U.S. patent number 3,836,383 [Application Number 05/193,151] was granted by the patent office on 1974-09-17 for pressure sensitive recording paper.
This patent grant is currently assigned to Fuji Photo Film Co., Ltd.. Invention is credited to Masayuki Aoki, Masataka Kiritani, Hiroharu Matsukawa.
United States Patent |
3,836,383 |
Kiritani , et al. |
September 17, 1974 |
PRESSURE SENSITIVE RECORDING PAPER
Abstract
A pressure-sensitive recording paper comprising a support having
coated thereon a layer of color former, said color former dissolved
in at least one compound represented by the following formula:
##SPC1## Wherein n is an integer of 1 to 8, R and R' each represent
a member selected from the group consisting of alkyl groups
containing one to eight carbon atoms, and a hydrogen atom, p and q
represent the number of alkyl groups, p + q being an integer of 1
to 3, and R and R' may be the same.
Inventors: |
Kiritani; Masataka (Shizuoka,
JA), Matsukawa; Hiroharu (Shizuoka, JA),
Aoki; Masayuki (Kanagawa, JA) |
Assignee: |
Fuji Photo Film Co., Ltd.
(Kanagawa, JA)
|
Family
ID: |
14122264 |
Appl.
No.: |
05/193,151 |
Filed: |
October 27, 1971 |
Foreign Application Priority Data
|
|
|
|
|
Oct 27, 1970 [JA] |
|
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45-94877 |
|
Current U.S.
Class: |
503/213; 8/500;
8/580; 8/617; 264/4.4; 8/526; 8/614; 264/4.3; 264/4.7;
428/402.2 |
Current CPC
Class: |
B41M
5/1655 (20130101); Y10T 428/24835 (20150115); Y10T
428/2984 (20150115) |
Current International
Class: |
B41M
5/165 (20060101); B41c 001/06 () |
Field of
Search: |
;117/36.2,36.8 ;252/316
;8/94 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Martin; William D.
Assistant Examiner: Pianalto; Bernard D.
Attorney, Agent or Firm: Sughrue, Rothwell, Mion, Zinn &
Macpeak
Claims
What is claimed is:
1. A pressure sensitive recording paper comprising a support having
coated thereon a layer of color former, said color former dissolved
in at least one compound represented by the following formula:
##SPC10##
wherein n is an integer of 1 to 8, R and R' each represent a member
selected from the group consisting of alkyl groups containing one
to eight carbon atoms, and a hydrogen atom, p and q represent the
number of alkyl groups, p + q being an integer of 1 to 3, and R and
R' may be the same.
2. The pressure sensitive recording paper as claimed in claim 1,
wherein said compound is a member selected from the group
consisting of: ##SPC11##
3. The pressure sensitive recording paper of claim 1, wherein said
compound is used as a mixture with a solvent selected from the
group consisting of a petroleum fraction, a synthetic oil and a
plant oil.
4. The pressure sensitive recording paper of claim 1, wherein said
color former and said compound are contained in microcapsules.
5. The pressure sensitive recording paper of claim 3, wherein said
petroleum fraction is a member selected from the group consisting
of liquid paraffin, kerosene and naphtha.
6. The pressure sensitive recording paper of claim 3, wherein said
synthetic oil is a member selected from the group consisting of
chlorinated paraffin, chlorinated diphenyl, hexahydroterphenyl,
alkylnaphthalenes and alkylated polyphenyls.
7. The pressure sensitive recording paper of claim 3, wherein said
plant oil is a member selected from the group consisting of
cottonseed oil and linseed oil.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a pressure-sensitive recording paper.
More particularly, it relates to a pressure-sensitive recording
paper using a compound, in which two alkyl-substituted benzene
nuclei are connected with each other through the unit --C.sub.n
H.sub.2n --, as a solvent for a color former: ##SPC2##
Wherein n is an integer of from 1 to 8, R and R' each is an alkyl
group having one to eight carbon atoms or a hydrogen atom, p and q
each is the number of alkyl groups, p + q being an integer of 1-3,
and wherein R and R' may be the same.
2. Description of the Prior Art
The object of the present invention is to obtain a
pressure-sensitive recording paper having no unpleasant smell and
toxicity, and capable of forming a color image having a higher
density without giving a color fog.
