JPH0819280B2 - Molding material - Google Patents

Description

TECHNICAL FIELD The present invention relates to a molding material, and more particularly to a molding material for molding a molded product having a good appearance and excellent physical properties.

[Prior art and its problems] Among composite resin materials using polyolefin as a matrix resin, fiber-reinforced polyolefin is lightweight and has excellent mechanical strength, so it is used as an important material in many fields. Has been done.

However, the fiber-reinforced polyolefin in which fibers having a long fiber length such as glass fiber are dispersed, the improvement in mechanical strength and the like is tentatively achieved, but the surface appearance of the molded product is poor, and warp and deformation are caused. It has the drawback of poor dimensional stability.

On the other hand, wollastonite, milled fiber and the like having a short fiber length and a small aspect ratio have an insufficient effect of improving rigidity and the like.

Therefore, recently, a method has been proposed in which ultrafine fibers having a large aspect ratio are used to obtain a material having high rigidity and good appearance (JP-A-57-109846).

In this case, the ultrafine and high aspect ratio fibers have a bulk specific gravity of a small value of about 0.02 to 0.1, so that it is difficult to stably produce the fibers, and the fibers are strongly aggregated in the matrix. This agglomeration hinders good dispersion of the fibers and causes a gel on the surface of the molded article. In order to prevent this agglomeration, it is necessary to knead with a high shearing force, which causes a problem that the fiber breaks and the fiber becomes short.

An object of the present invention is to overcome the above-mentioned drawbacks of the prior art and to provide a molding material for molding a molded product having a molded product having a good appearance and excellent physical properties.

[Means for Solving Problems] As a result of intensive studies to achieve the above object, the present inventors have granulated fibers having a specified average fiber diameter, aspect ratio and oil absorption into a specified average diameter and bulk specific gravity. It was found that a molded product molded using a specific molding material composed of the granulated fiber and the polyolefin described above has a good appearance and excellent physical properties, and as a result, the present invention has been completed.

That is, the composition of the present invention is 40 to 98% by weight of polyolefin, an average fiber diameter of 0.1 to 1.0 μm, an aspect ratio of 50 to 300, and an inorganic fiber having an oil absorption of 400 ml / 100 g or more. A molding material comprising 2 to 60% by weight of granulated fibers having an average diameter of 0.5 to 5 mm and a bulk specific gravity of 0.15 to 0.4.

Examples of the polyolefin that can be used in the present invention include polypropylene, high density polyethylene, medium density polyethylene, low density polyethylene, linear low density polyethylene, polybutene and the like. These may be used alone or in combination of two or more.

Of these, polypropylene is preferred.

Examples of the polypropylene include polypropylene homopolymer; ethylene-propylene block copolymer, ethylene-propylene random copolymer, ethylene-containing other monomers such as dicyclopentadiene.
Examples thereof include an ethylene-propylene copolymer such as a propylene-diene copolymer, and a mixture of a polypropylene homopolymer and the ethylene-propylene copolymer.

From the viewpoint of the production method, a polyolefin obtained by using a Ziegler-Natta catalyst and a multi-step polymerization method of two or three or more steps can also be used.

The method for producing polypropylene, for example, by this multistage polymerization method will be further described as follows.

That is, for example, in the presence of a Ziegler-Natta catalyst, for example, the propylene monomer in the first stage is polymerized to obtain a polypropylene homopolymer, and then the propylene monomer is removed or not removed in the presence of ethylene in the second and subsequent stages. Alternatively, polypropylene can be produced by carrying out a polymerization reaction in the coexistence of ethylene and propylene. The pressure in the reaction in each stage may be from several atm to 40 atm, and the temperature may be from room temperature to 80 ° C. Further, as a polymerization reaction system, solution polymerization, slurry polymerization, gas phase polymerization, a combination method thereof, or the like can be employed.

The polypropylene obtained by such a multi-stage polymerization method contains ethylene as a monomer unit in the resin, so it is not clear yet whether polyethylene is contained in the resin or a mixture of ethylene and propylene. It may contain a polymer.

In the present invention, polypropylene obtained by the above-mentioned multistage polymerization method is preferable.

One of the important things in the present invention is that the content of the above-mentioned polyolefin is 40 to 98% by weight, preferably 50 to 95% by weight.

