FUKUSHI TATSUO (US)
MACHIDA TAKESHI (JP)
NISHIOKA HIROSHI (JP)
| WO2019239288A1 | 2019-12-19 | |||
| WO2019230456A1 | 2019-12-05 |
| US3729313A | 1973-04-24 | |||
| US3741769A | 1973-06-26 | |||
| US3808006A | 1974-04-30 | |||
| US4250053A | 1981-02-10 | |||
| US4394403A | 1983-07-19 | |||
| US5545676A | 1996-08-13 | |||
| US5225504A | 1993-07-06 | |||
| US20150083979A1 | 2015-03-26 | |||
| US20200002589A1 | 2020-01-02 |
| What is claimed is: 1. A coatable curable fluoropolymer composition comprising: a. partially fluorinated amorphous polymer comprising at least one of an iodine, a bromine, and a nitrile cure site; b. curing initiator c. crosslinking agent; and d. a liquid solvent comprising a hydrochlorofluoropropene. 2. The coatable composition of claim 1, wherein the coatable curable fluoropolymer composition has a viscosity at 25 °C of at least 10 cPs to at most 1,000,000 cP. 3. The coatable composition of any one of the previous claims, wherein the liquid solvent consists essentially of the hydrochlorofluoropropene. 4. The coatable composition of any one of the previous claims, wherein the hydrochlorofluoropropene has a boiling point above room temperature. 5. The coatable composition of any one of the previous claims, wherein the hydrochlorofluoropropene is selected from at least one of C(X1)(C1)=C(X2)CX3X4X5 , C(X1)(X2)=C(C1)CX3X4X5 , and C(X1)(X2)=C(X3)C(C1)X4X5 , where X1, X2, X3, X4, and X5 are independently selected from H, F, or Cl, where the compound comprises at least one H and there are more fluorine atoms than hydrogen atoms. 6. The coatable composition of any one of the previous claims, wherein the coatable curable fluoropolymer composition comprises at least 10 wt % and at most 99 wt % of the liquid solvent. 7. The coatable composition of any one of the previous claims, wherein the hydrochlorofluoropropene substantially solubilizes the partially fluorinated amorphous polymer. 8. The coatable composition of any one of the previous claims, wherein the coatable curable fluoropolymer composition comprises 1-90 % by weight of the partially fluorinated amorphous polymer. 9. The coatable composition of any one of the previous claims, wherein the partially fluorinated amorphous polymer is derived from 3-35 wt % TFE; 25-65 wt % VDF; and 16- 65 wt % HFP. 10. The coatable composition of any one of the previous claims, wherein the partially fluorinated amorphous polymer is derived from 25-65 wt % vinylidene fluoride. 11. The coatable composition of any one of the previous claims, wherein the curing initiator is a photoinitiator. 12. The coatable composition of claim 11, wherein the photoinitiator is at least one of 2-benzyl- 2-dimethylamino-l-(4-morpholinophenyl)-butanone-l, phenyl bis(2,4,6-trimethyl benzoyl) phosphine oxide, diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide, and bis (eta 5-2,4- cyclopentadien-l-yl) bis [2,6-difluoro-3-(lH-pyrrol-l-yl)phenyl]titanium. 13. The coatable composition of claim 11, wherein the photoinitiator comprises a photosensitizer, and at least one of an iodonium salt or an electron donor. 14. The coatable composition of any one of claims 1-10, wherein the curing initiator is a peroxide. 15. The coatable composition of any one of the previous claims, wherein the crosslinking agent is selected from at least one of crosslinker is tri(methyl)allyl isocyanurate, triallyl isocyanurate, tri(methyl)allyl cyanurate, poly-triallyl isocyanurate, xylylene-bis(diallyl isocyanurate), N,N'-m-phenylene bismaleimide, diallyl phthalate, tris(diallylamine)-s- triazine, triallyl phosphite, 1,2-polybutadiene, ethyleneglycol diacrylate, diethyleneglycol diacrylate, or CH2=CH-Rfi-CH=CH2 wherein Rn is a perfluoroalkylene having from 1 to 8 carbon atoms. 16. The coatable composition of any one of the previous claims, wherein coatable curable fluoroelastomer composition further comprises at least one of a pigment, silica, carbon black, graphite, carbon nanotube, MgO, TiO2, alumina, and boron nitride. 17. The coatable composition of any one of the previous claims, wherein the liquid has a boiling point greater than 23°C. 18. The coatable composition of any one of the previous claims, wherein the coating composition is dispensable. 19. A cured composition derived from the coatable composition according to any one of claims 1-18. 0. A method of making a gasket, the method comprising: applying the coatable composition of any one of claims 1-18 onto a substrate; and curing the coatable composition. 1. The method of claim 20, wherein the substrate is a part which houses the gasket. 2. The method of claim 20, wherein the substrate is a continuous web and curing the coatable composition results in a cured web composition, optionally, further comprising cutting the cured web composition into a plurality of gaskets. 3. The method of any one of claims 20-22, wherein curing is initiated with electromagnetic radiation of 360 nanometers to 1100 nanometers. 4. The method of any one of claims 20-22, wherein curing is initiated with thermal radiation. |
TECHNICAL FIELD
[0001] The present disclosure relates to a composition comprising a partially fluorinated amorphous polymer in a liquid solvent comprising hydrochlorofluoropropene. Methods of making an article using the composition are disclosed herein.
SUMMARY
[0002] Due to their elasticity and inertness to chemical reactivity, heat, or both, fluoropolymeric elastomers are useful in making articles such as seals, gaskets, o-rings, and hoses. Many of the copolymers used to make fluoropolymeric elastomers have relatively high viscosities in comparison to non-fluorinated materials used to make elastomers (e.g., silicones for silicone elastomers). Typically, solvents such as acetone, 2-butanone, 4-methyl-2 -pentanone, cyclohexanone, methyl formate, ethyl formate, methyl acetate, ethyl acetate, n-butyl acetate, tertbutyl acetate, or dimethyl carbonate are used to reduce the viscosity of the fluoropolymeric compositions. However, these solvents are flammable, and therefore explosion-protected measures are needed for manufacturing processes and equipment.
[0003] Thus, there is a desire to reduce the cost of fluoropolymeric elastomeric articles. Such cost reductions can include using a partially fluorinated polymer, which is typically cheaper than its perfluororinated counterpart; using a non-flammable, more environmentally friendly solvent; and optionally making products in a continuous fashion versus a batch-type process.
[0004] In one aspect, a curable composition is disclosed. The curable fluoropolymer composition comprising:
(a) a partially fluorinated amorphous polymer comprising at least one of an iodine, a bromine, and a nitrile cure site;
(b) a curing initiator;
(c) a crosslinking agent; and
(d) a liquid solvent comprising a hydrochlorofluoropropene.
