JP2653543B2 - Resin composition for precision molding and method for producing the same - Google Patents

Description

The present invention relates to a high-strength thermoplastic resin composition.
More specifically, the present invention relates to a thermoplastic resin composition having excellent precision moldability, high mechanical strength such as impact strength, and good dimensional stability.

[Conventional technology and its problems]

A melt-processable polyester resin capable of forming an anisotropic molten phase (hereinafter abbreviated as liquid crystalline polyester resin) is a thermoplastic resin having good fluidity and excellent dimensional stability, and can be easily molded by injection molding. In addition to the fact that by adding a filler, it is possible to not only improve the mechanical strength but also obtain a molded product having a thermal expansion characteristic close to that of a metal, so that precision parts and the like can be manufactured at low cost by mass production. In recent years, the amount of use has been increasing as a material that can be used to manufacture parts by substituting a metal that requires much processing. As the filler to be added, use of glass fibers, inorganic fillers, whiskers, or the like is generally known depending on the purpose (for example, JP-A Nos. 61-285249, 63-101448, and 63-10448).
Nos. 1450, 63-162753, and 63-247098).

However, glass fibers usually have a fiber diameter of 5-20.
μm, fiber length is 50-40 after compounding
When injection molding a precision part with a small gate because it is as long as 0 μm, there are problems such as clogging of the gate opening and insufficient filling of the mold cavity. Depending on the size and shape of the molded product, it may not be used. Limited. Granular or plate-like inorganic fillers are effective in preventing deformation and improving dimensional accuracy, but have little strength reinforcing effect and do not satisfy the requirements in this respect, and their use may be limited.

Among these known fillers, potassium titanate fiber has an average fiber diameter of 1 μm or less and an average fiber length of 100 μm or less, which is relatively suitable for injection molding of precision parts. A composition containing potassium fiber is insufficient in mechanical properties such as impact strength and elongation, and is used in precision parts such as watches and gears of cameras, particularly in thin or small-sized applications requiring mechanical strength. Often not enough.

[Means for solving the problem]

The present inventors have intensively studied a resin composition having a wide range of applications that can be applied to precision parts, has high mechanical properties, and can be used for parts requiring strength. As a result, by using a liquid crystalline polyester resin having a small molding shrinkage rate, a low linear expansion coefficient, and good dimensional stability as a base resin and blending aluminum borate fiber as a filler, mechanical properties such as impact strength can be improved. It has been found that a composition having significantly improved strength can be obtained.

Further, this composition was found to further improve the strength by adding and melting and kneading a specific silane compound separately from the above-mentioned inorganic filler, thereby completing the present invention.

That is, the present invention provides (A) 95 to 20 parts by weight of a melt-processable polyester capable of forming an anisotropic molten phase, (B) 5 to 70 parts by weight of aluminum borate fiber, and (C) a component B) Apart from the presence or absence of the surface treatment agent of the component and the other inorganic filler, aminosilane,
One or more silane compounds of epoxy silane, vinyl silane, and mercapto silane are blended in an amount of 0.05 to 5 parts by weight based on 100 parts by weight of aluminum borate fiber (B), and the mechanical strength is further increased by melt-kneading. The present invention relates to a resin composition and a method for producing the same.

Hereinafter, the components constituting the composition of the present invention will be described in detail.

First, the liquid crystalline polyester, which is the base resin of the present invention, is a melt-processable polyester having a property that the polymer molecular chains take a regular parallel arrangement in a molten state. The state in which molecules are arranged in this manner is often referred to as a liquid crystal state or a nematic phase of a liquid crystal substance. Such polymer molecules are generally elongated, flat, composed of polymers that are fairly rigid along the long axis of the molecule and that have chain extension bonds, usually in either a coaxial or parallel relationship. .

The properties of the anisotropic molten phase can be confirmed by a conventional polarization inspection method using an orthogonal polarizer. More specifically, the anisotropic molten phase was analyzed using a Leitz polarizing microscope, Leitz
It can be confirmed by observing the molten sample placed on the hot stage under a nitrogen atmosphere at a magnification of 40 times. When tested between crossed polarizers, the polymers of the present invention transmit polarized light and exhibit optical anisotropy, even in the melt-static state.

