JPH0561210A - Electrostatic thermal recording medium - Google Patents

Abstract

PURPOSE:To obtain excellent repetitive recording characteristics by using a recording layer composed, of a surface layer containing a polymer compd. having >=200 deg.C glass transition temp. and a lower layer containing a polymer compd. having >=150 deg.C glass transition temp. CONSTITUTION:On a conductive layer 3, laminating of a lower layer 1 as an electrostatic thermal recording layer and a surface layer 8 to form a recording layer 2 is formed. This recording layer 2 consists of the lower layer 1 containing a polymer compd. having >=150 deg.C glass transition temp. and the surface layer 8 containing a polymer compd. having >=200 deg.C glass transition temp. The polymer compd. in the lower layer 1 is selected from polyethylene, polypropylene, etc. The polymer compd. in the surface layer 8 consists of a copolymer containing a heat-resistant component having >=200 deg.C glass transition temp. and a silicone-base lubricant component.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention uses a dielectric as a latent image body,
The present invention relates to a transfer type electrostatic thermal recording method (electrothermography) for forming a latent image by heating and a recording medium used therefor. In addition, a printer using this recording method,
It concerns fax machines and digital copiers.

[0002]

2. Description of the Related Art A method of visualizing an electrically conductive substrate by providing a resin layer whose electric resistance decreases with temperature by heating, electrostatically charging the layer, and applying heat by infrared irradiation is known. Kosho 35-14722, Japanese Shoko 37-15878, Japanese Shoko 38-
Known for 14347. It has been recorded that these use a substance having a characteristic that the electric resistance of the resin layer (macromolecular compound) decreases or increases with temperature. Japanese Patent Application Laid-Open Nos. 51-68233 and 52-19534 disclose a technique of using a thermal signal instead of a thermal head. However, it lacks the disclosure of concrete technical means and is at a level that requires more related technical development in order to be put into practical use.
In fact, an image forming apparatus that forms an electrostatic latent image by heating has not been commercialized yet.

On the other hand, there are many products of the image forming apparatus adopting the electrophotographic method.

However, the electrophotographic system has a problem with the photoconductor. One is that the cost is increased due to the manufacturing of the photoconductor, and the cost of the device is increased because the light-shielding property of the photoconductor is required. In addition, there is a problem in that the space occupied by the optical unit is large, the irradiation direction is regulated, and the degree of freedom in the mechanical configuration is impaired.

Further, Japanese Patent Application No. 2-21 relating to the application of the present applicant
In 3756, a thermal head is used for heating, and a description is given of applying a bias voltage to the thermal head that has been precharged, or the thermal head, and the recording layer has lubricity, and polypropylene, a polypropylene-based copolymer. , A fluorinated acrylic-acrylic copolymer, a perfluoroalkyl acrylate, a silicone-based polymer, or a mixture thereof is described.

Further, in Japanese Patent Application No. 2-288060, the glass transition temperature of the material is higher than the environmental temperature of use, and the heat deformation temperature thereof is higher than the glass transition temperature, due to the characteristics of the dielectric material which is the resin layer. And that the heat distortion temperature is higher than the heat writing temperature. In this case, unless Tdf is sufficiently higher than Tg, the recording layer cannot withstand repeated use. Specifically, the difference between Tdf and Tg is 50 ° C or more,
It is preferably 100 ° C or higher. However, many polymers have a Tg plus 50 to 60 ° C as a softening point, that is, a thermal softening temperature Td. By the way, Japanese Patent Application No. 2-2880 mentioned above.
In the example of No. 60, as shown in Table 1 below, polypropylene (PP) is not suitable for repetition, and polyethylene terephthalate (PET) and polybutylene terephthalate (PBT) can be used for a while even though they can withstand use. There is a problem that it does not have characteristics. Furthermore, polyethylene (PE), polyvinyl chloride (PVC), polyethylene naphthalate (PEN), polycarbonate (PC), etc. described in Japanese Patent Application No. 2-213756 also have a low Tg, and therefore Tdf. However, there was a problem in repeated recording characteristics.

[0007]

[Table 1]

[0008]

DISCLOSURE OF THE INVENTION The present invention provides a polymer compound (Tg having a sufficiently high Tg and therefore a sufficiently high Tdf).
> 200 ° C.) and a lower layer containing a polymer compound having a Tg of 150 ° C. or less, which is a temperature sufficiently lower than Tdf, for a recording layer having excellent repetitive recording characteristics. It is intended to provide an electrostatic thermal recording material.

[0009]

The constitution of the present invention for solving the above-mentioned problems is a thermal transfer recording material as described in the claims.

First, the structure of the thermal transfer recording material of the present invention and the thermal transfer recording method using the same will be specifically described with reference to the drawings.

FIG. 1 is a schematic cross-sectional view showing the constitution of the electrostatic thermal recording material of the present invention. The recording layer 2 is composed of a lower layer 1 of the electrostatic thermal recording layer and a surface layer 8 on a conductive layer 3. Are laminated. The outline of the electrostatic heat recording method using this electrostatic heat recording material is as shown in FIGS. 2 to 6. Charging step (FIG. 2) The method by corona discharge provides the most uniform charging, but a voltage is applied to the metal roller. Various methods and various methods such as triboelectrification with a brush having an organic or inorganic material surface or a roller having a sponge material may be used.

