PL114234B1 - Copying material with own pressure-sensitive layer and method of making the same - Google Patents

Description

The present invention relates to a method of producing a pressure-sensitive in-line copying material and a pressure-sensitive in-house copying material. by the pressure-sensitive copying method, usually known as the transfer method, the lower surface of the top sheet is covered with microcapsules containing a colorless solution of a color former, and the upper surface of the lower sheet is covered with a color developer, for example acid clay or phenolic resin. In most cases, a number of intermediate sheets are also used. The lower surface of each is covered with microcapsules and the upper surface with a color developing substance. Pressure applied to the sheets during handwriting or typewriting causes the microcapsules to break, thereby releasing a color-producing solution and allowing it to come into contact. shadow with the substance developing the color of the next lower sheet, which causes a chemical reaction that develops the color from the substance producing the color. Such a method has the disadvantage that it is necessary to produce at least two, and usually three, types of the aforementioned coated sheets, i.e. top, bottom and intermediate. Celsm to overcome the above-mentioned disadvantage, a system is proposed. copying material with its own layer. In this arrangement, the microcapsules and the color developing substance are applied to the same surface of the sheet, and typing or handwriting on another sheet placed over the sheet thus coated causes the capsules to burst and release a substance that produces a color, which then reacts with a color developing substance on the sheet which produces a color. The disadvantage of the self-layer material is that it has hitherto been necessary to produce the sheets in a two-step coating operation. The first step involves applying a microcapsule mixture to the sheet and the second applying a coating of the color developing material to the sheet produced in the first step. Of course, it would be simpler and therefore cheaper to apply the microcapsules and color developing material simultaneously in one operation. Such proposals are given, for example, in US Pat. US Am. No. 2,730,457. However, there is premature color development if this operation is performed either by mixing the suspension of microcapsules with a dispersed color developer before coating or after coating has been performed. The causes of premature color development are complex and complex. incompletely understandable. It is believed that one reason is that, after manufacture, the suspension of the microcapsules most often contains "some color-forming solution outside the capsules, which reacts violently with the color developer in the system, thus It has been found, however, that premature color development can also occur even if the color-producing solution is not present outside the capsules, for example when it is removed prior to mixing with the color developer, which would be the case on an industrial scale. too expensive. * The cause of the premature development of color in this way is not completely understood, and research indicates that there may be a mutual attraction between the capsules and particles of the color-inducing substance. It is not known exactly how this attraction causes premature growth. early coloring.As mentioned above, it has also been found that even if it is possible to obtain a non-tinted mixture covering the j, it is the paper coated with this mixture that may color either immediately upon drying or during several days after coating. Again, the cause of the premature tearing is not completely understood. It has now been found that in the case of a particulate mineral color developing substance, the symptoms of premature color development described above can in principle be avoided or at least reduced by a suitable chemical treatment of the color developing substance, as well as possibly the microcapsules. The substance used for such treatment will be hereinafter referred to as a protective agent. The subject of the invention is a method of producing a copying material with a pressure-sensitive in-house layer, including the step of coating the material. in sheets, for example paper, a mixture that contains both particulate mineral color-developing material and microcapsules containing a solution of a colorless color-developing material that is reactive with the color-developing material to form a colored product , consisting in fth that the triggering substance particles - the color, and possibly the microcapsules, is treated with a protective agent in an amount sufficient to inhibit premature color development, which factor is compatible with the type of microcapsules and does not substantially reduce the properties of the color developing substance. The protective agent according to the invention is a self-crosslinking polymer, for example a self-crosslinking agent that gives the paper wet strength. As such a polymer, an aminoplast is used, for example a urea-formaldehyde or a melamine-formaldehyde polymer, or an epichlorohydrin polymer, for example an aminoepichlorohydrin or an amide-amino-epichlorohydrin copolymer. An anionic sulfate-containing surfactant, for example a salt of lauryl sulfate, or a sulfonate surfactant, for example a sulfonated derivative of ricic acid, a salt of dodecyl benzene sulfonic acid or a dibutyl ester, can also be used as a protective agent. or dioctyl sulphobuccinic acid. As a protective agent, a fluoride-containing paper for bonding paper may be used, or a non-self-crosslinking agent that gives the paper a wet strength, for example a polyethylene imine resin. copying material with its own pressure-sensitive layer, which is a sheet material covered with both ground mineral color-generating substance and microcapsules, containing a solution of a colorless color-producing substance, reactive with the color-producing substance to form a colored product containing microcapsules and a substance The color developing agent is disposed in a single applied layer, this layer also containing a protective agent in an amount sufficient to inhibit premature color development, which factor is compatible with the type of microcapsule and does not substantially reduce the properties of the color developing material. It has been found that some substances that can be used with certain types of microcapsules elute the contents of other types of microcapsules, therefore it is important to ensure that the protective agent is compatible with the type of microcapsules used. Examples of mutually exclusive combinations of protective agent and microcapsules are provided below. A preferred color-developing mineral particulate material is acid-treated clay, for example as referred to in British Patent Specification No. 759,800 p. 2 pp. 15. -17, and in United Kingdom Patent Nos. 1,147,480, 1,213,835,. 