EP1355004A1 - Use of optical brighteners for the manufacturing of coating mixes - Google Patents

Abstract

Use is claimed of bis(aminotriazinyl)-stilbene optical brighteners in brightening aqueous sizing or coating compositions containing a latex binder and a different synthetic co-binder. Use is claimed of bis(aminotriazinyl)-stilbene optical brighteners of formula (I) in brightening aqueous sizing or coating compositions containing a latex binder and a different synthetic co-binder. Y = a group of formula (II) or (III); R1 = 1-6C alkyl and R2 = H or vice-versa; (R1)/ = 1-6C alkyl and (R2)/ = H or vice-versa; R3 and (R3)/ = H, methyl, ethyl, CH2CH2OH or CH2CH2OCH3; R4 = 1-4C alkyl; Z' = H or SO3H in the o-, m- or p-position; and M = H or an equivalent of a cation which is Li, Na, K, Ca, Mg, ammonium or mono-, di-, tri- or tetra-(1-4C alkyl or 2-4C hydroxyalkyl)-ammonium. An Independent claim is also included for a sizing or coating composition comprising the above bis(aminotriazinyl)-stilbene optical brightener together with a white pigment, a latex binder and a different synthetic co-binder.

Description

The invention relates to the use of special brighteners for the production of coating slips, coating slips per se and their use for the production lightened papers.

Optical brighteners are mainly used for whitening paper, textiles or used as an additive to detergents. The white tint of uncoated paper or coating base papers can by mass application and / or surface application of optical brighteners, which are usually available in dissolved form. When producing coated papers, the addition of optical brighteners is necessary Brush color usual, so that the optical brightener when finished coated Paper is also located in the pigment layer applied to the paper. Painted Papers are particularly suitable for making high-quality prints. Besides good ones Printability properties are therefore mainly based on optical quality Properties such as gloss and whiteness are assessed. There is a continuing trend towards coated papers with high degrees of whiteness and therefore the desire for as much as possible effective optical brighteners as coating color components.

worin

(Disulfotyp), oder

(Tetrasulfotyp), oder

(Hexasulfotyp) und

M

für Na, K oder gegebenenfalls substituiertes Ammonium steht.

The most common and most widespread paper brighteners are those of the formula (I)

wherein

(Disulfotype), or

(Tetrasulfotype), or

(Hexasulfotyp) and

M

represents Na, K or optionally substituted ammonium.

Comparing the use of the so-called tetrasulfotype shown in formula (I) and Hexasulfotyps in the paper line, this is evident from certain amounts of brightener added of the tetrasulf type a saturation behavior with regard to the CIE whiteness. That Larger amounts do not lead to any further whiteness build-up can even have a negative impact on the CIE whiteness. This saturation behavior usually occurs when using the hexasulfotype at significantly higher ones Amounts used compared to the Tetrasulfotype. This can brighten up with hexasulfoflavonate Generally higher degrees of whiteness can be achieved than with tetrasulfoflavonate brighteners. The effect of saturation is also called greening. The greening limit, i.e. the point at which increasing amounts of brightener are used practically no longer increase the degree of whiteness, e.g. from the a * b * diagram are derived, where a * and b * are the color coordinates in the CIELab system are.

Since the greening of hexasulfotypes only occurs with relatively high amounts, the hexasulfoflavonate brightener shown in formula (I) is also suitable especially for the production of coated, bright white papers. The exact amounts used, in which the greening occurs with tetra- or hexasulfoflavonate brighteners, depend on the composition of the respective coating color, including of their Carrier salary from.

When recycling coated papers, e.g. when reusing coated board in the paper mill, the coated paper is opened again, the non-fiber-fixed brightener from the line initially in Solution goes and partially pulls on paper fibers. In this context the increased solubility of the hexasulfoflavonate brightener disadvantageous because it is not more fiber-fixed Brightener in the circulation water of the paper machine as an anionic contaminant acts and the effect of cationic paper chemicals such as retention agents or mass sizing agents reduced, so that an additional consumption of these Paper chemicals result.

There is therefore a desire for improved optical brighteners for whitening of coating colors, especially paper coating colors, with which higher degrees of whiteness than using conventional di- and tetrasulfotypes, e.g. the one in formula (I) shown, can be realized, but on the other hand coated during recycling Papers lead to less contamination in the circulation water of the paper machine as hexasulfotypes.

