A PRESSURE SENSITIVE REPRODUCING MATERIAL

Abstract: The object of the present invention is to provide a pressure sensitive reproducing material which allows reproduced letters or patterns to fade away with the application of water on it. The present invention accomplished the object by a pressure-­ sensitive reproducing material composed of a colored material supported on a substrate, in which the colored material contains cobalt-thiocyanate as a main ingredient.

Description: FIELD OF THE INVENTION The present invention relates to a pressure sensitive reproducing material useful for providing reproduced letters or patterns which fade away with the application of water on it. DESCRIPTION OF THE PRIOR ART Pressure sensitive reproducing materials such as carbon paper in which pigments are applied on substrates of paper or plastic film are already known. With such reproducing materials, desired letters or patterns can be reproduced pressure-sensitively using a pressure applying tool such as ball-point pen, stylus or roulette on a sheet of paper, cloth or the like placed under the reproducing material. The reproduced letters or patterns usually do not fade away, and it is rather difficult to erase them in the case they become unnecesary. For example, in such works as sewing, embroidery or lettering, letters or patterns are drafted using conventional reproducing materials, and the drafted letters or patterns are to be erased at the end of works. The erasing is usually carried out using a rubber eraser or the like, however, the operation is rather troublesome. GB-A 2089827 discloses a transfer paper having thereon a transfer coating comprising cobalt thiocyanate, wax and surfactants. In this preparation, cobalt thiocyanate (crystal) is dissolved in a surfactant to prepare a non-aqueous solution; the solution is mixed thoroughly with a molten wax dissolving a non-ionic surfactant, the molten wax ink is coated on one or both surfaces of a base material (substrate), the transfer coating is cooled and solidified and thus a transfer paper is obtained. Accordingly, the transfer coating is a wax ink composed of a non-aqueous solution of cobalt thiocyanate in a surfactant dispersed in the solid wax. It is, therefore, necessary to remove the wax by washing the sheet bearing the transferred patterns with plenty of water in order to cause ionization of cobalt thiocyanate in the presence of water for erasing the color. In the present invention, the reproducing material is prepared by dipping a substrate in a cobalt thiocyanate solution containing a solvent and a polyalkyleneglycol as a color development enhancer to obtain the clear color tint development of cobalt thiocyanate followed by drying the dipped substrate. Accordingly, the transfer coating (colored material) of the present invention is a solution of cobalt thiocyanate in polyalkyleneglycol and remaining solvent containing no wax. As the polyalkyleneglycol is a hygroscopic materials originally transferred (reproduced) patterns of the transfer coating on a sheet can be erased by simply wiping with a wet paper, since the patterns of the transfer coating solution reacts directly with water. A cloth bearing patterns of transfer coating can be washed with water, but a paper bearing patterns of transfer coating is difficult to be washed with water. Accordingly, the reproducing material (transfer paper) of the present invention can be applied to a paper (such as a case of lettering) as well as to a cloth; on the other hand, the transfer paper of GB-A 2089827 is suitable to be applied to a cloth but unsuitable to be applied to a paper. Although cobalt thiocyanate is employed as the colored material in the present invention, its state of existence in transfer coating and in transferred patterns on a sheet material and the way of being erased by water differ substantially from those of the prior art. FR-A-1506782 also refers to pressure-sensitive reproducing materials. The example on page 3 of FR-A-1506782 also uses cobalt thiocyanate. The cobalt thiocyanate, however, is dispersed in a polyvinyl alcohol solution. The use of a polyalkyleneglycol is not disclosed or rendered obvious by this state of the prior art. SUMMARY OF THE INVENTION The object of the present invention is to provide a pressure sensitive reproducing material which allows reproduced letters or patterns to fade away with the application of water on it. The present invention accomplished the object by a pressure sensitive reproducing material composed of a colored material supported on a substrate, in which the colored material contains cobalt-thiocyanate as a main ingredient, and a polyalkyleneglycol. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention provides an improved pressure-sensitive reproducing material composed of a colored material supported on a substrate, in which the colored material contains cobalt-thiocyanate as a main ingredient. The colored material can be applied on the substrate as a solution to give the pressure-sensitive reproducing material of the present invention. Solvent of the colored material which can be used in the present invention includes water, organic solvent or a mixture of water and organic solvent. The organic solvent includes, for example, methanol, ethanol, ether, aceton, chloroform, ethylacetate. Color of cobalt-thiocyanate solution turns blue when it would come to proper concentration by dissolving it into one of such solvents. The preferable quantity of cobalt-thiocyanate to be added to the solvent is, although it would be varied depending upon the solvent used, generally speaking, 0.1 to 200 parts by weight, preferably 0.5 to 140 parts by weight per 100 parts of solvent. According to the