FLUORORESIN, MULTILAYER PRODUCT, AND TUBE

Abstract

A fluororesin having a tensile strength retention ratio of 50% or more, the tensile strength retention ratio being calculated by the following formula from the tensile strength of the fluororesin after a heat treatment obtained by conducting a heat treatment at 130° C. for 40,000 hours, and the tensile strength of the fluororesin before the heat treatment. Tensile strength retention ratio (%)=(tensile strength of fluororesin after heat treatment (MPa))/(tensile strength of fluororesin before heat treatment (MPa))×100.

Claims

1. A fluororesin having a tensile strength retention ratio of 50% or more, the tensile strength retention ratio being calculated by the following formula from a tensile strength of the fluororesin after a heat treatment obtained by conducting a heat treatment at 130° C. for 40,000 hours, and a tensile strength of the fluororesin before the heat treatment:
Tensile strength retention ratio (%)=(tensile strength of fluororesin after heat treatment (MPa))/(tensile strength of fluororesin before heat treatment (MPa))×100.

2. A fluororesin having an extraction of an extract to be extracted in perfluorocyclobutane of 0.3% by mass or less, upon immersion of the fluororesin in perfluorocyclobutane at 60° C. for 10 days, based on a mass of the fluororesin immersed.

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

4. The fluororesin according to claim 1, wherein the fluororesin has at least one selected from the group consisting of a carbonate group and a carboxylic halide group, and a total number of carbonate groups and carboxylic halide groups is 3 to 800 per 10.sup.6 main-chain carbon atoms.

5. The fluororesin according to claim 1, wherein the fluororesin contains ethylene unit and tetrafluoroethylene unit.

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

7. The fluororesin according to claim 1, wherein the fluororesin contains chlorotrifluoroethylene unit and tetrafluoroethylene unit.

8. A laminate comprising: a fluororesin layer containing the fluororesin according to claim 1; and a non-fluororesin layer containing a non-fluororesin.

9. The fluororesin according to claim 1, which is a pellet.

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

11. The fluororesin according to claim 2, wherein the fluororesin has at least one selected from the group consisting of a carbonate group and a carboxylic halide group, and a total number of carbonate groups and carboxylic halide groups is 3 to 800 per 10.sup.6 main-chain carbon atoms.

12. The fluororesin according to claim 2, wherein the fluororesin contains ethylene unit and tetrafluoroethylene unit.

13. The fluororesin according to claim 12, wherein the fluororesin further contains hexafluoropropylene unit.

14. The fluororesin according to claim 2, wherein the fluororesin contains chlorotrifluoroethylene unit and tetrafluoroethylene unit.

15. A laminate comprising: a fluororesin layer containing the fluororesin according to claim 2; and a non-fluororesin layer containing a non-fluororesin.

16. The fluororesin according to claim 2, which is a pellet.

Description

EXAMPLES

[0202] 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.

[0203] The numerical values of the Examples were measured by the following methods.

<Polymer Composition>

[0204] .sup.19F-NMR measurement was conducted using pellets of 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).

<Melting Point>

[0205] Thermal measurement was conducted using pellets of the fluororesin obtained in each Example and a differential scanning calorimeter REC220 (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 was determined from the peak of the endothermic curve obtained.

<Melt Flow Rate (MFR)>

[0206] The mass (g/10 min) of the fluororesin 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 pellets of the fluororesin obtained in each Example and a melt indexer (manufactured by Yasuda Seiki Seisakusho Ltd.) in accordance with ASTM D 1238.

<Number of Carbonate Groups and Carboxylic Acid Fluoride Groups>

[0207] 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 [ν.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 [Ξ.sub.(C═O)], and thus the absorbance of the ν.sub.(C═O) peaks was measured. The number of carbonate groups per 10.sup.6 main-chain carbon atoms of the fluororesin was calculated according to the following formula.

Number of carbonate groups or carboxylic acid fluoride groups (per 10.sup.6 main-chain carbon atoms)=(1×K)/t [0208] l: Absorbance [0209] K: Correction factor (—OC(═O)O—R: 1426, —COF: 405) [0210] t: Film thickness (mm)

[0211] 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.

<Tensile Strength>

[0212] Pellets of the fluororesin obtained in each Example were compression-molded at room temperature to produce a film having a thickness of 2.0 mm. A test piece (ASTM V-type dumbbell) was produced from the obtained film. The tensile strength was measured using the obtained test piece and a tensile testing machine (AUTOGRAPH AG-1 manufactured by Shimadzu Corporation) in accordance with ASTM D 638 under conditions of a distance between chucks of 25 mm and a tensile rate of 50 mm/min.

<Tensile Strength Retention Ratio>

[0213] The test piece obtained above (ASTM V-type dumbbell) was placed in an electric furnace, a heat treatment at 130° C. for 40,000 hours was conducted, and then the test piece was taken out of the electric furnace and allowed to cool to normal temperature. The tensile strength of the test piece after the heat treatment was measured by the method described above, and the tensile strength retention ratio was calculated according to the following formula. Further, a heat treatment was conducted for 40,000 hours also at an arbitrary temperature higher than 130° C. in order to grasp the temperature at which the tensile strength retention ratio reaches 50%, and the tensile strength retention ratio was calculated in the same manner.

