U.S. patent number 3,725,416 [Application Number 05/093,897] was granted by the patent office on 1973-04-03 for 7-piperidinofluoran.
This patent grant is currently assigned to Yamamoto Kagaku Gosei Co., Ltd.. Invention is credited to Nobuharu Sasaki, Mutsuo Terayama, Kenji Yamamoto.
United States Patent |
3,725,416 |
Yamamoto , et al. |
April 3, 1973 |
7-PIPERIDINOFLUORAN
Abstract
Compounds and a pressure-sensitive copying sheet containing said
compounds as a color-forming agent art provided said compounds have
the following general formula: ##SPC1## Wherein each of R.sub.1 and
R.sub.2 is independently alkyl of up to 4 carbon atoms; and each of
X and Y is independently hydrogen, halogen of alkyl of up to 4
carbon atoms.
Inventors: |
Yamamoto; Kenji (Fujiidera,
JA), Sasaki; Nobuharu (Higashiosaka, JA),
Terayama; Mutsuo (Yuge, JA) |
Assignee: |
Yamamoto Kagaku Gosei Co., Ltd.
(Yuge, Yao, JA)
|
Family
ID: |
14208731 |
Appl.
No.: |
05/093,897 |
Filed: |
November 30, 1970 |
Foreign Application Priority Data
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|
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Dec 5, 1969 [JA] |
|
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44/98034 |
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Current U.S.
Class: |
546/6;
546/236 |
Current CPC
Class: |
C09B
11/24 (20130101) |
Current International
Class: |
C09B
11/00 (20060101); C09B 11/24 (20060101); C07d
029/12 () |
Field of
Search: |
;260/293.58,335,336 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Viktorova et al., Chem. Abstracts 64:7546d. .
Ramette et al., J. Am. Chem. Soc. 78, 4872-8 (1956)..
|
Primary Examiner: Jiles; Henry R.
Assistant Examiner: Todd; G. Thomas
Claims
What we claim is:
1. A compound of the formula ##SPC11##
wherein each of R.sub.1 and R.sub.2 is independently alkyl of up to
4 carbon atoms; and each of X and Y is independently hydrogen,
halogen or alkyl of up to 4 carbon atoms.
2. A compound of claim 1 wherein said halogen is chlorine or
bromine.
3. 3-diethylamino-7-piperidinofluoran ##SPC12##
4. 3-diethylamino-5-methyl-7-piperidinofluoran ##SPC13##
5. 3-diethylamino-5-chloro-7-piperidinofluoran ##SPC14##
6. 3-dimethylamino-7-piperidinofluoran ##SPC15##
7. 3-dimethylamino-5-methyl-7-piperidinofluoran ##SPC16##
Description
This invention relates to a pressure-sensitive copying sheet and
more particularly to a pressure-sensitive copying sheet using a
novel fluoran compound as a color forming agent.
As a copying sheet, the so-called "carbon paper" has been used for
a long time. However, as is well known, such carbon paper has a
serious drawback that it stains the hands, clothes, etc. of the
user.
In order to overcome these drawbacks, there has been developed a
pressure-sensitive copying sheet which comprises an upper sheet and
a lower sheet. The back of the upper sheet is coated with a thin
layer of micro-capsules which can be ruptured by a local pressure
imparted, for example, by handwriting with pen, pencile, ball-point
pen or the like or by typewriting and which contain an electron
donating, adsorbable and color-developable colorless organic
compound (hereinafter referred to as "color forming agent")
dissolved in a non-volatile solvent or oil. The surface of the
lower sheet is coated with a thin layer of fine particles of an
electron acceptive solid adsorbent (e.g. acid clay, silton,
attapulgite, zeolite, bentonite, phenolic resin, etc.) dispersed in
a binder. In using such pressure-sensitive copying sheet, the upper
sheet is placed upon the lower sheet in such a manner that the back
face of the upper sheet would contact the surface of the lower
sheet. When a local pressure is applied on the exposed surface of
the upper sheet by handwriting or typewriting, the micro-capsules
are ruptured and the color-forming colorless agent is transferred
from the upper sheet to the surface layer on the lower sheet and is
adsorbed by the electron acceptive adsorbent to develope color.
