JPH04238089A - Coating agent for formation of dye-receptive layer and receptive sheet - Google Patents

Abstract

PURPOSE:To obtain a coating agent for the formation of a dye-receptive layer for a sublimable receptive sheet for thermal transfer printing which is excellent in terms of dyeing properties and a sublimable receptive sheet for printing consisting of a dye-receptive layer based on the coating agent. CONSTITUTION:A coating agent for the formation of a dye-receptive layer of a sublimable receptive sheet for thermal transfer printing contains polyalkyleneoxide with a urea group terminal which has a urea group at the terminal of a main chain, and polymer having a film forming function as essential components. In addition, a sublimable receptive sheet for thermal transfer recording consists of a dye-receptive layer based on the coating agent applied on the substrate.

Description

Description: TECHNICAL FIELD The present invention relates to a receptor sheet used in sublimation thermal transfer printing and a coating agent used to form a dye-receiving layer of the receptor sheet. 2. Description of the Related Art In recent years, with the development of signal processing technology, the quality of image signals has improved dramatically. In particular, signal frequency bands are becoming increasingly high, and improvements in video signal formats, broadcasting systems, etc. are being actively made. Furthermore, it is becoming possible for ordinary households to easily obtain and use high-quality image data by receiving high-definition broadcasts or using optical discs. Furthermore, the use of electronic recording of still images is progressing, and the shift from optical silver halide photographic recording methods to electronic recording of electronic still photographs is becoming more active. Characteristics of these electronic recordings include that since image information is converted into electrical signals and recorded, image information can be stored at high density and data can be easily transferred and processed. Furthermore, digitization of signals is progressing, and storage and reproducing systems with extremely low signal deterioration are being constructed. On the other hand, in response to the increasing quality of such image information, there has been a demand for a high-quality printing method for converting such image information into hard copies. In response, various non-impact printing methods are being developed, including thermal transfer printing methods such as sublimation thermal transfer printing and melting thermal transfer printing, electrophotographic methods, inkjet printing methods, and silver salt photographic methods. Among these printing methods, dye-sublimation thermal transfer printing can provide high-quality images with density gradation, and has a relatively simple printing mechanism and does not require much maintenance. Since then, the use of video printers for home use has become widespread. In sublimation thermal transfer printing, the coloring material layer of the transfer film and the dye-receiving layer on the surface of the receiving sheet are stacked in close contact with each other, and the sublimable dye in the coloring material layer is transferred to the dye-receiving layer using thermal printing means such as a thermal head. (hereinafter also referred to as a receiving layer). The color material layer is yellow, magenta,
Each color contains one of three (or four) sublimable dyes: cyan and (sometimes black), and color images can be created by printing each color on the same receiving layer one after the other. I'm reenacting it. In conventional receptor sheets, the material for the receptor layer formed on the surface is generally a polymer composition containing, for example, polyester resin, vinyl chloride-vinyl acetate copolymer resin, polycarbonate resin, etc. as a main component. ing. Problems to be Solved by the Invention One of the problems that should be improved with conventional dye sublimation thermal transfer printing is that the printing speed is slow. For this reason, there is currently a strong desire to develop a receptor layer with excellent dye transferability, that is, excellent dyeability, so that the sublimable dye can be quickly transferred to the receptor layer. The present invention has been made with the aim of improving or eliminating the problems in the prior art, and is a method for forming a dye-receiving layer of a dye-receiving sheet for sublimation thermal transfer printing with excellent dyeability. The object of the present invention is to provide a receiving sheet for sublimation printing on which a coating agent and a dye-receiving layer made of the coating agent are formed. Means for Solving the Problems The present inventors have investigated improvements in order to improve the dyeability of dyes during thermal transfer printing. The inventors have now completed the present invention by discovering that dyeing properties can be significantly improved