JPH04328175A - Developing ink and developing sheet - Google Patents

Abstract

PURPOSE:To obtain developing ink containing a developer, oil capsule having specific particle diameter and ink medium as basic components and capable of providing pressure sensitive duplicating paper having good coloring property in printing, extremely reduced in lowering of initial coloring property with lapse of time. CONSTITUTION:The objective ink containing (A) electron acceptable developer such as acidic clay, phenol resin, polyhydric salt of aromatic carboxylic acid and zinc salt of 2,2-bisphenol sulfonic acid compound, (B) oil capsule having 1-50mum (preferably 2-10mum) average particle diameter and preferably consisting of a melamine-formalin resin film and (C) ink medium as basic components. As an example of the component C, a volatile medium such as ethanol is used in case of evaporation drying type ink and high boiling point medium such as ethylene glycol is used in case of penetration drying type ink.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developer ink for pressure-sensitive copying paper and a developer sheet obtained by printing the ink.

0002

[Prior Art] Electron-donating coloring agents such as crystal violet lactone and benzoylleucomethylene blue;
Pressure-sensitive copying paper that utilizes the principle of color development by reaction with an electron-accepting color developer such as activated clay, phenol resin, or polyvalent metal salt of a salicylic acid derivative is well known.

[0003] In general, such pressure-sensitive copying paper is produced using a phase separation method,
Upper paper with color former-containing microcapsules prepared by interfacial polymerization method, in-situ method, etc. applied to the back side of the support, lower paper with color developer applied to the support, the above microcapsules and color developer. Inner paper sheets coated on different sides of a support are used in appropriate combinations. In addition, there are also so-called single-piece pressure-sensitive copying papers in which the above-mentioned microcapsules and color developer are coated as a laminated or mixed layer on the same side of a support, and furthermore, a capsule layer is provided on the back side of the single-piece pressure-sensitive copying paper. There are several types of paper, and these are used in combination with the above-mentioned top paper, middle paper, and bottom paper as appropriate.

Normally, the color developing layer of such pressure-sensitive copying paper is formed by applying an aqueous coating liquid to a support using a large coating machine (hereinafter referred to as the coating method). As a manufacturing method, there is a method (hereinafter referred to as a printing method) in which a non-aqueous ink is applied to a support using a printing machine.

[0005] Since the printing method allows the developer layer to be provided only in the areas where color development is desired, products with a small printing area can be produced at low cost, or can be used by printing on areas where color development is not desired on fully coated products. It has the advantage that there is no need for desensitizing ink. However, although the printing method is a production method that has merits as described above, it is still difficult to say that the quality of pressure-sensitive copying paper is sufficient. That is, color-developing sheets obtained by printing methods generally tend to have poorer color development properties than those obtained by coating methods, and in particular, there are problems such as a noticeable decrease in initial color development properties over time.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to obtain a pressure-sensitive copying paper which is printed with developing color ink and has good color development properties, and which exhibits extremely little deterioration in initial color development properties over time. As a result of repeated studies, the inventors of the present invention discovered that by including oil capsules with an average particle size of 1 to 50 μm in the developing ink, it is possible to obtain pressure-sensitive copying paper of high quality, which had not been possible until now. Finally, the present invention was completed.

[0007]

[Means for Solving the Problems] The present invention is a color developing ink characterized by containing a color developer, an oil capsule having an average particle size of 1 to 50 μm, and an ink medium as basic components. Furthermore, the present invention is a color developer sheet obtained by printing the color developer ink.

[0008]

[Function] The color developer used in the color developer ink of the present invention can include one of two components that react to develop color, but most commonly an electron-accepting color developer is mentioned. . Examples of electron-accepting color developers include clays such as acid clay and activated clay, phenol resins, and Japanese Patent Publication No. 51-25
polyvalent metal salts of various aromatic carboxylic acids described in No. 174;
Examples include materials known in the art, such as the zinc salt of 2,2-bisphenolsulfone compound described in JP-A-54-106316.

Oils used as the core material of the oil capsule of the present invention include, for example, vegetable oils such as cottonseed oil; mineral oils such as kerosene, paraffin, naphthenic oil, and chlorinated paraffin; alkylated biphenyls, alkylated terphenyls, Aromatic hydrocarbons such as alkylated naphthalene, diarylethane, triarylmethane, diphenylalkane; dimethyl phthalate, diethyl phthalate, di-n-butyl phthalate, dioctyl phthalate,
Materials known in the art include esters such as diethyl adipate, propyl adipate, di-n-butyl adipate, dioctyl adipate, and mixtures thereof.

