JPH03183568A - Thermal head - Google Patents

Abstract

PURPOSE:To lower thermal conductivity of a thermal insulation layer, to enhance mechanical strength and to realize an excellent print quality by composing the thermal insulation layer of a polymer in which an oligomer containing at least one of isoimido oligomer boded with an acetylene end group or imido oligomer bonded with acetylene end group is cured. CONSTITUTION:A thermal insulation layer 2 on an insulating alumina substrate 1 is composed of a polymer in which a polymerizable oligomer containing at least one of isoimido oligomer bonded with an acetylene end group or an imido oligomer bonded with an acetylene end group is cured. The polymer has low thermal conductivity and requires no pore. Consequently, mechanical strength of the thermal insulation layer is enhanced and dispersion of thermal response due to dispersion of the diameter of the pore can be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thermal head incorporated in a thermal printing device or the like.

[Conventional technology]

Conventionally, thermal heads have been desired to have lower power consumption and faster printing speed. Since such characteristics are greatly influenced by the thermal characteristics of the substrate constituting the thermal head, various improvements in this regard have been proposed.

FIG. 2 is a schematic sectional view showing a conventional thermal head. As shown in the figure, in the conventional thermal head, a heat insulating layer 12 is provided on an insulating substrate 11, and a heating resistor layer 13, power feeders 14a and 14b, and a protection 15 are provided in this order on top of the heat insulating layer 12. ing. A portion A between the conductors 14a and 14b of the heat generating resistor 13 becomes a heat generating portion.

By the way, in general, the heat insulating layer 12 has a thermal conductivity of 33xlO to 9x10-3cal/cn-s-'C.
This prevents the heat generated by the heating resistor 13 from escaping to the substrate 11 more than necessary.

Conventionally, the thermal conductivity of the heat-insulating M12 is made smaller than that of the protective layer 15 (SiO, Ta20s, etc.) located on the opposite side of the heating resistor 13, and the substrate 11
In order to prevent more heat from being dissipated than necessary, the heat insulating layer 12 is formed to be thick.

However, if the heat insulating layer 12 is formed to be thick, heat dissipation from the heat generating portion A will not occur quickly after the heat generating resistor 13 is turned off. Therefore, if the printing repetition cycle is fast, the next printing will start before the temperature of the heat generating part A has sufficiently decreased, causing the temperature of the heat generating part A to rise too much, resulting in a problem that the print quality will deteriorate. .

Therefore, in order to reduce the thermal conductivity of the heat insulating layer of the thermal head, it has been proposed to use glass having a large number of holes in the heat insulating layer (for example, as disclosed in Japanese Patent Application Laid-Open No. 611554). This heat-retaining layer has low thermal conductivity and excellent heat retention.
In addition, by forming it thinly, it is possible to provide good thermal response characteristics.

[Problem to be solved by the invention]

However, in order to make the porous glass layer as shown in the conventional example above, the temperature set during firing must be maintained within a range of ±2 to 3 °C of the set temperature, for example, This kind of temperature control is technologically advanced and requires 1
One problem was that it was difficult.

Also, due to the firing temperature not being set appropriately,
Since the diameter of the bubbles generated from inside the glass powder varies widely, there is a problem in that the thermal response of the thermal head varies depending on the IJ crystal production.

Furthermore, when the diameter of the bubbles is too large, there is a problem that the mechanical strength of the heat insulating layer becomes weak.

Furthermore, when the diameter of the bubbles is too large, the bubbles are exposed to the surface of the porous glass and the surface becomes uneven, which causes heating resistors and conductors formed on the heat insulating layer, etc. It becomes difficult to form a finely modified evaturn (for example, using photolithography technology), and there are also problems such as an adverse effect on print quality.

Therefore, the present invention has been made to solve the problems of the prior art as described above, and its purpose is to:
It is an object of the present invention to provide a thermal head in which the thermal conductivity of the heat insulating layer is low, the mechanical strength is strong, and good printing quality can be obtained.

[Means to solve the problem]

The thermal head according to the present invention includes an insulating substrate, a heat insulating layer provided on the insulating curtain plate, and a heating resistor layer provided on the heat insulating layer. It is characterized by being formed from a polymer obtained by curing an oligomer containing at least one of an isoimide oligomer to which a group is bonded, and an imide oligomer to which an acetylene end group is bonded.

