JPH0699613B2 - Inorganic filler-containing polypropylene resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention comprises a specific ethylene / propylene block copolymer, a specific ethylene / propylene copolymer rubber, and an inorganic filler surface-treated by a specific method. rigidity,
The present invention relates to a polypropylene resin composition containing an inorganic filler, which has an excellent balance of physical properties such as impact resistance, heat resistance, surface characteristics, molding fluidity, and appearance (weld).

[Conventional technology]

It has been widely practiced for a long time to improve rigidity, impact resistance, heat resistance, etc. by blending polypropylene resin with ethylene / propylene copolymer rubber and an inorganic filler. In order to satisfy the requirement, it is not enough to simply knead the above substances, and some improvement methods have been proposed.

Among them, by treating the surface of the inorganic filler with various treatment agents to improve the affinity with polypropylene and the dispersibility, a method for further improving the physical property balance between rigidity and impact resistance has become widely used. .

As the surface treatment method of the inorganic filler, the inorganic filler and various surface treatment agents, or if necessary, various solvents are charged into a Henschel mixer or the like and stirred at room temperature or high temperature to chemically or physically surface the surface. The method of processing is well known.

[Problems to be solved by the invention]

However, although the polypropylene resin composition containing the inorganic filler surface-treated by such a method is improved in various properties such as rigidity, impact resistance, and heat resistance,
It may not be said to be sufficient yet, and depending on the type of the inorganic filler, there may be no effect or the rigidity may be reduced. Also, since the surface treatment process is complicated, productivity,
There is a problem in terms of safety and the like, and there is a drawback that the cost becomes high.

An object of the present invention is to provide an inorganic filler-containing polypropylene resin composition that solves the above-mentioned drawbacks.

[Means for solving problems]

The present inventors earnestly studied to achieve the above object, and finally completed the present invention.

That is, the present invention comprises (a) crystalline ethylene having an ethylene content of 4 to 30% by weight, a boiling n-heptane insoluble matter (II) of 65% by weight or more, and a melt flow index (MI) at 230 ° C. of 5 g / 10 minutes or less. -Propylene block copolymer 40 to 87 parts by weight,
(B) Propylene content 40 to 90% by weight, Mooney viscosity (ML
_{1 + 4} (100 ° C)) 3 to 20 parts by weight of ethylene / propylene copolymer rubber of 10 to 100, (c) 100 parts by weight of inorganic filler and 0.01 to 5 parts by weight of surface treatment agent are both jet stream type pulverizers. Surface-treated inorganic filler obtained by pulverizing with 10-40
A polypropylene resin composition containing an inorganic filler, characterized in that a composition comprising 0.005 to 0.5 parts by weight of (d) an organic peroxide and (d) is heat-treated at a temperature of 170 to 280 ° C.

Furthermore, a preferred embodiment of the present invention is that the milling process is by a jet stream mill, and
The jet stream type pulverizer is a fluidized bed type jet pulverizer, and the inorganic filler is talc.

The polypropylene resin used in the present invention is a crystalline ethylene / propylene block copolymer having an ethylene content of 4 to 30% by weight, II of 65% by weight or more and MI of 5 g / 10 minutes or less. When the ethylene content is less than 4% by weight, the impact resistance of the resulting composition is lowered, and when it exceeds 30% by weight, the heat resistance and the rigidity are lowered, which is not preferable. II is 65% by weight or more, preferably 70% by weight or more, and if less than 65% by weight is used, the heat resistance and rigidity of the obtained composition are lowered, which is not preferable.

Furthermore, MI must be 5g / 10 minutes or less, and 5g / 10
If the amount exceeds the limit, the fluidity after heat treatment becomes too large and the impact resistance decreases, which is not preferable. Further, in order to prevent this, it is necessary to add the organic peroxide in an amount of 0.005 parts by weight or less, which is not preferable because the effect of improving the appearance of the product, particularly the easiness of conspicuous weld lines, becomes small.

The mixing ratio of the crystalline ethylene / propylene block copolymer in the present invention is 40 to 87 based on the total composition excluding the organic peroxide.
If the amount is less than 40 parts by weight or more than 87 parts by weight, the balance of physical properties such as rigidity and impact resistance of the resulting composition is deteriorated, which is not preferable.

The ethylene / propylene copolymer rubber used in the present invention is
Propylene content 40-90% by weight, Mooney viscosity (ML _{1 + 4}
(100 ° C)) is preferably 10 to 100, and if the propylene content is less than 40% by weight, flow marks and the like are likely to occur in the product, and the effect of improving the conspicuousness of the weld line becomes small, It is not preferable because the appearance is deteriorated.
On the other hand, if the propylene content exceeds 90% by weight, the productivity and properties are poor, the handling is difficult, and it is not suitable for use. When the ethylene / propylene copolymer rubber having ML _{1 + 4} (100 ° C.) of less than 10 or more than 100 is used, the particle diameter of the ethylene / propylene copolymer rubber dispersed in the obtained composition is small, or Getting too big,
The physical properties of the resulting composition are unfavorably deteriorated.

