KR101842284B1 - Anisotropy Liquid Crystal Polyester Composition and Radiant Heat Substrate Using the Same - Google Patents

Abstract

The present invention relates to a liquid crystal polyester composition comprising a liquid crystal polyester, an inorganic filler and a solvent,
Wherein the inorganic filler further comprises aluminum oxide.

Description

TECHNICAL FIELD [0001] The present invention relates to an anisotropic liquid crystal polyester composition and a heat dissipating plate using the same. ≪ Desc / Clms Page number 1 > Anisotropy Liquid Crystal Polyester Composition and Radiant Heat Substrate Using the Same &

The present invention relates to an anisotropic liquid crystal polyester composition and a heat dissipating plate using the same. More specifically, the present invention relates to an anisotropic liquid crystal polyester composition capable of increasing weak mechanical strength due to anisotropy of a liquid polyester, And a radiator plate using the same.

The liquid crystal polyester layer has high thermal stability and is applied to various electronic parts and is manufactured by using a method such as injection to form a shape. It is also manufactured with an inorganic filler to improve various properties.

For this purpose, an invention has been studied in which an inorganic filler is incorporated into a liquid crystal polyester layer by including an inorganic filler in the liquid composition. For example, Korean Patent Laid-Open Publication No. 10-2012-0010134 discloses a method for forming an inorganic filler and a liquid crystal polyester In order to improve the chemical resistance and adhesion, surface treatment of an inorganic filler is described.

However, even with such a liquid composition, the weak mechanical strength due to the anisotropy of the liquid polyester can not be improved, and the improvement of thermal conductivity is also limited.

KR 10-2012-0010134 A

Disclosure of Invention Technical Problem [8] Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide an anisotropic liquid crystal polyester composition capable of increasing weak mechanical strength due to anisotropy of liquid polyester and improving thermal conductivity, The purpose is to provide.

According to an aspect of the present invention,

1. A liquid crystal polyester composition comprising a liquid crystal polyester, an inorganic filler and a solvent,

Wherein the inorganic filler further comprises aluminum oxide. The present invention also provides an anisotropic liquid crystal polyester composition.

According to another aspect of the present invention,

Wherein the liquid crystal polyester composition is produced from the liquid crystal polyester composition.

According to the anisotropic liquid crystal polyester composition of the present invention, the weak mechanical strength due to the anisotropy of the liquid polyester can be increased and the thermal conductivity can be improved.

1 is a TEM image of a porous aluminum oxide particle of Example 1 of the present invention.
2 is a SEM image of aluminum oxide particles of Comparative Example 1 of the present invention.

Hereinafter, the present invention will be described in detail.

The liquid crystal polyester composition according to the present invention comprises a liquid crystal polyester, an inorganic filler and a solvent, and the inorganic filler further comprises aluminum oxide.

≪ Liquid crystal polyester &

The liquid crystal polyester of the present invention is a liquid crystal polyester which exhibits liquid crystallinity in a molten state, and is melted at a temperature of 450 DEG C or less. Especially, in the molten state, it is in the middle state of solid crystal and isotropic liquid, and has various properties because it has liquidity like liquid and regulatory structure. Further, typical examples of the polyester include those obtained by polymerizing (polycondensing) a compound selected from the group consisting of aromatic hydroxycarboxylic acid, aromatic dicarboxylic acid, aromatic diol, aromatic hydroxyamine and aromatic diamine, Those obtained by polymerizing an aromatic hydroxycarboxylic acid, those obtained by polymerizing a compound selected from the group consisting of an aromatic dicarboxylic acid, an aromatic diol, an aromatic hydroxyamine and an aromatic diamine, and a polyester obtained by polymerizing a polyester such as polyethylene terephthalate with an aromatic And a polymer obtained by polymerizing a hydroxycarboxylic acid.

