JPH02173048A - Inorganic filler-containing polyolefin resin composition - Google Patents

Abstract

PURPOSE:To prepare an inorg. filler-contg. polyolefin resin compsn. with a remarkably improved impact strength, esp. falling weight impact strength, without impairing the other properties such as rigidity by dispersing an inorg. filler of a specific particle diameter and a specific shape in a polyolefin resin to a high degree of dispersion. CONSTITUTION:An inorg. filler with an aspect ratio of a unit particle of 1.0-2.5 and a number-average diameter of the unit particle of 0.05-2mum (e.g. precipitated calcium carbonate or ground whiting) is dispersed in a polyolefin resin (e.g. polyethylene, or ethylene-vinyl acetate copolymer) to such a high degree of dispersion that the dispersion index is 2.5 or lower. The resulting compsn., when compared with a conventional inorg. filler-containing polyolefin resin, has a remarkably improved impact strength, esp. falling wt. impact strength (du Pont impact strength), without being impaired in the other properties such as rigidity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a novel polyolefin resin composition containing an inorganic filler. More specifically, the present invention improves impact resistance, especially falling weight impact (DuPont This invention relates to a polyolefin resin composition with dramatically improved impact strength.

[Prior Art] Conventionally, inorganic fillers have been widely added to polyolefin resins for the purpose of improving their rigidity, heat resistance, dimensional stability, paintability, and the like.

However, polyolefin resin compositions containing inorganic fillers usually do not have very high impact strength, especially falling weight impact (Dupont impact) strength, so for applications that require high impact strength, such as propylene-ethylene Attempts have been made to incorporate rubber components such as copolymer rubber, but in this case a problem arises in that the effect of improving rigidity by incorporating an inorganic filler is significantly reduced.

Various attempts have been made to solve these problems. For example, a polypropylene composition in which fine calcium carbonate of a specific particle size is blended with polypropylene has been proposed (Japanese Patent Publication No. 1983-1999). 31538, JP-A-56-120742).

However, in such compositions, it is difficult for the fine particles of the inorganic filler to be uniformly dispersed due to interparticle forces, and they tend to form aggregates in the composition, which makes it particularly difficult to improve the falling weight impact strength. The drawback was that it had its limitations.

[Problems to be Solved by the Invention] The present invention overcomes the drawbacks of conventional techniques for improving the impact resistance of polyolefin resins, and improves the impact resistance, without impairing physical properties such as rigidity. In particular, the purpose of this invention is to provide a polyolefin resin composition that has dramatically improved falling weight impact (DuPont impact) strength.

[Means for Solving the Problems] As a result of extensive research into polyolefin resin compositions with an excellent balance of rigidity and impact resistance, the present inventors have discovered that spherical inorganic fillers with a specific particle size can be dispersed into The condition is expressed by a parameter called a dispersion index, and by highly dispersing it in a polyolefin resin within a limited range of dispersion index, impact resistance, especially falling weight i, can be improved without reducing rigidity. ! Ti! II (Dupont impact) strength was dramatically improved and the above objective was achieved, and based on this knowledge, the present invention was completed.

That is, in the present invention, the aspect ratio of (A) polyolefin resin and (B) unit particles is 1.0 to 2.5,
Provided is an inorganic filler-containing polyolefin resin composition, which contains an inorganic filler whose unit particles have a number average diameter of 0.05 to 2 μm, and has a dispersion index of 2.5 or less. .

The present invention will be explained in detail below.

In the composition of the present invention, Sea 1 used as component (A),
Examples include homopolymers of a-olefins such as 3-methylpentene-1,4-methylpentene-1, copolymers thereof, and copolymers of unsaturated monomers copolymerizable with these and other unsaturated monomers. .

