JP2002105277A - Low temperature heat-sealing polypropylene film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polypropylene film excellent in low temperature heat selalability, transparency and impact resistance, and provide a multilayer film made of the same. SOLUTION: The polypropylene film composed of a resin composition is composed of (C) a propylene copolymer of 40-95 wt.% consisting of (A) a copolymer component of 1-30 wt.% obtained by polymerization of propylene and ethylene and/or C>=4 α-olefin and having α-olefin contents of <1-15 mol.% and ethylene contents of <=5 mol.% and (B) a copolymer component of 70-90 wt.% obtained by polymerization of propylene and ethylene and/or C>=4 α-olefin and having α-olefin contents of >=15 mol.% but <=30 mol.% and ethylene contents of <=5 mol.%, and (D) a propylene-ethylene block copolymer of 5-60 wt.% having a xylene soluble component of >=50 wt.% and ethylene concentration of 14-35 mol.% in the soluble component.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a polypropylene film. More specifically, the present invention relates to a polypropylene film excellent in low-temperature heat sealability, transparency and impact resistance, and a multilayer film containing at least one layer of the film.

[0002]

2. Description of the Related Art Polypropylene is widely used in the fields of films and sheets because of its excellent transparency, heat resistance and food hygiene. In recent years, the speed of bag making has been increased in the field of packaging of foods and the like, and materials having good low-temperature heat sealability have been demanded.

As a polypropylene having a low-temperature heat-sealing property, for example, propylene and an α-olefin, or a propylene and an α-olefin, substantially in the absence of a solvent using a Ziegler-Natta catalyst described in Japanese Patent No. 2888237. In a random copolymer obtained by copolymerizing propylene, ethylene and an α-olefin, the propylene content, the ethylene content, the α-olefin content, and the 20 ° C. xylene-soluble portion of the random copolymer in the random copolymer A polypropylene random copolymer having a limited content is known. However, the polypropylene random copolymer having good low-temperature heat sealability described in the above-mentioned patent publication, that is, having a low seal temperature, has insufficient impact strength, and further improvement has been demanded.

Japanese Patent Application Laid-Open No. 9-320022 discloses that the ethylene content in the first step is 1.5 to 6.0% by weight.
40 to 85% by weight of ethylene-propylene copolymer part
Is produced, and an ethylene-propylene copolymer portion having an ethylene content of 7 to 17% by weight in the second step is 15 to 6% by weight.
Is a block copolymer obtained by forming, the intrinsic viscosity of the copolymer portion formed in the second step is in a specific range, the intrinsic viscosity of the copolymer portion formed in the second step and the first A polypropylene block copolymer having excellent flexibility, transparency, and low-temperature impact resistance in which the ratio of the intrinsic viscosity of the copolymer portion formed in the process is in a specific range is described. However, further improvement has been required for the low-temperature heat-sealing properties of the materials described in the above-mentioned patent publications.

[0005]

SUMMARY OF THE INVENTION The present invention provides a polypropyne-based film having excellent low-temperature heat sealability, transparency and impact resistance, and a multilayer film containing at least one layer of the film.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in view of the above-mentioned circumstances, and as a result, have found that the present invention can solve the above-mentioned problems. That is, in the present invention, in the first step, propylene and ethylene and / or α-olefin having 4 or more carbon atoms are obtained by polymerizing α-olefin having 4 or more carbon atoms.
Copolymer component (A) having an olefin content of less than 1 to 15 mol% and an ethylene content of 5 mol% or less
%, And then the content of α-olefins having 4 or more carbon atoms obtained by polymerizing propylene with ethylene and / or α-olefins having 4 or more carbon atoms in the second and subsequent steps is 15%.
Not less than 30 mol% and ethylene content of 5 mol%
40-95% by weight of a propylene-based copolymer (C) comprising 70-99% by weight of the following copolymer component (B), and a xylene-soluble component (CXS component) at 20 ° C.:5.
0% by weight or more, and a polypropylene-based resin composition comprising a resin composition containing 5 to 60% by weight of a propylene-ethylene block copolymer (D) in which the concentration of ethylene in a xylene-soluble component at 20 ° C is 14 to 35% by mole. Film (The total of component (A) and component (B) contained in copolymer (C) is 100% by weight, and copolymer (C) and copolymer (D) contained in the resin composition Is 100% by weight.) And a polypropylene-based multilayer film including at least one layer of the polypropylene-based film. Hereinafter, the present invention will be described in detail.

