Paper making and fiber liberation – Processes and products – Non-fiber additive
Patent
1995-03-15
1996-09-10
Chin, Peter
Paper making and fiber liberation
Processes and products
Non-fiber additive
162148, 1621682, 1621811, D21H 2128
Patent
active
055542611
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a process for dyeing paper during paper manufacture by adding water-soluble anionic dyes and cationic polymers to the paper pulp as fixing agents and removing water from the paper pulp with the formation of dyed paper.
EP-A-0 061 173 discloses a process for dyeing paper using water-soluble acidic dyes and/or direct dyes in aqueous medium in the presence of cationic auxiliaries. The dyeing of the paper in this process is preferably carried out in bulk, ie. during manufacture of the paper. The cationic auxiliaries used here are water-soluble reaction products which are obtainable by reaction of alkylating agents which contain an aromatic substituent with cationic polyelectrolytes. Suitable auxiliaries of this type are, for example, benzylated polyethyleneimines. The known strongly cationic polymers have the disadvantage that they very greatly dull the brilliance of the dyed paper. Condensates of dicyandiamide and formaldehyde or condensates of urea and formaldehyde are therefore mainly used in practice as fixing agents for water-soluble anionic dyes in the dyeing of paper. The condensates have the disadvantage that they contain a certain amount of free formaldehyde.
EP-A-0 309 908 discloses a process for dyeing paper in bulk using pigments and fixing agents, in which pigments and fixing agents are added simultaneously to the paper pulp to be dyed and various classes of cationic polymers are used as fixing agents, for example polymers of diallyldimethylammonium chlorides, polymers of N-vinylimidazoles, polymers of N-vinylimidazolines, copolymers containing vinylamine units and copolymers of acrylamide with dialkylaminoalkyl acrylates and/or methacrylates.
U.S. Pat. No.4,421,602 discloses partially hydrolyzed homopolymers of N-vinylformamide which contain N-vinylformamide and vinylamine units. They are used as retention, dehydrating and flocculating agents in the manufacture of paper. EP-A-0 216 387 additionally discloses the addition of copolymers of 95-10 mol % of N-vinylformamide and 5-90 mol % of an ethylenically unsaturated monomer from the group consisting of vinyl acetate, vinyl propionate, the C.sub.1 - to C.sub.4 -alkyl vinyl ethers, N-vinylpyrrolidone, and the esters, nitriles and amides of acrylic acid and methacrylic acid in at least partially hydrolyzed form in which up to 100 mol % of the formyl groups are removed from the copolymer, in amounts of 0.1-5% by weight, based on dry fibers, to the paper pulp before sheet formation as a wet- and dry-consolidation agent for paper.
The use of hydrolysed homo- and/or copolymers of N-vinylformamide with a degree of hydrolysis of at least 60% of the copolymerized N-vinylformamide units as a fixing agent in combination with a cationic retention agent in the manufacture of paper, cardboard and (paperboard) by removal of water from a paper pulp containing interfering substances is additionally disclosed in EP-A-0 438 707.
It is an object of the present invention to make available a process for dyeing paper in which the dyeing is carried out in bulk during the paper-manufacturing process using water-soluble anionic dyes and cationic formaldehyde-free polymers as fixing agents, dyed paper with high light-fastness and a low dulling of the brilliance being obtained.
We have found that this object is achieved by a process for dyeing paper during paper manufacture by adding water-soluble anionic dyes and cationic polymers to the paper bulk as fixing agents and removing water from the paper pulp with the formation of dyed paper, if polymers containing vinylamine units are employed as cationic polymers.
The paper is dyed during paper manufacture by the process according to the invention. For this purpose, water-soluble anionic dyes and specially selected cationic polymers are added to the paper pulp. Compared with other known fixing agents, dyed paper which has a high light-fastness and in which the brilliance is only slightly dulled is obtained by the process according to the invention.
Suitable water-soluble anionic dyes for dyeing p
REFERENCES:
patent: 4421602 (1983-12-01), Brunmueller et al.
Breitschaft Walter
Lorencak Primoz
Nilz Claudia
Sendhoff Norbert
Zillig Manfred
BASF - Aktiengesellschaft
Chin Peter
LandOfFree
Dyeing of paper does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Dyeing of paper, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Dyeing of paper will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1318037