EP0194518A1 - Reaction recording system - Google Patents

Abstract

The subject of the invention is the use of special resins containing phenolic hydroxy groups as colour developers in reaction recording systems, in addition to reaction recording systems which contain these resins as colour developers.

Description

The invention relates to the use of special resins containing phenolic hydroxyl groups as color developers in reaction recording systems and reaction recording systems which contain these resins as color developers.

Reaction recording systems in the sense of the invention are in particular papers on which visual representations can be produced by imagewise mechanical printing or by imagewise heating.

These include the known carbon copy papers (see M. Gutcho, Capsule Technology and Microencapsulation, Noyes Data Corporation, 1972, pages 242-277; G. Baxter in Microencapsulation, Processes and Applications, edited by JE Vandegaer, Plenum Press New York, London, Pages 127-143).

Reaction carbon papers consist, for example, of two or more sheets of paper laid loosely one on top of the other, the upper one on the rear side being a donor layer and the lower one on the front side contains a slave layer. In other words, a donor layer and a receiver layer are in contact with each other. The donor layer contains, for example, microcapsules, the core material of which is a solution of a dye former in an organic solvent, and the receiver layer contains a color developer, ie a material which converts the dye former to the dye. A copy is created when the microcapsules are destroyed by the pressure of a writing instrument and the dye former reacts with the color developer.

If the dye former is embedded in a meltable wax instead of in microcapsules, a copy occurs when the paper is heated imagewise. It is then a thermoreactive recording system.

Dye formers and color developers can also be applied to the same paper sheet. One then speaks of "self contained paper". On such material, by means of imagewise printing or imagewise heating e.g. a font can be created.

Thermoreactive recording systems are preferably used in electronic computers, remote printers, teleprinters and measuring instruments. Markings can also be created on them using laser beams.

Thermoreactive recording systems can be constructed in such a way that the dye former is dissolved or dispersed in one binder layer and in a second layer the color developer in the same binder is dissolved or dispersed. Dye formers and color developers can also be dispersed in a layer. The binder is softened by heat and comes into contact with the color developer at the places where heat is applied. The color develops.

Typical examples of known color developers are active clay substances, such as attapulgus clay, acid clay, bentonite or montmorillonite; halloysite, zeolite, silicon dioxide, aluminum oxide, aluminum sulfate, aluminum phosphate, zinc chloride, kaolin and other clays or acidic organic compounds such as e.g. ring-substituted phenols, salicylic acid, their metal salts or salicylic acid esters, also acidic polymeric materials, such as phenolic polymers, alkylphenol acetylene resins, maleic acid-rosin resin or partially or completely hydrolyzed polymers from maleic anhydride and styrene, ethylene or vinyl methyl ether or polyacetals.

The color developers can also be used in a mixture with per se unreactive or less reactive pigments or other auxiliaries such as silica gel. Examples of such pigments are: talc, titanium dioxide, zinc oxide, chalk; Clays such as kaolin as well as organic pigments, e.g. Urea-formaldehyde or melamine-formaldehyde condensation products.

Activated clays are sensitive to moisture, ie developed color can be removed with water or forms very weakly in a damp atmosphere. The development of black fluoran dyes, such as e.g. 3-Dielhylamino-6-methyl-7-anilinofluoran or 3- (N-Cyclohexyl-N-methylamino) -6-methyl-7-anilinofluoran is not possible. Rather, corresponding organic color formers produce reddish-black or greenish-black images that quickly fade to red-brown.

DT-AS 22 42 250 and BE-PS 784 913 and 802 914 describe metal salts of substituted hydroxyaryl carboxylic acids, e.g. of salicylic acid as a color developer. Mixtures of aromatic carboxylic acids or their salts with polymers are also known from DT-OS 2 348 639. The aromatic carboxylic acids or their salts are often soluble in water, which is why some of the acids diffuse into the inside of the sheet when the aqueous printing paste is applied, resulting in a lower color-forming capacity and thus a lower color density.

