NO137532B - CHROMOGENIC LABELING MATERIAL. - Google Patents

Description

The present invention relates to a substantially colorless chromogenic marking material which is particularly usable in connection with pressure-sensitive copying material of the type where a solution of a normally colorless or weakly colored chromogenic substance is brought into reactive contact with an acid-reactive material such as attapulgite clay or phenolic polymer on the surface of a sheet,

in that said acid-reacting co-reactant converts the chromogenic compound into a strongly colored form, so that a legible mark or sign is formed on the sheet.

Such copying materials and a variety of suitable chromogenic substances are well known, and the preparation of chromogenic fluorane compounds useful in this connection is described in British Patent Nos. 1,269,601, 1,316,909 and 1,332,594.

It is a disadvantage of these fluorane compounds that they

tends to form colored marks which are not as easily copied as one would like: by xerographic copying and which change tone by bleaching.

With the present invention, the above disadvantages are avoided in that a substantially colorless chromogenic marking material is provided which is transferred to a black or almost black form when brought into reactive contact with an acid-reacting co-reactant and which comprises only 2 chromogenic compounds of amino-substituted fluorans , and this material is characterized by the fact that the first of the two compounds is chosen from among amino-substituted fluorans with the general formula:

wherein each of the groups R is hydrogen, a nitro or amino group; each of the groups R 1 is hydrogen, a methyl or ethyl group; and Rg is the group.

where R-^ has the above-mentioned

meaning, or

the group -CH^-X where X is hydrogen or a phenyl-, acetyl-, benzoyl-, methoxy-, -CH^CH^-, carboethoxy-, N,N-dimethylamido or methyl group, while the groups R both denote hydrogen when R 2 is the group -CH 2 -X; and the second of the two compounds is selected from 3,3-bis(1-ethyl-2-methylindol-3-yl)-phthalide, 3'-diethylamino-6', 7'-methylenedioxyfluorane, and amino-substituted fluorans of the general formula :

where has the meaning stated above; R^ is a hydrogen

atom or an acetyl group; R 1 is a hydrogen atom, or a methyl, ethyl, phenyl or o-carbomethoxyphenyl group; each of the groups R,_ is a hydrogen or chlorine atom, or a methyl, ethyl or thiomethyl group; and Rg represents a 7',8'-benzo-

group or a 7'(N),8'-pyridino group.

The aforementioned first compounds usually form a green color when reacted with an acidic compound such as a phenolic resin, and usually have two maximum peaks in their light absorption spectra, one peak being between 400 and 500 um and the other between 550 and 650 um. Fig. 1 in the attached drawings illustrates a typical absorption spectrum for one of these substances.

Said second compound usually produces a red or

pink color, although purple and orange can also occur, and usually has a single absorption peak between 500 and 600 ym. A typical absorption spectrum for these compounds is shown in fig. 2.

The combination of such a first and second compound may

in this way is used to give a more uniform and approximately linear absorption in the visible light spectrum, and a typical spectrum for such a combination is shown in fig. 3- This relatively even absorption in the visible spectrum gives a grey-black or neutral colour,

and the ratio between the first and second compounds forming this color is usually between 1:5 and 5:1, preferably between 1:1 and 5:1" and these neutral colors prove to be easier to copy by xerographic techniques and resist tendencies to bleaching.

Special examples of compounds suitable as mentioned

first connection includes:

Formula no.

1 3'-diethylamino-7'-anilinofluorane

2 3'-diethylamino-7'-(N-methylanilino)-fluorane

3 3<1->diethylamino-7'-(p-toluidino)-fluorane

4 3'-diethylamino-6'-methyl-7'-(p-toluidino)-fluorane

5 3'-diethylamino-7'-anilino-6-nitrofluorane

6 3'-diethylamino-7'-anilini-5-nitrofluorane

7-3'-diethylamino-7'-(N-methylanilino)-6-nitrofluorane

8 3'-diethylamino-7'-(N-methylanilino)-5~nitrofluorane

9 3'-diethylamino-7'-methylaminofluorane

10 3'-diethylamino-7'-benzylaminofluorane

11 3'-diethylamino-7'-(N-acetonyl-N-methylamino)fluorane

Formula no.

