US3692556A - Process for producing pressure-sensitive transfer sheets - Google Patents

Process for producing pressure-sensitive transfer sheets Download PDF

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US3692556A
US3692556A US3692556DA US3692556A US 3692556 A US3692556 A US 3692556A US 3692556D A US3692556D A US 3692556DA US 3692556 A US3692556 A US 3692556A
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layer
colloidal
solution
pigments
water
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Giorgi Cecconi
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
    • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
    • B41M5/10—Duplicating or marking methods; Sheet materials for use therein by using carbon paper or the like
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/31504—Composite [nonstructural laminate]
    • Y10T428/31725—Of polyamide
    • Y10T428/31765—Inorganic-containing or next to inorganic-containing
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/31504—Composite [nonstructural laminate]
    • Y10T428/31725—Of polyamide
    • Y10T428/31768—Natural source-type polyamide [e.g., casein, gelatin, etc.]
    • Y10T428/31772—Next to cellulosic
    • Y10T428/31775—Paper

Definitions

  • a process for producing a pressure-sensitive transfer sheet having an essentially coherent but particulate transfer color-yielding layer adherent to one face of a sheet support comprising the steps of providing a fine colloidal suspension in Water of pigments and fillers, of providing a colloidal solution in water of a film-forming macromolecular substance capable of irreversibly precipitating upon dehydration of the solution, of mixing said suspension and solution, of forming a layer of the resulting mixture on said face, of causing progressive elimination of the water from said layer to promote formation on said face of an essentially dry film wherein said pigments and fillers are embedded into a precipitated macromolecular pellicular structure.
  • This invention relates to a process for producing pressure sensitive transfer paper sheets provided with a coloryielding layer which can transfer script characters or marks, impressed either manually or typewritten on the front face of the paper itself, on the front surface, provided with suitable receiving layer of which an immediately underlying sheet is provided.
  • Such transfer papers are well known in the art, and their popularization and utilization is more and more expanding. They are designed to provide a plurality of copies without the use of any intermediate transfer or carbon paper sheets between the superposed sheets, the uppermost one of which is designed to constitute the original one, and the underlying the related copies.
  • the advantages consequent upon the use of such transfer papers known in trade as self-copying papers are many and refiect both economical service aspects and technical aspects as to neatness in the execution of the copies, possibility of obtaining a very high number of copies, elimination of the operations and inconveniences incidental to the use of the intercalated carbon paper sheets, and others.
  • the notoriety of the said self-copying papers and their advantages makes any detailed description thereof superfluous.
  • plasticizers adapted to ace as coagulating means for the polymer, so as to minimize the mechanical strength of the film and to lead to the formation of a substantially heterogeneous Patented Sept. 19, 1972 layer.
  • plasticizers consisting generally of oily substances, lead to softening of the layer, which is consequently more subject to soiling during the manipulation of the paper and contamination of the surfaces with which it comes in contact.
  • plasticizer while penetrating the fibers of the paper support, impair the rigidity thereof and makes it undesirably flabby.
  • organic solvents further results in several inconveniences. For example, they are of difiicult and also dangerous to handle and use on account of their combustibility, of the production of dangerous gaseous products, and others. Furthermore, such solvents, being partly retained in the polymer film even after apparent drying, and evaporating most slowly in subsequent times, lead to sweating and migration phenomena, particularly if assisted by different temperature and ambient relative conditions. Such phenomena lead among other things to the production of trimmings and blurring of the printing inks of typing ribbbons and ball point pens, due to partial solution of relative dyes.
  • the process of this invention advantageously applies to the formation of layers on support means consisting of paper sheet or other sheet material such as plastic sheet.
  • the process according to this invention advantageously permits to carry out the formation of the layers in the final steps of the manufacture of the papers themselves by particularly adopting adaptations and variations of known technical means, such for example as in the manufacture of the so-called patinated papers.”
  • the process is characterized by the formation of the transcribing layer with the use of a colloidal mass in aqueous vehicle, including hydrosoluble pigments and film-forming agents capable of irreversible precipitation in said vehicle during the progressive elimination thereof, so as to obtain an heterogeneous but essentially coherent film in which the pigments are embedded and evenly distributed, and in which the discontinuity is due to the presence of the particles of the precipitate.
