Aqueous dispersion of optical bleaching agent

FIELD: chemistry.

SUBSTANCE: invention describes an aqueous dispersion of an optical bleaching agent which is stable during storage, does not contain dispersants and stabilisers and contains 20-40% active substance in form of one or more optical bleaching agents obtained through successive reaction of cyanuric chloride with 4,4'-diamino-2,2'- stilbene sulphonic acid, amine and a product of reacting monoethanol amine with acrylamide.

EFFECT: disclosed dispersion of optical bleaching agent does not require dispersants or other stabilising additives to prevent settling during storage and has excellent properties for bleaching paper and other cellulose materials.

8 cl, 2 tbl, 4 ex

 

The present invention relates to aqueous dispersions of one or more optical brighteners (PO), which need no dispersants or other stabilizing additives in order to avoid sedimentation during storage. Optical brighteners are from sulphonated compounds triazinetrione, which have excellent bleaching properties of paper and other cellulose materials.

Water dispersion of optical brighteners are known in practice. DE-A-2715864 describes suspensions that are stable with the use of anionic, cationic or non-ionic dispersants. US 5076968 describes the use of anionic polysaccharides to obtain stable during storage suspensions of fluorescent whitening agents. In addition, EP-A-385374 describes anionic polysaccharides, in particular xanthan gum as a stabilizing agent.

However, any additional supplementation may exert a harmful influence during the bleaching process, and therefore, aqueous dispersion, does not require any stabilizing agent such as dispersants or other connections, will have a technical advantage.

Unexpectedly, it was found that stable when stored water dispersion from sulphonated compounds of triazinetrione that do not contain such additives can be obtained and profitably used for optical bleaching of paper, textiles or other cellulosic bases.

Therefore, the object of the present invention is

aqueous dispersion containing as active substance one or more optical brighteners of the formula (I)

in which

R represents a radical of the formula (II), (III) or (IV)

and where the two radicals R can be identical or different,

M represents a cation of an alkali metal or ammonium cation, unsubstituted or substituted C1-C2is an alkyl or hydroxyalkyl group, and most preferred is Na+.

Most preferred is a dispersion containing a mixture of 2-4 optical brighteners of the formula (I) with different radicals R.

These dispersions contain from 10 to 40% wt. the active substance, preferably from 14 to 26 wt.%. the active substance.

If required, these suspensions may additionally contain from 0.01% to 0.5% wt. the non or biocide, or both compounds in the indicated amounts.

Optical brighteners of the formula (I) are known substances and can be obtained by known methods, as described in the examples.

These dispersions are prepared without the use of any dispersant or stabilizing agents, and nevertheless are a hundred is safe during storage. It was completely unexpected, as in prior practice, such dispersion is always needed some supplements in order to obtain a stable suspension. Therefore, the next subject of the present invention is a method for preparing such dispersions, characterized in that the hot organic phase obtained in the synthesis of optical bleach, mix in cold water, allow it to cool to ambient temperature with continuous stirring, introducing a seed crystal of 0.1%-1% by weight. previously obtained dispersion, and finally diluted to the desired strength.

These dispersions are well suited for harmless optical bleaching of paper, textiles or other cellulosic bases due to the absence of possible interfering additives.

These dispersions can be added directly to a suspension of the cellulose pulp is usually in amounts of from 0.1 to 5%, preferably from 1 to 3% wt. calculated on dry fiber and used for the preparation of the paper web, which is then squeezed and dried.

These dispersions can also be added directly to water covering compositions which can be prepared by mixing chalk or other white pigments, one or more dispersing agents, the primary latex binder and possibly secondary is th binder and, possibly other additives. Usually used from 0.1 to 5%, preferably from 1 to 3% wt. calculated on dry fiber of the present dispersions for covering composition, which is then applied to the paper and then dried coated paper web.

The following examples explain in more detail the present invention.

EXAMPLES

Unless otherwise specified, % means % by mass.

Total synthesis

Synthesis suspensions optical bleach (PA) is conducted in water. The acid chloride cyanuric acid are suspended in water containing a wetting agent and ice. Add an aqueous solution of 4, 4'-diamino-2,2'-silencelevel acid at 0C.-5C., maintaining the pH of 4-6 diluted sodium hydroxide solution. After the addition completed, the reaction mixture was stirred additionally for one hour, allowing the temperature to rise to ~10C. Then add aniline and the reaction mixture is slowly heated to 60C., maintaining the pH 6-8 by the addition of dilute sodium hydroxide solution. Then the reaction mixture is stirred for a further one hour at 80C and add the product of the merger of monoethanolamine and acrylamide. The reaction mixture is heated to boiling under reflux and maintain pH 8-9 by the addition of dilute sodium hydroxide solution. After the reaction completed, the mixture is cooled to 8C - 90C and the stirrer is stopped. The lower organic oily layer is poured with stirring in enough cold water to get the concentration of active substances 20-40%. The mixture is stirred and cooled to ambient temperature and introducing a seed crystal of 0.5% previously prepared dispersion. The product crystallizes in the form of a dense dispersion. This dispersion is stirred for 5 to 12 hours and diluted with cold water to the desired potency. The stirring is continued for another hour and a dispersion of optical Brightener is Packed in containers.