12 3'-diethylamino-7'-phenacylaminofluorane

13 3'-diethylamino-7'-methoxymethylaminofluorane

14 3'-diethylamino-7'-allylaminofluorane

15 3'-diethylamino-7'-(N-carbotoxymethyl-N-Methylamino)-fluorane

16 3'-diethylamino-7,-(N,N-dimethylacetamidoamino)-fluorane

17 3'>7T<->bis(methylamino)-fluorane

18 3'-7f-thiis(diethylamino)-fluorane and

19 3'Tdiethylamino-7'-anilino-6-aminofluorane.

Examples of substances suitable as said second compound

in the mixture includes:

Formula no.

20 3,3-bis(1-ethyl-2-methylindol-3-yl)-phthalide

21 3'~diethylamino-7',8'-benzofluorane

22 3'-diethylamino-6'-methyl-7'-chlorofluorane

23 3'-Diethylaminofluorane

24 γ-diethylamino-7'-aminofluorane

25 3'-diethylamino-7'-(o-carbomethoxyanilino)-fluorane

26 3'-diethylamino-6', 7'-methylenedioxyfluorane

27 3'-diethylamino-7'-thiomethylfluorane

28 3'-diethylamino-7'-(N-acetylanilino)-fluorane

29 3'-diethylamino-7'-(N-acetylmethylamino)-fluorane

30 3'-diethylamino-7'-acetamidofluorane

31 3'-ethylamino-7't8'-benzofluorane

32 3'~diethylamino-7<1>(N),8'-pyridinofluorane and

33 3'-diethylamino-6'-methyl-7'-thiomethylfluorane.

It will be seen from the above examples that the preferred substituent in the 3' position in the fluoran compounds is a diethylamino group.

The structural formula for these compound examples is listed below with the corresponding formula number.

Certain special labeling compounds which have been produced in accordance with the invention are composed of substances with the formula numbers below, which correspond to the previous lists of formula numbers and structural formulas.-

These and other labeling compounds according to the invention can be used in commonly known ways for such compounds, and are not necessarily limited to the preferred types of copying material mentioned earlier. E.g. the labeling compound can be incorporated in a dry, crystalline state into a polymeric binder which is transferred by applied pressure to an acid-sensitive surface.

Listed below are examples of the manufacture of wood

of the substances used according to the invention.

Example 1.

Preparation of 3'-diethylamino-7T<->anilino-6-aminofluorane

was carried out in three steps, namely (1) conversion of m-diethylamino-

phenol with 4-nitrophthalic anhydride which gives two isomeric benzophenones which bILe separated to the desired 2'-carboxy-4-diethylamino-2-hydroxy-5'-nitro-benzophenone, (2) condensation of said nitrobenzo-phenone with p-anilinophenol to 7'-aniline-3'-diethylamino-6'-nitrofluorane and (3) reduction of the nitrofluorane to aminofluorane.

40.5 g 4-nitrophthalic anhydride, 34>6 g m-diethylamino-

phenol and 300 ml of benzene were refluxed for three hours, cooled, diluted with 200 ml of benzene and extracted with 150 ml of 5% aqueous NagCO^ twice. The alkaline extracts were combined, washed

with 500 ml benzene four times, diluted with "] 00 ml water and acidified to pH 2 which gave a precipitate which was washed with water and air dried. The precipitate was triturated several times with 300 ml portions of hot benzene

and filtered, leaving an insoluble residue. The benzene solutions were combined, extracted with 100 ml of 5N aqueous NagCO 3 solution twice, the combined alkaline extracts were washed with benzene and acidified to pH 2 to give 13.9 g of the crude 2'-carboxy-4-diethylamino-2- hydroxy-5'-nitrobenzophenone. Further purification of the compound consisted of recrystallization from benzene, and the pure product melted at 180-181°C.