[0005] In one embodiment, the curing initiator is a photoinitiator.
[0006] In another embodiment, the curing initiator is a peroxide cure initiator.
[0007] In one aspect, a method of making a gasket is disclosed. The method comprising (i) applying a coatable composition comprising a partially fluorinated amorphous polymer comprising at least one of an iodine, a bromine, and a nitrile cure site; a curing initiator; a crosslinking agent; and a liquid solvent comprising a hydrochlorofluoropropene; and (ii) curing the coatable composition.
[0008] The above summary is not intended to describe each embodiment. The details of one or more embodiments of the invention are also set forth in the description below. Other features, objects, and advantages will be apparent from the description and from the claims.
DETAILED DESCRIPTION
[0009] As used herein, the term
“and/or” is used to indicate one or both stated cases may occur, for example A and/or B includes, (A and B) and (A or B);
“backbone” refers to the main continuous chain of the polymer;
“crosslink” refers to connecting two pre-formed polymer chains using chemical bonds or chemical groups;
“cure site” refers to functional groups, which may participate in crosslinking;
“interpolymerized” refers to monomers that are polymerized together to form a polymer backbone;
“monomer” is a molecule which can undergo polymerization which then form part of the essential structure of a polymer;
“perfluorinated” means a group or a compound derived from a hydrocarbon wherein all hydrogen atoms have been replaced by fluorine atoms. A perfluorinated compound may however still contain atoms other than fluorine and carbon atoms, like oxygen atoms, chlorine atoms, bromine atoms and iodine atoms; and
“polymer” refers to a macrostructure having a number average molecular weight (Mn) of at least 10,000, 30,000, 50,000, 100,000, 200,000, 500,000, or even at least 1,000,000 dalton and not such a high molecular weight as to cause premature gelling of the polymer.
[0010] Also herein, recitation of ranges by endpoints includes all numbers subsumed within that range (e.g., 1 to 10 includes 1.4, 1.9, 2.33, 5.75, 9.98, etc.).
[0011] Also herein, recitation of “at least one” includes all numbers of one and greater (e.g., at least 2, at least 4, at least 6, at least 8, at least 10, at least 25, at least 50, at least 100, etc.).
[0012] Disclosed herein is a curable fluoropolymer composition. This curable fluoropolymer composition comprises a partially fluorinated amorphous polymer in a liquid solvent, wherein the liquid solvent comprises hydrochlorofluoropropene. These curable fluoropolymer compositions can be cured via peroxide or actinic radiation. The compounds curable fluoropolymer compositions of the present disclosure have good environmental properties as well as having good performance attributes, such as non-flammability, and ability to cure. [0013] Amorphous Fluoropolymer
[0014] The fluoropolymers of the present disclosure are amorphous, meaning that there is an absence of long-range order (i.e., in long-range order the arrangement and orientation of the macromolecules beyond their nearest neighbors is understood). The amorphous polymer has no detectable crystalline character by DSC (differential scanning calorimetry). If studied under DSC, the fluoropolymer would have no melting point or melt transitions with an enthalpy more than 0.002, 0.01, 0.1, or even 1 Joule/g from the second heat of a heat/cool/heat cycle, when tested using a DSC thermogram with a first heat cycle starting at -85°C and ramped at 10 °C/min to 350°C, cooling to -85°C at a rate of 10°C/min and a second heat cycle starting from -85°C and ramped at 10 °C/min to 350°C.
[0015] In one embodiment, the amorphous fluoropolymers of the present disclosure decompose above a temperature of 350, 325, 300, or even 275°C.
[0016] The amorphous fluoropolymers of the present disclosure are partially fluorinated. A partially fluorinated amorphous polymer comprises both C-F and C-H bonds along the carbon backbone of the polymer chain.
[0017] In one embodiment, the amorphous fluoropolymer of the present disclosure comprises at least 30, 50, 60, 66, 68, 70, or even 71% by weight of fluorine, and no more than 72, or even 73% by weight of fluorine (based on the total weight of the amorphous fluoropolymer).
[0018] In one embodiment, the amorphous fluoropolymer is derived from at least one hydrogencontaining monomer and at least one fluorine-containing monomer. In one embodiment, the amorphous fluoropolymer is derived from a monomer comprising both an olefinic hydrogen and an olefinic fluorine, such as vinylidene fluoride. Hydrogen containing monomers include those known in the art. The hydrogen-containing monomers may or may not contain fluorine atoms. Exemplary hydrogen-containing monomers include: vinylidene fluoride, pentafluoropropylene (e.g., 2-hydropentafluoropropylene), vinyl fluoride, trifluoroethylene, propylene, ethylene, isobutylene, and combinations thereof. Fluorine-containing monomers include those known in the art. Exemplary fluorine-containing monomers include: hexafluoropropene, tetrafluoroethylene, chlorotrifluoroethylene, perfluoro(alkylvinyl ether) (such as perfluoromethyl vinyl ether, perfluoropropyl vinyl ether, CF2=CFOCF2CF2CF2OCF3, CF2=CFOCF2OCF2CF2CF3, CF2=CFOCF2OCF2CF3, and CF2=CFOCF2OCF3), and combinations thereof.
[0019] In one embodiment, the amorphous fluoropolymer comprises interpolymerized units derived from vinylidene fluoride (VDF). In one embodiment, the amorphous fluoropolymer is derived from 30-70 wt % VDF, or even 35-65 wt % VDF.
[0020] In one embodiment, the amorphous fluoropolymer comprises interpolymerized units derived from (i) hexafluoropropylene (HFP), tetrafluoroethylene (TFE), and vinylidene fluoride (VDF); (ii) HFP and VDF, (iii) VDF and perfluoromethyl vinyl ether (PMVE), (iv) VDF, TFE, and PMVE, (v) VDF, TFE, and propylene, (vi) ethylene, TFE, and PMVE, (vii) TFE, VDF, PMVE, and ethylene, and (viii) TFE, VDF, and CF2=CFO(CF2)3OCF3.