C action] In the present invention, the heat insulating layer is made of a material with an acetylene terminal group, which is a material that has excellent properties of aging resistance and has the property of being able to sufficiently lower thermal conductivity even without pores. It is formed from a polymer obtained by softening an oligomer containing at least one of a bound isoimide oligomer and an imide oligomer bound to an acetylene terminal group. This polymer has low thermal conductivity and does not require the formation of pores, making it possible to increase the mechanical strength of the heat insulating layer and eliminating variations in thermal response due to variations in pore diameter. be able to. Furthermore, since the oligomer has the property of being easily dissolved in a solvent, it is possible to improve wettability and flatness.

〔Example〕

The present invention will be explained below based on illustrated embodiments.

Figure 1 is a schematic sectional view showing an embodiment of a thermal head according to the present invention. The structure of this embodiment will be explained based on the figure. In this embodiment, a heat insulation layer 2 is provided on an insulating alumina substrate 1.
A heating resistor layer 3 made of Ta2N or the like is provided thereon by sputtering. Then, a NiCr-
Power feeders 4a and 4b made of Au or the like are provided, and a protective layer 5 made of 5i02&4 formed by the Svavta method or the like is further provided thereon. Here, heating resistor 3
A portion A between the power supply bodies 4a and 4b becomes a heat generating part.

FIGS. 3(a) and 3(b) are diagrams showing the chemical formula of the oligomer constituting the heat retaining layer 2 of this example, and FIG. b) shows an imide oligomer with attached acetylene end groups. The heat insulating layer 2 of this example is a polymer made by curing a polymerizable oligomer consisting of at least one of an isoimide oligomer with an acetylene end group bonded thereto and an imide oligomer with an acetylene end group bonded as shown in FIG. The thermal head having the above-mentioned heat insulating layer 2 formed by combining can be manufactured by W, for example, by the following method.

First of all, one side? On a 50 x 50 x 1 mrn alumina substrate (manufactured by Kojundo Kagaku Kenkyushin) subjected to iJIIM, 1.5 ml of N-β (aminoethyln γ-aminopropyl trimesisilane (manufactured by Shin-Etsu Chemical Co., Ltd.)), 150 mJ of pure water, and 1.
The mixed solution was spin-coded at 4000 rpm for 30 seconds and dried at 100° C. for 30 minutes.

Next, isoimide (for example, Diglyme/Thermid IP-600 (trade name) manufactured by Kanebo NC Co., Ltd.)
Mixing ratio of THF (diglyme and T) IF 8:2>33%
Spin code the solution at 2000 rpm for 30 seconds. Then, heat treated at 180℃ for 30 minutes, and then heated to 300℃ for 30 minutes.
After heat treatment for 0 minutes, further heat treatment at 400°C for 15 minutes, heat treatment at 300°C for 30 minutes and at 400°C for 15 minutes.

On top of that, the above steps are repeated again to obtain a film thickness of 5 μm.

Then, T a 2 is applied onto this heat insulating layer 2 by sputtering.
A heating resistor layer 3 made of N is formed, and a power supply body 4a made of NiCr-Au is formed thereon by vapor deposition and plating.
and 4b, and furthermore, S is formed thereon by sputtering.
A protective layer 5 made of l02 is formed.

Figure 3 is a schematic sectional view showing another embodiment of the thermal head according to the present invention. In the figure, the same components as in the embodiment of FIG. 1 are given the same reference numerals to explain the structure of the embodiment. In the embodiment of FIG. 0.1μTTIP by sputtering method! ．． The only difference from the actual 1tAS shown in FIG. 1 is that it includes a stress relaxation layer 6 made of Si 0 2 or the like formed in the 1tAS. This stress relaxation layer 6 allows T'a2 to be formed by sputtering.
The N heating resistor 13 is not formed directly on the heat insulating layer 2 made of a polymer compound, but via the stress relaxation layer 6. Therefore, in the stress relaxation layer 6, the heat insulating layer 2 is 'f'a2
Affected by thermal stress due to N sputtering (to reduce J)
have power. Note that the configuration other than the above is the same as the embodiment shown in FIG.