11.1 g of 2'-carboxy-4-diethylamino-2-hydroxy-5'-nitrobenzo-phenone, 17.3 g of p-anilinophenol and 80 ml of a mixture of equal volumes of oleum SO^, 20%-ig and concentrated H2S0 ^ was stirred at 2o<i>.l°C for fifteen hours, poured into 600 g of ice, neutralized with 10$-ig aqueous NaOH which gave a semi-solid which solidified on immersion in water. The solid was triturated with water and the water filtered off. The residue was dissolved in benzene and the solution washed with 10% aqueous NaOH and with water. After concentration to approx. 100 ml volume, benzene was dissolved

ning chromatographed on activated alumina. The desired pro-

product, 2'-anilino-6'-diethylamino-6-nitrofluorane was eluted with benzene-ether-ethyl acetate (1:1:1) and had a weight of 5)0 g. 5 g of 2'-anilino-6 '-Diethylamino-6-nitrofluorane was dissolved in 70 ml of chloroform, diluted with an equal volume of ethanol and reduced with 11.1 g of mercuric chloride dihydrate in a mixture of 50 ml of HCl. (sp. weight 1.14) and 10 ml of water. The reaction mixture was made alkaline with aqueous NaOH to a pH of approx. 14 and extracted with hot benzene. The benzene extracts were combined, washed with 10 µg aqueous NaOH and with water, and a crude product weighing 4.7 g was obtained. This was chromatographed on activated alumina, and the desired substance eluted with benzene-ether-acetate (3: 3'-1)> °g one got 3>8 g with melting point 264-266°G.

Example 2.

Preparation of 3'-diethylamino-7(N-ethylanilino)-fluorane was carried out as follows.

0.3 g of 2'-anilino-6'-diethylamino-fluorane, 3 ml of triethyl phosphate, 1 ml of ethyl iodide and 0.1 g of Na^CO^ were gently heated in an open flask with a narrow neck so that the temperature of the reaction mixture increased slowly . When the temperature had reached 140°C, the flask was allowed to cool to approx. 60°C and after adding another 1 ml of ethyl iodide, it was heated again to 140°C. On cooling, the reaction mixture was diluted with 50 ml of benzene, washed with 10% aqueous NaOH and with water and concentrated to approx. 0.3 ml under reduced pressure. Repeated extractions of the solution with petroleum ether (low boiling point) gave a solid weighing 0.3 g. The latter was chromatographed on activated alumina and the desired product eluted with benzene ether (3:1), which gave 0.2 g with melting point 149*-151°C. Further recrystallization from benzene-petroleum ether gave pure 3'-diethylamino-7'-(N-ethylanilino)-fluorane melting at 158-160°C.

Example 3.

In the preparation of 3,3-bis(1-ethyl-2-methylindol-3-yl)-phthalide: 1.54 g of 1-ethyl-2-methyl-3-(2-carboxy-benzoyl)indole, 0 .8 g of 1-ethyl-2-methylindole and 5 ml of acetic anhydride were filled into a 5° ml flask immersed in a water bath at 28-32° C. for 5 hours. The precipitate formed was filtered, washed with ethyl ether and purified. The product 3-3-kis-(1-ethyl-2-methylindol-3-yl)phthalide had a melting point of 225-227°C. A benzene solution of the phthalide was colored red in contact with attapulgite clay coated on paper or with phenolic resin on paper.

Claims (2)

1. Substantially colorless chromogenic marking material which is transferred to a black or almost black form when brought into reactive contact with one acid-reacting co-reactant and which comprises only 2 chromogenic compounds of amino-substituted fluorans, characterized in that the first of the two compounds is selected among amino-substituted fluorans of the general formula: wherein each of the groups R is hydrogen, a nitro or amino group; . each of the groups R 1 is hydrogen, a methyl or ethyl group; and R^ is the group where R^ has the meaning indicated above, or the group -CI^-X where X is hydrogen or a phenyl-, acetyl-, benzoyl-, methoxy-, - CE=CH^-, carboethoxy-, N,N-dimethylamido- or methyl group, while the groups R both denote hydrogen when R 2 is the group -CH 2 -X; and the second of the two compounds is selected from among 3,3-bis(1-ethyl-2-methylindol-3-yl)-phthalide, 3'-diethylamino-6',7'-methylenedioxyfluorane, and amino-substituted fluorans with the general formula : where has the meaning stated above; R 1 is a hydrogen atom or an acetyl group; R 1 is a hydrogen atom, or a methyl, ethyl, phenyl or o-carbomethoxyphenyl group; each of the groups Rc is a hydrogen or chlorine atom, or a methyl, ethyl or thiomethyl group; and represents a 7'>8'-benzo group or a 7'(N),8'-pyridino group. 2. Marking material according to claim 1, characterized in that the molar ratio between the first compound and the second compound is between 1:1 and 5:1.