JPS61258793A - Image-receiving paper for thermal transfer - Google Patents

Abstract

PURPOSE:To ensure the color density is uniform, image quality free of color defects or voids in dots can be obtained, little electrostatic charge is generated at the time of printing and curling does not occur after printing, by providing a highly elastic intermediate layer between a photographic printing paper and a dyeable resin layer. CONSTITUTION:The image-receiving paper for thermal transfer comprises the printing paper 1, the intermediate layer 2 and the dyeable resin layer 3. The intermediate layer is formed of a material rich in elasticity and capable of easily achieving uniform close contact of the layers 3, 4 under a pressure exerted by a thermal head, and is generally provided by using a substance having rubber elasticity. Particularly, a substance having a Young's modulus of 10<5>-10<9>dyn/ cm<2>, preferably, 5X10<6>-5X10<8>dyn/cm<2> is suitable. A covalent bond crosslinked type elastomer generally called vulcanized rubber, a thermoplastic elastomer which is plasticized at high temperature so that it can be molded or formed by plastic-processing machines, and a thermoplastic having a low modulus of elasticity can be used as a substance for forming the intermediate layer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thermal transfer image receiving paper, and more particularly, to a thermal transfer paper having a color material layer containing a sublimable dye,
The present invention relates to a thermal transfer image-receiving paper used in a thermal recording method in which a sublimation dye on a thermal transfer paper is sublimated and transferred by heating with a thermal head or the like to perform desired color recording.

[Conventional technology]

In recent years, with the spread of personal computers, televisions, VTRs, video discs, etc. as information terminals and the use of color displays, the demand for printers that output these still images as color images has been increasing year by year. Recording methods for full-color printers include electrophotographic methods, inkjet methods, and thermal transfer methods, among which the thermal transfer method is often used because it is noiseless and easy to maintain. This thermal transfer consists of a solidified color ink sheet and image receiving paper, and the ink is thermally melted transferred or sublimated onto the image receiving paper using thermal energy controlled by electrical signals from a laser or a thermal head to form an image. This is a recording method. This thermal transfer method includes a heat melt transfer type and a sublimation transfer type using a sublimation dye. The hot-melt transfer type uses an ink sheet with pigments or dyes bound with hot-melt glue.
Pigments or dyes are transferred to the receiving paper along with the melted wax by the thermal energy of the thermal head, which makes it difficult to obtain the necessary halftones for image quality, and the transferred wax makes it difficult to obtain good hues. be. On the other hand, the sublimation transfer type using sublimation dyes is an application of the conventional sublimation transfer printing technology, and uses a sheet in which disperse dyes, which are generally relatively easy to sublimate, are bound together with a binder. The dye is sublimated and transferred to the image receiving paper to obtain an image.

At this time, since the sublimation dye sublimates in response to the thermal energy of the thermal head, it has the advantage of being able to easily obtain halftones and controlling the gradation at will, making it the most popular method for full-color printers. Conceivable.

In this sublimation transfer type thermal transfer system, plain paper as described in Japanese Patent Application Laid-open No. 15446/1983 can be used as the image receiving paper for thermal transfer.

However, when using plain paper, the color density is low,
In addition, it is not preferable because the color fading phenomenon over time is significant, and as described in JP-A-57-107885, sublimable dyes such as polyester resins, polyamide resins, epoxy resins, etc. are generally used on printing base paper. It is known that a printing base paper is provided with a layer made of a thermoplastic resin that can be effectively dyed (hereinafter referred to as a dyeing resin layer).

