Liquid crystal polyester resin

Abstract

To provide a liquid crystal polyester resin which is excellent in flowability and moldability while maintaining mechanical strength.SOLUTION: A liquid crystal polyester resin includes repeating units represented by formulae [I] to [V] (wherein, p, q, r, s and t are composition ratios (mol%) in liquid crystal polyester resins of the respective repeating units, and satisfy the following conditions: 15≤p≤30, 5≤q≤25, 15≤r≤35, 10≤s≤30, 10≤t≤30, q<r and p+q+r+s+t=100).SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a liquid crystal polyester resin having excellent flowability and moldability while maintaining mechanical strength. [Background technology]

[0002] Liquid crystal polyester has good fluidity and is less likely to produce burrs. It also has excellent heat resistance, mechanical properties such as rigidity, chemical resistance, and dimensional accuracy, so its use is increasing in electrical and electronic components with complex shapes.

[0003] In recent years, with the rapid growth of information technology (IT), the information and communications fields have seen progress in the trend toward higher integration, smaller size, thinner wall thickness, and lower profile of electric and electronic components, resulting in many cases of extremely thin sections of 0.5 mm or less, and good fluidity is required to completely fill such sections (thin sections). Generally, liquid crystal polyesters have superior fluidity compared to other resins, but when such thin sections are required, there is a demand for further improvements in fluidity while maintaining mechanical strength.

[0004] It is known that the fluidity of liquid crystal polyester can be improved by lowering the melt viscosity or blending with a filler or other resin. For example, a liquid crystal polyester resin composition having excellent fluidity and consisting of a liquid crystal polyester resin having a melt viscosity of not more than a certain level and a plate-like or granular filler (Patent Document 1), a liquid crystal polyester resin composition having improved fluidity and consisting of 0.5 to 10 parts by weight of an oligomer mainly composed of a repeating unit of p-hydroxybenzoic acid added to 100 parts by weight of liquid crystal polyester (Patent Document 2), and the like have been proposed. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP-A-1-197555 [Patent Document 2] Japanese Patent Application Publication No. 3-095260 Summary of the Invention [Problem to be solved by the invention]

[0006] However, although these methods improve fluidity, when the injection molding temperature is increased to produce thinner molded products, there is a risk of the resin dripping from the nozzle during injection molding (also known as drooling), or of the product becoming difficult to release from the mold when the mold is opened, resulting in problems with molding processability.

[0007] An object of the present invention is to provide a liquid crystal polyester resin which is excellent in flowability and moldability while maintaining mechanical strength. [Means for solving the problem]

[0008] In view of the above problems, the inventors conducted intensive research and discovered that by using a specific repeating unit as a constituent component, a liquid crystal polyester resin having excellent flowability and moldability while maintaining mechanical strength can be obtained, thereby completing the present invention.

[0009] That is, the present invention includes the following preferred embodiments. [1] Formula [I]~[V] [ka] [In the formula, p, q, r, s and t each represent a composition ratio (mol %) of each repeating unit in the liquid crystal polyester resin, and satisfy the following conditions: 15≦p≦30, 5≦q≦25, 15≦r≦35, 10≦s≦30, 10≦t≦30, q <r、 p+q+r+s+t=100] A liquid crystal polyester resin comprising a repeating unit represented by the formula: [2] The liquid crystal polyester resin according to [1], wherein r / q satisfies 1.05 to 5.0. [3] Shearing rate 1000sec -1 The liquid crystal polyester resin according to [1] or [2] has a melt viscosity of 1 to 200 Pa·s at a crystal melting temperature +17 to 23°C measured under the conditions of [4] The liquid crystal polyester resin according to any one of [1] to [3], which has a flow length of 10 to 40 mm. [5] A liquid crystal polyester resin composition comprising the liquid crystal polyester resin according to any one of [1] to [4] and an inorganic filler and / or an organic filler. [6] The liquid crystal polyester resin composition according to [5], wherein the inorganic filler and / or the organic filler is at least one selected from the group consisting of glass fiber, silica alumina fiber, alumina fiber, carbon fiber, potassium titanate fiber, aluminum borate fiber, aramid fiber, talc, mica, graphite, wollastonite, dolomite, clay, glass flakes, glass beads, glass balloons, calcium carbonate, barium sulfate, and titanium oxide. [7] An article made of a molded article, a film or a fiber, which is composed of the liquid crystal polyester resin according to any one of [1] to [4] or the liquid crystal polyester resin composition according to [5] or [6]. Effect of the Invention