In particular, the lightening of brush colors based on synthetic stands Cobinder in the foreground. Natural cobinders, especially starch, are due their swelling behavior when in contact with aqueous liquids is bad for Top or single lines are suitable. Due to the swelling when printing of the coated paper reduces the quality of the printed image. Therefore strength becomes preferably used as a co-binder in primers for multi-coated papers. while with plain coated papers or top coats synthetic Cobinder are preferred. For single and top coats, the white claims are generally higher than primers.

Surprisingly, it has now been found that a certain class of bistriazinyl flavonate brighteners with 2 or 4 sulfo groups, these requirements are outstanding Way in coating color systems containing synthetic cobinder Fulfills.

EP-A 192 600 describes that certain brightener formulations containing polyethylene glycol particularly suitable as coating color additives. However only latex binders in combination with natural co-binders for coating slips used explicitly.

worin

Y

ein Rest der Formel

oder

bedeutet und

R¹

für C₁-C₆-Alkyl und

R²

für H, oder

R¹

für H und

R²

für C₁-C₆-Alkyl steht, und unabhängig davon

R³

für H, Methyl, Ethyl, CH₂CH₂OH oder CH₂CH₂OCH₃ steht,

R^1'

für C₁-C₆-Alkyl und

R^2'

für H, oder

R^1'

für H und

R^2'

für C₁-C₆-Alkyl steht, und unabhängig davon

R^3'

für H, Methyl, Ethyl, CH₂CH₂OH, CH₂CH₂OCH₃ sowie

R⁴

für C₁-C₄-Alkyl stehen

Z

H oder SO₃M bedeutet, wobei die Sulfogruppen in o-, m- oder p-Position stehen können und

M

H oder ein Äquivalent eines Kations bedeutet, ausgewählt aus der Gruppe Li, Na, K, Ca, Mg, Ammonium oder Ammonium, welches mono-, di-, tri- oder tetrasubstituiert ist durch die Reste C₁-C₄-Alkyl oder C₂-C₄-Hydroxyalkyl

zum Aufhellen von wässrigen Streichmassen enthaltend wenigstens einen Latex-Binder und wenigstens einen davon verschiedenen synthetischen Cobinder.The invention therefore relates to the use of optical brighteners of the formula (II),

wherein

Y

a rest of the formula

or

means and

R ¹

for C ₁ -C ₆ alkyl and

R ²

for H, or

R ¹

for H and

R ²

represents C ₁ -C ₆ alkyl, and independently of it

R ³

represents H, methyl, ethyl, CH ₂ CH ₂ OH or CH ₂ CH ₂ OCH ₃ ,

R ^{1 '}

for C ₁ -C ₆ alkyl and

R ^{2 '}

for H, or

R ^{1 '}

for H and

R ^{2 '}

represents C ₁ -C ₆ alkyl, and independently of it

R ^{3 '}

for H, methyl, ethyl, CH ₂ CH ₂ OH, CH ₂ CH ₂ OCH ₃ as well

R ⁴

represent C ₁ -C ₄ alkyl

Z

H or SO ₃ M means, where the sulfo groups can be in the o-, m- or p-position and

M

H or an equivalent of a cation selected from the group Li, Na, K, Ca, Mg, ammonium or ammonium, which is mono-, di-, tri- or tetrasubstituted by the radicals C ₁ -C ₄ alkyl or C ₂ -C ₄ hydroxyalkyl

for lightening aqueous coating slips containing at least one latex binder and at least one synthetic cobinder different therefrom.

In a preferred embodiment, the synthetic cobinder is not a latex binder.

With regard to the brightener of the formula (II), there are also mixtures of the abovementioned Possibilities for M in question.

The optical brighteners of the formula (II) are preferred with R ¹ = H, R ² = linear C ₁ -C ₆ alkyl and R ³ = H; continue with the optical brighteners of formula (II) R ^{1 '} = H, R ^{2 '} = linear C ₁ -C ₆ alkyl and R ^{3 '} = H and R ⁴ = H, methyl.

worin

M

die oben angegebene Bedeutung hat.

The use of the optical brightener of the formula (IIa) is particularly preferred,

wherein

M

has the meaning given above.

The particularly preferred brightener of formula (IIa) and related structures are known per se. GB-A 896 533 describes the production of this Brighteners and the use in mass and size press use for Whites of paper.

The brighteners used according to the invention can be used as an aqueous solution essentially dissolved brightener salts, water and optionally adjusting agents contains. They can also be used as aqueous carriers Formulations are used which are essentially dissolved brightener salts, Contain water and carrier substances.