Tensile strength retention ratio (%)=(tensile strength of fluororesin after heat treatment (MPa))/(tensile strength of fluororesin before heat treatment (MPa))×100

<Extraction in Perfluorocyclobutane>

[0214] The entire pellets, about 10 g, of the fluororesin obtained in each Example were immersed in perfluorocyclobutane and allowed to be left at 60° C. for 10 days (240 hours). Thereafter, the pellets were taken out and the perfluorocyclobutane was recovered. The obtained perfluorocyclobutane was dried at room temperature for one week or more and heated to completely remove the perfluorocyclobutane, and the mass of the extract (dry mass of the residue) was weighed. The proportion of the mass of the extract based on the mass of the immersed pellets (fluororesin) was calculated as the extraction according to the following formula.

Extraction (% by mass)=(mass of extract (dry mass of residue) (g))/(mass of pellets immersed in perfluorocyclobutane (g))×100

<Initial Pyrolysis Temperature>

[0215] Pellets of the fluororesin obtained in each Example were heated at 10° C./min under an air atmosphere using a thermogravimeter-differential thermal analyzer TG/DTA6200 or TG/DTA7200 (manufactured by Hitachi High-Tech Science Corporation), and the temperature when the mass reduction of the fluororesin reached 1% by mass was defined as the initial pyrolysis temperature.

Example 1

Production of Fluororesin A

[0216] 380 L of distilled water was placed in an autoclave. After sufficient nitrogen purging, 166 kg of octafluorocyclobutane, 83 kg of HFP, 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, TFE 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 TFE/Et/EFP=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.

[0217] The recovered reaction product was placed in 1,000 kg of distilled water and cleaned by stirring for 60 minutes. This cleaning operation was repeated twice in total. The fluororesin obtained by cleaning was dried to obtain 250 kg of a powdery fluororesin.

[0218] The powdery fluororesin was placed in a 50 mmϕ single screw extruder comprising a cylinder having a vent hole. The fluororesin was melted in the cylinder at 220° C. while volatiles generated from the fluororesin were removed via the vent hole, and extruded from the extruder to form the fluororesin into cylindrical pellets (diameter: 2.5 mm, length: 2.5 mm).

[0219] The physical properties of the obtained pelletized fluororesin A are shown below.

[0220] Polymer composition (mol %): TFE/Et/HFP/perfluoro(1,1,5-trihydro-1-pentene)=45.5/44.4/9.5/0.6

[0221] Melting point: 197° C.

[0222] Melt flow rate (265° C.): 26.3 g/10 min

[0223] Number of carbonate groups and carboxylic acid fluoride groups: 237/10.sup.6C

[0224] Tensile strength retention ratio (130° C.): 50% or more

[0225] Tensile strength retention ratio (139° C.): 50%

[0226] Extraction in perfluorocyclobutane: 0.16% by mass

[0227] Initial pyrolysis temperature: 360° C.

Example 2

Production of Fluororesin B

[0228] 380 L of distilled water was placed in an autoclave. After sufficient nitrogen purging, 230 kg of octafluorocyclobutane and 0.9 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 20° C. and a stirring speed of 200 rpm. Thereafter, TFE was injected up to 0.78 MPa, and further subsequently, Et was injected up to 0.89 MPa. After the inside of the system was set to 35° C., 1.1 kg of cyclohexane was loaded, 1.2 kg of a 50% di-n-propyl peroxydicarbonate solution in methanol was placed, and polymerization was started. The pressure inside the system decreases as the progress of the polymerization, and thus a gas mixture of TFE/Et=57/43 mol % was continuously supplied to keep the pressure inside the system at 1.2 MPa. Then, perfluoro(1,1,5-trihydro-1-pentene) was continuously loaded up to a total amount of 6.0 kg, and stirring was continued for 26 hours. The pressure was released to atmospheric pressure, and the reaction product was recovered.

[0229] The recovered reaction product was placed in 1,000 kg of distilled water and cleaned by stirring for 60 minutes. This cleaning operation was repeated twice in total. The fluororesin obtained by cleaning was dried to obtain 200 kg of a powdery fluororesin.

[0230] The powdery fluororesin was placed in a 50 mmϕ single screw extruder comprising a cylinder having a vent hole. The fluororesin was melted in the cylinder at 300° C. while volatiles generated from the fluororesin were removed via the vent hole, and extruded from the extruder to foam the fluororesin into cylindrical pellets (diameter: 2.5 mm, length: 2.5 mm).

[0231] The physical properties of the obtained pelletized fluororesin B are shown below.

[0232] Polymer composition (mol %): TFE/Et/perfluoro(1,1,5-trihydro-1-pentene)=57.2/41.6/1.2

[0233] Melting point: 256° C.

[0234] Melt flow rate (297° C.): 22.5 g/10 min

[0235] Number of carbonate groups and carboxylic acid fluoride groups: 211/10.sup.6C

[0236] Tensile strength retention ratio (130° C.): 50% or more

[0237] Tensile strength retention ratio (151° C.): 50%

[0238] Extraction in perfluorocyclobutane: 0% by mass

[0239] Initial pyrolysis temperature: 374° C.

