JPH06255139A - Dye image solvent deposition method in thermal printer and device used therefor - Google Patents

Abstract

PURPOSE: To efficiently control solvent fusing of a thermal image without damaging a dye or the like by controlling a solvent vapor concentration supplied to an enclosure and fusion bonding the image to a receiver without damaging the image. CONSTITUTION: Inert gas such as nitrogen or the like from a gas source 32 is supplied to a bubble generating chamber 26, a predetermined solvent concentration gas is generated and supplied into an enclosure 18. Then, solvent vapor 12 flows into the enclosure 18 through a distributor 22, and a receiver layer 14 is uniformly brought into contact with the vapor 12 in the enclosure 18, a dye image 16 is fusion bonded to the layer 14 by the vapor 12. The solvent concentration in the enclosure 18 is sensed by a concentration measuring instrument 20, and confirmed that a target concentration is maintained in the enclosure 18. A preferred embodiment of the solvent is selected from the group consisting of CH2 Cl2 and CH3 COC2 H5 . A solvent temperature in a bubble generating chamber 26 can be separately regulated from the enclosure 18 according to a temperature of water 38, and the concentration of the vapor 12 can be arbitrarily controlled.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to thermal printers, and more particularly to a method of fusing a dye image to a receiver produced by the thermal printer.

[0002]

This application is filed by Long et al., June 1, 1991.
U.S. Application No. 721,819 filed on Oct. 0, "Method for Welding Solvents in Dye Images of Thermal Printers", and Brody et al.
No. 31,018, “Fusion method of solvent for dye image of thermal printer” is a continuous application.

The current thermal transfer of dyes involves a fusing process to "fix" the dye to the receiver. The term "thermal transfer of dye" means any method of transferring dye using heat, whether or not thermal energy is generated directly and / or indirectly and / or from other sources, but the resistive head This does not include thermal transfer of dyes, using resistive ribbons, lasers and ultrasound. There are two types of technology that can be applied to welding. One of the most common is the thermal welding process in which the receiver is reheated after the thermal transfer of the dye, which is the most common method. This technique uses thermal energy to generate large amounts of heat, so a separate unit separate from the heat-sensitive donor is required for this task. For this reason,
A two-step process and two separate units are required.
One for image transfer and the other for fusing, which increases the cost and time of thermal imaging. In such a heat-welding process, the receiver may be damaged in the process of heat-treating the receiver and fixing or welding the dye.

The solvent deposition method can eliminate the problems of receiver damage and dye damage due to subsequent heating steps. In the previous fusing process, the receiver with the dye image thermally transferred by thermal printing is placed in an enclosure near the open bath of solvent. The melting agent evaporates, this vapor penetrates into the receiver,
Fuse the dye image to the receiver.

[0005]

SUMMARY OF THE INVENTION In this solvent welding method,
The vapor concentration of the solvent is controlled (determined) by the saturated vapor pressure of the solvent at room temperature. Depending on the solvent used, a concentration can be reached that damages the dye image. Another problem with this method is that it is difficult for some solvents to penetrate the receiver into the receiver within a reasonable amount of time (to the proper concentration level to adequately fix the dye image to the receiver). is there. When the receiver layer is placed inside the enclosure, the vapor is depleted and the liquid-vapor equilibrium of the solvent is lost. When the solvent liquid evaporates and the concentration equilibrium is achieved again, the liquid is cooled by evaporative cooling and has a vapor concentration lower than the original concentration. This continues until the liquid has absorbed enough heat from the surroundings to reach ambient temperature again. Thus, the method of utilizing this natural solvent liquid-vapor equilibrium in solvent melting is rather difficult to control. Because this method is influenced by various changing factors such as the frequency of use, the amount of vapor lost during installation and removal of the receiver, the amount of liquid, the space volume of vapor, the material and shape of the enclosure, etc. Is.

It is an object of the present invention to provide a method for efficiently controlling the solvent deposition of a thermal image in an image transferred using heat without damaging the dye or the receiver.

[0007]

SUMMARY OF THE INVENTION The present invention is a method for welding a dye image for thermal printing to a receiver, wherein (a) the receiver on which the dye image is transferred is placed in an enclosure, and (b) ) Controlling the temperature of the liquid solvent in a separately provided container, (c) supplying bubbles of an inert gas to the solvent in the container at a predetermined ratio to evaporate the solvent to obtain solvent vapor, (d) The solvent evaporated in this manner is supplied to the enclosure, the concentration of solvent vapor in the enclosure is controlled, and the dye image is fused to the receiver without damaging the image.

The inert gas is nitrogen, and the solvent is selected from the group consisting of CH ₂ Cl ₂ and CH ₃ COC ₂ H ₅ .

Further, the liquid temperature of the solvent in the container is controlled so that the temperature of the solvent vapor is equal to or lower than the temperature of the receiver.

Further, in order to prevent liquefaction in the receiver, the concentration of the solvent vapor in the enclosure is determined to be saturated or equal to or less than the equilibrium vapor pressure.

