KR100727895B1 - Polypropylene resin composition for extrusion blow molding - Google Patents

Abstract

Provided is a polypropylene resin composition for extrusion blow molding, which has more excellent melt strength and elongation viscosity than the conventional resins, high heat resistance, and a good gas barrier property. The polypropylene resin composition for extrusion blow molding comprises 0.1-1.0 parts by weight of an antioxidant and 1-20 parts by weight of a blowing agent based on 100 parts by weight of a base resin composition including 30-99wt% of polypropylene having a long chain and 1-70wt% of propylene-ethylene random copolymer having an ethylene content of 1-4mol%. The polypropylene resin composition has a melt strength of 100mN or more.

Description

POLYPROPYLENE RESIN COMPOSITION FOR EXTRUSION BLOW MOLDING}

1 is a photograph of a scanning electron microscope (SEM) of a cross section of an extrusion hollow molded article prepared in Example 1. FIG.

2 is a photograph of a scanning electron microscope of a cross section of an extrusion hollow molded article prepared in Example 3. FIG.

The present invention relates to a polypropylene resin composition having excellent melt tension and stretch viscosity ratio, and more particularly, comprising a polypropylene and a propylene-ethylene random copolymer having a long branch introduced therein, and thus the melt strength and stretch viscosity ratio and The present invention relates to a low-density polypropylene resin composition for extrusion molding having excellent surface properties and excellent gas barrier properties.

Polypropylene is not only excellent in molding processability and chemical resistance, but also in mechanical properties, and thus has been applied to various applications such as food containers, detergent and shampoo containers, pharmaceutical containers, and automobile electric parts.

Recently, a technique for reducing the thickness of a product by increasing the rigidity of the material to reduce the weight of the blow molded container has been developed. However, such a technique has a problem in that a defect rate increases and weight loss is limited in blow molding due to a decrease in thickness.

In order to solve the problems described above, the present invention expands the application range of polypropylene, which is limited to melt strength and elongation viscosity ratio compared to existing resins, has high heat resistance, and is limited to small hollow molding materials. In addition, an object of the present invention is to provide a low-density polypropylene resin composition for extrusion molding having excellent gas barrier properties.

The polypropylene resin composition for low-density extrusion blow molding of the present invention is 30 to 99% by weight of the high melt strength polypropylene having a long branch and 1 to 70% by weight of a propylene-ethylene random copolymer having an ethylene content of 1 to 4 mol%. It is characterized by including 0.1 to 1.0 parts by weight of antioxidant, 1 to 20 parts by weight of the blowing agent to 100 parts by weight of the base resin composition containing.

The method for producing a polypropylene polymer having a long branch used in the resin composition of the present invention is described in Korean Patent No. 431637, filed and registered by the present applicant. In summary, the surface treatment of a solid titanium catalyst for olefin polymerization with a silane compound having two or more vinyl groups, followed by prepolymerization of the surface-treated solid titanium catalyst with an olefin monomer and a diene compound, results in a high molecular weight monomer around the catalyst. Polypropylene with long branches is prepared by polymerizing or copolymerizing propylene using a catalyst prepared by encapsulating propylene.

When the ethylene content of the propylene-ethylene random copolymer used in the resin composition of the present invention is 1 mol% or more, there is an effect of improving transparency due to the decrease in crystallinity of polypropylene, and the air having an ethylene content of more than 4 mol%. Coalescing is not possible due to the production process. If the content of the propylene-ethylene random copolymer is less than 1% by weight, the melt index is too high, and if it exceeds 70% by weight, the melt strength, the draw viscosity ratio, the parison stability and the heat resistance are inferior, which is not preferable.

Antioxidants used in the polypropylene resin composition of the present invention include tetrax [methylene (3,5-di-tetrabutyl-4-hydroxy) hydrosinameth] methane, octadecyl (3,5-tetrabutyl-4 -Hydroxyphenyl) propionate, 2,2'-methylenebis- (4-methyl-6-tert-butylphenol), 3,5-di-tetra-butyl-4-2-6-di-tetra- Butyl-para-cresol, 1,3,5-trimethyl-1,2,4,6-tris (3,5-di-tetra-butyl-4-hydroxybenzol) benzene, 1,3,5-tris ( 3,5-di-tetra-butyl-4'-hydroxybenzyl) -5-triazine, thiodipropionatedilauryl, dimyristylthiodipropionate, distearyldiodipropionate and tris ( 2,4-di-tetra-butyl-phenyl) phosphite and the like, the amount is preferably used 0.1 to 1.0 parts by weight based on 100 parts by weight of the basic resin composition, if less than 0.1 parts by weight is unstable processing stability Undesirable and 1 If it exceeds 0.00 part by weight, the stabilizing effect no longer increases, which is undesirable.