This thermal transfer image-receiving paper, which has a dyed resin layer on the printing base paper, can obtain sufficient color density when synthetic paper, that is, one made of polyolefin or polystyrene, is used as the printing base paper, and the image quality is also quite good. You can get something good, but
In general, synthetic paper is stretched to increase its strength, and when printed, only the side on which the dyeing resin layer is applied shrinks when it is heated in a thermal or decoder, causing significant distortion on the front and back sides of the printing base paper. There was a drawback that curling occurred. Furthermore, compared to plain paper, synthetic paper generates significant static electricity due to friction with the thermal head during printing, and thermal transfer and image receiving paper for thermal transfer stick together when running, causing wrinkles, making it difficult to run, and causing problems with image quality. Streaks often appeared on the skin. On the other hand, when plain paper is used as a printing base paper, the color density is generally lower than that of synthetic paper, and the voltage of the thermal head must be increased, and the unevenness of the surface of the plain paper is large, so the color density is lower than that of synthetic paper. There are drawbacks such as unevenness, and there is a strong desire to develop a thermal transfer image receiving paper that is compatible with this recording method.

[Problem that the invention seeks to solve]

The problem to be solved by the present invention is to solve the above-mentioned disadvantages of the conventional thermal transfer image-receiving paper, and more specifically, to develop a thermal transfer image-receiving paper that does not have the above-mentioned disadvantages, which has been strongly desired in the past. It is.

As a result of extensive research to solve the above-mentioned problems, the present inventor finally found that between the dyeing oil layer and the printing base paper,
It has been found that the intended purpose can be achieved when an intermediate layer having rubber elasticity is provided so that the heat-sensitive transfer paper and the image-receiving paper for heat transfer can be easily and uniformly brought into close contact with each other by the pressure of a thermal head during printing.

[Means to solve the problem]

That is, the present invention provides a thermal transfer image receiving paper which is transferred by heating from a thermal transfer paper having a coloring material layer containing a sublimable dye, in which an intermediate layer having rubber elasticity is provided between the dyeing resin layer and the printing base paper. The present invention relates to an image receiving paper for thermal transfer, which is characterized by being provided with a thermal transfer image receiving paper.

[Structure of the invention]

The thermal transfer image receiving paper of the present invention basically consists of a printing base paper (1), an intermediate layer (2) and a dyeing resin layer (3) as shown in FIG.
It consists of a three-layer structure, as shown in Figure 4 (printing base paper (
It is clearly distinguishable from conventional image-receiving paper, which has a two-layer structure consisting of one layer and a dyed resin layer. However, in Figures 3 and 4, (a) and (a') are thermal transfer image receiving paper, (
b) and (mouth') are respectively thermal transfer paper, (4),
(4 digits are ink layers, (5) and (5') are thermal transfer paper base films, (6) and (6 digits are thermal heads, respectively, and (7) and (7') are platen rollers, respectively. .

Through research conducted by the present inventors, the following has become clear. That is, as shown in Fig. 4, printing base paper (1') and dyeing resin layer (3') are combined.
In conventional thermal transfer image receiving paper consisting of a two-layer structure, when plain paper is used as printing paper (one layer), there are many unevenness on the surface, and when looking at the paper as a whole, There are large wavy unevenness and depressions, and by laminating the dyeing resin layer (3') on top of this, it is possible to smooth out small irregularities, but it is not possible to completely smooth out large unevenness and depressions. It is extremely difficult, and even if it were possible to smooth it, the back side of the printing paper (1 inch), or the platen roller (7
Because there are large and small irregularities and overall large thickness unevenness or depressions on the surface that comes into contact with the thermal head (6') and the bra (7') when they are pressed together by the thermal head (6') and the bra (7) , thermal transfer image receiving paper has considerable unevenness.

Furthermore, plain paper is made of cellulose fiber and is hard, and the resin of the dyeing resin layer (3') is usually used to prevent fusion with the binder resin in the ink layer (4') of thermal transfer paper. Since a resin with a high softening point or a partially crosslinked resin is used, the thermal transfer image receiving paper itself is hard, and therefore has poor followability and poor adhesion to the head surface, that is, the surface of the thermal transfer paper ink. This poor adhesion means that air exists between the dyeing resin layer (3') and the ink layer (4'), and this air layer inhibits the sublimation and migration of the sublimation dye. It is thought that the color density is low and unevenness occurs in the color density.

