TW202104346A - Liquid crystal polyester resin - Google Patents

Abstract

An objective of the present invention is to provide a liquid crystal polyester resin excellent in mechanical properties, especially in flexural modulus while maintaining excellent heat resistance and solvent resistance.

As a solution, the present invention relates to a liquid crystal polyester resin composed of repeating units represented by formulas (I) to (VI);

in the formula, p, q, r, s, t, and u are composition ratios (mol %) of the respective repeating units in the liquid crystal polyester resin, and satisfy the following conditions: 60≦p≦70, 15≦q+r≦20, 10≦s+t≦19, 1≦u≦5.

Description

Liquid crystal polyester resin

The present invention relates to liquid crystal polyester resin.

Thermotropic liquid crystal polymer (hereinafter referred to as liquid crystal polymer or LCP) has excellent mechanical properties, moldability, chemical resistance, gas barrier properties, moisture resistance, electrical properties, etc., so it is used in parts in various fields. In particular, due to its excellent heat resistance, solvent resistance, thin-wall formability, and insulation, its use in insulators (insulators) such as electric motors is expanding.

Motors used to drive hermetic compressors such as air conditioners, air conditioners, refrigerators, etc. are driven in a state of being immersed in a refrigerant. Therefore, the insulator installed inside the motor is also immersed in the refrigerant and used under extremely severe temperature conditions from room temperature to about 100°C.

Therefore, it is proposed to use a liquid crystal polymer with excellent heat resistance, mechanical and physical properties, and chemical resistance.

For example, Patent Document 1 proposes an insulator molded product of a motor that is formed by melt-molding a resin composition obtained by blending a filler in a liquid crystalline resin. In addition, Patent Document 2 proposes an insulator composed of a liquid crystal polymer using p-hydroxybenzoic acid and 2,6-hydroxynaphthoic acid as raw materials.

The insulators (insulators) described in Patent Documents 1 and 2 are composed of a liquid crystal polymer and have the advantages of excellent heat resistance and less burrs.

[Prior Technical Literature]

[Patent Literature]

[Patent Document 1] Japanese Laid-open Patent Publication No. 09-111106

[Patent Document 2] Japanese Laid-Open Patent Publication No. 2004-52730

However, the liquid crystal polymers disclosed in Patent Documents 1 and 2 still have insufficient mechanical properties, especially flexural modulus, and the insulator may be deformed when used under severe conditions. Furthermore, because of the high melting point of these liquid crystal polymers, there is a problem that the reaction does not proceed at high temperatures, the polymerization becomes insufficient, and low-molecular-weight compounds are likely to remain in the resin, and these are easily eluted in the refrigerant.

In order to solve such problems, it is desired to develop a liquid crystal polyester resin that has a good balance of high heat resistance and mechanical strength and is suitable for insulators.

The object of the present invention is to provide a liquid crystal polyester resin that maintains excellent heat resistance and solvent resistance and has excellent mechanical properties, particularly a flexural modulus.

In view of the above-mentioned problems, the inventors have made diligent studies and found that by polycondensation of monomers imparting specific repeating units, it is possible to obtain a liquid crystal polyester resin that maintains excellent heat resistance and solvent resistance and has an excellent flexural modulus. Thus, the present invention has been completed.

That is, the present invention includes the following preferable aspects.

[1] A liquid crystal polyester resin composed of repeating units represented by formulas (I) to (VI);

式中，

Where

p, q, r, s, t, and u are the composition ratios (mol %) of each repeating unit in the liquid crystal polyester resin, and satisfy the following conditions:

60≦p≦70;

15≦q+r≦20;

10≦s+t≦19;

1≦u≦5.

[2] The liquid crystal polyester resin as described in [1], wherein q/r is 0.9 to 1.3.

[3] The liquid crystal polyester resin as described in [1] or [2], wherein s/t is 0.9 to 1.5.

[4] The liquid crystal polyester resin according to any one of [1] to [3], which has a flexural modulus of 10 GPa or more.

[5] A liquid crystal polyester resin composition containing 0.1 to 200 parts by mass of fibrous, plate-like or Powdered filler.

[6] A molded article composed of the liquid crystal polyester resin described in any one of [1] to [4] or the liquid crystal polyester resin composition described in [5].

