JPH0613625B2 - Low gloss blow molding resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a novel low-gloss blow molding resin composition, more specifically, good blow moldability such as drawdown resistance and deep drawability. In addition, it is possible to provide an economically advantageous blow-molded product that has low glossiness, has little gloss temperature dependency of mold temperature, has no gloss unevenness, and does not require matte coating. The present invention relates to a low-gloss blow molding resin composition suitable as a material for automobile interior parts such as a lid and a lid.

[Prior Art] Generally, polyolefin resins are excellent in processability, chemical resistance, weather resistance, electrical characteristics, etc. Among them, polypropylene and polyethylene have good processability, and their surface is Has a smooth, glossy and beautiful appearance, and is widely used in the fields of home appliances, office automation equipment, automobile parts, various injection molded products, blow molded products, vacuum, compressed air molded products, films and sheets. It is used.

On the other hand, in recent years, the needs of consumers have been diversified, and not only a beautiful appearance with excellent surface gloss is not satisfactory, but there is a demand for something that has a textured appearance with reduced surface gloss and gives a high-class feeling. It's coming. For this reason, attempts have been made to improve the surface matte tone of a molded product by using a composition in which the surface of the molded product is textured or a composition in which an inorganic filler typified by talc is added to polyolefin.

By the way, automobile interior parts such as arm wrists and lids are usually made by blow molding, and
It is required to have a matte appearance. However, conventionally, polyolefin resin materials for blow molding used in these automobile interior parts have high gloss, and the gloss temperature dependency of the mold resin is large, and uneven gloss is likely to occur. I have a problem.

Therefore, in order to solve such a problem, when trying to give a texture to the surface of the molded product, a mold having a texture mark on the surface is necessary, and the mold manufacturing cost is unavoidably expensive.
In addition, there is a problem that a sufficient matting effect cannot be obtained only by giving a texture to the surface of the molded product. When a polyolefin-based resin composition containing an inorganic filler is used, the matte appearance of the molded product is quite satisfactory, but blow moldability such as blow-up characteristics and scratch whitening resistance may decrease. There is such a problem. Therefore, until now, automobile interior parts such as armrests and lids using blow-molding polyolefin-based resin materials have been given a matte coating, which has inevitably resulted in high product costs.

[Problems to be Solved by the Invention] Under these circumstances, the present invention overcomes the drawbacks of the conventional polyolefin resin materials for blow molding, and has blow molding resistance such as drawdown resistance and deep drawability. In addition to good properties, it has low gloss, low gloss temperature dependence on mold temperature, no uneven gloss, and low gloss that can provide economically advantageous blow-molded products without the need for matte coating. The purpose of the present invention is to provide a resin composition for flexible blow molding.

[Means for Solving the Problems] As a result of intensive studies to develop a low-gloss blow molding resin composition having the above-mentioned preferable properties, the present inventors have a specific melt index, and A polypropylene resin and a high-density polyethylene having a melt index ratio of both in a specific relationship, and an inorganic powder having a specific average particle diameter, by a composition containing a specific ratio, respectively, that the purpose can be achieved. They have found the present invention and have completed the present invention based on this finding.

That is, the present invention provides (A) melt index 1 to 5
(C) Average particle size with respect to 100 parts by weight of a mixture of 50 to 90% by weight of a polypropylene resin of g / 10 minutes and (B) 50 to 10% by weight of high density polyethylene having a melt index of 0.05 g / 10 minutes or less. Inorganic powder of 10 μm or less 0
˜50 parts by weight and the ratio MI _PE / MI _PP of the melt index (MI _PE ) of the component (B) to the melt index (MI _PP ) of the component (A) is expressed by the formula −3.0 ≦ log. _The present invention provides a resin composition for blow molding with low gloss, which satisfies the relationship of ₁₀ (MI _PE / MI _PP ) ≦ −1.3.

Hereinafter, the present invention will be described in detail.

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

The polypropylene resin as the component (A) in the composition of the present invention must have a melt index of 1 to 5 g / 10 minutes, preferably 2 to 4 g / 10 minutes. If the melt index is less than 1 g / 10 minutes, sufficient low gloss may not be obtained, and 5 g / 10
If the amount exceeds the limit, the drawdown resistance is lowered, and blow molding tends to be difficult.

When two or more polypropylene resins are mixed and used, the polypropylene having the highest melt index and the polypropylene having the lowest melt index are respectively set to MI _PP (large) and M.
If I _PP (small), the MI _PP (large) / MI _PP (small) ratio is desirably 3 or less.

