CS214740B2 - Independent copying material sensible for the pressure and method of making the same - Google Patents

Abstract

The present invention relates to a separate copying device a pressure sensitive material comprising the same sheet material coated with mineral particles the color of the developing material and the microcapsule, colorless solution a colorformer that is reactive with color developing material to create a color product. The nature of this material it is that the microcapsule and the color of the developer the material is contained in a single layer wherein the layer also comprises a composition to prevent premature development colors. A material of the invention is possible Use when making copies of written text

Description

The present invention relates to a separate pressure-sensitive copying material comprising a sheet material coated with particles of a mineral color developing material and a microcapsule enclosing a solution of a colorless coloring agent that is reactive with the color developing material to form a color product. The invention also relates to a process for the manufacture of this material.

In prior art pressure sensitive copying systems, the underside of the top sheet is coated with microcapsules containing a colorless coloring agent solution, and the top of the bottom sheet is coated with a color developing material, such as acid clay or phenolic resin. Usually, several intermediate sheets are also used, each of which is coated with microcapsules on its lower surface and coated with coloring material on its upper surface. The pressure exerted on the sheets by hand or by typing breaks the microcapsules, releasing a colorless solution the coloring agent, which thus comes into contact with the color developing material, whereby a dye is formed at the points where pressure is applied.

Such a system has the disadvantage that it is necessary to produce at least two and usually three types of coated sheets, i.e. the upper and lower sheets, and the intermediate sheets.

In order to overcome the disadvantages of this system, it has been proposed to use a so-called stand-alone system. In this system, the microcapsules and the color developing material are applied to one side of one sheet, and by hand or typewriting on the other sheet which is applied to the first sheet thus laminated, the walls of the microcapsules break and release colorless color forming. a component which then reacts with the color developing material to form a dye at the points where pressure is applied.

The disadvantage of this separate system is that it has so far been necessary to coat the first sheet twice. The mixture containing the microcapsules is first applied to it and only then the color of the developing material is applied to the layer thus formed.

Obviously, it would be easier and also cheaper to apply the microcapsules and the color developing material simultaneously. Such a process is described, for example, in U.S. Pat. No. 2,730,457. However, it has been shown that color development occurs either when the suspension of the microcapsules is mixed with the color development material dispersion prior to application of the mixture to the sheet, or after applying said mixture to the sheet.

The reasons for the premature development of a colorless coloring agent are probably very complex and are not yet fully understood. One of the reasons for the premature development of the colorless coloring agent is probably that the microcapsule suspension contains a certain amount of unencapsulated colorless coloring agent solution that rapidly reacts with the color developing material to form a dye.

It has also been found that premature development of a colorless dye component may occur even if the microcapsule suspension does not contain an unencapsulated colorless dye component (for example, when the unencapsulated colorless dye component is removed prior to mixing the microcapsules with the color developing material). The reason for the premature development of the colorless coloring agent in this case is not entirely clear, but research has shown that this may be due to the interaction between the microcapsules and the particles of the color developing material. The exact mechanism of this interaction is not yet known. /

Finally, it has been found that even if an uncoloured microencapsulated and particulate coating composition was obtained the color of the developing material, the paper coated with the composition is colored immediately upon drying or several days after coating. Again, the reason for the premature development of the coloring agent is not entirely clear.

It has now been found that the aforementioned premature development of a colorless coloring agent can be substantially avoided by suitable chemical treatment of the color of the developing material and / or the microcapsules.

The above-mentioned disadvantages do not have a separate pressure-sensitive copying material according to the invention, comprising a sheet material coated with particles of a mineral color developing material and a microcapsule enclosing a solution of a colorless colorant which is reactive with the color developing material to form a color product. The microcapsules and the color developing material are contained in a single layer, the layer also comprising a means for preventing premature unwinding of the ink from the group comprising a self-crosslinkable polymer, for example a self-crosslinkable wet strength agent, anionic surfactant, sizing agent. paper containing fluorine, a non-crosslinkable wet strength agent such as a polyethyleneimine resin, and a substance that is effective in reducing the mutual attraction between m and the color of the developing material.

The separate pressure-sensitive copying material of the invention preferably comprises an aminoplast polymer, such as a urea-formaldehyde or melamine-formaldehyde polymer, as a self-crosslinking polymer.

The separate copying material according to the invention also preferably comprises, as a self-crosslinkable polymer, an epichlorohydrin polymer, for example an amino epichlorohydrin polymer or an amide-amino epichlorohydrin copolymer.

As the surfactant, a separate pressure-sensitive copying material according to the invention, preferably a sulphate-containing surfactant, for example a lauryl sulfate salt, or a sulphonate-containing surfactant, for example a sulphonated ricinoleic acid derivative, dodecylbenzene sulphonate or dibutyl ester or dioctyl sulphosuccinate.

The present invention also provides a process for the production of the above-described separate pressure-sensitive copying material, wherein the sheet material, such as paper, is coated with a coating composition containing mineral coloring particles of the developing material and a microcapsule enclosing a color-reactive color-reactive solution. a coloring agent comprising: contacting the colorant of the colorant and, optionally, the microcapsules, with a preservative to prevent premature color development from a group comprising a self-crosslinkable polymer, for example, a self-crosslinkable agent; wet anionic surfactant, fluorine-containing paper sizing agent, non-crosslinkable wet strength agent such as polyethyleneimine resin, The composition is effective to reduce the mutual attraction between the microcapsules and the color developing material particles.

In the process according to the invention, an aminoplast polymer, for example a urea-formaldehyde or melamine-formaldehyde polymer, is preferably used as the self-crosslinkable polymer.

The epichlorohydrin polymer _and, for example, an aminoepichlorohydrin polymer or an amide-aminoepichlorohydrin copolymer can also be advantageously used as a self-crosslinkable polymer in the process of the invention.

In the process according to the invention can be co I _w surfactant used advantageously sulfate-containing surface active agent, e.g. laurylsíranovou salt or sulphonate-containing surfactant such as sulfonated ricinoleic acid derivative, or salt dodecylbenzensulfonátovou dibutyl or dioctyl sulfosuccinic acid.

It is an advantage of the invention that in a separate pressure-sensitive copying system, a colorless color former is not prematurely produced, and thus not destroyed, during its manufacture.

