JP3415346B2 - Injection molding method - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to injection molding of a thermoplastic resin composition comprising a thermoplastic resin (A) which does not form an anisotropic melt phase and a liquid crystalline polymer (B) which can form an anisotropic melt phase.
Regarding the shape method .

[0002]

2. Description of the Related Art Liquid crystalline polymers capable of forming an anisotropic molten phase have high strength, high rigidity,
Although it is a thermoplastic resin having many properties such as high heat resistance and easy moldability, it has a commercial disadvantage such as higher price because it has different molding shrinkage and mechanical properties in the direction perpendicular to the molecular chain orientation direction. On the other hand, thermoplastic resins using one or more of polyolefin-based (co) polymers, styrene-based (co) polymers, polyamide-based (co) polymers, polyacrylates and polyacetal (co) polymers are relatively It is inexpensive and has excellent slidability or impact characteristics, but it has the disadvantage of poor physical properties such as heat resistance and rigidity. Especially when used for thin-walled housings, the fluidity of the molten resin during production and the rigidity of the molded product are insufficient, so it is unavoidable to make it thick by design, so in the field of electric, electronic, communication equipment these days. There was a limit to the reduction in size and weight. Therefore, attempts have been made to utilize the advantages of the liquid crystalline polymer and the thermoplastic resin and to mix and use them in order to compensate for the drawbacks of both. JP-A-5-70700 and JP-A-5-700
As described in Japanese Patent No. 112709, first, the liquid crystalline polymer is extruded while stretching at a temperature at which both the liquid crystalline polymer and the thermoplastic resin are melted, so that the liquid crystalline polymer has a predetermined aspect ratio (length / thickness). When the molding material is prepared so that it exists in the form of large fibers, and the molding material is molded, the molding material is molded at a temperature at which only the thermoplastic resin is melted without melting the liquid crystalline polymer. A method for producing a molded article containing a fibrous liquid crystalline polymer having a reinforcing effect has been considered. However, in these methods, extruding while stretching in advance, further stretching the melt extrudate with a roller or the like to form a composition in which the liquid crystalline polymer is oriented in a fibrous state, and then molding by injection molding or the like. When a body is obtained, the body is molded at a molding temperature below the melting point of the liquid crystalline polymer. Alternatively, when a molded product is prepared from the beginning, a considerably large shearing force must be applied when the mold is filled with the resin composition to align the liquid crystalline polymer. Therefore, in the former case, the fluidity is deteriorated, the molding conditions are narrowed, and the rigidity is not sufficiently satisfactory. In the latter case, the shape of the molded product is considerably affected, and the strength is insufficient because the orientation is not sufficient depending on the place. Further, the melting point of the liquid crystalline polymer blended with the thermoplastic resin is too high, and the thermoplastic resin may be decomposed during processing, so that the inherent advantage of the thermoplastic resin has not been utilized.

[0003]

In view of the above problems, the inventors of the present invention have eagerly searched and studied for a material having excellent properties as a thin molding material, and found that the thermoplastic resin (A) and the liquid crystalline polymer By using (B) to specify the melt viscosity condition during the injection molding and using a liquid crystalline polymer having a relatively low flow initiation temperature in consideration of the melting point of the thermoplastic resin, the liquid crystalline polymer can be easily formed into a fiber. It has been found that a thin-walled molded product that exhibits a very high reinforcing effect that has not existed in the past, and therefore has a unique property of the molded product, can be a thin-walled molded product that is particularly excellent in mechanical strength. .

That is, the present invention relates to a heat treatment using one or two or more of polyolefin (co) polymers, styrene (co) polymers, polyamide (co) polymers, polyacrylates and polyacetal (co) polymers. Plastic resin (A) 99 to 50% by weight and liquid crystalline polymer (B) 1 to 5
The thermoplastic resin (A) under the processing temperature condition of a thermoplastic resin composition consisting of 0% by weight (total of 100% by weight of both)
Has a melt flow value of 0.15 to 100, a flow starting temperature of the liquid crystalline polymer (B) of 80 to 210 ° C.,
In addition, the viscosity ratio of the thermoplastic resin (A) and the liquid crystalline polymer (B) (Aη / when the shear rate is 1200 sec ⁻¹ at a processing temperature equal to or higher than the flow starting temperature of the liquid crystalline polymer (B).
A thermoplastic resin composition having a Bη) of 0.1 or more is injected at a processing temperature of the flow starting temperature of the liquid crystalline polymer (B) or more under the condition that the gate passage speed of the molten resin is in the range of 500 m / min or more. An injection molding method for molding is provided. Also,
In the above invention, there is provided an injection molding method using an injection molding die in which a ratio S _R / S _G of the cross-sectional area S _R of the runner to the cross-sectional area S _G of the gate is in the range of 3 to 150.