The high density polyethylene as the component (B) in the composition of the present invention has a normal density of 0.938 to 0.970 g / cm ^3.
Those in the range of are used. This high-density polyethylene may be used alone or in combination of two or more, and its melt index is 0.05 g / 1.
It should be 0 minutes or less, preferably 0.03 g / 10 minutes or less. This melt index is 0.05g
If it exceeds / 10 minutes, the drawdown resistance is lowered, molding becomes difficult, and the low gloss tends to be insufficient.

In the composition of the present invention, the ratio MI _PE / MI _PP of the melt index (MI _PE ) of the component (B) to the melt index (MI _PP ) of the component (A) is expressed by the formula −3.0 ≦ log ₁₀ (MI _PE / MI _PP ) ≤-1.3 ...
(I) Preferably −2.5 ≦ log ₁₀ (MI _PE / MI _PP ) ≦ −1.8 ...
It is necessary to satisfy the relationship of (II).

If the value of log ₁₀ (MI _PE / MI _PP ) is smaller than -3.0, blow-up characteristics may be deteriorated and moldability may be difficult, and if larger than -1.3, sufficiently low glossiness may be obtained. Is not obtained, and uneven gloss is likely to occur.

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

As the inorganic powder of the 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,
Metal elements such as gold, magnesium, cobalt and strontium and oxides of these metals, alloys such as stainless steel, solder and brass, powders of metal-based ceramics such as silicon carbide, silicon nitride, zirconia, aluminum nitride and titanium carbide. Among these, talc is particularly preferable.

The inorganic powder of component (C) may be used alone or in combination of two or more, but the average particle size is 1
It should be 0 μm or less, preferably 5 μm or less. If the average particle size exceeds 10 μm, the blow-up characteristics tend to deteriorate and 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 as desired. Examples of the surface treatment agent include saturated higher fatty acids such as stearic acid and palmitic acid or derivatives thereof, unsaturated higher fatty acids such as oleic acid or derivatives thereof, silane coupling agents, titanate coupling agents, silicone oils, and higher grades. Examples thereof include alcohols, and these may be used alone or in combination of two or more.

There is no particular limitation on the method of surface-treating the inorganic powder using these surface-treating agents, and for example, the surface-treating agent may be sprayed onto the inorganic powder in a Henschel mixer, and the mixture may be mixed and stirred for treatment. Alternatively, they may be treated simultaneously at the stage of producing the inorganic powder.

The inorganic powder of the component (C) in the composition of the present invention is 0 to 100 parts by weight of the mixture of the polypropylene resin of the component (A) and the high-density polyethylene of the component (B).
It is necessary to mix 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 characteristics are deteriorated, the blow moldability is deteriorated, the strength of the parting line is deteriorated, and the scratch whitening resistance tends to be deteriorated.

In the composition of the present invention, if desired, other thermoplastic resins, fibrous inorganic fillers, organic fillers, antioxidants, light stabilizers, heat stabilizers, lubricants may be used within the range not impairing the object of the present invention. A catalyst neutralizing agent (halogen scavenging material), an antistatic agent, a flame retardant, a coloring agent, a release agent, etc. can be added.

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

As the fibrous inorganic filler, for example, glass fiber, carbon fiber, boron fiber or calcium carbonate fiber, gypsum fiber,
Metal fibers such as magnesium sulfate fibers, magnesium hydroxide fibers, aluminum hydroxide fibers, aluminum fibers, stainless fibers, copper fibers, brass fibers, nickel fibers, silicon carbide fibers, single crystal potassium titanate and other simple metal fibers and alloy fibers. , And metal whiskers corresponding to these, and the like. Examples of the organic filler include shell fiber such as fir shell, wood powder, cotton, jute, paper strip, cellophane strip, aromatic polyamide fiber, cellulose fiber, nylon fiber, polyester fiber and the like. Preferable examples of the antioxidants include phenol-based and phosphorus-based antioxidants, and the combined use of these is particularly preferable. Examples of the phenolic antioxidant include 2,6-di-t-butyl-4-methylphenol, tris (3,5-di-t-butyl-4-hydroxybenzyl) isocyanurate (manufactured by Ciba Geigy,
Irganox 3114), 2,2'-methylenebis (4-ethyl-6-t-butylphenol), n-octadecyl-3- (3 ', 5'-di-t-butyl-4'-.
Hydroxyphenyl) propionate (Irganox 1076, manufactured by Ciba-Geigy), 4,4'-thiobis (3-methyl-6-t-butylphenol), tetrakis [methylene-3- (3 ', 5'-di-t-butyl-)-
4'-Hydroxyphenyl) propionate] methane (Ciba Geigy, Irganox 1010), 4,
4'-butylidene bis (3-methyl-6-t-butylphenol), 2,2'-methylene bis (4-methyl-6)
-T-butylphenol), N, N'-hexamethylenebis (3,5-di-t-butyl-4-hydroxyhydrocinnamide) (Ciba-Geigy, Irganox10).
98), triethylene glycol-bis [3- (3'-
t-butyl-5'-methyl-4-hydroxyphenyl)
Propionate], bis (3,5-di-t-butyl-4
A mixture of calcium (hydroxybenzylphosphonate) and PE wax (weight ratio 1: 1) (Irganox 1425WL manufactured by Ciba-Geigy).
Examples of phosphorus-based antioxidants include distearyl pentaerythritol diphosphite and tetrakis (2,4-
Di-t-butylphenyl) -4,4'-biphenylenediphosphite (manufactured by Sando Corporation, Sandostab P-
EPQ), trisnonylphenyl phosphite, tris (2,4-di-t-butylphenyl) phosphite and the like.

