KR101817359B1 - Wholly aromatic liquid crystalline polymer resin compound with enhanced strength and electronic compartments made from the same - Google Patents

Abstract

The present invention provides a wholly aromatic liquid crystal polymer resin composition containing carbon fibers, which has improved mechanical strength and does not deteriorate in heat resistance and fluidity. When the carbon fiber included in the composition is contained in a range of 2 to 100 parts by weight based on 100 parts by weight of the wholly aromatic liquid crystalline polymer resin as a material having high strength, heat resistance and light weight, the physical properties of the resin composition of the present invention are achieved.
The wholly aromatic liquid crystal polymer resin composition of the present invention can be used in the manufacture of various electronic devices which are vulnerable to external impact. Particularly, the present invention can be suitably used as a material for a connector or a memory card socket which is required to be manufactured in a small size in accordance with the trend of light weight.

Description

TECHNICAL FIELD [0001] The present invention relates to a wholly aromatic liquid crystalline polymer resin composition having a high strength and an electronic product made therefrom.

The present invention relates to a wholly aromatic liquid crystal polymer resin composition having high strength properties. Further, the present invention relates to an electronic device manufactured from the resin composition.

The wholly aromatic liquid crystal polymer resin is excellent in heat resistance and dimensional stability and has excellent fluidity when melted, and is widely used as a precision injection molding material mainly in the field of electronic parts.

Such a wholly aromatic liquid crystal polymer resin is a kind of thermoplastic polymer produced by condensation polymerization and is produced in the form of a composition by kneading with an inorganic filler such as glass fiber or talc and extrusion processing. The resin composition thus prepared is processed into an article through an injection process.

In particular, the wholly aromatic liquid crystal polymer resin composition reinforced with various organic / inorganic fillers has high heat resistance and excellent dimensional stability, electrical insulation and mechanical properties, so that it can be used as a connector for electronic products and other memory card socket, And its use is expanding.

Connectors and other memory card socket products of electronic products are required to be made thinner in structure, and particularly, in the case of connectors and memory card socket products, it is required to be made thinner and smaller in accordance with the trend of miniaturization of electronic products in recent years. Such thin and small connector and socket products may be broken or deformed when external force or impact is applied. Therefore, the resin composition used for molding a product such as a connector or a socket is required to be developed as a material having an improved strength so as not to be cracked or deformed by an external impact.

 On the other hand, when the degree of polymerization is increased in the polymerization process of the wholly aromatic liquid-crystalline polymer resin, which is the main material of the resin composition, in order to produce a resin composition sufficiently satisfying the mechanical properties so that the shape of the product is not deformed or damaged by external force, The fluidity of the resin generally decreases to make molding difficult, and the elasticity of the resin deteriorates, resulting in a problem that the molded article is easily broken.

Therefore, development of a wholly aromatic liquid crystal polymer resin composition having high strength properties without lowering the other physical properties of the resin composition including fluidity is required.

The present invention relates to a wholly aromatic liquid crystal polymer resin composition for use as a component material for connectors and memory card sockets, which comprises a wholly aromatic liquid crystal polymer resin composition having high strength in terms of mechanical properties and excellent in heat resistance, The purpose is to provide.

It is another object of the present invention to provide an electronic product having a property of being resistant to an external impact produced from the resin composition.

The present invention provides a wholly aromatic liquid-crystalline polymer resin composition comprising 2 to 100 parts by weight of carbon fibers per 100 parts by weight of a wholly aromatic liquid-crystalline polymer resin having a melting point of 300 to 450 ° C.

Preferably, the carbon fibers are acrylic carbon fiber, rayon carbon fiber, lignin carbon fiber or pitch carbon fiber.

Preferably, the wholly aromatic liquid crystal polymer resin is at least one aromatic compound selected from the group consisting of an aromatic diol, an aromatic diamine, an aromatic hydroxyamine, an aromatic dicarboxylic acid, an aromatic hydroxycarboxylic acid and an aromatic aminocarboxylic acid Which is synthesized from the condensation polymerization of a compound monomer.

Preferably, the aromatic compound includes a form in which substituted or unsubstituted phenylene, biphenylene, naphthalene or two phenylene are connected to each other by a carbon or non-carbon element.

Preferably, the resin composition comprises at least one inorganic filler selected from the group consisting of glass fiber, talc, mica, calcium carbonate and clay.