According to the present invention, it is possible to provide a liquid crystal polyester resin that maintains excellent heat resistance and solvent resistance and has an excellent flexural modulus.

The liquid crystal polyester resin of the present invention is a polyester resin that forms an anisotropic melt phase, and is called thermotropic liquid crystal polyester resin anisotropy by those with ordinary knowledge in the field of the present invention.

The properties of the anisotropic molten phase can be confirmed by a general polarization inspection method using crossed polarizers. More specifically, the confirmation of the anisotropic melt phase was performed by observing a sample mounted on a Leitz thermal platform at a magnification of 40 times using a Leitz polarizing microscope. The liquid crystal polyester resin of the present invention exhibits optical anisotropy, that is, one that transmits light when inspected between crossed polarizers. If the sample is optically anisotropic, for example, even in a stationary state, it will transmit polarized light.

The liquid crystal polyester resin of the present invention is composed of repeating units represented by formulas (I) to (VI);

式中，

Where

p, q, r, s, t, and u are the composition ratios (mol %) of each repeating unit in the liquid crystal polyester resin, and satisfy the following conditions:

60≦p≦70;

15≦q+r≦20;

10≦s+t≦19;

1≦u≦5.

The composition ratio p of the repeating unit represented by the formula (I) is preferably 62 to 68 mol%, more preferably 63 to 67 mol%.

The sum (q+r) of the composition ratio q of the repeating unit represented by formula (II) and the composition ratio r of the repeating unit represented by formula (III) is preferably 16 to 19 mol%, more preferably 17 to 18 mol% %.

The composition ratio s of the repeating unit represented by formula (IV) and the composition of the repeating unit represented by formula (V) The sum of the ratio t (s+t) is preferably 12 to 17.5 mol%, more preferably 14 to 16 mol%.

The composition ratio u of the repeating unit represented by the formula (VI) is preferably 1.5 to 4.0 mol%, more preferably 2.0 to 3.5 mol%.

The ratio of q to r (q/r) is preferably 0.9 to 1.3, more preferably 1.0 to 1.25, and still more preferably 1.05 to 1.25.

The ratio of s to t (s/t) is preferably 0.9 to 1.5, more preferably 1.0 to 1.45, and still more preferably 1.05 to 1.4.

The composition ratio q of the repeating unit represented by the formula (II) is preferably 7 to 12 mol%, more preferably 7.5 to 11 mol%, and still more preferably 8 to 10.5 mol%.

Moreover, the composition ratio r of the repeating unit represented by the formula (III) is preferably 5 to 11 mol%, more preferably 6 to 10 mol%, and still more preferably 7 to 9 mol%.

The composition ratio s of the repeating unit represented by the formula (IV) is preferably 5 to 11 mol%, more preferably 6 to 10 mol%, and still more preferably 7 to 9 mol%.

Moreover, the composition ratio t of the repeating unit represented by the formula (V) is preferably 4 to 10 mol%, more preferably 4.5 to 9.5 mol%, more desirably, and still more preferably 5 to 9 mol%.

Furthermore, it is preferably p+q+r+s+t+u=100.

Moreover, q+r=s+t+u is preferable.

Examples of the monomer to which the repeating unit represented by the formula (I) is imparted include 4-hydroxybenzoic acid and ester-forming derivatives such as 4-hydroxybenzoic acid and its acyl compounds, ester derivatives, and acid halides.

As a monomer imparting the repeating unit represented by the formula (II), for example, 4,4'-dihydroxybiphenyl and its alkyl, alkoxy or halogen substituents, and ester-forming compounds such as acyl compounds, etc. derivative.

As the monomer imparting the repeating unit represented by the formula (III), for example, hydroquinone and its alkane Ester-forming derivatives such as radicals, alkoxy or halogen substituents and these acyl compounds.

Examples of the monomer to which the repeating unit represented by the formula (IV) is imparted include terephthalic acid and its alkyl, alkoxy, or halogen substituents, and ester-forming derivatives such as these acyl compounds.

Examples of the monomer imparting the repeating unit represented by the formula (V) include ester-forming derivatives such as isophthalic acid and its alkyl, alkoxy, or halogen substituents, and these acyl compounds.

