KR20000041504A - Polypropylene resin composition excellent in flowability and heat resistance - Google Patents

Abstract

PURPOSE: A polypropylene resin comprising a highly stereo regular polyolefin resin and a nucleating agent is provided which is excellent in flowability, heat resistance, mechanical strength and surface hardness and has strong scratch resistance. CONSTITUTION: A resin comprises 100 parts by weight of a polypropylene resin, 0.05 to 0.3 parts by weight of an organic metal-based nucleating agent and 0.1 to 0.5 parts by weight of an inorganic-based nucleating agent. The polypropylene resin is a highly stereo regular polypropylene polymer having a molecular weight dispersion of 7 to 12 (as measured by a gel permeation chromatography) and a melt index of 10 to 70g/10min(230°C). The resin composition is suitable for use in automobile parts or home electric appliances.

Description

Polypropylene resin composition excellent in flowability and heat resistance

The present invention relates to a resin composition having excellent flowability and heat resistance, and more specifically, flowability, heat resistance, strength and surface hardness of a high-stereoregular polypropylene resin having a wide molecular weight distribution, an organometallic nucleating agent, and an inorganic nucleating agent. Relates to an excellent polypropylene resin composition.

Polypropylene resin has excellent rigidity, chemical resistance, and moldability compared to other polyolefin materials, and has a wide industrial application range for automobile interior parts and home appliance parts. However, polypropylene resins are somewhat inferior to those of polystyrene and acrylonitrile butadiene, which are competitively applied as household materials in terms of heat resistance, stiffness and surface hardness of chemical structures of molecules. In particular, in the application of automobile and electrical and electronic parts requiring high heat resistance, a method of reinforcing rigidity and heat resistance by mixing an inorganic filler with a polypropylene resin has been proposed. In this regard, Japanese Patent Application Laid-Open No. 53-64256, Compositions that improve mechanical properties by blending inorganic fillers and rubbers with polypropylene have been disclosed in SO 53-64257 and Japanese Laid-Open Patent No. 57-55952. However, appearance defects due to fillers, and costs incurred due to an increase in specific gravity of materials, etc. There is a problem.

Japanese Patent Application Publication No. 64-87645 and Japanese Patent Laid-Open No. Hei 1-174550 disclose polypropylene and styrene or styrene acrylonitrile-based polymers and compatibilizer compositions which improve the rigidity and heat resistance of the resin while maintaining the appearance unevenly. . However, all of the above compositions use a styrene butadiene block copolymer as a compatibilizer of polypropylene and polystyrene, but the compatibilizer is somewhat effective in improving the compatibility between the polypropylene polymer and the styrene polymer, but the styrene acrylonitrile polymer and poly Since there is no effect on improving compatibility with the propylene polymer, there is a problem that the effect of improving the surface peeling and physical properties of the composition is lowered.

In order to solve this disadvantage, Japanese Patent Laid-Open No. 3-162446 discloses a resin composition composed of modified polypropylene and rubber grafted with polyphenyl ether and styrene on a polypropylene resin. According to the above composition, it is possible to manufacture a material having improved resin stiffness, paintability, chemical resistance and heat resistance, but it is difficult to manufacture and has a limitation of using expensive materials. Inappropriate.

One of the widely used low cost fillers for improving the mechanical properties of polypropylene resins, especially heat resistance, is talc. In the case of talc, the heat resistance improves as the amount of talc is increased, but there is a limit to increase talc filling amount due to deterioration of gloss, which is the main characteristic of exterior parts, and increase in specific gravity. In the case of polypropylene resin filled with talc due to low material hardness of talc Scratch resistance is poor, and the appearance of the injection molded product is easily damaged by scratches.

Barium sulfate is added as a filler to increase the heat resistance while maintaining the gloss. In the case of barium sulphate, the effect of maintaining the gloss in the shape of the filler is obvious, but the high specific gravity of the filler itself (4.2 g / cm 3) increases the price of the filler and increases the specific gravity of the material. This has the disadvantage of falling. In addition, when the inorganic filler is generally added, the flowability becomes worse even in the same flow index, thereby increasing the possibility of problems such as poor dispersion of pigments and unmolding of complex products.

In order to solve these disadvantages, European Patent No. 562119 and Japanese Patent No. 5222078 have developed a resin composition which improves rigidity and heat resistance by adding a phosphorus-based nucleating agent to a polypropylene resin without filling inorganic materials. There is a disadvantage that the heat resistance is inferior to the inorganic filled polypropylene because it is not large heat resistance.

