New fluoroelastomers are described, comprising monomeric units deriving from a bis-olefin having general formula: wherein: R1, R2, R3, R4, R5, R6, equal or different from each other, are H or alkyls C1-C5; Z is an alkylene or cycloalkylene radical C1-C18, linear or branched, optionally containing oxygen atoms, preferably at least partially fluorinated, or a (per)fluoro-polyoxyalkylene radical. Such products are endowed with improved processability, especially during calendering of the vulcanization mixture, along with superior mechanical and workability properties during extrusion and injection molding, with a very good mold release.

Fluoroelastomers comprising monomeric units deriving from a bis-olefin

1) Fluoroelastomers characterized by the presence of iodine or bromine atoms at the end of the polymeric chain in an amount equal to or lower than 1 iodine or bromine atom per polymeric chain, and by a bromine content in the chain ranging from 0.05 to 2% by weight referred to the total weight of the monomeric units. Said fluoroelastomers exhibit improved characteristics of processability, particularly as regards the utilization in injection molding processes and the detaching from the molds, as well as of stability to heat. 2) A process for preparing fluoroelastomers containing iodine or bromine atoms at the ends of the polymeric chain, in an amount equal to or lower than 1 iodine or bromine atom per polymeric chain, which process comprises polymerizing mixes of fluorinated monomers (VDF, TFE, HFP, FVE) in bulk in suspension, in aqueous emulsion, or in solution of organic solvents by means of radical starters, in the presence of compounds capable of providing T or Br ions in the polymerization medium and conditions.

Fluoroelastomers endowed with improved processability and process for preparing them

Porous hydrophilic membranes comprising a porous inert support on which an ionomer is deposited, said membranes being chara- cterized in that they have an ionic conductivity and a water permeability higher than 1 l/(h.m2.Atm).

Porous hydrophilic membranes

New fluoroelastomers are described, having iodine atoms in terminal position and monomeric units in the chain deriving from an iodinated olefin of formula: CHR=CH-Z-CH2CHR-I (I) wherein: R is -H or -CH3; Z is a (per)fluoroalkylene radical C1-C18, linear or branched, optionally containing one or more ether oxygen atoms, or a (per)fluoropolyoxyalkylene radical. These products, upon peroxide curing, require extremely short post-curing treatments (around 30-60 minutes at 180°- 230°C) and are characterized by compression set values lower than 25% (measured on O-rings at 200°C for 70 hours according to ASTM Standard D395 Method B).

Peroxide curable fluoroelastomers particularly suitable for manufacturing O-rings

A (per)fluoroelastomeric composition curable by peroxidic way comprising for 100 phr of (per)fluoroelastomer: - as filler, from 2 to 70 phr of carbon black having a surface area between 25 and 35 m2/g; - as crosslinking agent, from 0.5 to 10 phr of a bis-olefin having general formula (I) wherein: R1, R2, R3, R4, R5, R6, equal to or different from each other, are H or C1-C5 alkyls; Z is selected between a linear or branched C1-C18 alkylene or cycloalkylene radical, optionally containing oxygen atoms, preferably at least partially fluorinated, or a (per)fluoropolyoxyalkylene radical.

per)fluoroelastomeric compositions

CURABLE MIXES OF FLUOROELASTOMERSCONTAINING BROMINE OR IODINE AND OF ORGANIC PEROXIDES Abstract There are described mixes, which are curable by using radical intermediates, are based on fluoroelastomers containing bromine or iodine, exhibit, during curing, a low emission of toxic vapors of methyl bromide or iodide and are characterized in that they contain, as cross-linking agents, peroxides having the following formulas: (I) (II) wherein the substituents from R1 to R17 have the significan-ces defined in the specification.

Curable mixtures of fluoroelastomers containing bromine or iodine and of organic peroxides

A process for the di-ter-peroxide synthesis, wherein the condensation reaction between a tertiary hydroperoxide and a tertiary alcohol is carried out in the presence of an acid catalyst, constituted by a compound having a mono-sulphonated aromatic ring selected from the following formulae: wherein: R is an alkyl group having from 2 to 9 carbon atoms, preferably from 2 to 6; R′ and R″ are alkyl groups having a number of from 1 to 9 carbon atoms, preferably from 1 to 6.

Preparation of di-tertiary-peroxides

PROBLEM TO BE SOLVED: To produce a di-t-peroxide useful as a polymer vulcanizing agent, etc., using a catalyst effective for improving the yield and suppressing the formation of by-product by carrying out the condensation reaction of a t- hydroperoxide with a t-alcohol in the presence of a specific acid catalyst. SOLUTION: The objective compound (preferably dicumyl peroxide) is produced by the condensation reaction of (A) a t-hydroperoxide (preferably cumene hydroperoxide) with (B) a t-alcohol (preferably cumyl alcohol) in the presence of (C) an acid catalyst composed on a compound having a mono-sulfonated aromatic group and selected from the compounds of formula I and formula II (R is a 2-9C alkyl; R' and R" are each a 1-9C alkyl) (e.g. p-toluenesulfonic acid) preferably at 25-60°C for about 30-90 min. Preferably, the molar ratio of the component A to B is 0.9-1.2 and the amount of the component C is 10-40 wt.% based on the organic mixture used as the reactant. COPYRIGHT: (C)2000,JPO

Production of di-ter-peroxides

A process for the di-ter-peroxide synthesis, wherein the condensation reaction between a tertiary hydroperoxide and a tertiary alcohol is carried out in the presence of an acid catalyst, constituted by a compound having a mono-sulphonated aromatic ring selected from the following formulae:

Ezio Montessoro

Papers

Curable mixtures of fluoroelastomers containing bromine or iodine and of organic peroxides

Preparation of di-tertiary-peroxides

Production of di-ter-peroxides

Preparation of di-tert-peroxides