JPH03239590A - Thermal transfer image receiving sheet - Google Patents

Abstract

PURPOSE:To obtain a thermal transfer image receiving sheet generating no curling by the heat applied at the time of printing by a method wherein a material having an m.p. lower than that of an elastic layer is provided in the elastic layer in a scattered state. CONSTITUTION:An elastic layer 2 and an image receiving layer 3 having dyeing properties are successively provided on a base material 1 and a material 4 having a low m.p. is provided in the elastic layer in a scattered state. It is necessary that the material having a low m.p. is sufficiently melted and heated by the heat applied at the time of printing and a material having the m.p. range of about 50 - 150 deg.C is selected and wax such as polyethylene wax or montan wax or polyethylene glycol with an MW of 1000 or more is designated. The elastic layer is formed by applying the same to the base material or laminating one preformed into a film form to the base material.

Description

Detailed Description of the Invention: "Industrial Application Field" The present invention relates to a thermal transfer image-receiving sheet, which is formed by sequentially providing an elastic layer and an image-receiving layer on a base material, and relates to a thermal transfer image-receiving sheet that is capable of preventing curling caused by heat applied during printing. This relates to an image-receiving sheet.

[Conventional technology J Thermal recording method, in which a recorded image is obtained simultaneously with an input signal, is used in a wide variety of applications such as facsimiles, computer terminal printers, and measuring instrument printers because the equipment is relatively simple, inexpensive, and has low noise. has been done. The most commonly used recording medium for these thermal recording methods is so-called color-forming type thermal recording paper, which is provided with a recording layer that develops color by causing physical or chemical changes when heated. However, color-forming type thermal recording paper tends to develop unnecessary color during the manufacturing process and storage, and the storage stability of recorded images is also poor, and color fading occurs when it comes into contact with organic solvents or chemicals. The problem is that it is easy to cause

Therefore, a recording method using a recording medium that uses colored coloring material itself as a recording medium to replace the color-forming type thermal recording paper has been proposed.
No. 6 discloses that a coloring material that is solid or semi-solid at room temperature is coated on a support such as paper or a polymer film, and
A method has been proposed in which a recording paper is brought into contact with a colorant on a support, the colorant on the support is heated by a thermal recording head, and the colorant is selectively transferred to the recording paper to obtain a recorded image. ing.

In this recording method, the coloring material on the support is melted, evaporated, or sublimated by heat, and transferred to the recording paper to obtain a recorded image by adhesion, adsorption, or dyeing. In particular, a sublimable dye is used as the coloring material. Since this recording method produces images with excellent gradation, attempts are being made to apply it to full-color recording.

In addition to plain paper, such recording paper includes JP-A-57-
107885, U.S. Pat. No. 3,601,484, etc., in order to form an image-receiving layer containing a thermoplastic resin as a main component, and to improve recording sensitivity, image quality, etc., JP-A-60236794, JP-A-61-1
As described in Japanese Patent No. 44394, an image-receiving sheet is used in which an elastic layer such as a thermoplastic resin is interposed between a support and an image-receiving layer.

By providing an elastic layer on the base material, it is possible to obtain a thermal transfer image-receiving sheet with excellent image quality and recording sensitivity, but the heat applied during printing causes the resin and other materials that make up the elastic layer to shrink. Since the degree of shrinkage differs between the elastic layer and the base material, distortion occurs, which causes curling in the thermal transfer image-receiving sheet, which significantly impairs the appearance of the printed matter.

Furthermore, in order to solve this problem, Japanese Patent Application Laid-Open No. 633152
Selecting a material with high rigidity as the base material as in Japanese Patent Application Laid-open No. 112693/1983 and Japanese Patent Laid-open No. 62-1
Although methods such as providing a highly rigid layer on a base material have been proposed as in Japanese Patent No. 98497, sufficient effects may not be obtained or there may be problems with paper passing properties. On the other hand, JP-A-63214484, JP-A-63-290790
No. 62-261486, a method has been proposed in which a layer made of an elastic layer material is provided on one or both sides of a base material with little thermal deformation. There were problems such as having to make the sheet larger and making the sheet more time-consuming.

``Problems to be Solved by the Invention'' The present invention aims to prevent curling by heat applied during printing in a thermal transfer image-receiving sheet in which an elastic layer and an image-receiving layer having dye-dyeability are sequentially provided on a base material. It is an object of the present invention to provide a thermal transfer image-receiving sheet that does not cause thermal transfer.

