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 that maintains mechanical strength while having excellent fluidity and molding processability.

Background Art

[0002] Liquid crystal polyester has characteristics such as good fluidity and low burr formation, and is also excellent in mechanical properties such as heat resistance and rigidity, chemical resistance, dimensional accuracy, etc. Therefore, in electrical and electronic parts having complex shapes, its usage amount is increasing.

[0003] In recent years, with the rapid growth of information technology (IT), in the information and communication field, the high integration, miniaturization, thinning, and low profile of electrical and electronic parts have been progressing. There are many cases where very thin parts of 0.5 mm or less are formed, and in such parts (thin parts), good fluidity is required so that the resin can be completely filled. Generally, liquid crystal polyester has better fluidity than other resins, but when such thinning is required, further improvement in fluidity is required while maintaining mechanical strength.

[0004] It is known that the fluidity of liquid crystal polyester can be improved by reducing the melt viscosity or blending with a filler or other resin. For example, a liquid crystal polyester resin composition having excellent fluidity composed of a liquid crystal polyester resin having a specific melt viscosity or less and a plate-like or granular filler (Patent Document 1), and a liquid crystal polyester resin composition with improved fluidity obtained by adding 0.5 to 10 parts by weight of an oligomer mainly composed of repeating units of p-hydroxybenzoic acid to 100 parts by weight of liquid crystal polyester (Patent Document 2), etc. have been proposed.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

[0006] However, while these methods improve fluidity, increasing the injection molding temperature to mold even thinner parts can lead to problems with moldability, such as the dripping phenomenon (also known as the drooping phenomenon) where resin drips from the nozzle during injection molding, and the stringing phenomenon which results in poor release properties of the product when the mold is opened.

[0007] The object of the present invention is to provide a liquid crystal polyester resin that maintains mechanical strength while exhibiting excellent fluidity and moldability. [Means for solving the problem]

[0008] In view of the above problems, the inventors of the present invention conducted diligent studies and found that by using specific repeating units as constituent components, a liquid crystal polyester resin with excellent fluidity and moldability while maintaining mechanical strength can be obtained, thus completing the present invention.

[0009] In other words, the present invention encompasses the following preferred embodiments. [1] Formula [I]~[V] [ka] [In the formula, p, q, r, s, and t are the composition ratios (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 composed of repeating units represented by [a specific symbol]. [2] A liquid crystal polyester resin as described in [1], where r / q is 1.05 to 5.0. [3] Shearing rate 1000sec -1 A liquid crystal polyester resin according to [1] or [2], wherein the melt viscosity at a crystal melting temperature of +17 to 23°C, measured under the following conditions, is 1 to 200 Pa·s. [4] A liquid crystal polyester resin according to any of [1] to [3], wherein the flow length is 10 to 40 mm. A liquid crystal polyester resin composition comprising a liquid crystal polyester resin described in any of [5][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 organic filler is one or more 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 dioxide. Articles consisting of molded articles, films, or fibers made from a liquid crystal polyester resin described in any of [7][1] to [4] or a liquid crystal polyester resin composition described in [5] or [6]. [Effects of the Invention]

[0010] According to the present invention, a liquid crystal polyester resin with excellent fluidity and moldability can be obtained while maintaining mechanical strength. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic diagram of the dumbbell-shaped test specimens used in the tensile strength tests of the examples and comparative examples. [Modes for carrying out the invention]

[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 properties of the anisotropic molten phase of the liquid crystal polyester resin can be confirmed by a normal polarization inspection method using a crossed polarizer, 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 has the formulas [I] to [V]

Chemical formula

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

[0016] When the repeating unit represented by the formula [I] is less than 15 mol%, it is difficult to maintain the mechanical strength, and when it exceeds 30 mol%, the heat resistance deteriorates due to the decrease in the crystal melting temperature.

[0017] Specific examples of the monomer that gives the repeating unit represented by the formula [I] include, for example, 4-hydroxybenzoic acid, and ester-forming derivatives such as acylates, ester derivatives, and acid halides thereof.

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

[0019] Specific examples of monomers that give repeating units represented by formula [II] include hydroquinone and ester-forming derivatives thereof such as its acylated compounds.

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

[0021] Specific examples of monomers that give repeating units represented by formula [III] include 4,4'-dihydroxybiphenyl and ester-forming derivatives thereof such as its acylated compounds.

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

[0023] Specific examples of monomers that give repeating units represented by formula [IV] include terephthalic acid, as well as its ester derivatives and ester-forming derivatives such as acid halides.