1 232 208, 1 247 909, 1307 319, 1323937, 1379 254, 1381928, 1383 376, 1 417 206 and 1 524 900. The fine mineral color developing substance can be treated with a protective agent by usually mixing a suspension of this substance with » a protective factor. The mixture can then be seasoned with possible mixing. The protective factor can be a self-crosslinking polymer. In this case, it may be desirable to heat the mixture of polymer and color developing material prior to mixing them with the microcapsules. It is preferable to treat the color developing material and possibly the microcapsules prior to mixing them. However, in cases where premature color development does not occur immediately during mixing, it is possible to add the protective agent after mixing, also achieving the desired result. The expression "crosslinking polymer" used in this description includes not only polymers having a large number of repeating members, but also; so-called prepolymers or precondensates, which have only a small number of repeating units * The self-crosslinking polymer may be living or precondensate, such as used in the papermaking industry to provide wet strength to rolls of paper. Resins or precondensates of epichlorohydrin and amino plastics are preferred. Examples of suitable epichlorohydrin are "Nadavin" FP and "Nadavin" FPN, both of which are With polyaminoepichlorohydrin resins, "Nadavin" LT, which is a polyamide / polyaminoepichlorohydrin resin. They are all produced by Bayer U.K. Ltd. "Nadavin" FP is preferred. Examples of suitable aminoplasts are meiamin-formaldehyde resins or precondensates or urea-formaldehyde resins or precondensates. Among aminoplasts, it has been found that melamine substances are most effective in preventing premature color development. Formaldehyde. An example of a suitable melamine-formaldehyde resin is Beetle Resin GC 27 sold by British Industrial Plastics Ltd. This resin, upon delivery, has a reactive resin content of about 100% and a solids content of about 93%. suitable meta-formaldehyde precondensates are Beetle Resin BC 71, BC 309 and BC 336, all also sold by British Industrial Plastics Ltd. These are methylated modified melamine formaldehyde precondensates. BC 71 precondensate contains reactive resin around 80% and solids around Q9! ° / o, BC 309 has a c reactive resin around 9GP / o and solids around 8010 / o. The BC 336 at delivery has a reactive resin content of about 76% and a solids content of about 71%. Other aminoplasts that can be used are L 5084 and "BC 6 urea-formaldehyde precondensates, both also sold by British Industrial Plastics Ltd." At the time of delivery, the first one has a reactive resin content of about 7% and solids about 68%, and the second one has a reactive resin content of about 50 * 70 and solids about 45%. Other self-crosslinking polymers that can be used as agents protective, there are polymers sold by Hercules Powder.Company as Kymene 709 and Kymene 557, and a polymer sold by Diamond Shamrock Corporation as Nopoobond SWS-10. "When the protective agent is a self-crosslinking polymer, the treatment of the color-inducing substance depends significantly depending on the type of polymer, the selection of the appropriate processing conditions is within the limits of the technologist experienced in the field. In the case of a clay-type color developing substance after acid treatment and the above-mentioned BC 27 and BC 71 melamine-formaldehyde substances, a suitable method of treatment is to heat the clay slurry with a 10% resin solution or a densate preconcentrate (based on the weight ratio) dry acid clay) at 90 ° C for about 2 hours. In the case of polyamino-epichlorohydrin resins and a clay-type color developing substance after acid treatment, a suitable treatment method is to mix the clay with a 10% aqueous solution. resin and mechanical agitation for several minutes at pH 7-8. Heating is not too bad. In some cases, treating the capsules with a self-crosslinking polymer may also be advantageous. It is convenient to use the same polymer as that used to treat the color developing substance. '*' Wet strength agents which are not self-crosslinking polymers may also be used as protective agents, for example polyethyleneimine resin, such as that sold by BASF as Bollymin P. Other substances that can be used as protective agents, there are anionic surfactants, especially those which contain sulfate or sulfonate groups. An example of an anionic surfactant containing a sulfate group is a salt of lauryl sulfate, such as sodium lauryl sulfate. Sulfonate surfactants include dodecylbenzenesulfonic acid salts, sulfosuccinic acid dibutyl ester (for example, sold by BDH Chemicals Ltd. as Manoxol IB), sulfosuccinic acid dioctyl ester (for example, sold by BDH Chemicals Ltd. as Ma - noxol GT) or sold by Rohm and Haas as Triton GR5 (and sulphonated ricinoleic acid derivatives) for example sold by Zschimmor and Schwarz of Lahnstein, Germany (as Glanzol CFD or Glanzol 100). In fact, Glanzol CFD is offered for sale as a plasticizer for coating compounds, but it is also a surfactant. An example of an anionic surfactant which. can be used as a protective agent, but which does not contain a sulphate or sulphonate group is ethylenediamine tetraacetic acid (EDTA). Plasticizers other than Glanzol CFD, which are anionic surfactants, are also effective as protective agents against example: dibutyl phthalate, hexyl di-2-ethyl adipate, dibutyl maleate and tris trimelitate (livenol 7-9). However, these compounds 55 have the disadvantage that, as a result of their use, "greasy" stains are formed on the coated sheet and are therefore not recommended. Another group of substances that can be used as protective agents are fluorine-containing 60 adhesives. for hydrophobic properties such as those sold by Du Pont Zonyl BP or Zonyl NF and sold by Minnesota Mining and Manufacturing Company 65 Scotchban FC 807. If desired, a mixture of nine different protective agents may be used. In some cases, the use of the mixture has advantages over the use of the individual components of the mixture. Mixtures of the fluorine-containing adhesives and resins of the Kymene type mentioned above have been found to have better protective properties than the adhesive or the Kymene type resins alone. The amount of protective agent to be used depends on the type of capsules used and the triggering substance. beautiful color. The optimal amount can be easily determined by a specialist. The amounts given in the examples below may be used as information. In conventional methods, microcapsules used in the self-layer copying method, based on the principle of pressure-sensitivity, must have thicker, i.e. stronger walls than the microcapsules used. in the more widely used method of transfer described above (transfer system). Likewise, in the present method, which is of course a self-layered method, the capsules should also be stronger than normally used in the pressure-sensitive copying method, if a suitable product is to be obtained. The method of producing strong walled capsules intended to be placed on a pressure sensitive copying paper of its own is well known in the art, but will nevertheless be illustrated in any case. However, it is preferable to use capsules with walls stronger than those normally used in However, for the capsules used in the transfer type copying method, a slight reduction in premature color development may be observed if the particulate color developing substance is treated with a self-linking polymer prior to mixing with the suspension of microcapsules during coating preparation. However, the product obtained is probably too colored to be used. Capsules intended for use in the present invention may have synthetic walls, for example, melamine-formaldehyde resin, urea-formaldehyde resin, and acrylic acid amide copolymer and acrylic acid. as set forth in British Patent Application No. 48 616/75 or from a urea-foimaldenide polymer as set forth in KFN Patent No. DOS 2,529,427. Other synthetic substances that may be used include diacryates, polyurethanes, polyureas - or * aminoplasts other than those cited previously. Alternatively, the capsules may have walls of coacervated hydrophilic colloids, for example a mixture of gelatin, acacia or carboxymethylcellulose (CMC) or a copolymer of polyvinyl methyl ether and anhydrous acid (PVM / male anhydrous acid) MA) as set forth in British Patent Specification No. 870,476. Such capsules may be were sufficiently strong when used with self-ply paper, the phase ratio at which they are produced should preferably be lower than the phase ratio for capsules intended for use in the pressure-sensitive transfer type copying method. (the phase ratio is the weight ratio of the solution of the color-forming material to the capsule-wall material in the aqueous solution from which the capsules are obtained). The use of a lower phase ratio results in a thicker capsule wall than a higher phase ratio. If a capsule of the transfer type is used, the use of the present invention will result in less color than if no protective agent is present, however the degree of color is likely too high to be acceptable. Capsules having synthetic walls, for example from aminoplasts, they prove to be stronger