[0021] In one embodiment, the amorphous fluoropolymer comprises interpolymerized units derived from at least 30, 35, 40, 45, 50, 55, or even 60 wt% and at most 65, 70, or even 75 wt% VDF; and at least 25, 30 or even 35 wt% and at most 40, 45, 50, 60, 65, or even 70 wt% HFP. In one embodiment, the amorphous fluoropolymer comprises interpolymerized units derived from at least 30, 35, 40, 45, 50, 55, or even 60 wt% and at most 65, 70, or even 75 wt% VDF; at least 10, 15, 20, or even 25 wt% and at most 27, 30, 35, 40, or even 45 wt% HFP; and at least 3, 5, 7, or even 9 wt% and at most 10, 12, 15, 20, 25, or even 15 wt% TFE. In one embodiment, the amorphous fluoropolymer comprises interpolymerized units derived from at least 25, 30, or even 35 wt% and at most 40, 45, 50, 55, or even 65 wt% VDF; at least 15, 20, 25, or even 30 wt% and at most 35, 40, or even 45 wt% HFP; and at least 1, 5, 10 15, 20, or even 30 wt% and at most 30, 35, or even 40 wt% TFE. In one embodiment, the amorphous fluoropolymer comprises interpolymerized units derived from at least 30, 35, 40, or even 45 wt% and at most 55, 60, or even 65 wt% VDF; at least 25, 30, or even 35 wt% and at most 40, 45, 50, 55, 60, or even 65 wt% PMVE; and at least 3, 5, or even 7 wt% and at most 10, 15, or even 20 wt% TFE. In one embodiment, the amorphous fluoropolymer comprises interpolymerized units derived from at least 30, 35, 40, or even 45 wt% and at most 55, 60, or even 65 wt% VDF; at least 10, 15, 20, 25, or even 35 wt% and at most 40, 45, 50, 55, or even 60 wt% PMVE; and at least 10 15, or even 20 wt% and at most 25, 30, or even 35 wt% TFE. In one embodiment, the amorphous fluoropolymer comprises interpolymerized units derived from at least 5, 10, or even 15 wt% and at most 20, 25, or even 30 wt% VDF; at least 5, 10, or even 15 wt% and at most 20, 25, or even 30 wt% propylene; and at least 50, 55, 60, or even 65 wt% and at most 70, 75, 80, or even 85 wt% TFE. In one embodiment, the amorphous fluoropolymer comprises interpolymerized units derived from a perfluorinated ether monomer of the formula CF2=CF(CF2)pO(RfiO)n(Rf2O) m Rf where Rn and Rf2 are different linear or branched perfluoroalkylene groups containing 2, 3, 4, 5, or 6 carbon atoms; m and n are independently 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, p is 0 or 1, and Rfis a perfluoroalkyl group of 1, 2, 3, 4, 5, or 6 carbon atoms. Such perfluorinated ether compounds are known in the art and include for example, perfluorinated alkyl vinyl ether such as perfluorinated methyl vinyl ether (PMVE), perfluorinated alkyl allyl ether such as perfluorinated methyl allyl ether, and perfluorinated alkoxy vinyl ether and perfluorinated alkoxy allyl ether.
[0022] The amorphous fluoropolymer of the present disclosure contains cure sites which facilitate cross-linking of the fluoropolymer. These cure sites comprise at least one of I, Br, and CN. The fluoropolymer may be polymerized in the presence of a chain transfer agent and/or cure site monomers to introduce cure sites into the fluoropolymer. Such cure site monomers and chain transfer agents are known in the art. Exemplary chain transfer agents include: an iodo-chain transfer agent, a bromo-chain transfer agent, or a chloro-chain transfer agent. For example, suitable iodo-chain transfer agent in the polymerization include: the formula of RI X , where (i) R is a perfluoroalkyl or chloroperfluoroalkyl group having 3 to 12 carbon atoms; and (ii) x = 1 or 2. The iodo-chain transfer agent may be a perfluorinated iodo-compound. Exemplary iodo-perfluoro- compounds include 1,3-diiodoperfluoropropane, 1,4-diiodoperfluorobutane, 1, 6- diiodoperfluorohexane, 1,8-diiodoperfluorooctane, 1,10-diiodoperfluorodecane, 1,12- diiodoperfluorododecane, 2-iodo- 1 ,2-dichloro-l, 1 ,2-trifluoroethane, 4-iodo- 1,2,4- trichloroperfluorobutan, and mixtures thereof. In some embodiments, the iodo-chain transfer agent is of the formula I(CF2)n-O-Rf-(CF2) m I, wherein n is 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, m is is 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 and Rf is a partially fluorinated or perfluorinated alkylene segment, which can be linear or branched and optionally comprises at least one catenated ether linkage. Exemplary compounds include: I-CF2-CF2-O-CF2-CF2-I, I-CF(CF 3 )-CF2-O-CF2-CF 2 -I, I-CF 2 -CF 2 -O-CF(CF 3 )- CF2-O-CF2-CF2-I, I-(CF(CF 3 )-CF 2 -O)2-CF2-CF 2 -I, I-CF 2 -CF2-O-(CF2)2-O-CF2-CF 2 -I, I-CF2-CF2- O-(CF 2 ) 3 -O-CF2-CF 2 -I, and I-CF 2 -CF 2 -O-(CF 2 ) 4 -O-CF 2 -CF 2 -I, I-CF 2 -CF 2 -CF 2 -O-CF 2 -CF 2 -I, and I- CF2-CF2-CF2-O-CF(CF 3 )-CF2-O-CF2-CF2-I, In some embodiments, the bromine is derived from a brominated chain transfer agent of the formula: RBr x , where (i) R is a perfluoroalkyl or chloroperfluoroalkyl group having 3 to 12 carbon atoms; and (ii) x = 1 or 2. The chain transfer agent may be a perfluorinated bromo-compound.
[0023] Cure site monomers, if used, comprise at least one of a bromine, iodine, and/or nitrile cure moiety.
