Antimicrobial liquid preservative solutions and process for preparation

A liquid antimicrobial solution for use as a preservative composition comprising, on a 100 weight percent basis:

• (A) from about 20 to about 75 weight percent of a 5,5-disubstituted hydantoin which has in at least one of the 1 and 3 positions a methylol substituent, said methylol substituent being present in both said 1 and 3 positions in at least about 10 weight percent of the total weight of said methylol substituted 5,5-disubstituted hydantoin and wherein each of said 5,5 substituents is selected from the group consisting of phenyl and lower alkyl groups;
• (B) from about 20 to about 70 weight percent of a liquid aromatic alcohol having the formula:
• ##STR9## where R is selected from the group consisting of:
• ##STR10## (C) an antifungally effective amount of iodoalkynyl alkyl carbamate having the formula:
• ##STR11## where:
• R.sub.1 is an alkyl group containing no more than 20 carbon atoms, and R.sub.2 is an alkylene group containing from 1 through 4 carbon atoms;
• (D) less than 15 weight percent water and the weight ratio of said methylol substituted 5,5-disubstituted hydantoin to said carbamate is in the range of from about 60:1 to about 80:1.

A process for preparing a liquid antimicrobial solution comprising a liquid aromatic alcohol that contains (i) a methylol substituted 5,5-disubstituted hydantoin which comprises at least 10 weight percent, on a 100 weight percent total methylol substituted 5,5-disubstituted hydantoin basis, 1,3-dimethylol-5,5-disubstituted hydantoin and wherein each of said 5,5 substituents is selected from the group consisting of phenyl and lower alkyl groups, and (ii) an iodoalkynyl alkyl carbamate having the formula:

• ##STR12## where:
• R.sub.1 is an alkyl group containing no more than 20 carbon atoms, and R.sub.2 is an alkylene group containing from 1 through 4 carbon atoms, said process comprising the steps of:
• (a) dissolving a formaldehyde selected from the group consisting of paraformaldehyde and formalin in at least one liquid aromatic alcohol having the formula:
• ##STR13## where R is selected from the group consisting of:
• ##STR14## to provide a liquid medium;
• (b) heating said liquid medium to a temperature of no more than about 50.degree. C. to provide a heated liquid medium;
• (c) admixing into said heated liquid medium said 5,5-disubstituted hydantoin to provide a reaction mixture, the amount of said 5,5-disubstituted hydantoin so admixed being sufficient to produce in said reaction mixture an initial calculated mole ratio of formaldehyde to said 5,5-disubstituted hydantoin of from about 1:1 to about 3:1;
• (d) further heating under autogenous conditions said reaction mixture to a temperature of no more than 110.degree. C. and maintaining said temperature until said 1,3-dimethylol 5,5-disubstituted hydantoin is produced;
• (e) cooling said resulting reaction mixture to a temperature range between from about 25.degree. C. to no more than about 40.degree. C.;
• and
• (f) dissolving in said so-cooled resulting reaction mixture said iodoalkynyl alkyl carbamate in an amount being sufficient to produce on a resulting total antimicrobial solution basis a weight ratio of said 1,3-dimethylol 5,5-disubstituted hydantoin to said iodoalkynyl alkyl carbamate in the range of from about 60:1 to about 80:1.