  • such colloidal mass also includes wax-like substances in aqueous emulsion, capable of particularly imparting the layer its most desirable surface properties.
  • Such layer includes, according to prior art, dark pigments, adapted to provide the necessary coloring and contrast in the mark or copy transferred onto the underlying receiving layer, fillers and white pigments or clear pigments.
  • the coating of paper or sheet may include two superposed layers, the outer layer of which not incorporating dark pigments and having the scope of masking and protecting the colored pigmented layer, at least one and preferably both said covering layers being obtained with the use of said process as above defined.
  • said colloidal mass in vehicle of aqueous nature is obtained by the association and intimate mixing in a suitable mixer of different previously and separately arranged components, i.e.:
  • the stability of the suspension may be assured by emulsifying means and dispersing agents (peptizing agents).
  • Such suspension is prepared by active subdivision carried out mechanically of the pigments through grinding and by the use of turbo-dispersing agitators.
  • the pigment choice it is advantageous to take into account the Wettability and dispersibility of the same in aqueous vehicle, which characteristics are imparted by the fineness (on the order of 1-10 microns) and by the diameter of the aggregates identifiable in the dispersion.
  • titanium oxides there are preferred the post-treated types based on SiO and A1 for increasing their stability to the light, as well as improving their wettability and promoting the formation of finer and more uniform dispersions with the least mechanical work.
  • filler one may advantageously use talc, magnesium silicate, barium sulphate, zinc sulphate, mica, kaolin, bentonite, clays, precipitated alumina, and silica, besides titanium oxide, such fillers or at least a part thereof having obviously the function of acting as masking or covering clear pigment.
  • the most part of these compounds has a bidimensional structure, and as such they foliate, forming lamellar particles.
  • the bidimensional planes are sealed by water molecules and OH ions, and hence their surface has a strong atfinity with these both components. In such case, there is a more or less acid reaction as a consequence of the increase in the concentration of H+ ions within the solution, because of the absorption of OH- ions on the particle surface.
  • the dark pigments designed to ensure the visibility and the contrast effect in the copies, are preferably constituted of carbon blacks, that is of well known amorphous absorbing compounds formed of mixtures consisting of carbon and hydrocarbons of different nature, adapted to give the suspension and hence the transcribing layer produced with the same in the most suitable concentration the required dark tonality.
  • Such carbon blacks are preferably selected from those obtained according to the Channel method due to both reduced particle dimensions (9-29 microns) and their low pH, which makes them more easily emulsifiable in water.
  • Such dark pigments are commercially available under different trade names, such as Carbolac, Monarch and Mogul (Cabot Corporation), Regent and Printex (Degussa) and Spectra (Columbian Carbon Company).
  • the dispersion and the stability of the colloidal suspension is preferably ensured by suitable emulsifying and tension active agents, such as polyoxyethylene ether of nonyl phenol, polyoxyethylene sorbitan monoleate and monolaurate, sorbitan monoleate and polymethylene lauryl alcohol.
  • suitable emulsifying and tension active agents such as polyoxyethylene ether of nonyl phenol, polyoxyethylene sorbitan monoleate and monolaurate, sorbitan monoleate and polymethylene lauryl alcohol.
  • suitable emulsifying and tension active agents such as polyoxyethylene ether of nonyl phenol, polyoxyethylene sorbitan monoleate and monolaurate, sorbitan monoleate and polymethylene lauryl alcohol.
  • a macromolecular colloidal solution designed for the formation of the film and binding vehicle.
  • colloidal solution prepared in a suitable known equipment, comprising preferably heating and slow agitating means, is constituted of a aqueous solution of colloids which should have the following characteristics:
  • ion generating groups are attached to any fundamental molecule, forming macroanions (polyanions and polycations) which determine the presence of surface charges, thus giving way to a double electric layer.
  • the colloidal substances utilizable may be selected from the natural products (animal proteins, bone glue, fish glue, lactic casein, ovalbumin or others), from the algae extracts (sodium and potassium alginates) and rice starches, wheats, potato feculae and maize.
  • Such products should be degraded, namely reduced to a short molecular chain, and treated so as to increase their solubility e.g. chlorodized, hydrolyzed, oxidized, esterified or sulphurized. Products of this kind are commercially available, for example under the trade names Farinex, Calfarex and Milgum. The white or yellow dextrine and the arabic gum may be used.
  • Synthetic products may also be made use of such as formaldehyde urea and formaldehyde phenol, which products have a particular aflinity with hydroxyls of the cellulose of the paper support, and which by binding therewith increase the resistance to humidity.
