US3463655A - Pressure-sensitive copying paper - Google Patents

Description

A118. 25, 1969 I-II-rosI-II IMAMIYA ET A L 3,463,655

PHESSUR-SENSITIVE COPYING PAPER Fnedprn 5, 19e? EXTINCTION I I I I I I I I I I I I `240 260 280 300 320 340 360 380 400 420 440 480 my -m- INVENT ORS HITOSHI IMAMIYA SHIZUO KATAYAMA HIROHARU MATSUKAWA TERUO KOBAYASHI SADAO ISHIGE BY v M/M/Z-R #Ma/f ATTORNEYS' United States Patent O ice Claims priority, application Japan, Apr. 9, 1966,

41/ 22,196 Int. Cl. B41m 5/16, 5/14 U.S. Cl. 117-361 4 Claims ABSTRACT F THE DISCLOSUREl A pressure-sensitive copying paper containing as a color former a coumarin compound of `the followingy general formula:

Suitable coumarin compounds of the above type are 4 methyl N,N dimethyl aminocoumarin, 4 methyl- N,N diethyl aminocoumarin, 4 propyl 7 N ethyl- N benzyl aminocoumarin, 4 phenyl 7 N,N dibutyl aminocoumarin, 4 (4 methoxyphenyl) 7- N,N dimethyl aminocoumarin and 4 (3 4methylphenyl) 7 N,N diethyl aminocoumarin. The coumarin may be used with or without leuco color forming compounds conventionally used in reaction-type pressuresensitive,.copying papers. The copy obtained with the new copying paper can be efficiently reproduced by diazo and electrophotographic printing or copying systems.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to a pressure-sensitive copying paper using a coumarin compound as a color former and it is concerned with pressure-sensitive copying paper which provides colored marks which can be reproduced, if desired, by an electrophotographic copying system or a diazo-type printing system.

Commercial pressure-sensitive copying papers utilize the phenomenon that when a colorless electron-donor, organic compound is adsorbed on an electron-acceptor adsorbent, -both of the colorless materials are converted into a colored material. In such pressure-sensitive copying systems, a paper is coated with a dispersion of nonvolatile, line liquid droplets containing a colorless electron-donor, organic compound encapsulated in a microcapsule which is capable of being ruptured by local pressure, e.g., by means of a pencil, stylus, ball-point pen and typewriter. A second paper is coated with a film of a finely divided adsorbent in a binder, and they are closely superimposed on each other and pressed locally. In this way, color is formed only in the pressed region.

Discussion of the prior art When the most commonly used color former for pressure-sensitive copying papers, `for example, a leuco com- 3,463,655 Patented Aug. 26, 1969 pound, such as, Leuco Methylene Blue or Crystal Violet Lactone, is adsorbed on a clay, such as, kaolin or bentonite, which are electron-acceptor adsorbents, the absorption wave length of the thus colored marks appears within a range of 550 to 700 millimicrons. Such colored marks, therefore, are hardly able to be copied on diazo copying paper, when submitted to a diazo copying procedure, and also lacks the ability to be eiciently copied by electrophotography.

Thus, the principal object of the invention is to overcome the foregoing disadvantages of known pressuresensitive copying papers.

SUMMARY OF THE INVENTION K The present invention is based upon our discovery that the use of a compound represented by lthe following general formula:

in which R1 and R2 each is a member selected from the group consisting of a lower alkyl group and an aralkyl group, and R3 is a member selected from the group consisting of a lower alkyl group and an aryl group, as a color former in a color forming reaction with an electron-acceptor adsorbent, such as, clays, result in the formation of colored `marks having an absorption wave length substantially within a range of 380 to 400 millimicrons and colored light yellow. This is an absorption range most suitable for the light-sensitive zone of the commercial diazo copying paper.

BRIEF DESCRIPTION OF THE DRAWING DETAILED DESCRIPTION OF THE INVENTION In the drawing, there are shown spectral absorption curves for markings obtained with a clay paper and a conventional paper that have been immersed in a benzene solution of 4-methyl-7-diethylaminocoumarin, one of the compounds of our invention, and then dried. Curve 1 shows the absorption spectrum of marks obtained by applying the coating on the clay paper and curve 2 is the absorption spectrum for markings obtained by applying the coating on the conventional paper. As is evident from the curves, use of the coumarin compounds of this invention gives markings having a maximum absorption near 385 millimicrons. The colored marks obtained by using the coumarin as a color former, with or without the foregoing leuco compounds, for pressure-sensitive copying papers and subjecting such papers to color forming reactions with clay according to the foregoing procedure, can be readily copied by diazo-type and electrophotographic reproduction procedures. In the case of using only the color forming compound of our invention, however, the color formed on a clay paper is light yellow and is not a clear color. However, this disadvantage is readily overcome by the joint use of the conventional leuco compound described above.

