JPH03197541A - Low-gloss resin composition for blow molding - Google Patents

Abstract

PURPOSE:To prepare the title compsn. having an excellent blow moldability and giving a blow molded article with a low and uniform gloss by mixing a polypropylene resin with a high density polyethylene, each having a specified melt index. CONSTITUTION:50-90wt.% polypropylene resin having a melt index of 1-5g/10min is mixed with 50-10wt.% high density polyethylene having a melt index of 0.05g/10min or lower, the ratio of the melt index of the polyethylene (MIPE) to that of the polypropylene (MIPP) satisfying a relation of the formula. 100 pts.wt. resulting mixture is compounded with 0-50 pts.wt. inorg. powder having a particle diameter of 10mu or lower to give the title compsn., which, when blow molded at a molding temp. of 190-260 deg.C and a mold temp. of 20-80 deg.C, gives a desired low gloss molded article.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a novel low-gloss blow molding resin composition, more specifically, it has good blow moldability such as drawdown resistance and deep drawability. At the same time, it is possible to provide economically advantageous blow-molded products that have low gloss, have little dependence of gloss on mold temperature, have no uneven gloss, and do not require matte coating, and can be used, for example, in armrests, etc. The present invention relates to a low-gloss blow molding resin composition suitable as a material for automobile interior parts such as lids.

[Prior art] Generally, polyolefin resins have excellent processability, chemical resistance, weather resistance, electrical properties, etc. Among them, polypropylene and polyethylene have good processability and have excellent properties when made into molded products. Because of its smooth, glossy and beautiful appearance, it is used in fields such as home appliances, OA equipment, automobile parts, various injection molded products, blow molded products, vacuum and pressure molded products, films, and sheets. Widely used.

On the other hand, in recent years, consumer needs have diversified, and they are no longer satisfied with simply a beautiful appearance with excellent surface gloss, but are now seeking products that have a textured appearance with less surface gloss and give a sense of luxury. It has become. For this reason, attempts have been made to improve the matte appearance of the surface of the molded product by adding texture to the surface of the molded product or by using a composition in which an inorganic filler such as talc is added to polyolefin.

By the way, automobile interior parts such as armrests and lids are usually created by blow molding, and
It is required to have a matte appearance. However, polyolefin resin materials for blow molding conventionally used for these automobile interior parts have high gloss, and the gloss has a large dependence on mold temperature, which tends to cause uneven gloss, resulting in poor appearance. I have a problem.

Therefore, in order to solve this problem, if we try to add texture to the surface of the molded product, a mold with grain marks on the surface is required, which inevitably increases the mold production cost.
Moreover, problems arise such as simply adding texture to the surface of the molded product does not provide a sufficient matte effect. In addition, when using a polyolefin resin composition containing an inorganic filler, the matte appearance of the molded product is quite satisfactory, but there is a risk that blow moldability such as blow-up properties and scratch and whitening resistance may deteriorate. A problem arises. Therefore, until now, automobile interior parts such as armrests and lids made of polyolefin resin materials for blow molding have been painted with a matte finish, which inevitably resulted in high product costs.

[Problem to be Solved by the Invention 1] Under these circumstances, the present invention overcomes the drawbacks of conventional polyolefin resin materials for blow molding, and improves blow molding properties such as drawdown resistance and deep drawability. Low gloss that can provide economically advantageous blow-molded products that have good properties and low gloss, and have low dependence of gloss on mold temperature, have no uneven gloss, and do not require matte coating. The purpose of this invention is to provide a resin composition for blow molding.

[Means for Solving the Problems] As a result of intensive research to develop a low-gloss blow molding resin composition having the above-mentioned preferable properties, the present inventors have found that the composition has a specific melt index and It is believed that this objective can be achieved by a composition containing a polypropylene resin and high-density polyethylene, each of which has a specific melt index ratio, and an inorganic powder having a specific average particle size, in specific proportions. Based on this finding, we have completed the present invention.

That is, the present invention provides (A) a melt index of 1 to 5;
9/10 min polypropylene resin 50-90% by weight
and (B) 50 to 10% by weight of high-density polyethylene with a melt index of 0.059/10 minutes or less 100
(C) 0 to 50 parts by weight of an inorganic powder with an average particle size of 10 μm or less per part by weight, and the melt index (MIP) of the component (B) relative to the melt index (M r pp) of the component (A) ) ratio MIpa/MI□
The object of the present invention is to provide a low-gloss blow molding resin composition, which is characterized by satisfying the following relationship:

The present invention will be explained in detail below.

