JPS5878796A - Thermal recording material - Google Patents

Abstract

PURPOSE:To obtain a thermal recording material capable of giving recordings having greatly improved color density by laminating a saturated polyester film subjected to a heat treatment at 120 deg.C or higher as a thermal recording layer receiving colorant transferred from a colorant layer provided on a base material on the base material. CONSTITUTION:As a thermal recording lever receiving selectively colorants transferred when being contacted with a colorant layer in solid or semi-solid at ordinary temprature, provided on a base material, and the heated, a saturated polyester film subjected to a heat treatment in an atmosphere of 120 deg.C or higher is dry-laminated on a supporter, or a dry-laminate consisting of the saturated polyester film and the supporter is heat-treated at 120 deg.C or higher. Also, after the saturated polyester film is laminated with the supporter, and then subjected to a heat treatment in an atmoshere of 120 deg.C. The polyester film is laminated on the supporter by hot press of 120 deg.C or higher.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermal recording medium, and more specifically, a base material coated with a coloring material is used, the coloring material layer and the recording medium are brought into contact, and the coloring is achieved by heating with a thermal head or the like. The present invention relates to a recording medium in a thermal recording method in which a material is transferred to the recording medium.

In general, the most popular thermal recording method is to bring a thermal head into contact with a thermal recording paper provided with a recording layer that develops color by causing a physical or chemical change when heated, thereby obtaining the desired color recording. However, this recording method has the disadvantage that the heat-sensitive recording paper used is flat due to color staining due to unavoidable pressure and heat during storage and handling, and is expensive to manufacture.

Therefore, as an alternative to the above-mentioned thermal recording method 2, for example, as described in JP-A No. 61-11S446, K. The coloring material is applied onto the recording material, the coloring material on the recording material is brought into contact with the recording paper, and the coloring material on the recording material is heated by a thermal head and selectively transferred to the recording paper to record. A method has been proposed to do this. In this recording method, the coloring material applied to the base material is transferred to the recording sheet when the coloring material or the binder containing the coloring material melts, evaporates, or sublimates due to heat, and as a result, adhesion to the writing sheet, This is because staining etc. may occur. The coloring materials used here are generally dyes and pigments dispersed in a binder such as wax.
For example, when the transition is carried out by sublimation, a sublimable dye having a sublimation temperature of 60 to 300 DEG C., that is, a disperse dye such as a nido ρ type, an azo type, a quinoline type, or an anthraquinone type, is used as the dye. In addition, in the case of a transfer method such as melting, under normal conditions, colorant transfer does not occur even if the colorant comes into contact with the recording sheet, but transfer of the colorant does not occur until heating at 60 to 300°C, for example. It is something that Therefore, this recording method is characterized by the use of plain paper as the recording sheet.

However, when plain paper is used, the color density of the recording is low, especially when it is dyed, so there is a demand for the development of a thermal recording sheet that is compatible with this recording method.The inventors of the present invention have conducted extensive research. As a result, the inventors discovered that by using a saturated polyester film heat-treated at 120'C or more as a recording layer, the color depth of the recorded material was significantly improved, and the present invention was completed.

The saturated polyester film used in the present invention is made by melt-extruding or casting a saturated polyester resin. Polybutylene terephthalate (PET, melting point 260°C) is known, as well as polybutylene terephthalate (PBT, melting point 224°C), poly1.
4-cyclohexane dimethylene terephthalate) (PC
HT, melting point 290'C), etc. These phthalic acid polyesters usually do not dissolve in most solvents, but recently granular ones that are soluble in ordinary solvents and those in the form of water dispersion have also been developed as saturated polyester binders.

The thermal recording material of the present invention is prepared by laminating this saturated polyester film on a support. The method is as follows:
1! As will be explained, there are three possible methods: dry lamyed, melt extrusion lamyed, and hot press, but no matter which type of pressure is used, it is necessary to heat-treat the saturated polyester at a temperature of 120'C or higher.

^ Dry lamination method: A saturated polyester film is first heat-treated in an atmosphere of 120°C or higher and then dry laminated onto a support, or a saturated polyester film and a support are dry-laminated and then heated at 120°C.
Heat treatment is performed above.

(2) Melt extrusion lamination method: After laminating the saturated polyester film and the support, heat treatment is performed in an atmosphere of 120°C or higher.

0 Heat press method: Polyester film is laminated on the support at a heat press temperature of 120°C or higher. Saturated polyester film has poor heat resistance if left untreated, and part of the film softens and melts during heat transfer. However, it cannot be applied to thermal recording materials because adhesion occurs between the film and the substrate coated with the coloring material, making it difficult to peel it off. However, once the film is heat-treated at 120°C or higher, the problem of adhesion can be solved. , a recording medium with good color density can be obtained. This is because crystallization of the saturated polyester film progresses when heat treated at 120° C. or higher, resulting in significantly improved heat resistance. In other words, it is said that the saturated polyester film of the PET group undergoes a transition at a temperature higher than the glass transition point, and at this temperature the internal structure of the film is fixed in a specific crystallized state. It is said to have a specific transition temperature (hereinafter referred to as K "crystallization temperature" to distinguish the transition temperature from the glass transition temperature). For example, PET film is 140 to 15
Although the crystallization temperature is 0° C., it is thought that this crystallization temperature varies depending on the environment or atmosphere, for example, depending on the heating time. Regardless of the pressure, when a saturated polyester film is heated to hK above its crystallization temperature, it shows an improvement in strength properties and heat resistance.

