Coating processes – Direct application of electrical – magnetic – wave – or... – Pretreatment of substrate or post-treatment of coated substrate
Reexamination Certificate
2000-07-06
2002-12-24
Bareford, Katherine A. (Department: 1762)
Coating processes
Direct application of electrical, magnetic, wave, or...
Pretreatment of substrate or post-treatment of coated substrate
C427S541000, C427S553000, C427S557000, C427S395000, C427S411000, C427S420000
Reexamination Certificate
active
06497926
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of producing an information recording material, particularly to a method of producing, with good productivity, an information recording material such as a thermal recording material and an inkjet recording material excellent in various properties and excellent in coating qualities in particular.
2. Related Art Statement
Information recording materials having an information-recording layer formed on a substrate are used in broad fields. A variety of recording materials such as a pressure-sensitive recording material, a thermal recording material, a thermal transfer recording material, an inkjet recording material, etc., are practically used as such information recording materials. In recent years, information recording materials having two or more layers formed on a substrate are also used due to demands for higher functions and higher performances.
A thermal recording material is generally a material in which a heat-sensitive recording layer containing a thermally color-formable material is formed on a substrate. An image is formed by heating it with a thermal head, a thermal pen, laser light, or the like. The thermal recording material is disclosed in Japanese Patent Publications Nos. 43-4160, 45-14039 and the like.
The above thermal recording material is advantageous in that a recording can be obtained with a relatively simple unit, that maintenance is easy and that no noise is made, so that it is widely used in the fields of measuring recorders, facsimile machines, computer terminals, labels, automatic vending machines of tickets, etc. In recent years, further, for attaining superior color density and sensitivity, image stability and tones of a plurality of colors, there is practically used a thermal recording material prepared by applying a protective layer, an undercoat layer and two or more heat-sensitive recording layers, in addition to a thermal recording material having a single heat-sensitive recording layer alone.
An inkjet recording method is a method in which fine globules of an ink are ejected from an inkjet recording device and allowed to adhere to an inkjet recording material to form an image or letters. As the above inkjet recording material, a material having no ink receptor layer such as a non-coated paper is sometimes used. However, a material prepared by forming an ink receptor layer on a substrate is used when printing is made on a synthetic resin film having no ink-reception properties or when it is intended to obtain a finer image. With diversification in use, color imaging or higher performances such as faster printing in recent years, a larger amount of an ink is ejected, and a higher-capacity ink absorption and a higher print density come to be required. Since no sufficient performances for the above requirements can be obtained with any conventional single ink receptor layer, an inkjet recording material having two or more ink receptor layers are practically used as well.
In a conventional information recording material having two or more layers laminated on a substrate, each layer is independently formed by application and drying to form the laminated layers, and the application is carried out by a method such as an air knife coating method, a blade coating method, a rod coating method or a reverse roll coating method. However, an information recording material prepared by any one of the above methods has problems that its coating quality is poor, that an upper layer has pin holes caused by infiltration of an upper layer coating color into a lower layer and repellency during application to form the upper layer and that the quality varies due to continuous coating for a long period of time. Moreover, there are problems in a limit to application at a high rate and a decrease in productivity due to application procedures to be carried out a plurality of times.
As compared with these methods, the curtain coating method disclosed in Japanese Patent Publications Nos. 49-24133 and 49-35447 is an application method in which a free-fall curtain of a coating color is formed and allowed to collide with a substrate, and it is known that the curtain coating method is suitable for application at a high rate. Further, since a plurality of layers can be simultaneously formed by forming a coating composition film made of a plurality of coating color layers, the productivity in multi-layer application can be improved to a great extent. In the simultaneous multi-layer application using a curtain coating method, the coating composition film made of a plurality of coating color layers is formed on a substrate, and thereafter, it is required to dry the coating composition film to solidness without disordering the layer structure thereof. In the field of conventional photographic photosensitive materials prepared by simultaneous multi-layer application using a curtain coating method, each coating color contains gelatin as a binder, and coating composition layers are cooled immediately after coating composition solutions are transferred onto a substrate, so that the gelatin in the coating colors gelled and that the coating composition solution are immobilized, whereby no intermingling of the layers takes place.
DISCLOSURE OF THE INVENTION
Under the circumstances, it is an object of the present invention to provide a method of producing an information recording material having at least two layers laminated on a substrate, with good productivity, in which pinholes in an upper layer and the variability in coating qualities, caused by the infiltration of a coating color for the upper layer into a lower layer and repellency during application for forming the upper layer, are inhibited and the information recording material is excellent in coating qualities and are excellent in various properties.
The present inventors have therefore made diligent studies for achieving the above object, and as a result, it has been found that the above object can be achieved by forming a coating composition film made of a plurality of coating color layers on a substrate by curtain coating and drying the coating composition film to form part or all of layers for forming an information recording material, and either (1) by adjusting the viscosity of each of the coating colors for a plurality of the coating color layers to a certain value or above and controlling the surface tension of the coating color for a lowermost layer so as to bring it into a specific range or (2) by controlling the density of the coating color for each layer for forming a plurality of the coating color layers. The present invention has been completed on the basis of the above findings.
That is, (1) according to the present invention, there is provided a method of producing an information recording material having at least two layers laminated on a substrate, which comprises forming a coating composition film made of a plurality of coating color layers on a substrate by curtain coating and drying the coating composition film, to form part or all of layers for forming the information recording material, wherein the coating colors for a plurality of the coating color layers during application have a viscosity of at least 100 mPa·s and the coating color for a lowermost layer of a plurality of the coating color layers has a surface tension of 18 to 45 mN/m (to be referred to as “Production method I of the present invention” hereinafter).
(2) According to the present invention, there is also provided a method of producing an information recording material having at least two layers laminated on a substrate, which comprises forming a coating composition film made of a plurality of coating color layers on a substrate by curtain coating and drying the coating composition film, to form part or all of layers for forming the information recording material, wherein a coating color for a layer to be positioned above has a density which does not exceed 140% of the density of a coating color for a layer to be positioned below and adjacent ther
Maruyama Toshihito
Yokota Yasuro
Bareford Katherine A.
Mitsubishi Paper Mills Ltd.
Nixon & Vanderhye P.C.
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