Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
  • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
  • B41M5/50—Recording sheets characterised by the coating used to improve ink, dye or pigment receptivity, e.g. for ink-jet or thermal dye transfer recording
  • B41M5/52—Macromolecular coatings
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H21/00—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
  • D21H21/14—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties characterised by function or properties in or on the paper
  • D21H21/30—Luminescent or fluorescent substances, e.g. for optical bleaching
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
  • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
  • B41M5/50—Recording sheets characterised by the coating used to improve ink, dye or pigment receptivity, e.g. for ink-jet or thermal dye transfer recording
  • B41M5/52—Macromolecular coatings
  • B41M5/5218—Macromolecular coatings characterised by inorganic additives, e.g. pigments, clays
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
  • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
  • B41M5/50—Recording sheets characterised by the coating used to improve ink, dye or pigment receptivity, e.g. for ink-jet or thermal dye transfer recording
  • B41M5/52—Macromolecular coatings
  • B41M5/5227—Macromolecular coatings characterised by organic non-macromolecular additives, e.g. UV-absorbers, plasticisers, surfactants
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
  • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
  • B41M5/50—Recording sheets characterised by the coating used to improve ink, dye or pigment receptivity, e.g. for ink-jet or thermal dye transfer recording
  • B41M5/52—Macromolecular coatings
  • B41M5/5236—Macromolecular coatings characterised by the use of natural gums, of proteins, e.g. gelatins, or of macromolecular carbohydrates, e.g. cellulose
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
  • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
  • B41M5/50—Recording sheets characterised by the coating used to improve ink, dye or pigment receptivity, e.g. for ink-jet or thermal dye transfer recording
  • B41M5/52—Macromolecular coatings
  • B41M5/5245—Macromolecular coatings characterised by the use of polymers containing cationic or anionic groups, e.g. mordants
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
  • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
  • B41M5/50—Recording sheets characterised by the coating used to improve ink, dye or pigment receptivity, e.g. for ink-jet or thermal dye transfer recording
  • B41M5/52—Macromolecular coatings
  • B41M5/5254—Macromolecular coatings characterised by the use of polymers obtained by reactions only involving carbon-to-carbon unsaturated bonds, e.g. vinyl polymers

Definitions

• the invention relates to a cationically modified brightener dispersion for the paper industry.
• the degree of whiteness of paper and cardboard is essential technical parameters of the final product.
• the most important Raw materials of paper production, pulp and wood pulp, are but not pure white, but yellowish. From human A yellow white is perceived as darker than an eye bluish white. It is for making a white paper therefore necessary, the yellow tint with the support of certain Aids, including to be eliminated by adding optical brighteners.
• the optical brighteners now have the ability to fluoresce to compensate for the yellow cast without simultaneously reducing the brightness to diminish.
• the optical brighteners adsorb UV light with a maximum at 350 - 360 nm and convert it into visible blue light with a maximum at 440 nm.
• the Substances are very effective, so adding a small amount has a great influence on the whiteness of the paper Has.
• optical brighteners in the paper pulp with surface sizing or in the stroke one is able to Produce papers with high whiteness.
• the optical brighteners generally have an anionic one Charge character and behave like in many cases substantive dyes.
• the derivatives of diamino-stilbene disulfonic acids have been able to prevail for use as brighteners in the paper industry.
• Types with high solubility tend to have less affinity for the fiber.
• the available products all have the following basic structure: wherein Me are alkali, preferably sodium, and x, y, w and z represent different end groups, such as halogen, alkyl, hydroxy or alkyl sulfo groups.
• disulfonic acid derivatives there are also the tetra- and hexasulfonic acid derivatives with 4 and 6 sulfo groups in the molecule. Solubility and acid stability increase with the number of sulfo groups, while the affinity for the fiber decreases.
• Distyryldiphenyl derivatives have recently been introduced as alternative brighteners for the paper industry.
• the advantage of these products is that the stilbene group is doubled, which has significantly increased efficiency.
• These connections have the general basic structure: the number of sulfo groups can also be up to 6.
• optical Brightener of the diamino stilbene sulfonic acid type is Existence of two different atomic arrangements (cis-trans isomerism).
• the optical brightener can only be used in the trans form fluoresce while the cis form is unable to do so is.
• Commercial brightener solutions are in the trans form in front. The effect of light transforms it into the cis shape instead, which is achieved by sufficient fixation of the Brighteners on a surface can be partially avoided. For this reason, the brighteners must be made of suitable substrates (Carrier) bound.
