AU472012B2 - Colour formers - Google Patents

Description

2,3 77 n2 This invention relates to colour formers and more

particularly to colourless colour formers suitable for use

in pressure-sensitive copying systems.

In known pressure-sensitive copying systems a colour-

less colour former, dissolved in a suitable solvent, is

brought into contact with an electron-accepting substance

whereupon a coloured image in the parent dyestuff is

formed.

In one known system a sheet of pressure-sensitive

copying paper comprising a paper base carrying the colour

former in encapsulated form is placed in contact with a copy

sheet, comprising a-paper base having an active mineral sur-

face coating, for example a surface coating of a so-called

acid clay. When local pressure is applied to the sheets by means of, for example, hand-writing or type-writing, the capsules on the pressed portions are broken and the colour

former comes into contact with the active mineral on the

copy sheet and a coloured image of the original writing is formed on the copy sheet.

Various colour formers for use in such systems are

known, but a difficulty has always been that if a dark image,

for example a black image, is required then a combination of

different colour formers has been required. The use of combinations of colour formers can lead to difficulties in

production and also difficulties in providing a copy sheet

having an active surface able to react as necessary with the

colour formers used.

Clearly it would be desirable to use a single colour

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52.3 77n2 former to provide a dark, for example a black, image.

According to the invention there are provided colourless

colour formers which are compounds of the general formula:

R1 N 0 A Z

wherein R l R2 and R 3 each independently represents hydrogen or an alkyl radical having from one to five carbon atoms or feme 1 ad R Rj part 2 kaqel^ of heterocyclic ring containing the attached nitrogen atom; R represents a halogen atom or an alkyl, aryl, aralkyl,

alkoxy, nitro, amino, acyl, carboxy, cyano or sulphamoyl radical;

n represents an integer of from 0 to 4; A represents an aromatic

nucleus the points of attachment being at two pairs of ortho

positions; and Z represents a divalent radical, a five- or six- membered ring being formed with -NR 3 and A, with the proviso that when Z is a 1,2-phenylene radical, thaiEnn is not 0. Alkyl radicals which may be represented by R1 and R2

include methyl and preferably ethyl. When R1 and R2 forms part of a heterocyclic ring containing the attached nitrogen atom

this may be because R and R 2 are joined together to form a divalent chain of atoms which together with the attached nitro-

gen atom constitutes a heterocyclic ring such as a pyrrolidine

or morpholine ring.

A is preferably a benzene ring having points of attach-

ment in the 1,2- and 4 ,5-positions. Z may be a 1,2-phenylene

3 47 2.012

52,377n2

radical. Z may terminate at its end remote from -NR 3 in 6 6 methylene, or -NR wherein R denotes hydrogen or

an alkyl, aryl or aralkyl radical.

The colour formers of the invention may be prepared by

reacting a compound of the formula: Rl~ N_ OH R

CO (R coc

wherein R 1 R2 R 4 and n have the significances already stated,

with a compound of the formula:

R7 0 AS-. z

H 3

wherein A, Z and R 3 have the significances already stated and

R7 represents hydrogen or an alkyl radical having from one to

five carbon atoms, the reaction being performed in the presence

of a suitable condensing agent, preferably sulphuric acid or

polyphosphoric acid.

The colour formers of the invention provide darker images

than the colour formers which have generally been used to date,

including black images in some cases, when reacted with a suit-

able electron-accepting substance. Such substances include

silica and attapulgite, which is a so-called acid clay, and

synthetic resins containing unreacted

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52.3 7 7

phenolic hydroxyl groups. by the The invention is illustrated but not limited percentages are by following Examples in which all parts and

weight.

EXAMPLE 1 0- 31.3 parts o(4-diethylamino-2-hydroxybenzoyl)e-benzoic and 100 parts of acid, 21.1 parts of 2-methoxyacridan 0 C with stirring for 2 hours sulphuric acid are heated at 100 drowned into water and then cooled. The reaction mixture is off and then slurried the solid which separates is filtered solution to give an in an excess of 2N ammonium hydroxide

off-white solid. Filtration and drying gives the product,

39 parts. has the struc- A toluene solution of the product which

ture -(C 2 H5 )2 V C

C

(6~

with a so-called acid gives a dark-coloured image on contact clay.

