JPS6317632B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pressure-sensitive recording paper comprising a transfer sheet having microcapsules containing an organic liquid and a receiving sheet having a colored dye soluble in the organic liquid.

The conventional forms of pressure-sensitive recording paper are:
It can be broadly divided into two parts. One of them is to obtain a colored recorded image by applying pressure with colorless pressure-sensitive recording paper. That is, the top paper coated with microcapsules containing a non-volatile organic solvent containing a colorless leuco dye dissolved therein, and the bottom paper coated with a colorless color developer that reacts with the colorless leuco dye to develop color at room temperature. By applying pressure with a ballpoint pen, pencil, etc. from above the top paper with the sides facing each other,
When the microcapsules are destroyed, the encapsulated dye 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 are colorless before use, so they do not stain hands or clothes, and are preferable in terms of appearance. However, both the colorless leuco dye and the color developer are expensive, and the colored recorded images produced have poor storage stability.
It has drawbacks such as easy discoloration due to sunlight, moist heat, etc.

Another form is to use a coloring agent such as a colored dye or pigment. A typical example is Uracarbon transfer paper. This is manufactured by applying a colored material and wax to the back side of transfer paper, or by dissolving the colored material in oil and retaining it in a porous coating layer. The recorded images obtained with this transfer paper have excellent storage stability, but since the transfer paper has a colored layer made of colored dyes or pigments, colored substances may adhere to hands and clothes during use, and the appearance may be affected. Not liked by people.

In order to compensate for the drawbacks of both types, several methods have been proposed in which the colored layer is whitened using a coloring agent such as a colored dye or pigment. In most cases, a white pigment, plastic, or the like is applied onto a colored layer to make it white.
Among them, Tokuko No. 49-43570, Tokuko No. 50-
As shown in Publication No. 14567, a whitening layer is placed on a colored layer containing a colorant, and the upper whitening layer is made transparent by placing a whitening layer directly on the coating layer or by overlapping a sheet coated with a solvent-containing capsule and applying pressure. A method of making a recorded image by making the colored layer appear as a lower layer, and also
No. 44-27258, Special Publication No. 1972-9622, Special Publication No. 1977-
As shown in Publication No. 1723, etc., there is a method in which a colored layer and a whitening layer are coated on the back side of a sheet surface, and both layers are simultaneously transferred onto another sheet by pressure to cause the colored layer to appear and form a recorded image. be. Both of these are 2
It is necessary to apply multiple layers, which increases the number of manufacturing steps and increases costs. Furthermore, if the colored layer is to be particularly whitened, the upper whitening layer must be made thicker, resulting in poorer properties as a recording paper. Furthermore, since the recorded image has the color of the colorant itself, a large amount of the colorant is required to achieve density.

As a result of our research to improve these shortcomings, the present inventors have discovered that in pressure-sensitive recording paper that uses a combination of a transfer sheet and a receiving sheet, the transfer sheet mainly contains microcapsules containing an organic liquid on the back side. The receiving sheet has a receiving layer mainly containing a colored dye soluble in the organic liquid (hereinafter referred to as an organic liquid soluble colored dye) and a white pigment on the surface thereof, and the receiving sheet The desired pressure-sensitive recording paper was able to be obtained by making the coating layers of the receiving sheet face each other and using them in combination. The pressure-sensitive recording paper according to the present invention will be explained in more detail. A receiving sheet is obtained by applying a small amount of fine powder of an organic liquid-soluble colored dye and a white pigment or the like to whiten the powder. Since the organic liquid-soluble colored dye is in the form of a fine powder, its absorbance is low, and a particularly large amount of white pigment or the like is not required to whiten the coating layer. Furthermore, even when applied in a single layer, the degree of coloration is low and an almost white coating layer can be obtained. This is layered with a transfer sheet coated with microcapsules containing organic liquid that dissolves organic liquid-soluble colored dyes, with the coating layer facing each other, and when pressure is applied from the transfer sheet side with a typewriter, pencil, etc., the microcapsules are removed. The destroyed and liberated organic liquid comes into contact with the organic liquid-soluble colored dye, and the fine powder of the dye is dissolved. As a result, the dye is perceived as a deep color and a clear recorded image can be 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.

