JPH07137438A - No-carbon pressure-sensitive copying paper - Google Patents

Abstract

PURPOSE:To provide no-carbon pressure-sensitive copying paper excellent in color developability by a method wherein color-developing ink is locally applied on a support. CONSTITUTION:No-carbon pressure-sensitive copying paper is obtained by locally printing with electron acceptable color-developer-containing developing ink on pigment coated layer, which does not substantially develop coloring image through the reaction with electron donating developer, provided on support. The preferable pigment employed in the pigment coated layer is a basic pigment having the weighted means of the absorption of oil in the whole pigment measured by JIS K 5101 of 30ml/100g or more.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to carbonless pressure sensitive copying paper. Furthermore, the present invention relates to a carbon-free pressure-sensitive copying paper in which a color-developing ink containing an electron-accepting color developer is partially provided on a support by printing.

[0002]

2. Description of the Related Art An electron-donating color former which is an electron-donating colorless or light-colored dye precursor (hereinafter referred to as a color former) and an electron-accepting developer which is an electron-accepting solid acid (hereinafter It has been known for a long time that a color image can be obtained by a contact reaction with a color developer. Examples of utilizing this phenomenon include carbonless pressure-sensitive copying paper (eg, US Pat. Nos. 2,505,470 and 2,505,489).
And thermal recording paper (eg, Japanese Patent Publication No. 45-14039).

Generally, as a developer for carbonless pressure-sensitive copying paper, activated clay, acid clay, attapulgite,
Inorganic developers such as zeolite, bentonite, silica and aluminum silicate, organic developers such as novolac phenolic resins, salicylic acid derivatives, and polyvalent metal salts of salicylic acid derivatives are known. In particular, a polyvalent metal salt of a salicylic acid derivative has good coloring properties and is widely used in the market. In recent years, many salicylic acid resins or their polyvalent resins have been developed for the purpose of improving the conventional phenolic resin-based color developer, which has a slow color development speed, and the salicylic acid-based color developer, which has slightly poor water resistance. Metal salts have been proposed as developers.

As a salicylic acid resin-based developer, a polyvalent metal salt of salicylic acid and a co-condensation resin such as α, α'-dialkoxy-p-xylene (JP-A-62-176875,
62-178387, 62-178388, 63-53092, 63-159082, 63.
-160877) and polyvalent metal salts of resins obtained by reacting a styrene derivative with a salicylic acid derivative (JP-A-63-186729, JP-A-1-133).
780), a polyvalent metal salt of a resin obtained by reacting a salicylic acid derivative with a benzyl derivative such as benzyl alcohol, benzyl ether and benzyl halide (JP-A-63-254124, 63-289017, 6).
4-56724, 64-77575, JP-A-4-
No. 89274, etc.), salicylic acid-modified terpene phenol resin polyvalent metal salts (JP-A No. 63-147682), and the like are known.

In general, as a carbon-free pressure-sensitive copying paper, a color former layer containing microcapsules containing a color former is provided on a support, and a color developer layer containing a color developer is provided on the support. Lower paper, or a separate type that uses a combination of middle paper with a developer layer and a color developer layer on the front and back sides of the support, and supports the developer and color developer in one or multiple layers. A self-type on one side of the body is used.

The lower and middle papers generally used have a developer layer provided on the entire surface of the support, and therefore, a portion of the desensitizing ink used for the purpose of preventing color development is formed in a portion where copy color development is not desired. Printing is performed, but the desensitizing effect is insufficient because the amount of desensitizing ink is too small, or the amount of desensitizing ink is too large to dry well, and the desensitizing ink is transferred to areas other than the desensitized printing area. However, there was a problem in that it caused defective coloring. For this reason, on the surface of the plain paper or the upper paper opposite to the coating layer containing the microcapsules, the color-developing ink containing the color-developing agent is partially printed only on the portion requiring the color development for copying, and the lower paper or the medium It has been conventionally used as a sheet.