It is also possible to use the brighteners used according to the invention in solid form, e.g. as powder or granules. It is advantageous if the Brighten the brightener before applying the coating color. The process of solving the When using powder or granules, the brightener can be applied Coating color.

The brighteners used according to the invention are produced by known ones Methods such as in GB-A 896 533 and in EP-A 860 437 are, for example from about 2 mol of cyanuric chloride, about 1 mol of 4,4'-diaminostilbene-2,2'-disulfonic acid or a corresponding salt, approx. 2 mol aniline, sulfanilic acid or a corresponding salt and about 2-2.5 mol of the substituent Y corresponding amines. After the reaction has ended, the crude solution of the appropriate brighteners e.g. desalted by suitable membrane separation processes and be concentrated, e.g. are described in EP-A-992 547. Preferred membrane separation processes are ultrafiltration, diffusion dialysis and electrodialysis. But it is also possible to use the resulting brightener as Isolate solid, e.g. by salting out or acid addition and precipitation as Dyeacid. The resulting solid can then e.g. isolated on a filter press and optionally further cleaned by washing.

The brightener can be used to produce the brightener preparation used also from solution e.g. isolated by spray drying in the form of a powder are, where appropriate, further additives such as dispersing agents, Dedusting agents etc. are added.

Aqueous preparations can be made from raw, concentrated and desalinated solutions Solutions or be made from water-containing press cake. For special good whiteness build-up it is advantageous in the aqueous brightener preparations to incorporate so-called carrier substances.

a) 10 bis 40 Gew.-% wenigstens eines Aufhellers der Formel (II),

b) 0 bis 30 Gew.-% Stellmittel

c) 0 bis 2 Gew.-% anorganische Salze und

d) 23 bis 90 Gew.-% Wasser,

wobei die Summe der Komponenten a) bis d) 95 bis 100 Gew.-%, bezogen auf die Präparation, beträgt.The aqueous brightener preparations preferably contain

a) 10 to 40% by weight of at least one brightener of the formula (II),

b) 0 to 30% by weight of adjusting agent

c) 0 to 2 wt .-% inorganic salts and

d) 23 to 90% by weight of water,

the sum of components a) to d) being 95 to 100% by weight, based on the preparation.

Usual actuators are e.g. Urea, diethylene glycol, triethylene glycol, propanediol, Glycerin, ε-caprolactam, ethanolamine, diethanolamine and triethanolamine. Preparations free of adjusting agents are preferred in each case.

a) 5 bis 40 Gew.-% wenigstens eines Aufhellers der Formel (II)

b) 1 bis 50 % Gew.-% wenigstens einer Carriersubstanz

c) 0 bis 2 Gew.-% anorganische Salze und

d) 3 bis 94 Gew.-% Wasser

wobei die Summe der Komponenten a) bis d) 95 bis 100 Gew.-%, bezogen auf die Präparation, beträgt.The aqueous brightener preparations also preferably contain:

a) 5 to 40% by weight of at least one brightener of the formula (II)

b) 1 to 50% by weight of at least one carrier substance

c) 0 to 2 wt .-% inorganic salts and

d) 3 to 94% by weight of water

the sum of components a) to d) being 95 to 100% by weight, based on the preparation.

Generally speaking, the carrier substances are hydrophilic polymers with the ability to Formation of hydrogen bonds in question. Preferred carrier substances are polyvinyl alcohols, carboxymethyl celluloses and polyethylene glycols a number average molecular weight of 200 to 8000 g / mol, as well as any Mixtures of these substances, these polymers being modified where appropriate could be. Preferred polyvinyl alcohols are those with a degree of hydrolysis > 85%, preferred carboxymethyl celluloses those with a degree of substitution DS of> 0.5. Polyethylene glycols with a number average are particularly preferred Molecular weight Mn from 200 to 8000 g / mol.

Furthermore, e.g. native, derivatized or degraded starches, alginates, Casein, proteins, polyacrylamides, polyacrylic acids, hydroxyalkyl cellulose as well Polyvinyl pyrrolidone in question.

With such formulations, regardless of the carrier content in the coating color As a rule, cheaper whiteness build-up curves can be realized than with carrier-free brightener preparations.

In addition, in the carrier-free as well as carrier-containing preparations in smaller Amounts, usually in amounts below 5% by weight, of other auxiliaries such as e.g. Dispersing agents, thickeners, antifreezes, preservatives, complexing agents etc. or organic by-products from the brightener synthesis, which at the workup was not completely removed.

