JP2002265713A - Polypropylene film for fusing seal - Google Patents

Abstract

(57) [Problem] To provide a polypropylene film for fusing seal excellent in fusing seal strength. SOLUTION: Polypropylene polymer (I) 70 to 9
9% by weight, and a propylene-based monomer (A) having a limiting viscosity of 5 dl / g or more obtained by polymerizing a monomer containing propylene as a main component in the first stage.
75% by weight of a crystalline propylene-based polymer component (B) having a limiting viscosity of less than 3 dl / g by polymerizing a monomer containing propylene as a main component in the second and subsequent steps.
The intrinsic viscosity is less than 3 dl / g and the Mw / Mn is 1
Polypropylene polymer (II) 1 to 30 less than 0
A polypropylene-based film for fusing and sealing comprising a polypropylene-based resin composition blended in an amount of up to 10% by weight.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a polypropylene film for fusing seal. More specifically, the present invention relates to a polypropylene-based film for fusing seals having excellent fusing seal strength.

[0002]

2. Description of the Related Art Polypropylene is widely used in the packaging field because of its excellent optical properties, mechanical properties and heat resistance, and is also used as a polypropylene film for fusing seal. For example, Japanese Patent Application Laid-Open No. 9-1273
In No. 9, the difference between the melting peak temperature and the crystallization peak temperature by DSC is in the range of 30 to 40 ° C., the transparency and mechanical strength are excellent, the fusing seal strength is high, and the fusing seal temperature width is wide In order to keep the difference between the melting peak temperature and the crystallization peak temperature by DSC in the range of 30 to 40 ° C., the amount of the propylene homopolymer to be added is reduced. It is described that the type of polypropylene resin is selected or that a nucleating agent such as talc is blended, and that the addition of the nucleating agent deteriorates the impact resistance of the film. Was desired.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a polypropylene film for fusing seals having excellent fusing seal strength.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in view of the above situation, and as a result, have found that a polypropylene-based polymer whose weight ratio is in a specific range and propylene as a main component in the first stage. Intrinsic viscosity is a specific range by polymerizing a monomer to produce a crystalline propylene-based polymer component whose content is a specific range, and by polymerizing a propylene-based monomer in the second and subsequent steps The intrinsic viscosity is a specific range, the intrinsic viscosity is a specific range obtained by continuously producing a crystalline propylene polymer component having a specific range of the content, and the Mw / Mn is a specific range. It has been found that a polypropylene-based film for fusing and sealing composed of a polypropylene-based resin composition obtained by blending a polypropylene-based polymer having a weight ratio within a specific range can solve the above-mentioned problems. This has led to the completion of the present invention.

That is, according to the present invention, 70 to 99% by weight of a polypropylene-based polymer (I) is polymerized with a monomer mainly composed of propylene in the first stage to have an intrinsic viscosity of 5 dl /.
g or more of the crystalline propylene polymer component (A)
75% by weight of a crystalline propylene polymer component (B) having an intrinsic viscosity of less than 3 dl / g by polymerizing a monomer containing propylene as a main component in the second and subsequent steps by producing from 0.05% by weight to less than 25% by weight. It contains 1 to 30% by weight of a polypropylene-based polymer (II) having an intrinsic viscosity of less than 3 dl / g and an Mw / Mn of less than 10 which is obtained by continuously producing less than 99.95% by weight. The present invention relates to a polypropylene film for fusing and sealing made of a polypropylene resin composition. Hereinafter, the present invention will be described in detail.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The polypropylene polymer (I) used in the present invention is a propylene homopolymer or a propylene random copolymer.

[0007] The propylene-based random copolymer is a propylene-ethylene random copolymer, propylene-α-
It is a random copolymer selected from an olefin random copolymer and a propylene-ethylene-α-olefin random copolymer.

[0008] The propylene-ethylene random copolymer is a random copolymer obtained by copolymerizing propylene and ethylene, in which ethylene is randomly bonded to a propylene chain.

