JPH10279744A - Polypropylene resin composition and hollow molded container - Google Patents

Abstract

(57) [Problem] To provide a propylene-based resin composition and a hollow molded container having an improved balance of transparency, impact resistance and drawdown property without impairing the heat resistance and rigidity of a polypropylene-based resin. To provide. A propylene block copolymer obtained by block polymerization of 10 to 30% by weight of an ethylene-propylene copolymer part after polymerization of a crystalline polypropylene part.
(A) an ethylene resin based on 87% by weight,
This and the above-mentioned propylene block copolymer and 10
When a film having a thickness of 0 μm is made and heat-sealed at 160 ° C., a resin having a peel strength of 700 g / 25 mm width or more is 3 to 10% by weight, and (B) a swell ratio measured at a melt flow rate measurement at 190 ° C. A hollow molded container comprising a polypropylene-based resin composition and 10 to 20% by weight of an ethylene-based resin having a ratio of 1.4 or more, and a composition of the present invention.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a polypropylene resin composition, and more particularly, to a low-temperature impact resistance, transparency,
The present invention relates to a polypropylene resin composition having an improved balance between rigidity and moldability, and a hollow molded container made of the composition.

[0002]

2. Description of the Related Art As a method for producing a plastic container using a thermoplastic resin, a hollow molding method is widely used. The blow molding method is also divided into the direct blow molding method of molding with a hot parison and the injection stretch blow molding method of molding with a cold parison.
It is superior to injection stretch blow molding in terms of molding stability and equipment costs. As resins for direct blow molding, polyethylene, polypropylene resins and the like have been used in various forms as containers for detergents and shampoos, as well as containers for beverages and foods, chemicals, and industrial use. Conventionally, polypropylene-based resins have the disadvantage of being excellent in heat resistance, rigidity and transparency, but poor in impact resistance. JP-A-54-249 describes an improvement in impact resistance.
A propylene block copolymer has been proposed in which an ethylene-propylene copolymer portion is block-polymerized on a crystalline polypropylene portion as typified by Japanese Patent Publication No. 95 (1995). In addition, as an improvement in impact resistance, a polypropylene resin (propylene block copolymer) as typified by Japanese Patent Publication No. 1-8657
It has been proposed that an ethylene-α-olefin copolymer be blended with the polymer. Further, in order to improve the draw-down property of the parison, it has been proposed to blend a low-density polyethylene with a polypropylene resin as typified by JP-A-55-108433. However, in order to improve the impact resistance of the polypropylene resin, the ethylene-propylene copolymer is polymerized blockwise, or the ethylene-α-olefin copolymer is blended with the propylene block copolymer, or the drawdown property is reduced. When low-density polyethylene is blended for improvement, the transparency is greatly deteriorated.
Japanese Patent Publication No. 5-88264 discloses that a polypropylene resin is mixed with a linear low-density polyethylene and an ethylene-α-olefin copolymer in order to balance a certain degree of transparency and impact resistance. However, the impact resistance such as the drop strength of the hollow molded container has not yet reached a satisfactory level.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a propylene-based resin composition having an improved balance of transparency, impact resistance and drawdown property without impairing the heat resistance and rigidity of the polypropylene-based resin. Object and a hollow molded container.

[0004]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that by blending two specific ethylene resins with a specific polypropylene resin, a propylene resin composition satisfying the above object can be obtained. It has been found that a product and a hollow molded container can be obtained, and the present invention has been achieved.

That is, according to the present invention, after the polymerization of the crystalline polypropylene part, the ethylene-propylene copolymer parts 10 to 3
(A) Ethylene-based resin, and the above-mentioned propylene block copolymer and a film having a thickness of 100 μm each with respect to 70 to 87% by weight of a propylene block copolymer obtained by block polymerization of 0% by weight. To make
When they are heat-sealed at 160 ° C., a resin having a peel strength of 700 g / 25 mm width or more, 3 to 10% by weight,
(B) a polypropylene-based resin composition comprising 10 to 20% by weight of an ethylene-based resin having a swell ratio of 1.4 or more measured at 190 ° C. in melt flow rate measurement; A hollow molded container comprising the composition is provided.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The propylene block copolymer used in the present invention is obtained by polymerizing a crystalline polypropylene portion in a polymerization stage and then sequentially polymerizing an ethylene-propylene copolymer portion in a blockwise manner. It is not a true block copolymer but a kind of blend system. If the melt flow rate at 230 ° C. of the propylene block copolymer is too high, the drawdown property is reduced and the moldability is deteriorated. Therefore, the melt flow rate is preferably 1.4 g / 10 min or less, more preferably 1.2 g / 10 min or less. It is.

