Fluorinated elastic copolymer, and method for producing fluorinated elastic copolymer

Abstract

To provide a fluorinated elastic copolymer excellent in adhesion, processability, mechanical properties, heat resistance and chemical resistance. A fluorinated elastic copolymer having units based on a monomer (a), units based on a monomer (b) and optionally units based on a monomer (c), which has an iodine atom bonded to a terminal of a molecular chain and the unit based on the monomer (b) adjacent to the iodine atom, and which has a proportion of the units based on the monomer (b) of from 0.09 to 2.0 mol % to all units. Monomer (a): monomer selected from the group consisting of tetrafluoroethylene, hexafluoropropylene, vinylidene fluoride, chlorotrifluoroethylene, a perfluoro(alkyl vinyl ether) and 2,3,3,3-tetrafluoropropene; monomer (b): a monomer having at least one type of functional group selected from the group consisting of an epoxy group, a hydroxy group, a carbonyl group-containing group and an isocyanate group; monomer (c): a monomer selected from the group consisting of ethylene and propylene.

Claims

1. A fluorinated elastic copolymer having units based on the following monomer (a), units based on the following monomer (b) and optionally units based on the following monomer (c), which has an iodine atom bonded to a terminal of a molecular chain of the fluorinated elastic copolymer, and the unit based on the monomer (b) adjacent to the iodine atom, and which has a proportion of the units based on the monomer (b) of from 0.09 to 2.0 mol % to all units of the fluorinated elastic copolymer: monomer (a): a monomer selected from the group consisting of tetrafluoroethylene, hexafluoropropylene, vinylidene fluoride, chlorotrifluoroethylene, a perfluoro(alkyl vinyl ether) and 2,3,3,3-tetrafluoropropene; monomer (b): a monomer having at least one adhesive functional group selected from the group consisting of an epoxy group and a hydroxy group, and having one polymerizable carbon-carbon double bond; monomer (c): a monomer selected from the group consisting of ethylene and propylene.

2. The fluorinated elastic copolymer according to claim 1, which is a copolymer selected from the group consisting of a copolymer having units based on tetrafluoroethylene, units based on propylene and units based on the monomer (b), a copolymer having units based on tetrafluoroethylene, units based on a perfluoro(alkyl vinyl ether) and units based on the monomer (b), a copolymer having units based on vinylidene fluoride, units based on hexafluoropropylene and units based on the monomer (b), a copolymer having units based on tetrafluoroethylene, units based on vinylidene fluoride, units based on hexafluoropropylene and units based on the monomer (b), and a copolymer having units based on vinylidene fluoride, units based on tetrafluoroethylene, units based on a perfluoro(alkyl vinyl ether) and units based on the monomer (b).

3. The fluorinated elastic copolymer according to claim 1, wherein the monomer (b) is a monomer selected from the group consisting of allyl glycidyl ether, vinyl glycidyl ether, 4-glycidyl oxybutyl vinyl ether and 4-hydroxybutyl vinyl ether.

4. The fluorinated elastic copolymer according to claim 1, wherein a proportion of the units based on the monomer (a) is from 30 to 98 mol % to the total amount of all units of the fluorinated elastic copolymer.

5. The fluorinated elastic copolymer according to claim 1, which has the units based on the monomer (c).

6. The fluorinated elastic copolymer according to claim 5, wherein the total proportion of the units based on the monomer (a) and the units based on the monomer (c) is from 50 to 99.91 mol % to the total amount of all units of the fluorinated elastic copolymer.

7. The fluorinated elastic copolymer according to claim 5, wherein the proportion of the units based on the monomer (c) is from 1 to 70 mol % to the total amount of the units based on the monomer (a) and the units based on the monomer (c).

8. The fluorinated elastic copolymer according to claim 1, which has a mass average molecular weight of from 10,000 to 2,000,000.

