FLUORINE-CONTAINING RESIN COMPOSITION AND METHOD FOR ITS PREPARATION

Description

TECHNICAL FIELD

[0001] The disclosure relates to fluororesin-containing compositions and methods for producing the same.BACKGROUND ART

[0002] JP-A-1990-110156 discloses a composition containing a fluororesin and a thermotropic liquid crystal polymer. Unfortunately, the compositions discussed in the examples contain a thermotropic liquid crystal polymer in an amount of at least 10% by mass and only mechanical properties are evaluated.

[0003] JP-A-1990-32147 discloses a composition containing a fluororesin and a thermotropic liquid crystal polymer. Unfortunately, disclosed is only a composition containing a thermotropic liquid crystal polymer in an amount of 40-60 mass%.

[0004] JP-A-1988-230756 discloses a composition containing a fluororesin and a thermotropic liquid crystal polymer. Unfortunately, disclosed is only a composition containing a thermotropic liquid crystal polymer in an amount of 20-80 mass%.

[0005] JP-A-1981-115357 discloses a composition containing a thermotropic liquid crystal polymer and a plastic such as a commodity plastic or an engineering plastic. However, it discloses the amount of the thermotropic liquid crystal polymer as 3-90 mass% and fails to mention fluororesins.

[0006] WO 2013 / 049620 discloses a polymeric article comprising a melt-processable blend of a melt-viscid fluoropolymer and a liquid crystalline polymer (LCP), preferably at a wt. / wt.-ratio of ≤ (99:1). The melt-viscid fluoropolymer preferably is selected from PTFE, FEP, PVDF, PCTFE, ECTFE, PFA and perfluoroelastomers.

[0007] EP-A-1 130 056 describes polymer composition comprising (A) (co)polymers based on PCTFE containing ≥ 99 mol% CTFE, and (B) (co)polymers based on ethylene / CTFE (ECTFE) and / or ethylene / TFE (ETFE) having a (ethylene:CTFE) or (ethylene:TFE) molar ratio of (1:3)-(3:1).SUMMARY OF INVENTION- Technical Problem

[0008] The disclosure aims to provide a fluororesin-containing composition having significantly improved fluidity and a method for producing the same.- Solution to Problem

[0009] The present invention provides a composition, which is a fluororesin-containing composition comprising (i) 99.99-97 mass% of a fluororesin having a melting point of 205-225°C, determined as the temperature corresponding to the maximum value on a heat-of-fusion curve drawn using a differential scanning calorimeter (DSC) at a temperature-increasing rate of 10°C / min, and (ii) 0.01-3 mass% of a thermotropic liquid crystal polymer having a liquid crystal transition starting temperature of 200-260°C, determined as the temperature at which the thermotropic liquid crystal polymer mounted on the sample holder of a polarization microscope becomes opalescent by heating under shear stress.

[0010] Also, the present invention provides a fluororesin-containing composition comprising ≥ 90 mass% of polychlorotrifluoroethylene and a thermotropic crystal polymer, and having a melt flow rate MFR at 280°C of 3-40 g / 10 min., measured in accordance with ASTM D1238 at 280°C and a load of 10.0 kg.

[0011] Furthermore, the present invention provides a method for producing the above compositions, comprising kneading polychlorotrifluoroethylene and a thermotropic liquid crystal polymer at 285-320°C.

[0012] Preferred embodiments of the invention are as defined in the appended dependent claims and / or in the following detailed description.- Advantageous Effects of Invention

[0013] The fluororesin-containing composition of the disclosure, containing a small amount of a thermotropic liquid crystal polymer, can significantly improve the fluidity while maintaining excellent properties of a fluororesin. The fluororesin-containing composition thereby has improved extrusion moldability and enables injection molding of a fluororesin, which has been difficult. Such a small amount of the thermotropic liquid crystal polymer can significantly improve the moldability without deteriorating the properties of a fluororesin (e.g., mechanical strength and vapor permeability of polychlorotrifluoroethylene).DESCRIPTION OF EMBODIMENTS

[0014] The inventors found that addition of a small amount of a thermotropic liquid crystal polymer to a fluorine-containing resin can significantly improve the fluidity and thereby completed the fluororesin-containing composition of the disclosure.