Further, the present invention is an apparatus for fusing a dye image for thermal printing to a receiver, comprising:
(A) an enclosure in which a receiver to which a dye image is transferred is installed, and (b) the temperature can be controlled,
A container containing the liquid solvent; (c) gas supply means for supplying inert gas bubbles into the liquid solvent to evaporate the solvent in the container to generate solvent vapor; And a solvent vapor supply means for supplying the solvent vapor into the enclosure.

As described above, according to the present invention, the concentration of the solvent vapor can be adjusted by the temperature of the solvent independently of the temperature inside the enclosure. Therefore, the solvent concentration in the enclosure can be controlled to a required value.

[0013]

EXAMPLES In the present invention, a controlled concentration of solvent vapor is constantly supplied to the receiver layer to fuse the image to the receiver. As shown in FIG. 1, the solvent vapor 12 is
A flow of an inert gas, such as nitrogen, from gas source 32 evenly distributes it to the receiver layers provided within enclosure 18. The dye receiver layer 14 carries the dye image 16 and is coated on the receiver support layer 30.
The solvent vapor 12 flows into the enclosure 18 via the distribution plate 22 so that the receiver layer 14 uniformly contacts the solvent vapor in the enclosure 18. The concentration 34 of the solvent in the enclosure 18 is detected by the concentration measuring device 20 and it is confirmed that the target concentration is maintained in the enclosure 18.

The solvent vapor is produced as follows. The inert gas flows from the gas source 32 to the bottom of the bubble generation chamber 26 under the control of the flow rate controller 36. This gas is introduced into the liquid solvent 10 through the bubble size reduction device (air diffuser) 40 and rises in the liquid solvent 10,
Generates solvent vapor 12. The predetermined concentration of solvent vapor 12 is
It is produced by controlling the evaporation rate of the solvent by controlling the gas flow rate, bubble size, contact time between gas and solvent, and liquid temperature of the solvent.

The bubble generating chamber 26 is housed in a container 24, and water 38 of which temperature is adjusted is circulated in the container 24 to accurately control the liquid temperature of the solvent. If the mass transfer parameters of the evaporation process are controlled to achieve vapor-liquid equilibrium, then the maximum achievable vapor concentration is a function of only the saturated vapor pressure at the liquid solvent temperature. . When performing the welding method in this manner, the liquid temperature of the solvent is controlled so that the vapor temperature of the solvent is lower than the temperature of the dye receiver layer 14 so that the solvent concentration in the enclosure is not excessively high, and the dye receiver Damage to the layers can be prevented. The concentration of solvent vapor is determined so as not to exceed saturation or equilibrium vapor pressure. In this way, the solvent is prevented from thickening in the receiver.

Depending on the measurement value of the concentration measuring device 20,
The temperature of the water 38 may be adjusted and the solvent concentration may be feedback-controlled. It is also possible to control the flow rate controller 36 or both. Further, the temperature of the liquid solvent 10 may be controlled by adjusting the temperature of the water 38 with the measurement value of the thermometer 28.

As the solvent for dissolving the dye receiver layer and the dye layer, any solvent can be used. The vapor concentration of the solvent and the time the dye receiver layer is exposed to the solvent vapor are important for effective deposition of the dye on the receiver layer. Effective fusing is the complete fixing of the dye to the receiver layer without distortion of the dye image.
It is necessary to fix the dye so that it does not remove a significant amount of the dye from the surface of the receiver layer with a solvent that can only melt the dye. Effective melting differs from solvent to solvent because the rate at which the dye receiver and dye melt varies with solvent. A fast-reacting solvent that rapidly dissolves the receiver and dye can distort the dye image in less than what is normally required at concentrations at which equilibrium is reached at ambient temperature. It is an object of the present invention to provide a control means for contacting the dye receiver layer with a solvent at a concentration below that obtained by equilibrating the liquid solvent within the enclosure at ambient temperature. Some solvents are capable of dissolving the receiver layer and dye when contacted with the liquid phase of the solvent, but these have low evaporation pressures, so the concentration of solvent that can be achieved at the processing temperature is low and effective deposition is not possible. . Vapor pressure of 50m when temperature is below 20 degrees Celsius
A solvent having a mHg or more can effectively reduce the contact time with the solvent in order to effectively deposit the dye on the receiver layer, and the solvent can be selected from the group consisting of CH ₂ Cl ₂ and CH ₃ COC ₂ H _5. preferable.

Any sublimable dye may be used provided it is transferred to the dye receiver layer by heating. Examples of sublimable dyes are anthraquinone dyes such as Sumikaron Violet RS (a product of Sumitomo Chemical), Dianix First Violet (a product of Mitsubishi Chemical Industries), and Kayalong Polyol.
Brilliant Blue N-BGM and KST Black 14
6 (product of Nippon Kayaku), azo dyes such as Kayalong Polyol Brilliant Blue BM, Kayalong Polyol Dark Blue 2BM, KST Black KR (Product of Nippon Kayaku), Sumikaron Diazo Black 5G (Sumitomo Chemical's products), Mictasol Black 5GH (Mitsui Toatsu Chemical's products); Direct type dyes such as Direct Dark Green B (Mitsubishi Chemical Industries' product), Direct Brown B and Direct First -Black D (product of Nippon Kayaku); acid dyes such as Kayanol Milling Cyan 5R (product of Nippon Kayaku), basic dyes such as Sumikacryl Blue 6G
(Sumitomo Chemical's product) and Eisen Malachito Green (Hodogaya Chemical's product); or US Patent No. 4
Any of the dyes described in No. 541830. This US patent is incorporated herein by reference.

