Note: Descriptions are shown in the official language in which they were submitted.
` llS3888
The present invention relates to recording material, particularly
impression sheets to be printed or written upon, which are coated with a
chromogenous (chromophoric~ color component which under pressure produces a
color reaction in conjunction with a second reagent, which contains a color
developer. The present invention also relates to a method of producing a
coating mass for application to the recording material.
With known recording sheets of this type (German Auslegeschrift
- 22 28 430), a carrier sheet is coated with a basic reacting chromogenous color
component and/or with an acid reacting phenolic material. When this material
engages with the chromogenous color component in a common dissolving medium,
the material reacts to form color, whereby the carrier sheet additionally has
a metal salt soluble in a dissolving medium.
The color is created with this known recording material as a conse-
quence thereof that a reaction occurs between an oil soluble phenolformal-
dehyde resin and a basic reacting, colorless chromogenous color component
when both reagents are dissolved in a common dissolving medium. Both reagents
can be located either on the same carrier sheet or on separate sheets which
together form the recording material, for example a set of forms. The common
dissolving medium for the reagents is enclosed or encapsulated by polymer
material in microcapsules capable of being ruptured or broken by pressure
during writing or printing thereon; the dissolving medium is isolated from one
or both reagents when both reagents are located on a single carrier sheet.
With a known set of forms, the encapsulated dissolving medium is
located upon one of the two sheets of the set of forms, and in particular,
either on a sheet of its own, or together with one of both reagents, whereby
these can already be dissolved in the dissolving means or can be separate
therefrom.
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With these known recordin~ sheets, it is disadvantageous that the
copy or duplicate quality, ~he rapidity of the copy development, as well as
the color strength and aging durability of the copy cannot be considered fully
satisfactory. Frequently an unpleasant smell from the paper occurs due to
the dissolving medium.
As a consequence of the encapsulation of the chromogenous color
component or the other reaction partner, the known recording materials have
further considerable disadvantages. For example, it is practically impossible
with the production to provide the walls of the capsules with identical wall
strength or thickness, and to distribute the capsules uniformly upon the paper
web. In practice, as a consequence of the clamping or balling together of
individual capsules, there results a so-called clustering forma~ion (Trauben),
which leads to production and quality problems. Furthermore, it is disadvan-
tageous that the capsules can rupture prematurely in an undesired manner,
whereby premature, undesired bluing or discoloration occurs.
Finally, the production of these known coating masses is relatively
expensive and requires special measures relative to quality control.
From ~erman patent 22 19 527 it is already known to utilize a solid,
dry, chromogenous color component which is adsorbed upon the surface of the
paper coating pigments. With this known method, the chromogenous color com-
ponents must be dissolved in a suitable dissolving medium, and must subsequent-
ly be mixed with the paper coating pigments. After this mixing, the dissolving
means is expelled or driven off again by heat. This method has the drawback
that for the fine, uniform distribution of the chromogenous color components,
large quantities of organic dissolving medium are needed, which represents a
great environmental burden. A further drawback consists in that with a
possible recovery of the dissolving means, high investment costs as well as
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continuous personnel and operating costs are necessary. Finally, an
additional cost-intensive working step is unavoidable. Yet another
drawback is that for optimum copy quality, increased quantities of
chromogenous color components are necessary, as a result of the
strong adsorption of the chromogenous color components on the paper
coating pigments.
The object of the present invention, in comparison, is to
provide a recording material, especially a recording or writing
sheet, which, while a~oiding the aforementioned drawbacks, makes
possible an extremely fine and uniform color component distribution
with the least possible portion of chromogenous color components,
and assures an optimum good copy quality, high speed of the copy
development with extremely fine sharpness, as well as a sufficient
color strength of the copy.
With this object in mind, the present inventive recording
material of the initially mentioned types is characterized primarily
in that the color component is provided finely distributed upon the
recording sheet in the form of micro-coagulated, flaky particles,
along with a binder. In this connection, the inventively embodied
color component is provided in the receiving layer of the recording
m,~terial.
Thus, the present invention involves a dissolving-medium-
free recording sheet in which the chromogenous color component is
present in a fine, micro-coagulated, flaky form.
With such a recording material, a wandering of the chromo-
genous color component, which can lead to premature bluing or
discoloration at the boundary layers between the individual reaction
partners, is avoided. Since the recording material is free of
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dissolving medium, neither any environmental burden nor any
undesirable smell results from a dissolving means. The material
is further distinguished by high light stability and aging
stability. Additionally, the recording sheets and the actual coat-
ing material are inexpensive to produce because of the low raw
material cost.
The present invention further concerns a method of produc-
ing a coating mass, containing a chromogenous color component, for
application upon a recording material, particularly a writing sheet
of the initially mentioned type; when pressure is applied, the coat-
ing mass reacts with a layer containing the color developer to pro-
duce color.