Example 1

Hot oil with end-stage reaction (500 g active substance 51%) was added under stirring to 411 ml of cold water. Formed a solution which contains 28% of the active NGO analysis of the intensity of the UV spectrum. This solution was cooled with stirring to ambient temperature (20-25C) and were introduced 50 g of seed of a previously prepared dispersion, during the period of cooling OO, distilled and the mixture thickens. Stirring was continued for 5 hours and then the thick suspension was diluted by the addition of 390 ml of cold water and stirring is continued for another one hour. This gives a dispersion with a content of active substances of 20%. The dispersion has a pale yellow color and, although there is a small loss of sieges is and for a period of several weeks, the dispersion is easily restored weak mixing.

Example 2

Repeating example 1, but this time added to 1.14 g of non (Dispelair CF531 from Blackburn Chemicals) together with 1,14 g of biocide (Nipacide CFB).

EXAMPLE 3:The input paper weight

Method And

200 g of a suspension of paper pulp (2.5% aqueous suspension of a 50%mixture of pulps bleached soft wood and hard wood, crushed to the consistency of grind about 20SR) (SR means Schopper Riegler, this reference measurement in the paper industry measures the difficulty with which water drains from the pulp) is measured into a beaker and stirred. The suspension was stirred for one minute and add to p% of the product of example 1 (R=0,1; 0,2; 0,4; 0,8; 1,0, 1,4; 1,8 and 2.0; p=0 represents the control). After the addition the mixture was stirred for a further one minute. The mixture is then diluted to one liter and formed sheet of paper on a lab machine for the manufacture of paper (this is essentially a cylinder with a wire mesh at the bottom of the cylinder partially filled with water, add a suspension of paper pulp, then blown off with air to ensure that the pulp is well dispersed, then use the vacuum and the suspension of the pulp stretch through the wire, leaving a paper sheet, this sheet is removed from the wire, squeezed and dried). The sheet is left in a humid chamber to achieve is Asia and then measure the whiteness, using the Minolta spectrophotometer CM-700d. The measured values showed an unexpectedly high degree of whiteness and exit.

Table 1
The input results in the paper mass (Method A)
The concentration of dry fiber, %White CIE standard OOWhite CIE
the product of example 1
077,477,4
0,2118,1118,3
0,4for 125.8125,6
0,8137,8137,2
1,2140,7to 140.5
1,6145144,9
2147,1147,9

EXAMPLE 4:Enter in the floor

Prepared covering composition containing 3000 parts of chalk (small white high-purity calcium carbonate with a density of 2.7 ISO 787/10 available in PR is even under the trade name HYDROCARB 90 from OMYA), 1932 parts of water, 16 parts of an anionic dispersing agent (such as Polysaltz S from BASF) and 600 parts of latex (commercially available under the trademark Latex XZ 95085,01 from Dow Chemicals). To covering of the composition was added with stirring a specified amount of the product of example 2 (0; 0,313; 0,625; 0,938; 1,25 and 1,875 mmol/kg relative to the optical bleach) and the solids content was brought to 55% by adding water. Then thus prepared covering the composition was applied on a sheet basis bleached technical paper (75 g/m2with a neutral primer (with the usual dimer of alkylbetaine)using automatic wire rod applicator with custom speed setting and a standard load on the rod. The paper with the coating was dried for 5 minutes at 70C in a stream of hot air. The dried paper was allowed to air-conditioned, and then measured the brightness CIE, using a calibrated spectrophotometer Minolta CM-700d. The measured values showed an unexpectedly high degree of whiteness and exit.

Table 2
The input results in the coating of example 2
Concentration per dry pigment, %White CIE standard GSBe the out of CIE product of example 1
092,492,4
096,496,8
1100,5100,1
1,5101,8102
2101101,1
399,6100

These dispersion showed excellent bleaching properties.

1. Storable aqueous dispersion optical bleach, do not contain dispersing agents and stabilizers, characterized in that it contains 20-40% of the active substance representing one or more optical brighteners, obtained by the sequential interaction of the acid chloride cyanuric acid with 4,4'-diamino-2,2'-stilbenederivatives, aniline and the product of the interaction of monoethanolamine with acrylamide.

2. The dispersion according to claim 1, containing from 10 to 40 wt.% the active substance.

3. The dispersion according to claim 2, containing from 14 to 26 wt.% the active substance.

4. The dispersion according to claim 1, additionally containing from 0.01 to 0.5 wt.% antispyware is, or biocide, or both compounds in the indicated amounts.

5. The method of preparation of a dispersion according to any one of claims 1 to 4, characterized in that the hot organic phase obtained in the synthesis of optical Brightener using the acid chloride cyanuric acid, 4,4'-diamino-2,2'-silentologist, aniline and the product of the interaction of monoethanolamine with acrylamide, mix in cold water, allow it to cool to ambient temperature with continuous stirring, introducing a seed crystal of 0.1-1 wt.% previously obtained dispersion and further diluted up to 20-40%concentration.

6. The use of a dispersion according to any one of claims 1 to 4 for optical bleaching of paper or other cellulosic bases.

7. The method of bleaching paper that includes the following basic stages:
preparation of a suspension of pulp;
adding from 0.1 to 5 wt.% calculated on dry fiber dispersion according to any one of claims 1 to 4;
the preparation of the paper web from the specified suspension of pulp;
extraction and drying cloths.

8. The method of bleaching paper that includes the following basic stages:
the preparation of an aqueous coating composition by mixing chalk or other white pigments, one or more dispersing agents, the primary latex binder and possibly secondary binder and, perhaps, others the other additives;
adding from 0.1 to 5 wt.% calculated on dry fiber dispersion according to any one of claims 1 to 4;
application covering the composition to the paper web;
drying the coated paper web.



 

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