"Means for Solving the Problems" The present invention provides a thermal transfer image-receiving sheet in which an elastic layer and an image-receiving layer having dye-dyeability are sequentially provided on a base material. It is characterized by having a material with a lower melting point interspersed therein.

"Function" To explain the present invention based on the drawings, FIG. 1 is a longitudinal cross-sectional view of a thermal transfer image-receiving sheet of the present invention, in which an elastic layer 2 is provided on a base material 1, and an image-receiving layer having dye-dyeability. 3 in sequence, and is characterized in that it is constructed so that low melting point materials 4 are scattered in the elastic layer. FIG. 2 shows a conventional thermal transfer image-receiving sheet, in which the elastic layer contracts due to the heat applied during printing, causing distortion and causing the sheet to curl.

On the other hand, in the thermal transfer image-receiving sheet of the present invention, as shown in FIG. 3, the material 4 having a low melting point is interspersed in the elastic layer 2, so that it is more easily deformed than other parts of the elastic layer. It absorbs and disperses the distortion that occurs between the elastic layer 2 and the base material 3 that contract due to the heat applied during printing, and prevents the entire sheet from curling significantly as a result. .

Further, in the present invention, as shown in FIG. 4, an elastic layer 2 is formed on a base material 1 in a form in which a low melting point material 4 is dispersed therein, and an image receiving layer 3 is formed on the elastic layer. In this case, the stress caused by the contraction of the elastic layer gathers around the material 4 which has been melted and softened by the heat applied during printing, and the elastic layer 2 is destroyed (see Fig. 5). ), as a result, the distortion that causes curling is absorbed and dispersed, and curling can be prevented.

The base material may be appropriately selected depending on the purpose from various known sheet materials such as plain paper, polymer film, or synthetic paper, but a sheet material with excellent dimensional stability against heat should be used. is desirable, and for this reason, plain paper is particularly preferably used. The plain paper referred to here is, for example, paper obtained by ordinary paper making with cellulose bulk as the main component and the addition of paper strength agents, sizing agents, fixing agents, and inorganic or organic pigments, and paper obtained from this. This includes paper that has improved surface properties by size-pressing oxidized starch or by providing a pre-coat layer mainly composed of pigments such as clay. Paper with excellent properties is particularly preferably used.

Thermoplastic resins are generally used as materials for forming the elastic layer, including but not limited to polyethylene, polypropylene, polybutene-1, polyisobutylene, polypentene-1, polyhexene-1, and poly-3-methylbutene-1. 1. Polyolefins such as poly-4-methylpentene-1, poly-5-methylhexene-1, and copolymers thereof; styrene, vinyltoluene, acrylic ester, methacrylic ester, acrylonitrile, vinyl chloride, acetic acid Polymers and copolymers of vinyl monomers such as vinyl; condensation polymers such as polyester, polyamide, polycarbonate, polysulfone, epoxy resin, polyurethane; or cellulose resins, etc. are used by appropriately selecting one or more of them. .

In order to fully obtain the effects of the present invention, it is necessary to use a material with a low melting point.
It is necessary to sufficiently melt and soften the material by the heat applied during printing, and when selecting the material, it is necessary to select and use a material with a lower melting point than the material of the elastic layer.

The melting point range is 50-150°C, preferably 70-150°C.
A material with a temperature of about 120°C is selected. Examples of such materials include the following substances.

Waxes such as polyethylene wax, montan wax, ester wax, carnauba wax; molecular weight 100
0 or more polyethylene glycol; other low melting point, low softening point thermoplastic resins, and the like. Of course, it is not limited to these.

Furthermore, in order to obtain the desired effect of the present invention, it is important that the material with a low melting point is interspersed in the material of the elastic layer, and the desired effect of the present invention cannot be obtained if the material is melted and mixed. Therefore, it is desirable to select a combination that has poor compatibility between the material of the elastic layer and the material forming the low melting point region.

The amount of the above-mentioned low melting point substance to be used is not particularly limited, as the degree of curl and compatibility vary depending on the material used for the elastic layer, but it is generally about 10 to 50% by weight in the elastic layer. used.

Furthermore, in the elastic layer of the present invention, the appearance of the image receiving sheet,
Organic or inorganic pigments may be added for purposes such as improving processability during formation of the image-receiving layer, within a range that does not impede the effects of the present invention.