When the content is less than 40% by weight, the impact resistance is significantly reduced, and when it is more than 98% by weight, the rigidity is significantly reduced.

As the inorganic fiber in the present invention, it is possible to use fibrous magnesium oxysulfate, potassium titanate fiber, magnesium hydroxide fiber, magnesium oxide fiber, gypsum fiber, glass fiber, silicon carbide fiber, calcium silicate fiber, carbon fiber and the like. it can.

In particular, magnesium-based fibers such as fibrous magnesium oxysulfate, magnesium hydroxide fiber and magnesium oxide fiber are preferable.

What is important in the present invention is that the average fiber diameter of the inorganic fibers is 0.1 to 1.0 μm, preferably 0.2 to 0.8 μm.

When the average fiber diameter is less than 0.1 μm, a large amount of fiber aggregates cannot be crushed, and the fibers are easily broken during crushing.

The aspect ratio of the inorganic fiber is 50 to 300,
It is preferably 60 to 200.

When the aspect ratio is less than 50, sufficient rigidity cannot be obtained, and when it exceeds 300, the appearance becomes poor.

The oil absorption of the inorganic fiber is 400 ml / 100 g or more,
It is preferably 450 ml / 100 g or more.

If the oil absorption is less than 400 ml / 100 g, the aggregated fibers will not be sufficiently crushed and a large number of aggregates will be present, resulting in gel formation in the molded product.

In the present invention, a granulated fiber having an average diameter and a bulk specific gravity obtained by granulating the inorganic fiber having a specific value for the average fiber diameter, the aspect ratio and the oil absorption amount by an appropriate method is used.

As an appropriate method for granulation, for example, in a stirring tank containing a predetermined amount of water, the inorganic fibers are charged, the aggregate of the inorganic fibers is crushed under stirring, water is separated, gel It can be mentioned that the crushed crushed fiber is extruded through a hole having a diameter of 0.3 to 5 mm to be granulated and dried in an oven to produce a target granulated product.

The average diameter of the granulated fiber is 0.3 to 5 mm, preferably 0.5 to 3 mm. When the average diameter is less than 0.3 mm or more than 5 mm, the handleability during kneading becomes poor.

The bulk specific gravity of the granulated fiber is 0.15 to 0.4, preferably 0.18 to 0.35. Bulk specific gravity is less than 0.15 or 0.4
When it exceeds the above range, the kneading machine is less likely to be bitten into the kneading machine, and it becomes difficult to produce a polyolefin resin molded product having stable quality.

The amount of such a specific granulated fiber is 60 to 2% by weight.
And preferably 50 to 5% by weight.

When the content is more than 60% by weight, the impact resistance of the polyolefin resin molded product is remarkably reduced, and when it is less than 2% by weight, the rigidity is remarkably reduced.

The molding material of the present invention may be blended with other inorganic filler in the form of a plate, a sphere or an amorphous material to the extent that the object of the present invention is not impaired.

As a plate-shaped inorganic filler, the average particle size is 0.3 ~ 10μ
Those in the range of m are preferable, and examples thereof include talc, mica, clay, sericite, glass flakes, graphite, and aluminum flakes having an average particle size in the above range, and particularly, the average particle size is in the range of 0.5 to 2 μm. The talc, sericite, and clay found in are suitable.

The spherical or amorphous inorganic filler preferably has an average particle size in the range of 0.05 to 10 μm. For example, calcium carbonate (heavy, light, colloid), barium sulfate, carbonic acid having an average particle size in the above range. Magnesium, alumina, silica, calcium sulfate, glass beads, glass powder, white carbon, hollow glass spheres, silica sand, silica stone, carbon black, magnesium hydroxide, zinc oxide, white luster, basic magnesium carbonate, zeolite, molybdenum, oxidation Examples include titanium, diatomaceous earth, calcium hydroxide, calcium sulfite, quartz powder, bentonite, sodium sulfate and the like.

Polyolefin resin molded article of the present invention, other polymers, for example, polyethylene, EP rubber, SB rubber and other elastomers, maleic anhydride modified polyolefin, epoxy modified polyolefin, etc., within the range not impairing the object of the present invention. It may be blended, and further, various surface treatment agents such as silane coupling agents and titanate coupling agents, higher fatty acids, metal salts of higher fatty acids, and dispersants such as higher alcohols, antioxidants, and ultraviolet rays. Additives such as an absorber, an antistatic agent, a weathering agent, and a flame retardant may be blended as desired.

