JP2003276136A - Biaxially oriented laminated polypropylene film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a biaxially oriented laminated polypropylene film which is free from matting irregularity and shows high thickness precision. <P>SOLUTION: This polypropylene film comprises a polyolefin composition (F) of a propylene polymer (D) and an ethylene polymer (E), laminated on at least one side or both sides of a biaxially oriented base layer obtained from a propylene polymer composition (C) of a propylene homopolymer (A) and a propylene/α-olefin copolymer (B), with the α-olefin content falling within the range of 0.1 to 1.8 mol%. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biaxially stretched laminated polypropylene film which has no unevenness in matting property and is excellent in laminating strength, thickness accuracy and the like.

[0002]

2. Description of the Related Art Biaxially oriented polypropylene films (hereinafter sometimes referred to as OPP films) are used in a wide range of fields including packaging materials by taking advantage of their excellent transparency, mechanical strength and rigidity. Also, in order to impart matteness to the OPP film in order to enhance the differentiated, high-class appearance and design of the packaged contents, a film is produced in which a thermoplastic resin layer having matteness is laminated on the surface of the OPP film.・ Sold.

However, when such a thermoplastic resin layer is laminated, the OPP film may become uneven in thickness depending on the stretching conditions, and a good film may not be obtained in some cases.
In addition, the matting property may vary.

[0004]

Therefore, the present invention has variously studied for the purpose of developing a biaxially stretched polypropylene film which is free from variations in matting property and is excellent in thickness accuracy, and as a result, a propylene homopolymer as a raw material for an OPP film. By using a propylene polymer composition composed of and a propylene / α-olefin random copolymer, it was possible to obtain a biaxially oriented polypropylene film with reduced variation in matting property and excellent thin-thickness accuracy.

[0005]

[Means for Solving the Problems]

SUMMARY OF THE INVENTION The present invention provides a propylene homopolymer (A) and a propylene / α-olefin copolymer having a biaxially stretched α-olefin content of 0.1 to 1.8 mol%. A polyolefin composition (F) layer of a propylene polymer (D) and an ethylene polymer (E) is laminated on at least one surface or both surfaces of a base layer obtainable from the propylene polymer composition (C) with (B). The present invention provides a biaxially stretched laminated polypropylene film.

Further, in the present invention, the propylene polymer composition (C) is 10 to 95% by weight of the propylene homopolymer (A), and the propylene / α-olefin copolymer (B) is 90 to 5%. And a biaxially stretched laminated polypropylene film, which is a propylene polymer composition obtainable from the composition by weight.

In the present invention, the propylene-based polymer (D) in the polyolefin composition (F) is 20 to 80% by weight.
And a biaxially stretched laminated polypropylene film which is a polyolefin composition (F) containing 80 to 20% by weight of an ethylene polymer (E).

The present invention also provides a biaxially stretched laminated polypropylene film having a propylene polymer (G) layer laminated on the other surface of the biaxially stretched laminated polypropylene film.

Furthermore, the present invention provides a biaxially stretched laminated polypropylene film, wherein the polyolefin composition (F) layer and the propylene polymer (G) layer contain an antiblocking agent.

[0010]

DETAILED DESCRIPTION OF THE INVENTION Propylene Homopolymer (A) The propylene homopolymer (A) according to the present invention comprises a propylene homopolymer and is usually MFR (melt flow rate; ASTM D-1238, load 2160 g,
The temperature (230 ° C.) is usually in the range of 0.5 to 10 g / 10 minutes, preferably 2 to 5 g / 10 minutes.

Propylene / α-olefin copolymer
(B) The propylene / α-olefin copolymer (B) according to the present invention contains propylene having an α-olefin content of 0.4 to 2.2 mol%, preferably 0.6 to 1.8 mol%. Is a random copolymer of. When the content of α-olefin is less than 0.4 mol%, the stretchability is not improved, while when it exceeds 2.2 mol%, the rigidity is poor. As α-olefin, ethylene, 1-butene, 1-hexene, 4
Examples include-methyl / 1-pentene and 1-octene. Of these, ethylene is preferred. Also, MFR
(Melt flow rate; ASTM D-1238 load 2160 g, temperature 230 ° C) is not particularly limited as long as it can be a stretched film, but is usually 0.5 to 10
g / 10 minutes, preferably 2 to 5 g / 10 minutes.

