CA2021559A1 - Process for the whitening of paper coating compositions and also whitener preparations for this process - Google Patents
Process for the whitening of paper coating compositions and also whitener preparations for this processInfo
- Publication number
- CA2021559A1 CA2021559A1 CA002021559A CA2021559A CA2021559A1 CA 2021559 A1 CA2021559 A1 CA 2021559A1 CA 002021559 A CA002021559 A CA 002021559A CA 2021559 A CA2021559 A CA 2021559A CA 2021559 A1 CA2021559 A1 CA 2021559A1
- Authority
- CA
- Canada
- Prior art keywords
- whitener
- parts
- cellulose powder
- optical brightener
- amino
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
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
Abstract
Process for the whitening of paper coating compositions and also whitener preparations for this Process A b s t r a c t Combinations of cellulose powder (average par-ticle size below 50 µm) and anionic cellulose optical brighteners and also optionally coating pigments are eminently suitable for the whitening of paper coating compositions. Besides an excellent optical brightening effect, the resulting papers have an improved light fastness.
Description
2~2~ ~5~
The preparation of coated papers and cardboard employs, to a very large extent, aqueous coating composi~
tions which, besides the customary white pigments, in particular china clay and calcium carbonate, contain synthetic dispersions as binders.
As a rule, the optical brightening of these coating compositions is achieved by the use of substan-tive snionic whiteners, for example, alkali metal salts ~ -of bistriazinylaminostilbenedisulphonic acids. However, these whiteners have only very unsatisfactory optical - brightening effects and a very low greyness limit (white- ~`
ner concentration at which further addition of the whitener gives no increase, or even a decrease, in the degree of whiteness). Furthermore, the abovementioned types of whitener have a very low light fastness in coating compositions of that kind.
It i8 generally known to partially eliminate the abovementioned difficulties in two different ways:
1. By adding to the coating composition minor propor-tions of hydrophilic cobinders to which the whiteners can become attached. Cobinders of this type are for example:
starch, casein, carboxymethylcellulose, alginates, polyvinyl alcohol, polyacrylate, and melamine- or ureaformaldehyde resins (cf. ~Das Papier" 36 (1982), 66).
2. By the use of specific water-soluble whiteners which contain hydrophilic carriers. Carriers of this type may be, for example, the polyglycols (cf. DE-A-3,502,038 and EP-A-43,790). -~ ;
Le A 27 045 - 1 - ~
... .. . . . . , ~ . .. -2 0 2 ~ 9 : ~
Although the brightening effect can be si~nifi-cantly improved by these methods, the water sensitivity of the coated papers is at the same time increased, which causes difficulties in certain printing processes and on use of the coated papers. Moreover, the use of these additives in the coating composition often causes rheo-logical problems on modern fast-running coating equip-ment.
Furthermore, it is known (cf. DE-A-3,112,435) to attach water-soluble whiteners to certain plastics ~uch as, for example, urea resins or methylol resins and to add these optically brightened plastics in the form of a dispersion to the paper coating composition. However, these proposals have hitherto not become established owing to their excessively high cost or owing to rheo-logical difficulties.
Surprisingly, it has now been found that composi-tions for paper coating can be optically brightened using the abovementioned whiteners and without the abovemen-tioned disadvantages if optical brighteners, water-dispersible cellulose powder and optionally coating pigments or an optical brightener product composed essentially of cellulose powder coated with optical brightener and also optionally a coating pigment are added to the coating compositions in any desired order, the cellulose powder having in every case an average particle ~ize of less than 50 ~m.
An example of a suitable cellulose powder is . .
microcrystalline cellulose which is obtained from cotton ~ -linters or wood cellulose usually by a combination of ~--' .
: .
~e ~ 27 0~5 - 2 -20;2~59 hydrolytic degradation and mechanical wet crushing of the particles and also by subsequent spray drying, the microcrystalline cellulose no longer having any kind of fibre structure (cf. "Umschau" 77 (1977), 312).
Also suitable are cellulose powders which have been prepared by dry grinding of customary wood cellulose and which likewise virtually no longer have any fibre structure.
Particularly suitable are cellulose powders which have a high crystallinity, above 30%, preferably above 50%, and also have a diminished hydrophily and are dispersible in water up to a solids content of about 25%.
Also suitable are water-insoluble substituted types of cellulose, for example cellulose ethers such as methyl- or ethyl-cellulose, or cellulose esters ~uch as cellulose acetate, cellulose acetobutyrate and cellulose acetopropionate.
Preference is given to cellulose powders of the type which have particle sizes of 25 - 35, in particular about 30 ~m.
The coating composition can be prepared by incor-porating up to 20% of cellulose powder (relative to the total amount of pigments added).
Suitable cellulose whiteners which are to be used according to the inven~ion are bistriazolylstilbenedi-sulphonic acid, bisstilbenedisulphonic acid and in particular bistriazinyl-aminostilbenedisulphonic acid.
Examples of particularly suitable optical brighteners are those of the formula Le A 2? Q~5 - 3 -: :~ . -: - . . . . .. .
~ 2021~59 X H=CH ~ N ~ 1 ~==N N==~ (I) :;:.
in which X1 is amino, methylamino, ethylamino, dimethylamino, diethylamino, 2-hydroxyethylamino, 3-hydroxy-propylamino, di-(2-hydroxyethyl)amino, di-(2 hydroxypropyl)amino, 2-sulphoethylamino, morpho-lino, anilino, chloroanilino, sulphoanilino, methylanilino or disulphoanilino and X2 i8 hydroxy, methoxy, ethoxy, methoxyethoxy, chlorine or Xl, and also those of the formula k N ~ H=CH ~ ~NN ~ (II) in which X3 and X4 are hydrogen, methyl, ethyl, phenyl or ``
lS sulphophenyl, and also of the formula .;
X5 ~ H-CH ~ H=CH ~ 5 (III) ~`
S03Z S03Z ;``
~. - . .~
, ~ ' ~"`.'.`'";.'',~",'.,"".
'.`.'~
.:
::
,.:: .:, . - .- -Le A 27 a4s - 4 : :
::
^ 202~9 in which X5 iS hydrogen, methyl, ethyl, methoxy, ethoxy, chlorine or sulpho and in every case -Z is an alkali metal ion, amine ion or ammonium ion.
The optical brighteners are preferably present in the form of their sodium salts.
Suitable coating pigments are clay, kaolin, silica, aluminium oxide, aluminium silicate, talc and in particular chalk. These pigments are preferably used in the form of an aqueous slurry. ~ -The optical brightener preparations according to the invention can be simply prepared by dispersing suitable cellulose powders in water and adding customary anionic optical brighteners for paper or textiles.
Surprisingly, even at low temperature, the optical brightener becomes attached to the dispersed cellulose powder without difficulty, and the optically ~ -brightened cellulose powder shows no greyness even at relatively high levels of optical brightener addition.