[0007]

DETAILED DESCRIPTION OF THE INVENTION The propylene copolymer (C) used in the present invention is a copolymer obtained by polymerizing propylene with ethylene and / or an α-olefin having 4 or more carbon atoms in the first step. Component (A) and then a copolymer component (B) obtained by polymerizing propylene with ethylene and / or an α-olefin having 4 or more carbon atoms in the second and subsequent steps.
And a copolymer consisting of: As the component (A), a copolymer component obtained by polymerizing propylene and an α-olefin having 4 or more carbon atoms is preferable. As the component (B), preferably, propylene and an α-olefin having 4 or more carbon atoms are used. It is a copolymer component obtained by polymerization.

The content of the component (A) is 1 to 30% by weight, preferably 5 to 30% by weight, more preferably 5 to 20% by weight. The content of the component (B) is from 70 to 99% by weight, preferably from 70 to 95% by weight, and more preferably from 80 to 95% by weight.

When the content of component (A) is less than 1% by weight (ie, when the content of component (B) exceeds 99% by weight),
In some cases, the properties of the powder at the time of polymerization are deteriorated and the productivity is reduced. When the content of the component (A) exceeds 30% by weight (that is, when the content of the component (B) is less than 70% by weight) ), The low-temperature heat sealability of the film may be insufficient.

[0010] α- having 4 or more carbon atoms contained in the component (A)
The olefin content is less than 1 to 15 mol%, preferably less than 5 to 15 mol%, more preferably 5 to 1 mol%.
0 mol%. When the content of the α-olefin having 4 or more carbon atoms contained in the component (A) is less than 1 mol%, the processability may be insufficient, and when the content is 15 mol% or more, the polymerization of the component (A) is stabilized. May be difficult to do.

[0011] α- having 4 or more carbon atoms contained in the component (B)
The olefin content is 15 to 30 mol%, preferably 15 to 25 mol%. Component (B)
When the content of α-olefins having 4 or more carbon atoms contained in is less than 15 mol%, the low-temperature heat sealability of the film may be insufficient, and when it exceeds 30 mol%, the stiffness (rigidity) of the film is low. May be.

The ethylene content of component (A) is at most 5 mol%, preferably at most 3 mol%. The ethylene content in the component (B) is 5 mol% or less,
It is preferably at most 3 mol%. If the amount of ethylene contained in the component (A) or the component (B) exceeds 5 mol%, the film may whiten over time or the stiffness (rigidity) may decrease.

The α-olefin having 4 or more carbon atoms contained in component (A) or component (B) includes, for example, 1-butene, 2-methyl-1-propene, 1-pentene, 2-pentene,
Methyl-1-butene, 3-methyl-1-butene, 1-hexene, 2-ethyl-1-butene, 2,3-dimethyl-
1-butene, 2-methyl-1-pentene, 3-methyl-
1-pentene, 4-methyl-1-pentene, 3,3-dimethyl-1-butene, 1-heptene, methyl-1-hexene, dimethyl-1-pentene, ethyl-1-pentene, trimethyl-1-butene, Methylethyl-1-butene, 1-octene, methyl-1-pentene, ethyl-1
-Hexene, dimethyl-1-hexene, propyl-1-
Heptene, methylethyl-1-heptene, trimethyl-
1-pentene, propyl-1-pentene, diethyl-
Examples thereof include 1-butene, 1-nonene, 1-decene, 1-undecene, and 1-dodecene, and are preferably 1-butene, 1-pentene, 1-hexene, and 1-octene. From the viewpoints of polymerization characteristics, economy, etc., they are 1-butene and 1-hexene.

