JPS58145745A - Production of polyolefin resin molding - Google Patents

Abstract

PURPOSE:To obtain a polyolefin resin molding having an improved surface, by mixing a polyolefin resin with a compsn. consisting of a polyolefin and an org. or inorg. filler without kneading, and injection-molding the mixture. CONSTITUTION:5-50pts.wt. polyolefin resin is mixed with 100pts.wt. compsn. consisting of a polyolefin resin and an org. and/or inorg. filler without kneading. The mixture is injection-molded. Examples of the polyolefin resins are those having an MW of pref. 50,000-300,000. Low-density to high-density ethylene homopolymer, propylene homopolymer, copolymers of ethylene with propylene and copolymers of ethylene or propylene with other alpha-olefin are preferred. When the amount of the polyolefin resin is less than 5pts.wt. no improved effect can be obtd., while when it exceeds 50pts.wt., the ratio of the filler is greatly reduced, and physical characteristics is changed, and hence, the expected purpose can not be achieved.

Description

DETAILED DESCRIPTION OF THE INVENTION ■Object of the Invention The present invention relates to a method for producing a polyolefin resin molded article. More specifically, the production of a polyolefin resin molded product is characterized in that a composition comprising a polyolefin resin and an organic filler and/or an inorganic filler and a polyolefin resin are mixed and molded without kneading. The present invention relates to a method and aims to provide a polyolefin resin molded product with an improved surface.

III BACKGROUND OF THE INVENTION Compositions obtained by mixing polyolefin resins with organic fillers and/or inorganic fillers have been industrially manufactured and widely used in many fields.

These compositions are intended to not only reduce the cost of the composition but also improve the physical properties of the olefin resin by mixing the filler with the polyolefin resin to increase the amount of the composition. However, these fillers are not only essentially incompatible with polyolefin resins, but also their fluidity decreases in proportion to the amount of fillers added. When such a composition is molded, the base resin (
Flow irregularities occur between the olefin resin (olefin resin) and the added filler, resulting in flow marks on the surface of the molded product. As a result, not only the appearance of the molded product deteriorates, but also the physical properties deteriorate, making it impossible to obtain a good molded product.

In order to improve or prevent these drawbacks, for example, lubricants such as fatty acids, metal soaps (for example, metal salts of carboxylic acids), and waxes may be added, or to improve the wettability and adhesion between the olefin resin and the filler. Widely used methods include using coupling agents such as silicon-containing organic compounds and titanium-containing organic compounds, or introducing reactive groups into the base resin itself. However, although these methods can improve the effect to some extent, the improvement effect is not only unsatisfactory, but also technically complex, and it is difficult to improve economic efficiency, safety and health, and productivity. This is also an undesirable method in industrial production.

Structure of the Invention Based on the above, the present inventors have conducted various searches to obtain a polyolefin resin molded product with an improved surface. ■ Polyolefin resin, organic filler and/or ≠1
By mixing 100 parts by weight of a composition consisting of a mechanical filler and 5 to 50 parts by weight of a polyolefin resin without kneading and injection molding, a molded product with no flow marks and a beautiful surface can be obtained. The present invention was achieved based on the discovery that the following can be obtained.

■ Effects of the Invention The polyolefin resin molded article of the present invention and its production exhibit the following effects (characteristics).

(1) In carrying out the present invention, the composition of the polyolefin resin and the filler and the production of the molded product require only the usual mixing, as described later, and are easy to handle.

(2) The deterioration of the physical properties of the composition can be minimized, and the surface of the molded product can be beautifully improved.

(3) When painting the surface of a molded article, it can be applied beautifully without causing unevenness in the coating due to surface defects.

The surfaces of molded products and painted products obtained by the present invention are
As mentioned above, it can be used in a wide variety of ways to make it look beautiful. Typical examples include consumer home appliances (e.g. televisions, videos), electric/electronic equipment (e.g. computers, communication equipment), and office equipment (e.g. , facsimiles, word processors), and automobile parts.