9. A method for producing a fluorinated elastic copolymer having units based on the following monomer (a), units based on the following monomer (b) and optionally units based on the following monomer (c), which comprises polymerizing a monomer component comprising the monomer (a) and optionally the monomer (c) and not including the monomer (b), in the presence of an iodine compound having two iodine atoms until units in an amount of at least 80 mol % to all units of the fluorinated elastic copolymer are formed, and copolymerizing monomer components comprising the monomer (a), the monomer (b) and optionally the monomer (c) until the units based on the monomer (b) in an amount of from 0.09 to 2.0 mol % to all units of the fluorinated elastic copolymer are formed: monomer (a): a monomer selected from the group consisting of tetrafluoroethylene, hexafluoropropylene, vinylidene fluoride, chlorotrifluoroethylene, a perfluoro(alkyl vinyl ether) and 2,3,3,3-tetrafluoropropene; monomer (b): a monomer having at least one adhesive functional group selected from the group consisting of an epoxy group and a hydroxy group, and having one polymerizable carbon-carbon double bond; monomer (c): a monomer selected from the group consisting of ethylene and propylene.

10. The production method according to claim 9, wherein the iodine compound is a compound represented by the following formula (1):
I—R.sup.f1—I  (1) wherein R.sup.f1 is a C.sub.4-12 perfluoroalkylene group.

11. The production method according to claim 9, wherein the monomer (a) and optionally the monomer (c) are polymerized in the presence of an emulsifier.

Description

EXAMPLES

(1) Now, the present invention will be described in further detail with reference to Examples. However, it should be understood that the present invention is by no means restricted to the following specific Examples. Ex. 1 to 4 are Examples of the present invention, and Ex. 5 to 8 are Comparative Examples.

(2) <Abbreviations>

(3) C4DI: 1,4-diiodoperfluorobutane

(4) Rongalit: a 2.5 mass % aqueous solution of sodium hydroxymethanesulfinate dihydrate adjusted to pH 10.0 with sodium hydroxide.

(5) SUS: stainless steel film (SUS304).

(6) PI: polyimide film.

(7) <Measurement method)

(8) (Copolymer Composition)

(9) The proportions (mol %) of the units constituting the fluorinated elastic copolymer were obtained by .sup.1H and .sup.19F-nuclear magnetic resonance (NMR) analysis. (Iodine atom content)

(10) The iodine content of the fluorinated elastic copolymer was quantitatively determined by an apparatus which is a combination of automatic quick furnace combustion apparatus (AQF-100, manufactured by Dia Instruments Co., Ltd.) and ion chromatography.

(11) (Elastic Shear Modulus G′)

(12) The torque was measured in accordance with ASTM D6204 by Rubber Process Analyzer (RPA2000, manufactured by ALPHA TECHNOLOGIES) under conditions of a sample amount of 7.5 g, a temperature of 100° C. and an amplitude of 0.5° by changing the frequency from 1 to 2,000 cpm, and the torque at 50 cpm was taken as the elastic shear modulus G′ of the fluorinated elastic copolymer.

(13) (Terminal Structure of Molecular Chain of Fluorinated Elastic Copolymer)

(14) The fluorinated elastic copolymer was heat-decomposed at 600° C. by means of Double-Shot Pyrolyzer (PY-2020iD, manufactured by Frontier Laboratories Ltd.), followed by analysis by means of EI+ ionization method by gas chromatography/Time-of-Flight Mass Spectrometer (hereinafter referred to as GC/TOFMS) (7890A, manufactured by Agilent, and JMS-T100GC, manufactured by JEOL Ltd.) to detect a structure bonded to an iodine atom at the terminal.

(15) <Evaluation Method>

(16) (Adhesion)

(17) 5 g of the fluorinated elastic copolymer was sandwiched between two sheets of SUS or PI, followed by hot pressing under a pressure of 10 MPa at a temperature of 170° C. for 5 minutes to bond a crosslinked product of the fluorinated elastic copolymer and the metal or the resin to obtain a structure. The structure was cooled to room temperature (25° C.) and subjected to manual peel test with hands.

(18) From the results of the peel test, the adhesion of the structure was evaluated based on standards ◯: no peeling occurred at the interface between the crosslinked product and the metal or the resin, and the whole crosslinked product underwent material failure, Δ: a part of the crosslinked product underwent material failure, and ×: peeling occurred at the interface.

