US 3669711 A
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United States Patent U.S. Cl. 11736.2 7 Claims ABSTRACT OF THE DISCLOSURE Pressure-sensitive copying papers containing a fluoran derivative having the following general formula a R R2 7 3 4, wherein R and R each represents an alkyl group having from 1 to 5 carbon atoms; wherein R represents a hydrogen atom, an alkyl group'having from 1 to 5 carbon atoms, or a benzyl group; and wherein R represents an arylgroup are disclosed. .7 r
BACKGROUND OF THE INVENTION (1) Field of the invention The present invention relates to a pressure-sensitive copyingpaper and more particnlarly'it is concerned with a pressureesensitive copying paper in which a fluoran de- M rivative is used as a color former 1 H I (2) Description of the priorart.
Ordinary pressure-sensitive copying papers-meromposed of an upper sheet prepared by applying to-asupport, such as paper, fine .capsules or microcapsules con;
taining therein an organic solvent solution of a substanpapers are 'composedof the aforesaid upper sheet, the
under sheet, and further an intermediate sheet having on ice In the practice of the combination of the upper sheet and the under sheet or the combination of the upper sheet, the intermediate sheet, and the under sheet, the papers are stacked so that the microcapsule layer contacts the solid acid layer and with localized pressure, the microcapsules at the pressurized portions are ruptured causing the reaction of the color former and the solid acid to form a distinct color. Also, when a pressure-sensitive copying paper of the type having the microcapsules and the solid acid on one surface of a support is locally pressurized, the microcapsules are ruptured to form a distinct color. These pressure-sensitive copying papers are Well known, having been described in U.S. Pat. 2,712,507, U.S. Pat. No. 2,730,457 and U.S. Pat. No. 2,730,456. I
An object of the present invention is to provide a pressure-sensitive copying paper having a high light fastness and capable of forming a black, a dark green, or a dark grey color using only a single color former.
Another object of the present invention is to provide a pressure-sensitive copying paper capable of being colored a desired color such as blue black using the color former of this invention together with a conventional color former and which is neither discolored nor faded by light.
SUMMARY OF THE INVENTION The present invention relates to a pressure-sensitive paper having a layer of microcapsules containing as a color former a fluoran derivative represented by the general formula,
wherein R and R each represents an alkyl group having from 1 to 5 carbon'atoms; wherein R represents a hydrogen atom, an alkyl group having from'l to 5, carbon atoms, or a benzyl group; and wherein Rfrepresents an one surface thereof a layer of microcapsules containing the color former and on the. opposite surface the layer of the solid acid. In another typeof pressure-sensitive.
copying paper, the microcapsules containing the color former and the solid acid are applied to the same surface of a support, such as paper.
DETAILED DESCRIPTION OF THE I INVENTION 7 1 I The inventors reported previously a fluoran derivative having the aforesaid formula in which, however, R is not an aryl group but is ia'hydrogen atom, an alkyl group having from l to 5 carbon atoms or a benzyl group, while R ,R2 and R are the same as described aboye..The fluoran derivative previously found as a color former is black when contacted with a solid acid but has the disadvantage that the color former is changed to a red color when exposed directly to sun light.
In the present invention, such disadvantages are improved by using the fluoran derivative of the above formula. Typical examples of the compounds represented by the above formula are as follows:
Color General formula former number R1 Ra Ra R4 Chemical name 1 02E; 02E H G 3-diethylamino-7-anillno-fluoran.
2 CH; CH; CH: Q 3-dimethylamino-7-(N-methylanilino)-fluoran.
3 H; CzHs H I v Q OH 3-diethylamino-7-(para-toluidino)-fluoran.
4. cam 0,11, H 3-diethyla1nino-7-(n1eta-toluidino )dluoram a CHI I v Y i 5 01H; 0,11 CH; a-diethirlamlnod-(N -niethylanillno)-fluoran. I
e can; can, H a d-diethylamino-F(ortho-toluidlno)-fluoran.
' Y CHAL 3 7.; 0E5 02H: H 3-diethylamino-7-(meta-xylldino)-fluoran.'
