JPH029677A - Back carbon copy paper - Google Patents

Abstract

PURPOSE:To prevent the lowering of surface whiteness due to the strike-through of ink by printing the necessary part of paper with non-aqueous ink containing a microcapsule having a colorant encapsulated therein to form a microcapsule- containing layer. CONSTITUTION:A colorant is usually encapsulated in a state dispersed or dissolved in oil and the mean particle size of a microcapsule is usually 0.5-15mum and the compounding amount of the colorant is usually 0.5-50pts.wt. per 100pts. wt. of the core substance of the microcapsule. Non-aqueous microcapsule- containing ink is prepared, for example, by dispersing the microcapsule dispersion prepared in an aqueous system in a non-aqueous solvent as it is but the microcapsule compounding amount of the microcapsule-containing ink is different according to the film quality and particle size of the microcapsule to be used, the kind of an ink medium or the kind and compounding amount of other additive and pref. 30-100pts.wt. per 100pts.wt. of the medium.

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial Application Field" The present invention relates to back carbon copying paper, and particularly to back carbon copying paper that does not have ink bleed through and the coloring of the ink layer is not visible through the surface. It is.

``Prior Art'' Carbon-back copy paper is a type of paper that has a hot-melt or solvent-type colored ink layer made of colorant and wax on the back side of the paper. Colored ink is transferred onto a sheet assembled under carbon copy paper to obtain a copy.

Conventionally, carbon-back paper, which is made of high-quality paper with a layer of ink such as blue partially provided on the back side, has been widely used for department store delivery slips and the like. This carbon-backed copying paper has excellent stability of copied images over time compared to carbonless paper that utilizes the coloring reaction of chromogen substances such as electron-donating color formers and electron-accepting color developers.

However, with conventional carbon-backed copy paper, the colored ink can be seen through the surface. Another disadvantage was that the colored ink oozed out onto the surface (ink bleed-through was a phenomenon).

For this reason, paper is made of paper that has been highly beaten, mixed with a large amount of internally added inorganic pigments such as calcium carbonate and titanium dioxide, and then subjected to surface size press treatment to increase its air permeability and opacity. is used as. However, the effects obtained are not sufficient, and new problems have arisen with the improvements. In other words, paper with pulp that has been subjected to a high beating process is more likely to expand and contract due to absorption and desorption of moisture than -a paper, and because the stiffness (stiffness, Young's modulus) and paper strength of the paper are weak, it is difficult to process the printing process. Troubles are likely to occur during processing and machining processes.

``Problems to be Solved by the Invention'' It is an object of the present invention to solve the above-mentioned problems and to provide a back carbon copying paper which prevents a reduction in surface whiteness due to ink bleed-through and the like.

"Means for Solving the Problems" The present invention is a back carbon copying paper formed by forming a microcapsule-containing layer containing a colorant on a support. This is carbon-back copy paper printed with a non-aqueous ink containing microcapsules to form a microcapsule-containing layer.

"Function" The colorant-containing microcapsules of the present invention have a larger particle size than the colorant contained in conventional back carbon inks, so the microcapsules serve as a support during ink printing or coating. It becomes difficult for the ink to enter the spaces between the pulp fibers of the paper used, and the phenomenon of ink bleeding can be prevented. Furthermore, by including the colorant in the microcapsules, it is possible to suppress the coloring of the ink layer itself, so when viewed from the surface of the Kei Carbon copying paper (the side on which the ink layer is not formed), most of the coloring of the ink layer is suppressed. The impact of this becomes unclear.

In normal applications, the ink layer containing microcapsules should be provided only in the area where information that needs to be copied is written, that is, usually in the necessary area on the support, and the ink layer contains microcapsules containing a non-aqueous medium and a colorant. Back carbon copying paper is manufactured by printing a non-aqueous ink on the required portions of the back surface of the support.

Specifically, methods such as using solvent-based ink, real-melt ink, or ink that is cured by electron beams or ultraviolet rays are used. The reason why non-aqueous inks are preferable is that when aqueous inks or paints are used, the paper shrinks after drying, so that if an ink layer is provided partially, wrinkles tend to occur.