The component (A) or component (B) includes, for example, propylene-1-butene copolymer component, propylene-1-hexene copolymer component, propylene-ethylene-1-butene copolymer component, propylene -Ethylene-1
-Hexene copolymer component and the like, and preferably a propylene-1-butene copolymer component and a propylene-1-hexene copolymer component. Component (A) and component (B) may be the same or different.

The propylene copolymer (C) used in the present invention includes, for example, (propylene-1-butene)
-(Propylene-1-butene) copolymer, (propylene-1-butene)-(propylene-ethylene-1-butene) copolymer, (propylene-ethylene-1-butene)
-(Propylene-1-butene) copolymer, (propylene-ethylene-1-butene)-(propylene-ethylene-
1-butene) copolymer, (propylene-1-hexene)
-(Propylene-1-hexene) copolymer and the like, preferably (propylene-1-butene)-(propylene-1-butene) copolymer, (propylene-1-hexene)-(propylene-1- Hexene) copolymer, more preferably (propylene-1-butene)-
(Propylene-1-butene) copolymer.

The production of the propylene copolymer (C) used in the present invention is carried out in a known polymerization method using a known polymerization method in a multistage polymerization comprising a first step, a second step and subsequent steps. Can be performed. Examples of the polymerization catalyst include a Ziegler-Natta type catalyst and a metallocene catalyst, and are preferably catalysts containing Ti, Mg, and halogen as essential components. For example, a Ti-Mg-based catalyst comprising a solid catalyst component obtained by complexing a Ti compound with a magnesium compound, and a catalyst system comprising the solid catalyst component and a third component such as an organic aluminum compound and, if necessary, an electron donating compound. For example, see JP-A-61-2
18606, JP-A-61-287904,
A catalyst system described in JP-A-7-216017 is exemplified.

The organoaluminum compound is not particularly limited, but is preferably triethylaluminum, triisobutylaluminum, a mixture of triethylaluminum and diethylaluminum chloride, and tetraethyldialumoxane.

The electron donating compound is not particularly limited, but is preferably cyclohexylethyldimethoxysilane, tert-butyl-n-propyldimethoxysilane, tert-butylethyldimethoxysilane, or dicyclopentyldimethoxysilane.

As the polymerization method, hexane, heptane,
Solvent polymerization using an inert solvent represented by hydrocarbon compounds such as octane, decane, cyclohexane, methylcyclohexane, benzene, toluene and xylene; bulk polymerization using a liquid monomer as a solvent; and gas polymerization in a gaseous monomer. A phase polymerization method and the like can be mentioned, and a bulk polymerization method or a gas phase polymerization method, in which post-treatment and the like are easy, is preferable. These polymerization methods may be a batch type or a continuous type.

The process for producing the propylene copolymer (C) used in the present invention is a process in which the polymerization is carried out in a multi-stage comprising a first step and subsequent steps in the above-mentioned polymerization method. The polymerization method of the first step and the polymerization method of the second and subsequent steps may be the same or different, and from the viewpoint that polymerization activity and post-treatment are easy, preferably the first step Is a step of performing polymerization in the absence of an inert solvent, and the second and subsequent steps are steps of performing polymerization in a gas phase. The polymerization in the first step and the polymerization in the second and subsequent steps may be performed in the same polymerization tank (reactor) or in different polymerization tanks (reactors).

The method for producing the propylene copolymer (C) used in the present invention includes, for example, a solvent-solvent polymerization method, a bulk-bulk polymerization method, a gas phase-gas phase polymerization method, and a solvent-gas phase polymerization method. , Bulk-gas-gas-phase polymerization method, solvent-gas-phase-gas-phase polymerization method, bulk-gas-phase-gas-phase polymerization method, and the like. Legal, bulk-gas-
It is a gas phase polymerization method.