The mineral color developing material particles are preferably of acidic clay, for example of clay found in Japan, known to the skilled person as Japanese acidic clay.

The mineral color developing material particles can be treated with the preservative by simply mixing the suspension of the material with the preservative.

The preservative may be a self-crosslinking polymer, in which case it is preferable to heat the mixture of the polymer obtained with the color developing material before mixing it with the microcapsules.

It is also advantageous to treat the color developing material and the microcapsules before mixing them together. However, in the absence of premature development of the colorless coloring agent immediately upon mixing of the microcapsules with the color developing material, it is possible to add the preservative after mixing them.

The term "self-crosslinkable polymer" encompasses not only polymers with a large number of repeating structural units, but also so-called prepolymers or precondensates having only a limited small number of these repeating structural units.

The self-crosslinkable polymer may be a resin or a precondensate that is used in the paper industry to wet-wet paper tissue. Examples of such resins are epichlorohydrins and aminoplast resins or precondensates. Examples of suitable epichlorohydrins are polyaminoepichlorohydrin resins and polyamidopolyaminoepichlorohydrin resins.

Examples of suitable aminoplasts are melamine-formaldehyde resins or precondensates or urea-formaldehyde resins or precondensates thereof. It has been found that melamine-formaldehyde resins are most effective against premature development of the color former.

When the preservative is a self-crosslinkable polymer, the method of treating the color of the developing material depends on the nature of the polymer. Choosing the appropriate treatment conditions for this polymer is not a problem for the person skilled in the art,

In the case of a coloring material based on acid clay, a melamine-formaldehyde resin having a reactive resin content of 1000% and a dry matter content of 93% and a methylated modified melamine pre-condensate containing a reactive resin content of 80 o / _o and a dry matter content of 69 ° / o. solution of said resin or said precondensate (the weight of resin or precondensate is 10% by weight of the acid clay dry weight) for 2 hours at 90 ° C. In the case of polyaminoepichlorohydrin resins and the color of the acidic clay-based developing material, the treatment is preferably done by mixing the clay with an aqueous resin solution (resin weight is 10% by weight of clay dry weight) and stirring for several minutes at pH 8 or 7. not necessary here.

Also, the microcapsules may optionally be treated with a self-crosslinkable polymer, preferably a crosslinkable polymer, which is used to treat the color developing material.

A non-crosslinkable wet strength agent such as polyethyleneimine resins can also be used as a preservative.

Other materials which can be used as a preservative are anionic surfactants, in particular anionic surfactants, in particular anionic surfactants which contain a sulfate or sulfate group. An example of a sulfate-containing anionic surfactant is a lauryl sulfate salt such as sodium lauryl sulfate.

Sulfate-containing anionic surfactants include dodecylbenzene sulfate salts, dibutyl sulfosuccinate, dioctyl sulfosuccinate, and sulfonated ricinoleic acid derivatives.

An example of anionic surfactants which are preferred as a preservative but which do not contain a sulphate or sulphonate group is ethylenediaminetetraacetic acid.

Other plasticizers which are anionic surfactants, such as dibutyl phthalate, di-2-ethylhexyl adipate and dibutyl maleate, are also effective as preservatives. The disadvantage of these substances, however, is that they cause oil spots on the coated sheet, and therefore the use of these substances is assumed only in extreme cases when other types of protective equipment are not available and high demands are not placed on the quality of the obtained copy.

Another class of materials that can be used as a preservative are fluoride-containing paper sizing agents which are intended to render the paper hydrophobic.

Mixtures of preservatives may also be used. In some cases, the use of such a mixture of preservatives offers some advantages over the use of a single type of preservative. For example, mixtures of fluorine-containing sizing agents and a self-crosslinkable polymer have better protective properties than sizing or self-crosslinkable polymers alone.

The amount of preservative depends on the nature of the microcapsules used and the color of the developing material used. The optimum amount of the composition is readily determined by one skilled in the art. The following examples can be used as a guide.

Preferably, the microcapsules for use in a separate pressure-sensitive copy material must have thicker walls, i.e., these walls must be stronger than the walls of the microcapsules used in the copier system used hitherto.

Although it is preferable to use microcapsules with walls stronger than those of the microcapsules previously used in a separate copier system, it has been found that even when using previously used microcapsules with relatively less rigid walls, a reduction in the premature development of a colorless colorant is achieved. the particles of the color of the developing material are treated with a self-crosslinkable polymer prior to mixing with the suspension of said micro-capsules. However, the coating composition thus obtained is relatively fairly colored despite this reduction, so that the process can be used in the absence of high demands on the copies obtained.

Microcapsules suitable for use in the stand-alone copying material of the invention may have walls of synthetic material such as melamine-formaldehyde resin, urea-formaldehyde resin, and a copolymer of acrylamide and acrylic acid. Other synthetic materials that can be used as the microcapsulated wall materials are polyacrylates, polyurethanes, polyureas, or amnoplasts.

The microcapsules may also have walls of coacervated hydrophilic colloids, for example a mixture of gelatin, acacia or carboxymethylcellulose and copolymers of polyvinyl methyl ether and maleic anhydride.

In order to obtain sufficient strength of the microcapsule walls, a lower weight ratio of the colorless coloring agent solution to the aqueous solution of the microcapsule wall material must be chosen in their manufacture.

When using microcapsules customary in prior art copying systems, the use of a preservative according to the present invention results in less bluing of the sheet than when no preservative is present, but the degree of blueing is still too high to be acceptable to produce quality copies. .

Cases with synthetic walls, for example of aminoplasts, are stronger and less <

soluble than coacervate type gelatin shells. Thus, synthetic capsules exhibit less premature bluing than coacervate type gelatin capsules. However, it has been found that it is desirable not to protect the sleeves with synthetic walls even if the difference in whiteness between the protected and unprotected copy paper is small. Even small differences in whiteness are easily observed, and even a small decrease in whiteness of copy sheets can greatly affect the commercial acceptability of these sheets.

Not all protective devices of the aforementioned types are suitable for all types of cases. For example, anionic surfactants leach the contents of the microcapsules with the walls of the gelatin of the coacervate type, but are, on the contrary, useful in the case with aminoplastic synthetic walls. However, the choice of preservative for a given type of microcapsule is not a problem for the person skilled in the art.

