Silicone coating formulations and planographic printing plates made therewith
AssigneePresstek, Inc.
InventorsThomas E. Lewis, Michael T. Nowak
Life of this patent
Estimating the term…
Abstract
Two-component silicone formulations consisting of a high-molecular-weight silicone component and a low-molecular-weight silicone polymer. The components are combined in varying proportions with a cross-linking agent to produce compositions of varying viscosities and dispersibilities. The high-molecular-weight component is linear polysiloxane compound with a molecular weight of at least 300,000, and preferably 500,000 or higher. The low-molecular-weight component has a similar structure, with a molecular weight no greater than 70,000. Various substitutions are made to facilitate cross-linking among components. The formulations are well-suited to coating applications, and can advantageously be used as coatings for planographic plates.
Claims45
A recording medium capable of being imaged using ablative discharge, comprising a substrate having applied to at least one surface thereof a composition comprising a cured polymeric silicone matrix consisting essentially of the reaction product of:
- a. a first polysiloxane component having a molecular weight in excess of 300,000 and comprising substantially linear chains of substituted siloxane units, some of which units contain, as substitutents, a first reactive functional group that facilitates cross-linking, and which functional group is randomly interspersed in each first-component chain;
- b. a second polysiloxane component having a molecular weight no greater than 70,000 and comprising substantially linear chains of substituted siloxane units, each of which is capped by terminal siloxane units that each contain, as substituents, a second reactive functional group that facilitates cross-linking;
- and
- c. a cross-linking component having a molecular weight less than 5,000 and containing a plurality of a third reactive functional group differing from but reactive with the first and second functional groups;
- wherein
- d. the relative weight proportion of the first component to the second component is at least 10% and no more than 90%.
A recording medium capable of being imaged using ablative discharge, comprising a substrate having applied to at least one surface thereof a composition comprising a cured polymeric silicone matrix consisting essentially of the reaction product of:
- a. a first polysiloxane component having a molecular weight in excess of 300,000 and comprising substantially linear chains of substituted siloxane units, some of which units contain, as substituents, a first reactive functional group that facilitates cross-linking, and which functional group is randomly interspersed in each first-component chain;
- b. a second polysiloxane component having a molecular weight no greater than 70,000 and comprising substantially linear chains of substituted siloxane units, each of which is capped by terminal siloxane units that each contain, as substituents, a second reactive functional group that facilitates cross-linking;
- and
- c. a cross-linking component having a molecular weight less than 5,000 and containing:
- i. a plurality of a third reactive functional group differing from the first and second functional groups but reactive with the first functional group, and
- ii. a plurality of a fourth functional group differing from the first and second functional groups but reactive with the second functional group;
- wherein
- d. the relative weight proportion of the first component to the second component is at least 10% and no more than 90%.
Dependencies are inferred from the claim text.