and less permeable than gelatine coacerate capsules. Therefore, they tend to be less premature staining than gelatine coacervate-type capsules. However, it has hitherto been found that protection of the capsules with synthetic walls is desirable, although the difference in whiteness between protected and unprotected copy paper may be small. The slight variation in whiteness is noticeable to the naked eye and can greatly affect the commercial suitability of the paper. Not all of the previously cited protective agents can be used with all types of capsules. For example, anionic surfactants leach the contents of capsules having walls of the gelatinous coacervate type, while they may be used with capsules having a synthetic wall of amine plastics. The specification will have no difficulty in choosing a protective agent that is compatible with the capsules it wants to use. Some substances that may be considered suitable for use as protective agents are in fact not suitable. Cationic and non-ionic surfactants, which would be expected to have the same effect as anionic surfactants, poison, as has been found in practice, the color developing substances, that is to say they inhibit its function as a color developer. Retention aids used in papermaking, which are in some respects similar to wet strength agents, could be considered effective, but previous practice has found that they cause iloculation of the coating mixture. . Perhaps there are ways to overcome the above difficulties. The invention is not limited to the use of specific color-producing substances or specific solvents thereof. Examples of color-generating substances that can be used are phthalide derivatives such as crystal violet lactone, fluoran derivatives, diphenylamine derivatives, spiropyran derivatives, phthalimidine derivatives , and benzoyl leuco derivatives of various dyes. As is known in the art, it is possible to use mixtures of color-generating substances. Examples of solvents that can be used are mixtures of partially hydrogenated terphenyls, chlorinated paraffins, diphenyl derivatives, darylmethane derivatives, alkyl naphthalenes, mixtures of dibenzylbenzenes, phthalic or phosphoric esters or linear alkylbenzenes having 10-14 atoms. coal. Solvents may be used in admixture with diluents such as kerosene. . If it is required to treat the capsules, as well as the color developing substance, with a protective agent, the treatment conditions depend on the substances used in the particular case. The choice of these conditions is within the limits of an experienced technologist. The data in some of the examples below may serve as information. The covering mixture may also contain a filler to improve its Theological properties and to increase the whiteness of the coated sheet. Suitable fillers include kaolin and calcium carbonate. Fillers such as is well known can sometimes have very little color development. This effect may not be so severe as to be objectionable, but if so desired, the filler may be treated with a preservative in a similar manner to the color developing agent. For example, the processing conditions for kaolin would be almost the same as for clays after acid treatment to develop color. The selection of the binder of the coating mixture requires special care. Some binders, usually used for copying paper of the type of transferring such as pressure sensitive, may cause color development or they may have other undesirable properties and therefore will not be suitable. For example, a starch binder may reduce the reactivity of the color developing substance. Perhaps the reason is that it forms a film on the surface of the color developer particles. Highly hydrolyzed polyvinyl alcohol has been found to be particularly suitable as a binder of the coating composition of the invention *. The coating mixture may also contain a dispersant, preferably one that also serves to adjust the pH of the mixture. Such developer compound dispersants for use on pressure sensitive copying papers are well known. Examples are sodium silicate and sodium hydroxide, which also serve to adjust the pH. The optimally preferred pH value is chosen to be the most compatible with the color development reaction. For example, if one of the coloring substances is crystal violet lactone and the developing material is acid-treated clay, then the pH value suitable for the coating mixture is about 10.0. The coating mixture may also contain an agent protecting the capsules against premature tearing during storage and handling of the paper rolls. The use of such a protective agent (often known as a backing material) is well known in the art of making copier on the basis. and for this reason, it will not be described. Examples of suitable supporting materials are cellulose fiber in the form of cakes and wheat starch in granules. The typical dry coverage density of papers coated according to the invention is 10-15 g. The coating techniques used to make this paper can be conventional, such as blade coating, air knife method or roller coating. To date, blade coatings have not been conventionally used on an industrial scale for capsule-containing compositions because this method has not been able to apply an economically low-density layer with sufficient uniformity. The present invention facilitates the use of blade coatings as the presence of a color developing agent in the microcapsule mix means that the weight of the coating to be applied is higher than that of a microcapsule only mix. The possibility of blade coating brings significant benefits in terms of the speed of operation and the tonnage of the copier that can be produced in-house. The mechanism by which the protective agent inhibits the premature development of color in the paper-ply mix with the core. it is not completely understandable. It is believed that the action of this factor is to reduce the mutual attraction between the color developing substance and the capsules. Figure 1 shows an enlarged scale of a schematic section of a pressure-sensitive copying paper sheet, and Figure 2 shows a diagram. flow machine illustrating the exemplary method of producing the paper shown in Fig. 1 From Fig. 1 it can be seen that a sheet of copier with its own pressure-sensitive layer comprises a paper substrate 1 supporting a coating 2 containing microcapsules 3 and particles 4 color evoking. The other ingredients of the shell are not shown so as not to obscure the whole. One of them is the protective agent, but it is not known exactly where it is located. From Figure 2, you can see that a fragmented developer, a suspension of microcapsules, a filler, a disk The pergator, the binder, and the pH adjusting agent are mixed to form the coating mixture. Before mixing, the developer and possibly the microcapsules and / or the filler are treated with a protective agent. If necessary, the filler may be mixed with the developer prior to this treatment. In Fig. 2, the transitions al- 10 15 20 25 30 35 40 45 50 55 60 114! 11 alternative alternatives are shown in dashed lines. The mixture is then applied to the paper and dried to obtain sheets of paper as shown in Fig. 1. The invention is illustrated by the following examples: * Example I.% a) Preparation of capsules "" 382 g 9.1% gelatin solution placed in at pH 6.4 in a Waring blender. With the mixer running at low speed, 274 g of internal phase, ie the substance to be encapsulated, was added. The internal phase was a 9: 1 mixture of Dobane JN (a mixture of linear alkylbenzenes having 10-14 carbon atoms in the molecule, sold by SheU) and Saniticizer 711 (a substance containing phytates sold by Monsanto) containing 1, 8% by weight of crystal violet lactone and 1.4% by weight of the benzoyl leuco derivative of methylene blue. Stirring was carried out until the droplet size was less than 3 micrometers. To 218 g of gelatin solution and internal phase emulsion were added 58 g of 17.61% by weight aqueous gum arabic and 422 g of deionized water. The pH was adjusted to 8.7 by adding NaOH and slowly added 8 g of 5 wt.