[0010] According to the present invention, a liquid crystal polyester resin having excellent flowability and moldability while maintaining mechanical strength can be obtained. [Brief description of the drawings]

[0011] [Figure 1] FIG. 2 is a schematic diagram of a dumbbell-shaped test piece used in the tensile strength tests of the Examples and Comparative Examples. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The liquid crystal polyester resin of the present invention is a liquid crystal polyester resin that forms an anisotropic molten phase, which is called a thermotropic liquid crystal polyester resin by those skilled in the art.

[0013] The nature of the anisotropic molten phase of the liquid crystal polyester resin can be confirmed by a conventional polarizing inspection method using cross polarizers, that is, by observing a sample placed on a hot stage under a nitrogen atmosphere.

[0014] The liquid crystal polyester resin of the present invention is represented by the formulas [I] to [V] [ka] [In the formula, p, q, r, s and t each represent a composition ratio (mol %) of each repeating unit in the liquid crystal polyester resin, and satisfy the following conditions: 15≦p≦30, 5≦q≦25, 15≦r≦35, 10≦s≦30, 10≦t≦30, q <r、 p+q+r+s+t=100] The polymer is constituted by a repeating unit represented by the formula:

[0015] The composition ratio p in the formula [I] is 15 to 30 mol %, preferably 16 to 24 mol %, more preferably 18 to 22 mol %, further preferably 19 to 21 mol %, and particularly preferably 19.5 to 20.5 mol %.

[0016] If the repeating unit represented by formula [I] is less than 15 mol %, it is difficult to maintain mechanical strength, whereas if it exceeds 30 mol %, the crystal melting temperature decreases, resulting in poor heat resistance.

[0017] Specific examples of monomers that provide the repeating unit represented by formula [I] include 4-hydroxybenzoic acid and its ester-forming derivatives such as acylation products, ester derivatives and acid halides.

[0018] The composition ratio q in the formula [II] is 5 to 25 mol %, preferably 7 to 20 mol %, more preferably 8 to 15 mol %, further preferably 9 to 12 mol %, and particularly preferably 9.5 to 11 mol %.

[0019] Specific examples of monomers which provide the repeating unit represented by formula [II] include hydroquinone and its acylated and other ester-forming derivatives.

[0020] The composition ratio r in the formula [III] is 15 to 35 mol %, preferably 20 to 33 mol %, more preferably 25 to 32 mol %, further preferably 27 to 31 mol %, and particularly preferably 29 to 30.5 mol %.

[0021] Specific examples of monomers which provide the repeating unit represented by formula [III] include 4,4'-dihydroxybiphenyl and its acylated and other ester-forming derivatives.

[0022] The composition ratio s in the formula [IV] is 10 to 30 mol %, preferably 15 to 28 mol %, more preferably 18 to 26 mol %, further preferably 19 to 22 mol %, and particularly preferably 19.5 to 20.5 mol %.

[0023] Specific examples of monomers which provide the repeating unit represented by formula [IV] include terephthalic acid and its ester-forming derivatives such as ester derivatives and acid halides.

[0024] The composition ratio t in the formula [V] is 10 to 30 mol %, preferably 15 to 28 mol %, more preferably 18 to 26 mol %, further preferably 19 to 22 mol %, and particularly preferably 19.5 to 20.5 mol %.

[0025] Specific examples of monomers that provide the repeating unit represented by formula [V] include 2,6-naphthalenedicarboxylic acid and its ester-forming derivatives such as ester derivatives and acid halides.