Examples of coloring agents included in the microcapsules include black pigments such as carbon black; red pigments such as monoazo, disazo, rhodamine, perylene, and quinacridone; and blue pigments such as copper phthalocyanine and triallylmethane. Pigments: various pigments such as yellow pigments such as benzidine, monoazo, and disazo; red dyes such as monoazo, disazo, rhodamine, and rose bengal; blue such as disazo and triallylmethane; Systematic dyes: Various dyes such as monoazo-based, disazo-based, yellow-based dyes and the like can be mentioned.

The coloring agent is usually encapsulated in a state dispersed or dissolved in oil, and examples of such oil include the following substances known in the field of pressure-sensitive copying paper.

Aromatic carbonization of vegetable oils such as cottonseed oil, mineral oils such as kerosene, paraffin, naphthenic oil, and chlorinated paraffin, alkylated biphenyls, alkylated terphenyls, alkylated naphthalenes, diarylethanes, triarylmethanes, diphenylalkanes, etc. Hydrogens, oleyl alcohol, tridecyl alcohol, benzyl alcohol, 1-
Alcohols such as phenylethyl alcohol and glycerin, organic acids such as oleic acid, dimethyl phthalate, diethyl phthalate, di-n-butyl phthalate, dioctyl phthalate, diethyl adipate, propyl adipate, di-n-butyl adipate, adipine Esters such as dioctyl acid, tricresyl phosphate,
Organic phosphorus compounds such as tributyl phosphate, tributyl phosphite, tributyl phosphine oxide,
Ethers such as phenyl cellosolve, pendyl carbitol, polypropylene glycol, propylene glycol monophenyl ether, amides such as N, N dimethyl lauramide, N, N-dimethyl stearamide, N, N-dihexyl octyl amide, Ketones such as diisobutyl ketone and methylhexyl ketone, alkylene carbonates such as ethylene carbonate and propylene carbonate, and mixtures thereof.

As the encapsulation method, the conventionally known coacervation method, interfacial polymerization method, 1n-situ method, etc. can be appropriately selected and used, but it is preferable to use a synthetic resin as the wall film material. Among them, the melamine-formaldehyde resin capsule as described in Japanese Patent Application No. 59-23698 has excellent solvent resistance,
It is particularly preferred because it has excellent heat resistance and hiding properties.

The average particle diameter of the microcapsules is usually 0.5-15μ, preferably 1-5μ.

Note that the microcapsules may further contain antioxidants, ultraviolet absorbers, resins, etc., if necessary.

The amount of colorant added to the capsule core material is usually
The amount is 0.5 to 50 parts by weight, preferably 2 to 30 parts by weight.

In the non-aqueous capsule-containing ink used in the present invention, for example, (1) a microcapsule dispersion prepared in an aqueous system is directly dispersed in a non-aqueous medium; (2) Concentration under reduced pressure After passing through a concentration process such as filtration, the acidic acid is dispersed in a non-aqueous medium. (2) After passing through a concentration step such as vacuum concentration or filtration, the product is washed with a water-miscible solvent and dispersed in a non-aqueous medium. ■After being made into powder capsules by means such as ventilation drying, surface drying, fluidized drying, flash drying, spray drying, vacuum drying, freeze drying, infrared drying, high frequency drying, ultrasonic drying, and pulverized drying, it is placed in a non-aqueous medium. Alternatively, as described in JP-A-53-135718, it can be prepared by mixing an aqueous capsule dispersion with a non-aqueous medium and then removing the aqueous medium under reduced pressure.

In this case, in order to obtain an ink with a good quality dispersion, the capsules used are ones that have been prepared with a capsule dispersion and further treated with an aldehyde-based resin forming material as described in JP-A No. 60-238141. is preferable.

The ink of the present invention contains, in addition to microcapsules, a resin, a pigment, a capsule protectant, a surfactant, an ultraviolet absorber, an antioxidant, a fluorescent brightener, and a plasticizer as necessary. Prepare by adding etc.

The amount of microcapsules in the capsule-containing ink used in the present invention varies depending on the membrane quality and particle size of the capsules used, the type of ink medium, and the types and amounts of other additives, and is not limited thereto. However, the amount is preferably 3 to 100 parts by weight, more preferably 10 to 60 parts by weight, based on 100 parts by weight of the medium.