The thermoplastic resin (A) to which the present invention is applied is, for example, polyethylene, polypropylene or poly-4.
-Polyolefin (co) polymer such as methyl-1-pentene, ABS resin, styrene (co) polymer such as AES, AS, PS, polyamide (co) polymer, polyacrylate, polyacetal (co) polymer Examples thereof include a combination and a resin mainly containing these resins, and one kind or a mixture of two or more kinds may be used. The reason why these thermoplastic resins are preferable is that, for example, a polyolefin-based (co) polymer is very inexpensive and well balanced in physical properties, and a styrene-based (co) polymer has a small molding shrinkage ratio.
In addition, polyamide-based (co) polymers have relatively good heat resistance, and polyacetal-based (co) polymers have good sliding properties. Usually, such (co) polymers have a melting point. Alternatively, the softening point is 210 ° C. or lower. Further, these thermoplastic resins (A) will be described in detail.

The polyacetal resin used in the present invention is a polymer compound having an oxymethylene unit-(OCH ₂ )-as a main constitutional unit, a polyoxymethylene homopolymer or an oxymethylene group as a main repeating unit. Besides, other structural units such as ethylene oxide, 1,3-dioxolane, 1,4-butanediol,
It may be a copolymer, terpolymer or block polymer containing a small amount of comonomer units such as formal, and the molecule may have not only a linear structure but also a branched or crosslinked structure. Further, a known modified polyoxymethylene having another organic group introduced may be used. The degree of polymerization is not particularly limited, and those having moldability, for example, a melt flow (MFR) value under load of 190 ° C. and 2160 g of 0.15 to 100 g / 10 minutes, preferably 0.5 to It may be 50 g / 10 minutes.

The polyolefin (co) polymers used in the present invention include homopolymers of α-olefins such as ethylene, propylene, butene, hexene, octene, nonene, decene and dodecene, or two or more of these. Random, block, or graft copolymer, or 1,4-hexadiene, dicyclopentadiene, 5-ethylidene-2-norbornene, 2,
Non-conjugated dienes such as 5-norbonadiene, conjugated diene components such as butadiene, isoprene and piperylene, α, β-unsaturated acids such as acrylic acid and methacrylic acid or derivatives thereof such as esters, acrylonitrile, styrene and α-methylstyrene. , A vinyl ester such as vinyl acetate, a vinyl ether such as vinyl methyl ether, and a random, block, or graft copolymer containing one or more comonomer components such as derivatives of these vinyl compounds The degree of polymerization, the presence or absence of side chains or branches, the degree thereof, the composition ratio of the copolymer, and the like are irrelevant.

The styrene-based (co) polymer used in the present invention contains styrene as a main component, a radical polymerization reaction,
Alternatively, it can be obtained by an ionic polymerization reaction, and any of those industrially obtained by bulk polymerization, solution polymerization, suspension polymerization, emulsion polymerization or the like can be used. Further, styrene may be the main component and other reactive monomers such as vinyl compounds and diene compounds may be copolymerized or a rubber component may be introduced so long as the properties are not significantly impaired. In particular, polystyrene, poly-α-methylstyrene or mainly these, acrylic acid, methacrylic acid, or their esters, acrylonitrile, butadiene, copolymers with ethylene chloride and the like are also preferably used,
The degree of polymerization, the presence or absence of side chains or branches, the degree thereof, the composition ratio of the copolymer, and the like do not matter. Specifically, PS, HIPS, A
S, AES, ABS, MBS, etc. are mentioned.

The polyamide (co) polymer used in the present invention is a polyamide obtained from ω-amino acid or ω-lactam, or a diamine or m-xylenediamine and adipic acid, sebacic acid, dodecanedioic acid, cyclohexanedicarboxylic acid. Examples thereof include homopolymers or copolymers obtained from acids, dicarboxylic acids such as terephthalic acid and isophthalic acid, and further mixed polymers. Preferred polyamides include homopolyamides such as nylon 6, nylon 11, nylon 12, nylon 46, nylon 66, adipic acid / terephthalic acid / hexamethylenediamine, adipic acid / 1,4-cyclohexanedicarboxylic acid / hexamethylenediamine, Copolyamides such as adipic acid / 1,3-cyclohexanedicarboxylic acid / hexamethylenediamine, terephthalic acid / isophthalic acid / hexamethylenediamine / paraaminocyclohexylmethane and the like can be mentioned.

To the thermoplastic resin, additives such as a nucleating agent, a pigment such as carbon black, an antioxidant, a stabilizer, a plasticizer, a lubricant, a release agent and a flame retardant are added to obtain desired characteristics. A thermoplastic resin provided with is also included in the range of the thermoplastic resin of the present invention.

Liquid crystalline polymer (B) used in the present invention
Means a melt-processable polymer having a property of forming an optically anisotropic melt phase having a flow initiation temperature of 80 to 210 ° C. The properties of the anisotropic molten phase can be confirmed by a conventional polarization inspection method using a crossed polarizer. More specifically, the confirmation of the anisotropic molten phase can be performed by using a Leitz polarization microscope and observing the molten sample placed on the Leitz hot stage under a nitrogen atmosphere at a magnification of 40 times. The liquid crystalline polymer applicable to the present invention, when inspected between orthogonal polarizers, normally transmits polarized light even if it is in a molten stationary state, and exhibits optical anisotropy.

