JP7441722B2 - liquid crystal polymer - Google Patents

Description

The present invention relates to a liquid crystal polymer with excellent mechanical strength.

Liquid crystal polymers have excellent mechanical properties such as heat resistance and rigidity, chemical resistance, and dimensional accuracy, so their use is expanding not only to molded products but also to various applications such as fibers and films. In particular, electrical and electronic components are rapidly becoming more highly integrated, smaller, thinner, and lower in height, and in many cases very thin wall parts of 0.5 mm or less are formed, making liquid crystal polymers an excellent solution. Its usage has increased significantly due to its excellent moldability, that is, its good fluidity and no burrs, which are characteristics not found in other polymers.

In recent years, with the development of a highly information-oriented society, the amount and speed of information transmitted by information and communication equipment has increased explosively in the information and communication field, such as personal computers and mobile phones. There is a growing need for high-performance, high-frequency electronic components that can be used in

On the other hand, electronic circuit boards tend to generate heat due to the transmission and reception of high-frequency, large-capacity electrical signals associated with information processing, and the amount of power consumed due to the heat generation is becoming impossible to ignore.

In general, the smaller the dielectric loss tangent of the molding material for the electronic circuit board, the lower the amount of heat generated, and the amount of power consumed due to heat generation can be suppressed. As an example focusing on this point, it is known that liquid crystalline aromatic polyester is used as a molding material with a low dielectric loss tangent. For example, Patent Document 1 discloses that the structural unit is composed of a structural unit derived from p-hydroxybenzoic acid and a structural unit derived from 6-hydroxy-2-naphthoic acid, and the content ratio of the structural unit derived from p-hydroxybenzoic acid is Liquid crystalline aromatic polyesters having a composition of approximately 20 to 35 mol % have been proposed.

Patent No. 4363057

However, the liquid crystalline aromatic polyester described in Patent Document 1 is inferior in mechanical strength, particularly Izod impact strength, and further improvement in mechanical strength is required.

It is an object of the present invention to provide a liquid crystal polymer with improved mechanical strength, such as Izod impact strength.

In view of the above-mentioned problems, the present inventors have made extensive studies and have developed molded products with improved mechanical strength by copolymerizing an aliphatic dicarboxylic acid component with a specific structure with other polymerizable monomers. The present inventors have discovered that a liquid crystal polymer that can be formed can be obtained, and have completed the present invention.

That is, the present invention includes the following preferred embodiments.
[1] Formula (1)
HOOC-(CH ₂ ) _n -COOH...Formula (1)
[In the formula, n is an integer from 4 to 18]
The structural unit (A) derived from one or more polymerizable compounds selected from the group consisting of the compounds represented by and their reactive derivatives, the structural unit (B) derived from 4-hydroxybenzoic acid, and the 6- A liquid crystal polymer containing a structural unit (C) derived from hydroxy-2-naphthoic acid, in which the structural unit (A) is 0.01 to 7 mol% with respect to 100 mol% of all structural units constituting the liquid crystal polymer. , a liquid crystal polymer containing 15 to 40 mol% of the structural unit (B) and 60 to 85 mol% of the structural unit (C).
[2] The compound represented by formula (1) is represented by formula (2)
HOOC-(CH ₂ ) ₈ -COOH...Formula (2)
The liquid crystal polymer according to claim 1, which is a compound represented by:
[3] The liquid crystal polymer according to [1] or [2], which has an Izod impact strength of 200 J/m or more.
[4] A liquid crystal polymer composition comprising the liquid crystal polymer according to any one of [1] to [3] and an inorganic or organic filler.
[5] An article made of a molded article, film, or fiber produced by processing the liquid crystal polymer according to any one of [1] to [3] or the liquid crystal polymer composition according to [4].

According to the liquid crystal polymer of the present invention, articles such as molded articles having improved mechanical strength such as Izod impact strength can be formed.

The liquid crystal polymer of the invention is preferably a polyester or polyester amide that forms an anisotropic melt phase. These are commonly referred to in the art as thermotropic liquid crystal polyesters or thermotropic liquid crystal polyester amides, but are not particularly limited.

The liquid crystal polymer of the present invention has the formula (1) with respect to 100 mol% of the total structural units constituting the liquid crystal polymer.
HOOC-(CH ₂ ) _n -COOH...Formula (1)
[In the formula, n is an integer from 4 to 18]
0.01 to 7 mol% of the structural unit (A) derived from one or more polymerizable compounds selected from the group consisting of the compounds represented by and their reactive derivatives, derived from 4-hydroxybenzoic acid It contains 15 to 40 mol% of the structural unit (B) and 60 to 85 mol% of the structural unit (C) derived from 6-hydroxy-2-naphthoic acid.

