JPS6220202B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a resin for film molding or blow molding. More specifically, the present invention relates to an ethylene-propylene random copolymer resin having a specific ethylene content and a specific composition and suitable for film molding or blow molding. When made into a film, polypropylene has excellent transparency and good rigidity, so it is used for many purposes, but its major drawback is poor impact resistance, especially at low temperatures. Therefore, it cannot be used as a blow rate or sheet grade for food containers. On the contrary,
It is already known that products with excellent low-temperature impact resistance, rigidity, and transparency can be obtained by copolymerizing a small amount of ethylene. However, in order to improve low-temperature impact resistance, it is necessary to increase the ethylene content. By the way, products with a high ethylene content can be molded into containers such as bottles by blow molding, or by the T-die method.
When formed into a film using the inflation method, there were problems such as the surface becoming cloudy (so-called embossment) and becoming opaque or sticky as time passed, even if there were no problems immediately after production. The present inventor has conducted extensive studies on ethylene-propylene random copolymer resins for film molding or blow molding that have solved the above problems, and has found that ethylene-propylene random copolymer resins that meet specific requirements do not have the above-mentioned drawbacks. The present invention has been completed based on the discovery that it has extremely excellent physical properties. An object of the present invention is to provide an ethylene-propylene random copolymer resin for film molding or blow molding having excellent properties. That is, in the present invention, the ethylene content is 1.5 to 8% by weight, and the melt flow index is
An ethylene-propylene random copolymer resin for film molding or blow molding that is 0.1 to 20 g/10 min, in which the ethylene content of the part that is soluble in white kerosene at 30°C is 40% by weight or less, and A film molding or blow molding resin characterized by having an intrinsic viscosity of 0.6 or more when measured in tetralin at 135°C. By using the resin of the present invention, blow molded products and films with good physical properties without the above-mentioned defects can be obtained. In the present invention, the part that is soluble in white kerosene at 30°C is defined as 10 g of a sample completely dissolved in 200 ml of white kerosene at 130 to 180°C, cooled to 30°C, held at 30°C for 12 hours, and then subjected to filtration. This refers to the product obtained by separating the insoluble matter. Ethylene content is determined by infrared absorption spectrum, Carbon
-13 Determined by NMR method. Melt flow index is 230℃, load 2.16
Measured according to ASTM D-1238-62T under Kg conditions. In addition, the intrinsic viscosity is measured in a tetralin solution at 135°C. The ethylene content in the resin of the present invention is 1.5 to 8% by weight, and if it is less than 1.5% by weight, the impact resistance, especially low temperature impact resistance, is poor and the object of the invention is not achieved. Furthermore, if the ethylene content exceeds 8% by weight, the rigidity will be poor. The resin of the present invention has a melt flow index of
0.1~20g/10min is preferable, and 0.1
If it is less than g/10 min, the flowability is poor and a large force is required for molding, making it difficult to obtain a good blow-molded film. Also, 20g/
If the time exceeds 10 min, problems such as a sticky surface will occur when used as a film. In the present invention, it is essential that there is a portion that is soluble in white kerosene at 30°C (hereinafter abbreviated as white kerosene soluble portion). Furthermore, the ethylene content of this part is 40% by weight.
It is important that the intrinsic viscosity at 135° C. in tetralin be 0.6 or more. If the ethylene content of the white kerosene soluble portion exceeds 40% by weight, the transparency will be poor when molded, which is undesirable, and the surface of the molded product will become whitish, impairing its commercial value. Furthermore, if the intrinsic viscosity of the white kerosene soluble portion is less than 0.6, the surface of the molded product will become cloudy, resulting in poor transparency and sticky surface, resulting in loss of commercial value. In the present invention, as long as the above conditions are satisfied, there is no restriction on the proportion of the white kerosene soluble portion. The resin of the present invention may be any resin as long as it satisfies the above conditions, and the method for producing it includes copolymerizing a polymer obtained by copolymerizing propylene and a small amount of ethylene using a stereoregular catalyst. , a method of removing a polymer soluble in a solvent such as propylene to obtain a residue, or a method of appropriately selecting a propylene homopolymer, an ethylene-propylene random copolymer, or an ethylene homopolymer and mixing them to meet the above conditions. can give. The former method is preferred because the desired resin can be produced at one time. Specifically, preferred production methods include, for example, using known alkyl aluminum and stereoregular polymerization catalysts such as titanium chloride to reduce the ethylene content to 1.5 by known solution polymerization, bulk polymerization, or gas phase polymerization.
The resulting copolymer is then completely dissolved in a hydrocarbon solvent such as heptane, decane, toluene, xylene, tetralin, white kerosene, or light oil, and the hydrocarbon solvent and butyl A method for obtaining the resin of the present invention as an insoluble component by adding butyl carbitol to precipitate the polymer so that the carbitol ratio is about 98/2 to 80/20 (volume ratio), or a method obtained by polymerization. A solution in which the copolymer is completely dissolved in a hydrocarbon solvent is cooled to precipitate most of the copolymer, and then a poor solvent such as methanol is added to precipitate the unprecipitated copolymer. An example of a method is to extract the obtained precipitate with low-temperature propylene itself at -20 to +30°C, remove the propylene-soluble content, and obtain the resin of the present invention as a residue. Note that, since the physical properties of the copolymer after polymerization vary depending on the polymerization catalyst system, polymerization medium, degree of polymerization, monomer composition, etc., the composition of the present invention is obtained by appropriately post-processing under optimal conditions. The resin of the present invention has extremely good transparency and excellent rigidity when made into a film or blow molded product, and therefore can be favorably used as a resin for film molding and blow molding. The present invention will be explained below with reference to Examples. Example 1 A bulk polymerization method using propylene itself as a medium, using pulverized titanium trichloride catalyst (AA catalyst) and diethylaluminium chloride (1:10 weight ratio) as catalysts (AA catalyst per 1 kg of liquid propylene).
