JPS5817139A - Novel polypropylene resin composition - Google Patents

Abstract

PURPOSE:To provide the titled compsn. having excellent rigidity and resistance to heat and impact, by blending a specified inorg. filler and an amorphous ethylene/alpha-olefin copolymer with crystalline PP. CONSTITUTION:10-40wt% inorg. filler, such as talc, having an aspect ratio of 5 or above, pref. 8 or above as uniformly dispersed in a state of a primary particle and having an average particle size of 5mu or below, pref. 3 or below in the direction of the major axis, and 5-30wt% of ethylene/alpha-olefin copolymer having an ethylene content of 40-85wt%, an average particle size of 0.5-4mu, pref. 1-3mu and an intrinsic viscosity of 2.5 or below as measured in xylene soln. at 70 deg.C, such as an ethylene/butene-1 copolymer, are blended with crystalline PE. The mixture is kneaded at a shear rate of 2X10<2> 1/sec or above.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a polypropylene resin composition having excellent rigidity, heat resistance, and impact resistance. In the past, many resin compositions have been proposed that have improved rigidity and heat resistance by simply blending fillers such as talc and calcium carbonate with polypropylene resin, but they have the drawback of significantly impairing impact strength. can be seen. In order to improve the drawback of reduced impact strength, Japanese Patent Publication No. 66-8874 conducted various studies on non-grade ethylene-a-oletuin copolymers to further improve the strength at 70°C. It was discovered that the average particle diameter of the amorphous ethylene-α-olefin copolymer has a great influence on the impact strength of the composition. or,
As a result of various studies regarding inorganic fillers, we found that the particle size of inorganic fillers is conventionally defined as impact strength, which is defined by JI8 7110. It has been found that there is almost no correspondence between the practical impact strength of a molded product and the conventional Izotsu impact strength, and the impact strength described in this invention is not the Izotsu impact strength, but the DuPont type impact strength, which is close to the practical impact strength. Indicates impact strength.

The present invention mainly consists of crystalline polypropylene, uniformly dispersed in the state of primary particles, with an aspect ratio of 6 or more, preferably 8 or more, and an average particle diameter in the major axis direction of 6μ or less, preferably 8
The inorganic filler □ below μ is included in the composition from lO to 40 Wt*
and an amorphous ethylene-α olefin copolymer with an ethylene composition ratio of 40 to 85 Wt* controlled to have an average particle size of 0.5 to 4 μ, preferably 1 to 8 μ, in the composition.
This invention relates to a polypropylene resin composition with excellent impact strength characterized by containing 0 Wt*.The present invention will be explained in more detail below.

The crystalline polypropylene used in the present invention is a polypropylene homopolymer obtained by polymerizing only propylene in the presence of a propylene polymerization catalyst, or a polypropylene homopolymer obtained by polymerizing only propylene in the presence of a propylene polymerization catalyst, or a polypropylene homopolymer made of propylene and ethylene or butene.
This shows a copolymer with a-olefin such as No. 1. The filler used in the present invention is an inorganic filler having an aspect ratio of 6 or more, preferably 8 or more, and an average particle size in the major axis direction of 5μ or less, preferably 8μ or less, and the amount used is 10 to 4Q with respect to the composition.
vt%. If the aspect ratio of the filler is smaller than 5, the reinforcing effect is small and high rigidity cannot be obtained. Furthermore, when the average particle diameter in the major axis direction exceeds 5 μm, our results show that the impact strength of the composition suddenly decreases. Regarding the amount used, if it is filled in excess of 4Qwt%, the impact strength will decrease and the fluidity will decrease or become thicker.
If the Wtg is less than 6, the contributions of rigidity and thermal properties are small, making it impossible to obtain balanced physical properties.

The non-quality ethylene-a-olefin copolymer used in the present invention refers to a copolymer of ethylene and an a-olefin such as propene and butene-1.

In addition, other polymeric components such as butadiene, ethylidenenorbornene, 1.4 dicycloq diene, styrene-
It also means a multicomponent copolymer with butadiene rubber etc. that has rubbery properties.

Among these copolymers, non-grade ethylene-propylene copolymers and amorphous ethylene-propylene copolymers are preferred.The non-grade ethylene-propylene copolymers used in the present invention are The ultimate fineness measured with a silene solution is 2.0 or less, and the ethylene composition ratio in the copolymer is 40 ~ @ 5 wt4
is preferable, and 46 to 80 w1@It is more preferable. or,
The non-grade ethylene butene copolymer has an intrinsic viscosity of 1.5 or less) and an ethylene composition ratio of 76 to 9Q in the copolymer.
Wt% is preferred, and 80 to 90 Wt* is more preferred.

If the intrinsic viscosity of these inferior ethylene-a olefin copolymers is larger than the claimed range of 4I'WIf, the fluidity of the composition will be reduced, and even if high shear is applied during cross-talk, the particle size of the copolymer will be 4μ. Since the dispersibility in the resin also decreases, the impact strength decreases significantly.