As the encapsulation method, well-known coacervation method, interfacial polymerization method, in-situ method, etc. can be selected and used as appropriate, but among them, melamine-formalin resin film obtained by in-situ method is used. Capsules are particularly preferred because they have excellent solvent resistance. As the oil capsule of the present invention, those having an average particle diameter in the range of 1 to 50 μm are effective, and among them, those having an average particle diameter in the range of 2 to 10 μm are particularly preferable in terms of effectiveness. Incidentally, if a material with a diameter of less than 1 μm is used, the effect of improving color development will be extremely small, whereas if a material with a diameter of more than 50 μm is used, the transfer efficiency of the capsule from the plate to the paper will decrease, and the effect of improving color development will be inferior. The capsules are destroyed by the printing pressure during printing, and as the oil evaporates, the color development tends to decrease over time. Incidentally, an antioxidant and an ultraviolet absorber can be contained in the capsule as necessary. The capsules obtained by the above method are usually aqueous capsule dispersions, which can be dried through air drying, surface drying, fluidized drying, flash drying,
It is usually dispersed in a dry state into an ink medium by processing such as spray drying, vacuum drying, freeze drying, infrared drying, high frequency drying, ultrasonic drying, pulverization drying, etc.

[0011] The ink medium used in the color developing ink of the present invention includes various media known in the ink industry.
For example, in the case of evaporative drying ink, a volatile medium, in the case of penetration drying ink, a high boiling point medium, in the case of hot melt ink, waxes, and in the case of ultraviolet curing ink, a vinyl group or vinylidene in the molecule. In the case of compounds having one or more groups and oxidative polymerization type inks, oils are used.

Volatile media used in evaporative drying inks include benzene, toluene, xylene, cyclohexane, hexane, ligroin, methyl isobutyl ketone, methyl acetate, ethyl acetate, butyl acetate, methyl cellosolve, ethyl cellosolve, methanol, ethanol, n
-propyl alcohol, isopropyl alcohol, n-
Examples include butanol, and ethanol is particularly preferred from the viewpoint of odor during printing.

[0013] Examples of the high boiling point medium used in the penetrating drying type ink include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, 2,3-butylene glycol, methyl cellosolve, cellosolve, and butyl cellosolve. , carbitol, butyl carbitol, and the like.

[0014] Both evaporative drying type and permeation drying type inks are not strictly classified, and a volatile medium and a high boiling point medium may be used together. When volatile or high boiling media are used, resins are usually used to fix the developer and oil capsules to the support. The amount of this additive is usually set so that the surface strength of the printed area is at a level that does not set off and form an image on the capsule side when printing, but generally speaking, it is per 100 parts by weight of color developer. Te5~5
It is added in an amount of 0 parts by weight.

Examples of the resin include gum rosin, wood rosin, shellac, ester gum, pentaerythritol ester of rosin, pentaerythritol ester of polymerized rosin, maleic acid resin, pentaerythritol ester of maleated rosin, dimerized rosin, and rosin-modified phenol resin. , butanol-modified urea resin, butanol-modified melamine resin, terpene resin, terpene phenol resin, soybean oil-modified alkyd resin, polyamide resin, polyvinyl acetate, acrylic resin, vinyl chloride, vinyl chloride
Vinyl acetate copolymer, ethylene-maleic anhydride copolymer, styrene-maleic anhydride copolymer, methyl vinyl ether-maleic anhydride copolymer, isobutylene-maleic anhydride copolymer, modified polyvinyl alcohol, polyvinyl butyral, Examples include polyvinylpyrrolidone, ethylcellulose, nitrocellulose, hydroxypropylcellulose, cellulose acetate propionate, cellulose acetate butyrate, and the like.

Examples of waxes used as a medium for hot melt ink include beeswax, spermaceti, lanolin, candelilla wax, carnauba wax, wood wax, rice wax, montan wax, ozokerite, paraffin wax, and microcrystalline wax. , montan wax derivatives, paraffin wax derivatives, microcrystalline wax derivatives, castor wax, opal wax, low molecular weight polyethylene,
Examples include distearyl ketone, caprylic acid amide, stearic acid amide, ethylene bisstearic acid amide, stearic acid, behenic acid, stearyl alcohol, and distearyl phosphate ester, which may be used alone or in combination. An aromatic hydrocarbon compound, a resin, etc. can be added to the waxes as necessary.

Examples of oils used as a medium for the oxidative polymerization type ink include vegetable oils such as linseed oil, safflower oil, soybean oil, and castor oil; dehydrated castor oil, polymerized oil, maleated oil, vinyl oil, and urethane oil. Processing oil; machine oil, etc.
Examples include mineral oil such as spindle oil. In the case of oxidative polymerization type ink, in addition to the above-mentioned oils, a solvent, wax, dryer, thickener, gelling agent, thixotropy agent, etc. are added as necessary.