Thus, in another aspect, the invention provides a method
of producing a coating mass containing a chromogenous color
component, for application together with a binding agent to a record-
ing material, said method comprising the steps of dissolving, or
melting chromogenous color component in an acidic substance, and
adding water and alkali to liberate said color component in the
form of flaky, micro-coagulated particles.
In particular, the invention provides a method of producing
a coating mass containing a chromogenous color component, for
application upon recording material, said method comprising the
steps of converti~g chromogenous color component into a dispersion-
like form by dissolving or melting in saponifiable, acidic chemicals,
subsequently emulsifying in water and adding alkali to effect
saponification of said saponifiable chemicals, thereby liberating
said color component in the form of flaky, micro-coagulated particles.
Alternatively, there is provided a method of producing a
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coating mass containing a chromogenous color component, for applicat-
ion upon recording material, said method comprising the steps of
converting chromogenous color component into a water soluble form
by dissolving in an aqueous acidic substance, adding alkali, to
neutralize resulting acid, in such a way that said color component
precipitates in the form of flaky, micro-coagulated particles, and
adding binder.
The inventive method of producing the coating mass can also
be undertaken in such a manner that the chromogenous color component
is converted into a flaky, micro-coagulated form by dissolving in an
organic or inorganic acid and neutralization thereof by leaching.
According to a further embodiment of the teaching of the
present invention, the micro-coagulated color component can be
bound or fixed on the paper surface with binding means, for example
a synthetic material dispersion, aqueous resin solutions, a micro-
wax dispersion, or natural binding means.
The inventively embodied micro-coagulated color component
can be embedded in a wax-like receiving layer. The color component
can furthermore be applied, in combination with organic and inorganic
pigments, upon the surface of the reeording material, for example
upon the paper surfaee. In this eonnection, aeeording to a further
embodiment of the method, for dissolving or melting the color
eomponent, fatty aeids, (sebaeie acids), preferably stearie aeids,
can be used. However, acid amides or fatty acid amides are also
suitable for dissolving or melting the color components.
The ehromogenous color component is deeomposed to very fine,
flaky partieles by a miero-coagulation so that even with small
quantities of chromogenous color eomponents, very high eoloring
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power can be obtained.
Compared with the previously known method, with which thechromogenous color component is applied by dissolving agent to paper
coating pigments, there results with the inventive utilization of
micro-coagulated chromogenous color components, that the use of
chromogenous material, with the same color intensity, can be
considerably reduced, namely as much as 40~. This is attributed to
the fact that the chromogenous color component is provided exclusive-
ly in its active form on the paper surface, and not partially
adsorbed by the coating pigments, as with the known solutions. With
the inventive method of producing the coating mass, the color
component is dissolved or melted in cold, heated, or even hot
saponifiable chemicals, for instance an organic or inorganic acid,
such as a stearic or maleic acid. Depending upon the solubility of
the color component, a temperature of 30C to 140C is utilized.
With this procedure, attention must be paid to accomplishing a
complete dissolving or melting. It was discovered that stearic
acid is particularly suitable for carrying out the method. With
color components which are insoluble or difficult to dissolve, or
when the dissolving agent has poor dissolving power for the color
component, it is expedient to undertake heating as far as into the
range of the melting temperature of the color component.
The color components dissolved or melted in the saponi-
fiable chemicals, i.e. the dissolving agent, are then added into
water while undergoing
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vigorous stirring; this water can be warmed or heated. According to the type
of saponifia~le chemicals an emulsion results in which the dissolved color
component forms a mixing component existing in already fine distribution.
If the color components and dissolving agents are soluble in cold
water, for instance certain acid amides, then the stirring can occur at normal
temperatures. In this way, a dispersion results in which the color component
already exists in fine distribution.
If, however, the dissolving agent, such as stearic acid, is insoluble
or soluble only with difficulty at normal temperature, then it is advisable
to heat the water to the melting range of the dissolving agent in order to be
able to emulsify the latter in a liquid phase. Higher acid amides, such as
fatty acid amides, palmitic acids, and the like, which are insoluble or soluble
only with difficulty in water, must be emulsified until they exist in a suit-
able dispersion.
Thereafter, by adding alkalies, the saponifiable chemicals are con-
verted into the corresponding soap, in which connection they are converted
into a colloid-soluble form. As a consequence of this chemical saponification
reaction, the water insoluble color component is released slowly by flaking-
out with increasing saponification. In view of this, the particle size and
also the particle form can be controlled in that the liquor or lye is, for
example, added slowly, for instance dropwise, to attain large flakes. With
quicker addition, smaller flakes of the color component can be obtained.
During slow saponification, a fine color distribution occurs, whereas with a
quick saponification, a coarser color component distribution occurs. The
resulting soap additionally has a strong capillary or boundary surface-active
effect, which brings about a further improvement of the color component dis-
persal.