The liquid crystalline polymer used in the present invention is practically insoluble in general solvents and therefore unsuitable for molding by a solution method.However, these polymers can be easily molded by ordinary melt processing. it can.

The polymer showing an anisotropic melt phase used in the present invention,
Aromatic polyesters and aromatic polyesteramides are preferred, and polyesters partially containing aromatic polyesters and aromatic polyesteramides in the same molecular chain are also preferred examples.

Particularly preferred are liquid crystalline aromatic polyesters and liquid crystalline aromatic polyesteramides having at least one compound selected from the group consisting of aromatic hydroxycarboxylic acids, aromatic hydroxylamines and aromatic diamines as constituents.

That is, the constituent components include: 1) a polyester mainly composed of one or more aromatic hydroxycarboxylic acids and derivatives thereof 2) mainly a) one of aromatic hydroxycarboxylic acids and derivatives thereof
B) one or more of aromatic dicarboxylic acids, alicyclic dicarboxylic acids and derivatives thereof and c) at least one of aromatic diols, alicyclic diols, aliphatic diols and derivatives thereof Or a polyester composed of two or more types. 3) Mainly a) Aromatic hydroxycarboxylic acid and one of its derivatives
B) one or more aromatic hydroxyamines, aromatic diamines and derivatives thereof and c) one or more aromatic dicarboxylic acids, alicyclic dicarboxylic acids and derivatives thereof 4) Mainly a) aromatic hydroxycarboxylic acid and one of its derivatives
B) one or more aromatic hydroxyamines, aromatic diamines and derivatives thereof and c) one or more aromatic dicarboxylic acids, alicyclic dicarboxylic acids and derivatives thereof d) Polyester amide comprising at least one kind or two or more kinds of aromatic diols, alicyclic diols, aliphatic diols and derivatives thereof.

Preferred examples of specific compounds constituting the liquid crystalline polyester of the present invention include para-substituted benzene compounds such as p-hydroxybenzoic acid, terephthalic acid, hydroquinone, p-aminophenol and p-phenylenediamine, and their nuclear substitution. Benzene compounds (substituents are chlorine, bromine,
Methyl, phenyl, 1-phenylethyl), meta-substituted benzene compounds such as isophthalic acid and resorcin, 2,6-naphthalenedicarboxylic acid, 2,6-dihydroxynaphthalene, 1,4-dihydroxynaphthalene and 6- Naphthalene compounds such as hydroxy-2-naphthoic acid, biphenyl compounds such as 4,4'-diphenyldicarboxylic acid and 4,4'-dihydroxybiphenyl, represented by the following general formula (I), (II) or (III) Compound: (However, X: alkylene (C ₁ -C ₄ ), alkylidene, -O
—, —SO—, —SO ₂ —, —S—, and —CO— a group Y: — (CH ₂ ) _n — (n = 1 to 4), —O (CH ₂ ) _n O— (n
= 1 to 4)).

In addition, the liquid crystalline polyester used in the present invention may include a polyalkylene terephthalate which does not show a partial anisotropic molten phase in the same molecular chain, in addition to the above-mentioned constituent components. In this case, the alkyl group has 2 to 4 carbon atoms.

Among the above-mentioned components, those containing one or more compounds selected from para-substituted benzene compounds, naphthalene compounds and biphenyl compounds as essential components are more preferable examples. Among the para-substituted benzene compounds, p-hydroxybenzoic acid, methylhydroquinone and 1-phenylethylhydroquinone are particularly preferred examples.

Specific examples of the compound having an ester-forming functional group as a constituent component and specific examples of a polyester forming an anisotropic molten phase preferable for use in the present invention are described in JP-A-61-285249. ing.

Liquid crystalline polyesters suitable for use in the present invention generally have a weight average molecular weight of about 2,000-200,000, preferably about 1
It is in the range of from 20,000 to 50,000, particularly preferably from about 20,000 to about 25,000. On the other hand, suitable aromatic polyesteramides generally have a molecular weight of about 5,000 to 50,000, preferably about 10,000 to 30,000.
0, for example, 15,000 to 17,000. Such determination of molecular weight can be performed by gel permeation chromatography and other standard methods without solution formation of the polymer, for example by quantifying end groups by infrared spectroscopy on compression molded films. Alternatively, the molecular weight can be measured by using a pentafluorophenol solution and using a light scattering method.