Phenols as color developers are e.g. in U.S. Patent 3,244,550, phenolic resins e.g. in U.S. Patent 3,672,935 and finally the special use of bisphenol A resins, e.g. in JA-PS 063 958.

• - Bei der Durchschrift zeigt sich - etwa im Vergleich zu Ton-Entwicklern - eine geringere Intensität bzw. Farbstärke.
• - Die Entwicklungsgeschwindigkeit der Durchschrift ist gering. Zu Beginn bleibt die Durchschrift blaß, bis sich im Laufe der Zeit allmählich die Intensität erhöht.
• - Beschichtete Farbentwickler-Papiere auf zeigen eine ausgeprägte Vergilbungstendenz. Diese wird durch Sonnenlicht, aber auch künstliche Lichtquellen noch verstärkt.
• - Die Herstellung einer wäßrigen Phenolharz-Dispersion zur Beschichtung ist häufig sehr schwierig, weil die Harze wegen ihrer hohen Schmelztemperatur, ihrer hohen Schmelzviskosität und ihrer großen Verklebungsneigung nur sehr schwierig homogen dispergierbar sind.
• - Bei Phenol-Formaldehydharzen besteht die Gefahr einer Ruckspaltung zu Phenol und Formaldehyd. Formaldehyd riecht unangenehm.

Phenols and phenolic resins currently used have the following disadvantages in particular:

• - The copy shows - for example in comparison to clay developers - a lower intensity or color strength.
• - The development speed of the copy is slow. At the beginning, the copy remains pale until the intensity gradually increases over time.
• - Coated color developer papers show a pronounced yellowing tendency. This is intensified by sunlight, but also by artificial light sources.
• - The preparation of an aqueous phenolic resin dispersion for coating is often very difficult because the resins are very difficult to disperse homogeneously because of their high melting temperature, their high melt viscosity and their high tendency to stick.
• - With phenol-formaldehyde resins, there is a risk of splitting back to phenol and formaldehyde. Formaldehyde smells unpleasant.

als Farbentwickler in Reaktionsaufzeichnungssystemen. Es handelt sich dabei um Harze, mit Erweichungspunkten von 30 bis 120°C, bevorzugt 35 bis 80°C.The invention relates to the use of mixtures of at least two of the following compounds pp-bisphenol A (I) op-bisphenol A (II) bisphenol-indane (III) chroman (A) (IV) chroman (B) (V) trisphenol (VI) 9.9-dimethylxanthene (VII)

as a color developer in reaction recording systems. These are resins with softening points of 30 to 120 ° C, preferably 35 to 80 ° C.

zugefügt sein, wobei

• R¹ bis R⁶ Wasserstoff, C₁ bis C₂₄ Alkyl, Chlor, Brom, Phenyl, Hydroxyl, N0₂, CO₂H, O-Alkyl (mit 1 bis 24 C-Atomen), O-CO-Alkyl (mit 1 bis 24 C-Atomen) bedeuten und
• R⁷ und R⁸ Wasserstoff oder C₁ bis C₄ Alkyl.

These mixtures can contain up to 40% by weight, based on the total mixture, of compounds of the formulas (VIII) and / or (IX)

be added, whereby

• R ¹ to R ^{6 are} hydrogen, C ₁ to C ₂₄ alkyl, chlorine, bromine, phenyl, hydroxyl, N0 ₂ , CO ₂ H, O-alkyl (with 1 to 24 C atoms), O-CO-alkyl (with 1 up to 24 carbon atoms) mean and
• R ⁷ and R ^{8 are} hydrogen or C ₁ to C ₄ alkyl.

Mixtures of 15 to 60% by weight of pp-bisphenol A (I), 1 to 25% by weight of op-bisphenol A (II), 1 to 15% by weight of bisphenol-indane (III), 1 to 20% by weight of chromane (IV) + (V), 1 to 20% by weight of trisphendl A (VI), 1 to 20% by weight of 9.9-dimethylxanthene (VII) and 0 to 40% by weight of an aromatic hydroxycarboxylic acid of the formula (VIII) and / or (IX).

