CH645306A5 - METHOD FOR PRODUCING CONCENTRATED SOLUTIONS OF COLOR IMAGES. - Google Patents

Description

The present invention accordingly relates to a process for the preparation of concentrated solutions of 40 color formers. The process according to the invention is characterized in that after the production process of the color former has ended, the solvent used is removed from the reaction mixture and the residue is dissolved in at least one suitable hydrophobic solvent to form an at least 10% by weight liquid formulation.

Preference is given to the production of such concentrated color former solutions which contain the color former in quantities of 10 to 50, in particular 20 to 30,% by weight.

so The color formers that come into consideration in the new liquid formulations are known colorless or slightly colored chromogenic substances which, if they come into contact with so-called color developers, become colored or change color. Color formers, which e.g. The 55 classes of azomethines, fluorans, benzofluoranes, phthalides, spiropyrans, leucoauramines, triarylmethane leuco dyes, phenoxazines, phenothiazines, and the chromeno or chroman color former can be used as long as the solubility in the solution 60 in question is sufficient . Examples of such suitable color formers are:

3,3- (bis-substituted indoiyl) phthalide, 3- (aminophenyl) -3-indolyl phthalide, 6-dialkylamino-2-n-octy! Amino-fluorane, 65 6-dialkylamino-2-arylamino-fluorane,

6-dialkylamino-3-methyl-2-aryIamino-fluorane, 6-dialkylamino-2- or -3-lower alkyl-fluorane, 6-diaIkylamino-2-dibenzylamino-fluorane,

3rd

645 306

6-pyrrolidino-2-arylamino fluoranes, bis (aminophenyl) furyl or phenyl or carbazolyl methanes.

Of particular interest are the carbazolylmethane compounds described in German Offenlegungsschriften 2,747,526.2,747,525 and 2,915,928 and the bis-indolyl phthalides of German Offenlegungsschriften 2,257,711 and 2,265,233.

Solvents provided for the preparation of the liquid formulations are, in particular, non-volatile hydrophobic (oily) solvents.

Examples of such solvents are polyhalogenated paraffins, such as chlorinated paraffins, halogenated diphenyls such as p-chlorodiphenyl and trichlorodiphenyl, dibenzyltoluene, benzylated xylenes, trichlorobenzene, terphenyl, partially hydrogenated terphenyl, alkyl-substituted diphenyls, naphthyls, ethynes or terphenes -butyl phthalate, dioctyl phthalate, dioctyl adipate, trichloroethyl phosphate, aromatic ethers such as benzylphenyl ether and diphenyl oxide and other chlorinated or hydrogenated, condensed aromatic hydrocarbons. If desired, mixtures of different solvents can also be used.

Preferred solvents are chlorinated paraffins, terphenyls, partially hydrogenated (30 to 45%) terphenyls, C 1 -C 4 -alkyl-substituted diphenyls, naphthalenes or terphenyls and mixtures thereof. Examples of alkyl-substituted diphenyls and naphthalenes are tetramethyldiphenyl, diisopropyldiphenyl and especially diisopropylnaphthalene. These preferred solvents are particularly suitable for the preparation of concentrated liquid formulations which contain 20 to 50% by weight of a carbazolylmethane compound of the formula

J \

y \ A

* —T a i; V V V

i

\] /

- * 2

included in the

R alkyl having 1 to 8 carbon atoms, acetyl, phenyl or benzyl,

Z hydrogen, halogen, nitro, methyl or methoxy,

Xj lower alkyl, phenyl, lower alkylphenyl or lower alkoxyphenyl or benzyl, X2 hydrogen, lower alkyl or benzyl and

Xj is hydrogen, methyl, methoxy or halogen.

The solvents, which are liquids at room temperature, can be used alone or together with diluents. Solvents that are very viscous at room temperature are typically used with a solubilizer or thinner to form a liquid mixture.

Suitable solubilizers or diluents are, for example, mineral oils or vegetable oils such as kerosene, paraffin oil, castor oil, neat's foot oil, sperm oil, fatty oil, olive oil, soybean oil, cottonseed oil, coconut oil, rapeseed oil and aromatic naphtha, Cj-C12-alkylbenzene Benzyldiphe-nyl or Ct-Ce-Alkylarylindan .

The concentrated liquid formulations may contain additives such as e.g. Viscosity regulators, antioxidants, odor masking agents, pour point depressants and / or plasticizers.

The concentrated color former solutions are prepared, for example, by treating the organic reaction solution with hot water (60 to 85 ° C.) after completion of the production process, dewatering the organic phase 5, and the solvent used to prepare the color former e.g. Methanol or chlorobenzene removes e.g. by vacuum distillation and the oily residue at a temperature of 20 to 100 ° C, preferably 50 to 75 ° C in the hydrophobic solvent to the desired concentration. The desired additives can then be added.

