KR880000268B1 - Process for polypropylene resin composition - Google Patents

Abstract

None.

Description

[Name of invention]

Process for preparing polypropylene-based resin composition

Detailed description of the invention

[Technical Field]

The present invention relates to a method for producing a polypropylene-based resin composition having excellent low temperature impact resistance, high molding flowability, and paintability, and having high rigidity.

[Background]

Conventionally, polypropylene resin has been widely used in various fields because of its excellent properties such as weight, porosity, chemical resistance, heat resistance, etc., but has a disadvantage of low impact resistance at low temperatures. Copolymerization of propylene and ethylene may be carried out for the purpose of improving this drawback, or a method of mixing rubbery material such as ethylene-propylene copolymer or polyethylene with polypropylene has been performed. Moreover, it is common practice to improve rigidity, heat resistance, dimensional stability, coating property, etc. by mix | blending various fillers with polypropylene resin.

However, these phenomena require high stiffness, high heat resistance, easy paintability, high molding fluidity, and opposing physical properties such as high impact resistance to the polypropylene resin. Moreover, a high degree of each of these Buddhas is required.

At present, various improvements have been proposed for these purposes. However, many of these proposals are insufficient to counterbalance the high physical properties required. Therefore, in many cases, the price of the polypropylene resin is inevitably increased by increasing the amount of the rubber component and the filler.

[Initiation of invention]

An object of the present invention is to provide a method for producing an inexpensive polypropylene-based resin composition which is excellent in low temperature impact resistance, high molding fluidity and paintability, and has high rigidity.

It is a further object of the present invention to provide a process for producing a polypropylene-based resin composition suitable for use in producing large moldings such as automated bumpers, fenders and body side members.

As such, the present invention provides a process for preparing the following polypropylene-based resin compositions:

a) crystalline ethylene-propylene block copolymer having an ethylene content of 7 to 30% by weight and at least 65% by weight of boiling n-heptane insoluble;

b) an ethylene-propylene copolymer rubber having a propylene content of 40 to 65% by weight and a Mooney viscosity of 15 to 80 at 100 ° C;

c) an inorganic filler having a particle diameter of 6 μm or less, and

d) organic peroxides

Containing 65 to 95% by weight of component a), 35 to 5% by weight of component b), 2 to 25% by weight of component c) and d) based on the total amount of components a) and b). Is 0.001 to 0.5% by weight of the composition of the polypropylene resin composition, characterized in that for heating at 170 ° to 280 ° C.

Best Mode of the Invention

The crystalline ethylene-propylene block copolymers useful in practicing the present invention are those containing 7 to 30% by weight of ethylene and at least 65% by weight of boiling n-heptane insolubles. If the ethylene content is 7% by weight or less, the paintability and impact resistance of the obtained molded article is reduced, while if it exceeds 30% by weight, the flexural modulus of the molded article is lowered to use the crystalline ethylene-propylene block copolymer outside the above range. It is not desirable.

In addition, ethylene-propylene copolymer rubbers useful in the practice of the present invention are limited to those having a propylene content of 40 to 65 weight percent and a Mooney viscosity at 100 ° C. of 15 to 80. When the propylene content in the ethylene-propylene copolymer rubber is 40% by weight or less, the formed article is bad in appearance and low temperature impact resistance is reduced. On the other hand, when the propylene content exceeds 65% by weight, the flexural modulus and paintability of the molded article become poor. Therefore, it is preferable not to mix | blend an ethylene-propylene copolymer rubber in quantity out of the said range. When an ethylene-propylene copolymer having a Mooney viscosity of less than 15 or 80 or more is added to the crystalline ethylene-propylene copolymer, the particle size of the dispersed ethylene-propylene copolymer rubber becomes too small or too large and the physical properties of the molded article are Out of balance Therefore, it is preferable not to use an ethylene-propylene copolymer rubber having a Mooney viscosity outside the above range.