In the present invention, the liquid crystal polyester is a polyester obtained by copolymerizing a repeating unit represented by the following formula (hereinafter sometimes referred to as a " repeating unit (1) ") and a repeating unit represented by the following formula (2) (Hereinafter may be referred to as " repeating unit (3) "), and a repeating unit represented by the following formula (3)

[Chemical Formula 1]

-O-Ar < ^{1 >} -CO-

(2)

-CO-Ar ² -CO-

(3)

-X-Ar &^lt; ¹ &^gt; -Y-

(Wherein Ar ¹ represents a phenylene group, a naphthylene group or a biphenylene group, Ar ² and Ar ³ each independently represent a phenylene group, a naphthylene group, a biphenylene group or a group represented by the following general formula (4) Each independently represents an oxygen atom or an imino group (-NH-), and each of the hydrogen atoms in the group represented by Ar ¹ , Ar ² or Ar ³ may be independently substituted with a halogen atom, an alkyl group or an aryl group)

[Chemical Formula 4]

-Ar ⁴ -Z- Ar ⁵ -

(Ar ⁴ and Ar ⁵ each independently represent a phenylene group or a naphthylene group, and Z represents an oxygen atom, a sulfur atom, a carbonyl group, a sulfonyl group or an alkylidene group)

Examples of the halogen atom include a fluorine atom, a chlorine atom and a bromine atom. Examples of the alkyl group include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, s-butyl, t- 1 to 10. Examples of the aryl group include a phenyl group, o-tolyl group, m-tolyl group, p-tolyl group, 1-naphthyl group and 2-naphthyl group. Examples of the alkylidene group include a methylene group, an ethylidene group, an isopropylidene group, an n-butylidene group and a 2-ethylhexylidene group, and the carbon number thereof is usually 1 to 10. [

The repeating unit (1) is a repeating unit derived from an aromatic hydroxycarboxylic acid. As Ar1, a p-phenylene group (derived from p-hydroxybenzoic acid) and a 2,6-naphthylene group (6-hydroxy- Naphthoic acid) is preferable.

The repeating unit (2) is a repeating unit derived from an aromatic dicarboxylic acid. As Ar2, a repeating unit derived from a p-phenylene group (derived from terephthalic acid), an m-phenylene group (derived from isophthalic acid), a 2,6- -Hydroxy-2-naphthoic acid) and a diphenyl ether-4,4'-diyl group (derived from diphenyl ether-4,4'-dicarboxylic acid).

The repeating unit (3) is a repeating unit derived from an aromatic diol, an aromatic hydroxylamine, or an aromatic diamine. As the Ar3, a p-phenylene group (derived from hydroquinone, p-aminophenol or p- -Biphenylene group (derived from 4,4'-dihydroxybiphenyl, 4-amino-4'-hydroxybiphenyl or 4,4'-diaminobiphenyl) is preferable.

The content of the repeating unit (1) is determined by dividing the total amount of all the repeating units constituting the liquid crystal polyester (the mass of each repeating unit constituting the liquid crystal polyester by the amount of each repeating unit, Is preferably 30 to 80 mol%, more preferably 30 to 60 mol%, and still more preferably 30 to 40 mol% based on the sum The more the content of the repeating unit (1) is, the more the liquid crystallinity of the liquid crystal polyester tends to be improved. The smaller the content of the repeating unit (1), the better the solubility of the liquid crystalline polyester in a solvent.

The content of the repeating unit (2) is preferably 10 to 35 mol%, more preferably 20 to 35 mol%, and still more preferably 30 to 35 mol%, based on the total amount of all the repeating units constituting the liquid- 35 mol%. The higher the content of the repeating unit (2), the better the solubility of the liquid crystalline polyester in the solvent. The smaller the content of the repeating unit (2), the better the liquid crystallinity of the liquid crystal polyester.

The content of the repeating unit (3) is preferably 10 to 35 mol%, more preferably 20 to 35 mol%, and still more preferably 30 to 35 mol% based on the total amount of all the repeating units constituting the liquid crystal polyester 35 mol%. The higher the content of the repeating unit (3), the better the solubility of the liquid crystalline polyester in a solvent. The smaller the content of the repeating unit (3), the better the liquid crystallinity of the liquid crystal polyester.