[0015] Hereinafter, the disclosure is described in detail.

[0016] The fluororesin-containing composition of the disclosure contains 99.99-97 mass% of a fluororesin having a melting point of 205-225°C and 0.01-3% by mass of a thermotropic liquid crystal polymer.

[0017] The fluororesin has a melting point of 205-225°C, preferably 210-216°C. The melting point herein means a temperature corresponding to the maximum value on a heat-of-fusion curve drawn using a differential scanning calorimeter (DSC) at a temperature-increasing rate of 10°C / min.

[0018] The fluororesin having a melting point of 205-225°C may be any fluororesin satisfying this melting point range, and examples thereof include polychlorotrifluoroethylene (PCTFE), ethylene tetrafluoroethylene (ETFE), and tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride (THV). Preferred among these is polychlorotrifluoroethylene in terms of low fluidity of the fluororesin and a better effect of improving the fluidity.

[0019] Examples of the PCTFE used in the present invention include a chlorotrifluoroethylene (CTFE) homopolymer and a copolymer of a polymerized unit based on CTFE ("CTFE unit") and a polymerized unit based on a monomer (α) polymerizable with CTFE ("monomer (α) unit").

[0020] The PCTFE preferably contains CTFE units in an amount of 90-100 mol%. In terms of excellent moisture proof properties, the amount of CTFE units is more preferably 98-100 mol%, still more preferably 99-100 mol%.

[0021] In the case where the PCTFE is a copolymer of a CTFE unit and a monomer (α) unit, the monomer (α) may be any monomer copolymerizable with CTFE, and examples thereof include tetrafluoroethylene (TFE), ethylene (Et), vinylidene fluoride (VdF), perfluoro(alkyl vinyl) ether (PAVE), a vinyl monomer of formula (I):         CX 3< X 4< =CX 1< (CF 2 ) n X 2<      (I) wherein X 1< , X 3< , and X 4< each independently are H or F; X 2< is H, F, or Cl; and n is an integer of 1-10), and an alkyl perfluorovinyl ether derivative of formula (II) wherein Rf is C 1-5 -perfluoroalkyl:         CF 2 =CF-OCH 2 -Rf     (II).

[0022] Examples of the PAVE include perfluoro(methyl vinyl ether) (PMVE), perfluoro(ethyl vinyl ether) (PEVE), perfluoro(propyl vinyl ether) (PPVE), and perfluoro(butyl vinyl ether).

[0023] Examples of the vinyl monomer of formula (I) include hexafluoropropylene (HFP), perfluoro(1,1,2-trihydro-1-hexene), perfluoro(1,1,5-trihydro-1-pentene), and a perfluoro(alkyl) ethylene of formula (III):         H 2 C=CX 5< Rf 5<      (III) wherein X 5< is H, F, or CF 3 , and Rf 5< is C 1-10 -perfluoroalkyl. The perfluoro(alkyl) ethylene is preferably perfluoro(butyl) ethylene.

[0024] The alkyl perfluorovinyl ether derivative of formula (II) is preferably one in which Rf is C 1-3 -perfluoroalkyl, more preferably CF 2 =CF-OCH 2 -CF 2 CF 3 .

[0025] The monomer (α) polymerizable with CTFE preferably includes at least one selected from TFE, Et, VdF, PAVE, and a vinyl monomer of formula (I). One kind or two or more kinds of the monomer (α) may be used.

[0026] The monomer (α) may also be an unsaturated carboxylic acid copolymerizable with CTFE. Examples of the unsaturated carboxylic acid include unsaturated aliphatic C 3-6 -carboxylic acids such as (meth)acrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, mesaconic acid, and aconitic acid. The monomer (α) may also be an unsaturated aliphatic C 3-6 -polycarboxylic acid.