[0026] The composition ratio q according to formula [II] and the composition ratio r according to formula [III] satisfy q < r, and r / q is preferably from 1.05 to 5.0, more preferably from 1.5 to 4.5, still more preferably from 2.0 to 4.0, and particularly preferably from 2.5 to 3.5.

[0027] The total [p + q + r + s + t] of the composition ratios of the repeating units in the liquid crystal polyester resin of the present invention is preferably 100 mol%, but other repeating units may be further contained within a range not impairing the object of the present invention.

[0028] Examples of the monomer that provides other repeating units include other aromatic hydroxycarboxylic acids, aromatic diols, aromatic dicarboxylic acids, aromatic hydroxyamines, aromatic diamines, aromatic aminocarboxylic acids, aromatic hydroxydicarboxylic acids, aliphatic diols, aliphatic dicarboxylic acids, aromatic mercaptocarboxylic acids, aromatic dithiols, aromatic mercaptophenols, and combinations thereof.

[0029] The total of the composition ratios of the repeating units provided by these other monomer components is preferably 10 mol% or less in the whole repeating units.

[0030] Hereinafter, the method for producing the liquid crystal polyester resin of the present invention will be described.

[0031] The method for producing the liquid crystal polyester resin of the present invention is not particularly limited, and known polycondensation methods for forming an ester bond with the above monomer components, such as a melt acidolysis method and a slurry polymerization method, can be used.

[0032] The melt acidolysis method is a method suitable for producing the liquid crystal polyester resin of the present invention. In this method, first, the monomers are heated to form a melt of the reactants, and the reaction is continued to obtain a molten polyester. In addition, a vacuum may be applied to facilitate the removal of volatile substances (such as acetic acid and water) by-produced in the final stage of condensation.

[0033] A slurry polymerization process is a process in which the reaction is carried out in the presence of a heat exchange fluid, and a solid product is obtained in suspension in the heat exchange medium.

[0034] In both the melt acidolysis method and the slurry polymerization method, the polymerizable monomer component used in producing the liquid crystal polyester resin can be subjected to the reaction in a modified form in which the hydroxyl group is acylated, that is, as a lower acylated product, at room temperature. The lower acyl group preferably has 2 to 5 carbon atoms, more preferably has 2 or 3 carbon atoms. Particularly preferred is a method in which an acetylated product of the monomer component is used in the reaction.

[0035] The lower acylated monomer may be one which has been previously synthesized by separate acylation, or may be produced in the reaction system by adding an acylating agent such as acetic anhydride to the monomer during the production of the liquid crystal polyester resin.

[0036] In either the molten acidolysis method or the slurry polymerization method, a catalyst may be used in the reaction, if necessary.

[0037] Specific examples of catalysts include organotin compounds (dialkyltin oxides such as dibutyltin oxide, diaryltin oxides, etc.), titanium dioxide, antimony trioxide, organotitanium compounds (alkoxytitanium silicates, titanium alkoxides, etc.), alkali and alkaline earth metal salts of carboxylic acids (potassium acetate, sodium acetate, etc.), Lewis acids (BF3, etc.), gaseous acid catalysts such as hydrogen halides (HCl, etc.), and the like.

[0038] The amount of the catalyst used is preferably from 10 to 1000 ppm, more preferably from 20 to 200 ppm, based on the mass of the monomer.

[0039] The liquid crystal polyester resin obtained by such a polycondensation reaction is discharged in a molten state from a polymerization reaction tank, and then processed into pellets, flakes, or powder, and is subjected to molding or melt kneading.

[0040] The liquid crystal polyester resin in the form of pellets, flakes, or powder may be heat-treated in a substantially solid state under reduced pressure, vacuum, or an atmosphere of an inert gas such as nitrogen or helium, in order to increase the molecular weight and improve the heat resistance.