0.2 g), polymerization was carried out at 60°C for 4 hours at a gas phase hydrogen concentration of 7.0 vol% and a gas phase ethylene concentration of 2.5 vol%. The resulting copolymer was dissolved in heptane, cooled to room temperature to precipitate most of it, and then metal was added to precipitate most of the remaining part. remove the sediment,
Then extracted with propylene at -10°C, Table 1
A resin powder having the physical properties shown below was obtained. Phenol stabilizer 20/10000 weight ratio, calcium stearate to the obtained resin powder
After adding a 10/10,000 weight ratio, an amide lubricant at a 10/10,000 weight ratio, and a silica-based lubricant at a 10/10,000 weight ratio and mixing them in a Fuensiel mixer, 240
A T-die film with a thickness of 30 μm and a width of 25 cm was molded at ℃. A predetermined sample was cut out from the center of this film and subjected to measurement of various physical properties. The physical properties measured were haze, blocking, Young's modulus, tensile strength, impact and embossing. Note that these physical properties were measured as follows. (i) Haze (%): According to ASTM D-1003-53. (ii) Blocking (%): Two films are placed one on top of the other, a weight of 2 kg is placed on top of the film, and the adhesion area ratio is determined after holding the film at 50°C for 24 hours. (iii) Young's modulus (Kg/mm ² ): Measured using an Instron using a 20 mm x 220 mm film. (iv) Tensile strength (Kg/cm ² ): ASTM D-882-
Compatible with 64T. (v) Impact (Kg・cm/mm): A small ball was attached to the tip of a weight on a fixed 10cm x 10cm film, the arm was rotated to apply an impact, and the impact energy at the time of destruction was determined. (vi) Embossment: Judgment was made by visually observing the film surface after holding the film at 50°C for 24 hours. The results of these measurements are shown in Table-1. Example 2 Gas phase hydrogen concentration and ethylene concentration, respectively
A resin powder having the physical properties shown in Table 1 was obtained in the same manner as in Example 1 except that the amounts were 4.0 vol% and 2.0 vol%.
Using the obtained resin powder, a film was obtained in the same manner as in Example 1, and various physical properties were measured. Table 1 shows the results.
Shown below. Comparative Examples 1 and 2 A resin powder having the physical properties shown in Table 1 was obtained in the same manner as in Example 1 or Example 2 except that the extraction temperature with propylene was 50°C (Example 1 → Comparative Example 1 , Example 2 → Comparative Example 2). Using the obtained resin powder, a film was obtained in the same manner as in Example 1, and various physical properties were measured. The results are shown in Table-1. Example 3 Gas phase hydrogen concentration and ethylene concentration, respectively
A resin powder having the physical properties shown in Table 1 was obtained in the same manner as in Example 1 except that the amounts were 8.0 vol% and 1.0 vol%.
Using the obtained resin powder, a film was obtained in the same manner as in Example 1, and various physical properties were measured. Display the results -
Shown in 1. Comparative Example 3 Example 1 except that the gas phase ethylene concentration was 0.5 vol% for the first 3 hours and 4.5 vol% for the remaining 1 hour.
In the same manner as above, a resin powder having the physical properties shown in Table 1 was obtained. Using the obtained resin powder, a film was obtained in the same manner as in Example 1, and various physical properties were measured. The results are shown in Table-1. Comparative Examples 4 and 5 Example 1 except that the gas phase hydrogen concentration was set to 12.0 vol% (Comparative Example 4) and 0.5 vol% (Comparative Example 5), respectively.
Resin powder was obtained in the same manner as above. The melt flow index of the obtained resin powder was 50g/each.
10min, 0.01g/10min. Further, attempts were made to obtain a film using the obtained resin powder in the same manner as in Example 1, but in no case could a film of constant quality be obtained. Therefore, physical properties other than melt flow index were not measured. Comparative Examples 6 and 7 Resin powders having the physical properties shown in Table 1 were obtained in the same manner as in Example 1, except that the gas phase ethylene concentration was set to 0.1 vol% (Comparative Example 6) and 3.5 vol% (Comparative Example 7), respectively. Ta. Using the obtained resin powder, a film was obtained in the same manner as in Example 1, and various physical properties were measured. The results are shown in Table-1.

[Table] As shown in Table 1, the resin of the present invention can be made into a very well-balanced film, and the blocking property is also very small and good. On the other hand, when the intrinsic viscosity of the white kerosene soluble portion is too low (Comparative Examples 1 and 2) or when the ethylene content is too high, there are problems with blocking properties and embossing. Furthermore, if the melt flow index of the resin itself is too small (Comparative Example 4) or too large (Comparative Example 5), the film cannot be produced satisfactorily, and if the ethylene content of the resin itself is too low, blocking may occur. Along with this, the impact strength is insufficient (Comparative Example 6),
If the amount is too large, blocking properties and embossing will deteriorate, causing problems.

Claims (1)

[Claims] 1 Ethylene content is 1.5-8% by weight, and melt flow index is 0.1-20g/
It is an ethylene-propylene random copolymer resin for film molding or blow molding that is 10 min, and the ethylene content of the part soluble in white kerosene at 30℃ is
40% by weight or less, and the intrinsic viscosity of the portion measured in tetralin at 135°C is 0.6 or more.