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After termination of the saponification reaction, the
appropriate pigments, such as calcium carbonate, titanium dioxide,
as well as calcium stearate, or other similar pigments, can be added.
The mixture is cooled off for example to 30C; thereafter, the bind-
ing agents, such as starch, polyvinyl alcohol, synthetic material
dispersions, or also micro-wax dispersions can be added. There is
then obtained a finished liquid coating mass which can be applied
to a recording sheet without further treatment.
With a recording sheet, for example a set of forms, the
inventively produced coating mass are applied as a receiving layer.
It should be noted that, if during the pressure application only
the wax of the wax layer with the color developer is pressed into
the adjoining layer containing the color component, so that no
delivery or transfer of color component particles to the other
layer occurs, then a receiving layer exists.
When the inventive coating or layer mass is applied as a
receiving layer, then a transmitting layer contains the counter
reaction mass, i.e. the developer material, so that by pressure
the transmitting layer is transferred onto the receiving layer,
whereby the color reaction occurs in the interfaces.
With known recording materials, the color component is in
the coating mass in capsules, whereby through pressure, i.e. during
writing or printing, a chemical reaction occurs in that the capsule
ruptures, the dye or coloring material liquid discharges, and a
color-forming chemical reaction occurs with the substance of the
counter-reaction liquid; or the chromogenous color component is
finely distributed by dissolving medium upon paper coating or
layering pigments, whereby through intimate contact with the counter-
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reaction layer, the color formation occurs. In contrast, with the
present invention, the color component is no longer contained or
encapsulated in a capsule, nor adsorbed upon the surface of the
paper coating or layering pigments, but rather lies in finely micro-
coagulated or precipitated flaky form directly on the paper surface,
whereby the bonding on the paper surface can occur with small
quantities of binding agent.
Since the color component is inventively arranged on the
paper surface in micro-coagulated form, the pressure sensitivity
1~ of the coated paper is considerably reduced in comparison to the
known method, with which the color forming means is contained in
capsules.
Also, it is no longer necessary that a special space-
maintaining means be embedded, as required with the known micro-
capsule papers, in order to preclude a premature, unintentional
rupturing of the color capsules, for example during rolling-up of
the paper.
A further possibility of finely distributing chromogenous
color component in an aqueous coating mass in the inventive manner,
comprises converting the chromogenous color component into the water
soluble form by a chemical reaction, for example by adding organic
acids, as a result of which certain chromogenous color components
can be dissolved in the water. Also under these circumstances,
by adding alkalies, the acids can be neutralized again, whereby the
color component precipitates in a fine and flaky form. An aqueous
paste or pulp results, in which the chromogenous color component
exists in the finest distribution and, after the addition of binders,
such as starch or synthetic material dispersion, needs only to be
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spread on the paper.
Example
Color preparation
720 g water
60 g starch
8 g polyacrylic salt
16 g polyvinyl alcohol
30 g titanium dioxide
The individual components are dissolved or suspended during
stirring. The starch is turned into paste by heating the mixture
to 95C.
Color component preparation
80 g stearic acid (saponification number 200)
15 g crystal violet-lactone (CVL)
5 g spiro-dibenzopyran (xanthene)
5 g diazo-rhodamine-lactone
The color components are dissolved at a temperature of
120C while stirring.
While stirring very vigorously, the color component mixture
is slowly added to the color mixture. The shear forces must be so
high that an emulsion-like distribution of the color component
mixture results.
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Subsequently, 5 g potassium hydroxide are dissolved in 20 g water
and are added dropwise into the entire mixture.
The mixture is thoroughly mixed at a temperature of 95C while stir-
ring vigorously for 20 minutes.
After successful partial saponification, the mixture is cooled to
30C, and the further chemicals are added in the following sequence:
6no g calcium carbonate
120 g calcium stearate dispersion
250 g acrylic styrene copolymer dispersion
Papers are coated on one side with 2 _ 4 g/m2 of the coating mass.
Example 2
parts dry parts wet
calcium carbonate 250 250
maleic acid 24 24
triarylmethane coloring material 12 12
titanium dioxide 60 60
polyvinyl-vinylchloride copolymer 200 400
water 254
24 parts of maleic acid are dissolved in 254 parts of water. The
chromogenous color component is slowly stirred into this solution and immedi-
ately dissolves. After complete dissolving, the calcium carbonate is slowly
stirred in, triggering neutralization. The termination of the neutralization
is indicated by the decolorization of the chromogenous color component. The
titanium dioxide is thereafter added as pigment while stirring, and the poly-
vinylacetate-vinylchloride dispersion is added.
The present invention is, of course, in no way restricted to the
specific disclosure of the specification and examples, but also encompasses
any modifications within the scope of the appended claims.
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