The ethylene / propylene copolymer rubber used in the present invention has an ethylene / propylene copolymer rubber having the above propylene content.
It also includes a propylene / diene copolymer rubber.

The blending ratio of the ethylene / propylene copolymer rubber in the present invention is 3 to 20 parts by weight of the whole composition. If it is less than 3 parts by weight, the impact resistance of the resulting composition is lowered and exceeds 20 parts by weight. In this case, the rigidity and heat resistance are deteriorated, which is not preferable.

As the inorganic filler used in the present invention, for example,
Calcium oxide, magnesium oxide, diatom oxide, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, calcium carbonate, magnesium carbonate, calcium silicate, magnesium silicate, calcium sulfate, barium sulfate, calcium sulfite, talc, car, clay,
Dolomite, basic magnesium carbonate, glass and the like can be mentioned, with talc being most preferred.

The particle size of the inorganic filler used in the present invention varies depending on the type and amount used, but the uniformity of the treatment, the compatibility with the resin, the physical property balance in the resin composition, and the like,
The average particle size after the treatment is preferably 10 μm or less, more preferably 8 μm or less.

Examples of the surface treatment agent used in the present invention include organic silane coupling agents, titanium coupling agents, various surfactants, silicone oils, various silane compounds, metal soaps, higher alcohols, poi olefins and unsaturated carboxylic acid modified polyolefins. Etc.

The ratio of the inorganic filler to the surface treatment agent is usually preferably 0.01 to 5 parts by weight with respect to 100 parts by weight of the inorganic filler. That is, 0.01 parts by weight or more is preferable in terms of increasing the surface treatment effect, while the rigidity of the obtained resin composition,
From the viewpoint of improving the balance of physical properties such as impact resistance, heat resistance, and surface characteristics, it is preferably 5 parts by weight or less. If the amount exceeds 5 parts by weight, not only the rigidity and impact resistance may decrease, but also the cost increases, which is not preferable in any case.

The surface treatment of these inorganic fillers, pre-mixing the inorganic filler and the surface treatment agent, or separately supplied to the crusher,
It can be done by dry or semi-dry method by crushing and surface treatment simultaneously.

Here, the crusher may be any one that can be finely crushed by a dry or semi-dry method, and examples thereof include a crusher such as a micron mill, a jet stream crusher, a ball mill, a micronizer, a turbo mill, and an atomizer. However, from the viewpoint of pulverization efficiency, pulverization time, workability, jet stream type pulverizers such as macronizer type, reduction type, impact type, facing type and fluidized bed type are preferable, and among them,
A fluidized bed type jet pulverizer in which the surface treatment is more uniformly performed is particularly preferable.

The mixing ratio of the inorganic filler treated in the present composition is preferably 10 to 40 parts by weight of the entire composition, and if less than 10 parts by weight, the resulting composition has improved rigidity, heat resistance and surface properties. Is small, and if it exceeds 40 parts by weight, the impact resistance is lowered, so that it is not preferable in any case.

Examples of the organic peroxide used in the present invention include di-t-butyl peroxide, t-butyl peroxypivalate, lauroyl peroxide, benzoyl peroxide, cyclohexanone peroxide, t-butyl peroxyisopropyl carbonate, t-butyl. Peroxybenzoate, methyl ethyl ketone peroxide, dicumyl peroxide, 2,5-dimethyl-2,5 di (t-butylperoxy) hexane, di-t-butylperoxide, 2,5-dimethyl-2,5- Di (t-butylperoxy) hexyne-3 and the like can be mentioned. These may be used alone or in combination of two or more.

The amount of organic peroxide added is usually 0.00 of the total composition.
It is 1 to 0.5 parts by weight, preferably 0.01 to 0.3 parts by weight. 0.0
If the amount is less than 01 parts by weight, the resulting composition has a small fluidity and is inferior in molding fluidity, flow marks and the like are generated in the product, the effect of improving the visibility of the weld line is reduced, and the appearance is deteriorated, which is not preferable. Further, if it is used in excess of 0.5 parts by weight, the molecular weight of the obtained composition becomes too small, which is not practically suitable.

Antioxidants, heat stabilizers, ultraviolet absorbers, flame retardants, nucleating agents, organic or inorganic pigments and the like, which are usually added to polypropylene resins, may be used alone or in combination as long as the effects of the present invention are not significantly impaired. I don't mind. Further, if necessary, a polyolefin resin other than the resin used in the present invention can be used in combination.