In the carrier-containing preparations, adjusting agents can also be used for increasing of solubility and storage stability.

The carrier-free aqueous brightener preparations are generally produced here. by adjusting a brightener solution (raw or membrane filtered) with a base a neutral to weakly alkaline pH, if necessary addition and dissolution one or more adjusting agents and, if necessary, dilution with water the desired final concentration. The brightener is in the form of a water moist Press cake used, a certain amount of press cake is submerged in water Base addition, stirring and possibly elevated temperatures completely dissolved and if necessary by further water addition to the desired concentration set.

Preferred bases for this are alkali metal hydroxides, demineralized for dilution Water preferred. The set pH is in the range from 7 to 11, preferably from 8 to 10. Temperatures of 25 to 80 ° C. are customary for dissolution.

The preparation of the carrier-containing preparations is generally carried out. in an analogous way, in addition, the carrier substance at any point in the manufacturing process is added. If the carrier substance is added in solid form, it becomes I. A. completely dissolved with stirring and possibly elevated temperatures, so that a homogeneous liquid preparation is created. The viscosity is preferably of the carrier-containing preparations at room temperature <3000 mPas. The usual The dissolving temperature is in the range from 25 to 100 ° C.

Concentrated, aqueous brightener preparations are usually made by the characterized the so-called E1 / 1 value. For this purpose, the extinction of a very diluted Solution of the preparation according to the usual and known to the expert Methods of UV / Vis spectroscopy in a 1 cm cuvette for a specific one Wavelength determined. This wavelength corresponds to the long-wave absorption maximum of the respective brightener molecule. For flavonate brighteners it is approx. 350 nm. The E1 / 1 value then corresponds to the fictitious one-percent solution extrapolated extinction value.

The E1 / 1 values of the brightener preparations used according to the invention are preferably between 50 and 180, particularly preferably between 70 and 140.

The coating slips to be lightened according to the invention contain, for example, as latex binders Latices based on styrene-butadiene, styrene-acrylate or vinyl acetate. These polymers can optionally be replaced by other monomers such as acrylonitrile, Acrylamide, α, β- unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid or maleic acid, acrylates, vinyl esters, ethylene, vinyl chloride, vinylidene chloride etc. be modified. Generally, however, all common latex binders come used for the production of paper coating slips in question. As of it various synthetic cobinders contain the coating slips, for example Carboxymethyl cellulose, hydroxyalkyl cellulose and / or polyvinyl alcohol as well synthetic thickener based on acrylate.

Preferred latex binders are those based on styrene-butadiene. Preferred synthetic Cobinders are polyvinyl alcohols, especially those with a degree of hydrolysis of> 85%, and in particular a Brookfield viscosity of 2-80 mPas (measured on a 4% aqueous solution at 20 ° C.) carboxymethyl celluloses, in particular those with a degree of substitution of> 0.5, and in particular one Brookfield viscosity of 5-5000 mPas (measured on a 2% aqueous Solution at 25 ° C) and mixtures of these two substances.

The coating slips to be lightened according to the invention preferably further contain White pigments.

Calcium carbonate in natural or precipitated form, kaolin, talc, titanium dioxide, satin white, aluminum hydroxide and Barium sulfate used, often in the form of mixtures.

As, if necessary, further ingredients to be lightened according to the invention Spreaders should first be mentioned as dispersants. Polyacrylates are common here, Polyphosphates or Na citrate. In principle, polyaspartic acid is also suitable. Other possible additives are crosslinkers. Examples include urea-formaldehyde resins, Melamine formaldehyde resins, glyoxal or ammonium zirconium carbonate. In principle, wet strength agents based on polyamide amine-epichlorohydrin resins also come glyoxalized polyacrylamides or hydrophilized polyisocyanates, such as. described in EP-A-825 181, as a crosslinker in question. Finally, other possible additives are defoamers, biocides, Complexing agents, bases for pH adjustment, Ca stearate, other optical brighteners than that of formula (II) and shading dyes. Sometimes become Hydrophobization of the coating color also added to surface sizing agents. Examples for this are polymer solutions based on styrene-acrylic acid, styrene-maleic anhydride or oligourethanes, and polymer dispersions based on acrylonitrile acrylate or styrene acrylate. The latter are e.g. in WO-A-99/42490 described.