by adding a urea group-terminated polyalkylene oxide to a polymer having the following properties. That is, the gist of the present invention is as follows. [0010] A dye for a receiving sheet for sublimation thermal transfer printing, characterized in that it contains as essential components a urea group-terminated polyalkylene oxide having a urea group at the end of its main chain, and a polymer having film-forming ability. Coating agent for forming a receptor layer. Furthermore, the receiving sheet for sublimation type thermal transfer printing according to the present invention is characterized in that a dye receiving layer made of the above-mentioned coating agent is formed on a substrate. The present invention will be explained in detail below. The urea group-terminated polyalkylene oxide which is the first component of the coating agent for forming a dye-receiving layer (hereinafter also referred to as coating agent) of the present invention can be represented by the following structural formula. embedded image In the above formula, m is an integer of 0 to 5, and n is an integer of 100 or less. Generally, a compound having a polyethylene oxide chain or a polypropylene oxide chain in which m is 0 or 1 can be preferably used. Furthermore, the degree of polymerization of the polyalkylene oxide that meets the purpose of the present invention is preferably one in which n in the structural formula is 100 or less,
More preferably, n is 50 or less. There is a tendency that the higher the molecular weight, the lower the dyeability. The polymer having film-forming ability, which is the second component used in the coating agent of the present invention, is not particularly limited as long as it has film-forming ability. Preferably, vinyl chloride resin, vinylidene chloride resin, vinyl acetate resin, polyamide, polyethylene, polycarbonate, polystyrene, polypropylene, acrylic resin, phenol resin, polyester, polyurethane resin, epoxy resin, silicone resin, fluororesin, melamine resin, polyvinyl alcohol. Examples include cellulose resins, maleic anhydride copolymer resins, mixtures, copolymers, and modified products of these resins. Among these, vinyl chloride-vinyl acetate copolymer resins, thermoplastic polyesters, polycarbonate resins, and mixtures of two or more thereof may be preferably used. The present invention is not limited in any way by the type of polymer mentioned above. [0016] The raw materials for the first and second components used to obtain the coating agent of the present invention are not limited in shape, and may be in the form of, for example, powder, solution, or emulsion. The proportion of the first component contained in the coating agent of the present invention is usually 1 to 50% by weight, preferably 5 to 30% by weight, based on the total weight of the first and second components constituting the coating agent.
It is desirable that the amount is in the range of 5 to 25% by weight, and if it is less than 1% by weight, the effect of improving dyeability will be low, and if it exceeds 50% by weight, the film-forming ability will deteriorate, which is not preferable. Further, it is preferable that the total amount of the first and second components contained in the entire coating composition of the present invention is at least 50% by weight. The coating agent of the present invention may contain various substances in addition to the above-mentioned essential components, if desired. Specifically, it is also possible to add a relatively low molecular weight compound that exhibits a liquid state. Examples include liquid epoxy compounds and liquid isocyanate compounds. [0021] In addition, the coating agent of the present invention improves the whiteness of the receptor layer provided and improves the quality of the recorded image, and also prevents the receptor layer from fusing with the thermal transfer sheet during thermal transfer. White inorganic particles can be added to prevent retransfer of the image. Examples of the white inorganic particles in this case include titanium oxide, calcium carbonate, calcium phosphate, clay, diatomaceous earth, zinc oxide, and silica. These white inorganic particles can be used alone or in combination of two or more. Furthermore, in order to prevent blocking of the receptor layer provided using the coating agent and to prevent fusion between the transfer film having the coloring material layer and the receptor paper having the receptor layer during thermal transfer printing, the coating of the present invention is used. A release agent can be added to the agent. Examples of the mold release agent include organopolysiloxane compounds such as dimethylpolysiloxane, silicone compounds, fluorine compounds, amide and polyethylene waxes, and surfactants. These mold release agents can be used alone or in combination of two or more. Preferably, a thermosetting type is recommended, but
It is not limited to these. The method of use is to add a mold release agent to the coating solution, or to coat it.