Preferably, the inorganic filler is contained in an amount of 3 to 900 parts by weight based on 100 parts by weight of the wholly aromatic liquid crystal polymer resin.

The present invention provides an electronic device element which is manufactured from the wholly aromatic liquid crystal polymer resin composition.

Preferably, the electronic device is a connector or a memory card socket.

The resin composition of the present invention comprising a wholly aromatic liquid crystal polymer resin having a melting point of melting and carbon fibers has high strength properties without deterioration in fluidity and heat resistance. Therefore, the composition of the present invention can be suitably used for forming a small-sized connector and a memory card socket according to a thin structure vulnerable to an external impact, and in particular, a miniaturization tendency of a product.

The present invention relates to a wholly aromatic liquid crystalline polymer resin composition having improved mechanical strength and at the same time maintaining the same level of heat resistance and fluidity as conventional ones. The present invention provides a wholly aromatic liquid crystalline polymer resin composition comprising a wholly aromatic liquid crystalline polymer resin having a melting point of 300 to 450 캜, Wherein the liquid crystal polymer resin composition is a liquid crystal polymer.

Specifically, the resin composition contains 2 to 100 parts by weight of carbon fibers per 100 parts by weight of the wholly aromatic liquid crystal polymer resin.

The wholly aromatic liquid crystal polymer resin used in the resin composition of the present invention has a melting point of 300 to 450 ° C because it is a resin having a high melting point and thus the resin composition of the present invention produced therefrom has excellent heat resistance.

In the present invention, the use of a resin having a high melting point of 300 ° C or higher as described above is preferable because the fluidity is too high in a high-temperature processing region of 330 ° C or higher for electronic product molding when the melting point is less than 300 ° C, If the melting point exceeds 450 ° C, it is difficult to have sufficient fluidity in the high-temperature machining area and the machining becomes difficult.

In the present invention, a carbon fiber is mixed with a resin in order to provide a resin composition with improved mechanical properties. The carbon fibers usable in the present invention include acrylic carbon fiber, rayon carbon fiber, lignin carbon fiber, And the like can be used in the present invention. Among them, acrylic carbon fiber is preferable because it has the highest level of rigidity and light weight.

The acrylic-based carbon fiber is produced by spinning a spinning liquid containing a PAN-based polymer as a precursor thereof by a wet spinning method, a dry spinning method or a dry wet spinning method to obtain a precursor fiber and then heating it in an oxidizing atmosphere at a temperature of 200 to 400 ° C Converted into chlorinated fibers, and carbonized by heating in an inert atmosphere at a temperature of at least 1000 캜.

The carbon fibers used in the present invention can be in any form, for example in the form of chopped strand roughened yarns or fabrics.

Various methods can be used for mixing the carbon fiber with the wholly aromatic liquid crystal polymer resin. For example, mixing can be accomplished by supplying chopped strand carbon fiber having a length of 3 to 6 mm and a wholly aromatic liquid crystal polymer resin separately to a melt extruder and then mixing them together. Alternatively, they may be premixed in a mixer such as a mixer or ribbon blender before being fed to a melt extruder. As another method, the dried carbon fibers may be directly supplied to a melt extruder to be mixed with the wholly aromatic liquid crystal polymer resin. Therefore, there is no limitation in the order and method of mixing the two components as long as the mixing ratio of the carbon fiber and the wholly aromatic liquid crystal polymer resin in the composition finally obtained in the present invention can be achieved.

Regarding the mixing ratio of the carbon fibers, when less than 2 parts by weight of carbon fibers are mixed with 100 parts by weight of the wholly aromatic liquid crystal polymer resin, the reinforcing effect is insufficient and a resin composition having sufficient mechanical strength can not be produced. On the other hand, Is mixed in an amount greater than 100 parts by weight, the finally obtained resin composition is difficult to melt and mix into a homogeneous mixture, and the melt flowability is remarkably reduced, resulting in poor moldability at the time of injection molding.

The resin composition containing the above-mentioned carbon fibers of the present invention exhibits excellent heat resistance in a wide temperature range due to a synergistic effect between the improved heat resistance and the reinforcing effect of the carbon fibers.

In addition, as described above, the wholly aromatic liquid crystal polymer resin having a melting point in the range of 300 to 450 ° C. is used in the present invention. Since the carbon fiber is a material which secures thermal stability even at a high temperature of 300 ° C. or higher, Can be used.