The coating slips to be lightened according to the invention preferably contain the latex binder in an amount of 3 to 20% by weight and the synthetic cobinder in an amount of 0.1 to 3 wt .-%, each based on the white pigment Coating slip.

• wenigstens ein Weißpigment
• wenigstens einen Latex-Binder
• wenigstens einen davon verschiedenen synthetischen Cobinder und
• wenigstens einen Aufheller der Formel (II).

The invention further relates to an aqueous coating slip, ie containing an aqueous pigment preparation

• at least one white pigment
• at least one latex binder
• at least one different synthetic cobinder and
• at least one brightener of the formula (II).

The amount of latex binder (calculated as dry substance) is preferably 3 to 20 wt .-%, in particular 5 to 15 wt .-%, regardless of the amount of Cobinder 0.1 to 3 wt .-%, in particular 0.5 to 1.5 wt .-% and also independently of this, the amount of brightener of the formula (II) 0.025 to 1% by weight, each based on the amount of white pigment.

The preferred embodiments for white pigment, latex binder, Cobinder, brightener and other additives as described above.

The coating slip preferably additionally contains at least one dispersant, in particular in an amount of 0.05 to 1 wt .-%, based on the white pigment in the coating slip. The preferred dispersing agent is polyacrylic acid or corresponding salts in question. The water content of the coating slip is preferred 30 to 50 wt .-%, based on the total amount of coating slip.

The invention further relates to the use of the coating slips according to the invention for the production of coated papers.

The coating slips can preferably be used once or several times with all of them suitable application methods are applied to the paper, e.g. With Squeegees in various designs, air brush, blade, roll coater, film press, Cast coating processes etc. The immobilization and drying of the coating color usually takes place initially by contactless hot air and / or IR drying, which is usually followed by contact drying using heated rollers followed. After that, there is usually a satin finish for compression, smoothing or gloss influence of the coated paper e.g. carried out with a calender.

Suitable as uncoated base papers or base papers, cardboards and boxes principally consist of bleached or unbleached, wood-containing or wood-free, Papers, cardboards and boxes made from waste paper and deinked fibrous materials. These can continue to contain mineral fillers such as natural or precipitated Contain chalk, kaolin, talc or annaline. The uncoated papers, Cardboards and boxes can be glued in the mass and / or surface, whereby et al the penetration and the adhesion of the coating color are influenced. usual Bulk sizing agents are alkyl ketene dimer (AKD), alkenyl succinic anhydride (ASA) or a combination of resin glue and alum, common surface sizing agents the above-mentioned polymer solutions based on styrene-acrylic acid, Styrene-maleic anhydride or oligourethanes, as well as polymer dispersions based on acrylonitrile acrylate or styrene acrylate. To control the desired white properties of the resulting coated paper can Base papers are lightened in mass and / or surface, for which purpose e.g. Flavonataufheller to be used.

Examples example 1

77.6 g of a membrane-filtered aqueous concentrate with an E1 / 1 value of 161 and a pH of 8.5, which contains the brightener of the formula (IIa) as Na salt, be with 22 g of demineralized water while stirring at room temperature added and adjusted to pH 9.0 with approx. 10% sodium hydroxide solution. You get one carrier-free brightener preparation with an E1 / 1 value of 125 in the form of a yellow-brownish, homogeneous liquid. This corresponds to a (IIa) content of approx. 23 Wt .-%.

Example 2

65.2 g of a membrane-filtered aqueous concentrate with an E1 / 1 value of 161 and a pH of 8.5, which contains the brightener of the formula (IIa) as Na salt, are stirred with 31 g of polyethylene glycol 1550 (medium Molecular weight Mn 1550 g / mol) added. This becomes waxy at room temperature Polyethylene glycol 1550 heated to approx. 60 ° C before addition, melted in the process, and added as a liquid approx. 60 ° C hot. 3.5 g are still used demineralized water and adjust the pH with approx. 10% sodium hydroxide solution to 9.0. The preparation is then heated to 50 ° C. with stirring and at 30 min this temperature stirred. After cooling to room temperature, one is obtained carrier-containing brightener preparation with an E1 / 1 value of 105 in the form of a yellow-brownish, fluorescent, homogeneous liquid. This corresponds to a salary of (IIa) of approx. 19% by weight.

Example 3 (not according to the invention)

64,8 g eines membranfiltrierten wässrigen Konzentrats mit einem E1/1-Wert von 162 und einem pH-Wert von 8,6, das den Tetrasulfotyp-Aufheller der Formel (I) als Na-Salz enthält

31 g Polyethylenglykol 1550

4 g demineralisiertes Wasser.

