FLUORINE RESIN MATERIAL, LAMINATE, TUBE, AND TUBE MANUFACTURING METHOD

Abstract

A fluororesin material containing a fluororesin. The fluororesin has a carbonyl group, the total number of carbonyl groups is 1 or more and less than 800 per 10.sup.6 main-chain carbon atoms, and the fluororesin contains ethylene unit and tetrafluoroethylene unit. When the fluororesin material is heated at a rate of 10° C./minute, the initial pyrolysis temperature when the mass reduction of the fluororesin material reaches 1% by mass is 390° C. or more.

Claims

1. A fluororesin material containing a fluororesin, wherein the fluororesin has a carbonyl group, a total number of carbonyl groups being 1 or more and less than 800 per 10.sup.6 main-chain carbon atoms, and the fluororesin contains ethylene unit and tetrafluoroethylene unit, and wherein when the fluororesin material is heated at a rate of 10° C./minute under an air atmosphere, an initial pyrolysis temperature when a mass reduction of the fluororesin material reaches 1% by mass is 390° C. or more.

2. A fluororesin material containing a fluororesin, wherein the fluororesin has a carbonyl group, a total number of carbonyl groups being 1 or more and less than 800 per 10.sup.6 main-chain carbon atoms, and the fluororesin contains ethylene unit and tetrafluoroethylene unit, and wherein the fluororesin material has a critical shear rate at 280° C. within a range of 50 to 500 sec.sup.−1.

3. The fluororesin material according to claim 1, having electrical conductivity.

4. The fluororesin material according to claim 1, wherein the fluororesin is a melt-fabricable fluororesin.

5. The fluororesin material according to claim 1, wherein the fluororesin further contains hexafluoropropylene unit.

6. The fluororesin material according to claim 1, further containing an electroconductive material.

7. The fluororesin material according to claim 6, wherein the electroconductive material is carbon black.

8. The fluororesin material according to claim 7, wherein an average particle size of the carbon black is 500 to 1,000 wt.

9. A laminate comprising: a fluororesin layer containing a fluororesin material; and a non-fluororesin layer containing a non-fluororesin, wherein a fuel permeation rate X (g/m.sup.2/day) of the laminate and Y determined from a surface resistivity of the laminate satisfy all the following relational expressions:
Y<800/X
Y<250
X<10 wherein X represents the fuel permeation rate for the laminate measured at 60° C. using CE20, the fuel permeation rate measured at 60° C. using CE50, or the fuel permeation rate measured at 60° C. using CE85; and Y represents a ratio of the surface resistivity measured using CE20, the surface resistivity measured using CE50, or the surface resistivity measured using CE85, based on the surface resistivity measured using CE85 being 100; and each surface resistivity is measured after encapsulating CE20, CE50, or CE85 in the laminate at 60° C. for 1,000 hours, then removing the CE20, CE50, or CE85, removing the laminate from an electric furnace at 60° C. after 3 hours has passed, and allowing the laminate to be left to stand for an hour.

10. The fluororesin material according to claim 1, the fluororesin has a carbonyl group, a total number of carbonyl groups being 1 or more and 320 or less per 10.sup.6 main-chain carbon atoms.

11. The fluororesin material according to claim 2, having electrical conductivity.

12. The fluororesin material according to claim 2, wherein the fluororesin is a melt-fabricable fluororesin.

13. The fluororesin material according to claim 2, wherein the fluororesin further contains hexafluoropropylene unit.

14. The fluororesin material according to claim 2, further containing an electroconductive material.

15. The fluororesin material according to claim 14, wherein the electroconductive material is carbon black.

16. The fluororesin material according to claim 15, wherein an average particle size of the carbon black is 500 to 1,000 μm.

17. The fluororesin material according to claim 2, the fluororesin has a carbonyl group, a total number of carbonyl groups being 1 or more and 320 or less per 10.sup.6 main-chain carbon atoms.

Description

EXAMPTES

[0196] Next, embodiments of the present disclosure will now be described by way of Examples, but the present disclosure is not limited solely to the Examples.

[0197] The numerical values of the Examples were measured by the following methods.

[0198] <Polymer Composition>

[0199] .sup.19F-NMR measurement was conducted using the fluororesin obtained in each Example and a nuclear magnetic resonance apparatus AC300 (manufactured by Bruker-Biospin AG) to determine the polymer composition from the integrated values of peaks. Depending on the kind of monomer, the results of elemental analysis were suitably combined to determine the polymer composition (the content of each monomer unit of the polymer).

[0200] <Melting Point>

[0201] Thermal measurement was conducted using the fluororesin obtained in each Example and a differential scanning calorimeter RDC220 (manufactured by Seiko Instruments Inc.) in accordance with ASTM D 4591 at a temperature-increasing rate of 10° C./min, and the melting point of the fluororesin material was determined from the peak of the endothermic curve obtained.