Propylene-based Polymer (D) The propylene-based polymer (D) according to the present invention is a polymer mainly composed of propylene, which is generally manufactured and sold under the name of polypropylene, and usually has a density of 0.890. ~ 0.
930 g / cm ³ , MFR (ASTM D1238 load 2160 g, temperature 230 ° C) is 0.5 to 60 g / 10.
Min, preferably 0.5 to 30 g / 10 min, more preferably 2 to 25 g / 10 min propylene homopolymer or propylene and 20 mol% or less of other α-olefins,
For example, it is a random or block copolymer with ethylene, butene, hexene-1, etc. These polymers have 1
One kind or two or more kinds may be used.

Ethylene Polymer (E) The ethylene polymer (E) according to the present invention is a homopolymer of ethylene or ethylene and an α-olefin having 3 or more carbon atoms, preferably 4 or more carbon atoms, more preferably 6 or more carbon atoms. A random copolymer having a density of 0.910 to 0.9
Polymers in the range of 60 g / cm ³ are so-called high-pressure low-density polyethylene, linear low-density polyethylene (LLDPE) and high-density polyethylene. Such an ethylene-based polymer (E) is usually ethylene produced by a high-pressure method, a Ziegler-based catalyst, or a metallocene-based catalyst and, if necessary, propylene, butene-1, pentene-1, hexene-1,4-methyl-pentene. -1, Octene-1
It is a copolymer with other α-olefins. The melt flow rate (MFR) is based on ASTM D-1238, and the value measured at 190 ° C. under a load of 2.16 kg is
0.05-30, preferably 0.1-20 (g / 10
Minutes). These polymers may be used alone or in combination of two or more, but in order to obtain a coating layer composed of the polyolefin composition (F) having matt property by mixing with the propylene-based polymer (D), a high density is required. It is preferable to use polyethylene.

Propylene Polymer (G) The propylene polymer (G) according to the present invention is a polymer mainly composed of propylene, which is generally manufactured and sold under the name of polypropylene, and usually has a density of 0.890 to 0. .9
30 g / cm ³ , MFR (ASTM D1238 load 2160 g, temperature 230 ° C.) 0.5 to 60 g / 10
Min, preferably 0.5 to 10 g / 10 min, more preferably 2 to 5 g / 10 min of propylene homopolymer or other small amount, for example, 5 mol% or less of α-olefin, such as ethylene, butene, It is a random or block copolymer with hexene-1 and the like. Among these, a homopolymer of propylene or a random copolymer of 2 mol% or less, which is a polymer having a high isotacticity, is obtained, and the biaxially stretched film surface is excellent in scratch resistance, which is preferable. Further, the propylene polymer (G) according to the present invention
May be the above-mentioned propylene homopolymer (A) and propylene / α-olefin copolymer (B) or propylene-based polymer (D), or may be a composition thereof.

The propylene polymer (G) according to the present invention includes a heat resistance stabilizer, weather resistance stabilizer, ultraviolet absorber, lubricant, slip agent, nucleating agent, antiblocking agent, antistatic agent, antifog agent, pigment and dye. Various additives usually used for polyolefins such as inorganic or organic fillers may be added within a range not impairing the object of the present invention.

Among them, the antiblocking agent is added in an amount of 0.01 to
By adding 3.0% by weight, preferably 0.05 to 1.0% by weight, a biaxially stretched laminated polypropylene film having antiblocking properties can be obtained. If the amount of the anti-blocking agent is less than 0.01% by weight, the resulting biaxially stretched laminated polypropylene film is insufficient in the anti-blocking effect, while if it exceeds 3.0% by weight,
The surface of the obtained biaxially stretched laminated polypropylene film tends to be rough. As such an antiblocking agent, various known agents such as silica, talc, mica,
Inorganic compound particles such as metal oxides obtained by firing zeolite or metal alkoxide, organic compound particles such as polymethylmethacrylate, melamine formalin resin, melamine urea resin, polyester resin and the like can be used. Among these, silica and polymethylmethacrylate are particularly preferable from the viewpoint of antiblocking property.