[0007] As the color-developing ink which has been put into practical use, there is an ink corresponding to a printing method such as letterpress printing, offset printing, flexo printing or silk screen printing, and also an ultraviolet curable ink for speeding up the drying property. Developed and put to practical use. For these,
35487, 54-9085, 60-2546.
No. 7, No. 61-46320, No. 60-54197,
60-54198, 61-26595, 61
-50110, Japanese Patent Publication No. 1-51350, JP-A-52
-141705, 52-147107, 58-
126184, 58-181685, 59-1
No. 31676, No. 63-154391 and the like.

[0008] Conventionally, flexographic printing using a volatile organic solvent has been widely used. However, due to the risk of fire and environmental problems caused by handling the organic solvent, use of color-developing ink for letterpress or offset printing. Is increasing. However, the printed matter of these color-developing inks has a serious problem that it is difficult to obtain the density of the color-developed image as compared with the lower and middle papers coated with the color-developing agent. As a method for improving the color developability of the color developing ink, JP-A-4-288285 is known.
No. 4,298,384, No. 4-298385, No. 4-320879, No. 4-320880 and the like, various additives to the color developing ink are disclosed in JP-A-4-3.
Japanese Patent No. 28175 discloses a method of adding microcapsules containing oil in a color-developing ink, but it has not yet been able to obtain a sufficient color developability.

There is also a method of using an upper paper or a medium paper coated with more microcapsules than usual for the purpose of improving the color developability, but the color former contained in the microcapsules is an expensive material. Yes, and very uneconomical, it was not a practical method.

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a partial color-forming type carbonless pressure-sensitive copying paper having a sufficient color forming property by partially printing a color-developing ink on a support. To do.

[0011]

Means for Solving the Problems As a result of intensive studies for solving the above problems, the present inventors have found that a developer containing an electron-accepting developer that produces a color image by reaction with an electron-donating color developer. In a carbonless pressure-sensitive copying paper in which a color ink is partially provided on a support by printing, a pigment that does not substantially form a colored image due to a reaction with a color-forming agent on the surface on which the color-developing ink is printed as a support. It has been found that the above object can be solved by using a support provided with a coating layer.

Particularly, a basic pigment typified by light calcium carbonate is used as the pigment of the pigment coating layer, and the JI of the entire pigment is
The weighted average value of oil absorption by S ・ K5101 is 30ml /
More preferable results were obtained when the amount was 100 g or more.

A detailed description will be given below of means for solving the problems. As the pigment for the pigment coating layer coated on the support of the present invention, pigments generally used for aqueous coating can be used, but basic pigments are preferably used.

Examples of the basic pigment include calcium oxide, calcium hydroxide, calcium carbonate, calcium metasilicate, magnesium oxide, magnesium hydroxide, magnesium carbonate, aluminum hydroxide and aluminum silicate. Among these, light calcium carbonate is most preferable because it has a uniform particle shape, contains few impurities, is inexpensive, and can be easily obtained with a relatively large oil absorption amount.

As the light calcium carbonate, particles in the form of horns, columns, needles, spindles, spheres, rice grains, etc., or worm-like particles formed by three-dimensionally intertwining them regularly or irregularly, There are aggregated particles such as sea urchin particles, and as the crystal system, there are aragonite system, calcite system, vaterite system and the like, and any of them can be used.

Since the pigment showing acidity reacts with the color-forming agent to form a color-developed image, a color-developed image is generated even in a portion where the color-developing ink is not printed. Therefore, when using an acidic pigment, it is necessary to eliminate its color developability,
Neutral p that can be erased by a compound with weak desensitizing effect
It is preferable to use an acidic pigment close to H. In this case, it can be used by mixing a compound having a desensitizing effect with a coating liquid and applying the mixture.

Pigments that can be used in addition to the above basic pigments include inorganic pigments such as kaolin, calcium sulfate, zinc oxide, zinc hydroxide and titanium oxide, and organic pigments such as urea-formaldehyde resin and melamine-formaldehyde resin. Is mentioned. These basic and acidic pigments can be used alone or in combination of two or more.

For the purpose of increasing the color developability of the printed portion of the color-developed ink, it is preferable to use a pigment having a large oil absorption property, and the weighted average value of the oil absorption amount according to JIS K5101 of the entire pigment is 30 ml / 100 g or more. Preferably there is. There is no particular upper limit to the weighted average value of the oil absorption of the pigment, but most of the pigments generally used for aqueous coating generally have an oil absorption of 80 ml / 100 g or less.