Specific examples of resins include rosin (gum rosin, wood rosin, Dole oil rosin), natural resins such as shellac, copal, dalman, giltonite, and zein, hardened rosin, ester gum, and other rosin esters, maleic acid resins, and fumaric resins. Semi-synthesis of acid resin, trimerized rosin, polymerized rosin, rosin-modified phenolic resin, methylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, ethylhydroxyethylcellulose, carboxymethylcellulose, cellulose acetate propionate, cellulose acetate butyrate, nitrocellulose, etc. resin, phenolic resin,
xylene resin, urea resin, melamine resin, ketone resin,
Coumarone, indene resin, petroleum resin, terpene resin, cyclized rubber, chlorinated rubber, alkyd resin, polyamide resin, acrylic resin, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, ethylene-maleic anhydride copolymer Polymer, styrene-maleic anhydride copolymer, methyl vinyl ether-maleic anhydride copolymer, isobutylene-maleic anhydride copolymer, polyvinyl alcohol,
Examples include synthetic resins such as modified polyvinyl alcohol, polyvinyl butyral (butyral resin), polyvinylpyrrolidone, chlorinated polypropylene styrene resin, epoxy resin, and polyurethane.

These resins are appropriately selected and used depending on the type of non-aqueous medium used, and the method for using them is disclosed in, for example, "Printing Ink Technology" CMC Co., Ltd. can be adopted as appropriate.

Pigments include calcium carbonate, magnesium carbonate, zinc oxide, titanium oxide, aluminum hydroxide, calcium phosphate, colloidal silica, acid clay, activated clay,
Examples include clays such as attapulgite, zeolite, bentonite, kaolin, and calcined kaolin, and organic pigments such as melamine resin and urea resin.

Specifically, cellulose powder,
Examples include starch powder, microspheres, glass beads, and synthetic resin powder.

Surfactants include sodium alkyl sulfate, sodium alkylbenzene sulfonate, sodium alkylnaphthalene sulfonate, sodium polystyrene sulfonate, sodium oleate amide sulfonate, sodium dialkyl sulfosuccinate, anionic surfactants such as sulfated castor oil; halogens; Cation activators such as trimethylaminoethylalkylamide, alkylpyridium sulfate, alkyltrimethylammonium halide, polyoxyethylene alkyl ether, polyoxyethylene fatty acid ester, polyoxyethylene alkylphenyl ether, polyhydric alcohol fatty acid ester, Examples include nonionic surfactants such as sucrose fatty acid ester; amphoteric surfactants such as alkyltrimethylaminoacetic acid and alkyldiethylenetriaminoacetic acid.

The wall film of each non-aqueous ink will be explained below.

(1) Flexo ink, gravure ink As the non-aqueous medium, those known in the printing industry can be used as appropriate, but specific examples 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
-butanol, etc., and low-boiling alcohols such as methanol and ethanol are most preferably used, and in addition, to control the drying properties of the ink, a small amount of n-hexanol, cyclohexanol, or any other alcohol within the range that does not impede the effects of the present invention is used. Water is added, or methyl acetate, ethyl acetate, butyl acetate, methyl cellosolve, ethyl cellosolve, etc. are added.

In the case of flexo type or gravure type ink, a resin is added as a binder, and if necessary, a pigment is added. Examples of this resin include the resins mentioned above, among which polyvinyl acetate, vinyl chloride/vinyl acetate copolymer, ethylene-maleic anhydride copolymer, styrene-maleic anhydride copolymer, methyl vinyl ether-maleic anhydride Copolymers, isobutylene-maleic anhydride copolymers, modified polyvinyl alcohol, polyvinyl butyral, polyvinylpyrrolidone, ethylcellulose, nitrocellulose, hydroxypropylcellulose, cellulose acetate propionate, cellulose acetate butyrate, and the like are preferred.

(II) Hot-melt ink The medium for hot-melt ink includes waxes, including animal waxes such as beeswax, spermaceti, lanolin, candelilla wax, carnauba wax, and wood wax. , vegetable waxes such as rice wax and sugarcane wax, mineral waxes such as montan wax, osikerite, and lignite wax, petroleum waxes such as paraffin wax and microcrystalline wax, Monkun wax derivatives, halaffin wax derivatives, and microstarine. Modified waxes such as wax derivatives, hydrogenated waxes such as castor wax and opal wax, low molecular weight polyethylene and its derivatives, synthetic waxes such as Akrawanox and distearyl ketone, caproic acid amide, caprylic acid amide, pelargonic acid amide, capric acid amide , lauric acid amide, tridecylic acid amide, myristylic acid amide,
Fatty acid amide waxes such as stearamide, behenic acid amide, ethylene bisstearamide, cabroic acid amide, oleic acid amide, linoleic acid amide, ricinoleic acid amide, linoleic acid amide, fatty acid based waxes such as stearic acid and behenic acid,
Alcohol-based waxes such as stearyl alcohol and phosphate-based waxes such as distearyl phosphate ester are used alone or in combination. Among them, oxidized mineral waxes such as montan wax, amide waxes such as ethylene bisstearamide, stearamide, behenic acid amide, fatty acid waxes, phosphate ester waxes, and mixtures thereof, 0.1 to 30
Those having a penetration hardness of , a melting point of 50°C to 160°C, and a melting range of less than 20°C are preferably used.