[0024] In one embodiment, the cure site monomers may be of the formula: CX2=CX(Z), wherein: (i) X each is independently H or F; and (ii) Z is I, Br, R/-U wherein U=I or Br and R/=a perfluorinated or partially perfluorinated alkylene group optionally containing ether linkages. In addition, non-fluorinated bromo-or iodo-olefins, e.g., vinyl iodide and allyl iodide, can be used. Exemplary cure site monomers include: CH2=CHI, CF2=CHI, CF 2 =CFI, CH2=CHCH2l, CF 2 =CFCF 2 I, ICF2CF2CF2CF2I, CH2=CHCF 2 CF 2 I, CF2=CFCH 2 CH 2 I, CF 2 =CFCF 2 CF 2 I, CH 2 =CH(CF2)6CH 2 CH2l, CF 2 =CFOCF 2 CF 2 I, CF2=CFOCF 2 CF 2 CF2l, CF2=CFOCF 2 CF2CH 2 I, CF2CFCF2OCH2CH2I, CF2=CFO(CF 2 ) 3 -OCF2CF 2 I, CH 2 =CHBr, CF 2 =CHBr, CF 2 =CFBr, CH 2 =CHCH 2 Br, CF 2 =CFCF 2 Br, CH2=CHCF 2 CF 2 Br, CF2=CFOCF 2 CF 2 Br, CF 2 =CFC1, 1-CF 2 - CF2CF2-O-CFCF2, 1-CF 2 -CF2CF2-O-CF 2 CF=CF2, 1-CF2-CF2-O-CF2-CFCF2, 1-CF(CF 3 )-CF 2 -O- CF=CF 2 , 1-CF(CF 3 )-CF2-O-CF 2 -CF=CF 2 , 1-CF 2 -CF2-O-CF(CF 3 )-CF2-O-CF=CF 2 , 1-CF2-CF2-O- CF(CF 3 )-CF2-O-CF2-CF=CF2, 1-CF 2 -CF2-(O-(CF(CF 3 )-CF2)2-O-CF=CF 2 , I-CF 2 -CF 2 -(O-(CF(CF 3 )- CF2)2-O-CF2-CF=CF2, Br-CF2-CF2-O-CF2-CF=CF 2 , Br-CF(CF 3 )-CF 2 -O-CF=CF 2 , 1-CF2-CF2-CF2- O-CF(CF 3 )-CF 2 -O-CF=CF 2 , I-CF 2 -CF 2 -CF 2 -O-CF(CF 3 )-CF 2 -O-CF 2 -CF=CF 2 , 1-CF 2 -CF 2 -CF 2 -(O- (CF(CF 3 )-CF 2 ) 2 -O-CF=CF 2 , 1-CF 2 -CF 2 -CF 2 -O-(CF(CF 3 )-CF 2 -O) 2 -CF 2 -CF=CF 2 , Br-CF 2 -CF 2 -CF 2 - O-CF=CF 2 , Br-CF 2 -CF 2 -CF 2 -O-CF 2 -CF=CF 2 , 1-CF 2 -CF 2 -O-(CF 2 ) 2 -O-CF=CF 2 , 1-CF 2 -CF 2 -O- (CF 2 ) 3 -O-CF=CF 2 , 1-CF 2 -CF 2 -O-(CF 2 ) 4 -O-CF=CF 2 , 1-CF 2 -CF 2 -O-(CF 2 ) 2 -O-CF 2 -CF=CF 2 , I-CF 2 - CF 2 -O-(CF 2 ) 3 -O-CF 2 -CF=CF 2 , 1-CF 2 -CF 2 -O-(CF 2 ) 2 -O-CF(CF 3 )CF 2 -O-CF 2 =CF 2 , I-CF 2 -CF 2 -O- (CF 2 ) 2 -O-CF(CF 3 )CF 2 -O-CF 2 -CF 2 =CF 2 , Br-CF 2 -CF 2 -O-(CF 2 ) 2 -O-CF=CF 2 , Br-CF 2 -CF 2 -O-(CF 2 ) 3 - O-CF=CF 2 , Br-CF 2 -CF 2 -O-(CF 2 ) 4 -O-CF=CF 2 , and Br-CF 2 -CF 2 -O-(CF 2 ) 2 -O-CF 2 -CF=CF 2 [0025] In another embodiment, the cure site monomers comprise nitrile -containing cure moieties. Useful nitrile-containing cure site monomers include nitrile-containing fluorinated olefins and nitrile-containing fluorinated vinyl ethers, such as: perfluoro(8-cyano-5-methyl-3,6-dioxa-l- octene); CF 2 =CF-O-(CF 2 ) n -CN where n = 2-12, preferably 2, 3, 4, 5, or 6. Examples of a nitrile- containing cure site monomer include CF 2 =CF-O-[CF 2 -CFCF 3 -O] n -CF 2 -CF(CF 3 )-CN; where n is 0, 1, 2,3, or 4, preferably 0, 1, or 2; CF 2 =CF-[OCF 2 CF(CF 3 )] x -O-(CF 2 ) n -CN; where x is 1 or 2, and n is 1, 2, 3, or 4; and CF 2 =CF-O-(CF 2 ) n -O-CF(CF 3 )CN where n is 2, 3, or 4. Exemplary nitrile- containing cure site monomers include: CF 2 =CFO(CF 2 )5CN, CF 2 =CFOCF 2 CF(CF 3 )OCF 2 CF 2 CN, CF 2 =CFOCF 2 CF(CF 3 )OCF 2 CF(CF 3 )CN, CF 2 =CFOCF 2 CF 2 CF 2 OCF(CF 3 )CN, CF 2 =CFOCF 2 CF(CF 3 )OCF 2 CF 2 CN; and combinations thereof.
[0026] The amorphous fluoropolymer composition of the present disclose comprises iodine, bromine, and/or nitrile cure sites, which are subsequently used to crosslink the amorphous fluoropolymer. In one embodiment, the amorphous fluoropolymer composition of the present disclosure comprises at least 0.1, 0.5, 1, 2, or even 2.5 wt% of iodine, bromine, and/or nitrile groups versus the total weight of the amorphous fluoropolymer. In one embodiment, the amorphous fluoropolymer of the present disclosure comprises no more than 3, 5, or even 10 wt% of iodine, bromine, and/or nitrile groups versus the total weight of the amorphous fluoropolymer. [0027] In one embodiment, the amorphous fluoropolymer comprising cure sites is blended with a second amorphous fluoropolymer, which may or may not comprise bromine, iodine, and/or nitrile cure sites.
[0028] Cure initiator
[0029] The curable compositions of the present disclosure comprise a cure initiator. In one embodiment, the initiator is a photoinitiator, which when exposed to actinic radiation, causes the composition to at least partially cure. As used herein, partially cured refers to a state that the crosslinking degree in the fluoropolymer is higher than that in an uncrosslinked fluoropolymer, which can be observed by an increase in the viscosity of the fluoropolymer.
[0030] The photoinitiators of the present disclosure are effective in causing cross-linking of the curable compositions of the present disclosure when exposed to actinic radiation. Such photoinitiators are known in the art and commercially available. Ideally, the photoinitiators are soluble or dispersible in the present composition (e.g., solvent) to ensure adequate reaction. Two classes of photoinitiator systems are disclosed herein.
