JP2976536B2 - Image receptor for thermal transfer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer image receiving member used for thermal transfer recording. More specifically, the present invention provides
The present invention relates to a thermal transfer image receiving body which heats with a thermal head or the like on a thermal transfer paper having a coloring material layer containing a sublimable dye and sublimates and transfers the sublimable dye to a dyeing resin layer to perform color recording.

[0002]

2. Description of the Related Art In recent years, with the spread of information terminals such as personal computers, word processors, televisions, VTRs, and video disks, the use of display devices such as color displays has been rapidly expanding. Accordingly, the demand for a printer that outputs a still image as a color image is increasing year by year. As a recording system of such a full-color printer, there are an electrophotographic system, an ink jet system, a thermal transfer system, and the like. Of these, the thermal transfer method is widely used because it has no noise and the maintenance of the apparatus is easy.

[0003] Thermal transfer is performed by combining a fixed color ink sheet and an image receiving paper, and uses thermal energy controlled by an electric signal from a laser, a thermal head, or the like, to form an ink on the thermal transfer paper (ink sheet). It is classified into a hot-melt transfer type in which (color material) is hot-melt-transferred to a thermal transfer image-receiving paper and a sublimation transfer type in which sublimation transfer is performed.

In the case of the thermal melting transfer type, a thermal transfer recording sheet in which a dye or a pigment is bound by a thermal fusible substance (generally a wax) is used, and a coloring material layer melted by thermal energy of a thermal head or the like is used as an image receiving material for thermal transfer. Transfer to body. However, this method generally has disadvantages in that it is difficult to obtain a halftone, it is difficult to obtain a good hue due to the transferred hot-melt substance, and the surface has low abrasion resistance.

[0005] On the other hand, sublimation transfer type thermal transfer using a sublimable or vaporizable dye is an application of a conventional sublimation printing technique. In this method, an image is formed by using a heat-sensitive transfer paper to which a disperse dye which easily sublimates is bound by a binder, and sublimating and transferring the dye to a thermal transfer image receiving body by the thermal energy of a thermal head. This method has the advantage that during printing, the amount of sublimable dye corresponding to the amount of thermal energy of the thermal head sublimates, so that halftones can be easily obtained and the gradation can be controlled arbitrarily. It is considered to be the most suitable method.

Conventionally, as a sublimation transfer type thermal transfer image receiving body, a dyeing resin layer made of a thermoplastic resin such as a saturated polyester resin, a polyamide resin, or an epoxy resin which is effectively dyed to a sublimable dye is used. An image receiving member provided on a substrate has been proposed (JP-A-57-107885). However, in recent years, various studies have been made on high-speed printing using a thermal head using high heat energy in order to secure a sufficient printing speed against other recording methods such as a thermal fusion transfer method and an electrophotographic method. The temperature of such a thermal head may reach as high as 200 ° C. or more during printing, and the coloring material layer of the thermal transfer paper and the dyeing resin layer of the thermal transfer image receiving member are fused to each other. Abnormal transfer of the dye to the dyed resin layer or poor running of the thermal transfer paper or the thermal transfer image receiving member may be caused.

Conventionally, in order to prevent such abnormal transfer due to fusion, a method of adding a release compound such as silicone to the surface or inside of the dyeing resin layer, a method of using a thermosetting resin alone, A method of cross-linking with a thermoplastic resin to improve the heat resistance of the dyed resin layer has been attempted. However, there has been a demand for a thermal transfer image receiving body having better heat resistance so that stable printing can be performed at higher speed.

For example, when an epoxy resin is used as a dyeing resin, a bisphenol A type epoxy resin having a large epoxy equivalent (molecular weight) and high heat resistance is used together with a release compound to prevent abnormal transfer. Alternatively, epoxy resins are crosslinked using an amine-based curing agent or the like. Examples of the former include a bisphenol A type epoxy resin having an epoxy equivalent of about 2000 to 3000 and a melting point of about 120 to 160 ° C. by a Durance method.