In the composition of the present invention, the polypropylene resin used as component (A) is not particularly limited, and may be a homopolymer of propylene or a copolymer of propylene and other α-olefin. or a mixture thereof. Other olefins used in this copolymer include those having 2 to 8 carbon atoms, such as ethylene, 1-butene, 1-pentene, and hexene-1.
Preferred examples include 1, heptene-1, and octene-1. As the copolymer, a block copolymer or a random copolymer containing the above-mentioned other α-olefin units, usually 40% by weight or less, preferably 30% by weight or less, can be used, but in particular, 20% by weight or less % or less of ethylene units are preferred.

It is necessary that the polypropylene resin as the component (A) in the composition of the present invention has a melt index in the range of 1 to 59/10 minutes, preferably 2 to 49/10 minutes. If this melt index is less than 1 g/10 minutes, sufficient low gloss may not be obtained;
If it exceeds 10 minutes, drawdown resistance tends to decrease and blow molding becomes difficult.

In addition, when using a mixture of two or more types of polypropylene resins, if the Nor 1-index of the polypropylene with the largest melt index and the polypropylene with the smallest melt index are Mlpp (large) and MIpp (small), then M I pp (large) /
It is desirable that the M I PF (small) ratio is 3 or less.

The high-density polyethylene as component (B) in the composition of the present invention usually has a density of 0.938 to 0.970 g 7
A material in the range of cm3 is used.

This high-density polyethylene may be used alone or in combination of two or more, but its melt index is 0.059710 minutes or less, preferably 0.039.
/10 minutes or less is required. When the melt index exceeds 0.05 g/10 minutes, drawdown resistance decreases, molding becomes difficult, and low gloss tends to be insufficient.

In the composition of the present invention, the ratio of the melt index (M I PK) of the component (B) to the melt index (Mlpp) of the component (A) M I p, / M
It is necessary that Ipp satisfy the relationship of the formula % (1) ().

The QOg +o (M I PP: / M I pp)
If the value is less than -3.0, the blow-up properties may deteriorate and moldability may become difficult; if it is larger than -1.3, sufficient low gloss cannot be obtained and uneven gloss may occur. There is a tendency for it to become easier.

In the composition of the present invention, the polypropylene resin as the component (A) and the high-density polyethylene as the component (B) are contained in an amount of 50 to 90% by weight and 50 to 10% by weight, preferably 60 to 85% by weight and 40 to 40% by weight, respectively. It is necessary to mix in a proportion of 15% by weight. If the amount of high-density polyethylene used as component (B) is less than 10% by weight, drawdown resistance will decrease, molding will be difficult, and low gloss may not be obtained; if it exceeds 50% by weight, There is a tendency for high temperature rigidity to decrease.

As the inorganic powder of component (C) in the composition of the present invention,
For example, silica, diatomaceous earth, barium ferrite, beryllium oxide, aluminum hydroxide, magnesium hydroxide, basic magnesium carbonate, calcium carbonate, magnesium carbonate, dolomite, dawsonite, calcium sulfate, barium sulfate, ammonium sulfate, calcium sulfite, talc, clay, Calcium silicate, montmorillonite, bentonite, carbon black, graphite,
Molybdenum sulfide, zinc borate, barium metaborate, calcium borate, sodium borate, etc., or zinc, copper, iron, lead, aluminum, nickel, chromium, titanium, manganese, tin, platinum, tungsten, gold, magnesium, cobalt. , metal elements such as strontium, oxides of these metals, stainless steel, solder, alloys such as brass, and powders of metal ceramics such as silicon carbide, silicon nitride, zirconia, aluminum nitride, and titanium carbide. Among these, talc is particularly suitable.

This inorganic powder of component (C) may be used alone or in combination of two or more, but the average particle size is 1
0 μm or less, preferably 5 μm or less. If the average particle size exceeds 10 μm, the blow-up properties tend to deteriorate and the blow moldability tends to deteriorate.