Usually, as pressure-sensitive recording paper, there are those
comprising so-called upper paper prepared by dissolving a
substantially colorless compound (hereinafter referred to as a
"color former") in an organic solvent, encapsulating it, and then
coating the capsules onto a support; lower paper prepared by
coating a color-developing material (hereinafter referred to as a
"color developer"), which is capable of forming colored images,
onto another support; and, in some cases, middle paper prepared by
coating capsules containing a color former onto one side of a
support and a color developer onto the other side thereof, or those
containing said capsules and a color developer onto the same side
of a support.
In the case of the combination of upper and lower paper, or upper,
middle and lower paper, color is developed by locally pressing in
such a way that the capsule layer comes into contact with the color
developer layer to decompose the capsules located at the pressed
part and to cause reaction between the color former and the color
developer. When a pressure sensitive recording paper having
capsules and a color developer agent on the same surface thereof is
used, color will be developed by pressing in the same way. As the
color developer, active clay materials, such as acid clay, active
zeolite and bentonite, or organic acidic materials, such as
succinic acid, tannic acid, gallic acid, pentachlorphenol and
phenol resin are generally used. As a color former for a pressure
sensitive recording paper, malachite green lactone, benzoyl
leucomethylene blue, crystal violet lactone, rhodamine B lactom,
3-dialkylamino-7-alkylfluorans,
3-methyl-2,2'-spirobi(benzo[f]chromene), etc. are used.
The conditions a solvent dissolving a color former for pressure
sensitive recording paper should satisfy are:
a. to have enough solubility to dissolve a necessary amount of
color former,
b. to have a high boiling point so as not to vaporize in a
heat-drying process and in a place of elevated temperature,
c. not to be eluted on encapsulation,
d. not to desensitize or prevent the color formation on the lower
paper,
e. not to provide changes, such as decomposition of the color
former, color formation, etc.,
f. to have a low viscosity so that the effusion thereof from inside
the capsules can be freely done on breakage of the capsules, and to
have a small rise in viscosity, even at a low temperature,
g. to have no unpleasant smell,
h. to have little toxicity to human beings and animals,
and the like. Among these, conditions (a)-(e) are especially of
importance and, if one of these conditions is not satisfied, the
solvent cannot be used as a solvent for a color former.
In fact, however, solvents satisfying conditions of said (a)-(h)
have so far not been found. Therefore, as things are, those
prepared by mixing several kinds of solvents in a suitable ratio
are used.
That is, ethers do not satisfy the conditions of (a) and (d),
alcohols do not satisfy the conditions of (a), (c) and (d),
paraffins do not satisfy the conditions of (a), ketones, esters,
olefins and amines do not satisfy the conditions of (d), and
organic acids do not satisfy the conditions of (c), and usual
aromatic hydrocarbons do not satisfy the conditions of (a), (g) and
(h). Chlorinated diphenyl now used as a solvent for pressure
sensitive recording paper, nearly satisfies the conditions of (a)
to (e). It has, however, defects in that, at a low chlorination
degree, it has a peculiar unpleasant smell, while it has low
viscosity and that, at high chlorination degree, it has high
viscosity, and does not have much of an unpleasant smell. That is,
the viscosities of low chlorinated trichlorodiphenyl and
tetrachlorodiphenyl are comparatively low. However, they have a
peculiar unpleasant smell. Highly chlorinated pentachlorodiphenyl
and hexachlorodiphenyl have considerably reduced unpleasant smell,
but their viscosity conspicuously increases on the other hand.
Hexachlorodiphenyl has no fluidity at a room temperature.
Therefore, the pressure-sensitive recording paper wherein low
chlorinated trichlorodiphenyl and tetrachlorodiphenyl are used, has
the defect of having an unpleasant smell. The pressure sensitive
recording paper wherein highly chlorinated pentachlorodiphenyl and
hexachlorodiphenyl are used, has the defect in that the effusion
thereof is difficult to be freely done due to their high viscosity
and that sufficient color density cannot be obtained, while they
have less of an unpleasant smell. The pressure-sensitive recording
paper wherein the mixture of chlorinated diphenyl with a low
chlorination degree and the same with high chlorination degree is
used, is a little more improved in the smell than that wherein
chlorinated diphenyl with low chlorination degree is used
separately and, in the density of the color formed, the former is a
little more improved than that wherein highly chlorinated diphenyl
is used independently, but the former has still considerable
unpleasant smell and the density of color formed is not sufficient.