Further, the transfer layer and the receiving layer can be provided on the back and front surfaces of the same sheet, respectively. In this case, there is a risk that some of the microcapsules will be destroyed by pressure or heat during printing or coating, allowing the organic liquid to penetrate and coloring the surface. To prevent this, it is preferable to apply a natural or synthetic polymer as a penetration inhibitor to the lower layer of the transfer layer containing microcapsules, or to treat both sides of the sheet in advance using a size press. By using the transfer layer and the receiving layer of this sheet in a stacked manner so as to face each other, recording on two or more sheets can be obtained simultaneously. The recorded image obtained is resistant to light, heat, chemicals, etc. and has excellent storage stability.

The pressure-sensitive paper of the present invention takes advantage of the difference in absorbance between an organic liquid-soluble colored dye in its solid state and when the dye is dissolved in an organic liquid, and is published in Japanese Patent Publication No. 49, 1973.
The color development mechanism is quite different from the method disclosed in Japanese Patent No. 43570, in which a whitening layer is made transparent with an organic liquid to make a colored pigment appear in a two-layer coating format.

As the organic liquid-soluble colored dye used in the pressure-sensitive recording paper according to the present invention, any colored dye having high solubility in the organic liquid can be used.

For example, it is selected from colored dyes such as monoazo, disazo, metal complex type monoazo, anthraquinone, phthalocyanine, and triallylmethane. Specifically, the color index numbers are 11020, 11021, 12055, 12700,
18690, 18820, 47000, etc., 12010, 12150 for red,
12715, 26105, 26125, 27291, 45170B, 60505
etc., 61565 etc. for green, 61100, 61705, etc. for blue.
61525, 62100, 42563B, 74350, etc., black has
Examples include 12195, 26150, 50415, etc. These colored dyes can be used alone or in combination.

Examples of white pigments include inorganic pigments such as barium sulfate, magnesium sulfate, calcium sulfate, zinc oxide, titanium oxide, calcium carbonate, kaolin, activated clay, acid clay, zeolite, bentonite, and talc, polystyrene, polyethylene, urea-formalin resin, etc. Organic pigments and the like can be used alone or in combination. In addition to white pigments, waxes and the like that have the effect of whitening organic liquid-soluble colored dyes can also be used together with white pigments.

Such waxes include 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; and paraffin waxes. wax, microcrystalline wax, oxidized paraffin wax, chlorinated paraffin wax,
Synthetic waxes such as ricinoleic acid amide, lauric acid amide, erucic acid amide, palmitic acid amide, oleic acid amide, 12-hydroxystearic acid, distearyl kettle, ethylene bissteric acid amide, etc. can be used alone or in combination. can.

The organic liquid to be encapsulated in the microcapsules used in the pressure-sensitive recording paper of the present invention is preferably one that has an excellent ability to dissolve organic liquid-soluble colored dyes, such as volatile organic liquids such as benzene, toluene, methyl cellosolve, etc. More preferably, a nonvolatile organic liquid such as diarylmethane, diarylethane, alkyl diphenyl, alkylnaphthalene, chlorinated paraffin, aromatic ester, aliphatic ester, higher alcohol, or higher fatty acid is used alone. or can be used in combination. Further, it can be produced by any method such as a microcapsule interfacial polymerization method, an in situ polymerization method, a phase separation method, and a spray drying method.

The transfer layer and receiving layer of the pressure-sensitive recording paper according to the present invention can be coated on the entire surface of the sheet using a general coater such as an air knife coater as an aqueous dispersion coating solution, or using a flexo printing machine or the like. There is a method of applying it to the entire surface or part of the sheet. Further, the coating can be similarly applied as an organic liquid dispersion coating liquid using an organic liquid that does not dissolve the organic liquid-soluble colored dye. Multicolored pressure-sensitive recording papers can also be obtained by partially coating the receiving layer with organic liquid-soluble colored dyes of different colors.

The sheet used for the pressure-sensitive recording paper according to the present invention is mainly paper, but various nonwoven fabrics, plastic films, synthetic papers, metal foils, etc., or composite sheets made of a combination of these can also be used as desired.

