JPH0372665B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention is an inorganic filler-containing polypropylene resin composition that is obtained by blending a propylene-ethylene block copolymer with a specific structure with an inorganic filler of a specific particle size, and has excellent elongation and surface gloss in a tensile test. relating to things. Due to its excellent mechanical strength and heat resistance, polypropylene resins containing inorganic fillers are being actively applied to automobile parts, electrical parts, and the like. However, polypropylene resins containing inorganic fillers generally have lower elongation in tensile tests and lower surface gloss. In particular, the elongation in a tensile test is a measure of the surface impact strength required for instrument panels, etc., and the decrease in elongation hinders its application to interior parts such as instrument panels among automobile parts. The problem is that there are many cases where Generally, methods to improve these problems include (1) adding an elastomer such as an ethylene-α-olefin rubber-like polymer to increase the elongation in a tensile test, and (2) fluidity of the composition. (3) Adding an inorganic filler having a fine average particle size and a nearly spherical shape to improve surface gloss. However, although the addition of an elastomer improves elongation in a tensile test, on the other hand, the rigidity and heat resistance are greatly reduced, which limits its use as an instrument panel material, where heat resistance is particularly important. Furthermore, if the fluidity of the composition is improved to increase the surface gloss, the degree of adhesion to the mirror surface of the mold will also increase, which will be effective, but on the other hand, the impact strength will drop significantly. Furthermore, the addition of an inorganic filler with a small average particle size and a shape close to a spherical shape significantly contributes to improving the surface gloss of the composition, but since the aspect ratio (aspect ratio = major axis / minor axis) is small, the inorganic filler The effect of improving rigidity and heat resistance, which is the original purpose of adding , is extremely small. As described above, it is currently extremely difficult to obtain an inorganic filler-containing polypropylene resin composition that exhibits small decreases in stiffness, heat resistance, and impact strength, and has excellent elongation and surface gloss in tensile tests. . The present inventors have conducted various studies on methods for obtaining inorganic filler-containing polypropylene resin compositions that have excellent rigidity, heat resistance, elongation in tensile tests, and surface gloss, which are required as instrument panel materials for automobile parts, for example. As a result, they discovered that the desired objective could be achieved by blending an inorganic filler with a specific particle size into a propylene-ethylene copolymer having a specific structure, leading to the present invention. That is, the present invention has an intrinsic viscosity of 1.7 to 2.5 (dl/g) in tetralin at 135°C, an ethylene content of 5 to 13% by weight, and an intrinsic viscosity of 1.60 to 1.75 (dl/g) of the propylene polymerized part in tetralin at 135°C. /
g) A propylene-ethylene block copolymer with an ethylene content of 25-40% by weight in the copolymerized portion of propylene and ethylene, 65-85% by weight, and an inorganic filler with an average particle diameter of 4.0μ or less, preferably an average It is a polypropylene resin composition consisting of 15 to 35% by weight of an inorganic filler consisting of talc or a mixture of talc and calcium carbonate with a particle size of 4.0μ or less, and the composition has excellent rigidity, heat resistance, and tensile test. Demonstrates elongation and surface gloss. The propylene-ethylene block copolymer used in the present invention is obtained by first polymerizing propylene to form a polypropylene portion using a Ziegler-Natsuta catalyst, and then copolymerizing a mixture of propylene and ethylene. More specifically, for example, in a batch polymerization reactor, n-heptane is used as a solvent and H ₂ is used as a molecular weight regulator.
After adding the water, the temperature is raised to approximately 70℃. Next, a titanium trichloride-based Ziegler-Natsuta catalyst and diethylaluminium chloride as a co-catalyst are added.
Polymerization was started by increasing the polymerization pressure to approximately 9 Kg/cm ² G with propylene, and propylene was supplied to maintain the polymerization pressure to reduce the H ₂ concentration in the gas phase to approximately 4.5 vol%.
Polymerization is continued while supplying H ₂ to maintain the temperature.
After about 3 hours, the propylene polymerization section is terminated, the remaining propylene in the reactor is purged to normal pressure, and the polymerization temperature is adjusted to 60°C. Next, the concentrations of propylene, ethylene, and H ₂ were adjusted so that the ethylene concentration in the gas phase was approximately 15 vol%, and the H ₂ concentration was approximately 17 vol%.
After increasing the polymerization pressure to approximately 3.5 Kg/cm ² G by adjusting the supply amounts of propylene, ethylene, and H ₂ ,
Polymerization is continued for about 1 hour while supplying propylene, ethylene, and H ₂ to maintain the polymerization pressure and gas phase gas composition, and the ethylene-propylene copolymer portion is polymerized. The amount of polymerization of the ethylene and propylene copolymer portion is calculated by mass balance. The difference between the amount of polymer recovered after the completion of all steps and the amount of propylene polymer in the propylene polymerization section calculated by subtracting the monomers remaining in the reactor at the end of propylene polymerization from the total monomer supply amount in the propylene polymerization section. is the amount of polymerized propylene and ethylene copolymer in the propylene and ethylene copolymer portion. The ethylene content is measured by infrared absorption spectrum, and combined with the material balance results, the ethylene content of the propylene and ethylene copolymerized portion is calculated. Incidentally, in the first step and the second step of polymerization, sampling of the polymer is performed as appropriate and necessary analysis is performed. The block copolymer has an intrinsic viscosity of 1.7 to 2.5 (dl/g) in tetralin at 135°C and an ethylene content of 5 to 5.