Examples of the elastomer include styrene-ethylene-butadiene-styrene rubber (S-E-B-S), styrene-butadiene-styrene rubber (S-B-S), styrene-isoprene-styrene rubber (S-I-S). Styrene-based elastomers such as styrene-butadiene rubber (SB), olefin-based elastomers such as ethylene propylene rubber and ethylene propylene diene rubber are preferable,
Styrene-butadiene rubber and ethylene propylene rubber are particularly preferable.

In addition to the above components, the molding material of the present invention may optionally contain various additives such as a lubricant, a nucleating agent, an antioxidant, an antistatic agent, an ultraviolet absorber, a flame retardant, a release agent, and a colorant. In particular, when a lubricant is added and blended, the dispersibility of the granulated fiber blended in the polyolefin resin composition can be improved and impact strength and flow characteristics can be improved.

Here, examples of the lubricant include hydrocarbon lubricants such as liquid paraffin, natural paraffin and wax; fatty acid lubricants such as higher fatty acids such as stearic acid, palmitic acid, oleic acid, myristic acid and behenic acid, and oxyfatty acids; stearin. Fatty acid ester lubricants which are lower alkyl esters of higher fatty acids such as acids, palmitic acid, oleic acid, myristic acid, behenic acid, etc. such as methyl, ethyl, propyl, butyl; aliphatic higher or lower alcohols, alcohols such as polyglycol System lubricants; metal soaps such as calcium stearate and barium stearate; silicone oils, silicones such as modified silicones, and the like. Among these, metal soap type which is a metal salt of higher fatty acid and alkyl ester type of higher fatty acid are particularly preferable, and magnesium stearate and stearic acid n-butyl ester are particularly preferable.

Examples of the antioxidant include 2,6-di-t-butyl-p-cresol, butylated hydroxyanisole,
2,6-di-butyl-4-ethylphenol, stearyl-β- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, 2,2-methylenebis (4-methyl-6-t-butylphenol) ), 2,2-methylenebis (4-ethyl-6-t-butylphenol), 4,4-thiobis (3-methyl-6-t-butylphenol), 4,
4-butylidene bis- (3-methyl-6-t-butylphenol), tetrabis [methylene-3- (3,5-di-
t-butyl-4-hydroxyphenyl) propionate] methane, phenolic compounds such as 1,1,3-tris- (2-methyl-4-hydroxy-5-t-butylphenyl) butane, phenyl-β-naphthylamine , N, N
Amine compounds such as diphenyl-p-phenylenediamine, tris (nonylphenyl) phosphite, triphenyl phosphite, trioctadecyl phosphite, phosphorus compounds such as diphenyl isodecyl phosphite, dilauryl thiodipropionate Sulfur compounds such as dimyristyl thiodipropionate and distearyl thiodipropionate.

Examples of the antistatic agent include nonionic antistatic agents such as polyoxyethylene alkylamines and polyoxyethylene alkylamides, anionic antistatic agents such as alkyl sulfonates and alkylbenzene sulfonates, quaternary ammonium chlorides, Examples include cationic antistatic agents such as quaternary ammonium sulfate, and amphoteric antistatic agents such as alkylbetaine type and alkylimidazoline type.

Examples of the ultraviolet absorber include salicylic acid-based ultraviolet absorbers such as phenyl salicylate and pt-butylphenyl salicylate, benzophenone-based ultraviolet absorbers such as 2,4-dihydroxybenzophenone-2-hydroxy-4methoxybenzophenone, 2- (2-hydroxy-
5-methylphenyl) benzotriazole, 2- (2-
Examples include hydroxy-5-t-butylphenyl) benzotriazole-based UV absorbers.

Examples of the nucleating agent include metal salts of organic acids, amine salts of organic acids, sorbitol derivatives and the like, and metal salts of organic acids and sorbitol derivatives are preferable.

Examples of the metal salt of the organic acid include benzoic acid, p
-(Tert-butyl) benzoic acid, cyclohexanecarboxylic acid, β-naphthoic acid, cyclopentanecarboxylic acid, succinic acid, diphenylacetic acid, glutaric acid, isonicotinic acid,
Adipic acid, sebacic acid, phthalic acid, isophthalic acid, benzenesulfonic acid, glycolic acid, caproic acid,
Examples thereof include sodium salts such as isocaproic acid, phenylacetic acid, and cinnamic acid, calcium salts, aluminum salts, magnesium salts, and the like, and aluminum salt of p- (tert-butyl) benzoic acid is preferable.