The aromatic polyesters and polyesteramides described above, when dissolved in pentafluorophenol at a concentration of 0.1% by weight at 60 ° C., have at least about 2.0 dl / g, for example, about 2.0 dl / g.
An intrinsic viscosity (IV) of 110.1 dl / g is generally indicated.

Further, as the liquid crystal polyester resin as the base resin of the present invention, a resin to which other thermoplastic resin is added in addition to the liquid crystal polyester resin may be used as long as the purpose is not hindered.

The thermoplastic resin used in this case is not particularly limited, but examples thereof include polyethylene, polyolefins such as polypropylene, polyethylene terephthalate, aromatic dicarboxylic acids such as polybutylene terephthalate and aromatic polyesters such as diols or oxycarboxylic acids. , Polyacetal (homo or copolymer), polystyrene, polyvinyl chloride, polyamide, polycarbonate, ABS, polyarylene oxide, polyarylene sulfide, fluororesin and the like. These thermoplastic resins can be used as a mixture of two or more kinds.

Next, the aluminum borate fiber used in the present invention mainly has a composition represented by the general formula mAl ₂ O ₃ .nB ₂ O ₃ (m, n is an integer of 1 to 10), for example, 9Al ₂ O _3. 2B ₂ O ₃ or 2Al ₂ O ₃ · B ₂ O ₃ as a main component of the substance represented by the composition, or a mixture of both as the main component,
It is a single crystal fiber having an average fiber diameter of 5 μm or less and an average fiber length of 150 μm or less as measured by microscopy. Among them, particularly, the average fiber diameter is 0.2 to 4.0 μm, and the average fiber length is 5 to 5.
Those with a diameter of 100 μm are preferably used, and those with smaller diameters and lengths have less reinforcing effect on molded products, and those with larger diameters may cause clogging of gates or insufficient filling when molding precision parts. Is not preferred for use.

The amount of aluminum borate fiber used is 95 to 30
The appropriate amount is 5 to 70 parts by weight based on the weight. If the amount is less than 5 parts by weight, the mechanical strength is not sufficient.

In the present invention, the aluminum borate fiber is not particularly subjected to a surface treatment, or may be one obtained by hydrolyzing a surface treatment agent on the surface of the aluminum borate fiber and reacting and adhering it, as is usually performed. Good, especially when the silane compound is used alone and melt-kneaded separately from the surface treatment agent as described below, the mechanical strength reinforcing effect becomes extremely excellent and the fluidity is also improved. Was found.

As such a silane compound, especially aminosilane,
Epoxy silane, vinyl silane and mercapto silane are preferably used.

Specific examples of these silane compounds include, for example, aminosilanes such as γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropylmethyldimethoxysilane, γ
-Aminopropylmethyldiethoxysilane, N- (β-
Epoxysilanes such as aminoethyl) -γ-aminoproltrimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-diallylaminopropyltrimethoxysilane, and γ-allylaminopropyltrimethoxysilane Glycidoxypropyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, and the like. Examples of vinylsilanes include vinyltriethoxysilane, vinyltrimethoxysilane, Vinyl tris (β-
Examples of mercaptosilanes such as methoxyethoxy) silane include γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, γ-allylthiopropyltrimethoxysilane, and the like.

The amount of silane compound used is aluminum borate fiber 10
0.05 to 5 parts by weight with respect to 0 parts by weight is suitable.
３3 parts by weight are preferably used. If the amount is too small, the effect of reinforcing the mechanical strength is not sufficient, and if it is too large, gas is generated during extrusion, which is not preferable.