The procedure is as in Example 2, but using a different brightener type and using the following amounts:

64.8 g of a membrane-filtered aqueous concentrate with an E 1/1 value of 162 and a pH value of 8.6, which contains the tetrasulfotype brightener of the formula (I) as Na salt

31 g polyethylene glycol 1550

4 g demineralized water.

A carrier-containing brightener preparation with an E1 / 1 value of 105 is obtained and a pH of 9.0 in the form of a yellow-brownish, fluorescent, homogeneous liquid. This corresponds to a content of the tetrasulfotype brightener of about 18% by weight.

Example 4 (not according to the invention)

The procedure is as in Example 1, but the Tetrasulfotype is used as the brightener Formula (I) as Na salt.

The brightener preparation has an E 1/1 value of 125. This corresponds to one Brightener content of approx. 21% by weight.

Application example 1 :

100 Teile Weißpigment (Kreide-Kaolin-Mischung)

6,5 Teile Baystal P7110 als Binder, gerechnet als Trockensubstanz (Styrol-Butadien-Latex der Polymerlatex GmbH)

1,5 Teile Finnfix 10 als synthetischen Cobinder (Carboxymethylcellulose der Firma Noviant)

0,25 Teile Polysalz® S als Dispergiermittel auf Basis von Polyacrylsäure (BASF AG) Wasser

10-%ige Natronlauge.

A paper coating slip is made from the following components:

100 parts white pigment (chalk-kaolin mixture)

6.5 parts of Baystal P7110 as a binder, calculated as dry matter (styrene-butadiene latex from Polymerlatex GmbH)

1.5 parts of Finnfix 10 as a synthetic cobinder (carboxymethyl cellulose from Noviant)

0.25 part of Polysalz® S as a dispersant based on polyacrylic acid (BASF AG) water

10% sodium hydroxide solution.

The CMC Finnfix 10 used has an active content of 98%. The Brookfield viscosity a 4% solution, measured at 25 ° C, is 50-200 mPas.

The amount of water and caustic soda is chosen so that a solids content of 57%. and a pH of 9.0 results.

The coating slip is divided into 10 parts and one part each with 0.4%, 0.8%, 1.2%, 1.6% and 1.8% of the brightener preparation from Example 1 were added and then 10 min stirred. The amounts added relate to the solids content of the Coating slip. For comparison, part of the coating slip is made in the same way with the same amounts of the brightener preparation from Example 4.

The lightened coating slips obtained are applied with a laboratory doctor device (Erichsen, K-Control-Coater, model K 202) to wood-free base papers with a basis weight of approx. 80 g / m ² . The coated papers are dried for 1 min at 95 ° C on a drying cylinder and then stored for 3 h at 23 ° C and 50% relative humidity. The measurement of the parameters L *, a *, b * and the determination of the CIE whiteness is then carried out using a whiteness measuring device (Datacolor Elrepho 2000).

The values obtained are listed in Tables 1 and 2. Brightener preparation from example 1 (E1 / 1 = 125) Quantity (%) CIE whiteness L * a * b * 0.4 101.80 94.12 0.81 -3.60 0.8 108.00 94.24 1.11 -4.89 1.2 111.50 94.34 1.26 -5.63 1.6 114.50 94.42 1.34 -6.25 1.8 116.10 94.46 1.37 -6.62 Brightener preparation from example 4 (E1 / 1 = 125) Quantity (%) CIE whiteness L * a * b * 0.4 102.10 94.11 0.74 -3.69 0.8 107.70 94.33 0.97 -4.81 1.2 110.04 94.43 0.98 -5.36 1.6 113.30 94.55 0.97 -5.96 1.8 113.50 94.60 0.90 -6.04

It can be seen that when E1 / 1 is used in the same way, the one used according to the invention Brightener in the carboxymethyl cellulose-containing coating color for better CIE whiteness values leads to that from example 4. From the a * -b * values continues to derive from the fact that in the tetrate type not according to the invention the greening from 1.6% uses, while this when using the brightener according to the invention Example 1 to 1.8% is not yet recognizable.

Example of use 2 :

The procedure is as in Application Example 1, but a polyvinyl alcohol-containing one is used Spreading compound of a different composition and uses the carrier-containing Brightener preparations from Examples 2 and 3 with respective additional amounts of 0.8%, 1.6%, 2.4% and 3.2%, based on the solids content of the Coating slip.