  • One may finally utilize some cellulose derivatives, such as methylcellulose, carboxy-methyl-cellulose, monoacetyl-cellulose and xanthogenate of cellulose.
  • the initial stability of the macromolecular colloidal solution as well as the formation of the same and in the layer being dried, of precipitates adapted to impart to the binding vehicle of the layer or coating the desired microscopic homogeneity, which is advantageous to ensure the maximum sensitivity and selectivity in the transfer and formation of the copies.
  • a few considerations are therefore added to better illustrate the conditions under which the desired phenomena are taking place and to comment on the means cooperating to the development thereof.
  • the stability of the colloidal solution is influenced by different factors: primarily by the probability of the shocks between the molecules, due to the Brownian motion and therefore by the temperature and the viscosity of the medium. Consequently, by suitable heating, it is possible to promote and/or contribute to the precipitation of the colloid into very fine grains and separation of the solid phases, with the increase of the kinetic energy of the molecules, because the increase of the molecular motion, particularly combined with the increase of the colloid concentration and/or dehydrating agents, leads to an increase in the number of shocks between the particles and the weakening of the aqueous mantle due to the hydrophilic nature of the macromolecules.
  • Such stability is further influenced by electrolytes capable of developing a fiocculating action, inasmuch as they lower the electrokinetic potential of the double charge layer.
  • dehydrating means and electrolytes particularly the latter in the necessary measure to reach a value near the critical potential, but without exceeding at least in sensible measure the isoelectric point, so as to lead the colloids to the minimum solubility condition and maximum sensitivity to the precipitating agents, occurring upon the production of fine precipitation phenomena, without however undesirable coagulation or amassment phenomena of the particles, and therefore to obtain the formation of the desired discontinuous layer of very thin grain.
  • Heating action in drying phase so as to increase the kinetic energy of the molecule and therefore the number and the intensity of the molecular shocks
  • dehydrating means one may use ethyl alcohol, ace tone, glacial acetic acid, trichloroacetic acid, sulphosalicylic acid, and others.
  • electrolytes one may use the ammonium sulphate, sodium sulphate, magnesium sulphate, as well as the chlorides of the same metals, and the ferric compounds, the electrolytes having to be selected on the basis of their ac tivity, and by taking into account of the pH corresponding to the isoelectric point of the utilized soluble colloids.
  • a wax-based aqueous emulsion has the purpose of improving the chemical-physical character istics of the layer, particularly imparting the following properties to the transcribing layer:
  • wax emulsions consist of aqueous dispersions of microscopic wax particles, maintained in suspension by emulsifying agents.
  • Such emulsions for the practical purposes of the accomplishment of the process, behave like solutions. As a matter of fact, they may be diluted with H O, applied on dry or wet material, and particularly incorporated in the wet process manufacture. The water, being subsequently eliminated from the treated material, leaves a very thin Wax layer, possessing also desired properties.
  • the emulsions may be obtained by suitable emulsifying equipment, including heating and quick agitating means, with paraflin, petroleum and micro-crystalline waxes and however preferably with non-ionic matters for obtaining a better stability to the different acidity and alkalinity conditions.
  • suitable waxes are commercially available, such as Mobilcer of the types A, P and Q (Mobilco) Alvax (Du Pont) and the Hoechst Waxes of the types E, S, L, LP and KPS.
  • wax material polyethylene suspended in soaps may be used, such as the oleic acid, palmitic acid and stearic acid, in combination with amines.
  • the colloidal mass may further comprise secondary fiixing and/ or cooperating agents for the purposes of the resistance to water, such as the formaldehyde, the boric acid and others; also softem'ng agents may be added, such as the glycerine and the solid polyglycols with high molecular weight.
  • secondary fiixing and/ or cooperating agents for the purposes of the resistance to water, such as the formaldehyde, the boric acid and others; also softem'ng agents may be added, such as the glycerine and the solid polyglycols with high molecular weight.
  • the properly pigmented black layer designed to provide visible and contrasting copies, may be protected and masked by a white or clear covering layer, showing similar characteristics to those of the dark layer in order to assure compatibility for the purpose of the selective particle transfer.
  • a white or clear covering layer should be distinct from the underlying black layer, while still having the capacity of fixing thereto, and it is necessary for it not to appreciably alter the intensity of the reproduction and the tonality of the copy writing.
  • FIG. 1 represents schematically and in part in flow sheet form the complete execution of the process