The content of ethylene-propylene copolymer in the propylene block copolymer is 10 to 30% by weight.
And it is preferably 11 to 25% by weight, more preferably 12 to 20% by weight. When the content of the ethylene-propylene copolymer is less than 10% by weight, the effect of improving the impact resistance is poor. When the content exceeds 30% by weight, the rigidity of the propylene block copolymer is significantly reduced, and the polymer particles become sticky because the polymer particles become sticky. Handling during granulation of the copolymer is deteriorated.

The ethylene content of the propylene block copolymer in the crystalline polypropylene may be 0 to 2% by weight, preferably 1% by weight or less. If the ethylene content in the crystalline polypropylene exceeds 2% by weight, the rigidity of the propylene block copolymer decreases, which is not preferable.

Further, the ethylene content in the ethylene-propylene copolymer part of the propylene block copolymer is 15 to
The content may be 50% by weight, preferably 20 to 45% by weight, more preferably 30 to 40% by weight. If the ethylene content in the ethylene-propylene copolymer is less than 15% by weight, compatibility with the crystalline polypropylene occurs, and the rigidity is significantly reduced. The improvement effect decreases.
Such a propylene block copolymer is produced by a known method.

The (A) ethylene-based resin used in the present invention is prepared by forming a film having a thickness of 100 μm each with the above-mentioned propylene block copolymer and heat-sealing them at 160 ° C. to obtain a peel strength of 700.
g / 25 mm or more resin. The peel strength after heat sealing may be 700 g / 25 mm width or more.
The width is preferably 800 g / 25 mm or more, more preferably 1000 g / 25 mm or more. 700g / 25m
With an ethylene resin having a width of less than m, the compatibility between the propylene block copolymer and the ethylene resin becomes poor, and the impact resistance is reduced.

The amount of the ethylene resin (A) in the composition may be 3 to 10% by weight, preferably 4 to 10% by weight.
It is 8% by weight, more preferably 5-7% by weight.
When the blending amount of the ethylene resin as the component (A) is less than 3% by weight, the compatibility between the propylene block copolymer and the ethylene resin deteriorates, and the transparency decreases. Is reduced. Examples of the ethylene resin as the component (A) include a linear low-density polyethylene having a density of 0.915 or less, an ethylene-α-olefin copolymer, and the like.

The ethylene resin as the component (B) used in the present invention is an ethylene resin having a swell ratio of 1.4 or more measured at 190 ° C. when measuring the melt flow rate. The sometimes measured swell ratio may be 1.4 or more, preferably 1.42 or more, and more preferably 1.44 or more. If the swell ratio measured at the time of measuring the melt flow rate at 190 ° C. is less than 1.4, the effect of improving the drawdown property of the composition decreases.

The amount of the ethylene resin (B) in the composition may be from 10 to 20% by weight, preferably from 1 to 20% by weight.
It is 2 to 18% by weight, more preferably 14 to 16% by weight. (B) If the amount of the ethylene-based resin is less than 10% by weight, the effect of improving the drawdown property is poor, and the impact resistance is reduced. If it exceeds 20% by weight, the rigidity of the composition is reduced. As the ethylene resin of the component (B),
For example, high-pressure low-density polyethylene can be used.

In the composition of the present invention, an inorganic filler such as talc, calcium carbonate, mica, etc., a neutralizing agent, an antioxidant, a heat stabilizer, a lubricant, and an ultraviolet absorber as long as the predetermined physical properties are not impaired. An additive such as an antistatic agent, or a nucleating agent such as an organic phosphate, an alkyl aluminum salt, or a sorbitol, or a coloring agent such as a pigment may be added.

As a compounding method of the composition of the present invention, a known kneader can be used. With a known kneader,
For example, a single-screw kneading extruder, a multi-screw kneading extruder, a Banbury mixer and the like can be mentioned, but the method is not limited to these methods. The melt-kneading conditions at this time need to be set so as not to cause deterioration of the molten resin due to shearing, high-temperature heating and shearing heat during kneading. In order to prevent the deterioration of the molten resin, it is necessary to adjust the temperature appropriately and adjust the resin pressure so as not to increase, and it is also effective to increase the amount of additives such as an antioxidant and a heat stabilizer.