100 Teile Weißpigment (Kreide-Kaolin-Mischung)

7,5 Teile Baystal P 7110 als Binder, gerechnet als Trockensubstanz (Styrol-Butadien-Latex der Polymerlatex GmbH)

1 Teil Polyvinylalkohol als synthetischen Cobinder, gerechnet als Trockensubstanz

0,25 Teile Polysalz® S als Dispergiermittel (BASF AG)

Feststoffgehalt: 65 %, pH-Wert: 8,8.

Composition of the coating slip:

100 parts white pigment (chalk-kaolin mixture)

7.5 parts Baystal P 7110 as binder, calculated as dry matter (styrene-butadiene latex from Polymerlatex GmbH)

1 part of polyvinyl alcohol as synthetic cobinder, calculated as dry matter

0.25 part of Polysalz® S as a dispersant (BASF AG)

Solids content: 65%, pH: 8.8.

Polyviol LL 603 (Wacker-Chemie) was used as the polyvinyl alcohol. It is a 20% aqueous solution of a polyvinyl alcohol with Degree of hydrolysis 88%, which has a Brookfield viscosity of approx. 900 mPas at 20 ° C having.

The coating slip is divided into 8 parts and one part each with the above Amounts of the brightener preparations from Examples 2 and 3 were added.

The whiteness parameters of the papers obtained are shown in Tables 3 and 4. Brightener preparation from example 2 (E1 / 1 = 105) Quantity (%) CIE whiteness L * a * b * 0.8 97.90 94,30 1.15 -2.68 1.6 107.10 94.52 1.59 -4.59 2.4 111.50 94.62 1.83 -5.53 3.2 114.60 94.73 2.02 -6.16 Brightener preparation from example 3 (E1 / 1 = 105) Quantity (%) CIE whiteness L * a * b * 0.8 98.70 94.41 1.13 -2.79 1.6 104.50 94.55 1.27 -4.00 2.4 107.00 94.61 1.31 -4.52 3.2 109.70 94.73 1.42 -5.07

It can be seen that the brightener preparation according to the invention from Example 2 in the Coating paint containing polyvinyl alcohol significantly improved build-up behavior with respect to the CIE whiteness compared to that not according to the invention Preparation from Example 3.

Example of use 3 :

The procedure is as in Application Example 1, but a polyvinyl alcohol-containing one is used A coating of different composition and uses the brightener preparations from Example 1 in concentrations of 1%, 4.5% and 8% on the pigment content in the coating slip. Polyvinyl alcohol used was Polyviol® LL 603 (Wacker Chemie).

Composition of the coating slip:

100 Parts of kaolin 24 Parts Acronal® S 320 D (BASF AG) 8th Parts of polyvinyl alcohol, calculated as dry matter 0.3 Parts of Polysalz® s (BASF AG) 0.1 Part of NaOH water

The water content is chosen so that a solids content of 50% results.

The coating slip is in 3 parts and one part each with the amounts specified above the brightener preparation from Example 1.

The whiteness parameters of the papers obtained are shown in Table 5.

Example of use 4:

The procedure is as in Application Example 3, but the coating slip is used instead of 8 Parts of polyvinyl alcohol 8 parts of carboxymethyl cellulose Finnfix® 10 (Noviant) on.

The whiteness parameters of the papers obtained are shown in Table 5.

Comparative example (analogous to example C 1 of EP 192 600):

1 part, 4.5 parts and 8 parts (based on pigment) of the brightener preparation from Example 1 are incorporated into an aqueous coating slip. the coating composition had the following composition: 100 Parts of kaolin 24 Parts Acronal® S 320 (BASF AG) 8th Parts of starch, calculated as dry matter 0.3 Parts of Polysalz® S (BASF AG) 0.1 Part of NaOH water

The water content is chosen so that a solids content of 50% results.

Papers are coated with the coating slips thus obtained and their whiteness parameters are determined in accordance with the procedure described in Application Example 1. The results are shown in Table 5. Brightener preparation from example 1 (E1 / 1 = 125) Quantity (% based on pigment) CIE whiteness L * a * b * Application example 3 (coating slip containing polyvinyl alcohol): 1.0 106.10 94,10 1.29 -4.53 4.5 117.0 94.35 1.85 -6.81 8.0 120.6 94.43 1.97 -7.59 Application example 4 (coating color containing CMC): 1.0 101.7 93.98 0.85 -3.60 4.5 109.2 94.16 1.17 -5.17 8.0 114.6 94.23 1.26 -6.34 Comparative example (starchy coating color): 1.0 98.3 93.93 0.67 -2.89 4.5 103.8 94.18 0.71 -3.98 8.0 107.4 94.45 0.38 -4.63

It can be seen that the brightener preparation from Example 1 in a coating color, which contains polyvinyl alcohol or carboxymethyl cellulose as cobinder, too clearly leads to higher whiteness values than in a starch-containing coating color with the same Cobindergehalt.