  • FIGS. 2 anud 3 show, still schematically, two embodiments of the means for and the step of application and formation of the layers.
  • A, B and C designate schematically the means for the preventive independent preparation of the components referred to above, namely of the fine colloidal suspension of the pigments and charge matters in Water, and respectively of the macromolecular colloidal solution, in water, and of the emulsion still in water of the cerous substances.
  • Such essential components are caused to flow into a mixing environment M, in which are, in turn, added the dehydrating agents D and the electrolytes E, in addition to the eventual cooperating, fixing and/or softening means.
  • the colloidal mass provided in a mixing environment M is applied in thin layer or film form to the laminar sup port L for example by means of a smearing roller S, provided with dosing blade, and the applied layer, adjusted as to quantity and thickness for example by a scraper Ra, is then dried for example through passage of the laminar support around heated cylinders or rollers R.
  • the dosed application of the colloidal material Mc may be carried out by other systems, for example by sprayers Sp, and the layer may be adjusted and uniformized between calendering cylinders R and R", which may also act as heaters, all as exemplified in FIG. 2.
  • the laminar material L of support receives the application, by means of an inking roller Ri supplied by an inking system I consisting of cylinders, the layer being dried through the passage around a heated roller R and/or in presence of a radiator Rt provided for example with electrical resistors.
  • an opposed inking roller Ri' supplied by a proper inking system I for the application of a material M designed for the formation of the opposed receiving layer.
  • Such example are subdivided into groups regarding the composition of the above-discussed three essential components in aqueous vehicle, and then examples of final compositions are given by dilferent combinations and associations of said components, together with eventual cooperating substances.
  • Such examples are grouped in form of tables in order to ease a comparative examination.
  • All dark pigments above indicated by their trade names, can consist of low pH carbon blacks produced by Channel process and of dimensions comprised between 9 and 29 microns.
  • the waxes referring to Examples C -C are available on trade as emulsions with the above mentioned solid contents. By using Montana waxes it is instead necessary, generally, to provide for the preparation of the relative emulsion.
  • compositions of the colloidal mass will be indicated in parts in weight by making simple reference to the examples given in the preceding Tables I, II and III and with the addition of dehydrating means (indicated with D), of the electrolytes (indicated with E) and various cooperating means (indicated with C) having an emollient, hardener, fixer and others function.
  • Examples I-V represent colloidal masses and mixtures adapted for the formation of a dark transfer layer, designed for transfer with formation of neat and sharp copies, whilst the Examples VI-VIII give compositions adapted for the formation of white or clear coating, protecting and surface completing overlayers for the transfer dark layer.
  • Example IV Total To Example IV Parts by wt. Colloidal suspension of Example A; 5 8 Colloidal solution of Example B 20 D acetone 10 E potasium nitrate 2 C polyglycol, M.W. 4000 10 Total TOT) It may be observed that in the above Example IV the wax emulsion, is not included in that the composition character does not necessarily require the use.
  • Example V Parts by wt. Colloidal suspension of Example A 69 Colloidal solution of Example B 10 Wax emulsion of Example C 11 D: trichloroacetic acid 8 E: amomnium sulphate 2 Total 3%
  • D pentadigalloil-glucose 1
  • C polyglycol, M.W. 4000 1 Total F10
  • Example VIII Parts by wt. Colloidal suspension of Example A 45 Colloidal solution of Example B 8 Wax emulsion of Example C 30 D: ethyl alcohol 15 C: formaldehyde 2 Total at As it may be observed in this Example VIII, no electrolytes are being used for contributing to the formation of the precipitate of the colloidal solution, since, in view of the composition adopted, the dehydrating will act as an agent for the demolition of the solvated mantle of the macromolecules in solution.
  • a process for preparing the transfer layer of selfcopyin-g paper which comprises the steps of (l) applying to a support a colloidal material in an aqueous vehicle, said colloidal material consisting of a mixture of (a) a colloidal aqueous suspension of pigments and filler materials, (b) a colloidal aqueous solution of water-soluble film-forming macromolecular compounds capable of irreversible precipitation in said vehicle, (c) an aqueous waxy emulsion, (d) a dehydrating agent and (e) an electrolyte, (2) adjusting the pH to the range at which said irreversible precipitation occurs and (3) progressively eliminating said vehicle by heat so as to obtain a heterogeneous but coherent film in which the pigments are distributed.
  • colloidal aqueous solution is formed of colloids containing hydrophilic groups N11 COOH, CO or OH, which colloids are substantially insoluble in organic solvents.
  • colloidal aqueous solution is formed with colloids having a structure which is substantially isodimensional.
  • a selfcopying paper having a transfer layer produced by the process of claim 1.