The content ratio of the repeating unit (2) to the repeating unit (3) is 0.9 / 1 to 1 / 0.9, expressed as [repeating unit (2)] / [repeating unit (3) The polyester is preferable because it exhibits high liquid crystallinity.

It is preferable that the liquid crystal polyester has repeating units (3) in which X and / or Y is an imino group, that is, a repeating unit derived from an aromatic hydroxylamine and / or a repeating unit derived from an aromatic diamine, , And it is more preferable that X and / or Y of substantially all the repeating units (3) are imino groups.

The liquid crystal polyester is most suitable when its flow initiation temperature is in the range of 260 ° C to 330 ° C. The higher the liquid initiation temperature of the liquid crystal polyester, the more the heat resistance and strength of the liquid crystal polyester tends to be improved. , The viscosity of the liquid crystal polyester composition is increased, and the handling becomes difficult. The liquid crystal polyester is characterized by high mechanical strength and heat resistance, high elastic modulus and low mold shrinkage due to its characteristic physical properties, and since the electric conductivity is also low, the material of the radiator plate is used as a suitable material. However, . High shear stress in the molten state facilitates orientation in one direction and this degree of orientation indicates that the intermolecular force is strong, but it also means that it has anisotropy. This has the disadvantage that the stress when not in the alignment direction is lower than the alignment direction. In addition, the liquid crystal polyester of the present invention can be dissolved in a solvent, which can contain a relatively large amount of filler, thereby increasing the efficiency of the filler. As described above, the liquid crystal polyester of the present invention is suitable as a heat-radiating material due to its excellent mechanical properties, low electrical conductivity and high thermal conductivity.

<Inorganic filler>

In the present invention, in order to improve the mechanical properties of the polyester resin, various inorganic fillers may be used depending on the purpose. In particular, in the case of polyesters whose mechanical and thermal properties are lowered in the direction perpendicular to the orientation, the plate-like inorganic fillers can increase the mechanical strength and can secure the thermal properties and the like depending on the types.

Examples of the inorganic fillers usable in the present invention include boron nitride, silicon oxide, aluminum oxide, porous aluminum oxide, graphene, boron nitride, clay and the like. More preferably, silicon oxide and porous aluminum oxide are used .

Particularly, the porous aluminum oxide used in the present invention has a particle size of 100 to 1000 탆 and a specific surface area of 100 to 500 m ² / g. Therefore, the porous aluminum oxide of the present invention has a very large surface area as compared with the aluminum oxide used as the conventional inorganic filler, so that heat can be transferred more easily and efficiently in thermal conduction, Function can be provided.

The porous aluminum oxide included in the present invention is preferably contained in an amount of 5 to 20% by weight based on the total weight of the liquid crystal polyester composition. If the weight ratio of the porous aluminum oxide is less than 5% by weight, the effect of increasing the thermal conductivity is insignificant and the increase of the mechanical properties is decreased. When the weight ratio is more than 20% by weight, the workability and the flexibility of the final product are problematic.

The method for producing the porous aluminum oxide of the present invention is as follows. First, a composite of polystyrene and Al ₂ O ₃ is prepared, followed by firing at 800 ° C. to remove polystyrene, thereby forming a large number of pores in the place where polystyrene is present, thereby producing porous aluminum oxide. The particle size and the comparative area of the porous aluminum oxide of the present invention can be controlled by adjusting the size of the polystyrene used in the above production process.

<Solvent>

As the solvent used for the production of the liquid crystalline polyester composition, a solvent mainly composed of an aprotic compound, particularly a non-protonic compound having no halogen atom, is suitable because it is low in corrosiveness and easy to handle. N, N-dimethylformamide, N, N-dimethylacetamide, N-methylpyrrolidone and the like are suitable from the viewpoint of easily dissolving the liquid crystal polyester.

