CA2029220A1

CA2029220A1 - Brightener-containing paper-coating compositions

Info

Publication number: CA2029220A1
Application number: CA002029220A
Authority: CA
Inventors: Florin Seng; Ernst Kysela; Joachim Konig; Erhard Schuffenhauer; Werner Bieber; Bernhardt Hunke
Original assignee: Bayer AG
Current assignee: Bayer AG
Priority date: 1989-11-04
Filing date: 1990-11-02
Publication date: 1991-05-05
Also published as: DE3936793A1; FI905412A0; EP0427040A1; JPH03152296A

Abstract

Abstract Paper-coating compositions containing compounds of the formula (I) wherein R1, R2, R3 and R5, R6, R7 denote H, F, Cl or CH3 and R4 and R8 denote H, O-C1-C4-alkyl, S-C1-C4-alkyl, SO2C1-C4-alkyl, CF3, OCF3 or SCF3, are inexpensive and are distin-guished by high brightness.

Description

-` 2~2~220 For optical brightening of coating compositions based on plastics dispersions, substantive anionic brighteners are normally employed. However, in the coating compositions, these brighteners show only very S unsatisfactory brightening effects, a very low greying limit and too little light-fastness.
It is generally known partially to solve the said difficulties by adding hydrophillic co-binders or car-riers to the coating composition. (Compare "Das Papier"
36 (1982), 66, DE-A-3,502,038 and EP-A-43,79~).
Although the brightening effect can be signifi-cantly improved in this way, the water sensitivity of the coated papers is increased at the same time.
It is also known (compare DE-A 3,112,435) to cause water-soluble brighteners to be absorbed on certain plastics such as, for example, urea resins or methylol resins, and to add these brightened plastics as a disper-sion to the paper coating composition.
Finally, it has been proposed (DE-A 3,643,215) to employ water-insoluble salts of anionic brighteners and long-chain fatty amines for paper coating. However, these proposals have so far been unable to gain acceptance because of their excessive costs or because of rheologi-cal difficulties.
It has now been found, surprisingly, that coating compositions for paper coating can be brightened without the said disadvantages, if brighteners of the formula Le A 27 229 - 1 --`~ 2~29220 Rl R5 R2 ~ -CH=CH ~ CH=CH ~ SR6 R3~ \~R7 -wherein - independently of one another - Rl, R2, R3 and R5, R6, R~ denote H, F, Cl or CH3 and R4 and RB denote H, O-C1-C4-alkyl, S-Cl-C4-alkyl, SO2Cl-C4-alkyl, CF3, OCF3 or SCF3, ; .
it also being possible for two adjacent radicals to represent -OCH2O- or -CH=CH-CH=CH-, are added to the coating compositions.
Preferably, the alkyl radicals represent methyl ~: radicals.
~he invention also relates to novel compounds of the formula I, wherein R4 and R8 F, CF3, OCF3 or SCF3 and the remaining radicals have ~he meaning given above, with the proviso that these radicals do not represent hydrogen if R4/R~
denote F or CF3.
The distyryl compounds of the formula ~I) can be prepared according to methods known per se by reacting a compound of the formula ..

: 20 zl ~ zl (II) in the desired ratio with in each case one compound of the formulae Le A 27 229 - 2 . , . ~ ~ , .

2 ~ z2 (IIIa) or 6 ~ z2 (IIIb), one of the symbols 71 and Zz in each case repre~enting a formyl group and the other representing a grouping of the formula o O
Il 11 -CH2-P(OR)2 -CH2-P-OR
:~ R
o R
Il I
-CH2-P-~ or -CH2-P-R
R R
wherein R denotes a C1-C4-alkyl, C5-C6-cycloalkyl or an option-ally further substituted aryl radical, preferably a phenyl radical.
In this way, symmetrical and un~ymmetrical compounds and mixtures of symmetrical and unsymmetrical compounds can be prepared.
The phosphorus compounds of the formulae (IIIa), (IIIb) and (II) reguired here as starting materials are : 15 obtained by reacting halogenomethyl compounds, preferably chloroethyl or bromomethyl compounds of the formulae i Le A 27 229 - 3 - ~