The color developers according to the invention are resins with softening points of 3D-120 ° C, preferably of 35-80 ° C. Resins with too low a softening point tend to stick on paper, while those with too high a softening point show poorer color development.

Preferred aromatic hydroxycarboxylic acids of the formula (VIII) or (IX) are those with long-chain alkyl radicals such as 3-nonylsalicylic acid, 5-tert.-octylsalicylic acid, 3-methyl-5-tert.-amylsalicylic acid, 3-methyl-5-tert .-Octylsalicylic acid, 3-cyclohexyl-5-ethylsalicylic acid, 3,5-di- (α, α-dimethylbenzyl) -salicylic acid and semi-volatile salicylic acid derivatives, such as 4,4'-Di-hydroxydiphenylmethane-3,3'-dicarboxylic acid ¢ bis (4-hydroxy-3-carboxy-S-methylphenyl) methane, 2,2-bis (3-carboxy-4-hydroxyphenyl ) propane, 1,1-bis (3-carboxy-4-hydroxyphenyl) cyclohexane.

However, resins which contain low-substituted salicylic acid derivatives, such as e.g. 3-methylsalicylic acid, 5-methylsalicylic acid, 5-tert-butylsalicylic acid, 2,4-dihydroxybenzoic acid or salicylic acid itself.

The papers coated with the color developers according to the invention show a markedly reduced tendency to yellowing, particularly after storage and exposure to light.

Furthermore, because of their favorable melting point / melting behavior, the color developers according to the invention make it easy to prepare aqueous coating color dispersions.

In addition, the resins according to the invention do not offer the possibility of splitting back into phenol and formaldehyde, as is the case with the conventional phenol-formaldehyde resins.

The color development properties of the color developers according to the invention are particularly favorable when they are used as "hybrid systems", i.e. if they are combined with chemically modified aluminum layer silicates based on montmorrillonite.

In addition to the excellent development properties, the color developer resins according to the invention have further advantages, e.g. a significantly lower melt viscosity than other phenolic resins, which significantly facilitates their incorporation into the corresponding carbonless papers.

Because of their good solubility in organic liquids, the color developer mixtures according to the invention can be applied by applying the solution and evaporating the solvent. These are as a solvent, for example, C _l -C ₆ alcohols, C ₂ -C ₄ alkane diols, triols, suitable ethylene glycol monoalkyl ethers, aromatic hydrocarbons, esters and / or ketones. Preferred solvents are methanol, ethanol, n-propanol and isopro panol, n _- butanol, isobutanol, sec-butanol, ethylene glycol monomethyl ether, ethylene glycol, 1,2-propanediol, glycerol, acetone, methyl ethyl ketone, toluene, xylene or mixtures thereof.

Because of their very good solubility, the color developers according to the invention can advantageously be used in the form of concentrates. Storage-stable concentrates can be produced which contain up to 90% by weight, preferably 40 to 60% by weight, based on the concentrate (solution), of resin.

It is particularly preferred to apply the color developers of the invention from aqueous dispersions. This process offers advantages over the former in terms of explosion safety (no solvent vapors).

The color developer mixtures according to the invention can be mixed with binders such as polyvinyl alcohol, SBR latices and pigments, e.g. Combine absorbents such as kaolin, attapulgite, montmorrillonite, bentonite and clays, chemically modified layered aluminum silicates and disperse them in water.

Dispersants which can be used are, for example, polyvinyl acetates, polyvinyl alcohols, hydroxyethyl cellulose, gum arabic, guar gum, locust bean gum or ghatti gum. Dispersions are particularly preferred which, in addition to the color developers according to the invention, contain combinations of different polysaccharides, for example rubber arabic and guar gum or gum arabic and locust bean gum; Here gum arabic apparently acts as a dispersant, while the other polysaccharide as a thickener prevents sedimentation and agglomeration of resin particles.

The color developers according to the invention and the aqueous dispersions described can be used, for example, for the production of carbonless carbonless papers and for the production of thermoreactive recording materials. For this purpose, the solutions or dispersions according to the invention of the color developers according to the invention can be spread onto a paper carrier web. The formulation of such coating materials is known.

