JPS61106296A - Thermal transfer sheet - Google Patents

Abstract

PURPOSE:To obtain color images with durability and continuous gradations, by combining a thermal transfer sheet and a thermal transfer recording sheet. CONSTITUTION:The thermal transfer sheet 1 comprises a thermally conductive layer 3 provided on one side of a base sheet 2. The base sheet may be a polyester film, a polyethylene film or the like, and has a thickness of 0.5-5.0mum. The layer 3 is composed of a dye capable of being transferred to the thermal transfer recording sheet and a reaction product of an isocyanate with a compound having an active hydrogen atom. The reaction products is used as a binder resin in the layer 3. At least one diisocyanate is used singly or in combination as the isocyanate. The compound having an active hydrogen atom is preferably a high molecular weight one such as polyvinyl butyral and polyvinyl formal which has a large number of -OH groups or -COOH groups as reaction sites for the isocyanate.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to thermal transfer sheets. More specifically, the thermal transfer sheet (= related.

[Technical Background of the Invention and Problems Therewith] Conventionally, thermosensitive coloring paper has been mainly used to obtain images according to image information I using a thermal head. However, thermal coloring paper has a fatal drawback in that if the resulting image is stored for a long period of time, the color may fade or non-image areas may develop color. In addition, color printing is limited to a single color, and it has been impossible to obtain a color image with continuous gradations.

In order to solve the above problems, a thermal transfer sheet was developed in which a thermal transfer layer containing a heat-transferable dye was provided on a base sheet. Upper (= Used by being superimposed on a provided thermal transfer sheet. By using such a thermal transfer sheet and a thermal transfer sheet in combination, a color image that is durable and has continuous gradation can be obtained. becomes possible.

The thermal transfer sheet and the thermal transfer sheet are overlapped and heated to perform recording, but generally (=, the running speed of the thermal transfer plate and the running speed of the thermal transfer sheet are controlled to the same speed, and the thermal transfer sheet is completely overlapped. Heating records have been carried out.

However, when thermal recording is performed by making the running speed of the thermal transfer sheet and the running speed of the thermal transfer plate perfectly match, the following problems occur.

(a) Even when recording is performed on only one part of the thermal transfer sheet, a thermal transfer sheet with the same area as the thermal transfer sheet is required; This can result in a thermal transfer sheet that is extremely wasteful.

(b) After heating recording is completed, a clear trace of dye transfer remains on the thermal transfer sheet, so the recorded contents can be easily read by looking at the thermal transfer sheet after use, making it highly confidential. When a thermal transfer sheet is used for recording (-), there is a problem that the thermal transfer sheet after use cannot be disposed of without special treatment.

In order to solve these problems, studies have begun to consider making the traveling speed of the thermal transfer sheet smaller than the traveling speed of the thermal transfer sheet when the thermal transfer sheet and the thermal transfer sheet are overlapped and thermally recorded. However, when an existing thermal transfer sheet and a thermal transfer sheet are stacked so that the transfer layer of the thermal transfer sheet and the receiving layer of the thermal transfer sheet overlap and the running speeds of the two sheets are different, friction occurs between the two sheets and heat is generated. The inventors of the present invention have found that there is a fatal problem in that the thermal transfer layer of the thermal transfer sheet partially adheres to and transfers to the receiving layer of the thermal transfer sheet.

[Object of the invention and its outline]

The present invention is an attempt to solve such problems, and is aimed at a method that allows the running speed to be lower than the running speed of the thermal transfer sheet when the thermal transfer sheet and the sheet to be thermally transferred are overlapped and thermally recorded. The purpose is to provide thermal transfer sheets.

The thermal transfer sheet according to the present invention is a thermal transfer sheet in which a thermal transfer sheet (=thermal transfer layer containing a dye that migrates) is provided on a base sheet by heating, and the thermal transfer layer is made of isocyanates and active hydrogen. It is characterized by containing a reaction product with a compound having

When such a thermal transfer sheet is used in combination with a thermal transfer sheet and the running speed of the thermal transfer sheet is lower than that of the thermal transfer sheet, the following objects are achieved.

(a+ Thermal recording is achieved with a thermal transfer sheet having a smaller area than the thermal transfer sheet, making effective use of the thermal transfer sheet and reducing wastage of the thermal transfer sheet.

(b) Looking at the thermal transfer sheet after it has been used for heating recording,
It is not immediately clear what kind of records were made.

[Detailed description of the invention]

The present invention will be specifically explained below based on the drawings.

As shown in the figure, the thermal transfer sheet/ according to the present invention has a thermal transfer layer J provided on one surface of the base material GITCO.