An object of the present invention is to improve the above problems to provide a polypropylene resin composition excellent in flow resistance and excellent in scratch resistance with excellent heat resistance, mechanical strength and surface hardness.

The resin composition of the present invention is characterized by consisting of a polypropylene resin, an organometallic nucleus agent, and an inorganic nucleus agent.

Polypropylene resins used in the present invention have a high molecular weight distribution having a molecular weight distribution of 7 to 12 by gel permeation chromatography (GPC) method, and a stereoregularity index of nuclear magnetic resonance method of 96% or more based on the pentaad method. A regular polypropylene homopolymer is used, and the melt index (MI) is preferably 10 to 70 g / 10 minutes (ASTM D1238, 230 ° C).

If the molecular weight distribution is less than 7, there is a risk of poor molding during molding of a product having a complicated shape such as grille due to poor flowability.If the molecular weight distribution is over 12, the measuring time becomes too long during injection molding, resulting in overall production speed. Will be lowered.

In addition, when the stereoregularity index is less than 96% based on the pentaad method, the heat resistance and strength of the polypropylene resin are lowered.

If the melt index is less than 10g / 10 minutes, the moldability of the part is not good, the productivity is lowered, while if the melt index exceeds 70g / 10 minutes, the impact strength is sharply lowered.

The organometallic nucleating agent used in the present invention is not particularly limited, and a metal salt selected from aluminum salts, calcium salts, and sodium salts may be used. Specific examples thereof include aluminum parabutyl benzoic acid, sodium benzoic acid, calcium benzoic acid, and the like. Can be mentioned. The organometallic nucleating agent is preferably added in an amount of 0.05 to 0.3 parts by weight with respect to 100 parts by weight of the polypropylene polymer, and when it is less than 0.05 parts by weight, it is difficult to obtain sufficient heat resistance. It doesn't work.

The inorganic nuclear agent used in the present invention is an inorganic substance having an average particle diameter of 2.0 mu and a maximum particle diameter of 6.0 mu or less, particularly preferably a talc nucleating agent, and when the amount exceeds 6.0 mu, the nucleating agent efficiency is lowered. It is preferable to add 0.1-0.5 weight part of inorganic type nucleating agents with respect to 100 weight part of polypropylene polymers, and when it is less than 0.1 weight part, sufficient heat resistance is hard to be acquired, and when it exceeds 0.5 weight part, an effect will not improve further.

Various additives such as reinforcing materials, fillers, heat stabilizers, weather stabilizers, antistatic agents, lubricants, slip agents, nucleating agents, flame retardants, pigments, dyes, and the like may be added to the resin composition of the present invention within a range that does not contravene the characteristics of the present invention. .

There is no particular limitation on the method for producing the resin composition of the present invention, and a method for producing a polypropylene resin composition which is commonly known can be used, and each of the above components can be freely selected and mixed in a desired order. In general, a method of kneading using a kneader such as a kneader, a roll, a short-barrier mixer, and a single or twin screw extruder may be used by adding each of the above components and other additives in a required amount.

The present invention can be understood in more detail by the following examples and comparative examples, the following examples are only examples for illustrating the present invention and are not intended to limit the protection scope of the present invention.

Examples and Comparative Examples

Table 1 shows the results of measuring the contents and the physical properties of the components of Examples 1-2 and Comparative Examples 1-3.

Put all the ingredients in Table 1 into this PCM30 twin-screw kneading extruder at once and knead to prepare a polypropylene resin composition, and then inject it with Samsung Klucner FCM-110 (cutting force = 110 tons) to produce specimens determined by ASTM standards. It was.

Test conditions for each test property are as follows.

1) Specific gravity

The injection test specimen was measured according to ASTM D792.

2) flow index

It was measured at 2.16 kg load according to ASTM D1238.

3) Spiral Flow

It was measured by the Samsung comprehensive chemical self test method, the measurement conditions are as follows.

Injection molding machine 110 tons (9.2 oz)

Shape of injection channel Semicircle (section)

Feeding part temperature 215 ℃

Cylinder and nozzle temperature 235 ℃

Mold temperature 50 ℃

Cooling time 10 seconds

Injection speed 15mm / s

Injection pressure 1000kg / ㎠

Evaluation item Spiral injected under the above conditions

Measurement of flow length of specimen

4) heat deflection temperature

It was measured under reduced weight (4.6 kg) according to ASTM D648.