The production of the liquid crystal polyester composition of the present invention can be carried out by mixing the liquid crystal polyester, the inorganic filler and other components to be used as needed, either collectively or in an appropriate order. However, when the liquid crystal polyester is dissolved in a solvent, When the ester solution is obtained and the inorganic filler is dispersed in the liquid crystal polyester solution, the degree of dispersion of the inorganic filler can be further improved. In the production of the liquid crystal polyester composition described above, the liquid crystal polyester, the solvent and the inorganic filler can be mixed together or in an appropriate order. However, after the liquid crystal polyester is dissolved in a solvent to obtain a liquid crystal polyester solution, It is preferable to conduct the dispersion by dispersing the surface-treated inorganic filler in the solution, and when dissolving the liquid-crystalline polyester in the solvent, dissolution at about 100 캜 is suitable.

The radiator plate according to the present invention can be manufactured using the liquid crystal polyester composition. In the case of manufacturing the radiator plate, the liquid crystal polyester composition can be produced by extruding and melting and kneading. The extrusion method used in the extrusion process is not particularly limited and a generally available extruder can be used. Preferably, the liquid crystal polyester composition is coated on a PET film by dip coating or the like. The coated liquid-crystalline polyester composition was ventilated by hot air at about 80 to 100 ° C for 10 to 60 minutes and dried. Then, the PET film having the completed liquid-crystalline polyester composition laminated was transferred to a copper plate through a rolling coating method, A radiator plate can be obtained.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention. Such variations and modifications are intended to be within the scope of the appended claims.

Example  1 to 3 and Comparative Example  One:

Production of liquid crystal polyester

1976 g (10.5 moles) of 6-hydroxy-2-naphthoic acid, 1474 g (9.75 moles) of 4-hydroxyacetanilide, 10 g of iso 1620 g (9.75 mol) of phthalic acid and 2374 g (23.25 mol) of acetic anhydride were introduced. After sufficiently replacing the inside of the reactor with nitrogen gas, the temperature was raised to 150 캜 over 15 minutes under a nitrogen gas stream, and the temperature was maintained and refluxed for 3 hours. Thereafter, while the by-produced acetic acid and the unreacted acetic anhydride were distilled off, the temperature was raised to 300 ° C over 170 minutes, and when the increase in torque was confirmed, the contents were taken out and cooled to room temperature. The obtained solid matter was pulverized by a pulverizer to obtain a liquid crystalline polyester in powder form. The starting temperature of the liquid crystal polyester was 235 占 폚. Subsequently, the liquid-crystalline polyester was subjected to solid-state polymerization by heating at 223 캜 for 3 hours in a nitrogen atmosphere. The liquid crystallization temperature of the liquid crystal polyester after the solid phase polymerization was 270 ° C.

Manufacture of Porous Aluminum Oxide

Initiator APS (392 g, Aldrich) was added using styrene (8.25 g, Aldrich), divinylbenzene (3 g, Aldrich) and vinyl acetate (3.75 g, Aldrich) as precursors, To thereby polymerize styrene particles having an average particle diameter of 0.20 mu m. The styrene particles thus obtained are mixed with distilled water and trimethylaluminum (TMA) in a fluidized bed reactor, and reacted at 33 ° C. for 2 hours. The collected particles were calcined at 800 DEG C for 2 hours, and then recovered porous aluminum oxide having a specific surface area of 100 mu m and an average particle size of 200 m &lt; ² &gt; / g, respectively.

Preparation of liquid crystal polyester composition

[Synthesis Example 1]

220 g of the liquid crystal polyester thus prepared was added to 780 g of N, N-dimethylacetamide and heated at 100 DEG C for 2 hours to obtain a liquid crystal polyester solution. To this solution was added Aluminum Oxide , Sumitomo Chem.) And silicon oxide (Aerosil 200, Sumitomo Chem.) At a ratio of 1: 1 to obtain a liquid crystal polyester composition. The amounts of aluminum oxide and silicon oxide used in the production of the liquid crystal polyester composition were 15% by weight and 0.8% by weight, respectively, with respect to the liquid crystal polyester. [Synthesis Example 2]

A liquid crystal polyester composition was prepared in the same manner as in Synthesis Example 1, except that the porous aluminum oxide prepared above was used in place of aluminum oxide in Synthesis Example 1. [

 [Synthesis Example 3]

A liquid crystal polyester composition was prepared in the same manner as in Synthesis Example 1, except that a mixture of aluminum oxide in place of aluminum oxide and porous aluminum oxide prepared in Synthesis Example 1 was used in a ratio of 1: 1.