On the other hand, as shown in Fig. 3, when an elastic intermediate layer (2) is provided between the printing base paper (1) and the dyeing resin layer (3), Even if there are some irregularities, uneven thickness, etc., these can be easily smoothed out, and the thermal head pressure can easily follow the ink surface of the thermal transfer paper, maintaining excellent adhesion. Therefore, it has been found that it is possible to prevent problems such as a decrease in color density and occurrence of uneven color density due to poor adhesion.

As the intermediate layer having rubber elasticity used in the present invention, the dyed resin layer (3
) and the ink layer (4) are used, and a material that is generally said to have rubber elasticity is used.

More specifically, its Young's modulus is 10' dyn/c+
Substances in the range of 4 to 109 dyn/-, preferably 5 X 10' dyn/aJ to 5 X 108 dyn
It is made of a substance in the range /aj. If a material with a Young's modulus of 105 dyn/cIi or less is used as an intermediate layer, the intermediate layer itself will be distorted by the heating and pressure applied by the thermal head during printing and will not recover, resulting in unevenness on the surface of the thermal transfer image-receiving paper and a noticeable gloss. On the other hand, if a material with a Young's modulus of 109 dyn/cJ or more is used as the intermediate layer, the dyeing resin layer (3
) and the ink layer (4) cannot have sufficient adhesion, resulting in decreased color density and uneven color density.

In addition, the thickness of this intermediate layer (2) is 1 to 200 in terms of dry coating amount.
g/rrr, preferably about 5 to 30 g/rd, and in this case, if the amount is less than 1 g/n, sufficient adhesion cannot be obtained and the color density decreases.Also, if the dry coating amount is 200 g/r
Even if a dZr intermediate layer is provided, color density unevenness does not occur, and good color density and image quality can be obtained, but larger improvements in color density and image quality cannot be seen, and this is disadvantageous in terms of cost. Examples of such intermediate layer materials include covalently crosslinked elastomers commonly referred to as vulcanized rubber, thermoplastic elastomers that can be plasticized at high temperatures and molded using plastic processing machines, and some thermoplastic plastics with low elastic modulus. . Bonded crosslinked elastomers such as natural rubber, butyl rubber, and nitrile rubber generally have excellent heat resistance, while thermoplastic elastomers have excellent processability and are easy to form into thin films. Good results can be obtained as an intermediate layer in In addition, thermoplastic elastomers require both a rubber component that has entropic elasticity in the molecule and a molecular restraint component that prevents plastic deformation. There are methods based on the crystalline phase of urethane systems, hydrogen bonds such as urethane systems, and ionic crosslinking systems such as acrylic systems, all of which yield good results.

In these intermediate layers, if necessary, conventionally known inorganic vulcanizing agents,
Processability of organic vulcanizing agents, vulcanization accelerators, activators, anti-aging agents, mastication accelerators, softeners, reinforcing agents, fillers, resins, etc.
It can be added at appropriate times and in appropriate amounts to adjust heat resistance, elasticity, weather resistance, strength, etc.

The intermediate layer material as described above is prepared by dissolving it in an appropriate organic solvent or by adjusting the viscosity as an emulsion solution to an appropriate level, applying it by any coating means such as a roll coater, kiss coater, gravure coater, etc., and drying it. Furthermore, for thermoplastic materials, extrusion coating such as Accumator is also used.

Furthermore, as the printing base paper used in the present invention, any conventionally used printing paper can be used, including plain paper such as high-quality paper and medium-quality paper, as well as resin-based paper such as polypropylene. Synthetic paper can also be used, and excellent image quality can be obtained without missing dots or white spots in the image.

Furthermore, as the dyeing resin layer, a wide variety of materials can be used as long as they have sufficient dyeability for sublimation dyes, such as polyester resin, epoxy resin, polyamide resin, cellulose acetate resin, acrylic resin, etc. These can be dissolved in a suitable solvent and applied onto the intermediate layer using any coating machine. These dyed resin layers may be partially crosslinked if necessary.