Production Method of Polymer Various propylene homopolymers (A), propylene / α-olefin copolymers (B), propylene-based polymers (D) and propylene polymers (G) according to the present invention are known. It can be produced using a method, for example, a catalyst typically formed from a solid titanium catalyst component and an organometallic compound catalyst component, or a catalyst formed from both components and an electron donor.

As the solid titanium catalyst component, titanium trichloride or a titanium trichloride composition produced by various methods,
Alternatively, a carrier-supported titanium catalyst component having a specific surface area of preferably 100 m 2 / g or more, which contains magnesium, halogen, an electron donor, preferably an aromatic carboxylic acid ester or an alkyl group-containing ether and titanium as essential components, can be mentioned. In particular, a polymer produced by using the latter catalyst component with a carrier is suitable.

The organometallic compound catalyst component is preferably an organoaluminum compound, specifically, trialkylaluminum, dialkylaluminum halide,
Examples thereof include alkyl aluminum sesquihalide and alkyl aluminum dihalide. Among these compounds, a suitable organometallic compound catalyst component varies depending on the type of the titanium catalyst component used.

The electron donor is an organic compound containing nitrogen, phosphorus, sulfur, oxygen, silicon, boron and the like, and preferable specific examples thereof include organic esters and organic ethers having these elements. .

Regarding the method for producing a polymer using a catalyst component with a carrier, for example, JP-A-50-108385 and JP-A-50-
No. 126590, JP-A-51-20297, JP-A-51-28189, JP-A-52-151691 and the like.

The propylene homopolymer and propylene / α-olefin copolymer having a high Iso according to the present invention can also be produced by using a single site catalyst. The single-site catalyst is a catalyst having a uniform active site (single site), and examples thereof include a metallocene catalyst (so-called Kaminsky catalyst) and a Brookhart catalyst. For example, a metallocene catalyst is a catalyst composed of a metallocene-based transition metal compound and at least one compound selected from the group consisting of an organoaluminum compound and a compound that reacts with the metallocene-based transition metal compound to form an ion pair, and an inorganic substance It may be supported on.

The metallocene-based transition metal compound is, for example, JP-A-5-209014 and JP-A-6-10.
Compounds forming 0579, JP-A-1-301704, and JP-A-3-pair are described, for example, in JP-A-1-501950.
And the compounds described in JP-A-3-207704 and the like. Examples of the inorganic material supporting the single-site catalyst include silica gel, zeolite, diatomaceous earth and the like.

Polymerization methods include bulk polymerization, solution polymerization,
Examples include suspension polymerization and gas phase polymerization. These polymerizations may be a batch method or a continuous method. The polymerization conditions are usually a polymerization temperature of −100 to + 250 ° C., a polymerization time of 5 minutes to 10 hours, and a reaction pressure of atmospheric pressure to 300 Kg / cm ³ (gauge pressure).

Propylene Polymer Composition (C) The propylene polymer composition (C) according to the present invention is a composition obtainable from a propylene homopolymer (A) and a propylene / α-olefin copolymer (B). And an α-olefin content of 0.1 to 1.8 mol%, preferably 0.2
To 1.5 mol%, preferably 95 to 10 wt% of the propylene homopolymer (A), and more preferably 90.
To 20% by weight, propylene / α-olefin copolymer (B) is 5 to 90% by weight, and more preferably 10 to 80% by weight. If the propylene / α-olefin copolymer (B) is less than 5% by weight, the effect of improving the stretching temperature range in obtaining a biaxially stretched film may be small, and if it exceeds 90% by weight, a biaxially stretched film obtained. There is a possibility that the rigidity, mechanical strength, etc. of the