Typical examples include high-density, medium-density, and low-density polyethylene, linear low-density polyethylene, ultra-high molecular weight polyethylene, polyethylenes such as ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, and atactic polyethylene. , syndiotactic, isotactic polypropylene, polypropylenes such as propylene-ethylene block copolymers or random copolymers, and poly4-methylpentene-1. One type of these polyolefin resins may be used, or two or more types may be used in combination.

In the composition of the present invention, the inorganic filler used as component (B) has a unit particle aspect ratio of 1.0 to
2.5, and the number average diameter of unit particles is 0.0
It is necessary to use a material in the range of 5 to 2 μm. The aspect ratio of the unit particle referred to here refers to the aspect ratio of the smallest particle that composes the inorganic filler that is observed when observing the inorganic filler using an electron microscope. / minor axis of unit particle)
is measured for 500 unit particles, and the value obtained by taking the number average.

On the other hand, the number average diameter of unit particles is determined by measuring the major axis of 500 unit particles observed with an electron microscope, and formulating the number average diameter of unit particles - d l + d z + d 3+ ... + d .

(where d is the major axis of the i-th unit particle, and n is the number of measured unit particles, that is, 500).

If the aspect ratio and number average diameter of the unit particles of the inorganic filler deviate from the above ranges, the object of the present invention will not be fully achieved.

The type of inorganic filler is not particularly limited as long as the aspect ratio and number average diameter of its unit particles are within the above ranges. Specific examples of inorganic fillers include:
Silica, beryllium oxide, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, barium sulfate, clay, carbon black, etc., or zinc, copper, iron, lead, aluminum, nickel, chromium,
Metal elements such as titanium, manganese, tin, platinum, tungsten, gold, magnesium, cobalt, strontium and oxides of these metals, stainless steel, solder, alloys such as brass, silicon carbide, silicon nitride, zirconia,
Examples include powders of metal-based ceramics such as aluminum nitride and titanium carbide, and among these, calcium carbonates such as precipitated lucicum carbonate and heavy calcium carbonate are particularly suitable. These inorganic fillers may be used alone or in combination of 2ff or more.

In the present invention, the inorganic filler can be used after surface treatment with a known surface treatment agent, if desired.

Examples of the surface treatment agent include saturated higher fatty acids or derivatives thereof such as stearic acid and balmitic acid, unsaturated higher fatty acids such as oleic acid or derivatives thereof, fluorine-based coupling agents, titanate-based coupling M, silicone oil, and higher-grade fatty acids. Examples include alcohol, and these are 1
A species may be used, or two or more species may be used in combination.

There are no particular limitations on the method of surface treating the inorganic filler using these surface treating agents. For example, the surface treating agent may be sprayed onto the inorganic filler in a Henschel mixer, mixed and stirred. Alternatively, the treatment may be carried out simultaneously during the production stage of the inorganic filler.

The content ratio of the polyolefin resin as the component (A) and the inorganic filler as the component (B) in the composition of the present invention is usually selected in the range of 60:40 to 95:5 on a weight basis. If this content ratio deviates from the above range, the effect of improving impact resistance will not be sufficiently exhibited.

Undesirable.

In the composition of the present invention, the inorganic filler has a dispersion index of 2.
．． It is necessary to have a high degree of dispersion so that the number of particles is 5 or less. The dispersion index referred to here means that a polyolefin resin composition containing an inorganic filler is plane-cut using an ultra-thin sectioning machine (ultra-microtome) equipped with a glass knife, and the cut surface is cut using a scanning electronic Ijl microscope. , and measure the major axis of the region of inorganic filler with a particle size of 2 μm or more that appears on the cutting surface. The major axis, A is the total area of the observation surface, and π is the circumference of pi. Note that during cutting, it is preferable to cool the sample with liquid nitrogen, and the measurement uses five or more sample pieces randomly taken out from the composition, and the area A of the observation surface is 5 ms+''.

For compositions with a dispersion index of more than 2.5, impact strength,
In particular, the falling weight impact (DuPont impact) strength is not sufficiently high, and the object of the present invention cannot be achieved.