Examples of the amine salt of the organic acid include benzoic acid,
There are amines derived from phthalic acid, adipic acid, etc.

Examples of the sorbitol derivative include 1,3,2,4
-Dibenzylidene sorbitol, 1,3,2,4-di (methoxybenzylidene) sorbitol, 1,3,2,4-di (ethoxybenzylidene) sorbitol and the like are mentioned, and among these, dibenzylidene sorbitol is preferable.

In producing a molded product using the molding material of the present invention, the above-mentioned components are blended in a predetermined amount and preblended in advance using a ribbon blender, a V-type blender or the like so that the granulated fiber is not crushed.

The kneading can be performed using a single-screw extruder, a twin-screw extruder or the like, and is performed at a temperature of 180 ° C. or higher, preferably 210 ° C. or higher. There is no particular limitation on the order of addition of each component and the mixing order during mixing and melt mixing.

In the case of producing a molded product from the molding material of the present invention, various molding methods such as injection molding method, extrusion molding method, hollow molding method, compression molding method, lamination molding method, roll processing method, stretching processing method, stamping method, etc. Can be adopted.

The molding material of the present invention is widely used as an automobile material or a weak electric material depending on various molding methods.

[Examples] Hereinafter, the present invention will be described in more detail with reference to Examples.

The granulated fiber used in the following examples was manufactured as follows.

Manufacture of granulated fiber A Into a stirring tank of 20, 1 kg of fibrous magnesium oxysulfate (raw material) having an average fiber diameter of 0.6 μm, an aspect ratio of 100, and a bulk specific gravity of 0.06 is charged, and stirred for 3 hours, After crushing the agglomerates and then separating the water content, the gel-like fibers are extruded through a hole with a diameter of 3 mm, granulated, and dried in an oven at 200 ° C. for 1 hour,
This obtained the target granulated fiber A.

Table 1 shows the properties of the fibrous magnesium oxysulfate before the granulation after the water separation and the shape of the granulated fiber.

Production of Granulated Fiber B In the production of the above-mentioned granulated fiber A, an average fiber diameter of 0.4 μm,
A fibrous magnesium oxysulfate (raw material) with an aspect ratio of 50 and a bulk specific gravity of 0.08 is used, and the stirring time is 3
Granulated fiber B was produced in the same manner as in the case of the granulated fiber A except that the time was changed to 10 minutes and the fibrous magnesium oxysulfate shown in Table 1 was used.

Production of Granulated Fiber C In the production of the granulated fiber A, water 2 is used without crushing with water by using fibrous magnesium oxysulfate having an average fiber diameter of 0.04 μm, an aspect ratio of 40, and a bulk specific gravity of 0.09. In addition, after gelling, fibrous magnesium oxysulfate shown in Table 1 was used to extrude and granulate in the same manner.
After drying for an hour, the target granulated fiber C was obtained.

 The properties of the granulated fibers A, B and C are shown in Table 1.

In addition, in the following examples, the oil absorption was measured according to JIS-K5101 using the fiber before granulation as a sample.

The bulk specific gravity is measured using JIS-K
It carried out according to 5101.

In addition, photographs showing the state of the fibers in the manufacturing process of the granulated fibers A, B, and C are attached as FIGS. 1 (a), (b), and (c).

Photo A: In the production of granulated fiber A, it is a photomicrograph of the fiber after stirring for 3 hours to crush the aggregates.

Photo B: In the production of granulated fiber B, it is a micrograph of the fiber after stirring for 10 minutes and disintegrating the aggregates.

Photo C: A photomicrograph of the raw material magnesium oxysulfate.

(Example 1) Polypropylene a (ethylene content 4% by weight, MI = 8 g
/ 10 minutes) 80% by weight and 20% by weight of the above granulated fiber A are mixed,
After mixing, pellets were produced by kneading using a twin-screw kneader (2FCM; Kobe Steel) at a set temperature of 200 ° C. and a rotor speed of 900 rpm. Using this pellet, a flat plate of 140 × 140 × 3 mm and a test piece were prepared by an injection molding machine. The surface condition of the flat plate was observed and the amount of gel was measured. In addition, bending strength (in accordance with JIS K7203), bending elastic modulus (in accordance with JIS K7203), and Izod impact strength (in accordance with JIS K7110) were measured.