Examples of the above-mentioned liquid crystalline polymer (B) include aromatic polyester or aromatic polyesteramide, aromatic polyester or polyester partially containing the aromatic polyesteramide in the same molecular chain.

Liquid crystalline polymer (B) applicable to the present invention
The aromatic polyester or the aromatic polyester amide has as a constituent component at least one compound selected from the group consisting of aromatic hydroxycarboxylic acid, aromatic aminocarboxylic acid, aromatic hydroxyamine, and aromatic diamine. Aromatic polyesters and aromatic polyester amides. More specifically, (1) 1 mainly of aromatic hydroxycarboxylic acid and its derivative
One or two or more of (a) an aromatic hydroxycarboxylic acid and its derivative and (b) an aromatic dicarboxylic acid, an alicyclic dicarboxylic acid and its derivative Polyester comprising one or more kinds and (c) at least one kind or two or more kinds of aromatic diol, alicyclic diol, aliphatic diol and derivatives thereof; (3) mainly (a) aromatic hydroxy One or more carboxylic acids and their derivatives, (b) one or more aromatic hydroxyamines, aromatic diamines and their derivatives, and (c) aromatic dicarboxylic acids and alicyclic dicarboxylic acids. And one or more kinds of derivatives thereof, and (4) mainly (a) an aromatic hydroxycarboxylic acid,
One or more aromatic aminocarboxylic acids and their derivatives, (b) one or more aromatic hydroxyamines, aromatic diamines and their derivatives, and (c) aromatic dicarboxylic acids, alicyclics Examples include polyester amides comprising one or more kinds of group dicarboxylic acids and their derivatives, and (d) at least one kind or two or more kinds of aromatic diols, alicyclic diols, aliphatic diols and their derivatives. To be Further, if necessary, a molecular weight modifier may be used in combination with the above constituent components. When these are dissolved in pentafluorophenol at a concentration of 0.1% by weight at 60 ° C., 0.5 or more, preferably 2.0 to 10.0 dl / g
Those having a logarithmic viscosity (IV) of 1 are used and may include an oligomer region.

Specific examples of the compound constituting the liquid crystal polymer (B) applicable to the present invention include aromatic hydroxycarboxylic acids such as p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid, and aminobenzoic acid. Aromatic aminocarboxylic acids such as acids, 2,6-dihydroxynaphthalene, 1,4-dihydroxynaphthalene, 4,4′-dihydroxybiphenyl, hydroquinone, resorcin, the following general formula [1] and the following general formula [2] Aromatic diols such as compounds to be treated; ethylene glycol, 1,4-
Aliphatic glycols typified by butanediol; terephthalic acid, isophthalic acid, 4,4'-diphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and aromatic dicarboxylic acids such as compounds represented by the following general formula [3] acid;
Examples thereof include aromatic amines such as p-aminophenol and p-phenylenediamine.

[0015]

[Chemical 1]

A particularly preferred liquid crystal polymer (B) to which the present invention is applied is an aromatic polyester having an aromatic hydroxycarboxylic acid and ethylene glycol or terephthalic acid as a constitutional unit from the viewpoint of a flow initiation temperature of 80 to 210 ° C. is there. In this case, the content of the aromatic hydroxycarboxylic acid is 30 to 70 mol%, preferably 35 to 55 mol%, and particularly preferably 40 to 45 mol%. Furthermore, the aromatic hydroxycarboxylic acid is preferably p-hydroxybenzoic acid, or a mixed constitution of p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid.
In the latter case, in particular, p-hydroxybenzoic acid and 6-
The ratio of hydroxy-2-naphthoic acid is 50:50 to 7
0:30 is preferable, and the ratio is particularly 55: 45-6.
5:35 is preferable. Liquid crystalline polymer (B) of the present invention
The degree of polymerization of the substance obtained by any of the above compositions may include an oligomer region.

The thermoplastic resin composition used in the injection molding method of the present invention comprises the thermoplastic resin (A) and the liquid crystalline polymer (B). Regarding the composition ratio of the thermoplastic resin (A) and the liquid crystalline polymer (B), the former is 99 to 50% by weight, preferably 95 to 60% by weight,
The latter is 1 to 50% by weight, preferably 5 to 40% by weight (the total of both is 100% by weight). When the composition ratio of the liquid crystalline polymer (B) is in the range of 1 to 50% by weight, the matrix phase is not inverted, and the thermoplastic resin (A) can be reinforced by the liquid crystalline polymer (B). . Further, when the composition is heat-treated under a temperature condition not lower than the melting point of the liquid crystalline polymer and cooled to room temperature without any load, and the obtained composition is observed, the liquid crystalline polymer (B) is a thermoplastic resin ( It is necessary that the matrix phase of A) is microdispersed in an island shape. Then, the dispersion state of the liquid crystalline polymer (B) has a weight average particle diameter of 10 to 4
Range of 0μm, that particularly in the range of 15~30μm
It is preferable that 80% by weight or more of the liquid crystalline polymer (B) is in the range of 0.5 to 60 μm, particularly 5 to 50 μm. The heat treatment is a means for making the liquid crystalline polymer (B) into a spherical shape that is easy to observe even if the liquid crystalline polymer (B) is dispersed in a shape other than a spherical shape. However, in order to completely melt and spheroidize the liquid crystalline polymer, it is preferable to leave it at a temperature higher than the melting point by 10 ° C. or more and for 20 seconds or more, particularly 30 seconds to 3 minutes. When the dispersion having a shape other than the spherical shape remains, the heat treatment time may be extended, but when the heat treatment time becomes longer, it may be melted depending on the combination of the thermoplastic resin (A) and the liquid crystalline polymer (B). Since the spherical liquid crystalline polymer (B) may agglomerate and change its microdispersion state, it is preferable to use a particle size converted into a spherical shape without extending the heat treatment time.