The polymerization temperature in the first step is not particularly limited, but is usually 20 to 150 ° C., and is preferably 35 from the viewpoint of productivity and controlling the contents of the components (A) and (B). ９５95 ° C. The polymerization temperature in the second and subsequent steps may be the same as or different from the polymerization temperature in the first step, but is usually 20 to 150 ° C, preferably 35 to 9 ° C.
5 ° C.

In the method for producing the propylene-based copolymer (C) used in the present invention, if necessary, post-treatment such as deactivation of the catalyst, desolvation, demonomerization, drying and granulation may be carried out. Is also good.

The propylene-ethylene block copolymer (D) described in the present invention includes a repeating unit derived from propylene (hereinafter referred to as "propylene repeating unit") and a repeating unit derived from ethylene. (Hereinafter, referred to as “ethylene repeating unit”), a copolymer portion (X portion) randomly bonded, and a copolymer in which a propylene repeating unit and an ethylene repeating unit having a structure different from the aforementioned X portion are randomly bonded. Merging part (Y
(Propylene-ethylene)-(propylene-ethylene) block copolymer.

The xylene-soluble component (CXS component) at 20 ° C. of the propylene-ethylene block copolymer (D) used in the present invention is at least 5.0% by weight, preferably 5.0 to 40%. % By weight. 5% by weight of CXS component
If less than, low-temperature heat sealability is insufficient,
Impact resistance may be poor.

The concentration of ethylene in the xylene-soluble component (CXS component) at 20 ° C. of the propylene-ethylene block copolymer (D) used in the present invention is 14 to 35 mol%.
It is. Concentration of ethylene in CXS component is 14mol%
When the amount is less than the above, the low-temperature heat-sealing property may be insufficient, and when it exceeds 35 mol%, the transparency may decrease.

The intrinsic viscosity [η] of the xylene-soluble component (CXS component) at 20 ° C. of the propylene-ethylene block copolymer (D) used in the present invention [η] ^(D) _CXS is preferred from the viewpoint of transparency. Is not more than 2.0 dl / g.

The ethylene content of the X part of the propylene-ethylene block copolymer (D) used in the present invention is as follows:
From the viewpoint of low-temperature heat sealability or stable production of the propylene-ethylene block copolymer (D), the content is preferably 2.0 to 9.0 mol%, more preferably 4.0 to 7.0 mol%. .

The content of the X portion of the propylene-ethylene block copolymer (D) used in the present invention is preferably from the viewpoint of low-temperature heat sealability or stable production of the propylene-based block copolymer (D). Is 40 to 85% by weight, more preferably 45 to 80% by weight.

The ethylene content of the Y portion of the propylene-ethylene block copolymer (D) used in the present invention is as follows:
From the viewpoint of low-temperature heat sealability, preferably 10.0 to
24.0 mol%, more preferably 11.5 to
21.0 mol%.

The content of the Y portion of the propylene-ethylene block copolymer (D) used in the present invention is preferably from the viewpoint of low-temperature heat sealability or stable production of the propylene-based block copolymer (D). Is 15 to 60% by weight, more preferably 20 to 55% by weight.

The intrinsic viscosity [η] ^(D) of the Y portion of the propylene-ethylene block copolymer (D) used in the present invention.
_{Y part} is the amount of solvent extraction components, that is, food hygiene, or
From the viewpoint of transparency, preferably 2.0 to 5.0 dl / g.
And more preferably 2.5 to 4.5 dl / g.

The intrinsic viscosity ([η] ^(D) of the Y portion of the propylene-ethylene block copolymer (D) used in the present invention.
The intrinsic viscosity of the _{Y part)} and X moiety ^{([η] (D)} _{X part)} and the ratio of ^{([η] (D)} _{Y parts} / [η] ^(D) _{X portion),} the low-temperature heat sealability, food hygiene From the viewpoint of the balance between the transparency and the transparency, preferably 0.5 ≦ [η] ^(D) _{Y portion} / [η] ^(D) _{X portion} ≦ 1.8.

The method for producing the propylene-ethylene block copolymer (D) used in the present invention is not particularly limited, and includes a method using a generally known catalyst. And the method described in JP-A-200421. As the polymerization catalyst, the organic aluminum compound and the electron donating compound, for example,
Examples thereof include those used in the production of the propylene-based copolymer (C).