In order to confirm the performance of the thermal heads according to the above embodiments 1 and 2, the thermal heads were subjected to the following tests. All-black printing was performed on thermal recording paper by varying the selected power, and the printing density was measured using a Macbeth densitometer. For comparison, similar measurements were also performed on thermal heads having the configurations shown below as Comparative Example 1 and Comparative Example 2.

Shonu Plate 1 This is a thermal head having the same configuration as Example 1, except that the material of the heat insulating layer is glazed glass with a thickness of 10 μm.

A comparative example is a thermal head having the same structure as Example 2, except that the material of the heat insulating layer is glazed glass with a thickness of 40 μm, which differs from Example 2 above.

FIG. 4 is a graph showing the results of measuring the relationship between applied voltage and print density for the thermal heads of Example 1.2 and Comparative Example 1.2. In the figure, a. ,b,c,d
show the measurement results of Example 1.2 and Comparative Examples 1 and 2, respectively. From a comparison of Examples 1 and 2 and Comparative Examples 1 and 2, Example 1.

It was confirmed that in both Comparative Examples 1 and 2, high concentrations could be obtained with less power. Furthermore, Example 1 and Example 2
There was no difference in performance.

The heat insulating layers of Examples 1 and 2 described above have sufficient heat insulating performance, so there is no need to form holes in the heat insulating layer. It is not necessary to set the heat insulating layer 2 to 1, which simplifies the manufacturing process, and also increases the mechanical strength of the heat insulating layer 2.

Further, since no holes are required, variations in thermal response due to variations in the diameter of the holes can be eliminated.

Furthermore, since the pores are not exposed on the surface, the surface smoothness can be improved. Furthermore, since the oligomer has the property of being easily dissolved in a solvent, it is possible to improve wettability and flatness. As a result, the smoothness of the layer formed thereon can be improved, and the printing quality can be improved.

Furthermore, since ordinary polyimide is formed by thermally curing a substance that does not have reactive end groups, only imidization occurs and it becomes a polyimide with a two-dimensional network structure, so its heat resistance is not always satisfactory. Although it was not (300~
(approximately 400°C), the cured polymer film of this example has a three-dimensional crosslinked structure and has excellent heat resistance (approximately 400°C).
(about 50°C).

〔Effect of the invention〕

As explained above, the heat insulating layer of the present invention has sufficient heat insulating performance, so there is no need to form pores in the heat insulating layer, and the firing temperature is strictly set unlike conventional glazed glass that has pores. This simplifies the manufacturing process, and the mechanical strength of the heat insulating layer can be increased.

In addition, since no holes are required, it is possible to eliminate variations in thermal response due to variations in hole diameter.
Since the pores are not exposed on the surface, the surface smoothness can also be improved. Furthermore, since the oligomer has the property of being easily dissolved in a solvent, it is possible to improve wettability and flatness.

As a result, the smoothness of the layer formed thereon can be improved, and the printing quality can be improved.

Furthermore, the cured polymer film has a three-dimensional crosslinked structure and has excellent heat resistance.

[Brief explanation of drawings]

Fig. 1 is a schematic configuration diagram showing an embodiment of a thermal head according to the present invention, Fig. 2 is a schematic IR configuration diagram of a conventional thermal head, and Figs. 3(a) and (b) are heat retention diagrams of this embodiment. Figure 4 is a diagram showing the chemical formula of the oligomers constituting the layer, Figure 4 is a schematic configuration diagram showing the example of the pond, and Figure 5 is a graph showing the applied power/concentration characteristics of Example 1.2 and Comparative Example 1.2. be. 1... Alumina substrate 2... Heat insulation layer 3... Matured resistor layers 4a, 4b... Power feeder 5... Protective layer 6... Stress relaxation layer A... Maturing part

Claims (1)

[Claims] A thermal head comprising an insulating substrate, a heat insulating layer provided on the insulating substrate, and a heating resistor layer provided on the heat insulating layer, wherein the protective layer has an acetylene terminal group. A thermal head characterized in that it is formed from a polymer obtained by curing an oligomer containing at least one of a bonded isoimide oligomer and an imide oligomer bonded to an acetylene terminal group.