To produce a thermoplastic resin composition in which the liquid crystalline polymer (B) is micro-dispersed in an island shape in the matrix phase of the thermoplastic resin (A) when cooled through the above heat treatment, Both may be blended in the above composition ratio and kneaded. Usually, the mixture is kneaded by an extruder, extruded into pellets and used for the next injection molding, but the kneading by such an extruder is not limited. As the kneading method,
A single-screw or twin-screw extruder used for kneading and extruding a usual thermoplastic resin is used. In order to obtain the above-mentioned dispersed thermoplastic resin composition, (1) flow of the liquid crystalline polymer (B) is used. Processing temperature above the starting temperature, shear rate 1200 sec ^-1
The melt viscosity ratio (Aη / Bη) of the thermoplastic resin (A) and the liquid crystalline polymer (B) measured by
Preferably, there are a method of 0.1 to 6 or less, (2) a method of repeating kneading and extrusion, (3) a method of finely granulating the liquid crystalline polymer (B) to be blended, etc. Two types of methods can be used together. this
Among them, in the injection molding method of the present invention , the melt viscosity ratio (Aη / Bη) is set to 0.1 or more from the viewpoint of easily obtaining the above-mentioned microdispersed thermoplastic resin composition. When the melt viscosity is 0.1 or less, the viscosity of the matrix (thermoplastic resin) phase is too low, sufficient shear stress and extension stress are not applied to the liquid crystalline polymer (B), and the liquid crystalline polymer is difficult to be fiberized. When the viscosity ratio exceeds 6, the liquid crystalline polymer (B) is fibrillated, but since the viscosity of the thermoplastic resin (A) is increased, the fiber diameter of the fibrillated liquid crystalline polymer is increased, and the reinforcing effect is increased. May be unfavorable and may cause problems such as poor fluidity during molding. The flow initiation temperature of the liquid crystalline polymer (B) is a temperature at which the liquid crystalline polymer (B) exhibits fluidity by an external force when the liquid crystalline polymer (B) is heated and heated, and is measured by the method described below.

In order to produce the thermoplastic resin composition as described above, both may be blended in the above composition ratio and kneaded.
Usually, the mixture is kneaded by an extruder, extruded into pellets, and used for injection molding or the like, but the kneading by such an extruder is not limited.

In the thermoplastic resin composition according to the present invention, it is necessary that the liquid crystalline polymer (B) is micro-dispersed to the extent as described above when it is cooled through heat treatment. The liquid crystalline polymer (B) may be fiberized in the composition as disclosed in JP-A-5-112709 and JP-A-5-70700, but such fiberization is possible. Is not necessary.
Therefore, it is not necessary to form oriented fibers by stretching the roll, which is performed at the time of melting after the extruder as described in the above publication. In the present invention, the thermoplastic resin composition in which the liquid crystalline polymer (B) is in the above-mentioned dispersed state is injection-molded under the conditions described below, so that the particles of each microdispersed liquid crystalline polymer (B) can be easily Since fibers are formed in a state where the ratio is large, fibers are uniformly formed inside the injection-molded body, and the strength is easily higher than that of the molded body obtained by a known method with the composition ratio of the same liquid crystalline polymer (B). High rigidity will be exhibited.

The injection molding method of the present invention uses the thermoplastic resin composition in which the liquid crystalline polymer (B) is micro-dispersed in the matrix phase of the thermoplastic resin (A) as described above.
Adopting the injection molding conditions described below is a feature of the injection molding method according to the present invention. The first injection molding condition is the temperature (processing temperature) of the thermoplastic resin composition at the time of injection.
Is above the flow initiation temperature of the liquid crystalline polymer (B), preferably above the flow initiation temperature by 10 ° C. Due to this temperature condition, when the thermoplastic resin composition in a fluidized state passes through the gate leading to the mold cavity of the injection molding machine at the time of injection molding, the liquid crystalline polymer (B) micro-dispersed in an island shape is heated. It is stretched in the matrix phase of the plastic resin (A) and sufficiently fiberized. That is, this fiberization makes it possible to obtain an injection-molded article having a sufficiently high function in the dispersed state and having high rigidity and high strength.
When the liquid crystalline polymer (B) dispersed in an island shape is not micro-dispersed, the number of the liquid crystalline polymer (B) formed into fibers becomes small and an injection molded article having high rigidity and high strength can be obtained. In some cases, it is an important requirement that the liquid crystalline polymer (B) be micro-dispersed in an island shape. From the viewpoint of saving energy and preventing thermal decomposition of the thermoplastic resin composition, the upper limit of the resin temperature is preferably not higher than the thermal decomposition temperature of the liquid crystalline polymer (B), particularly preferably the melting point of the liquid crystalline polymer (B) plus 50 ° C. Keep below. The processing temperature in the present invention is a set temperature of a resin processing machine such as a molding machine. However, even if the set temperature is equal to or lower than the liquid crystal start temperature, the present invention includes as long as the resin temperature is equal to or higher than the liquid crystal start temperature.