• optical brighteners have no affinity for pigments or synthetic binders must be in coating colors basically another component can be added who can pull up the brighteners.
• carrier materials act z.
• optical brighteners are anionic Substances by cationic aids, such as alum, cationic sizing, wet strength and retention agents disturbed become. The higher the cationic, the more serious this is Auxiliary charge density is.
• cationic Additives in size press formulations (such as cationic Starch, cationic dialkyldiketenes (AKD), cationic synthetic surface sizing agents) and in coating colors.
• anionic brighteners Especially with cationic coating color formulations that state of the art for coated inkjet papers, anionic brighteners fail.
• Cationic brighteners correspond but not the 36th recommendation of the Federal Health Office (BGA) for dyes in food packaging. Become bright white papers are required, so often the qualitative and economic benefits of cationic sizing or Coating system because of the loss of white and the Damage to the anionic optical brightener not used become.
• DE 26 28 571 A1 describes a method for improvement the effect of optical brighteners in the paper industry, taking anionic brighteners with a polypiperidinium halide (a cationic polymer) that is dispersed in State adsorbed on a finely divided carrier, in Be brought into contact.
• the carrier can e.g. B. a finely divided inorganic filler or a finely divided organic Substance such as starch, carboxymethyl cellulose, fine particles Represent cellulose fibers or finely divided wood pulp. Under the finely divided carriers (this also applies to starch) one substances that are not in colloidal solution are present, d. H. the cationic polymer pulls onto the surface of the inorganic or organic carrier.
• CH 6 17 453 A5 describes aqueous solutions more water-soluble optical brightener, which is an anionic optical brightener, an amioplast precondensate (a cationic polymer) and optionally contain an additional solubilizer.
• the solubilizer can be, for example, a polyglycol. However, this is not a protective colloid. Further the brightener dispersion is anionic.
• the invention has for its object the brightening effect of anionic optical brighteners in the presence of cationic Interfering substances or cationic surface and To improve coating color formulations. Another job is to reduce bleeding of the brightener and increase its light stability.
• the anionic protective colloid is preferably weakly anionic. Under the term “weakly anionic” or “weakly cationic "means that the protective colloid has a charge density less than 1 mmol / g, preferably around 0.25 mmol / g.
• the protective colloid (b) is believed to be the anionic brightener (a) envelops so that there is little interaction with the cationic or cationized polymer (c) takes place, which causes flocculation of the brightener (a) and an associated Fluorescence quenching is prevented.
• the invention also encapsulates the cationic polymer become (coacervate formation) whereby a flocculation of the Whitener (a) is prevented, even if it is not now is more enveloped.
• the charge density is determined using the following method: a aqueous dispersion of the weakly anionic or weakly cationic Protective colloids are in a concentration of 0.1 up to 5 wt .-% with a standard polyelectrolyte opposite Charge using the Streaming Current Detection (SCD) method titrated.
• SCD Streaming Current Detection
• stronger anionic protective colloids (b) can also be used a charge density of about 1 to 1.5 mmol / g can be used.
• the optimal fixation of the cationically modified brightener to the fiber and its weakly cationic charge make it possible even under difficult conditions , e.g. B. in the presence of Al +3 ions, cationic fixing, wet strength and sizing agents, achieve excellent brightening effects even with heavily wood-containing and waste paper (AP) -containing material systems.
• the cationically modified brighteners can also be used without Problems in cationic size press formulations and Use coating color systems. In addition to an excellent Brightening effect in cationic glue and coating color formulations will also see significant quality improvements in the Terms of inkjet printability, and improving the Bleeding and lightfastness of inkjet inks achieved.
• Brightening is not only the desired renunciation of the reductive Bleach can be realized, but it is also from many manufacturers of waste paper and wood-containing (h.h.) paper desired, 3 to 4 points higher whiteness economically achievable.
• the synergistic Bleaching and brightening effect can be used, which can be combined of photoactivators and optical brighteners. Suitable photoactivators are e.g. in EP-A-0 588 767 and EP-A-0 588 768 and in DE-A-199 16 078.3.
• modified brightener dispersion used anionic optical Brightener is preferably a stilbene derivative or a Distyryldiphenyl compound as discussed above of the prior art.
• the nonionic protective colloid is preferably polyvinyl alcohol (PVA), polyvinyl pyrrolidone (PVP), polyethylene glycol (PEG), polyacrylamide (PAA) and / or a nonionic or amphoteric polysaccharide, the anionic protective colloid Polysaccharide with a charge density of up to about 1.5, preferably up to 1.0 mmol / g and the weakly cationic Protective colloid a cationized polysaccharide, such as Galactomannan or guar with a charge density of up to about 1 mmol / g.