[0009]

However, if a highly heat-resistant resin is used as the dyeing resin in order to prevent abnormal transfer, the dyeing resin is not sufficiently used in a region where the thermal energy of the thermal head is relatively low. The dye is dyed without being softened. For this reason, the print density of the low gradation portion becomes non-uniform, and print unevenness and print blur occur. Also, since the dye is dyed only on the surface of the dyed resin layer and the dye does not sufficiently diffuse into the dyed resin layer, for example, the light resistance under light irradiation conditions and the cover when stored in an album The storability of the photographic printing paper decreases, such as the occurrence of back fogging on the film. Further, when a coated paper such as art paper or coated paper having low cushioning properties or a hard plastic film such as a polyester film is used as the base material of the image receiving paper, the printing unevenness and print blurring become more remarkable.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a heat transfer material having excellent heat resistance which does not cause abnormal transfer in a high gradation area, and excellent dyeing properties with less printing unevenness and print blur in a low gradation area. An object of the present invention is to provide a receiver.

[0011]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve both abnormal transfer of a high gradation area and nonuniformity of print density in a low gradation area. By using a dyeing resin having a rubbery polymer introduced therein, it has been found that both high heat resistance and excellent dyeing properties of the dye can be achieved, and the present invention has been completed.

That is, the present invention relates to a thermal transfer image receiving body which receives a transfer of a sublimable dye from a thermal transfer paper provided with a coloring material layer containing a sublimable dye by heating the epoxy resin with a carboxyl group-containing rubber polymer. An object of the present invention is to provide a thermal transfer image receiving member provided with a dyeing resin layer containing a rubber-modified epoxy resin obtained by a reaction. Hereinafter, the present invention will be described in detail.

As the epoxy resin used for the production of the rubber-modified epoxy resin, bisphenol A type epoxy resin is preferable, but other cyclic aliphatic epoxy resin, hydantoin type epoxy resin, novolak type epoxy resin, glycidyl ester type epoxy resin are also available. Resins and the like may be used alone or in combination of two or more. The epoxy equivalent of the epoxy resin is usually about 500 to 3500, and preferably has an average of two or more epoxy groups in one molecule.

On the other hand, the carboxyl group-containing rubbery polymer used in the present invention includes a carboxyl group-containing butadiene-acrylonitrile copolymer, a carboxyl group-containing polybutadiene, a carboxyl group-containing butadiene-acrylonitrile-acrylate copolymer, and a carboxyl group-containing copolymer. Butadiene-acrylic acid ester copolymer, carboxyl group-containing isoprene-methacrylic acid ester copolymer, carboxyl group-containing polyisoprene, carboxyl group-containing butadiene-styrene-acrylic acid ester copolymer, carboxyl group-containing butadiene-isoprene-acrylic acid Ester copolymers and the like can be mentioned. Of these, butadiene having a terminal carboxyl group-
Those having a carboxyl group at the molecular terminal, such as acrylonitrile copolymer and polybutadiene having a terminal carboxyl group, are particularly preferred. Commercial products of these rubbery polymers include, for example, the Hiker CTBN series (Goodrich, USA). The carboxyl group-containing diene rubbery polymer has a molecular weight of 1,000.
~ 100,000, preferably 1,000 ~ 10,000
0, particularly preferably in the range of from 1,500 to 5,000 and the number of carboxyl groups per molecule is from 1.4 to 10
, Preferably 1.6 to 2.4.

To produce the rubber-modified epoxy resin used in the present invention, the epoxy resin is reacted with a rubbery polymer in the presence or absence of a catalyst.
As a catalyst, 0.05 to 0.2 parts by weight of triphenylphosphine or the like is added to 100 parts by weight of the epoxy resin. The reaction is carried out by melting and mixing at about 70 to 160 ° C. for about 0.5 to 4 hours. An epoxy resin composition may be obtained by adding a normal epoxy resin that does not undergo rubber modification to the rubber-modified epoxy resin.