Examples of such pigments include inorganic pigments such as heavy calcium carbonate, light calcium carbonate, talc, clay, natural or synthetic silicic acids, titanium oxide, aluminum hydroxide, and zinc oxide; urea/formaldehyde resin powder, styrene pigments, and Styrene/acrylic crosslinked resins, phenolic resins, urea resins, melamine resins, aryl resins, polyimide resins, benzoguanamine resins, and more! Pigment cheeks are mentioned. Of course, it is not limited to these.

The method for forming the elastic layer specified in the present invention is not particularly limited, but it may be formed by coating it on a base material, or by pasting together a film that has been previously formed. Ru.

When forming an elastic layer by smearing, for example, a coating solution in which the material forming the elastic layer is dissolved or dispersed in water or a solvent is applied using a blade coater, air knife coater, roll coater, brush coater, curtain coater, bar coater, etc. The coating is applied onto the substrate using an on-machine or off-machine coater equipped with various known coating devices such as a coater and a gravure coater. The thickness of the elastic layer is adjusted to 1 μm or more, more preferably in the range of about 3 to 30 μm. The coating layer can be dried to form an elastic layer by various known methods such as steam heating, hot air heating, gas heater heating, electric heater heating, infrared heater heating, high frequency heating, laser heating, and electron beam heating.

It is preferable to subject the thus formed elastic layer to a smoothing treatment before or after forming the image-receiving layer, as this can further improve the image quality of the resulting image-receiving sheet. The smoothing process is appropriately performed using various known smoothing process methods such as a super calendar.

On the other hand, the elastic layer of the present invention can be produced by laminating sheet-like materials, which are preliminarily dotted with low-melting-point materials, onto a base material using various known methods such as dry lamination and wet lamination. Alternatively, an elastic layer-forming material in which a low melting point material is interspersed can be formed directly on the Go board using a method such as hot melt lamination or extrusion lamination. The thickness of the elastic layer when formed by a lamination method is generally about 5 to 100 μm, but preferably adjusted to a range of 20 to 50 μm.

In the image-receiving sheet of the present invention, the image-receiving layer provided on the elastic layer is not particularly limited, but generally a thermoplastic resin layer having an effective dyeing ability for sublimation dyes is preferably used. As the thermoplastic resin layer,
For example, polymers and copolymers of vinyl monomers such as styrene, vinyltoluene, acrylic esters, methacrylic esters, acrylonitrile, vinyl chloride, and vinyl acetate!
Combined; polyester, polyamide, polycarbonate,
Examples include condensation polymers such as polysulfone, epoxy resin, and polyurethane; or cellulose resins.

These thermoplastic resins may be used alone, or two or more resins having different properties may be used in combination. In addition, methylcellulose, ethylcellulose, hydroxypropylcellulose, starch, polyvinyl alcohol, polyamide resin, phenolic resin, melamine resin,
Other resin materials such as urea resin, urethane resin, epoxy resin, and silicone resin may be contained, and the image-receiving layer is modified by adding reactive compounds such as polyvalent isocyanate compounds, epoxy compounds, and organometallic compounds. It is also possible. However, it is necessary to keep the thermoplastic resin constituting the image-receiving layer within a range in which it does not lose its thermoplasticity.

Furthermore, the image-receiving layer contains, for example, heavy calcium carbonate, light calcium carbonate, talc, clay, etc., for the purpose of improving writing properties.
Inorganic and organic pigments such as natural or synthetic silicic acids, titanium oxide, aluminum hydroxide, zinc oxide, urea/formaldehyde resin powder, and various auxiliaries such as ultraviolet absorbers, antioxidants, antistatic agents, mold release agents, and lubricants. It is also possible to add agents.

The amount of the constituent components forming the image-receiving layer to be coated on the elastic layer is appropriately selected depending on the intended use of the image-receiving sheet, but is generally applied in an amount of about 2 to 15 g/rd in terms of dry weight.

In addition, for purposes such as improving the shelf life of printed materials,
It is also possible to form a barrier layer between the elastic layer and the image-receiving layer to prevent the movement of low-melting substances and the like.

In addition, on the image-receiving layer, for example, Japanese Patent Laid-Open No. 59-16568
As disclosed in Japanese Patent Application Laid-open No. 61-27290, etc., a thin heat-resistant peeling layer is formed which is mainly composed of a silicone resin or the like that has the property of transmitting sublimation dyes. It is also possible to prevent the dye or dye layer from being directly transferred from the color material transfer sheet.

Furthermore, in order to supplement the effects of the present invention, between the base material and the elastic layer,
Alternatively, a layer for preventing curling may be provided on the back side.

The thus obtained thermal transfer image-receiving sheet of the present invention exhibits extremely excellent performance as an image-receiving sheet, especially when a sheet containing a heat sublimable dye is used as a coloring material transfer sheet.

