JPH0358920B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat-melting pressure-sensitive paper ink comprising microcapsules dispersed in a hydrophobic substance having a melting point of 40° C. or higher and which is solid at room temperature.

The conventionally known form of pressure-sensitive copying paper is made by dissolving an electron-donating, colorless substance in nonvolatile oil, etc., and creating microcapsules with the oil containing the coloring substance as a core material. , an upper paper coated on the back side of a support and a lower paper coated on the surface of the support with an electron-accepting colorless substance are placed so that each coated layer faces each other, and the surface of the upper paper is written on. When printing under pressure with a typewriter or the like, a colored image can be obtained on the bottom paper.When making copies of three or more sheets, an electron-accepting color-forming substance,
A large number of copies can be obtained by inserting the required number of inner sheets, each coated with microcapsules containing an electron-donating color-forming substance on the back, between the upper and lower sheets. There is also a so-called self-coloring type pressure-sensitive copying paper in which microcapsules containing an electron-donating color-forming substance and an electron-accepting color-forming substance are coated on the same side of a support.

In the above-mentioned pressure-sensitive copying paper, microcapsules containing an electron-donating color-forming substance and/or an electron-accepting color-forming substance are usually formed by a microencapsulation method in an aqueous medium. It is applied to the entire surface or a part of the support using an air knife coater as an aqueous dispersion containing microcapsules, or sometimes using gravure printing, flexography, etc. as an aqueous or alcohol-based ink containing microcapsules.

On the other hand, hot-melt printing as a heat-melting ink has been studied in recent years and is now being put to practical use.

However, as shown in Japanese Patent Publication No. 48-12255, Japanese Patent Application Laid-Open No. 52-136017, etc., in this hot melt printing, microcapsules are dispersed in wax and used as ink, so microcapsule aqueous dispersion is used. must be dispersed in the wax. For this reason, the disadvantage is that the water contained must be removed by means of spray drying or concentration before dispersion, and many microcapsules are destroyed when the water-free microcapsules are dispersed in wax. It has the disadvantage of being stored away.

In order to improve these drawbacks, the present inventors conducted extensive research and found that color-forming substances that dissolve in water or hydrophilic substances, or color-forming substances themselves, can be used in natural and synthetic waxes, higher alcohols, The color-forming substance is microencapsulated by dispersing and emulsifying it into a melt of a hydrophobic substance made of higher fatty acids that is solid at room temperature and has a melting point of 40°C or higher.By cooling, the color-forming substance is apparently solid at room temperature. A heat-melting type pressure-sensitive paper ink was produced by dispersing microcapsules containing the color-forming substance therein.

The heat-melting pressure-sensitive paper ink of the present invention does not require the removal of water, which has been a disadvantage when microcapsules are dispersed in conventional hydrophobic substances with a melting point of 40°C or higher that are solid at room temperature, such as wax. When the microencapsulation is completed and the ink is cooled to room temperature, an instant melting type pressure-sensitive paper ink is completed and can be used as is as a hot melt ink.

This not only eliminates the process of removing water from the microcapsule-containing aqueous dispersion when dispersing the microcapsules into the wax, but also because the microcapsules themselves are easily destroyed. Reducing the dispersion process would be very advantageous.

Furthermore, the apparently solid heat-melting type pressure-sensitive paper ink containing microcapsules dispersed therein can be sent to a printing shop by simply cutting it into a standard shape and packaging it.

Regarding the heat-melting type pressure-sensitive paper ink of the present invention,
Various systems can be used. Taking a chelate system that causes a color reaction as an example,
A two-sheet type in which an ink containing microcapsulated ligands and an ink containing microcapsulated metal compounds are applied to separate supports, or a so-called self-coloring ink in which both are applied together to a support. A type type, and furthermore, a plain paper transfer type type in which both types are coated together on the back side of a support are also available. It can also be used in the same way for a color reaction between a colorless dye precursor and an organic acid by encapsulating each of them.

If the various types mentioned above are contaminated due to the action of masatsu, etc., existing stilts such as wheat starch can be mixed into the microencapsulation process up to cooling. Alternatively, they may be mixed during hot melt printing.

Next, specific examples of color-forming substances used in the present invention will be given.