The propylene-α-olefin random copolymer is a random copolymer obtained by copolymerizing propylene and at least one α-olefin, and at least one α-olefin is randomly added to a propylene chain. It is combined with

[0010] The propylene-ethylene-α-olefin random copolymer is a random copolymer obtained by copolymerizing propylene, ethylene and at least one α-olefin, and ethylene and at least one type of propylene are present in a propylene chain. Α-olefins are randomly bonded.

[0011] α-olefins are I to 4-1 carbon atoms.
An olefin consisting of two, for example, 1-butene,
2-methyl-1-propene, 1-pentene, 2-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-1-
Butene, 1-nonene, 1-decene, 1-undecene, 1
-Dodecene and the like. Preferably, 1-butene,
1-pentene, 1-hexene and 1-octene, more preferably 1-butene and 1-hexene. Further, these α-olefins may be used alone,
More than one species may be used in combination.

Examples of the propylene-α-olefin random copolymer include a propylene-1-butene random copolymer, a propylene-1-pentene random copolymer, and a propylene-1-hexene random copolymer. And preferably a propylene-1-butene random copolymer and a propylene-1-hexene random copolymer.

The propylene-ethylene-α-olefin random copolymer includes, for example, propylene-ethylene-1-butene random copolymer, propylene-ethylene-1-pentene random copolymer, propylene-ethylene-1-hexene A random copolymer and the like are mentioned, and a propylene-ethylene-1-butene random copolymer and a propylene-ethylene-1-hexene random copolymer are preferable.

The method for producing the polypropylene polymer (I) is not particularly limited, and examples thereof include a production method using a generally known catalyst and a known polymerization method. Examples of the known catalyst include a known catalyst for stereoregular polymerization of propylene.

Examples of the catalyst for stereoregular polymerization of propylene include, for example, a Ti-Mg-based catalyst comprising a solid catalyst component obtained by complexing a Ti compound with a magnesium compound; an organic aluminum compound; And a catalyst in which a third component such as an electron donating compound is combined. Preferably, for example, JP-A-61-2
18606, JP-A-61-287904,
A catalyst comprising a solid catalyst component containing magnesium, titanium and halogen as essential components, an organoaluminum compound and an electron donating compound described in JP-A-7-216017.

The method for polymerizing the polypropylene polymer (I) is not particularly limited, and a solvent polymerization method performed in the presence of an inert solvent, a bulk polymerization method performed in the presence of a liquid monomer, Examples include a gas phase polymerization method performed in the absence of a substantially liquid medium, and a gas phase polymerization method is preferable. In addition, a one-stage polymerization method or a two-stage or more multi-stage polymerization method can be used, and a multi-stage polymerization method is preferable.

The polypropylene polymer (II) used in the present invention is a polypropylene polymer comprising a crystalline propylene polymer component (A) and a crystalline propylene polymer component (B). The crystalline propylene polymer component (A) is a component produced by polymerizing a monomer containing propylene as a main component in the first step in the production of the polypropylene polymer (II), and is preferably isotactic. A propylene polymer, more preferably a homopolymer of propylene, or a copolymer obtained by copolymerizing propylene with ethylene and / or an α-olefin having 4 to 12 carbon atoms to such an extent that crystallinity is not lost; It is. As the α-olefin having 4 to 12 carbon atoms, for example,
1-butene, 4-methylpentene-1, 1-hexene,
Examples thereof include 1-octene and the like, preferably 1-butene.

The intrinsic viscosity of the component (A) is at least 5 dl / g, preferably at least 6 dl / g, more preferably at least 7 dl / g. If it is less than 5 dl / g, the fusing seal strength may be poor.