Also, some materials that seemed to be suitable for use as preservatives are in fact inappropriate. The cationic and nonionic surfactants, which would be expected to have the same effect as the anionic surfactants, act as a poison for the color developing material, i.e., limit its ability to develop a colorless coloring agent. The retention enhancers used in paper making, which in some respects are chemically similar to the wet strength enhancers, also appear to be useful as preservatives, but have been found in practice to flocculate the coating compositions. However, methods are known to overcome these problems.

The invention is not limited to the use of certain coloring agents or certain solvents for coloring agents. Examples of coloring agents that can be used are phthalide derivatives, such as crystal violet lactone, fluorane derivatives, diphenylamine derivatives, spiropyran derivatives, phthalimidine derivatives, and benzoyl leuco derivatives of various dyes.

Examples of such usable solvents are mixtures of partially hydrogenated terphenyls, chlorinated paraffins, biphenyl derivatives, diarylmethane derivatives, alkylnaphthalenes, mixtures of dibenzylbenzenes, phthalate esters, phosphoric acid esters or linear alkylbenzenes of 10 to 14 carbon atoms. These solvents may be used in admixture with a diluent such as kerosene.

If both the microcapsules and the color of the developing material need to be treated, then the conditioning conditions of the OD1 depend on the nature of the microcapsules and the color of the developing material. Choosing the treatment conditions does not present a problem for the person skilled in the art. The specific examples given in the examples below can be used as a guide.

The coating composition may also contain a filler to improve the theological properties of the coating composition and to increase the whiteness of the coated sheet. Suitable fillers include kaolin and calcium carbonate. It is known that said fillers sometimes have a weak color developing effect. However, this effect is not strong enough to cause disturbance; otherwise, the filler may be treated with a preservative used to treat the color of the developing material. For example, the conditions for treating kaolin would be almost the same as those for treating the acid color of the developing clay.

Therefore, some attention must be paid to choosing a suitable binder for the coating composition. Some binders that are commonly used in prior art copier systems may have a color developing effect or other undesirable properties and are therefore not suitable for use in the standalone copier system of the invention. For example, a starch binder may reduce the reactivity of the color of the developing material, since the film forms the color of the developing material on the surface of the particles. On the contrary, it has been found that highly hydrolyzed polyvinyl alcohol is particularly suitable as a binder for the coating composition of the copier system of the invention.

The coating composition of the invention may also contain a dispersing agent, preferably a dispersing agent, which also serves to adjust the pH of the coating composition. Such dispersing agents are well known and exemplified are sodium silicate and sodium hydroxide, which also serve, as mentioned above, to adjust the pH. The optimum pH is preferably adjusted to be most suitable for developing a colorless coloring agent. For example, if the coloring agent is crystal violet lactone and the acid clay is a color developing material, then a suitable pH of the coating composition is a pH of about 10.

The coating composition may also include means for protecting the sleeves from premature breakage during storage and shipping of the coated paper web. The use of such protective means, often known as reinforcing material, is well known in pressure-sensitive copying papers.

Two examples of suitable reinforcing materials are fibrous cellulose flakes and wheat starch grains.

Typical dry basis weight is from 10 to 15 g / m ² .

In the manufacture of a separate pressure-sensitive copying material, conventional coating methods are used, such as ruler coating, air-wipe coating, or roller coating. Until now, it has not been possible to apply coating compositions containing only microcapsules by means of a ruler under operating conditions, since it is generally not possible to apply a low basis weight coating. The method according to the invention allows this application because the coating containing both the micro-casing and the color developing material may have a higher basis weight, since in this case only a single coating is applied instead of two previously applied coatings. material. The possibility of this application significantly speeds up production.

The mechanism, as a protective agent, prevents premature development of the color-forming component in the coating composition for the separate copying material of the invention is not entirely known. It is believed that the protective agent causes a reduction in the mutual attraction of the color of the developer material and the microcapsules.

In the following, the invention will be described with reference to the accompanying drawing, in which Fig. 1 is an enlarged sectional view of a sheet of separate pressure-sensitive copying material, and Fig. 2 is a block diagram illustrating an exemplary method of manufacturing the material of Figs.

1.

It can be seen from FIG. 1 that the pressure-sensitive copying material itself comprises a paper backing 1 carrying a layer 2 comprising the microcapsules 3 and particles 4 of the color of the developing material. The remaining components of the layer are not shown in FIG. One such component is a preservative, but it is not known exactly where it is stored.

It can be seen from Fig. 2 that the color developing material particles 4, the microcapsule suspension 5, the fillers 13 and the mixture 14 comprising the binder, the dispersant and the pH adjusting agent are mixed to form the coating mixture 6.

Prior to mixing, the ink-developing material and optionally the microcapsules 3 and / or the filler 13 are treated with a preservative. If desired, the filler 13 may be mixed with the colorant 4 of the developer material prior to treatment with the preservative.

In Figure 2, these optional alternatives are shown in dashed lines. The laminate 6 is then coated with a paper backing in the lamination stage 7. The material obtained is then dried in the drying stage 8 to form a separate pressure-sensitive copying material 9.

The invention will be further elucidated by the following examples.

Example 1 aj Preparation of microcapsules

382 g of a 9.1% gelatin solution at pH 6.4 are placed in a Varing mixer. At the low speed of the mixer, 274 g of the internal phase, the material to be encapsulated, is added. The inner phase is a mixture of (9: 1) linear alkylbenzenes of 10 to 14 carbon atoms and a phthalate material containing

1.8% crystal violet lactone and 1.4% benzoylleukomethylene blue. Allow the mixer to run until a droplet size of less than 3 microns is reached.

g of 17.6% aqueous gum arabic solution and 422 g of deionized water are then added to 218 g of gelatin-internal phase emulsion solution. The pH of the mixture is adjusted to

8.7 g of potassium hydroxide and slowly add 8 g of a 5% aqueous solution of polyvinylmethyl ether and maleic anhydride. Then, 14.7 percent acetic acid is added to lower the pH to 4.3, eliminating coacervate that clumps around the internal phase droplets. The emulsion is then cooled to 10 ° C, then was added 3.3 ml of 50 ° / ₀ of glutaraldehyde for crosslinking of the coacervate.