The heat-sublimable dye referred to in the present invention refers to a dye that does not cause colorant transfer even when it comes into contact with an image-receiving sheet under normal handling conditions; means a dye that causes the transition of
For example, use appropriate dyes selected from various dyes such as disperse dyes such as azo, nitro, anthraquinone, and quinoline, basic dyes such as triphenylmethane and fluoran, and oil-soluble dyes. be done.

The thermal transfer image-receiving sheet of the present invention can be produced not only by a thermal recording method in which contact heating is performed using a hot plate or a thermal head of a thermal printing unit, but also by a non-contact method using heat ray radiation such as an infrared lamp, YAG laser, or carbon dioxide laser. It is also useful for thermal transfer recording using a heating method.

"Example J" The present invention will be explained in more detail with reference to Examples below, but the present invention is of course not limited to these Examples. are "parts by weight" respectively.
and “% by weight”.

Example 1 60 parts of polyolefin resin fine particle dispersion (trade name: Chemivar A-100, no melting point, solid content 40%, manufactured by Mitsui Petrochemical Industries), polyethylene wax powder (trade name: AF30, melting point 105°C, average) Mix 20 parts of styrene-butadiene copolymer latex (product name: L-1599, solid content 48%, manufactured by Asahi Kasei ■) with 20 parts of styrene-butadiene copolymer latex (product name: L-1599, solid content: 48%, manufactured by Asahi Kasei) and add water to form a solid. A coating liquid for forming an elastic layer with a content of 40% was obtained.

Apply this coating liquid to commercially available art paper (product name: Kinto double-sided <1
10>, basis weight 12 B g/m, manufactured by Kanzaki Paper ■) so that the coating amount after drying is 10 g/rd,
It was dried using a dryer at 0° C. to form an elastic layer.

Linear pressure of 60 kg is applied to this sheet using a super calender.
The smoothing process was performed under the following conditions: /cm, paper passing speed of 50 m/sec, and 2 nips.

Next, 40 parts of methyl ethyl ketone, 40 parts of toluene,
20 parts of cyclohexanone and polyester resin (product name:
Byron 200, Toyobo side type) was dissolved in 20 parts of amino-modified silicone oil (trade name: KF-393,
(manufactured by Shin-Etsu Chemical ■) 0.3 parts, epoxy modified silicone oil (product name: X-33-343, manufactured by Shin-Etsu Chemical ■) 0.3 parts
The image-receiving layer paint was coated on the elastic layer at a dry weight of 4 g/rd, dried at 120° C. for 5 minutes, and cured by heating.

Next, smoothing treatment is performed using a super calender consisting of mirror-finished metal rolls and elastic rolls (linear pressure 200 kg).
/cm, paper passing speed 50m/sec, 2 nips), and
A thermal transfer image-receiving sheet as shown in the figure was obtained.

Example 2 Vinyl chloride vinyl acetate copolymer resin (trade name: S-1e
cA, no melting point, solid, manufactured by Miki Kagaku Kogyo 01) 60 parts, 30 parts of DOP as a plasticizer, 10 parts of polyethylene wax with a melting point of 95°C, 0 parts of organic tin laurate as a stabilizer
．． 5 parts were kneaded at 140° C. for about 20 minutes to obtain a cloudy white composition.

Using a Honto Melt Laminator, apply this onto commercially available art paper (product name: Nikinfuji Double-Sided <110>) with a smear amount of 10.
g/m to form an elastic layer.

Using this sheet, a thermal transfer image-receiving sheet as shown in FIG. 4 was obtained in the same manner as in Example 1.

Example 3 70 parts of low-density polyethylene (melting point: about 120°C), 10 parts of rutile titanium dioxide (product name: FR-22, powder, manufactured by Furukawa Mining Co., Ltd.), polyethylene glycol (reagent: oxidizing agent, melting point: 85°C) ) were kneaded at 140° C. for about 20 minutes to obtain a cloudy composition.

Using a Honmelt laminator, apply this onto commercially available art paper (product name: Kinto double-sided <110>) with an amount of 10 smears.
g/rd to form an elastic layer.

Using this sheet, a thermal transfer image-receiving sheet as shown in FIG. 4 was obtained in the same manner as in Example 1.

Comparative Example 1 80 parts of polyolefin resin fine particle dispersion (product name: Chemivar A-100) and 20 parts of styrene-butadiene copolymer latex (product name: L-1599) were mixed and water was added to obtain an elasticity with a solid content of 40%. A coating liquid for layer formation was obtained.