The following compounds are illustrative of the color former compound used in the invention although the invention shall not be limited to them. Each structural support member in a predetermined coating amount by formula thereof is represented by substituents R1, R2 and means of an air knife coating or roll coating, followed by R3 of the foregoing general formula. drying, to obtain a pressure-sensitive copying paper.

TABLE 1 Color Former No. Ri R2 R; Compound aniinocoumarln.

V C l-I; C H3 -O C H3 diinethyl-aminocoumariu.

dimethyl-aminoeoumarin.

V11 -CiHi C2115 diethyl-annocoumarin.

A pressure-sensitive copying paper using the coumarin When a colored mark formed on a clay paper by the compounds of the invention, as mentioned above, as a use of the pressure-sensitive copying paper made by the color former, may be prepared in the conventional man- 30 foregoing procedure, was subjected to commercial diazo ner. Preparation of oil-involving capsules, for example, copying, a very sharp copied image was obtained.

may be carried out according to the coacervation process Similarly, when subjected to electrophotographie copyas disclosed in U.S. Patents 2,800,457 and 2,800,458. ing, an excellent copied image was obtained which is quite The feature of the pressure-sensitive copying paper of r different from the experience with the prior art. the present invention consists in the use of the coumarin 0 The colored marking was resistant to radiation of suncompound as a color former, whereby there are provided light, ultraviolet rays, arcs, and so on, over a long period colored marks giving an absorption wave length suitable. of time. The coating surface was subjected to heat treatfor diazo copying papers. The properties of the pressure ment at 150 C. for 10 hours and to radiation of ultrasensitive copying paper are inuenced by the manner in 0 violet rays for l hour, and then was used to form colored which it is prepared. Therefore, as is well known in the markings on a clay' paper. The colored markings so proart, various raw materials for pressure-sensitive copying duced were scarcely influenced by the pretreatment of papers may be utilized and the preparation of a coating the paper.

solution and the preparation, application and drying of Example 2 the coating compositions may be carried out by any con- This example is similar to Example 1 except that 3.5

Ventionally used apparatus or plant 4D parts by weight 4-methyl-7N,Ndiethylaminocoumarin PREFERRED EMBODIMENTS OF THE (Color Former N0. II 0f Table 1), 4.5 parts by weight INVENTION of Crystal Violet Lactone and 3 parts by weight of Benzoyl Leuco Methylene Blue were dissolved in 89 parts by The following examples are given in order to illustrate r Weight of a mixed Oil of trichlorodiphenyl and kerosene the Invention: "o in a mix ratio of 4:1 and 5.0 kg. of the rresulting color Example 1 former oil was used.