〔Effect of the invention〕

As explained in detail above, a highly elastic intermediate layer that improves the adhesion between the thermal transfer paper and the dyeing resin layer of the thermal transfer image receiving paper is formed by the thermal head pressure between the printing base paper (1) and the dyeing resin layer. By providing it between layer (3), it is possible to obtain extremely good image quality with high color density and even color density, and no missing colors or white spots in dots, and also to prevent static electricity during printing. It is possible to obtain an extremely useful image-receiving paper for thermal transfer that has little occurrence of curling, has excellent runnability, and does not curl after printing.

〔Example〕

The present invention will be explained below with reference to Examples. In addition, in the example text,
Parts indicate parts by weight, and each physical property was measured by the following method.

Dark color density> Thermal head recording conditions: 6 dots/dragon, applied power: 0.4
A gradation pattern was printed using a color printer while changing the applied pulse width (W/dot), and the reflection density at each gradation was measured using a color reflection densitometer DM-400 (manufactured by Dainippon Screen Mfg. Co., Ltd.).

<Color density unevenness> In the above gradation pattern, the applied pulse width is 10m5e
At point c, the color density was measured at 10 arbitrary locations, and the unevenness of the color density, that is, the difference between the maximum value and the minimum value of the color density was measured.

<Curl> The thermal transfer image receiving paper (8) on which the gradation pattern was printed using a color printer as described above is placed on a horizontal plate (9) as shown in Figure 5.
), and the maximum height h, which indicates the degree of curl, was measured.

Example 1 Disperse dye with sublimation property (Lurafix Blue)
An ink liquid consisting of 10 parts of polyamide resin (Persalon 1140, Henkel Hakusui?), 40 parts of luene, and 40 parts of isopropyl alcohol was dispersed in a ball mill for 24 hours to form a 6μ polyester film. Dry coating amount with gravure coater is 3
A thermal transfer paper was prepared by coating and drying to give a ratio of g/rrr.

On the other hand, thermoplastic elastomer (Califlex TR11
A solution consisting of 20 parts (manufactured by Shell Kagaku Co., Ltd.) and 80 parts of toluene was placed on art paper (basis weight 127.9 g/err, smoothness 2).
000 seconds) with a dry coating weight of l.

g/n (coated with a roll coater and dried to form the intermediate layer in the present invention, and further coated with 20 parts of saturated polyester resin (Vylon #200 manufactured by Toyobo Co., Ltd.), a polyisocyanate compound (coronated, and Nippon urethane). company) 3
A dyeing resin solution consisting of 77 parts of methyl ethyl ketone was applied onto the intermediate layer using a roll coater so that the dry coating amount was 5 g/rd, dried at 110°C for 3 minutes, and further dried at 50°C.
The mixture was aged for 24 hours to prepare an image receiving paper for thermal transfer.

Using the thus obtained thermal transfer paper and thermal transfer image receiving paper, thermal head recording conditions were 6 donts/dragon and applied power 0.
When a gradation pattern was printed using a color printer while changing the pulse width at 4 W/dot, the color density shown in FIG. 1(a) and the printing characteristics of the thermal transfer receiving paper shown in Table 1 were obtained.

Comparative Example 1 In Example 1, a solution consisting of 20 parts of a thermoplastic elastomer (Califlex TR1007, mentioned above) and 80 parts of toluene was coated on high-quality paper (93.0 g/d; smoothness 220 seconds) in a dry coating amount. It was coated with a roll coater to give a weight of 10 g/rd, dried to form an intermediate layer, and a thermal transfer image receiving paper was prepared in the same manner, and a gradation pattern was printed with a color printer, as shown in Figure 1 (b).
The color density shown in Table 1 and the printing characteristics of the thermal transfer image receiving paper shown in Table 1 were obtained.