[0031] A first photoinitiator system comprises a single component, which when exposed to actinic radiation, cleaves forming two radicals. Such photoinitiators are known in the art. Exemplary photoinitiators of this type include: benzoin ethers (e.g., benzoin methyl ether or benzoin isopropyl ether) or substituted benzoin ethers (e.g., anisoin methyl ether). Other exemplary photoinitiators are substituted acetophenones such as 2,2-diethoxyacetophenone or 2,2- dimethoxy-2 -phenylacetophenone (commercially available under the trade designation “IRGACURE 651” from BASF Corp. (Florham Park, New Jersey) or under the trade designation “ESACURE KB-1” from Sartomer (Exton, Pennsylvania). Still other exemplary photoinitiators are substituted alpha-ketols such as 2-methyl-2-hydroxypropiophenone, aromatic sulfonyl chlorides such as 2-naphthalenesulfonyl chloride, and photoactive oximes such as 1 -phenyl- 1,2- propanedione-2-(O-ethoxycarbonyl)oxime. Other suitable photoinitiators include, for example, 1- hydroxy cyclohexyl phenyl ketone (commercially available under the trade designation “IRGACURE 184” from BASF Corp.), phenyl bis(2,4,6-trimethyl benzoyl) phosphine oxide, diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (commercially available underthe trade designation “IRGACURE 819” from BASF Corp.), 1 -[4-(2-hydroxyethoxy)phenyl] -2-hydroxy-2-methyl- 1 -propane- 1 -one (commercially available under the trade designation “IRGACURE 2959” from BASF Corp.), 2 -benzyl -2 -dimethylamino- 1- (4-morpholinophenyl)butanone (commercially available under the trade designation “IRGACURE 369” from BASF Corp.), 2-methyl-l-[4-(methylthio)phenyl]-2-morpholinopropan-l-one (commercially available under the trade designation “IRGACURE 907” from BASF Corp.), and 2- hydroxy-2 -methyl- 1 -phenyl propan- 1 -one (commercially available underthe trade designation “DAROCUR 1173” from Ciba Specialty Chemicals Corp. (Tarrytown, New York).
[0032] The optimum amounts of the first photoinitiator system depend on the type used. Typical amounts include, but are not limited to, at least 0.01, 0.05, or even 0.1% wt; and at most 1, 3, or even 5 % wt versus the amount of amorphous fluoropolymer.
[0033] A second photoinitiator system is a multiple component system wherein a radical is generated through electron transfer to or from a second compound. For example, the photoinitiator system comprises a first component (A) which is a photosensitizer and a second component which comprises at least one of an iodonium salt (B) or an electron donor compound (C).
[0034] The first component (A) in the photoinitiator system is a photosensitizer compound. The photosensitizer is capable of electromagnetic radiation absorption somewhere within the range of the wavelength(s) of interest (for example if the actinic radiation is in the UV range, the photosensitizer should absorb wavelengths within the UV range). Suitable photosensitizers are believed to include compounds in the following categories: ketones, coumarin dyes (e.g., ketocoumarins), xanthene dyes, acridine dyes, thiazole dyes, thiazine dyes, oxazine dyes, azine dyes, aminoketone dyes, porphyrins, aromatic polycyclic hydrocarbons, p-substituted aminostyryl ketone compounds, aminotriaryl methanes, merocyanines, squarylium dyes and pyridinium dyes. Ketones (e.g., monoketones or alpha-diketones), ketocoumarins, aminoarylketones and p- substituted aminostyryl ketone compounds are preferred sensitizers. An exemplary photosensitizer includes 2 -isopropylthioxanthone; 2-chlorothioxanthone (ITX); and 9,10-dibutoxyanthracene. [0035] Suitable ketones include monoketones such as 2,2-, 4,4- or 2,4-dihydroxybenzophenone, di-2 -pyridyl ketone, di-2-furanyl ketone, di-2-thiophenyl ketone, benzoin, fluorenone, 2- chlorothioxanthone, acetophenone, benzophenone, and the like. Suitable diketones include aralkyldiketones such as anthraquinone, phenanthrenequinone, and the like. Suitable a-diketones include 2,3-butanedione, 2,3-pentanedione, 2,3-hexanedione, 3,4-hexanedione, 2,3-heptanedione, 3,4-heptanedione, 2,3-octanedione, 4,5 -octanedione, benzil, 2,2'- 3 3'- and 4,4'-dihydroxylbenzil, furil, di-3,3'-indolylethanedione, 2,3-bomanedione (camphorquinone), biacetyl, 1,2- cyclohexanedione, 1,2-naphthaquinone, acenaphthaquinone, and the like.
[0036] The second component can be (i) an iodonium salt, (ii) an electron donor compound, or (iii) an iodonium salt and an electron donor compound.
[0037] Suitable iodonium salts are described in U.S. Pat. Nos. 3,729,313, 3,741,769, 3,808,006, 4,250,053 and 4,394,403, the iodonium salt disclosures of which are incorporated herein by reference. The iodonium salt can be a simple salt (e.g., containing an anion such as Cl’, Br’, Tor C4H5SO3 ) or a metal complex salt (e.g., containing SbFsOH or AsFg ). Mixtures of iodonium salts can be used if desired.
[0038] Exemplary iodonium salts include bis(4-t-butylphenyl)iodonium hexafluoroantimonate (available under the trade designation “FP5034” from Hampford Research Inc., Stratford, CT), bis(4-t-butylphenyl) iodonium hexafluorophosphate (available under the trade designation “FP5035” from Hampford Research Inc.), (4-methoxyphenyl)phenyl iodonium triflate, bis(4-tert- butylphenyl) iodonium camphorsulfonate, bis(4-tert-butylphenyl) iodonium hexafluoroantimonate, bis(4-tert-butylphenyl) iodonium hexafluorophosphate, bis(4-tert-butylphenyl) iodonium tetraphenylborate, bis(4-tert-butylphenyl) iodonium tosylate, bis(4-tert-butylphenyl) iodonium triflate, ([4-(octyloxy)phenyl]phenyliodonium hexafluorophosphate), ([4- (octyloxy)phenyl]phenyliodonium hexafluoroantimonate), (4-isopropylphenyl)(4- methylphenyl)iodonium tetrakis(pentafluorophenyl) borate (available under the trade designation “RHODORSIL 2074” from Bluestar Silicones, East Brunswick, NJ), bis(4-methylphenyl) iodonium hexafluorophosphate (available under the trade designation “OMNICAT 440” from IGM Resins, St. Charles, IL), 4-(2-hydroxy-l-tetradecycloxy)phenyl]phenyl iodonium hexafluoroantimonate. Preferred iodonium salts include diaryliodonium salts such as (4- isopropylphenyl)(4-methylphenyl)iodonium tetrakis(pentafluorophenyl) borate, bis(4- methylphenyl) iodonium hexafluorophosphate, bis(4-t-butylphenyl)iodonium hexafluoroantimonate, and bis(4-t-butylphenyl) iodonium hexafluorophosphate.