[0041] The temperature of the heat treatment is not particularly limited as long as the liquid crystal polyester resin does not melt, but is preferably 260 to 350°C, and more preferably 280 to 320°C.

[0042] The melt viscosity of the liquid crystal polyester resin of the present invention (measured with a capillary rheometer, crystal melting temperature + 17 to 23°C, 1000 s -1 ) is preferably from 1 to 200 Pa·s, more preferably from 5 to 100 Pa·s, even more preferably from 10 to 80 Pa·s, and particularly preferably from 25 to 40 Pa·s.

[0043] If the melt viscosity is less than 1 Pa·s, drooling and stringiness tend to occur, and if it exceeds 200 Pa·s, the mechanical strength tends to decrease.

[0044] The flow length of the liquid crystal polyester resin of the present invention is preferably 10 to 40 mm, more preferably 13 to 30 mm, further preferably 17 to 25 mm, and particularly preferably 19 to 22 mm. The flow length in this specification is a value measured by the measurement method described in the Examples below.

[0045] The liquid crystal polyester resin of the present invention obtained as described above can be made into a liquid crystal polyester resin composition containing an inorganic filler and / or an organic filler, additives, other resin components, and the like.

[0046] Specific examples of inorganic fillers and / or organic fillers that may be contained in the liquid crystal polyester resin composition of the present invention include glass fibers, silica alumina fibers, alumina fibers, carbon fibers, potassium titanate fibers, aluminum borate fibers, aramid fibers, talc, mica, graphite, wollastonite, dolomite, clay, glass flakes, glass beads, glass balloons, calcium carbonate, barium sulfate, titanium oxide, etc. These fillers may be used alone or in combination of two or more.

[0047] Among these, talc and glass fiber are preferred because they have an excellent balance between mechanical properties and cost.

[0048] When an inorganic filler and / or an organic filler is contained, the content thereof is preferably 1 to 150 parts by mass, and more preferably 10 to 100 parts by mass, based on 100 parts by mass of the liquid crystal polyester resin.

[0049] When the content of the inorganic filler and / or the organic filler is 1 part by mass or more, the liquid crystal polyester resin composition is likely to have an improved mechanical strength. When the content of the inorganic filler and / or the organic filler exceeds 150 parts by mass, the fluidity tends to decrease.

[0050] Specific examples of other additives that may be contained in the liquid crystal polyester resin composition of the present invention include lubricants such as higher fatty acids, higher fatty acid esters, higher fatty acid amides, and higher fatty acid metal salts (here, higher fatty acids refer to those having 10 to 25 carbon atoms), release agents such as polysiloxanes and fluororesins, colorants such as dyes, pigments, and carbon black, flame retardants, antistatic agents, surfactants, antioxidants such as phosphorus-based antioxidants, phenol-based antioxidants, and sulfur-based antioxidants, weathering agents, heat stabilizers, and neutralizing agents. These additives may be used alone or in combination of two or more.

[0051] When these additives are contained, the total content thereof is preferably 0.01 to 10 parts by mass, and more preferably 0.1 to 3 parts by mass, based on 100 parts by mass of the total amount of the liquid crystal polyester resin.

[0052] When an additive is added to express a function, if the content is less than 0.01 parts by mass, the function of the additive tends to be difficult to realize, and if the content exceeds 10 parts by mass, the thermal stability of the liquid crystal polyester resin composition during molding processing tends to be poor.

[0053] Furthermore, when additives such as lubricants and release agents are used among the above other additives, they may be added when preparing the liquid crystal polyester resin composition, or may be attached to the pellet surface of the liquid crystal polyester resin during molding processing.

[0054] Specific examples of other resin components that may be contained in the liquid crystal polyester resin composition of the present invention include thermoplastic resins such as polyamide, polyester, polyacetal, polyphenylene ether and its modified products, polysulfone, polyethersulfone, polyetherimide, polyamideimide, etc., and thermosetting resins such as phenol resin, epoxy resin, polyimide resin, etc. These resin components may be used alone or in combination of two or more kinds.