I v v s CH8 Y'Y'SN s. 0:115 0211. H 3-diethylarnino-l-(ortho-anisidino)-tluoran.
OCH L i. 7' I: 9 02H; 02H; Q Q 3-diethylamino-7-(N-lienzrlanilino)-flu0ran. 1o CzHu (3H; CH, @0011 3-dlethylamino-7-(N-IuethyLpara-anisidino)-fluoran.
v a 11 03H; (32115 H @0011 3-diethylam1no-7-(para-anisldino)-fluoran. 12 02H; Iso-CzHz n-olm Q 1 '3-N-ethyl-N-isopropyl-amino-7-(N-butyl-anilino)-fluoran.
The color former used in the present invention can be prepared by the followingnianner. I u v That is, general methods for preparing the color formers V wherein R1, R2, R3 and R4 are as above rdefined one a of the present invention are as follows. of Intermediate A, o-(4-dialky1amino-Z-hydroxybenzoyl) RI 'benzoic acid, and one mole of Intermediate 'B', p-N-arylaminophenoLare dissolved in 10-20 moles of sulfuric acid r I v and thersystem is reacted for 2-8 hours at 80-100 C. R4 v After the reaction is over, the reaction product is poured I into a large proportion of ice'wa'ter and the sulfuric acid in "thereaction product is neutralized with an aqueous v v alkali solution, such as an aqueous solution of sodium hy- (rnteymediate B) droxide; to convert the systein into a slightly alkaline state.
1, The product thus precipitated'is extracted from the aqueous phase "toluenegfand the like, concentrated and dried. Thecr'ude product thus obtained is then recrystal- Ra I lized. fron1 benzene, ethenrethanol or. a mixture thereof.
The color, formers of theapresent invention can be prepared by the following "method generally; the method 5Bin h wver',' applicable to only the case of preparing a color former having the aforesaid general formula wherein R is a hydrogen atom;
(Intermediate B) wherein R R and R are as above defined and R represents an alkyl group having 1 to 5 carbon atoms or an aryl group.
1 One mole of o-(4-dialkylamino-2-hydroxybenzoyl)-benzoio acid is caused to react with one mole of p-(N-acyl- N-arylamino)-phenol in concentrated sulfuric acid for 8-50 hours at 30l00 C. and the reaction product is pouredin a large proportion of ice-cooled water to form a precipitate, which is recovered and heated in diluted sulfuric acid or diluted hydrochloric acid for 3-6 hours at 90-100" C. to liberate the acyl group (COR'). By neutralizing the product with an aqueous alkali solution, th color former desired is obtained.
Intermediate A used as a starting material for preparing the color former of this invention, can be prepared according to a known method as described in Fliedlendar, vol. 4, page 260, by refluxing under heating for a few hours 1 mole of meta-dialkylamino-phenol and 1 mole of phthalic anhydride in a solvent such as toluene.
Intermediate B having thewaforesaid general formula, wherein R is hydrogen atom, can be prepared as product (11) below by a known method as described in Chemical Abstracts, 52, 718421, by heating an arylamine (I), hydroquinone, and cone. sulfuric acid to cause a dehydration and condensation reaction.
wherein R represents an aryl group.
Furthermore, Intermediate B having the above-described general formula wherein R is an alkyl group having from ltto 5 carbon atoms or a benzyl group can be prepared by. alkylating or benzylating compound (H) shown above in a conventional manner.
Moreover, Intermediate B shown above can be prepared by acylating compound (II) in a conventional manner.
Preparation of the color formers of the present invention is further illustrated by theexamples given hereinafter.
6 PREPARATION EXAMPLE 1 Preparation of color former No. 1: Color former No. 1 was prepared by causing the dehydration reaction of Intermediate A, wherein R is C H and R is C H o-(4-diethylamino-2-hydroxybenzoyl) benzoic acid, and Intermediate B, in which R is H and R is a phenyl group, p-anilinophenol, in concentrated sulfuric acid by the same procedure as in the general method described above. The product was recrystallized from a benzene-ethanol mixture to provide white crystals of the color former having a melting point of 182-185 C.