Examples of compounds having one or more vinyl groups or vinylidene groups in the molecule used as a medium for ultraviolet curable inks include acryloyl groups, methacryloyl groups, allyl groups, unsaturated polyesters, vinyloxy, and acrylamide groups. Examples include reaction products of polyols, polyamines, amino alcohols, etc., and unsaturated carboxylic acids, and reaction products of acrylates or methacrylates having hydroxyl groups and polyisocyanates. Typical compounds include, for example, polyethylene glycol diacrylate, propylene glycol dimethacrylate, pentaerythritol triacrylate,
Trimethylolpropane diacrylate, trimethylolpropane triacrylate, pentaerythritol tetraacrylate, hexanediol diacrylate,
1,2-butanediol diacrylate, reaction product of epoxy resin and acrylic acid, reaction product of pentaerythritol and methacrylic acid, acrylic acid, reaction product of diethylene glycol and maleic acid, acrylic acid, methyl methacrylate, butyl methacrylate, Examples include styrene.

When using the above compound, it is necessary to add a photopolymerization initiator and, if necessary, a sensitizer. Examples of the photopolymerization initiator include benzoquinone, phenanthrenequinone, naphthoquinone, diisopropylphenanthrenequinone, benzoisobutyl ether, benzoin, Freinbutyl ether, Michler's ketone, Michler's thioketone, fluorenone, trinitrofluorenone, and β-benzoylaminonaphthalene. Examples include aromatic ketones, quinone compounds, ether compounds, and nitro compounds. Examples of the sensitizer include triethanolamine, N-methyldiethanolamine, N,N-dimethylethanolamine, and N-methylmorpholine. Incidentally, the above-mentioned volatile medium and high boiling point medium can be added to this ink within a range that does not cause curing failure upon irradiation with ultraviolet rays.

The contents of the color developer, oil capsules and ink medium in the color developer ink are usually 5 to 95 parts by weight of the color developer and 1 to 50 parts of the oil capsule per 100 parts by weight of the ink.
The ink medium is adjusted to a range of 20 to 90 parts by weight. The evaporative drying type ink, penetrating drying type ink, hot melt ink, ultraviolet curing ink, and oxidation polymerization type ink of the present invention may further include stilt materials such as cellulose powder and starch particles, silica, calcium carbonate, hydroxide, etc. White pigments such as aluminum, zinc oxide, titanium oxide, and melamine resin particles, ultraviolet absorbers, antioxidants, optical brighteners, colorants, and the like can be added.

The addition and mixing of the above-mentioned materials to the ink medium is usually carried out by methods known in the art, such as a stirrer, ball mill, sand grinder, roll mill, etc. The prepared color developing ink can be used in various printing methods such as flexo, letterpress, offset, gravure, and screen with a dry weight of 1.
It is applied in a range of 10 g/m2, preferably 2 to 6 g/m2.

The color developing ink of the present invention can be applied to the base paper surface of normal paper, the coated or uncoated surface of coated paper such as art paper, coated paper, lightly coated paper, high quality paper, synthetic paper, film, etc. printed.

The sheet obtained by printing is used in appropriate combination with general-purpose pressure-sensitive copying paper such as top paper, middle paper, and bottom paper. In addition, the color developing sheet obtained by the present invention is most effective when used in combination with a smear sheet of capsule ink containing a color former, which generally tends to have inferior color development compared to coated products. Become.

[0024]

[Examples] In order to make the effects of the present invention even clearer, Examples and Comparative Examples are given below, but the present invention is not limited to these Examples. In addition, unless otherwise specified, parts and % in the examples represent parts by weight and % by weight, respectively.

Example 1 (Preparation of oil capsule) Ethylene-maleic anhydride copolymer (trade name: EMA-31,
After emulsifying 100 parts of alkyldiphenylethane as an internal phase oil into 200 parts of a 3% aqueous solution (manufactured by Monsanto), the system was heated to 55°C. Separately, 15 parts of melamine was added to 45 parts of a 37% formaldehyde aqueous solution and reacted at 60° C. for 15 minutes to prepare a prepolymer aqueous solution. This prepolymer aqueous solution was dropped into the emulsion, and while stirring, 0.1N hydrochloric acid was added dropwise to adjust the pH to 5.3.
The system was heated to 80°C and stirred for 1 hour, followed by 0.2N
of hydrochloric acid was added dropwise to lower the pH to 3.5, and after further stirring for 3 hours, the mixture was cooled to obtain a dispersion of capsules with an average particle size of 8.0 μm. Subsequently, the oil capsule dispersion was filtered and dried to obtain powdered oil capsules.

(Preparation of color developing ink) To 100 parts of ethyl acetate, 30 parts of zinc 3,5-di(t-butyl)salicylate, 8 parts of the above powdered oil capsule, 2 parts of pulp powder, and styrene-methacrylic acid ester were added. Polymer hollow particles (manufactured by Dainippon Ink and Chemicals, trade name VONCOAT, PT-
207-S) and 3 parts of nitrified cotton (manufactured by Daicel Chemical Industries, Ltd., trade name SS 1/8) were added and mixed to obtain a color developing ink.