An additional 10 g of a 5% aqueous solution of polyvinylmethyl ether and maleic anhydride was added to prevent agglomeration of the microcapsules. 6 g of a 12.5% aqueous sodium carbonate solution are then added as a buffer. The pH is then raised very slowly to 10 with sodium hydroxide.

bj Preparation of the coating composition and coating of the acidic color of the developing clay is dispersed in water up to about 36% of the dry matter content of the composition. 3 g of methylated modified melamine pre-condensate are then added as a preservative. The resulting suspension was heated to 90 ° C with stirring and held at that temperature for 2 hours and then cooled.

g of kaolin is dispersed in a sufficient quantity of water to obtain approximately 36% solids content of the mixture. To the mixture was added 1 g of methylated melaminoformaldehydového precondensate modified with a reactive resin content of 80 O / _o and 69% solids as a preservative and the suspension was heated to 90 ° C and maintained at this temperature for 2 hours and then cooled.

The treated clay and kaolin are treated in this way and the pH of the mixture is adjusted to 10 with sodium hydroxide solution.

132 ml of the microcapsule suspension prepared as described above is then added to the clay suspension, and 30 g of a 10% polyvinyl alcohol binder are added. The resulting mixture was then coated in a strength of 9 g / m ² paper with a basis weight of 49 g / m ² using a laboratory ovrstvovacího machine and, after drying, the paper is tested for whiteness using opacimeter (e.g. opacimeter by Bausch & Lomb as described in the disclosure of U.S. Patent No. 1950,975). The test involves measuring the reflectance of the sheet and comparing the obtained value with that of the standard white surface (powdered magnesium oxide surface). The result is expressed as:

____ layered sheet reflectance x 100_ standard white surface reflectance.

The higher the value obtained, the whiter the surface of the coated sheet.

The test is carried out at several different points in the sheet and the average is then calculated. A difference of only a few percent may seem insignificant, but such a difference is readily detectable by the eye and can greatly affect the marketability of the coated material produced.

An average of 93% was obtained and the leaf appeared white. When an ordinary sheet of paper was placed on such a laminated sheet and described, a clear blue copy of the written text was formed on the coated sheet.

In order to demonstrate the effect of the melamine-formaldehyde precondensate, a similar experiment was carried out in which neither the acid color developing clay nor the kaolin were treated with the melamine-formaldehyde precondensate.

g of an acidic color of developing clay and 10 g of kaolin are dispersed in a sufficient quantity of water to obtain about 40% solids content of the mixture. The pH of the mixture was then adjusted to 10 with sodium hydroxide solution.

132 ml of the microcapsule suspension prepared as described above are added together with 30 g of a 100% polyvinyl alcohol binder. The resulting mixture was bluish and when applied to the paper at a coating weight of 9 g / m ² , the sheet was pale blue and had an average reflectance of 81%. Example 2

In this example, different self-crosslinkable polymers are used as a preservative.

³ g of polyaminoepichlorohydrin resin are dissolved in 60 g of water. 30 g of an acidic color of developing clay and 10 g of kaolin are dispersed in this solution. 2 g of 1% dispersing agent are added to the mixture to prevent flocculation. The pH is slowly adjusted to 10 by the addition of sodium hydroxide solution.

132 ml of the microcapsule suspension prepared as described in Example 1 are then added, followed by 30 g of a 10% polyvinyl alcohol binder.

The resulting color of the blend was slightly pale blue and when the paper was coated with this blend with a basis weight of 8 g / m ² , a pale blue sheet with a reflectivity of 87% was obtained. This resulted in an improvement over the untreated acidic color of the developing clay which, as shown in Example 1, gave a reflectance of 81%.

In a repeated process using another colorless coloring agent solution, the acid-treated clay sheet had an average reflectance of 88%.

When an ordinary sheet of paper was placed on two coated sheets produced by the above-described finishing procedures and handwritten, a clear blue copy of the written text was formed on both coated sheets.

Example 3

a) Preparation of microcapsules

First they mix:

aj 19 g cationic urea-formaldehyde resin with a reactive resin content of 45% and a dry matter content of 35%;

bj 42 g of a 20% acrylamide-acrylic acid copolymer solution having a viscosity average molecular weight of 40,000 and an acrylic acid content;

cj 200 g deionized water.

The mixture was then heated to 55 ° C and held at that temperature for 45 minutes. Then 12 g of methylated modified melamine pre-condensate is added and the pH is lowered to 4.4 by addition of acetic acid.

89 g of the coloring agent solution are then added to the mixture and the dispersion thus formed is ground to 4-5 microns. 20 g of deionized water are added and the mixture is stirred for one hour at 35 ° C and then for a further 2 hours at 55 ^° C, then allowed to cool overnight and cool to ambient temperature. The following morning the pH was raised to 10 by adding 1θο / _ο sodium hydroxide solution. The dry matter content of the resulting microcapsule suspension is 30 o / o and the phase ratio, i.e. the ratio of the weight of the colorless coloring agent solution to the mass of the microcapsule wall material is 3.4: 1.

bj Preparation of the coating composition and coating g of the acidic color of the developing clay is dispersed in a sufficient amount of water to produce a 40% dry matter content of the composition, and then 1.5 g of methylated modified melamine pre-condensate is added as a preservative.

The mixture was then heated to 90 ° C, maintained at this temperature for 2 hours, and then allowed to cool. The pH of the mixture was adjusted to 10 with sodium silicate.

ml of microcapsule suspension (dry mass of the microcapsule is 5.5 g) is then mixed with 0.55 g of methylated modified melamine-formaldehyde resin used as a preservative, then heated to 70 ° C, held at this temperature for 1 hour and then Allow to cool.

The treated color developer clay dispersion and the treated microcapsule suspension are then mixed and 15 ml of a 10% polyvinyl alcohol binder are added under stirring, followed by 15 g of kaolin while stirring. The resulting mixture is then coated with a sheet of paper as described in Examples 1 and 2, except that the basis weight of the layer is 12.5 g / m ² .

The leaf was tested for whiteness and was found to have an average reflectance of 93.5%. When an ordinary sheet of paper was placed on such a layered sheet and handwritten, a clear blue copy of the written text was formed on the coated sheet.

After 10 days, the leaf whiteness measurements were repeated and an average reflectance of 98% was found.