The second injection molding condition is the speed of the molten thermoplastic resin composition passing through the gate. The passing speed of this gate is 500 m / min or more, preferably 1,000
m / min or more, more preferably 3,000 m / min or more. By satisfying this condition and performing injection molding, in combination with the temperature condition, the fiberization of the liquid crystalline polymer (B) by the stretching during the passage can be sufficiently achieved.
The higher the passage speed of the gate is, the more preferable. However, the upper limit is preferably 100,000 m / min or less in view of the performance of an ordinary molding machine.
It is also possible to use 50,000 m / min or more.

As a mold used for the injection molding, the ratio S _R / S _G of the cross-sectional area S _R of the runner to the cross-sectional area S _G of the gate is in the range of 3 to 150, particularly 6 to 120. That promotes fiberization of the liquid crystalline polymer (B),
It is particularly preferable because the aspect ratio of the fibers generated in the matrix phase can be increased. The gate and runner cross-sectional areas are defined as shown in FIG. 1 depending on the type of gate. A gate having a shape not shown in the figure can be similarly defined. In the case of the side gate and film gate of FIG. 1A and the overlap gate of FIG. 1B, S _G = S _Y when S _X > S _Y and S _X <S _Y
, S _G = S _X , and S _X = S _Y , S _G = S _X =
It is S _Y. In the case of the pin gate of FIG. 1C, S _R = S _X when the cross-sectional area S _X > S _Y and S when S _X <S _{Y.
When R} = S _Y and S _X = S _Y , S _R = S _X = S _Y. In the case of the direct gate shown in FIG. 1D, the area of the conical bottom surface of the conical runner is S _R, and the area of the virtual outer peripheral surface of the cylinder formed immediately below the conical bottom surface is S _G. Further, in the case of the disc gate of FIG. 1E, the area of the conical bottom surface in the figure is S _R , and similarly to the case of the direct gate, the area of the outer peripheral surface of the virtual cylinder formed in the gate in the figure is S S.
_{Let G.}

The resin pressure at the time of injection molding is appropriately set so as to satisfy the velocity condition of the molten thermoplastic resin composition passing through the gate, but it is usually 300 to 2,000 Kg / c.
m ² , preferably in the range of 500 to 1,500 Kg / cm ² .

The thermoplastic resin composition, that is, one or more kinds of polyolefin-based (co) polymers, styrene-based (co) polymers, polyamide-based (co) polymers, polyacrylates, polyacetal (co) polymers. The used thermoplastic resin (A) 99 to 50% by weight and the liquid crystalline polymer (B)
The thermoplastic resin (A) has a melt flow value of 0.15 to 100 under processing temperature conditions of a thermoplastic resin composition composed of 1 to 50% by weight (total of 100% by weight of both), and the liquid crystalline polymer is The flow starting temperature of (B) is 80 to 210.
Viscosity ratio (Aη / Bη) between the thermoplastic resin (A) and the liquid crystalline polymer (B) at a shearing rate of 1200 sec ⁻¹ at a processing temperature higher than the flow starting temperature of the liquid crystalline polymer (B). The thermoplastic resin composition having a value of 0.1 or more
At a processing temperature above the flow initiation temperature of the liquid crystalline polymer (B)
The molten resin passing through the gate at a speed of 500 m / min or more.
The injection-molded body obtained by injection molding under the conditions of being enclosed is
The liquid crystalline polymer (B) is fibrous and has an average aspect ratio of 6 or more, preferably 8 or more and is dispersed in the matrix phase of the thermoplastic resin (A). Further, the fibrous liquid crystalline polymer (B) is relaxed by heating the molded product dispersed in the fibrous state under no load under a temperature condition of the melting point of the liquid crystalline polymer (B) or higher, and cooled to room temperature. When the liquid crystalline polymer (B) has a weight average particle size of 10 to 40 μm and 80% by weight or more of the liquid crystalline polymer (B) has a particle size of 0.5 to 60 μm, the matrix phase of the thermoplastic resin (A) is A major feature is that the islands are micro-dispersed. The heat treatment temperature and the holding time in this case are the same as in the case of the thermoplastic resin composition of the present invention. Liquid crystalline polymer (B) observed when the above-described thermoplastic resin composition according to the present invention is cooled without heat treatment under a temperature condition higher than the melting point of the liquid crystalline polymer (B). Since the dispersion state itself does not substantially change even when it is re-kneaded and passed through the gate under the injection molding conditions, the injection molded article is heated as described above to change the dispersion state of the liquid crystalline polymer (B). By observing, it can be easily discriminated that it is an injection-molded article according to the present invention and whether or not the above-mentioned thermoplastic resin composition is used as a raw material thereof.