In the wholly aromatic liquid crystal polymer resin composition of the present invention, by including the wholly aromatic liquid crystalline polymer resin having a melting point as described above and carbon fiber, heat resistance and fluidity can be secured at a desirable level while having high strength properties.

The wholly aromatic liquid crystal polymer resin included in the resin composition of the present invention may be prepared by the following steps:

(a) synthesizing a prepolymer of a wholly aromatic liquid crystal polymer resin by condensation polymerization of at least two kinds of aromatic compound monomers, and

(b) synthesizing the wholly aromatic liquid crystal polymer resin by solid-phase polycondensation of the prepolymer.

The monomer of the aromatic compound used in the polycondensation reaction in the step (a) is used in the production of a resin by a conventional polycondensation reaction, and includes at least one kind selected from the group consisting of aromatic diols, aromatic diamines and aromatic hydroxyamines And an aromatic dicarboxylic acid. Also, an aromatic hydroxycarboxylic acid or an aromatic aminocarboxylic acid may be used by condensation polymerization, or these may be further added to the condensation reaction between the diol, diamine or hydroxyamine and the dicarboxylic acid to carry out the reaction of the step (a) You can proceed.

As the synthesis method of the step (a), a solution condensation polymerization method or a bulk condensation polymerization method may be used as a method used for producing a resin by a conventional condensation polymerization reaction.

In the step (a), the monomers are pre-treated with a chemical substance such as an acylating agent (particularly, an acetylating agent) to increase the reactivity (that is, in the form of an acylated monomer) .

Next, for the solid-phase polycondensation reaction in the step (b), a condensation reaction is performed while heat is being supplied to the prepared prepolymer. Such heat providing methods include a method using a heating plate, a method using hot air, or a method using a high temperature fluid. In addition, purge or vacuum removal using an inert gas can be performed to remove by-products generated during the solid-phase polycondensation reaction.

The wholly aromatic liquid crystal polymer resin contains various repeating units in the polymer chain depending on the aromatic compound monomer used in the polymerization reaction as follows:

(1) a repeating unit derived from an aromatic diol:

[-O-Ar-O-]

(2) a repeating unit derived from an aromatic diamine:

[-HN-Ar-NH-] < / RTI >

(3) repeating unit derived from aromatic hydroxyamine:

[-HN-Ar-O-]

(4) repeating unit derived from an aromatic dicarboxylic acid:

[-OC-Ar-CO-]

(5) a repeating unit derived from an aromatic hydroxycarboxylic acid:

[-O-Ar-CO-]

(6) a repeating unit derived from an aromatic aminocarboxylic acid:

[-HN-Ar-CO-]

In the formulas (1) to (6), Ar may be a substituted or unsubstituted form of phenylene, biphenylene, naphthalene or two phenylene linked by carbon or non-carbon atoms. Preferably, the substituent may be an aliphatic substituent having 1 to 6 carbon atoms, and the non-carbon linking element may be nitrogen.

The resin composition of the present invention can contain high-strength properties without deteriorating the fluidity and heat resistance of the composition by including carbon fibers. Therefore, the wholly aromatic liquid crystal polymer resin composition of the present invention can be suitably used for forming a thin structure and a small connector and memory card socket product which are particularly vulnerable to external impact.

The carbon fiber contained in the resin composition of the present invention is preferably used in an amount of 2 to 100 parts by weight based on 100 parts by weight of the resin in consideration of the improvement of the mechanical strength and the dispersibility in the wholly aromatic liquid crystal polymer resin and the fluidity of the resin composition. As described above, when the carbon fiber is used in an amount less than 2 parts by weight, it is difficult to expect a sufficient improvement in mechanical strength in the wholly aromatic liquid crystal polymer resin composition. If the carbon fiber is used in an amount exceeding 100 parts by weight, The acidity and the fluidity of the composition deteriorate, which makes it difficult to knead the resin composition.

The resin composition of the present invention may further include conventional inorganic fillers to improve the mechanical properties and heat resistance of the resin composition in addition to the wholly aromatic liquid crystal polymer resin and the carbon fiber.

The inorganic filler is at least one selected from the group consisting of glass fiber, talc, mica, calcium carbonate and clay.

The content of the inorganic filler is preferably in the range of 3 to 900 parts by weight based on 100 parts by weight of the wholly aromatic liquid crystal polymer resin. When the total content of the inorganic filler is less than 3 parts by weight based on 100 parts by weight of the wholly aromatic liquid crystal polymer resin, it is difficult for the wholly aromatic liquid crystal polymer resin composition to achieve sufficient mechanical strength. When the total content is more than 900 parts by weight, The fluidity and moldability of the composition deteriorate.

