JPH0611867B2 - Thermoplastic resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a novel thermoplastic resin composition, more specifically,
A molded product that contains surface-modified inorganic fibers of a specific shape, has an excellent balance of rigidity and impact resistance, and that suppresses the occurrence of silver streaks. The present invention relates to a thermoplastic resin composition having properties.

[Prior Art] Thermoplastic resins are easier to process than metal materials, have excellent corrosion resistance, are lightweight, and are relatively inexpensive. Therefore, in recent years, mechanical parts, precision parts, general industrial parts, furniture,
It is widely used in many fields as a material for daily sundries and structural materials.

However, thermoplastic resins generally have inferior rigidity and mechanical properties such as impact resistance as compared with metal materials, and also have drawbacks such as heat resistance and dimensional stability that are not always satisfactory. is doing.

Therefore, in order to improve the drawbacks of such a thermoplastic resin, conventionally, powdery, granular, plate-like, or fibrous ones are appropriately selected from inorganic fillers and organic fillers according to the purpose. It is performed by selecting and filling a thermoplastic resin.

For example, it is known that a resin composition having high rigidity can be obtained by blending polypropylene with ultrafine inorganic fibers having a high aspect ratio (JP-A-57-109).
846 publication). However, in this case, since the inorganic fibers are extremely fine and have a high aspect ratio, the entanglement of the fibers is likely to occur, and when the inorganic fibers are blended with the resin, the entanglement is not sufficiently disentangled, and as a result, the molded article is formed. Problems such as easy occurrence of spots on the surface of the are caused. In order to solve such a problem, it is possible to knead with a high shear, but in this case, a new problem occurs such that the fiber is likely to break and the effect of improving rigidity is insufficient.

Furthermore, since the inorganic fiber has a large specific surface area, the fluidity of the resin is significantly reduced when compounded, and it is difficult to produce a large-sized molded product or a thin molded product, and the molded product is dried even before molding. Silver streaks tend to occur on the surface,
It has the drawback of requiring drying at a considerably high temperature for a long time.

[Problems to be Solved by the Invention] The present invention can provide a molded article having an excellent balance of rigidity and impact resistance, and having a good surface in which the occurrence of silver streets and spots is suppressed, and the fluidity. The object of the present invention is to provide a thermoplastic resin composition containing an inorganic fiber, which has a good molded product and is free from deterioration.

[Means for Solving the Problem] As a result of intensive studies to develop a thermoplastic resin composition having the above-mentioned preferable properties, the present inventors have found that the surface of an inorganic fiber is a fatty acid metal salt in an aqueous medium. It was found that the object can be achieved by using the modified magnesium-based inorganic fiber having a specific property, and the present invention has been completed based on this finding.

That is, the present invention comprises (A) a thermoplastic resin and (B) a magnesium-based inorganic fiber having an average fiber diameter of 0.1 to 1.0 μm, an average fiber length of 5 to 100 μm and an oil absorption of 350 m / 100 g or more in an aqueous medium. 0.1 to 100 parts by weight
Containing in a weight ratio of 50:50 to 99: 1, surface-modified inorganic fibers obtained by surface-treating with 10 parts by weight of fatty acid sodium salt or fatty acid potassium salt, and granulated fibers obtained by further granulating. The present invention provides a thermoplastic resin composition comprising

Hereinafter, the present invention will be described in detail.

In the composition of the present invention, the thermoplastic resin used as the component (A) is not particularly limited, and any of those conventionally used as a molding material can be selected and used. When the temperature exceeds 260 ° C, the moldability of the resulting composition tends to deteriorate, and a silver streak may occur in a molded product. Therefore, a thermoplastic resin having a melting point of 260 ° C or lower is preferable. Examples of such a thermoplastic resin include a polyolefin resin, a polyvinyl chloride resin, a polyamide resin, a polyester resin, a polyacetal resin, a polycarbonate resin, a styrene resin, and an acrylate resin.