Example 4

a) Preparation of microcapsules

This preparation is carried out as in Example 3, except that 40 g of deionized water and 10 g of methylated modified melamine-formaldehyde precondensate are added after the coloring agent solution has been added and comminuted. The remaining steps were the same as in Example 3. The methylated modified melamine formaldehyde precondensate had a reactive resin content of 80% and a dry matter content of 69%.

b) Preparation of the coating composition and coating of the acidic color of developing clay is dispersed in sufficient water to form a mixture with a 40% solids content and then 2 g of methylated modified melamine pre-condensate with a reactive resin content of 80% means. The mixture was then heated at 90 ° C for 2 hours, then allowed to cool. The pH is then adjusted to 10 with sodium silicate.

g of kaolin is dispersed in sufficient water to form a mixture containing 50% dry matter, and then 1.5 g of methylated modified melamine pre-condensate containing a reactive resin content of 80 o / _o and dry matter of 69% are added as a preservative. The mixture was heated to 90 ° C, maintained at this temperature for 2 hours and allowed to cool.

The treated color clay dispersion and the treated kaolin dispersion are then mixed.

ml of the microcapsule suspension (dry weight equal to 5.8) is then mixed with 0.58 g of methylated modified melamine-formaldehyde precondensate with a reactive resin content of 80% and a solids content of 69% used as preservative and heated to 70 ° C, maintaining at this temperature for 1 hour and allowed to cool. The treated microencapsulated suspension is then added to the treated clay dispersion.

15 ml of a 10% polyvinyl alcohol binder are then added to the mixture with stirring.

The resulting mixture is coated with a sheet of paper as described in the previous examples except that the basis weight of the coating is 14 g / m ² .

The leaf was then tested for brightness, with an average reflectance of 97%. When an ordinary sheet of paper was placed on the coated sheet and handwritten, a clear blue image of the written text was formed on the coated sheet. After 10 days, the leaf whiteness measurement was repeated and the average reflectance was determined to be 96%.

Example 5

The microcapsules used in this example are the same as in Example 4 except that they are not treated with melamine formaldehyde.

g of the acidic color of the developing clay is dispersed in sufficient water to form a mixture with a 40% solids content, and then 1.5 g of a melamine-formaldehyde resin with a reactive resin content of 100% and a solids content of 93% are added as a preservative. The mixture was heated to 90 ^° C, held at that temperature for 2 hours and then allowed to cool. The pH is then adjusted to 10 with sodium silicate.

ml of microcapsule suspension (dry weight of the microcapsules is 5.8 GJ was added and then 15 ml of _100/0 polyvinyl alcohol binder and 15 g of kaolin with mixing.

The resulting mixture is then coated with a sheet of paper as described in the preceding examples, except that the coating weight is 13.6 g / m ² . The leaf was tested for brightness and an average reflectance of 96.5% was found. When an ordinary sheet of paper was placed on such an overlay and handwritten, a clear blue copy of the written text was formed on the overlay.

After 10 days, the whiteness measurements of Ust were repeated, with an average reflectance of 96%.

Example 6

In this example, a microcapsule was used which was prepared as described in Example 4 but was not subsequently treated with melamine formaldehyde.

g of the acidic color of the developing clay is dispersed in sufficient water to form a mixture with a 40% solids content. The pH is then adjusted to 10 with sodium silicate.

The dispersion is then divided into 2 parts, one of which is treated with a methylated modified melamine pre-condensate having a reactive resin content of 80% and a solids content of 69% used as preservative, as described in Example 4.

ml of the microcapsule suspension (dry weight of the microcapsule is 7 g) is added to each part of the clay dispersion, then 15 ml of a 10% polyvinyl alcohol binder are added with stirring. The resulting mixtures, which are both colorless, are then coated with a sheet of paper as described in the preceding examples to obtain a basis weight of 8 g / m @ 2.

The color of the treated clay blend is white and has an average reflectance of 95%, while an untreated clay blend has an average reflectance of 91%.

When ordinary sheets of paper were deposited on both coated ears and handwritten, a clear blue image of the written text was formed on both sheets, but this image was brighter on the clay-treated sheet.

After 10 days, the average reflectance measurements were repeated, with an average reflectance of 85 o / _o for the untreated clay sheet; the clay treated sheet had an average reflectance of 92%.

Example 7

This example illustrates the use of an aminoepichlorohydrin resin as a preservative in place of a melamine-formaldehyde resin or a melamine-formaldehyde precondensate.

The capsules used in this example were prepared as described in Example 4, but the melamine formaldehyde was not treated.

g of the acidic color of the developing clay is dispersed in a sufficient quantity of water containing 1.5 g of the polyaminoepichlorohydrin resin as a preservative to obtain a 30% solids content of the mixture. The mixture was adjusted to pH 8 with sodium hydroxide and stirred at ambient temperature for several minutes.

The pH of the mixture was then adjusted to 10 with sodium hydroxide. 20 ml of microencapsulated suspension (7 g of dry microencapsulated) and 15 ml of 10% polyvinyl alcohol binder were added to the mixture with stirring. The resulting mixture is then coated with a sheet of paper at an applied weight of 8 g / m @ ² . The leaf color was white and an average reflectance of 93 percent was found when the whiteness measurements were taken.

When an ordinary sheet of paper was placed on such a layered sheet and handwritten, a clear blue image of the written text was formed on the coated sheet.

After 10 days, the whiteness measurements were repeated, with an average reflectance of 92.1%.

It should be noted that it is not necessary to heat the polyaminoepichlorohydrin resin as was done with the above-mentioned melamine-formaldehyde resins. In addition, it minimizes the release of formaldehyde fumes.

Example 8

This example illustrates the production of a separate pressure-sensitive copy material by coating on an operational coating device.

a) Preparation of microcapsules

This preparation is carried out at a 2.7: 1 phase ratio as follows.

kg of hot deionized water was mixed with 16.8 kg of acrylamide-acrylic acid copolymer, after which the temperature was raised to 55 ° C.

Then 7.6 kg of urea-formaldehyde resin are added and the mixture is stirred for 40 minutes while maintaining a temperature of 55 ° C. Then 8.9 kg of methylated modified melaxin formaldehyde precondensate with a reactive resin content of 76% and a dry matter content of 71% are added and the pH is adjusted to 4.4 with acetic acid. Then add

36.4 kg of the colorless coloring agent solution and the dispersion thus formed are milled to a droplet size of 4-5 microns. The pH of the mixture was then adjusted to 4 with acetic acid and the mixture was heated to 55 ° C and maintained at this temperature for 3 hours. The pH of the mixture was then raised to 10 and the mixture was stirred overnight.