5) Impact strength

According to ASTM D256 was measured with a NOTCHED specimen at room temperature.

6) surface hardness

In accordance with ASTM D785 it was measured by R-SCALE at room temperature.

7) Flexural modulus

It was measured at room temperature in accordance with ASTM D770.

Table 1

Example Comparative example One 2 One 2 3 Polypropylene 1 100 100 - - - Polypropylene 2 - - 100 100 100 Sodium-based nucleating agent 0.05 0.05 0.05 - - Talc 0.1 0.3 0.3 - - Barium sulfate - - - 12.5 25 Measurement result Specific gravity (g / cm 3) 0.91 0.91 0.91 0.96 1.05 Flow index (g / 10 minutes) 10 10 11 13 13 Spiral Flow (cm) 120 120 105 98 90 Flexural modulus (kgf / ㎠) 21,000 22,000 19,000 18,000 20,000 Impact strength (kgf.cm/cm) 2.5 2.4 2.4 2.4 3.0 Heat deflection temperature (℃) 137 140 127 125 130 Hardness (R-scale) 106 106 100 100 99

1) Polypropylene 1: High-sterile regular polypropylene with a melt index (MI) of 10 g / 10 min (230 ° C.), nuclear magnetic resonance method pentaad method stereoregularity index of 96%, and molecular weight distribution of 8.0 polymer

2) Polypropylene 2: Polypropylene homopolymer with a melt index (MI) of 10 g / 10 min (230 ° C.), nuclear magnetic resonance method pentaad method stereoregularity index of 92% and molecular weight distribution of 5.5

3) Sodium-based nucleating agent: Sodium-phosphorus compound

4) Talc: plate-shaped mineral with an average particle diameter of 3μ

5) Barium sulfate: spherical inorganic substance with an average particle diameter of 1μ

As shown in Table 1, Examples 1 and 2 are resin compositions prepared using a high-stereoregular polypropylene polymer having a wide molecular weight distribution, and have very high flowability, rigidity, and heat deformation temperature as compared with Comparative Examples 1 to 3. great.

In general, the heat-resistant temperature that can be used as a heat-resistant home appliance material is understood to be 130 ℃, the resin composition of Examples 1 and 2 can be used as a heat-resistant home appliance, while the resin composition illustrated in Comparative Examples 1 and 2 Silver is a resin composition using a general polypropylene polymer, the heat resistance is insufficient to be used as a heat-resistant home appliance, and the numerical value of the spiral flow showing moldability was also inferior.

The resin composition shown in Comparative Example 3 has a heat resistance temperature of 130 ° C., which is suitable as a heat-resistant home appliance, but has a specific gravity higher than that of Examples 1 and 2 (Examples 1 and 2: 0.91, Comparative Example 3: 1.05). Since the amount of raw materials used is large and a kneading step of adding an inorganic filler is additionally performed, manufacturing costs are high. In addition, the length of the spiral flow, which is an index indicating flowability, is very inferior, which is due to the addition of inorganic fillers, which may worsen the dispersibility of the pigments used in the manufacture of plastic parts and may cause problems such as complicated molding. have. From this point of view, the resin composition of Example 2 had excellent pigment dispersibility as compared with Comparative Example 3.

As can be seen from the above, the polypropylene resin composition prepared according to the present invention is excellent in flowability, heat resistance, strength and surface hardness, and is suitable for use in automobile parts or home appliances.

Claims (4)

A polypropylene resin composition comprising 0.05 to 0.3 parts by weight of an organometallic nucleating agent and 0.1 to 0.5 parts by weight of an inorganic based nucleating agent with respect to 100 parts by weight of polypropylene resin. The method of claim 1, wherein the polypropylene resin has a molecular weight distribution of 7 to 12 as measured by gel permeation chromatography, the stereoregularity index of the nuclear magnetic resonance method is 96% or more based on the pentaad method, the melt index of 10 It is a high-stereoregular polypropylene homopolymer which is -70 g / 10min (230 degreeC), The polypropylene resin composition characterized by the above-mentioned. The polypropylene resin composition according to claim 1, wherein the organometallic nucleating agent is a metal salt selected from aluminum salts, calcium salts and sodium salts. The polypropylene resin composition according to claim 1, wherein the inorganic nucleating agent is a talc nucleating agent having an average particle diameter of 2.0 mu and a maximum particle diameter of 6.0 mu.