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US3692556D 1967-05-27 1968-05-24 Process for producing pressure-sensitive transfer sheets Expired - Lifetime US3692556A (en)

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US (1) US3692556A (enrdf_load_stackoverflow)
AT (1) AT302375B (enrdf_load_stackoverflow)
DE (1) DE1761495C3 (enrdf_load_stackoverflow)
FR (1) FR1578073A (enrdf_load_stackoverflow)
GB (1) GB1235695A (enrdf_load_stackoverflow)
NL (1) NL6807324A (enrdf_load_stackoverflow)
SE (1) SE360041B (enrdf_load_stackoverflow)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3925088A (en) * 1973-07-20 1975-12-09 Us Navy Thermally sensitive ink
US4957773A (en) * 1989-02-13 1990-09-18 Syracuse University Deposition of boron-containing films from decaborane
WO1998052765A1 (en) * 1997-05-23 1998-11-26 Nashua Corporation Glossy ink jet paper

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3118980A1 (de) * 1981-05-09 1982-11-25 Pelikan Ag, 3000 Hannover Multicarbon-material zur schrifterzeugung

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3925088A (en) * 1973-07-20 1975-12-09 Us Navy Thermally sensitive ink
US4957773A (en) * 1989-02-13 1990-09-18 Syracuse University Deposition of boron-containing films from decaborane
WO1998052765A1 (en) * 1997-05-23 1998-11-26 Nashua Corporation Glossy ink jet paper

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Publication number Publication date
NL6807324A (enrdf_load_stackoverflow) 1968-11-28
GB1235695A (en) 1971-06-16
DE1761495C3 (de) 1978-04-13
SE360041B (enrdf_load_stackoverflow) 1973-09-17
AT302375B (de) 1972-09-15
DE1761495A1 (de) 1971-07-01
FR1578073A (enrdf_load_stackoverflow) 1969-08-14
DE1761495B2 (de) 1977-08-18

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