The dry matter content of the resulting microencapsulated emulsion is 29.5%.

b) Preparation of the coating composition and coating

100 l of water is added to the galatite cauldron and 50 kg of acidic color of the developing clay is dispersed in this water. Then 5 kg of methylated modified melamine pre-condensate having a reactive resin content of 80% and a solids content of 69% as preservative are added and the mixture is maintained at a temperature above 90 ° C for 2 hours with stirring. The mixture is then transferred to a rod mill and the process is repeated with an additional 50 kg of acidic developing clay.

100 kg of kaolin are treated as described for the acidic color of the developing clay, and the resulting mixture is also transferred to said bar mill.

13 kg of 50% sodium silicate are then added and the resulting clay suspension is transferred to a stock vat.

11 kg of polyvinyl alcohol binder are added to 136 liters of water in a galatite boiler. The water is then heated to 90 ° C to dissolve the polyvinyl alcohol, and the solution is then transferred to another bar mill.

liters (47 kg dry matter of microcapsules) of the microcapsule suspension, prepared as described in (a) above, is then added to the galatite boiler. Then, 4.7 kg of methylated modified melamine-formaldehyde precondensate with a reactive resin content of 80 percent and a solids content of 69 o / o as preservative are added and the mixture is heated at 70 ° C for 1 hour with stirring. This mixture is added to the polyvinyl alcohol binder in a rod mill. After stirring, the resulting mixture was added to a clay slurry in a stock vat.

After overnight storage, several papers are coated with this blend using an air-wiper coating machine to obtain different basis weights of the deposited coating. The results obtained for the mean reflectance measurements are summarized in Table 1.

TABLE 1

Area weight (g / m ² ) 17

Mean reflectance (° / o) 95.9

When an ordinary sheet of paper was placed on the coated sheet and described, a clear blue image of the written text was formed on the coated sheet.

After 10 days, a sample with a basis weight of 14 g / m &lt; ² &gt; was repeated to measure the whiteness of the leaf, with an average reflectance of 94%.

After 14 months measurements of the whiteness of the sheet with a basis weight of 14 g / m ² were repeated and the average reflectance was determined

93.4%.

Example 9

It explains the production of a separate pressure-sensitive copy material by coating on an operational coating device using a self-crosslinkable polymer other than that used in the previous example.

a) Preparation of microcapsules

The microcapsules used in this example were prepared as described in Example 8.

b) Preparation of the coating composition and coating of kg of polyaminoepichlorohydrin resin used as preservative and 50 kg of dispersant were dissolved in 210 liters of water in a rod mill. 75 kg of acidic color of developing clay and 25 kg of kaolin are then dispersed in this water. The pH of the mixture was slowly adjusted to 10 with 1% sodium hydroxide solution.

178 kg (55 kg of microencapsulated dry matter) of the microencapsulation suspension prepared as described in (a) above are then added to the clay and kaolin slurry. 30 kg of styrene-butadiene latex binder (15 kg dry matter) are then added and after mixing the mixture is transferred to a stock vat.

The paper is mixed with several papers using a windscreen wiper 20

17 16.7 8.3 96.2 97 96.4 16.7 96.9 14 95.3 14.7 96.7 what; results obtained in Table 2. are summarized in our TABLE 2 Surface weight of coating (g / m ² ) 5 4 6 Average reflectance (%) 96 96 97

When a plain sheet of paper was placed on the coated sheet and described, a clear blue image of the written text was formed on the coated sheet.

After 12 days, the whiteness measurements of the sheet with a coating weight of 6 g / m ^{2 were} repeated, with an average reflectance of 95%.

After 10 weeks, the whiteness measurements of the sheet with a coating weight of 6 g / m ² were repeated and an average reflectance of 96% was found.

EXAMPLE 10 g of an acidic color of developing clay and 3 g of kaolin are dispersed in 20 ml of water and one of the preservatives listed in Table 3 is added in each case. The pH of the mixture is adjusted slowly to 10 with sodium hydroxide solution. Was added 38 ml (17% solids) slurry of microcapsules (prepared as described in Example 1 was also added 1% polyvinyl alcohol binder (10 gj. The resulting mixture was then coated paper sheet when reaching the surface weight of the applied layer of 10 g / m ² The basis weight of the paper sheet is 49 g / m ² .

After drying, the reflectance is measured at various points in the sheet using an opacimeter, as described above, and the average reflectance value is calculated. The results obtained, together with the results of a control experiment in which no preservative was used, are shown in Table 3 below.

TABLE 3 Protective equipment Quantity of preservative based on clay weight (%) Average reflectance (%) initial after 10 days None (counter) 84.5 81.8 Polyaminoepichlorohydrin resin 10 87.8 85.1 Polyethyleneimine resin 10 91.3 90.7 Fluorine containing paper sizing agent 10 91.2 89.7 Dibutyl sulfoate amber 10 89.4 83.5 Self-crosslinkable polymer 5 88.8 84.2 Fluorine containing paper sizing agent 0.5 88.8 84.2

Each coated laminate sheet was placed under an ordinary sheet of paper, which was then described. In all cases, a clear blue image of the written Wxt was created on the coated sheet.

Example 11

a) Preparation of microcapsules g of acrylamide-acrylic acid copolymers are added to 170 g of deionized water and the mixture is heated to 55 ° C. 19 g of resin are added and the mixture is held at 55 ° C for 40 minutes. Then 105 g of deionized water and 179 g of a colorless coloring agent solution are added. The resulting mixture was ground to a droplet size of 4-5 microns and cooled to 15 ° C. 40 g of methylated modified melamine pre-condensate having a reactive resin content of 76% and a dry matter content of 71% and 125 g of deionized water are then added and the pH of the dispersion is adjusted to 4.15 with acetic acid. The temperature was maintained at 15 ^° C for 1 hour and then raised to 55 ° C and maintained at that temperature for an additional hour. Finally, the pH is raised to a value

8.5 with sodium hydroxide solution,

b) Preparation of the coating composition and coating

22.5 g of acidic color of developing clay and 7.5 g of kaolin are dispersed in 40 ml of water and one of the preservatives listed in Table 4 is added to this dispersion. The pH of the mixture is adjusted slowly to 10 with sodium hydroxide solution. Then 65 ml of microcapsule suspension with 30% solids content is added. Next, 225 g of wheat starch granules are added to protect the microcapsules against premature breaking along with 15 g of styrene-butadiene binder. The resulting mixture is coated with a paper sheet to achieve a basis weight of 10 g / m ² ; the paper sheet has a basis weight of 49 g / m ² .

