JPH0359192A - Method of increasing white color of paper paint and white increasing agent product for use in the same - Google Patents

Abstract

PURPOSE: To manifest sufficient optical brightening effect while retaining light- fast property by adding a optical brighter agent product consisting of an optical brighter agent and specific cellulose powder and a pigment to a paper coating material. CONSTITUTION: A paper coating material is effectively brightened with a mixture prepared by adding to (A) an optical brighter product consisting of an optical brighter and water dispersible cellulose powder, or comprising cellulose powder coated with a an optical brighter (B) a pigment for a coating material. The cellulose powder has <50 μm average particle diameter.

Description

DETAILED DESCRIPTION OF THE INVENTION Aqueous coating compositions which, in addition to the usual white pigments, in particular kaolin and calcium carbonate, also contain synthetic leather latex as a binder are used very extensively in the production of coated paperboards and paperboards. .

Generally, optical brightening of these paints is achieved through the use of direct anionic optical brighteners, such as alkali metal salts of bistriazinylaminostilbene disulfonic acid. However, these brighteners have a very poor optical brightening effect and a very low gray limit (brightener concentration where addition of further brightener does not increase whiteness or even decreases it). It's nothing more than that. Furthermore, this type of brightener is
This type of paint has a very low lightfastness.

It is generally known that these difficulties can be partially overcome in two different ways.

1. By adding a small amount of hydrophilic co-binder to the paint to which the brightener can bind. Examples of co-binders of this type are starch, casein, carboxymethyl cellulose, alkynates, polyvinyl alcohol, polyacrylates and melamine- or urea-formaldehyde resins [
"Das Papier", 36
(1982), 66 1°2, by the use of certain water-soluble brighteners containing woody carriers. This type of carrier can be, for example, a polyglycol (
cf. German Patent Application No. 3.502.038 and European Patent Application No. 43.790).

Although the whitening effect is considerably improved by these methods, the sensitivity of the coated paper to water is increased at the same time, which causes difficulties in certain printing methods and uses of the coated paper. Furthermore, the use of these additives in paints often creates rheological problems on modern high speed coating equipment.

Furthermore, it is known to bind water-soluble brighteners to certain resins, such as urea resins or methylol resins, and to add these fluorescent brightening resins in a dispersed state to paper preparations (Germany). (See National Patent Application Publication No. 3.112.435). However, these proposals have so far not taken root due to their excessively high cost or rheological difficulties.

Surprisingly, an optical brightener product consisting of an optical brightener and a water-dispersible cellulose powder, or a cellulose powder coated with an optical brightener, and optionally a paint pigment can be added to the paint in any desired order; If the cellulose powder has an average particle size of less than 50 μm in all cases, it can be used for paper coatings with the abovementioned brighteners and without the abovementioned disadvantages!
It has been found that 1Flt products can be fluorescently brightened.

Examples of suitable cellulose powders include microcrystalline cellulose, which no longer has a fibrous structure of any kind, usually obtained from cotton linters or wood cellulose by a combination of hydrolysis and mechanical wet crushing of the particles and by spray drying. , [See Um5chau J 7ヱ (1'J77), 312 1゜ Also, as appropriate,
There are cellulose powders which are produced by dry milling of conventional wood cellulose and which likewise no longer have essentially any fibrous structure.

Particularly suitable are about 30% or more, preferably about 50%
It is a cellulose powder that has a high crystallinity and also has a reduced hydrophilicity and is dispersed in water with a solids content of up to about 25%.

Also suitable are water-soluble substituted celluloses, such as cellulose ethers, such as methyl or ethyl-
Cellulose or cellulose esters such as cellulose acetate, cellulose acetobutyrate and cellulose acetogropionate.

Cellulose powder having a particle size of 25 to 35, especially about 35 μm is preferred.

Paints may be made by incorporating up to 20% cellulose powder (based on the total amount of pigment added).

Suitable cellulose brighteners for use according to the invention are bistriazolylstilbene disulfonic acid, bisstilbene disulfonic acid and especially bistriazinyl-aminostilbene disulfonic acid.