The content of the rubber component in the epoxy resin composition is preferably from 3 to 50% by weight. The rubber component content is the amount of the epoxy resin used in producing the rubber-modified epoxy resin in part A, and the carboxyl group-containing rubbery polymer in B
Parts, the amount of epoxy resin additionally added to the rubber-modified epoxy resin is defined as part C, and expressed as B / (A + B + C) × 100. When the content of the rubber component is lower than 3% by weight, the flexibility of the composition is low, and uneven printing, blurring of printing, or dyeing of the dye on the surface of the dyeing resin layer are not sufficient. When the content of the rubber component is higher than 50% by weight, heat resistance,
Problems such as inferior adhesion and coloring of the rubber component become remarkable.

The epoxy resin composition of the present invention comprises
As long as the transparency required for the dyeing resin layer is not impaired, various known additives such as an antioxidant, a fluorescent brightener, an adhesion improver, an antistatic agent, and a filler may be further compounded. .

The introduction of the rubbery polymer into the epoxy resin composition makes it possible to ensure the heat resistance and the dyeability of the dyeing resin because of the flexibility and molecular weight of the epoxy resin molecules. This is considered to be due to the increase in the temperature and the gradual softening and melting of the thermal head in response to a temperature change from a low temperature to a high temperature. Also, it is considered that remarkable liquefaction flow is suppressed even in the molten state, the gradation becomes smooth, and abnormal transferability at high temperature is improved.

In the image receiving body of the present invention, the dyeing resin layer may be formed as a single layer of an epoxy resin composition containing a rubber-modified epoxy resin. Further, in order to further enhance the effect of the present invention, a dyeing of a multilayer structure in which an epoxy resin composition containing a rubber-modified epoxy resin is used as a first layer and an epoxy resin having a higher heat resistance than the second layer is used as a second layer. A resin coating layer may be formed. In the case of a dyeing resin layer having a two-layer structure, the first layer may be provided on the base material side, and the second layer may be provided thereon, or vice versa.

As the base material of the image receiving body for thermal transfer of the present invention,
Plain paper such as medium paper and woodfree paper; coated paper such as art paper and coated paper; plastic film such as nylon, polyester, polyimide, polyvinyl chloride, polycarbonate, polystyrene, polypropylene or synthetic paper made from them; Examples include plain paper coated with synthetic resin or synthetic paper, coated paper, metal-deposited or laminated paper or sheet, and the like.

As a method of applying the dyeing resin on these substrates, a coating method such as gravure coating, roll coating such as reverse, wire bar coating, and fauten coating is used. The coating thickness of the dyed resin layer is usually set to about 4 to 10 μm.

[0022]

Next, the present invention will be described more specifically with reference to examples and comparative examples. The image receiving bodies obtained in Examples and Comparative Examples were evaluated by the following methods using the thermal transfer paper obtained in the following Production Examples. In the following, “parts” means “parts by weight”.

[Production Example] (Thermal transfer paper): 10 parts of a sublimable disperse dye (Kayaset Red 126, manufactured by Nippon Kayaku Co., Ltd.)
An ink liquid composed of 10 parts of a polyamide resin (Hasaron 1140, manufactured by Henkel Hakusui), 40 parts of toluene, and 40 parts of isopropyl alcohol was dispersed by ultrasonic waves for 6 hours.
This ink liquid was applied using a gravure coater on a 6 μm polyester film so that the dry coating amount was 2 g / m ^2, and dried to form a color material layer, thereby obtaining a thermal transfer paper.

[Printability of Low Gradation Area] A 1 cm ² circle set at 110 ° C. from the back side of the thermal transfer paper by bringing the color material layer of the thermal transfer paper into contact with the dyeing layer of the thermal transfer receiver. Was pressed at a pressure of 1 kg / cm ² for 0.2 seconds to thermally transfer the sublimable disperse dye onto the dyeing layer of the image receiving body for thermal transfer. Regarding printability, the dyeing state of the dye on the dyeing layer of the image receiving body for thermal transfer was evaluated on the basis of the following three grades A to C.

