JPH1044594A - Pressure-sensitive copy sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provice a pressure-sensitive copy sheet capable of being easily produced by a general printing system, especially, an offset printing system, hard to carelessly generate the development of a color or frictional contamination by the adhesion of oil or a solvent and locally having a carbonless copy means different in developed color hue. SOLUTION: In a pressure-sensitive copy sheet performing duplication by a combination of a microcapsule layer 5 composed of a mixture of microcapsules 4 including a color former and microcapsules including a color former B developing a hue different from that of the color former A and a coupler layer 6, the microcapsule layer consists of microcapsules prepared by coating a substance compatible with ink vehicle with capsule wall material surface and is formed from ink wherein microcapsules with an average particle size of 5μm or less are dispersed in ink vehicle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure-sensitive copying sheet having carbonless copying means having locally different colors and hues, and more particularly to a pressure-sensitive copying sheet which can be easily manufactured by a general offset printing method, and The present invention relates to a pressure-sensitive copying sheet having a configuration in which color is inadvertently formed due to adhesion of oil or a solvent, and hardly rubbed.

[0002]

2. Description of the Related Art A pressure-sensitive copying sheet utilizing the principle of forming a color by a reaction between an electron-donating color former and an electron-accepting developer is well known and widely used. Conventional pressure-sensitive copying sheets use color formers such as crystal violet lactone and benzoyl leucomethylene blue.
Liquid components containing microcapsules containing a color former, which are generated by encapsulation methods such as the interfacial polymerization method, the in-situ method, the phase separation method, and the coacervation method, contain binder components such as polyvinyl alcohol, starch, natural rubber latex, starch powder, and talc. A pressure-sensitive copying sheet obtained by applying a coating liquid obtained by mixing a capsule protective agent to the sheet substrate surface, and activated clay, acid clay, zeolite, bentonite,
A phenol-formaldehyde resin, a pressure-sensitive copying sheet obtained by applying a coating liquid obtained by adding a binder component, a pigment, and the like to a color developer such as a polyvalent metal salt of an aromatic carboxylic acid on a sheet substrate surface; A pressure-sensitive copying sheet formed by applying the colorant-encapsulating microcapsule coating liquid and the developer coating liquid on separate sheet substrate surfaces is appropriately combined.

Conventionally, the hue of the main color former used in such a pressure-sensitive copying sheet is blue, black, or red.
The color-encapsulating agent-containing microcapsules are applied by an air knife coater, a roll coater, or a blade coater so as to develop a single color on the entire surface of the sheet substrate. However, recently, as a special application for preventing falsification, a color effect, and the like, a multicolor pressure-sensitive copying sheet that locally realizes a color development having a different hue has been proposed.

For example, Japanese Utility Model Laid-Open No. 1-301360 discloses a pressure-sensitive copying method in which a color former-encapsulated microcapsule ink that develops a color tone different from that of the color former is locally printed on the color former-enclosed microcapsule layer. A seat was proposed. The microcapsule ink here is obtained by filtering and drying a capsule dispersion liquid (product liquid), dispersing the powder in an ink vehicle, and using a printing machine such as letterpress, gravure, offset, or screen to form a sheet. Printing is performed on a substrate surface to obtain a pressure-sensitive copying sheet. However, when the capsule dispersion is filtered, dried, and pulverized, the capsule wall material is hardened and becomes brittle, and further, in the powder state, binding between the capsules, so-called secondary agglomeration occurs, and the average particle size of the capsules Will increase. As a result, the capsules are destroyed in the ink-making step, and there is a problem with offset printing, which is a general form printing method.

Therefore, in Japanese Utility Model Laid-Open No. 6-40147, a coloring agent which forms a color having a different hue from that of the coloring agent is directly encapsulated on the microcapsule layer enclosing the coloring agent without powdering the coloring agent. There has been proposed a pressure-sensitive copying sheet formed by locally printing a coloring agent ink obtained by incorporating the ink in an ink vehicle, particularly a photocurable ink (ultraviolet curable ink). However, when the coloring agent is directly contained in the ink vehicle without encapsulation, unintentional coloring due to the adhesion of oil or a solvent, and rubbing stains are more likely to occur as compared with those protected by the capsule wall material. Problems arise.