Examples of particularly suitable optical brighteners include those of the formula (2), where 2 is an alkali metal ion, an amine ion or an ammonium ion, and xl is amino, methylamino, ethylamino, dimethylamino, diethylamino, 2-hydroxy-ethylamino, 3-hydroxy-propylamino, di(2-hydroxyethyl)amino, di(2-hydroxypropyl)amino, 2-sulfo-ethylamino, morpholino,
anilino, chloroanilino, sulfoanilino, methylanilino or disulfoanilino, and X is hydroxy, methoxy, ethoxy, methoxyethoxy, chlorine or Xl, and where X and X are hydrogen, methyl , ethyl, phenylma I; is sulfophenyl, and in the formula, X is hydrogen, methyl, ethyl, methoxy, ethoxy,
chlorine or sulfo, where 2 is in all cases an alkali metal ion, an amine ion or an ammonium ion.

The optical brightener is preferably present in its sodium salt form.

Suitable paint pigments include clay, kaolin, silica, aluminum oxide, aluminum silicate, talc and especially chalk. These pigments are preferably used in the form of an aqueous slurry.

The optical brighteners according to the invention can be easily prepared by dispersing a suitable cellulose powder in water and adding the customary anionic optical brighteners for paper or textiles.

Surprisingly, even at low temperatures, the optical brightener remains bound to the dispersed cellulose powder without difficulty, and the optically brightened cellulose powder remains stable even at relatively high optical brightener loadings. Does not show graying.

If the brightener preparation according to the invention contains a conventional white pigment, a suitable cellulose powder and also a conventional anionic optical brightener for paper or textiles are mixed with a small amount of water, if necessary, and a commercially available filler slurry. Mix together while stirring or
Alternatively, the filler slurry can be easily produced by mixing during the dispersion and pulverization process that is performed during the production of the filler slurry.

The resulting dispersion can be prepared using conventional anionic or nonionic dispersants such as salts of polycarboxylic acids, sulfated or unsulfated higher alkanol ethers or alkylphenol polyglycol ethers, lignin sulfonates, carboxymethyl cellulose, hydroxyethyl cellulose, etc. Get the content.

Surprisingly, despite its high hydrophilicity, cellulose powder additives only slightly increase filler slurry viscosity, so that they can contain high solids contents up to concentrations of 70% or more.

Cellulose powder can be used in the brightener preparations according to the invention in any desired ratio to the white pigment, and the viscosity can be adjusted to the desired value at the same time by adding water.

Cellulose powder contents of up to 20% relative to white pigment are preferred, and high pigment concentrations in the slurry can be chosen without significant increase in viscosity.

The paint may be made by incorporating up to 20% cellulose powder (based on the total amount of pigment added) into the paint.

The amount of optical brightener added is controlled by the amount of cellulose powder present in the brightener preparation according to the invention.

Generally, amounts of active acid up to 10% based on cellulose powder can be used.

Higher amounts have no further effect as the graying limit is exceeded. 2.5-7 for dry cellulose powder
Preference is given to using amounts of %. In addition to this, about lO~30
It is advantageous to use commercially available liquid preparations with a concentration of 15% to 25%.

The optical brightener preparations used according to the invention are new and therefore likewise an object of the invention.

The optical brightener preparation can be added to the paint in dispersion immediately after its manufacture and processed on a conventional coating machine.

Aqueous optical brightener products may also be processed by conventional processes such as filtration and drying to produce powder products.

In another variant according to the invention, the cellulose powder and the optical brightener can also be added separately during the production of the paint, in which case the optical brightener is immediately bound to the cellulose powder used.

The amount of optical brightener or optical brightener preparation used is adjusted according to the desired optical brightening effect. Generally, 0, O1 ~
0.5% by weight of the pure active ingredient of the optical brightener (based on the pigment of the paper coating to be brightened) is sufficient. A particular advantage is the graying limit (
Up to that limit, the addition of further optical brighteners is still effective) is extremely high.

It is particularly advantageous to use optical brighteners in the form of commercially available liquid preparations with a concentration of approximately 10-30%, preferably 15-25% (%=% by weight).

Examples ka Microcrystalline cellulose having an average particle size of 20 μm [e.g.
ss), Avicei P H105 manufactured by Mburg
@1250 parts were dispersed in 750 parts of water and 25 parts of optical brightener of formula (A) (in a 25% liquid preparation) were added to this dispersion.