By molding the resin composition of the present invention using a hollow molding machine, a hollow molded container can be obtained. With the hollow molding container of the present invention, a molten parison extruded from an extruder is set in a container-shaped mold of a molding machine, and is inflated to the inner wall of the mold by blowing compressed gas, and then taken out through cooling. The container is not limited to a molding machine and a container shape. The hollow molded container thus obtained is used for hair washing, hair conditioning, cosmetics,
Can be widely used as a container for daily necessities liquids such as detergents and bactericides, as a container for food liquids such as soft drinks, water and seasonings, and as an industrial liquid container for other chemicals etc. Not something.

[0017]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the scope of the invention. The evaluation methods used in Examples and Comparative Examples are described below. (1) Melt flow rate (MFR) Measured according to JIS K7210 under the method of condition -14. Polypropylene was measured at 230 ° C and polyethylene at 190 ° C. (2) Swell ratio (SR) MFR strands extruded were taken at the time of measurement was measured diameter D _S on 5mm from the strand lower end of the cooled and solidified.
The ratio D _S / D of this D _S to the orifice diameter D _O of the MFR measuring instrument
The D _O was swell ratio. (3) Peel strength after heat sealing 20mmφ single screw extruder VS20 (T
Mold die, die width 100mm) 250 ° C for polypropylene, 200 ° C for polyethylene, 50 rpm, cooling roll temperature 20 ° C
Under the conditions described above, a film having a thickness of 100 μm was obtained. After that, heat-sealed tester TP-701B from Tester Sangyo Co., Ltd.
Sealing was performed at 160 ° C. (sealing bar width 10 mm) under the conditions of a sealing time of 5 sec and a sealing pressure of 3 kg / m ² , and then allowed to cool at 23 ° C. Cut out this sealed film to a width of 25mm, using a tensile tester manufactured by Yasuda Seiki Co., Ltd. tensile speed 200mm / mi
The film peel strength at the time of n was measured.

(4) Transparency (Haze) The body of the hollow molded container according to the present invention having a height of 80 mm was cut out as a test piece and measured according to JIS K7105. (5) Flexural modulus Measured according to JIS K7106. (6) Izod impact strength Measured according to JIS K7110 after the test piece was allowed to stand in a thermostat at a temperature of 0 ° C. for 24 hours or more. (7) Drop strength A hollow molded container according to the present invention is filled with 500 g of water, left standing in a low-temperature constant temperature bath at 5 ° C for 24 hours or more, and then placed on a concrete floor from a height of 1.5 m with the bottom of the container facing down. After free fall repeatedly, the container was observed for damage and cracks. The residual ratio was measured from the number of undestructed 10 test containers. (8) Melt tension The resin composition according to the present invention was prepared using a melt tension tester MT-501D3 manufactured by Toyo Seiki Co., Ltd. at a temperature of 230 ° C. and a sample amount of 5
g, residual heat 10 min, L / D = 4 at extrusion speed 5.7 mm / min, tension measured when winding a strand extruded from an orifice 2 mm in diameter with a 50 mm diameter roller at a take-up speed of 100 rpm as melt tension did. Tables 1 and 2 show details of the contents of the polypropylene resin and the ethylene resin used in the examples and comparative examples of the present invention. Table 3 shows the amounts of the resins used in Examples and Comparative Examples of the present invention.

EXAMPLE 1 Using a composition comprising 80% by weight of a propylene block copolymer, 5% by weight of an ethylene resin A and 15% by weight of an ethylene resin D, hot pressing at a temperature of 230 ° C. A sheet having a thickness of 1 mm was formed by a molding machine. A parison was extruded at a die extrusion temperature of 210 ° C with an extrusion rate of 10 kg / h using a hollow molding machine manufactured by Nippon Steel Works (NB3B type; screw diameter 50 mm) and a pressure of 6 kg.
/ cm ² air is blown in for 12 seconds, the parison low side is pinched off by a mold and melt-bonded, side thickness about 0.8 m
A narrow cylindrical hollow container having a capacity of 500 ml and a capacity of 500 ml was produced. Flexural modulus and other physical properties of the selected hot pressed sheet,
Table 4 shows the drop impact resistance and transparency of the hollow molded container.

