Tanning agent formulation for manufacture of semifinished leather products

Abstract

A tanning agent formulation obtained by reacting 1 mole of an aliphatic ω,ω'-dialdehyde having 2-8 carbon atoms in the form of an aqueous solution of about 3-60% strength with about 0.2-4 moles of a hydroxy compound of the formula R.sub.1 --O--[(C.sub.2 H.sub.4 O).sub.x --(C.sub.3 H.sub.6 O).sub.y --C 4 H 8 O) z] n --H whereby n is an integer from 0 to 10, x+y+z is an integer from 1 to 20, wherein the alkoxy groups may be arranged in any order, and R 1 is H, C 1 -C 12 alkyl, or C 1 C 12 alkyl having one or more hydroxyl groups, wherein n is not 0 for R 1 ═H is disclosed. Pelts pretanned with the formulation have improved mold resistance and are free of tanning metal salts and formaldehyde.

What is claimed is: 
     
       1. A process for manufacturing a semifinished leather product, which comprises the steps of pickling a pelt and pretanning said pickled pelt with a tanning agent formulation obtained by reacting 1 mole of an aliphatic ω,ω'-.[.dialedehyde.]. .Iadd.dialdehyde .Iaddend.having 2-8 carbon atoms in the form of an .Iadd.about 3-60% by weight .Iaddend.aqueous solution .[.of about 3-60% strength.]. with about 0.2-4 moles of a hydroxy compound .[.of.]. .Iadd.selected from the group consisting of glycerol, a saccharide and a compound having .Iaddend.the formula I   .[.R.sub.1 --[(C.sub.2 H.sub.4 O)x-(C.sub.3 H.sub.6 O)y-(C.sub.4 H.sub.8 O)z]n-H                                                   (I).].       .Iadd.R.sub.1 --O--[(C.sub.2 H.sub.4 O).sub.x --(C.sub.3 H.sub.6 O).sub.y --(C.sub.4 H.sub.8 O).sub.z ].sub.n --H                   (I)     .Iaddend. .[.whereby.]. .Iadd.wherein.Iaddend.   n is an integer from .[.0.]. .Iadd.1 .Iaddend.to 10,   x+y+z is an integer from 1 to 20, wherein the alkoxy groups .[.may be.]. .Iadd.are .Iaddend.arranged in any order, and   R 1  is H, C 1  -C 12  alkyl, or C 1  -C 12  alkyl having one or more hydroxyl groups.[.,.]..Iadd...Iaddend.   wherein n is not O for R 1  ═H..].   
     
     
       2. The process of claim 1 wherein said tanning agent is produced in a reaction medium having a pH from about .Badd.2 to 5. 
     
     
       3. The process of claim 2 wherein said tanning agent is produced in a reaction medium having a pH from 3.5 to 4.5. 
     
     
       4. The process of claim 1 wherein the amount of said ω, ω'-dialdehyde present in the tanning agent formulation is about 0.2-1.0%, based on 100% .[.strength.]. dialdehyde and based on pelt weight. 
     
     
       5. The process of claim .[.1.]. .Iadd.4 .Iaddend.wherein the amount of said ω, ω'-dialdehyde present in the tanning agent formulation is 0.3-0.6%. 
     
     
       6. The process of claim 1 wherein said ω, ω'-dialdehyde is glutardialdehyde, succindialdehyde or adipindialdehyde. 
     
     
       7. The process of claim 1 wherein said hydroxy compound is an alkylglycol, alkylpolyglycol, .[.aliphatic alcohol,.]. glycerol or .[.saccaride.]. .Iadd.saccharide..Iaddend. 
     
     
       8. The process of claim 1 wherein said hydroxy compound is an alkoxyalcohol. .[.9. A process for manufacturing a semifinished leather product, which comprises the steps of pickling a pelt and pretanning said pickled pelt with a tanning agent formulation as claimed in claim 1..]. 
     
     
            A semifinished leather product produced by the process as claimed in 
     
     
        claim 1. 11. The process of claim 1 wherein the tanning agent consists 
     
     
        essentially of the recited reaction product. 12. A semifinished leather product produced by the process as claimed in claim 11.