JPS6094387A - Thermal transfer recording medium - Google Patents

Abstract

PURPOSE:To obtain a luterless color-transferred picture by preventing the lowering of sensitivity during the thermal transfer period by providing a thermally transferable color layer containing a color whose grain size distribution is of at least two or more peaks on a supporter. CONSTITUTION:A paint liquid for forming a thermally transferable color layer, containing colors whose grain size distribution is of at least two or more peaks, is obtained by mixing colors (1) and (2), colors (1) and (3), colors (2) and (3), and colors (1), (2), and (3), in which the color (1) has peak at 0.01-5mmu, the color (2) has peak at 10-30mmu, and the color (3) has peak at 40-90mmu. The colors used include various dyes or pigments which are being used in every fields. The paint liquid is coated on a supporter, e.g., papers, resin films, metal sheets, etc., and dried to obtain a thermal transfer recording medium with a thermally transferable color layer of a thickness of 15mum or less.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a thermal transfer recording medium, and more particularly to a thermal transfer recording medium capable of obtaining a dye transfer image with no gloss.

[Prior Art] A thermal transfer recording medium has been conventionally used as a recording medium for transferring and forming an image on a recording sheet such as plain paper using a thermal printer, a thermal facsimile, or the like. This thermal transfer recording medium has at least one coloring material layer on a support, and the coloring material layer includes, for example, a layer containing a coloring agent made of a dye such as a pigment and a heat-fusible substance. etc. are known. In addition, films with excellent surface smoothness and dimensional stability are used as the support in order to obtain good reproducibility of the color transfer image obtained from the color material layer coated on the support. ing.

Dye transfer images (printed images) obtained from such conventional thermal transfer recording media have extremely smooth and glossy surfaces, which causes significant eye strain when the records need to be read for a long time. Additionally, there is a drawback that the dye transfer image cannot be seen depending on the condition of the light source. On this point, JP-A-56
JP-A-164891 proposes mixing a matting agent into the coloring material layer. However, according to this technology, compared to a thermal transfer recording medium that has a coloring material layer that does not contain a matting agent, the thickness of the coloring material layer must be increased in order to obtain a dye transfer image of the same density. Therefore, there is a drawback that the transfer sensitivity is lowered.

[Object of the Invention] An object of the present invention is to provide a thermal transfer recording medium capable of obtaining a matte dye transfer image without causing a decrease in sensitivity during thermal transfer.

Other objects of the invention will become apparent from the following description of the specification.

[Summary of the Invention] As a result of intensive research, the present inventor has discovered that in a thermal transfer recording medium having a heat-sensitive transferable color material layer containing a colorant on a support, the particle size distribution curve of the colorant is at least 2. It has been discovered that the above object can be achieved by having two peaks, and the present invention has been achieved.

[Structure of the invention] The present invention will be described in further detail below.

The thermal transfer recording medium of the present invention has at least one coloring material layer on a support, and the particle size distribution curve of the coloring material contained in the coloring material layer has at least two peaks.

The colorant used in the present invention preferably has an average particle diameter ratio within the following range. It is more preferably b/a-1, Ei or more.

Furthermore, the particle size distribution curve of the colorant such as carbon black used in the colorant layer of the present invention has at least two peaks.
For example, if the mountain (peak) is ■0.0
1~5ml range, ■10~30mpL range, 040
When preparing three types of colorants each in the range of ~90 mg, these ■ and ■, ■ and ■, ■ and ■, and ■, ■, (
Any mixture of Φ may be used. Note that methods for obtaining colorants such as carbon black that have two or more peaks (for example, three peaks) are not limited to the above-mentioned mixed use, but also by adjusting the temperature of the processing furnace or the amount of oxygen gas. It is also possible to produce a coloring agent such as a carbon blank having a two-peak distribution or a three-peak distribution by changing it during the manufacturing process, and use this.

In the present invention, the interval in average particle size between the mode of the largest peak of two or more peaks in the particle size distribution curve and the mode of the next largest peak is preferably 1 to 30 m p-, and further, It is more preferably 511#L or more, and most preferably 7m,p or more.