In the present invention, the inorganic powder can be used after being surface-treated with a known surface-treating agent, if desired. Examples of the surface treatment agent include saturated higher fatty acids or derivatives thereof such as stearic acid and palmitic acid, unsaturated higher fatty acids such as oleic acid or derivatives thereof, silane coupling agents, titanate coupling agents, silicone oil, Examples include higher alcohols, and these may be used alone or in combination of two or more.

There are no particular limitations on the method of surface treating the inorganic powder using these surface treating agents; for example, the surface treating agent may be sprayed onto the inorganic powder in a Henschel mixer, and the treatment may be carried out by mixing and stirring. , may be treated simultaneously at the inorganic powder manufacturing stage.

The inorganic powder as the component (C) in the composition of the present invention is 0 to 100 parts by weight based on 100 parts by weight of the mixture of the polypropylene resin as the component (A) and the high-density polyethylene as the component (B).
It is necessary to mix it in a proportion of 50 parts by weight, preferably 5 to 40 parts by weight. If the blending amount exceeds 50 parts by weight, the blow-up properties deteriorate, the blow moldability decreases, the strength of the parting line decreases, and the scratch and whitening resistance tends to deteriorate.

The composition of the present invention may optionally contain other thermoplastic resins, fibrous inorganic fillers, organic fillers, antioxidants, light stabilizers, heat stabilizers, and lubricants to the extent that the purpose of the present invention is not impaired. , a catalyst neutralizer (halogen scavenger), an antistatic agent, a flame retardant, a coloring agent, a mold release agent, etc. can be added.

Examples of the other thermoplastic resins include medium and low density polyethylene, modified polypropylene, polyolefin resins such as polybutene-1, polyvinyl chloride resins, polyamide resins, polyimide resins, polyester resins, polyacetal resins, Examples include polycarbonate resins, polyaromatic ether or thioether resins, polyaromatic ester resins, polysulfone resins, styrene resins, and acrylate resins.

Examples of fibrous inorganic fillers include glass fiber, carbon fiber, poron fiber, aluminum fiber, stainless steel fiber,
Copper 1 & fiber, brass fiber, nickel fiber, silicon carbide fiber,
Examples include metal fibers such as single crystal potassium titanate 11 2 , other single metal fibers, alloy fibers, and metal whiskers corresponding to these. Examples of organic fillers include husk fibers such as rice husk, wood flour, cotton, jute, paper strips, cellophane strips,
Examples include aromatic polyamide fiber, cellulose 1111m, nylon fiber, polyester fiber, and polypropylene fiber. Preferable examples of antioxidants include phenol-based and phosphorus-based antioxidants, and combinations of these are particularly preferred. Examples of phenolic antioxidants include 2,6-di-t-butyl-4-methylphenol, tris(3,5-di[-phthyl-4-hydroxybenzyl)incyanurate (manufactured by Ciba Geigy, Irganox 3114), 2I2'- Methylenebis(4-ethyl-6-butylphenol), n-octadecyl-3(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate (manufactured by Ciba Geigy, Irganox1076), 4,4' -thiobis(3
-methyl-6-t-butylphenol), tetrakis[
Methylene-3-(3',5'-di[-butyl-4'-
Hydroxyphenyl) propionate comethane (manufactured by Ciba Geigy, Irganoxlolo), 4.4″-butylidenebis(3-methyl-6-t-butylphenol), 2,2′-methylenebis(4-methyl-6-t-1)
tylphenol), N,N'-hexamethylene bis(
3,5-di-t-butyl-4-hydroxyhydrocinnamide) (manufactured by Ciba Geigy, Irganox 109g)
, triethylene glycol-bis[3-(3″-t-butyl-5′-methyl-4-hydroxyphenyl)propionate], bis(3,5-di-t-butyl-4-hydroxybenzylphosphonate)calcium and PE wax (weight ratio 1:1) (manufactured by Ciba Geigy, I
rganox1425WL). Examples of phosphorus antioxidants include distearylpentaerythritol diphosphite, tetrakis(2,4-di-t-
butylphenyl)-4,4'-biphenylene diphosphite (Say1dostabP-EPQ, manufactured by Sandoz)
, trisnonylphenyl phosphite, tris(2,4
-di-t-butylphenyl) phosphite and the like.