[0027] Examples of the unsaturated aliphatic polycarboxylic acid include maleic acid, fumaric acid, itaconic acid, citraconic acid, mesaconic acid, and aconitic acid. Among these, those which can be in the form of an acid anhydride, such as maleic acid, itaconic acid, and citraconic acid, may be in the form of an acid anhydride.

[0028] Two or more kinds of the monomer (α) may be used. Still, in case that monomer (α) is a monomer such as VDF, PAVE, or HFP, the monomer (α) does not need to be used in combination with itaconic acid, citraconic acid, or an acid anhydride thereof.

[0029] The PCTFE preferably has a melt flow rate (MFR) of 0.1-1 g / 10 min. The MFR is a value obtained by measurement under the conditions of a temperature of 280°C and a load of 10.0 kg in accordance with ASTM D1238.

[0030] The fluororesin-containing composition contains the fluororesin in an amount of 99.99-97 mass%, preferably 99.9-98 mass%. The fluororesin-containing composition contains the thermotropic liquid crystal polymer in an amount of 0.01-3 mass%, preferably 0.1-2 mass%. Less than 97 mass% of the fluororesin tends to reduce the mechanical strength, while more than 99.99 mass% thereof tends to reduce an effect of improving the fluidity.

[0031] The thermotropic liquid crystal polymer may be any polymer that becomes a liquid crystal state such as a nematic state by heating, and examples thereof include: type-I liquid crystal polymers (e.g., a biphenol / benzoic acid / para-hydroxybenzoic acid (POB) copolymer); type-II liquid crystal polymers (e.g., a hydroxynaphthoic acid (HNA) / POB copolymer); and type-III liquid crystal polymers (e.g., a POB / ethylene terephthalate copolymer). Preferred among these are type-III liquid crystal polymers such as a POB / ethylene terephthalate copolymer in terms of the kneading temperature and the liquid crystal transition temperature.

[0032] The amount of the POB units copolymerized in the POB / ethylene terephthalate copolymer is not limited and is preferably 20-80 mol%, more preferably 30-70 mol%. Less than 20 mol% of the amount copolymerized tends to fail to provide sufficient liquid crystallinity, while more than 80 mol% thereof tends to give too rigid molecular chain in the polymer, leading to too high a liquid crystal starting temperature.

[0033] The liquid crystal transition starting temperature of the thermotropic liquid crystal polymer is preferably a temperature not higher than the processing temperature of the fluororesin. Since the processing temperature of PCTFE is 280°C or higher, the liquid crystal transition starting temperature is 200-260°C, preferably 210-240°C. A liquid crystal transition starting temperature of lower than 200°C tends to cause decomposition of the liquid crystal polymer at a kneading temperature to reduce the dispersion effect, while a liquid crystal transition starting temperature of higher than 260°C tends to increase the melt viscosity at a kneading temperature to fail to achieve an effect of improving the fluidity. The liquid crystal starting temperature herein means a temperature at which a thermotropic liquid crystal polymer mounted on the sample holder of a polarization microscope becomes opalescent by heating under shear stress.

[0034] The melt flow rate MFR of the fluororesin-containing composition of the disclosure is preferably 3-40 g / 10 min at 280°C, more preferably 5-30 g / 10 min at 280°C. A melt flow rate MFR of lower than 3 g / 10 min causes too high a melt viscosity to cause defects during injection molding, while a melt flow rate MFR of higher than 40 g / 10 min tends to reduce the mechanical strength.

[0035] According to another embodiment of the invention a fluororesin-containing composition of the disclosure contains ≥ 90 mass% of polychlorotrifluoroethylene and a thermotropic crystal polymer, and has a melt flow rate MFR at 280°C of 3-40 g / 10 min, measured in accordance with ASTM D1238 at 280°C and a load of 10.0 kg.