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

[0025] Specific examples of monomers that give repeating units represented by formula [V] include 2,6-naphthalenedicarboxylic acid, as well as ester-forming derivatives thereof, acid halides, and other ester-forming derivatives.

[0026] The composition ratio q according to formula [II] and the composition ratio r according to formula [III] satisfy q < r, and it is preferable that r / q is 1.05 to 5.0, more preferably 1.5 to 4.5, even more preferably 2.0 to 4.0, and particularly preferably 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, a slurry polymerization method, etc. can be used.

[0032] The melt acidolysis method is a method suitable for producing the liquid crystal polyester resin of the present invention. This method first heats the monomer to form a melt of the reactants, and obtains a melt polyester by continuing the reaction. In addition, a vacuum may be applied to facilitate the removal of volatile by-products (such as acetic acid, water, etc.) generated in the final stage of condensation.

[0033] Slurry polymerization is a method in which a reaction is carried out in the presence of a heat exchange fluid, and the solid product is obtained in a suspended state in the heat exchange medium.

[0034] In both the molten acidolysis method and the slurry polymerization method, the polymerizable monomer components used in the production of liquid crystal polyester resin can also be used in the reaction at room temperature as a modified form in which the hydroxyl group is acylated, i.e., a lower acyled. 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 in which the acetylated monomer component is used in the reaction.

[0035] The lower acylated monomers may be synthesized beforehand by acylation, or they can be generated in the reaction system during the production of liquid crystal polyester resin by adding an acylation agent such as acetic anhydride to the monomer.

[0036] In either the molten acidolysis method or the slurry polymerization method, a catalyst may be used during the reaction as needed.

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

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

[0039] The liquid crystal polyester resin obtained by this polycondensation reaction is removed from the polymerization reactor in a molten state and then processed into pellets, flakes, or powder, which are then subjected to molding or melt kneading.

[0040] Liquid crystal polyester resins in pellet, flake, or powder form may be heat-treated in a substantially solid state under reduced pressure, under vacuum, or in an atmosphere of an inert gas such as nitrogen or helium, in order to increase their molecular weight and improve their heat resistance.

[0041] The heat treatment temperature is not particularly limited as long as the liquid crystal polyester resin does not melt, but is preferably 260 to 350°C, 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 + 17~23°C, 1000 s) -1 The pressure is preferably 1 to 200 Pa·s, more preferably 5 to 100 Pa·s, even more preferably 10 to 80 Pa·s, and particularly preferably 25 to 40 Pa·s.

[0043] When the melt viscosity is less than 1 Pa·s, drooping and stringing phenomena tend to occur more easily, and when 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, even more preferably 17 to 25 mm, and particularly preferably 19 to 22 mm. The flow length in this specification is the 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 a liquid crystal polyester resin composition containing inorganic fillers and / or organic fillers, additives, or other resin components.

[0046] Specific examples of inorganic and / or organic fillers that may be contained in the liquid crystal polyester resin composition of the present invention include, for example, 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 dioxide, and the like. These fillers may be used alone or in combination of two or more.

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

[0048] If inorganic fillers and / or organic fillers are included, their content is preferably 1 to 150 parts by mass, and more preferably 10 to 100 parts by mass, per 100 parts by mass of liquid crystal polyester resin.

[0049] When the inorganic filler and / or organic filler content is 1 part by mass or more, an improvement in mechanical strength is easily obtained for the liquid crystal polyester resin composition. When the inorganic filler and / or organic filler content exceeds 150 parts by mass, 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, for example, lubricants such as higher fatty acids, higher fatty acid esters, higher fatty acid amides, and higher fatty acid metal salts (where higher fatty acids refer to those with 10 to 25 carbon atoms), mold 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 individually or in combination of two or more.

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

[0052] When additives are added to achieve a specific function, if their content is less than 0.01 parts by mass, the function of the additive tends to be difficult to realize, and if it exceeds 10 parts by mass, the thermal stability of the liquid crystal polyester resin composition during molding tends to deteriorate.

[0053] Furthermore, when using other additives such as lubricants and release agents, they may be added when preparing the liquid crystal polyester resin composition, or they may be attached to the surface of the liquid crystal polyester resin pellets during the molding process.

[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, and polyamideimide, as well as thermosetting resins such as phenolic resin, epoxy resin, and polyimide resin. These resin components may be used individually or in combination of two or more.

[0055] If other resin components are included as described above, their content is preferably 0.1 to 100 parts by mass, and more preferably 0.5 to 80 parts by mass, per 100 parts by mass of liquid crystal polyester resin.

