Antimicrobial preservative system and method comprising a formaldehyde substituted hydantoin
First Claim
1. A cold stable antimicrobial preservative system in substantially anhydrous liquid form which is dissolvable in an antimicrobially effective amount in a medium capable of supporting microbial growth comprising:
- (a) as an active preservative, a condensation product of formaldehyde and a 5,5-disubstituted hydantoin wherein each such substituent group on the hydantoin ring is independently selected from the group consisting of phenyl and lower alkyl containing 1 to about 6 carbon atoms, said condensation product having a methylol functional group attached to one or both nitrogen atoms on the hydantoin ring;
(b) a substantially anhydrous, water-miscible solvent selected from the group consisting of polyhydroxy alcohols having about 3 to about 6 carbon atoms per molecule, alkylene carbonates having about 2 to about 3 carbon atoms in the alkylene radical thereof per molecule, and mixtures thereof; and
(c) sufficient alkalizing agent to provide a pH between about 6 and about 9 when one part by weight of said liquid preservative system is diluted with about 9 to about 19 parts by weight of deionized water.
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Abstract
A method of preparing an antimicrobial preservative system in a substantially anhydrous liquid form is disclosed. The antimicrobial preservative system inhibits or retards microbial growth when an effective antimicrobial amount is subsequently added to a medium capable of supporting undesirable microbial growth. More particularly, the preservative system comprises a condensation product of a 5,5-disubstituted hydantoin and formaldehyde prepared in the presence of a substantially anhydrous, water-miscible, solvent and an alkalizing agent. Also disclosed is a cold-stable, substantially anhydrous liquid preservative system comprising 1,3-dimethylol-5,5-dimethylhydantoin alone or in combination with an effective antimicrobial amount of at least one paraben preservative prepared by an embodiment of the disclosed method.
31 Citations
33 Claims
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1. A cold stable antimicrobial preservative system in substantially anhydrous liquid form which is dissolvable in an antimicrobially effective amount in a medium capable of supporting microbial growth comprising:
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(a) as an active preservative, a condensation product of formaldehyde and a 5,5-disubstituted hydantoin wherein each such substituent group on the hydantoin ring is independently selected from the group consisting of phenyl and lower alkyl containing 1 to about 6 carbon atoms, said condensation product having a methylol functional group attached to one or both nitrogen atoms on the hydantoin ring; (b) a substantially anhydrous, water-miscible solvent selected from the group consisting of polyhydroxy alcohols having about 3 to about 6 carbon atoms per molecule, alkylene carbonates having about 2 to about 3 carbon atoms in the alkylene radical thereof per molecule, and mixtures thereof; and (c) sufficient alkalizing agent to provide a pH between about 6 and about 9 when one part by weight of said liquid preservative system is diluted with about 9 to about 19 parts by weight of deionized water. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 23, 24, 25, 26)
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17. A method for preparing a substantially anhydrous liquid antimicrobial preservative composition comprising the steps of sequentially:
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(a) dissolving each of paraformaldehyde and a 5,5-disubstituted hydantoin wherein each such substituent is independently selected from the group consisting of phenyl and lower alkyl containing less than 7 carbon atoms in a substantially anhydrous, water-miscible solvent selected from the group consisting of polyhydroxy alcohols each having about 3 to about 6 carbon atoms per molecule, alkylene carbonates each having about 2 to about 6 carbon atoms per molecule, and mixtures thereof, together with sufficient alkalizing agent to provide a substantially anhydrous liquid composition having a pH above about 6 when diluted with about 9 to about 19 parts by weight of deionized water; (b) heating said liquid composition to a temperature above about 50 degrees C. to provide a heated liquid reaction mixture which is substantially visually clear; (c) maintaining said liquid reaction mixture at said temperature and said diluted pH until reaction between said paraformaldehyde and said hydantoin is substantially complete based on a determination of the amount of free formaldehyde present in said reaction mixture, said reaction being substantially complete when the amount of said free formaldehyde is below about 2 weight percent based on total weight of said reaction mixture; and (d) cooling and optionally filtering the so-cooled said resulting reaction mixture to provide such a substantially anhydrous liquid antimicrobial preservative composition, said preservative composition being characterized by; (1) containing a condensation product of said paraformaldehyde and said hydantoin wherein methylol functional groups are attached to at least one of the two nitrogen atoms of the ring of said hydantoin, and (2) having a capacity to inhibit and/or retard the growth of undesirable microorganisms when an antimicrobially effective amount thereof is subsequently included in a medium capable of supporting microbial growth. - View Dependent Claims (18, 19, 20, 21, 22)
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- 27. The method of claim 34 wherein said liquid composition contains 5,5-dimethylhydantoin as said hydantoin and about 1 to about 3 moles of said paraformaldehyde, calculated as formaldehyde, per mole of said 5,5-dimethylhydantoin, said solvent comprises a substantially anhydrous polyhydroxy alcohol having about 3 to about 6 carbon atoms per molecule, said temperature is in the range of about 50 degrees C. to about 110 degrees C. and said method is carried out in a sealed reaction vessel.
- 30. An antimicrobial preservative system produced by the process of claim 34 wherein said 5,5-disubstituted hydantoin is 5,5-dimethylhydantoin, and said preservative system contains 1,3-dimethylol-5,5-dimethylhydantoin.
Specification