In the present invention, the components (a) to (d) are mixed using a Henschel mixer or the like generally used in the art. As a heat treatment method, a Banbury mixer,
Although there is a method of using a hot roll or the like, generally, a method of melting and kneading into pellets using a single-screw extruder or a twin-screw extruder is preferable. The temperature of the extruder in this case is appropriately determined depending on the type of the crystalline ethylene / propylene block copolymer used, the type of the organic peroxide and the addition amount thereof, but is controlled to 170 to 280 ° C. in the present invention. It is necessary. At a temperature of 170 ° C. or lower, thermal degradation is not sufficiently performed, and the effects of the present invention cannot be sufficiently obtained. Further, even if the heat treatment is performed at a temperature of 280 ° C. or higher, the effect of the heat treatment does not increase so much, and if the temperature is too high, the resin composition is thermally decomposed, which is not preferable.

The resin composition thus obtained can be molded into a predetermined molded product by a commonly used molding method such as an injection molding method, an extrusion molding method and a compression molding method.

〔Example〕

 Hereinafter, the present invention will be described with reference to examples.

In the following description, melt flow index (MI)
Was measured according to ASTM D-1238, flexural modulus was measured according to ASTM D-790, Izot impact strength was measured according to ASTM D-256, and heat distortion temperature was measured according to ASTM D-648.

The surface characteristics were visually determined by the following method.

Sample 80 × 160 × 2 mm convex area about 3 mm ² oval shape with a depth of about 0.1 mm
A flat plate with a grain (However, red iron oxide: carbon black 5: 1
1 part by weight of the pigment is added to 100 parts by weight of the sample composition for coloring.) Judgment method With a pencil scratch tester shown in JIS K-5401, attach a 0.5R brass rod at the tip instead of a pencil, and load it. The surface of the sample was scratched at 0.8 kg and the degree of scratching was determined.

Judgment Criteria ◎: No scratches are observed ○: 〃 Almost not observed △: 〃 Somewhat recognized ×: 〃 Accepted The visibility of the weld line was visually evaluated by the following method.

Sample 80 × 240 × 2mm, flat plate with a hole of 20mmφ at the center of 80mm from the gate (Bengala: carbon black = 5: 1
(1 part by weight of the pigment is added to 100 parts by weight of the sample composition for coloring) Criteria ○: Weld line hardly noticeable Δ: 〃 somewhat conspicuous ×: 〃 quite conspicuous 1) Raw materials Talc: Normal particle size distribution with an average particle size of about 10 μm Mica: Normal particle size distribution with an average particle size of about 15 μm Calcium carbonate: Heavy calcium carbonate with an average particle size of 3 μm (2) Crusher And grinding conditions Grinding machine: Fluidized bed type counter jet mill (400AFG type manufactured by Albine, West Germany) Grinding pressure: 6kg / cm ² (using compressed air) Classifier rotation speed: 4000rpm (3) Surface treatment agent and addition amount table Shown in 1.

(4) Treatment method The raw material described in (1) and the surface treatment agent described in (3) were separately fed to the pulverizer described in (2) for pulverization surface treatment.

Inorganic fillers, polypropylene resins, ethylene / propylene copolymer rubbers and organic peroxides used in the following Examples and Comparative Examples are shown in Tables 1 to 4.

Examples 1 to 15 and Comparative Examples 1 to 9 The above polypropylene resin, ethylene / propylene copolymer rubber, inorganic filler and organic peroxide are added at a ratio shown in Table 5 with a small amount of antioxidant, metal soap and the like. Then
After mixing with a Henschel mixer, it was pelletized with a 40 mmφ uniaxial extruder at 230 ° C., and the obtained pellets were molded into predetermined test pieces at 230 ° C. with an injection molding machine, and various physical properties were measured.

The results obtained are shown in Table 5.

[Effects of the invention] As is clear from Table 5, only in the case of the present invention, all of bending elasticity, impact strength, thermal deformation resistance and surface characteristics are good.

The polyolefin resin composition containing an inorganic filler according to the present invention has an excellent balance of physical properties such as rigidity, impact resistance, heat resistance and surface characteristics, and is suitable for industrial parts such as automobile parts and home electric appliance parts.

Claims (2)

[Claims] 1. (a) Ethylene content 4 to 30% by weight, boiling n
-Crystalline ethylene / propylene block copolymer having a heptane insoluble content (II) of 65% by weight or more and a melt flow index (MI) at 230 ° C of 5 g / 10 minutes or less 40 to 87 parts by weight (b) Propylene content 40 ~ 90% by weight, Mooney viscosity (ML
_{1 + 4} (100 ° C)) is 10 to 100, ethylene-propylene copolymer rubber 30 to 20 parts by weight (c) 100 parts by weight of inorganic filler and 0.01 to 5 parts by weight of surface treatment agent are both jet stream type pulverizers Surface-treated inorganic filler obtained by pulverizing at 10 to 40 parts by weight (d) Organic peroxide 0.005 to 0.5 parts by weight, a composition comprising an inorganic filler characterized by being heat-treated at 170 to 280 ° C. Polypropylene resin composition. 2. The polypropylene resin composition containing an inorganic filler according to claim 1, wherein the jet stream type pulverizer is a fluidized bed type jet stream type pulverizer.