As the base sheet, films such as polyester film, polystyrene film, polysulfone film, polyvinyl alcohol film, and cellophane are used, and polyester film is particularly preferred from the viewpoint of heat resistance. Its thickness is 0.5 to 50 μm, preferably 3 to 70 μm
It is desirable that it is m.

The thermal transfer layer 3 is composed of a dye that transfers to the thermal transfer sheet by heating, and a reaction product of isocyanates and a compound having active hydrogen.

The dye that transfers to the thermal transfer sheet by heating is preferably a thermally sublimable disperse dye, and approximately /! ;0-(40
It is desirable to have a molecular weight of about 0. This dye is
It is selected in consideration of thermal sublimation temperature, hue, weather resistance, stability in binder resin, etc., and specific examples (= are as follows) are selected.

Miketon Polyster Yellow
-Y L (Mitsui Toatsu, C, I, Dispers
Yellow-'I 2 ), Kayaset
Yellow-G (Nippon Kayaku, (, I.

Di@pers Yellow 77), PTY-
, t2 (manufactured by Mitsubishi Kasei, C, I, 5olvent Ye
low /ll-/ ), Miketon Po1
yecter Red B SF (manufactured by Mitsui Toatsu, C, 1, Disperse Red / / /
), Kayaset RedB (Nippon Kayaku,
C11, Disperse Red B), PTR
-tu (manufactured by Mitsubishi Kasei, C, 1, Disperse Red
! ; 0), Miketon Polyst
er Blue-FBL (manufactured by Mitsui Toatsu, C, 1, Di
Spers Blue J & ), PTB-67
(Mitsubishi Kasei, C0I, DisperrieBlue
Kota/), Kayaset Blue-90&
(Nippon Kayaku, C01,5ololvsn -/ko)
A reaction product of isocyanates and a compound having active hydrogen is used as a binder resin in the thermal transfer layer 3.

Diisocyanates are used as the inreanates, and these are used alone or in combination. Specifically, the following compounds are used.

Rose phenylene diisocyanate, /-chloro-,! ,
44-phenylene diisocyanate, Cochrolow/,
Terphenylene quinine anate, co, 4-) Toluene diison anate, 2, A-Toluene diison anate,
Hexamethylene diisocyanate, rt,! -biphenylene diisocyanate, triphenylmethane triisocyanate, u, </, e"-trimethyl-3,
! ,! - Triisocyanate, 4I, O - Triphenylnoanurate.

Examples of compounds having active hydrogen that react with isocyanates to form a binder resin include polyvinyl butyral and polyvinyl formal.

Among the above-mentioned compounds, those having a high molecular weight such as polyester polyol, polyether polyol, acrylic polyol, polyurethane polyol, etc. and containing a large amount of 1-OH group or -COOH group, which are reaction sites with isocyanates, are particularly preferred. The molecular weight is bo,
o o o~200.000. Glass transition temperature is 60
~/10°C, inreanates and the above-mentioned compound having active hydrogen react with each other by heating to form a resin having excellent heat resistance and mechanical strength.

The reaction products of isonanoates and compounds with active hydrogen have excellent heat resistance and mechanical strength, so
When this reaction product is used as a binder for the thermal transfer layer (- means that even if friction occurs between the thermal transfer sheet and the thermal transfer sheet and heat is generated, the thermal transfer layer of the thermal transfer sheet will not adhere to the receiving layer of the thermal transfer sheet. It will no longer metastasize.

As mentioned above, the thermal transfer layer 3 consists of a dye that transfers to the thermal transfer sheet by heating and a reaction product of isocyanates and a compound having active hydrogen, and each component is contained in the following amounts. Exists in a relationship.

Isocyanates are used in an amount of 7 to 100 parts by weight based on 100 parts by weight of the compound having active hydrogen.

The dye is used in an amount of IO-200 parts by weight per 100 parts by weight of the compound having active hydrogen. The amount of this dye varies within the above range depending on the ratio of the running speed of the thermal transfer sheet to the running speed of the thermal transfer sheet. In other words, the smaller the ratio between the running speed of the thermal transfer sheet and the running speed of the thermal transfer sheet, that is, the slower the running speed of the thermal transfer sheet and the running speed of the thermal transfer sheet, the greater the amount of dye present. It is preferable to do so.

The thermal transfer sheet/ in which the thermal transfer layer N3 as described above is provided on the base sheet λ may have a heat-resistant protective layer on the side of the base sheet on which the thermal transfer layer 3 is not provided. It is preferable that

The thermal transfer sheet / having the above-mentioned configuration is used by being superimposed on the thermal transfer sheet, and the ratio between the running speed of the thermal transfer sheet and the running speed of the thermal transfer sheet is / -0,
The range is preferably 0.02. If the speed ratio mentioned above is 0,
If it is less than 0.02, it is not preferable because the print density of the recording formed on the thermal transfer sheet may be too low. As the thermal transfer sheet, a wide variety of conventionally known sheets can be used.