If the whitener preparations according to the ~ ;~
invention contain customary white pigments, the prepara~
tion can be simply carried out by admixing suitable -~
cellulose powders and also customaxy anionic optical brighteners for paper or textiles, if necessary together with a little water, with commercially available filler slurries with stirring or else by admixing even during the dispersion and grinding opexations which take place during the preparation of the filler slurries.
The resulting dispersions may contain customary :~ :"'' -'.
:::' '~
~ . :..
Le A 27 045 - 5 -.~:
~- 2021~
anionic or non-ionic dispersants, for example salts of polycarboxylic acids, sulphated or unsulphated higher alkanol ethers or alkylphenol polyglycol ethers, lignin-sulphonates, ~arboxymethylcellulose, hydroxyethylcellu-lose and the like.
Surprisingly, despite its high hydrophily, the cellulose powder additive causes only a slight inçrease in viscosity of the filler slurries, which may conse-quently contain high solids concentratione of up to over 70%.
The cellulose powders may be used in the whitener preparations according to the invention in any desired ratio relative to the white pigment, and the viscosity can be ad~usted to a desired value by simultaneous addition of water. Preference is given to a cellulose powder content of up to 20% relative to white pigment, and high pigment concentrations in the slurry can be ~elected without causing any significant increase in viscosity.
The coating composition may be prepared by incorporating up to 20% of cellulose powder (relative to the total amount of added-pigment) into the coating -~
composition.
The amount of optical brightener added is governed by the amount of cellulose powder which is present in the whitener preparations according to the invention. Gener-ally, it is possible to use amounts of up to 10% of active ingredient relative to cellulose powder. Larger amounts do not have any further effect since the greyness limit i~ exceeded. Preference is given to the use of ,': ~ : '~
`: :
Le A 27 045 - 6 -~ . .
^` 2021~9 amounts of from 2.5 to 7% relative to dry cellulose powder. In this addition, it is advantageous to use the optical brightener in the form of an approximately 10 to 30% strength, preferably 15 to 25% strength commercially available liquid formulation.
The optical brightener preparations which are to be used according to the invention are novel and are therefore likewise a sub~ect of the present invention.
The optical brightener preparation may be added in the form of a dispersion to the coating composition immediately after this has been prepared and may be processed on customary coating machines.
The aqueous optical brightener products may also be processed to form powder compositions by conventional process steps such as filtration and drying.
In another variant according to the invention, the cellulose powder and the optical brightener are added separately during the preparation of the coating composi-tion, the optical brightener immediately becoming attached to the cellulose powder which has been employed.
The amount of optical brightener or of optical brightener preparation which is used is governed by the desired optical brightening effect. Generally, from 0.01 to 0.5~ by weight of the pure active ingredient of the optical brightener (relative to the pigment of the paper coating composition which i8 to be brightened) is suffi-cient. A particular advantage is that, depending on the constituents of the coating composition, the achievable greyness limit (up to which further addition of optical brightener is still effective) is exceptionally high.
Le A 27 045 - 7 -2 ~ 2 1 ~ ~ ~
It is particularly advantageous to use the optical brightener in the form of an approximately 10 ~
30% strength, preferably 15 - 25% strength, commercially available liquid forming (% = percent by weight).
Example Ia 250 parts of microcrystalline cellulose having an average particle size of 20 ~m, for example Avicel PH 105 from Lehman and Voss, Hamburg) are dispersed in 750 parts of water and to this dispersion are added 25 parts of an -optical brightener of the formula (A) ; ;;-H H ~ :
NaO35~3N ~03Na ,, . ~. ,.:, N `~ NH ~ CH-C} ~ 3 NH ~ (A) (HOCH2CH2)2N S03Na 503Na N(cH2cH2oH)2 (in the form of a 25% strength liquid formulation). -~-This dispersion can be incorporated directly into the paper coating composition. This gives an excellent optical brightening effect with comparatively high light fastness.
Example 2a 250 parts of cellulose powder having an average particle size of 30 ~m (for example Arbocel BE 600/30 from Rettenmaier, Holzm~hle ~ber Ellwangen) are dispersed in 750 parts of water and to this dispersion are added 25 parts of an optical brightener of the formula (B) Le A 27 045 - 8 -n ' ' ~ . . ~ , ~21~3~ ;
~CH=CH~3~J3 (B) S03Na S03Na (in the form of a 13% strength liquid formulation).
This dispersion can be incorporated directl~ into the paper coating composition. The resulting paper coating has an excellent light fastness.
Example 3a 250 parts of cellulose powder (for example Avicel PH 105 from Lehmann and Voss) are dispersed in 750 parts of water and to this dispersion are added 50 parts of an opt~cal brightener of the formula (C) O~NH~H=CH~}NH~N (C) ( HocH2cH2 ) 2N S03Na S03Na N ( CH2CH20H ~
(in the form of a 25% strength liquid formulation).
After incorporation in coating compositions, this gives a good optical brightening effect and a compara-tively high light fastness in the paper coating.
Example 4a 250 parts of cellulose powder having an average particle size of 30 ~m (for example Technocel 30~ from Cellulose-F~llstoff-Fabrik, Nonchengladbach) are dispersed in 750 parts of water and to this disper~ion are added 3.5 parts of an optical brightener of the formula (D) Le A 27 045 - 9 -~` 2021~9 ..... .
, . -H H --~
N ~NH ~ H=CH ~ NH ~ N (D) /---N S03Na 503Na N ~
(in the form of a powder formulation containing ~8% of pure optical brightener).
The resulting di~persion can be incorporated directly into coating compositions. It likewise gives excellent results.
Example 5a 250 part~ of cellulose powder having an average ~:
particle size of 30 ~m (for example Arbocel BE 600/30 10from Rettenmaier) are dispersed in 750 parts of water and :~
to this dispersion are added 5 parts of an optical brightener of the formula (E) H H
N N ~ (E) NH ~ H=CH ~ NH ~ ~ N ::: :
~ ~ ~ N ~ :
H3C-N 503Na 503Na N-CH~ ;:
(in the form of a powder formulation containing 83~ of active ingredient). : :~
The resulting dispersion is likewise eminently suitable for incorporation in coating compositions. ~:
Example 6a 250 parts of pulverulent cellulose acetobutyrate .'..~:
:: . ~ . : -:: :
'~;: -~ ~ ..
Le A 27 045 - 10 -~.. .
` 2 ~ 2 1 5 ~ 9 : : ~
are dispersed in 750 parts of water and to this dispersion are added 25 parts of a 25% strength liquid forming of the optical brightener (A). The dispersion can be incor~
porated directly into the paper coating composition. This 5 gives an excellent brightening effect with comparatively good light fastness.