The propylene polymer composition (C) according to the present invention comprises the propylene homopolymer (A) and propylene.
It can be obtained by mixing the α-olefin copolymer (B) by various known methods. For example, a method in which a propylene homopolymer (A) and a propylene / α-olefin copolymer (B) are separately polymerized separately in advance and mechanically mixed, a method in which they are melt-kneaded after mixing, Alternatively, a method of polymerizing the propylene homopolymer (A) or the propylene / α-olefin copolymer (B) and then polymerizing the propylene / α-olefin copolymer (B) or the propylene homopolymer (A). Etc.

Polyolefin Composition (F) The polyolefin composition (F) according to the present invention is a composition comprising a propylene polymer (D) and an ethylene polymer (E), and is a biaxially stretched laminated polypropylene obtained. It is a coating material that imparts matte properties to the film. The amounts of the propylene-based polymer (D) and the ethylene-based polymer (E) are not particularly limited as long as the matte property is expressed, but usually the propylene-based polymer (D) is 20 to 80% by weight, preferably 30.
To 70% by weight, and the ethylene polymer (E) is in the range of 80 to 20% by weight, preferably 70 to 30% by weight. or,
In order to develop more matte property, the polyolefin composition (F) (100) is used as the ethylene polymer (E) component.
5% to 20% of high-density polyethylene
%, Preferably 5 to 15% by weight.

Like the propylene polymer (G), various additives may be added to the polyolefin composition (F) according to the present invention within a range that does not impair the object of the present invention. , 0.01 anti-blocking agent
-3.0 wt%, preferably 0.05-1.0 wt% is added to obtain a biaxially stretched laminated polypropylene film having antiblocking property.

The propylene homopolymer (A), propylene / α-olefin copolymer (B), propylene polymer composition (C), propylene polymer (D), ethylene polymer (E) of the present invention. The polyolefin composition (F) may include a heat stabilizer, a weather stabilizer, an ultraviolet absorber, a lubricant, a slip agent, a nucleating agent, an antistatic agent, an antifogging agent, a pigment, a dye, etc. Various additives usually used for polyolefins may be added within a range that does not impair the object of the present invention.

Biaxially Stretched Laminated Polypropylene Film The thickness of the biaxially stretched laminated polypropylene film of the present invention is variously determined depending on the application and is not particularly limited, but usually 10 layers of the propylene polymer composition (C) layer are used.
To 100 μm, preferably 15 to 50 μm, the polyolefin composition (F) layer has a thickness of 0.5 to 15 μm, preferably 1 to 10 μm, and when the propylene polymer (G) layer is laminated, 0.5 to 15 μm in thickness,
It is preferably in the range of 1 to 10 μm.

The biaxially stretched laminated polypropylene film of the present invention may be subjected to surface treatment such as corona treatment or flame treatment on one side or both sides, if necessary. In addition, the biaxially stretched laminated polypropylene film of the present invention may further have a low-temperature heat-sealing property depending on the application, in order to impart low-temperature heat-sealing property, high-pressure process low-density polyethylene, linear low-density polyethylene, crystalline or low-crystalline ethylene and carbon number 3 A low-melting polymer such as a random copolymer of 10 to α-olefin or a random copolymer of propylene and ethylene or α-olefin having 4 or more carbon atoms, polybutene, ethylene-vinyl acetate copolymer These compositions may be laminated on the polyolefin composition (F) layer or the propylene polymer (G) layer. Further, in order to impart a gas barrier property, ethylene / vinyl alcohol copolymer, polyamide, polyester, vinylidene chloride polymer or the like may be laminated by extrusion coating or the like,
You may vapor-deposit a metal or its oxide, silica, etc.
Of course, the surface of the stretched film may be subjected to anchor treatment with an adhesive such as imine or urethane, or a maleic anhydride-modified polyolefin may be laminated in order to increase the adhesion with other substances.