Furthermore, if the ethylene composition ratio of the non-quality ethylene-olefin copolymer is larger than the claimed range, the copolymer loses its rubber elasticity and the effect of improving impact strength is small. Furthermore, if the ethylene composition ratio is less than the claimed range, the stiffness of the composition is greatly reduced, which is disadvantageous. The amount used is 6 in the composition.
~@Q wt% is preferred, and 6 to 25 wt% is even more preferred. If the amount used exceeds BOwt Excellent, the rigidity and heat resistance will be greatly reduced, making it difficult to obtain balanced physical properties, and if the amount is less than 5 wt%, the effect of improving impact resistance will be small.

The essential conditions of the present invention are to uniformly disperse the inorganic filler in the composition in the form of primary particles and to control the average particle size of the non-grade ethylene-a-olefin copolymer to 0.5 to 4 microns. Our results show that there is a close relationship between the average particle size of the copolymer and the impact strength of the composition, and it is clear that the impact strength is maximum when the average particle size is 1 to 8μ. Tonatsu Nine.

Various conventionally known methods can be used to produce the composition of the present invention.

Typical examples thereof include a method using an extruder, a roll, a mixer such as a Banbury, a method of producing the composition during the production of polypropylene, and a method of combining both.

Regarding the method using a kneading machine, in order to satisfy the above conditions, the so-called shear rate, expressed as circumferential speed/gap, is set to 2.
It is necessary to knead the mixture at a temperature of X 10” Vsec or higher.

If the breaking speed is less than 2 x 10" 1/see, no matter how long the kneading time is, the uniform dispersion of the filler in the primary particles in the composition and the particle size of the ethylene-α-olefin copolymer will be poor. % is not within the claimed range, and the impact strength of the composition is greatly reduced, making it impossible to satisfy the present invention.Banbury mixer-1 special is used as a mixer that provides a shear rate of 2 x 10" 1/see or higher. There is a two-shaft mixer.

As a method for obtaining the composition of the present invention during the production of polypropylene, it is possible to use a so-called block copolymerization technique in which ethylene and α-olefin are polymerized successively after polypropylene polymerization.

Inorganic fillers can also be added during polymerization. However, a method of mixing the polymers with a suitable mixer is also a preferred manufacturing method. The ethylene-α-olefin copolymer portion formed by block copolymerization forms relatively small particle sizes, but the method of controlling the particle size to the desired size in the present invention by reagglomeration due to crosstalk is more practical. It's a method.

In the present invention, in order to improve the fluidity and impact strength of the composition, it is preferable to add higher fatty acids or salts thereof, and surfactants.
More preferred are fatty acids of ts or higher and salts thereof. Various antioxidants, ultraviolet absorbers, lubricants, pigments, nucleating agents, antistatic agents, etc. conventionally used in polypropylene may be added to the polypropylene S81 composition according to the Okamoto invention. . The amount generally used for polypropylene is sufficient. Examples will be shown below to clarify the content of the present invention. The bending stiffness and Izo/Soto impact strength are MU8TMD7g□ and JI respectively.
Measured with 7110 on 8th. The DuPont impact strength was measured using a jig of JI8 K-6400 on a 2 m dollar flat plate molded product in an atmosphere of 0° C., and the energy at half-breakage was measured. The particle size of the non-quality ethylene-a-olefin copolymer in each composition was measured using an electron microscope.

Examples 1-2 Crystalline polypropylene homopolymer (MI=8) 64,
Talc g5wt with an average particle size of 8μ in 6 Wt*
20 wt* of an amorphous ethylene-propylene copolymer with an intrinsic viscosity of 1.6 measured in a xylene solution at 70°C and an ethylene composition ratio of 65 wt* in the copolymer, and stearic acid strength/I/F um. A mixture of 0.6Wt* is used.
After boiling in a mixer for 4 minutes, use a mixer to bring the temperature to 180~2.
Knead at 20°C with different shear rates to form pellets into circles.

These pellets are molded into Tes F pieces using a screw-in-twin molding machine at a resin temperature of 280°C, and the particle size, flexural rigidity, Izotsu impact strength, and DuPont formula of the non-quality ethylene-propylene copolymer in the composition are Impact strength was measured. Table 1 shows these measurement results in comparison with the control example.

Example 8 The intrinsic viscosity of a non-quality ethylene-propylene copolymer measured in a xylene solution at 70°C was 1. The experiment was carried out under the same conditions as in Example 2, except that the ethylene composition ratio of the copolymer changed to a non-grade ethylene-butene copolymer with an ethylene composition ratio of 85 Wtlm.

Table 2 shows the results of this measurement in comparison with the control example.

Claims (1)

[Claims] l) The polypropylene is mainly composed of crystalline polypropylene, which is uniformly dispersed in the form of secondary particles and has an aspect ratio of 5 or more, preferably 8.
In the above, an inorganic filler with an average particle diameter of 8 degrees in the long axis direction of 5 μ or less, preferably 8 μ or less, and an inorganic filler with an average particle diameter of 0.5 to 4 μ, preferably 1 to 8 μ, are used. ethylene-a olefin co-merged 6~8゜w
t* (each based on the weight of the composition) and t
% mold and has excellent impact strength. 2.5 or less, and the ethylene content is 40 to 85
The composition of claim l) which is a non-grade ethylene-propylene copolymer of Wt*. 1.6 or less, and contains ethylene, with an amount of 7b to 90
The composition of claim FMl) which is an amorphous ethylene-butene copolymer with a predominant Wt content. 4) The composition according to claim 1), wherein the inorganic filler is talc.