■ Detailed Description of the Invention 8 Polyolefin Resin The polyolefin resin used in producing the compositions and molded articles of the present invention includes an ethylene homopolymer, a propylene homopolymer, and a copolymer of ethylene and propylene. Copolymers of ethylene and/or propylene with other α-olefins having at most 7 carbon atoms (
The copolymerization ratio of α-olefins is at most 20% by weight) and copolymers with vinyl compounds such as ethylene vinyl acetate, acrylic esters and methacrylic esters (the copolymerization ratio of vinyl compounds is at most 50 molar, preferably (at most 40 moles). The molecular weight of these polyolefins is generally 2 to 10
00,000, preferably 20,000 to 50,000, especially 5 to 30,000
00,000 olefin resin is suitable. Also, low density (
0,900g/cr/l) to high density (0,98
Ethylene homopolymers, propylene homopolymers, copolymers of ethylene and propylene, and copolymers of ethylene or propylene with other α-olefins are preferred.

(2) Inorganic fillers and organic fillers The inorganic fillers and organic fillers used to produce the compositions of the present invention are those commonly used in synthetic resins and rubbers. Inorganic fillers include metals whose chemical composition is aluminum, copper, iron, silver, and alloys containing these as main components, as well as aluminum oxide, its hydrates, aluminum silicate, antimony oxide, baryram titanate, Colloidal silica, calcium carbonate, barium sulfate, calcium sulfate, iron oxide, asbestos, carbon black, graphite, shirasu balloon, fly ash, glass fiber, lithium silicate/aluminum clay, mica, silica, silica, diatomaceous earth, silicon Carbide, talc, asbestos, zirconium oxide,
Examples include compounds such as zirgonium silicate, molybdenum disulfide, titanium oxide and glass bulbs, double salts and mixtures thereof. In addition, organic fillers include spherical phenol, linter, linen, silk, viscose, polyacetate, polyamide fiber, polyester fiber, vinylon fiber, wood flour, waste paper, rice husk, jute,
Examples include cork flour and fiber flock. The shapes of these fillers are powder (e.g. calcium carbonate), plate (e.g. mica), needle (e.g. asbestos), spherical (e.g. glass spheres), fibrous (various fibers) and fibrous (e.g., glass fiber mats). Among the inorganic fillers, powder, plate-like, and spherical materials preferably have a diameter of 1 square meter or less. Further, as for the organic filler, one having a density of 12 meshes is preferable, and one having a density of 45 meshes is particularly preferable. Furthermore, for organic or inorganic fibrous materials, the diameter is 1 to 5.
Preferably, the length is 0.1 to 6 microns.

0 Production of Composition The composition of the present invention can be produced by uniformly mixing the polyolefin resin and an organic filler and/or an inorganic filler.

(1) Composition ratio The composition ratio of the polyolefin resin in the composition is generally 20 to 95% by weight, and 30 to 90% by weight.
is preferred, particularly 40 to 80% by weight. If the composition ratio of the polyolefin resin is 200% by weight or less, it becomes difficult to produce a uniform composition with an organic filler and/or an inorganic filler. On the other hand, if it exceeds 95% by weight, it is not preferable because the effect of reducing costs and improving physical properties is small.

(2) Production method The composition of the present invention can be produced by any method commonly used for producing compositions of polyolefin resins and fillers. Examples of this method include tri-blending using a mixer such as a Henschel mixer, and melt-kneading using a mixer such as a Banbury mixer, kneader, roll mill, and screw extruder. At this time, a more uniform composition can be obtained by triblending in advance and further melt-kneading the resulting mixture.

In this case, the mixture is generally melt-kneaded and then molded into a pellet-like product, which is then used to produce the molded product described later.

This composition is produced by homogeneously mixing a polyolefin resin and an organic filler and/or an inorganic filler, and also contains stabilizers against oxygen and heat. Additionally, additives such as light stabilizers, metal deterioration inhibitors, electrical property improvers, adhesion improvers, flame retardants, foaming agents, lubricants, plasticizers and colorants may be incorporated.

0 Production of Molded Article A molded article can be manufactured by mixing the composition obtained as described above and a polyolefin resin without kneading and injection molding the mixture. Furthermore, instead of the polyolefin resin, a polyolefin resin partially or entirely modified with an unsaturated compound may be used.

(1) Molding ratio In producing the molded product of the present invention, the ratio of polyolefin resin to 100 parts by weight of the composition is 5 to 50 parts by weight, preferably 5 to 50 parts by weight, especially 7 to 50 parts by weight.
35 parts by weight is preferred.

If the ratio of the polyolefin resin to 100 parts by weight of the composition is less than 5% by weight, no improvement effect will be observed. On the other hand, when the amount is 50 parts by weight or more, the improvement effect is sufficiently recognized, but it is difficult to achieve the initial purpose of significantly reducing the proportion of filler in the molded product and further changing its physical properties in the same way. I can't.