Examples of light stabilizers used include salicylates, benzophenones, triazoles, oxalic acid anilides, and hinderamines. Examples of lubricants include stearamide, palmitamide, oleic acid amide, and erucic acid. Examples of catalyst neutralizing agents include higher fatty acid metal salts such as calcium stearate, zinc stearate, and magnesium stearate, and hydrotalcite.

The resin composition of the present invention comprises a required amount of the component (A), (B
), component (C), and various additive components used as necessary, for example, using an FCM, a twin-screw continuous extruder, a kneader,
It can be prepared by melt-kneading using a Henschel mixer, a Pan Bali mixer, a roll, or the like.

At this time, it is desirable to adopt conditions such that the melt index of the mixed material does not become too high, that is, conditions that suppress deterioration due to shear heat generation during kneading.

The thus obtained low-gloss blow molding resin composition of the present invention is applied to a mold using a method conventionally used in blow molding polypropylene or high-density polyethylene at a molding temperature of 190 to 260° C. Temperature 20-80
By blow molding at .degree. C., desired low gloss molded products can be obtained.

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

In addition, each characteristic was calculated|required as follows.

(1) Melt index (MI') JISK-7
It was carried out in accordance with 210. Furthermore, the melt index of polypropylene resin is 230°C! The melt index of high density polyethylene was measured at 190°C and a load of 21609g.

(2) Drawdown resistance Using a die with a die diameter of 37 mm and a core diameter of 33 mm, a parison with a parison weight of 340 g and a parison length of 40 cm was created, and the time required for the total length of this parison to reach 60 cm was measured. Drawdown performance was evaluated.

(3) Glossiness A 120 x 120 x 200 mm IQ square bottle with the shape shown in Figure 1 is molded, the flat side part 1 and the textured part 2 are cut out, and the gloss level of each is determined according to JIS standards.
Evaluation was made according to K-7105 (angle: 60').

(4) Gloss unevenness The cut-out portion of the textured surface in (3) above was visually observed and evaluated according to the following criteria.

@: Gloss unevenness is not observed ○: Gloss unevenness is slightly compared ×: Gloss unevenness is clearly observed (5) Blow-up characteristics Observe the wall thickness of part of the corner and flat part of the square bottle in (3) above. The results were evaluated according to the following criteria.

○: The wall thickness of a part of the corner is not much different from the wall thickness of the flat part. △: The wall thickness of a part of the corner is considerably thinner than the wall thickness of the flat part. ×: A part of the corner is torn and cannot be formed. The following polypropylene resin was used.

(1) Bronk PP (a): MI = 0.50, ethylene content - 1.8 mol% (2) Block PP (b): MI = 0.15, ethylene content - 10 mol% (3) Block PP ( c): MI=6.0, ethylene content -6 mol% Examples 1 to 8,
Comparative Examples 1 to 7 Each component of the type and amount shown in Table 1 was supplied to a twin screw extruder [2FCM manufactured by Kobe Steel, Ltd.] and melted and kneaded at 220 to 250°C to prepare a resin composition. , and evaluated its performance. The results are shown in Table 1.

(The following is a blank space) 9 [Effects of the Invention] According to the present invention, it has low gloss without impairing blow moldability such as drawdown resistance and deep drawability, and the dependence of gloss on mold temperature is small. Since there is no unevenness in gloss, it is possible to easily obtain a low-gloss polyolefin resin composition for blow molding that can provide economically advantageous blow molded products that do not require matte coating.

Since this low-gloss blow molding resin composition has the above-mentioned excellent characteristics, it is suitably used, for example, as a material for automobile interior parts such as armrests and lids.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a square bottle molded to evaluate the performance of a resin composition, in which reference numeral 1 indicates a flat surface and 2 indicates a textured surface.

Claims (1)

[Claims] 1 (A) 50 to 90% by weight of polypropylene resin with a melt index of 1 to 5 g/10 min and (B) high density polyethylene with a melt index of 0.05 g/10 min or less 5
(C) for 100 parts by weight of the mixture with 0 to 10% by weight.
It contains 0 to 50 parts by weight of inorganic powder with an average particle size of 10 μm or less, and has a melt index (MI) of component (A).
The melt index (
The ratio MI_P_E/MI_P_P of MI_P_E) is determined by the formula -3.0≦log_1_0(MI_P_E/MI_P_
A low-gloss blow molding resin composition, which satisfies the relationship P)≦−1.3.