Examples of the polyolefin resin include α, such as ethylene, propylene, butene-1, 3-methylbutene-1, 3-methylpentene-1, and 4-methylpentene-1.
Examples thereof include olefin homopolymers, copolymers thereof, and copolymers of these with other copolymerizable unsaturated monomers. As a typical example, high density, medium density, low density polyethylene and linear low density polyethylene, ultra high molecular weight polyethylene, ethylene-vinyl acetate copolymer,
Polyethylene such as ethylene-ethyl acrylate copolymer, atactic, syndiotactic, isotactic polypropylene, polypropylene such as propylene-ethylene block copolymer or random copolymer, poly-4-methylpentene-1 etc. Can be mentioned.

Examples of the polyvinyl chloride-based resin include a vinyl chloride homopolymer and a copolymer of vinyl chloride and an unsaturated monomer copolymerizable with vinyl chloride. Examples of the copolymer include vinyl chloride-acrylic acid ester copolymer, vinyl chloride-methacrylic acid ester copolymer, vinyl chloride-ethylene copolymer, vinyl chloride-propylene copolymer, vinyl chloride-vinyl acetate copolymer. Examples thereof include polymers and vinyl chloride-vinylidene chloride copolymers. Further, those obtained by post-chlorinating these polyvinyl chloride resins to increase the chlorine content can be used.

Examples of polyamide resins include 6-nylon and 12
-A ring-opening polymerization of a cycloaliphatic lactam such as nylon, 6,6-nylon, 6,10-nylon, a condensation-polymerization of an aliphatic dicarboxylic acid such as 6,12-nylon and an aliphatic dicarboxylic acid, A polycondensation product of an aromatic diamine and an aliphatic dicarboxylic acid such as a polycondensation product of m-xylenediamine and adipic acid, a polycondensation product of p-phenylenediamine and terephthalic acid, and m-phenylenediamine and isophthalic acid. Examples thereof include those obtained by polycondensing an aromatic diamine and an aromatic dicarboxylic acid such as a polycondensation product of, and those obtained by polycondensing an amino acid such as 11-nylon.

Examples of the polyester resin include those obtained by polycondensing an aromatic dicarboxylic acid and an alkylene glycol,
Specific examples include polyethylene terephthalate and polybutylene terephthalate.

Examples of the polyacetal resin include homopolymer polyoxymethylene and formaldehyde-ethylene oxide copolymer obtained from trioxane and ethylene oxide.

The polycarbonate resin can be obtained by a 4,4′-dihydroxydiarylalkane polycarbonate, particularly a phosgene method in which bisphenol A and phosgene are reacted, or a transesterification method in which bisphenol A and a carbonic acid diester such as diphenyl carbonate are reacted. Bisphenol A-based polycarbonate is preferably used. In addition, modification in which a part of bisphenol A is replaced with 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane or 2,2-bis (4-hydroxy-3,5-dibromophenyl) propane Bisphenol A-based polycarbonate and flame-retardant bisphenol A-based polycarbonate can also be used.

Examples of the styrene-based resin include homopolymers such as styrene and α-methylstyrene, copolymers thereof, and copolymers with unsaturated monomers copolymerizable therewith. Typical examples are general-purpose polystyrene, impact-resistant polystyrene, heat-resistant polystyrene (α-methylstyrene polymer), acrylonitrile-butadiene-styrene copolymer (ABS), acrylonitrile-styrene copolymer (AS), acrylonitrile-. Examples thereof include chlorinated polyethylene-styrene copolymer (ACS) and acrylonitrile-ethylene propylene rubber-acrylonitrile-styrene copolymer (AAS).

Examples of the acrylate resin include methacrylic acid ester polymers and acrylic acid ester polymers, and examples of these monomers include methacrylic acid and acrylic acid methyl, ethyl, n-propyl, isopropyl,
Butyl ester and the like are used, and as a typical industrial molding material, a methyl methacrylate resin can be mentioned as a typical example.