As the monomer imparting the repeating unit represented by the formula (VI), for example, 2,6-naphthalenedicarboxylic acid, its alkyl, alkoxy, or halogen substituents, and ester-forming derivatives such as acyl compounds, etc. can be cited .

The liquid crystal polyester resin of the present invention is the above-mentioned liquid crystal polyester resin composed of repeating units represented by formulas (I) to (VI), with [p+q+r+s+t+u=100] as the comparison Preferably, it may further contain other repeating units within a range that does not impair the purpose of the present invention.

Examples of monomers imparting other repeating units include other aromatic hydroxycarboxylic acids, aromatic hydroxyamines, aromatic diamines, aromatic aminocarboxylic acids, aromatic hydroxydicarboxylic acids, aliphatic diols, and aliphatic Dicarboxylic acids, aromatic mercaptocarboxylic acids, aromatic dithiols, aromatic mercaptophenols, and combinations thereof.

It is preferable that the sum of the monomers imparting other repeating units to the monomers imparting repeating units represented by formulas (I) to (VI) is 10 mol% or less.

The method for producing the liquid crystal polyester resin of the present invention is not particularly limited, and a conventional polycondensation method of polyester that forms ester bonds between the above-mentioned monomer components, such as a melt acid hydrolysis method, a slurry polymerization method, etc., can be used.

The so-called molten acidolysis method refers to the process of first heating the monomer to form a molten solution of the reacting substance, and then continuing the reaction to obtain a molten polymer. Furthermore, in order to easily remove the volatiles (for example, acetic acid, water, etc.) of the by-products in the final stage of the condensation polymerization, a vacuum may be applied. This method is particularly suitable in the present invention.

The so-called slurry polymerization method refers to a method of reacting in the presence of a heat exchange fluid, and the solid product is obtained in a suspended state in the heat exchange medium.

In either of the molten acidolysis method and the slurry polymerization method, the polymerizable monomer component used in the production of the liquid crystal polyester resin is supplied to the reaction in a modified form in which the hydroxyl group is esterified, that is, as a lower acyl ester. The lower acyl group preferably has 2 to 5 carbon atoms, and more preferably has 2 or 3 carbon atoms. Particularly preferred is a method of using the acetate of the aforementioned monomer component in the reaction.

The lower acylated ester of the monomer can be synthesized in advance by acylation. When the liquid crystal polyester resin is produced, an acylated agent such as acetic anhydride can be added to the monomer to be generated in the reaction system.

In either of the molten acidolysis method and the slurry polymerization method, a catalyst can be used as needed.

Specific examples of the catalyst include organotin compounds such as dialkyl tin oxide (for example, dibutyl tin oxide) and diaryl tin oxide; metal oxides such as titanium dioxide; and antimony such as antimony trioxide. Compounds; organic titanium compounds such as titanium alkoxysilicate and titanium alkoxide; alkali and alkaline earth metal salts of carboxylic acids (such as potassium acetate); Lewis acids (such as boron trifluoride), hydrogen halides (such as hydrogen chloride), etc. The gaseous acid catalyst and so on.

The use ratio of the catalyst is usually 10 to 1000 ppm, preferably 20 to 200 ppm relative to the total amount of the monomer.

The thus obtained liquid crystal polyester resin of the present invention generally has a crystal melting temperature measured by a differential scanning calorimeter (DSC) of 330°C or lower, and has excellent low-temperature workability that can suppress thermal decomposition. The crystal melting temperature of the liquid crystal polyester resin of the present invention is preferably 290 to 330°C, more preferably 295 to 325°C, and still more preferably 300 to 323°C.

The liquid crystal polyester resin of the present invention has a flexural strength measured by the method described below with respect to a molded article composed of it, preferably 130 MPa or more, more preferably 130 to 170 MPa, and still more preferably 140 To 160MPa.

The liquid crystalline polyester resin of the present invention has a flexural modulus measured by the method described later, preferably 10 to 16 GPa, and still more preferably 11 to 15 GPa, as measured by the method described later.

The liquid crystal polyester resin of the present invention has a dissolution rate of the liquid crystal polyester resin when immersed in 700 g of chloroform for 16 hours at a temperature of 70°C, preferably 600 ppm or less, more preferably 500 ppm or less, and still more preferably 400 ppm the following.