Examples of the compound represented by formula (1) include hexanedioic acid, heptanedioic acid, octanedioic acid, nonanedioic acid, decanedioic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, and pentadecanedioic acid. acids, hexadecanedioic acid, heptadecanedioic acid, octadecanedioic acid, nonadecanedioic acid, eicosanedioic acid, and the like.

Among these, decanedioic acid (sebacic acid), hexanedioic acid (adipic acid) and dodecanedioic acid, which are represented by the following formulas (2) to (4), respectively, have a higher effect of improving mechanical strength. is preferred, and decanedioic acid (sebacic acid) is particularly preferred.

HOOC-(CH ₂ ) ₈ -COOH...Formula (2)
HOOC-(CH ₂ ) ₄ -COOH...Formula (3)
HOOC-(CH ₂ ) ₁₀ -COOH...Formula (4)

The structural unit (A) derived from one or more polymerizable compounds selected from the group consisting of compounds represented by formula (1) and reactive derivatives thereof is preferably based on 100 mol% of the total structural units. is 0.05 to 5 mol%, more preferably 0.07 to 4 mol%, even more preferably 0.1 to 3 mol%. If the content of the structural unit (A) exceeds 7 mol% based on 100 mol% of all structural units constituting the liquid crystal polymer, heat resistance and mechanical properties will decrease. If the total amount of the structural unit (A) is less than 0.01 mol% with respect to 100 mol% of all structural units constituting the liquid crystal polymer, the effect of improving mechanical properties including Izod impact strength cannot be obtained. .

The structural unit (B) derived from 4-hydroxybenzoic acid is preferably 18 to 36 mol%, more preferably 20 to 34 mol%, even more preferably It is 21 to 32 mol%, particularly preferably 22 to 30 mol%.

The structural unit (C) derived from 6-hydroxy-2-naphthoic acid is preferably 64 to 82 mol%, more preferably 66 to 80 mol%, based on 100 mol% of all structural units constituting the liquid crystal polymer. More preferably 68 to 79 mol%, particularly preferably 70 to 78 mol%.

In a preferred embodiment of the liquid crystal polymer of the present invention, a structural unit (A) derived from one or more polymerizable compounds selected from the group consisting of compounds represented by formula (1) and reactive derivatives thereof; -A liquid crystal polymer composed of a structural unit (B) derived from hydroxybenzoic acid and a structural unit (C) derived from 6-hydroxy-2-naphthoic acid.

The total amount of structural units (A) to (C) in the liquid crystal polymer of the present invention is preferably 100 mol%, but other structural units may be further contained within a range that does not impair the object of the present invention.

Monomers providing other structural units include other aromatic hydroxycarboxylic acids, aromatic diols, aromatic dicarboxylic acids, aromatic hydroxyamines, aromatic diamines, aromatic aminocarboxylic acids, aromatic hydroxydicarboxylic acids, Examples include aliphatic diols, aliphatic dicarboxylic acids, aromatic mercaptocarboxylic acids, aromatic dithiols, aromatic mercaptophenols, and combinations thereof.

The total amount of repeating structural units provided by these other monomer components is preferably 10 mol % or less of the total structural units.

The method for producing the liquid crystal polymer of the present invention will be described below.

The liquid crystal polymer of the present invention comprises one or more polymerizable compounds selected from the group consisting of compounds represented by formula (1) and reactive derivatives thereof, 4-hydroxybenzoic acid and 6-hydroxy-2- It is a liquid crystal polymer formed by polymerizing a polymerizable monomer containing naphthoic acid. There are no particular limitations on the method for producing the liquid crystal polymer of the present invention, and the above polymerizable monomer may be subjected to a known polycondensation method to form an ester bond or an amide bond, such as a melt acidolysis method or a slurry polymerization method. The liquid crystal polymer of the present invention can be obtained by this method.

Melt acidolysis is a preferred method for producing the liquid crystal polymers of the present invention. In this method, the polymerizable compound and/or monomer are first heated to form a molten solution of the reactants, and then a polycondensation reaction is continued to obtain a molten polymer. Note that a vacuum may be applied to facilitate the removal of volatile by-products (eg, acetic acid, water, etc.) in the final stage of condensation.