The present invention relates to a method for producing the wholly aromatic liquid crystal polymer resin composition, which comprises mixing 2 to 100 parts by weight of carbon fibers with 100 parts by weight of a wholly aromatic liquid crystal polymer resin having a melting point of 300 to 450 ° C to prepare a mixture, And the mixture is melt-kneaded. Wherein the mixture further comprises at least one inorganic filler selected from the group consisting of glass fibers, talc, mica, calcium carbonate and clay in an amount of 3 to 900 parts by weight per 100 parts by weight of the wholly aromatic liquid crystal polymer resin Can be used.

For the melt-kneading of the mixture containing the resin and the carbon fiber or the like, a twin-screw extruder, a batch kneader or a mixing roll may be used. In particular, when melt kneading is performed using a twin-screw extruder, the barrel temperature of the extruder can be maintained at 330 to 450 ° C. Here, the barrel of an extruder is a portion for melting, kneading, and transporting an extruded raw material (i.e., a mixture of resin and nano-clay or the like), which is also referred to as a cylinder. The barrel is equipped with a screw, so that the extruded raw material is fed forward in accordance with two rotations of the screw, and at the same time, the extruded raw material is melted due to the heat conducted from the barrel wall surface. Further, in order to smoothly melt-knead the raw material for extrusion, an activator may be additionally used in melt-kneading.

The present invention provides an electronic device manufactured from the resin composition produced by the above production method. Examples of such electronic appliances include thin-walled connectors and particularly small connector and memory card socket products.

Hereinafter, the present invention will be described in detail with reference to examples. However, this is for facilitating the understanding of the invention, and therefore the present invention should not be construed as being limited thereto.

Example  One

(1) Production of wholly aromatic liquid crystal polymer resin

24.4 kg of parahydroxybenzoic acid (UENO Fine Chemirals), 10.8 kg of biphenol (Songwon), 7.3 kg of terephthalic acid (Samsung Petrochemical), and isophthalic acid (Perstorp) were added to a 100 liter capacity batch- And nitrogen gas was injected to make the internal space of the reactor inactive, and 33 kg of acetic anhydride (CELANESE) was further added to the reactor. Thereafter, the reactor temperature was raised to 150 캜 over 30 minutes, and the alcohol group (hydroxyl group) of the monomers was subjected to acetylation reaction at the above temperature for 3 hours.

Next, the acetic acid produced in the acetylation reaction was removed, and the temperature of the reactor was elevated to 330 ° C over 6 hours to prepare a wholly aromatic liquid-crystalline polymer resin prepolymer by the polycondensation reaction of monomers. During the preparation of the prepolymer, acetic acid was further produced as a by-product. The acetic acid was continuously removed in the course of preparation of the prepolymer in the same manner as the acetic acid produced in the acetylation reaction.

After completion of the reaction, the prepolymer was recovered from the reactor and cooled and solidified. Thereafter, the prepolymer was pulverized to an average particle size of 1 mm, 20 kg of the pulverized prepolymer was introduced into a 100-liter capacity rotary kiln reactor, nitrogen was continuously flowed at a flow rate of 1 Nm 3 / The temperature was raised to 280 DEG C over a period of 10 hours and maintained for 3 hours to prepare a wholly aromatic liquid crystal polymer resin.

Subsequently, the reactor was cooled to room temperature over 1 hour, and the wholly aromatic liquid crystal polymer resin was recovered from the reactor. The melting point of the resin measured using a differential scanning calorimeter was 320 ° C.

(2) Preparation of wholly aromatic liquid crystal polymer resin composition

The wholly aromatic liquid crystal polymer resin, glass fiber (Sungjin Fiber MF75-NL) and carbon fiber (Toho Tenax, HT C493) prepared in the above step (1) were mixed in a weight ratio of 85: 10: 5, And melt-kneaded using an extruder (L / D: 40, diameter: 20 mm). The barrel temperature of the extruder during the melt-kneading was 350 ° C. At the same time as the melt kneading, a by-product was removed by applying a vacuum to the twin screw extruder.