[0039] Preferred electron donor compounds include amines (including aminoaldehydes and aminosilanes), ascorbic acid and its salts. The donor can be unsubstituted or substituted with one or more non-interfering substituents. Particularly preferred donors contain an electron donor atom such as a nitrogen, oxygen, phosphorus, or sulfur atom, and an abstractable hydrogen atom bonded to a carbon or silicon atom alpha to the electron donor atom.
[0040] Preferred amine donor compounds include alkyl-, aryl-, alkaryl- and aralkyl-amines such as triethanolamine, N,N'-dimethylethylenediamine, p-N N-dimethyl-aminophenethanol; aminoaldehydes such as p-N,N-dimethylaminobenzaldehyde, p-N,N-diethylaminobenzaldehyde, and 4-morpholinobenzaldehyde.
[0041] Suitable ether donor compounds include 4,4'-dimethoxybiphenyl, 1,2,4-trimethoxybenzene and 1,2,4,5-tetramethoxybenzene.
[0042] The photosensitizer and at least one of the iodonium salt or electron donor are present in "photochemically effective amounts", that is, amounts of each component are sufficient to enable at least partial crosslinking of the fluoropolymer upon exposure to the actinic radiation. Preferably, for every 100 parts of fluoropolymer, the curable composition of the present disclosure contains about 0.005 to about 10 parts (more preferably about 0. 1 to about 4 parts) each of iodonium salt, sensitizer and donor. The amounts of each component are independently variable and thus need not be equal, with larger amounts generally providing faster cure, but shorter shelf life. Sensitizers with high extinction coefficients (e.g., above about 10,000) at the desired wavelength of irradiation for photopolymerization generally are used in reduced amounts. In one embodiment, at least 0.01, 0.05, or even 0.1% wt; and at most 1, 3, or even 5 %wt of the photosensitizer is used versus the amount of amorphous fluoropolymer; if the iodonium salt is used, at least 0.001, 0.01, 0.05, or even 0.1% wt; and at most 1, 3, or even 5 %wt of the iodonium salt is used versus the amount of the amorphous fluoropolymer; and if the electron donor is used, at least 0.001, 0.01, 0.05, or even 0.1% wt; and at most 1, 3, or even 5 %wt of the electron donor is used versus the amount of amorphous fluoropolymer.
[0043] A three component photoinitiator system comprising the photosensitizer, iodonium salt and an electron donor is described in U.S. Pat. No. 5,545,676 (Palazzotto, et al.), herein incorporated by reference with respect to the various components. [0044] The photoinitiator/photosensitizer is activated by irradiation with actinic radiation. As used herein, actinic radiation refers to electromagnetic radiation in the ultraviolet, visible, and infrared wavelengths.
[0045] In another embodiment, the curing initiator is a peroxide. In one embodiment, the peroxide is an organic peroxide, preferably, a tertiary butyl peroxide having a tertiary carbon atom attached to peroxy oxygen.
[0046] Exemplary peroxides include: benzoyl peroxide, dicumyl peroxide, di-tert-butyl peroxide, 2,5-di-methyl-2,5-di-tert-butylperoxyhexane, 2,4-dichlorobenzoyl peroxide, l,l-bis(tert- butylperoxy)-3,3,5-trimethylchlorohexane, tert-butyl peroxy isopropylcarbonate (TBIC), tert-butyl peroxy 2-ethylhexyl carbonate (TBEC), tert-amyl peroxy 2-ethylhexyl carbonate, tert-hexylperoxy isopropyl carbonate, carbonoperoxoic acid, O,O'-l,3-propanediyl OO, OO'-bis( 1,1 -dimethylethyl) ester, tert-butylperoxy benzoate, t-hexyl peroxy-2-ethylhexanoate, t-butyl peroxy-2- ethylhexanoate, di(4-methylbenzoyl) peroxide, laurel peroxide and cyclohexanone peroxide. Other suitable peroxide curatives are listed in U.S. Pat. No. 5,225,504 (Tatsu et al.).
[0047] The amount of peroxide used generally will be at least 0.1, 0.2, 0.4, 0.6, 0.8, 1, 1.2, or even 1.5; at most 2, 2.25, 2.5, 2.75, 3, 3.5, 4, 4.5, 5, or even 5.5 parts by weight per 100 parts of the amorphous fluoropolymer.
[0048] Crosslinking agent
[0049] The curable fluoropolymer composition further comprises a crosslinking agent.
[0050] In one embodiment, the crosslinking agent is a multifunctional polyunsaturated compound, which includes allyl-containing cyanurates, isocyanurates, and phthalates, homopolymers of dienes, and co-polymers of dienes and vinyl aromatics. A wide variety of these crosslinking agents are commercially available including di- and triallyl compounds, divinyl benzene, vinyl toluene, vinyl pyridine, 1,2-cis-poly butadiene and their derivatives. Exemplary Type II coagents include a diallyl ether of glycerin, triallylphosphoric acid, diallyl adipate, diallylmelamine and triallyl isocyanurate (TAIC), tri(methyl)allyl isocyanurate (TMAIC), triallyl iscocyanurate, tri(methyl)allyl cyanurate, poly-triallyl isocyanurate (poly-TAIC), and xylylene-bis(diallyl isocyanurate) (XBD) N,N'-m-phenylene bismaleimide, diallyl phthalate, tris(diallylamine)-s- triazine, triallyl phosphite, 1,2-polybutadiene, ethyleneglycol diacrylate, diethyleneglycol diacrylate, or CH2=CH-Rfi-CH=CH2 wherein Rn is a perfluoroalkylene having from 1 to 8 carbon atoms.
[0051] The amount of crosslinking agent used generally will be at least 0.1, 0.5, or even 1 part by weight per 100 parts of amorphous fluoropolymer; and at most 2, 2.5, 3, or even 5 parts by weight per 100 parts of amorphous fluoropolymer.
[0052] Other Additives [0053] In one embodiment, the compositions of the present disclosure comprise additional components, which facilitate the processing or final properties of the resulting article. For the purpose of, for example, enhancing the strength or imparting the functionality, conventional adjuvants, such as, for example, fillers, acid acceptors, process aids, or colorants may be added to the curable composition. Exemplary fillers include: an organic or inorganic filler such as clay, silica (SiC>2), alumina, iron red, talc, diatomaceous earth, barium sulfate, wollastonite (CaSiCE), calcium carbonate (CaCO,). calcium fluoride, magnesium oxide, titanium oxide, iron oxide and carbon particles (such as graphite or carbon black, carbon fibers, and carbon nanotubes), silicon carbide, boron nitride, molybdenum sulfide, pigment, high temperature plastics, an electrically conductive filler, a heat-dissipating filler, and the like may be added as an optional additive to the composition. Those skilled in the art are capable of selecting specific fillers at required amounts to achieve desired physical characteristics in the vulcanized compound. The filler components may result in a compound that is capable of retaining a preferred elasticity and physical tensile, as indicated by an elongation and tensile strength value, while retaining desired properties such as retraction at lower temperature (TR-10). In one embodiment, the filler content is between 0.01 to 10 % or up to 30 % or even up to 50 % by weight based on the total weight of the composition. [0054] Conventional adjuvants may also be incorporated into the composition of the present disclosure to enhance the properties of the resulting composition. For example, acid acceptors may be employed to facilitate the cure and thermal stability of the compound. Suitable acid acceptors may include magnesium oxide, lead oxide, calcium oxide, calcium hydroxide, dibasic lead phosphite, zinc oxide, barium carbonate, strontium hydroxide, calcium carbonate, hydrotalcite, alkali stearates, magnesium oxalate, or combinations thereof. The acid acceptors are preferably used in amounts ranging from about 1 to about 20 parts per 100 parts by weight of the polymer.
