Melamine Chemicals, Inc.

Shen Ji

George M Crews

Charles U Pittman, Jr

Ruicheng Ran

Ammeline-melamine-formaldehyde resins (AMFR) containing from 5-100% ammeline were synthesized by the polymerization of the sodium salt of ammeline, which must be made in advance, melamine, and formaldehyde in basic medium (pH=9.2-10.0). In this copolymerization, it is possible to make uniform random AMFR resins with any mole ratio of ammeline salt to melamine. Preferably the AMFR resin will contain from 5-10% ammeline. As an 'ionomer' or a 'polyelectrolyte,' both the solid and solution properties of these resins (such as melting temperature, solubility, solution stability, etc.) depended directly on the mole ratio of ammeline to melamine and formaldehyde, and/or on the pH value of the medium in which the AMFR resin was present. The pH value controlled the ammeline rings/ammeline's salt groups and also the ratio of unprotonated to protonated amino groups on both the melamine and ammeline rings. These polymers have different solubilities, cloud points and solution lifetimes (which depend on pH) than melamine-formaldehyde resins. AMFR systems containing from 5-10% ammeline are more flexible than MFR resins and exhibit different adhesion properties than MFR resins.

Ammeline-melamine-formaldehyde resins (AMFR) and method of preparation

A process of producing melamine formaldehyde resins using crude or impure melamine is described. The process using the impure or crude melamine includes the control of the pH within the range of from about 8 to 10, and preferably 9 to 9.2 during at least the initial stages of the formaldehyde/melamine reaction. The pH control provides resins having commercially acceptable characteristics, with the cook times of the resin formation also being commercially acceptable.

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Mississippi State, MS, United States of America

Shen Ji