The color developers according to the invention can be used in the form of highly concentrated coating slips and the coating slips can be dried more effectively.

Highly concentrated coating compositions containing color developers according to the invention permit the use of various known coating techniques, for example application with a blade coater or by means of gravure rollers. The application techniques mentioned work faster than, for example, coating with an air knife. The application with engraving rollers already represents a modified, aqueous "gravure" process.

Aqueous dispersions can be prepared very easily from the color developer mixtures according to the invention (Example 12b) while phenol-formaldehyde resins stick together (cf. US Pat. No. 3,672,935).

Examples A.) Production of the color developers example 1

• a) Color developer consisting of 54.1% pp-bisphenol A 11% op-bisphenol A 4.5% bisphenol-indan 10.9% chromane (A + B) 6.3% trisphenol A 11% 9.9-dimethylxanthene
  The mixture has a softening point of approx. 40 ° C.
• b) preparation of an aqueous emulsion from the resin of la)
  2.5 g gum arabic and 0.5 g locust bean gum are dissolved in 60 ml of hot water. Then 40 g of melted resin from example la) are added at 80 ° C. and the two liquids are emulsified with an Ultraturrax for 5 minutes at 10,000 rpm. An approximately 40% milky white emulsion is obtained, in which no sedimentation of particles was observed after four weeks.

Example 2

• a) color developer consisting of 43.3% pp-bisphenol A 8.8% op-bisphenol A 3.6% bisphenol-indan 8.7% chromane (A + B) 5.0% trisphenol A 8.8% 9, 9-dimethylxanthene 20.0% 4,4'-dihydroxydiphenyl-3 ', 3'-dicarboxylic acid
• b) Preparation of an aqueous emulsion from the color developer resin of Example 2a
  2.5 g gum arabic and 0.5 g locust bean gum are dissolved in 60 ml of hot water. Then 40 g of melted resin from example 2a) are added at 90 ° C. and the two liquids are emulsified with an Ultraturrax for 5 minutes at 10,000 rpm. An approximately 40% milky white dispersion is obtained, in which no sedimentation of particles was observed after four weeks.
  

The mixtures were made by simply mixing the components at 100 ° C.

Example 12

• a) 100 g des gemäß 2a zusammengesetzten Farbentwicklers werden unter Rühren auf ca. 90°C erwärmt. Unter weiterem Rühren werden 100 g 10 Xige Polyvinylacetat-Lösung, die ebenfalls auf 90°C vorgewärmt wurde, hinzugegeben und mit einem Ultraturrax 5 Minuten bei 10.000 U/min intensiv homogenisiert. Beim Abkühlen ergibt sich so eine milchig-weiße 50 %ige Dispersion.
• b) Zu 400 ml Wasser werden unter Rühren 240 g China Clay, 60 g Ca-Carbonat und 100 g eines chemisch modifizierten Aluminium-Schichtsilikates auf Montmorrillonit-Basis gegeben. Der pH-Wert dieser Dispersion wird mit 40 Xiger Natronlauge auf pH 9 eingestellt. Unter weiterem Rühren werden 200 g der gemäß a) hergestellten Phenolharz-Dispersion hinzugefügt sowie 64 g eines SBR-Latex. Es ergibt sich so eine Farbentwickler-Dispersion mit einem Feststoffgehalt von 50 %, die, gegebenenfalls verdünnt mit Wasser, auf Papier aufgetragen und getrocknet eine CF-Nehmer(Farbentwickler)-Schicht ergibt. In diesem Beispiel wurde auf etw 15 % Feststoffgehalt mit Wasser verdünnt, was einem Beschichtungsgewicht (trocken) von ca. 4-5 g/m² entsprach.