invention polyalkyleneglycol is added to the colored material to obtain the clear color tint development of cobalt-thiocyanate. Polyethyleneglycol, polypropyleneglycol or copolymer of ethyleneglycol and propyleneglycol can be used as polyalkyleneglycol for the purpose and their molecular weight are not limited specifically, but generally 100 to 6,000, preferably 200 to 3,000 are desirable. By adding such a color development enhancer to the solution of cobalt-thiocyanate, it would be possible to get dark blue colored solution, even at the lower concentration such as 5 to 20 weight percent of cobalt-thiocyanate. The colored material which contains cobalt-thiocyanate as a main ingredient can also be prepared by adding nickel-thiocyanate, cobaltchloride and polyalkyleneglycol into a solvent. The preferable quantities of each components to be added to the solvent is, although it would be varied depending upon the solvent used, generally speaking, 0.1 to 120 parts, preferably 0.5 to 50 parts by weight of nickel-thiocyanate, 0.1 to 100 parts, preferably 0.5 to 90 parts by weight of cobaltchloride, 2 to 30 parts, preferably 5 to 20 parts by weight of polyalkyleneglycol per 100 parts by weight of solvent. 5 to 80 parts, preferably 20 to 60 parts by weight of a drying inhibitor or a hygroscopic agent such as glycerin, alkyleneglycol or polyalkyleneglycol per 100 parts by weight of solvent may be added to the colored material to improve the shelf life of the reproducing material, if necessary. Further, such water-soluble macro-molecular substances as polyvinylalcohol, starch, sodium-alginate or carboxymethylcellulose may be added as a binder, if desired. Pressure sensitive reproducing material of the present invention can be prepared by dipping a substrate such as paper (especially filter paper or blotting paper), cloth, hygroscopic rubber, hygroscopic plastic sheet or film into a solution of above-written colored material, then drying it. Dipping conditions might be depending upon the kind of substrate. Generally speaking, if treated substrate was in the state of surface-dry and inside-wet, it is recommendable to pass it through compressed rolls to squeeze the surplus liquid out of it. The reproducing material of the present invention can also be prepared by daubing or spraying the solution of the colored material on the substrate. In this case the solution of the colored material can be applied on one side or both side of the substrate. When a sheet of paper or a piece of cloth is placed under the reproducing material, and pressure is applied using a pencil, ball-point pen, stylus or roulette etc. on the surface of substrate, desired letters or patterns are reproduced on the paper or the like. The letters and patterns thus reproduced fade away with the contact of wet paper, cloth or sponge etc. absorbed water in it. This phenomenon is based on the principle that color of cobalt-thiocyanate disappeares by diluting with enough quantity of water. Accordingly, the reproducing material of the present invention is especially suitable for drafting letters and patterns in the field of sewing, embroidery, lettering and the like. The present invention will be explained in detail hereunder using examples. Example 1. Into 80 milliliter of water, were dissolved successively 15 grams of cobalt-thiocyanate and 25 grams of polyethyleneglycol (molecular weight; 200), and further 50 grams of glycerin one after another to prepare a solution having a blue color. A sheet of blotting paper was dipped into the solution, and the dipped paper was dried to produce a reproducing material. On a sheet of paper or a piece of cloth, was placed the reproducing material, and patterns were drawn on the surface of the reproducing material using a ball-point pen to reproduce on the paper or the cloth blue colored patterns corresponding to those drawn. When the reproduced patterns were wiped through with a wet paper or cloth absorbed small quantity of water, they faded away immediately after. Example 2. Into 100 milliliters of water, were dissolved successively 20 grams of nickelthiocyanate and 15 grams of cobaltchloride, and further were added 30 grams of polyethyleneglycol (molecular weight; 200) and 50 grams of glycerin one after another to prepare a solution having a blue color. A sheet of paper was dipped into the solution, and the dipped paper was dried to prepare a reproducing material. On a piece of cloth or a sheet of paper, was placed the reproducing material and reproduction was performed using ball-point pen to reproduce on the cloth or paper blue colored patterns corresponding to those drawn. When the blue colored patterns on the cloth or paper were wiped with other paper or cloth wetted with water, patterns faded away immediately after wiping with it.

Claims: A pressure sensitive reproducing material composed of a colored material supported on a substrate, in which the colored material comprises cobalt thiocyanate and a polyalkyleneglycol. A pressure sensitive reproducing material as claimed in claim 1, in which the colored material further contains a hygroscopic material or a drying inhibitor. A method of making a pressure sensitive reproducing material composed of a colored material supported on a substrate according to claim 1 or 2, which comprises a step of preparing in situ the colored material by adding nikkel thiocyanate, cobalt chloride and a polyalkyleneglycol into a solvent. A method for making a pressure sensitive reproducing material as claimed in claim 3, in which the solvent contains a hygroscopic material or a drying inhibitor.

Inventors: IIJIMA, ZENSHIRO
Applicants: ADGER KOGYO CO., LTD.
Application year: 1988
Main classification: B41M5
IPC codes: B41M5