` 2~9~20 Rl R5 Hal or 7 ~ -CH2-Hal R R
and Hal-CH2 ~ H2-Hal :, with phosphorus compounds P(OR~ 3 ~ R-P(OR) 2 ~ RO-P(R) 2 or P(R)3, R having the meaning indicated. Preferably, R
denotes Cl-C4-alkyl if bound to oxygen, but phenyl if bound to phosphorus.
To prepare the final substances, the correspond-ing components are condensed in organic solvents in the presence of basic condensing agents.
The solvents selected are advantageously inert solvents, for example hydrocarbons such as toluene or xylene, or alcohols such as methanol, ethanol, isopropan-ol, butanol, glycol, glycol ethers such a~ 2-methoxy-ethanol, hexanol, cyclohexanol or cyclooctanol, and also ethers such as diisopropyl ether, dioxane or tetrahydro-furan; moreover formamides, N-methylpyrrolidone, dimethyl sulphoxide and phosphoric acid amide. Dimethylformamide, dimethylacetamide and phosphoric acid tris-dialkylamides, alkyl being in particular Cl-C4-alkyl, are preferred.
~he condensing agents used can be strongly basic compounds such as alkali metal hydroxides or alkaline earth metal hydroxides, alkali metal amides or alkaline earth metal amides and alkali metal alcoholates or Le A 2? 229 - 4 _ 2~29220 alkaline earth metal alcoholates, for example potassium hydroxide, sodium hydroxide, potassium tert.-butylate, sodium amide or sodium methylate, and also the alkali metal compounds of dimethyl sulphoxide and alkali metal hydrides as well as, if appropriate, alkali metal dispersions.
The reactions are preferably carried out in the temperature range from 0 to 120C.
The compounds (I) according to the invention are also obtained when the corresponding aldehyde anils are reacted in a dipolar aprotic solvent such as dimethyl-formamide in the presence of basic condensing agents with the corresponding methyl compounds.
In the dissolved or finely dispersed state, the compounds of the formula (I) show a very strong blue fluorescence. They are suitable, individually or as a mixture, for brightening the most diverse synthetic, semi-synthetic or natural organic materials.
Particularly preferred fields of application of the compounds and mixtures of the formula (I) is the use in paper-coating compositions.
The brighteners can be used as brightening agents directly or after preceding fine grinding or liquid formulating.
The liquid formulations can be prepared as follows:
The press cakes and/or powders are, after addition of a surface-active material and/or dispersant and optionally water, homogenized with vigorous stirring.
Subsequently, the quantity of these auxiliaries can be .
:

Le A 27 229 - 5 -', ~ ' ~: ' ' . ' ' - '~ ' , ' ' . ' . . ' , ' ' ~ 2~9220 increased op~ionally to the total quantity required for the stability of the dispersion.
The suspension obtained is then pre-comminuted and wet-ground.
The pre-comminution can be carried out by means of stone mills or toothed colloid mills.
The subsequent wet comminution can be carried out in colloid mills, oscillating mills, cone mills and vibro mills and also in dissolvers or in ball mills, or in sub-micron dispersers. Preferably, however, continuously running stirred mills with grinding bodies, preferably those of SiO2 of 0.1 to 5 mm, in particular 0.2-2 mm diameter, are used. The grinding ~tep is complete when a particle size of the product of < 5 ~m, preferably < 0.5 ~m has been reached.
After the grinding treatment, further quantities of surface-active materials or also hydrotropic substan-ces such as, for example, ethylene glycol or glycerol, preservatives, wetting agents, antifoams, dedusting agents and/or water can optionally also be added, unless this has already been done at an earlier point in time, for example before grinding.
The dispersions prepared by this process contain 5 to 50 %, preferably 10 to 30 % of the brightener salts according to the invention, which are sparingly soluble or insoluble in water, 1 to 50 %, preferably 5 to 20 % of surface-active materials or dispersants, 0 to 5 % of preservatives and water, it being possible for a part of the water to be replaced by hydrotropic substances (% =
per cent by weight).

