JP2857031B2 - Film production method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polypropylene film having excellent transparency and smoothness and good processability by a calender molding method.

[0002]

2. Description of the Related Art Conventionally, soft vinyl chloride films and sheets have been produced by a calender molding method having high productivity. However, in recent years, conversion of materials to polyolefins such as polypropylene has been desired due to the problem of toxic gas generated when soft vinyl chloride is incinerated.

On the other hand, a T-die method or an inflation method is generally used for the production of a polypropylene film. In the calendering of polypropylene, the transparency and smoothness of the film are poor, and adhesion to a calender roll or the like is difficult. There is a problem that the moldability is also poor.

In order to solve these problems, attempts have been made to add lubricants and inorganic fillers. However, these methods cause bleed-out of the lubricant and decrease transparency and smoothness.

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to propose a method for producing a film having excellent transparency and smoothness with good moldability in calendering of polypropylene.

[0006]

Means for Solving the Problems The present inventors have conducted intensive studies on the above problems, and as a result, by forming a specific polypropylene into a film by calendering, a film having excellent transparency and smoothness was obtained. And found that they can be manufactured with good moldability, and completed the present invention.

That is, the present invention is a method for producing a film, comprising calender molding isotactic polypropylene having a low molecular weight component having a molecular weight of 10,000 or less and a proportion of 1% by weight or less of the whole.

[0008] The isotactic polypropylene of the present invention has no limitation as long as the proportion of low molecular weight components having a molecular weight of 10,000 or less is 1% by weight or less, more preferably 0.5% by weight or less. Can be used. In the present invention, such a low-molecular-weight component having a molecular weight of 10,000 or less is calender-molded with an isotactic polypropylene having a weight of 1% by weight or less to form a film having excellent transparency and smoothness with good moldability. Can be manufactured.

Here, the isotactic polypropylene is not particularly limited, but may be a homopolymer of propylene, or propylene and ethylene, 1-butene,
It is preferable to use a random or block copolymer with an α-olefin such as 1-hexene, 1-octene, and 4-methyl-1pentene. The amount of the α-olefin to be copolymerized is preferably at most 60 mol%. As such a copolymer, for example, a random copolymer of propylene and ethylene having a content of monomer units based on ethylene of 10% by weight or less, or a polypropylene component having 1 to 9%
9% by weight, the propylene-ethylene random copolymer component is 99 to 1% by weight, and the content of monomer units based on ethylene in the copolymer is the amount of the α-olefin to be copolymerized. Such propylene-ethylene block copolymers are exemplified. In addition, this propylene-ethylene block copolymer, in addition to the polypropylene component and the propylene-ethylene random copolymer component,
It may contain a small amount of a polybutene component or the like. As such a propylene-ethylene block copolymer containing a polybutene component, for example, a polybutene component having a content of 0.01 to 5
% By weight, 1 to 70% by weight of a polypropylene component, and 25 to 98.9 of a propylene-ethylene random copolymer component.
9% by weight, and the propylene-ethylene random copolymer component is composed of a random copolymer containing 15 to 80 mol% of a monomer unit based on ethylene and 85 to 20 mol% of a monomer unit based on propylene. Propylene-
Ethylene block copolymers are exemplified. In the propylene-ethylene block copolymer, a small amount of α-olefin such as ethylene may be copolymerized in the polypropylene component.

In the present invention, the ratio of the low molecular weight component having a molecular weight of 10,000 or less in isotactic polypropylene is determined by, for example, determining the ratio of the low molecular weight component having the molecular weight in a differential molecular weight distribution curve measured by gel permeation chromatography. Can be measured.

In the present invention, the isotactic polypropylene has an average molecular weight in a range suitable for calendering, that is, a weight average molecular weight of 150,000 to 150,000.
It is preferable to use 800,000, more preferably 250,000 to 600,000. Such isotactic polypropylene, for example, the weight average molecular weight measured by gel permeation chromatography is 1,000,000 or more, more preferably 1.5 million or more ultra-high molecular weight isotactic polypropylene is decomposed by organic peroxide or the like. Obtainable. Generally, a weight average molecular weight of 10
The proportion of the low molecular weight component of the isotactic polypropylene of not more than 100,000 is more than 1% by weight and cannot be used as it is as the isotactic polypropylene of the present invention.

