Yeda Research and Develpment & Co. Ltd

Makhteshim Chemical Works Ltd.

Other

David Vofsi

Stephen L Daren

Shymon Reich

Yael Allingham

Moshe Levy

Martin M Halmann

Israel Cabasso

Joseph Jagur-Grodzinski

Ella Cohen

Gideon Levin

Michael Martan

Meir Asscher

David Aelony

Saul A Gassner

Jonathan Freddy Cohen

Saul Yanai

Shaul Yanai

Israel Tchoukran

Joaquin Mayoral

Aurelia Finkels

The invention relates to the stabilization of monobromostyrene of dibromostyrene and of mixtures of these. The stabilization is effected by means of hydroxy-benzene derivatives, where the benzene ring contains at least two substituents, one of these being a hydroxy group. The process is advantageously carried out by heating the styrene material with an excess of the inhibitor, distilling the monomer and adding an additional quantity of the inhibitor. The distilled monomer is preferably dried prior to the addition of the further quantity of inhibitor.

Stabilization of bromostyrenes

There is provided a scaife for the polishing of gemstones wherein the abrasive material is embedded in a matrix of a material maintained in the solid state, which material has a high enthalpy of phase transition from solid to liquid. Suitable materials are frozen water, frozen water/organic liquid mixtures such as water/alkanol mixtures and suitable metals or metal alloys. There is also provided a process for the polishing of gemstones which comprises a process for the polishing of gemstones which comprises establishing a layer of abrasive embedded in a suitable solid matrix in or on the surface of a rotatory plate and polishing said gemstones, overheating being prevented by the high enthalpy of solid/liquid transition of the said matrix.

Novel lap for the polishing of gem stones

The invention relates to an improved process for the production of crystalline tribromostyrene. The process involves removal of hydrogen bromide in a two phase system with the aid of phase transfer catalysts. One of the phases used is an aqueous one containing an alkali metal hydroxide whereas the second comprises .beta.-bromoethyltribromobenzene in an alcohol as solvent.

Production of crystalline tribromostyrene

There is provided a scaife for the polishing of gemstones wherein the abrasive material is embedded in a matrix of a material maintained in the solid state, which material has a high enthalpy of phase transition from solid to liquid. Suitable materials are frozen water, frozen water/organic liquid mixtures such as water/alkanol mixtures and suitable metals or metal alloys. There is also provided a process for the polishing of gemstones which comprises establishing a layer of abrasive embedded in a suitable solid matrix in or on the surface of a rotatory plate and polishing the gemstones, overheating being prevented by the high enthalpy of solid/liquid transition of the said matrix.

Lap for the polishing of gemstones

The invention relates to a process for the production of a contact lens, which comprises coating a tool made of an inert material, having a curvature corresponding to that of one of the optical surfaces of the lens to be produced, with a layer of solid polymer, and machining the outer surface of said polymer to the desired curvature of the second surface of said lens while supported by said tool, and to a tool for carrying out such process.

Production of contact lenses

Phosphonoacetals of the formula ##STR1## wherein R.sup.1 is an alkyl group having from 1-3 carbon atoms;

Plant growth regulant phosphonoacetals

The present invention relates to antifouling paints for marine use comprising a conventional paint base containing as active ingredient a compound of the formula ##STR1## wherein X is selected from chlorine and bromine,

Antifouling paints for marine use

The present invention relates to modified polyvinylchloride, wherein part of the chlorine atoms are replaced by groups of the formula --S--CH.sub.2 --CH.sub.2 --R--(CH.sub.2 --CH.sub.2 --R).sub.n --Alk, wherein R is selected from oxygen, sulfur and --NH--, where R may also designate a bond, where Alk designates an alkyl group of up to 14 carbon atoms, and where n is zero or an integer of from 1 to 100, and to a process for the production of such modified polyvinylchloride polymers which comprises reacting an aqueous emulsion or suspension of polyvinylchloride in the presence of a solvent adapted to cause swelling of the PVC particles with a compound of the formula Alk--(CH.sub.2 --CH.sub.2 --R).sub.n --R--CH.sub.2 --CH.sub.2 --SH, wherein Alk, R and n are as defined above.

Modified polyvinylchloride

The present invention relates to the production of ring-halogenated styrene monomers of high purity. These are of value in the production of polymers which possess flame retardance. The process of the invention comprises reacting heterogenously ring halogenated beta-bromoethyl benzene with a strong aqueous alkali base in the presence of a quaternary phase transfer catalyst until substantially all the bromoethyl benzene has undergone reaction, separating the phases, washing and neutralizing the organic phase and recovering the ring-halogenated styrene monomer, which is the desired product.

Process for preparing ring halogenated styrenes

Polyhydroxylated O,O-dialkyl phosphonoacetals having the formula ##STR1## wherein R is an alkyl group having from 1-3 carbon atoms;

Phosphorus containing polyols

The present invention relates to novel 2,5-dihalophenyl-.beta.-substituted sulfone compounds of the formula ##STR1## wherein Q is selected from ##STR2## and wherein: X designates chlorine or bromine,

Novel 2,5-dihalophenyl-.beta.-substituted sulfone fungicides

According to the invention there is provided a polymeric composition of matter substantially transparent to solar radiation and constituting an effective barrier to infra-red radiation, especially in the region of about 7.mu. to 15.mu., comprising polyethylene or a copolymer of mainly polyethylene, containing an effective quantity of a phosphate, having a preferred range of content of phosphate of from 1 to 20 percent by weight. There is also provided a tunnel-shaped or similar structure for the cultivation of agricultural crops comprising a cover of sheeting made of such polymer.

Polyethylene sheets and films

Compounds are disclosed of the formula ##STR1## wherein R designates hydrogen or an alkyl group of 1 to 6 carbon atoms, inclusive;

Novel halogenated organic compounds, process for the production of same,

Polymer alloys of a phosphorus-containing polymer component having the formula: ##STR1## WHEREIN X is hydrogen or halo; Z and Z' are each hydrogen or a phosphonate group PO(OR)(OR.sub.1) in which R and R.sub.1 are each alkyl or aryl, but are not both hydrogen, Y is a bivalent radical from an ethylenically unsaturated monomer copolymerized with styrene, and m, m', n, n' and p are zero or integers as specified; and a second polymer component compatible with and alloyed with the phosphorus-containing polymer component, the second component being a cellulose ester, or a polystyrene or unsaturated polyester resin. Polymer alloys thus constituted are particularly useful as fire-retardant and flame-resistant materials, and as membranes useful in the separation of solvents exhibiting differential permeabilities therethrough.

Polymer alloys of phosphonylated polystyrene or polyphenylene oxide with

The present disclosure relates to improved polymeric materials and to a process for preparing same, which comprises blending suitable polymers into novel polymeric alloys. The disclosure further relates to novel fire-retarding and flame-resistant materials comprising such polymeric alloys and to novel membrane materials and membranes, adapted to provide novel processes of separation based on membrane technology. The novel polymeric alloys comprise commercially available polymers, blended with novel polymeric phosphonates of the general formula: ##STR1## WHEREIN: M, M', N, N' ARE ZERO OR ANY INTEGER, P IS AN INTEGER HIGHER THAN 10

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Rehovot, Israel

David Vofsi