Classifications

• • 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
  • D21H19/00—Coated paper; Coating material
  • D21H19/36—Coatings with pigments
  • D21H19/38—Coatings with pigments characterised by the pigments
  • D21H19/42—Coatings with pigments characterised by the pigments at least partly organic
• • 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

Definitions

• aqueous coating slips are used to a very large extent, which in addition to the usual white pigments - especially china clay and calcium carbonate - contain plastic dispersions as binders.
• whiteners For the optical brightening of these coating slips, substantive anionic whiteners are usually used, e.g. Alkali salts of bistriazinylaminostilbene disulfonic acids used.
• these whiteners only have very unsatisfactory brightening effects and a very low graying limit (whitener concentration, at which further addition of the whitener does not result in an increase or even a decrease in the whiteness).
• the white toner types mentioned have a very low light fastness in those coating slips.
• coating slips for the paper coating can be lightened with the above-mentioned whiteners without the disadvantages mentioned, if the coating slips are brighteners, water-dispersible cellulose powder and optionally coating pigments or a brightener preparation consisting essentially of brighteners in any order Cellulose powder and optionally a coating pigment are added, the cellulose powder in each case having an average particle size of less than 50 ⁇ m.
• Suitable cellulose powder is, for example, microcrystalline cellulose which is obtained from cotton linters or wood pulp mostly by a combination of hydrolytic degradation and mechanical wet comminution of the particles and by subsequent spray drying and which no longer has any fiber structure (cf. "Umschau” 77 (1977), 312).
• Cellulose powders which have been produced by dry grinding of conventional wood pulp and which likewise have practically no fiber structure are also suitable.
• Cellulose powders which have a high crystallinity of more than 30%, preferably more than 50%, and a reduced hydrophilicity and dispersibility in water up to a solids content of about 25% are particularly suitable.
• water-insoluble substituted cellulose types e.g. Cellulose ethers such as methyl or ethyl cellulose or cellulose esters such as cellulose acetate, acetobutyrate or acetopropionate.
• Preferred cellulose powders are those which have particle sizes of 25-35, in particular approximately 30 ⁇ m.
• cellulose powder based on the total amount of pigment addition
• Suitable cellulose whitening agents to be used according to the invention are bistriazolylstilbene, bisstilbene and especially bistriazinyl-aminostilbene disulfonic acids.
• Examples of particularly suitable brighteners are those of the formula wherein X1 amino, methylamino, ethylamino, dimethylamino, diethylamino, 2-hydroxy-ethylamino, 3-hydroxypropylamino, di- (2-hydroxy-ethyl) -amino, di- (2-hydroxypropyl) -amino, 2-sulfo-ethylamino, morpholino , Anilino, chloranilino, sulfoanilino, methylanilino or disulfoanilino and X2 is hydroxy, methoxy, ethoxy, methoxyethoxy, chlorine or X1, as well as those of the formula wherein X3 and X4 represent hydrogen, methyl, ethyl, phenyl or sulfophenyl, as well as the formula wherein X5 is hydrogen, methyl, ethyl, methoxy, ethoxy, chlorine
• the brighteners are preferably in the form of their sodium salts.
• Suitable coating pigments are clay, kaolin, silica, aluminum oxide, aluminum silicate, talc and especially chalk. These pigments are preferably used as an aqueous slurry.
• the brightener preparations according to the invention can be prepared in a simple manner by dispersing suitable cellulose powders in water and adding customary anionic paper or textile brighteners.
• the brightener is readily absorbed onto the dispersed cellulose powder even at low temperature, and the brightened cellulose powder shows no graying even with relatively high brightener additives.
• the white toner preparations according to the invention contain customary white pigments
• the preparation can be carried out in a simple manner by stirring suitable cellulose powders and customary anionic paper or textile brighteners, possibly together with a little water, into commercially available filler slurries or else by adding them during the dispersing and grinding process in the production of the filler slurries.
• the dispersions obtained can contain conventional anionic or nonionic dispersants, e.g. Salts of polycarboxylic acids, sulfated or unsulfated higher alkanol or alkylphenol polyglycol ethers, lignin sulfonates, carboxymethyl cellulose, hydroxyethyl cellulose and others.