Alternatively, a liquid release agent diluted with an appropriate solvent such as toluene can be applied to the surface of each coating layer obtained by coating a substrate with a coating liquid containing or not containing a mold release agent. . In order to improve the storage stability and light resistance of the receptor layer formed using the coating agent of the present invention, the coating agent may contain stabilizers, antioxidants, ultraviolet absorbers, ultraviolet stabilizers, etc. Stabilizers may be included. Examples of these stabilizers include organotin stabilizers, lead stabilizers, metal soap stabilizers, and the like. Examples of the antioxidant include phenolic antioxidants, sulfur-based antioxidants, phosphorus-based antioxidants, and the like. Examples of the ultraviolet absorber include salicylic acid-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, and cyanoacrylate-based ultraviolet absorbers. Examples of the UV stabilizer include hindered amine stabilizers. One or two of these stabilizers
It is possible to use combinations of more than one species. Furthermore, in order to impart antistatic properties to the receiving layer, the coating agent may contain an antistatic agent, and the antistatic agent may be applied to at least one side of the receiving paper. Furthermore, the coating agent may contain appropriate amounts of plasticizers, fillers, lubricants, foaming agents, etc., if desired. Next, the receiving sheet for sublimation type thermal transfer printing of the present invention will be explained. The receiving paper of the present invention has a dye receiving layer containing the above-mentioned coating agent of the present invention on at least one side of a substrate. As the substrate for the receiving sheet used in the present invention, for example, paper mainly composed of pulp, coated paper thereof, polypropylene synthetic paper, polystyrene synthetic paper, and various plastic sheets can be used. It is not limited. [0028] When the adhesion between the substrate and the receptor layer is low,
Adhesion can be improved by subjecting the surface of the substrate to corona discharge treatment, primer treatment, or both, if necessary. A method for forming a dye-receiving layer containing the coating agent of the present invention on a substrate includes, for example, coating at least one side of the substrate using a coating solution of a dissolved dispersion containing the coating agent using various coaters. The method is common. However, other coating methods may be used, for example, coating the substrate by blending various substances with the coating agent of the present invention and melting the mixture with heat without using a solvent.
The receiving layer can also be provided on the substrate by the so-called extrusion coating method. In addition, there is a method of producing a film containing this coating agent and laminating this film on a substrate, and a multilayer melt coextrusion method in which the coating agent and the plastic constituting the substrate are formed so that the coating agent layer is the outermost layer. It is also possible to do so. [0030] The coating liquid containing the coating agent of the present invention can be obtained by dissolving and dispersing the coating agent in one or more organic solvents, water, and other solvents, and various substances to be blended as desired. It is convenient to add and blend during this dissolution and dispersion for uniform mixing. The above solvents are not particularly limited, but preferred ones are selected mainly depending on the II component used.
For example, methyl ethyl ketone (MEK), acetone, methyl isobutyl ketone (MIBK), toluene, tetrahydrofuran (THF), or a mixed solvent thereof can be used. [0032] Various coaters used for coating a substrate with the coating agent of the present invention include a bar coater,
A direct gravure coater, an offset gravure coater, a top feed reverse coater, a bottom feed reverse coater, an extrusion coater, etc. can be used, but are not particularly limited to these. In parallel with the coating on the substrate, after coating, or both, heat drying treatment for solvent removal or crosslinking reaction can be performed as necessary. As a method of heating and drying treatment, methods such as a Yankee cylinder method, an air floating method, a far-infrared heating method, and a microwave heating method can be used. The heating and drying conditions are selected taking into account the type and content of the solvent used when the purpose is desolvation, and the type of catalyst used in addition to these when crosslinking and curing is also performed. In any of these cases, the heat resistance of the substrate used is also taken into consideration. The present invention is not limited by these heating drying methods, conditions, etc. As described above, a receiving sheet for sublimation thermal transfer printing is obtained, in which a dye receiving layer containing the coating agent of the present invention is provided on a substrate. The thickness of the dye receiving layer of the receiving sheet for sublimation type thermal transfer printing of the present invention is usually 1 to 50 μm, preferably 5 μm.
