JPS63189252A - Thermal head - Google Patents

Abstract

PURPOSE:To prevent delamination from being caused by an interfacial tension generated due to the difference between the coefficient of thermal expansion of a heat-resistant resin layer and that of a metallic base, by forming the resin layer from a heat-resistant resin having an Si group in the molecular structure thereof and having favorable adhesion to the base. CONSTITUTION:A thermal bead comprises a metallic base 1, a heat resistant resin layer 2 comprising an imide component and provided on the base 1, a multiplicity of heat generating resistors 3 provided on the resin layer 2, and conductors connected to the resistors. The resin layer 2 is formed of a polyimide resin obtained by the reaction of biphenyl-tetracarboxylic acid dianhydride and p-phenylenediamine, and at least a part of the layer 2 on the base side is formed of a polyimide resin having an Si group at a part of the main chain of the resin. The polyimide resin can be obtained by subjecting a mixture of equivalent amounts of pphenylenediamine and biphenyltetracarboxylic acid dianhydride to a ring-opening addition reaction in an organic solvent, then applying a varnish comprising a polyamic acid solution thus obtained, and causing debydration cyclization. By this, the adhesion between the base 1 and the resistors 3 is enhanced.

Description

Detailed Description of the Invention [Objective of the Invention] (Industrial Application Field) The present invention involves forming a heat-resistant resin layer containing an imide component on a metal support, and forming a large number of heat-generating resistors on this heat-resistant resin layer. It relates to a thermal head formed by a body.

(Prior Art) In recent years, thermal heads have come to be widely used in various recording devices such as facsimiles and word processor printers, taking advantage of their advantages such as sound reception, reduced maintenance, and low running costs. - On the other hand, these lit devices are smaller,
There is a demand for lower prices, and for this reason, there is a desire for long length heads to be small and inexpensive.

By the way, conventional thermal heads are made by forming a glazed glass layer on an alumina ceramic substrate with an AJ2203 purity of 90% or more, and forming a large number of heating elements and conductors connected to the heating elements on top of the glazed glass layer. Things were used a lot. However, the ceramic substrates used in such thermal heads undergo many processes during manufacturing, such as processing to remove alkali metal components from raw powder, high-temperature firing, and finishing polishing to remove warping of the substrate that occurs during high-temperature firing. There was a problem in that the production cost was high because it required a process.

For this reason, recently, a polyimide resin layer is formed on a gold mW plate as a heat insulating layer to control heat dissipation and heat accumulation, and a large number of heating resistors are formed on this polyimide resin layer to produce a small and inexpensive thermal head. has been proposed (
Collection of summaries of the 1986 IEICE Comprehensive National Conference (198
B), 1-125 and 5°-126).

The thermal head, which is made by forming a polyimide resin layer with excellent heat resistance on a metal substrate and forming a heating resistor on top of it, is similar to the conventional gutter plate which is made by forming a glazed glass layer on an alumina M base. Compared to thermal heads using
It is considered promising as a normal head.

However, in the thermal head using this polyimide resin layer, although the polyimide resin has the feature of extremely excellent heat resistance, it has poor adhesion with the metal support J3 and the heating resistor, and as a result, it has poor adhesion with the metal support J3 and the heating resistor, so it is difficult to use in post-processing or during use. There was a problem that peeling easily occurred.

(Problems to be Solved by the Invention) In the thermal head in which a large number of heating resistors are formed on a polyimide resin layer, the polyimide resin has extremely high heat resistance and thermal efficiency, and can be bent. Although it has the advantage of being easily miniaturized, it has the problem that it tends to peel off during post-processing or during use.

The present inventors conducted intensive research to eliminate these drawbacks, and found that an aromatic polyimide obtained from biphenyltetracarboxylic dianhydride and p-phenylenediamine has excellent heat resistance and It has been found that the thermal expansion coefficient is close to that of the metal support. However, although this aromatic polyimide has properties suitable for such a thermal head, it has a problem of insufficient adhesion to a metal support.

The present inventors further conducted research to improve this point,
It has been found that this problem can be significantly improved by replacing a portion of p-phenylenediamine with p-phenylenediamine having a Si group.

The present invention was made based on this knowledge, and improves the adhesion between the heat-resistant resin layer provided on the metal substrate as a heat-retaining layer for controlling heat dissipation and heat accumulation, and the metal support and heating resistor. The aim is to provide a low-cost, high-performance thermal head that has excellent thermal efficiency, can be bent, is easily miniaturized, and has excellent thermal efficiency.