[0006]

In view of the above problems, the present invention can be easily manufactured by a general printing method, especially an offset printing method, and inadvertently develops color or rubs due to adhesion of oil or solvent. It is an object of the present invention to provide a pressure-sensitive copying sheet having a carbonless copying means having a configuration in which stains are hardly generated and locally having different coloring hues.

[0007]

In order to solve the above-mentioned problems, a pressure-sensitive copying sheet of the present invention comprises a microcapsule containing a color-forming agent A and a color-forming agent B which forms a color different from that of the color-forming agent A.
A pressure-sensitive copying sheet that performs copying by a combination of a microcapsule layer and a developer layer composed of a mixture of encapsulated microcapsules, wherein the microcapsule layer is
The microcapsules are characterized in that the surface of the capsule wall material is coated with a substance having an affinity for the ink vehicle, and the microcapsules are formed of a microcapsule-containing ink dispersed in the ink vehicle with an average particle size of 5 μm or less.

[0008] In particular, the pressure-sensitive copying sheet of the present invention is characterized in that the ink containing microcapsules containing the color former B is an ultraviolet curable ink.

Hereinafter, the microcapsules enclosing a color former in the present invention will be described in detail. The coloring agent used in the present invention is a known coloring agent, such as crystal violet lactone, 3,6-bis-diphenylaminofluoran, or 3- [1,1-bis (4-diethylaminophenyl) ethylene-2-yl. Blue-coloring agents such as -6-dimethylaminophthalide, 2-anilino-3-methyl-6
Such as -N-methyl-pentylaminofluoran, 2-anilino-3-chloro-6-dimethylfluoran, 2-anilino-3-methyl-6-N-methyl-N- (iso-propyl) aminofluoran and the like Black coloring agent, 2-chloro-
3-methyl-6-diethylaminofluoran, 1,2-
Red coloring agents such as benzo-6-diethylaminofluoran and 3,3-bis (1-octyl-2-methylindol-3-yl) phthalide, or 2-dibenzylamino-6-diethylaminofluoran, Octylamino-6-diethylaminofluoran, 3,3 bis (4-
It is arbitrarily selected from green coloring agents such as diethylamino-2-ethoxyphenyl) -4-azaphthalide. In the present invention, the color former A and the color former B applied locally on the upper surface thereof are selected so as to have different color hues, that is, a pressure-sensitive copying lower sheet or an intermediate sheet. On the surface of the color developer layer, a color image of the hue of the color former A and a color image of a mixed color of the color former A and the color developer B are locally obtained.

[0010] The ink containing microcapsules containing a color former contains a substance having a function as a dispersant having an affinity for both the capsule wall material and the ink vehicle, for example, with glycerin, A substance such as ethylene glycol, butanediol, or propylene glycol is mixed, and this substance is mixed with the ink component in a state where the capsule wall material is coated. The water in the mixture is vaporized and removed by a vacuum distillation method. To give an example of water removal, when the substance that is compatible with both the capsule wall material and the ink vehicle is, for example, glycerin (boiling point: 290 ° C.), the mixed liquid is 30 to
The mixture was heated to 970 ° C. and finally reduced to a water content of 5 to 15% by weight under reduced pressure (about 10 Pa) by evacuation.
Preferably, it is about 8 to 12% by weight.

The boiling point of the ink vehicle is higher than that of water because it is necessary to selectively vaporize and remove water by vacuum distillation. For example, in the case of ultraviolet curable ink used in offset printing of business forms, methyl acrylate, methyl acrylate, acrylic ester of polyhydric alcohol, epoxy acrylate, urethane acrylate, polyester acrylate, polyether type In the case of acrylate or oxidative polymerization type inks, drying oils such as linseed oil and cinnamon oil mainly containing oleic acid, linoleic acid, and linoleic acid, semi-dry oils such as soybean oil, and non-drying oils such as castor oil And mixed glycerides of unsaturated fatty acids.