On the other hand, the proportion of low molecular weight components in isotactic polypropylene having a weight-average molecular weight of 1,000,000 or more is generally small, and the isotactic polypropylene can be converted to an organic peroxide or the like to a weight-average molecular weight suitable for calendering. Does not increase the proportion of the low molecular weight component.

The ultra-high molecular weight isotactic polypropylene having a small amount of low molecular weight components and a weight average molecular weight of 1,000,000 or more can be produced by a known method using a Ziegler type polymerization catalyst or its improved type catalyst. For example, a titanium compound and an organoaluminum compound conventionally known as a catalyst can be used in combination, and if necessary, various kinds of electron donors such as esters and ethers can be used in combination. The polymerization mode may be any of a continuous type and a batch type.Solution polymerization performed in a solution such as heptane, slurry polymerization using propylene itself as a solvent,
Alternatively, it may be gas phase polymerization. The polymerization is usually performed at 0 ° C to 10 ° C.
In a temperature range of 0 ° C., propylene and other α-
The reaction is carried out by supplying an olefin and hydrogen, and the polymerization is stopped with isopropyl alcohol or the like. In the polymerization of this isotactic polypropylene, for example, if the polymerization is carried out without using hydrogen as a molecular weight regulator or without using it at all, an ultra-high molecular weight isotactic polypropylene can be obtained.

The above ultrahigh molecular weight isotactic polypropylene has 1,3-bis- (t-butylperoxy-
Isopropyl) -benzene, methyl ethyl ketone peroxide, isobutyl peroxide, lauroyl peroxide, diisopropylbenzene hydroperoxide, cumyl peroxide, di-t-butyl peroxide, 1,1-di-t-butylperoxy-3,
By adding and kneading a known organic peroxide such as 3,5-trimethylcyclohexane or t-butylperoxyisopropyl carbonate to obtain an isotactic polypropylene having the above average molecular weight and most preferably used in the present invention. Obtainable. At that time, the use amount of the organic peroxide is not particularly limited,
It is preferably 0.001 to 1% by weight. Further, the melting and kneading temperature is preferably in a temperature range of 150 ° C to 300 ° C.

Further, the isotactic polypropylene used in the present invention is obtained by adjusting the amount of hydrogen added in the above-mentioned isotactic polypropylene polymerization, and obtaining the obtained isotactic polypropylene having a weight average molecular weight of 150,000 to 800,000. Can also be obtained by extracting a low molecular weight component from an organic solvent or the like. The extraction of low molecular weight components from isotactic polypropylene is performed by a known method, for example, heptane, hexane, or the like as an organic solvent.
Using octane or the like, low molecular weight components can be extracted at room temperature to 200 ° C.

The isotactic polypropylene of the present invention may further comprise a heat stabilizer, a weather stabilizer,
Additives such as a nucleating agent, a pigment, a plasticizer, and a lubricant may be added.

In the present invention, a film is produced by calender molding using the above isotactic polypropylene. In the present invention, the shape of the film is not particularly limited, and includes a thick film usually called a sheet.

In the calendering, known devices and methods are used without any limitation. For example, the isotactic polypropylene of the present invention and additives are mixed by a Henschel mixer, a ribbon blender or the like, and are melt-kneaded using a kneading roll or an extruder. Next, the raw material in a molten state is continuously rolled to a constant thickness by two or more heat rolls. The arrangement of the heat roll is 4 Z type, 4 inverted L
Any shape, three inclined shapes, and two upright shapes can be used. The conditions for calendering vary depending on the composition of the isotactic polypropylene, the thickness of the film, etc., but the calendering is usually performed at a molding temperature of 100 ° C. to 220 ° C. and a rotation speed ratio of the hot roll of 1 to 3. be able to.