%. Aqueous solution of polyvinyl methyl ether and maleic anhydride (PVM / MA). M 14.7% acetic acid was then used to reduce the pH uniformly to 4.3. During this operation, coacervate was released and droplets of internal phase were coated. The emulsions were then cooled to about 10 ° C. and 3.3 ml of 50% glutaraldehyde were used to cross-link the coacervate. A further 10 g of PVM / MA was added to prevent agglomeration of the capsules. Then, 6.0 g of a 12.5% w / w sodium carbonate aqueous solution was introduced as a pH buffer and the pH was raised very slowly to 10.0 by adding sodium hydroxide. b) Preparation and application of a mixture covering 30 g of clay with an acid treatment (brand Silton M-AB * supplied by Mizusawa Industrial Chemicals Limited) which produces a color dispersion in a quantity of water sufficient to obtain a content of about 3 g%. 3 g of BC 71 melamine-formaldehyde precondensate were added as a protective agent. The resulting slurry was heated to 90 ° C. with stirring, kept at this temperature for 2 hours, and then cooled. Thereafter, 10 g of kaolin (Dinkie brand, English China Clays X.imited brand) was dispersed in such an amount of water as to obtain a solids content of about 36% in the mixture. 1 g of melamine-formaldehyde precondensate as protective agent was added to the mixture, the slurry was heated to 90 ° C, kept at this temperature for 2 hours, and then cooled. The thus prepared Silton clay and Dinkie kaolin are mixed and the pH of the mixture is adjusted to 10 by adding NaOH solution. Then 132 ml of the capsule suspension, prepared as described above, are added to the clay slurry, and then 30 g. % PVOH binder (MOVIOL 56-98 supplied by Harlow Chemical Co. Ltd.) The resulting mixture was applied using a laboratory apparatus at a rate of 9 g / m 2 to a 49 g / m 2 paper substrate. After drying, the whiteness of the paper was checked with a opacimeter (for example, the Bausch and Lomb opacimeter disclosed in US Patent No. 1,950,975 or the Diano BNL 2 opacimeter). The whiteness test measures the sheet's reflectance and compares the result with the reflectance of a standard white surface (surface coated with magnesium oxide powder). The result is expressed as a percentage of the (sheet's reflectance) of X 100 to (reflectance of the sheet) standard white surface). Thus, the higher the score, the whiter the background is. The test is carried out at several different points on the sheet and the results are calculated as the average. A difference of a few percent may seem insignificant, but it is easily visible to the naked eye and can significantly affect the commercial suitability of the paper. An average of 93 was obtained. % 7 The paper turned out to be white. When a normal piece of paper was placed on the thus obtained paper and written on it, a distinct blue writing appeared on the covered sheet. In order to demonstrate the effect of melamine-formaldehyde precondensate, A similar experiment was carried out, with neither Silton clay nor Kaolin Dinkie having been previously exposed to the action of melamine-formaldehyde precondensate, 30 g of Silton M-AB clay and 10 g of Dinkie kaolin dispersed in enough water to obtain mac, the solids content of the mixture was about 4O0 / O. The pH of the mixture was adjusted to 10 by the addition of sodium hydroxide solution. Then 132 ml of a capsule suspension, prepared as described above, were added. and 30 g of 10ty PVOH binder (Gohsenol NH 26 "supplied by Nippon Synthetic Chemical Industries Oo.). Ltd., Japan). The resulting mixture had a pale blue color, and when applied to paper at 9 g / m2, a pale blue sheet color was obtained with an average reflectance of 81%. Example II. This example illustrates the use of various self-crosslinking polymers as a protective agent. The protective agent was obtained by dissolving 3 g of Nadavin FP in 60 g of water. 30 g of acid treated clay with a color developing Silton M-AB brand and 10 g of Dinkie's kaolin are dispersed in this solution. To prevent flocculation, 2 g of the Lithium Dispex N 40 solution (dispersant supplied by Allied Collids Ltd. as a liq. Solution) was added. The pH was slowly adjusted to 10 by the addition of sodium hydroxide solution after Then 132 ml of capsule suspension prepared as described in the description were added. g) was mixed with 0.55 g of melamine-formaldehyde resin BC 71, serving as a protective agent, and the mixture was heated to 70 ° C. and held at this temperature for 1 hour, then allowed to cool. The treated color developed clay slurry was then mixed and the treated slurry containing capsules was mixed, 15 milliliters of 10% polyvinyl alcohol ("Gohsenol NH 26") was added with stirring, and 15 g kaolin (brand name Dinkie ') was added with stirring. A '). The slides in Example 1 followed by 30 g of 101% PVOH binder (MOVIL 56-98). The color of the mixture thus obtained was slightly pale blue, and when the paper was covered with a density of 8 g / cm 2, it was used sheets with a pale blue color and a reflectance of 87% were scanned, a better result than when Silton clay was not used, which, as found in Example 1, gave a reflectance of 81%. By repeating the procedure, but using others After the dye solution, a sheet was obtained after the Silton clay had been treated, the average reflectance of which was 88%. When a plain sheet of paper was placed on the coated sheets, prepared according to the procedures described above, and written on it in normal way, was obtained on both covered with ar a clear blue reflection. Example III. a) Preparation of capsules The following substances were mixed: - 19 g of cationic urea-formaldehyde resin BC 77 with a reactive resin concentration of about 45% and a solids content of about 35% (BC 77 supplied by British Industrial Plastics Xiimited), - 42 g of R 1144 (20% solution of acrylic acid amide / acrylic acid copolymer with an average molecular weight of 40,000 and an acrylic acid content of 42%, supplied by Allied Colloids Limited), - 200 g of deionized as per the mixture. to 55 ° C and held at this temperature for 45 minutes, then 12 g of BC 336 melamine-formaldehyde precondensate were added and the pH was lowered to 4.4 by the addition of acetic acid. Then, 89 g of a colorator solution was added and the dispersed mixture thus obtained was comminuted until the droplet size was obtained. 4-5 microns, and then 20 g of deionized water was added. The mixture was stirred for one hour at 35 ° C and for a further two hours at 55 ° C, then allowed to cool to ambient temperature overnight. The next morning, the pH was raised to 10.0 by the addition of a 10% sodium hydroxide solution. The solids content of the resulting capsule suspension was approximately 30%, and the phase ratio was 3.4: 1. B) Formation of the cover mixture and its application of 15 g of acid-treated clay with Silton M-AB brand giving a color the amount of water was dispersed so as to obtain a solids content of the mixture of about 40%, and 1.5 g of melamine-formaldehyde precondensate was added as a protective agent. The mixture was heated to 90 ° C., kept at this temperature for 2 hours, then allowed to cool. The pH was then adjusted to 10 by adding sodium silicate. 20 milliliters of capsule suspension (dry capsule weight 5.5 65) The resulting mixture was then applied to a sheet of paper as described in Examples I and II, with the difference that the density was 12.5 g / m2. The sheet was checked for whiteness giving / average The result was 93.5%. When a sheet of normal paper was placed on the thus obtained copying sheet and recorded using normal pressure when writing, a clear blue reflection was obtained on the coated sheet. After 10 days, the whiteness measurement was repeated. the sheet gave an average value of 88%. Example IV.a) Preparation of capsules The method of preparation was as in Example III, except that after adding and grinding the color-producing substance solution, 40 g of deionized water and 10 g of BC were added. 