• PVA polyvinyl alcohol
• PVP polyvinyl pyrrolidone
• PEG polyethylene glycol
• PAA polyacrylamide
• the nonionic protective colloids are generally commercial products. For example, PVA by partial or full saponification from Obtained polyvinyl acetate.
• Commercial products are the "Mowiol®" types from Hoechst AG, e.g. Mowiol 3-83, Mowiol 4-88 (partially saponified), Mowiol 3-98, Mowiol 4-98 and Mowiol 6-98 (fully saponified).
• Mowiol® from Hoechst AG, e.g. Mowiol 3-83, Mowiol 4-88 (partially saponified), Mowiol 3-98, Mowiol 4-98 and Mowiol 6-98 (fully saponified).
• the achievable solids contents result from the saponification number and the molecular weight.
• PEG Polyethylene glycols
• PAA Polyacrylamides
• the nonionic or amphoteric polysaccharides are, for example by the company Meyhall (Galactomannane, Guars) as well as from starch manufacturers (Cerestar, Roguette, etc.).
• the preferably weakly anionic protective colloids are also commercially available under the names galactomannan, Guar, starch available.
• the protective colloid e.g. PVA
• the protective colloid e.g. PVA
• the mixture is brought to a minimum temperature of 90 ° C warmed until the PVA is completely dissolved.
• the intended cationic auxiliaries are brought to about 60-65 ° C (e.g. Poly-DADMAC) as well as the non-ionic auxiliaries (e.g. PVP or PEG) slowly added with stirring and stirred in. You can then add other chemicals while stirring be added.
• the weakly cationic protective colloid dispersions can e.g. can be produced as follows:
• the PVA is in 350 parts by weight of water at 95 ° C for 30 minutes open minded. After cooling to 60 ° C remaining chemicals stirred in.
• the dispersion has one Charge density from 0.10 to 0.70 mmol / g.
• the preparation is carried out analogously to Example A with a solids content of 30% by weight.
• the dispersion has a charge density from 1.0 to 2.0 mmol / g. It can also be used for deployment of the cationized polymer (component C) used become.
• the cationic or cationized water-soluble polymers (c) are generally characterized in that they contain quaternary nitrogen atoms in the main chain and / or in the side chains.
• examples of such compounds are polymeric dially compounds, melamine-formaldehyde resins, epichlorohydrin resins, dicyandiamide resins, quaternary acrylates and inorganic polymers such as polyaluminium hydroxychloride (PAC).
• Poly- (diallyldimethylammonium chloride) (poly-DADMAC) which preferably has a molecular weight of 45,000 and 120,000 and the following possible structure, has proven particularly useful:
• the following cationic polymers for the Cationization or for the cessation of the cationic Charge density (the protective colloid dispersion) (b) used be made of relatively low molecular weight compounds is assumed.
• R H, methyl, ethyl, n-butyl;
• X OH, Cl, Br
• PAA cationically modified polyacrylamides
• PAAM Polyamide amines
• PEI Polyethyleneimine
• polyaluminium hydroxychloride (PAC) Al 2 (OH) 5 Cl.2.5 H 2 O can be used as the inorganic polymer.
• the ratio of components a: b: c is preferably 1: 1-10: 1-6. This ratio depends on the number of sulfo groups in the optical brightener.
• the cationized polymer (c) a coacervate of an anionic or nonionic hydrophilic polymer containing OH groups, preferably a polysaccharide and / or a polyvinyl alcohol and a cationic polymer.
• the coacervate has a lower cationic charge density as the cationic polymer, whereby a coating of the anionic brightener (a) with the Protective colloid (b) (as in the first embodiment) is not more is needed. So the coacervate is unable to to precipitate anionic brighteners. This way too simplifies the manufacture of the brightener dispersion.
• the unclad brightener (a) that is formed by the nonionic or anionic protective colloid Protective coating over the cationic polymer preferably thicker, as it is otherwise easier to precipitate or delete of the brightener comes.
• the protective coating causes the coacervate has a low electrical charge. It is in front of everyone Things important that when starting to mix the cationic Polymers with the non-ionic or weakly anionic Protective colloid no brightener present in the dispersion is, but this is only added afterwards.
• the protective colloid (b) completely or partially omitted if an excess of anionic or non-anionic polysaccharide used in the coacervate becomes.
