Concentrated solutions of optical brightener

FIELD: chemistry.

SUBSTANCE: invention relates to concentrated aqueous solutions of hexa-sulfonated stilbene used optical brighteners. Description is given of an aqueous solution of hexa-sulfonated stilbene optical brightener which is stable during storage with over 0.214 mol/kg content thereof in the solution. The solution does not contain a soluble agent, for example urea. By removing salts formed during synthesis of the optical brightener, its concentration of up to 0.35 mol/kg can be achieved without losing stability during storage. Also described is a method of preparing an aqueous solution of the said optical brightener and its use for bleaching paper or cellulose materials.

EFFECT: high concentration solutions of the said optical brightener do not show crystallisation signs after 2 weeks at 5°C and enables formation of coating compositions with low water content, which reduces energy consumption on drying and reduces penetration of water and adhesive into the paper layer.

10 cl, 1 dwg, 1 tbl, 3 ex

 

This invention relates to concentrated aqueous solutions hexachlorophane stilbene used as optical brighteners, which are stable during storage in the absence of facilitating the dissolving agents, such as urea.

PRIOR art

Application hexachlorophane of stilbene as optical bleaching agents (OEA) is a well studied method for obtaining a high quality paper with a high degree of whiteness. Such optical brighteners are widely marketed and used in the form of aqueous solutions. Japanese patent 62-106965 discloses an optical Brightener, or its salts

in which R1and R2each independently may represent a same group of the following

and a represents a group such as a hydrogen atom, alkyl group containing from 1 to 4 carbon atoms and which may have lateral branching, hydroxymethylene group, hydroxyethylene group, methylthioethyl group, benzyl group, methoxycarbonyl group and ethoxycarbonyl group.

According to Japanese patent mentioned optical brighteners have very high solubility in water and can be sold in the form of a concentrated solution of the Les removal of sodium chloride, formed in the reaction and concentration of the aqueous solution in an appropriate way. Optical brighteners claimed as a very effective tool in the bleaching of paper with surface treatment.

Each example Japanese patent describes the preparation of optical Brightener in the form of concentrated solutions, which were absoluely by ultrafiltration. Assuming that in example 1, the reaction of the starting compounds gives 100% output mentioned optical Brightener, the maximum concentration in the above-mentioned concentrated solution will 0,214 mol/kg (30-32%). All solutions were then led in a stable storage state by adding 10% urea.

The document, therefore, indicates that the aqueous solutions mentioned optical brighteners unstable at concentrations 0,214 mol/kg (30-32%) in the absence of urea.

However, there is a demand for a more concentrated aqueous solutions of optical brighteners. The concentration of the aqueous solution is subject to specific values when bleach is used in the composition for a colored coating. It is well known that paper manufacturers strive to reduce the water content in the composition for coating in order to reduce energy drying and to reduce the penetration of water and glue in the paper (see, for example, "The Essential uide to Aqueous Coating of Paper and Board", ed.T.W.R.Dean, PITA,1997).

Description of the INVENTION

Unexpectedly, and in contrast to the claims mentioned Japanese patent now discovered that some of these hexachlorophane of stilbene used as AOA can be obtained in the form of highly concentrated aqueous solutions, which are stable when stored at a concentration 0,350 mol/kg (54% by weight). When applied to the surface of the paper or in the composition for a colored coating or in press in size, these aqueous solutions provide excellent effects fluorescent whitening.

Thus, the object of the present invention is stable during storage of the aqueous solution of the optical Brightener of formula (1)

where M may be hydrogen, a cation of an alkali metal, ammonium ion, or an ammonium ion, a mono-, di-, or trisemester2-C3-hydroxyalkyl radicals, and hydrogen or sodium cation is more preferable; and

n is a natural number from 1 to 4, preferably 1 or 2,

characterized in that the optical Brightener content higher than 0,214 mol/kg, preferably from 0,215 to 0,350 mol/kg, particularly preferably from 0,250 to 0,340 mol/kg and the solution does not contain the agent that promotes dissolution.

Aqueous solutions of optical brighteners can dobova is but to contain one or more carriers, antifreeze agents, preservatives, complexing agents and organic by-products formed during the preparation of optical bleach.

It is known that the media give improved characteristics OSVETLENIE and these may be the glycols, polyvinyl alcohols, carboxymethylcellulose.

Antifreeze can be, for example, urea, diethylene glycol or triethylene glycol.

The compounds of formula (1) was obtained by reaction of cyanoguanidine consistently with

a) a diamine of the formula (A)

b) an amine of the formula (B)

c) an amine of the formula (C)

Here as cyanoglucoside can be used bromide or, preferably, chloride.