Example 7a Stirred mixing of ~-60 parts of china clay SPS
40 parts of calcium carbonate 20 parts of an anionic synthetic dispersion of an acryloyl-ester-containing copolymer having a solids content of about 50%
(for example Acronal S 320 D from BASF) 0.5 parts of polyvinyl alcohol parts of polyacryloyl ester as co-binder (40%
strength) (for example Acrosol 40 D from BASF) and 80 parts of water is used to prepare a non-brightened paper coating compo-sition having a solids content of about 55%, whose pH is ad~usted to 9 using aqueous sodium hydroxide solutLon.
Example 8a (comparison, not according to the invention) The coating composition from Example 6 is opti-cally brightened by adding 1.6 parts of the optical brightener of the formula (A) according to Example 1, relative to pigment.
- :.
~: :
Le A 27 045 - 11 --'~ 2 0 2 1 ~ ~ 9 Example 9a Stirred mixing of 60 parts of china clay SPS
30 parts of calcium carbonate 40 parts of the cellulose dispersion from Example .
1 containing 25% of optical brightener 20 parts of an anionic synthetic dispersion of an acryloyl-ester-containing copolymer having a solids content of about 50%
(for example Acronal S 320 D~ from :~
BASF) 0.5 parts of polyvinyl alcohol -~
5 parts of polyacrylate binder ~40% strength) (for example Acrosol 40 D from BASF) and 50 parts of water :~
is used to prepare a paper coating composition having a ~ :
solids content of about 55% whose pH is ad~usted to 9 :. :~
using aqueous sodium hydroxide solution.
Examples lOa - 13a .
To a coating composition composed of 60 parts of china clays SPS
30 parts of calcium carbonate ~:;:
1~ psrts of cellulose powder (Arboc~l BE 600/30 ;~
from Rettenmaier) 20 part~ of an anionic synthetic dispersion of an ~ -:.
acryloyl-ester-containing copolymer ~ ~:
having a solids content of about 50 (forexample Acronal S 320 D from BASF) -~: , . .
~':,~' :, ,~
~e A 27 045 - 12 -: .:: . :
:
2021~9 0.5 parts of polyvinyl alcohol 5 parts of polyacrylate binder (for example Acrosol 40 D from BASF) and 80 parts of water are added the following amounts of the optical brightener ~ ~-for paper, according to formula (A) of Example la, and the pH i6 ad~usted to 9 using aqueous sodium hydroxide solution:
Example lOa: 0.4 parts of optical brightener of the formula (A) Example lla: 0.6 parts of optical brightener of the formula (A) Example 12a: 0.8 parts of optical brightener of the formula (A) Example 13a: 1.6 parts of optical brightener of the formula (A).
Example 14a The coated paper is prepared by applying the coating compositions from Examples 7a - 13a to paper using a doctor blade or test coating equipment and drying the product at 80C. ;
Table 1 shows the CIE whiteness of the papers after preparation and also after exposure to light (1 week in daylight).
Papers which have been prepared by the process according to the invention have, even at reduced optical brightener concentration, not only a higher degree of whitenes~ but also a significantly improved light fastness.
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~- 2 ~ 5 9 Examples 15a - 22a .
A coating composition is prepared similarly to Example 7a, but one part of the chalk is replaced by the same amount of microcrystalline cellulose ~Avicel PH 105) to which 2% in each case of the optical brightener of the formula (A) or (B) has previously been fixed.
The degree of whiteness of the coated papers was examined after preparation and also after exposure to light (Table 2). Papers which have been prepared by the proces~ according to the invention have not only a higher - degree of whiteness but also an improved light fastness.
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. . -~-- 2021~9 :, Example lb ~, 90 parts of microcrystalline cellulose having an 3 average particle size of 20 ~m (for example Avicel PH
1050 from Lehman and Voss, Hamburg) are dispersed in 900 , 5 parts of chalk slurry (for example Omyalite 90~ from ,`~ Omya, having a solids content of 72%) and to this disper-'~ sion are added 9 parts of an optical brightener of the formula (A) ~
H H
Na03S ~ N ~ S03Na N~NI~H- CH~NH~
( HOCH2CH2 ) 2N S03Na S03Na N(CH2CH20H) 2 (in the form of a 25% strength liquid formulation) and I also 33 parts of water.
This dispersion has a solids content of 72% and can be incorporated directly into the paper coating composition. This gives an excellent optical brightening effect with comparatively high light fastness.
I ~ Example 2b ! ~ 116 par~s of cellulose powder having an average particle size of 30 ym (for example Arbocel BE 600/30 from Rettenmaier, Holzmuhle Uber Ellwangen) are dispersed in 900 parts of chalk slurry according to Example 1 and to this dispersion are added 9 parts of an optical brightener of the formula (B) . : .-.: :
_e A 27 045 - 17 -- 2Q~ 9 N~H=CH~3~3 (B) 503Na S03Na (in the form of a 13% strength liquid formulation) and also 80 parts of water.
This dispersion having a solids content of 70%
can be incorporated directly into the paper coating composition. The resulting paper coating has an excellent light fastness. ~
Example 3b ;
90 parts of cellulose powder (for example Avicel PH 105 from Lehmann and Voss) are dispersed in 900 parts of chalk slurry according to Example 1 and to this di~persion are added 18 parts of an optical brightener of the formula (C) I~CH=CH~N~;> ( C ) )=N N=<
(HocH2cH2)2N SQ3Na S03Na N(CH2CH20H)3 '''~
lS (in the form of a 25% strength liquid formulation).
After incorporation in coating compositions, this gives a good optical brightening effect and a compara~
tively high light fastness in the paper coating. ~ ~ -Example 4b 90 parts of cellulose powder having an average particle size of 30 ~m (for example Technocel 30 from Cellulose-FUll~toff-Fabrik, Monchengladbach are dispersed , ~ .,, :: .
, Le A 27 045 - 18 --~` 2021~9 in 900 parts of chalk slurry according to Example 1 and to this dispersion are added 1.2 parts of an optical brightener of the formula (D) H H
N ~NH~:H-CH~NH~ ~N , (D) ~,~> S03Na 53Na N~ ~:
:: ':' (in the form of a powder formulation containing 78% of ~-pure optical brightener) and also 60 parts of water.
The resulting dispersion can be incorporated directly into coating compositions. It likewise gives excellent results.
Example 5 90 parts of cellulose powder having an average psrticle size of 30 ~m (for example Arbocel BE 600/30 from Rettenmaier) are dispersed in 900 parts of chalk slurry according to Example 1 and to this dispersion are added 1.75 parts of an optical brightenar of the formula (E) H - H
N ~NH~CH~CH~}NH~ N
H3C -N S03Na S03N~ N - CH3 ~ .r.. ..
This di~persion can be incorporated directly into a coating composition. The resulting paper coating has a good optical brightening effect and a comparatively high light fastness.
. . .