Slurry polymerization is a method in which polymerizable compounds and/or polymerizable monomers are reacted in the presence of a heat exchange fluid, and a solid product is obtained in a suspended state in the heat exchange medium.

In both the melt acidolysis method and the slurry polymerization method, the polymerizable monomers used to produce liquid crystal polymers are modified forms in which hydroxyl groups and/or amino groups are acylated at room temperature. That is, it can also be subjected to the reaction as a lower acylated product.

The lower acyl group preferably has 2 to 5 carbon atoms, more preferably 2 or 3 carbon atoms. Particularly preferred is a method in which an acetylated product of the polymerizable compound and/or polymerizable monomer is used in the reaction.

The lower acylated product of the polymerizable compound and/or the polymerizable monomer may be acylated separately and synthesized in advance, or the polymerizable compound and/or the polymerizable monomer may be anhydrous during production of the liquid crystal polymer. It can also be produced within the reaction system by adding an acylating agent such as acetic acid.

In either the melt acidolysis method or the slurry polymerization method, the polymerization reaction is preferably carried out at a temperature of 150 to 400°C, preferably 250 to 370°C, under normal pressure and/or reduced pressure, and a catalyst is optionally used. may also be used.

Specific examples of catalysts include organotin compounds such as dialkyltin oxide (e.g. dibutyltin oxide), diaryltin oxide; titanium dioxide; antimony trioxide; organotitanium compounds such as alkoxytitanium silicates, titanium alkoxides; alkalis and alkalis of carboxylic acids. Gaseous acid catalysts such as earth metal salts (for example, potassium acetate); Lewis acids (for example, boron trifluoride), hydrogen halides (for example, hydrogen chloride), and the like.

When a catalyst is used, the amount of the catalyst is preferably 1 to 1000 ppm, more preferably 2 to 100 ppm, based on the total amount of polymerizable monomers.

The liquid crystal polymer of the present invention obtained by polycondensation reaction in this manner is usually extracted from the polymerization reaction tank in a molten state and then processed into pellets, flakes, or powder.

Liquid crystal polymers in the form of pellets, flakes, or powders are made into a substantially solid state under reduced pressure, vacuum, or an inert gas atmosphere such as nitrogen or helium, in order to increase the molecular weight and improve heat resistance. Heat treatment may be performed in this state.

The liquid crystal polymer of the present invention obtained as described above is blended with one or more selected from inorganic or organic fillers, other additives explained below, and other resin components to form a liquid crystal polymer. It may also be used as a composition.

The inorganic or organic filler that may be incorporated into the liquid crystal polymer of the present invention may be fibrous, plate-like or granular, such as glass fiber, milled glass, silica-alumina fiber, alumina fiber, carbon fiber, aramid. Fibers, potassium titanate whiskers, aluminum borate whiskers, wollastonite, talc, mica, graphite, calcium carbonate, dolomite, clay, glass flakes, glass beads, barium sulfate, and titanium oxide. Among these, glass fiber is preferable because it has an excellent balance between physical properties and cost. Two or more of these fillers may be used in combination.

The total amount of inorganic or organic fillers in the liquid crystal polymer composition of the present invention is preferably 1 to 200 parts by weight, more preferably 5 to 100 parts by weight, based on 100 parts by weight of the liquid crystal polymer. If the total amount of the inorganic or organic filler exceeds 200 parts by mass based on 100 parts by mass of the liquid crystal polymer, the moldability of the liquid crystal polymer composition tends to decrease, and the moldability of the cylinder or mold of the molding machine tends to deteriorate. There is a tendency for increased wear.

The liquid crystal polymer of the present invention may contain other additives, such as higher fatty acids, higher fatty acid esters, higher fatty acid amides, higher fatty acid metal salts (here, higher fatty acids are usually carbon mold release improvers such as polysiloxanes and fluororesins; colorants such as dyes and pigments; antioxidants; heat stabilizers; ultraviolet absorbers; antistatic agents; surfactants etc. may also be blended. These additives may be used alone or in combination of two or more.

The total amount of other additives in the liquid crystal polymer composition of the present invention is preferably 0.1 to 10 parts by weight, more preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the liquid crystal polymer. If the total amount of other additives exceeds 10 parts by mass based on 100 parts by mass of the liquid crystal polymer, the moldability of the liquid crystal polymer composition tends to decrease and the thermal stability tends to deteriorate.