Ligands and metal compounds include tannic acid and ammonium metavanadate, tannic acid and ferric alum, stable diazonium salts of naphthol AS caustic soda and 4-benzamide 2,5 diethoxyaniline, phthalonitrile and copper sulfate, respectively. Totokuko Showa 43-
Water-soluble chelate reactants described in Publication No. 23710, etc.:
Any colorless dye precursor may be used as long as it reacts with an organic acid to produce a colored substance; for example, 2
-Chloro-3-methyl-6-diethylaminofluorane, 2-methoxy-6-diethylaminofluorane, 3,6-dimethoxyfluorane, 3,6
-dibenzyloxyfluorane, 2-anilino-
3-Methyl-6-diethylaminofluorane, 2
-Phenyl-6-diethylaminofluorane, 2
-anilino-6-diethylaminofluorane, 3
-xanthenes such as chloro-6-ethylaminofluorane, 3,3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide, 3,3
-bis(p-dimethylaminophenyl)phthalide, 3-(p-dimethylaminophenyl)-3-
Phthalides such as (2-methylindol-3-yl)phthalide, 3-(4-diethylamino-2-
azaphthalide series such as (ethoxyphenyl)-3-(1-ethyl-2-methylindol-3-yl)-4-azaphthalide, thiazine series such as benzoylleucomethylene blue, 3-methyl-spirodinaphthopyran, 3,3 Spiro compounds such as '-dichlorospirodinaphthopyran can be used alone or in combination.

In addition, examples of organic acids include malonic acid, maleic acid,
Succinic acid, oxalic acid, citric acid, glycolic acid,
Organic carboxylic acids such as diglycolic acid and fumaric acid, toluenesulfonic acid, benzenesulfonic acid,
Phenolsulfonic acid, naphthalenesulfonic acid,
Organic sulfonic acids such as polystyrene sulfonic acid can be used alone or in combination.

Specific examples of the hydrophobic substance of the present invention having a solid melting point of 40° C. or higher at room temperature will be given below.

Higher fatty acids include stearic acid, behenic acid, arachidic acid, palmitic acid, etc. Higher alcohols include stearyl alcohol, 1-docosanol, cetyl alcohol, etc. Waxes include beeswax, spermaceti, Chinese wax, lanolin, etc. Animal-based waxes, Candelilla waxes, carnauba waxes, plant-based waxes such as wood wax, rice waxes, and sugarcane waxes, mineral-based waxes such as montan waxes, ozokerite, ceresin, and lignite waxes, paraffin waxes, and micro waxes. Petroleum-based waxes such as crystalline waxes, modified waxes such as montan wax derivatives, paraffin wax derivatives, and microcrystalline wax derivatives, hydrogenated waxes such as Castor wax and opal wax, low molecular weight polyethylene and its derivatives, and Akura waxes. , synthetic waxes such as distearyl ketone, stearamide, behenic acid amide, ethylene bisstearic acid amide, cabronic acid amide, caprylic acid amide, pelargonic acid amide, capric acid amide, lauric acid amide, tridecylic acid amide, myristic acid amide saturated fatty acid amides such as caproleic acid amide, myristoleic acid amide, oleic acid amide, linoleic acid amide, erucic acid amide, ricinoleic acid amide, linoleic acid amide, etc. alone or in combination of two or more types. It can be used as

However, if a hydrophobic substance with a high melting point is used, there will be many disadvantages such as decomposition of the color-forming substance and equipment problems. preferable.

Specific examples of water or hydrophilic substances of the present invention will be given below.
Examples of water or amines include diethylenetriamine, polyethyleneimine, etc., and examples of organic substances with alcoholic hydroxyl groups in the molecule include
Nonionic activators as shown in Publication No. 16324,
That is, polyoxyethylene alkyl ether, polyoxyethylene thioether, polyoxyethylene alkylamine, polyoxyethylene alkyl amide, polyoxyethylene sorbitan fatty acid ester, sorbitan fatty acid ester,
Polyoxyethylene polyoxypropylene, polyethylene glycol fatty acid ester, polyoxyethylene alkyl phenyl ether, polyoxyethylene hydrogenated castor oil derivative, alkyl phosphate ester, alkyl ether phosphate ester, fatty acid ethanolamide, sugar rose ester, pentaerythritol Ester etc., also glycerin, monoacetyl glycol, ethylene glycol, isobutylene glycol, diethylene glycol, polypropylene glycol, polyethylene glycol, 1,2-propanediol, 1,3
-propanediol, furfuryl alcohol,
Examples include 2,5-hexanediol, tetrahydrofurfuryl alcohol, 2-chloro-1,3-propanediol, 2-methyl-2,3-butanediol, and these hydrophilic substances may be used alone or in combination of two or more. Can be used together. It can also be used in combination with water and one or more hydrophilic substances.