In addition, chlorinated diphenyl is slightly decomposed by light
to form hydrogen chloride. Accordingly, the capsule coated sheet
wherein chlorinated diphenyl is used has the defect that, when it
is exposed to light for a long time, the generated hydrogen
chloride will be reacted with the color former to cause colored
fog. Furthermore, this capsule coated sheet wherein the colored fog
took place has less color developing ability onto the lower paper,
and a sufficient density of the color formed cannot be obtained.
Besides, chlorinated diphenyl has appreciable toxicity to human
beings and animals. Therefore, the conventional pressure sensitive
recording paper wherein chlorinated diphenyl is used, has had the
defects that it has unpleasant smell, that sufficient density of
the color formed cannot be obtained, that when exposed to light for
a long time, colored fog on capsule coated sheet and the lowering
of the color developing ability thereof to the lower paper take
place, and that it has a problem in its toxicity.
SUMMARY OF THE INVENTION
We, the inventors, as the result of many investigations concerning
these kind of solvents, have found that the specific compound
represented by the general formula I has properties which are quite
adequate for our purpose, and accomplished this invention. That is,
the present invention is characterized in that, in the pressure
sensitive recording paper, the compound represented by the general
formula (I) is used as a solvent for the color former, separately
or in combination with other solvents.
The compound (I) in this invention is characterized in that two
alkyl substituted benzene nuclei are connected with each other
through a --C.sub.n H.sub.2n -- bond and, as is different from the
usual aromatic compounds, the compound (I) of the present invention
has a considerably high boiling point, does not vaporize off in a
heat drying process or in a place of the elevated temperature, has
no unpleasant smell, and in addition, it has no toxicity to human
beings and animals.
DETAILED DESCRIPTION OF THE INVENTION
The reason why p + q in the compound (I) used in the present
invention is restricted to not more than 3, is that, when p + q is
not less than 4, the viscosity thereof conspicuously increases or
the compound becomes solid, which is not desirable.
The reason why the number of the carbon atoms contained in R and
R', and that in the --C.sub.n H.sub.2n -- existing between the two
benzene nuclei is not more than 8 and 8, respectively, is that,
when the number of the carbon atoms contained in R and R' becomes
not less than 9 and n becomes not less than 9, the viscosity
thereof conspicuously increases and the solubility of a color
former thereto decreases, which is not desirable.
The compound of this invention having a particularly restricted
structure, satisfies the aforesaid conditions of (a)-(e) demanded
for a solvent for the color former of pressure sensitive recording
paper. In addition, it has the excellent advantages that there is
little rise in viscosity, even at a low temperature, that it has no
unpleasant smell or toxicity to human beings and animals, that it
raises the stability of the capsule coated sheet to light, that,
even when the capsule coated sheet is exposed to light for a long
time, the colored fog of the sheet is remarkably less compared with
conventional ones, that the color developing ability in developing
this capsule coated sheet onto the lower paper does not decrease
like the conventional ones, and the like. The pressure sensitive
recording paper of this invention is excellent also in that it has
a higher density with respect to the color formed compared with
conventional pressure sensitive recording paper, wherein
chlorinated diphenyl is used. Therefore, it can be said that the
compound (I) used in the present invention having a particularly
restricted structure is extremely excellent as a solvent for a
color former of pressure sensitive recording paper.
The compound of the general formula (I) of the present invention
may be used in combination with other solvents. As solvents to be
mixed together, there are petroleum fractions such as liquid
paraffin, kerosene, naphtha, etc., synthesized oils, such as
chlorinated paraffin, chlorinated diphenyl, hexahydroterphenyl,
alkylnaphthalenes, alkylated polyphenyls, etc., and vegetable oils,
such as cotton seed oil, linseed oil, etc. These solvents are mixed
and used together in order to adjust the viscosity, to control the
solubility of a color former, and to increase the quantity for the
reduction of cost, etc.
This invention is characterized by using the compound of the
general formula (I) having a particularly restricted structure as a
solvent for a color former of pressure sensitive recording paper
and, accordingly, all of the publicly known art can be applied as a
method or process for encapsulating this solvent. Therefore, the
present invention is not restricted by the method or process for
the encapsulation.