Le A 27 045 - 19 -2021.559 Example 6b 90 parts of cellulose powder having an average particle size of 30 ~m (for example Arbocel BE 600/30 from Rettenmaier, HolzmUhle uber Ellwangen) are dispersed in 900 parts of kaolin slurry (for example clay SPS~) and to this dispersion are added 9 parts of an optical brightener of the formula (A) (in the form of a 25%
strength liquid formulation) and also 250 parts of water.
This dispersion can be incorporated directly into the paper coating composition. This gives an excellent - optical brightening effect with a comparatively high light fastness.
Example 7b Stirred mixing of 60 parts of china clay SPS~
40 parts of calcium carbonate (corresponding to 55 parts of chalk slurry according to Example 1) 20 parts of an anionic synthetic dispersion of an acryloyl-ester-containing copolymer having a solids content of about 50%
(for example Acronal S 320 D from BASF) 0.5 parts of polyvinyl alcohol 5 parts of polyacryloyl esters as co-binder (40 strength) (for example Acrosol 40 D~
from BASF) and 65 parts of water Le A 27 045 - 20 -2 0 '~
is used to prepare a non-brightened paper coating compo-sition having a solids content of about 55%, whose pH is ad~usted to 9 using aqueous sodium hydroxide solution.
Example 8b (comparison, not according to the invention) The coating composition from Example 7 is opti-cally brightened by adding 1.6 parts of the optical brightener of the formula (A) according to Example lb, -~
relative to pigment.
Example 9b Stirred mixing of 60 parts of china clay SPS~
55 parts of the chalk slurry from Example containing 72% of optical brightener 20 parts of an anionic synthetic dispersion of an acryloyl-ester-containing copolymer having a solids content of about 50%
(forexample Acronal S 320 D~ from BASF) 0.5 parts of polyvinyl alcohol -5 parts of polyacrylate binder (40% strength) (for example Acrosol 40 D~ from BASF) and 65 parts of water is used to prepare a paper coating composition having a solids content of about 55~ whose pH i8 ad~usted to 9 using aqueous sodium hydroxide solution.
Exam~le lOb The coated paper is prepared by applying to paper the coating compositions from Examples 7b - 9b using a doctor blade or test coating equipment and the product is dried at 80C.
Le A 27 045 - 21 - -.'-~' :' ~ 2~21~9 Table 3 shows the CIE whiteness of the papers after preparation and also after exposure to light (1 week in daylight).
Papers which have been prepared by the process S according to the invention have, even at reduced optical ;~
brightener concentration, not only a higher degree of whiteness but also a significantly improved light fastness.
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The preparation of coated papers and cardboard employs, to a very large extent, aqueous coating composi~
tions which, besides the customary white pigments, in particular china clay and calcium carbonate, contain synthetic dispersions as binders.
As a rule, the optical brightening of these coating compositions is achieved by the use of substan-tive snionic whiteners, for example, alkali metal salts ~ -of bistriazinylaminostilbenedisulphonic acids. However, these whiteners have only very unsatisfactory optical - brightening effects and a very low greyness limit (white- ~`
ner concentration at which further addition of the whitener gives no increase, or even a decrease, in the degree of whiteness). Furthermore, the abovementioned types of whitener have a very low light fastness in coating compositions of that kind.
It i8 generally known to partially eliminate the abovementioned difficulties in two different ways:
1. By adding to the coating composition minor propor-tions of hydrophilic cobinders to which the whiteners can become attached. Cobinders of this type are for example:
starch, casein, carboxymethylcellulose, alginates, polyvinyl alcohol, polyacrylate, and melamine- or ureaformaldehyde resins (cf. ~Das Papier" 36 (1982), 66).
2. By the use of specific water-soluble whiteners which contain hydrophilic carriers. Carriers of this type may be, for example, the polyglycols (cf. DE-A-3,502,038 and EP-A-43,790). -~ ;
Le A 27 045 - 1 - ~
... .. . . . . , ~ . .. -2 0 2 ~ 9 : ~
Although the brightening effect can be si~nifi-cantly improved by these methods, the water sensitivity of the coated papers is at the same time increased, which causes difficulties in certain printing processes and on use of the coated papers. Moreover, the use of these additives in the coating composition often causes rheo-logical problems on modern fast-running coating equip-ment.
Furthermore, it is known (cf. DE-A-3,112,435) to attach water-soluble whiteners to certain plastics ~uch as, for example, urea resins or methylol resins and to add these optically brightened plastics in the form of a dispersion to the paper coating composition. However, these proposals have hitherto not become established owing to their excessively high cost or owing to rheo-logical difficulties.
Surprisingly, it has now been found that composi-tions for paper coating can be optically brightened using the abovementioned whiteners and without the abovemen-tioned disadvantages if optical brighteners, water-dispersible cellulose powder and optionally coating pigments or an optical brightener product composed essentially of cellulose powder coated with optical brightener and also optionally a coating pigment are added to the coating compositions in any desired order, the cellulose powder having in every case an average particle ~ize of less than 50 ~m.
An example of a suitable cellulose powder is . .
microcrystalline cellulose which is obtained from cotton ~ -linters or wood cellulose usually by a combination of ~--' .
: .
~e ~ 27 0~5 - 2 -20;2~59 hydrolytic degradation and mechanical wet crushing of the particles and also by subsequent spray drying, the microcrystalline cellulose no longer having any kind of fibre structure (cf. "Umschau" 77 (1977), 312).
Also suitable are cellulose powders which have been prepared by dry grinding of customary wood cellulose and which likewise virtually no longer have any fibre structure.
Particularly suitable are cellulose powders which have a high crystallinity, above 30%, preferably above 50%, and also have a diminished hydrophily and are dispersible in water up to a solids content of about 25%.
Also suitable are water-insoluble substituted types of cellulose, for example cellulose ethers such as methyl- or ethyl-cellulose, or cellulose esters ~uch as cellulose acetate, cellulose acetobutyrate and cellulose acetopropionate.
Preference is given to cellulose powders of the type which have particle sizes of 25 - 35, in particular about 30 ~m.
The coating composition can be prepared by incor-porating up to 20% of cellulose powder (relative to the total amount of pigments added).
Suitable cellulose whiteners which are to be used according to the inven~ion are bistriazolylstilbenedi-sulphonic acid, bisstilbenedisulphonic acid and in particular bistriazinyl-aminostilbenedisulphonic acid.
Examples of particularly suitable optical brighteners are those of the formula Le A 2? Q~5 - 3 -: :~ . -: - . . . . .. .
~ 2021~59 X H=CH ~ N ~ 1 ~==N N==~ (I) :;:.
in which X1 is amino, methylamino, ethylamino, dimethylamino, diethylamino, 2-hydroxyethylamino, 3-hydroxy-propylamino, di-(2-hydroxyethyl)amino, di-(2 hydroxypropyl)amino, 2-sulphoethylamino, morpho-lino, anilino, chloroanilino, sulphoanilino, methylanilino or disulphoanilino and X2 i8 hydroxy, methoxy, ethoxy, methoxyethoxy, chlorine or Xl, and also those of the formula k N ~ H=CH ~ ~NN ~ (II) in which X3 and X4 are hydrogen, methyl, ethyl, phenyl or ``
lS sulphophenyl, and also of the formula .;
X5 ~ H-CH ~ H=CH ~ 5 (III) ~`
S03Z S03Z ;``
~. - . .~
, ~ ' ~"`.'.`'";.'',~",'.,"".