As the adhesive used for the pigment coating layer, those which have hitherto been known can be used. For example, proteins such as casein and gelatin, cellulose derivatives such as carboxymethylcellulose and hydroxymethylcellulose, water-soluble natural polymer compounds such as oxidized starch and esterified starch, and further polyvinyl alcohol, polyacrylic acid, styrene-butadiene latex, polyvinylpyrrolidone Water-soluble synthetic polymer compounds and latexes such as acrylonitrile-butadiene-acrylic acid latex and styrene-maleic anhydride copolymer can be used.

The coating amount per unit area of the pigment coating layer provided on the support is preferably 3 to 15 g / m ² . When the amount is too small, the effect of improving the color developability of the color ink printing portion is small. The greater the coating amount, the greater the effect of improving the color developability, but if it exceeds 15 g / m ² , it will be difficult to obtain further effects. The pigment coating layer is usually applied as a single layer, but it is also possible to provide it as a multilayer having two or more layers.

When forming a pigment coating layer, if necessary, a defoaming agent, a water retention agent, a water resistance agent, a penetrant, a dispersion stabilizer, an ultraviolet absorber, an antioxidant, a fluorescent dye, etc. in the coating liquid. Additives such as lubricants can be added.

The support provided with the pigment coating layer is paper,
Synthetic paper, non-woven fabric, plastic film, etc. are used. On the other surface of the support, the same type or different types of coating layers may or may not be provided. When a coating layer containing microcapsules containing a color former is provided, a colorless ink can be printed to obtain a carbonless pressure-sensitive copying paper that functions as an intermediate paper.

The coating method is not particularly limited, for example, on-machine by various coating methods such as an air knife coater, a blade coater, a roll coater, a rod coater, a gravure coater, a curtain coater and a size press coater. , Can be manufactured by off-machine coat.

The color-developing ink used in the present invention is produced by appropriately mixing an electron-accepting color-developing agent with a solvent for ink, an adhesive for ink, a white pigment, and other additives.

Examples of the electron-accepting color developer include novolac type phenol resin or its polyvalent metal salt, salicylic acid derivative or its polyvalent metal salt, salicylic acid resin or its polyvalent metal salt, and the like.

The novolac type phenol resin is produced by polycondensing various phenol derivatives and a lower aldehyde represented by formaldehyde as raw materials in the presence of an acidic catalyst. At this time, examples of the phenolic raw material used include unsubstituted phenol, alkyl group-substituted phenol (eg, cresol, ethylphenol, butylphenol, octylphenol, nonylphenol, etc.), aralkyl group-substituted phenol (eg, p-benzylphenol, p-cumylphenol, etc.), aryl group-substituted phenol (eg, p-phenylphenol), halogen-substituted phenol (eg, p-chlorophenol), and the like.

The salicylic acid derivative is a compound having at least one aromatic substituent, specifically, 3-phenylsalicylic acid, 5-phenylsalicylic acid, 3-benzylsalicylic acid, 5-benzylsalicylic acid, 3- (α-
Methylbenzyl) salicylic acid, 5- (α-methylbenzyl) salicylic acid, 3- (α, α-dimethylbenzyl) salicylic acid, 5- (α, α-dimethylbenzyl) salicylic acid, 3,5-diphenylsalicylic acid, 3,5- Di (α-
Methylbenzyl) salicylic acid, 3,5-dibenzylsalicylic acid, 3,5-di (α, α-dimethylbenzyl) salicylic acid, 3,5-di (4-methylbenzyl) salicylic acid and the like can be mentioned.

As the salicylic acid resin or the polyvalent metal salt thereof, all of the above-mentioned compounds can be used, but as an example, the above salicylic acid derivative and styrene, o. m. p-
Styrene derivatives such as methyl styrene, α-methyl styrene and β-methyl styrene at a molar ratio of 1: 0.5 to 10,
The salicylic acid resin obtained by the Friedel-Crafts reaction in the presence of a strong acid catalyst is a polyvalent metal chloride. The types of polyvalent metals include Ca, Mg, Al, Zn, and Mn.
Etc., but most preferably used as a zinc salt. These color developers may be used in combination of two or more kinds.