47 2.012

52.3 77 2

2 EXAMPLE A 3.13 parts of o-(4-diethylamino-2-hydroxy benzoyl)

benzoic acid, 2.25 parts of 2-methoxy-acridone and 20 parts 0 of sulphuric acid are heated at 100 C for 14 hours then cooled. The reaction mixture is drowned into water and the solution made alkaline with ammonia. The solid which

separates is filtered off, washed with water and dried to give 1.4 parts of the product of structure:

H NO

A toluene solution of the above fluoran gives a dark blue image on contact with electron accepting surfaces. 34 EXAMPLE 3

3.11 parts of 0-(4-pyrrolidin-l-yl-2-hydroxy benzoyl)

47 2.012

52.3 777 n2

benzoic acid, 2.01 parts of 3-methoxy-5,6,7,8-tetrahydro-

carbazole and 30 parts of sulphuric acid are heated at 80 0 C

for 6 hours then cooled. The reaction mixture is drowned into water and made alkaline with ammonia. The solid which separates is collected, washed with water and dried

to give 2.3. parts of the product of structure:

A toluene solution of the above colour former gives a dark

red image on contact with electron accepting surfaces.

EXAMPLE/1 4.51 parts of 1-(4-diethylamino-2'-hydroxy benzoyl)- 4,',t-tetrachlorobenzoic acid, 1.97 parts of 3-methoxy- carbazole and 30 parts of sulphuric acid are heated at for 6 hours then cooled. The reaction mixture is drowned into water and made alkaline with ammonia. The solid which is formed is collected, washed with water and dried to give 1.8 parts of the product of structure:

(C2 5 )21

ci YO Cl 1

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52.3 77n2 A toluene solution of the above colour former gives a dark

bluish-red image on contact with electron accepting surfaces.

EXAMPLE

6.26 parts of o-( 4 -diethylamino-2-hydroxy benzoyl)

benzoic acid, 4.94 parts of l-ethyl-2-methyl mothyl-3-

and 22 parts of 98% sulphuric acid are heated at 70-75°C for 12 hours. The reaction mixture is drowned into water and the precipitated tar is extracted into chloroform. After drying over magnesium sulphate, the chloroform solution is evaporated to dryness and the residue is recrystallised from petroleum ether.

3.3 parts of a white solid melting at 218°C and having the structure:

(C T) 0

are obtained. A toluene solution of the above colour former gives a dark ruby-red colour on contact with electr on accepting surfaces. 6 EXAMPLE

The preparation of Example& is repeated except that the reaction temperature is 0-5°C. 9.3 parts of a white solid, melting point 2530°C and having the structure:

2N-j i0"2.C o 2 0 4.5

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52.3 7 7 n2

are obtained. A toluene solution of the above colour former gives a scarlet colour on contact with electron accepting surfaces. EXAMPLE 7& In place of the 4.94 parts of l-ethyl-2-methyl-3- used in examplet-& there are used 5.94 parts of l-ethyl-2-methyl-3-carboethoxy-5- hydroxy-6,7-benz indole. 4.3 parts of a product having the structure:

(C2 H5) 22

N C2 -o C

O3

is obtained. A toluene solution of this colour former gives a dark ruby-red colour on electron accepting surfaces. EXAMPLE 9 In place of the 6.26 parts of o-(4-diethylamino-2- hydroxy benzoyl) benzoic acid used in Example4-& there are used 6.22 parts of o-[4-(pyrrolidin-l-yl)-2-hydroxybenzoyl] benzoic acid. 3.5 parts of a white solid having melting point 2320 C and the structure:

c- N CH3

0 1C2H are obtained. A toluene solution of the colour former gives a dark ruby-red colour on electron accepting surfaces.