The method for polymerizing the propylene-ethylene block copolymer (D) used in the present invention is not particularly limited, and for example, the method used in the production of the propylene-based copolymer (C) described above. And
Preferably, it is a gas phase polymerization method, and it may be produced by a one-stage polymerization method or may be produced by a two-stage or more multi-stage polymerization method.

In the method for producing the propylene-ethylene block copolymer (D) used in the present invention, as in the case of the propylene-based copolymer (C), if necessary, post-treatment such as deactivation of the catalyst may be carried out. Desolvation, demonomerization, drying, granulation and the like may be performed.

The propylene copolymer (C) and propylene-ethylene block copolymer (D) used in the present invention have a melt flow rate (M) measured at 230 ° C.
FR) is preferably from 0.1 to 50 g / 10 min, more preferably from 1 to 20 g / 10 min, from the viewpoint of fluidity or film-forming properties.

The resin composition used in the present invention comprises 40 to 95% by weight of a propylene-based copolymer (C) and 5 to 60% by weight of a propylene-ethylene block copolymer (D). Preferably, it is composed of 60 to 95% by weight of a propylene-based copolymer (C) and 5 to 40% by weight of a propylene-ethylene block copolymer (D).

When the content of the propylene-based copolymer (C) in the resin composition used in the present invention is less than 40% by weight (the content of the propylene-ethylene block copolymer (D) exceeds 60% by weight) Case), the low-temperature heat-sealing property may be insufficient, and the content of the propylene-based copolymer (C) exceeds 95% by weight (the content of the propylene-ethylene block copolymer (D) is 5% by weight). %), The impact resistance may be insufficient.

The method for producing the resin composition used in the present invention is not particularly limited. For example, a propylene-based copolymer (C) and a propylene-ethylene block copolymer (D) which are separately polymerized are dried. A method of blending, a method of solution mixing, a method of melt kneading, and the like can be given.

The melt flow rate (MFR) of the resin composition used in the present invention can be changed by a known method during melt kneading, and by changing the melt flow rate (MFR) of the resin composition, The flow properties of the composition can be adjusted. Melt flow rate (M
As a method for changing the FR), for example, an organic peroxide may be added to the propylene-based copolymer (C) and / or the propylene-ethylene block copolymer (D) as long as the object and effects of the present invention are not impaired. And the like.

[0042] Additives and other resins may be added to the resin composition used in the present invention as long as the objects and effects of the present invention are not impaired. As additives, for example, antioxidants, ultraviolet absorbers, antistatic agents, lubricants, nucleating agents,
Adhesives, antifogging agents and the like are included.

Examples of other resins include ethylene resins, butene resins, petroleum resins, and styrene resins. From the viewpoint of high-speed film-forming properties, high-density polyethylene resin can be added at 5% by weight or less, and from the viewpoint of adhesive properties, ethylene-methyl (meth) acrylate resin can be added at 5% by weight or less. it can.

As a method for producing the film of the present invention, a method of forming a film alone using a commonly used inflation method, T-die method, calendar method, or the like,
A method of forming a film as at least one layer of a multilayer structure with a different resin may be used. Examples of the method for forming a multilayer include an extrusion lamination method, a heat lamination method, a dry lamination method, and the like, which are usually used. Further, a method of stretching a film or sheet obtained by molding in advance to produce a film, as a stretching method, for example,
Examples include a method of uniaxially or biaxially stretching by a roll stretching method, a tenter stretching method, a tubular stretching method, or the like. From the viewpoint of balance of physical properties such as low-temperature heat sealability, transparency, and rigidity of the film, an unstretched coextrusion molding method or a biaxial stretching method is preferable.

[0045]

EXAMPLES The present invention will be described in detail with reference to examples and comparative examples, but the present invention is not limited to the examples. The physical properties described in Examples and Comparative Examples were measured by the following methods.