Comparative Example 2 In Example 1, the intermediate layer was not provided, and instead a mixture of 20 parts of saturated polyester resin (mentioned above), 3 parts of polyisocyanurate compound (mentioned above), and 77 parts of methyl ethyl ketone was applied directly onto art paper (see above). The dry coating amount of the dyeing resin liquid directly onto the art paper (mentioned above) is 15g/n? Roll coke so that
A thermal transfer image receiving paper was prepared by drying and aging in the same manner, and a gradation pattern was printed using a color printer. Print characteristics were obtained.

Comparative Example 3 In Comparative Example 2, high-quality paper (as described above) was used as the base paper for printing.
Similarly, the dyeing resin liquid was applied directly to this with a dry coating amount of 15g/n.
? A thermal transfer image-receiving paper was prepared by applying the following, and a gradation pattern was printed using a color printer.The color density shown in Figure 1(d) and the printing characteristics of the thermal transfer image-receiving paper shown in Table 1 were obtained. Ta.

Comparative Example 4 In Comparative Example 2, polypropylene synthetic paper (basis weight 97 g/%; smoothness 1000 sec or more) was used as the base paper for printing, and the dyeing resin liquid was applied directly to it in the same manner at a dry coating amount of 1 s gi.
A thermal transfer image-receiving paper was prepared by coating the paper in such a manner that the gradation pattern was printed using a color printer.The color density shown in Figure 1 (8) and the printing characteristics of the thermal transfer image-receiving paper shown in Table 1 were Obtained.

Comparative Example 5 In Example 1, a solution consisting of 20 parts of thermoplastic elastomer (Califlex TR1107, above) and 80 parts of toluene was applied onto polypropylene synthetic paper (see above) so that the dry coating thickness was 10 g/n (see above). Apply with a roll coater to
After drying, a thermal transfer image-receiving paper was prepared in the same manner, and a gradation pattern was printed using a color printer. The color density shown in FIG. 1(f) and the printing characteristics of the thermal transfer image-receiving paper shown in Table 1 were obtained.

Example 2 10 parts of a disperse dye having a sublimation part (Kayasef Trend 126; manufactured by Nippon Kayaku Co., Ltd.), a polyamide resin (Persalon 11)
40, manufactured by Henkel Hakusuisha), 40 parts of toluene, and 40 parts of isopropyl alcohol were dispersed using ultrasonic waves for 6 hours, and a dry coating amount of 2 g/d was obtained using a gravure coater on a 6μ polyester film. This was applied and dried to make thermal transfer paper.

On the other hand, thermoplastic elastomer (VISTANEX LM-M
H Fso Standard Oil Co.) 20 parts, toluene 80
A dry coating of 10 parts of the solution was applied onto high-quality paper (see above).
g/+yr with a roll coater and dried to form an intermediate layer in the present invention, and further coated with 20 parts of a saturated polyester resin (Vylon #200, manufactured by Toyobo Co., Ltd.) and a polyisocyanurate compound (Coronate L, Nippon Urethane). (manufactured by) 3.

A dyeing resin solution consisting of 2 parts of melamine resin (Super Beckamine J-820 manufactured by Dainippon Ink Co., Ltd.) and 75 parts of methyl ethyl ketone was applied onto the above intermediate layer using a roll coater so that the dry coating amount was 3 g/1rd. , 3 at 130℃
The mixture was dried for a minute and then aged at 50° C. for 24 hours to prepare an image-receiving paper for thermal transfer.

Using the thus obtained thermal transfer paper and thermal transfer image receiving paper,
When a gradation pattern was similarly printed using a color printer, the color density shown in FIG. 2 and the printing characteristics shown in Table 2 were obtained.

Example 3 In Example 2, a solution consisting of 20 parts of vulcanized rubber and 80 parts of toluene was coated on high-quality paper (described above) in a dry coating amount of 10 g.
/rd, and heated at 150°C for 15 minutes to form the intermediate layer of the present invention.A dyeing resin layer was applied in the same manner, dried, and aged for thermal transfer. When a receiver paper was prepared and a gradation pattern was printed using a color printer, the color density shown in FIG. 2 and the printing characteristics shown in Table 2 were obtained. However, the sulfurized rubber used had the following formulation.

lR2200 (Japanese Synthetic Rubber> 100 parts zinc white)
5.0 parts stearic acid
,,,,,,,,,,,,,,, 1.0 part vulcanization accelerator MBT (Iruuchi Shinko Chemical), 0.5 part vulcanization accelerator MBTS (Iruuchi Shinko Chemical), ,, , 0.
Part 5 Parnok R (Iriuchi Shinko Kagaku)... 1.
Part 0 sulfur, , , , , , , , , , , , , , , , , ,
,,,,,,,, 0.5 part Escolets 1102
(Esso Chemical) 10.0 parts Example 4 In Example 3, 20 parts of the vulcanized rubber compound, 8 parts of toluene
A solution consisting of 0 parts was coated on copy paper (basis weight 63 g/rd, smoothness 24 seconds) using a roll coater so that the dry coating amount was 10 g/d, and heated to form an intermediate layer in the present invention.
Thereafter, a dyed resin layer was similarly applied, dried, and aged to create a thermal transfer image receiving paper, and a gradation pattern was printed using a color printer.The color density shown in Figure 2 and the printing characteristics shown in Table 2 were obtained. Obtained.

Table 1 Table 2

[Brief explanation of drawings]

1 and 2 are graphs showing the relationship between reflection density and applied pulse width, respectively, and FIGS. 3 and 4 are simulated cross-sectional views of a thermal transfer paper and a thermal transfer image receiving paper. Further, FIG. 5 is an explanatory diagram for explaining a method for measuring curl. (1), (1 勺10009.Print paper (2),,,,,,,,,,,,,,,,,,,,,,,,,,,,,, intermediate layer (3), (
3'), dyed resin layer (4), (4'),
,,,,, Ink layer (5), (5'),,,,,, Thermal transfer paper base film (6), (6'),,,,,,
, Thermal head (7), (7') , Platen roller (8), , Image receiving paper (9), , , , , , , , , , horizontal plate (or more) Patent applicant Hitachi, Ltd. Figure 4 Figure 5

Claims (9)

[Claims] (1) In a thermal transfer image receiving paper that is transferred by heating from a thermal transfer paper having a color material layer containing a sublimable dye, an intermediate layer having rubber elasticity is provided between the dyeing resin layer and the printing base paper. An image receiving paper for thermal transfer characterized by comprising: (2) The Young's modulus of the intermediate layer having rubber elasticity in the thermal transfer image receiving paper is 10^5 to 10^9 dyn/cm^2
An image receiving paper for thermal transfer according to claim 1. (3) The thermal transfer image-receiving paper according to claim 2, wherein the intermediate layer having rubber elasticity is made of a covalently crosslinked elastomer. (4) The thermal transfer image-receiving paper according to claim 2, wherein the intermediate layer having rubber elasticity is made of a thermoplastic elastomer. (5) The thermal transfer image-receiving paper according to claim 4, wherein the molecular binding component of the thermoplastic elastomer in the thermal transfer image-receiving paper is formed by ionic crosslinking. (6) The thermal transfer image-receiving paper according to claim 4, wherein the molecular restraint component of the thermoplastic elastomer in the thermal transfer image-receiving paper is a frozen phase. (7) The thermal transfer image-receiving paper according to claim 4, wherein the molecular binding component of the thermoplastic elastomer in the thermal transfer image-receiving paper is due to hydrogen bonding. (8) The thermal transfer image-receiving paper according to claim 4, wherein the molecular constraint component of the thermoplastic elastomer in the thermal transfer image-receiving paper is a crystalline phase. (9) The image-receiving paper for thermal transfer according to claim 1, wherein the printing base paper in the image-receiving paper for thermal transfer is commonly used plain paper such as wood-free paper, medium-quality paper, art paper, coated paper, etc.