Example 3

Production of Fluororesin C

[0240] To a stirring polymerization vessel equipped with a jacket capable of containing 174 kg of water, 51.5 kg of distilled water was loaded. After the inside space was sufficiently purged with pure nitrogen gas, the nitrogen gas was eliminated by vacuum. Then, 40.6 kg of octafluorocyclobutane, 1.3 kg of CTFE, 4.5 kg of TFE, and 2.8 kg of PPVE were injected. 0.075 kg of n-propyl alcohol was added as a chain transfer agent, the temperature was adjusted to 35° C., and stirring was started. 0.38 kg of a 50% by mass di-n-propyl peroxydicarbonate solution in methanol was added thereto as a polymerization initiator, and polymerization was started. During the polymerization, a monomer mixture prepared to have the same composition as a desired copolymer composition was additionally loaded such that the pressure inside the vessel was maintained at 0.66 MPa, and the stirring was continued. The pressure was released to atmospheric pressure, and the reaction product was recovered.

[0241] The recovered content was placed in 150 kg of distilled water and cleaned by stirring for 60 minutes. This cleaning operation was repeated twice in total. The fluororesin obtained by cleaning was dried to obtain 30 kg of a powdery fluororesin.

[0242] The powdery reaction product was placed in a 50 mmϕ single screw extruder comprising a cylinder having a vent hole. The fluororesin was melted in the cylinder at 270° C. while volatiles generated from the fluororesin were removed via the vent hole, and extruded from the extruder to form the fluororesin into cylindrical pellets (diameter: 2.5 mm, length: 2.5 mm).

[0243] The physical properties of the obtained pelletized fluororesin C are shown below.

[0244] Polymer composition (mol %): CTFE/TFE/PPVE=21.0/76.5/2.5

[0245] Melting point: 248° C.

[0246] Melt flow rate (297° C.): 29.7 g/10 min

[0247] Number of carbonate groups and carboxylic acid fluoride groups: 182/10.sup.6C

[0248] Tensile strength retention ratio (130° C.): 50% or more

[0249] Tensile strength retention ratio (220° C.): 50%

[0250] Extraction in perfluorocyclobutane: 0.01% by mass

[0251] Initial pyrolysis temperature: 425° C.

[0252] Laminates to be obtained by using the produced fluororesins A to C will be described with reference to Examples. The physical properties of the laminates were measured by the following methods.

<Adhesive Strength>

[0253] A 1 cm-width test piece was cut off from the tube obtained in each Example 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).

<Surface Roughness Ra>

[0254] A test piece was produced by cutting the tube obtained in each Example, 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.

[0255] In Examples, the following materials were used in addition to the fluororesin A.

Polyamide 12

[0256] Vestamid X7297 manufactured by Daicel-Evonik Ltd.

Polyamide 612

[0257] Vestamid SX8002 manufactured by Daicel-Evonik Ltd. Ethylene/vinyl alcohol copolymer resin

[0258] F101B manufactured by Kuraray Co., Ltd.

Example 4

Production of Laminate

[0259] Using a five-component five-layer tube extrusion apparatus equipped with a multimanifold (manufactured by Pla Giken 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.

Example 5

[0260] 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 (B) and the fluororesin A as a layer (A) were fed to two extruders, respectively, to mold a two-component two-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), and the layer (A) is the innermost layer. The evaluation results are shown in Table 2.

Example 6

[0261] 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 (B) and the fluororesin B as a layer (A) were fed to two extruders, respectively, to mold a two-component two-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), and the layer (A) is the innermost layer. The evaluation results are shown in Table 2.

Example 7

[0262] 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 (B) and the fluororesin C as a layer (A) were fed to two extruders, respectively, to mold a two-component two-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), and the layer (A) is the innermost layer. The evaluation results are shown in Table 2.

[Table 2]

[0263]

TABLE-US-00002 TABLE 2 Exam- Exam- Exam- Exam- ple 4 ple 5 ple 6 ple 7 Layer (A) Cylinder 280-280 280-280 230-300 260-280 temperature (° C.) Adapter 280 280 300 280 temperature (° C.) Layer (B) Cylinder 230-260 210-245 210-245 310-280 temperature (° C.) Adapter 260 245 245 260 temperature (° C.) Layer (C) Cylinder 200-220 temperature (° C.) Adapter 220 temperature (° C.) Layer (D) Cylinder 230-260 temperature (° C.) Adapter 260 temperature (° C.) Layer (E) Cylinder 210-250 temperature (° C.) Adapter 250 temperature (° C.) Die temperature (° C.) 280 230 230 280 Line speed (m/min)  30 30 20 30 Thickness Layer (A) 100 250 250 250 μm Layer (B) 350 750 750 750 Layer (C) 150 Layer (D) 100 Layer (E) 300 Adhesive strength  51 49 45 48 Surface roughness Ra (μm)    0.12 0.03 0.03 0.03