The composition of the present invention may include other thermoplastic resins, modified polyolefins, fibrous inorganic fillers, organic fillers, antioxidants, light stabilizers, heat stabilizers, lubricants, Catalyst neutralizers (halogen scavengers), antistatic agents, flame retardants, colorants, mold release agents, and the like can be added as desired.

Examples of thermoplastic resins having the above properties include polyvinyl chloride resins, polyamide resins, polyimide resins, polyester resins, polyacetal resins, polycarbonate resins, polyaromatic ether or thioether resins, and polyaromatic ester resins. Examples include resins, polysulfone resins, styrene resins, and acrylate resins.

Examples of modified polyolefins include unsaturated organic acids or derivatives thereof, such as acrylic acid, methacrylic acid, maleic acid, and itaconic acid; unsaturated organic acids such as maleic anhydride, itaconic anhydride, and citraconic anhydride; Ethylene anhydrides, esters of unsaturated organic acids such as methyl acrylate and monomethyl maleate, amides of unsaturated organic acids such as acrylic acid amide and fumaric acid monoamide, and imides of unsaturated organic acids such as itaconic acid imide. or 100 parts by weight of propylene polymer, usually 0.
Examples include those modified by a grafting method by adding 05 to 20 parts by weight. In this modification, organic peroxides such as benzoyl peroxide, lauroyl peroxide, dicumyl peroxide, and L-butylhydroperoquine are used to promote modified polymerization.

In addition to the above, there are also products in which ethylene or propylev-based 21 combinations are graft-modified with unsaturated epoxides such as grindyl acrylate, glycidyl methacrylate, vinyl glycidyl ether, and allyl grindyl ether, and in the case of such graft modification. It is also possible to use liquid rubbers such as polybutadiene with hydroquinyl terminals added thereto.

Examples of the fibrous inorganic filler include glass fiber, carbon fiber, poron fiber, aluminum fiber, stainless steel fiber, copper fiber, brass fiber, nickel fiber, silicon carbide fiber,
Examples include single crystal potassium titanate, other single metal fibers, metal fibers such as alloy fibers, and metal whiskers corresponding to these. Examples of organic fillers include rice husk fiber, wood flour, cotton, jute,
Examples include paper strips, cellophane strips, aromatic polyamide fibers, cellulose fibers, nylon fibers, polyester fibers, and polypropylene fibers.

Preferable examples of antioxidants include phenol-based and phosphorus-based antioxidants, and combinations of these are particularly preferred. As a phenolic antioxidant, for example, 2.6
-di-t-butyl-4-methylphenol, tris(3
, 5-di-t-butyl-4-hydroxybenzyl)isone anurate (manufactured by Ciba Geigy, Irganox31
14), 2,2'-methylenebis(4-ethyl-6-7-butylphenol), n-tadecyl-3-(3'
, 5'-di-t-butyl-4''-hydroxyphenyl)
Propionate (manufactured by Ciba Geigy, Irganox1
076), 4,4'-thiobis(3-methyl-6-t-
butylphenol), tetrakis[methylene-3-(3
',5'-di[-butyl-4'-hydroxyphenyl)propionate J methane (manufactured by Ciba Geigy, Ir
ganoxlolo), 4.4″-butylidene bis(3
-methyl-6-t-butylphenol), 2,2'-methylenebis(4-methyl-6-(=butylphenol)
, N,N'-hexamethylenebis(3,5-di[-butyl-4-hydroxyhydrocinnamide) (manufactured by Ciba Geigy, Irganox109B), triethylene glycol-bis[3-(3''-t- butyl-5'-methyl-4''-hydroxyphenyl) 70 bionate], a mixture of bis(3,5-di-t-butyl-4-hydroquine benzylethylphosphonate) calcium and PE wax (weight ratio 1:l) (manufactured by Ciba Geigy, trade name). Examples of phosphorus antioxidants include stearylpentaerythritol diphosphite, tetrakis(24-di-t-butyl-7enyl)-4,4''-
Biphenylene diphosphite (manufactured by Su'do Co., Ltd., 5ando
stab P-EPQ), trisnonylphenyl phosphite, tris(2,4-di-t-butylphenyl)
Examples include phosphite.