(1) Content (unit:% by weight) of copolymer component (A) and component (B) contained in propylene copolymer (C) was determined from the material balance. (2) 1-butene content (unit: mol%) contained in the copolymer components (A) and (B) Polymer Handbook (1995, published by Kinokuniya Bookstore)
The IR spectrum measurement described on page 619 was performed to determine the content of 1-butene contained in the component (A) and the propylene-based copolymer (C). Component (B)
The content of 1-butene in the components (A) and (B)
And the 1-butene content of the component (A) and the propylene-based copolymer (C) were calculated by the following equation. (1-Phtene content in the component (B)) = ((Propylene copolymer (C)
1-pentene content) × 100− (1-pentene content in component (A)) × (content of component (A)) / (content of component (B))

(3) Intrinsic viscosity [η] (unit: g / dl) Reduced viscosities were measured at three concentrations of 0.1, 0.2 and 0.5 g / dl using an Ubbelohde viscometer. The temperature was measured at 135 ° C. using tetralin as a solvent. The limiting viscosity is "Polymer solution, experimental polymer chemistry 11"
(1982 Kyoritsu Shuppan Co., Ltd.), page 491, that is, the reduced viscosity was plotted against the concentration, and the extrapolation method was used to extrapolate the concentration to zero.

(4) Ethylene content (unit: mol%) of propylene-ethylene block copolymer (D) Polymer Handbook (1995, published by Kinokuniya Bookstore)
The measurement was carried out using the ¹³ C-NMR method described on page 616 of the above.

(5) Melt flow rate (MFR) (unit: g / 10 minutes) According to JIS K7210, temperature 230 ° C., load 2
1. Measured at 18N. (6) 20 ° C. xylene soluble component (CXS component) (unit:
5% by weight) After completely dissolving 5 g of the propylene-ethylene block copolymer (D) in 500 ml of boiling xylene, the temperature was lowered to 20 ° C, and the mixture was allowed to stand for 4 hours or more. Thereafter, this was separated into a precipitate and a solution by filtration, and the filtrate was dried under reduced pressure at 70 ° C., and the weight of the obtained dried product was measured.

(7) Haze (unit:%) Measured in accordance with JIS K7105. (8) Heat seal temperature (HST) (unit: ° C.) φ50 with 400 mm wide coat hanger type T-die
mm extruder, resin temperature 250 ° C, discharge rate 12Kg
/ hr, chill roll temperature 40 ° C, line speed 2
By cooling at 0 m / min by an air chamber cooling method, a 30 μm film was obtained. After the obtained film was stabilized at 23 ° C. for 24 hours or more, heat sealing was performed. The heat seal was performed using a thermal gradient tester manufactured by Toyo Seiki Co., Ltd. at intervals of 2 ° C., 15 mm width, and a gauge pressure of 2 kg / g.
cm ² for 2 seconds. The obtained film was allowed to stand at 23 ° C. for 24 hours or more, and then subjected to T-type peeling at 23 ° C. at a speed of 200 mm / min using a tensile tester to determine the heat seal strength, and a temperature of 300 g was determined.

(9) Impact strength (unit: kg-cm / m
m) Using a film impact tester manufactured by Toyo Seiki,
The impact strength of the film was measured at 15 ° C. using a 15 mm hemispherical impact head.