A: Uniformly and uniformly dyed, non-dyed white blank portions are less than 15% of the total print area. B: 15% or more and less than 50% of unstained white dropouts. C: 50% or more of the non-dyed white blank portion.

[Anomalous Transfer Resistance of High Gradation Area] The color material layer of the heat-sensitive transfer paper is brought into contact with a dyeing layer of a thermal transfer image-receiving body.
A 1 cm ² circular thermal plate set at 250 ° C. was pressed from the back side of the thermal transfer paper at a pressure of 1 kg / cm ² for 0.2 seconds to thermally transfer to a thermal transfer image receptor. The abnormal transfer resistance was evaluated by observing the fusion state between the thermal transfer image receiving body and the thermal transfer paper immediately after the thermal transfer, and evaluated by the following three grades I to III.

I: Thermal transfer paper does not fuse to thermal transfer image receiving paper at all. II: Thermal transfer paper is fused to thermal transfer image receiving paper but can be peeled off. III: The thermal transfer paper is fused to the thermal transfer image receiving paper and cannot be peeled off.

Example 1 Epicoat 1007 (Epoxy resin manufactured by Yuka Shell Epoxy Co., Ltd., molecular weight: about 3,000)
80 parts and Hycar CTBN 1300 × 8 (BF Goodrich Co., Ltd., butadiene-acrylonitrile copolymer rubber, molecular weight about 3,400, average carboxyl group number 1.9)
(Molecule) 20 parts was reacted at 140 ° C. for 3 hours in a dissolving mixer to obtain a rubber-modified epoxy resin. 15 parts of Epicoat 1007 was added to 5 parts of this rubber-modified epoxy resin,
The rubber component content was 5% by weight. Further KF-393
(Shin-Etsu Chemical Co., Ltd. amino silicone) 0.5 part, X
-22-343 (Epoxy-modified silicone manufactured by Shin-Etsu Chemical) 0.5 part, methyl ethyl ketone 60 parts, toluene 2
A dyeing resin solution consisting of 0 parts was prepared.

As a substrate for a thermal transfer receiver, a thickness of 150 μm
m of polypropylene synthetic paper YUPO FPG-150 (manufactured by Oji Yuka Synthetic Paper Co., Ltd.), and applying the above-mentioned dyeing resin onto the surface thereof using a wire bar so that the dry coating amount is 10 g / m ^2. , Dried at 110 ° C for 3 minutes and then at 50 ° C
For 24 hours to prepare an image receiving body for thermal transfer. The obtained thermal transfer image-receiving body and the thermal transfer paper obtained in the production example were combined, and the printability of the low gradation portion and the abnormal transfer resistance of the high gradation portion were evaluated by the above-described evaluation method. Table 1 shows the results.

Example 2 In Example 1, the mixing ratio of the rubber-modified epoxy resin and Epicoat 1007 was changed to 10
A dyeing resin liquid was prepared in the same manner as in Example 1 except that the ratio of the rubber component was changed to 10 parts and the content of the rubber component was changed to 10%. Using a coated paper (manufactured by Oji Paper Co., Ltd.) having a basis weight of 128 g as a substrate for a thermal transfer image receiving body, the printing properties of the low gradation area and the abnormal transfer resistance of the high gradation area were measured in the same manner as in Example 1. evaluated.
Table 1 shows the results.

Example 3 Epicoat 1009 (epoxy resin manufactured by Yuka Shell Epoxy Co., Ltd., molecular weight of about 3,75)
0) 80 parts and 20 parts of NISSO-PB, C-2000 (butadiene rubber manufactured by Nippon Soda Co., Ltd., molecular weight: about 2,000, average number of carboxyl groups: 2.0 / molecule) were mixed at 140 ° C. in a dissolving mixer at 140 ° C. After reacting for a time, a rubber-modified epoxy resin was obtained. To 15 parts of the obtained rubber-modified epoxy resin, 5 parts of the epicoat 1009 was added, and the content of the rubber component was reduced to 1 part.
Adjusted to 5%. In addition, KF-
393, X-22-343, methyl ethyl ketone and toluene were added in the same amounts to prepare a dyeing resin solution. Using the same base material as in Example 2 as the thermal transfer image receptor base material, a thermal transfer image receiver was prepared. In the same manner as in Example 1, the printability of the low gradation portion and the abnormal transfer resistance of the high gradation portion were evaluated.
Table 1 shows the results.

Example 4 A rubber-modified epoxy resin was obtained in the same manner as in Example 3, except that 55 parts of Epicoat 1009 and 45 parts of NISSO-PB and C-2000 were used. Example 1 was applied to 20 parts of the obtained rubber-modified epoxy resin.
KF-393, X-22-343, methyl ethyl ketone and toluene were added in the same amounts as in the above to prepare dyeing resin solutions. Using the same base material as in Example 2 as the thermal transfer image receptor base material, a thermal transfer image receiver was prepared. In the same manner as in Example 1, the printability of the low gradation portion and the abnormal transfer resistance of the high gradation portion were evaluated. Table 1 shows the results.

[Comparative Example 1] A dyeing resin solution was prepared in the same manner as in Example 1 except that Epicoat 1007 was used instead of the rubber-modified epoxy resin in Example 1.
An image receiving member was prepared in the same manner as in Example 1 using this dyed resin solution. Table 1 shows the results of evaluating the printability of the low gradation area and the abnormal transfer resistance of the high gradation area.

Comparative Example 2 A dyeing resin solution was prepared in the same manner as in Comparative Example 1 except that Epicoat 1007 was changed to Epicoat 1009. The same substrate as that used in Example 2 was used as the thermal transfer image receptor base material to prepare a thermal transfer image receiver. Table 1 shows the results of evaluating the printability of the low gradation area and the abnormal transfer resistance of the high gradation area.

Table 1 ━━━━━━━━━━━━━━━━━━━━━━━━━━━ Sample Printability of low gradation area Abnormal transfer resistance of high gradation area ━━━━━━━━━━━━━━━━━━━━━━━━━━━ ───────────────────────── Example 1 AI Example 2 AI Example 3 AI Example 4 AI Comparative Example 1 B II Comparative Example 2 C I ━━━━━━━━━━━━━━━━━━━━━━━━━━━

As is clear from Table 1, the thermal transfer image receiving body of the present invention in which an epoxy resin composition containing a rubber-modified epoxy resin is provided as a dyeing resin layer has a low gradation part printability and a high gradation part. Both of the abnormal transfer resistances are good.
On the other hand, an image receiving body for thermal transfer provided with a composition of a single epoxy resin as a dyeing resin layer has poor printability in a low gradation area and abnormal transfer resistance in a high gradation area.

[0037]

According to the thermal transfer image receiving body of the present invention, there is no printing unevenness or print blur in a low gradation area, and abnormal transfer in a high gradation area hardly occurs.

──────────────────────────────────────────────────続 き Continued from the front page (56) References JP-A-61-277493 (JP, A) JP-A-61-6650 (JP, A) JP-A-63-54285 (JP, A) JP-A-63-54285 69872 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) B41M 5/38

Claims (3)

(57) [Claims] 1. A thermal transfer image receiving body which receives a transfer of a sublimable dye from a thermal transfer paper provided with a coloring material layer containing a sublimable dye, by heating the epoxy resin with a carboxyl group-containing rubbery polymer. An image receiving body for thermal transfer, comprising a dyeing resin layer containing the obtained rubber-modified epoxy resin. 2. The image receiving body for thermal transfer according to claim 1, wherein the dyeing resin layer contains an epoxy resin and a rubber-modified epoxy resin. 3. The thermal transfer image receiver according to claim 2, wherein the content of the carboxyl group-containing rubbery polymer in the epoxy resin composition comprising the epoxy resin and the rubber-modified epoxy resin is 3 to 50% by weight.