Among these thermoplastic resins, polyethylene, polypropylene, polyamide, polyethylene terephthalate, polybutylene terephthalate, polyacetal, polycarbonate, polyphenylene ether, polystyrene, A
BS and the like are preferable.

In the composition of the present invention, one kind of these thermoplastic resins may be used, or two or more kinds thereof may be used in combination.

In the composition of the present invention, as the inorganic fiber of the component (B), the average fiber diameter is 0.1 to 1.0 μm, and the average fiber length is 5 to 100 μm.
m and an oil absorption amount of 350 m / 100 g or more of magnesium-based inorganic fibers surface-modified with fatty acid sodium salt or fatty acid potassium salt in an aqueous medium are used.
As described above, by surface-modifying the fiber, the dispersion performance is remarkably improved, and as a result, a molded product having no lumps can be obtained, kneading with a low share is possible, breakage of the fiber is suppressed, and higher A rigid molded product can be obtained.

If the average fiber diameter of the magnesium-based inorganic fibers is less than 0.1 μm, the bulk becomes too large, and it is difficult to knead. In addition, the entanglement of the fibers is severe, and it is difficult to uniformly disperse. Is deteriorated, and the rigidity tends to be insufficient. If the average fiber length is less than 5 μm, the effect of improving the rigidity is not sufficiently exhibited, and if it exceeds 100 μm, the appearance of the molded product tends to be deteriorated. further,
If the oil absorption is less than 350 m / 100 g, defibration of the fibers is insufficient, aggregates may occur, and gel may be generated in the molded product.

The amount of the fatty acid sodium salt or fatty acid potassium salt used for the surface modification of the magnesium-based inorganic fiber is selected in the range of 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight, per 100 parts by weight of the fiber. Be done. This amount is 0.1
If it is less than 10 parts by weight, the effect of improving the dispersion of the fiber is low, aggregates are easily generated, and the effect of improving the fluidity is not sufficiently exerted. If it exceeds 10 parts by weight, the effect of improving the dispersion is obtained for the amount. Is not observed, but rather the heat resistance and rigidity of the molded product tend to decrease.

The oil absorption is the amount of oil required for kneading with 100 g of the fiber to form a paste having a constant consistency.

Examples of the magnesium-based inorganic fiber include magnesium hydroxide fiber, magnesium oxysulfate fiber,
Magnesium sulfate fiber, magnesium oxide fiber, magnesium borate fiber and the like can be mentioned, and among these, magnesium oxysulfate fiber, magnesium hydroxide fiber and magnesium borate fiber are particularly preferable.
These inorganic fibers may be used alone or in combination of two or more.

In the present invention, the surface treatment of the magnesium-based inorganic fibers is performed in an aqueous medium. Next, one example of a suitable surface treatment method for the magnesium-based inorganic fiber is as follows:
First, the fibers are stirred in an aqueous medium to open the aggregate which is the entanglement of the fibers to release the entanglement. If there are many aggregates here, the oil absorption of the inorganic fibers will decrease and
/ 100g is not reached. Next, the fatty acid sodium salt or the fatty acid potassium salt is put into the suspension of the inorganic fiber and the aqueous medium under stirring, and the stirring is continued for several minutes to several hours. At this time, the fatty acid sodium salt or fatty acid potassium salt used is one that can be dissolved in an aqueous medium, and may be a saturated fatty acid sodium salt or potassium salt, or an unsaturated fatty acid sodium salt or potassium salt. Good.

The surface-modified magnesium-based inorganic fiber is washed with water, separated by a known means such as centrifugation, and then dried to obtain a desired surface-modified inorganic fiber. In addition, the separated inorganic fiber has a diameter of 0.3 to 5 m.
A granulated fiber obtained by extruding from an m hole to be granulated and then drying this in an oven at a temperature of about 150 ° C. for about 1 to 6 hours is preferable in terms of handling, and therefore is used in the present invention. It In this case, it is desirable that the average particle size of the granulated fiber is in the range of 0.1 to 5 mm, and if the average particle size is less than 0.1 mm, the handling improving effect is not sufficiently exhibited, and if it exceeds 5 mm, the dispersibility decreases. There is a tendency to do.

