Grafting of silane on thermoplastics or elastomers for purposes of cross linking
AssigneeKabel-und Metallwerke Gutehoffnungshutte Aktiengesellschaft
InventorsFritz Glander, Hermann U. Voigt
Life of this patent
Estimating the term…
Abstract
Granulated polyethylene is agitated and mixed with a solution of silane with peroxide, activators and anti-oxidants and at a temperature between 80.degree. to 100.degree. C. to obtain diffusion of these additives into the polyethylene particles which is followed by grafting through extrusion or radiation which in turn is followed by exposure to and/or development of water to obtain cross-linking. A catalyst is added preferably by mixing polyethylene powder with the catalyst and adding that powder to the powder with diffused silane, after that diffusion has been completed.
Claims35
In a method for cross-linking thermoplastic or elastomeric material wherein cross-linking is preceded by grafting of silane and is carried out in the presence of moistures, the combination of steps comprising:
- providing the thermoplastic or elastomeric material as dry, fluid powder;
- agitating the powder to obtain fluidization thereof and raising the temperature by operation of the agitating;
- adding a silane compound to the material prior to completion of the agitation, the silane compound being of the variety that permits grafting on the molecules of said powder;
- providing for a temperature below the crystallite melting range, between 80.degree. C. and 100.degree. C., so that the silane or silane compound as agitated together with the said material fluid is caused to diffuse into the fluid particles without grafting;
- and
- providing for grafting of the silane or silane compound molecules to the molecules of the thermoplastic or elastomeric material.
In a method for cross-linking thermoplastic or elastomeric material, wherein cross-linking is preceded by grafting of silane and is carried out in the presence of moistures, the combination of steps comprising:
- providing the thermoplastic or elastomeric material as a dry, fluid powder;
- agitating the powder to obtain fluidization thereof and raising the temperature by operation of the agitation;
- adding a silane compound to the material prior to completion of the agitation, the silane compound being of a variety that permits grafting on the molecules of said powder;
- providing for a temperature below the crystallite's melting range, so that the silane or silane compound, as agitated, together with the said material fluid is caused to diffuse into the fluid particles without grafting;
- and
- subjecting the material to a high energy radiation for grafting the silane or silane compound molecules upon the molecules of the thermoplastic or elastomeric material.
In a method for cross-linking thermoplastic or elastomeric material, wherein cross-linking is preceded by grafting of silane and is carried out in the presence of moistures, the combination of steps comprising:
- providing the thermoplastic or elastomeric material as a dry, fluid powder;
- agitating the powder to obtain fluidization thereof and raising the temperature by operation of the agitation;
- adding a silane compound when the temperature of the powder has risen to 60.degree. C. to 100.degree. C. prior to completion of the agitation, the silane compound being of a variety that permits grafting on the molecules of said powder;
- providing for a temperature below the crystallite's melting range, so that the silane or silane compound, as agitated, together with the said material fluid is caused to diffuse into the fluid particles without grafting;
- and
- providing for grafting of the silane or silane compound molecules on the molecules of the thermoplastic or elastomeric material.
Dependencies are inferred from the claim text.