'.`.'~
.:
::
,.:: .:, . - .- -Le A 27 a4s - 4 : :
::
^ 202~9 in which X5 iS hydrogen, methyl, ethyl, methoxy, ethoxy, chlorine or sulpho and in every case -Z is an alkali metal ion, amine ion or ammonium ion.
The optical brighteners are preferably present in the form of their sodium salts.
Suitable coating pigments are clay, kaolin, silica, aluminium oxide, aluminium silicate, talc and in particular chalk. These pigments are preferably used in the form of an aqueous slurry. ~ -The optical brightener preparations according to the invention can be simply prepared by dispersing suitable cellulose powders in water and adding customary anionic optical brighteners for paper or textiles.
Surprisingly, even at low temperature, the optical brightener becomes attached to the dispersed cellulose powder without difficulty, and the optically ~ -brightened cellulose powder shows no greyness even at relatively high levels of optical brightener addition.
If the whitener preparations according to the ~ ;~
invention contain customary white pigments, the prepara~
tion can be simply carried out by admixing suitable -~
cellulose powders and also customaxy anionic optical brighteners for paper or textiles, if necessary together with a little water, with commercially available filler slurries with stirring or else by admixing even during the dispersion and grinding opexations which take place during the preparation of the filler slurries.
The resulting dispersions may contain customary :~ :"'' -'.
:::' '~
~ . :..
Le A 27 045 - 5 -.~:
~- 2021~
anionic or non-ionic dispersants, for example salts of polycarboxylic acids, sulphated or unsulphated higher alkanol ethers or alkylphenol polyglycol ethers, lignin-sulphonates, ~arboxymethylcellulose, hydroxyethylcellu-lose and the like.
Surprisingly, despite its high hydrophily, the cellulose powder additive causes only a slight inçrease in viscosity of the filler slurries, which may conse-quently contain high solids concentratione of up to over 70%.
The cellulose powders may be used in the whitener preparations according to the invention in any desired ratio relative to the white pigment, and the viscosity can be ad~usted to a desired value by simultaneous addition of water. Preference is given to a cellulose powder content of up to 20% relative to white pigment, and high pigment concentrations in the slurry can be ~elected without causing any significant increase in viscosity.
The coating composition may be prepared by incorporating up to 20% of cellulose powder (relative to the total amount of added-pigment) into the coating -~
composition.
The amount of optical brightener added is governed by the amount of cellulose powder which is present in the whitener preparations according to the invention. Gener-ally, it is possible to use amounts of up to 10% of active ingredient relative to cellulose powder. Larger amounts do not have any further effect since the greyness limit i~ exceeded. Preference is given to the use of ,': ~ : '~
`: :
Le A 27 045 - 6 -~ . .
^` 2021~9 amounts of from 2.5 to 7% relative to dry cellulose powder. In this addition, it is advantageous to use the optical brightener in the form of an approximately 10 to 30% strength, preferably 15 to 25% strength commercially available liquid formulation.
The optical brightener preparations which are to be used according to the invention are novel and are therefore likewise a sub~ect of the present invention.
The optical brightener preparation may be added in the form of a dispersion to the coating composition immediately after this has been prepared and may be processed on customary coating machines.
The aqueous optical brightener products may also be processed to form powder compositions by conventional process steps such as filtration and drying.
In another variant according to the invention, the cellulose powder and the optical brightener are added separately during the preparation of the coating composi-tion, the optical brightener immediately becoming attached to the cellulose powder which has been employed.
The amount of optical brightener or of optical brightener preparation which is used is governed by the desired optical brightening effect. Generally, from 0.01 to 0.5~ by weight of the pure active ingredient of the optical brightener (relative to the pigment of the paper coating composition which i8 to be brightened) is suffi-cient. A particular advantage is that, depending on the constituents of the coating composition, the achievable greyness limit (up to which further addition of optical brightener is still effective) is exceptionally high.
Le A 27 045 - 7 -2 ~ 2 1 ~ ~ ~
It is particularly advantageous to use the optical brightener in the form of an approximately 10 ~
30% strength, preferably 15 - 25% strength, commercially available liquid forming (% = percent by weight).
Example Ia 250 parts of microcrystalline cellulose having an average particle size of 20 ~m, for example Avicel PH 105 from Lehman and Voss, Hamburg) are dispersed in 750 parts of water and to this dispersion are added 25 parts of an -optical brightener of the formula (A) ; ;;-H H ~ :
NaO35~3N ~03Na ,, . ~. ,.:, N `~ NH ~ CH-C} ~ 3 NH ~ (A) (HOCH2CH2)2N S03Na 503Na N(cH2cH2oH)2 (in the form of a 25% strength liquid formulation). -~-This dispersion can be incorporated directly into the paper coating composition. This gives an excellent optical brightening effect with comparatively high light fastness.
Example 2a 250 parts of cellulose powder having an average particle size of 30 ~m (for example Arbocel BE 600/30 from Rettenmaier, Holzm~hle ~ber Ellwangen) are dispersed in 750 parts of water and to this dispersion are added 25 parts of an optical brightener of the formula (B) Le A 27 045 - 8 -n ' ' ~ . . ~ , ~21~3~ ;
~CH=CH~3~J3 (B) S03Na S03Na (in the form of a 13% strength liquid formulation).
This dispersion can be incorporated directl~ into the paper coating composition. The resulting paper coating has an excellent light fastness.
Example 3a 250 parts of cellulose powder (for example Avicel PH 105 from Lehmann and Voss) are dispersed in 750 parts of water and to this dispersion are added 50 parts of an opt~cal brightener of the formula (C) O~NH~H=CH~}NH~N (C) ( HocH2cH2 ) 2N S03Na S03Na N ( CH2CH20H ~
(in the form of a 25% strength liquid formulation).
After incorporation in coating compositions, this gives a good optical brightening effect and a compara-tively high light fastness in the paper coating.
Example 4a 250 parts of cellulose powder having an average particle size of 30 ~m (for example Technocel 30~ from Cellulose-F~llstoff-Fabrik, Nonchengladbach) are dispersed in 750 parts of water and to this disper~ion are added 3.5 parts of an optical brightener of the formula (D) Le A 27 045 - 9 -~` 2021~9 ..... .
, . -H H --~
N ~NH ~ H=CH ~ NH ~ N (D) /---N S03Na 503Na N ~
(in the form of a powder formulation containing ~8% of pure optical brightener).