[0055] When the other resin component is contained, the content thereof is preferably 0.1 to 100 parts by mass, and more preferably 0.5 to 80 parts by mass, based on 100 parts by mass of the liquid crystal polyester resin.

[0056] The liquid crystal polyester resin composition can be obtained by mixing a liquid crystal polyester resin with an inorganic filler and / or a filler, additives or other resin components, and melt-kneading the mixture under temperature conditions ranging from near the crystalline melting temperature of the liquid crystal polyester resin to the crystalline melting temperature + 50°C using a Banbury mixer, kneader, single-screw or twin-screw extruder or the like.

[0057] The liquid crystal polyester resin or liquid crystal polyester resin 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.

[0058] The present invention will be described in detail below with reference to examples, but the present invention is not limited thereto. EXAMPLES

[0059] In the examples, the physical properties were measured by the following methods.

[0060] <Crystal Melting Temperature> The measurement was carried out using a differential scanning calorimeter (DSC) Exstar6000 manufactured by Seiko Instruments Inc. The liquid crystal polymer sample was heated from 40°C to 375°C at a temperature increase rate of 20°C / min, and then held for 10 minutes. Next, the sample was cooled to 50°C at a temperature decrease rate of 20°C / min, and then measured again at a temperature increase rate of 20°C / min up to 375°C. The endothermic peak was observed, and the temperature showing the peak top was taken as the crystalline melting temperature of the liquid crystal polymer. In addition, when multiple peaks were observed, the side with the larger peak area (the side with the larger melting enthalpy) was taken as the crystalline melting temperature.

[0061] <Melt Viscosity> The melt viscosity was measured using a melt viscosity measuring device (Toyo Seiki Co., Ltd., Capillograph 1D) with a capillary of 0.7 mm diameter x 10 mm at a shear rate of 1000 sec -1 Under the above conditions, the melt viscosity was measured at the measurement temperatures shown in Table 2 (crystal melting temperature +13 to 23° C.).

[0062] <Flow length (fluidity)> A rectangular barflow test piece measuring 50.0 mm in length, 2.0 mm in width, and 0.2 mm in thickness was used, and injection molding was performed using an injection molding machine (Nissei Plastic Industrial Co., Ltd., NEX-15-1E) under the molding conditions shown in Table 1. The flow length was measured when the material was filled into a barflow mold. The longer the flow length, the better the fluidity.

[0063] [Table 1]

[0064] Tensile strength Using an injection molding machine (MINIMAT M26 / 15 manufactured by Sumitomo Heavy Industries, Ltd.) with a clamping pressure of 15t, injection molding was performed at the cylinder temperature shown in Table 2 and the mold temperature was 70°C to obtain dumbbell-shaped test pieces with a thickness of 2.0 mm as shown in Figure 1. Tensile tests were performed using an INSTRON5567 (a universal testing machine manufactured by Instron Japan Co., Ltd.) with a span distance of 25.4 mm and a tensile speed of 5 mm / min.

[0065] <Bending strength> Using an injection molding machine (MINIMAT M26 / 15 manufactured by Sumitomo Heavy Industries, Ltd.) with a clamping pressure of 15t, injection molding was performed at the cylinder temperature shown in Table 2, and the mold temperature was 70°C to prepare rectangular test pieces (length 65 mm x width 12.7 mm x thickness 2.0 mm). A three-point bending test was performed using an INSTRON5567 (a universal testing machine manufactured by Instron Japan Co., Ltd.) in accordance with ASTM D790, with a span distance of 40.0 mm and a compression speed of 1.3 mm / min.

[0066] <Izod impact strength> Using an injection molding machine (MINIMAT M26 / 15 manufactured by Sumitomo Heavy Industries, Ltd.) with a clamping pressure of 15 t, injection molding was performed at the cylinder temperature shown in Table 2 and the mold temperature of 70°C. Strip-shaped test pieces (length 65 mm x width 12.7 mm x thickness 2.0 mm) were prepared and notched, and then measured in accordance with ASTM D256.