In the composition of the present invention, the thermoplastic resin as the component (A) and the surface-modified inorganic fiber as the component (B) are used in a weight ratio of 50:
50 to 99: 1, preferably 70:30 to 9
It is necessary to mix in a ratio of 5: 5. If the content of the inorganic fiber is less than 1% by weight based on the total weight of the thermoplastic resin and the inorganic fiber, the effect of improving the rigidity is not sufficiently exerted, and if it exceeds 50% by weight, the impact strength is significantly lowered, There is a tendency that the fluidity decreases and the appearance deteriorates.

If desired, the composition of the present invention may be blended with other powdery, granular, plate-like, fibrous, or other inorganic fillers and organic fillers as long as the object of the present invention is not impaired. it can.
Examples of the inorganic filler include oxides such as silica, diatomaceous earth, barium ferrite, beryllium oxide, pumice and pumice balloons, hydroxides such as aluminum hydroxide, magnesium hydroxide and basic magnesium carbonate, and calcium carbonate. , Carbonate such as magnesium carbonate, dolomite, dawsonite, calcium sulfate, barium sulfate, ammonium sulfate, sulfate or sulfite such as calcium sulfite, talc, clay, mica, asbestos, glass fiber, glass balloon, glass beads, calcium silicate , Montmorillonite, bentonite and other silicates,
Carbons such as carbon fiber, carbon black, graphite, carbon hollow spheres, etc., powders such as molybdenum sulfide, zinc borate, barium metaborate, calcium borate, sodium borate, boron fibers, etc., granular, plate-like, fibrous Inorganic fillers, powders of metal elements, metal compounds, alloys, etc., granular, fibrous, whisker-like metal fillers, powders of silicon carbide, silicon nitride, zirconia, aluminum nitride, titanium carbide, potassium titanate, etc. , Granular, fibrous, whisker-like ceramic fillers and the like.

On the other hand, as the organic filler, for example, shell fiber such as fir shell, wood powder, cotton, jute, paper strip, cellophane piece, aromatic polyamide fiber, cellulose fiber, nylon fiber, polyester fiber, polypropylene fiber, thermosetting Resin powder, rubber, etc. can be mentioned.

In the composition of the present invention, a chemical modifier such as a modified polyolefin may be optionally incorporated for the purpose of improving the compatibility between the matrix resin and the filler.
Further, in the composition of the present invention, if desired, various additives usually used in the resin composition, for example, a lubricant, a colorant,
Stabilizers, antioxidants, ultraviolet absorbers, antistatic agents, flame retardants, plasticizers and the like can be added.

The composition of the present invention comprises a predetermined amount of the component (A) thermoplastic resin,
It may be prepared by mixing the surface-modified inorganic fiber of the component (B) and various additive components used as desired, and kneading with a kneader, or using a thermoplastic resin and a desired resin in advance. It may be prepared by quantitatively feeding the added components to the extruder and kneading, and by side-feeding the surface-modified inorganic fiber to the portion where the resin is melted and kneading, but it is prepared by the latter method. Is advantageous.

The kneader is not particularly limited as long as it can knead the thermoplastic resin and the inorganic fiber, for example, a single screw extruder, a screw extruder such as a multi-screw extruder, an elastic extruder, hydrodynamic extrusion Machines, ram type continuous extruders, roll type extruders, gear type extruders and other non-screw extruders, and the like. Among these, screw extruders, particularly twin-screw extruders are preferable, and among them, hoppers A method in which more resin is added, and after melting, inorganic fibers are added from the side and kneading is particularly preferable.