This dispersion could be incorporated directly into paper coatings.

This resulted in an excellent optical brightening effect with relatively high lightfastness.

Example 2a Cellulose powder with an average particle size of 30 μm [e.g. Rettenmaier, Holzmuhle
Arbocel manufactured by BER Ellwangen
250 parts of B E 600 / 30O] were dispersed in 750 parts of water and 25 parts of an optical brightener of formula (B) (in a 13% liquid preparation) were added to this dispersion.

This dispersibility allowed for direct incorporation into paper coatings.

The resulting paper coating had excellent lightfastness.

Example 3a Cellulose powder (e.g. A from Lehman & Boss)
vicel P) (l O5') 250 parts to 750 parts of water
s and to this dispersion, formula (C) (25%
50 parts of optical brightener (in liquid preparation form) were added.

After being incorporated into paints, this provided painters with a good optical brightening effect and relatively high lightfastness.

Example 4a Cellulose powder with an average particle size of 30 μm [e.g.
ff-F abrik, M6nchengladba
ch) @T echnoce130[F]]250
part is dispersed in 750 parts of water, and this dispersion is given the formula (
D) 3.5 parts of optical brightener (in the form of a powder preparation containing 78% pure optical brightener) of (D) were added.

Arise! The bidispersion could be incorporated directly into the paint. This gave equally good results.

Example 5a Cellulose powder with an average particle size of 30 pm (e.g. Arbocel B E 600/3 from Rettenmeyer)
0) Disperse 250 parts in 750 parts of water and add to this dispersion 5 parts of an optical brightener of the formula (E) (in the form of a powder preparation containing 83% of the active ingredient) I;

The resulting dispersion was likewise eminently suitable for formulation into paints.

Example 6a 250 parts of powdered cellulose acetobutyrate were dispersed in 750 parts of water, and 25 parts of 25% liquid optical brightener (A) were added to this dispersion. The dispersion could be incorporated directly into paper coatings. This showed an excellent whitening effect with relatively good lightfastness.

Example 7a Anionic synthetic latex of acrylic-ester-containing copolymer with 360 parts of Kaolin 5P, 40 parts of calcium carbonate, about 50% solids (e.g. Acrona from BASF)
l S 320 D@) 20 parts, polyvinyl alcohol 0.5 part, polyacrylic ester (40%) as co-binder (for example Acrosul from BASFlR)
A stirred mixture of 5 parts D') and 80 parts water was used to prepare an unwhitened paper paint with a solids content of about 55%, and the pH value of the paint was adjusted to 9 using an aqueous sodium hydroxide solution.
Adjusted to.

Example 8a (comparative example not according to the invention) The paint from Example 6 was optically brightened with respect to the pigment by adding 1.6 parts of optical brightener of formula (A) according to Example 1.

Example 8a 40 parts of the cellulose dispersion from Example 1 containing 60 parts of kaolin 5PS, 30 parts of calcium carbonate, 25% of optical brightener, anionic synthetic latex of acrylic-ester-containing copolymer with a solids content of about 50%. (For example, BASF's Ac
ronal S 320 D'20 parts, polyvinyl alcohol 0.5 parts, polyacrylate binder (4
0%) (e.g. BASFM Acronal 40
A stirred mixture of 5 parts D■) and 50 ml of water was used to prepare a paper coating with a solids content of approximately 55%, the pH of which was adjusted to 9 using an aqueous sodium hydroxide solution.

Example 10a-13a Kaolin 5PS 60 parts, calcium carbonate 30 parts Cellulose powder (ArbocelBE manufactured by Rettenmeyer)
600/30) 10 parts, approximately 50% solids acrylic
Anionic synthetic latex of ester-containing copolymer (
For example, BASF! l's Acronal 5320D) 2
0 parts, polyvinyl alcohol 0.5 parts, acrylate.
5 parts of binder (e.g. Acronal 4 from BASF)
0 D) To a paint consisting of 5 parts and 80 parts water, add the following amounts of optical brightener according to formula (A) of Example 1a for paper,
Example 10a: 0.4 parts of optical brightener of formula (A) Example 11a: 0.6 part of optical brightener of formula (A) Section Example 12
a: 0.8 parts of optical brightener of formula (A) Example 13a: Formula (
1.6 parts of optical brightener of A) Example 14a The coatings from Examples 7a to 13a are applied to paper using a doctor blade or test coating equipment and the coating is heated at 80°C. A coated paper was produced by drying.