The crystalline propylene polymer component (B) comprises:
In the production of the polypropylene-based polymer (II), after the crystalline propylene-based polymer component (A) is produced, a component produced by polymerizing a propylene-based monomer in the second and subsequent steps, Preferably is an isotactic propylene-based polymer, more preferably a propylene homopolymer, a crystalline copolymer obtained by copolymerizing propylene with ethylene and / or an α-olefin having 4 to 12 carbon atoms, This is a polymer in which an amorphous ethylene / α-olefin copolymer is dispersed in a crystalline propylene polymer. More preferably, propylene homopolymer, random copolymer of propylene and 10% by weight or less of ethylene, random copolymer of propylene and 30% by weight or less of α-olefin having 4 to 12 carbon atoms, propylene and 10% by weight It is a tertiary random copolymer of not more than 30% by weight of ethylene and not more than 30% by weight of an α-olefin having 4 to 12 carbon atoms. Examples of the α-olefin having 4 to 12 carbon atoms include 1-butene and 4-methylpentene-
Examples thereof include 1,1-hexene and 1-octene, and preferably 1-butene.

The intrinsic viscosity of component (B) is less than 3 dl / g, preferably less than 2 dl / g. Intrinsic viscosity is 3
When it is dl / g or more, the fluidity is poor, and the processability may be deteriorated.

The content of the crystalline propylene-based polymer component (A) and component (B) in the entire polypropylene-based polymer is as follows: component (A) is at least 0.05% by weight and less than 25% by weight (ie, (B) is not less than 75% by weight and 99.9%
Less than 5% by weight). Preferably component (A) is 0.3
% By weight and less than 20% by weight (that is, 80% by weight and less than 99.7% by weight of the component (B)). The content of the component (A) is less than 0.05% by weight (that is, the content of the component (B) is 99.
When the content of the component (A) is 25% by weight or more (that is, when the content of the component (B) is less than 75% by weight), the fluidity is significantly reduced. In some cases, processability may be deteriorated.

The intrinsic viscosity of the polypropylene polymer (II) is less than 3 dl / g, preferably 2.5 dl / g.
Is less than. When the intrinsic viscosity of the polypropylene polymer (II) is 3 dl / g or more, processability may be deteriorated.

Mw / of the polypropylene polymer (II)
Mn is less than 10, preferably less than 8. When Mw / Mn of the polypropylene polymer (II) is 10 or more, processability may be deteriorated.

The method for producing the polypropylene polymer (II) is a production method in which polymerization is carried out in two or more stages using a generally known catalyst and a known polymerization method. Examples of the known catalyst include, for example, a catalyst for stereoregular polymerization of propylene, and specifically, the same catalyst as that used in the production of the above-mentioned polypropylene-based polymer (I). Moreover, as a well-known polymerization method, the same polymerization method as the polymerization method used in the production of the above-mentioned polypropylene-based polymer (I) can be mentioned.

In the multistage polymerization method of two or more stages used in the production of the polypropylene-based polymer (II), a propylene-based monomer is polymerized in the first stage in the presence of a polymerization catalyst to produce a crystalline propylene-based polymer. Producing a united component (A),
Subsequently, in the second and subsequent steps, a monomer comprising propylene as a main component is polymerized in the presence of the catalyst and the polymer to produce a crystalline propylene-based polymer component (B).

Specifically, a batch polymerization method in which the crystalline propylene polymer component (A) is polymerized in the same polymerization tank and then the crystalline propylene polymer component (B) is polymerized, After the polymerization of the crystalline propylene-based polymer component (A) is performed, the component (A), which is a product, is transferred to the next polymerization tank. A polymerization method for polymerizing the polymer component (B) is exemplified.

The weight ratio of the polypropylene polymer (I) and the polypropylene polymer (II) in the polypropylene resin composition used in the present invention is such that the polypropylene polymer (I) is 70 to 99% by weight (namely, Polypropylene-based polymer (II) is 1 to 30% by weight),
Preferably, the polypropylene polymer (I) is 80 to 98.
% By weight (that is, the amount of the polypropylene-based polymer (II) is
20% by weight), more preferably 80 to 95% by weight of the polypropylene-based polymer (I) (i.e., 5 to 20% by weight of the polypropylene-based polymer (II)). When the content of the polypropylene-based polymer (I) exceeds 99% by weight (that is, the content of the propylene-based polymer (II) is less than 1% by weight), the fusing seal strength may be poor, and the propylene-based polymer (I) Is less than 70% by weight (that is, when the propylene-based polymer (II) is 30% by weight or more), the processability may be deteriorated.

