Process for the manufacture of collagen membranes used for hemostasis, the dressing of wounds and for implants

Claim 1

A process for the manufacture of collagen membranes having an integral cohesion of fine fibers corresponding to that of a collagen raw material, and having a dry weight of approximately 25% by weight consisting essentially of, the step of: (a) mechanically freeing fatty residues from a collagen raw material and washing the raw material; (b) treating the collagen raw material with a strong alkali unit the amide nitrogen content is less than or equal to 0.35 mmol/g collagen; (c) treating the alkali-treated raw material with a strong acid at a pH value of less than or equal to 1 and subsequently washing the treated materials with water to obtain a dry weight of between 10 and 14% by weight, in which process the pH value increases to between 2.5 and 3.5; (d) shrinking the washed material by adding thereto an inorganic saline solution; (e) swelling the shrunken material by squeezing off the inorganic saline solution and washing the shrunken material with water to reach a dry weight of between 40 and 50% by weight; (f) repeating steps (d) and (e) at least twice; (g) removing water from the resulting matrix product of step (f) by the addition of a solvent; and (h) drying the matrix in a stretched form, to obtain a membrane wherein the integral cohesion of the fibers of the membrane's matrix correspond to that of a collagen raw material and having a dry weight of approximately 25% by weight.