PREPARATION EXAMPLE 2 Preparation of color formers 2-12: The same procedure as used in Preparation Example 1 was followed using Intermediate A and Intermediate B corresponding to each color former to provide the color former desired.
The melting points of the color formers thus prepared and the visible absorption of the color formers in acetic acid are shown in the table below.
PREPARATION EXAMPLE 3 Preparation of color formers Nos. 1, 3-4, and 6-8 by the second method: By applying the second method described using 1 mole of o-(4-diethylamino-2-hydroxybenzoyl)benzoic acid and 1 mole of p-(N-acetanilino)- (or N-benzoylanilino)phenol, color former No. 1 was also obtained. The crystals of the color former had the same melting point, same infrared spectrum, and same visible absorption spectrum in acetic acid as those of the color former No. 1 prepared in Preparation Example 1.
Maximum Color Melting absorpt1on(m ormer Solvent for pom irumber recrystallization 0.) x1 A2 446 605 450 605 451 616 447 610 451 605 450 601 451 605 455 600 452 606 456 596 451 596 455 610 1 Amorphous solid.
The color formers Nos. 3, 4, 6, 7 and 8 were also prepared in the same manner using the corresponding startlng materials. r For preparing the pressure-sensitive copymg paper of the present invention using the color formers described above, and/or conventional color formers such as crystal violet lactone, leuco methylene blue, malachite green lactone, rhodamine B lactram, and the like, the known method disclosed in, for example, the specification of US. Pat. Nos. 2,548,366, 2,800,457 and 2,800,458, that is, a method of preparing microcapsules utilizing a co-acervation technique can be employed. However, since the feature of the present invention is in the use of the color former and the function of the pressure-sensitive copying paper of the present invention is not influenced by the method of preparing the pressure-sensitive copying paper employed, other methods than above described can also be employed in the present invention.
The proportion of the color former used usually ranges from 1 to 10% by Weight to the amount of the oily solvent employed.
Also, as the electron-acceptive solid acid, suitable materials are clays, such as acid clay, active clay, attapulgite, zeolite or bentonite; organic acid maerials, such as succinic acid, tannic acid, gallic acid or pentachlorophenol resins, phenol compounds and phenolic resins. As the organic solvent for dissolving the color former, suitable solvents are chlorobenzene, chlorinated paraflins, and diphenyl chloride.
The pressure-sensitive copying paper of this invention is substantially colorless before color formation and when the copying paper is locally pressed together with the layer of the solid acid, the color forming reaction occurs instantaneously to form a black, drak green or dark grey color. That is, the color thus formed absorbs the entire visible region of from about 410 ru to about 650 m and also has absorption in the spectral region of from about 350 Inn to about 420 mp. This makes it possible to copy on a diazotype light-sensitive paper. Furthermore, the pressure-sensitive copying paper has excellent light fastness as compared with conventional ones.
Now, the invention will be explained by the following examples in which the pressure-sensitive copying papers using the above-mentioned color formers shown by the general formula are illustrated.
Example l.-Three grams of each of the color formers No. 1 to No. 12 were processed as follows. The color former was dissolved in 100 g. of diphenyl trichloride and the solution was added to a solution of 20 g. of gum arabic dissolved in 160 g. of water and then the mixture was emulsified. Then, a solution of 20 g. of acid-treated gelatin in 160 g. of water was added to the resultant emulsion, the pH of the system was reduced to 5 by adding acetic acid with stirring constantly, and then 500 g. of water was added to cause co-acervation, whereby a concentrated gelatin-gum arabic film was formed around an oil drop having dissolved therein the color former. Thereafter, the pH of the system was further reduced to 4.4 and then 4 g. of 37% formalin was added as a hardening agent. The above procedures were all conducted at a temperature of 50 C. Thereafter, the temperature of the system was lowered to C. for gelling the concentrated liquid film around the oil drop and further the pH thereof was increased to 9 for improving the hardening effect. Then, by allowing the system to stand for a few hours, the capsulation was finished. The capsule-containing solution thus prepared was applied to a paper by roll coating or air-knife coating and dried to provide the pressure-sensitive copying paper (upper sheet). The upper sheet was placed on a clay-coated sheet (under sheet prepared by applying the above-described active clay to a paper) and they Were locally pressurized by handwriting. Thereby, the following color was instantly formed on the clay-coated paper.