Thus obtained by the injection molding method of the present invention
The injection molded article is a liquid crystalline polymer (B) contained in it.
Since it has a reinforcing effect by being included in a fibrous form, a filler usually added for reinforcement is not necessary, but depending on the application, within a range that does not impair the effects of the present invention, a known fibrous form, powdery form Alternatively, a plate-shaped or hollow filler may be blended.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited thereto. The method for evaluating the injection-molded article is as follows.

(Melt Flow Value) The melt flow value (g / 10 minutes) at the processing temperature was measured according to ASTM D1238-89E.

(Fluid Start Temperature) Using a capillary rheometer (Flow tester CFT-500 manufactured by Shimadzu Corporation), 100 Kg / cm ^{2 of} a sample resin heated and melted at a temperature rising rate of 4 ° C./min.
When extruded from a nozzle having an inner diameter of 1 mm and a length of 10 mm under load, the melt viscosity was expressed as a temperature showing 48,000 poise.

(Flexural Modulus) According to ASTM D790, the flexural modulus (Kg / cm ² ) of a bending test piece having a thickness of 1/32 inch was measured.

(Average Aspect Ratio of Fibrous Liquid Crystalline Polymer) The test piece used in the measurement of flexural modulus was cut so that a plane parallel to the flow direction would appear, and the cross section was mirror-polished. It was observed and evaluated by. The thickness and length of 50 arbitrarily selected fibrous liquid crystalline polymers were measured. Regarding the length, the length of the portion that can be observed on the surface was defined as the length of the fiber. The results are shown by ◯ when the average aspect ratio is 8 or more, Δ when the average aspect ratio is 8 to 6, and x when the average aspect ratio is less than 6.

(Dispersion Particle Diameter of Liquid Crystalline Polymer (B)) A pellet after melt-kneading or a part of a test piece after molding is heated to a temperature higher than the melting point of the liquid crystalline polymer by 10 ° C. in a nitrogen stream for 3 minutes It was kept at that temperature and then cooled to room temperature. The cut surface of the sample after heat treatment and cooling was observed by an electron microscope and evaluated. The diameter of 50 particles of the liquid crystalline polymer arbitrarily selected was measured, and the weight average particle diameter was obtained.

(Melt Viscosity) The pellet or powder of each resin was measured for melt viscosity under a shearing stress of 1200 sec ⁻¹ at a processing temperature of each thermoplastic resin composition using a Capillograph manufactured by Toyo Seiki.

(Vicat softening point) It was measured according to JIS K6870.

(Example 1) Polyacetal resin (manufactured by Polyplastics Co., Ltd., M
25-44 (MI = 2.5), melting point 165 ° C. and liquid crystalline polyester (manufactured by Unitika Ltd., Rod Run LC30)
A resin having a mixing ratio of 7: 3 with 00) was blended, melt-kneaded at a resin temperature of 190 ° C. with a 30 mm twin-screw extruder, and pelletized. Then, the pellets were molded into a test piece at a molding temperature of 190 ° C. with an injection molding machine (side gate), and the mechanical properties, melt viscosity, and average aspect ratio of the liquid crystalline polyester were evaluated. The results are shown in Table-1. In addition, the dispersed particle diameter of the liquid crystalline polyester of the pellets before being melted without load is 25 (μm) on a weight average, and 80% by weight or more of the dispersed particles have a particle diameter of 5 to 45 (μm). Was in range. The molding conditions are as follows. (1) Runner cross-sectional area S _R / gate cross-sectional area S _G : 9.3 (2) Gate passing speed: 1200 (m / min) (3) Injection pressure: 800 (Kg / cm ² ) (4) Injection speed: 5.8 (m / min)

(Example 2) Polyacetal resin (manufactured by Polyplastics Co., Ltd., M
90-44 (MI = 9.0), melting point 165 ° C. and liquid crystalline polyester (manufactured by Unitika Ltd., Rod Run LC30)
A resin having a mixing ratio of 7: 3 with 00) was blended, melt-kneaded at a resin temperature of 190 ° C. with a 30 mm twin-screw extruder, and pelletized. Then, the pellets were molded into a test piece at a molding temperature of 190 ° C. with an injection molding machine (side gate), and the mechanical properties, melt viscosity, and average aspect ratio of the liquid crystalline polyester were evaluated. The results are shown in Table-1. In addition, the dispersed particle diameter of the liquid crystalline polyester obtained by melting the pellets before molding with no load is 30 (μm) on a weight average, and 80% by weight or more of the dispersed particles have a particle diameter of 5 to 45 (μm). Was in range. The molding conditions are as follows. (1) Runner cross-sectional area S _R / gate cross-sectional area S _G : 9.3 (2) Gate passing speed: 1200 (m / min) (3) Injection pressure: 800 (Kg / cm ² ) (4) Injection speed: 5.8 (m / min)