As the light stabilizer, for example, salicylate-based, benzophenone-based, triazole-based, oxalic acid anilide-based, hind-damine-based, etc. are used, and as the lubricant, for example, stearic acid amide, palmitic acid amide, oleic acid amide, erucic acid. Examples of catalyst neutralizing agents such as amides 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),
The component (B), the component (C), and various additives used as necessary are prepared by melt-kneading using, for example, an FCM, a twin-screw continuous extruder, a kneader, a Henschel mixer, a Banbury mixer, or a roll. be able to. At this time, it is desirable to adopt a condition that the melt index of the kneaded product does not become too high, that is, a condition that suppresses deterioration due to shearing heat during kneading.

The low-gloss blow-molding resin composition of the present invention thus obtained is subjected to a conventional method for blow-molding polypropylene or high-density polyethylene, for example, at a molding temperature of 190 to 260 ° C. and a mold temperature. 20-80 ° C
A desired low-gloss molded product can be obtained by blow molding under the conditions of.

EXAMPLES Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Each property was determined as follows.

(1) Melt index (MI) The melt index was measured according to JIS K-7210. The polypropylene resin has a melt index of 230 ° C., 21
It was measured under the condition of a load of 60 g, and the melt index of the high-density polyethylene was measured under the condition of 190 ° C. and a load of 2160 g.

(2) Drawdown resistance A die with a die diameter of 37 mm and a core diameter of 33 mm was used to make a parison with a parison weight of 340 g and a parison length of 40 cm, and the time required for the parison to reach a total length of 60 cm was measured. The drawdown property was evaluated.

(3) Glossiness A 120 × 120 × 200 mm single-sided bottle having the shape shown in FIG. 1 was molded, the flat surface portion 1 and the embossed surface portion 2 on the side surface were cut out, and the glossiness of each was measured according to JIS K-7105 (angle:
It was evaluated according to 60 °).

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

⊚: No gloss unevenness was observed ○: Some gloss unevenness was observed ×: Gloss unevenness was clearly observed (5) Blow-up characteristics The wall thickness of the corner and flat portions of the bottle in (3) above was observed. The evaluation was made according to the following criteria.

◯: The wall thickness of the corner portion is not so different from the wall thickness of the flat surface portion Δ: The wall thickness of the corner portion is considerably smaller than the wall thickness of the flat surface portion ×: The corner portion is broken and molding is impossible. The following resins were used as the resin.

(1) Block PP (a): MI = 0.5, ethylene content = 1.8 mol% (2) Block PP (b): MI = 3.0, ethylene content = 10 mol% (3) Block PP ( c): MI = 6.0, ethylene content = 6 mol% Examples 1 to 8, Comparative Examples 1 to 7 Twin screw extruder [Kobe Steel Works, Ltd.] 2 FCM] and melt-kneaded at 220 to 250 ° C. to prepare a resin composition, and its performance was evaluated. The results are shown in Table 1.

[Effects of the Invention] According to the present invention, it has low glossiness without impairing blow moldability such as drawdown resistance and deep drawability, and has less unevenness in gloss due to a small mold temperature dependency. Therefore, a polyolefin resin composition for blow molding having low gloss which can provide an economically advantageous blow molded product without the need for matt coating can be easily obtained.

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

[Brief description of drawings]

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

Claims (1)

[Claims] 1. A melt index of 1 to 5 g / 10.
100 parts by weight of a mixture of 50 to 90% by weight of polypropylene resin and (B) 50 to 10% by weight of high density polyethylene having a melt index of 0.05 g / 10 minutes or less, (C) having an average particle diameter of 10 μm or less. The inorganic powder is blended in an amount of 0 to 50 parts by weight, and the ratio MI _PE / MI _PP of the melt index (MI _PE ) of the component (B) to the melt index (MI _PP ) of the component (A) is expressed by the formula-3. A resin composition for blow molding having low gloss, which satisfies the relationship of 0 ≦ log ₁₀ (MI _PE / MI _PP ) ≦ −1.3.