In addition, in the present invention, aromatic hydrocarbon compounds having a melting point in the range of 40°C to 200°C can be used in addition to the waxes described above. It is preferable to use a resin that can be used in combination. A good system can also be obtained by using aromatic hydrocarbon compounds and waxes in combination. A more preferable system is one in which a resin is used in combination with the mixed system.

Specifically, the aromatic hydrocarbon compound is 2.6-
Diituprobylnaphthalene, 1,4,5-trimethyl-
Naphthalene, 2,3.5-)limethylnaphthalene, 2
．． 3-dimethylnaphthalene, 1.3.6.8-tetramethylnaphthalene, 1゜2-di-0-tolylethane, bis-(2,4,5 trimethylphenyl)methane, 1.18
-diphenyl-octadecane, l,3-terphenyl,
1.2-di-p-)lylethane, diphenyl-p-tolylmethane, 1.2-dibenzylbenzene, 3.4-diphenylhexane, 1,2-bis-(2,3-dimethylphenyl)ethane, 4.4゜Isopropylidene diphenol, bisresorcinol ethylene ether, 4-tert-butylphenyl salicylate, 2,2-bis(
4-acetoxyphenyl)propane, bis(4-acetoxyphenyl)sulfone, terephthalic acid dichlorophenyl ester, terephthalic acid distearylamide, malonic acid ethyl ester 4-methoxyanilide, benzyl mandelate, benzoic acid phenyl ester, benzoic acid - 2-
Naphthyl ester, 2hydroxy-3-octylcarbamoylnaphthalene, 4-hydroxybenzoic acid benzyl ester, p-benzyloxybenzoic acid benzyl ester, 1.4
-bispropionyloxybenzene, 1,1-benzoylmethane and the like.

In addition, examples of the resin include the resins mentioned above, among which hardened rosin, ester gum, ethyl cellulose, phenol resin, rosin-modified phenol resin, urea resin,
Melamine resin, chlorinated rubber, cyclized rubber, maleic acid resin,
Petroleum resins, terpene resins, etc. are preferred.

(III) Electron beam or ultraviolet curable ink The medium for electron beam or ultraviolet curable ink includes compounds having one or more vinyl or vinylidene groups, such as acryloyl group, methacryloyl group, allyl group. group, unsaturated polyester, vinyloxy,
Examples include compounds having an acrylamide group and the like. The most typical 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. For example, typical compounds include polyethylene glycol diacrylate, propylene glycol dimethacrylate, pentaerythritol triacrylate, trimethylolpropane triacrylate, pentaerythritol tetraacrylate, hexanediol diacrylate, 1,2-butanediol diacrylate, and epoxy resin. and acrylic acid, a reaction product of methacrylic acid, pentaerythritol, and acrylic acid, a condensation product of maleic acid, diethylene glycol, and acrylic acid, methyl methacrylate, butyl methacrylate, styrene, etc. Regarding these monomers, see JP-A-49-52889 and JP-A-48-686.
No. 41, No. 48-32586, Special Publication No. 49-71) 5
You can also choose from those disclosed in the issue.

When curing the coating layer with ultraviolet rays, it is preferable to add a photopolymer initiator to the ink.

Examples of photopolymer initiators include aromatic ketones, quinone compounds, ether compounds, nitro compounds, etc.
Specific examples include benzoquinone, phenanthrenequinone, naphthoquinone, diisopropylphenanthrenequinone, benzoin butyl ether, benzoin, furoinbutyl ether, Michler's ketone, Michler's thioketone, fluorenone, trinitrofluorenone, and β-benzoylaminonaphthalene.