The present invention further provides a liquid crystal polyester resin composition obtained by blending one or more types of fibrous, plate-like, or powdery fillers in the liquid crystal polyester resin of the present invention. As the filler, it can be appropriately selected from conventionally known substances used in resin compositions in accordance with the purpose and application of the liquid crystal polyester resin.

Examples of fibrous fillers include glass fiber, silica alumina fiber, alumina fiber, carbon fiber, and aramid fiber. Among these, from the viewpoint of excellent balance of physical properties and cost, glass fiber is preferred.

As a plate-like or powder-like filler, for example, talc, mica, graphite, wollastonite, calcium carbonate, dolomite, clay, glass flakes, glass beads, barium sulfate, titanium oxide, and the like. Among these, talc is preferred from the viewpoint of a good balance of physical properties and components.

In the liquid crystal polyester resin composition of the present invention, the total compounding amount of the filler is preferably 0.1 to 200 parts by mass, and particularly preferably 10 to 100 parts by mass, relative to 100 parts by mass of the liquid crystal polyester resin. When the blending amount of the filler exceeds 200 parts by mass, the molding processability of the resin composition is reduced, and the abrasion of the cylinder and mold of the molding machine tends to increase.

The liquid crystal polyester resin composition of the present invention, in a range that does not impair the effects of the present invention, According to the purpose and application of the resin composition, release agents for higher fatty acids, higher fatty acid esters, higher fatty acid amides, higher fatty acid metal salts, polysiloxanes, fluororesins, etc. can be added; coloring agents for dyes, pigments, etc. Antioxidant; Thermal stabilizer; Ultraviolet absorber; Anti-charge agent; Surfactant and other conventional additives used in resin compositions in one or a combination of two or more.

Those having an external lubricant effect such as higher fatty acids, higher fatty acid esters, higher fatty acid metal salts, fluorocarbon surfactants, etc., can be used by being attached to particles in advance during molding.

In the liquid crystal polyester resin composition of the present invention, all ingredients such as fillers and additives are added to the polyester resin, using a Banbury mixer, kneader, one-axis or two-axis extruder, etc. The liquid crystal polyester resin is prepared by melting and kneading from the vicinity of the crystal melting temperature to the crystal melting temperature + 100°C.

The liquid crystal polyester resin and liquid crystal polyester resin composition of the present invention thus obtained can be processed into injection molded products, films, etc. by conventional molding methods such as injection molding, compression molding, extrusion molding, and blown film. Molded products such as sheets and non-woven fabrics.

The liquid crystal polyester resin and the liquid crystal polyester resin composition of the present invention have an excellent balance of heat resistance and mechanical properties and are suitable for use as electrical and electronic parts, mechanical parts such as camera modules, automobile parts, and the like. In particular, the liquid crystal polyester resin of the present invention has excellent solvent resistance and flexural modulus, and is useful as an insulator (insulator) for electric motors.

Hereinafter, the present invention will be described in detail with examples, but the present invention is not limited to these examples.

[Example]

The crystal melting temperature, flexural strength, flexural modulus, and dissolution rate in the examples were measured by the methods described below.

<Crystal melting temperature>

Exstar6000 manufactured by Seiko instruments was used for measurement. Starting from room temperature, the liquid crystal polyester resin sample was measured under a temperature increase of 20°C/min, and after the endothermic peak temperature (Tm1) was observed, it was kept at a temperature 20 to 50°C higher than Tm1 for 10 minutes. Then, after cooling the sample to room temperature at a temperature drop of 20°C/min, the endothermic peak when measured under a temperature rise condition of 20°C/min again was observed, and the temperature indicating the peak top was regarded as the crystal melting of the liquid crystal polyester resin. temperature.

〈Bending strength and bending modulus〉

Using an injection molding machine with a clamping pressure of 15t (MINIMAT M26/15 manufactured by Sumitomo Heavy Industries Co., Ltd.), injection molding is performed at a crystal melting temperature + 20 to 40°C, a cylinder temperature, and a mold temperature of 70°C to produce a ribbon curve. Test piece (length 65mm×width 12.7mm×thickness 2.0mm). The bending test system uses INSTRON5567 (universal testing machine manufactured by INSTRON Japan), and performs a 3-point bending test at a span of 40.0 mm and a compression speed of 1.3 mm/min.