In addition, when molding the liquid crystal polymer or liquid crystal polymer composition of the present invention, among the other additives mentioned above, additives having an external lubricant effect such as higher fatty acids, higher fatty acid esters, higher fatty acid metal salts, and fluorocarbon surfactants may be used. may be attached to the surface of the liquid crystal polymer pellet in advance.

The liquid crystal polymer of the present invention may contain other resin components. Examples of other resin components include polyamides, polyesters, polyolefins, polyacetals, polyphenylene ethers, and modified products thereof, thermoplastic resins such as polysulfone, polyethersulfone, polyetherimide, polyamideimide, phenolic resins, epoxy resins, Examples include thermosetting resins such as polyimide resins. Other resin components can be blended alone or in combination of two or more. The blending amount of other resin components is not particularly limited, and may be determined as appropriate depending on the use and purpose of the liquid crystal polymer. In one typical example, the total amount of other resin components is usually 0.1 to 100 parts by weight, particularly 0.5 to 80 parts by weight, based on 100 parts by weight of the liquid crystal polymer.

The melt viscosity of the liquid crystal polymer of the present invention is preferably 1 to 300 Pa·s, more preferably 5 ^to 100 Pa·s, even more preferably 10 ~50 Pa・s. Note that the lower the melt viscosity, the better the fluidity during molding.

The liquid crystal polymer of the present invention preferably has an Izod impact strength of 200 J/m or more, and has excellent mechanical strength. The Izod impact strength of the liquid crystal polymer of the present invention is more preferably 210 J/m or more, still more preferably 220 J/m or more, particularly preferably 240 J/m or more. The upper limit of Izod impact strength is not particularly limited, but is usually 620 J/m.

The liquid crystal polymer of the present invention has a tensile strength of preferably 190 MPa or more, more preferably 200 MPa or more, and still more preferably 210 MPa or more in a tensile strength test using an ASTM No. 4 dumbbell test piece. The upper limit of the tensile strength is, for example, 400 MPa, although it is not particularly limited.

In a bending test using a strip-shaped test piece (length 65 mm, width 12.7 mm, thickness 0.5 mm), the liquid crystal polymer of the present invention has a bending strength of preferably 160 MPa or more, more preferably 165 MPa or more, and Preferably it is 170 MPa or more. The upper limit of the bending strength is, for example, 400 MPa, although it is not particularly limited.

The liquid crystal polymer composition of the present invention is produced by adding inorganic or organic fillers, other additives, other resin components, etc. to a liquid crystal polymer, and then using a Banbury mixer, kneader, single screw or twin screw extruder, etc. It can be obtained by melting and kneading in a temperature range from near the crystal melting temperature of the liquid crystal polymer to 100° C. above the crystal melting temperature.

The liquid crystal polymer or liquid crystal polymer composition of the present invention thus obtained is processed into articles such as molded articles, films, or fibers by known processing methods such as injection molding, compression molding, extrusion molding, and blow molding.

The liquid crystal polymer or liquid crystal polymer composition of the present invention has improved mechanical strength such as Izod impact strength, and preferably has excellent mechanical properties, and is therefore particularly useful as electrical/electronic parts, mechanical mechanism parts, automobile parts, etc.

EXAMPLES Hereinafter, the present invention will be explained in detail with reference to Examples, but the present invention is not limited thereto.

Melt viscosity, tensile strength, bending strength and Izod impact strength in Examples were measured by the methods described below.

(1) Melt viscosity It was measured at 350° C. using a melt viscosity measuring device (Capillograph 1D manufactured by Toyo Seiki Co., Ltd.) using a 0.7 mmφ×10 mm capillary at a shear rate of 1000 sec ⁻¹ .

(2) Tensile strength Using an injection molding machine (UH1000-110 manufactured by Nissei Jushi Kogyo Co., Ltd.), an ASTM No. 4 dumbbell test piece was molded at a cylinder temperature of 350°C and a mold temperature of 70°C. Measured according to ASTM D638.

(3) Bending strength Injection molding was performed using an injection molding machine (MINIMAT M26/15 manufactured by Sumitomo Heavy Industries, Ltd.) with a mold clamping pressure of 15 tons at a cylinder temperature setting of 350°C and a mold temperature of 70°C, and a strip test was performed. A piece (length 65 mm x width 12.7 mm x thickness 2.0 mm) was produced. The bending test was a three-point bending test using INSTRON 5567 (a universal testing machine manufactured by Instron Japan Company Limited) in accordance with ASTM D790, with a span distance of 40.0 mm and a compression speed of 1.3 mm/min.