In the present invention, the ethylene-propylene copolymer is blended at 5 to 35 parts by weight per 100 parts by weight of the total amount of the crystalline ethylene-propylene block copolymer and the ethylene-propylene copolymer rubber. If it is 5 parts by weight or less, the impact resistance and paintability of the molded article are reduced. When the amount of the ethylene-propylene copolymer rubber exceeds 35 parts by weight, the molding fluidity of the composition and the flexural modulus of the molded article are lowered. Therefore, it is preferable not to blend ethylene-propylene copolymer rubber outside the above range.

Examples of inorganic fillers useful in the present invention include calcium oxide, magnesium oxide, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, magnesium carbonate, calcium carbonate, barium sulfate, talc, clay, glass powder, dolomite, pyrsonite, and the like. There is a thing of 6 micrometers or less (preferably 5 micrometers or less). Particular preference is given to using calcium carbonate, barium sulfate or talc. These inorganic fillers may be used alone or in combination.

The impact resistance of the polypropylene-based resin composition formed when at least one inorganic filler having a particle diameter of more than 6 µm is used is lowered.

As a method generally used to determine the particle size of the inorganic filler, there are various regulations such as Greens or Ferrets particle size, Gobellanes particle size, Nussensestein particle size and Stokes particle size. The particle diameter can be measured according to various measurement methods shown in the "Chemical Industrial Handbook".

As used herein, the term "particle diameter" refers to a Nussensestein particle size obtained by the light transmission method. Particle size such as light by using a transmission type particle size distribution meter Model SKC-2000 (Seishin Enterprise Co., Ltd.) can be measured, the accumulated particle size distribution of a particle size of 50% (commonly referred to as "D _50") for the equivalent of Can be.

The proportion of the inorganic filler having a particle size of 6 μm or less to be added in the present invention is in the range of 2 to 25 parts by weight based on 100 parts by weight of the total amount of the resin component of the crystalline ethylene-propylene block copolymer and the ethylen-propylene copolymer rubber. Less than 2 parts by weight is too small to improve rigidity. Rigidity may increase the rigidity to some extent if the proportion of the inorganic filler increases more than 25 parts by weight or more. However, when the inorganic filler is blended at 25 parts by weight or less, the paintability is lowered. In particular, swelling is caused between the resin layer and the coating film due to moisture absorption of the inorganic filler added, thereby deteriorating hot water resistance and moisture resistance. Therefore, it is preferable not to add the inorganic filler outside the above prescribed range.

Examples of organic peroxides useful in practicing the present invention include tbutyl peroxypivalate, lauroyl peroxide, benzoyl peroxide, cyclohexanone peroxide, t-butyl peroxyisopropyl carbonate, t-butylperoxybenzoate, methyl ethyl Ketone peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di (6-butylperoxy) hexane, di-t-butyl peroxide, 2,5-dimethyl-2,5-di (t-butylper Oxy) hex-3 and the like. These organic peroxides may be used alone or in combination.

The ratio of the organic peroxide is in the range of 0.001 to 0.5 parts by weight (preferably 0.01 to 0.3 parts by weight) based on 100 parts by weight of the total amount of the crystalline ethylene-propylene block copolymer and the ethylene-propylene copolymer rubber. While the melt flow index of the resin composition obtained becomes 0.001 parts by weight or less, resulting in poor molding fluidity, while exceeding 0.5 parts by weight, the resin composition in the resin composition of the present invention is too small in molecular weight to be suitable for practical use. Can not get

In addition, as long as it does not impair the effect of this invention remarkably, antioxidant, a heat stabilizer, a ultraviolet absorber, a flame retardant, a nucleating agent, an organic or an inorganic pigment etc. which are normally added to a polypropylene resin can be used individually or in combination.

In the present invention, the mixing of the components a) to d) is carried out using a Henschel mixer or the like generally used in the art. As a heating method, there is also a method of using a Banbury mixer, a thermal roller, or the like, but generally, a method of melting and kneading using a single extruder or a twin screw extruder to form pellets is preferable. In this case, the temperature of the extruder may vary depending on the amount and form of the crystalline ethylene-propylene block copolymer and organic peroxide used.