3.5 pai-is by weight ef 4-methy1-7-N,Ndieihy1amiiie A colored mark produced on a clay paper by the resultcoumarin (Color Former No. II of Table 1) was dis- 1ng Pressure-sensitive Copying Paper Was in ho Way in' solved in 97 parts by weight of a mixed oil of trichloro- 55 ferior to that of known Pressure-sensitive Copying Papers, diphenyl and kerosene in a proportion 0f 4:1 at 60 70 which are free of the color former of the present inven- C. (This is simply called color former oil.) 1.0 kg. of gum tion, With respect to the Color tone, density and Other arabic and 1.0 kg. of gelatin, treated with acid, were dis- Properties. Further, the paper produced a Copy Capable served in 4 liters ef water at 40 c. and mixed with 0.12 0f being Copied by diam-type peper in a diaz@ ebpier- The kg. ef Turkey red eil as en emuieifiei, iii which 5.0 kg. ef 60 COPY also produces a eupy havmg better contrast, than in the color former oil was then dispersed with stirring until the Prior art, When subieeted t0 eieetrophotographythe size of the oil drops was from 3 to 6 microns. The There Was no change ln the 6010i Signal @Ven after so obtained emulsion was diluted with water at 4050 exposure t0 Sunllsht, ultravlolet rays Or ares for a 1011s C, to 90; 1, and its PH was adjusted to from 4.0 to 4.2 by time. When the coating surface was subjected to heat treatthe addition of 10% acetic acid with stirring, thereby ac- (55 ment at 150 C- for 10 hours and t0 radiatiOn 0f ultracumulating a colloid around the oil drops to form cap- Violet rays and then a Copy Was formed by reaction With sules. Continuing the stirring for about 20 minutes, the a Clay Paper, the Colored marks Produced Were satisfaccapsules were cooled from the outside by ice water and tOry and gave better results, in Particular, in terms 0f geljed or xed At 20 Q 1 liter of 37% formalin was light resistance than copies produced from materials free added thereto to harden the xed walls of the capsules. 70 of the Compound of the inVenti0n- This is Perhaps due Where it is desired to harden them further, an aqueous to the. fact that the Compound sets as an absorbent 0f 15% caustic soda solution is added to adjust the pH to Ultravlolet rays from 9 to 10 and the softening point is thus raised. Example 3 After 30 minutes, the capsule solution was heated with A pressuresensiiive Copying paper was prepared in u stirring for 20 minutes to 50 C. and applied to a suitable 75 similar manner to Example 2 except that 4 parts by weight of 4-methyl 7 N,N dimethyl aminocoumarin (Color Former No. I of Table l) was used in place of the Color Former No. II. A colored mark formed on a clay paper by the resulting pressure-sensitive copying paper was a copy image capable of being reproduced by diazo copying paper or electrophotography and otherwise performed satisfactorily as in the case of the materials of Example 2.

Example 4 A pressure-sensitive copying paper was prepared in a similar manner to Example 2, except that 3.5 parts by weight of 4-propyl-7-N-ethyl-N-benzyl-aminocoumarin (Color Former No. III) or 3.2 parts by weight of 4-phenyl- 7-N,N-dibutyl-aminocoumarin (Color Former No. IIV) or 3.0 parts by weight of 4-(4-methoxyphenyl)-7N,N- dimethyl-aminocoumarin (Color Former No. V) or 3.0 parts by weight of 4(2chlorophenyl)-7-N,Ndimethyl aminocoumarin (Color Former No. VI) or l3.0'parts by weight of 4-(3'-methylphenyl-7-N,Ndiethylaminocou marin (Color Former No. VII) was used in place of the Color Former No. II of Table 1. Although some of the compounds were colored light yellow and the coating surfaces were colored light yellow in some of the yresulting pressure-sensitive copying papers, colored markings formed on clay papers could be copied by diazo-type or electrophotographic copying procedures and increased the light resistance of the images where used together with a leuco compound color former.

What is claimed is:

1. A pressure sensitive copying transfer paper comprising a support and a transfer layer containing as a color former, at least one coumarin compound represented by the following general formula:

in which R1 and R2 each is a radical selected from the group consisting of lower alkyl and aralkyl radicals, and R3 is a radical selected from the group consisting of lower alkyl and aryl radicals, said transfer layer being adapted to transfer said color former onto a second support which carries an electron-acceptor adsorbant thereon, whereupon a color froming reaction takes place between said color former and said electron acceptor adsorbant.

2. The pressure-sensitive copying paper as described in claim 1 wherein the coumarin compound is one selected from the group consisting of 4-methylN,N-dimethylaminocoumarin, 4methyl7-N,N-diethy1-aminocoumarin, 4 propyl-7-N-ethyl-N-benzyl-aminocoumarin, 4 phenyl- 7-N,N-dibutyl aminocoumarin, 4-(4methoxyphenyl-7- N,N dimethyl aminocoumarin, 4-(2-chlorophenyl)-7 N,N-dimethyl-aminocoumarin and 4-(3methylphenyl)7 N,N-diethyl-aminocoumarin.

3. The pressure-sensitive copying paper as described in claim 1 wherein said layer further contains a leuco compound which enters a color forming reaction with an electron-acceptor material.

4. The pressure-sensitive copying paper as described in claim 3 wherein said leuco compound is one selected from the group consisting of Crystal Violet Lactone and Leuco Methylene Blue.

References Cited UNITED STATES PATENTS 3,016,308 l/l962 MacAulay 117-361 3,020,170 2/1962 MacAulay 117--362 3,207,621 9/1965 Newman et al. 117--36.1

MURRAY KATZ, Primary Examiner U.S. Cl. X.R.

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