Le A 27 229 - 6 -~29220 The surface-active materials used can be any conventional, cationic and nonionic surface-active materials such as are described, for example, in DE-OS
tGerman Published Specification) 2,334,769, pages 8 to 10 tcorresponds to British Patent Specification 1,417,071).
Preferably, nonionic surfactants are used.
Suitable anionic dispersants are conventional formalde-hyde condensation products of arylsulphonamines, sul-phonated diaryl ethers and diaryl sulphones and others.
The paper-coating compositions, in whiah the brighteners to be used according to the invention are incorporated, have the following structure: plastic dispersions based on styrene/butadiene copolymers, carboxylated styrene/butadiene copolymers or polyvinyl acetate copolymers or of acrylic acid esters in combina-tion with white pigment~, both without and with small quantities of hydrophilic co-binders.
The quantity of the compounds I employed depends on the desired brightening effect. In general, 0.01 to 0.5 % by weight of pure active substance (relative to the solids content of the paper-coating composition to be brightened) is sufficient. One particular advantage is that, depending on the composition of the coating com-positions, the attainable greying limit (up to which a 2S further addition of brightener still produces additional effects) is extremely high.

~e A 27 229 - 7 - ~
:' . ..

2~29220 Example 1 ~:H=CH~CH=CH~

a) 40 g (0.1 mol) of p-xylylene diathyl bisphosphona~e (93.4 % pure) are initially introduced together with 23.3 g (0.22 mol) of benzaldehyde into 100 ml of S dimethylformamide. To this, 39.6 g (0.22 mol) of a 30 ~ ~trength sodium methylate solution are added dropwise at room temperature under nitrogen. The mixture i8 stirred for 2 hours at room temperature and ~or a further 30 minutes at 60C. After cooling, the mixture is filtered with suction. This gives 19.8 g (70.2 %) of distyrylbenzene in the form of slightly yellow crystals which, after reprecipita-tion from toluene~Tonsil, melt at 173C. Extinction in DME~ = 355.9 nm; 6 = 6600.

b) 250 g of the crystalline brightener are mixed with 200 g of benzylphenylphenol with 14 ethylene oxide and 550 g of water and 3ubjected to a pre-comminu-tion on a corrundum disc mill and ground until an ~verage particle size of less than 50 ~m is ob-tained. Grinding i6 then continued with glass beads of 0.2 mm diameter in a stirred ~ilI down to an average particle size of less than 0.5 ~m. The fine dispersion obtained can immediately be incorporated into the paper-coating composition ready for application.

Le A 27 229 - 8 -20~9220 .

c) lS0 g of a formaldehyde condensation product of the Na salt of ditolyl ether-sulphonic acid and 550 g of water are added ~o 300 g of the crystalline bright-enex, and the mixture is treated as in Example lb.
After fine grinding, a further 200 g of the conden-sation product of formaldehyde and the Na salt of ditolyl ether-sulphonic acid and 200 g of the con-densation product of formaldehyde and the Na salt of naphthalenesulphonic acid as well as 50 g of a mineral oil emulsion (10 % aqueous) are added.

The suspension is then subjected to a spray-drying process and, at about 5 % residual moisture content, dried to give granules containing 30 ~ of active substance, which can then be incorporated under a high-speed stirrer into the paper-coating composi-tion ready for application.
.
Example 2 ;

~ H=CH ~ H=CH ~ ~;~
F F ~ ~:

24.6 g (0.1 mol) in fluorobenzyl ether phosphon- `~
ate and 6.5 g (0.05 mol) of terephthalaldehyde are initially introduced under nitrogen into 50 ml of dimethylformamide. At room temperature, 18 g (0.1 mol) of 30 % strength sodium methylate solution are added drop- ;~
wise, and the mixture is stirred for 2 hours at room .''''."`'" ' Le A 27 229 _ 9 _ ,. . , ~:
': . ' ~ ':

temperature and for one further hour at 60C. After cooling, the mixture is filtered with suction, and 24.5 g (77 %) of bis-(m-fluorostyryl-)benzene are obtained as colourless crystals which, afte:r reprecipitation from toluene/Tonsil, melt at 188-190C. Extinction in DMF:
~m~ = 355.9 nm; ~ = 61,200.