336. The following procedure was carried out as described in Example III. b) Preparation of the coating mixture and its application 20 g of acid-treated clay of the Silton M-AB brand, which develops a color, was dispersed in such an amount of water to obtain a solids content of the mixture of about 40%, and then added 2.0 g of BC 71 melamine-formaldehyde precondensate as protective agent. The mixture was heated to 90 ° C, kept at this temperature for 2 hours and allowed to cool. The pH was then adjusted to 10 by adding sodium silicate. 15 g of kaolin (DinkieW brand) were dispersed in such an amount of water to give the mixture a solids content of about 50%, and then 1.5 g of melamine-formaldehyde precondensate was added as a protective agent. The mixture was heated to 90 ° C. C, held at this temperature for 2 hours, and then allowed to cool. The treated clay developing color and the treated kaolin slurry were then mixed. 25 milliliters of capsule suspension (dry capsule weight 5.8 g) was mixed with 0.58 g of BC 71 melamine-formaldehyde precondensate as protective agent, then heated to 70 ° C, kept at this temperature. for 1 hour and allowed to cool. The treated slurry was then added to the treated clay slurry. 15 milliliters of 10% polyvinyl alcohol ("Gohsenol 26") was added with stirring. The resulting blend was applied to a sheet of paper as described in the previous examples with 30 35 40 4515 114 234 16 10 15 20 25, the difference being that the density was 14 g / m8. The whiteness of the sheet was checked and an average result of 97% was obtained. When a sheet of plain paper was placed on the sheet covered in this way and written in the normal way, a clear blue reflection was obtained on the coated sheet. the whiteness of the sheet and an average value of 96% was obtained. EXAMPLE 5 Capsules prepared as in Example 4 were used in this example, but were not treated with melamine-formaldehyde precondensate. 15 g of acid treated clay of the Silton M-AB brand giving barium The mixture was dispersed in such an amount of water as to obtain a substance content of about 40%, and then 1.5 g of BC 27 melamine-formaldehyde resin was added as a protective agent. The mixture was heated to 90 ° C and maintained. It was left at this temperature for 2 hours and then allowed to cool. The pH was adjusted to 10 by adding sodium silicate. 25 milliliters of the capsule suspension (mass of dry capsules 5 g) were added, followed by mixing 15 milliliters of 10% polyvinyl alcohol CGohsenol NH 26 "and 15 g of kaolin (Dinkie brand The resulting mixture was then applied to the sheet). of the paper as described in the previous examples, except that the coverage density was 13.6 g / m2. The whiteness of the sheet was checked and an average result of 96.5% was placed on the sheet so coated. On the coated sheet and recorded in the normal way, a clear blue reflection was obtained on the coated sheet. After 10 days, the whiteness measurement of the sheet was repeated, giving an average value of 96%. Example VI. This example uses capsules prepared as in Example IV, but were not then treated with a melamine-formaldehyde precondensate. 30 g of Silton M-AB clay was dispersed in such an amount of water as to obtain a solids content of the mixture of about 40%. pH to 10 by adding sodium silicate. The resulting mixture was divided into two parts. One of them was treated with melamine-formaldehyde precondensate as a protective agent as described in Example 4. 22 milliliters of the capsule suspension (dry capsule weight approximately 7 g) was added to both parts of the slurry, and then mixed with 15 milliliters of 10% PVOH ("Cohsenol NH 26") each. applied to a sheet of paper as described in the previous examples so that the coverage density was 8 g / m 2. The color of the sheet coated with the precondensate treated compound was white and the background reflectance was 95% on average, while for on the second blend, this ratio was 91%. When plain paper sheets were placed on both coated sheets and written in the normal way, a clear blue reflection was obtained on both coated sheets, but on the sheet covered with the mixture. the inscription containing precondensate was clearer. After 10 days the reflectance measurements were repeated and an average value of 92% was obtained for the sheet covered with the precondensate treated mixture, and for the second sheet this value "was 85%. Example VII. This example illustrates the use of an amino-epichlorohydrin resin as a protective agent in place of a resin or a melamine-formaldehyde precondensate. The capsules used in this example were prepared as described in Example 4, but were not treated with a meta-formaldehyde precondensate. 15 g of acid treated clay of the Silton M-AB brand, which develops color, was dispersed in such an amount of water, containing 1.5 g of aminoepichlorohydrin resin serving as a protective agent, to obtain a solids content of the mixture of about 30%. . The pH was adjusted to 8 by adding sodium hydroxide, the mixture was stirred at room temperature for a few minutes. The pH was then adjusted to 10 with sodium hydroxide. 22 milliliters of the capsule suspension (dry weight 7 g) were added followed by mixing with 15 milliliters of 10% polyvinyl alcohol ("Gohsenol NH 26"). The resulting mixture was applied to a sheet of paper at a density of 8 g / m2. white in color and the whiteness measurements gave an average background reflectance of 93%. When a sheet of normal paper was placed on the coated sheet and written in the normal way, a clear blue reflection was obtained on the coated sheet. After 10 days the whiteness measurement was repeated. and an average value of 92.1% was obtained. It should be noted here that the heating of the Nadavin resin is unnecessary, that is, contrary to the previously described melamine-formaldehyde resins. Moreover, the possibility of formaldehyde vapor formation is minimal. VIII. This example illustrates the production of a pressure-sensitive copying paper according to the invention by a coating operation on an industrial scale apparatus. - a) Preparation of Opera capsules The phase ratio was 2.7: 1 as follows: 80.0 kg of hot deionized water was mixed with 16.8 kg of acrylic acid amide / acrylic acid R 1144 copolymer and the temperature was raised to 55 ° C. Thereafter, 7.6 kg of BC 77 urea-formaldehyde resin were added and mixed for 40 minutes while maintaining a temperature of 55 ° C. 8.9 kg of BC 336 melamine-formaldehyde precondensate were added and the pH was adjusted to 4.4 by the addition of acetic acid. Then, 36.4 kg of the colorant solution was added and the resulting dispersed mixture was ground so that the droplet size was 4-5 micrometers. The pH was adjusted to 4.0 with acetic acid, and the mixture was warmed up. to 55 ° C and held at that temperature for 3 hours. The pH was then increased to 1.0 and the mixture was allowed to stir overnight. The solids content of the resulting capsule-containing emulsion was 29.5%. b) Preparation of the coating mixture and its application 100 liters of water are placed in a casein kettle and 50 kg of Silton M-AB clay are dispersed therein. Thereafter, 5 kg of melamine-formaldehyde precondensate was added as a protective agent, and the mixture was kept at 90 ° C for 2 hours with constant stirring. The mixture was then transferred to the pre-mill and the entire procedure was repeated, adding 50 kg. Silton M-AB clays. 