JPS6317634B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a plain paper transfer type pressure sensitive copying paper having a white transfer layer.

Forms conventionally used as pressure-sensitive copying paper can be broadly classified into two types. One of them is copying paper that uses a combination of a colorless electron-donating color former and a colorless electron-accepting color developer. That is, the upper paper coated with microcapsules containing a non-volatile organic liquid in which a color former is dissolved, and the lower paper coated with a color developer that reacts with the color former to form a color, with the coated surfaces of each coated paper facing each other, and the upper paper side By applying pressure with a ballpoint pen, pencil, typewriter, etc., the microcapsules are destroyed, and the encapsulated coloring agent moves with the solvent to the underlying paper and reacts with the color developer to obtain a colored recorded image. In this form, both the top paper and the bottom paper before use are colorless and do not stain hands or clothes during handling, which is preferable in terms of appearance. However, both colorless color formers and color developers are expensive.
There are disadvantages such as the fact that a recorded image can only be obtained on the lower paper coated with a color developer, and the recorded image has poor storage stability and is prone to discoloration and fading over time.

Another form is copy paper that uses colorants such as colored dyes or pigments. A typical example is carbon-back copy paper. This is produced by applying a colorant and wax to the back side of the support, or by dissolving or dispersing the colorant in oil and retaining it in a porous layer formed on the back side of the support. With these, a recorded image can be obtained on plain paper by overlapping the colored side on plain paper and applying pressure from the copy paper side. In this form, a coloring agent is applied to the back side of the copy paper to give it a colored appearance, and the coloring on the back side is reflected from the front side, which is undesirable in terms of appearance. Another disadvantage is that the coloring agent adheres to hands, clothes, etc. during use. However, the obtained recorded image has excellent storage stability and there is no economic change.

Therefore, in order to compensate for the shortcomings of both types, there are several ways to create a copy paper with a transfer layer in which the colored layer is whitened using a coloring agent such as a colored dye or pigment, and to obtain a recorded image on plain paper. or has been proposed. For example, Special Publication No. 44-27258, Special Publication No. 7333,
Japanese Patent Publication No. 46-1723 discloses a method in which a colored layer and a whitening layer are coated on the back side of a support, and both layers are simultaneously transferred onto plain paper by pressure, whereby the colored layer appears and a recorded image is obtained. has been done. Both of these are 2
It is necessary to apply multiple layers, which increases the number of manufacturing steps and increases costs. Furthermore, the colorant is left as it is,
Alternatively, since the colorant dissolved or dispersed in oil is encapsulated and used, the concentration of the colorant is applied to the support as it is, and as a result, a large amount of whitening agent must be used to whiten the concentration. As a result, the thickness of the coating layer increases, and the properties of the paper deteriorate, such as the number of copies that can produce clear recorded images decreases.

As a result of our research to improve these drawbacks, the present inventors have developed microcapsules that contain an organic liquid on the back side of a support, and colored dyes that are soluble in the organic liquid (referred to as organic liquid-soluble colored dyes). By providing a transfer layer containing a whitening agent as a main component, the desired plain paper transfer type pressure-sensitive copying paper could be obtained.

The plain paper transfer type pressure sensitive copying paper according to the present invention will be explained in more detail. A small amount of fine powder of an organic liquid-soluble colored dye is mixed with a whitening agent for whitening the powder. Since organic liquid-soluble colored dyes are in the form of fine powder, they have low absorbance and do not require a particularly large amount of whitening agent to whiten the coating layer, and can be applied in a single layer without the need to apply a separate whitening layer. Also, sufficient whiteness can be obtained. A transfer ink is prepared by further mixing microcapsules containing an organic liquid that dissolves an organic liquid-soluble colored dye into this mixture. A plain paper transfer type pressure-sensitive copying paper coated with the obtained transfer ink on the back side of the support is placed on a plain paper-like support, and when pressure is applied from the copy paper side with a typewriter, pencil, etc., the back side of the copy paper is The microcapsules are ruptured and the released organic liquid contacts the fine powder of organic liquid soluble colored dye. As a result, the organic liquid-soluble colored dye dissolves and is perceived as a dark color.
At the same time, it is transferred onto plain paper and a clear recorded image is obtained. Therefore, even if a small amount of the dye is used, a recorded image of sufficient density can be obtained, which is also economically advantageous. As described above, the plain paper transfer type pressure-sensitive copying paper according to the present invention is obtained by applying the difference in absorbance between the solid state of fine powder of organic liquid-soluble colored dye and the state dissolved in organic liquid. The principle of color development is quite different from that of pressure-sensitive copying paper, which is coated with a colorant such as the above, and uses the color of the colorant as it is in the recorded image. Also, Special Publication No. 37-2718,
JP-A-53-106210 discloses a pressure-sensitive copying paper that combines oil-containing capsules and a colorant, but in all of these, the capsules are undercoated and
It is a two-layer coating form in which a colored layer containing a coloring agent is applied thereon, and the back side of the obtained pressure-sensitive copying paper, that is, the coated side, is colored because the coloring agent is directly exposed to the surface. The structure is different from that of .