[0202] <Melt Flow Rate (MFIR)>

[0203] The mass (g/10 min) of the fluororesin material flowing out from a nozzle having an inner diameter of 2 mm and a length of 8 mm per 10 minutes at 265° C. or 297° C. under a load of 5 kg was determined as the MFR using the fluororesin obtained in each Example and a melt indexer (manufactured by Yasuda Seiki Seisakusho Ltd.) in accordance with ASTM D 1238.

[0204] <Number of Carbonyl Groups>

[0205] Pellets of the fluororesin obtained in each Example were compression-molded at room temperature to produce films having a thickness of 50 to 200 μm. In an infrared absorption spectrum analysis of this film, a peak assigned to the carbonyl group of a carbonate group [—OC(═O)O—] appears at an absorption wavelength of 1817 cm.sup.−1 [v.sub.(C═O)], and a peak assigned to the carbonyl group of a carboxylic acid fluoride group [—COF] appears at an absorption wavelength of 1884 cm.sup.−1 [v.sub.(C═o)], and thus the absorbance of the v.sub.(═O) peaks was measured. The number of carbonyl groups per 10.sup.6 main-chain carbon atoms of the fluororesin was calculated according to the following formula.

[0206] Number of carbonyl groups (carbonate groups or carboxylic acid fluoride groups) (per 10.sup.6 main-chain carbon atoms)=(1×K)/t

[0207] l: Absorbance

[0208] K: Correction factor (—OC(═O)O—R: 1426, —COF: 405)

[0209] t: Film thickness (min)

[0210] The infrared absorption spectrum analysis was conducted by scanning 40 times using a Perkin-Elmer MIR spectrometer 1760X (manufactured by The Perkin-Elmer Corporation). The obtained IR spectrum was subjected to automatic baseline judgment by Perkin-Elmer Spectrum for Windows Ver. 1.4C to measure the absorbance of the peaks at 1817 cm.sup.−1 and 1884 cm .sup.−1. The thickness of the films was measured with a micrometer gauge.

[0211] <Initial Pyrolysis Temperature>

[0212] The fluororesin material obtained in each Example was used to measure the initial pyrolysis temperature. The temperature was raised at 10° C./min under an air aLuosphere using a thermogravimeter-differential thermal analyzer TG/DTA6200 or TG/ETA7200 (manufactured by Hitachi High-Tech Science Corporation), and the temperature when the mass reduction of the fluororesin material reached 1% by mass was defined as the initial pyrolysis temperature.

[0213] <Critical Shear Rate>

[0214] The shear rate (sec.sup.−1) when a state was reached where a melt fracture began to occur in a fluororesin flowing out from an orifice having a diameter of 1 mm and a length of 16 mm at 280° C. under a shear stress was measured using the fluororesin material obtained in each Example and a Capilograph (manufactured by Bohlin Instruments Ltd.). The melt fracture on the polymer surface was observed by a microscope at a magnification of 16.

Example 1

Production of Fluororesin A

[0215] 380 L of distilled water was placed in an autoclave. After sufficient nitrogen purging, 166 kg of octafluorocyclobutane, 83 kg of HEP, and 0.3 kg of perfluoro(1,1,5-trihydro-1-pentene) (CH.sub.2═CF(CF.sub.2).sub.3H) were loaded, and the inside of the system was kept at 35° C. and a stirring speed of 200 rpm. Thereafter, TEE was injected up to 0.87 MPa, and further subsequently, Et was injected up to 0.95 MPa. Then, 6.3 kg of di-n-propyl peroxydicarbonate was placed, and polymerization was started. The pressure inside the system decreases as the progress of the polymerization, and thus a gas mixture of TEE/Et/HEP=46/44/10 mol % was continuously supplied to keep the pressure inside the system at 0.95 MPa. Then, perfluoro(1,1,5-trihydro-1-pentene) was continuously loaded up to a total amount of 3.2 kg, and stirring was continued for 23 hours. The pressure was released to atmospheric pressure, and the reaction product was recovered.

[0216] The obtained reaction product was cleaned and dried to obtain 250 kg of a powdery fluororesin. The obtained fluororesin had the following physical properties.

[0217] Polymer composition (mol %): TEh/Et/HEP/perfluoro(1,1,5-trihydro-1-pentene)=45.5/44.4/9.5/0.6

[0218] Melting point: 197° C.

[0219] Melt flow rate (265° C.) : 28.9 g/10 min

[0220] Number of carbonyl groups (carbonate groups and carboxylic acid fluoride groups): 314/10.sup.6C

[0221] The powdery fluororesin and carbon black (DENKA BLACK manufactured by Denka Company Limited, average particle size: 650 μm) were kneaded and famed using a single screw extruder to obtain a pelletized fluororesin material. The obtained fluororesin material had the following physical properties.

[0222] Content of carbon black: 11% by mass

[0223] Initial pyrolysis temperature: 425° C.

[0224] Critical shear rate: 170 sec.sup.−1

[0225] Laminates (multilayer tubes) obtained using the produced fluororesin materials will be described with reference to Examples. The numerical values of the laminates were measured by the following methods.