[0036] The fluororesin-containing composition of the disclosure may contain different components in addition to the fluororesin and the thermotropic liquid crystal polymer. Examples of the different components include reinforcing fibers, fillers, plasticizers, processing aids, mold lubricants, pigments, flame retarders, lubricants, light stabilizers, weathering agents, conducting agents, antistatic agents, ultraviolet absorbers, antioxidants, foaming agents, perfumes, oils, softeners, dehydrofluorinating agents, and nucleating agents. Examples of the reinforcing fibers include carbon fibers, glass fibers, and basalt fibers. Examples of the fillers include polytetrafluoroethylene, mica, silica, talc, cerite, clay, titanium oxide, and barium sulfate. An example of the conducting agents is carbon black. Examples of the plasticizers include dioctyl phthalic acid and pentaerythritol. Examples of the processing aids include carnauba wax, sulfone compounds, low molecular weight polyethylene, and fluorine-based aids. Examples of the dehydrofluorinating agents include organic oniums and amidines.

[0037] Also, the method for producing a fluororesin-containing composition of the disclosure includes kneading polychlorotrifluoroethylene and a thermotropic liquid crystal polymer at 285-320°C.

[0038] Kneading may be performed with any tool such as an open roll, a Banbury mixer, a pressure kneader, or an extruder. Preferred among these is a pressure kneader or an extruder such as a biaxial extruder in terms of applying a high shear force.

[0039] Melt kneading is preferably performed at a temperature not lower than the melting point of PCTFE and not higher than the decomposition temperature thereof. Specifically, the temperature is preferably 250-360°C, more preferably 285-320°C. Melt kneading at a temperature lower than 250°C tends to inhibit dispersing, while melt kneading at a temperature higher than 360°C tends to reduce the molecular weight of the fluorine-containing resin, leading to reduced strength.

[0040] The fluororesin-containing composition of the disclosure and a fluororesin-containing composition obtained by the production method of the disclosure can be molded by e.g. extrusion molding or injection molding. Obtained molded articles can be used for various applications such as semiconductor-related articles, drug wrapping films, barrier films, industrial equipment, electrical components, and automotive components.EXAMPLES

[0041] The disclosure is described with reference to examples.

[0042] Materials used in the examples and comparative examples are listed below. Polychlorotrifluoroethylene: CTFE 100 mol%, melting point 211°C, MFR at 280°C: 0.49 g / 10 min Thermotropic liquid crystal polymer: X7G (available from Eastman Kodak Company), liquid crystal starting temperature: 245°C, amount of para-hydroxybenzoic acid units copolymerized: 40 mol% Examples 1 and 2

[0043] A fluororesin-containing composition was produced at the liquid crystal polymer content shown in Table 1 by kneading with a biaxial extruder at a cylinder temperature of 290-315°C. The resulting fluororesin-containing composition was injection molded with an injection molder set to have a cylinder temperature of 270-300°C, a nozzle temperature of 300°C, and a mold temperature of 100°C to provide a dumbbell specimen and a bending specimen.Comparative Example 1

[0044] PCTFE was injection molded with an injection molder set to have a cylinder temperature of 300-330°C, a nozzle temperature of 330°C, and a mold temperature of 100°C to provide a dumbbell specimen and a bending specimen.<Melt flow rate (MFR)>

[0045] The MFR was determined as the mass (g / 10 min) of the polymer that was held at 280°C for five minutes and then flew out of a nozzle having an inner diameter of 2.095 mm and a length of 8 mm per 10 minutes and under a load of 10 kg using a melt indexer (available from Toyo Seiki Seisaku-sho, Ltd.) in accordance with ASTM D1238.<Tensile properties>

[0046] Each of the resulting dumbbell specimens was subjected to a tensile test using a Tensilon universal material testing instrument (available from A&D Company, Limited) at a speed of 50 mm / min, and the tensile breaking strength and the tensile elongation at break were determined in accordance with ASTM D638.<Bending properties>

[0047] Each of the resulting bending specimens was subjected to a bending test with a Tensilon universal material testing instrument (available from A&D Company, Limited) at a speed of 2 mm / min, and the bending strength and the flexural modulus were determined in accordance with ASTM D790.<Heat deflection temperature>