Supports for the thermal recording medium according to the present invention include plain paper such as agrain paper, paperboard, and the surface of these papers containing kaolin, heavy or light calcium carbonate, titanium oxide, atl hydrium, and aluminum hydroxide. , Kitan White, or the like can be used, coated with a paint containing pigment as the main pigment and smoothed with a super calender or the like if necessary. In addition, any support such as woven fabric, non-woven fabric, wood, ceramics, glass, entertainment, synthetic resin, etc. can be used depending on the purpose.

Hereinafter, the present invention will be explained in detail according to examples [Example 1] Commercially available white paperboard (thickness approximately 430 μm, for carton use) consisting of approximately 80 NBKP and approximately 20 LBKP was coated with laminated paperboard. Use a die temperature of 300℃ and a barrel temperature of 245~
PET (polyethylene terephthalate) was extrusion laminated at 280° C. to obtain a recording sheet Nl11 on which PET films having a thickness of about 40 μm were laminated. This IIILI recording sheet was held in an air bath at 100° C. for 5 minutes to obtain a recording sheet Ugly 2. Furthermore, the first recording sheet was heated to 120℃.
The thermal recording sheet-3 according to the present invention was obtained by holding the sheet in an air bath for 5 minutes.

[Example 2] A PET film (unstretched) with a thickness of about 25μ was used as a white paperboard 1c as a sheet of paper 1.
A thermal recording sheet of 凰4 was obtained by hot pressing for 3 minutes at a pressure of Ok/d.

[Example 3] A distribution sheet was obtained. Furthermore, it was heat-treated at 120° C. in the same manner as sheet No. 5, Naugi 3, to obtain a thermal recording sheet of fly 6 according to the present invention.

[Reference example]

Prepared by mixing 30 parts by weight (solid content) of the ao% aqueous dispersion of saturated polyester used in Example 3, and 70 parts by weight (solid content) of heavy calcium carbonate (Maruo Calcium Co., Ltd., Super 1soo) Noslurry. The resulting paint was applied to the same white paperboard as sheet 111 at a coating weight of approximately 1 iSF/- to obtain a record of 7 flies. Furthermore, the same white paperboard itself was used as the recording sheet for floor 8, and it was heat treated at 120°C in the same manner as N13, a commercially available milk carton paper on which about 25 μm of polyethylene film was extruded and laminated.
I made it a note of floor 9.

The recording characteristics of the recording sort obtained in the above Examples and Reference Examples were investigated using the following method.

First, as a sublimable disperse dye, Disperse Fluor 24
(Product name Dursnol Blue 2G), Dispersui x cy-42 (Product name Re5olln Y
yellow GRL) and Dispersed Red-1
(Product name: C@1llton 5carlet B), 10 parts by weight of dye for each, Polyvinino L
Blue, yellow, and red sublimation thermal transfer inks were prepared by kneading 3 parts by weight of butyral and 45 parts by weight of isopropyl alcohol using a three-roll mill, and further adding these inks to 30 f/I11' A base paper for transfer was made by gravure peta printing on thin paper. Next, the color material layer of this base paper for transfer was brought into contact with the hard surface of the harden sheet obtained in Examples and Comparative Examples, and 300C was set from the back side of the base paper for transfer.
Press a thermal plate measuring ax x 3 cm for 5 seconds to thermally transfer the image to the recording sheet. The reflection densities of the yellow, yellow, and red recordings thermally transferred onto the recording sheet in this manner were measured using a Macbeth densitometer, and the results are shown in the table. As can be seen from the table, the reflection density is 12 for each filter: Visual (Ratten@106) for blue, Blue (Rano Ching #47) for yellow, and Hagelean (Ratten #58) for red.
Thermal recording sheet according to the present invention, in which a saturated polyester film heat-treated at or below 0' is laminated on a support) 1 & 13,
M4 and floor 6 have much higher reflection densities than the white paperboard itself (Zui 8), as well as the recording sheet of XX 7, which has a coating layer made of saturated polyester and carbonate. . In addition, 8111.1 is a saturated polyester film laminated onto white paperboard without heat treatment.
The No. 95 recording sheet, the recording sheet level 2 heat-treated at 100°C, and the I@9 recording sheet, which was laminated with a polyethylene film instead of a saturated polyester film and heat-treated at 120°C, were all laminated by thermal transfer, etc. 1) One part of the film σ) softened and stuck to the base material, making it impossible to peel it off.

Patent applicant: Jujo Paper Co., Ltd.

Claims (1)

[Claims] 11) A thermal recording material that is heated while in contact with a color material layer that is solid or semi-solid at room temperature and provided on a base material.