratio 1/8/1 thickness 60
A μm laminated film was obtained. Table 2 shows the physical properties of the film.

Example 7 IPP-3 layer / SPP-3 layer / IPP-3 in Example 6
Example 6 except that the layer thickness ratio was 0.5 / 9 / 0.5
And a laminated film was obtained without any problems in film formation. Table 2 shows the physical properties of the film.

Example 8 IPP-3 layer / SPP-3 layer / IPP-3 in Example 6
A laminated film was obtained in the same manner as in Example 6 except that the layer thickness ratio was set to 1/2/1, without any problems in film formation. Table 2 shows the physical properties of the film.

Comparative Example 6 In order to compare the film-forming properties with those of Examples 6 to 8, SPP-3 was melted and supplied to a single-layer film die at a resin temperature of 240 ° C. to form a film. In that case, the film could not be formed, and a 60 μm single layer film was formed using a satin roll. Adhesion of the film to the cooling roll was observed during film formation. Also, the film was sticking to each other after being wound up.
Table 2 shows the physical properties of the film.

Comparative Example 7 In order to compare the flexibility and impact resistance with Example 6, IPP-
3 was melted and supplied to a die for monolayer film at a resin temperature of 240 ° C. to form a 60 μm film. A monolayer film was obtained without any problems in film formation, but the flexibility and impact resistance were insufficient. Table 2 shows the physical properties of the film.

Comparative Example 8 In order to compare the flexibility and impact resistance with Example 6, a propylene-ethylene random copolymer (MI = 7.3, ethylene content = 4.2 wt%, Mw / Mn = 5. 3) 100
Pellets containing 0.1 part by weight, 0.1 part by weight of phenolic antioxidant, 0.04 part by weight of phosphorus antioxidant, and 0.2 part by weight of spherical silica (SO-C5 manufactured by Admatex Co., Ltd.) (hereinafter, Abbreviated as IPP-4), and the resin temperature 2
The film was fed to a monolayer film die at 40 ° C. to form a 60 μm film. A monolayer film was obtained without any problems in film formation, but the flexibility and impact resistance were insufficient. Table 2 shows the physical properties of the film.

Comparative Example 9 IPP-3 layer / SPP-3 layer / IPP-3 in Example 6
Example 6 except that the layer thickness ratio was 3.5 / 3 / 3.5
A laminated film was obtained without any problems in film formation, but the touch was poor, and the flexibility and impact resistance were reduced.
Table 2 shows the physical properties of the film.

Comparative Example 10 In order to compare the transparency with Example 6, propylene homopolymer (MI = 7.5, Tm = 15) was used instead of IPP-3.
9.6 ° C., Mw / Mn = 5.3) 100 parts by weight, phenol-based antioxidant 0.1 part by weight, phosphorus-based antioxidant 0.
04 parts by weight, spherical silica (S manufactured by Admatechs Co., Ltd.
Pellets containing 0.2 parts by weight of O-C5) (hereinafter referred to as IPP
Except that it is abbreviated as -5).
A laminated film was obtained without any problems in film formation, but the transparency was deteriorated. Table 2 shows the physical properties of the film.

[0058]

[Table 2] Example 9 The addition amount of the ethylene-octene copolymer in Example 6 was changed to 2
A laminated film was obtained in the same manner as in Example 6 except that the amount was 0 part by weight (hereinafter, abbreviated as SPP-4), without any problem in film formation. Table 3 shows the physical properties of the film.

Example 10 The amount of ethylene-octene copolymer added in Example 6 was 8
A laminated film was obtained in the same manner as in Example 6 except that the amount was 0 part by weight (hereinafter abbreviated as SPP-5), without any problem in film formation. Table 3 shows the physical properties of the film.

Comparative Example 11 The amount of ethylene-octene copolymer added in Example 6 was 0.
A laminated film was obtained in the same manner as in Example 6 except that the weight part was used (hereinafter abbreviated as SPP-6), and a laminated film was obtained without any problems in film formation, but the impact resistance was lowered. Table 3 shows the physical properties of the film.

Comparative Example 12 The amount of ethylene-octene copolymer added in Example 6 was adjusted to 1
A laminated film was obtained in the same manner as in Example 6 except that the amount was 50 parts by weight (hereinafter abbreviated as SPP-7), and a laminated film was obtained without any problems in film formation, but the transparency was deteriorated. Table 3 shows the physical properties of the film. Example 11 Instead of SPP-3 in Example 6, 80 w of SPP-1 was used.
A laminated film was obtained in the same manner as in Example 6 except that a pellet mixture of 20% by weight of t% and IPP-4 (hereinafter abbreviated as SPP-8) was used, and there was no problem in film formation. Table 3 shows the physical properties of the film.

[0062]

[Table 3]

[0063]

EFFECT OF THE INVENTION The polypropylene laminated film of the present invention is extremely excellent in film-forming property and transparency, and moreover, has flexibility before and after retort sterilization treatment, impact resistance at low temperature and anti-blocking property at high temperature. Excellent and extremely valuable industrially.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshito Imabayashi 1-6 Takasago, Takaishi-shi, Osaka Mitsui Toatsu Chemical Co., Ltd.

Claims (4)

[Claims] 1. A crystalline polypropylene, which is a homopolymer of propylene having a syndiotactic pentad fraction of 0.6 or more or a copolymer of propylene and a small amount of other olefins, is used as a base layer, and both surfaces are provided. A polypropylene laminated film obtained by laminating isotactic polypropylene on a substrate, wherein the thickness of the base material layer is 50 to 95% of the thickness of the entire layer. 2. Young's modulus before and after retort treatment is 80.
The polypropylene laminated film according to claim 1, which has a kg / mm ² or less. 3. 100 parts by weight of crystalline polypropylene, which is a homopolymer of propylene having a syndiotactic pentad fraction of 0.6 or more, or a copolymer of propylene and a small amount of other olefin, and ethylene-octene copolymer. A polypropylene resin composition composed of 10 to 100 parts by weight of a polymer is used as a base material layer, and a weight average molecular weight (M
A polypropylene laminated film obtained by laminating isotactic polypropylene having a ratio of w) / number average molecular weight (Mn) of 4.5 or less, wherein the thickness of the base material layer is 50 to 95 with respect to the thickness of the entire layer. % Polypropylene laminated film. 4. A haze of 2.5% or less and a Young's modulus of 60 k.
g / mm ² or less, impact resistance at 5 ° C is 50 kg · cm /
The polypropylene laminated film according to claim 3, which has a thickness of at least mm.