〈Dissolution rate〉

Nine test pieces and 700 g of chloroform, which are the same as those used for the measurement of flexural strength and flexural modulus, were put into a 1000-ml four-necked flask, immersed in a 70°C water bath, and refluxed for 16 hours. Filter the test piece and the solution, dry the solidified filtrate under reduced pressure, and then dry it at 60°C for 12 hours. The value obtained by dividing the mass of the obtained solid by the mass of the test piece supplied for measurement was calculated, and this was taken as the dissolution rate. The larger the elution rate, the larger the amount of eluted low-molecular compounds.

In the examples, the following abbreviations indicate the following compounds.

POB: 4-hydroxybenzoic acid

BON6: 6-hydroxy-2-naphthoic acid

BP: 4,4’-dihydroxybiphenyl

HQ: Hydroquinone

TPA: Terephthalic acid

IPA: Isophthalic acid

NDA: 2,6-naphthalenedicarboxylic acid

(Example 1)

In a reaction vessel equipped with a stirring device with a torque meter and a distillation tube, feed POB, BP, HQ, TPA, IPA, and NDA with the composition ratio shown in Table 1 so that the total amount is 6.5 mol, and then compare it to The hydroxyl amount (mole) of all monomers was fed into 1.03 times mol of acetic anhydride, and then deacetic acid polymerization was carried out under the following conditions.

In a nitrogen atmosphere, the temperature is increased from room temperature to 150°C for 1 hour, and the temperature is maintained at the same temperature for 30 minutes. Then, the by-product acetic acid was distilled off and the temperature was rapidly raised to 210°C, and the temperature was maintained at the same temperature for 30 minutes. Then, after the temperature was raised to 340°C in 4 hours, the pressure was reduced to 10 mmHg in 80 minutes. The polymerization reaction is terminated at the time point when the specified torque is displayed, the contents are taken out from the reaction vessel, and the particles of the liquid crystal polyester resin are obtained by a pulverizer. The amount of acetic acid distilled during polymerization is almost the theoretical value.

Using the obtained particles of the liquid crystal polyester resin, the crystal melting temperature, bending strength, bending modulus, and dissolution rate were measured by the above-mentioned methods. The results are shown in Table 1.

(Examples 2 to 3 and Comparative Examples 1 to 6)

Except that the monomer composition ratio was changed to the composition ratio shown in Table 1, pellets of liquid crystal polyester resin were obtained in the same manner as in Example 1. The obtained pellets were used to measure the crystal melting temperature, flexural strength, flexural modulus, and dissolution rate. The results are shown in Table 1.

The liquid crystal polyester resin of Examples 1 to 3 has a crystal melting temperature of 318 to 323° C., a bending strength of 144 to 155 MPa, a bending modulus of 11.6 to 12.2 GPa, and excellent heat resistance and mechanical strength. Moreover, the elution rate is 400 ppm or less, and the solvent resistance is excellent.

On the other hand, the liquid crystal polyester resins of Comparative Examples 1 to 5 have a flexural modulus of less than 10 GPa and poor mechanical strength.

Furthermore, in Comparative Example 6, when the temperature was raised to 340°C over 4 hours, the contents were cured when the temperature was raised to 305°C, and stirring became impossible, so the reaction was terminated and the liquid crystal polyester resin could not be obtained.

[Table 1]

Claims (6)

A liquid crystal polyester resin, which is composed of repeating units represented by formulas (I) to (VI);

Where p, q, r, s, t, and u are the composition ratios (mol %) of each repeating unit in the liquid crystal polyester resin, and satisfy the following conditions: 60≦p≦70; 15≦q+r≦20; 10≦s+t≦19; 1≦u≦5. The liquid crystal polyester resin according to claim 1, wherein q/r is 0.9 to 1.3. The liquid crystal polyester resin according to claim 1 or 2, wherein s/t is 0.9 to 1.5. The liquid crystal polyester resin according to any one of claims 1 to 3, which has a flexural modulus of Above 10GPa. A liquid crystal polyester resin composition containing 0.1 to 200 parts by mass of fibrous, plate-like or powdery filler with respect to 100 parts by mass of the liquid crystal polyester resin according to any one of claims 1 to 4 Agent. A molded product composed of the liquid crystal polyester resin according to any one of claims 1 to 4 or the liquid crystal polyester resin composition according to claim 5.