When preparing the coating liquid for forming the transfer layer and receiving layer of the pressure-sensitive recording paper according to the present invention, adhesives, etc. are used to hold each layer on the sheet surface, and liquid property improvers are added to suit various coaters and printing machines. Can be added. Liquidity improvers include thickeners that keep the viscosity constant and surfactants that improve dispersibility.
It is clear that the 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 (1) Creation of transfer sheet 100 parts of Hysol SAS N296 (manufactured by Nippon Petrochemical Co., Ltd., diarylethane solvent) at 5%
It was emulsified in 200 parts of an ethylene-maleic anhydride aqueous solution and the pH of the system was adjusted to 4.0. Add 200 parts of an aqueous solution containing 10 parts of urea and 2 parts of resorcin to the emulsion,
Furthermore, 25 parts of a 37% formalin aqueous solution was added, the temperature of the system was maintained at 55°C, and the reaction was allowed to proceed for 3 hours, followed by cooling, and the pH was adjusted to 8.0 to complete the encapsulation. 100 parts of the obtained microcapsule dispersion, 8 parts of oxidized starch, and water were added to make the solid content 25%, and the mixture was coated on a base paper with a basis weight of 40 g/m ² using a coating rod and dried to obtain a transfer sheet. .

(2) Creation of receipt sheet Oil violet water dispersion (30%) 10
parts, zinc oxide 130 parts, urea-formalin resin 20 parts
1, 67 parts of styrene-butadiene copolymer latex (45%), and 380 parts of water, stirred thoroughly, and coated on base paper with a basis weight of 40 g/m ² using a coating rod and dried to form an almost white coating. I got a receipt sheet.

After the coated side of the obtained transfer sheet and the coated side of the receiving sheet were faced and overlapped, a typewriter IBM82C with a printing pressure of 5 was applied from the transfer sheet side.
When printed, a clear reddish-purple recorded image could be obtained on the receiving sheet.

Example 2 (1) Preparation of transfer sheet 60 parts of an adduct of hexamethylene diisocyanate and trimethylolpropane as a wall-forming substance were added and dissolved in 300 parts of diisopropyl adipate. In this oily solution, 30 parts of carboxymethyl cellulose and 30 parts of polyvinyl alcohol were dissolved.
Add to 550 parts of water at 20℃ with vigorous stirring,
After forming oil droplets with a diameter of 4 to 8 microns, 500 parts of water was added for dilution. Furthermore, 60 parts of ethylenediamine was added and the temperature of the system was raised to 70°C to complete the encapsulation. 100 parts of the obtained microcapsule dispersion, 10 parts of wheat starch, ethylene.
6 parts of vinyl acetate copolymer latex (40%),
After adding 90 parts of water and thoroughly stirring, the mixture was coated on base paper with a basis weight of 50 g/m ² using a coating rod and dried to obtain a transfer sheet.

(2) Creation of acceptance sheet Oil Blue BA (manufactured by Chuo Gosei Kagaku Co., Ltd.)
Color index No. 61555) aqueous dispersion (30
%) 10 parts, titanium oxide 100 parts, paraffin wax emulsion (40%) 120 parts, styrene.
67 parts of butadiene copolymer latex (45%),
After adding 380 parts of water and stirring thoroughly, the basis weight is 50g/
A receiving sheet with an almost white coating layer was obtained by coating a ² m2 base paper using a coating rod and drying it.

After the coated side of the obtained transfer sheet and the coated side of the receiving sheet were faced and overlapped, a typewriter IBM82C with a printing pressure of 5 was applied from the transfer sheet side.
When printed, a blue recorded image was obtained on the receiving sheet.

Claims (1)

[Claims] 1. In a pressure-sensitive recording paper that uses a combination of a transfer sheet and a receiving sheet, the transfer sheet has a transfer layer mainly consisting of microcapsules containing an organic liquid on the back surface, and the receiving sheet has a transfer layer on the surface that is compatible with the organic liquid. A pressure-sensitive recording paper characterized by having a receiving layer mainly containing a soluble colored dye and a white pigment.