The microencapsulation method of the present invention is
446, 771, 2883, 8693, Tokuko Sho 43-17654,
The interfacial polymerization method described in Japanese Patent Publication No. 11772/1977, 20885/1985, etc., and the method of interfacial polymerization described in Japanese Patent Publication No. 44-3495, Japanese Patent Publication No. 45/1973.
-5616, Special Publication Showa 46-30282, Special Publication No. 47-23165, Same
The in situ method described in Japanese Patent No. 47-10780 and the like can be used depending on the characteristics of the core material. In microencapsulation, it is desirable that the color-forming substance be dispersed and emulsified at a temperature higher than the melting point of the hydrophobic substance so that microencapsulation proceeds quickly.

As a method for producing pressure-sensitive paper using the heat-melting pressure-sensitive paper ink of the present invention, the ink can be coated on the entire surface or part of the support using a commonly used hot-melt coater such as a gravure roll coater or a kiss roll coater. There is a way to print.

A liquid property improver can be added to the hot-melt pressure-sensitive paper ink according to the present invention in accordance with various coaters and printing machines. For example, adding stilt to protect the capsule, thickening agent to keep the viscosity constant,
Surfactants to improve dispersibility, mineral oils, vegetable oils, etc. as softeners to control the pressure sensitivity of ink, opacifying agents such as titanium oxide, wax modifiers such as vinyl acetate resin, etc. It is clear that the ink can be melted and mixed at the end of microencapsulation or before coating or printing, but this is not limiting.

Paper is mainly used as the support for forming the coating layer according to the present invention, but various nonwoven fabrics, plastic films, synthetic papers, metal foils, etc., or composite sheets made of a combination of these may also be used.

Hereinafter, the present invention will be specifically explained with reference to Examples. Note that "parts" indicate parts by weight.

Example 1 (1) An ink containing microcapsules containing a metal compound was prepared as follows.

Mix 10 parts of polyamine with 80 parts of a 10% ammonium metavanadate aqueous solution to prepare a uniform aqueous solution and use it as Solution A.

Next, add 150 parts of oxidized wax with a melting point of 70°C.
The mixture is heated to 80°C and melted, and 0.3 parts of sorbitan sesquioleate (trade name: Nikkolso-15, manufactured by Nikko Chemicals Co., Ltd.) is added thereto, mixed well, and this is used as liquid B.

Keep solution B in a water bath at 80℃ and add A while stirring.
After gradually adding the liquid and dispersing, when the emulsified particles have an average size of 7μ, a solution (dissolved at 80℃) of 10 parts of toluylene diisocyanate, which reacts with polyamine, diluted with 20 parts of oxidized wax is added dropwise. I will do it.

After the dropwise addition was completed, stirring was continued to continue the reaction for 2 hours. After the reaction is complete, lower the temperature to room temperature. At this time, it is necessary to stop stirring according to the increase in viscosity due to cooling.

The prepared microcapsules containing an aqueous ammonium metavanadate solution were dispersed in the solid oxide wax.

(2) The oxidized wax ink containing the ammonium metavanadate aqueous solution prepared in (1) above was applied to base paper using a hot melt coater.

(3) Stir and mix 10 parts of tannic acid, which reacts with ammonium metavanadate, in 50 parts of a 10% PVA aqueous solution, and apply it to base paper so that the coated surface faces the ammonium metavanadate coated paper obtained in (2) above. When pressure printing was performed using pen pressure over the paper, a clear black color was obtained.

Example 2 (1) A microcapsule-containing ink containing a coloring agent (colorless dye precursor) was prepared as follows.