100 kg of Dinkie 'A * brand kaolin was treated in the same way as described for Silton M-AB clay, and the resulting mixture was also transferred to a pretensioner. Thereafter, 3 kg of sodium silicate at 501% concentration were added and the resulting slug was transferred to a storage vat. 11 kg of PVOH ("Gohsonol NH 26") was added to 136 liters of water placed in a casein kettle. The water was heated to 90 °. C to dissolve the PVOH and the solution was transferred to another pretzel mill. 145 liters (47 kg dry capsule weight) of the capsule suspension prepared as described in (a) above were then added to the casein kettle. Melamine-formaldehyde precondensate BC 71 as a protective agent, mixed, and the mixture heated to 70 ° C for 1 hour with continuous stirring. The mixture was then added to the PVOH contained in the pre-mill. The mixture was added to the clay slurry in the storage vat. After standing overnight, the mixture was applied to the paper using an air-knife coating device. A range of different densities were applied. The results are shown in Table I When a sheet of plain paper is placed on the coated sheet and written in the normal manner, clear blue reflections were obtained on the coated sheet. After 10 days, the whiteness measurement of the sheet sample with a coverage density of 14.0 g / m2 was repeated and an average value of 94.01% was obtained. After 14 months, the whiteness measurement on the same sheet was repeated and an average value of 93.4% was obtained. Example IX. This example illustrates the production of a pressure-sensitive copying paper according to the invention with an industrial-scale coating device, this time using a cross-linking polymer different from the previous example. a) Preparation of capsules The capsules used in this example were prepared as described in example VIII. b) Preparation of the coating mixture and its application 19 kg of Nadevin FP, serving as a protective agent, and 50 g of Dispex N 40, were dissolved in 209 liters of water placed in a bar mill. 75 kg of Silton M-AB clay and 25 kg of Dinkie A kaolin were dispersed in this water. The pH was adjusted to 10 by slowly adding 14% sodium hydroxide solution. About 178 kg of clay were added to this clay slurry ( weight of dry capsules 55 kg) of suspension containing the capsule,. prepared as described. in a) above. Then 30 kg of Dow 620 latex binder (dry weight 15 kg) was added and, after homogenization, the mixture was transferred to a storage vat. This mixture was applied to paper using an air knife coating device. The results are shown in Table II below: Table 1 ica II 40 45 Density of coverage (g / m2) Average reflectance of the background,% 5 96 4 96 6 97 When a sheet of plain paper is placed on the coated sheet and written in the normal way, a clear blue was obtained on the coated sheet reflection. "" After 12 days, the whiteness measurement of the sheet with a cover density of 6 g / m2 was repeated and an average value of 96% was obtained. After 10 weeks, the whiteness measurement was repeated. Coverage density ¦fe / m «) Average reflectance of the background,« / o 17.0 95.9 17.0 36.2 Table 16.7 97.0 I 8.3 96.4 16.7 96.9 14.0 95.3 14.7 * 96.7f V id of the same sheet and an average of 96% was obtained. Example X 10 g of Silton M-AB brand clay and 3 g of Dinkie! A 'kaolin were dispersed in 20 ml of water and a protective agent was added. The pH was adjusted to 10 by the slow addition of sodium hydroxide solution. 38 ml of the suspension containing the capsules were then added with a solids concentration of 17.5% (prepared similarly to Example I). 10 g of 10% PVOH binder (MOVIL 56-98) was also added. The resulting mixture was applied at a density of about 10 g / m2 to a paper substrate having a basis weight of 49 g / m2. After drying, the background reflectance was measured at different positions on the sheet using an opacimeter as described previously and its average value determined. The results, together with the results of a control experiment in which no protective agent was applied, are presented in Table III. Table III, Protective Factor. and its amount (in relation to the weight of the clay) Without the protective agent (control) Nadavin FP (10%) Polyamin P (10%) Zonyl BP (10%) Menoxol IB (10%) Kymene 709 (5%) Zonyl RP (0.5%) Reflectance coefficient background (° / o) - initial 84.5 87.8 91.3 91.2 89.4 s 88.8 after 10 days 81.8 85.1 90.7 89.7 83.5 84.2 Each of the sheets with the coating treated with the protective agent was placed under a sheet of plain paper which was then wrapped. In each case a clear blue reflection was obtained on the coated sheet. Example XI. a) Capsule Preparation 42 g of R 1144 copolymer was added to 170 g of deionized water and the mixture was heated to 55 ° C. To this was added 19 g of BC 77 resin and the mixture was held at 55 ° C for 40 minutes. Then 105 g of deionized per dye and 179 g of coloring agent were added. The resulting dispersed mixture was ground to a droplet size of 4-5 microns and cooled to 15 ° C. 40 g of BC 336 precondensate and 125 g of deionized water were then added, and the pH was adjusted to 4.15 by adding Acetic acid. The temperature was held at 15 ° C for one hour, then raised to 55 ° C and held at that level for a further two hours 20 minutes. Finally, the pH was raised to 8.5 by 2 hours. addition of sodium hydroxide solution b) Preparation of the coating mixture and its application, 9 22.5 g of Silton M-AB clay and 7.5 g of Dinkie 'A * kaolin were dispersed in 40 g of water, and a protective agent was added. was adjusted to 10 by the slow addition of sodium hydroxide solution, then 65 ml of a capsule suspension containing approximately 30% solids (prepared as described above) was added and 22.5 g of granulated wheat starch (Keestar) was added. 328 provided by Stale y Starch Company) to prevent the capsules from prematurely rupturing, as already mentioned above, along with 15 g of latex binder (620 Latex supplied by Dow Chemical). The resulting mixture was applied at a density of about 10 g / m2 to a paper substrate with a basis weight of 49 g / m2. After drying (about 105 ° C for 20 seconds), the background reflectance was measured with an opacimeter at different positions on the sheet and the average value was determined. The results, together with the result of a control experiment in which no antifreeze was applied. Table IV The protective factor and its amount (in relation to the mass of clay) Without protective factor (control) Nadavin FP (10%) Glanzol CFD (10%) Kymene 557 (5%) + Zonyl RP (0.5%) Emulsion of polyethylene (10% -polyethylene calculated on the strength basis). Background reflectance (%) initial 93.2 95.0. 95.1 94.7 95.1 and after 10 days 92.6 93.9 94.1 93.3 93.9 Each sheet with the coating treated with the protective agent was placed under a sheet of plain paper which was then written. In each case a clear blue reflection was obtained on the coated sheet. Example XII. Example XI was repeated using a series of 80-ammonium surfactants as a protective agent. For comparison, the experiments with Nadanin FP and GlanzoFu were repeated, as well as A control experiment in which no protective agent was applied The results are shown in Table V, 21 - Table V 114 234 22 Table VI Protective factor and its amount (in relation to the mass of clay) Without protective agent (control) Nadavin FP (10%) Glanzol CFD (10%) Sodium salt of dodecylbenzenesulfonic acid to (10l0 / o) EDTA (10%) Manoxol 1 B (10%) Manoxol 1 T (10%) Sodium lauric sulphate- lowa (10%) 1 1 Triton GR 5 (10%) Nopcote C 104 (10%) Background reflectance (%) initial 93.3 95.3 95.0 95.1 95.9 ^ 95.9 95.1 95.3 96.3 94.7 after 10 days 92.1 94.5 94.5 94.4 94.3 95 3.94.5 94.7 95.9 µm 94.1 Each of the coated sheets was placed under a sheet of plain paper which was then wrapped. In each case a clear blue reflection was obtained on the coated sheet. Example XIII. 22.5 g of Silton M-AB clay and 7.5 g of Dinkie 'A' kaolin were dispersed in water and the protective agent was added. The pH was adjusted to 10 by the slow addition of sodium hydroxide solution. Then 65 ml of suspension containing microcapsules with a solids concentration of approximately 30% (prepared as described in example XI) as well as 22.5 g of wheat starch granules were added. Keestar 328 and 15 g of Dow 620 latex binder. The resulting mixture was then applied at a density of about 10 g / m 2 to a 49 g / m 2 paper substrate. After drying, the background reflectance was measured at various points on the sheet with a opacimeter. previously described and its average value was determined. The results, along with the result of a control experiment in which no preservative was applied, are given in Table VI. Each of the coated sheets was placed under a sheet of plain paper which was then wrapped. In each case a clear blue reflection was obtained on the coated sheet. Example 14. In this example, capsules prepared as described in German Patent Specification No. 2,529,427 were used. 22.5 g of Silton M-AB