As described above, the microcapsules enclosing a color former formed in an aqueous system without drying the capsule-producing liquid to form a powder have a dispersant function having an affinity for both the capsule wall material and the ink vehicle. Substituting water in a dispersed state in the ink while retaining the substance allows the microcapsules to grow without compromising physical properties such as elasticity and strength at the time of their formation, and by combining multiple capsules. So-called secondary agglomeration, such as formation of formed particles, does not occur, and the average particle size can be set to 5 μm or less in the same manner as that set when producing capsules for pressure-sensitive copying. Therefore, the capsule is not broken even when it is kneaded with a roller and further when it is pressed against a printing medium, or the capsule is broken by specifying the material of the blade when the ink is scraped off by a doctor blade. Does not occur.

The ink containing microcapsules containing the color former in the present invention can be obtained by appropriately selecting the ink components.
It can be an ink compatible with various printing methods such as letter press, gravure, offset, flexo, and screen. Among them, the offset printing method is a general printing method for preparing a pressure-sensitive copy sheet, and when printing by the method, it is most preferable to use an ultraviolet curable ink.

When the ink containing the microcapsules containing the color former is an ultraviolet-curable ink, the ink components include a photopolymerizable oligomer such as polyester acrylate, epoxy acrylate, urethane acrylate and polyol acrylate, and 2-hydroxyethyl (meth) acrylate. , 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, amyl Monofunctional (meth) acrylates such as (meth) acrylate, isobutyl (meth) acrylate, pentyl (meth) acrylate, t-butyl (meth) acrylate, and isoamyl (meth) acrylate Relate, trimethylolpropane tri (meth) acrylate, trimethylolpropane ethylene oxide adduct triacrylate, pentaerythritol tetra (meth) acrylate, ethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di A photopolymerizable vehicle comprising a photopolymerizable monomer such as a polyfunctional (meth) acrylate such as (meth) acrylate, 1,4-butanediol di (meth) acrylate, and 1,6-hexanediol di (meth) acrylate; and , 1-hydroxycyclohexylphenyl ketone, 2,2-dimethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, orthobenzoylbenzoate Photopolymerization initiators such as acid methyl ester, triethanolamine, p-
Photosensitizers such as dimethylaminobenzoate, 4,4-diethylaminobenzophenone, triisopropanolamine, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, hydroquinone, p-benzoquinone, phenothiazine, t
-Additives such as thermal polymerization inhibitors such as butyl catechol.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The pressure-sensitive copying sheet of the present invention will be described below in more detail with reference to the accompanying drawings. Here, FIG. 1 is a schematic cross-sectional explanatory view of the pressure-sensitive copying sheet of the present invention, and FIG. 2 is a diagram of the ink layer containing the color former A-containing microcapsules and the color former B-containing microcapsules in the pressure-sensitive copying sheet of FIG. It is an enlarged explanatory view.

As shown in FIG. 1, the pressure-sensitive copying sheet 1 according to the present embodiment has an upper sheet 2 and a lower sheet 3 which are separably overlapped with an adhesive 7 and a cut-out sewing line 8. A predetermined color on the back side of the upper sheet 2 is provided with a microcapsule layer 4 containing a coloring agent A selected from a blue coloring agent, and further, a coloring selected from the microcapsules containing a coloring agent A and a red coloring agent. The microcapsule-containing ink layer 5 of the color formers A and B mixed with the microcapsules containing the agent B is applied. Further, a color developer layer 6 is provided on the entire front surface side of the lower sheet 3, and with such a configuration, the color image of the color developer A having a bluish hue is formed on the surface of the color developer layer 6 of the lower sheet 3. As a result, a purple colored image, which is a mixed color of the coloring agent A and the coloring agent B, is obtained.

Hereinafter, a method for preparing the ink containing microcapsules containing the color former and a method for forming the ink layer containing microcapsules containing the color former will be described.