The m1 table shows the whiteness of the paper after manufacture and after exposure to light (1 week at 13 lights).

The paper produced by the process according to the invention has not only a high degree of brightness even at reduced optical brightener concentrations, but also a considerably improved lightfastness.

Examples 15a-22a Paints are prepared analogously to Example 7a, but a portion of the chalk is in each case 2 of an optical brightener of formula (A) or (B).
The same amount of microcrystalline cellulose (A
vicel PHI O5).

The whiteness of the coated paper was tested after production and after exposure to light (Table 2), and the paper produced by the method according to the invention has not only a high degree of whiteness, but also an improved lightfastness. .

Example 1b Microcrystalline cellulose having an average particle size of 20 μm (e.g. Avicel from Lehmann & Bos, Hamburg)
PHI O5@) 90 parts of chalk slurry [e.g. Omya manufactured by Omya having a solids content of 72%]
yalite 90 O) and to this dispersion were added parts of an optical brightener of formula (A) (in the form of a 25% liquid preparation) and also 33 parts of water.

This dispersion had a solids content of 72% and could be incorporated directly into paper coatings. This showed an excellent fluorescent whitening effect with relatively high light fastness.

Example 2b Cellulose powder with an average particle size of 30 μm (e.g. Arbocel BE 600/30” from Leftenmayer, Holzmühle-Uebel-Erwangen)
) 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 () ) (in a 13% liquid preparation) and also 8 parts of water. Ta.

This dispersion with a solids content of 70% could be incorporated directly into paper coatings. The resulting paper coating had excellent lightfastness.

Example 3b Cellulose powder (e.g. A from Lehman & Boss)
90 parts of vicel PH105@) were dispersed in 900 parts of the chalk slurry according to Example 1 and 18 parts of optical brightener of formula (C) (in a 25% liquid preparation) were added to this dispersion.

After incorporation into paints, it showed good fluorescent whitening effects and relatively high lightfastness in paper coatings.

Example 4b 90 parts of cellulose powder (e.g. Technocel 30' from Mönchengraftbach) having an average particle size of 30 μm are dispersed in 900 parts of Chiro-Kes slurry according to Example 1 and To the dispersion were added 2% optical brightener L-2 of formula (D) (form a of powder preparation containing 78% pure optical brightener) and 60% water.

The resulting dispersion could be incorporated directly into paints.

This gave equally good results.

Example 5b Cellulose powder with an average particle size of 30 pm (e.g. Arbocal B E 600/3 from Rettenmeyer)
0@) 90 parts of chalk slurry according to Example 1 900
and to this dispersion was added 1.75 parts of an optical brightener of formula (E).

This dispersion could be incorporated directly into paints. The resulting paper tray had good fluorescent whitening effect and relatively high light fastness.

Example 6b Cellulose powder with an average particle size of 30 μm (e.g. Arbocel B E 600/300 from Rettenmayer, Holzmühle ◆ Uber Erwangen) 9
0 parts of kaolin slurry (e.g. clay SPS■) 900
and to this dispersion, formula (A) (25%
9 parts of optical brightener (in a liquid preparation) and also 25 parts of water
Added 0 parts.

This dispersion can be directly incorporated into paper coatings.

This showed an excellent fluorescent whitening effect with relatively high light fastness.

Example 7b 60 parts of kaolin SPS, 40 fi of calcium carbonate (corresponding to 55 parts of the chalk slurry according to Example 1), anionic synthetic latex of acrylic-ester-containing copolymer with a solids content of about 50% (e.g. from BASF) Acr of
onal S 320 D@) 20 parts, polyvinyl alcohol 0.5 g, polyacrylic ester (40%) as co-binder (for example Acron from BASF)
A stirred mixture of 5 parts al 40 D') and 65 parts water was used to prepare an unwhitened paper paint with a solids content of about 55%, and the pH of the paint was adjusted to 9 using an aqueous sodium hydroxide solution.