The plain paper transfer type pressure-sensitive copying paper according to the present invention can be used to simultaneously record two or more sheets by stacking them so that the front and back surfaces, that is, the surfaces coated with white transfer ink, face each other. Even if the recorded image is subjected to careless pressure or rubbing, no new coloring will occur and only the recorded image will be preserved clearly.Also, since colored dyes are used, electron-donating coloring agents Compared to recorded images obtained by the reaction between the color and electron-accepting color developer, it has greater resistance to light, heat, chemicals, etc., and has excellent storage stability.

As the organic liquid-soluble colored dye used in the plain paper transfer type pressure-sensitive copying paper according to the present invention, any colored dye having high solubility in the organic liquid can be used. For example, monoazo series, disazo series, metal complex type monoazo series, anthraquinone series,
Selected from colored dyes such as phthalocyanine and triallylmethane. Specifically, the color index numbers are 11020, 11021, and 11020 for yellow.
12055, 12700, 18690, 18820, 47000, etc., 12010, 12150, 12715, 26105, 26125, 27291, etc. for red.
45170B, 60505 etc., 61565 etc. for green, blue for
61100, 61705, 61525, 62100, 42563B, 74350
etc., black colors include 12195, 26150, 50415, etc. These colored dyes alone or in combination
It can be used after being made into a fine powder of 100 μm or less, preferably 80 μm or less.

Any whitening agent with a high degree of whiteness can be used as a whitening agent to whiten the coating layer when applied together with an organic liquid-soluble colored dye, but white pigments, celluloses, waxes, and metals are particularly suitable. Soaps and the like are preferred. Examples of white pigments include inorganic pigments such as barium sulfate, magnesium sulfate, calcium sulfate, zinc sulfate, titanium oxide, calcium carbonate, kaolin, activated clay, acid clay, zeolite, bentonite, and talc, polystyrene,
Organic pigments such as polyethylene and urea-formalin resin can be used alone or in combination.

As celluloses, nitrocellulose, methylcellulose, ethylcellulose, acetylcellulose, carboxymethylcellulose, hydroxyethylcellulose, etc. can be used alone or in combination. As waxes,
Plant-based waxes such as rice wax, wood wax, Candelilla wax, and carnauba wax; animal-based waxes such as lanolin, beeswax, and Serratus wax; mineral-based waxes such as Montan wax;
Paraffin wax, microcrystalline wax, oxidized paraffin wax, chlorinated paraffin wax, ricinoleic acid amide, lauric acid amide, erucic acid amide, palmitic acid amide, oleic acid amide, 12-hydroxystearic acid, distearyl ketone, Synthetic waxes such as ethylene bisstearamide can be used alone or in combination. Examples of metal soaps include sodium stearate, sodium palmitate, potassium laurate, potassium myristate, calcium stearate, zinc stearate, aluminum stearate, magnesium stearate, lead stearate, dibasic barium stearate, etc. Can be used in combination.

Further, as a whitening agent, one or a combination of white pigments, celluloses, waxes, metal soaps, etc. can also be used.

The organic liquid to be encapsulated in the microcapsules used in the plain paper transfer type pressure-sensitive copying paper of the present invention is preferably an organic liquid that has excellent ability to dissolve organic liquid-soluble colored dyes, such as benzene, toluene, methyl cellosolve, etc. organic liquids, more preferably diarylmethane-based, diarylethane-based, alkyldiphenyl-based, alkylnaphthalene-based, chlorinated paraffinic, aromatic ester-based,
Nonvolatile organic liquids such as aliphatic esters, higher alcohols, and higher fatty acids can be used alone or in combination.

Furthermore, microcapsules can be produced by any method such as interfacial polymerization, in situ polymerization, phase separation, and spray drying.