(Example 3) Polyacetal resin (manufactured by Polyplastics Co., Ltd., M
90-44 (MI = 9.0), melting point 165 ° C. and liquid crystalline polyester (manufactured by Unitika Ltd., Rod Run LC30)
A resin having a mixing ratio of 7: 3 with 00) was blended, melt-kneaded at a resin temperature of 190 ° C. with a 30 mm twin-screw extruder, and pelletized. Next, the pellets were molded into a test piece at a molding temperature of 190 ° C. with an injection molding machine (pin gate), and the mechanical properties, melt viscosity, and average aspect ratio of the liquid crystalline polyester were evaluated. The results are shown in Table-1. In addition, the dispersed particle diameter of the liquid crystalline polyester obtained by melting the pellets before molding with no load is 30 (μm) on a weight average, and 80% by weight or more of the dispersed particles have a particle diameter of 5 to 45 (μm). Was in range. The molding conditions are as follows. (1) Runner cross-sectional area S _R / gate cross-sectional area S _G : 25 (2) Gate passing speed: 2850 (m / min) (3) Injection pressure: 1200 (Kg / cm ² ) (4) Injection speed: 5. 8 (m / min)

(Example 4) Polyacetal resin (manufactured by Polyplastics Co., Ltd., M
270-44 (MI = 27.0), melting point 165 [deg.] C. and liquid crystalline polyester (manufactured by Unitika Ltd., Rod Run LC)
30) with a resin with a mixing ratio of 7: 3
The resin was melt-kneaded at a resin temperature of 190 ° C. in a twin-screw extruder of m to pelletize. Then, the pellets were molded into a test piece at a molding temperature of 190 ° C. with an injection molding machine (side gate), and the mechanical properties, melt viscosity, and average aspect ratio of the liquid crystalline polyester were evaluated. The results are shown in Table-1. In addition, the dispersed particle diameter of the liquid crystalline polyester obtained by melting the pellets before molding with no load is 30 (μm) on a weight average, and 80% by weight or more of the dispersed particles have a particle diameter of 5 to 45 (μm). Was in range. The molding conditions are as follows. (1) Runner cross-sectional area S _R / gate cross-sectional area S _G : 9.3 (2) Gate passing speed: 1200 (m / min) (3) Injection pressure: 800 (Kg / cm ² ) (4) Injection speed: 5.8 (m / min)

Comparative Example 1 Polyacetal resin (manufactured by Polyplastics Co., Ltd., M
90-44 (MI = 9.0), melting point 165 [deg.] C., and liquid crystalline polyester (Vectra A950 manufactured by Polyplastics Co., Ltd.) powder were mixed with a resin having a mixing ratio of 7: 3, and a 30 mm biaxial The resin was melt-kneaded with an extruder at a resin temperature of 190 ° C. and pelletized. Then, the pellets were molded into a test piece at a molding temperature of 190 ° C. with an injection molding machine (side gate), and the mechanical properties, melt viscosity, and average aspect ratio of the liquid crystalline polyester were evaluated. The results are shown in Table-1. The dispersed particle size of the liquid crystalline polyester of the pellets before molding (observed without heat treatment) was complex and inconstant and could not be evaluated. The molding conditions are as follows. (1) Runner cross-sectional area S _R / gate cross-sectional area S _G : 9.3 (2) Gate passing speed: 1200 (m / min) (3) Injection pressure: 800 (Kg / cm ² ) (4) Injection speed: 5.8 (m / min)

Example 5 Polypropylene resin (manufactured by Mitsui Petrochemical Co., Ltd., Hipol J600 (MI = 7.0), melting point 160 ° C.) and liquid crystalline polyester (manufactured by Unitika Ltd., Rod Run LC)
30) with a resin with a mixing ratio of 7: 3
The resin was melt-kneaded at a resin temperature of 230 ° C. and pelletized by a twin-screw extruder of m. Then, the pellets were molded into a test piece at a molding temperature of 230 ° C. by an injection molding machine (side gate), and the mechanical properties, melt viscosity, and average aspect ratio of the liquid crystalline polyester were evaluated. The results are shown in Table-1. In addition, the dispersed particle diameter of the liquid crystalline polyester of the pellets before being melted without load is 25 (μm) on a weight average, and 80% by weight or more of the dispersed particles have a particle diameter of 5 to 45 (μm). Was in range. The molding conditions are as follows. (1) Runner cross-sectional area S _R / gate cross-sectional area S _G : 9.3 (2) Gate passing speed: 1200 (m / min) (3) Injection pressure: 800 (Kg / cm ² ) (4) Injection speed: 5.8 (m / min)

Example 6 Polypropylene resin (manufactured by Mitsui Petrochemical Co., Ltd., Hipol J900 (MI = 40.0), melting point 160 ° C.) and liquid crystalline polyester (manufactured by Unitika Co., Ltd., Rod Run L)
C3000) with a resin having a mixing ratio of 7: 3,
mm twin screw extruder, melt kneading at a resin temperature of 230 ° C,
Pelletized. Then, the pellets are molded into a test piece at a molding temperature of 230 ° C. by an injection molding machine (side gate),
The mechanical properties, melt viscosity, and average aspect ratio of the liquid crystalline polyester were evaluated. The results are shown in Table-1. In addition, the dispersed particle diameter of the liquid crystalline polyester obtained by melting the pellets before molding with no load is 30 (μm) on a weight average,
80% by weight or more of the dispersed particles have a particle size of 5 to 45 (μm)
Was in the range. The molding conditions are as follows. (1) Runner cross-sectional area S _R / gate cross-sectional area S _G : 9.3 (2) Gate passing speed: 1200 (m / min) (3) Injection pressure: 800 (Kg / cm ² ) (4) Injection speed: 5.8 (m / min)