As the coloring agent of the present invention, various dyes or pigments that have been widely used in the art can be used without any particular restrictions. For example, a substance that can be dissolved or dispersed in the binder in the colorant layer when melted, has a color, and is solid or semi-solid at room temperature may be used as a colorant, such as various pigments known in the art. can be used. Specifically, the following can be mentioned. That is, as yellow pigments, Kayalon Polyester Light Ye o-5O-5 (Nippon Kayaku), Oil Yellow 5-7 (white clay), Eisen Subiron GRH Special (Hodogaya), Sumiplast Yellow F
G (Sumitomo), Eisensviron Yellow GRH (Hodogaya), etc. are preferably used. Red pigments include Diaceritone Fast Red R (Mitsubishi Kasei), Dianix Brilliant Red BS-E (Mitsubishi Kasei), Sumipura Tread FB (Sumitomo), Sumipura Tread HFG
(Sumitomo), Kayalon Polyester Pink RCL-E
(Nippon Kayaku), Eizenspiron Red GEH Special (Hodogaya), etc. are preferably used. As blue pigments, Diaceritone Fast Brilliant Blue R (Mitsubishi Kasei), Dianic Sprue EB-E (Mitsubishi Kasei), Kayalon Polyester Blue B-3F Conch (Nippon Kayaku), Sumiplast Blue 3R (Sumitomo), Sumiplast Blue G (Sumitomo) and the like are preferably used. In addition, as yellow pigments, Hansa Yellow 3G, Taldrazine Lake, etc. are used, as red pigments, brilliant carmine FB-Pure (Yamao Color), brilliant carmine 6B (Yamao Color), Alizarin Lake, etc. are used, and as blue pigments, As the pigment, Cerulean Blue, Sumikabrintocyanine Blue GN-0 (Sumitomo), Phthalocyanine Blue, etc. are used, and as the black pigment, carbon black,
Oil black or the like is used. In addition, metal particles or metal oxides may also be used. Among these, a combination of colorants having the same color tone is preferred because it does not cause color turbidity. Note that, in the present invention, the term "similar in tone" refers to the same color having the same tone within the hue as visually recognized. For example, in terms of absorption wavelengths, those whose main absorption wavelengths differ within a range of Ionm, preferably 5 nm, are considered to be of the same type.

The coloring material layer of the present invention contains one or more heat-melting substances. As this heat-fusible substance, conventionally known heat-fusible substances can be used without any particular limitations.

The thermofusible substance preferably used in the present invention has a softening point (
The melting point (measured by the ring and ball method) or the melting point (measured by the purlin MPJ-2 type) is 120°C or less, particularly preferably the melting point is 50 to +20'C.

Specific examples of heat-melting substances preferably used in the present invention include paraffin waxes such as paraffin wax and microwax, natural waxes such as beeswax, carnauba wax, and wood wax, and ester waxes such as Hoechst wax. , stearic acid, palmitic acid,
Higher fatty acids such as behenic acid, myristic acid, and 1,20-eicosanniic acid, higher alcohols such as stearyl alcohol and balmityl alcohol, higher amides such as stearamide, oleamide, and palmitylamide, butyl stearate, ethyl palmitate, and myristyl. Examples include esters such as stearate.

The composition ratio of the coloring material layer of the present invention is 50 to 90% of the heat-melting substance.
(wt%, the same applies hereinafter), colorant small particle group 2.5 to 1
5%, large particles of colorant 2.5-15%, resins 5-3
It is preferably 0%, and the composition ratio of the small particles and large particles of the colorant is 1:10 to 10:1, preferably 2:8.
The ratio may be in the range of ~8:2.

The color material layer of the present invention may contain various additives in addition to the above components. For example, examples of the thermally conductive substance include metals with good thermal conductivity such as aluminum, copper, and zinc. Such a thermally conductive substance melts the coloring material layer with heat,
It promotes the conduction effect of heat for softening or sublimation. Furthermore, vegetable oils such as castor oil, linseed oil, and olive oil, animal oils such as whale oil, and mineral oils may be suitably used as softeners.

Coating methods suitable for applying a coloring material layer onto a support by solvent coating, hot melt coating, etc. are known in the art, and these techniques can also be used in the present invention. For example, by solvent coating the coating solution of the present invention using any known technique such as a reverse roll coater method, an extrusion coater method, a gravure coater method, or a wire coater method, and then removing the solvent, a color of 15W or less can be obtained. A material layer can be applied.

Further, the thermal transfer recording medium of the present invention has at least one coloring material layer of the present invention, and may have other constituent layers such as a subbing layer, an intermediate layer, or a top coat layer. . That is, for example, examples of the undercoat layer include silicone resin, melamine resin, polyvinacetal resin, polyethylene, polyvinyl chloride, polyvinylidene chloride, fluorine resin, etc., and the application of the undercoat layer is performed on the basis of the color material layer. This can be done prior to coating.