Examples of light stabilizers used include salicylates, benzphenones, triazoles, oxalic acid anilides, and hinderamines. Examples of lubricants include stearic acid amide, palmitic acid amide, oleic acid amide, and erucic acid. Examples of catalyst neutralizing agents include higher fatty acid metals such as calcium stearate, magnesium stearate, and hydrotalcite.

The method for preparing the inorganic filler-containing polyolefin resin composition of the present invention is not particularly limited as long as it is a method that disperses the inorganic filler so that the dispersion index is 2.5 or less. For example, it can be prepared by melt-kneading each component under strong mixing conditions using a Henschel mixer, an axle or twin-screw extruder, a Banbury mixer, a roll, or the like.

It is desirable that the resin temperature during this melt-kneading does not exceed the deterioration temperature in order to prevent a decrease in impact resistance due to deterioration of the resin.

Conventionally, polyolefin resin compositions containing inorganic fillers are
Although it has been prepared using the above-mentioned kneading machine under strong mixing conditions, the impact resistance, particularly the falling weight impact (DuPont impact) strength, was not fully satisfactory.

Although kneading has been carried out on the premise of homogeneous dispersion under strong crosstalk conditions, the dispersion state has not been quantitatively evaluated, and in reality, appropriate crosstalk conditions and methods have not been adopted. It depends on what happened.

In contrast, in the present invention, the falling weight impact (Dupont impact) strength is significantly improved by controlling the operating conditions of the kneading machine so that the dispersion index of the inorganic filler is 2.5 or less. A polyolefin resin composition containing an inorganic filler can be easily obtained.

Incidentally, even if the mixing conditions are set to be the same, the flow of resin within the kneading machine is affected by the temperature around the kneading machine, and as a result, the modulus dispersion index is also affected by external conditions such as the temperature. Therefore, in order to control the dispersion index to 2.5 or less, it is not possible to uniformly specify the crosstalk conditions, but the present inventors
As a result of intensive study, for example, a two-axis mixed a! IFCM(lft-
When dispersing carbonate into polypropylene at a mixing speed of 2 inches, three operating conditions are set: the amount of resin and inorganic filler supplied, the rotation speed of the rotor, and the size of the resin outlet opening. It was found that the resin temperature should be adjusted to 225 to 240°C. With this kind of operation, the kneading machine is not affected by the temperature around the kneading machine.
Moreover, the dispersion index can be made 2.5 or less, and the falling weight impact (Dupont impact) strength can be dramatically improved without causing a decrease in the falling weight impact (DuPont impact) strength due to resin deterioration. In addition, when polypropylene was used, deterioration was observed at resin temperatures of 240° C. or higher.

[Example] Next, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited in any way by these examples.

In addition, each physical property of the composition was determined as follows.

(1) Rigidity A three-point bending test was conducted at 23° C. according to JrSK-7203.

(2) Izot impact strength According to JISK-7110, make a notch in the test piece and
Tests were conducted at 3°C.

(3) DuPont impact strength JIS K5400-6 using a 3mm thick test piece.
Using the test equipment shown in Section 13-3, Method B, 23°
The C1 receiver was evaluated under the conditions that the radius of curvature of the plate was 1/4 inch, the load was 500 g, and the falling height was varied.

Examples 1 to 5 80 parts by weight of a propylene polymer with a melt flow index of 4.59/10 minutes was surface-treated with stearic acid to form unit particles with a number average diameter of 0.15 μm and an aspect ratio of 1.2.
After blending 20 parts by weight of synthetic calcium carbonate,
This blend was supplied to 2FCM manufactured by Kobe Steel and kneaded. At this time, the wall temperature of the kneader barrel was set at 200°C, the amount of resin and inorganic filler supplied, the rotation speed of the rotor,
The resin temperature at the kneader outlet was adjusted to a range of 225 to 240°C by setting the three operating conditions of the resin outlet opening size to the values shown in Table 1.