[0226] <Thickness of Layers of Laminate>

[0227] The thickness of layers constituting the tubes obtained in Examples and Comparative Examples was measured with a micrometer gauge.

[0228] <Adhesive Strength>

[0229] A 1 cm-width test piece was cut off from the tube obtained in Examples and Comparative Examples and subjected to a 180° delamination test at a speed of 25 mm/min using a Tensilon Universal Tester. The average of 5 local maximum points in the elongation amount—tensile strength graph was determined as the adhesive strength (N/cm).

[0230] <Surface Roughness Ra>

[0231] A test piece was produced by cutting the tube obtained in Examples and Comparative Examples, and the surface roughness Ra was measured at a point of the test piece corresponding to the inner surface of the tube. Measurement at 5 measurement points was repeated 3 times using a surface roughness measuring machine (SURFTEST SV-600 manufactured by Mitutoyo Corporation) in accordance with JIS B0601-1994, and the average of the obtained measurements was defined as the surface roughness Ra.

[0232] <Fuel Permeation Rate>

[0233] The tube obtained in each of Examples and Comparative Examples was cut, and the inner diameter and the length thereof were measured. A Swagelok coupling was attached to both ends of the tube, the tube was filled with CE20, CE50, or CE85 (a fuel in which 20, 50, or 80% by volume of ethanol was mixed), and the cap was closed.

[0234] The fuel inside was replaced every other week while the tube was kept at 60° C. After 1,000 hours passed, the fuel permeation rate (g/m.sup.2/day) was calculated from the mass change per hour and the inner area of the tube.

[0235] <Surface Resistivity>

[0236] The tube obtained in each of Examples and Comparative Examples was cut, and the inner diameter and the length thereof were measured. The tube was placed in an electric furnace at 60° C., taken out after 3 hours passed, and allowed to stand for an hour. The resistance value of the tube was measured by applying a voltage of 500 V using a resistance meter (3454-10 manufactured by HIOKI E.E. Corporation) based on SAE J 2260, and the surface resistivity (MΩ/square) was measured from the inner diameter and length of the tube.

[0237] In Examples, the following materials were used in addition to the fluororesin material.

Polyamide 12

[0238] Vestamid X7297 manufactured by Daicel-Evonik Ltd.

Polyamide 612

[0239] Vestamid SX8002 manufactured by Daicel-Evonik Ltd. Ethylene/vinyl alcohol copolymer resin

[0240] F101B manufactured by Kuraray Co., Ltd.

Example 2

Production of Laminate

[0241] Using a five-component five-layer tube extrusion apparatus equipped with a multimanifold (manufactured by PLABOR Research Laboratory of Plastics Technology Co., Ltd.), polyamide 12 as a layer (E), polyamide 612 as layers (B and D), an ethylene/vinyl alcohol copolymer resin as a layer (C), and the fluororesin A as a layer (A) were fed to five extruders, respectively, to mold a 5-component 5-layer multilayer tube having an outer diameter of 8 mm and an inner diameter of 6 mm, according to the extrusion conditions shown in Table 2. The multilayer tube has a layer arrangement of the layer (A)/layer (B)/layer (C)/layer (D)/layer (E), and the layer (A) is the innermost layer. The evaluation results are shown in Table 2 and Table 3.

Comparative Example 1

[0242] Using a two-component two-layer tube extrusion apparatus equipped with a multimanifold (manufactured by PLABOR Research Laboratory of Plastics Technology Co., Ltd.), polyamide 12 as a layer (E) was fed to one extruder, to mold a monolayer tube having an outer diameter of 8 mm and an inner diameter of 6 mm, according to the extrusion conditions shown in Table 2. The evaluation results are shown in Table 2 and Table 3.

TABLE-US-00002 TABLE 2 Comparative Example 2 Example 1 Layer (A) Cylinder temperature (° C.) 260-280 — Adapter temperature (° C.) 280 — Layer (B) Cylinder temperature (° C.) 230-260 — Adapter temperature (° C.) 260 — Layer (C) Cylinder temperature (° C.) 200-220 — Adapter temperature (° C.) 220 — Layer (D) Cylinder temperature (° C.) 230-260 — Adapter temperature (° C.) 260 — Layer (E) Cylinder temperature (° C.) 210-250 200-230 Adapter temperature (° C.) 250 240 Die temperature (° C.) 280 240 Line speed (m/min)  30  8 Thickness Layer (A) 100 — μm Layer (B) 350 — Layer (C) 150 — Layer (D) 100 — Layer (E) 300 1000  Adhesive strength  51 — Surface roughness Ra (μm)    0.15    0.03

TABLE-US-00003 TABLE 3 Comparative Example 2 Example 1 Permeation rate CE 20 2.1 163.0 g/m.sup.2/day CE 50 4.0 377.0 CE 85 4.3 310.0 Surface resistivity CE 20 0.141 0.022 after immersion CE 50 0.113 0.009 (Ω/square) CE 85 0.081 0.006 Y CE 20 172 367 CE 50 138 150 CE 85 100 100