A low density extrusion blow molding product can be obtained by mixing the polypropylene resin composition with a conventional blowing agent and performing extrusion blow molding.

The blowing agent may be selected from the group consisting of organic compounds such as citric acid-sodium bicarbonate, azodicarbonamide, para-toluenesulfonyl semicarbonate, oxybisbenzenesulfonylhydrazide and paratoluenesulfonylhydrazide. At least one organic compound selected; Aliphatic hydrocarbons such as butane, isobutane, pentane, hexane and heptane; Alicyclic hydrocarbons such as cyclobutane, cyclopentane and cyclohexane; And one or more organic selected from the group consisting of halogenated hydrocarbons such as chlorodifluorocyclomethane, dichloromethane, dichlorofluoromethane, trichlorofluoromethane, chloroethane, dichlorotrifluoroethane and perfluorocyclobutane At least one selected from the group consisting of gases and inorganic gases such as carbon dioxide, nitrogen and air can be used.

The addition amount of the blowing agent is preferably used 1 to 20 parts by weight with respect to 100 parts by weight of the resin composition for extrusion molding, more preferably 1 to 10 parts by weight, if less than 1 part by weight of the product has a high density It is not preferable because the weight loss effect is inadequate, and if it exceeds 20 parts by weight, the efficiency of the foaming agent is lowered, an open cell is formed, and the surface property is lowered.

The polypropylene resin composition of the present invention is a melt index of 0.5 ~ 10g / 10 minutes, preferably 1.0 ~ 3.0g / 10 minutes in accordance with the standard of ASTM D1238 at 230 ℃, 2.16kg conditions. When the melt index of the resin composition of the present invention is less than 0.5g / 10 minutes, there is a problem in that a lot of load during processing, if the melt index is more than 10g / 10 minutes, the viscosity of the molten resin is sharply lowered, the parison can not be molded And, there is a problem that the thickness uniformity of the blow molded product is worse.

The polypropylene resin composition of the present invention has a melt strength of 100 mN or more and a draw viscosity ratio of 3 or more.

To the polypropylene resin composition of the present invention, various additives added to the resin composition for extrusion extrusion molding, such as a heat stabilizer, a slip agent, and a neutralizing agent, can be added within a range not departing from the characteristics of the present invention.

There is no restriction | limiting in particular in the method of manufacturing the polypropylene resin composition of this invention, The manufacturing method of the polypropylene resin composition known to those skilled in the art can be used. In other words, kneaders, rolls, balm mixers, kneaders, tandem extruders, uniaxially selected polypropylene, propylene-ethylene random copolymers and the additives of each branch in the desired order. Or the kneading | mixing using a twin screw extruder etc. can manufacture the resin composition of this invention.

The polypropylene resin composition of the present invention is used as an extrusion molding material. Extruded hollow molded article manufactured using the resin composition of the present invention is molded by a conventional blow molding, excellent parison stability, excellent mechanical strength, can easily adjust the workability to the user, medium / large blow (blow ) Can be used for containers.

Hereinafter, the present invention will be described in more detail with reference to the following examples, but the scope of the present invention is not limited to the examples.

[ Example ]

The measuring method of the physical property in each Example and a comparative example is as follows.

Melt Index Measurement

It measured at 230 degreeC and 2.16 kg according to ASTM D1238.

Melt strength

The melt strength of the strand exiting the die of the capillary rheometer at 200 ° C. was measured at 180 ° C. chamber temperature using a rheometer (Samsung Melt Tension Rheometer). At this time, the L / D of the die was 16 and the acceleration ratio was increased to 1 mm / second.

Stretch viscosity

A cylindrical strand having a length of 250 mm and a diameter of 5 ± 0.5 mm was stretched after completely melting in a 200 ° C. oil using a drawing viscosity, and the drawing viscosity was calculated by the following equation.

Elongation Stress = Force / Area

Elongation rate = Line speed / Sample Length

Elongation viscosity = Elongation Stress / Elongation rate

Elongation viscosity ratio = Elongation viscosity / strain when the strand breaks When the elongation viscosity shear shear phenomenon occurs, the elongation viscosity ratio is 1 or more and the elongation viscosity ratio increases as the shear thickening phenomenon increases.

density

It was measured according to the ASTM D1505 method.