In addition to the aluminum borate fiber, the composition of the present invention comprises
If necessary, a filler generally used for a thermoplastic resin may be used in combination as long as the object of the present invention is not impaired. In this case, a fibrous, powdery, or plate-like filler is used. Among them, fibrous fillers include glass fiber, asbestos fiber, carbon fiber, silica fiber, silica-alumina fiber, zirconia fiber, boron nitride fiber, silicon nitride fiber, boron fiber, potassium titanate fiber, and stainless steel, Inorganic fibrous substances such as fibrous materials of metals such as aluminum, titanium, copper, and brass. In addition, a high melting point organic fibrous substance such as polyamide, fluorine resin, and acrylic resin can also be used.

On the other hand, as the granular filler, carbon black, silica, quartz powder, glass beads, glass powder, calcium silicate, aluminum silicate, kaolin, talc, clay,
Diatomaceous earth, silicates like wollastonite, iron oxide,
Oxides of metals such as titanium oxide, zinc oxide and alumina,
Further, there may be mentioned metal carbonates such as calcium carbonate and magnesium carbonate, metal sulfates such as calcium sulfate and barium sulfate, and other metal powders such as silicon carbide, silicon nitride, boron nitride.

Examples of the plate-like filler include mica, glass flake, various metal foils, and the like.

These inorganic fillers can be used in combination of two or more kinds in addition to the aluminum borate fiber.

Since many of these fillers, especially fibrous inorganic fillers, have large average diameters and average lengths, care must be taken in their size and amount used to prevent clogging and insufficient filling during precision molding. .

The amount of the filler used is generally at most 40% by weight or less based on the total composition, and the total amount of the filler and the aluminum borate fiber is desirably 75% by weight or less based on the whole composition.

The composition of the present invention further includes known substances generally added to thermoplastic resins, such as antistatic agents, flame retardants, coloring agents such as dyes and pigments, lubricants and crystallization accelerators, and crystal nucleating agents. Can also be added as needed.

The resin composition of the present invention can be prepared by equipment and a method generally used for preparing a synthetic resin composition.
That is, necessary components can be mixed, kneaded using a single-screw or twin-screw extruder, and extruded into pellets for molding.

The silane compound may be added directly to the extruder in a state where the silane compound and other components are simply adhered and mixed instead of being strongly bonded by chemical bonding or surface treatment, or the silane compound may be extruded. It is preferable to use an addition method such as a method of supplying the material alone into the machine. Although the cause is not clear, the silane compound is hydrolyzed to the surface of the aluminum borate fiber prior to compounding as usual, and the reaction is adhered, or compared to the method of adding by adhering, the simple addition and mixing as described above It is more preferable to supply the product to an extruder or the like because the reinforcing effect of the molded product is more excellent, and the method is preferably used together with the simplicity of operation.
It is also effective to supply the silane compound directly to the extruder separately from other components.

Further, the method of adding aluminum borate fiber or the like in the melt extrusion step while the resin component is being melted is a method in which the fibrous filler is less damaged and the effect of the present invention is sufficiently exhibited.

The material pellets obtained in this manner can be molded by a generally known thermoplastic resin molding method such as injection molding, extrusion molding, vacuum molding, compression molding, etc., and the most preferable is injection molding.

〔Example〕

Examples are shown below, but the present invention is not limited thereto.

Comparative Examples 1 to 9 As shown in Table 1, the liquid crystalline polyester (A) and the inorganic filler (B) were measured in a blender and mixed for 30 seconds.
Next, these mixtures were kneaded with an extruder at a cylinder temperature of 300 ° C. without adding the silane compound (C) to produce pellets of the resin composition. Using these pellets, ASTM at cylinder temperature 310 ° C, mold temperature 100 ° C with injection molding machine
Test specimens were molded and the mechanical properties shown in Table 1 were measured.

Using the same pellets, the melt viscosity was measured by a Capillograph 1B type device manufactured by Toyo Seiki Seisaku-sho, Ltd. The capillary uses 1mmφ × 10mmL, temperature 320 ° C, shear rate 1200 /
The value in sec was taken as the melt viscosity.

Using the same pellet, cylinder temperature 310 ° C, mold temperature 100 ° C, injection speed 1m / min, injection pressure 50
A flat plate of 80 mm × 80 mm × 2 mmt was formed with a side gate at 0 kg / cm ² , and the shrinkage ratio was calculated from the dimensions of the mold and the molded product.
The flow direction was defined as MD, and the direction perpendicular to the flow was defined as TD. The results are shown in Table 1.