In addition, fillers (organic fillers and inorganic fillers) occupying in the molded product obtained from the composition and polyolefin resin.
The amount is preferably 3 to 35 volumes, particularly preferably 5 to 30 volumes.

(2) Modified polyolefin resin The modified polyolefin resin used in the present invention is obtained by modifying the polyolefin resin described above using an unsaturated organic compound (particularly preferably an unsaturated carboxylic acid or its anhydride). can be obtained by

Representative examples of the unsaturated carboxylic acids or anhydrides thereof include monobasic carboxylic acids having at most 10 carbon atoms and at least one double bond (e.g., acrylic acid, methacrylic acid); Dibasic carboxylic acids (e.g. maleic acid) and anhydrides of the dibasic carboxylic acids (e.g. maleic anhydride, himic anhydride) having at most 15 carbon atoms and at least one double bond; can give. Among these unsaturated carboxylic acids or their anhydrides, maleic acid and maleic anhydride are particularly preferred.

Modified polyolefin resins are generally obtained by treating polyolefin resins with unsaturated norboxylic acids and/or their anhydrides in the presence of organic peroxides.

Various known methods (for example, solution method, suspension method, melt method) can be used to produce the modified polyolefin resin of the present invention.
Any manufacturing method can be adopted.

Among these production methods, when polyolefin resin is modified with unsaturated carboxylic acid or its anhydride by a solution method, the polyolefin resin and unsaturated carboxylic acid and/or its anhydride are placed in a nonpolar organic solvent. A modified polyolefin resin can be obtained by further adding a radical initiator and heating at a high temperature.

In this case, examples of nonpolar organic solvents used include hexane, heptane, benzene, toluene, xylene, chlorobenzene, and tetrachloroethane. Also,
As a radical initiator, 2,5-dimethyl-2,5-
Examples include organic peroxides such as tertiary-butylperoxy)hexane, 2,5-dimethyl-2,5-di(tertiary-butylperoxy)hexane-3, and pensoyl peroxide.

Furthermore, the treatment temperature is a temperature at which the polyolefin resin used is dissolved, and is generally 110 to 160°C, particularly preferably 130 to 150°C.

In addition, when modifying polyolefin resins with unsaturated carboxylic acids or their anhydrides by the suspension method, polar solvents (
Generally, it is obtained by adding a polyolefin resin and an unsaturated carboxylic acid and/or its anhydride to water), adding the above-mentioned radical initiator, and treating under high pressure at a temperature of 100°C or higher. .

Furthermore, when modifying a polyolefin resin with an unsaturated carboxylic acid or its anhydride by a melting method, a melt mixer (for example, an extruder) used in the field of general synthetic resins is used to modify the polyolefin resin, It can be obtained by processing an unsaturated carboxylic acid and/or its anhydride and the above-mentioned radical generating agent while melt-kneading. The crosstalk temperature at this time varies depending on the type of polyolefin resin and radical generator used, but is in the temperature range from above the melting point of the polyolefin resin used to below 300°C. In the case of polyethylene, it is generally 120-270°C, and in the case of polypropylene, it is generally 160-270°C.

(3) Manufacturing method A good molded product cannot be obtained if the composition and the polyolefin resin are melt-kneaded.

That is, it is necessary to triblend them. Even if it is melted and kneaded, it will not be possible to obtain a molded product that achieves the object of the present invention. A molded article can be produced from the mixture thus obtained by a commonly used injection molding method. At this time, the polyolefin resin mixed with the composition may contain additives other than the filler contained in the composition. Further, it is usually necessary to include a stabilizer. In this case, the polyolefin resin used to produce the molded product may be of a different type from the polyolefin resin used to obtain the composition, but if the same type is used, it will be of a good quality. [For example, if polyethylene (including copolymers) is used to manufacture the composition, it is desirable to use polyethylene or a modified product thereof to manufacture the molded product.]
.

Whether it is melt-kneaded when producing the composition or injection molding when producing the molded article, the process must be carried out at a temperature equal to or higher than the softening point of the polyolefin resin or its modified product. No, but 25
When carried out at a temperature of 0° C. or higher, a part of the polyolefin resin or its modified product may undergo thermal deterioration.

Therefore, it is natural that the process must be carried out at a temperature below this temperature.

