Water-soluble quaternized melamine-aldehyde resins and their application in the paper industry

Claim 1

Resin as claimed in claim 1, in which said aldehyde compound is selected from the group consisting of glyoxal and a mixture of formaldehyde and glyoxal.

Claim 7

A method of preparation of resins comprising the condensation product of melamine and an aldehyde compound selected from the group consisting of glyoxal and a mixture of formaldehyde and glyoxal, reacted with a quaternization agent selected from the group of dimethyl sulphate, alkyl halide and esters of arylsulfonic acids, comprising the carrying out of the condensation reaction between said melamine and 1 to 6 moles of said aldehyde compound per mole of said melamine in an aqueous medium at a pH value between 5 and 8, at a temperature lower than 100* C. for about 3 hours; the adding of, at the same temperature, said quaternization agent in an amount of from 0.2 to 0.5 moles of said agent per mole of said melamine; the curing of the resultant product and the adjusting of the final concentration by the addition of water.

Claim 8

A method for the manufacture of soft paper having good temporary resistance to humidity, comprising providing an aqueous slurry of paper pulp having a neutral or slightly alkaline pH up to about 8; introducing into said paper pulp in the pulping machine in proportions of about 1 to 10 percent based on the dry weight of the paper pulp of a resin resulting from the condensation of melamine and an aldehyde compound selected from the group consisting of glyoxal and a mixture of formaldehyde and glyoxal, in an amount per mole of melamine of 1 to 6 moles of glyoxal, reacted with 0.2 to 0.5 moles per mole of said melamine of a quaternization agent selected from the group consisting of dimethyl sulphate, alkyl halides and arylsulfonic acid esters; and forming the pulp slurry into a sheet of paper and drying the paper thus obtained.