Treating reinforcing fibers with carbodiimide aqueous dispersion

DETAILED DESCRIPTION OF THE INVENTION The present invention is hereinafter described in detail.
The carbodiimide compound, which is the main component of the present aqueous surface-treating agent for surface treatment of reinforcing material, can be any carbodiimide compound as long as it can be dispersed in an aqueous solvent by the use of a dispersing agent.
It includes, for example, an aromatic or aliphatic carbodiimide compound represented by the following general formula R.
sub.
2 --NCN--(R.
sub.
1 --NCN).
sub.
n --R.
sub.
2 (wherein R.
sub.
1 is a residue of a diisocyanate compound selected from the group consisting of m- or p-tetramethylxylylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, isophorone diisocyanate, 4,4'-diphenylmethane diisocyanate, and 2,4- or 2,6-tolylene diisocyanate; R.
sub.
2 is a residue of a monoisocyanate compound selected from the group consisting of cyclohexyl isocyanate, phenyl isocyanate, and butyl isocyanate; and n is an integer of 2 to 30).
The dispersing agent used for dispersing the carbodiimide compound in an aqueous solvent to obtain the present aqueous surface-treating agent, can be an emulsifier or the like.
With respect to the n (average polymerization degree) of the above formula, when n is less than 2, the number of carbodiimide groups is insufficient and no satisfactory surface-treating agent can be obtained.
When n is more than 30, there occurs solidification or gelling of reaction product during the synthesis of carbodiimide, which is undesirable.
The carbodiimide compound as main component of the present aqueous surface-treating agent for reinforcing material may be a water-soluble or self-emulsifiable type.
Such a carbodiimide compound includes, for example, a carbodiimide compound in which a hydrophilic segment has been introduced at the terminals, represented by the following general formula Z--OOC--NH--(R.
sub.
3 --NCN).
sub.
n --R.
sub.
3 --NH--COO--Z (wherein R.
sub.
3 is a residue of a diisocyanate compound selected from the group consisting of m- or p-tetramethylxylylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, and isophorone diisocyanate; Z is a hydrophilic segment; and n is an integer of 2 to 30)