Abstract: Paper, board and cardboard are produced by draining a paper stock in the presence of a nonhydrolyzed copolymer which contains, as polymerized units,(a) from 99 to 1 mol % of N-vinylformamide and(b) from 1 to 99 mol % of one or more water-soluble basic monomers of the formula ##STR1## where R.sup.1 is H, CH.sub.3 or C.sub.2 H.sub.5, R.sup.2, R.sup.3 and R.sup.4 are each H, CH.sub.3, C.sub.2 H.sub.5 or (--CH.sub.2 --CH.sub.2 --O--).sub.n H, R.sup.5 and R.sup.6 are each C.sub.1 -C.sub.10 -alkyl, A is C.sub.1 -C.sub.6 -alkylene, n is from 1 to 6 and Y.sup..crclbar. is an anion, in an amount of from 0.01 to 3.5% by weight, based on dry paper stock.

Abstract: Bridged, water-soluble copolymers are obtainable by(A) copolymerization of a monomer mixture of(a) from 50 to 99 mol % of acrylamide and/or methacrylamide,(b) from 50 to 1 mol % of a monoethylenically unsaturated monomer containing actual groups and(c) from 0 to 20 mol % of monomers which differ from (a) and (b),in the presence of a polymerization initiator under conditions such that the acetal groups of the monomers (b) undergo virtually no hydrolysis,(B) hydrolysis of the acetal groups of the monomers (b), present as copolymerized units in the copolymers (A),(C) condensation of the copolymers (B) containing aldehyde groups at a pH above 5, at most to a degree such that the resulting condensates are still water-soluble and(D) stopping of the condensation reaction by adding acid until the pH reaches 3 or less,and are used as paper stock additives in papermaking for increasing the wet strength of paper.

Abstract: Paper, board, and cardboard having high dry strength are made by adding to the paper stock a dry strength agent which is obtainable by mixing enzymatically digested starch having a viscosity of from 20 to 2,000 mPa.s (measured in 7.5% strength aqueous solution at 45.degree. C.) and a cationic polymer which contains, as typical copolymerized monomers,(a) diallyldimethylammonium chloride,(b) N-vinylamine or(c) an unsubstituted or substituted N-vinylimidazoline, the K value of the cationic polymer in each case being not less than 30, and draining the paper stock with sheet formation.

Abstract: The novel compounds of the general formula ##STR1## where R.sup.1 and R.sup.2 are identical or different aliphatic, cycloaliphatic, aromatic or heterocyclic radicals which are free of groups which impart water solubility,X, Y and Z are each chlorine, bromine or a radical OR.sup.3 andR.sup.3 is unsubstituted or substituted phenyl, naphthyl or anthryl,are very useful as fluorescent dyes in organic material.

Abstract: Paper and paperboard of high dry strength are produced by adding a dry strength enhancer to the paper stock and dewatering the paper stock with sheet formation by using as the dry strength enhancer a mixture of a cationic polymer which contains as characteristic monomers copolymerized units of(a) diallyldimethylammonium chloride,(b) N-vinylamine or(c) a substituted or unsubstituted N-vinylimidazoline and has a K value of not less than 30, and natural potato starch which is converted into a water-soluble form by heating in an aqueous medium at above the gelatinization temperature of natural potato starch in the absence of any oxidizing agents or alkali.

Abstract: A process for the drying of inorganic hydrogels obtained from readily hydrolyzable compounds of the elements Al, Si, Ti, B, La, Zr, Cr, Sn, Th or Mg, and organic hydrogels based on gelatine, albumin or agar agar, from CO.sub.2, to give aerogels is easy to carry out industrially, and drying can be effected at from room temperature to 90.degree. C.The resulting aerogels are transparent and have a low bulk density and low thermal conductivity.The aerogels can be used as packing materials for liquid chromatography, as catalyst carriers, as substrates for enzymes and as adsorbents.