Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
2000-09-28
2002-06-04
Hess, Bruce H. (Department: 1774)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C428S195100, C428S208000, C428S913000, C428S914000
Reexamination Certificate
active
06398898
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an ink image-receiving sheet which is excellent in writing property, and on which an image that is excellent in gradation reproducibility and dot reproducibility including variable performance and color clearness can be formed by using a thermal transfer printer, and a method of forming an image wherein the ink image-receiving sheet is used.
With respect to a method of forming a high-definition image through a thermal transfer printer, a method of forming an image comprising: using an image-receiving body having a porous layer, and melt-transferring ink from thermal transfer sheets of yellow, magenta, and cyan, (if necessary, black or the like) thereupon, wherein a heat-meltable ink in a molten state is infiltrated into pores in the porous layer was previously reported in Institute of Television Technical Report, ITE Technical Report, Vol.17, No.27 (May, 1993), p.19-24. Furthermore, as a method of forming a porous layer, the following are known: Wet-solidification method or wet-coagulation method (hereinafter referred to as “wet-solidification method”), which is a method of forming a porous layer wherein a sheet on which a solution of a binder resin in dimethylformamide is applied is dipped into water, thereby replacing the dimethylformamide with water, see JP, B, 49-25430, and JP, A, 5-155163; Mechanically agitating foaming method, which is a method of forming a porous layer wherein a binder resin is mechanically agitated and foamed, and thereafter, the resultant is applied on a sheet, see JP, A, 7-32753, and JP, A, 7-309074; Pigment addition method, which is a method of forming a porous layer wherein a porous pigment is added into a binder resin so as to utilize the oil-absorbing property of the pigment, see JP, A, 3-98333, and JP, B2, 2535371; Solvent-dissolving method or dry method, which is a method of forming a porous layer wherein a binder resin is dissolved into a mixture of a good solvent having a low boiling point and a poor solvent having a high boiling point, and the resultant is dried so that the voids which remain after the poor solvent which is slow in drying is removed by drying form pores, see JP, A, 4-82790, and JP, A, 6-166283; Foaming agent method, which is a method of forming a porous layer wherein a foaming agent which generates a gas upon heating is added into a binder resin, see JP, A, 2-3396; Method of dissolving and removing soluble particles, which is a method of forming a porous layer wherein soluble particles are added into a binder resin and the resultant is formed into a film, and the film is then washed to remove the soluble particles, JP, A, 6-171250; and the like. However, even according to any of those methods, it is difficult to control the state of pores formed in an ink-receiving layer, which is considered to be most important in a thermal transfer of infiltration type, and as a result, there is a problem that the number of pores in the ink-receiving layer is decreased so that an infiltration of ink cannot be sufficiently attained, or a problem that the pore size becomes too large, which exerts a bad influence upon a transfer of fine dots.
Among the above-mentioned methods of forming a porous layer, the wet-solidification method is a method by which a large number of pores can be relatively easily formed in an ink-receiving layer, and thus various technologies have been investigated. Among them, technologies of adding a filler component to a binder component in order to improve the strength of the ink-receiving layer was reported in JP, B, 49-25430 (which discloses wet-solidification using a styrene resin, a plasticizer and a filler), and JP, B, 5-18332 (which discloses wet-solidification using a polyester resin, a plasticizer and a filler). However, even in ink-receiving porous layers formed according to these technologies, pores therein have a too large pore size, and the pores are coarse. Therefore, on thermal transfer printing, an infiltration of ink cannot be sufficiently attained, and thus, it is difficult to form dots in a uniform shape. In particular, when a full-color printing is carried out, a second color ink or subsequent color ink(s) which are to be overlapped with a first color ink or with each other cause an inferior transfer, and thus, it has been difficult to form a high-definition image.
The present inventors have evaluated various types of image-receiving sheets based on the prior art mentioned above. With respect to the mechanically agitating foaming method and wet-solidification method, each of which is considered to largely leave room for improvement from the view point of forming a high-quality image as compared with conventional image-receiving sheets, the characteristics of each of these methods are put in order as follows: Namely, in the case of an image-receiving sheet having an ink-receiving layer comprising a micro-porous layer formed according to the mechanically agitating foaming method, an aqueous coating liquid can be used, and the image-receiving sheet can be formed by merely drying after application of the aqueous coating liquid, and thus this type of image-receiving sheet has the advantage that a paper support can be used, and a support for the image-receiving sheet has a wide range of choice, while communicating pores have a large variation in pore size and a lot of the pores have a large pore size, and thus this type of image-receiving sheet has, for example, the disadvantage that it is difficult to form a sharp dot, small dots in a highlight region cause an outstanding rough appearance, it is difficult to provide a high maximum density, and the gloss of the obtained image is inferior. On the other hand, in the case of an image-receiving sheet having an ink-receiving layer comprising a micro-porous layer formed according to the wet-solidification method, a support of pure paper cannot be used due to the process, and manufacturing costs are high, but from the view point of forming a high-quality image, communicating pores have a small variation in pore size and a little of the pores have a large pore size as compared with the mechanically agitating foaming method, and thus the performance is largely improved. However, in order to stand comparison with a sublimation transfer method or to be superior thereto, a lot of improvement is necessary.
Furthermore, using an image-receiving sheet having an ink-receiving layer comprising a micro-porous layer, which was formed according to the wet-solidification method as disclosed in JP, A, 62-197183, which is one of methods as disclosed in JP, A, 6-286181, the present inventors evaluated the overlapping properties of a second color, a third color and a fourth color. As a result, this type of image-receiving sheet had the disadvantage that a flow of ink and a deficiency of dot were found in a large amount of dots from an intermediate density region to a shadow region. In order to provide a color image having a high-quality, it is very important to evaluate not only the quality of a first color but also overlapping properties of a second color and subsequent color(s). However, as far as the present inventors know, none of conventional technologies as publicly known refer thereto.
It is an object of the present invention to provide an ink image-receiving sheet used in a melting type of thermal transfer recording system, which is excellent in receiving property of transferred ink, and capable of forming thereon an image of a high quality and a high-definition which is excellent in dot reproducibility and gradation property, in particular when a full-color printing is carried out.
Another object of the present invention is to provide an ink image-receiving sheet having a surface layer wherein a lot of pores having an average pore size of preferably 1 to 5 &mgr;m and a small variation in size and shape are formed.
A still another object of the present invention is to provide an ink image-receiving sheet which is excellent in writing property.
A further object of the present invention is to provide a method of
Fukui Takuto
Suematsu Hideki
Suzuki Kyoichi
Yamane Toshiyuki
Fish & Neave
Fujicopian Co. Ltd.
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