Color developer coating color with a color developer resin according to Example 2a:

• a) 100 g of the color developer composed according to 2a are heated to about 90 ° C. with stirring. With further stirring, 100 g of 10% polyvinyl acetate solution, which was likewise preheated to 90 ° C., are added and homogenized intensively with an Ultraturrax for 5 minutes at 10,000 rpm. This results in a milky white 50% dispersion when cooling.
• b) 240 g of china clay, 60 g of calcium carbonate and 100 g of a chemically modified aluminum layer silicate based on montmorrillonite are added to 400 ml of water with stirring. The pH of this dispersion is adjusted to pH 9 using 40% sodium hydroxide solution. With further stirring, 200 g of the phenolic resin dispersion prepared according to a) and 64 g of an SBR latex are added. The result is a color developer dispersion with a solids content of 50%, which, optionally diluted with water, is applied to paper and dried to give a CF receiver (color developer) layer. In this example, water was diluted to about 15% solids content, which corresponded to a coating weight (dry) of approx. 4-5 g / m ² .

For a comparative assessment of the copy-through intensity, the resins were dissolved in 10% ethanol and this solution was applied to base paper with a roller. After drying, the coating weight was 1-2 g / m ² . The coated sheets of paper were pure white.

Example 13 (comparative example)

10% solution of a mixture of a phenolic resin (Example 1 from US 3,672,935) in ethanol.

Example 14 (comparative example)

Reaction product of 90% of a bisphenol A / formaldehyde resin with 10% 4,4-dihydroxydiphenylmethane-3,3-dicarboxylic acid (= example 3). 10% dissolved in ethanol.

Example 15 (comparative example)

Reaction product of 70% of a bisphenol A / formaldehyde resin with 30% 4,4-dihydroxydiphenylmethane-3,3-dicarboxylic acid (= example 4). 10% dissolved in ethanol.

Example 16 (comparative example)

10% solution of a bisphenol A / formaldehyde resin in ethanol.

Example 17 (comparative example)

10% ethanolic solution of p-tert-butylsalicylic acid.

Example 18 (comparative example)

10% ethanolic solution of p-methylsalicylic acid.

Example 19 (comparative example)

Analogously to the process from Example 12b), a dispersion was prepared with a phenolic resin according to Example 1 of US 3,672,935; at 90 ° C. the resin is strongly bonded. The aqueous dispersion cannot be worked up further.

(B) Writing performance check

To determine the writing performance, a black carbon inking paper (CFB) from Boise Cascade Corp., Portland Oregon, USA, was placed on the coated raw paper (CF) and an area of 4x4 cm so was used with an electric typewriter (Olympia Standard) at constant velocity labeled as closely as possible with the letter "w". The writing now visible on the reaction paper was checked for its writing intensity by determining the loss of reflection compared to unlabelled paper with a reflectance measuring device (Elrephomat, Zeiss).

The following font intensities were measured:

Claims (5)

1. Use of a mixture of resins with a softening point of 30-120 ° C from at least two of the following compounds: pp-bisphenol A, op-bisphenol A, bisphenol-indane, chroman A, chroman B, trisphenol, 9,9-dimethylxanthene , as a color developer in reaction recording systems. 2. Use according to claim 1, wherein up to 40% by weight, based on the total mixture, of compounds of the formulas (VIII) and / or (IX) are added to the resins,

in which R ¹ to R ^{6 are} hydrogen, C ₁ to C ₂₄ alkyl, chlorine, bromine, phenyl, hydroxyl, HO ₂ , C0 ₂ H, 0-A1-alkyl (with 1 to 24 C-atoms), O-CO-alkyl ( with 1 to 24 carbon atoms) means and R ⁷ and R ^{8 are} hydrogen or C ₁ to C ₄ alkyl. 3. Use of a resin mixture with a softening point of 30 to 120 ° C of the following composition: 15-60 wt .-% pp-bisphenol A, 1-25 wt .-% op-bisphenol A, 1-15 wt .-% bisphenol Indan, 1-10 wt% chroman (A), 1-10 wt% chroman (B), 1-20 wt% trisphenol A as a color developer for reaction recording systems. 4. Pressure sensitive carbonless reaction papers containing a color developer according to claim 1. 5. Thermoreactive recording systems containing a color developer according to claim 1.