JPS5942014B2 - Polyolefin resin composition for molding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a molding polyolefin resin composition that provides molded articles with significantly improved mechanical properties and surface gloss.

It is known to blend a large amount of a finely powdered inorganic filler into a polyolefin resin to obtain a resin composition with improved properties such as heat resistance, rigidity, and dimensional stability.

However, in such a composition, as the amount of inorganic filler added increases, the mechanical strength of the resulting molded article decreases, and the surface becomes rough, resulting in a significant decrease in surface gloss. Ta. Due to these drawbacks, there has been a problem in that the applications of compositions containing inorganic fillers are severely limited. As a result of extensive research in order to overcome these drawbacks, the present inventors have found that by adding acrylamide together with a small amount of organic peroxide to a composition of polyolefin resin and inorganic filler, this objective can be achieved. The present inventors have found that this can be achieved, and have completed the present invention.

The polyolefin resin in the present invention is a polymer containing an olefin such as ethylene or propylene as a main component,
Copolymers or graft copolymers having these as main chains,
Alternatively, among these mixtures, low-density polyethylene, high-density polyethylene, and polypropylene are preferably used.

Inorganic fillers include carbonates such as calcium carbonate, magnesium carbonate, and barium carbonate; sulfates such as calcium sulfate, barium sulfate, and zinc sulfate; sulfites such as calcium sulfite; kaolin, talc, and clay mica; In addition to silicate minerals classified as clay minerals, quartz fine powder, amorphous silica, alumina, titanium oxide, and oxides such as zinc oxide, mica, glass powder and spheres, glass fiber, and volcanic glass powder are used. , diatomaceous earth, asbestos, carbon black, wollastonite, feldspar, etc., and these have a particle size of 30 μ or less, preferably 10 μ to 0.
A particle size of 2μ is used. The composition of the present invention contains acrylamine and an organic peroxide in addition to the polyethylene resin and inorganic filler.

The use of acrylamide has the effect of improving the surface gloss of resin composition molded products.On the other hand, organic peroxides do not show any effect even when used alone, but when used together with acrylamide, they have the effect of improving mechanical properties. give. Further, since mechanical properties cannot be improved even when acrylamide is used alone, the intended purpose cannot be achieved unless both are used together. Specific examples of the organic peroxide used in the present invention include benzoyl peroxide, lauroyl peroxide, t-butyl peroxide, cumene hydroperoxide, dicumyl peroxide, t-butyl hydroperoxide, α, α-bis (t-butylperoxydiisopropyl)benzene and the like can be mentioned. In addition to the above-mentioned components, the composition of the present invention also includes plasticizers and lubricants commonly used for polyolefin resins.
Auxiliary additives such as stabilizers, pigments, etc. can be added.

Regarding the quantitative ratio of the mixed components in the composition of the present invention, the inorganic filler is 40 to 400 parts by weight, preferably 50 to 200 parts by weight, per 100 parts by weight of the polyolefin resin.
Acrylamide 0.5-40 parts by weight, preferably 1-2
0 parts by weight, organic peroxide 0.005 to 2.0 parts by weight, preferably 0.01 to 1.0 parts by weight.

In the composition of the present invention, this amount of acrylamide is 0.
．． When the amount is less than 5 parts by weight, there is no substantial effect of the addition. On the other hand, the upper limit is not particularly limited, but from an economical point of view it is preferably 40 parts by weight or less. When the amount of organic peroxide is less than 0.005 parts by weight, there is no substantial effect; on the other hand, when it exceeds 2.0 parts by weight, no greater effect can be obtained, and on the contrary, moldability decreases. This is undesirable because it tends to cause decomposition of the polymer. In order to obtain various molded products according to the present invention, the above-mentioned mixed components are uniformly kneaded using a Banbury mixer, an internal mixer, an extruder, a continuous kneader, etc. to obtain a uniform composition, and then pelletized. The pellets or sheets thus obtained are then used as a molding material to form various molded products.

Furthermore, after the above-mentioned mixed components are uniformly mixed using a tumbler mixer or a super mixer, this mixture can be used as a molding material for injection molding. Various molded products obtained using the composition of the present invention as a molding material are different from those obtained from conventional compositions of polyolefin resin and inorganic filler, because they contain acrylamide and organic peroxide specially contained. As a result of this action, its mechanical strength and surface gloss are significantly improved, and it can be applied to applications to which conventional methods could not be applied.

Next, the present invention will be explained in more detail with reference to Examples.

Example 1 Density 0,919/CC Melt Index 8.59/1
When melt-kneading 67 parts by weight of calcium carbonate and a small amount of lubricant (calcium stearate) to 100 parts by weight of polypropylene at 0min in a Banbury mixer,
As shown in the table, acrylamide, α,α'-bis(t-butylperoxy)diisopropylbenzene (hereinafter referred to as PDX)
) was added to obtain various mixed compositions.

The tensile strength and surface gloss of injection molded products of these compositions were measured according to ASTM D-638 and D-523, respectively, and the results are shown in Table 1. Example 2 A molded article was obtained in the same manner as in Example 1 except that the blending ratio of the composition was changed.

The tensile strength and surface gloss of this molded article were as follows.
Example 3 Density 0.929/CC, Melt Index 2.49/
10m1.

Tensile strength of an injection molded article obtained from a composition obtained by adding calcium sulfite or kaolin clay, acrylamide, and PDX to 100 parts by weight of polypropylene in the proportions shown in Table 3 below, and further blending a small amount of a lubricant. Table 3 shows the strength and surface gloss. Example 4 Density 0.969/CCl melt index 5.59/
Table 4 shows the tensile strength and surface gloss of injection molded products obtained by adding acrylamide and PDX to a mixture containing 100 parts by weight of polyethylene, 67 parts by weight of calcium carbonate, and a small amount of lubricant. .

Claims (1)

[Claims] 1. To a mixture of 100 parts by weight of a polyolefin resin and 40 to 400 parts by weight of an inorganic filler, 0.5 to 40 parts by weight of acrylamide is added to 0.005 to 2 parts by weight of an organic peroxide.
A polyolefin resin composition for molding, which contains the following parts by weight.