As for such color-forming colorless organic compounds there have
been proposed various substances such as Crystal Violet Lactone,
Malachite Green Lactone, Benzoyl Leucomethylene Blue, Michler's
Hydrol, N-Phenyl Leucoaulamine, Leucotriphenyl Methane, Rhodamine
Lactone, Diaminodiphenyl Methane, Spirodipyran, Benzodifurane, etc.
However, in all the pressure-sensitive color-developing copying
sheets now commercially available, there are used Crystal Violet
Lactone (referred to as "CVL" hereinafter) and Benzoyl
Leucomethylene Blue (referred to as "BLMB" hereinafter) together as
their main color-forming agent.
As is known, CVL has an advantage that it is high in the
color-forming reaction velocity but has a drawback that the
resistance to light and water or moisture is poor. On the contrary,
BLMB has a drawback that its color-forming reaction velocity is low
but has an advantage that it, once color-developed, has a high
resistance to light and water or moisture. Therefore, when these
two agents are used together the respective drawbacks are mutually
compensated.
However, such CVL + BLMB mixed system has another drawback that it
can develope only a bluish color and not black.
The development of black color is desirable because a black image
is more distinctively legible and because a black image can be
reproduced or copyed in a more sharp, dense and legible image, than
from a bluish image, by the presently available copying machines of
various types such as Xerox, thermography, etc. utilizing
ultraviolet rays or short wave visible rays.
Therefore there have been proposed various measures to resolve the
above problems. Thus, the first one is to use a mixture of various
color-forming agents to develope a color as close to black as
possible. Most typical proposal in this respect is to add a red
color-forming agent (such as Rhodamine-lactam) to the above
mentioned CVL + BLMB system to develope violet color which is more
close to black than blue of the CVL + BLMB system. Another measure
which has been proposed is to incorporate an ultraviolet absorber
into the color forming agent so that the developed image may be
reproduced by copying machines. However, these methods have not
been fully satisfactory.
Therefore, a more endeavor has been directed to the development of
a pressure-sensitive copying sheet which can form black color copy.
The most simple way to attain the above object would, of course, be
to prepare a color-forming colorless substance which alone can
develope black color when adsorbed by an electron acceptive
adsorbent on the lower copy sheet. However, as a result of various
experiments and researches, it has been concluded that it is very
difficult in the present chemical technology to synthesize a
color-reactive colorless substance which alone can develope black
color. Therefore, nowadays, researches are being concentrated
mostly to the production of a pressure-sensitive copy sheet which
makes use of a mixture of various different color-forming
substances which can develope different colors such as red, blue,
yellow, etc. and together or jointly form black color.
Therefore, it is a main object of this invention to provide novel
compounds which are useful in developing black and suitable for use
in pressure-sensitive copying sheet.
Another object of this invention is to provide a pressure-sensitive
copying sheet by using the above mentioned novel compound.
Other objects of this invention will become apparent from the
following description.
Briefly, this invention provides color-developable substantially
colorless organic compounds having the following general formula:
##SPC2##
wherein each of R.sub.1 and R.sub.2 is a lower alkyl radicals
having 1 - 4 carbon atoms and each of X and Y a member selected
from the group consisting of hydrogen, halogen atoms (e.g.
chlorine, bromine, etc.) and lower alkyl radicals of 1 - 4 carbon
atoms.
