Fluoroelastomer compositions

Abstract

Fluoropolymers comprising a fluoroelastomer matrix incorporating therein particles of a semicrystalline fluoropolymer formed of tetrafluoroethylene (TFE) homopolymers or copolymers, wherein the average particle sizes of the semicrystalline fluoropolymer latex range from 10 to 100 nm.

1 . Fluoropolymers comprising a fluoroelastomer matrix incorporating therein particles of a semicrystalline fluoropolymer latex formed by tetrafluoroethylene (TFE) homopolymers, or TFE copolymers with one or more monomers containing at least one unsaturation of ethylene type in amounts ranging from 0.01% to 10% by moles, preferably from 0.05% to 5% by moles, wherein the average particle sizes of the semicrystalline fluoropolymer latex range from 10 to 100 nm for at least 60% by weight of the semicrystalline fluoropolymer.  
     
     
         2 . Fluoropolymers according to  claim 1  wherein the latex particle sizes of the semicrystalline fluoropolymer range from 10 to 60 nm.  
     
     
         3 . Fluoropolymers according to claims  1 - 2  obtainable by mixing the semicrystalline fluoropolymer latex with the fluoroelastomer latex and subsequent coagulation.  
     
     
         4 . Fluoropolymers according to claimns  1 - 2  obtainable by polymerizing in a first step the semicrystalline fluoropolymer and in a second step the fluoroelastomer.  
     
     
         5 . Fluoropolymers according to claims  1 - 4  wherein the semicrystalline fluoropolymer amount inside the fluoroelastomer matrix is in the range 2%-40% by weight on the total of the polymeric mixture.  
     
     
         6 . Fluoropolymers according to  claim 5  wherein the semicrystalline fluoropolymer amount inside the fluoroelastomer matrix is in the range 5-30% by weight on the total of the polymeric mixture.  
     
     
         7 . Fluoropolymers according to claims  1 - 6  wherein the semicrystalline polymer is based on PTFE modified with comonomers with ethylene unsaturation both of hydrogenated and fluorinated type.  
     
     
         8 . Fluoropolymers according to  claim 7  wherein the hydrogenated comonomers are selected from ethylene, propylene, methylmethacrylate, methacrylic acid, butylacrylate, hydroxyethylhexylacrylate, styrene.  
     
     
         9 . Fluoropolymers according to  claim 7  wherein the fluorinated comonomers are selected from: 
 perfluoroolefins C 3 -C 8 , such as hexafluoropropene (HFP), hexafluoroisobutene;  
 hydrogenated fluorolefins C 2 -C 8 , such as vinyl fluoride (VF), vinylidene fluoride (VDF), trifluoroethylene, perfluoroalkylethylene CH 2 ═CH—R f , wherein R f  is a perfluoroalkyl C 1 -C 6 ;  
 chloro- and/or bromo- and/or iodo-fluoroolefins C 2 -C 8 , such as chlorotrifluoroethylene (CTFE);  
 (per)fluoroalkylvinylethers (PAVE) CF 2 ═CFOR f , wherein R f  is a (per)fluoroalkyl C 1 -C 6 , for example CF 3 , C 2 F 5 , C 3 F 7 ;  
 (per)fluoro-oxyalkyvinylethers CF 2 ═CFOX, wherein X is: 
 an alkyl C 1 -C 12 , or an oxyalkyl C 1 -C 12 , or a (per)fluoro-oxyalkyl C 1 -C 12  having one or more ether groups, for example perfluoro-2-propoxy-propyl; fluorodioxoles.  
 
 
     
     
         10 . Fluoropolymers according to claims  7 - 9  wherein the preferred comonomers are perfluoromethyl-, ethyl-, propylvinylether and perfluorodioxoles.  
     
