Process for preparing stable aqueous suspensions of formaldehyde
AssigneeMontedison S.p.A.
InventorsAngelo De Micheli, Piero Bizzozero
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Abstract
Stable aqueous suspensions of formaldehyde of at least 40% by weight concentration are prepared by heating aqueous formaldehyde solutions to a temperature of from about 40.degree. C. to about 80.degree. C. in the presence of stabilizing agents, in the presence or absence of methanol, and at a pH in the range of from about 0.5 to 1.5 or about 6.0 to about 8.0, cooling the mass to a temperature of from about 10.degree. C. to about 40.degree. C., and adjusting the pH thereof to about 3.0 to 4.0.
Claims16
A stable, fluid and homogeneous suspension, containing from 40 to 60% by weight of formaldehyde in water, in which a portion of the formaldehyde is present in the form of soluble monomer and/or oligomers, the remnant of the formaldehyde, amounting to 5 to 25% by weight, with respect to the whole suspension, being present in the form of undissolved but thermally re-dissolvable polymers of the formaldehyde, which polymers do not settle after at least ten days at temperatures equal to or higher than 20.degree. C., said suspension being obtained by heating a starting aqueous solution, containing from 40 to 60% by weight of formaldehyde at temperatures from 40.degree. to 80.degree. C. under stirring, then admixing with it, at such temperatures, a stabilizing combination of polyvinyl-alcohol and of a guanamine selected from the group consisting of benzoguanamine, m-phthalo-bis-guanamine and lauroguanamine, adjusting the pH to a value from 0.5 to 1.5 or from 6.0 to 8.0, cooling the mixture to a temperature from 10.degree. to 40.degree. C., maintaining such cooled mixture under stirring for a time comprised between 4 and 24 hours, and finally adjusting the pH of the cooled mixture between 3.0 and 4.0.
A process for preparing stable, fluid and homogeneous suspensions of formaldehyde in water, said process comprising healing a starting aqueous solution containing from 40 to 60% by weight of formaldehyde at temperatures from 40.degree. to 80.degree. C. under stirring, then admixing with it, at such temperatures, a stabilizing combination of polyvinyl-alcohol and a guanamine selected from the group consisting of benzoguanamine, m-phthalo-bis-guanamine and lauroguanamine, adjusting the pH of the mixture to a value from 0.5 to 1.5 or from 6.0 to 8.0, cooling the mixture to a temperature from 10.degree. to 40.degree. C., maintaining such cooled mixture under stirring for a time comprised between 4 and 24 hours, and finally adjusting the pH of the cooled mixture to between 3.0 and 4.0, to obtain a stable, fluid and homogeneous suspension.
Dependencies are inferred from the claim text.