• the ratio between optical brightener (a) and the above-mentioned coacervate is generally about 5 to 40% by weight, preferably about 10 to 25% by weight.
• the brightener dispersion according to the invention preferably has one Solids concentration of about 5 to 25 wt .-%, the The proportion of the anionic optical brightener is about 0.5 to 5 % By weight.
• the brightener dispersion according to the invention generally has pH ranging from about 4.5 to about 10 preferably from about 5.5 to 7.5.
• the charge density of the brightener dispersion according to the invention is preferably about 0.002 to 0.8 mmol / g, especially 0.08 to 0.3 mmol / g.
• the charge density of the total dispersion is determined using the same method as the charge density the protective colloid dispersion from the components (a) and (b).
• the invention Brightener dispersion additionally a finely divided, insoluble Contain silicate.
• the insoluble silicate is preferred a layered silicate, especially a swellable smectite Layered silicate, a zeolite and / or a synthetic Alkali or alkaline earth aluminum silicate.
• the layered silicate is believed to be the weakly cationic Coacervate adsorbs because it is anionic. On the coacervate layered silicate complex the anionic brightener is also stored on, thereby avoiding its bleeding. Also has the sorbed brightener has higher light stability.
• the preferred layered silicates adsorb the anionic Brightener, the protective colloid and / or the coacervate the outer surfaces or between the layers.
• the special preferred swellable smectic layer silicates offer a larger size to the components mentioned as adsorbents Variety of different binding sites than other pigments.
• the absorbed macromolecules are almost constant not desorbed again when the solution is diluted or pH and ionic strength are changed.
• the smectite Layered silicates have a high structure Water binding capacity.
• the best-known swellable smectic layered silicate, bentonite is a three-layer mineral in which the Al octahedral layer lies between two Si tetrahedral layers. Isomorphic replacement of Al 3+ by Mg 2+ in the middle lamella creates negative stratified charges, which are compensated for by cations between the layers. These cations can be hydrated, which in the case of sodium ions can lead to complete delamination of the layers in aqueous suspension.
• the invention further relates to a method for the production a cationically modified brightener dispersion, such as it is defined above; the process is characterized by that one (variant 1) the anionic optical Brightener (a) first in one or more steps with the non-ionic or weakly ionic or weakly cationic Protective colloid (b) in an aqueous medium and then the cationic or cationized polymer (c) adds, or that one (variant 2) the anionic brightener (a) with the coacervate in an aqueous medium.
• the method according to variant 1 is carried out that in the first stage (s) the anionic Brightener in an aqueous medium and this medium with stirring the nonionic or weakly anionic or weakly cationic protective colloid is added until you get close of the zero point of charge comes or this easily exceeds positive range, whereupon a dispersion of the cationic or cationized polymer (c) is added.
• the production of the cationically modified brightener dispersion from an anionic brightener (a) Variant 1 in several steps, the sequence of which was followed exactly must be avoided to avoid precipitation reactions.
• the first step is to make sure that by adding the protective colloid (b) an optimal fixation of the anionic Brightener on the nonionic or weakly cationic polymers he follows. There will also be a significant reduction achieved the anionic charge of the optical brightener.
• polyelectrolytes are dissociated into polyvalent ones Macroions and an equivalent number of solvated low molecular counterions. Coacervation occurs when one of the polymers is negative and the other is positively charged.
• cationic polymer Charge density (mmol / g) Poly DADMAC 5.5 - 7.5 Dicyanidimide condensate product 2.5 - 3.5 Cationic MF resins 3.0 - 4.0
• the non-coated anionic brightener (a) preferably added only after the formation of the coacervate.
• the invention also relates to the use of the above described cationic brightener dispersions in the Paper production (in bulk), for surface sizing, when painting paper and to lighten the filler and Coating color pigments.
• the invention further relates to the paper which contains brightener dispersions described above or is coated with it.
• Example B 60 parts by weight of the cationic PVA dispersion of Example B (as part of component (c)) very slowly below Stir metered in and 15 min. mixed well. Finally 20 parts by weight of a 5% poly DADMAC solution (rest component (c)) and 25 parts by weight of a PAC solution (Cartafix LA liquid) added. The finished dispersion has one Charge density of 0.3 mmol / g.
• an anionic distyryl diphenyl derivative brightener (Uvitex® NFW; manufacturer Ciba-Geigy; also contains PEG and a surfactant) are placed in a beaker. Then 50 parts by weight of a (30%) PVP K 30 solution and 50 Parts by weight of water added.