• anionic or nonionic dispersants e.g. Salts of polycarboxylic acids, sulfated or unsulfated higher alkanol or alkylphenol polyglycol ethers, lignin sulfonates, carboxymethyl cellulose, hydroxyethyl cellulose and others.
• the cellulose powders can be used in the white toner preparations according to the invention in any ratio based on white pigment, the viscosity being able to be adjusted to a desired value by adding water at the same time.
• a content of up to 20% cellulose powder based on white pigment is preferred, it being possible to set high pigment concentrations in the slurry without a significant increase in viscosity occurring.
• cellulose powder based on the total amount of pigment addition
• the amount of brightener used depends on the amount of the cellulose powder present in the white toner preparations according to the invention. In general, you can Amounts up to 10% active substance based on cellulose powder are used. Higher quantities no longer have any additional effects since the graying limit is exceeded. Amounts of 2.5 to 7% based on dry cellulose powder are preferred. It is advantageous to use the brightener in the form of an approximately 10 to 30%, preferably 15 to 25%, commercially available liquid formulation.
• the brightener preparations to be used according to the invention are new and therefore also the subject of the present invention.
• the brightener preparation can be added to the coating color in dispersed form immediately after its preparation and can be processed on conventional coating machines.
• aqueous brightener preparations can also be processed into powder mass by customary process steps, such as filtration and drying.
• Another variant according to the invention is to add the cellulose powder and the brightener in separate form when preparing the coating color, the brightener immediately drawing onto the cellulose powder used.
• the amount of the brightener or the brightener preparation used depends on the desired brightening effect. In general, 0.01 to 0.5% by weight of pure active substance on brightener (based on the pigment of the paper coating slip to be lightened) is sufficient.
• a particular advantage is that, depending on the coating slip composition, the graying limit that can be achieved (up to which a further brightener additive brings additional effects) is extremely high.
• microcrystalline cellulose with an average particle size of 20 ⁇ m for example Avicel PH 105® from Lehmann and Voss, Hamburg
• an optical brightener of the formula (A) (as 25% liquid setting).
• This dispersion can be incorporated directly into the paper coating slip. An excellent brightening effect with a comparatively high light fastness is obtained.
• cellulose powder having an average particle size of 30 ⁇ m for example Arbocel BE 600 / 30® from Rettenmaier, Holzmühle via Ellwangen
• a brightener of the formula (B) in the form of a 13% liquid setting
• This dispersion can be incorporated directly into the paper coating slip.
• the paper coating obtained shows excellent lightfastness.
• cellulose powder for example Avicel PH 105® from Lehmann and Voss
• a brightener of the formula (C) are added (as 25% liquid setting).
• cellulose powder having an average particle size of 30 ⁇ m for example Technocel 30® from the Cellulose Filler Factory, Mönchengladbach, are dispersed in 750 parts of water, and 3.5 parts of a brightener of the formula (D) (as powder setting with 78% pure brightener).
• the dispersion obtained can be incorporated directly into coating slips. It also gives excellent results.
• cellulose powder with an average particle size of 30 ⁇ m for example Arbocel BE 600/30 from Rettenmaier
• a brightener of the formula (E) (as powder setting with 83% active ingredient content).
• the dispersion obtained is also extremely suitable for incorporation into coating slips.
• the coating color from Example 6 is lightened by adding 1.6 parts of the brightener of the formula (A) according to Example 1, based on pigment.
• a coating color 60 parts of China Clay SPS 30 parts calcium carbonate 10 parts of cellulose powder (Arbocel BE 600/30 from Rettenmaier) 20 parts of an anionic plastic dispersion of a copolymer containing acrylic acid ester with a solids content of approx. 50% (eg Acronal S 320 D from BASF) 0.5 parts polyvinyl alcohol 5 parts of polyacrylate binder (e.g.
• Example 10a 0.4 parts of brightener of the formula (A)
• Example 11a 0.6 part of brightener of the formula (A)
• Example 12a 0.8 parts of brightener of the formula (A)
• Example 13a 1.6 parts of brightener of the formula (A).
• the coating slips of Examples 7a-13a are applied to paper with the aid of a hand-held squeegee or a test coater and dried at 80.degree.
• Table 1 shows the CIE whiteness of the papers after production and after exposure (1 week in daylight).