clay, 7.5 g of the protective agent and its amount (based on the weight of the clay) were mixed. protective factor (control) Nadavin FP (10%) Nadavin LT (10%) Kymene 70.9 (10%) Kymene 557 (15%) Kymene 557 (5%) + Zonyl RP (0.5%) 1 Glanzol CFD (10%) Kymene 557 (3%) +. Glansol CFD (3%) + Zonyl RP (0.3%) Nopcobond SWS 10 (10%) Background reflectance (%) initial 95.2 96.3 95.9 95.9 95.9 95.7 96.1 95.9 95.8 after 10 days 94.3 95.8 94.9 95.1 95.2 94.9 95.3 | 95.4 | 95.2 Dinkie W brand kaolin, protective agent and 40 g of water; the pH of the mixture was then adjusted to 10 by adding sodium hydroxide solution. Then 50 g of a suspension containing capsules with a solids concentration of approximately 40% and 22.5 g of Keestar 328 Kio wheat starch and g of latex binder were added. Dow 620. The mixture was applied at a density of about 10 g / m2 to a 49 g / m2 paper substrate and dried at 105 ° C for about 20 seconds. The results, together with the results of the control experiment in which no protective agent was applied, are given in Table VII. Table VII. Protective factor and its amount (based on the weight of clay) Without protective agent (control) Nadavin FP (10%) Polymin P (10%) 1 Zonyl RP (10%) | Glanzol CFD (10%) Sodium Lauryl Sulphate (10%) Teepol 610 (10%) | Teepol GD 53 (10%) Background reflectance (%) initial • 76.4 90.0 84.8 85.7 85.7 87.0 86.4 85.8 after 10 days 64.3 85.9 ai, 8- 79.5 79.9 1 72.3 78.0 | 73.0, 23 114 234 24 Teepol 610 is an anionic surfactant supplied by Shell. It is the sodium salt of the secondary alkyl sulfate. Teepol GD 53 is also a surfactant sold by Shell. It is a mixture of sodium alkylbenzene sulphonate, sodium ethoxyl sulphate and nonionic alcohol ethoxylate. Each coated sheet was placed under a sheet of plain paper which was then written. In each case, a clear blue reflection was obtained on the coated sheet. Example XV-. The procedure of Example XIV was repeated except that, instead of the suspension containing the capsule used in Example XIV, 65 ml of the suspension prepared as described in Example XI was used. The results are given in Table VIII. Table VIII Protective factor and its amount (in relation to the weight of clay) 1 Without protective factor (controls) [Nadavin FP (10%) | Glanzol CFD (10%) | Teepol 610 (10%) V Tergitol 7 (10%) Background reflectance (%) initial 94.9 95.4 96.1 96.2 96.5 after 10 days 94.3 95.0 95.6 95.5 95.8. Tergitol 7 is an anionic surfactant supplied by BDH Chemicals Limited. It is a sodium salt of a secondary alkyl sulfate having 17 carbon atoms. Each of the coated sheets was placed under a sheet of plain paper which was then written. In each case a clear blue reflection was obtained on the coated sheet. Example XVI. This example illustrates the production of paper according to the invention using an industrial blade-type coating apparatus. The capsules used herein were prepared generally as described in Example 11, except that the amounts used were increased according to the scale shift and the mixture, after cooling to 15 ° C, was kept at 55 ° C overnight. 22.5 kg of Nadavin FP and 296 liters of water were added to the mixer and 225 kg of Silton M-AB clay was dispersed in the resulting mixture. The pH was then raised to 8 by adding 13.7 g of 47% sodium hydroxide solution. 500 kg (139 kg dry) of the suspension containing the capsules were then added. 225 kg of Keestar 328 wheat starch and 75 kg of Dinkie 'A' kaolin were dispersed in this mixture, followed by 150 kg of Dow 620 latex binder (75 kg dry). The resulting mixture was applied with a density of about 14 g. / m2 on a paper substrate with a weight of 47 g / m2. The reflectance of the background of the coated sheet was 96.1% immediately after coating, 96.0% after 10 days and 94.5% after 7 months. When a sheet of plain paper was placed on the coated sheet and written in the normal way, a clear blue reflection was obtained on the coated sheet. Example XVII. This example illustrates the application of the method of the invention to carbon-type capsules rather than self-film capsules. As previously stated, the use of this type of capsule generally does not result in sufficiently bright sheets. However, the results show that the method according to the invention gives an increase in resistance to premature color development for any wall thicknesses of the capsules used. The capsules used in this example were prepared similarly to the method described in Example 1 of British Patent No. 1,053,935, except that carboxymethyl cellulose was used instead of gum arabic. The capsule suspension was divided into three parts a), b) and c). 10 - Part a) The capsule suspension was treated with 13% BC 71 melamine-formaldehyde precondensate solutions as a protective agent. 5 Operations were carried out at 60 ° C for 1/2 hour, then all of it was allowed to cool. making. 40 g of Silton M-AB clay was dispersed in such an amount of water to obtain a solids content of 40% in the mixture. The pH was adjusted to 10 by adding sodium silicate. Then 100 ml of the capsule suspension were added with constant stirring and the resulting mixture was applied to a sheet of paper. A dark blue sheet with a reflectance of 19% was obtained. Part b) The suspension containing the capsules was treated as described for part a). 50 g of Silton M-AB clay was dispersed in such an amount of water that the solids content of the mixture was 40%. Then 4 g of BC 71 melamine-formaldehyde precondensate was added as a protective agent, the mixture was heated to the boiling temperature. and allowed to cool, then the PH was adjusted to 10 by adding sodium silicate. 100 ml of the capsule suspension was then added with constant stirring and the resulting mixture was applied to a sheet of paper in the same manner as described above. The sheet also had. blue color. The refractive index was 30%, which is much more than the 19% found when no clay treatment was used. C) In this case, the suspension containing capsules was not treated before it was used. g of water was dissolved in 4 g of Nadavin FP resin as a protective agent. 40 g of Silton M-AB clay were dispersed in this solution, resulting in a solids content of the mixture of approximately 40%. The pH was adjusted with stirring for a few minutes with a sodium hydroxide solution. Then 100 ml of the slurry containing the capsules were added with constant stirring, and the resulting mixture was applied to a sheet of paper in the manner described above. The sheet was blue again. The reflection coefficient was 3910%, which is again much more than 19%, was found in the case of not using the clay treatment. The paper coats, a coating mixture that contains both a particulate mineral color-developing material and microcapsules containing a solution of a colorless color-developing material that is reactive with the color-developing material to form a colored product, characterized by the fact that the particles are The color developing agent, as well as possibly the microcapsules, are treated with a protective agent in an amount sufficient to inhibit premature color development, which factor is compatible with the type of microcapsules and does not substantially reduce the properties of the color developing agent. 2. The method according to claim The method of claim 1, wherein the protective agent is a self-crosslinking polymer, for example a self-crosslinking agent that gives the paper a wet strength. 3. The method according to p. A process as claimed in claim 2, characterized in that an amino-plast, for example a urea-formaldehyde or a melamine-formaldehyde polymer, is used as the cross-linking polymer. 4. The method according to p. The method of claim 2, wherein the self-crosslinking polymer is an epichlorohydrin polymer, for example an aminoepichlorohydrin polymer or an amide-amino-epichlorohydrin copolymer. 5. The method according to p. 4. The process of claim 4, wherein the protective agent is anionic surfactant. 6. The method according to p. 5. The method of claim 5, wherein the surfactant is a sulfate-containing surfactant, for example a salt of lauryl sulfate, or a sulfonate surfactant, for example sulfonated ricinoleic acid, dodecylbenzene sulfonate salt, or sulfosuccinic acid dibutyl or dioctyl ester. 