13% by weight, the intrinsic viscosity of the propylene polymerized part in tetralin at 135°C is 1.60 to 1.75 (dl/g), and the ethylene content of the propylene and ethylene copolymerized part is 25 to 40% by weight. do.
If the intrinsic viscosity of the block copolymer is less than 1.7 (dl/g), the physical properties of the inorganic filler-containing polypropylene resin composition (hereinafter referred to as the resin composition), especially the impact strength, will be significantly reduced, and the ultimate The viscosity
When it exceeds 2.5 (dl/g), the fluidity of the resin composition decreases, and injection molded products using complex-shaped molds, for example, may have a decreased surface gloss or an appearance called flow marks. If the ethylene content in the block copolymer is less than 5% by weight, the impact strength of the resin composition will decrease, and if it exceeds 13% by weight, the heat resistance will decrease.
Furthermore, if the intrinsic viscosity of the propylene polymerized portion of the block copolymer is 1.60 (dl/g), it cannot be expected to improve the elongation of the resin composition in the tensile test as claimed in the present invention; /g), the fluidity of the resin composition decreases and the appearance becomes poor. If the ethylene content of the copolymerized portion of propylene and ethylene in the block copolymer is outside the range of 25 to 40% by weight, impact strength, elongation, etc. will decrease. Although the cause is not clear, when the block copolymer within the above range is used, the surface gloss of the resin composition, which is another feature claimed by the present invention, is significantly improved. In order to have the characteristics claimed in the present invention, it is essential that the composition be as described above. The ethylene content here is determined from an infrared absorption spectrum. The inorganic filler used in the present invention is
It has an average particle size of 4.0μ or less, and is preferably made of talc or a mixture of talc and calcium carbonate.Those with an average particle size of more than 4.0μ have a large drop in impact strength, especially in tensile tests. This results in poor elongation. Furthermore, the appearance such as surface glossiness is also deteriorated. The average particle size here is determined by sedimentation particle size distribution measurement and is a particle size corresponding to a 50% cumulative distribution. The inorganic filler may be used without treatment, but various commonly known silane coupling agents, titanium coupling agents, Those whose surfaces have been treated with higher fatty acids, higher fatty acid esters, higher fatty acid amides, higher fatty acid salts, or other surfactants can be used. The inorganic filler-containing polypropylene resin composition obtained in the present invention has excellent rigidity, heat resistance, elongation in a tensile test, and surface gloss.
It is composed of 85% by weight and 15 to 35% by weight of an inorganic filler, and if the propylene-ethylene block copolymer exceeds 85% by weight, the rigidity will be low and the heat resistance will be poor, and if it is less than 65% by weight, it will have poor heat resistance. Its impact strength and elongation in tensile tests are low, and its surface gloss is poor, making it unsuitable as an instrument material. Such a resin composition, which is the object of the present invention, can only be obtained by adjusting the structure of each component used within a specific range as described above and specifying the blending ratio of each component. The resin composition of the present invention can be produced using a kneader such as a single-screw or twin-screw extruder, a Banbury mixer, or a heated roll. The temperature required for kneading is 160 to 260°C and the time is 1 to 20 minutes. Furthermore, in addition to these basic ingredients, antioxidants, ultraviolet absorbers, lubricants, pigments, antistatic agents, copper damage inhibitors,
Additives such as flame retardants, neutralizing agents, blowing agents, plasticizers, nucleating agents, and crosslinking agents can be blended. Next, the present invention will be explained in more detail with reference to Examples and Comparative Examples, but the scope is not limited thereby. Physical properties in the present invention are measured by the following method. (1) Melt index: Compliant with JIS K6758. (2) Elongation in tensile test: Based on ASTMD, 23
Measured at °C. The test piece for measurement is Sumitomo Heavy Industries.
Molding was performed using a screw in-line injection molding machine manufactured by Co., Ltd. (3) Flexural modulus: Measured at 23°C in accordance with ASTM D790. The test piece for measurement was molded in the same manner as the test piece for the tensile test. Izotsu impact strength: Compliant with JIS K7110,
Measured at 23°C. The test piece for measurement was molded in the same manner as the test piece for the tensile test. (4) Surface gloss: Compliant with ASTM D532-53T. The test piece for measurement was molded into a sheet with a thickness of 2 mm using a screw in-line injection molding machine manufactured by Sumitomo Heavy Industries, Ltd. Example 1 Intrinsic viscosity is 1.90, ethylene content is 6.0% by weight,
The intrinsic viscosity of the propylene polymerization part is 1.72 and the ethylene content of the propylene and ethylene copolymerization part is 33.
