US RE31,193 EGranted

Thermosetting heat bondable lacquer

AssigneeSchweizerische Isola-Werke

InventorsPeter Heim, Karl Borer, Werner Alleman

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Abstract

The thermosetting heat bondable lacquer comprises a solution of a thermosetting mixture of various resins in a solvent or mixture of solvents which boils at a temperature in the range of 50.degree. to 230.degree. C., preferably 130.degree. to 210.degree. C. The thermosetting mixture consists of a polyhydantoin resin, a polyhydroxy polyether or phenoxy resin and a polyurethane resin, each of which must have a pre-determined structure and a pre-determined specific viscosity. The composition of the thermosetting mixture must be within the hatched area in FIG. 1. The thermosetting heat bondable lacquer can be obtained by mixing solutions of the three resin components and can contain auxiliaries and additives and/or catalysts. If the solvent or mixture of solvents is removed from the heat bondable lacquer, e.g. by drying a thin coating produced therefrom or by precipitation with a non-solvent for the resin components, a mixture which is viscoelastic at room temperature and homogeneous is left, which mixture can be first molten and then cured by supplying heat. The heat bondable lacquer can be used in the production of baking lacquer wires, which serve for the manufacture of electromagnetic coils which can be subjected to high mechanical and thermal stresses, but it can also be applied to other carriers or by converted into heat bondable adhesive powders by precipitation in a non-solvent.

Claims17

Dependent claims

Thermosetting heat bondable lacquer which comprises a solution of a thermosetting mixture in a liquid selected from the group consisting of solvents boiling at a temperature in the range of 50.degree. to 230.degree. C. and mixtures of such solvents, said thermosetting mixture consisting of--based on the resin solids--

(a) 20 to 80% by weight of polyhydantoin resin of linear, branched or mixed linear and branched structure and having the formula:
##STR4## wherein the R's are the same or different and are hydrogen or alkyl radicals containing from 1 to 4 carbon atoms and the X's are the same or different and are selected from the group consisting of aliphatic, cycloaliphatic, heterocyclic and aromatic linking groups and combinations thereof, and n is a positive number having a value corresponding to the specific viscosity, a one percent solution of the resin in cresol DAB V having a specific viscosity between 0.2 and 1.5 at 20.degree. C.,
(b) 5 to 65% by weight of polyhydroxy polyether or phenoxy resin of linear, branched or mixed linear and branched structure and having the formula:
##STR5## wherein Y is a bivalent linking group selected from the group consisting of [bivalent] aliphatic, cycloaliphatic, heterocyclic and aromatic groups and combinations thereof, m is a positive number having a value corresponding to the specific viscosity, p is a positive number having an average value of 1 to 30 and q is a positive number with a value corresponding to the specific viscosity, a one percent solution of the resin in cresol DAB V having a specific viscosity between 0.2 and 1.5 at 20.degree. C., and
(c) 3 to 40% by weight of polyurethane resin of linear, branched or mixed linear and branched structure, at least 4% by weight of the resin consisting of the urethane grouping having the formula:
##STR6## and a one percent solution of the resin in cresol DAB V having a specific viscosity between 0.1 and 1.0 at 20.degree. C. the composition of said heat bondable lacquer falling within only the hatched area of FIG. 1 .

3 more elements

Process for the preparation of a heat bondable lacquer which comprises the steps of mixing a solution of (a) 20 to 80% by weight of polyhydantoin resin of linear, branched or mixed linear and branched structure and having the formula:

##STR7## wherein [The] the R's are the same or different and are hydrogen or alkyl radicals containing from 1 to 4 carbon atoms and the X's are the same or different and are selected from the group consisting of aliphatic, cycloaliphatic, heterocyclic and aromatic linking groups and combinations thereof, and n is a positive number having a value corresponding to the specific viscosity, a one percent solution of the resin in cresol DAB V having a specific viscosity between 0.2 and 1.5 at 20.degree. C., in a first solvent , a solution of (b) 5 to 65% by weight of polyhydroxy polyether or phenoxy resin of linear, branched or mixed linear and branched structure and having the formula:
##STR8## wherein Y is a bivalent linking group selected from the group consisting of aliphatic, cycloaliphatic, heterocyclic and aromatic groups and combinations thereof, m is a positive number having a value corresponding to the specific viscosity, p is a positive number having an average value of 1 to 30 and q is a positive number with a value corresponding to the specific viscosity, a one percent solution of the resin in cresol DAB V having a specific viscosity between 0.2 and 1.5 at 20.degree. C., in a second solvent mixture of solvents, preferably in a phenolic solvent, benzyl alcohol, N-methylpyrrolidone, dimethylformamide, 2-methoxyethyl acetate or 2-ethoxyethyl acetate or mixtures thereof, optionally with the addition of hydrocarbons which are preferably aromatic, such as xylene, or mixtures thereof, and a solution of (c) 3 to 40% by weight of polyurethane resin of linear, branched or mixed linear and branched structure, at least 4% by weight of the resin consisting of the urethane grouping having the formula:
##STR9## a one percent solution of the resin in cresol DAB V having a specific viscosity between 0.1 and 1.0 at 20.degree. C., in a third solvent, the weight percentages being based on the weight of the total resin solids and the resin composition of said heat bondable lacquer falling only within the hatched area of FIG. 1 .

Dependencies are inferred from the claim text.