Then, the melt-kneaded product was mixed with an automatic mixer (Jeil Industry Instrument) for 10 minutes and dried at 130 ° C for 2 hours using a hot-air dryer (manufactured by Shing PLANT) to produce a wholly aromatic liquid crystal polymer resin composition.

Example  2

The mixing ratio of the wholly aromatic liquid crystal polymer resin, glass fiber (Sungjin Fiber MF75-NL) and carbon fiber (Toho Tenax, HT C493) prepared in the step (1) of Example 1 was changed to 80:10:10 by weight , A wholly aromatic liquid crystal polymer resin composition was prepared in the same manner as in Example 1 above.

Comparative Example  One

Except that the wholly aromatic liquid-crystalline polymer resin prepared in step (1) of Example 1 and glass fibers (Sungjin Fiber MF75-NL) were used at 90:10 by weight, A wholly aromatic liquid crystal polymer resin composition was prepared.

Evaluation of physical properties of resin composition

The physical properties of each of the wholly aromatic liquid crystal polymer resin compositions prepared in the above Examples and Comparative Examples were measured by the following methods.

(Measurement of melt viscosity)

The resin composition was measured for viscosity under a condition of 330 캜 and 1/1000 s using a capillary viscometer to compare the fluidity of the molten state.

(Measurement of tensile strength and tensile elongation)

The tensile strength and tensile elongation of the resin composition were measured according to ASTM D638.

(Measurement of flexural strength and flexural elongation)

The flexural strength and flexural elongation of the resin composition were measured according to ASTM D790.

(Measurement of heat resistance (heat distortion temperature)) [

The heat resistance of the resin composition was measured according to ASTM D648. At this time, the applied pressure was 18.5 kgf / cm 2.

The physical properties measured for the resin composition are summarized in Table 1 below.

From Table 1, it was found that the wholly aromatic liquid crystalline polymer resin compositions prepared in Examples 1 and 2 had similar melt viscosity and heat resistance characteristics as those of the resin composition prepared in Comparative Example 1, but improved tensile strength and flexural strength. Also, when Examples 1 and 2 were compared, as the amount of carbon fiber used increased, the synergistic effect of mechanical strength was more pronounced.

On the other hand, when the carbon fiber is used in an excess amount exceeding 100 parts by weight with respect to 100 parts by weight of the resin, the fluidity of the mixture is drastically lowered, making it impossible to prepare the composition.

From the above results, it can be seen that by using a certain amount of carbon fiber in the omnidirectional liquid crystal polymer resin composition, fluidity suitable for molding of the composition can be maintained and mechanical strength can be effectively improved.

Claims (8)

Based on 100 parts by weight of a wholly aromatic liquid crystal polymer resin having a melting point of 300 to 450 DEG C, 2 to 100 parts by weight of acrylic carbon fiber and at least one inorganic filler selected from the group consisting of glass fiber, talc, mica, calcium carbonate and clay and
The acryl-based carbon fiber is obtained by spinning a spinning liquid containing a PAN-based polymer as a precursor thereof by a wet spinning method, a dry spinning method or a dry wet spinning method to obtain precursor fibers and then heating it in an oxidizing atmosphere at a temperature of 200 to 400 ° C Converted into chlorinated fibers, and carbonized by heating in an inert atmosphere at a temperature of at least 1000 ° C. [3] The wholly aromatic liquid-crystalline polymer resin composition according to claim 1, delete The method of claim 1,
Wherein the wholly aromatic liquid crystal polymer resin comprises at least one aromatic compound monomer selected from the group consisting of an aromatic diol, an aromatic diamine, an aromatic hydroxyamine, an aromatic dicarboxylic acid, an aromatic hydroxycarboxylic acid and an aromatic aminocarboxylic acid Wherein the aromatic polycarbonate resin is synthesized from a condensation polymerization reaction. 4. The method of claim 3,
Wherein the aromatic compound includes a form in which substituted or unsubstituted phenylene, biphenylene, naphthalene or two phenylene are linked by carbon or non-carbon atoms,
Wherein said substituent is substituted with an aliphatic substituent having 1 to 6 carbon atoms. delete The method of claim 1,
Wherein the inorganic filler is contained in an amount of 3 to 900 parts by weight based on 100 parts by weight of the wholly aromatic liquid crystal polymer resin. An electronic appliance element manufactured from the wholly aromatic liquid crystal polymer resin composition of any one of claims 1, 3, 4, and 6. 8. The method of claim 7,
Wherein the electronic device is a connector or a memory card socket.