The physical properties of the resin composition thus obtained are shown in Table 2.

The number average diameter and aspect ratio of the unit particles of synthetic calcium carbonate dispersed in the resin composition were measured using a scanning electron microscope and were found to be the same as the values of the raw material before crosstalk.

Comparative Examples 1 to 4 Using 80 parts by weight and 20 parts by weight of the same propylene polymer and carbonic acid as in Examples 1 to 5, the first
A resin composition was prepared under the crosstalk conditions shown in the table. In this case, the resin temperature at the outlet of the kneader cannot be within the range of 225 to 240°C.

Table 2 shows the physical properties of the resin composition thus obtained.

The number average diameter and aspect ratio of the unit particles of synthetic calcium carbonate dispersed in the resin composition were measured using a scanning electron microscope and were found to be the same as those of the raw material for kneading.

Comparative Example 5 Table 2 shows the physical properties of propylene polymer alone without adding an inorganic filler.

(Left below) As can be seen from these tables, the compositions of Examples 1 to 5 have a dispersion index of 2.5 or less, the inorganic filler is highly dispersed in the resin, and the unfilled propylene Compared to polymers, it has improved rigidity, Izot impact strength, and significantly improved falling weight impact (DuPont impact) strength.

In contrast, the compositions of Comparative Examples 1 to 4 had a dispersion index of 2.
5, and the rigidity and Izot impact strength are from Example 1.
5, but falling weight impact (DuPont impact)
The strength does not approach the values of the compositions of Examples 1-5, in which the inorganic fillers are highly dispersed.

Examples 6 to 8, Comparative Examples 6 to B Using the same propylene polymer and calcium carbonate as in Examples 1 to 5, 70 parts by weight and 301 parts by weight, respectively, the third
Resin compositions were prepared in the same manner as in Examples 1 to 5 under the crosstalk conditions shown in the table. Table 4 shows the physical properties of the obtained composition.

In addition, in the DuPont impact test of the compositions of Examples 7 and 8,
Since the sample did not break under the load of 5009 and the strength could not be measured, the load was increased to 10009 and measurements were performed.

The number average diameter and aspect ratio of unit particles of synthetic calcium carbonate dispersed in the resin composition were measured using a scanning electron microscope and were found to be the same as those of the raw material before kneading.

(Left below) As can be seen from these tables, the compositions of Examples 6-B have a dispersion index of 2.5 or less, the inorganic filler is highly dispersed, and the falling weight impact (DuPont impact) strength is low. Remarkably high. On the other hand, the compositions of Comparative Examples 6 to 8 had a dispersion index greater than 2.5, and the falling weight impact strength did not reach the level of Examples 6 to 8.

[Effect of the invention] The inorganic filler-containing polyolefin resin composition of the present invention has an inorganic filler having a specific particle size and shape highly dispersed in a polyolefin resin such that the dispersion index is below a certain value. Compared to conventional inorganic filler-containing polyolefin resin compositions, it has dramatically improved impact resistance, especially falling weight impact (DuPont impact) strength, without sacrificing physical properties such as rigidity. Suitable for use in applications requiring impact resistance.

Claims (1)

[Claims] 1. (A) a polyolefin resin, and (B) an inorganic filler whose unit particles have an aspect ratio of 1.0 to 2.5 and a number average diameter of the unit particles of 0.05 to 2 μm. An inorganic filler-containing polyolefin resin composition characterized in that it contains an inorganic filler and has a dispersion index of 2.5 or less. 2. The composition according to claim 1, wherein the content ratio of the polyolefin resin and the inorganic filler is in the range of 60:40 to 95:5 by weight.