Propylene-ethylene block copolymer (referred to as PP-1) and talc (referred to as talc-1) with an average particle size of 2.7μ are mixed in a ratio of 75:25 (referred to as talc-1), and then the above After adding 0.5 parts by weight of the antioxidant Irganox 1010 (manufactured by Ciba-Geigy) and 0.2 parts by weight of the ultraviolet absorber Sanol LS770 (manufactured by Ciba-Geigy) to 100 parts by weight of the total amount of ingredients, the mixture was placed in a Banbury mixer. 190℃
The mixture was kneaded for 10 minutes. After kneading, the pellets were pelletized using a crusher at a resin temperature of 230℃ and a pressure of 870Kg/cm ² .
Specified test pieces were prepared under injection molding conditions with a total cycle of 40 seconds, and physical property tests were conducted. The measurement results are shown in Table 1. Example 2 Example 1 except that in Example 2, a mixture of talc with an average particle size of 2.7μ and calcium carbonate with an average particle size of 2.0μ in a weight ratio of 4:1 was used instead of Talc-1. It was carried out in the same manner as. The physical property measurement results are shown in Table 1. Comparative Example 1 In Example 1, instead of PP-1, the intrinsic viscosity was 2.2 and the ethylene content was 6.9% by weight, the intrinsic viscosity of the propylene polymerization part was 1.5, and the ethylene content of the propylene and ethylene copolymerization part was 46% by weight. Propylene-ethylene block copolymer (PP-
Example 1 was carried out in the same manner as in Example 1, except that 2) was used. The physical property measurement results are shown in Table 1. Comparative Example 2 In Example 1, instead of PP-1, the intrinsic viscosity was 2.6 and the ethylene content was 6.3% by weight, the intrinsic viscosity of the propylene polymerization part was 1.80, and the ethylene content of the propylene and ethylene copolymerization part was 40% by weight. Propylene-ethylene block copolymer (PP
-3) was used in the same manner as in Example 1. The physical property measurement results are shown in Table 1. Comparative Example 3 A test was carried out in the same manner as in Example 1 except that talc (talc-2) having an average particle diameter of 10 μm was used instead of talc 1 in Example 1. The physical property measurement results are shown in Table 1. Comparative Example 4 Instead of setting the mixing ratio of PP-1 and talc-1 to 75:25 (parts by weight) in Example 1, the ratio was changed to
It was carried out in the same manner as in Example 1 except that the ratio was 90:10. The physical property measurement results are shown in Table 1. Comparative Example 5 Instead of setting the mixing ratio of PP-1 and talc-1 to 75:25 (parts by weight) in Example 1, the ratio was changed to
It was carried out in the same manner as in Example 1 except that the ratio was 60:40. The physical property measurement results are shown in Table 1. Comparative Example 6 In Example 1, instead of PP-1, the intrinsic viscosity was 2.10 and the ethylene content was 7.2% by weight, the intrinsic viscosity of the propylene polymerization part was 1.50, and the ethylene content of the propylene and ethylene copolymerization part was 30% by weight. %
The same procedure as in Example 1 was carried out except that a propylene-ethylene block copolymer (referred to as PP-4) was used. The physical property measurement results are shown in Table 1. Comparative Example 7 In Example 1, instead of PP-1, the intrinsic viscosity was 2.2 and the ethylene content was 7.0% by weight, the intrinsic viscosity of the propylene polymerized part was 1.68, and the ethylene content of the propylene and ethylene copolymerized part was 48% by weight. % propylene-ethylene block copolymer (PP
-5) was used in the same manner as in Example 1. The physical property measurement results are shown in Table 1. Comparative Example 8 In Example 1, instead of PP-1, the intrinsic viscosity was 1.90 and the ethylene content was 6.0% by weight, the intrinsic viscosity of the propylene polymerization part was 1.80, and the ethylene content of the propylene and ethylene copolymerization part was 33% by weight. %
The same procedure as in Example 1 was conducted except that a propylene-ethylene block copolymer (referred to as PP-6) was used. The physical property measurement results are shown in Table 1.

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Claims (1)

[Claims] 1. Intrinsic viscosity in tetralin at 135°C is 1.7
~2.5 (dl/g), ethylene content 5-13% by weight,
The intrinsic viscosity of the propylene polymerization part in tetralin at 135℃ is 1.60 to 1.75 (dl/g), and the ethylene content of the propylene and ethylene copolymerization part is 25 to 1.75 (dl/g).
An inorganic filler-containing polypropylene resin consisting of 40% by weight of a propylene-ethylene block copolymer (A) from 65 to 85% by weight and an inorganic filler (B) having an average particle size of 4.0 μ or less from 15 to 35% by weight. Composition. 2. The inorganic filler-containing polypropylene resin composition according to claim 1, wherein the inorganic filler (B) consists of talc or a mixture of talc and calcium carbonate with an average particle size of 4.0 μ or less .