The kneading is performed at a temperature equal to or higher than the melting temperature or the softening point of the thermoplastic resin used, and when kneading using a screw extruder, the screw rotation speed is usually 100 to 6
00 rpm, preferably 200 to 300 rpm is selected.

The thermoplastic resin composition of the present invention thus prepared can be used in injection molding, extrusion molding, blow molding, compression molding, lamination molding, roll processing, stretching, stamping, etc. A desired molded product is molded by various molding methods.

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 physical property of the composition was determined as follows.

(1) Izod impact strength (with notch) Obtained according to JIS K-7110.

(2) Flexural modulus It was determined according to JIS K-7203.

(3) Determined according to MI JIS K-7210.

(4) Dispersion state By press molding, create a thin film of 50 × 50 × 0.1 mm,
The number of aggregates of 0.05 mm or more was measured.

(5) Presence or absence of silver streak Using each pellet dried at 80 ° C for 3 hours 14
A box having a size of 5 × 95 × 35 mm and a gate diameter of 1 mm was molded, and the presence or absence of silver streaks near the gate was visually determined.

Further, as the inorganic fibers, those of the kind shown in Table 1 treated as follows were used.

That is, water 20 and 1 kg of each inorganic fiber in 20 stirring tanks.
Was charged and stirred for 3 hours. For the surface treatment, the surface treatment agents of the types shown in Table 1 are added to the inorganic fibers in the amounts shown in Table 1, and the mixture is stirred for another 1 hour, then water is separated and dried, The present fibers A to E and comparative fibers a to e used for preparing the composition were obtained.

The oil absorption of the inorganic fiber was measured according to JIS K-5101.

That is, sample 2 dried at 105 to 110 ° C. for 2 hours
5 g is taken on a glass plate (about 200 × 200 × 5 mm), and essential linseed oil (acid value 4 or less) is dropped little by little from the buret to the center of the sample, and kneaded with a spatula each time. The operation of dripping and kneading is repeated, and when the whole is gathered into one rod for the first time, the end point is determined, and the amount of refined linseed oil required is determined, and the oil absorption amount is calculated by the following formula.

Examples 1-5, Comparative Examples 1-6 A twin-screw kneader [TEM-35, shown in FIG. 1 as a kneader.
Manufactured by Toshiba Machine Co., Ltd.], and various thermoplastic resins shown in Table 2 are supplied from the material supply port 2 at a rate of 24 kg / Hr. Inorganic fiber is fed at a rate of 6 kg / Hr and kneading temperature is 200 to 2
The mixture was kneaded under the conditions of 60 ° C. and a rotor speed of 500 rpm, and then pelletized.

After drying the obtained pellets, they were molded by a predetermined mold by injection molding to obtain test pieces and box molded products. The evaluation results of each physical property are shown in Table 2.

[Effects of the Invention] The thermoplastic resin composition of the present invention is a mixture of a desired thermoplastic resin with surface-modified magnesium-based inorganic fibers having specific properties, and provides a balance between rigidity and impact resistance. It is possible to provide a molded product that is excellent and in which the occurrence of silver streaks is suppressed, and there is no decrease in fluidity.
It has good moldability and is suitable for use as a material for large-sized molded products and thin-walled molded products.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a kneader used for preparing a thermoplastic resin composition in Examples and Comparative Examples of the present invention,
In the figure, reference numeral 1 is a twin-screw kneader, 2 and 3 are material inlets, and 4 is a strand.

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Claims (1)

[Claims] 1. A thermoplastic resin (A) and an average fiber diameter (B).
0.1-1.0 μm, average fiber length 5-100 μm and oil absorption 3
50m / 100g or more magnesium-based inorganic fiber,
A weight ratio of granulated fibers obtained by further granulating the surface-modified inorganic fibers obtained by surface-treating with 0.1-10 parts by weight of fatty acid sodium salt or fatty acid potassium salt per 100 parts by weight in an aqueous medium. A thermoplastic resin composition comprising 50:50 to 99: 1.