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

[0057] The liquid crystal polyester resin or liquid crystal polyester resin composition obtained in this manner 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] Each physical property value in the examples was measured by the following method.

[0060] <Crystal melting temperature> Measurements were performed using a differential scanning calorimeter (DSC) Exstar6000 manufactured by Seiko Instruments Inc. A liquid crystal polymer sample was heated from 40°C to 375°C under a heating rate of 20°C / min, and then held for 10 minutes. Next, the sample was cooled to 50°C under a cooling rate of 20°C / min, and then measured again under a heating rate of 20°C / min to 375°C. The endothermic peak observed at this temperature was defined as the crystal melting temperature of the liquid crystal polymer. If multiple peaks were observed, the peak with the larger area (higher enthalpy of melting) was considered the crystal melting temperature.

[0061] <Melting viscosity> Using a melt viscosity measuring device (Capillograph 1D, manufactured by Toyo Seiki Co., Ltd.), a 0.7 mmφ × 10 mm capillary was measured at a shear rate of 1000 sec. -1 Under these 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 bar flow type test specimen measuring 50.0 mm in length, 2.0 mm in width, and 0.2 mm in thickness was used. Injection molding was performed using an injection molding machine (NEX-15-1E, manufactured by Nissei Plastic Industrial Co., Ltd.) under the molding conditions shown in Table 1, and the flow length was measured when the specimen was filled into the bar flow mold. A longer flow length indicates better fluidity.

[0063] [Table 1]

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

[0065] <Bending strength> Using an injection molding machine with a clamping pressure of 15t (MINIMAT M26 / 15 manufactured by Sumitomo Heavy Industries, Ltd.), injection molding was performed with the cylinder temperature set to the molding temperature shown in Table 2 and the mold temperature to 70°C to produce strip-shaped test pieces (length 65mm × width 12.7mm × thickness 2.0mm). Bending tests were performed using a three-point bending test machine (INSTRON 5567, Instron Japan Company Limited) in accordance with ASTM D790, with a span distance of 40.0mm and a compression speed of 1.3mm / min.

[0067] <Runny nose and stringy nose> When measuring the flow length (fluidity) using an injection molding machine (NEX-15-1E, manufactured by Nissei Plastic Industrial Co., Ltd.), the occurrence of smudging and stringing was visually confirmed. Cases where these phenomena occurred were marked with "×", and cases where they did not occur were marked with "○". The absence of smudging and stringing indicates better handling 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 distillation tube, POB, HQ, BP, TPA, and NDA were charged in the composition ratios shown below to a total amount of 6.5 moles. Acetic anhydride was then added at a concentration of 1.05 moles relative to the total amount of hydroxyl groups (moles) of the monomers, and deacetic acid polymerization was carried out under the following conditions: The mixture was heated from room temperature to 150°C over 1 hour under a nitrogen gas atmosphere and held at that temperature for 30 minutes. Next, the temperature was rapidly increased to 210°C while distilling off the by-product acetic acid and held at that temperature for 30 minutes. Afterward, the temperature was increased to 350°C over 3 hours, and then the pressure was reduced to 20 mmHg over 30 minutes. The polymerization reaction was terminated when the predetermined torque was reached, 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 approximately as per 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: 216.1g (20 mol%) NDA: 281.2g (20 mol%)

[0070] [Examples 2-7, Comparative Examples 1-4] LCP was obtained in the same manner as in Example 1, except that the raw material monomers were charged to the molar percentages shown in Table 2. Each physical property of the obtained LCP was 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 monomer raw materials were added in the molar percentages shown in Table 2. However, stirring became difficult due to increased torque, and the reaction was stopped.

[0072] As is clear from Table 2, the liquid crystal polyester resins obtained in Examples 1 to 7 exhibit excellent fluidity and moldability.

[0073] Table 2

Claims

1. Formulas [I] to [V] 【Chemistry 1】 [In the formula, p, q, r, s, and t are the composition ratios (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, 15 ≤ s ≤ 30, 10 ≤ t ≤ 30, q < r, p+q+r+s+t=100] A liquid crystal polyester resin composed of repeating units represented by [a specific symbol].

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

0.

3. Shearing rate 1000sec －１ The liquid crystal polyester resin according to claim 1, wherein the melt viscosity at the crystal melting temperature + 17 to 23°C, measured under the specified conditions, 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 described in claim 1 and an inorganic filler and / or an organic filler.

6. An article comprising a molded article, a film, or fibers, which is made from a liquid crystal polyester resin according to any one of claims 1 to 4 or a liquid crystal polyester resin composition according to claim 5.

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