A storage-stable, highly concentrated and homogeneous color former solution is thus obtained which generally shows no crystallization or decomposition after storage for three months, in particular at −15 ° C. to 40 ° C.

The liquid formulations according to the invention can be easily metered volumetrically and therefore do not require a complex solution process, including heating, as when using solid color formers. They are particularly suitable for the preparation of ready-to-use color former solutions, which are encapsulated as marking liquids for pressure-sensitive recording materials. Since, according to the method according to the invention, the color former 25 is no longer isolated in solid form by lengthy work-up processes, the manufacturing process can be made cheaper, including time and energy savings, and the color former can also be increased in yield.

The following examples illustrate the invention. 3o parts mean parts by weight and percentages by weight.

example 1

In a flask, 146 ml of dimethylformamide are added to 500 ml of chlorobenzene with stirring. 223.3 g of N-n-butylcarbazole are introduced into this mixture. 230 g of phosphorus oxychloride are then added dropwise to the solution formed at room temperature. The reaction mixture is then heated to 60 ° C. and left at this temperature for 40 hours. After this time, 72 g of water are added to the reaction mixture and 330 g of N-methyl-diphenylamine are added. Then add 100 g of conc. Hydrochloric acid added and heated at 70 ° C for 15 hours.

After the reaction has ended, the reaction mixture 45 is brought to a pH of 10.5 with 1330 g of a 30% strength sodium hydroxide solution and 500 ml of hot water are added. The aqueous phase is then separated off and 1.51 hot water is added to the organic solution. After briefly stirring, the aqueous phase is separated off again. The remaining solution is dewatered azeotropically with 250 ml of chlorobenzene and clarified with activated carbon using a water separator. The chlorobenzene is then removed as completely as possible by vacuum distillation. The residue is taken up in partially hydrogenated terphenyl and set to 25%.

This gives 2000 g of a solution which contains 25% of a carbazolyl compound of the formula s \ A

V1 /

n "C4H9

contains.

645 306

Example 2

179.2 g of acetic anhydride are placed in a flask under nitrogen. 103.7 g of phthalic anhydride are then added with stirring. The mixture is first stirred for 5 minutes and then 243 g of 1-n-octyl-2-methylindole are added. The reaction mixture is then heated to 118 to 122 ° C. and stirred at this temperature for 10 hours. It is cooled to 80 ° C. and 26.3 g of water are added over the course of 5 minutes. The reaction product is then mixed with 600 ml of methanol, heated to 65 ° C and poured into a larger flask. It is washed first with 200 ml of methanol at room temperature and then with 400 ml of water at 65 ° C and cooled again to 20 ° C. The upper methanolic phase is drawn off and the residue is treated again with 1.81 hot water at 80 ° C. for 15 minutes. Finally, the water is completely removed by vacuum distillation.

The oily residue (318 g) is then taken up in 900 g of partially hydrogenated terphenyl with stirring for 30 minutes at 70 ° C. and adjusted to 25%.

1200 g of a solution are obtained, which is 25% of a bis-dolylphthalide compound of the formula

/ \

I If II

r • • •

v vs

CH.

n "C8H17

0 CO

YES

/ -Î ii V / '

contains.

Example 4

50 g of 3- (2 / -ethoxy-4'-diethylaminophenyl-) 3- (1 "-ethyl-2" -methyl-indole-3 "-yl-) 5/6-carboxyphthalide and 50 g of potassium carbonate are in 1600 ml of acetone are added and 36 g of 1-bromohexadecane are added, and the mixture is heated under reflux for 2 hours and then poured onto water, whereupon the reaction product is extracted with toluene then evaporated to dryness. The residue is taken up in 165 g of partially hydrogenated terphenyl. 240 g of a solution are obtained, which is 30% of an isomer mixture of a phthalide compound of the formula

15

®2E5

A A / h3 ¥ AA / WI • • • ~

I II il% /

(14)

25th

30th

Example 3

30 g of 2- (4'-diethylamino-2'-hydroxy-benzoyl-) benzoic acid and 30 g of 4-hydroxy-2-methyl-4'-n-butyldiphenylamine are concentrated with stirring in 360 g. Sulfuric acid reacted at 0 to 10 ° C for 24 hours. The reaction mixture is then poured onto 1 liter of water and the crystals which have precipitated out are filtered off. The crystals are treated with 1 liter of a 2% aqueous sodium hydroxide solution and extracted with 500 ml of toluene. The toluene solution is washed several times first with a 2% aqueous sodium hydroxide solution and then with water, then treated with activated carbon and filtered. The toluene is then distilled off under reduced pressure and the residue is taken up in 150 g of partially hydrogenated terphenyl with stirring at 80 ° C. for 30 minutes. 175 g of a solution are obtained, which is 15% of a fluoran compound of the formula

35

50

-COO (CH2) 15CS3

contains.