[0055] Liquid solvent
[0056] The partially fluorinated amorphous polymers disclosed herein are dissolved and/or dispersed in a liquid solvent comprising a hydrochlorofluoropropene to form the curable compositions.
[0057] In one embodiment, the hydrochlorofluoropropene is selected from at least one of C X')(CI)=C(X 2 )CX 2 X 4 X\ C(X')(X 2 )=C(CI)CX 2 X 4 X\ and C(X 1 )(X 2 )=C(X 3 )C(C1)X 4 X 5 , where X 1 , X 2 , X 3 , X 4 , and X 5 are independently selected from H, F, or Cl, where the compound comprises at least one hydrogen atom and there are more fluorine atoms than hydrogen atoms. In some instances, the hydrochlorofluoropropene is an isomer, which may be cis or trans in configuration.
[0058] Exemplary hydrochlorofluoropropene compounds include: cis-l-Chloro-3,3,3- trifluoropropene, 2-chloro-3,3,3-trifluoropropene; I,2-dichloro-3,3,3-trifluoropropene; 1,1- dichloro-3,3-difluoro-l-propene; and 3 -chloro-3, 3 -difluoro- 1 -propene. These hydrochlorofluoropropene compounds may be cis or trans or a blend thereof.
[0059] In one embodiment, the hydrochlorofluoropropene has a boiling point above room temperature at ambient pressures. In one embodiment, the hydrochlorofluoropropene has a boiling point greater than 23, 25, 30, or even 35 °C.
[0060] In one embodiment, the coatable composition comprises at least 10, 20, 30 or even 40 wt % of the liquid solvent. In one embodiment, the coatable composition comprises at most 50, 60, 70, 80, 90, or even 99 wt % of the liquid solvent.
[0061] In one embodiment, the amorphous fluoropolymer content of the curable compositions is preferably as high as possible, for example, at concentrations from at least 50, 75, 80, 85, or even 90 % by weight; and at most 95, 98, 99, or even 99.5 % by weight based on the total weight of the curable composition.
[0062] In one embodiment, the hydrochlorofluoropropene substantially solubilizes the partially fluorinated amorphous polymer. In other words, 80, 100, 150, or even 200 grams of the partially fluorinated amorphous polymer dissolves in 100 mL of the hydrochlorofluoropropene.
[0063] The partially fluorinated amorphous polymers dissolved and/or dispersed in the liquid solvent are coatable. In one embodiment, the compositions have a viscosity at 25°C of at least 50, 100, 500, 1000, 2000, 4000, 6000 or even 10000 cP (centiPoise). In one embodiment, the compositions have a viscosity at 25°C of at most 2000, 4000, 6000, 8000, 10000, 15000, 20000, 50000, 100000, 200000, 500000, or even 1000000 cP. The low viscosities can enable the coating compositions to be dispensible.
[0064] Additional liquid solvents may be present in the curable fluoropolymer composition, typically as a result of carriers or impurities in the components. Ideally, these additional liquid solvents are kept to a minimum. In one embodiment, the liquid solvent consists essentially of the hydrochlorofluoropropene, meaning that the inert liquid present in the curable fluoropolymer composition comprises at least 90, 95, 98, 99, or even 99.9 wt % of the hydrochlorofluoropropene. In some embodiments, no additional liquid is present other than the hydrochlorofluoropropene. [0065] Advantageously, the hydrochlorofluoropropene is used as a liquid solvent to at least partially dissolve the partially fluoropolymer. Hydrochlorofluoropropene is unique because it is able to at least partially solubilize the partially fluorinated amorphous polymer and has a good environmental profile and is non-flammable making it especially useful.
[0066] In one embodiment, the hydrochlorofluoropropene and/or the curable fluoropolymer composition of the present disclosure has a low environmental impact. In this regard, the hydrochlorofluoropropene and/or the curable fluoropolymer composition of the present disclosure may have a global warming potential (GWP) of less than 10, 5, 2, or 1. As used herein, GWP is a relative measure of the global warming potential of a compound based on the structure of the compound. See paragraphs [0020]-[0022] of U.S. Publ. No. 2015/0083979 (Costello et al.) for discussion on how to determine the GWP.
[0067] In one embodiment, the hydrochlorofluoropropene and/or the curable fluoropolymer composition of the present disclosure have an atmospheric lifetime of less than 10 years, or even less than 5 years when tested as disclosed in paragraph [0060] of U.S. Publ. No. 2020/0002589 (Uamanna).
[0068] Non-flammability can be assessed by using standard methods such as ASTM D-3278-96 e-l“Standard Test Method for Flash Point of Uiquids by Small Scale Closed-Cup Apparatus”. In one embodiment, the hydrochlorofluoropropene and/or the curable fluoropolymer composition of the present disclosure is non-flammable based on closed-cup flashpoint testing following ASTM D-3278-96 e-1.
[0069] Method of making
[0070] The curable composition comprising the partially fluorinated amorphous polymer, the cure initiator, crosslinking agent, liquid solvent, and optional additives can be combined together, using techniques known in the art, and cured. In one embodiment, the cure initiator is a peroxide initiator, allowing the coatable composition to be thermally cured. In another embodiment, the cure initiator is a photoinitiator, allowing the coatable composition to be photochemically cured.
[0071] In one embodiment, the curable composition is at least partially cured using thermal radiation, whereby the curable composition is exposed to temperatures greater than 120, 140, 160, 180, 200, 220, or even 250°C; and less than the decomposition temperature of the fluoropolymer or its components (e.g., less than 300, or even 275°C), causing the peroxide cure initiator to activate, resulting in the crosslinking (or curing) of the composition. Typically, curing is performed in an oven.