The resulting di~persion can be incorporated directly into coating compositions. It likewise gives excellent results.
Example 5a 250 part~ of cellulose powder having an average ~:
particle size of 30 ~m (for example Arbocel BE 600/30 10from Rettenmaier) are dispersed in 750 parts of water and :~
to this dispersion are added 5 parts of an optical brightener of the formula (E) H H
N N ~ (E) NH ~ H=CH ~ NH ~ ~ N ::: :
~ ~ ~ N ~ :
H3C-N 503Na 503Na N-CH~ ;:
(in the form of a powder formulation containing 83~ of active ingredient). : :~
The resulting dispersion is likewise eminently suitable for incorporation in coating compositions. ~:
Example 6a 250 parts of pulverulent cellulose acetobutyrate .'..~:
:: . ~ . : -:: :
'~;: -~ ~ ..
Le A 27 045 - 10 -~.. .
` 2 ~ 2 1 5 ~ 9 : : ~
are dispersed in 750 parts of water and to this dispersion are added 25 parts of a 25% strength liquid forming of the optical brightener (A). The dispersion can be incor~
porated directly into the paper coating composition. This 5 gives an excellent brightening effect with comparatively good light fastness.
Example 7a Stirred mixing of ~-60 parts of china clay SPS
40 parts of calcium carbonate 20 parts of an anionic synthetic dispersion of an acryloyl-ester-containing copolymer having a solids content of about 50%
(for example Acronal S 320 D from BASF) 0.5 parts of polyvinyl alcohol parts of polyacryloyl ester as co-binder (40%
strength) (for example Acrosol 40 D from BASF) and 80 parts of water is used to prepare a non-brightened paper coating compo-sition having a solids content of about 55%, whose pH is ad~usted to 9 using aqueous sodium hydroxide solutLon.
Example 8a (comparison, not according to the invention) The coating composition from Example 6 is opti-cally brightened by adding 1.6 parts of the optical brightener of the formula (A) according to Example 1, relative to pigment.
- :.
~: :
Le A 27 045 - 11 --'~ 2 0 2 1 ~ ~ 9 Example 9a Stirred mixing of 60 parts of china clay SPS
30 parts of calcium carbonate 40 parts of the cellulose dispersion from Example .
1 containing 25% of optical brightener 20 parts of an anionic synthetic dispersion of an acryloyl-ester-containing copolymer having a solids content of about 50%
(for example Acronal S 320 D~ from :~
BASF) 0.5 parts of polyvinyl alcohol -~
5 parts of polyacrylate binder ~40% strength) (for example Acrosol 40 D from BASF) and 50 parts of water :~
is used to prepare a paper coating composition having a ~ :
solids content of about 55% whose pH is ad~usted to 9 :. :~
using aqueous sodium hydroxide solution.
Examples lOa - 13a .
To a coating composition composed of 60 parts of china clays SPS
30 parts of calcium carbonate ~:;:
1~ psrts of cellulose powder (Arboc~l BE 600/30 ;~
from Rettenmaier) 20 part~ of an anionic synthetic dispersion of an ~ -:.
acryloyl-ester-containing copolymer ~ ~:
having a solids content of about 50 (forexample Acronal S 320 D from BASF) -~: , . .
~':,~' :, ,~
~e A 27 045 - 12 -: .:: . :
:
2021~9 0.5 parts of polyvinyl alcohol 5 parts of polyacrylate binder (for example Acrosol 40 D from BASF) and 80 parts of water are added the following amounts of the optical brightener ~ ~-for paper, according to formula (A) of Example la, and the pH i6 ad~usted to 9 using aqueous sodium hydroxide solution:
Example lOa: 0.4 parts of optical brightener of the formula (A) Example lla: 0.6 parts of optical brightener of the formula (A) Example 12a: 0.8 parts of optical brightener of the formula (A) Example 13a: 1.6 parts of optical brightener of the formula (A).
Example 14a The coated paper is prepared by applying the coating compositions from Examples 7a - 13a to paper using a doctor blade or test coating equipment and drying the product at 80C. ;
Table 1 shows the CIE whiteness of the papers after preparation and also after exposure to light (1 week in daylight).
Papers which have been prepared by the process according to the invention have, even at reduced optical brightener concentration, not only a higher degree of whitenes~ but also a significantly improved light fastness.
e A 27 045 - 13 -~,. ~:: : . . .
: - ..
- . :
w a~ o~ o N 1` CO` O~ O
O 1 ~t~
u~ ~ a~_~
~ ~ O ~
a\ ~ , "
a~
U~ o O~ t~ o ~ a~ o _~ N
W ,~ ~ ~ o t~
u ~ 0 a~ ~ : .
o a~ ~0 o u~
~ ~ 0~ t~ O~ O C~ O
_ a3 0 ~
¢ ~ a~ ~: a!
P. w a~ ~ a~ a~ a~ ~ a~ ~ a~ a~ a~
~0 a~ C , ~,, .c_l ~ O ~ , " ~, rl .: :, a~ ~ ~ ~ a~ A a~ ~ a~
_I U --I u --0l u 0 u ,a u u u ~ u ~ u ~ u ~ u ~ -rl O rl O ~ O ~rl O ~1 0' '' ~ æ æ~ æ~ æ~ æ~ æ~
o o a~ o ~ o a~ o a~o a~ . --0 W W d W rl W X W X W X
rl ~ O O W O W O W O W O W
dP d~
_I _I O O O _I : .:
.: .:
:-' 0 0 ~ 0 0 0 0 :' '.:'.'.' .' I` Ct~ O~ O _I N ~
a~ a~ a~ a~
x x x x x 0 x0 . --: - -:
Le A 27 045 - 14 ~
.
~- 2 ~ 5 9 Examples 15a - 22a .
A coating composition is prepared similarly to Example 7a, but one part of the chalk is replaced by the same amount of microcrystalline cellulose ~Avicel PH 105) to which 2% in each case of the optical brightener of the formula (A) or (B) has previously been fixed.
The degree of whiteness of the coated papers was examined after preparation and also after exposure to light (Table 2). Papers which have been prepared by the proces~ according to the invention have not only a higher - degree of whiteness but also an improved light fastness.
Le A 27 045 - 15 -~A ~ . , ' 2~
C
U~ ~ : .
u~ la ~ :
a~ o ~ ~ ~ ~ O ~D ~ ~ O
o e P.`~
V ~-,~ o o~
O r: e o 3 o~ :
~o ., ~U 0 o 1~ H ~r N
~1 ~I.C o ~ o ~
P ~1 co cn o ~ o o o `': "'"~"
a) o _~ ~.
H ~ ~ O ~ : ~
0 ~D ~ . :: .
' a C .Oe o~ O ~ N t`~
~D ~ ~ O ~ 1~ ~ N
~J J, (~J ~J~ o o N ~
H ~LI S-l t~, u ~a P. . .