After drying (at 105 ° C for 20 seconds), the reflectance of the sheet was measured with an opacimeter at different locations in the sheet and the average reflectance was calculated. The results obtained, together with the results of a control experiment in which no preservative was used, are given in Table 4 below.

TABLE 4

Protective equipment Quantity of preservative based on clay weight (%) Average reflectance (%) initial after 10 days None (check) 0 93.2 92.6 Polyaminoepichlorohydrin resin 10 95 93.9 Sulfonated acid derivative ricinolejové 10 95.1 94.1 Self-crosslinkable polymer 5 94.7 93.3 Fluorine containing paper sizing agent 0.5 Polyethylene emulsion (10%) dry polyethylene) 95.1 93.9

Each of the treated coated laminate sheets was placed under an ordinary sheet of paper, which was then described. A clear blue image of the written text was created on all coated sheets.

Example 12

Example 11 was repeated using several anionic surfactants as a preservative. For comparison, a test with a polyaminoeplchlorohydrin resin and a sulphonated ricinoleic acid derivative as well as a control experiment in which no preservative was used were also repeated. The results obtained are shown in Table 5 below.

TABLE 5

Protective equipment Quantity of preservative based on clay weight (%) Average reflectance (° / o) initial after 10 days None (check) 0 93.3 92.1 Polyaminoepichlorohydrin resin 10 95.3 94.5 Sulphonated ricinoleic acid derivative 10 95 94.5 Sodium dodecylbenzenesulfonic acid 10 95.1 94.4 Ethylenediaminetetraacetic acid 10 93.9 94.3 Dibutyl ester of sulfo- amber 10 95.9 95.3 Sulfo- acid dioctyl ester amber 10 95.1 94.5 Sodium lauryl sulphate 10 95.3 94.7

Each of the treated coated laminate sheets was placed under a plain sheet of paper, which was then described. A clear blue image of the written text was formed on all the coated sheets.

Example 13

22.5 g of the acidic color of the developing material and 7.5 g of kaolin are dispersed in water and one of the preservatives listed in Table 6 is added to the dispersion thus obtained. Slowly adjust the pH of the dispersion to 10 with sodium hydroxide solution. Then, 65 ml of microcapsule suspension with a dry matter content of 30% (prepared in the same manner as in Example 11j) was added. 22.5 g of wheat starch in grains and 15 g of styrene-butadiene latex binder were added to the mixture. to achieve a basis weight of 10 g / m ² , the paper had a basis weight of 49 g / m ² .

After the sheet is dried, the reflectance is measured at various points in the sheet using an opacimeter and the average reflectance is calculated. The results obtained, together with the results of the control experiment in which no preservative was used, are summarized in Table 6 below.

TABLE 6

Preservative Amount of preservative - Average reflectance (° / o) of the center relative to the initial weight after 10 days (%)

None (check) 0 95.2 94.3 Polyaminoepichlorohydrin resin 10 96.3 95.8 Polyamidopolyamlnoepichlor- hydrin resin 10 95.9 94.9 Self-crosslinkable polymer 10 95.9 95.1 Self-crosslinkable polymer 15 Dec 95.9 95.2 Self-crosslinkable polymer 5 95.7 94.9 Fluorine containing paper sizing agent 0.5 Sulfonated acid derivative ricinolejové 10 96.1 95.3 Self-crosslinkable polymer 3 Fluorine containing paper sizing agent 0.3 95.9 95.4

Sulphonated ricinoleic acid derivative 3

Each of the treated coated laminate sheets was placed under a plain sheet of paper, which was then described.

A clear blue image of the written text was created on all sheets.

Example 14

In this example, microcapsules prepared according to German Patent Specification No. 2,529,427 were used.

22.5 g of acidic color of developing clay, 7.5 g of kaolin, one of the preservatives listed in the following Table 7 and 40 g of water are mixed and the pH of the resulting mixture is adjusted to 10 with sodium hydroxide solution. 50 g of the microencapsulated suspension with 40% solids content are then added, then added

22.5 g of wheat starch and 15 g of styrene-butadiene latex binder. The resulting mixture is coated with a paper of 49 g / m ² to achieve a coating weight of 10 g / m ² ; the deposited layer is dried at 105 ° C for 20 seconds.

The results obtained are shown in Table 7 below together with the results of a control experiment in which no preservative was used.

Protective equipment

None

Polyaminoepichlorohydrin resin

Polyethyleneimine resin Fluor containing paper sizing

Sulphonated ricinoleic acid derivative

Sodium lauryl sulphate

Sodium salt of secondary alkyl sulphate

Mixture of sodium alkyl benzene sulphonate, sodium ethoxysulphate alcohol and non-ionic alcohol ethoxylate

TABLE 7

Quantity of preservative based on clay weight (%) Average reflectance (%) initial after 10 days 0 76.4 64.3 10 90 85.9 10 84.8 81.8 10 85.7 79.5 10 85.7 79.9 10 87 72.3 10 86.4 78 10 85.8 73

Each of the treated coated laminate sheets was placed under a plain sheet of paper, which was then described. A clear blue image of the written text was created on all sheets.

by preparing a 65 ml microcapsule suspension as in Example 11, which was used instead of the microcapsule suspension used in Example 14. The results obtained are shown in Table 8 below.

Example 15

The procedure of Example 14 was repeated except that

TABLE 8 Protective equipment Quantity of preservative based on clay weight (%) Average reflectance (% j initial after 10 days None (control) Polyaminoepichlorohydrin 0 94.9 94.3 resin Sulfonated acid derivative 10 95.4 95 ricinoíejové Secondary sodium 10 96.1 95.6 alkyl sulfate Secondary alkyl- sodium salt 10 96.2 95.5 of sulfate with 17 carbon atoms 10 96.5 95.8

Each of the treated coated laminate sheets was placed under a plain sheet of paper, which was then described.