Surfactant Span 65 (manufactured by Kao-Atlas)
100 parts of paraffin wax containing 0.5 part and having a melting point of 70°C are heated to 75°C and melted. Separately 10 parts of melamine, 25 parts of 37% formaldehyde aqueous solution
33 parts of water was adjusted to pH 9 with sodium hydroxide, and 60
℃ to form a melamine-formalin initial condensate. 32 parts of a diethylene glycol solution containing 5% 2-anilino-3-methyl-6-diethylaminofluorane dissolved in the prepared melamine-formalin initial condensate is mixed. The melamine-formalin initial condensate ~ diethylene glycol solution is gradually added dropwise to the previously dissolved paraffin wax melt while stirring, and dispersed.
Emulsify. 5% 2-anilino-3- in about 30 minutes
Microcapsules containing a diethylene glycol solution containing methyl-6-diethylaminofluorane are formed. The reaction was continued for an additional 2 hours, and then cooled to room temperature. The viscosity increases during the process and stirring is stopped. A microcapsule ink containing 2-anilino-3-methyl-6-diethylaminofluorane dispersed in paraffin wax was thus obtained.

(2) Apply the ink obtained in (1) above to base paper using a hot melt coater, and apply 2-anilino-3-methyl-
A paper coated with microcapsules containing diethylaminofluorane was prepared.

(3) The following color developer (organic acid) sheet was prepared.

Disperse 100 parts of kaolin in 100 parts of water to which 0.3 parts of sodium pyrophosphate has been added as a dispersant, add 15 parts of SBR latex as an adhesive, and add 100 parts of a 15% malonic acid aqueous solution to this solution to form a coating solution for base paper. was coated with Meyer Bar No. 16 to obtain a developer sheet.

When the color forming agent sheet and the color developer sheet obtained in (2) above were stacked so that the coated surfaces faced each other and pressed using an IBM electric typewriter, a clear black image was obtained on the color developer sheet. Ta.

Example 3 (1) An ink containing microcapsules containing a ligand was prepared as follows.

Mix 10 parts of polyamine with 80 parts of 10% tannic acid aqueous solution to prepare a uniform aqueous solution. Separately, add 150 parts of oxidized wax with a melting point of 70°C to 80°C.
Heat to melt, add 0.5 part of sorbitan sesquioleate as an emulsifier, and mix thoroughly. This adjusted oxidized wax melt was heated to 80°C.
20 parts of oxidized wax at 80°C and toluylene diisocyanate were fixed in a hot water bath, and the tannic acid aqueous solution was gradually added while stirring, and emulsified. When the emulsified particles had an average size of 5 to 7μ, 10 parts of the melt was added dropwise. After the dropwise addition, the mixture was allowed to react for 2 hours with stirring.

After the reaction is completed, the temperature is lowered to room temperature, but stirring is stopped during cooling depending on the increase in viscosity.

(2) The microcapsule ink containing an aqueous solution of ammonium metavanadate, a metal compound that reacts with the tannic acid-containing capsule ink in (1) above, was prepared in the same manner as in Example 1 (1).

(3) Using the above (1) and (2), the following formulation was applied to 40 g/m ² base paper using a hot melt coater.

Microcapsule ink containing tannic acid aqueous solution
50 parts Microcapsule ink containing ammonium metavanadate aqueous solution 50 parts Wheat starch 30 parts Powder 1.3 parts When the coated paper was layered with plain paper and pressure was applied from the non-coated side of the coated paper, the result was clear. I was able to obtain a clear black color on a plain paper surface.

Claims (1)

[Claims] 1. A color-forming substance that is dissolved or dispersed in water or a hydrophilic substance, or a color-forming substance itself that is solid at room temperature and has a melting point of 40, consisting of natural and synthetic waxes, higher alcohols, and higher fatty acids. The color-forming substance is microencapsulated by dispersing and emulsifying it into a molten hydrophobic substance having a temperature of ℃ or higher, and by cooling the color-forming substance-containing microcapsules, which are apparently solid at room temperature, are dispersed. A method for producing a heat-melting pressure-sensitive paper ink. 2. The method for producing a heat-melting pressure-sensitive paper ink according to claim 1, wherein the color-forming substance is selected from the group consisting of a ligand, a metal compound, a colorless dye precursor, and an organic acid. 3. The method for producing a heat-melting type pressure-sensitive paper ink according to claim 1, wherein the water or hydrophilic substance comprises water, amines, or an organic substance having an alcoholic hydroxyl group in the molecule.