The present invention will be further explained by the following
Examples, which are merely illustrative and not limitative of the
present invention.
In the examples of the present invention, there is used a clay
paper (lower paper) prepared as follows. That is, 100 g of sulfuric
acid processed acidic terra abla was dispersed in 280 g of water
containing 6 g of 40 percent sodium hydroxide aqueous solution
using homogenizer. Thereafter, 50 g of a 10 percent aqueous
solution of sodium salt of casein and 30 g of a styrene butadiene
latex (trade name: Dow Latex 626, made by Dow Chemical Co.), were
added thereto as a binder, and coated on a paper by air knife
coating, and dried to obtain the clayed paper.
EXAMPLE 1
To 100 g of 2,4-dimethyldiphenylmethane obtained by the reaction
between meta-xylene and benzyl chloride, having the following
formula (b.p. 295.degree. - 296.degree.C/760 mmHg, specific gravity
(D.sub.4.sup.20 ) 0.9951); ##SPC3## was dissolved 3 g of crystal
violet lactone. The resulting solution was then added to a solution
of 20 g of gum arabic and 160 g of water to emulsify. Thereafter,
20 g of acid processed gelatin and 160 g of water were added
thereto and the pH thereof was reduced to 5 by the addition of
acetic acid under constant stirring, 500 g of water was then added
to cause coacervation. On coacervation, a dense liquid membrane of
gelatin-gum arabic was formed around the oil droplets containing a
color former. The pH was further reduced to 4.4, and 4 g of 37
percent formalin was successively added for hardening the membrane.
Said operation was carried out keeping the temperature of the
system at a temperature of 50.degree.C. Then the system was cooled
to 10.degree.C in order to gel the dense liquid membrane.
Furthermore, in order to raise the effect of hardening, the pH
thereof was raised to 9 and the system was allowed to stand for
several hours to accomplish the encapsulation. The capsule solution
thus obtained was coated on a sheet of paper by air knife coating,
then dried. The pressure sensitive recording paper thus obtained
had no unpleasant smell like that of the conventional pressure
sensitive recording paper wherein chlorinated diphenyl was used as
a solvent. When this paper (upper paper) was superposed on a clay
paper (aforesaid lower paper coated with active clay substance) and
writing was conducted with pressure, there was developed a blue
image on a clayed paper in an instant. The density of this color
developed image was remarkably high compared with that of the
conventional pressure sensitive recording paper. In addition, even
when this upper paper was exposed to sun light for a long time, the
lowering in the color developing ability and colored fog were not
recognized.
EXAMPLE 2
3 g of rhodamine B lactam was dissolved in 100 g of
2,5-dimethyldiphenylmethane obtained by the reaction between
para-xylene and benzyl chloride, having the following formula (b.p.
293.5.degree. - 294.5.degree.C/760 mmHg, specific gravity
(D.sub.4.sup.20) 0.9950); ##SPC4##
and treated in the same manner as in Example 1 to obtain upper
paper. The upper paper thus obtained had no unpleasant smell like
that of the conventional pressure sensitive recording paper. When
this upper paper was superposed on a clay paper and writing was
conducted with pressure, there was developed red image on a clay
paper in a moment. The density of color developed image was
remarkably high compared with that of the conventional recording
paper wherein chlorinated diphenyl was used. Besides, even when
this upper paper was exposed to sun light for a long time, the
lowering in the color developing ability and fog were not
observed.
EXAMPLE 3
2 g of 3-diethylamino-7-methylfluoran was dissolved in a mixture of
80 g of octadecyldiphenylmethane having the following structure
(mixture of several kinds of isomers, b.p.
232.degree.-244.degree.C/10 mmHg); ##SPC5##
and 20 g of paraffin containing 10-12 carbon atoms, treated in the
same was as in Example 1 to obtain upper paper. The upper paper for
pressure sensitive recording paper thus obtained had no unpleasant
smell like that of the conventional pressure sensitive recording
paper prepared by the analogous treatment using chlorinated
diphenyl. When this upper paper was superposed on a clay paper and
writing was conducted with pressure, there was developed a red
image on a clay paper. The density of this color developed image
was remarkably high compared with that of the conventional pressure
sensitive recording paper wherein chlorinated diphenyl was used. In
addition, even when this upper paper was exposed to sun light for a
long time, the lowering in the color developing ability and colored
fog were not observed.