[0019]

According to the production method of the present invention, it is possible to obtain an isotactic polypropylene film having excellent transparency and smoothness and excellent moldability.

[0020]

EXAMPLES The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited to these examples. Prior to the examples, the measuring method used in the examples will be described.

(1) Weight average molecular weight and proportion of low molecular weight components having a molecular weight of 10,000 or less Measured by gel permeation chromatography. OPC by Waters GPC-150C
Performed at 135 ° C. using dichlorobenzene as a solvent. The column used was TSK gel GMH6- manufactured by Tosoh Corporation.
HT, gel size 10-15 μm. The calibration curve shows a weight average molecular weight of 550, 2900, 1 as a standard sample.
It was prepared using 10,000, 50,000, 49,980, 2.7, and 6.75 million standard polystyrene.

(2) Pentad fraction Macromole by Zawbelli et al.
Culles 6.925 (1973), the fraction bound to the isotactic bond in the polymer molecular chain was measured using ¹³ C-NMR. The measurement is J
Using EOLGSSX-270, the pulse width was 90 °, the pulse interval was 15 seconds, and the integration was 10,000 times. Peak assignments were made using Macromolecules 8.697 (19
75).

[0023] (3) Ethylene content Ethylene content, using JEOL GSX-270, ¹³
It measured using the C-NMR spectrometer.

(4) Haze and internal haze Haze was measured according to JIS K7105. Also,
Liquid paraffin was applied to both sides of the sample, the haze was measured, and this value was defined as the internal haze.

(5) Average Surface Roughness The average surface roughness of the sample was measured according to JIS B0601.

(6) Adhesion to Hot Roll The surface temperature of the hot roll was set to 140 ° C. and 160 ° C., and the adhesion of the sample to the hot roll was evaluated. The results were evaluated in three stages based on the following criteria.

；: No adhesion to a heat roll, a film,
Alternatively, the sheet can be easily peeled off.

(2): Slightly adheres to the heat roll and is slightly difficult to peel.

×: Adhered to hot roll, impossible to mold.

Example 1 According to the method of Japanese Patent Publication No. 2-62886, homopolymerization of propylene was carried out without adding hydrogen, and the weight average molecular weight was 2
An ultrahigh molecular weight isotactic propylene homopolymer having 800,000 and a pentat fraction of 0.90 was obtained. 0.06 parts by weight of 1,3-bis- (t-butylperoxy-isopropyl) -benzene as an organic peroxide was added to the ultrahigh molecular weight isotactic propylene homopolymer, and the cylinder temperature was set to 260 ° C. The mixture was melted and kneaded with a twin screw extruder having a diameter of 20 mm to decompose the ultrahigh molecular weight isotactic propylene homopolymer. The weight average molecular weight of the obtained isotactic propylene homopolymer was 430,000, and the ratio of low molecular weight components having a molecular weight of 10,000 or less was 0.2% by weight. This isotactic propylene homopolymer was melt-kneaded with a φ40 mm extruder set at a cylinder temperature of 220 ° C., and a width of 500 m set at a surface temperature of 140 ° C.
m, a pair of heat rolls having a diameter of 200 mm and a thickness of 0.1 mm.
A 1 mm sheet was made. Haze of the obtained sheet,
Table 1 shows the average roughness of the surface. Table 1 also shows the moldability when the surface temperature of the hot roll was set at 140 ° C. and 160 ° C.

Example 2 According to the method of JP-A-4-154817, homopolymerization of propylene was carried out without addition of hydrogen, and ultrahigh molecular weight isotactic propylene having a weight average molecular weight of 1.7 million and a pentat fraction of 0.96 was used alone. A polymer was obtained. Example 1 was added to the ultrahigh molecular weight isotactic propylene homopolymer by adding 0.05 parts by weight of 1,3-bis- (t-butylperoxy-isopropyl) -benzene as an organic peroxide.
The ultra-high molecular weight isotactic propylene homopolymer was decomposed in the same manner as in. The weight average molecular weight of the obtained isotactic propylene homopolymer was 360,000, and the ratio of low molecular weight components having a molecular weight of 10,000 or less was 0.6% by weight. Hereinafter, a sheet was prepared in the same manner as in Example 1.
Table 1 shows the haze, average roughness, and moldability of the obtained sheet.
It was shown to.