Example 2 The same composition as in Example 1 was used except that the ethylene-based resin D was replaced with the ethylene-based resin E.
And a narrow cylindrical hollow container were obtained. Table 4 shows the test results.

Example 3 The same composition as in Example 2 was used except that the ethylene resin A in Example 2 was replaced with the ethylene resin B, and the thickness was 1 mm.
And a narrow cylindrical hollow container were obtained. Table 4 shows the test results.

Comparative Example 1 A 1 mm-thick press sheet and a narrow cylindrical hollow container were prepared by using the same composition as in Example 1 except that the propylene block copolymer in Example 1 was replaced with a propylene homopolymer. Obtained. Table 4 shows the test results.

Comparative Example 2 The propylene block copolymer of Example 1 was replaced with propylene-
Using the same composition as in Example 1 except that the ethylene random copolymer was used, a 1 mm-thick press sheet and a narrow cylindrical hollow container were obtained. Table 4 shows the test results.

Comparative Example 3 The same composition as in Example 2 was used except that the ethylene-based resin A in Example 2 was replaced with the ethylene-based resin C.
And a narrow cylindrical hollow container were obtained. Table 4 shows the test results.

COMPARATIVE EXAMPLE 4 The same composition as in Example 1 was used except that the ethylene-based resin A of Example 1 was not used and the amount of the ethylene-based resin D was changed to 20% by weight. And a narrow cylindrical hollow container were obtained. Table 4 shows the test results.

Comparative Example 5 The amount of the ethylene resin A of Example 1 was changed to 15% by weight.
Using the same composition as in Example 1 except that the blending amount of the ethylene-based resin D was changed to 5% by weight, a pressed sheet having a thickness of 1 mm and a narrow cylindrical hollow container were obtained. Table 4 shows the test results.

Comparative Example 6 A 1 mm thick press was prepared using the same composition as in Example 1 except that the blending amount of the ethylene resin A was changed to 20% by weight and the ethylene resin D was not blended. A sheet and a narrow cylindrical hollow container were obtained. Table 4 shows the test results.

Comparative Example 7 The amount of the propylene block copolymer of Example 1 was 90
The same composition as in Example 1 was used except that the amount of ethylene resin D was changed to 5% by weight.
And a narrow cylindrical hollow container were obtained. Table 4 shows the test results.

Comparative Example 8 The blending amount of the propylene block copolymer of Example 1 was 70
A press sheet having a thickness of 1 mm was prepared using the same composition as in Example 1 except that the amount of the ethylene resin A was changed to 25% by weight and the amount of the ethylene resin D was changed to 5% by weight. Thus, a narrow cylindrical hollow container was obtained. Table 4 shows the test results.

Table 1 Contents of polypropylene resin

[Table 1]

Table 2 Ethylene resin content

[Table 2]

Table 3 Mixing ratio (% by weight) of Examples and Comparative Examples

[Table 3]

Table 4 Press sheet properties and bottle properties of each sample

[Table 4]

[0034]

[Table 5]

[0035]

According to the propylene resin composition of the present invention, a hollow molded container having an improved balance of transparency, impact resistance and drawdown property can be obtained by hollow molding.

Claims (3)

[Claims] 1. A propylene block copolymer 70-70 obtained by block polymerization of 10-30% by weight of an ethylene-propylene copolymer part after polymerization of a crystalline polypropylene part.
(A) Ethylene resin, and a film having a thickness of 100 μm each of the above and the above-mentioned propylene block copolymer were prepared, and when they were heat-sealed at 160 ° C., the peel strength was 700 g / 25 mm. Resin 3 ~ showing width or more
10% by weight (B) 10 to 20% by weight of an ethylene-based resin having a swell ratio of 1.4 or more measured at 190 ° C. in a melt flow rate measurement, a polypropylene-based resin composition comprising: 2. The propylene block copolymer has a temperature of 230 ° C.
The melt flow rate is 1.2 g / 10 min or less, the ethylene content in the crystalline polypropylene part is 0 to 2% by weight, and the ethylene content in the ethylene-propylene copolymer part is 15 to 50% by weight. The polypropylene-based resin composition as described in the above. 3. A hollow molded container using the polypropylene resin composition according to claim 1.