7. The method according to p. The method of claim 1, wherein the protective agent is a paper glue containing fluorine. 8. The method according to p. A process as claimed in claim 1, characterized in that a non-self-crosslinking agent is used as a protective agent, which gives the paper a wet strength, for example a polyethylene imine resin. 9. The method according to p. The method of claim 1, wherein the protective agent is a material that reduces the adhesion between the microcapsules and the particles of the color developing substance. 10. A copying material with an inherent pressure-sensitive layer, which is the material in the sheets coated with both a particulate mineral color builder and with microcapsules containing a solution of a colorless color builder material, which material is reactive with the substance. a color developing agent to form a colored product characterized in that it contains microcapsules and color developing substances in one applied layer, this layer also containing sufficient protective agent to inhibit premature color development, which is the agent is compatible with the type of microcapsules and does not substantially reduce the color developing properties of the agent. 11. Material according to claim The process of claim 10, wherein the protective agent is a self-crosslinking polymer, for example a self-crosslinking agent, which gives the paper a wet strength. 12. Material according to claim The process of claim 11, wherein the self-crosslinking polymer is an aminoplast, for example a urea formaldehyde or a melamine formaldehyde polymer. 13. Material according to claim The method of claim 11, wherein the self-crosslinking polymer is an epichlorohydrin polymer, for example an aminoepichlorohydrin polymer or an amide-copolymer. -aminoepichlorohydrin. 14. Material according to claim The method of claim 10, wherein the protective agent is an anionic surfactant. 15. Material according to claim The process of claim 14, wherein the surfactant is a sulfate-containing surfactant, for example a salt of lauryl sulfate, or a sulfonate surfactant, for example. a sulfonated ricinolic acid derivative, a dodecylbenzenesulfonic acid salt, or a dibutyl or dioctyl ester of sulfosuccinic acid. 16. Material according to claim The method of claim 10, wherein the protective agent is a fluoride-containing paper gluing agent. 17. Material according to claim The method of claim 11, wherein the protective agent is a non-self-crosslinking agent which gives the paper a wet strength, for example a polyethylene imine resin. 18. Material according to claim 10. A method according to claim 10, characterized in that it comprises as a protective agent a substance which reduces the mutual attraction between the microcapsules and the particles of the color developing substance. xK FIG. 1.s * [, a. 4 \, o. • .o- '0. °. .o • 'ol v «, .TZZZZZZZZZZl FIG. 2 PROTECTIVE FACTOR k PARTIAL COLOR DEACTOR FILLER BINDER. COATING MIXTURE] COATING IN ONE OPERATION ^ SUSPENSION AND MICROCOPULES | DRYING | COPY PAPER WITH ITS OWN PRESSURE SENSITIVE LAYER Price PLN 100

Claims (1)

Claims 1. A method of producing a pressure sensitive in-house copying material comprising a sheet coating step, for example a sheet of paper, a coating compound that contains both a particulate mineral color developing substance and microcapsules containing a solution of a colorless color-developing substance which is reactive towards the color-developing substance to form a colored product, characterized in that the particles of the color-developing substance, as well as possibly microcapsules, are treated with a protective agent in an amount sufficient to suppress premature development. color, which factor is compatible with the type of microcapsules and does not in principle diminish the color developing properties of the substance. 2. The method according to claim The method of claim 1, wherein the protective agent is a self-crosslinking polymer, for example a self-crosslinking agent that gives the paper a wet strength. 3. The method according to p. A process as claimed in claim 2, characterized in that an amino-plast, for example a urea-formaldehyde or a melamine-formaldehyde polymer, is used as the cross-linking polymer. 4. The method according to p. The method of claim 2, wherein the self-crosslinking polymer is an epichlorohydrin polymer, for example an aminoepichlorohydrin polymer or an amide-amino-epichlorohydrin copolymer. 5. The method according to p. 4. The process of claim 4, wherein the protective agent is anionic surfactant. 6. The method according to p. 5. The method of claim 5, wherein the surfactant is a sulfate-containing surfactant, for example a salt of lauryl sulfate, or a sulfonate surfactant, for example sulfonated ricinoleic acid, dodecylbenzene sulfonate salt, or sulfosuccinic acid dibutyl or dioctyl ester. 7. The method according to p. The method of claim 1, wherein the protective agent is a paper glue containing fluorine. 8. The method according to p. A process as claimed in claim 1, characterized in that a non-self-crosslinking agent is used as a protective agent, which gives the paper a wet strength, for example a polyethylene imine resin. 9. The method according to p. The method of claim 1, wherein the protective agent is a material that reduces the adhesion between the microcapsules and the particles of the color developing substance. 10. A copying material with an inherent pressure-sensitive layer, which is the material in the sheets coated with both a particulate mineral color builder and with microcapsules containing a solution of a colorless color builder material, which material is reactive with the substance. a color developing agent to form a colored product characterized in that it contains microcapsules and color developing substances in one applied layer, this layer also containing sufficient protective agent to inhibit premature color development, which is the agent is compatible with the type of microcapsules and does not substantially reduce the color developing properties of the agent. 11. Material according to claim The process of claim 10, wherein the protective agent is a self-crosslinking polymer, for example a self-crosslinking agent, which gives the paper a wet strength. 12. Material according to claim The process of claim 11, wherein the self-crosslinking polymer is an aminoplast, for example a urea formaldehyde or a melamine formaldehyde polymer. 13. Material according to claim The method of claim 11, wherein the self-crosslinking polymer is an epichlorohydrin polymer, for example an aminoepichlorohydrin polymer or an amide-copolymer. -aminoepichlorohydrin. 14. Material according to claim The method of claim 10, wherein the protective agent is an anionic surfactant. 15. Material according to claim The process of claim 14, wherein the surfactant is a sulfate-containing surfactant, for example a salt of lauryl sulfate, or a sulfonate surfactant, for example. a sulfonated ricinolic acid derivative, a dodecylbenzenesulfonic acid salt, or a dibutyl or dioctyl ester of sulfosuccinic acid. 16. Material according to claim The method of claim 10, wherein the protective agent is a fluoride-containing paper gluing agent. 17. Material according to claim The method of claim 11, wherein the protective agent is a non-self-crosslinking agent which gives the paper a wet strength, for example a polyethylene imine resin. 18. Material according to claim 10. A method according to claim 10, characterized in that it comprises as a protective agent a substance which reduces the mutual attraction between the microcapsules and the particles of the color developing substance. xK FIG. 1.s * [, a. 4 \, o. • .o- '0. °. .o • 'ol v «,. TZZZZZZZZZZl FIG. 2 PROTECTIVE FACTOR k PARTIAL COLOR DEACTOR FILLER BINDER. LiSPERGATOR LCZYNMJK ADJUSTING MIXING AND FORMING! COATING MIXTURE] COATING IN ONE OPERATION ^ SUSPENSION AND MICROCOPULES | DRYING | COPY PAPER WITH ITS OWN PRESSURE SENSITIVE LAYER Price PLN 100