That is, color formers No. 1, No. 6 and No. 7 were colored black; color formers No. 2, No. 3, No. 4, No. 5, N0. 9, and No. 10 were colored dark green, and color formers No. 8 and No. 11 were colored dark grey. Also, the dyes thus colored were not faded when they were exposed to sun light for a long period of time and wetted with water or glycerine. Also, when the upper sheet having the layer of the microcapsules containing the color former was heated to 100 C. for 20 hours and exposed to sunlight for a long period of time, the color forming ability of the copying paper was not degraded. In other words, the light fastness, water resistance, and heat resistance of the pressure-sensitive copying paper of this invention before color forming and after color forming were sufliciently high from a practical standpoint when the copying paper was stored for a long period of time.
Example 2.--The same procedure as used in Example 1 was followed except that 1 g. of the color former No. 1, 1 g. of the color formed No. 3, 0.5 g. of Malachite Green Lactone, and 0.5 g. of benzoyl leucomethylene blue were used as a mixture thereof instead of the color former in the Example 1. The results were that the clay-coated paper was colored blue black.
What is claimed is:
1. A pressure-sensitive copying paper comprising a support having coated thereon a layer of microcapsules containing at least one fluoran derivative having the following general formula,
wherein R and R each are an alkyl group having from 1 to 5 carbon atoms,.wherein R is selected from the group consisting of a hydrogen atom,*an alkyl group having from 1 to 5 carbon atoms, and a benzyl group, and wherein R is an aryl group. v
2. The pressure-sensitive copying paper as claimed in claim 1 wherein said fluoran derivative is a member selected from the group consisting of 3 -diethylamino-7-anilino fiuoran,
3 -dimethyla mino-7- (N-methylanilino) -fluoran, 3-diethylamino-7- (p-toluidino) -fluoran,
3 -diethylamino-7- m-toluidino -fluoran, 3-diethylamino-7- (N-methylanilino) -fluoran, 3-diethylamino-7- o-toluidino) -fluoran,
3 -diethylamino-7- m-xylidino) -fluoran, 3-diethylamino-7- (o-anisidino) -fluoran,
3 -diethylamino-7- (N-b enzylanilino) -fluoran, 3-diethylamino-7- (N-methyl-p-anisidino -fiuoran, 3 -diethylamino-7- (p-anisidino) -fluoran, and
3 -N-ethyl-N-isopropylamino-7- N-butyl anilino) -fiuoran.
claim 1 wherein said fluoran derivative is capable of forming a distinct color when contacted with a material selected from the group consisting of acid clay, active clay, attapulgite, zeolite, phenolic compounds and phenolic resins. 4. The pressure-sensitive copying paper as claimed in claim 1 wherein said fluoran derivative is used together with at least one color former selected from the group consisting of crystal violet lactone, leuco methylene blue, malachite green lactone and rhodamine B lactam.
5. A pressure-sensitive copying paper comprising an upper sheet having coated thereon a layer of microcapsules containing at least one fluoran derivative having the following general formula, 3 v
wherein R and R each are an alkyl group having from 1 to 5 carbon atoms, wherein R is selected from the group port having coated on the same surface thereof two layers,-
one of said layers comprising microcapsules containing at least one fluoran derivative having the following general formula,
3. The pressure-sensitive copying-paper as claimed in the UNITED 7. The pressure-sensitive copying paper as claimed in claim 6 wherein said eleetro accepting material is a member selected from the group consisting of acid clay, active clay, attapulgite, phenol compounds and phenolic resins.
References Cited STATES PATENTS Kimura et al 117--36.8 Kimura et a1. 117-362 Katayama et a1. 117-362 MURRAY KATZ, Primary Examiner US. Cl. X.R.