All reactions can be performed in the aquatic environment, when suspendirovanie of cyanoglucoside in water or in aqueous-organic medium, however, cyanogenetic can be dissolved in a solvent such as acetone. Any amine can be introduced into the reaction without dilution, in the form of an aqueous solution or suspension. Amines can be introduced into the reaction in any order, although it is preferable to first enter into the reaction of the aromatic amine. Any of the amines can be introduced into the reaction in equimolar quantity or used in excess. Typically, the aroma is practical amines are used in equimolar amount or in slight excess, and aliphatic amines are generally used in excess 5-30% of stoichiometric.

For the first substitution of halogen in cyanoglucoside, it is preferable to work at temperatures in the range 0-20°C, in an acidic or neutral medium, preferably in the pH range 2-7. To replace the second halogen in cyanoglucoside, it is preferable to work at temperatures in the range of 20-60°C and in a weakly acidic or weakly alkaline medium, preferably in the range of pH 4-8. To replace the third halogen in cyanoglucoside, it is preferable to work at temperatures in the range 60-102°C in acid or alkaline medium, preferably in the range of pH 7-10. A certain value of pH can be supported by the addition of suitable acids or bases as needed, it is preferable to use as hydrochloric acid, sulfuric, formic or acetic acid, and bases, hydroxides, carbonates or bicarbonates of alkali metals (lithium, sodium or potassium) or an aliphatic tertiary amines, for example triethanolamine or triisopropanolamine.

Further object of this invention is the method for obtaining the above-mentioned aqueous solutions, in which the compounds of formula 1 were obtained as described previously, and salts of alkali metals or amines, formed as a side product in all reactions between AMI is AMI and cyanoglucosides, were removed from the reaction solution.

In order to obtain a stable aqueous solution with a concentration higher than 0,214 mol/kg (32-33% by weight), preferably from 0,214 to 0,340 mol/kg, particularly preferably from 0,250 to 0,340 mol/kg, the compound of formula (1) without adding facilitate dissolving agents, such as ethylene glycol, urea or mono-, di-, tri-(2-hydroxyethyl)-, (2-hydroxypropyl)amine, it is necessary to remove at least 50%, better than 80% by weight of salts of alkali metals or amines, which formed as a side product in all reactions between amine and cyanoglucosides. This is best done by ultrafiltration or membrane filtration of the solution obtained as described previously. In another method, the compounds of formula (1) can be isolated by precipitation (for example, by adding acid) and then re-dissolved.

Further object of this invention is the application of data storable aqueous solutions for whitening paper or other cellulosic materials.

Concentrated solutions of compounds of formula (1) is particularly suitable for bleaching paper after the formation of the printed sheet. This can be achieved by adding a solution of the optical Brightener in the composition for a colored coating or to the solution or suspension to be printed.

In preferred options the ante for the present invention, concentrated solutions of formula (1) are applied on the surface of the paper in the composition for a colored coating.

Covering compositions are substantially water compositions containing at least one binder and a white pigment, in particular opalescent white pigment, and may further contain additional additives, such as desdemonia additives such as dispersant additives and defoamers.

Although it is possible to produce a cover song without white pigment, best white preparations for printing were made using matte coating compositions containing 10-70% by weight of white pigment. Such white pigments are mostly inorganic pigments, such as aluminum silicate (kaolin, otherwise known as China clay), calcium carbonate (chalk), titanium dioxide, aluminum hydroxide, barium carbonate, barium sulfate, calcium sulfate (gypsum).

The binder can be any of those typically used in the paper industry to obtain coating compositions and can consist of a single binder or a mixture of primary or secondary binder. The base or primary binder is a synthetic latex, usually styrene-butadiene, vinyl acetate, styrene-acrylic, vinyl-acrylic or ethylene-vinyl acetate polymer. WTO the ranks of the binder may be, for example, starch, carboxymethylcellulose, casein, soy polymers or polyvinyl alcohol.

The upkeep of the grounds, or the primary binder is 5-25% by weight of white pigment. The content of the used secondary binder is 0.1-2% by weight of white pigment, however, the starch content is 5-10% by weight of white pigment.

The optical Brightener content is 0.01-1% by weight of white pigment, preferably in the range of 0.05-0.5% by weight of white pigment.

The following examples will explain the invention in more detail. The word "part", unless otherwise specified, means "part by weight".

An EXAMPLE of OBTAINING 1.