Claims (10)

Use of optical brighteners of the formula (II)

wherein

Y

a rest of the formula

or

means and

R ¹

for C ₁ -C ₆ alkyl and

R ²

for H, or

R ¹

for H and

R ²

represents C ₁ -C ₆ alkyl, and independently of it

R ³

represents H, methyl, ethyl, CH ₂ CH ₂ OH or CH ₂ CH ₂ OCH ₃ ,

R ^{1 '}

for C ₁ -C ₆ alkyl and

R ^{2 '}

for H, or

R ^{1 '}

for H and

R ^{2 '}

represents C ₁ -C ₆ alkyl, and independently of it

R ^{3 '}

for H, methyl, ethyl, CH ₂ CH ₂ OH or CH ₂ CH ₂ OCH ₃ as well

R ⁴

represent C ₁ -C ₄ alkyl,

Z

H or SO ₃ M means, where the sulfo groups can be in the o-, m- or p-position and

M

H or an equivalent of a cation selected from the group Li, Na, K, Ca, Mg, ammonium or ammonium, which is mono-, di-, tri- or tetrasubstituted by the radicals C ₁ -C ₄ alkyl or C ₂ -C ₄ hydroxyalkyl,

for lightening aqueous coating slips containing at least one latex binder and at least one synthetic cobinder different therefrom. Use according to claim 1, characterized in that the brightener corresponds to the formula (IIa),

wherein

M

has the meaning given in claim 1.

Use according to claim 1, characterized in that at least one latex based on styrene-butadiene, styrene-acrylate or vinyl acetate is used as the latex binder. Use according to claim 1, characterized in that at least carboxymethyl cellulose, hydroxyalkyl cellulose, polyvinyl alcohol or synthetic acrylate-based thickeners are used as the synthetic cobinder. Use according to claim 1, characterized in that at least one based on styrene-butadiene is used as the latex binder and at least carboxymethyl cellulose and / or polyvinyl alcohol is used as the synthetic cobinder. Use according to claim 1, characterized in that the coating slip contains at least one white pigment. Use according to claim 1, characterized in that the coating slip contains the latex binder in an amount of 3 to 20% by weight, in particular 5 to 15% by weight, and the cobinder in an amount of 0.1 to 3% by weight. -%, in particular 0.5 to 1.5 wt .-%, each based on the amount of white pigment. Containing coating slip at least one white pigment at least one latex binder at least one different synthetic cobinder and at least one brightener of the formula (II),

wherein

Y

a rest of the formula

or

means and

R ¹

for C ₁ -C ₆ alkyl and

R ²

for H, or

R ¹

for H and

R ²

represents C ₁ -C ₆ alkyl, and independently of it

R ³

represents H, methyl, ethyl, CH ₂ CH ₂ OH or CH ₂ CH ₂ OCH ₃ ,

R ^{1 '}

for C ₁ -C ₆ alkyl and

R ^{2 '}

for H, or

R ^{1 '}

for H and

R ^{2 '}

represents C ₁ -C ₆ alkyl, and independently of it

R ^{3 '}

for H, methyl, ethyl, CH ₂ CH ₂ OH or CH ₂ CH ₂ OCH ₃ as well

R ⁴

represent C ₁ -C ₄ alkyl,

Z

H or SO ₃ M means, where the sulfo groups can be in the o-, m- or p-position and

M

H or an equivalent of a cation selected from the group Li, Na, K, Ca, Mg, ammonium or ammonium, which is mono-, di-, tri- or tetrasubstituted by the radicals C ₁ -C ₄ alkyl or C ₂ -C ₄ hydroxyalkyl.

Spreading composition according to claim 8, containing 3 to 20 wt .-%, in particular 5 to 15 wt .-% of latex binder 0.1 to 3% by weight, in particular 0.5 to 1.5% by weight, of cobinder 0.025 to 1% by weight of brightener of the formula (II) each based on the amount of white pigment. Use of the coating slip according to claim 8 for the production of coated Papers.