Examples of the method of blending the polypropylene polymer (I) and the polypropylene polymer (II) in the polypropylene resin composition used in the present invention include, for example, a melt blending method and a pellet blending method during molding. Is mentioned. The method of kneading the polypropylene resin composition used in the present invention includes a method using a known kneader, for example, a method using a single-screw kneading extruder, a multi-screw kneading extruder or a Banbury mixer. And the like.

[0029] The polypropylene resin composition used in the present invention may contain, as long as the object and effects of the present invention are not impaired.
Other resins such as polyethylene and rubber may be blended.

The polypropylene-based polymers (I) and (II) used in the present invention contain an antioxidant, a neutralizing agent, an ultraviolet absorber, and the like, as long as the objects and effects of the present invention are not impaired.
Various auxiliaries such as an anti-foaming agent, a dispersant, an antistatic agent, a lubricant, and an anti-blocking agent, and a dye may be added.

The polypropylene film for fusing and sealing of the present invention may be a single-layer film or a multilayer film including a layer composed of the polypropylene film for fusing and sealing of the present invention.

The method for producing the polypropylene film for fusing seal of the present invention is not particularly limited, and a method of forming a film independently using a commonly used inflation method, T-die method, calendering method, or the like, Examples of the method include forming a film as at least one layer of a multilayer film. Examples of the method for forming a multilayer include a commonly used co-extrusion method, an extrusion lamination method, a heat lamination method, a dry lamination method, and the like.

Further, there is a method for producing a film by stretching the obtained film. Examples of the stretching method include uniaxial or biaxial using a roll stretching method, a tenter stretching method, a tubular stretching method, or the like. A stretching method and the like can be mentioned.

Examples of the use of the polypropylene film for fusing and sealing of the present invention include packaging of foods, fibers, and miscellaneous goods.

[0035]

EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to these examples. The physical properties of the polypropylene-based polymer and the polypropylene-based resin composition used in Examples and Comparative Examples were measured according to the following methods.

(1) Content of crystalline propylene-based polymer component (A) and component (B) (unit:% by weight) It was determined from the mass balance at the time of polymerization. (2) Intrinsic viscosity (unit: dl / g) of the polypropylene-based polymer and the polypropylene-based resin composition The measurement was performed in tetralin at 135 ° C using an Ubbelohde viscometer. In addition, the intrinsic viscosity of the crystalline propylene-based polymer component (B) was determined from the intrinsic viscosity of the entire crystalline propylene-based polymer component (A) and the propylene-based polymer by the following formula. [η] B = ([η] T × 100− [η] A × WA) / WB [η] T: intrinsic viscosity of the entire crystalline propylene polymer [η] A: intrinsic viscosity of component (A) WA : Content of component (A) (% by weight) WB: Content of component (B) (% by weight)

(3) Melt flow rate (MFR, unit: g / 10 min) According to JIS K7210, temperature 230 ° C., load 2
1. Measured at 18N.

(4) Fusing seal strength (unit: N / 25m)
m width) Using a Taylor model HT hot tack tester, a 25 mm wide strip-shaped sample was sealed bar temperature (top)
Fusing sealing was performed at 300 ° C., (lower) 30 ° C., sealing pressure 414 kPa, sealing time 0.5 second, and immediately thereafter, fusing sealing strength was measured at a tensile speed of 200 m / min.