     
         11 . Fluoropolymers according to claims  1 - 10  wherein the fluoroelastomer is selected from the following classes: 
 (1) vinylidene fluoride (VDF)-based copolymers, wherein VDF is copolymerized with at least one comonomer selected from the following ones: 
 perfluoroolefins C 2 -C 8 , such as tetrafluoroethylene (TFE), hexafluoropropene (HFP); chloro- and/or bromo- and/or iodo-fluoroolefins C 2 -C 8 , such as chlorotrifluoroethylene (CTFE) and bromotrifluoroethylene; (per)fluoroalkylvinylethers (PAVE) CF 2 ═CFOR f , wherein R f  is a (per)-fluoroalkyl C 1 -C 6 , for example trifluoromethyl, bromodifluoromethyl, pentafluoropropyl; perfluoro-oxyalkylvinylethers CF 2 ═CFOX, wherein X is a perfluoro-oxyalkyl C 1 -C 12  having one or more ether groups, for example perfluoro-2-propoxy-propyl; non fluorinated olefins (Ol) C 2 -C 8 , for example ethylene and propylene;  
 
 (2) tetrafluoroethylene (TFE)-based copolymers, wherein TFE is copolymerized with at least one comonomer selected from the following: 
 (per)fluoroalkylvinylethers (PAVE) CF 2 ═CFOR f , wherein R f  is as above defined; perfluoro-oxyalkylvinylethers CF 2 ═CFOX, wherein X is as above defined; fluoroolefins C 2 -C 8  containing hydrogen and/or chlorine and/or bromine and/or iodine atoms; non fluorinated olefins (Ol) C 2 -C 8 ; perfluorovinylethers containing hydrocyanic groups.  
 
 
     
     
         12 . Fluoropolymers according to  claim 11  wherein the preferred fluoroelastomer is selected from the following compositions expressed by moles: 
 (a) vinylidene fluoride (VDF) 45-85%, hexafluoropropene (HFP) 15-45%, tetrafluoroethylene (TFE) 0-30%;  
 (b) vinylidene fluoride (VDF) 50-80%, perfluoroalkylvinylether (PAVE) 5-50%, tetrafluoroethylene (TFE) 0-20%;  
 (c) vinylidene fluoride (VDF) 20-30%, non fluorinated olefins (Ol) C 2 -C 8  10-30%, hexafluoropropene (HFP) and/or perfluoroalkylvinylether (PAVE) 18-27%, tetrafluoroethylene (TFE) 10-30%;  
 (d) tetrafluoroethylene (TFE) 50-80%, perfluoroalkylvinylether (PAVE) 20-50%;  
 (e) tetrafluoroethylene (TFE) 45-65%, non fluorinated olefins (Ol) C 2 -C 8  20-55%, vinylidene fluoride 0-30%;  
 (f) tetrafluoroethylene (TFE) 32-60% by moles, non fluorinated olefins (Ol) C 2 -C 8  10-40%, perfluoroalkylvinylether (PAVE) 20-40%;  
 (g) tetrafluoroethylene (TFE) 33-75%, perfluoroalkylvinylether (PAVE) 15-45%, vinylidene fluoride (VDF) 5-30%.  
 
     
     
         13 . Fluoropolymers according to claims  1 - 12  wherein the fluoroelastomer comprises also monomer units deriving from a bis-olefin having general formula:  
       
         
           
           
               
               
           
         
       
       wherein: 
 R 1 , R 2 , R 3 , R 4  , R 5 , R 6 , equal to or different from each other, are H or alkyls C 1 -C 5 ;  
 Z is a linear or branched, alkylene or cycloalkylene C 1 -C 18  radical, optionally containing oxygen atoms, preferably at least partially fluorinated, or a (per)fluoropolyoxyalkylene radical.  
 
     
     
         14 . Fluoropolymers according to  claim 13  wherein the unit amount in the chain deriving from the bis-olefin is in the range 0.01-1.0% by moles of the other monomer units forming the fluoroelastomer base structure.  
     
     
         15 . Fluoropolymers according to claims  1 - 14  wherein the fluoroelastomers are cured by peroxidic route.  
     
     
         16 . Fluoropolymers according to claims  1 - 14  wherein the fluoroelastomers when they contain cyano groups are cured by tin organic compounds and/or di-aromatic aminic compounds.  
     
     
         17 . Fluoropolymers according to  claim 16  wherein the fluoroelastomers are cured by tin organic compounds and/or di-aromatic aminic compounds and optionally by peroxidic route if in the polymeric chair iodine and/or bromine atoms are present.  
     
     
         18 . Use of fluoropolymers according to claims  1 - 17  for the preparation of sealing manufactured articles.