The biaxially stretched laminated polypropylene film of the present invention is a propylene polymer composition (C) obtainable from a propylene polymer (A) and a propylene / α-olefin copolymer (B) and, if necessary, A polyolefin composition (F) containing a predetermined amount of an antiblocking agent,
A multi-layer sheet obtained by co-extrusion molding with a propylene polymer (G) to which a predetermined amount of an anti-blocking agent is added, if necessary, is a known biaxially stretched film or a sequential biaxially stretched film. It is obtained by the manufacturing method. The biaxial stretching conditions are known OPP film production conditions, for example,
In the sequential biaxial stretching method, the longitudinal stretching temperature is 125 ° C to 145 ° C.
C, the stretching ratio is in the range of 4.5 to 6 times, and the transverse stretching temperature is 16.
The stretch ratio is in the range of 5 to 190 ° C. and 8.5 to 10 times.

In the propylene polymer composition (C) according to the present invention, the temperature range of transverse stretching can be widened to 7 ° C. as compared with the conventional one in the method for producing a biaxially stretched film, and the transverse stretching operation can be performed. The thickness accuracy of the obtained biaxially stretched laminated polypropylene film, for example, the thickness variation (2σ) with respect to the reference thickness of the OPP film is 20 to 50 with respect to the biaxially stretched laminated polypropylene film obtained from the propylene polymer (A) alone. % Can be reduced.

[0034]

INDUSTRIAL APPLICABILITY The biaxially stretched laminated polypropylene film of the present invention is excellent in concealing property, thickness accuracy and the like, and is improved in biaxially stretched uniform stretchability and wide temperature range stretchability. And production is more stable (improvement of operating rate and profitability)
it can. Further, the biaxially stretched laminated polypropylene film obtained from the polypropylene composition of the present invention is excellent in thickness accuracy, has no stickiness, is improved in mat unevenness, and is excellent in matte tone. Applications such as rice balls, sushi, rice crackers,
Starting with film for food packaging such as candy and sweet bread,
It can be used for non-food packaging films such as daily sundries and industrial products.

[0035]

EXAMPLES Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples as long as the gist thereof is not exceeded.

Physical properties and the like in the examples and comparative examples were determined by the following evaluation methods. (Evaluation Method) 1) Elastic Modulus: Measured according to JIS K 7127. 2) Film thickness unevenness: The standard deviation of the specified width was measured. 3) Haze: A test piece was cut out from the central portion and the end portion in the lateral direction of the film, and a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd.)
Was measured using.

Example 1 <Base layer: propylene polymer composition layer> 40% by weight of a propylene homopolymer (MFR: 3.0 g / 10 minutes) relative to a propylene / ethylene-random copolymer (ethylene content: 1. 3 mol% MFR: 3.0 g / 10 min) 60
Tetrakis [methylene-3- (3 ', 5'-di-t-butyl-4'hydroxyphenyl) propionate] methane (Japan Product of Ciba-Gaiki Co., Ltd. Product name Irganox 1010) 1000
ppm, stearic acid monoglyceride (manufactured by Riken Vitamin) 6000 ppm as an antistatic agent, stearyldiethanolamine (manufactured by Toho Chemical Co., Ltd.) 2000 ppm, and calcium stearate (manufactured by NOF Corporation) 1000 ppm were added to prepare a propylene polymer composition. <Anti-blocking layer: Propylene-based polymer composition layer>
Melting point 162 as a polymer constituting the anti-blocking layer
C., MFR 2.4 g / 10 min propylene homopolymer, 0.10% by weight of an anti-blocking agent composed of polymethylmethacrylate particles, and tetrakis [methylene-3- (3 ', 5'-di-t -Butyl-4'hydroxyphenyl) propionate] Methane (Product name Irganox 10 manufactured by Ciba-Gaiki Co., Ltd., Japan)
10) A propylene polymer composition containing 1000 ppm and 1000 ppm of calcium stearate (manufactured by NOF CORPORATION) was prepared. <Mat layer: polyolefin composition layer> High-density polyethylene (MFR: 0.33 g / 10 minutes, density: 0.964
g / cm ³ , melting point: 132 ° C.) 40% by weight, propylene-ethylene block copolymer (MFR: 20 g / 10
Min, ethylene content: 12 mol%, melting point: 153 ° C.) to prepare a matte-forming resin. The above-mentioned antioxidant is added to this resin composition at 3000 pp.
m compounded. <OPP film molding> Matte forming resin shown above /
Base layer resin / laminated resin is melt-extruded using a screw extruder so as to have an extrusion rate ratio (1/6/1), shaped using a multi-manifold type T-die, and rapidly cooled on a cooling roll to a thickness of about A 1.5 mm original sheet was obtained. This sheet was heated to about 125 degrees and stretched 5 times in the film flow direction (longitudinal direction). 155 this stretched sheet 5 times
After heating up to 10 degrees, it was stretched 10 times in a direction (transverse direction) orthogonal to the flow direction to obtain an OPP film having a thickness of 30 μm. The results are shown in Table 1.