A thermal transfer image-receiving sheet was obtained in the same manner as in Example 1 except that this coating liquid was used.

Comparative Example 2 Vinyl chloride vinyl acetate copolymer resin (trade name: S-1e
cA), 30 parts of DOP as a plasticizer, and 0.5 part of organic tin laurate as a stabilizer were kneaded at 140°C for about 20 minutes to obtain a cloudy composition for forming an elastic layer.

A thermal transfer image-receiving sheet was obtained in the same manner as in Example 2 except that this was used.

Comparative Example 3 85 parts of low density polyethylene and 15 parts of rutile titanium dioxide (trade name: FR-22) were kneaded at 140°C for about 20 minutes to obtain a cloudy composition for forming an elastic layer.

A thermal transfer image-receiving sheet was obtained in the same manner as in Example 2 except that this was used.

Comparative Example 4 Example 1 except that the elastic layer is not formed in Example 1.
A thermal transfer image-receiving sheet was obtained in the same manner as above.

Regarding the seven types of thermal transfer image-receiving sheets thus obtained,
A quality comparison test was conducted as follows.

That is, blue heat sublimation dye (trade name: KST-B-71
4. 0.45 parts of Nippon Kayaku ■, 0.4 parts of polyvinyl butyral resin (product name: S-1ecBX-L Building Blocks Chemical Industry ■), 4.6 parts of methyl ethyl ketone, 4 parts of toluene
．． The ink was dissolved in 6 parts and applied as a colorant layer forming ink to a 6 μm thick polyethylene terephthalate film whose back side was heat-resistant treated so that the dry weight was 1.0 g/m.
It was dried to create a color material transfer sheet.

Next, the coated surfaces of the color material transfer sheet and the thermal transfer image receiving sheet are overlapped, and heat is applied from the back side of the color material transfer sheet using a thermal head to form a thermal transfer recorded image on the image receiving surface of the image receiving sheet. was formed, and the recording sensitivity, image quality, and curl during printing were evaluated as follows, and the results are listed in Table 1.

"Evaluation Method" Recording Sensitivity Recorded images were measured with a MACBETH densitometer, and recording sensitivity was evaluated from the sensitivity curve.

image quality The recorded images were observed and evaluated using a 25x magnification looper.

Using a thermal transfer image-receiving sheet cut to a size of Printing Curl 10 (1+m x 125wm), printing was repeated three times, and the degree of curling was compared and evaluated, and those with less curling were evaluated as good.

Table 1 Evaluation Criteria■...Extremely Excellent○...Good It is possible to obtain printed matter with excellent appearance without causing the sheet to curl during printing.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a thermal transfer image-receiving sheet showing an embodiment of the present invention. An elastic layer 2 having a low melting point material 4 scattered therein is formed on a base material 1, and a dye-dyeable image receiving layer 3 is formed on the elastic layer. FIG. 2 is a comparative example, and is a diagram schematically showing a longitudinal section after printing of a thermal transfer image-receiving sheet that does not contain a low-melting-point material in its elastic layer. It shows how the entire sheet curls significantly due to the distortion generated between the base material 3 and the elastic layer 2 that contracted due to the heat applied during printing. FIG. 3 is a diagram schematically showing a longitudinal section of the image-receiving sheet after printing using the thermal transfer image-receiving sheet of the present invention. , absorbs and disperses the distortion that occurs between the elastic layer 2 and the base material 3 that contract due to the heat applied during printing, resulting in a thicker sheet as a whole (preventing curling). In Figure 4, an elastic layer 2 is formed on a base material 1 in such a manner that a material 4 with a low melting point is dispersed therein, and a dye-dyeable image receiving layer 3 is formed on the elastic layer. FIG. 5 is a longitudinal cross-sectional view of the thermal transfer image-receiving sheet of the present invention, which is shown in FIG. The stress caused by the thermal contraction of the elastic layer gathers around the low melting point material 4 dispersed in the sheet, causing the elastic layer 2 to break at that part, and as a result, suppressing the large curling of the entire sheet. 1...Base material 2...Elastic layer 3...Image receiving layer 4...Low melting point region within the elastic layer

Claims (1)

[Claims] In a thermal transfer image-receiving sheet comprising an elastic layer and an image-receiving layer having dye-dyeability sequentially provided on a base material, a material having a lower melting point than the material of the elastic layer is dotted in the elastic layer. A thermal transfer image-receiving sheet with special features.