Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Patent
1998-01-16
1999-12-28
Niland, Patrick D.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
162119, 162135, 1621646, 4273722, 4273855, 427391, 4284231, 4284251, 524590, 524839, 524840, C08J 300, C08K 320, C08L 7500, B32B 2700
Patent
active
060082895
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to improved coating slips and a process for the production of coated papers and boards.
Aqueous coating slips based on inorganic coating pigments and polymeric binders are usually used for the production of coated papers and boards. Customary coating pigments for coating paper are China clay and calcium carbonate, as well as talc, satin white, aluminium hydroxide and titanium dioxide. Customary synthetic binders for coating slips for paper are, for example, styrene/butadiene, styrene/butyl acrylate and acrylic ester polymers and copolymers, vinyl acetate polymers and copolymers and polyurethanes. Starch or casein are chiefly suitable as naturally occurring binders.
In addition, in many cases the coating slips comprise optical brighteners for increasing the whiteness, and hydrophilic cobinders, such as polyethylene glycol, polyvinyl alcohol, polyvinylpyrrolidone, carboxymethylcellulose, algnates, guar, galactomannans and copolymers based on acrylic acid or methacrylic acid with alkyl esters of acrylic acid or methacrylic acid. These cobinders serve on the one hand as thickening agents for establishing and stabilizing the viscosity of the coating slip for paper, and on the other hand as a carrier for optical brighteners which substantially increases the activity and light-fastness of the brightener. Although on the one hand a shift in the greying limit of optical brighteners to higher use concentrations and a considerable increase in the whiteness can be achieved by using these cobinders, the hydrophilicity of these components on the other hand reduces the resistance of the coated paper to water to an undesirable extent.
The fastness of the optical brighteners to bleeding is also impaired in many cases by the hydrophilic cobinders.
The addition of crosslinking agents, such as polyamidoamines/epichlorohydrin resin, epoxy resin, polyethyleneimine, ammonium zirconyl carbonate, urea- and melamine-formaldehyde resins or dialdehydes, such as glyoxal, in order to avoid the disadvantages mentioned is known: "Wochenblatt fur Papierfabrikation 1989, page 499 and Ullmann, Encyclopadie der technischen Chemie [Encyclopedia of industrial chemistry] Volume 17, page 608". Epichlorohydrin resins indeed have a good activity as crosslinking agents. However, their high cationic charge leads to rheology problems and to fluorescence quenching and a reduction in the whiteness because of their interaction with the anionic binder and the optical brightener. Urea- and melamine-formaldehyde condensates, moreover, are undesirable in many cases because of their formaldehyde load, or, like epoxy resins, ammonium zirconyl carbonate and glyoxal, in many cases have only little action.
Polyisocyanates are mentioned as crosslinking agents in specific cast coating processes in DE-A-4 327 336. The operating speed is limited to about 30-90 m/minute. However, there is no indication at all as to which polyisocyanates could be suitable. Transfer of the process to customary high-speed coating machines with lower amounts applied has also not yet been successful, since there are considerably higher requirements on the rheology and viscosity stability of the coating colour here, and it has not as yet been possible to meet these satisfactorily.
Water-dispersible polyisocyanates have hitherto been employed for the production of optionally wood-containing papers which have been given a dry strength and/or wet strength treatment, these being employed either in the pulp or in a sizing press. A process for wet strength treatment of paper with the aid of water-dispersible polyisocyanate mixtures which contain 2 to 20% by weight of ethylene oxide units arranged in the form of polyether chains, the polyether chains containing on average 5 to 70 ethylene oxide units, is known specifically from DE-A-4 211 480. EP-A-0 582 166 describes the use of polyisocyanate mixtures which contain tertiary amino groups and/or ammonium groups and 0 to 30% by weight of ethylene oxide units in the form of polyether chains for the production of cellulo
REFERENCES:
patent: 4663377 (1987-05-01), Hombach et al.
patent: 5252696 (1993-10-01), Laas et al.
patent: 5503714 (1996-04-01), Reiners et al.
patent: 5718804 (1998-02-01), Jansen et al.
Bernhard Jansen, et al., Process for Finishing Paper Using Polyisocyanates having Anionic Groups.
U.S. Patent Application No. 08/973,066. Filed Nov. 25, 1997. (Le A 30 975).
Bernhard Jansen, et al., Repulpable Cellulose-Containing Materials.
U.S. Patent Application No. 08/860,144. Filed Jul. 19, 1997. (Le A 30 744) pp. 1A-28, plus copy of filing receipt.
Harro Traubel et al., Process for Imparting Wet Strength to Paper.
U.S. Patent Application No. 08/041,731. Filed Apr. 1, 1993. (Le A 28 857) pp. 1-29, plus copy of filing receipt.
W. Kogler, et al. Kationische Streichfarben--Derzeitiger Stand und Ausblick Wochenblatt fur Papierfabrikation, 1989, vol. 13, pp. 5419-554.
R. Pelzer, et al., Nassfestmittel heute--morgen? Wochenblatt fur Papierfabrikation, 1989, vol. 11/12. pp. 499-804.
Ullman, Encyclopadie der techn. Chemie, 4. Auflage, vol. 17, (1979) pp. 608-609.
Ullman, Encyclopedia of Industrial Chemistry, vol. A18, (1991) pp. 650-651.
H. Graab, Derzeitiger Stand und Entwicklungstendenzen der Streichmaschinen Das Papier 10 (1986), vol. 10a, pp. 125-133.
Konig Joachim
Kopp Jurgen
Wallpott Gottfried
Wenderoth Eckhard
Bayer Aktiengesellschaft
Gil Joseph C.
Henderson Richard E.L.
Niland Patrick D.
LandOfFree
Coating slips with polyisocyanates does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Coating slips with polyisocyanates, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Coating slips with polyisocyanates will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2382960