Method for preparing ink containing microcapsules containing a color former: 200 parts of a 5% by weight aqueous solution obtained by dissolving a styrene-maleic anhydride copolymer together with a small amount of sodium hydroxide in a 300 ml closed container connected to a vacuum pump. 6 parts of a 2-chloro-3-methyl-6-diethylaminofluorane dye as a red coloring agent is heated and dissolved in 194 parts of the alkylnaphthalene. This was dispersed to form a dispersion having an average particle size of 2 μm, and 60 parts of a melamine-formalin initial polycondensate was added to the emulsion, and the mixture was stirred at a system temperature of 75 ° C. for 2 hours to produce 50% by weight microcapsules. Make 80 parts of liquid. Further, glycerin 20 is added and sufficiently stirred. To the mixture, 20 parts of an ultraviolet-curable ink component is added while stirring and mixed, and the pressure in the flask is reduced to about 10 Pa by evacuation while heating to 40 ° C., and for 1 to 2 hours While maintaining this state, water is removed and the water content is reduced to about 10% by weight. Further, 30 parts of a preparation for printing ink was added and sufficiently stirred to prepare an ink containing microcapsules containing a color former.

Method for forming ink layer containing microcapsules containing color former: The ink containing microcapsules containing color former prepared as described above was prepared using a general offset printing machine at a printing speed of 600 feet / min. A locally dried ink amount of 2 g /
m ^2, and a layer is formed via a UV dryer.

As shown in FIG. 2, the microcapsules C containing the color former in the ink layer 5 containing the microcapsules containing the color former have a state in which a substance D (glycerin) having an affinity for the ink vehicle V covers the surface of the capsule wall material C1. In an ink vehicle V cured by irradiation with ultraviolet rays, a good dispersion state is obtained while maintaining the average particle size of 5 μm or less at the time of capsule formation, so that a very uniform and good color image can be obtained at the time of color development under pressure. It is.

The developer layer 6 applied to the lower sheet 3
Mixing electron-accepting resins and clays such as phenolic resin, acid clay, activated clay, zeolite and bentonite with white pigments such as titanium oxide, calcium carbonate and zinc oxide in aqueous binders such as starch and polyvinyl alcohol. May be a conventional composition formed by applying a developer paint prepared on the entire surface of the sheet substrate.For example, an oil-soluble phenol-formalin resin, an acid clay or an aromatic carboxylic acid derivative, an aromatic hydrocarbon, an alcohol, Dissolve it in a low-boiling organic solvent such as an ester together with a surfactant such as an alkylbenzene sulfonate, and further prepare a developer ink by adding a white pigment, and partially print the necessary portion of the sheet substrate surface. The obtained configuration may be used.

[0022]

According to the constitution of the pressure-sensitive copying sheet of the present invention, the ink having the carbon-free copying means having locally different coloring hues and forming the ink layer containing the microcapsules containing the coloring agent is excellent in printability. Since it has appropriate fluidity and drying properties and can be handled in the same way as conventional inks, it can be easily manufactured by a general offset printing method, and the coloring agent is protected by the capsule wall material. Therefore, there is an effect that color is inadvertently formed due to adhesion of oil or a solvent, and rubbing is less likely to occur.

[Brief description of the drawings]

FIG. 1 is a schematic sectional explanatory view of a pressure-sensitive copying sheet of the present invention.

FIG. 2 is an enlarged explanatory view of a color-encapsulating microcapsule-containing ink layer in the pressure-sensitive copying sheet of FIG. 1;

[Explanation of symbols]

REFERENCE SIGNS LIST 1 pressure-sensitive copying sheet 2 upper sheet 3 lower sheet 4 microcapsule layer containing colorant A and microcapsule containing colorant A and B 6 color developer layer C microcapsule containing colorant C1 capsule wall material V ink Vehicle D Substances compatible with the ink vehicle

Claims (2)

[Claims] 1. Copying is performed by a combination of a microcapsule layer and a developer layer comprising a mixture of a microcapsule containing a color former A and a microcapsule containing a color developer B that develops a color different from that of the color former A. A pressure-sensitive copying sheet, wherein the microcapsule layer is formed by coating the surface of a capsule wall material with a substance which is compatible with an ink vehicle and dispersing the microcapsules in the ink vehicle with an average particle size of 5 μm or less. A pressure-sensitive copying sheet formed of ink containing microcapsules. 2. The pressure-sensitive copying sheet according to claim 1, wherein the ink containing microcapsules containing the color former B is an ultraviolet curable ink.