[Structure of the Invention] (Means for Solving the Problems) The thermal head of the present invention includes a metal support, a heat-resistant resin layer containing an imide component formed on the metal support, and a heat-resistant resin layer containing the imide component. In a thermal head comprising a large number of heating resistors formed on a heat-resistant resin layer containing a heat-resistant resin layer and a conductor connected to each heat-generating resistor, the heat-resistant resin layer containing an imide component contains biphenyl tetrafluoride. This is a polyimide resin obtained by the reaction of carboxylic dianhydride and p-phenylenediamine, and the metal support side of the heat-resistant resin layer containing at least the imide component has Si in a part of the main chain of the polyimide resin. It is characterized by being made of a polyimide resin having a group.

The aromatic polyimide resin used in the present invention is prepared by subjecting an equivalent mixture of p-phenylene diamine and biphenyltetracarboxylic dianhydride to a ring-opening addition reaction in an organic solvent, and applying a varnish made of the resulting polyamic acid solution. It can be obtained by dehydration and cyclization.

In order to introduce a Si group into this molecular structure, as part of p-phenylenediamine during the ring-opening addition reaction, for example, the general formula % formula % (where R is a divalent organic group such as an alkylene group , R'
represents a monovalent in such as an alkyl group. ), such as bisaminopropyltetramethyldisiloxane.

Note that the amount of diamine having 5ill such as bisaminodisiloxane is desirably 10 mol % or less based on the total diamine component.

Furthermore, in the present invention, in a range that does not substantially impair the excellent heat resistance of the aromatic polyimide obtained during the ring-opening addition reaction or the excellent adhesion with the metal support,
It is also possible to replace a part of p-phenylenediamine with other aromatic diamines, or to replace a part of biphenyltetracarboxylic acid anhydride with other aromatic tetracarboxylic acid anhydrides or dicarboxylic acids. .

Furthermore, in the present invention, by adding a silane coupling agent to the aromatic polyimide, it is possible to further improve the adhesion between the metal support and the heating resistor, especially the heating resistor.

Examples of such silane coupling agents include γ-
Aminopropyltriethoxysilane, N-phenyl-γ
Examples include silane compounds having an amino bond such as -aminopropyltrimethoxysilane and silane compounds having a urea bond such as γ-ureidopropyltrimethoxysilane.

One or more of these silane coupling agents can be added and mixed in any ratio into an aromatic polyamic acid that has undergone a ring-opening addition reaction, or an aromatic polyamic acid having a Si group in its main chain. Ru.

The amount of the silane coupling agent added to the heat-resistant resin layer is preferably about 0.05 to 10% by weight.

The heat-resistant resin layer in the thermal head of the present invention can be formed by selectively using one or more of the above varnishes to form the following laminated layer on a metal support, for example, the metal substrate 1, as shown in FIG. Can be formed in a structure.

li 叉亘1” Hirosara 1 &1 Aigo 11 (a)
・・・・・・・・・・・・・・・Pi(Si)+
Si ・・・・・・・・・・・・・・・・・・(b)
・・・・・・Pi(Si)・・・・・・
・・・・・・・・・Pi・・・・・・・・・(C)
・・・・・・Pi(Si)・・・・・・
・・・・・・Pi+Si ・・・(d) ・
・・・・・・Pi(Si)・・・・・
...Pi(Si)+Si...(8)
・・・Pi(Si)÷Si ・・・ ・・・・
・・・・・・Pi・・・・・・・・・(f) ・・・
Pi(Si)+Si ・・・・・・・・・
・・Pi+Si ・・・・・・Pi(Si)+Si
: Polyimide Pi(Si) into which 3 i groups are introduced and contains a silane coupling agent : Polyimide P into which Si groups are introduced
i+Si Polyimide containing silane coupling agent Pi: Polyimide in which SiJJ is not introduced and does not contain silane coupling agent These layer structures are formed by repeatedly applying and drying each varnish.