~. . . ,' ~
E J ~ '~
~J
~ C m ~r~ m m ~rl Oe ~
~ ~, 4~
~ p t~rl o o o o o o o o 0 rl ~ U~ ~ ~ ~ ~ . ;.
U J,~ '1 Q N N N N N N N N
.rl ~rl ~ a. ` :::
O O
0 ~ U
~ P~ O Pl O p~ O p~ o p~ o p~ o , ~
o ~, tn" u u u u u u ... ' ,~ .
Q Wo Wo Wo Wo Wo Wo~ ';. .`.:
.-~ ~ 0 6 dP ~ dP
~ a o o u~ O o u~ o o: :--: '- ~ ;.
U 0 U U _I N ~I N`: ~- : : -~,'' '". .', ~'' ~:, ~D : ;.
0 0 la 0 ~ 1 0 "'- ' ;' ' 0 --~ --I H --I ~I N N N ' ~
Le A 2 7 0 4 5 - 16 . .:
. . -~-- 2021~9 :, Example lb ~, 90 parts of microcrystalline cellulose having an 3 average particle size of 20 ~m (for example Avicel PH
1050 from Lehman and Voss, Hamburg) are dispersed in 900 , 5 parts of chalk slurry (for example Omyalite 90~ from ,`~ Omya, having a solids content of 72%) and to this disper-'~ sion are added 9 parts of an optical brightener of the formula (A) ~
H H
Na03S ~ N ~ S03Na N~NI~H- CH~NH~
( HOCH2CH2 ) 2N S03Na S03Na N(CH2CH20H) 2 (in the form of a 25% strength liquid formulation) and I also 33 parts of water.
This dispersion has a solids content of 72% and can be incorporated directly into the paper coating composition. This gives an excellent optical brightening effect with comparatively high light fastness.
I ~ Example 2b ! ~ 116 par~s of cellulose powder having an average particle size of 30 ym (for example Arbocel BE 600/30 from Rettenmaier, Holzmuhle Uber Ellwangen) are dispersed in 900 parts of chalk slurry according to Example 1 and to this dispersion are added 9 parts of an optical brightener of the formula (B) . : .-.: :
_e A 27 045 - 17 -- 2Q~ 9 N~H=CH~3~3 (B) 503Na S03Na (in the form of a 13% strength liquid formulation) and also 80 parts of water.
This dispersion having a solids content of 70%
can be incorporated directly into the paper coating composition. The resulting paper coating has an excellent light fastness. ~
Example 3b ;
90 parts of cellulose powder (for example Avicel PH 105 from Lehmann and Voss) are dispersed in 900 parts of chalk slurry according to Example 1 and to this di~persion are added 18 parts of an optical brightener of the formula (C) I~CH=CH~N~;> ( C ) )=N N=<
(HocH2cH2)2N SQ3Na S03Na N(CH2CH20H)3 '''~
lS (in the form of a 25% strength liquid formulation).
After incorporation in coating compositions, this gives a good optical brightening effect and a compara~
tively high light fastness in the paper coating. ~ ~ -Example 4b 90 parts of cellulose powder having an average particle size of 30 ~m (for example Technocel 30 from Cellulose-FUll~toff-Fabrik, Monchengladbach are dispersed , ~ .,, :: .
, Le A 27 045 - 18 --~` 2021~9 in 900 parts of chalk slurry according to Example 1 and to this dispersion are added 1.2 parts of an optical brightener of the formula (D) H H
N ~NH~:H-CH~NH~ ~N , (D) ~,~> S03Na 53Na N~ ~:
:: ':' (in the form of a powder formulation containing 78% of ~-pure optical brightener) and also 60 parts of water.
The resulting dispersion can be incorporated directly into coating compositions. It likewise gives excellent results.
Example 5 90 parts of cellulose powder having an average psrticle size of 30 ~m (for example Arbocel BE 600/30 from Rettenmaier) are dispersed in 900 parts of chalk slurry according to Example 1 and to this dispersion are added 1.75 parts of an optical brightenar of the formula (E) H - H
N ~NH~CH~CH~}NH~ N
H3C -N S03Na S03N~ N - CH3 ~ .r.. ..
This di~persion can be incorporated directly into a coating composition. The resulting paper coating has a good optical brightening effect and a comparatively high light fastness.
. . .
Le A 27 045 - 19 -2021.559 Example 6b 90 parts of cellulose powder having an average particle size of 30 ~m (for example Arbocel BE 600/30 from Rettenmaier, HolzmUhle uber Ellwangen) are dispersed in 900 parts of kaolin slurry (for example clay SPS~) and to this dispersion are added 9 parts of an optical brightener of the formula (A) (in the form of a 25%
strength liquid formulation) and also 250 parts of water.
This dispersion can be incorporated directly into the paper coating composition. This gives an excellent - optical brightening effect with a comparatively high light fastness.
Example 7b Stirred mixing of 60 parts of china clay SPS~
40 parts of calcium carbonate (corresponding to 55 parts of chalk slurry according to Example 1) 20 parts of an anionic synthetic dispersion of an acryloyl-ester-containing copolymer having a solids content of about 50%
(for example Acronal S 320 D from BASF) 0.5 parts of polyvinyl alcohol 5 parts of polyacryloyl esters as co-binder (40 strength) (for example Acrosol 40 D~
from BASF) and 65 parts of water Le A 27 045 - 20 -2 0 '~
is used to prepare a non-brightened paper coating compo-sition having a solids content of about 55%, whose pH is ad~usted to 9 using aqueous sodium hydroxide solution.
Example 8b (comparison, not according to the invention) The coating composition from Example 7 is opti-cally brightened by adding 1.6 parts of the optical brightener of the formula (A) according to Example lb, -~
relative to pigment.
Example 9b Stirred mixing of 60 parts of china clay SPS~
55 parts of the chalk slurry from Example containing 72% of optical brightener 20 parts of an anionic synthetic dispersion of an acryloyl-ester-containing copolymer having a solids content of about 50%
(forexample Acronal S 320 D~ from BASF) 0.5 parts of polyvinyl alcohol -5 parts of polyacrylate binder (40% strength) (for example Acrosol 40 D~ from BASF) and 65 parts of water is used to prepare a paper coating composition having a solids content of about 55~ whose pH i8 ad~usted to 9 using aqueous sodium hydroxide solution.
Exam~le lOb The coated paper is prepared by applying to paper the coating compositions from Examples 7b - 9b using a doctor blade or test coating equipment and the product is dried at 80C.
Le A 27 045 - 21 - -.'-~' :' ~ 2~21~9 Table 3 shows the CIE whiteness of the papers after preparation and also after exposure to light (1 week in daylight).
Papers which have been prepared by the process S according to the invention have, even at reduced optical ;~
brightener concentration, not only a higher degree of whiteness but also a significantly improved light fastness.
.~- ' ,',",':.' ' : ..- . .. ... .