Example 1 Using a catalyst containing Ti, Mg and halogen as essential components, a propylene-1-butene copolymer having 1-butene content of 9.2 mol% was used in the first step at 9% by weight of the total amount. Polymerization was performed, and then in a second step, a propylene-based copolymer powder was obtained by polymerizing a propylene-1-butene copolymer portion having a 1-butene content of 20.7 mol% in a total amount of 91% by weight. 0.05 parts by weight of calcium stearate, 0.15 parts by weight of Irganox 1010 manufactured by Ciba Specialty Chemicals, and Irgafus 168 manufactured by Ciba Specialty Chemicals based on 100 parts by weight of the powder of the copolymer
0.05 parts by weight, 0.11 parts by weight of erucamide and 0.16 parts by weight of Sylysia 550 manufactured by Fuji Silysia were mixed and melt-kneaded to obtain pellets of a propylene-based copolymer (C-1). MFR was 6.0. 85% by weight of the propylene-based copolymer (C-1) and propylene-
Exelene EPXKS37G1 (MF, manufactured by Sumitomo Chemical Co., Ltd.) which is an ethylene block copolymer (D-1)
R: 2.9 g / 10 min, CXS component amount: 23.5% by weight, [η] _{X part} : 3.0 dl / g, [η] _{Y part} : 3.8 d
1 / g) Dry blended with 15% by weight, width 400
Extruding at a resin temperature of 250 ° C. and a discharge rate of 12 kg / hr using a φ50 mm extruder equipped with a coat hanger type T-die of 20 mm, a chill roll temperature of 40 ° C., and a line speed of 20 m / m.
in, cooled by air chamber cooling method, thickness 30μm
Film was made. Table 1 shows the evaluation results of the physical properties of the obtained film.

Example 2 The propylene copolymer (C-1) and the propylene-ethylene block copolymer (D-1), Exelen EPX KS37G1 manufactured by Sumitomo Chemical Co., Ltd., were mixed at 70% by weight and 30% by weight, respectively. The procedure was performed in the same manner as in Example 1 except that the weight% was changed. Table 1 shows the evaluation results of the obtained films.

Example 3 The propylene copolymer (C-1) and the propylene-ethylene block copolymer (D-1), Exelen EPX KS37G1 manufactured by Sumitomo Chemical Co., Ltd., were mixed at 50% by weight and 50% by weight, respectively. The procedure was performed in the same manner as in Example 1 except that the weight% was changed. Table 1 shows the evaluation results of the obtained films.

Example 4 In a first step, a propylene copolymer (C-1) having a 1-butene content of 6.6 mol% was prepared using a catalyst containing Ti, Mg and halogen as essential components. 10% by weight of the total amount of the butene copolymer portion is polymerized, and then, in the second step, propylene-1-yl having a 1-butene content of 21.8 mol%.
Example 2 was carried out in the same manner as in Example 2, except that the propylene copolymer (C-2) obtained by polymerizing 90% by weight of the butene copolymer portion was used. Table 1 shows the evaluation results of the obtained films.

Comparative Example 1 Exelene EPX KS3 manufactured by Sumitomo Chemical Co., Ltd., which is a propylene-ethylene block copolymer (D-1)
The same operation as in Example 1 was performed except that 7G1 was not blended. Table 1 shows the evaluation results of the obtained films.

Comparative Example 2 Exelene EPX KS3 manufactured by Sumitomo Chemical Co., Ltd., which is a propylene-ethylene block copolymer (D-1)
The same operation as in Example 4 was performed except that 7G1 was not blended. Table 1 shows the evaluation results of the obtained films.

Comparative Example 3 Propylene having a 1-butene content of 17.5 mol% was obtained by subjecting a propylene-based copolymer (C-1) to single-stage polymerization using a catalyst containing Ti, Mg and halogen as essential components. -1
Example 2 except for changing to -butene copolymer (C-3)
Was performed in the same manner as described above. Table 1 shows the evaluation results of the obtained films.
It was shown to.

[0059]

[Table 1]

Examples 1-4 satisfying the requirements of the present invention are:
It turns out that it is excellent in low-temperature heat sealability, transparency, and impact resistance. On the other hand, Comparative Examples 1 and 2, which did not use the propylene-ethylene block copolymer (D), which is a requirement of the present invention, had insufficient low-temperature heat sealability and impact resistance. Shows that the transparency is also insufficient. Comparative Example 3 in which the propylene-based copolymer (C) obtained by polymerization in the first step and the subsequent steps, which is a requirement of the present invention, was not used.
Shows that the low-temperature heat sealability, transparency and impact resistance are all insufficient.

[0061]

As described above, according to the present invention,
It is possible to provide a polypropylene-based film excellent in low-temperature heat sealability, transparency and impact resistance, and a polypropylene-based multilayer film including at least one layer of the film.