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52.3 7 7n2 9 EXAMPLE r 6.26 parts of o-(4-diethylamino-2-hydroxybenzoyl)- *P- benzoic acid, 3.3 parts of l-methyl-6-hydroxypy-tetra- n. and 22 parts of 98% sulphuric acid are heated at 50-550C for 12 hours. The reaction mixture is drowned into water and neutralised by addition of concen- trated ammonia hydroxide solution. The white precipitate is collected by filtration, washed with water and recry- stallised from n-propanol. 7.3 parts of a white solid having the structure:

CH o. co

are obtained. A toluene solution of the colour former gives a green colour on electron accepting surfaces. EXAMPLE 4a In place of the o-(4-diethylamino-2-hydroxybenzoyl) 9 benzoic acid used in ExampleAh- there are used 6.54 parts of o-[14-(morpholin-l-yl)-2-hydroxybenzoyl]-benzoic acid. The product which has the structure:

0 N

CO

10 47 2.0 1 2

52,3 7 7 n2

is obtained as a white solid. A toluene solution gives a greenish-black colour on electron accepting surfaces.

11 47 2,0 1 2

Claims (1)

1. 52.377/172 The Claims defining the invention are as follows:-

   1. Colourless colour formers which are compounds of the

   general formula:

   N 0

   r3 AZ

   C0 (R4)n

   wherein R I R 2 and R3 each independently represents hydrogen or an alkyl radical having from one to five carbon atoms or Rlazdt 2r#dI.ep 94m& part or a heterocyclic ring containing the attached nitrogen atom; R4 represents a halogen atom or an alkyl, aryl,

   aralkyl, alkoxy, nitro, amino, acyl, carboxy, cyano or sulpha- moyl radical; n represents an integer of from 0 to 4; A repre-

   sents an aromatic nucleus the points of attachment being at

   two pairs of ortho positions; and Z represents a divalent

   radical, a five- or six-membered ring being formed with -NR 3

   and A, with the proviso that when Z is a 1,2-phenylene radical,

   then n is not O.

   2. Colourless colour formers as claimed in Claim 1, in

   which R1 and R2 each independently represent methyl or ethyl.

   3. Colourless colour formers as claimed in Claim 1, in which R 1 and R 2 are joined together to form a divalent chain

   of atoms which together with the attached nitrogen atom con-

   stitutes a pyrrolidine or morpholine ring.

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   52.3 77/n2

   4. Colourless colour formers as claimed in any one of the preceding Claims, in which A is a benzene ring having points of attachment in the 1,2- and

   Colourless colour formers as claimed in any one of the preceding Claims, in which Z is a 1,2-phenylene radical.

   6. Colourless colour formers as claimed in any one of the preceding Claims, in which Z terminates at its end remote from- -NR3 in methylene, or -NR, wherein R6 denotes hydrogen or an alkyl, aryl or aralkyl radical.

   7. A method of preparing colourless colour formers as claimed in Claim 1, comprising reacting a compound of the formula:

   R CO

   ICOOH'

   wherein R1 R2 R4 and n have the significances stated in Claim 1, with a compound of the formula:

   A Z

   H N

   wherein A, Z and R have the significances stated in Claim 1; 3

   and R7 represents hydrogen or an alkyl radical having from one to five carbon atoms, the reaction being performed in the pre- sence of a suitable condensing agent. 13 472012

   52.3 77 n2

   8. A method as claimed in Claim 7, in which the condensing

   agent is sulphuric acid.

   9. A method as claimed in Claim 7, in which the condensing

   agent is polyphosphoric acid.

   Colourless colour formers prepared by the method claimed

   in any one of Claims 7, 8 or 9.

   11. A pressure-sensitive copying paper comprising a paper

   base carrying a colour former as claimed in any one of Claims

   1 to 5 or Claim 10 in encapsulated form.

   12. In combination, a pressure-sensitive copying paper as

   claimed in Claim 11 and a copy sheet comprising a paper base

   having an active mineral surface coating capable of reacting

   with the colour former to provide a coloured image.

   DATED this first day of March, 1976.

   WIGGINS TEAPE LIMITED, By Its Patent Attorneys, ARTHUR S. CAVE CO.

   14 472.012