' '~ "'" ~-,';
.:,: .
~. .
Le A 27 045 - 22 - :.
-~ 2021~9 oo ~
a to ~ o o a~ o ~ , . . . .~.
O ~ P.
~ X.
~ ~ 8 ~o oo @ ~ ~
.. . . .
oN
U 111 ~ ~
. ~ . '-:
:~ .' :., :.:
0 rl '` 1 Ul O U~ ~
a~ ~ p, N N N
~-~1 ~ ~ :' ; ~- :
~C ~ "
: .~ ~:
Pt ~ O, ~ , ~
~ ~ æ~
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~ W ~.
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... . .
,~ :`..'`':`'` '' . ~:: ::
Claims (10)
1. Process for the whitening of paper coating compositions using substantive anionic whiteners, charac-terized in that optical brighteners, water-dispersible cellulose powder or an optical brightener product com-posed essentially of cellulose powder coated with optical brightener and also optionally a coating pigment are added to the coating compositions in any desired order, the cellulose powder having in every case an average particle size of less than 50 µm.
2. Process according to Claim 1, characterized in that use is made of whiteners of the formula (I) in which Z is an alkali metal ion, an amine ion or an ammonium ion, X1 is amino, methylamino, ethylamino, dimethylamino, diethylamino, 2-hydroxy-ethylamino, 3-hydroxy-propylamino, di-(2-hydroxyethyl)amino, di-(2-hydroxypropyl)amino, 2-sulpho-ethylamino,morpho-lino, anilino, chloroanilino, sulphoanilino, methylanilino or disulphoanilino and X2 is hydroxy, methoxy, ethoxy, methoxyethoxy, chlorine or X1.
3. Process according to Claim 1, characterized in that the proportion of cellulose powder in the coating compositions is up to 20% by weight, relative to pigment.
4. Whitener products composed essentially of cel-lulose powder having an average particle size of less than 50 µm, and a substantive anionic whitener.
5. Whitener preparation composed essentially of a) a substantive anionic whitener, b) water-dispersible cellulose powder having an average particle size of less than 50 µm and c) coating pigment.
6. Whitener preparation according to Claim 4 or 5, characterized in that this is an aqueous dispersion.
7. Whitener preparation according to Claim 4 or 5, characterized in that this contains a whitener of the formula (I) in which Z is an alkali metal ion, amine ion or ammonium ion, X1 is amino, methylamino, ethylamino, dimethylamino, diethylamino, 2-hydroxy-ethylamino, 3-hydroxy-propylamino, di-(2-hydroxyethyl)amino, di-(2-hydroxypropyl)amino, 2-sulpho-ethylamino,morpho-lino, anilino, chloroanilino, sulphoanilino, methylanilino or disulphoanilino and X2 is hydroxy, methoxy, ethoxy, methoxyethoxy, chlorine or X1.
8. Whitener preparation according to Claim 5, characterized in that this contains chalk as the coating pigment.
9. Whitener preparation according to Claim 4 or 5, characterized in that this additionally contains a dispersant.
10. Process for the whitening of paper coating com-positions using substantive anionic whiteners, charac-terised in that optical brightener preparations according to Claim 4 or 5 are added to the coating compositions.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP3924051.7 | 1989-07-21 | ||
| DE19893924051 DE3924051A1 (en) | 1989-07-21 | 1989-07-21 | Whitening paper coating compsn. with anionic white toner |
| DEP3938690.2 | 1989-11-22 | ||
| DE3938690 | 1989-11-22 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2021559A1 true CA2021559A1 (en) | 1991-01-22 |
Family
ID=25883227
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002021559A Abandoned CA2021559A1 (en) | 1989-07-21 | 1990-07-19 | Process for the whitening of paper coating compositions and also whitener preparations for this process |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0409028A1 (en) |
| JP (1) | JPH0359192A (en) |
| CA (1) | CA2021559A1 (en) |
| FI (1) | FI903648A0 (en) |
| NO (1) | NO903004L (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10781314B2 (en) | 2015-11-30 | 2020-09-22 | Anomera Inc. | Cellulose-based organic pigments |
| US20220306875A1 (en) * | 2021-03-29 | 2022-09-29 | Micro Powders, Inc. | Biodegradable Cellulosic Powders |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB9101965D0 (en) * | 1991-01-30 | 1991-03-13 | Sandoz Ltd | Improvements in or relating to organic compounds |
| JPH0832997B2 (en) * | 1991-09-20 | 1996-03-29 | 日清紡績株式会社 | Coated paper using cellulose fine powder |
| DE4202598C1 (en) * | 1992-01-30 | 1993-09-02 | Stora Feldmuehle Ag, 4000 Duesseldorf, De | |
| DE19500195A1 (en) | 1995-01-05 | 1996-07-11 | Bayer Ag | Use of white-tinted plastics for tinting paper coating slips and such white-tinted paper coating slips |
| DE19945580C5 (en) | 1999-09-23 | 2007-03-15 | Stora Enso Publication Paper Gmbh & Co. Kg | Coated, optically brightened printing paper and process for its production |
| JP4841263B2 (en) * | 2006-02-21 | 2011-12-21 | 日本化薬株式会社 | Fluorescent whitening agent aqueous liquid composition and fluorescent whitening method using the same |
| EP2799618B1 (en) | 2013-04-29 | 2016-04-27 | Blankophor GmbH & Co. KG | Use of micronized cellulose and fluorescent whitening agent for surface treatment of cellulosic materials |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| BE568156A (en) * | 1957-06-06 | |||
| US3157518A (en) * | 1960-02-23 | 1964-11-17 | Fmc Corp | Coatings of cellulose crystallite aggregates |
| DE3643215A1 (en) * | 1986-12-18 | 1988-06-30 | Bayer Ag | WHITE-TONED PAPER COATINGS |
-
1990
- 1990-07-05 NO NO90903004A patent/NO903004L/en unknown
- 1990-07-07 EP EP90113025A patent/EP0409028A1/en not_active Withdrawn
- 1990-07-19 FI FI903648A patent/FI903648A0/en not_active Application Discontinuation
- 1990-07-19 CA CA002021559A patent/CA2021559A1/en not_active Abandoned
- 1990-07-20 JP JP2190893A patent/JPH0359192A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10781314B2 (en) | 2015-11-30 | 2020-09-22 | Anomera Inc. | Cellulose-based organic pigments |
| US20220306875A1 (en) * | 2021-03-29 | 2022-09-29 | Micro Powders, Inc. | Biodegradable Cellulosic Powders |
Also Published As
| Publication number | Publication date |
|---|---|
| EP0409028A1 (en) | 1991-01-23 |
| JPH0359192A (en) | 1991-03-14 |
| FI903648A0 (en) | 1990-07-19 |
| NO903004L (en) | 1991-01-22 |
| NO903004D0 (en) | 1990-07-05 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |