JPH0218146B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a glossy printing sheet material, and its purpose is to provide printing that has sufficient gloss while further improving the absorption of printing ink applied to the surface. It is easy to provide sheet materials for use. Examples of sheet materials for printing include paper, nonwoven fabric, etc., but the most common paper will be described. Glossy printing paper called art paper, coated paper, etc. has a coating layer made of pigment and binder on one side of the paper, and this is calendered to make it glossy. In addition, in order to make the paper retain even more gloss, that is, strong gloss, a gloss layer is provided on the above-mentioned coating layer using a substance such as casein, and a thermoplastic synthetic resin is further added as the gloss layer. Attempts have been made to make the gloss stronger by using However, although the formation of this glossy layer improves the gloss, it goes without saying that when printing, the printing ink is applied on top of this glossy layer, so the drying of the printing ink is slow, and Since the printing ink is poorly absorbed by the glossy layer, it has the disadvantage of poor adhesion of the ink to the paper surface, and this tendency is particularly pronounced when offset printing is performed compared to when using other printing methods. In this way, printing suitability, which is the drying of printing ink and adhesion quality depending on the quality of absorption of printing ink, and gloss can basically be said to be contradictory suitability. There is a type of printing paper that balances gloss and printability, but there is something called cast-coated paper, which is paper with the above-mentioned coating layer on top of the paper, which is specially coated to make it glossy. Since it is a paper that has undergone extensive post-processing and does not have the above-mentioned gloss layer, it has the disadvantage of poor water resistance. In other words, paper having the above-mentioned glossy layer on the top surface produces a desirable gloss depending on the material of the glossy layer, and this glossy layer also serves as a waterproof layer.
Although it can be said to have excellent water resistance, cast-coated paper only consists of two layers: paper and a coating layer, and it does not have a gloss layer that is a layer for gloss and a layer for waterproofing. However, the paper as a whole has poor water resistance. Furthermore, since this cast coated paper requires special equipment and techniques, it also has the disadvantage that it is difficult to easily provide it at low cost. The inventors of the present invention have conducted extensive research and conducted various experiments in order to easily and inexpensively obtain a printing paper that has a desirable gloss, has good absorption of printing ink, has good ink adhesion, and is suitable for printing. (1) A method for producing a glossy printing sheet material, which involves applying an emulsion or latex made of a mixture of two or more thermoplastic resins having different minimum film forming temperatures to the surface of a substrate, and then drying it; (2) After applying an emulsion or latex made of a mixture of two or more thermoplastic resins with different minimum film forming temperatures to the surface of the base material, on this coated surface,
A method of producing glossy printing sheet materials by applying heat and pressure using a smooth surface. By doing so, the purpose was successfully achieved. The first invention, which is the former, imparts a preferable gloss and good printing properties to the printing sheet material, and the second invention, the latter, imparts a more preferable strength to the printing sheet material. To provide a method for easily and inexpensively providing a printing sheet material that skillfully balances the contradictory properties of gloss and printability, which can provide gloss and exhibit good performance without impairing its printability. be. In the present invention, the base material refers not only to paper but also to paper coated with a mixture of color pigment and binder. In the present invention, the fact that the minimum film forming temperatures are different means that, for example, the minimum film forming temperatures of two types of thermoplastic synthetic resins to be mixed are not equal to each other, and that the minimum film forming temperatures of two types of thermoplastic synthetic resins to be mixed are not equal to each other. In this case, the minimum film forming temperatures of the two types of thermoplastic synthetic resins need not be equal to each other, and even if there are four or more types of thermoplastic synthetic resins to be mixed, the minimum film forming temperature of the two types of thermoplastic synthetic resins should not be the same. It is similar to In the present invention, these two or more types of thermoplastic synthetic resins having different minimum film forming temperatures are applied as a mixture thereof, and this mixture is applied as an emulsion or latex, but the application method can be arbitrary. . Further, the coating may be applied not only to one side of the substrate but also to both sides. In the present invention, a mixture of two or more thermoplastic synthetic resins having different minimum film forming temperatures is applied as an emulsion or latex to the surface of the substrate. This drying may be done by leaving it to dry naturally or by air drying, or by heating, or drying may be carried out together with application. After coating the surface of the substrate with an emulsion or latex consisting of a mixture of two or more thermoplastic synthetic resins with different minimum film-forming temperatures, the surface of the printing sheet material becomes glossy by drying. Moreover, it is modified into a printing sheet material with good printing ink absorption and excellent ink adhesion, and good printability, but the desirable gloss on the surface of this material is not due to the thermoplastic synthetic resin. However, when the applied emulsion or latex dries, the printability is improved by the film-forming action of the emulsion or latex. Since these are mixtures with different minimum film-forming temperatures, extremely fine cracks occur on the film-forming surface, and a portion of the printing ink brought to the surface during printing is absorbed into these cracks. The ink is absorbed well and dries quickly. The inventors have not yet elucidated the reason why this crack occurs. As mentioned above, the cracks that occur on the surface of the film are extremely minute, cannot be seen with the naked eye, and do not affect the whiteness or gloss of the entire surface. When printing with printing ink, very good results can be obtained not only in the absorption and adhesion of the printing ink adhering to the surface but also in drying. This gloss and printability can be achieved by applying the emulsion or latex described above to the surface of the sheet material, or by applying a mixture of pigment and binder to the surface of the sheet material. As mentioned above, it may be the same. Thermoplastic synthetic resins preferably used in the present invention include, for example, styrene resin, a copolymer of styrene and acrylic, an acrylic resin, a copolymer of acrylic and vinyl acetate, a copolymer of ethylene and vinyl acetate, and SBRMBR. , NBR, etc., but are not limited thereto. The second invention is an invention that is effective when it is desired to impart stronger gloss to the printing sheet material obtained by the first invention, and is an invention in which the minimum film forming temperature is different on the surface of the base material. The application of an emulsion or latex made of a mixture of two or more thermoplastic synthetic resins is the same as the first invention, but in the second invention, the surface to which the emulsion or latex is applied is heated. It is characterized by applying pressure using a smooth surface, which gives the printing sheet material both high gloss and excellent printability. In this case, the heating is performed to completely melt the thermoplastic synthetic resin with the lowest minimum film forming temperature among the mixed thermoplastic synthetic resins, and to melt only a portion of the thermoplastic synthetic resin with the high minimum film forming temperature. If so, it is extremely preferable. Further, the pressure applied by the smooth surface is performed by, for example, being pressed against a mirror-finished smooth roll. In this case, if this smooth roll is used as a heating roll,
Heating and pressurization will be applied simultaneously. In this case, even if heat and pressure are applied, cracks that occur on the film forming surface are slightly affected, but not to the extent that they cause a decrease in printability. Items used for this pressurization include a metal roll with a smooth surface and a metal plate with a smooth surface, but even in these cases, it is preferable that the surface is finished as smooth as possible. According to the present invention, a mixture of two or more thermoplastic synthetic resins having different minimum film forming temperatures is placed on a base material as an emulsion or latex,
All you have to do is apply it, and in order to obtain a strong gloss, you just need to heat it and pressurize it with a smooth surface.It does not require any special equipment or technology, and can be provided easily and inexpensively. Moreover, while the printing sheet material obtained by the present invention has sufficient gloss, it has extremely improved printing ink absorption and adhesion, which is higher than conventional gloss and printing ink absorption. Although these were understood to be mutually exclusive, this is an excellent invention that can provide a printing sheet material that satisfies both. Next, the present invention will be explained in more detail with reference to Examples. As a base material, coat bleached kraft paper with 100 parts of clay, 70 parts of calcium carbonate, 30 parts of titanium dioxide, and 40 parts of carboxyl-modified SBR to give a coating weight of 15 g/m ² with an undercoat with a total solids content of 60%. Using evenly coated paper, emulsions of two types of thermoplastic synthetic resins with different minimum film-forming temperatures (Test Groups No. 1 to 6) and latex (Test Group No. 7) were applied on top of this undercoat paint. The results of testing the gloss of the printing sheet material obtained by applying it uniformly to a coating weight of 5 g/m ² and the ink absorption when printing on this printing sheet material are as follows. It was hot.

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Claims (1)

[Claims] 1. Glossy printing characterized by coating the surface of a substrate with an emulsion or latex made of a mixture of two or more thermoplastic synthetic resins with different minimum film forming temperatures and then drying. Manufacturing method of sheet material for use. 2. After applying an emulsion or latex made of a mixture of two or more thermoplastic synthetic resins with different minimum film-forming temperatures to the surface of the base material,
A method for producing a glossy printing sheet material, which is characterized by applying heat and pressure to the coated surface using a smooth surface. 3. The method for producing a glossy printing sheet material according to claims 1 and 2, wherein the base material is a single sheet material such as paper, nonwoven fabric, etc. 4. The glossy material according to claims 1 and 2, wherein the base material is a sheet-like material such as paper, nonwoven fabric, etc., coated with a mixture of a pigment and a binder. A method of manufacturing certain printing sheet materials.