The receiver layer 14 is a commercially available polycarbonate or polyester which is capable of undergoing thermal transfer of the dye and can also be applied to a dye support layer such as paper.

Experimental Example: In an example according to the invention, unfused red, green and blue dye images were formed on a polycarbonate receiver by thermal transfer. These images for 4 minutes 3
It was exposed to 4 mol% solvent vapor. The vapor concentration of 34 mol% was determined by calculating the vapor pressure with respect to the total pressure. The fused image was washed with methanol and was unaffected. When the unfused image was similarly washed, the dye was completely peeled off.

The solvent used was CH ₂ C ₁₂ and was controlled at 14 degrees Celsius. The nitrogen flow rate was controlled to 0.5 liter / min with a rotameter. The temperature of the solvent in the room could be raised to 18 degrees Celsius. With the liquid height at 10 cm, the size of the bubbles is reduced by passing it through a sintered glass plate (porous diffuser plate) in a glass bubble mixing tube with a diameter of 5.0 cm. The height of the liquid in the tube was increased by 10 cm. The enclosure for welding shown by reference numeral 18 in the figure is 2.5
It had a volume of 1 liter and had a bottom of glass (porous plate) sintered to evenly diffuse the vapor. The solvent vapor concentration in the enclosure for welding is determined by the Matheson Model 8017
It was detected by a thermal conduction gas leak detector. This detector was modified to reduce the gain for high concentration detection.

While a particular embodiment of the invention has been described above, it will be understood that changes and modifications are made within the spirit of the invention.

[0023]

The advantages of the present invention are as follows.

1. By welding the solvent, distortion of the dye receiver layer due to heat can be eliminated, and deterioration of dye quality or sublimation due to the heat welding method can be eliminated.

2. Since an inert gas is used as a carrier for solvent vapor, the risk of fire due to the use of flammable solvents can be reduced.

3. A constant concentration of solvent vapor from an external source,
Supplied continuously within the enclosure with the dye receiver layer.

4. It is possible to control the solvent vapor concentration below the concentration determined by the equilibrium state between the solvent vapor and the liquid at the temperature inside the enclosure, and depending on the solvent, the solvent vapor concentration that may occur is too high. Image damage can be prevented.

[Brief description of drawings]

FIG. 1 shows a schematic configuration of an apparatus for carrying out the method of the present invention.

[Explanation of symbols]

 10 Liquid Solvent 12 Solvent Vapor 14 Receiver Layer 16 Dye Image 18 Enclosure

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor David Lewis Bangalio 14420 Brockport Sherwood Drive, New York, USA 58 (72) Inventor Samiel Es Brody, New York, USA 14534 Pittsford Saxony Road 5 (72) Inventor Mark J. Robins United States New York 14615 Rochester Lanham Street 132

Claims (7)

[Claims] 1. A method for depositing a dye image for thermal printing on a receiver, comprising: (a) installing the receiver on which the dye image has been transferred in an enclosure, and (b) using a liquid solvent in a separately provided container. The temperature is controlled, and (c) bubbles of an inert gas are supplied to the solvent in the container at a predetermined ratio to evaporate the solvent to obtain a solvent vapor, and (d) the solvent evaporated in this way is The method is characterized in that the dye image is supplied to the receiver, the concentration of solvent vapor in the container is controlled, and the dye image is fused to the receiver without damaging the image. 2. The method of claim 1, wherein the inert gas is nitrogen and the solvent is CH ₂ Cl ₂ and CH _3.
It is characterized in that it is selected from the group consisting of COC ₂ H ₅ . 3. The method according to claim 1, wherein the liquid temperature of the solvent in the container is controlled so that the temperature of the solvent vapor is equal to or lower than the temperature of the receiver. 4. The method according to claim 1, wherein in order to prevent liquefaction in the receiver, the concentration of the solvent vapor in the enclosure is determined to be saturated or equal to or less than the equilibrium vapor pressure. A method characterized by. 5. An apparatus for welding a dye image for thermal printing to a receiver, comprising: (a) an enclosure in which the receiver having the dye image transferred is installed; and (b) a temperature controllable. A container for containing a liquid solvent, and (c) gas supply means for supplying inert gas bubbles into the liquid solvent to evaporate the solvent in the container to generate solvent vapor, (d) An apparatus comprising: a solvent vapor supply unit configured to supply the generated solvent vapor into the enclosure. 6. The apparatus according to claim 5, wherein the temperature of the liquid solvent in the container is controlled so that the solvent vapor temperature is equal to or lower than the temperature in the enclosure. 7. The device according to claim 5, wherein the concentration of the solvent vapor in the enclosure is controlled to be saturated or equal to or less than the equilibrium vapor pressure in order to prevent liquefaction in the receiver. .