The transfer ink of the plain paper transfer type pressure-sensitive copying paper according to the present invention can be applied by coating the entire surface of the sheet using a general coater such as an air knife coater as an aqueous dispersion coating solution, or by using a flexo printing machine, etc. There is a method of applying it to the entire surface or part of the sheet. Further, the coating can be similarly applied as a solvent dispersion coating solution using an organic solvent that does not dissolve the organic liquid-soluble colored dye. Multicolored plain paper transfer type pressure sensitive copying paper can also be obtained by partial application of transfer ink using organic liquid soluble colored dyes of different colors.

Although paper is mainly used as the support for the plain paper transfer type pressure-sensitive copying paper according to the present invention, various nonwoven fabrics, plastic films, synthetic papers, metal foils, etc., or composite sheets combining these can also be used as desired. .

In order to hold the transfer ink according to the present invention on the sheet surface, an adhesive or the like can be added, and a liquid property improver can be added depending on various coaters and printing machines. Examples of liquid property improvers include thickeners that keep the viscosity constant and surfactants that improve dispersibility, but it is clear that the present invention is not limited to these.

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

Example 1 100 parts of Hysol SAS N296 (manufactured by Nippon Petrochemical Co., Ltd., diarylethane solvent) was emulsified in 200 parts of a 5% ethylene-maleic anhydride aqueous solution,
The pH of the system was set to 4.0. Add 200 parts of an aqueous solution containing 10 parts of urea and 2 parts of resorcin to the emulsion, and
After adding 25 parts of a 37% formalin aqueous solution, the temperature of the system was maintained at 55°C and the reaction was carried out for 3 hours. After the reaction, the mixture was cooled and the pH was adjusted to 8.0 to obtain a microcapsule dispersion containing an organic liquid. 20 parts of the microcapsule dispersion, 4 parts of an aqueous dispersion (solid content 25%) of Oil Blue BA (manufactured by Chuo Gosei Kagaku Co., Ltd., color index number: 61555), an aqueous dispersion of microcrystalline wax (solid content) 40%) and 117 parts of an aqueous dispersion of zinc stearate (solid content 30%) were added and thoroughly stirred, then coated on the back side of high-quality paper with a basis weight of 50 g/m ² using a coating rod and dried. A plain paper transfer type pressure-sensitive copying paper having an almost white transfer layer was obtained.

The resulting plain paper transfer type pressure-sensitive copying paper was stacked with high-quality paper with the transfer layer facing down, and then placed on a typewriter.
Pressure printing was performed using IBM82C (printing pressure 5), and a clear blue transfer image was obtained on high-quality paper.

Example 2 20 parts of an adduct of hexamethylene diisocyanate and trimethylolpropane containing an isocyanate group were added as a wall-forming substance to 100 parts of diisopropyl adipate and dissolved therein. This oily solution was added to 180 parts of water at 20°C in which 10 parts of carboxymethyl cellulose and 10 parts of polyvinyl alcohol were dissolved, with vigorous stirring to form oil droplets with a diameter of 5 to 8 μ, and then diluted by adding 170 parts of water. . 20 parts of ethylenediamine was added and the temperature of the system was raised to 70°C to obtain a microcapsule dispersion containing an organic liquid. 30 parts of the microcapsule dispersion, 4 parts of an aqueous dispersion (solid content 25%) of Oil Black HBB (manufactured by Orient Chemical Industry Co., Ltd., color index number: 26150), Castor Wax (manufactured by Kokura Gosei Kogyo Co., Ltd.) water dispersion (solid content 40%)
105 parts, aqueous dispersion of ethyl cellulose (solid content 25
%) 48 parts and 6 parts of calcium carbonate, then add water.
After adding 40 parts and stirring thoroughly, the basis weight is 50
g/m ² high-quality paper using a coating rod and dried to obtain a plain paper transfer type pressure-sensitive copying paper having an almost white transfer layer.

The transfer layer of the obtained plain paper transfer type pressure-sensitive copying paper was placed face down on a piece of high-quality paper, and pressure printing was performed using a typewriter to obtain a clear black transferred image on the high-quality paper.

Claims (1)

[Scope of Claims] 1. A plain paper transfer type pressure-sensitive copying paper having on the back side of a support a transfer layer mainly containing microcapsules containing an organic liquid, a colored dye soluble in the organic liquid, and a whitening agent. . 2. The plain paper transfer type pressure-sensitive copying paper according to claim 1, wherein the whitening agent is one or more selected from the group of white pigments, celluloses, waxes, and metal soaps.