Example 5

A mixture of 104.4 g of 4,4'-bis-dimethylaminobenz-hydrol, 16 ml of glacial acetic acid and 112 g of n-octylsulfinic acid sodium salt is stirred in 200 ml of ethanol under reflux for 11/2 hours. After cooling to 20 ° C., the precipitated product is filtered off, washed with methanol and dried. The product is then taken up in 220 g of dibutyl phthalate. 275 g of a solution are obtained, which is 20% of a compound of the formula

45

<CH3'2S— (/ - () —f <CH3) 2

• I

(15> S02- (CH2) 7-CH3

(C2H5) 2N-

(13)

contains.

0 CH "

* \ / V / ^ / 3 '• • • *

1 II il i.

contains.

55

In O.

\

Example 6

^ / "\ / ~ \ ^ V S In Example 1, the partially hydrogenated terphenyl is replaced

• * v • «H — n-C ^ Hg by one of the following solvents

Diisopropylnaphthalene,

6o monoisopropyldiphenyl,

benzylated m-xylene,

benzylated ethylbenzene or chlorinated paraffin,

this also gives 2000 g of a solution which contains 65-25% of a carbazolyl compound of the formula (11).

/ V

1 II

• v •

V

CO

s

Claims (4)

645 306 1. A process for the preparation of concentrated solutions of color formers, characterized in that after the production process of the color formers has ended, the solvent used is removed from the reaction mixture and the residue is dissolved in at least one hydrophobic solvent to form an at least 10% by weight liquid formulation. -2 R alkyl having 1 to 8 carbon atoms, acetyl, phenyl or benzyl, Z is hydrogen, halogen, nitro, methyl or methoxy, Xx lower alkyl, phenyl, lower alkylphenyl or lower alkoxyphenyl or benzyl, X2 hydrogen, lower alkyl or benzyl and X3 is hydrogen, methyl, methoxy or halogen. 5. The method according to any one of claims I to 4, characterized in that a terphenyl, partially hydrogenated terphenyl, C1-C4-alkyl-substituted diphenyl, naphthalene or terphenyl, chlorinated paraffin or a mixture thereof is used as the hydrophobic solvent. 6. Concentrated liquid formulation of a color former, produced according to the process according to one of claims 1 to 5. 7. Liquid formulation according to claim 6, characterized in that it contains at least 10% by weight of a carbazolylmethane compound or a bis-indolylphthalide dissolved in at least one hydrophobic solvent. 8. Liquid formulation according to claim 7, characterized in that it is a carbazolylmethane compound of the formula / V 4- II f V f J 2. The method according to claim 1, characterized in that solutions are prepared which contain the color former in amounts of 10 to 50, preferably 20 to 30 wt .-%. 2nd PATENT CLAIMS 3. The method according to any one of claims 1 and 2, characterized in that the color former is a carbazolyl methane compound or a bis-indolyl phthalide. 4. The method according to claim 3, characterized in that the color former is a carbazolylmethane compound of the formula Z is hydrogen, halogen, nitro, methyl or methoxy, Xj lower alkyl, phenyl, lower alkylphenyl or lower alkoxyphenyl or benzyl, X2 hydrogen, lower alkyl or benzyl and 5 X3 is hydrogen, methyl, methoxy or halogen. 9. Liquid formulation according to one of claims 7 and 8, characterized in that the hydrophobic solvent is terphenyl, partially hydrogenated terphenyl, an io Cj-C4-alkyl-substituted diphenyl, naphthalene, terphenyl, chloroparaffin or a mixture thereof. 10. Use of the liquid formulations according to one of claims 6 to 9, for the production of pressure-sensitive recording materials. IS J V II ./ V »I 4th v YV » R -TW VK \ is in the 4th V Y V i R contains in the R alkyl having 1 to 8 carbon atoms, acetyl, phenyl or benzyl, • 'W w K \ The conventional pressure-sensitive recording materials generally contain a solution of color formers encapsulated in microcapsules. Finely ground color formers are used to prepare these solutions required for the encapsulation, which are dissolved in a selected solvent to form the desired 1-725% by weight marking liquids. It has now been found that a storage-stable, highly concentrated liquid formulation of a color former is obtained if the color former is taken up directly in the desired solvent without isolation after completion of the production process. From these concentrates ready-to-use solutions can be prepared by appropriate dilution, which can be encapsulated and used in pressure-sensitive recording materials. This can have certain disadvantages, such as 35 e.g. Dust generation and solution problems that occur when using color formers in powder form are avoided.