• the mixture is mixed thoroughly with stirring (10 min.). Then 90 parts by weight of the weakly cationic PVA dispersion (from example A) metered in very slowly with stirring, and the mixture is 10 min. well stirred. The charge density the dispersion is 0.009 mmol / g.
• the cationic brightener dispersion thus obtained has one Charge density of 0.085 mmol / g.
• an anionic brightener Tinopal® SK B from Ciba-Geigy, a distyryl diphenyl derivative brightener
• Example B Another 30 parts by weight of water and 85 parts by weight the cationic PVA dispersion of Example B very slowly metered in with stirring and 15 min. mixed well.
• the cationically modified brightener dispersion thus obtained has a charge density of 0.12 mmol / g.
• Example B 90 parts by weight of the cationic PVA of Example B be metered in very slowly with stirring.
• the dispersion is 15 min. mixed well, whereupon 30 parts by weight of one 5% poly-DADMAC solution can be added.
• the charge density of the cationically modified so obtained Brightener dispersion is 0.002 mmol / g.
• This dispersion is mixed with 60 parts by weight of water and 40 parts by weight cationic PVA dispersion from Example B 15 min. mixed well while stirring. Then 35 parts by weight a 5% poly DADMAC solution slowly with stirring added.
• the cationically modified brightener dispersion has one Charge density of 0.04 mmol / g.
• Example B 60 parts by weight of cationic PVA dispersion of Example B metered in very slowly with stirring, after which it was good for 15 min is mixed. Finally, 30 parts of polyaluminium chloride (PAC) solution (Cartafix® LA liquid) added.
• PAC polyaluminium chloride
• the PVP K 30 solution provides additional stabilization the dispersion achieved.
• the PAC solution without the addition of the protective colloid and the cationized polymer would have fluorescence of the stilbene derivative brightener normally delete. In the present Example, however, it can be used for further charge adjustment be used.
• the charge density of the cationically modified brightener dispersion is 0.4 mmol / g.
• the quality of the inkjet print is determined by the mechanical Requirements of the printer used as well as of the chemical-physical Properties of ink and substrates certainly.
• the coating colors were prepared by means of a motorized hand knife (Erichsen K Control Coater) on wood-free, surface sized base paper of 80 g / m 2 with a coating amount of 10g / m 2 applied.
• the pH was determined with a glass electrode, the zeta potential according to PTS-RS: 016/93 based on the principle of microelectrophoresis measured (see also "Zeta Potential Symposium", Kunststoff 1988, conference proceedings, pp. 5-7).
• coated papers were in a forced air drying cabinet dried at 50 ° C.
• For printing on coated papers became a Canon BJC 4000 printer or a Hewlett-Packard (HP) DJ 850 printer used.
• the whiteness determination was carried out according to DIN 53 145, part 1 and part 2 (04.92) with and without UV component.
• the recipe and the properties the coating color and the assessment of the coated Papers are shown in the table below.
• test results show that the addition the cationically modified brightener dispersion according to the invention not only achieve significant whiteness improvements but also improved inkjet printing results in the Comparison to the standard recipe can be obtained. Another one The result of the laboratory tests was that different printers (Canon or HP) very different printer results can deliver the same paper.
• Powdered cationic starch (C-Film 5960, manufacturer Cerestar) is done in a starch cooker or a water bath Add water (solids content 25% by weight) at 90 ° C for 30 min. open minded.
• This strength serves as a reference substance.
• digested cationic starch (a) or the cationic starch coacervate (b) were treated with a cationic synthetic polyacrylate dispersion as a sizing agent (Basoplast® 280 D BASF) by mixing the cationic size press formulations given below manufactured.
• a cationic synthetic polyacrylate dispersion as a sizing agent Basoplast® 280 D BASF
• the whiteness was determined according to DIN 53 145, part 1 and Part 2 with and without UV component.
• the results show that with the cationic starch coacervate (b) compared to cationic Starch with cationic sizing agents considerable Whiteness increase up to 15 CIE whites, let achieve.
• Inkjet coating colors were used according to the procedure of Example 8 manufactured.
• the yellowness index and the brightness were as in Example 7 or 8 determined.
• the results of the investigation show that the modified Bentonite with an optical brightener is an improvement the whiteness compared to the untreated bentonite by 4 points, an increase in brightness by 2 points and a reduction of the yellow cast can be achieved by about 3 points.

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• 1999
  • 1999-05-22 DE DE1999123778 patent/DE19923778A1/de not_active Withdrawn
• 2000
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