Note that the support used as a base material for the thermal transfer recording medium of the present invention is preferably a support that has heat-resistant strength, high dimensional stability, and high surface smoothness.

Heat resistance strength requires strength and dimensional stability to maintain the toughness of the support without becoming softened or plasticized by the heating temperature of a heat source such as a thermal head, and surface smoothness requires heat melting on the support. It is desired that the layer containing a sexual substance has sufficient smoothness to exhibit a good transfer rate. The smoothness was determined by a smoothness test using a Beck tester (JIS P 8119) for 100 seconds.
ec or more is better, and if it is 300 sec or more, images with better transfer rate and reproducibility can be obtained. Materials include, for example, papers such as plain paper, condenser paper, laminated paper, and coated paper; resin films such as polyester, polycarbonate, polyethylene, polyethylene terephthalate, polystyrene, polypropylene, and polyimide; and paper-resin film composites. Metal sheets such as aluminum foil are preferably used. The thickness of the support is usually about 60 mm or less in order to obtain good thermal conductivity.
In particular, it is preferably 2 to 20 tons. Furthermore, in the thermal transfer recording medium of the present invention, the structure of the back side of the support is arbitrary.

[Effect of the invention] According to the invention, the particle size distribution curve of the colorant is at least 2
Since the paper has two peaks, it is possible to achieve the above-mentioned object of the present invention, it does not cause eye fatigue even when read for a long time, and high sensitivity allows high-speed recording (printing).

[Example] Examples are given below, but the embodiments of the present invention are not limited thereto. In addition, "1 copy" used below means "
Parts by weight.

Example 1 50 parts of carnauba wax, 20 parts of low molecular weight polyethylene, and 10 parts of olive oil were dispersed in 10 parts of small carbon black particles with an average particle size of 30a+g and 10 parts of large carbon black particles with an average particle size of 5B+og. It was added to a xylene dispersion liquid and stirred at 60°C to obtain a coating liquid for a coloring material layer. This coating solution was coated onto a polyethylene terephthalate film support with a thickness of 5.21 μm using a wire parer, and dried to obtain a thermal transfer recording medium sample ① of the present invention having a coloring material layer with a thickness of 3.1 μm. Obtained. Regarding this sample ■, a high-sensitivity thermal printer
An attempt was made to record on plain paper using a thin M-type (prototype machine equipped with an in-thermal hand). As a result, a clear dye transfer image with low gloss and easy to read was obtained. This dye transfer image was heated at 75°C using the method described in JIS Z 8741.
The glossiness was measured at an angle of 7.4%.

Example 2 Same as in Example 1 except that the colorant was replaced with a mixture of 5 parts of carbon black small particles with an average particle size of 5 mK and 15 parts of Torikawa carbon black large particles with an average particle size of 30. A thermal transfer recording medium sample (2) of the present invention having a thick coloring material layer was obtained. As a result of trying to print this sample (2) in the same manner as in Example 1, a clear dye transfer image with little gloss and easy to read was obtained. The glossiness of this dye transfer image was measured using the same method as in Example 1 and was found to be 8.8%.

Example 3 In Example 1, the colorant was mixed with small particles 4 with an average particle size of 5m7z.
group, a medium particle group with an average particle size of 3Qm g, and an average particle size of 5B
The colorant layer had the same thickness except that it was replaced with a mixture of 67 parts of carbon black with m7L large particles,
A thermal transfer recording medium sample (2) of the present invention was obtained. As a result of trying to print this sample (2) in the same manner as in Example 1, a clear dye transfer image with little gloss and easy to read was obtained. The glossiness of this dye transfer image was measured using the same method as in Example 1 and found to be 111.5%.

Comparative Example 1 Comparative thermal transfer having the same thickness of colorant layer as in Example 1 except that the colorant was replaced with a xylene dispersion in which 20 parts of carbon black with an average particle size of 30 layers was dispersed. A recording medium sample @ was obtained. When printing was attempted on this sample (2) in the same manner as in Example 1, only a glossy dye transfer image was obtained. The glossiness of this dye transfer image was measured using the same method as in Example 1 and was found to be 28%.

Patent applicant: Konishiroku Photo Industry Co., Ltd. Agent: Patent attorney Nobuaki Sakaguchi (1 other person)

Claims (1)

[Claims] 1. A heat-sensitive transfer recording medium having a heat-sensitive transferable color material layer containing a colorant on a support, wherein a particle size distribution curve of the colorant has at least two peaks.