Comparative Example 1 A propylene homopolymer having a weight average molecular weight of 400,000 and a low molecular weight component having a ratio of 2.2% or less of 2.2% obtained by a usual polymerization method was used. Created a sheet. Table 1 shows the haze, average roughness, and moldability of the obtained sheet.

Example 3 An ultrahigh molecular weight isotactic propylene-ethylene block copolymer having an ethylene content of 2.8% by weight and a weight average molecular weight of 3.2 million was polymerized according to the method described in Japanese Patent Publication No. 2-62886. Next, the ultrahigh molecular weight isotactic propylene-ethylene block copolymer was decomposed by the method of Example 1, and the ratio of the low molecular weight component having a weight average molecular weight of 470,000 and a molecular weight of 10,000 or less was 0.3% by weight. Was obtained as an isotactic propylene-ethylene block copolymer. Less than,
A sheet was prepared in the same manner as in Example 1. Table 1 shows the haze, average roughness, and moldability of the obtained sheet.

Comparative Example 2 A propylene-ethylene block obtained by a usual polymerization method and having a weight average molecular weight of 380,000, an ethylene content of 3.8% by weight, and a low molecular weight component having a molecular weight of 10,000 or less having a ratio of 2.7% was used. A sheet was prepared by the method of Example 1 using a polymer.
Table 1 shows the haze, average roughness, and moldability of the obtained sheet.
It was shown to.

Example 4 An ultrahigh molecular weight isotactic propylene-ethylene random copolymer having an ethylene content of 3.1% by weight and a weight average molecular weight of 2.6 million was polymerized according to the method described in JP-B-2-62586. Next, the ultrahigh molecular weight isotactic propylene-ethylene random copolymer was decomposed by the method of Example 1, and the ratio of the low molecular weight component having a weight average molecular weight of 390,000 and a molecular weight of 10,000 or less was 0.4% by weight. Was obtained as an isotactic propylene-ethylene block copolymer. Less than,
A sheet was prepared in the same manner as in Example 1. Table 1 shows the haze, average roughness, and moldability of the obtained sheet.

Comparative Example 3 Propylene-ethylene random copolymer having a weight average molecular weight of 410,000, an ethylene content of 3.4% by weight, and a low molecular weight component having a molecular weight of 10,000 or less having a ratio of 3.1% obtained by a usual polymerization method was used. A sheet was prepared by the method of Example 1 using a polymer.
Table 1 shows the haze, average roughness, and moldability of the obtained sheet.
It was shown to.

Example 5 According to the method of Japanese Patent Application No. 4-128942, the polybutene component was 0.2% by weight and the polypropylene component was 12.0%.
An ultra-high molecular weight isotactic polypropylene resin having a weight average molecular weight of 3.6 million and having a weight percentage of 87.8% by weight of a propylene-ethylene random copolymer component and a total ethylene content of 21% by weight was polymerized. 1,3-bis- is added to the ultra-high molecular weight isotactic polypropylene resin.
0.1 parts by weight of (t-butylperoxy-isopropyl) -benzene was added, and the mixture was decomposed in the same manner as in Example 1. The ratio of low-molecular-weight components having a weight average molecular weight of 420,000 and a molecular weight of 10,000 or less was reduced to 0. 0.3% by weight of an isotactic polypropylene resin was obtained. Hereinafter, a sheet was prepared in the same manner as in Example 1. Haze, average roughness,
Table 1 shows the moldability.

[0038]

[Table 1]

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) B29C 43/24 C08L 23/00-23/16 C08F 10/00-10/06

Claims (1)

(57) [Claims] 1. A method for producing a film, comprising calender molding isotactic polypropylene having a low molecular weight component having a molecular weight of 10,000 or less and a proportion of 1% by weight or less of the whole.