(19) <Production of Fluorinated Elastic Copolymer>

(20) (Ex. 1)

(21) The interior of a stainless steel pressure resistant reactor having an internal capacity of 3,200 mL equipped with a stirring anchor blade was deaerated, and then 1,500 g of deionized water, 60 g of disodium hydrogenphosphate dodecahydrate, 0.9 g of sodium hydroxide, 198 g of tert-butanol, 8.9 g of sodium lauryl sulfate and 3.8 g of ammonium persulfate were added to the reactor. Further, an aqueous solution having 0.4 g of disodium ethylenediaminetetraacetate dihydrate and 0.3 g of ferrous sulfate heptahydrate dissolved in 200 g of deionized water was added to the reactor. The pH of the aqueous medium in the reactor was 9.5.

(22) Then, a monomer mixture gas of TFE/P=88/12 (molar ratio) was injected at 25° C. so that the pressure in the reactor would be 2.47 MPaG. The anchor blade was rotated at 300 rpm, and 4.0 g of C4DI was added. Then, Rongalit was added to the reactor to initiate the polymerization reaction. After the polymerization reaction started, Rongalit was continuously added to the reactor by a high pressure pump.

(23) At a point when the amount of the TFE/P monomer mixture gas injected reached 400 g, addition of Rongalit was terminated, and 12.4 mL of AGE was injected to the reactor by nitrogen back pressure. At a point when the total amount of the TFE/P monomer mixture gas injected reached 500 g, the internal temperature of the reactor was cooled to 10° C. to terminate the polymerization reaction to obtain a latex. The amount of Rongalit added from initiation of the polymerization to termination of the polymerization was 40 g. The polymerization time was 5 hours.

(24) To the obtained latex, a 5 mass % aqueous solution of calcium chloride was added to aggregate the latex thereby to precipitate fluorinated elastic copolymer in Ex. 1. The precipitated fluorinated elastic copolymer in Ex. 1 was collected by filtration, washed with deionized water and dried in an oven at 100° C. for 15 hours to obtain 500 g of white fluorinated elastic copolymer in Ex. 1. The copolymer composition of the fluorinated elastic copolymer in Ex. 1 was TFE units/P units/AGE units=56/44/0.4 (molar ratio).

(25) (Ex. 2)

(26) Monomers were polymerized in the same manner as in Ex. 1 except that the amount of AGE injected was 37.2 mL to obtain a latex containing fluorinated elastic copolymer in Ex. 2. In Ex. 2, at a point when the total amount of the TFE/P monomer mixture gas injected reached 420 g, the polymerization reaction was terminated. The amount of Rongalit added from initiation of the polymerization to termination of the polymerization was 39 g. The polymerization time was 4.5 hours.

(27) In the same manner as in Ex. 1, the fluorinated elastic copolymer in Ex. 2 was recovered from the latex, washed and dried to obtain 420 g of white fluorinated elastic copolymer in Ex. 2. The copolymer composition of the fluorinated elastic copolymer in Ex. 2 was TFE units/P units/AGE units=56/44/0.5 (molar ratio).

(28) (Ex. 3)

(29) Monomers were polymerized in the same manner as in Ex. 1 except that the monomer (b) injected was 18.8 mL of GO-BVE to obtain a latex containing fluorinated elastic copolymer in Ex. 3. The amount of Rongalit added from initiation of the polymerization to termination of the polymerization was 39 g. The polymerization time was 5 hours.

(30) In the same manner as in Ex. 1, the fluorinated elastic copolymer in Ex. 3 was recovered from the latex, washed and dried to obtain 500 g of pale yellow fluorinated elastic copolymer in Ex. 3. The copolymer composition of the fluorinated elastic copolymer in Ex. 3 was TFE units/P units/GO-BVE units=56/44/0.5 (molar ratio).

(31) (Ex. 4)

(32) Monomers were polymerized in the same manner as in Ex. 1 except that the monomer (b) injected was 13.2 mL of HBVE to obtain a latex containing fluorinated elastic copolymer in Ex. 4. The amount of Rongalit added from initiation of the polymerization to termination of the polymerization was 39 g. The polymerization time was 6 hours.

(33) In the same manner as in Ex. 1, the fluorinated elastic copolymer in Ex. 4 was recovered from the latex, washed and dried to obtain 482 g of pale yellow fluorinated elastic copolymer in Ex. 4. The copolymer composition of the fluorinated elastic copolymer in Ex. 4 was TFE units/P units/HBVE units=56/44/0.6 (molar ratio).