• Papers which have been produced by the process according to the invention have both an increased degree of whiteness and a significantly improved light fastness even with a reduced brightener concentration.
• Table 1 Brightening (% -related to pigment) CIE whiteness after manufacture CIE whiteness after exposure Whiteness drop due to exposure
• Example 8a 1.6% brightener (A) 92.5 76.5 -16.0
• a coating color is prepared analogously to Example 7a, part of the chalk being replaced by an equal amount of microcrystalline cellulose (Avicel PH 105), to which 2% of the brightener of the formula (A) or (B) has been fixed beforehand.
• the coated papers were examined for their whiteness after production and after exposure (Table 2). Papers which have been produced by the process according to the invention have both an increased degree of whiteness and improved light fastness.
• Table 2 example Cellulose powder addition to the coating color Brightening addition to the coating color CIE whiteness after manufacture CIE whiteness after exposure Whiteness drop due to exposure 15a - 2% (A) 96.9 86.8 -10.1 16a 5% Avicel PH 105 2% (A) 105.7 95.8 -9.9 17a 10% Avicel PH 105 2% (A) 107.5 100.8 -6.7 18a 20% Avicel PH 105 2% (A) 120.0 113.0 -7.0 19a - 2 B) 99.3 94.7 -4.6 20a 5% Avicel PH 105 2 B) 105.2 101.1 -4.1 21a 10% Avicel PH 105 2 B) 107.2 103.4 -3.8 22a 20% Avicel PH 105 2 B) 112.2 109.2 -3.0
• microcrystalline cellulose with an average particle size of 20 ⁇ m for example Avicel PH 105® from Lehmann and Voss, Hamburg
• chalk slurry for example Omyalite 90® from Omya with a solids content of 72%)
• an optical brightener of the formula (A) as 25% liquid setting
• This dispersion has a solids content of 72 and can be incorporated directly into the paper coating slip. An excellent brightening effect with a comparatively high light fastness is obtained.
• 116 parts of cellulose powder having an average particle size of 30 ⁇ m are dispersed in 900 parts of chalk slurry according to Example 1 and mixed with 9 parts of a brightener of the formula (B) (in the form of a 13% liquid setting) and with 80 parts of water.
• This dispersion with a solids content of 70% can be incorporated directly into the paper coating slip.
• the paper coating obtained shows excellent lightfastness.
• cellulose powder for example Avicel PH 105® from Lehmann and Voss
• a brightener of the formula (C) (as 25% liquid setting).
• cellulose powder having an average particle size of 30 ⁇ m for example Technocel 30® from the Cellulose Filler Factory, Mönchengladbach, are dispersed in 900 parts of chalk slurry according to Example 1 and 1.2 parts of a brightener of the formula (D) (as powder setting with 78% pure brightener) and with 60 parts of water.
• the dispersion obtained can be incorporated directly into coating slips. It also gives excellent results.
• This dispersion can be incorporated directly into coating slips.
• the paper coating obtained shows a good brightening effect and a comparatively high light fastness.
• cellulose powder having an average particle size of 30 ⁇ m for example Arbocel BE 600 / 30® from Rettenmaier, Holzmühle above Ellwangen
• kaolin slurry for example Clay SPS®
• a brightener of the formula (A) as 25% liquid setting
• This dispersion can be incorporated directly into the paper coating slip. An excellent brightening effect with a comparatively high light fastness is obtained.
• the coating color from Example 7 is lightened by adding 1.6 parts of the brightener of the formula (A) according to Example 1b, based on pigment.
• the coating slips of Examples 7b-9b are applied to paper with the aid of a hand-held squeegee or an experimental coating system and dried at 80.degree.
• Table 3 shows the CIE whiteness of the papers after production and after exposure (1 week in daylight).
• Papers which were produced by the process according to the invention have both an increased degree of whiteness and a significantly improved light fastness even when the brightener concentration is reduced.
• Table 3 Brightening (% -related to pigment) CIE whiteness after manufacture CIE whiteness after exposure Whiteness drop due to exposure Example 7b - 72.0 72.4 - Example 8b 1.6% brightener (A) 92.5 76.5 -16.0

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• 1990
  • 1990-07-05 NO NO90903004A patent/NO903004L/no unknown
  • 1990-07-07 EP EP90113025A patent/EP0409028A1/fr not_active Withdrawn
  • 1990-07-19 CA CA002021559A patent/CA2021559A1/fr not_active Abandoned
  • 1990-07-19 FI FI903648A patent/FI903648A0/fi not_active Application Discontinuation
  • 1990-07-20 JP JP2190893A patent/JPH0359192A/ja active Pending

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