However, it is necessary to adjust it within 170-280 degreeC. 170 degrees C or less is too low and thermal sensitivity is not performed to a sufficient degree, and the effect of this invention is not fully acquired.

Moreover, even if it heat-processes at the temperature of 280 degreeC or more, the thermosensitivity effect does not increase so much and when it makes it high temperature, since the resin composition thermally decomposes, it is not favorable.

The resin composition thus obtained can be molded into a predetermined molded article by molding methods such as injection molding, extrusion, and compression molding which are usually used.

The present invention is described in detail in the following examples and comparative examples where the melt flow index, flexural modulus and Izod impact strength were respectively measured according to ASTM-D-1238, ASTM D-790 and ASTM D-256.

Example 1

Ethylene content 8.5% by weight, 92.0% by weight of boiling n-heptane insoluble content, 80 parts by weight of crystalline ethylene-propylene block copolymer (hereinafter referred to as PP-A) having a melt flow index of 1.3, propylene content of 50% by weight, 100 ° C 20 parts by weight of an ethylene-propylene copolymer rubber having a Mooney viscosity of 24 (hereinafter referred to as EPR-A), and a particle size of 1.3 to 100 parts by weight of the total amount of the crystalline ethylene-propylene block copolymer and the ethylene-propylene copolymer rubber. 0.13 weight of 2, 5- dimethyl- 2, 5- di (t-butyl peroxy) hexane with respect to 5 weight part of micrometers of calcite, and 100 weight part of total amounts of a crystalline ethylene propylene block copolymer and an ethylene propylene copolymer rubber. Part, and other small amounts of heat stabilizers, antioxidants, and the like were mixed in a Henschel mixer. The mixture was pelleted at 210 ° C. with an extruder. The obtained pellets were molded into predetermined test pieces using an injection molding machine, and the physical properties of the molded product were measured. Moreover, about coatability, it evaluated by the following method.

A two-component acrylic-chlorinated polypolypropylene base paint was applied to a test piece obtained by using an injection molding machine so as to have a thickness of 10 μm, and then the two-component acrylic-urethane-based top coating paint was coated to a film thickness of 25 μm, and then 90 After drying at 30 degreeC for 30 minutes, it was left to stand at room temperature for 24 hours to obtain a coating test piece. Using the cutter of this test piece, the coating of each test piece was cut into 100 1 mm x 1 mm square grids. The adhesive tape was attached to the scratched portion and then peeled off sharply. The ratio of residual film was measured by the percentage at which the initial adhesion was evaluated (grid-type peeling experiment). Furthermore, after immersing a test piece useful for paintability test in hot water at 40 ° C. for 240 hours, the surface state of the coating film was observed, and grid-type peeling demonstration was performed to evaluate hot water resistance.

Further, the pellets obtained above were allowed to stand for one week in an air at a temperature of 30 ° C. and a humidity of 90, and then a flat plate having a length of 160 mm, a width of 80 mm, and a thickness of 2 mm was formed by an injection molding machine. The surface of the molding was observed. The melt flow index of the polypropylene resin thus obtained, the flexural modulus and Izod impact strength of the test piece, the paintability result of the test piece, and the surface state of the molded article are shown in Table 1.

[Examples 2 and 3]

The procedure of Example 1 was repeated except that 2 and 10 parts by weight of activity were added for Examples 2 and 3, respectively. The experimental results are shown in Table 1.

Comparative Example 1

The procedure of Example 1 was repeated except that no talc was used. The experimental results are shown in Table 1.

Comparative Example 2

The procedure of Example 1 was repeated except that talc was added in an amount of 30 parts by weight. The experimental results are shown in Table 1.

Comparative Example 3

The procedure of Example 1 was repeated except that talc with 7.0 μm was used instead of 1.3 μm in particle size. The experimental results are shown in Table 1.

