Radiation imagery chemistry: process – composition – or product th – Transfer procedure between image and image layer – image... – Imagewise heating – element or image receiving layers...
Reexamination Certificate
2001-08-01
2002-11-05
Schilling, Richard L. (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Transfer procedure between image and image layer, image...
Imagewise heating, element or image receiving layers...
C430S201000, C430S207000, C430S256000, C430S259000, C430S262000, C430S263000
Reexamination Certificate
active
06475695
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an intermediate image receiving sheet for a thermal transfer recording method. More specifically, the present invention relates to an intermediate image receiving sheet for a laser thermal image transfer recording method, which can easily transfer the image and yield a high quality transfer image without image defects, and is suitable for various kinds of paper, resulting in high quality proofs.
BACKGROUND OF THE INVENTION
In recent years, a need for direct digital color proofs (DDCP) has been raised particularly, in the field of printing in accordance with the spreading use of image forming technology employing digital data. In the DDCP process, laser thermal transfer technology is used to satisfy the requirements of high color reproducibility and stable repeatability.
The laser thermal transfer technology has already been disclosed. It is structured to use,
(i) an ink sheet comprising a light-heat conversion layer and a ink layer containing a dye,
(ii) an image receiving sheet comprising an ink receiving layer and a thermoplastic layer.
The ink layer face of (i) and the ink receiving layer face of (ii) are superposed, then imagewise exposed with a laser beam from the rear of the ink sheet. The ink layer is thermally transferred to the image receiving layer by a light-heat conversion effect, and then the image, transferred onto the receiving layer is further transferred onto a final image forming material.
The above-mentioned DDCP process enables printing out the final image on the same kind of paper used for a production run. The print produced with this process can be used as a final proof sample, due to the similarity to prints employing dot printing, the use of print ink pigments, and the use of the same kinds of paper used for a production run.
A variety of papers may be used for a production run such as art paper, coated paper, matt paper, fine coated paper, and uncoated paper. Recently, there has been an increasing demand to use the above-mentioned paper for the DDCP process.
However, when the softening ability or the fluidity of the thermoplastic layer in the image receiving sheet is enhanced under a heated condition in order to increase the transferring ability of the above-mentioned image receiving sheet onto matt paper or uncoated paper, the adhesiveness of the thermoplastic layer increases even at normal temperature. This results in an increase of the adhesion property between the paper and the image receiving sheet during the transferring process and the peeling process, causing problems such as tearing of the paper.
Because of the above-mentioned defect, the enhancement of the softening ability or the fluidity can not be considered the desired solution to achieve the preferred objective.
A composition for an image receiving sheet is disclosed in Japanese Patent Publishing Open to Public Inspection (JP-A) No. 9-52458. Said disclosed composition is: a support/a cushion layer/a releasing layer/and an image receiving layer. The thermoplastic property of the cushion layer and the stickiness of the image receiving layer is not directly related in this composition. Therefore, a variety of cushion layers can be chosen in this composition. One can even use a thermoplastic material in the cushion layer which has a tack property at normal temperature. However, the releasing layer prevents the cushion layer from closely contacting a rough surfaced paper. As a result, a satisfactory transfer property cannot be realized when this technology is applied to matt paper, uncoated paper such as fine-quality paper or medium-quality paper.
Another technology is disclosed in JP-A No. 2001-47753. When said technology was applied, it was found that the force required to peel the image receiving layer from the final image forming material was too high, and often resulted in damaging the surface thereof.
OBJECT OF THE INVENTION
The object of the present invention is to provide an intermediate image receiving sheet for a laser thermal transfer recording method, which can easily transfer an image to even a rough surface paper with high quality and stable repeatability, and can use a variety of papers to produce an image proof which yields results similar to a print made in a production run.
SUMMARY OF THE INVENTION
The object of this invention can be achieved by the following compositions.
1. An intermediate image receiving sheet, comprising:
(i) a support;
(ii) a thermoplastic layer which is capable of being thermally softened; and
(iii) an image receiving layer which is capable of receiving an image from an image recording material; wherein the intermediate image receiving sheet is capable of transferring the image and the image receiving layer to a final image forming material by a process of applying heat or pressure to the intermediate image receiving sheet, and a force to peel the image receiving layer transferred to the final image recording material from a leaving portion on the support side is 1 to 100 g/cm, the force being measured with a material whose Bekk smoothness is 0 to 15 seconds at 25° C. and RH 50%, defined by JIS P8119
2. The intermediate image receiving sheet of item 1, wherein the force is 10 to 100 g/cm.
3. The intermediate image receiving sheet of item 2, wherein the force is 10 to 50 g/cm.
4. The intermediate image receiving sheet of item 1, wherein the intermediate image receiving sheet further comprises a releasing layer, which is capable of reducing the force and is provided between the thermoplastic layer and the image receiving layer, and the force to peel the image receiving layer transferred to the final image recording material from the releasing layer is 1 to 100 g/cm.
5. The intermediate image receiving sheet of item 4, wherein the releasing layer contains a binder resin in an amount of not less than 50% by weight of the releasing layer, and the binder resin in the releasing layer has a different SP value of 1 to 20 from that of a binder resin used in the image receiving layer.
6. The intermediate image receiving sheet of item 4, wherein the thermoplastic layer contains a binder resin in an amount of not less than 50% by weight of the thermoplastic layer, and the binder resin meeting the following requirements:
(i) a TMA softening point of 30 to 100° C.,
(ii) a melting point of 80 to 150° C.,
(iii) a difference between the melting point and the TMA softening point of less than 50° C.
7. The intermediate image receiving sheet of item 4, wherein the releasing layer contains a binder resin in an amount of not less than 50% by weight of the releasing layer, and having a TMA softening point of the binder resin of 120 to 300° C.
8. The intermediate image receiving sheet of item 4, wherein a thickness of the releasing layer is 0.3 to 6.0 &mgr;m.
9. The intermediate image receiving sheet of item 4, wherein a thickness of the image receiving layer is 0.1 to 3.0 &mgr;m.
10. The intermediate image receiving sheet of item 9, wherein a thickness of the image receiving layer is 0.2 to 2.5 &mgr;m.
11. The intermediate image receiving sheet of item 1, wherein the image receiving layer is placed on the thermoplastic layer which is placed on the support, and a force to peel the image receiving layer transferred to the final image recording material from the thermoplastic layer is 1 to 100 g/cm.
12. The intermediate image receiving sheet of item 11, wherein the thermoplastic layer contains a binder resin in an amount of not less than 50% by weight of the thermoplastic layer, and the binder resin meeting the following requirements:
(i) a TMA softening point of 30 to 100° C.,
(ii) a melting point of 80 to 150° C.
(iii) a difference between the melting point and the TMA softening point of less than 50° C.
13. The intermediate image receiving sheet of item 11, wherein a thickness of the image receiving layer is 0.5 to 10.0 &mgr;m.
14. The intermediate image receiving sheet of item 13, wherein a thickness of the image receiving layer is 0.8 to 8.0 &mgr;m.
15. The intermediate image receiving sheet of item 11, wherein the i
Kuroki Takaaki
Maehashi Tatsuichi
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