The piperidino radical-containing fluoran compounds represented by
the above indicated general formula (I) are novel compounds which
are substantially colorless but, upon adsorption on a phenolic
resin (electron acceptive adsorbent) can develope black color. Upon
adsorption on an inorganic electron acceptive adsorbent usually
used in pressure-sensitive copying sheet, the said compounds may
develope a color ranging from dark red to reddish violet. Therefore
in latter cases (the use of an inorganic electron accepting solid
adsorbent), black color can be developed by using the compound of
the formula (I) together with a small amount of other color
developing agent such as 3-diethylamino-7-benzylamino fluoran, etc.
disclosed in U.S. Pat. No. 3,501,331 (Canadian Pat. No.
814,948).
Further, the piperidino group-containing fluoran compounds of this
invention are compatible with conventional color-forming agent,
soluble in various solvents or oils and the color developed
therefrom is high in resistance or fastness to light. Therefore,
the color-forming agents (piperidino group-containing fluoran
compounds) of this invention are excellent for use in making
pressure-sensitive copying sheet.
Typical compounds belonging to the above general formula (I) are
indicated below together with their melting points and colors to be
developed thereby upon adsorption on silton and phenolic resin.
A. 3-diethylamino-7-piperidinofluoran ##SPC3##
m.p. 182.degree. - 185.degree.C. Dark red on silton Black on
phenolic resin
B. 3-diethylamino-5-methyl-7-piperidinofluoran ##SPC4##
m.p. 152.degree. - 153.degree.C. Dark reddish violet on silton
Black on phenolic resin
C. 3-diethylamino-5-chloro-7-piperidinofluoran ##SPC5##
m.p. 125.degree. - 130.degree.C. Dark red on silton Black on
phenolic resin
D. 3-dimethylamino-7-piperidinofluoran ##SPC6##
m.p. 193.degree. - 195.degree.C. Dark red on silton Black on
phenolic resin
E. 3-dimethylamino-5-methyl-7-piperidinofluoran ##SPC7##
m.p. 235.degree. - 236.degree.C. Dark reddish violet on silton
Black on phenolic resin
The essential and novel feature of this invention is in the use of
the novel piperidino group-containing fluoran compound of the
general formula (I) as a color-forming agent for a
pressure-sensitive copying sheet. In making a pressure-sensitive
copying sheet any conventional manner which is well known in the
art may be used and therefore no detailed explanation thereabout
will be required. In this connection, reference may be made, for
example, to U.S. Pat. Nos. 2,548,366, 2,800,457, 2,800,458 and
3,501,331. However, when a phenolic resin (e.g. novolac resin,
p-phenylphenol-formaldehyde condensation product,
p-chlorophenol-formaldehyde condensation product, etc.) is used as
the electron accepting absorbent the fluoran compound of this
invention can develope black color and therefore it is preferable
to employ a phenolic resin as the electron accepting absorbent.
The piperidino-containing fluoran compounds of the general formula
(I) may be prepared, for example, as follows. Thus, p-anisidine or
its nucleus substitute is reacted with 1,5-dibromopentane to obtain
p-peridinoanisol or its derivative of the formula: ##SPC8##
, which is then condensed with an
o-(4-dialkylamino-2-hydroxy-benzoyl)-benzoic acid of the formula:
##SPC9##
(wherein X. Y, R.sub.1 and R.sub.2 are as defined before) in the
presence of a condensing agent such as sulfuric acid to obtain the
desired piperidino-containing fluoran compound of the formula
I.
As a more specific example, the production of
3-diethylamino-7-piperidinofluoran of the formula A is as follows.