(4) Izod impact strength Using an injection molding machine (UH1000-110 manufactured by Nissei Jushi Kogyo Co., Ltd.), the cylinder temperature was set at 350°C, the mold temperature was 70°C, and the length was 127.0 mm, the width was 12.7 mm, and the thickness was 127.0 mm. A rectangular test piece with a length of 3.2 mm was molded. The center of this test piece was cut perpendicularly to the length direction to obtain a strip-shaped test piece with a length of 63.5 mm, a width of 12.7 mm, and a thickness of 3.2 mm, and measurements were made in accordance with ASTM D256.

In the Examples, the following abbreviations indicate the following compounds.
POB: 4-hydroxybenzoic acid BON6: 6-hydroxy-2-naphthoic acid

Furthermore, the following compounds were used as the compounds (polymerizable compounds) represented by formula (1).
A1: HOOC-(CH ₂ ) ₈ -COOH (sebacic acid)
A2: HOOC-(CH ₂ ) ₄ -COOH (adipic acid)
A3: HOOC-(CH ₂ ) ₁₀ -COOH (dodecanedioic acid)

[Example 1]
The following compounds were charged into a reaction vessel equipped with a stirring device equipped with a torque meter and a distillation tube, and acetic anhydride was added in an amount of 1.03 times the hydroxyl group amount (mol) of all monomers, and decomposition was carried out under the following conditions. Acetic acid polymerization was performed.
Sebacic acid: 13.1g (1.0 mol%)
POB: 213.7g (23.8 mol%)
BON6: 919.8g (75.2 mol%)

The temperature was raised from room temperature to 150° C. in 1 hour under a nitrogen gas atmosphere, and maintained at the same temperature for 30 minutes. Next, the temperature was rapidly raised to 210° C. while distilling off the by-produced acetic acid, and the temperature was maintained at the same temperature for 30 minutes. Thereafter, the temperature was raised to 350° C. over 4 hours, and then the pressure was reduced to 10 mmHg over 80 minutes. The polymerization reaction was terminated when a predetermined torque was exhibited, the contents of the reaction vessel were taken out, and pellets of liquid crystal polymer were obtained using a pulverizer. The amount of acetic acid distilled during the polymerization was almost the same as the theoretical value. Using the obtained pellets, melt viscosity, tensile strength, bending strength and Izod impact strength were measured by the above methods. The results are shown in Table 1.

[Examples 2-5, Comparative Examples 1-2]
Liquid crystal polymer pellets were prepared in the same manner as in Example 1, except that the compound represented by formula (1) (polymerizable compound), POB and BON6 were used in the proportions (mol%) shown in Table 1. Obtained. Using the obtained pellets, melt viscosity, tensile strength, bending strength and Izod impact strength were measured by the above methods. The results are shown in Table 1.

As shown in Table 1, the liquid crystal polymers of the present invention containing specific aliphatic dicarboxylic acids (Examples 1 to 5) have higher tensile strength and It is understood that the mechanical properties such as bending strength and Izod impact strength are improved and the mechanical strength is excellent.

Claims (5)

Formula (1)
HOOC-(CH ₂ ) _n -COOH...Formula (1)
[In the formula, n is an integer from 4 to 18]
The structural unit (A) derived from one or more polymerizable compounds selected from the group consisting of the compounds represented by and their reactive derivatives, the structural unit (B) derived from 4-hydroxybenzoic acid, and the 6- A liquid crystal polymer composed of a structural unit (C) derived from hydroxy-2-naphthoic acid, in which the structural unit (A) is 0.01 to 7% based on 100 mol% of the total structural units constituting the liquid crystal polymer. A liquid crystal polymer comprising 15 to 36 mol% of the structural unit (B) and 60 to 82 mol% of the structural unit (C). The compound represented by formula (1) is represented by formula (2)
HOOC-(CH ₂ ) ₈ -COOH...Formula (2)
The liquid crystal polymer according to claim 1, which is a compound represented by: The liquid crystal polymer according to claim 1 or 2, having an Izod impact strength of 200 J/m or more. A liquid crystal polymer composition comprising the liquid crystal polymer according to any one of claims 1 to 3 and an inorganic or organic filler. An article made of a molded article, film, or fiber obtained by processing the liquid crystal polymer according to any one of claims 1 to 3 or the liquid crystal polymer composition according to claim 4.