Examples 3 - 48 Analogously to the procedures of Examples 1 and 2, the brighteners listed in the table which follows are obtained:

Table Ex- Formula Extinction ample in DMF

~ = ~ = 359.9 nm Cl Cl ~ = 48,500 ~ = 358.4 nm ~ -~ ~ = 66,500 Cl Cl F3C ~ ~ 3 ~ - 67,000 Le A 27 229 - 10 -.~ , 2~29220 Table (continuation) Ex- ~ormula Extinction ample in DMF
_ F3C`o ' ~ ' ~ ~ ~CF3 ~ - 357 1 nm CH3O ~ CH3 ~ = 371 nm c = 67,700 Cl Cl 502 J = CH3 ~ ~ 368200 Cl H3C~5O ~ ~ ~ ~ ~ = 52 ~ = 369,7 nm 6 = 80,800 :": '~'' ''`~' F3C~ ~ ~ = ~ S~ = 368 5 nm `~
6= 74,600 ll ~ `

CH3~ - 61,800 C 1 C 1 , ,~

Le A 27 229 :, :":, . ; - , ~ :

,~, 2029220 Table (continuation) Ex- Formula Extinction ample in DMF
_ r ~ ~' ~ C ~ ~ - 56 000 F F F F

F ~ 351 7 nm \~='/ \ ~ ~ = 354.6 nm = 57,000 ~ O-CF3 F3C-O
: 15 F ~ = 354.5 nm 6 = 62,000 :
~ 16 : ~ ~3 = 355.9 nm Cl Cl 6 = 55,000 Le A 27 229 - 12 -,. ~ , . ~

:

~ 20~9220 Table ~continuation) Ex- For.mula Extinction ample in DNF

~ ~ = 355.9 nm H3C ~F e = 63, 500 H3C~ Cl ~ = 367.6 nm e = 69,000 ~
CH30 Cl ~ ~:
. :.

H3C~50~ ~ = 367 nm;;~
C 1 e = 66,800 ~ -52 _~ ~ C ~CH3 Cl ~ = 367 nm e = 66,800 :~
: .: :
. .. :..

H3C~ ~ CH

Cl Cl ~ = 363.6 nm ~ ~.
e = 73,700 :~

Le A 27 229 - 13 -f``` 2029220 Table ( continuation ) Ex- Formula Extinction ample in DMF
-CH3` ~ ~ ~ ~ $ CH3 6 69,600 Cl CH30 Cl Cl ~ CH3 ~ = 363 nm H3C ~ ~ 1 ~ = 73~000 Cl ~ ~ j } So~CH3 e ~ 83~ioo Cl - ~ '~ 1 e ~ 71~500 Cl ~ CH3 ~ = 361.7 nm Cl Cl ~ 55~000 27 Cl Cl } CH3~ = 361.7 nm Cl ~ ~ 60,0oo Le A 27 229 - 14 -'''~" ;' '' "' ' '' '' ' ' , ~' i , ' ,' ' ~ ~

Table (continuation) Ex- Formula Extinction ample in DMF

{3 ` `
Cl ~ / \~ ~ 361 7 nm Cl Cl F3C ~ ~ == F ~ = 361 nm ~;~

3 ~ = 69,600 :-Cl Cl CH3~ ~ 3 ~ = 582 4 nm ;~
OCH3 CH30 6 = 61,500 ~ ~.
~ .

CH3 ~3C

3C~so ~ ~ 6 - 807000 Cl Le A 27 229 - 15 -: :. : .. .: -.: :
. : . ~ .~: . -: .