Thus, 27 g. of p-anisidine and 17.5 g. of 1,5-dibromopentane in 50
ml. of methanol were refluxed for 17 hours. To the reaction mixture
was added 50 g. of 20 percent aqueous solution of sodium hydroxide,
and the formed oily layer was separated and purified by vacuum
distillation to recover the fraction of 114.degree.-118.degree.C./4
mmHg., which is colorless p-piperidinoanisol. Yield 9.5 g. (65.6
percent of theory). ##SPC10##
Elementary analysis:
Calculated N 7.33 %
Found N 7.27 %
Then 5.73 g. of the above prepared p-piperidino anisol and 9.4 g.
of o-(4-diethylamino-2-hydroxybenzoyl)benzoic acid were reacted
together in 50 g. of 98 percent sulfuric acid for 60 hours at
35.degree.-40.degree.C. while stirring. Then the reaction mixture
was poured into 200 ml. of water. The solution was rendered
alkaline with the addition of 200 ml. of 25 percent solution of
sodium hydroxide. The formed precipitate was recovered by
filtration and dried to obtain 8.5 g. of violet brown powder, which
was recrystallized from 300 ml. of benzene with the use of 2 g.
active carbon. Thus, there were obtained 7.7 g. (yield 56.5
percent) of slightly reddish white crystals (m.p.
182.degree.-185.degree.C.) of
3-diethylamino-7-piperidinofluoran.
The invention will be further explained by referring to the
following Examples which are given for illustra purpose only and
not for limiting the scope of the invention.
EXAMPLE 1
In 500 ml. of water there were dissolved at 40.degree.C. 600 g. of
gelatin and 60 g. of gum arabic. On the other hand, 5 g. of
3-diethylamino-7-piperidinofluoran were dissolved in 150 g. of
diphenylchloride. The latter solution was added to the former
solution and the mixture was emulsified by a homogenizer. Then
water at 50.degree.C. was added thereto until the whole becomes
2000 ml. Then 90 ml. of 10 percent acetic acid were added and the
mixture was stirred and further added with water at 50.degree.C.
until the whole becomes 4 kg. The stirring was continued for one
hour and the mixture was cooled with ice water while continuing the
stirring. When the mixture was cooled below 10.degree.C., there was
added a 10 percent aqueous solution of sodium hydroxide to increase
the pH up to 9, whereupon the cooling is discontinued and the
mixture is allowed to stand to return to the room temperature.
The coating composition thus prepared was applied on the lower
surface of the upper sheet by roll-coating and dried. Apart from
the above, an aqueous gelatine solution containing powder of
phenolic resin (p-phenylphenol-formaldehyde condensation product)
dispersed therein was applied on the upper face of a lower sheet
and was dried.
The coated upper sheet was placed on the coated lower sheet in such
a way that the respective coated layers contact intimately with
each other. Upon writing with an inkfree steel point pen on the
upper face of the upper sheet to exert pressure, black color was
rapidly developed on the written area on the upper face of the
lower sheet. This color did not fade even upon exposure to the sun
light for a long time.
The same procedure as above was repeated except that there was used
except silton powder was used in place of the phenolic resin
powder. Upon writing there was developed dark red color, which is
excellent in light-resistance.
EXAMPLE 2
The same procedure as in Example 1 was repeated except that
3-diethylamino-5-methyl-7-piperidinofluoran was used instead of
3-diethylamino-4-piperidinofluoran. Upon writing, black color was
developed when phenolic resin used as the absorbent, while dark
reddish violet was developed when silton was used as the
adsorbent.
EXAMPLE 3
The procedure same as in Example 1 was repeated except that,
instead of 5 g. of 3-diethylamino-7-piperidinofluoran, there were
used a mixture of 4.5 g. of 3-diethylamino-7-piperidinofluoran and
0.5 g. of 3-diethylamino-7-benzylaminofluoran (U.S. Pat. No.
3,501,331), and silton was used as the adsorbent. Upon writing
there was developed black color.
EXAMPLE 4
The same procedure as in Example 1 was repeated except that
3-diethylamino-5-chloro-7-piperidinofluoran (C),
3-dimethylamino-7-piperidinofluoran (D) or
3-dimethylamino-5-methyl-7-piperidinofluoran (E) was used in place
of 3-diethylamino-7-piperidinofluoran. Upon writing the following
colored copies were obtained.
Color forming agent Phenolic resin Silton C Black Dark red D Black
Dark red E Black Dark reddish violet
* * * * *