Example 7 Polystyrene resin (manufactured by Mitsui Toatsu Chemicals, Inc., Topolex 500 (MI = 4.0), Vicat softening point 86 ° C.)
And a liquid crystalline polyester (Rod Run LC3000 manufactured by Unitika Ltd.) were mixed with a resin having a mixing ratio of 7: 3, and 3
The mixture was melt-kneaded at a resin temperature of 190 ° C. with a 0 mm twin-screw extruder and pelletized. Then, the pellets were molded into a test piece at a molding temperature of 190 ° C. with an injection molding machine (side gate), and the mechanical properties, melt viscosity, and average aspect ratio of the liquid crystalline polyester were evaluated. The results are shown in Table-1. In addition,
The average particle diameter of the dispersed particles of the liquid crystalline polyester, which was obtained by melting the pellets before molding without load, was 25 (μm), and 80% by weight or more of the dispersed particles had a particle diameter of 5 to 45 (μm).
m). The molding conditions are as follows. (1) Runner cross-sectional area S _R / gate cross-sectional area S _G : 9.3 (2) Gate passing speed: 1200 (m / min) (3) Injection pressure: 800 (Kg / cm ² ) (4) Injection speed: 5.8 (m / min)

Example 8 Polyamide resin (UBE Nylon 6 manufactured by Ube Industries, Ltd.)
(1013B), melting point 210 ° C) and liquid crystalline polyester (Rod Run LC3000 manufactured by Unitika Ltd.) were mixed in a resin with a mixing ratio of 7: 3, and melted at a resin temperature of 230 ° C with a 30 mm twin-screw extruder. Kneaded and pelletized. Then, the pellets were molded into a test piece at a molding temperature of 230 ° C. by an injection molding machine (side gate), and the mechanical properties, melt viscosity, and average aspect ratio of the liquid crystalline polyester were evaluated. The results are shown in Table-1. In addition, the dispersed particle diameter of the liquid crystalline polyester obtained by melting the pellets before molding with no load was 30 (μm) on a weight average, and the dispersed particle diameter was 8
0% by weight or more was in the range of particle diameter 5 to 45 (μm).
The molding conditions are as follows. (1) Runner cross-sectional area S _R / gate cross-sectional area S _G : 9.3 (2) Gate passing speed: 1200 (m / min) (3) Injection pressure: 800 (Kg / cm ² ) (4) Injection speed: 5.8 (m / min)

[0044]

[Table 1]

[0045]

As described above in detail, the present invention
By the injection molding method , it has become possible to obtain a thermoplastic resin molded product containing dispersed fibrous liquid crystalline polymer, which has not been obtained by the same technique in the related art. Since this molded product has the characteristics of extremely high rigidity and high strength, it is particularly preferably applied to a thin-walled molded product.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a cross-sectional area of a gate and a runner.

─────────────────────────────────────────────────── --- Continuation of the front page (56) References JP-A-2-263849 (JP, A) JP-A-5-70700 (JP, A) JP-A-7-188569 (JP, A) JP-A-6- 64653 (JP, A) JP 5-309692 (JP, A) JP 4-28768 (JP, A) JP 1-304136 (JP, A) JP 1-301750 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C08L 1/00-101/16 B29C 45/00-45/76

Claims (2)

(57) [Claims] 1. A thermoplastic resin containing one or more of a polyolefin-based (co) polymer, a styrene-based (co) polymer, a polyamide-based (co) polymer, a polyacrylate, and a polyacetal (co) polymer ( A) 99 to 50% by weight and liquid crystalline polymer (B) 1 to 50% by weight (both total 10
(0% by weight), the thermoplastic resin (A) has a melt flow value of 0.1 under the processing temperature conditions of the thermoplastic resin composition.
5 to 100, the flow starting temperature of the liquid crystalline polymer (B) is 80 to 210 ° C., and the shear rate is 12 at a processing temperature higher than the flow starting temperature of the liquid crystalline polymer (B).
When the thermoplastic resin composition having a viscosity ratio (Aη / Bη) of the thermoplastic resin (A) and the liquid crystalline polymer (B) at 00 sec ⁻¹ is 0.1 or more, the flow starting temperature of the liquid crystalline polymer (B) is changed. At the above processing temperatures, the molten resin passes through the gate at a speed of 5
An injection molding method for a thermoplastic resin composition, which comprises performing injection molding under the condition of a range of 00 m / min or more. 2. A mold for injection molding having a ratio S _R / S _G of the cross-sectional area S _R of the runner to the cross-sectional area S _{G of the} gate in the range of 3 to 150 is used. Injection molding method of thermoplastic resin composition.