Resins used for the thermal transfer layer include ester bonds,
Urethane bond, amide bond, urea bond, C-CN bond,
A synthetic resin having a polar group such as a C-Cl bond is used. More specifically, ester resins such as polyester resins, polyacrylic acid ester resins, polycarbonate resins, polyvinyl acetate resins, and styrene acrylate resins, polyurethane resins, polyamide resins, urea resins, and polyester resins with highly polar bonds. Vinyl chloride resin, polyacrylonitrile resin, etc. are used.

〔Effect of the invention〕

The thermal transfer sheet according to the present invention has the following effects because the thermal transfer layer is composed of a heat-transferable dye and a reaction product of an inocyanate and a compound having active hydrogen.

(1) When thermal recording is performed by overlapping a thermal transfer sheet and a thermal transfer sheet, the running speed of the thermal transfer sheet can be made lower than that of the thermal transfer sheet.

(1il) Therefore, recording can be achieved on a thermal transfer sheet with a smaller area than the sheet to be thermally transferred, and the thermal transfer sheet can be used more effectively and waste of the thermal transfer sheet can be reduced.

Even when looking at the thermal transfer sheet after it has been used for f:i+l thermal recording, it is not immediately clear what type of recording was performed.

EXAMPLES The present invention will be explained below with reference to Examples, but the present invention is not limited to these Examples.

Example 1.

An ink composition for forming a thermal transfer layer having the following composition was prepared, and this composition was applied to a polyethylene phthalate film (9μ
m thickness, Toyobo 5-PET) coated and dried, then daQ
The reaction was cured at ℃ for q days.

Next, an ink composition for forming a receptor layer having the following composition was prepared, and this composition was applied to synthetic paper Y made by Tamago Yuka Co., Ltd. using Myapa #J6.
UPO-FPG#/jO top: 2. Coating and drying to obtain a heat transfer sheet.

(Dry application amount: approx. 0, og/ze).

The thermal transfer layer of the thermal transfer sheet and the receiving layer of the thermal transfer sheet are placed one on top of the other so that they face each other, and the thermal transfer sheet is
The thermal transfer sheet was run at a speed of Oxrx/s@c, while the thermal transfer sheet was moved at the same speed, // 2 times, l/lA times, 7
Recording was performed by running each at a speed of 710 times, and applying energy of 7 r m3/d from the back side using a g/Ryu thermal head. Even when observing the receiving layer of the thermally transferred sheet after the transfer, no transfer of binder or the like occurred (measuring device: Macbeth RD-wit).

Furthermore, the friction between the transfer layer and the receiving layer was small, and good running properties were exhibited.

Example 1 The ink composition for forming a thermal transfer layer having the above composition was applied onto a 9 μm thick condenser paper using Myapa #10, dried, and then aged for q days at <i oo to create a thermal transfer sheet. .

Next, when printing was carried out under the same conditions as in Example-/, good running properties were exhibited.

Example 3 A thermal transfer sheet was prepared in the same manner as in Example, except that an ink composition for forming a thermal transfer layer having the following composition was used.
Heat printing was performed in combination with a thermal transfer sheet.

When the speed ratio of the thermal transfer sheet and the sheet to be thermally transferred was set to /, l/co, i/s, //10, no adhesion of the thermal transfer layer of the transfer sheet was observed even on the receiving layer after transfer. The sheet showed good running properties.

[Brief explanation of drawings]

The figure is a sectional view of a thermal transfer sheet according to the present invention.

Claims (4)

[Claims] (1) A thermal transfer sheet in which a thermal transfer layer containing a dye that transfers to the thermal transfer sheet by heating is provided on a base sheet, the thermal transfer layer being formed by a reaction between isocyanates and a compound having active hydrogen. A thermal transfer sheet characterized by containing a substance. (2) The compound having active hydrogen is polyvinyl butyral, polyvinyl formal, polyester polyol,
The thermal transfer sheet according to claim 1, which is selected from the group consisting of acrylic polyols. (3) The thermal transfer sheet according to claim 1, wherein the isocyanate is a diisocyanate or a triisocyanate. (4) Compound 1 in which the dye has active hydrogen in the thermal transfer layer
The thermal transfer sheet according to claim 1, wherein the thermal transfer sheet is used in an amount of 10 to 200 parts by weight based on 00 parts by weight.