[Synthesis Example 4]

A liquid crystal polyester composition was prepared in the same manner as in Synthesis Example 1 except that a mixture of aluminum oxide and silicon oxide was not used in Synthesis Example 1 but only silicon oxide was used.

Manufacture of radiator plate

Example 1.

The liquid crystal polyester composition of Synthesis Example 1 prepared above was first coated on a PET film by dip coating. At this time, the thickness of the polyester was 70 μm on the copper foil and the thickness was 350 μm. The polyester was ventilated at 100 ° C. for 20 minutes and heated to remove the solvent sufficiently. The PET film laminated with the liquid crystal polyester composition thus obtained was transferred to a copper plate through a rolling coating method and then heat-treated at 290 ° C for 3 hours to finally prepare a radiator plate.

Example 2.

A radiator plate was manufactured in the same manner as in Example 1, except that the liquid crystal polyester composition of Synthesis Example 2 was used.

Example 3.

A radiator plate was manufactured in the same manner as in Example 1, except that the liquid crystal polyester composition of Synthesis Example 3 was used.

Comparative Example 1

A radiator plate was produced in the same manner as in Example 1, except that the liquid crystal polyester composition of Synthesis Example 4 was used.

Experimental Example

Thermal conductivity at 30 캜 was measured using a thermal conductivity meter (LFA447 NESKA, ASTM E 1461) for the heat dissipating plate prepared in Examples 1 to 3 and Comparative Example 1.

The measured values of the thermal conductivity of Examples 1 to 3 and Comparative Examples 1 to 2 are shown in Table 1 below.

Liquid crystal polyester composition Thermal conductivity
(W / mK) Example 1 Synthesis Example 1 3.5 Example 2 Synthesis Example 2 4.3 Example 3 Synthesis Example 3 3.9 Comparative Example 1 Synthesis Example 4 1.8

As shown in Table 1, Comparative Example 1 containing only silicon oxide exhibited low thermal conductivity, whereas Examples 1 to 3 including aluminum oxide exhibited high thermal conductivity. In particular, Example 2, which comprises porous aluminum oxide, exhibits a much higher thermal conductivity than other radiator plates comprising aluminum oxide, and Example 4, which includes both conventional aluminum oxide and porous aluminum oxide, It can be seen that the thermal conductivity is higher when the porous aluminum oxide is used because the thermal conductivity is higher than that of the second embodiment.

Claims (4)

1. A liquid crystal polyester composition comprising a liquid crystal polyester, an inorganic filler and a solvent,
Wherein the inorganic filler further comprises a porous aluminum oxide having a particle size of 100 to 1000 mu m and a specific surface area of 100 to 500 m &lt; ² &gt; / g. delete The method according to claim 1,
Wherein the liquid crystal polyester has a repeating unit represented by the following formula (1), a repeating unit represented by the following formula (2), and a repeating unit represented by the following formula (3).
[Chemical Formula 1]
-O-Ar &lt; ^{1 &gt;} -CO-
(2)
-CO-Ar ² -CO-
(3)
-X-Ar &lt; ³ &gt; -Y-
(Wherein Ar ¹ represents a phenylene group, a naphthylene group or a biphenylene group, Ar ² and Ar ³ each independently represent a phenylene group, a naphthylene group, a biphenylene group or a group represented by the following general formula (4) Each independently represents an oxygen atom or an imino group (-NH-), and each of the hydrogen atoms in the group represented by Ar ¹ , Ar ² or Ar ³ may be independently substituted with a halogen atom, an alkyl group or an aryl group)
[Chemical Formula 4]
-Ar ⁴ -Z- Ar ⁵ -
(Ar ⁴ and Ar ⁵ each independently represent a phenylene group or a naphthylene group, and Z represents an oxygen atom, a sulfur atom, a carbonyl group, a sulfonyl group or an alkylidene group) A radiator plate produced by the liquid-crystalline polyester composition of claim 1.

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