JPS60149434A - Biaxially stretched polypropylene film - Google Patents

Abstract

PURPOSE:To obtain a biaxially stretched polypropylene film which is greatly improved in rigidity, transparency, and oil resistance from a polypropylene resin composition having a specific solvent solubility, a specific viscosity, and a specific molecular weight distribution. CONSTITUTION:A polypropylene resin composition, containing 1.0wt% or less soluble in component A with 1.0wt% or less soluble in component B of insoluble in the component A, and 0.8wt% or less soluble in the component C of insoluble in the component B when boiling diethylether (A), boiling n-hexane (B), and boiling n-heptane (C) are used for a consecutive extraction, where the solubles have each intrinsic viscosities of 0.5dl/g or less, 0.4dl/g or less, and 0.3dl/g or less and a molecular weight distribution MW/MN is less than a given value, is molded into the desired film.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a biaxially stretched polypropylene film having excellent rigidity, transparency, and oil resistance.

Polypropylene biaxially stretched film has high tensile strength, stiffness,
Because it has excellent transparency, oil resistance, and electrical properties, it is widely used as a variety of packaging films and for electrical parts such as capacitors.

On the other hand, recently there has been a strong desire to further improve the excellent physical properties of the above-mentioned polypropylene biaxially oriented film. For example, in the cigarette packaging field, when switching from cellophane to polypropylene biaxially oriented film, there has been a strong desire to further improve the physical properties of polypropylene biaxially oriented film.
Improvements in transparency are requested. Further, it is desired to further improve oil resistance, for example, as a capacitor film.

The inventors of the present invention have made extensive studies in view of these points, and have found that if a polypropylene resin composition having specific physical properties is used, the resulting biaxially stretched polypropylene film will have even better rigidity, transparency, and oil resistance. The present invention was achieved by discovering that

That is, in the present invention, (1) In sequential extraction with boiling diethyl ether, boiling n-hexane, and boiling n-hexane, boiling diethyl ether soluble matter is 1.0% by weight or less, boiling diethyl ether insoluble matter contains boiling n- The hexane soluble matter is 10% by weight or less, the boiling n-hebutane soluble matter in the boiling n-hexane insoluble matter is 08% by weight or less, and the intrinsic viscosity [η] of the soluble material in (2) above is 0. ,5
d l/jJ or less, 0.4 dl/, 9 or less, and 0
．． It is a polypropylene biaxially stretched film made using a polypropylene resin composition having a molecular weight distribution Mw/I ton of 5 or less.

The sequential extraction method using boiling diethyl ether, boiling n-hexane, and boiling n-hebutane in the present invention is as follows.

After completely dissolving 5 g of a polypropylene resin composition sample in 500 ml of tetralin at 160°C, it was gradually cooled to 20°C over 6 hours, and then 1.57 g of acetone was added to completely precipitate the polypropylene. dry.

The obtained polypropylene powder was first diluted with diethyl ether 1
Soxhlet extraction was performed using 20ml for 6 hours to separate insoluble and soluble components. Then boiling diethyl ether insoluble matter is η,
- Soxhlet extraction with 120 ml hexane for 13 hours,
Separate into insoluble and soluble components.

Finally, remove the insoluble matter from boiling n-hexane with 120ml of n-hebutane.
A Soxhlet extraction was performed for 13 hours to separate insoluble and soluble components.

In the present invention (C), the ratio of the above-mentioned various boiling solvent soluble substances and the intrinsic viscosity [η] (
Hereinafter, it will be simply written as [η]. ) must be within a certain range.

That is, regarding the proportion of soluble matter, boiling diethyl ether soluble matter is 1.0% by weight or less, boiling n-hexane soluble matter in boiling diethyl ether insoluble matter is 10% by weight or less, boiling n-hexane insoluble matter The boiling n-hebutane solubles in it are 08
% by weight or less.

If it is outside these ranges, the biaxially stretched film will not have sufficient rigidity and oil resistance.

Moreover, [η] of each soluble substance is 0.5 dl/ji or less for boiling diethyl ether soluble content, and o4dn/ for boiling n-hexane soluble content! i' or less, boiling n-hebutane soluble content is 0.3 dl/ji or less. If it is outside these ranges, the biaxially stretched film will not have sufficient transparency.

In the present invention, the molecular weight distribution + Vlψ feeling was determined by gel permeation chromatography, and the molecular weight was calibrated using a monodisperse polyethylene molecular weight standard.

In the present invention, it is necessary that the value of the ratio is 5 or less, and if this value exceeds 5, the transparency will be insufficient.

Melt Flow Index MI (ASTM D-12
38-65T, at a temperature of 230°C and a load of 216 to 9) is not particularly limited, but is preferably 05 to 10!9/10 minutes, particularly preferably 1.0 to
4. o, 9/1o minutes. MI value is 0.5g710
If it is less than 10 minutes, the film forming property is poor and the MI value is 10 minutes.
If the time exceeds 710 minutes, the strength of the biaxially stretched film will be insufficient.

The method for producing polypropylene used in the present invention is not particularly limited as long as it satisfies the physical properties described above, but as an example, titanium tetrachloride is treated with diethylaluminum chloride, then treated with diisoamyl ether, and then Polypropylene polymerized with a catalyst system consisting of a titanium trichloride composition catalyst treated with titanium chloride, an organoaluminum compound (e.g. diethylaluminum chloride) and optionally a third component (e.g. ether, ester, phosphite compound, etc.) One example is a method of reducing molecular weight.

In the present invention, antioxidants, ultraviolet absorbers, anti-blocking agents, commonly used in polypropylene resin compositions,
After adding a slip agent, an antistatic agent, a coloring agent, etc., the film is made into a film using a T-die or the like, and then a biaxially stretched film is obtained by conventional two-stage stretching or simultaneous biaxial stretching.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

The physical properties of the film were measured as follows.

Haze: A, according to STM D-1003-53.

Young's modulus: A test piece with a width of 2 Qmm was sampled from the longitudinal direction (MD) and the transverse direction (TD), and the chuck interval was measured using a tensile tester.

Tensile strength: A, according to STM D-882-64T.

Oil resistance: A film of 5 cm x 5 cm x 2 fkμ is immersed in JIS No. 1 oil at 80°C for 24 hours, then taken out, washed with JIS No. 1 oil, and dried.

weight at that time Expressed as an increase rate.

Examples 1 to 3, Comparative Examples 1 to 2 A polypropylene resin composition having the physical properties shown in Table 1 was extruded at 250°C using a T-die film forming machine, and cooled with a cooling roll at 50°C to determine the thickness. A sheet of 750 μm was prepared. This sheet was processed by TM Ronc biaxial stretching machine to 150
5x in longitudinal direction (MD) then transverse direction (TD, ) at °C.
After stretching 7 times the VC, the film was heat-set to obtain a biaxially stretched film with a thickness of 25 μm.

The physical properties of this film were measured and the results are shown in Table 1.

Claims (1)

[Claims] ■ In sequential extraction with boiling diethyl ether, boiling n-hexane and boiling n-hexane, boiling diethyl ether soluble matter is 10% by weight or less, boiling n-hexane in boiling diethyl ether insoluble matter is possible. The dissolved material is 1.0% by weight or less, the boiling n-hebutane soluble material in the boiling n-hexane insoluble material is 0.8% by weight or less, and the intrinsic viscosity [η] of the soluble material in (2) above is respectively 0.5
dl1717 or less, 0.4 dn /17 or less, and 0
3dl1g or less, and (1) a biaxially stretched polypropylene film using a polypropylene resin composition having a molecular weight distribution &/r6 of 5 or less.