EXAMPLES EXAMPLES AND COMPARATIVE EXAMPLES The present invention will be explained in more detail with reference to Examples below.

In addition, in the examples and comparative examples, the melt flow
Index (hereinafter referred to as "MFI") uJIs K
-6758 at a temperature of 230°C and a load of 2
．． The measurement was carried out under the condition of 16 kg. In addition, the melt index (hereinafter referred to as [M, Il) is JIS K-676
According to 0, the temperature is 190℃ and the load is 2.16K.
The measurement was carried out under the conditions of g.

Example 1 45 parts by weight of propylene homopolymer with a density of 0.900.9/cr/l, wood flour (particle size 100 mesh pass) 15
Parts by weight, barium sulfate (average particle size 5 microns) 25
parts by weight and 15 parts by weight of Merck (average particle size 30 microns and 2 parts by weight of calcium stearate (lubricant)) were mixed for 3 minutes (tri-blend) using a Hensiel mixer. The resulting mixture was extruded with a twin-screw vent. Machine (
Melt kneading using vent suction (600mm)
wn-I-1g).

Pelletization was performed while maintaining the resin temperature at 200°C.

To 100 parts by weight of this pellet, 20 parts by weight of propylene homopolymer (MPI 10.9/10 minutes) was added,
Mix for 10 minutes using a tumbler (dry nalendo)
did. The resulting mixture was molded using a 10 oz injection molding machine (resin temperature 200°C) into a radio box (vertical 100°C).
mm, width 200 ron and depth 60 ron, average thickness
3) was molded. As a result, a beautiful molded product was obtained with no flow marks. Furthermore, when this molded product was coated with silver paint (Micron" 3000), the painted surface was uniform and beautiful.

Comparative Example 1 The pellets obtained in Example 1 were injection molded in the same manner as in Example 1. As a result, many flow marks were generated due to uneven flow of filler such as wood powder, especially on the depth surface. Furthermore, when this molded product was painted with silver in the same manner as in Example 1, flow marks also appeared on the painted surface, and a beautiful product could not be obtained.

Comparative Example 2 Density is 0.900,! 91crd propylene-ethylene block copolymer (MFI 20.!i'/10
minute, ethylene content 15.0% by weight, hereinafter rPP (2
)j] and 40 parts by weight of calcium carbonate (average particle size 10 microns) and 2 parts by weight of calcium stearate as a lubricant in exactly the same manner as in Example 1.
Triblending, melt kneading and injection molding were performed. As a result, similar to Comparative Example 1, flow marks were generated on the surface of the molded product and the painted surface.

Example 2 100 parts by weight of the same composition as used in Comparative Example 2 and 10 parts by weight of P P (2) were added, and triblending was performed for 10 minutes using a tumbler. The obtained mixture was injection molded in the same manner as in Example 1. As a result, there were no flow marks on the surface or painted surface of the molded product, and both were beautiful.

Comparative Example 3 Ethylene-butene with a density of 0.9489/crA
1 copolymer CM, 1.20 g/10 min, butene-1
Content: 05% by weight, hereinafter referred to as PE (1) 70 parts by weight, 30 parts by weight of Merck (average particle size 30 microns)
and 05 parts by weight of calcium stearate in Example 1
Tri-blending, melt-kneading and injection molding were carried out in the same manner as above. As a result, it was observed that flow marks were generated on both the surface of the molded product and the painted surface.

Example 3 100 parts by weight of the same composition as that used in Comparative Example 3 and 5 parts by weight of Pg(+) were triblended in the same manner as in Example 1, and then injection molded in the same manner as in Example 1. I did it. No flow marks were observed on the surface or painted surface of the obtained molded product, and it had a beautiful surface.

Comparative Example 4 Example 3 except that instead of 5 parts by weight of PE (1) used in Example 3, triple-layered PE (1) was used.
Triblend and injection molding were carried out in the same manner as above. No improvement effect on the surface of the obtained molded product was observed, and 70-marks were observed on the surface as in Comparative Example 3.

Patent applicant: Showa Denko Co., Ltd. Agent: Patent attorney Sei Kikuchi

Claims (1)

[Claims] (5) 100 parts by weight of a composition consisting of a polyolefin resin and an organic filler and/or an inorganic filler and 5 to 50 parts by weight of a polyolefin resin are mixed without kneading and then injection molded. A method for producing a polyolefin resin molded article, characterized by: