JPH02229076A - Production of sublimable thermal transfer recording medium - Google Patents

Abstract

PURPOSE:To level the irregularities of a layer caused by, for example, the cohesion of a particulate dye and to improve an unevenness of density caused by the partial exposure of a dye supply layer by mixing a surfactant in a coating liquid for forming the dye supply layer. CONSTITUTION:On a substrate, a dye supply layer 4 at least containing a sublimable dye in undissolved particle forms and an organic binder and a dye transfer contributing layer 5 containing at least a sublimable dye in molecular dispersing forms and an organic binder are laminated in this order from the side of the substrate. In the transfer contributing layer, the concentration of the dye is normally 5 - 80% and preferably the order of 10 - 60%. In the dye supply layer, the concentration of the dye is preferably 5 - 80%.

Description

[Detailed description of the invention] 〔Technical field〕 The present invention relates to a method for manufacturing a sublimation type thermal transfer recording medium.

[Prior art]

Conventionally, two ink layers are formed, and the dye concentration of the outermost ink layer (the dye concentration of the ink layer on the support side) is the dye concentration of the outermost ink layer (the dye diffusion coefficient of the outermost ink layer), and the dye diffusion coefficient of the ink layer on the support side increases sensitivity and maintains storage stability. A thermal transfer sheet has been proposed (see JP-A-63-47193).

There is also a thermal transfer paper that is used many times by dyeing a base film with 2 to 20 times as much dye as the ink layer and supplying the dye from the base film to the ink layer each time (Japanese Patent Laid-Open No. 176186/1986). reference).

However, these conventional printers still lack sufficient ability to print multiple times. Moreover, in the latter case, since a large amount of dye is present in the base film itself, the strength of the film decreases, and there is a drawback that it cannot be put to practical use as a ribbon.

Therefore, in Japanese Patent Application No. 63-268204, the present inventors created a two-layer ink layer, separated the functions into a dye supply layer and a dye transfer contribution layer, and caused particulate dye to exist in the dye supply layer. Improved the ability to print multiple times.

However, due to the presence of this particulate dye, unevenness occurs on the surface of the lower layer (dye supply M) due to aggregation of dye particles.

Due to this unevenness, the large portion of the convex portion is not covered with the upper layer (dye transfer contributing layer) and becomes exposed, and during recording, dye transfer occurs directly from the lower layer (supply layer) to the receiver, resulting in density unevenness. As a result, image uniformity tends to deteriorate, and there remains room for improvement. The present invention is a further improvement of this prior invention.

〔the purpose〕

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a sublimation thermal transfer recording medium that overcomes the conventional drawbacks, has improved multi-printing characteristics, prevents agglomeration of dye particles, and improves single-image uniformity.

〔composition〕

As a result of intensive research to achieve the above object, the present inventors have found that, on a substrate, in order from the substrate side, a dye supply layer containing at least an undissolved particulate sublimable dye and an organic binder, and at least In a method for producing a sublimation thermal transfer recording medium, which comprises laminating a dye transfer contribution layer containing a molecularly dispersed sublimable dye and an organic binder, a surfactant is added to the coating solution for forming the dye supply layer. It has been found that the above object can be achieved by providing a method for manufacturing a sublimation type thermal transfer recording medium characterized by the following.

In the sublimation type thermal transfer recording medium of the present invention, the dye supply layer contains at least an undissolved particulate sublimable dye, and the dye transfer contribution layer contains at least a molecularly dispersed sublimable dye.

A feature of the method for manufacturing the sublimation thermal transfer recording medium of the present invention is that a surfactant is added to the coating liquid used to form the dye supply layer. By adding a surfactant, it is possible to prevent the dye particles from agglomerating in the resin binder, improve the dispersibility of the dye particles, and provide the following effects even during storage.

(i) It is possible to prevent the dye from being deposited on the surface, and as a result, background staining can be prevented.

(il) By preventing the aggregation of dye molecules dissolved in the binder and particulate dye, it is possible to prevent a decrease in recording density in the first printing.

(■) The surface of the layer becomes smooth, so there is no need for a super calender, etc.), the uniformity of the image is improved, and the recording performance is improved.

Specific examples of surfactants to be added to the dye supply layer coating solution include sorbitan monooleate, sorbitan sesquioleate, sorbitan monostearate, polyoxyethylene alkyl or alkyl allyl ether, and other nonionic surfactants that reduce HLB. 10 or less, aliphatic amines, aliphatic quaternary ammonium salts, metal soaps, etc.

The amount of surfactant added is 0.1 to 3 in the dye supply layer.
0% by weight is suitable. If it is less than 0.1% by weight, the desired effect cannot be obtained, and if it is more than 30% by weight, dye diffusion (supply) can be prevented.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings. FIG. 1 is an explanatory diagram showing the structure of the sublimation type thermal transfer recording medium of the present invention, in which 1 indicates a support, 2 is an ink layer composed of a dye supply layer 4 and a dye transfer contribution layer 5, and 3 6 indicates an image receptor such as paper, and 6 indicates a thermal head.

By mixing undissolved particulate dye in the dye supply layer and creating an appropriate concentration gradient and/or diffusion coefficient gradient between the dye supply layer and the dye transfer contribution layer, it is possible to perform multiple recordings with good quality while maintaining the initial gradient each time. becomes.

However, here, undissolved particulate dye refers to the undissolved particulate dye that is formed when the ink (organic binder + sublimable dye + solvent) is applied and dried during the formation of the ink layer.
It refers to a dye that cannot be completely dissolved in an organic binder and precipitates in the form of particles, and even if the binder and dye are the same, the presence of undissolved particulate dye differs depending on the solvent. The presence or absence of undissolved particulate dye can be easily identified by electron microscopy after the dye supply layer is formed. The particle size of the undissolved particulate dye varies depending on the layer thickness of the dye supply layer, but is 0.01 μm to 20 μm, preferably 1.0 μm to 5 μm.

In addition, the state of the dye in the dye transfer contribution layer is dispersed in a monomolecular state that actually contributes to transfer, which prevents uneven transfer density and prevents the dye from forming between the dye supply layer and the dye transfer contribution layer. This is desirable because it keeps the concentration gradient stable.

Next, the thickness of the dye transfer contributing layer is generally 0.05 to 5.
μm, preferably 0.1 to 2 μm.

The thickness of the dye supply layer is generally 0.1 to 20 μm.
, preferably 0.5 to 10 μm.

Further, known sublimable dyes, binders, etc. used in the transfer contributing layer and dye supply layer of the present invention can be used.

Sublimable dyes are dyes that sublimate or vaporize at temperatures above 60°C, and are mainly disperse dyes, oil-soluble dyes, and other dyes used in thermal transfer printing.For example, C, I, disperse yellow, etc. 3,8°9.16,41,54
,60,77.116 etc.,C,1,dispersed thread 1.4,6,11,15.17,55,59,60
, 73.83, etc., C, 1, Disperse Blue's 3.
14,19,26,56,60゜64.72,99,1
08 etc., C, 1, Solvent Yellow 77.1.1
6 etc., C, 1, Turben 1-Red 23.25.2
7 etc. C, 1, Solvent Blue 36.83,105
These dyes can be used singly or in combination.

Thermoplastic or thermosetting resins are used as binders for the dye transfer contributing layer and the dye supplying layer, and among them, resins with relatively high glass transition points or high softening properties include:
For example, vinyl chloride resin, vinyl acetate resin, polyamide, polyethylene, polycarbonate, polystyrene, polypropylene, acrylic resin, phenol resin, polyester, polyurethane, epoxy resin, silicone resin, fluorine resin, butyral resin, melamine resin, natural rubber, synthetic rubber. , polyvinyl alcohol, cellulose resin, etc.

These resins can be used alone, but several types may be mixed or a copolymer may be used.

Furthermore, when creating a difference in glass transition or softening temperature between the dye transfer contribution layer and the dye supply layer, resins, natural or synthetic rubbers, or waxes having a glass transition temperature of 0°C or less or a softening temperature of 60°C or less are preferable. , syndiotactic 1,2-polybutadiene (JSRRB8 as a commercial product)
10,820,830 Japan Ichisei Rubber); olefin copolymers and terpolymers containing acid or non-acidic acids (commercially available Dexon XEA-
7, Dexon Chemical); Ethylene-acid picopolymer (
400 & 40OA as commercial products.

405, 430. Allied Fibers &Plastics; P-3307 (EV150), P-280
7 (EV250), Mitsui DuPont Polychemicals); low molecular weight polyolefin polyols and derivatives thereof (commercially available products include Polytail H, HE Mitsubishi Chemical Industries); brominated epoxy resins (YDI3: 340., 400.500.
600 Tsukuto Chemical); Novolac type epoxy resin (YDC
N-701.

702, 703 Tobu Kagaku): Thermoplastic acrylic trusion (Titanal LR1075, 1080, 1081
゜10g2.1063.1079 Mitsubishi Rayon); Thermoplastic acrylic emulsion (LX-400, LX-'4
50. Mitsubishi Rayon); polyethylene oxide (Alcox E-30, 45, Alcox R-150,
400,1000 Meisei Chemical Industry) = caprolactone polyol (Plaxel H-1.4, 7. Daicel Chemical Industry); etc. are preferred, especially polyethylene oxide,
Polycaprolactone polyol is useful in practice, and is preferably used in the form of a mixture of the above-mentioned thermoplastic or thermosetting resin and one or more of the above.

The dye concentration of the transfer contributing layer is usually 5 to 80%, preferably
It is about 10 to 60%.

Further, the dye concentration in the dye supply layer is preferably 5 to 80%, but when creating a dye concentration gradient between the dye transfer contribution layer and the dye supply layer, the dye concentration in the dye transfer contribution layer is 1%. .1 to 5 times, preferably 1.5 to 3 times.

Films such as condenser paper, polyester film, polystyrene film, polysulfone film, polyimide film, and polyamide film are used as the base sheet, and conventional adhesives are used between the base sheet and the dye supply layer as necessary. A conventional heat-resistant lubricating layer may be provided on the back surface of the base sheet, if necessary.

Up until now, we have described an example in which the dye layer is divided into two layers, but
If an appropriate difference in the amount of dye transfer is created and the functional separation as intended by the present invention can be achieved, it is possible to form the dye layer into a multilayer of two or more layers.

Although the above description has been made with reference to a recording method using a thermal head, the transfer medium of the present invention can also be applied to a recording method in which recording thermal energy is applied by a method other than a thermal head, for example.
It can also be used for methods utilizing Joule heat generated by electrical current in a medium such as a thermal printing plate, a laser beam, or a support and/or an ink layer. Among these, the so-called electrical thermal transfer method, which uses Joule heat generated in the medium, is the most well-known, for example, USP 4.

103.066, JP-A-57-14060, JP-A-57
=11080, or in many documents such as JP-A-59-9096.

When used in this current transfer method, the support is made of resins with relatively good heat resistance such as polyester, polycarbonate, triacetylcellulose, nylon, polyimide, aromatic polyamide, etc., as well as aluminum, copper, iron, tin, zinc, etc.
Supports in which metal powders such as nickel, molybdenum, and silver and/or core-shaped powders such as carbon black are dispersed to adjust the resistance value to between that of an insulator and a good conductor; A support on which a conductive metal is deposited or sputtered may be used. The thickness of these supports is desirably about 2 to 15 microns in consideration of Joule heat conduction efficiency.

Further, when used in a laser beam transfer method, a material that absorbs laser beams and generates heat may be selected as the support. For example, a conventional thermal transfer film containing a light absorption heat conversion material such as carbon, or a film in which an absorbing layer is formed on the front and back surfaces of a support is used.

EXAMPLES Hereinafter, the present invention will be explained in more detail based on the following examples, but the present invention is not limited thereto.

Example 1 Two kinds of dye supply layer and dye transfer contributing layer phase inks having the following compositions were prepared, and the dye supply layer was 4.5 μm thick and the dye transfer contributing layer was 0.8 μm thick on an 8.0 μm polyimide film support. The coating was applied and dried to form a sublimation type thermal transfer recording medium.

Solvent Toluene Methyl Ethyl Ketone Example 3 In Example 1, the surfactant was Rheodol 5P-Ll.
(manufactured by Kao Corporation) A sublimation type thermal transfer recording medium was formed in the same manner as in Example 1 except that the amount was changed to 5 parts by weight.

Example 4 Two types of dye supply layer and dye transfer contributing layer phase inks having the following compositions were prepared, and the dye supply layer was 4.5 μm thick and the dye transfer contributing layer was 0.8 μm thick on an 8.0 μm polyimide film support. The coating was applied and dried to form a sublimation type thermal transfer recording medium.

Example 2 In Example 1, the surfactant was Emazol 0-15R.
A sublimation type thermal transfer recording medium was formed in the same manner as in Example i except that the material was changed to (manufactured by Kao Corporation).

Solvent Toluene 6040 Methyl Ethyl Ketone 6040 Surfactant Turpon 5-80 5
0 Example 5 In Example 4, the surfactant was Rheodol 5P-01.
A sublimation type thermal transfer recording medium was formed in the same manner as in Example 4 except that the material was changed to (manufactured by Kao Corporation).

In Example 1, after forming the dye supply layer, a scanning electron microscope S-31OA (manufactured by Hitachi, Ltd.) was used to
When observed under 00x magnification, it was found that in the dye supply layer, needle-like crystalline dye particles with an average particle size of about 3.0μI11 were present in the dye supply layer in a state of being densely spread over one surface. It was confirmed that

This was also true for Examples 2-5.

Regarding the sublimation type thermal transfer media of Examples 1 to 5 above, the first
As shown in the figure, an image receiving paper from Hitachi Video Printer VY-50 supply VY-8100, which is an image receiving paper for sublimation type thermal transfer recording, is used as an image receptor 3, and a thermal head 6 is used as printing conditions with an applied power of 455 mW/ As a result of printing multiple times at the same location with dots, Examples 1 to 5 were obtained.
Good results were obtained in which there was no density unevenness, the image was uniform, and there was no substantial difference in print density reduction even when the number of printings was increased.

However, the print density (optical density) is Macbeth Densitometer RD-
Density unevenness was visually evaluated using 914.

〔effect〕

By mixing a surfactant into the coating solution for forming the dye supply layer during the production of the sublimation type thermal transfer recording medium of the present invention, unevenness of the layer due to aggregation of particulate dye is improved, and part of the dye supply layer is Density unevenness due to exposed areas has been improved.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the structure of the sublimation type heat-sensitive transfer material of the present invention. 1...Support 2...Ink layer 3...Image receptor 4...Dye supply layer 5...Dye transfer contributing layer 6...1 thermal head

Claims (1)

[Claims] 1. On the substrate, in order from the substrate side, a dye supply layer containing at least an undissolved particulate sublimable dye and an organic binder, and a dye containing at least a molecularly dispersed sublimable dye and an organic binder. 1. A method for producing a sublimation thermal transfer recording medium comprising laminating transfer contributing layers, the method comprising adding a surfactant to the coating liquid for forming the dye supply layer.