[Examples 4 and 5]

Example 1 and 5 were repeated except that barium sulfate with a particle size of 1.2 μm and calcium carbonate with a particle size of 1.9 μm were used as inorganic fillers instead of talc with a particle size of 1.3 μm, respectively. The experimental results are shown in Table 1.

TABLE 1

Example 6

The procedure of Example 1 was repeated except that instead of EPR-A an ethylene-propylene copolymer rubber having a propylene content of 55% by weight and a pattern viscosity of 47 at 100 ° C (hereinafter referred to as "EPR-B") was used. . The results are shown in Table 2.

Example 7

The procedure of Example 1 was repeated except that ethylene-propylene copolymer (hereinafter referred to as "EPR-C") having a propylene content of 53% by weight and a pattern viscosity of 72 at 100 ° C was used instead of EPR-A. The experimental results are shown in Table 2.

Example 8

The procedure of Example 1 was repeated except that PP-A and EPR-A were added in 70% by weight and 30% by weight, respectively. The experimental results are shown in Table 2.

[Comparative Example 5]

The procedure of Example 1 was repeated except that PP-A and EPR-A were added in amounts of 50 parts by weight and 50 parts by weight, respectively. The experimental results are shown in Table 2.

Example 9

A crystalline ethylene-propylene block copolymer (hereinafter referred to as "PP-B") having an ethylene content of 7.8% by weight, 93.5% by weight of insoluble content of boiling heptane and a melt flow index of 3.5 is used instead of PP-A, and an organic peroxide The procedure of Example 1 was repeated except that it was added in an amount of 0.03 parts by weight. The experimental results are shown in Table 2.

Comparative Example 6

The procedure of Example 1 was repeated except that no organic peroxide was used. The experimental results are shown in Table 2.

Comparative Example 7

The procedure of Example 1 was bent except that 0.6 parts by weight of organic peroxide was added. The experimental results are shown in Table 2.

Comparative Example 8

The same PP-A, EPR-A, talc, organic peroxide, thermal stabilizer, PP-A, EPR-A, organic peroxide, thermal stabilizer and antioxidant as in Example 1 were pelleted in the same manner as in Example 1. It was made. Talc was added to the formed pellets and then the mixture was pelleted in the same manner. The pellets thus obtained were molded into a sample by an injection-molding machine. It was found that talc did not disperse well in the sample. This problem is especially pronounced in plate specimens. Therefore, their physical property and paintability test were omitted.

TABLE 2

Claims (6)

a) crystalline ethylene-propylene block copolymer containing 7-30 wt% of ethylene and 65 wt% or more of boiling n-heptane insoluble content, b) propylene content of 40-65 wt% with a Mooney viscosity of 15-15 An ethylene-propylene copolymer rubber of 80, c) an inorganic filler having a particle diameter of 6 μm or less, and d) an organic peroxide, wherein component a) is 65 to 95% by weight based on the total amount of components a) and b), component a composition comprising b) of 35 to 5% by weight, component c) of 2 to 25% by weight and component d) of 0.001 to 0.5% by weight, at a temperature of 170 ° to 280 ° C. of the polypropylene-resin composition Manufacturing method. The method of claim 1 wherein the particle size of the inorganic filler is 5 μm or less. The inorganic filler according to claim 1, wherein the inorganic filler is selected from calcium oxide, magnesium oxide, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, magnesium carbonate, calcium carbonate, barium sulfate, talc, clay, glass powder, dolomite, pyrsonite. How to. The method of claim 1 wherein the inorganic filler is selected from calcium carbonate, barium sulfate or talc. The method of claim 1 wherein the organic peroxide is t-butyl peroxy pivalate, lauroyl peroxide, benzoyl peroxide, t-butyl peroxyisopropyl carbonate, t-butylperoxybenzoate, methyl ethyl ketone peroxide, dicumyl peroxide From 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, di-t-butyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hex-3 Selected method. The process according to claim 1, wherein components a), b), c) and d) are kneaded in a molten state at 170 ° to 280 ° C and then pelletized for thermal sensitivity.