A clear blue copy of the written text was made on all sheets.

Example 16

In this exemplary embodiment, the separate pressure-sensitive copying material is manufactured using an operational coating device.

Microcapsules were prepared as described in Example 11, but higher amounts of individual components were used and the mixture was maintained at 55 ° C overnight after cooling to 15 ° C.

22.5 kg of polyaminoepichlorohydrin resin and 296 liters of water are mixed in a propeller whisker, then 225 kg of acidic color of developing clay is dispersed in the resulting mixture.

The pH of the mixture was then raised to 8 by adding 13.7 g of 47% sodium hydroxide solution. 500 kg (139 kg of dry matter) of the microcapsule suspension are then added, then 225 kg of wheat starch and 75 kg of kaolin are dispersed in the resulting mixture and 150 kg of styrene-butadiene latex binder (75 kg of dry matter) are added. The resulting mixture is coated with a base paper having a basis weight of 47 g / m ² to achieve a basis weight of 14 g / m ² .

The mean reflectance of the coated sheet was determined immediately after curing

96.1%, 96% after 10 days and 94.5% after seven months.

When an ordinary sheet of paper was applied to the coated sheet and described, a blue image of the written text was formed on the coated sheet.

Example 17

This example illustrates the use of the method according to the invention for the known type of microcapsules. As mentioned previously, the use of these micro-capsules does not lead to an acceptably bright sheet. However, the results obtained with the method of the invention show that the method provides increased resistance to premature development of a colorless coloring agent at any wall thickness of the used micro-capsules.

The microcapsules used in this example were made as described in the description of the invention (Example 1) of British Patent Specification No. 1,053,935, except that carboxymethylcellulose was used instead of gum arabic. The microcapsule suspension was divided into 3 doses, one dose

a), dose b] and dose cj.

A batch of a methylated modified melamine precondensate solution containing a reactive resin content of 80% and a solids content of 69% used as preservative at 60 ° C for 30 minutes was then allowed to cool.

g of the acidic color of developing clay is dispersed in sufficient water to form a mixture with a 40% solids content, then the pH of the mixture is adjusted to 10 with sodium silicate.

To this mixture was added 100 ml of the microcapsule suspension with stirring and the resulting mixture was coated with a sheet of paper. A dark blue leaf with an average reflectance of 19% is obtained. Batch (b)

The microcapsule suspension is adjusted as in a).

g of the acidic color of the developing clay is dispersed in sufficient water to form a mixture with a 40% solids content. To the dispersion obtained 4 g of methylated modified melamine precondensate having a reactive resin content of 80% and a solids content of 69% used as preservative are added and the mixture is heated to boiling point and then allowed to cool. The pH is then adjusted to 10 with sodium silicate.

10 ml of the microcapsule suspension are then added to the mixture with stirring and the resulting mixture is coated with a sheet of paper as described above. The paper was again blue and had an average reflectance of 30%, which is a better result than the 19% determined for the sheet coated with the unprotected mixture. Batch c)

The microcapsule suspension in this case was not pretreated.

g of polyaminoepichlorohydrin resin used as preservative are added to 60 g of water. 40 g of an acidic color of developing clay is dispersed in this solution to form a mixture with a 40% solids content. The pH of the mixture was adjusted with stirring for several minutes with sodium hydroxide solution.

100 ml of the microcapsule suspension are then added with stirring and the resulting mixture is coated with a sheet of paper as described above. The leaf was again blue and was estimated to have an average reflectance of 39% by calculating the average of the reflectance measured at various points in the leaf. This value is also better than the average reflectance value determined for a leaf that has been coated with a mixture that has not been treated with a preservative (19%).

Adjust the microcapsule suspension to 13%

Claims (8)

SUBJECT A separate pressure-sensitive copying material comprising a sheet material overlaid with mineral color developing material particles and a microcapsule enclosing a colorless coloring agent solution that is reactive with the color developing material to form a color product, characterized in that the microcapsules and the color developing material are contained in The layer also comprises a means for preventing premature color development from the group comprising a self-crosslinkable polymer, for example a self-crosslinkable wet strength agent, anionic surfactant, a fluorine-containing paper sizing agent, a non-crosslinkable wet strength agent , for example, a polyethyleneimine resin, and a substance which is effective to reduce the mutual attraction between the microcapsule and the color developing material particles. Separate copying material according to claim 1, characterized in that it comprises an aminoplast polymer, for example a urea-formaldehyde or melamine-formaldehyde polymer, as a self-crosslinkable polymer. 3. A separate copying material according to claim 1, wherein the self-crosslinkable polymer comprises an epichlorohydrin polymer, for example an aminoepichlorohydrin polymer or an amide-aminoepichlorohydrin copolymer. 4. A separate copying material as claimed in claim 1, wherein the surfactant is a sulfate-containing surfactant, e.g., a lauryl sulfate salt, or a sulfonate containing a surfactant, e.g. acid. 5. A process for producing a separate pressure-sensitive copier of the invention according to items 1 to 4, wherein the sheet material, such as paper, is coated with a coating composition comprising mineral color developing material and a microcapsule enclosing a solution of a colorless coloring agent reactive with a color developing material to form a color product, characterized in that the particles of the color developing material and optionally also the microcapsules are contacted with a protective agent for preventing premature color development from the group comprising a self-crosslinkable polymer, for example a self-crosslinkable wet strength a surfactant, a fluorine-containing paper sizing agent, a non-crosslinkable wet strength agent, such as a polyethyleneimine resin, and a substance that is effective to reduce mutual attraction between the microcapsules and the particles of the color developing material. 6. Process according to claim 5, characterized in that an aminoplast polymer, for example urea-formaldehyde or melamine-formaldehyde polymer, is used as the self-crosslinkable polymer. 7. A process according to claim 5, wherein the self-crosslinkable polymer is an epic-chlorohydrin polymer, for example an amino-epichlorohydrin polymer or an amide-amino epichlorohydrin copolymer. 8. The method of claim 5, wherein the surfactant is a sulfate-containing surfactant, e.g., a lauryl sulfate salt, or a sulfonate containing a surfactant, e.g., a sulfonated ricinoleic acid derivative, dodecylbenzenesulfonate salt or dibutyl ester or dioctyl sulfosuccinate.