(Note-1); Polymers A, B and C are liquid crystal polymers having the following structural units (Note-2); 1) Shikoku Chemical Industry Co., Ltd. (average fiber diameter 0.5 to 1μ)
m, average fiber length 10-30 μm) 2) Otsuka Chemical Co., Ltd. (average fiber diameter 0.5-1 μm, average fiber length 10-30 μm) 3) Asahi Fiber Glass Co., Ltd. (average fiber diameter about 10 μm)
m, average fiber length: about 3 mm) Examples 1 to 12, Comparative Examples 10 to 13 After the silane compound (C) shown in Table 2 was previously mixed with the liquid crystal polymer (A), the inorganic filler (B) was added, and the mixture was mixed with a blender. Mix for an additional 30 seconds. Next, this mixture was kneaded with an extruder having a cylinder temperature of 300 ° C. to form pellets of the resin composition.

Using the pellets, mechanical properties, melt viscosity, and shrinkage were measured in the same manner as described above. Table 2 shows the results. However, in Comparative Example 10, the silane compound (C) was previously placed in a dropping funnel as a dispersion mixture having a weight ratio of silane compound / ethyl alcohol / water = 1/9/1, and aluminum borate fiber (Henschel mixer) was used. B) The mixture was added dropwise to the mixture in 5 minutes, and the mixture was coated on the surface.
The surface-treated filler is dried at 105 ° C. for 10 hours, and the surface-treated filler is mixed with the liquid crystal polymer (A) in a blender for 30 seconds.

Examples 1 to 3 were obtained when the amount of the aluminum borate fiber (B) was changed. Examples 4 to 7 were obtained when the amount of the silane compound to the component (B) was changed. When the kind of the compound was changed, Examples 11 and 12 are cases where the kind of the liquid crystalline polymer was changed.

(Note-1); Same as Table 1 (Note-2); Same as Table 1 (Note-3); a) γ-glycidoxypropyltrimethoxysilane a ') manufactured by Nippon Unicar Co., Ltd. a') Aluminum borate previously B) γ-aminopropyltriethoxysilane manufactured by Nippon Unicar c) γ-mercaptopropyltrimethoxysilane manufactured by Nippon Unicar d) Vinyl manufactured by Nippon Unicar Trimethoxysilane The addition amount (parts by weight) is based on 100 parts by weight of the component (B). [Effect of the Invention] As apparent from the above description and Examples, the resin composition of the present invention and the production of the present invention The resin composition prepared by the method,
In particular, it has good fluidity, does not cause clogging of gates, does not cause insufficient filling, and has good dimensional stability, and is therefore suitable for precision molding, especially for thin or small precision molded products. Moreover, since it has excellent mechanical properties, it is most suitable for equipment parts requiring such properties. For example, it is a very suitable material for gears of watches and cameras, and can be mass-produced in place of conventional metal parts, thereby enabling cost reduction.

Claims (4)

(57) [Claims] (1) 95 to 30 parts by weight of a melt-processable polyester resin capable of forming an anisotropic molten phase; (B) 5 to 70 parts by weight of aluminum borate fiber; Separately from the presence or absence of the surface treatment agent of the component (B) and the other inorganic filler, one or more silane compounds of aminosilane, epoxysilane, vinylsilane and mercaptosilane are added to 100 parts by weight of aluminum borate fiber (B). The resin composition for precision molding is obtained by blending 0.05 to 5 parts by weight with respect to each other and melt-kneading. 2. An aluminum borate fiber as component (B),
The resin composition according to claim 1, wherein the average fiber length is 5 to 100 m and the average fiber diameter is 0.2 to 4.0 m. (3) In preparing the composition according to the above (1) or (2), the aluminum borate fiber (B) is supplied to an extruder in a simple mixed state without previously performing a surface treatment on the aluminum borate fiber (B) with the silane compound (C). , Melt kneading, a method for producing a resin composition. 4. The resin composition according to claim 1, wherein the silane compound (C) is directly supplied to an extruder separately from other components and melt-kneaded in preparing the composition according to claim 1 or 2. Production method.