[0067] <Dripping and stringiness> When measuring the flow length (fluidity) using an injection molding machine (Nissei Plastic Industrial Co., Ltd., NEX-15-1E), the occurrence of sagging and stringing was visually confirmed. Those in which each phenomenon occurred were rated as "X", and those in which they did not occur were rated as "O". Those in which sagging and stringing did not occur had better handleability during molding, i.e., better moldability.

[0068] In the examples, the following abbreviations represent the following compounds. LCP: Liquid crystal polymer POB: 4-hydroxybenzoic acid HQ: Hydroquinone BP: 4,4´-dihydroxybiphenyl TPA: Terephthalic acid NDA: 2,6-naphthalenedicarboxylic acid

[0069] [Example 1] In a reaction vessel equipped with a torque meter-equipped stirrer and a distillation tube, POB, HQ, BP, TPA and NDA were charged in a total amount of 6.5 moles in the composition ratio shown below, and 1.05 times the moles of acetic anhydride relative to the amount of hydroxyl groups (moles) of all monomers was charged, and deacetic acid polymerization was performed under the following conditions. The temperature was raised from room temperature to 150°C over 1 hour in a nitrogen gas atmosphere and held at the same temperature for 30 minutes. Next, the temperature was raised quickly to 210°C while distilling off the by-product acetic acid, and held at the same temperature for 30 minutes. After that, the temperature was raised to 350°C over 3 hours, and the pressure was reduced to 20 mmHg over 30 minutes. The polymerization reaction was terminated when a predetermined torque was indicated, the contents were removed from the reaction vessel, and pellets of liquid crystal polymer 1 were obtained using a pulverizer. The amount of acetic acid distilled during polymerization was almost the theoretical value. The physical properties of the obtained LCP were measured. The results are shown in Table 2. POB: 179.8g (20 mol%) HQ: 71.7g (10 mol%) BP: 363.8g (30 mol%) TPA: 216.1 g (20 mol%) NDA: 281.2 g (20 mol%)

[0070] [Examples 2 to 7, Comparative Examples 1 to 4] LCPs were obtained in the same manner as in Example 1, except that the raw material monomers were charged in the mole percentages shown in Table 2. The physical properties of each of the obtained LCPs were measured. The results are shown in Table 2.

[0071] [Comparative Example 5] Polymerization was carried out in the same manner as in Example 1, except that the raw material monomers were charged so as to have the mole percentages shown in Table 2. However, stirring became difficult due to an increase in torque, and the reaction was discontinued.

[0072] As is clear from Table 2, it can be understood that the liquid crystal polyester resins obtained in Examples 1 to 7 are excellent in flowability and molding processability.

[0073] [Table 2]

Claims

1. Formulas [I] to [V] 【Chemical 1】 [wherein, p, q, r, s and t are each the composition ratio (mol%) in the liquid crystal polyester resin of each repeating unit, and satisfy the following conditions: 15 ≤ p ≤ 30, 5 ≤ q ≤ 25, 15 ≤ r ≤ 35, 10 ≤ s ≤ 30, 10 ≤ t ≤ 30, q < r, p + q + r + s + t = 100] A liquid crystal polyester resin comprising repeating units represented by the formula.

2. The liquid crystal polyester resin according to Claim 1, wherein r / q satisfies 1.05 to 5.

0.

3. Cutting speed: 1000 sec －１ The liquid crystal polyester resin according to claim 1, wherein the melt viscosity at a temperature of the crystal melting temperature + 17 to 23°C measured under the conditions of －１ is 1 to 200 Pa·s.

4. The liquid crystal polyester resin according to Claim 1, wherein the flow length is 10 to 40 mm.

5. A liquid crystal polyester resin composition comprising the liquid crystal polyester resin according to Claim 1 and an inorganic filler and / or an organic filler.

6. An article made of a molded product, a film or a fiber, which is 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.

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