Example 8b (comparative example not according to the invention) The paint from Example 7 was optically brightened with respect to the pigment by adding 1.6 parts of optical brightener of formula (A) according to Example 1b.

Example 9b 60 parts of kaolin SPS'', 55 parts of the chalk slurry from Example 1 containing 72% optical brightener, an anionic synthetic latex of an acrylic-ester-containing copolymer having a solids content of about 50% (e.g. Acronal made by BASF
S 320 D ■) 20 parts, polyvinyl alcohol 0.5 part, polyacrylate binder (40%) (for example Acrona 140D@ from BASF) 5 parts and water 65
The stirred mixture of 50% was used to prepare a paper coating with a solids content of about 55%, the pH of which was adjusted to 9 using an aqueous sodium hydroxide solution.

Example 10b Coated papers were prepared by applying Examples 7b to 9b to paper using a doctor blade or test coating equipment, and the coatings were dried at 80°C.

Table 3: After manufacture and also exposure to light (1 week in sunlight)
The CIE brightness of the subsequent paper is shown.

The paper produced by the process according to the invention has not only a high degree of whiteness even at reduced optical brightener concentrations, but also a considerably improved lightfastness.

The main features and aspects of the invention are as follows.

1. Adding an optical brightener, an optical brightener rawhide consisting of a water-dispersible cellulose powder or a cellulose powder essentially coated with an optical brightener, and optionally a paint pigment to the paint in any desired order; wherein the cellulose powder has in all cases an average particle size of less than 50 μm,
A method for whitening paper paint, characterized by the following.

2, Formula (1) In the formula, 2 is an alkali metal ion, amine ion or ammonium ion, and Xl is amino, methylamino, ethylamino, dimethylamino, diethylamino, 2-hydroxy-ethylamino, 3-hydroxy Seaglobylamino, di(2-hydroxyethyl)amino, di(2-hydroxypropyl)amino, 2-sulfo-ethylamino, morpholino,
Anilino, chloroanilino, sulfoanilino, methylanilino or disulfoanilino, wherein x2 is hydroxy, methoxy, ethoxy, methoxyethoxy, chlorine or X. How to put it on.

3. The ratio of cellulose powder in the paint is 2 based on the pigment.
1. The method according to item 1, characterized in that it contains up to 0% by weight.

4. Cellulose powder with an average particle size of essentially less than 50 pm and a direct anionic whitening agent (rawhide).

5. A brightener preparation consisting essentially of: a) a direct anionic brightener; b) a water-dispersible cellulose powder with an average particle size of less than 50 μm; and C) a paint pigment.

6. The brightener preparation as described in 4 or 5 above, which is an aqueous dispersion.

7. Formula (1) In the formula, 2 is an alkali metal ion, amine ion or ammonium ion, and X is amino, methylamino, ethylamino, dimethylamino, diethylamino, 2-hydroxy-ethylamino, 3- Hydroxy-propylamino, di(2-hydroxyethyl)amino, di(2-hydroxypropyl)amino, 2-sulfo-ethylamino, morpholino,
In 4 or 5 above, the whitening agent is anilino, chloroanilino, sulfoanilino, methylanilino or disulfoanilino, and X2 is hydroxy, methoxy, ethoxy, methoxyethoxy, chlorine or X. Brightener preparation as described.

8. The brightener preparation as described in 5 above, characterized in that it contains chalk as a paint pigment.

9. The brightener preparation according to 4 or 5 above, further comprising a dispersion pair.

10. A method for whitening paper paint using a direct anionic brightener, which comprises adding the optical brightener preparation according to 4 or 5 above to the paint.

Claims (1)

[Claims] 1. An optical brightener product consisting of an optical brightener, a water-dispersible cellulose powder or a cellulose powder essentially coated with an optical brightener, and optionally a paint pigment, as desired. in addition to the paint, wherein the cellulose powder is in all cases of an average particle size of less than 50 μm.
A method for whitening paper paint, characterized by the following. 2. A brightener product consisting essentially of cellulose powder with an average particle size of less than 50 μm and a direct anionic brightener. 3. A brightener preparation consisting essentially of a) a direct anionic brightener, b) a water-dispersible cellulose powder with an average particle size of less than 50 μm, and c) a paint pigment.