(34) (Ex. 5)

(35) Monomers were polymerized in the same manner as in Ex. 1 except that AGE was not added, to obtain a latex containing fluorinated elastic copolymer in Ex. 5. The amount of Rongalit added from initiation of the polymerization to termination of the polymerization was 40 g. The polymerization time was about 5.5 hours.

(36) In the same manner as in Ex. 1, the fluorinated elastic copolymer in Ex. 5 was recovered from the latex, washed and dried to obtain 477 g of white fluorinated elastic copolymer in Ex. 5. The copolymer composition of the fluorinated elastic copolymer in Ex. 5 was TFE units/P units=56/44 (molar ratio).

(37) (Ex. 6)

(38) Monomers were polymerized in the same manner as in Ex. 1 except that the amount of AGE injected was 4.0 mL to obtain a latex containing fluorinated elastic copolymer in Ex. 6. The amount of Rongalit added from initiation of the polymerization to termination of the polymerization was 41 g. The polymerization time was about 5.5 hours.

(39) In the same manner as in Ex. 1, the fluorinated elastic copolymer in Ex. 6 was recovered from the latex, washed and dried to obtain 518 g of white fluorinated elastic copolymer in Ex. 6. The copolymer composition of the fluorinated elastic copolymer in Ex. 6 was TFE units/P units/AGE units=56/44/0.08 (molar ratio).

(40) (Ex. 7)

(41) Monomers were polymerized in the same manner as in Ex. 1 except that C4DI was not added, to obtain a latex containing fluorinated elastic copolymer in Ex. 7. The amount of Rongalit added from initiation of the polymerization to termination of the polymerization was 42 g. The polymerization time was about 6 hours.

(42) In the same manner as in Ex. 1, the fluorinated elastic copolymer in Ex. 7 was recovered from the latex, washed and dried to obtain 410 g of white fluorinated elastic copolymer in Ex. 7.

(43) (Ex. 8)

(44) Monomers were polymerized in the same manner as in Ex. 1 except that C4DI was not added, and 12.4 mL of AGE to be injected was divided into four, and 3.1 mL of AGE was intermittently added every 100 g of the TFE/P monomer mixture gas injected, to obtain a latex containing fluorinated elastic copolymer in Ex. 8. The amount of Rongalit added from initiation of the polymerization to termination of the polymerization was 40 g. The polymerization time was about 6 hours.

(45) In the same manner as in Ex. 1, the fluorinated elastic copolymer in Ex. 8 was recovered from the latex, washed and dried to obtain 428 g of white fluorinated elastic copolymer in Ex. 8.

(46) <Analysis and Evaluation of Fluorinated Elastic Copolymer>

(47) With respect to the fluorinated elastic copolymers in Ex. 1 to 6, whether or not the units (b) were contained was analyzed by NMR. The fluorinated elastic copolymers in Ex. 7 and 8 had low solubility and were thereby not analyzed by NMR.

(48) The fluorinated elastic copolymers in Ex. 1 to 4 and 6 were confirmed to have the units (b), since a peak assigned to a carbon-oxygen bond was confirmed in NMR spectra of the fluorinated elastic copolymers in Ex. 1 to 4 and 6.

(49) Further, the structure of the terminal of the fluorinated elastic copolymers in Ex. 1 to 8 was analyzed by pyrolysis gas chromatography.

(50) The fluorinated elastic copolymers in Ex. 1, 2 and 6 were confirmed to have an iodine atom bonded to the terminal of a molecular chain and have an AGE unit adjacent to the iodine atom.

(51) The fluorinated elastic copolymer in Ex. 3 was confirmed to have an iodine atom bonded to the terminal of a molecular chain and have a GO-BVE unit adjacent to the iodine atom.

(52) The fluorinated elastic copolymer in Ex. 4 was confirmed to have an iodine atom bonded to the terminal of a molecular chain and have a HBVE unit adjacent to the iodine atom.

(53) The fluorinated elastic copolymer in Ex. 5 was confirmed to have an iodine atom bonded to the terminal of a molecular chain but have no unit (b).

