| 摘要 |
A new process for producing orthopedic structures is provided, which comprises impregnating a fabric carrier with a solution of a polymer and removing the solvent from the impregnated carrier, which process is characterized in that the fabric carrier is impregnated with a solution in an organic solvent of a prepolymer polyurethane having two isocyanate end groups which has been formed by the reaction of a bifunctional compound reactive with an isocyanate group with a molar excess of a diisocyanate, which solution contains a chain extender and optionally a catalyst for the chain-extending reaction and the impregnated carrier is warmed to remove the solvent and to prepare the final polymer.
<??>By the invention a new thermoplastic linear polyurethane is produced, which comprises recurring units of a prepolymeric diisocyanate, which are linked by radicals of a bifunctional chain-extender. The prepolymeric diisocyanate, which is used as a reactant for forming the linear polyurethane, has been formed by reacting a diol of the general formula
H-(-O-R1-@-)xY-R2-Z-(-@-R1-O)-yH
with a diisocyanate of the general formula OCN-R3-NCO, wherein R1 represents an alkylene radical having 4 to 6 carbon atoms, which is unsubstituted or may be substituted with lower alkyl groups, cycloalkyl groups, lower alkoxy groups, the number of substituents being 1 to 3, the radicals R1 being identical radicals or mixed radicals, R2 represents a lower alkylene radical having 2 to 6 carbon atoms. R3 represents the radical of an aromatic or aliphatic diisocyanate, and Y und Z standing for -O-, -NH-, or -COO-, x and y are 10 to 20.
<??>The process according to the invention enables to impregnate carrier materials for orthopedic structure in a one-step procedure by using highly concentrated solutions without reaching a high viscosity.
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