[0072] In one embodiment, the curable composition is at least partially cured using actinic radiation. In one embodiment, the curable composition is exposed to wavelengths from at least 180, 200, 210, 220, 240, 260, or even 280 nm; and at most 700, 800, 1000, 1200, or even 1500 nm. In one embodiment, the curable composition is exposed to wavelengths from at least 180, 210, or even 220 nm; and at most 340, 360, 380, 400, 410, 450, or even 500 nm. In one embodiment, the curable composition is exposed to wavelengths from at least 400, 420, or even 450 nm; and at most 700, 750, or even 800 nm. In one embodiment, the curable composition is exposed to wavelengths from at least 800, 850, or even 900 nm; and at most 1000, 1200, or even 1500 nm.
[0073] Any light source, as long as part of the emitted light can be absorbed by the photo-initiator or photo-initiator system, may be employed as a radiation source, such as, a high or low pressure mercury lamp, a cold cathode tube, a black light, a light emitting diode, a laser, and a flash light. Of these, the preferred source is one exhibiting a relatively long wavelength UV-contribution having a dominant wavelength of 300-400 nm. UV radiation is generally classed as UV-A, UV-B, and UV-C as follows: UV-A: 400 nm to 320 nm; UV-B: 320 nm to 290 nm; and UV-C: 290 nm to 100 nm.
[0074] In one embodiment, the dosage of the actinic radiation is 10-1000 watts.
[0075] In one embodiment, the curable composition is coated onto a substrate and then exposed to either thermal radiation or actinic radiation. For example, the curable composition is coated onto a substrate using techniques known in the art including, for example, dip coating, spray coating, spin coating, blade or knife coating, bar coating, roll coating, and pour coating (i.e., pouring a liquid onto a surface and allowing the liquid to flow over the surface)). Substrates may include, metals (such as carbon steel, stainless steel, and aluminum), plastics (such as polyethylene, or polyethylene teraphthalate), or release liners, which are a temporary support comprising a backing layer coated with a release agent (such as a silicone, fluoropolymer, or polyutherane). The composite comprising the substrate and a layer of curable composition is then exposed to thermal or actinic radiation to at least partially cure the curable composition. In one embodiment, a thin coating of the curable composition is disposed on a substrate, for example a coating thickness of at least 10 nm or even 100 nm to at most 1 pm, 10 pm, or even 100 pm. In one embodiment, the thin coating is substantially crosslinked, meaning that when tested following the Gel Content Measurement described below, there is at least 65, 70, 80, or even 90% gelling.
[0076] In one embodiment, the coating compositions can be processed in a continuous fashion. In this type of processing, the coating composition is coated onto a web, and then transported to a curing station containing the radiation (thermal or electromagnetic) source. The cured fluoroelastomer composition can then be transported to a cutting station, whereby articles of desired shapes are cut from the web of fluoroelastomer. Such a process can enable faster processing of articles, due to the continuous nature of the processing. The low flammability and/or good environmental profde of the hydrofluoropropene enables the coating compositions to be continuously processed without the necessity of making equipment explosion proof.
[0077] In another embodiment, the coating composition is coated directly onto the article and cured in place. For example, if a gasket for a part (e.g., a head) is needed, the coating composition could be coated directly onto the part and then cured. Such a process would enable made-to-order parts and eliminates cutting and/or the need for a mold.
[0078] The articles of the present disclosure are shaped and can include gaskets, ring lip seals, washer seals, O-rings, grooved seals, etc. EXAMPLES
[0079] All materials are commercially available, for example from Sigma-Aldrich Chemical Company, Milwaukee, WI, USA, or known to those skilled in the art, unless otherwise stated or apparent.
[0080] The following abbreviations are used in this section: g=grams, m=meters, cm=centimeters, mm=millimeters, min=minutes, °C=degrees Celsius, UV=ultraviolet, mPa=milliPascal, s=seconds. Abbreviations for materials used in this section, as well as descriptions of the materials, are provided in Table 1
Table 1 [0081] Characterization Methods
[0082] Gel Content measurement
[0083] Samples were soaked into Acetone for 10 min. Then samples were rinsed 5 times by Acetone. Samples were dried in an oven under 80 °C for 10 min. Gel content % was calculated by:
Weight after drying
Gel contents % = - x 100
Initial weight
[0084] Viscosity measurement
[0085] Viscosities reported in Tables 3 and 4 were determined using a B type viscometer, available under the trade designation “Model BM” from TOKYO KEIKI INC., Tokyo, Japan, using either 30 or 60 rpm and a No. 4 rotor, at 23 °C. For Example 1 (EX-1) and Comparative Example 1 (CE-1), Fluoropolymer, Coagent, UV Initiator, and Solvent as indicated in Table 3 were weighed into glass jars. Jars were rotated until Fluoropolymer, Coagent and UV Initiator were dissolved into the solvent completely. Viscosity of the solutions was measured and is recorded in Table 3. The solutions were dispensed from a dispenser available under the trade designation “MODEL SHOT MINI 200SX” from Musashi Engineering, Inc., Tokyo, Japan using a 20 gauge (0.61 mm inner diameter) nozzle at room temperature onto substrates. Dispensed solutions were pre-dried according to conditions indicated in Table 3 and then cured by exposure to UV light from a H type bulb in a system available under the trade designation “MODEL DRS” from Heraeus Nobelight Americal LLC, Buford, GA. The UV energy output of the UV source is provided in Table 2, below. The samples were cured by 10 passes through the UV source at a line speed of 13.4 m/min. Samples were tested for gel content before and after UV curing. The results are presented in Table 3.
Table 2 UV energy output of UV source Table 3
[0086] For Example 2 (EX-2) and Comparative Example 2 (CE-2), Fluoropolymer, Coagent, Peroxide, and Solvent as indicated in Table 4 were weighed into glass jars. Jars were rotated until Fluoropolymer, Coagent and Peroxide were dissolved into the solvent completely. The viscosity of the solutions was measured. Viscosity results are presented in Table 4. The solutions were dispensed from a dispenser available under the trade designation “MODEL SHOT MINI 200SX” from Musashi Engineering, Inc. using a 20 gauge (0.61 mm inner diameter) nozzle at room temperature onto substrates. Dispensed solutions were pre-dried and heat cured according to conditions listed in Table 4. Samples were tested for gel content before and after UV curing. The results are presented in Table 4.
Table 4 Table 5
[0087] Foreseeable modifications and alterations of this invention will be apparent to those skilled in the art without departing from the scope and spirit of this invention. This invention should not be restricted to the embodiments that are set forth in this application for illustrative purposes. To the extent that there is any conflict or discrepancy between this specification as written and the disclosure in any document mentioned or incorporated by reference herein, this specification as written will prevail.