As the ink solvent, in the case of non-evaporative drying type ink such as permeation drying or oxidative polymerization, for example,
Examples include high boiling point petroleum solvents having a boiling point of 200 ° C. or higher, higher fatty acid esters, higher alcohols, glycol solvents, linseed oil, tung oil, soybean oil, etc., and their compatibility with color developers, suitability for printing machines, etc. Selected in consideration. In the case of the evaporative drying type, water, methanol, ethanol, n-propyl alcohol, isopropyl alcohol, methyl cellosolve,
Ethyl cellosolve, methyl acetate, ethyl acetate, butyl acetate, methyl isobutyl ketone, cyclohexane, toluene, xylene, hexane, ligroin and the like are used.

In the case of the photo-curable color developing ink, a (meth) acrylate type monomer is used, and for example, lauryl (meth) acrylate, 2-ethylhexyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate. Monofunctional monomers such as, diethylene glycol di (meth) acrylate, bifunctional monomers such as tricyclodecane dimethanol (meth) acrylate, polyfunctional such as trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate Examples include monomers. Further, in order to make skin irritation lower than that of a simple polyol (meth) acrylate, it can be used in the form of a polyether polyol having an alkylene oxide added thereto or a polyester polyol modified with a polybasic acid carboxylic acid.

Examples of the adhesive resin for ink include rosin-modified phenol resin, rosin-modified maleic acid resin,
Examples thereof include petroleum resins, hydrogenated petroleum resins, polyamide resins, butanol-modified amino resins and the like. In the case of photocurable color developing ink, (meth) acrylic acid ester of polyhydric alcohol, epoxy (meth) acrylate, rosin-modified epoxy (meth) acrylate, polyester (meth) acrylate, polyurethane (meth) acrylate, polyether Examples thereof include (meth) acrylate prepolymers such as (meth) acrylate and alkyd (meth) acrylate.

Examples of the pigment for ink include titanium oxide, calcium carbonate, aluminum hydroxide, alumina white, barium sulfate, zinc oxide, kaolin, activated clay and the like, and the content thereof is 0 to 50% by weight in the ink. %,
It is preferably used in an amount of 5 to 30% by weight.

Further, in the color-developing ink, dispersants, waxes, oils, adhesive resins, synthetic resins for improving offset printing suitability, ultraviolet absorbers, antioxidants, fluorescent dyes, starches, dextrins. An anti-setoff agent such as the above, a drying accelerator and the like may be appropriately used.

When the color developing ink is a photo-curable type, a proper amount of a polymerization inhibitor can be added. Further, examples of the photopolymerization initiator added to cause photocuring during printing include acetophenone-based, benzoin-based, anthraquinone-based, oxime-based, xanthone-based, thioxanthone-based, and the like.

The color-developing ink is printed by various printing methods such as flexography, gravure, letterpress, offset and screen. The dry amount of the color-developed ink applied to the support by printing is 0.5 to 10 g / m ² , preferably 1 to 4 g / m ² .

As the color-forming agent used for developing the color of the color-developed ink, a conventionally known general dye for carbonless pressure-sensitive copying paper (electron-donating color-forming agent) can be used. A color former for OCR whose color image has absorption in the near infrared region can also be used.

These color formers can be microencapsulated by a generally known method, and examples thereof include a coacervation method, a monomer polymerization method, an interfacial polymerization method and an in situ polymerization method. . As a preferred example, a urea-formaldehyde resin microcapsule disclosed in U.S. Pat.
Examples thereof include methods for producing melamine-formaldehyde resin microcapsules disclosed in JP-A-3-84881, JP-A-54-49984 and the like.

As the non-volatile solvent used in the internal phase of the microcapsules, those used in general pressure-sensitive copying paper can be used, for example, alkylated diphenylmethane,
Diarylalkanes such as alkylated diphenylethane, alkylated diphenylpropane and alkylated diphenylbutane, alkylnaphthalene such as alkylnaphthalene and dialkylnaphthalene, alkylated biphenyl,
Examples thereof include aromatic ester type, aliphatic ester type, paraffin oils such as chlorinated paraffin, n-paraffin, and isoparaffin. These can be used alone or in combination of two or more.