(rV) Letterpress type ink Oil is used as a medium for oxidative polymerization type (letterpress type) ink, and a solvent, wax, dryer, thickener, gelling agent, and thixotropy agent are added as necessary.

Examples of oils include vegetable oils (drying oils such as linseed oil and safflower oil, semi-drying oils such as soybean oil, and non-drying oils such as castor oil), processed oils (dehydrated castor oil, polymerized oils, maleated oils). , vinylated oil, urethanized oil), and mineral oil (machine oil, spindle oil).

Specific examples of the solvent include high-boiling petroleum solvents (ink oil), diethylene glycol moppyl ether, diethylene glycol moppyl ether acetate, and the like.

The thus prepared microcapsule ink containing the colorant is applied onto a support using various printing machines or coating machines such as a letterpress, an intaglio (gravure), a lithographic (offset), and a screen.

The amount of the microcapsule-containing ink to be applied is adjusted appropriately depending on the type of ink prepared, and is not particularly limited, but is generally 0°3 to 10g/rrr.
The amount is adjusted preferably within a range of about 1 to 5 g/rrr.

As the support used for printing or coating, it is not necessarily necessary to use valve-treated paper that has been subjected to a high beating process as is used for conventional Kacarbon copying paper; Various known supports including paper can be used.

"Examples" Examples and comparative examples are given below to further clarify the effects of the present invention, but the present invention is not limited to these examples. Parts and % in the examples represent parts by weight and % by weight, respectively, unless otherwise specified.

Example 1 Preparation of hot melt ink 10 parts of black dye (Sudan Blank B) was mixed with 100 parts of alkyldiphenylethane (trade name Hysol 5AS-296).
, manufactured by Nippon Petrochemicals Co., Ltd.) to obtain an internal phase oil. Ethylene-maleic anhydride copolymer (trade name EMA31.
After the internal phase oil was emulsified in a solution whose pH was adjusted to 6.0 by dropping a 20% aqueous sodium hydroxide solution into 200 parts of a 3.0% aqueous solution of Monsato Co., Ltd., the temperature of the system was raised 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 solution in water.

This prepolymer aqueous solution was added dropwise to the emulsion, and while stirring, the prepolymer solution was added dropwise. IN- Hydrochloric acid was added dropwise to adjust the pH to 5.
3, heated to 80°C, held at that temperature for 1 hour, lowered the pH to 3.5 with 0.2N hydrochloric acid, kept warm for an additional 3 hours, and then left to cool to obtain an average particle size of 3.8μ. A capsule dispersion was obtained.

Then, this dispersion was filtered and dried, and 100 dry capsules were obtained.
A true melt type capsule ink was obtained by dispersing 1 part in a mixed melt (at 130° C.) of 300 parts of carnauba wax and 10 parts of distearyl phosphate.

The above carbon capsule ink was printed on a gravure printing machine at 40 g/rd for pressure-sensitive copying paper (air permeability 20 seconds, opacity 65).
%, pulp freeness csf 420 ml) at a speed of 80 m/min, and the ink amount was 3.0 g/cd.
I obtained some copy paper.

...The obtained back carbon copy paper has no ink bleed through,
It has good whiteness, and when I printed it on my father's paper using a typewriter, a clear record was obtained.

Comparative Example 1 6 parts of black dye (Sudan Black B) was mixed with a mixture of 400 parts of Carnauba Wasox and 10 parts of distearyl ester (
(130° C.) to obtain a hot melt ink.

Creation of back carbon copy The above ink was printed on 40glrd base paper for pressure-sensitive copying paper similar to that in Example 1 using a gravure printing machine at a speed of 80 m/min, and the ink amount was 3.0 g/td. I got some copy paper.

The obtained back carbon copy paper showed considerable ink bleed through and was considerably inferior to the copy paper of Example 1 in terms of whiteness.

"Effects" The present invention was an excellent back carbon copying paper in which there was no phenomenon of ink strike-through and the coloring of the ink layer was not visible through the surface (original paper surface).

Claims (3)

[Claims] (1) Back carbon copying paper comprising a support and a layer containing microcapsules containing a colorant. (2) Back carbon copying paper made by printing a non-aqueous ink containing microcapsules containing a colorant on necessary parts of the paper to form a microcapsule-containing layer. (3) The back carbon copying paper according to claim (1) or claim (2), wherein the microcapsules have a wall film made of melamine-formaldehyde resin.