Heating Step by Thermal Signal (FIG. 3) In the conventional thermal electrostatic recording, the original and the recording medium were superposed, and the absorption-heat generation of the black portion due to infrared irradiation was utilized (analog signal), but in this recording Heating is performed by a digital signal from the thermal head. As the thermal head, a serial head or a line head with a high resolution of 8dot / mm to 16dot / mm is used.

Developing Step (FIG. 4) The development step is the same as the powder toner development and liquid toner development that are performed in ordinary electrophotography, but the reversal development is performed. [Development by repulsive electric field of toner having the same sign as the electric charge (negative electric charge in the figure) that remains without inputting a heat signal] Transfer step (FIG. 5) This step is performed in the same manner as electrophotography. In the case of powder toner, it is heated and fixed by a heat roller after transfer. In the case of liquid toner, it is only necessary to dry the remaining liquid.

Cleaning Step (FIG. 6) After transfer, to ensure a good surface for the next image,
The powder or liquid toner left on the electrostatic recording layer must be removed before reuse. By repeating such steps, digital information can be recorded on plain paper.

The composition and constitution of the recording layer of the recording material of the present invention is a polymer substance having a glass transition temperature of 200 ° C. or higher, for example, polyimide (PI) (Tg = 310 ° C.), polyamideimide (PAI) (Tg = Tg = 280 ℃), aromatic polyamide (APA) (Tg = 280 ℃), polyparabanic acid (PP
A) (Tg = 290 ° C), polyether sulfone (PE
S) (Tg = 230 ° C.) or the like can be used. Under the surface layer containing these polymer compounds with excellent heat resistance, Tg is 150
Layers composed of a polymer compound having a temperature of not higher than 0 ° C. are laminated. This Tg
Examples of the polymer compound having a temperature of 150 ° C. or less include PP, PET, PBT, PE, PVC, PEN and P listed in Table 1.
C or the like can be used. Further, in order to impart lubricity to the heat resistant surface layer, copolymerization of a silicone-based polymer can be used to obtain even better repeatability.

[0016]

EXAMPLES The present invention will be specifically described below with reference to examples. Table 2 below shows the materials and thicknesses of the surface layer and the lower layer of the recording layer of the electrostatic thermal recording material of the example of the present invention and the use results of this electrostatic thermal recording material.

[0017]

[Table 2]

The repeatable number of times in Table 2 is the number of times of recording until a defect occurs in an image when the repeated recording is performed, and the recording density is deteriorated to a recording density of 1.0 or less, or Indicates the number of recordings until the soiling of the background occurs due to insufficient lubricity. The mode of failure is shown in parentheses. The recording conditions are as follows. An electrostatic thermal recording layer made of the above recording material is charged at minus 500 V, thermal writing is performed with an 8 dot / mm thermal head, developed with a negative polarity developer, and then transferred to PPC paper. I got an image.

[0019]

As described above, the electrostatic thermal recording layer has a laminated structure composed of two layers. (1) Potential attenuation at low energy (low temperature) is possible, that is, with high sensitivity. That is, (2) it is possible to prevent thermal deformation at the time of writing by the thermal head and to prevent disturbance of the electrostatic latent image due to lack of lubricity, that is, to prevent background stains and ID deterioration that occur during repeated use.

That is, it is possible to solve the problem of the thermal characteristics of a polymer compound as a recording medium and to provide a highly reliable electrostatic heat recording material.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing the constitution of an electrostatic thermal recording material of the present invention,

[Fig. 2]

[Figure 3]

[Figure 4]

[Figure 5]

FIG. 6 is an explanatory view of steps of the electrostatic thermal recording method using the electrostatic thermal recording material of the present invention.

[Explanation of symbols]

 1 ... Lower layer, 2 ... Electrostatic thermal recording layer, 3 ... Conductive layer, 4 ... Negative corona charging device, 5 ... Thermal head, 6 ... Toner, 7 ... Paper, 8 ... Surface layer, 12 ... Positive corona charging device, 14 ... Cleaner

Claims (3)

[Claims] 1. An electrostatic thermal recording material having a recording layer on a conductive layer, wherein the recording layer has a lower layer containing a polymer compound having a glass transition temperature of 150 ° C. or lower and a glass transition temperature of 200 ° C.
An electrostatic thermal recording material comprising a surface layer containing the above polymer compound. 2. The polymer compound contained in the lower layer is any one of polyethylene, polypropylene, vinyl chloride, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate and polycarbonate. The electrostatic thermal recording material according to claim 1, wherein 3. The polymer compound contained in the surface layer is a copolymer containing a heat-resistant component having a glass transition temperature of 200 ° C. or higher and a silicone-based lubricating component. Alternatively, the electrostatic thermal recording material according to claim 2.