A range of ~20 μm is desirable. [0035] In general, it has been thought that the melt viscosity of low-molecular compounds is extremely reduced during dye transfer, and problems such as fusion between the receptor layer containing the compound and the coloring material layer and bleeding in printed matter are likely to occur. However, the dye-receiving layer formed using the coating agent of the present invention containing the above-mentioned urea group-terminated polyalkylene oxide and a polymer having film-forming ability has improved dye stainability and image plasticity resistance. Not only does it exhibit a remarkable improvement effect, but the above-mentioned troubles can be effectively prevented and suppressed. Furthermore, since the surface of this receptor layer does not become sticky or sticky, when thermal sublimation transfer is carried out onto a receptor sheet on which this receptor layer is formed, the fusion of the receptor sheet with the transfer film and the rolls of the printer are difficult. This also has the effect that troubles such as wrapping around the roll, contamination of the roll surface, and getting caught in the printer do not occur. [Examples] The present invention will be explained in more detail below with reference to Examples and Comparative Examples. Example 1 Preparation of coating liquid Urea-terminated polypropylene oxide (component I) (trade name: Jeffamine BuD-2000, manufactured by Mitsuishi Texaco Chemical Co., Ltd.), A (component) which is a polymer having film-forming ability shown in Table 1 II) A coating solution was prepared by blending and dissolving dimethylpolyorganosiloxane as a mold release agent and a solvent in the proportions shown in Table 2. Preparation of printed matter and evaluation thereof The coating solution was bar-coated onto a polypropylene synthetic paper as a substrate, and dried by heating at 120° C. for 15 minutes to prepare a receiving sheet having a receiving layer with a thickness of 7 μm. The receiving sheet is 100mm x 150mm.
After cutting to a size of 1, a cyan test pattern (14 gradation stripes) was printed on the receiving layer by sublimation thermal transfer using a video printer (manufactured by Hitachi, VY-50). The reflected optical density of the obtained printed matter immediately after printing and after the plasticizer resistance test were measured. In addition, the reflected optical density is Macbeth RD9.
14 (manufactured by Macbeth). The results of the dyeability evaluation, which is the reflected optical density immediately after printing, are also listed in Table 2 below. Dyeability The reflective optical density of the printed surface of the printed matter was measured immediately after printing, and the value was defined as the dyeability. Example 2 and Comparative Examples 1 and 2 A coating solution was prepared, a receiving sheet and a printed matter were prepared in the same manner as in Example 1, except that the formulation of the coating solution was changed as shown in Table 2. The obtained printed matter was evaluated. The evaluation results are also listed in Table 2. The receptor sheets obtained in Examples 1 and 2 were fused with the coloring material layer of the transfer film,
Thermal transfer printing was possible without problems such as wrapping around the printer roll, contaminating the roll surface, or getting caught in the printer. Furthermore, no bleeding was observed in the dots of the obtained printed matter when observed under a microscope. [0041]
Table 1
Polymer with film-forming ability (component II)
kinds
Product name
A: Thermoplastic polyester resin Vylon 290 B:
Vinyl chloride-vinyl acetate copolymer resin Denka Vinyl #1000A (1) The above A has an average molecular weight of about 20,000 to 25,000,
Glass transition temperature 77°C, softening temperature 180°C. Toyobo (
Manufactured by Co., Ltd. (2) The above B is a copolymer of 86% by weight of vinyl chloride and 14% by weight of vinyl acetate with an average degree of polymerization of about 430. Manufactured by Denki Kagaku Kogyo Co., Ltd. [0042]
Table 2 Coating composition formulation Example 1
Example 2 Example 3 Comparative example 1 Comparative example 2
Component I 2.2
5g 1.12g 2.25g
- - Component II A
12.75g 12.75g
12.75g 15g
15g B
− − −
− − Solvent
Toluene 42.5 g 42.5
g - 42.5 g
- MEK 42
．． 5 g 42.5 g 85 g
42.5 g 85 g Epicote 828 - 1.13 g
− − −
Mold release agent 1g
1 g 1 g
1 g 1 g evaluation Dyeing property 1.
28 1.40 1.20
1.10 1.04 [Effects of the Invention] As explained above, the receiving layer of the receiving sheet for sublimation thermal transfer printing prepared using the coating agent of the present invention has excellent dye dyeing properties. be.

Claims (3)

[Claims] 1. A receiving sheet for sublimation thermal transfer printing, comprising as essential components a urea group-terminated polyalkylene oxide having a urea group at the end of its main chain, and a polymer having film-forming ability. A coating agent for forming a dye-receiving layer. 2. The coating agent for forming a dye-receiving layer according to claim 1, wherein the urinary group-terminated polyalkylene oxide comprises a compound represented by the following general formula. [Formula 1] (In the above formula, m is an integer of 0 to 5, and n is an integer of 100 or less.) 3. A receiving sheet for sublimation thermal transfer printing, comprising a dye receiving layer comprising the coating agent according to claim 1 formed on a substrate.