(Preparation of inner paper) The above developer ink was flexographically printed on the back side of N-40KS Copy Bright top paper (manufactured by Kanzaki Paper Industries) so that the dry weight was 2.0 g/m2 to create inner paper. did.

(Evaluation) Two months after preparation, two sheets of this inner paper were overlapped and printed using a typewriter, and printing with extremely excellent initial color development was obtained.

Comparative Example 1 A developing ink was prepared in the same manner as in Example 1, except that 8 parts of powdered oil capsules were not added, and an inner paper was prepared in the same manner.

(Evaluation) Two months after preparation, two sheets of this inner paper were overlapped and printed using a typewriter, and a print with considerably poor initial color development was obtained.

Example 2 An inner paper was prepared in the same manner as in Example 1 except that the average particle diameter of the oil capsules was changed to 2.5 μm. Two months after the preparation, two sheets of this inner paper were overlapped and printed using a typewriter, and a print with extremely excellent initial color development was obtained.

Example 3 An inner paper was prepared in the same manner as in Example 1 except that the average particle diameter of the oil capsules was changed to 21 μm. Two months after the preparation, two sheets of this inner paper were overlapped and printed using a typewriter. Although slightly inferior to Example 1, a print with good initial color development was obtained.

Example 4 An inner paper was prepared in the same manner as in Example 1 except that the average particle diameter of the oil capsules was changed to 1.5 μm. Two months after the preparation, two sheets of this inner paper were overlapped and printed using a typewriter. Although slightly inferior to Example 1, a print with good initial color development was obtained.

Comparative Example 2 An inner paper was prepared in the same manner as in Example 1 except that the average particle diameter of the oil capsules was changed to 60 μm. Two months after the preparation, two sheets of this inner paper were stacked together and printed using a typewriter, resulting in a print with considerably poor initial color development.

Comparative Example 3 An inner paper was prepared in the same manner as in Example 1 except that the average particle diameter of the oil capsules was changed to 0.7 μm. Two months after the preparation, two sheets of this inner paper were stacked together and printed using a typewriter, resulting in a print with considerably poor initial color development.

Example 5 (Preparation of capsule ink) 3,3-bis(2-methyl-
The internal phase oil obtained by heating and dissolving 25 parts of 1-octyl-3-indolyl) phthalide in 75 parts of benzyltoluene was adjusted to pH
After emulsifying in 200 parts of a 3% aqueous solution of EMA-31 adjusted to 6.0, the system was heated to 55°C. Separately, 37
15 parts of melamine was added to 45 parts of % formaldehyde aqueous solution and reacted at 60° C. for 15 minutes to prepare a prepolymer aqueous solution. This prepolymer aqueous solution was dropped into the emulsion, and while stirring, 0.1N hydrochloric acid was added dropwise to adjust the pH.
After setting the pH to 5.3, the system was heated to 80°C and stirred for 1 hour, then 0.2N hydrochloric acid was added dropwise to lower the pH to 3.5, and after further stirring for 3 hours, it was cooled. A dispersion of capsules having an average particle diameter of 4.0 μm was obtained. Next, this dispersion was filtered and dried to form powder capsules, and then 100 parts of these capsules were dispersed in 300 parts of ethanol, and an ultraviolet curable resin containing a photopolymerization initiator (trade name: Grandik, Dainippon Co., Ltd. Capsule ink was prepared by adding and mixing 100 parts (manufactured by Ink Co., Ltd.) and 20 parts of cellulose powder.

(Preparation of inner paper) Developing ink obtained in the same manner as in Example 1 was applied to a 40 g/m2 base paper with a dry weight of 2.
．． 0g/m2, and then print the above capsule ink on the back side (dry weight 3.0g/m2).
m2), and the ink was cured using an ultraviolet irradiation device to create inner paper.

(Evaluation) Two months after preparation, two sheets of this inner paper were overlapped and printed using a typewriter, and printing with excellent initial color development was obtained.

Comparative Example 4 An inner sheet was obtained in the same manner as in Example 2, except that the ink of Comparative Example 1 was used as the developing ink.

(Evaluation) Two months after the preparation, two sheets of this inner paper were overlapped and printed using a typewriter, and a print with extremely poor initial color development was obtained.

[0041]

[Effects of the Invention] The color developer sheet obtained using the color developer ink of the present invention had excellent initial color development.

Claims (2)

[Claims] 1. A color developing ink comprising a color developer, an oil capsule having an average particle size of 1 to 50 μm, and an ink medium as basic components. 2. A color developer sheet obtained by printing the color developer ink according to claim 1.