(54) The fluorinated elastic copolymers in Ex. 7 and 8 were confirmed to have no iodine atom bonded to the terminal of a molecular chain, since no iodine material was added.

(55) The fluorinated elastic copolymer in Ex. 5 was dissolved in THF and subjected to measurement of the mass average molecular weight as calculated as polystyrene by means of gel permeation chromatography (GPC), whereupon it was 150,000.

(56) With respect to the fluorinated elastic copolymers in Ex. 1 to 4 and 6 to 8, the solubility in THF was different from the solubility of the fluorinated elastic copolymer in Ex. 5 in THF, and the measurement under the same conditions was not conducted.

(57) However, as described above, the elastic shear modulus G′ is an index of the molecular weight and the flowability, and a high elastic shear modulus G′ means a high molecular weight and a low flowability. As described hereinafter, the elastic shear moduli G′ of the fluorinated elastic copolymers in Ex. 1 to 4 and 6 were close to the elastic shear modulus G′ of the fluorinated elastic copolymer in Ex. 5, and accordingly it is estimated that the mass average molecular weights of the fluorinated elastic copolymers in Ex. 1 to 4 and 6 are close to that of the fluorinated elastic copolymer in Ex. 5.

(58) With respect to crosslinked products of the fluorinated elastic copolymers in Ex. 1 to 8, the density and the elastic shear modulus G′ were measured, and adhesion to SUS or PI was evaluated. The results are shown in Table 1.

(59) TABLE-US-00001 TABLE 1 Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7 Ex. 8 Monomer (b) AGE AGE GO-BVE HBVE — AGE AGE AGE Amount of 105 316 106 110 — 34 105 105 monomer (b) charged [mmol] Amount of C4DI 8.8 8.8 8.8 8.8 8.8 8.8 0.0 0.0 charged [mmol] Proportion of units 0.4 0.5 0.5 0.6 — Less — — (b) to all units in than 0.09 fluorinated elastic copolymer [mol %] Content of iodine 0.4 0.5 0.4 0.4 0.4 — 0.0 0.0 atoms to 100 mass % of fluorinated elastic copolymer [mass %] Elastic shear 206 163 202 207 235 266 521 470 modulus G′ [kPa] Adhesion to SUS ◯ ◯ ◯ ◯ X Δ X X Adhesion to PI ◯ ◯ ◯ ◯ X X X X

(60) The fluorinated elastic copolymers in Ex. 1 to 4, which had an iodine atom bonded to the terminal of the molecular chain and a unit (b) adjacent to the iodine atom and which had a proportion of the units (b) of from 0.09 to 2.0 mol %, was excellent in adhesion, heat resistance and chemical resistance.

(61) In Ex. 1 to 4, the monomer (a), the monomer (b) and the monomer (c) were copolymerized after units in an amount of at least 80 mol % to all units of the fluorinated elastic copolymer were formed, and accordingly the obtainable fluorinated elastic copolymer was excellent in processability and mechanical properties.

(62) The fluorinated elastic copolymer in Ex. 5, which had no units (b), was inferior in adhesion.

(63) The fluorinated elastic copolymer in Ex. 6, which had a proportion of the units (b) of less than 0.09 mol %, was inferior in the adhesion.

(64) The fluorinated elastic copolymers in Ex. 7 and 8 were inferior in the adhesion. Further, since no C4DI was added, the molecular weight could not be controlled, and flowability of the fluorinated elastic copolymer was low.

INDUSTRIAL APPLICABILITY

(65) The fluorinated elastic copolymer of the present invention and a fluorinated elastic copolymer obtained by the production method of the present invention are suitable for materials such as a composite sealing material, an O-ring, a sheet, a gasket, an oil seal, a diaphragm and a V-ring. Further, they are applicable to a heat resistant chemical resistant sealing material, a heat resistant oil resistant sealing material, an electric wire coating material, a sealing material for a semiconductor device, a corrosion resistant rubber coating material, and a sealing material for a urea resistant grease.

(66) This application is a continuation of PCT Application No. PCT/JP2018/044285, filed on Nov. 30, 2018, which is based upon and claims the benefit of priority from Japanese Patent Application No. 2017-234569 filed on Dec. 6, 2017. The contents of those applications are incorporated herein by reference in their entireties.