[0048] The heat deflection temperature of each resulting bending specimen was determined as a temperature at which the deflection value reached 0.254 mm under a load of 1.83 MPa using a heat distortion tester (available from YASUDA SEIKI SEISAKUSHO, LTD.) in accordance with ASTM D648.<Vapor permeability>

[0049] A film formed by press molding the composition was cut into a 50 mm × 50 mm size. A 30-mm diameter filter was set beside the film, and the water vapor transmission rate of the film was measured in accordance with JIS K7129 (method A) using water vapor transmission rate tester L80-5000 (available from Dr. Lyssy). [Table 1]Example No.LCP parts by massMFR at 280°C, 10 kgTensile propertiesBending propertiesHeat deflection temperatureVapor permeabilityStrengthElongation at breakStrengthFlexural modulusMPa%MPaMPa°Cg / m 2< dayComparative Example 10.00.494810671700730.22Example 10.514.84912692040730.14Example 21.024.7488652130720.17

[0050] In spite of the fact that the fluororesin-containing composition in Example 1 contained a liquid crystal polymer in an amount of as small as 0.5 parts by mass, the MFR of the polychlorotrifluoroethylene was significantly increased from 0.49 g / 10 min to 14.8 g / 10 min, which was an about 25 times increase, and thus the fluidity was significantly improved. As a result, the PCTFE could be injection molded even when the molding temperature was reduced to 300°C from 320-330°C.

[0051] As for the mechanical properties, the flexural modulus was improved, while the tensile strength, bending strength, heat deflection temperature, and vapor permeability were hardly changed.

[0052] Also, in spite of the fact that the fluororesin-containing composition in Example 2 contained a liquid crystal polymer in an amount of as small as 1 part by mass, the MFR was significantly increased by about 50 times, and thus the fluidity was significantly improved. As for the mechanical properties, the flexural modulus was improved, while the tensile strength, bending strength, heat deflection temperature, and vapor permeability were hardly changed.INDUSTRIAL APPLICABILITY

[0053] The fluororesin-containing composition of the disclosure has significantly improved fluidity and thus is suitably used for extrusion molding and injection molding.

Claims

1. A composition, which is a fluororesin-containing composition comprising (i) 99.99-97 mass% of a fluororesin having a melting point of 205-225°C, determined as the temperature corresponding to the maximum value on a heat-of-fusion curve drawn using a differential scanning calorimeter (DSC) at a temperature-increasing rate of 10°C / min, and (ii) 0.01-3 mass% of a thermotropic liquid crystal polymer having a liquid crystal transition starting temperature of 200-260°C, determined as the temperature at which the thermotropic liquid crystal polymer mounted on the sample holder of a polarization microscope becomes opalescent by heating under shear stress.

2. The composition of claim 1, wherein the fluororesin is polychlorotrifluoroethylene.

3. The composition of claim 2, comprising 99.9-98 mass% of the polychlorotrifluoroethylene and 0.1-2 mass% of the thermotropic liquid crystal polymer.

4. The composition of any of claims 1-3, wherein the polychlorotrifluoroethylene has a melt flow rate MFR at 280°C of 0.1-1.0 g / 10 min., measured in accordance with ASTM D1238 at 280°C and a load of 10.0 kg.

5. The composition of any of claims 1-4, wherein the thermotropic liquid crystal polymer is a copolymer of para-hydroxybenzoic acid and ethylene terephthalate.

6. A fluororesin-containing composition comprising ≥ 90 mass% of polychlorotrifluoroethylene and a thermotropic liquid crystal polymer, and having a melt flow rate MFR at 280°C of 3-40 g / 10 min., measured in accordance with ASTM D1238 at 280°C and a load of 10.0 kg.

7. A method for producing the composition of any of claims 1-6, comprising kneading polychlorotrifluoroethylene and a thermotropic liquid crystal polymer at 285-320°C.