Comparative Example 1 Example 1 except that the propylene homopolymer was used as the base layer resin.
The same procedure was performed as described above to prepare a film having a thickness of 30 μm. The results are shown in Table 1.

[0039]

[Table 1]

As is clear from the results shown in Table 1, a propylene polymer composition obtained from the propylene homopolymer (A) of the present invention and the propylene / α-olefin copolymer (B) was used as the base layer. The axially stretched laminated polypropylene film has reduced variations in film thickness unevenness and haze, as compared with the biaxially stretched film shown in Comparative Examples,
Further, it can be seen that the heat seal strength at the same temperature also becomes stronger.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) B29L 7:00 B29L 7:00 9:00 9:00 F term (reference) 4F100 AK04B AK04C AK07B AK07C AK64A AK66A AL05A AL05B AL05C BA02 BA03 BA06 BA10A BA10B BA10C BA16 CA30 EH20 EJ38 GB15 JK01 JL00 JN01 YY00A 4F210 AA04 AA11 AA11E AB07 AG01 AG03 QC05 QC06 QG01 QG15 QG18 4J002 BB03X BB05X GF00X14BB14X BB12X BB14W

Claims (9)

[Claims] 1. A propylene homopolymer (A) and a propylene / α-olefin copolymer (B) having a biaxially stretched α-olefin content of 0.1 to 1.8 mol%. A polyolefin composition (F) layer of a propylene polymer (D) and an ethylene polymer (E) is laminated on at least one side or both sides of a base layer obtainable from the propylene polymer composition (C). A biaxially stretched laminated polypropylene film. 2. The propylene polymer composition (C) comprises 10 to 95% by weight of the propylene homopolymer (A) and 90 to 5% by weight of the propylene / α-olefin copolymer (B).
The biaxially stretched laminated polypropylene film according to claim 1, which is a composition of 3. The propylene / α-olefin copolymer (B) has an α-olefin content of 0.4 to 2.2 mol%.
The biaxially stretched laminated polypropylene film according to claim 2. 4. The polyolefin composition (F) is a composition comprising 20 to 80% by weight of a propylene polymer (D) and 80 to 20% by weight of an ethylene polymer (E).
The biaxially stretched laminated polypropylene film described. 5. The biaxially stretched laminated polypropylene film according to claim 1, wherein a propylene polymer (G) layer is laminated on the other side. 6. The biaxially stretched laminated polypropylene film according to claim 1, wherein the polyolefin composition (F) layer comprises an antiblocking agent. 7. The biaxially stretched laminated polypropylene film according to claim 5, wherein the propylene polymer (G) layer contains an antiblocking agent. 8. A sheet obtained by co-extruding a propylene polymer composition (C) layer and a polyolefin composition (F) layer can be obtained by biaxially stretching.
7. The biaxially stretched laminated polypropylene film according to any one of items 7. 9. A sheet obtained by co-extruding a propylene polymer composition (C) layer, a polyolefin composition (F) layer and a propylene polymer (G) layer can be biaxially stretched. The biaxially stretched laminated polypropylene film according to claim 5 or 7.