EXAMPLE 4
3 g of 3-diethylamino-7-dibenzylaminofluoran was dissolved in a
mixed oil of 70 g of a mixture of dimethyldiphenylmethane and
ethyl-diphenylmethane having a specific gravity of 0.984 at
25.degree.C, a viscosity of 2.27 centistokes at 50.degree.C and a
refractive index of 1.5684 at 20.degree.C, ##SPC6##
and 30 g of isoparaffin containing 12 - 14 carbon atoms, treated in
the same way as in Example 1 to obtain upper paper. This upper
paper had no unpleasant smell like that of the conventional
pressure sensitive recording paper wherein chlorinated diphenyl was
used. When this upper paper was superposed on a clay paper and
writing was done with pressure, there was developed a blackish
green image on a clay paper. The density of this color developed
image was remarkably high compared with that of the conventional
pressure sensitive recording paper wherein chlorinated diphenyl was
used. In addition, even when this upper paper was exposed to sun
light for a long time, the lowering in the color developing ability
and colored fog were not observed.
EXAMPLE 5
0.2 g of 3-diethylamino-7-diethylaminofluoran was dissolved in 20 g
of 1,1-di-p-toluylethane (having a melting point lower than
20.degree.C and a boiling point of 295.degree. - 300.degree.C/760
mmHg) represented by the following structure: ##SPC7##
and to this were added 5 g of toluylenediisocyanate and 10 g of
methylene chloride containing 3 g of bisphenol A to prepare a first
solution. Thereafter, 3 g of polyvinyl alcohol was dissolved in 25
g of water, and to this was added said first solution under
vigorous stirring to emulsify. The resulting emulsion was poured
into 150 g of water kept at 50.degree.C, and the temperature of the
system was raised to 80.degree.C under stirring. The system was
maintained at this temperature for 30 minutes to cause
polymerization between the toluylenediisocyanate and bisphenol A on
the surface of the oil droplets to form a capsule wall, whereby
encapsulation was accomplished. The capsule solution thus obtained
was coated on a paper by way of roll coating, then dried. The upper
paper obtained in this way did not have the unpleasant smell like
that of the conventional pressure sensitive recording paper
obtained by the analogous treatment using chlorinated diphenyl.
When this upper paper was superposed on a clay paper and writing
was conducted, there was developed a blackish green image on a clay
paper. The density of this color developed image was remarkably
high compared with that of the conventional pressure sensitive
recording paper wherein chlorinated diphenyl was used. Furthermore,
even when this upper paper was exposed to sun light for a long
time, the lowering in the color developing ability and colored fog
were not observed.
EXAMPLE 6
Example 1 was duplicated using 2-methyl-5-isopropyldiphenylmethane
(having a boiling point of 307.degree. - 310.degree.C and specific
gravity of 0.9916 at 20.degree.C) instead of
2,4-dimethyldiphenylmethane, and using 3-methyl-2,2'-spirobi(benzo[
f]chromene) instead of crystal violet lactone. The result thereof
was the same as in Example 1.
EXAMPLE 7
Example 1 was duplicated, except that 1,1-diphenyl-1-heptylmethane
(having a boiling point of 143.degree.-145.degree.C/0.1 mmHg, a
melting point of -5 to -4.degree.C and a specific gravity of 0.9444
at 20.degree.C) ##SPC8##
was used instead of 2,4-dimethyldiphenylmethane. The result thereof
was the same as in Example 1.
EXAMPLE 8
Example 1 was duplicated, except that 1,2-bis-tolyl-ethane (having
a boiling point of 290.degree.-340.degree.C and a specific gravity
of 0.968 (25.degree.C), viscosity 3.2 cp (50.degree.C) was used
instead of 2,4-dimethyldiphenylmethane. ##SPC9##
The result thereof was the same as in Example 1.
EXAMPLE 9
Example 1 was duplicated, except that
dimethyl-t-butyldiphenylmethane (mixture of several kinds of
isomers, having a boiling point of 132.degree.-148.degree.C/0.1
mmHg) was used instead of 2,4-dimethyldiphenylmethane, and the same
result as in Example 1 was obtained.
Although the present invention has been adequately set forth in the
foregoing specification and Examples included therein, it is
readily apparent that various changes and modifications can be made
without departing from the spirit and scope thereof.
* * * * *