Melamine-Formaldehyde Resins

Melamine-Formaldehyde Resins

 

synthetic products used in manufacturing plastics, carbamide glue, decorative laminated plastics, and varnishes. In terms of chemical composition, they are oligomers and are formed by polycondensation of melamine with formaldehyde.

Melamine-formaldehyde resins are synthesized in two stages with a 1:(2–12) molar ratio of melamine to formaldehyde. Various methylol derivatives of melamine are formed during the first stage at a temperature of 80°-90° C and pH 8.5; the second stage involves subsequent polycondensation of the products in an acid medium. For example, the reaction mixture must be cooled to 50°-60° C and a certain quantity of acid added to produce melamine-formaldehyde resins with the highest industrial value.

Melamine-formaldehyde resins are amorphous white products that are readily soluble in water but insoluble in organic solvents. The methylol groups in the resins undergo esterification with alcohols, primarily n-butanol and methanol, to impart to them hydrophobic properties, solubility in organic solvents (during the preparation of varnishes), and the ability to combine with plasticizers. Melamine-formaldehyde resins are cured at high temperatures, or at room temperature in the presence of slightly acidic catalysts.

REFERENCE

Tekhnologiia plasticheskikh mass. Edited by V. V. Korshak. Moscow, 1972.

G. M. TSEITLIN

References in periodicals archive ?
40-EpEs-PET was modified with urea-formaldehyde and melamine-formaldehyde resins and epoxy ester-amino resin (40-EpEs-PET-AR) was synthesized.
Epoxy ester resin having 40% oil content was modified with urea-formaldehyde and melamine-formaldehyde resins and epoxy ester-amino resin was synthesized.
5 co-condensed urea-melamines and hydroxymethylated ureas remain stable while hydroxymethylated melamine components probably condense further to form somewhat stable melamine-formaldehyde resins as shown by Pizzi (1994).
Crosslinking is through the drying oil fatty esters and/or external crosslinkers such as melamine-formaldehyde resins.
Reversibility of F-containing bonds is a specific feature of OF resins, compared to melamine-formaldehyde resins and ultimately also to phenol(resorcinol) formaldehyde resins [1].
Melamine-formaldehyde resins are already used heavily in laminate flooring, says Ulf Panzer of Agrolinz Melamine international GmbH.
g] and fractional conversion for melamine-formaldehyde resins.
Work on fast-reacting natural and synthetic resins (all deficient in formaldehyde), mainly tannins (Pizzi and Tekely 1995), resorcinol-formaldehyde resins (Pizzi and Tekely 1996), and melamine-formaldehyde resins (Pizzi and Tekely 1996, Pizzi et al.
Melamine-formaldehyde resins used for commercial molding compounds are typically filled, for example, with cellulose or wood flour in order to enhance the properties and decrease the amount of polycondensation water created during curing and to reduce the cracking propensity.
As mentioned above, known amounts of filler and melamine-formaldehyde resin, using a proportion of formaldehyde to melamine established by Perstorp AB, were mixed during the metering stage to obtain the desired weight fraction of filler in matrix [W.
In majority, these models require several elastic constants that are not readily available for the melamine-formaldehyde resin.