The solution containing 21.3 parts of aniline-2,5-disulfonate and 6.7 parts of water, was added to a stirred suspension of 15.5 parts of cyanuric chloride in 50 parts of water. Precapitalism 30% sodium hydroxide kept pH 6. The mixture was stirred at a temperature below 10°C up until primary aromatic amino group was determined by vasoreactive. Then was added a solution of 14.8 parts of 4,4'-diaminostilbene-2.2 dissolvability and 3.2 parts of sodium hydroxide in 20 parts of water, with addition of 30% sodium hydroxide was keeping the pH between 6.5 to 7.5 and the mixture was stirred at 30°C until, until there was obtained a negative desireable. After adding 12.2 parts of L-and arginbai acid 22.9 parts of 16% sodium hydroxide and the mixture was boiled for 6 hours keeping pH in the range of 7.5-8.5 by addition of 30% sodium hydroxide. Thus obtained solution of the compound (2) in the form of its sodium salt, which has a concentration of approximately 0,167 mol/kg, was desalted by membrane filtration and concentrated to 0,330 mol/kg (50% by weight). The resulting solution, 2% sodium chloride, has a viscosity of 0.23-0.25 Pa at 20°C and shows no signs of crystallization after 2 weeks at 5°C.

EXAMPLE of RECEIPT 2.

An aqueous solution (3) in the form of its sodium salt with a concentration of 0,330 mol/kg (51 by weight) prepared as described in example 1, but using 13.5 parts of L-glutamic acid instead of 12.2 parts of L-asparginase acid. The resulting solution, 2% sodium chloride, has a viscosity of 0.23-0.25 Pa at 20°C and shows no signs of crystallization after 2 weeks at 5°C.

APPLICATION EXAMPLE 1.

Covering composition was obtained from 500 parts of chalk (commercially available under the trade name Hydrocarb 90 from the company OMYA), 500 parts of clay (commercially available under the trademark of SPS Kaolin company IMERYS) 470 parts of water, 6 parts of dispersing agent (sodium salt of polyacrylic acid, commercially available under the trademark Polysalz S BASF), 200 parts of latex (copolymer of acrylic ester commercially available under the trade name Acronal S320D BASF) and 0 parts 10% aqueous solution of carboxymethyl cellulose (commercially available under the trademark Finnfix 5.0 company Noviant). The solids content was adjusted to 65% by adding water, and the pH was adjusted to 8-9 by adding sodium hydroxide.

The bleach solution in the form of its sodium salt, obtained as described in example obtain 1, was added to achieve a content of 0.1 to 0.6% for mixed covering composition. Then bleached covering the composition was applied on a commercial medium white paper sheet, using automatic wire-roller application with standard speed settings and a standard load bars. Coated paper was then dried for 5 minutes in a stream of hot air. The dried paper meets the requirements, as shown by measurement of the whiteness index CIE on the calibrated spectrophotometer “Elrepho”.

Table
The concentration of AOA(%)White index CIE when applying the bleach from example 1
092,0
0,197,9
0,2102,6
0,3106,2
0,4 108,4
0,5110,3
0,6to 112.2

Results are also presented in graphical form in the drawing.

1. Storable aqueous solution containing an optical Brightener of the formula 1,

where M may be hydrogen, a cation of an alkali metal, ammonium ion, or an ammonium ion, a mono-, di-, or trisemester2-C3-hydroxyalkyl radical, and
n is a natural number from 1 to 4
characterized in that the optical Brightener content higher than 0,214 mol/kg, and the solution does not contain the agent that promotes dissolution.

2. Storable aqueous solution according to claim 1, where
M may be hydrogen or a cation of sodium, and
n is a natural number of 1 or 2.

3. Storable aqueous solution according to claim 1 or 2, in which the concentration of the optical Brightener from 0,215 to 0,350 mol/kg

4. Storable aqueous solution according to claim 3, in which the concentration of the optical Brightener from 0,250 to 0,340 mol/kg

5. Storable aqueous solution according to any one of claim 1 or 2, in which there are advanced inorganic salts, carriers, antifreeze agents, preservatives or complexing agents.

6. The way to get water is astora according to any one of claims 1 to 5, where the compounds of formula (1) was obtained by reaction of cyanoglucoside consistently with
a) a diamine of the formula (A)

b) an amine of formula (V)

c) an amine of the formula (C)

and in which at least 50%, preferably 80% by weight alkali metal salt or amine salt formed as a by-product of each reaction with an amine, and cyanogenetic removed from the reaction solution.

7. The method according to claim 6, in which the removal of the alkali metal salt or amine is performed by ultrafiltration or membrane filtration of the reaction solution or by separating the optical Brightener and then dissolving it again.

8. The method according to claim 7, in which the removal is performed by membrane filtration.

9. The use of stable storage of an aqueous solution according to claims 1-5 for whitening paper or pulp products, in which the optical Brightener used in a concentration of from 0.05 to 0.5 wt.% from the white dye.

10. The use according to claim 9 for clarification paper in the composition for a colored coating.



 

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2 tbl, 12 ex

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SUBSTANCE: present invention relates to new amphoteric bis-triazinylaminostilbene fluorescent whitening agents for fluorescent whitening of organic materials, particularly paper. Description is given of use of compounds with formula (5) for fluorescent whitening of paper.

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2 cl, 2 tbl, 48 ex

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