The concentration of the color-developing agent in the internal phase of the microcapsules is generally 2 to 20% by weight, but 3-1.
2% by weight is preferable, and 5 to 10% by weight is particularly preferable.
When the dissolved concentration of the dye is low, many non-volatile solvents are transferred to the developer layer, which causes bleeding of the color image. Further, when the dissolved concentration of the dye is high, the transfer rate of the internal phase of the microcapsule to the developer layer is lowered, and a sufficient color development density cannot be obtained.

The microcapsules include a tilting agent such as wheat starch, corn starch and fine cellulose powder, a water-soluble adhesive, an adhesive such as latex, and, if necessary, a surfactant, a wax, a desensitizer and a desensitizer. A foaming agent, an ultraviolet absorber, a white pigment, etc. are added, and the whole or a part of the support is coated on a support such as acidic paper, synthetic paper, film and the like.

[0041]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.
In addition, (part) in an Example shows a weight part.

Examples 1 to 10 and Comparative Example 1 Using the various pigments shown in Table 1, a pigment coating layer coating solution was prepared with the following composition, and a high-quality paper having a basis weight of 50 g / m ² was prepared. Each support was coated with a blade coater so that the dry coating amount was ² to 10 g / m ^2, and dried to obtain each support having the pigment coating layer of Examples 1 to 10.

[Pigment coating layer coating liquid formulation] Water 200 parts Sodium pyrophosphate 1 part Pigment 100 parts 5% polyvinyl alcohol aqueous solution (Nippon Gosei Kagaku Co., Ltd.)
NH-20) 250 parts The pigment ratio in the pigment coating layer coating liquid formulation is shown in Table 2.

Example 11 and Example 12 Polyethylene glycol nonyl phenyl ether (Nonion NS-2 manufactured by NOF CORPORATION) was added to the coating liquid for the pigment coating layer.
10) 5 parts was added to obtain each support provided with the pigment coating layer of Examples 11 and 12.

Commercially available color-developing inks for letterpress printing (Mitsubishi Paper Mills Co., Ltd., letterpress spot ink MS20) were applied to each of the supports of Examples 1 to 12 and Comparative Example 1 on a high-quality paper without a pigment coating layer.
00) is printed so that the ink amount is about 2 g / m ^2, and commercially available blue carbon-free carbonless pressure-sensitive copying paper (N-40 on Mitsubishi Paper Mills NCR paper) is used. Typewriter printing was performed, and the print density was measured with a color difference meter. The results are shown in Table 2.

[0046]

[Table 1]

[0047]

[Table 2]

The unit of the weighted average oil absorption is ml / 100 g
Is. The smaller the value of the color density, the better the color developability. The evaluation of color development is ⊚: very good, ◯: good, Δ: almost good and practically no problem, and x: poor. In addition, in all cases, there was almost no color development other than the color-developed ink printed portion, and there was no problem in practical use.

Examples 1 to 10 are examples in which a color-developing ink was printed on a support provided with a coating layer using a basic pigment, and good color development was obtained. The heavier the coating layer, the more
It can be seen that the greater the oil absorption of the pigment used, the higher the color developability of the printed part. Examples 11 and 12 are examples in which the acidic pigment is partially used, and compared with the case where only the basic pigment is used,
Although the color developability is slightly low, good color developability is obtained as compared with Comparative Example 1 in which the coating layer is not provided.

[0050]

As is clear from the results shown in Table 2, all of the carbonless pressure-sensitive color developing papers of the present invention have good color forming properties.

Claims (3)

[Claims] 1. A color-developing ink containing an electron-accepting color developer that produces a color image by reaction with an electron-donating color developer.
In a carbon-free pressure-sensitive copying paper partially provided on a support by printing, the support does not substantially form a color image on the surface on which the color-developing ink is printed by reaction with an electron-donating color former. A carbon-free pressure-sensitive copying paper having a pigment coating layer. 2. The carbon-free pressure-sensitive copying paper according to claim 1, wherein the pigment in the pigment coating layer is a basic pigment. 3. JIS K51 for the entire pigment in the pigment coating layer
The weighted average value of oil absorption by 01 is 30ml / 100g
The carbonless pressure-sensitive copying paper according to claim 1 or 2, characterized in that the above is the case.