[Examples 1-3]

Stage 1 : Extrusion Blow Molding  Preparation of Resin Composition

As shown in Table 1, the resin composition containing each component was kneaded at 220 ° C. using a 32φ twin screw compounder, melt-extruded the composition to prepare pellets, and then general properties of the resin composition. It evaluated and shown together in Table 1.

Step 2: low density Of extruded hollow molding container  Produce

The resin pellets were fed to a 40 φ extrusion blow molding machine with 2 parts by weight of citric acid-sodium bicarbonate azodicarbonamide (hydrocerol CF40, made by Clariant) as a blowing agent, followed by molding a parison. Got. The density, container weight, and surface characteristics of the blow molded container manufactured as described above were measured as described above, and the results are also shown in Table 1.

[Comparative Examples 1 and 2]

Each component was prepared and evaluated in the same manner as in Example according to Table 1 below, and the results are shown in Table 1 together.

Comparative Example 3

After preparing the one-step resin composition as shown in Table 1 below, a hollow molding container was obtained without the blowing agent. The density, container weight, and surface properties of the prepared blow molded containers were measured and the results are shown in Table 1 together.

Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3  Resin composition Polypropylene polymer ¹ with long branches (% by weight) 75 50 30 10 - - Propylene-ethylene random copolymer ² (% by weight) 25 50 70 90 100 100 Antioxidant (parts by weight) 0.5 0.5 0.5 0.5 0.5 0.5 Resin properties Melt Index (g / 10min) 1.8 1.8 1.8 1.7 1.7 1.7 Melt strength (mN) 265 145 105 52 35 35 Stretch viscosity 9.0 7.3 5.2 1.2 0.2 - Foam properties Density (g / cc) 0.515 0.563 0.687 0.732 0.812 0.910 Mold weight (g) 26.8 30.5 31.6 34.9 36.3 41.5 Surface characteristics ³ ○ ○ ○ △ Ｘ ○

*One. Polypropylene prepared by the method of Example 1 of Korean Patent No. 431637.

*2. RB200, manufactured by Samsung Total Co., Ltd.

* 3. Evaluation criteria of surface properties ○: Excellent, △: Normal, Ｘ: Poor

As shown in Table 1, the resin composition of the embodiment according to the present invention is excellent in melt strength and stretch viscosity ratio, the surface is beautiful, can provide a low-density extrusion molding container of 20% or more reduced weight. .

Polypropylene resin composition of the present invention is excellent in melt strength and stretch viscosity compared to the existing resin can be molded in a low density extrusion blow molding container. In addition, it has a beautiful surface, making it suitable for food containers, detergent / shampoo containers, and medicine containers.

Claims (5)

Antioxidant 0.1-1.0 with respect to 100 weight part of basic resin compositions containing 30-99 weight% of polypropylene which introduced the long branch, and 1-70 weight% of the propylene-ethylene random copolymers of 1-4 mol% of ethylene content Polypropylene resin composition for extrusion molding comprising a weight part, 1 to 20 parts by weight of the blowing agent. According to claim 1, wherein the polypropylene is introduced into the polypropylene surface treatment of the solid titanium catalyst for olefin polymerization with a silane compound having two or more vinyl groups, and then the surface-treated solid titanium catalyst, olefin monomer and diene compound Polypropylene resin composition for extrusion blow molding, characterized in that the polymer produced by polymerizing or copolymerizing propylene using a catalyst prepared by encapsulating a high molecular weight monomer around the catalyst by polymerization. The polypropylene resin composition for extrusion molding according to claim 1, wherein the polypropylene resin composition has a melt strength of 100 mN or more. The polypropylene resin composition for extrusion molding according to claim 1, wherein the polypropylene resin composition has a draw viscosity ratio of 3 or more. The blowing agent of claim 1, wherein the blowing agent is selected from the group consisting of citric acid-sodium bicarbonate, azodicarbonamide, para-toluenesulfonyl semicarbonate, oxybisbenzenesulfonylhydrazide and paratoluenesulfonylhydrazide. Polypropylene for extrusion molding, characterized in that at least one selected from the group consisting of one or more organic and inorganic gases selected from the group consisting of at least one organic compound, aliphatic hydrocarbons, alicyclic hydrocarbons and halogenated hydrocarbons. Resin composition.

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