2~292~

Table (continuation~
~x- Formula Extinction ample in DMF

i CH3 ~ = 367.6 nm Cl Cl 6 = 71,000 34 Cl CH3 ~ ~
: OCH3 Cl ~ = 366.3 nm ~ = 58,500 ~ ` ~ ~ = 373.4 nm L o i 6 = 68,500 O

Cl ~,_$1 6 - 54 500 Cl OCH3 CH30 Cl ,r ~1 ~ = 365.3 nm Cl OCH3 H3C c = 58,000 Le A 27 229 - 16 -:, ~,, j ,, .. . - . ~ . , ~

~- 2029220 Table ( continuation ) Ex- Formula Extinction ample in DMF

CH3~ e ~ 71,000 Cl Cl , ~_ Y. ;
~ ~ ~ = 355.9 nm l O F F e = 61 ~ 200 Cl~
F c - 63245030nm 41 C~

~ ~ e - 67,500 C l OCH3 C l ~S ~ }S~ ~ = 370.4 nm r3~ Cl Cl ' 3 e = 58,000 ~S '~ S~ ~ = 368.3 nm F3C C l CF3 6 = 60 ~ 000 Le A 27 229 - 17 ~

: . . - : : : : :
.~ , . .: . . . .

~ 2029220 Table (continuation) Ex- Formula Extinction ample in DMF

Cl ~ ~ l ~ - 347 8 nm Cl ` ~ ~ = 358.4 nm Cl CH30 Cl ~ = 62,500 OCH3 ~ CH30 = 381.7 nm ~ ~ ~ = 42,000 ~ ~ ~ = 375.2 nm ~ = 66,000 48 ~
~ = ~ . .
~, ~<
= 373.8 nm ~ = 52,000 Le A 27 229 - 18 -.. , .... ~ , . , ~

-,. : ~ :: : :
, . ~ . . . . .

.

~ 2029220 Example 49 A paper-coating composition having a solids content of about 55 % is prepared by stirring together 60 parts of SPS china clay 40 parts of calcium carbonate 20 parts of an anionic plastics dispersion of an acylic acid ester-containing copolymer having a solids content of about 50 ~ (for example Acronal S 320 D~ from BASF) :~
5 parts of a polyacrylic acid ester as a co-binder t40 %
strength) (for example Acrosol 40 D~ from BASF) and 80 parts of water, and the pH value of the composition is ad~usted to 9 with ~ :
sodium hydroxide solution.
lO g, 20 g, 40 g, 60 g or 100 g of a 25 ~
strength dispersion of the optical paper brightener of Example lb) are stirred in each case into one 1 kg of this coating composition.
After the prepared coating composition has been coated onto paper with the aid of a manual coating blade or an experimental coating unit and after drying at 80C, coated papers are obtained which, depending on the addi-tion of brightener, show a significant to excellent brightening effect. In contrast to conventional paper brighteners, a significant incr~ase in whiteness is still achievable without a co-binder, even at higher brightener additions such as, for example, 50 g/kg of coating compound.
Table 1 shows the CIE whiteness of the coated papers.

Le A 27 229 - 19 - .

~.

"' j ,' : ' ~'` , , ' ' ' ~ ' ~, ,, , ~ . .

!, ' ' ,. ~ : : , :

, 2029220 Table 1 25 % strength brightener dispersion CIE
(Example lb) whiteness (g/kg of coating compound) . . . .
- 63.0 88.0 113.2 121.2 lO0 128.3 Le A 27 229 - 20 -

Claims

Patent Claims

1. Brightener-containing paper-coating compositions containing, as the brightener, compounds of the formula (I) wherein - independently of one another - R1, R2, R3 and R5, R6, R7 denote H, F, Cl or CH3 and R4 and R8 denote H, O-C1-C4-alkyl, S-C2-C4-alkyl, SO2C2-C4-alkyl, CF3, OCF3 or SCF3, it also being possible for two adjacent radicals to represent -OCH2O- or -CH=CH-CH=CH-.

2. Paper-coating compositions according to Claim 1, characterized in that they contain the compound of the formula

3. Paper-coating compositions according to Claim 1, characterized in that they contain the compound of the formula

4. Paper-coating compositions according to Claim 1, characterized in that the average particle size of the brighteners is less than 5 µm, preferably less than 0.5 µm.

5. Compounds of the formula (I) wherein R4 and R8 F, CF3, OCF3 or SCF3 and the remaining radicals have the meaning given above, with the proviso that these radicals do not represent hydrogen if R4/R8 denote F or CF3.

6. Compound of the formula

7. Compound of the formula