 The results are shown in Table 2.

(Comparative Examples 1 and 2) The procedure of Example 1 was repeated except that the granulated fibers B and C were used instead of the granulated fibers A.

 The results are shown in Table 2.

(Examples 2 and 3) and (Comparative Examples 3 and 4) Polypropylene a and the granulated fiber A or fibrous magnesium oxysulfate (raw material) before crushing thereof were blended at a ratio shown in Table 3 and mixed. After that, using a twin-screw kneader (ZSK-90: manufactured by Werner Co.), a set temperature of 200 ° C,
Kneading was performed at a screw rotation speed of 300 rpm.

 The discharge state and discharge amount were measured.

 The results are shown in Table 3.

(Examples 4, 5, 6) and (Comparative Examples 5, 6) In the production of the granulated fiber A, the diameter of the extrusion hole was 3 mm.
From 1 mm, 2 mm, 3 mm, 0.1 mm and 8 mm to produce various granulated fibers D, E, F, G, H shown in Table 4,
Biaxial kneader as a kneader (4FCM: Kobe Steel, Ltd.)
Was carried out in the same manner as in Example 1 except that the set temperature was 200 ° C., the rotor speed was 600 rpm, and the orifice opening was 60%.

 The results are shown in Table 5.

(Examples 7, 8, 9) and (Comparative Examples 7, 8, 9) Fibrous magnesium oxysulfate (raw material) having a bulk specific gravity shown in Table 6 before crushing and before granulation after crushing Granulated fibers I, J, K and L were obtained in the same manner as the granulated fiber A by extruding fibrous magnesium oxysulfate through extrusion holes of 3 mm and 1 mm.

Next, polypropylene (b) (ethylene 4%, MI = 10
g / 10 minutes) and blending each granulated fiber as shown in Table 7, mixing, and then pelletizing at a set temperature of 200 ° C and a rotor speed of 900 rpm using a twin-screw kneader (2FCM). Was manufactured.

Then, using an injection molding machine, a 140 × 140 × 3 mm flat plate and a test piece were prepared. Each physical property was measured in the same manner as in Example 1.

 The results are shown in Table 7.

(Examples 10, 11, 12, 13) Example 1 was carried out in the same manner as in Example 1 except that various polyolefins shown in Table 8 were used instead of polypropylene a.

In the table, c is linear low density polyethylene (density 0.
920g / cm ³ , MI = 1.0g / 10min, butene-1 content 5mol%), d is high density polyethylene, (density 0.968g / cm ³ , MI
= 5g / 10 minutes), e is polypropylene “Idemitsu Polypro J3050
H, manufactured by Idemitsu Petrochemical Co., Ltd., density 0.90 g / cm ³ , MI = 35 g /
10 minutes, f is a mixture of d and e at 20:80.

 The results are shown in Table 8.

(Comparative Examples 10, 11, 12, and 13) Comparative Example 2 was carried out in the same manner as Comparative Example 2 except that various polyolefins shown in Table 9 were used instead of using polypropylene a.

The polyolefin used in Examples 10 to 13 was used.

 The results are shown in Table 9.

[Effects of the Invention] The molding material of the present invention can stably manufacture a molded product of constant quality, and the molded product obtained has a good appearance without gel and has a good bending strength and bending elasticity. The mechanical properties such as the elastic modulus and Izod impact strength are excellent.

[Brief description of drawings]

1 (a), (b) and (c) are electron micrographs showing the state of the manufacturing process of the granulated fiber in the present invention.

Claims (2)

[Claims] 1. Granulation of 40 to 98% by weight of polyolefin, an average fiber diameter of 0.1 to 1.0 μm, an aspect ratio of 50 to 300, and an oil absorption of 400 ml / 100 g or more. , The average diameter is 0.5 to 5 mm, and the bulk specific gravity is 0.
A molding material comprising 2 to 60% by weight of granulated fibers of 15 to 0.4. 2. The molding material according to claim 1, wherein the inorganic fiber is a magnesium fiber.