Continued on the front page F-term (reference) 4F071 AA15X AA20X AA21X AA75 AA88 AF05 AF23 AF30 AF59 AH04 BB06 BC01 4F100 AK01B AK06A AK06J AK07A AK07J AK08A AK08J AK64A AK66A AK01A02 GB02A02A02BA BP022 BP031 GG02 4J026 HA02 HA03 HA04 HB02 HB03 HB04 HE01

Claims (7)

[Claims] (1) In the first step, propylene and ethylene and / or
Or the content of α-olefins having 4 or more carbon atoms obtained by polymerizing α-olefins having 4 or more carbon atoms is 1 to 15 mol%
And a copolymer component (A) having an ethylene content of 5 mol% or less, and then polymerizing propylene with ethylene and / or an α-olefin having 4 or more carbon atoms in the second and subsequent steps. Α- with 4 or more carbon atoms
A copolymer component (B) 70 having an olefin content of 15 to 30 mol% and an ethylene content of 5 mol% or less.
To 99% by weight of a propylene-based copolymer (C) 4
0 to 95% by weight, and the xylene-soluble component (CXS component) at 20 ° C is 5.0% by weight or more, and the concentration of ethylene in the 20 ° C xylene-soluble component is 14 to 35 mol%.
Is a propylene-ethylene block copolymer (D) 5
What is claimed is: 1. A polypropylene-based film comprising a resin composition containing 60 to 60% by weight. (The total of the component (A) and the component (B) contained in the copolymer (C) is 100% by weight.
And a copolymer (C) contained in the resin composition
And the copolymer (D) is 100% by weight. ) 2. The copolymer component (A) of the propylene-based copolymer (C) is propylene and an α-olefin copolymer having 4 or more carbon atoms, and the copolymer component (B) is composed of propylene and carbon atoms. The polypropylene film according to claim 1, which is a copolymer of four or more α-olefins. 3. The polypropylene system according to claim 1, wherein the xylene-soluble component (CXS component) at 20 ° C. of the propylene-ethylene block copolymer (D) is 5.0 to 40% by weight. the film. 4. The limiting viscosity ([η] ^(D) _CXS ) of the xylene-soluble component (CXS component) at 20 ° C. of the propylene-ethylene block copolymer (D) is 2.0 dl / g or less. The polypropylene film according to claim 1, wherein: 5. A propylene-based copolymer (C) having a content of 6
The polypropylene film according to claim 1, comprising a resin composition having a content of 0 to 95% by weight and a propylene-ethylene block copolymer (D) of 5 to 40% by weight. 6. A propylene-ethylene block copolymer (D) is prepared by using a Ziegler-Natta type catalyst to obtain a total polymerization amount of 40% in a first step in which substantially no inert solvent is present.
~ 85% by weight of the resulting ethylene is 2.
0 to 9.0 mol% of the propylene-ethylene copolymer portion (X portion) and 1% of the total weight in the second step in the gas phase.
The ethylene content obtained by polymerizing 5 to 60% by weight is 1
It consists of a propylene-ethylene copolymer part (Y part) of 0.0 to 24.0 mol%, and the intrinsic viscosity of the Y part
([η] ^(D) _{Y portion} ) is 2.0 to 5.0 dl / g, and the intrinsic viscosity of the Y portion ([η] ^(D) _{Y portion} ) and the intrinsic viscosity of the X portion ([η]
^((D) _{X part} ) and the ratio ([η] ^(D) _{Y part} / [η] ^(D) _{X part} ) is 0.5
2. The polypropylene-based film according to claim 1, wherein the propylene-ethylene block copolymer satisfies ≦ [η] ^(D) _{Y portion} / [η] ^(D) _{X portion} ≦ 1.8. 3. (The total of the X part and the Y part contained in the copolymer (D) is 100% by weight.
It is. ) 7. A polypropylene-based multilayer film comprising at least one layer of the polypropylene-based film according to claim 1.