Example 1 95% by weight of Sumitomo Noblen FLX80E3 (propylene homopolymer) powder (PP-1) and Sumitomo Noblen EL80F1 ([η] A = 7.9 dl, [η] B = 1.2)
dl / g, 10% by weight of component A, 90% by weight of component B, 5% by weight of powder (PP-2) of propylene homopolymer (both A and B components) 100 0.05 parts by weight of calcium stearate, 0.20 parts by weight of Irganox 1010 (manufactured by Ciba Specialty), 0.03 parts by weight of Irgafos (manufactured by Ciba Specialty), 0.12 part by weight of erucamide Parts, 0.10 parts by weight of Sylysia 530 (manufactured by Fuji Silysia Ltd.)
Pelletization was carried out using an mφ uniaxial granulator. The MFR of the obtained pellet was 8.7 g / 10 minutes. The obtained pellets were coated with a coat hanger type T die having a width of 400 mm.
Using a 0 mm extruder, resin temperature 250 ° C, discharge rate 12
The film was extruded at Kg / hr, cooled at a chill roll temperature of 40 ° C., at a line speed of 20 m / min, and in an air chamber cooling system to form a film having a thickness of 30 μm. The fusing seal strength of the obtained film was 7.6 N / 25 mm width.

Example 2 The weight ratio of PP-1 and PP-2 in Example 1 was
The procedure was performed in the same manner as in Example 1 except that P-1 was changed to 90% by weight and PP-2 was changed to 10% by weight. The MFR of the obtained pellet was 8.6 g / 10 min, and the fusing seal strength of the obtained film was 8.0 N / 25 mm width.

Example 3 The weight ratio of PP-1 and PP-2 in Example 1 was
The procedure was performed in the same manner as in Example 1 except that the weight of P-1 was changed to 80% by weight and the weight of PP-2 was changed to 20% by weight. The MFR of the obtained pellet was 9.1 g / 10 min, and the fusing seal strength of the obtained film was 6.3 N / 25 mm width.

Comparative Example 1 The procedure of Example 1 was repeated, except that PP-2 was not used. The MFR of the obtained pellet was 9.5 g / 10 min, and the fusing seal strength of the obtained film was 5.7 N / 25 mm width.

Examples 1 to 3 satisfying the requirements of the present invention are as follows:
It can be seen that the sealing strength is excellent. On the other hand, it can be seen that Comparative Example 1, in which the polypropylene-based polymer (II), which is a requirement of the present invention, was not used, had insufficient fusing seal strength.

[0044]

As described above, according to the present invention,
A polypropylene-based film for fusing seal excellent in fusing seal strength can be obtained.

Continued on front page F term (reference) 4F071 AA15 AA15X AA20 AA20X AA21 AA21X AA75 AA76 AA88 AC09 AC12 AF59 AH19 BA01 BB04 BB06 BB07 BB08 BB09 BC01 4J002 BB121 BB141 BB151 BP022 BP032 GT00

Claims (5)

[Claims] 1. A polypropylene polymer (I) of 70 to 99.
% By weight, and polymerizing a monomer containing propylene as a main component in the first step to produce a crystalline propylene polymer component (A) having an intrinsic viscosity of 5 dl / g or more, from 0.05% by weight to less than 25% by weight. Then, in the second and subsequent steps, a monomer containing propylene as a main component is polymerized, and 75% by weight or more and less than 99.95% by weight of the crystalline propylene-based polymer component (B) having an intrinsic viscosity of less than 3 dl / g is continuously added. Obtained by manufacturing
A polypropylene for fusing seal, comprising a polypropylene resin composition containing 1 to 30% by weight of a polypropylene polymer (II) having an intrinsic viscosity of less than 3 dl / g and Mw / Mn of less than 10. System film. 2. The crystalline propylene-based polymer component (A) and component (B) are each a propylene homopolymer, a random copolymer of propylene with 10% by weight or less of ethylene, and propylene with 30% by weight or less. Has 4 to 1 carbon atoms
Crystals selected from random copolymers with α-olefins of No. 2 and terpolymers of propylene with 10% by weight or less of ethylene and 30% by weight or less of α-olefins having 4 to 12 carbon atoms. The polypropylene film for fusing and sealing according to claim 1, which is a water-soluble propylene polymer component. 3. The polypropylene film for fusing seal according to claim 2, wherein the α-olefin is 1-butene. 4. The polypropylene film according to claim 1, wherein the intrinsic viscosity of the crystalline propylene polymer component (A) is 7 dl / g or more. 5. The polypropylene film for fusing seal according to claim 1, wherein the intrinsic viscosity of the polypropylene polymer (II) is less than 2 dl / g.