(Function) In the thermal head of the present invention, the heat-resistant resin layer is formed of a heat-resistant resin having Si groups in its molecular structure and has good adhesion to the metal support. Peeling caused by interfacial stress caused by the difference in expansion coefficients can be effectively prevented.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

The thermal head of this example consists of a metal substrate 1 made of an Fe alloy, a polyimide varnish made by dissolving polyamic acid represented by the formula (I) into which 5iJ3 is dissolved in an organic solvent, and a polyimide varnish represented by the formula (I[)]. Polyimide varnish made by dissolving the polyamic acid to be dissolved in an organic solvent and adding a silane coupling agent thereto is overcoated to a thickness of 5 to 100 μm.
A heat-resistant resin layer 2 with a thickness of preferably 10 to 50 μm is formed, and Ta-8iO2, Cr-SiOz, -ri-
A heating resistor 3 made of 8io2 or the like is formed.

(Left below) (In the formula, X represents one length) peφaxe, and n represents a positive number. same as below. ) Individual electrodes 5 and common electrodes 6 made of <A, 12, An-8i, etc. are formed on this heating resistor 3 to form an opening that will become a heating section 4, and cover at least this heating section 4. 5i-N-0 type oxidation prevention and wear resistance gI
7 is formed.

Formulas (III) and (IV) are molecular structures of polyimides formed by dehydration and cyclization of polyamic acids of formulas (I) and (II), respectively. The J5 cyclization model and silane coupling agent are present as a thin layer on the surface.

... (IV) And is this thermal head an individual type? By applying a pulse voltage between 4+5 and the common electrode 6 at predetermined time intervals, the heating resistor 3 of the heating section 4 generates heat and printing is performed.

This thermal head is manufactured, for example, as follows.

First, for example, the thickness is 0.311 containing 16% by weight of Cr.
A metal substrate 1 made of a Fe alloy of about 100 mL is cut into a predetermined size as a leveling pattern, and subjected to degreasing, cleaning, and heat treatment at a temperature of 600° C. to 800° C. in a dry hydrogen atmosphere. Next, the polyamic acid represented by the above-mentioned formula (1) is coated onto the metal substrate 1 to a predetermined thickness using an organic solvent such as N-methylpyrrolidone using a roller coater or a spin coater, 120℃30 in nitrogen gas atmosphere using a firing furnace
70 to 80% of the solvent is removed, and then a polyamic acid represented by the formula (IF) containing a silane coupling agent is placed on top of this to adjust the viscosity to a predetermined viscosity to obtain a predetermined film thickness. 120°C for 30 minutes, 150°C for 30 minutes, 250°C for 30 minutes, 450°C in a nitrogen gas atmosphere.
A film is formed by heating for 30 minutes.

Thereafter, Cr-8iQ2, Cr-SiO2,
A heat generating resistor 3 made of Ti=SiOz or the like is formed, and then sputtering or other known methods are used to form an opening on the heat generating resistor 3 to form a heat generating part 4.
J2, Aβ-8i, AA-8i-Cu or A
Forming individual electrodes 5 and common electrodes 6 made of U etc.,
An anti-oxidation film/wear-resistant film 7 made of S i -N-0 is formed by, for example, sputtering method so as to cover the heat generating portion 4 .

During the manufacturing process of this thermal head, the adhesion and heat resistance of the polyimide resin surface were evaluated.

Figure 3 is a graph showing the adhesion strength with metal determined from the results of a tensile test and the thermal decomposition onset temperature determined from thermal mass measurement as a function of the amount of aminosiloxane added. FIG. 3 is a diagram showing the adhesion strength of a heating resistor on a film as a function of the amount of silane coupling agent added.

From these figures, it can be seen that the substitution of diamine with Si group
is preferably in the range of about 2 to 10 mol%, and it is understood that the amount of addition 1 of the silane coupling agent is preferably in the range of about 0.05 to 10% by weight. In addition, the heating resistor of the thermal head operates at a humidity of 450°C momentarily and 250-300°C continuously, but the results shown in Figure 4 show that the addition of a silane coupling agent improves heat resistance. It can be seen that the heat-resistant life of the heat-resistant resin layer can be extended by using it on the side that is in contact with the heating resistor.

Note that when using a polyimide resin that does not have SiM on the heating resistor side without adding a silane coupling agent, it is desirable to modify the surface in order to obtain sufficient adhesive strength with the heating resistor. . This kind of surface treatment is
For example, this can be realized by plasma treatment, sputter etching treatment in Ar added with 02, or the like.

Note that since a metal support is used in the present invention, it is also possible to use this metal support as a common electrode to further reduce production costs. Further, the oxidation-preventing and wear-resistant film does not necessarily have to be provided on the entire surface, but it can sufficiently function as long as it is formed on at least the heat-generating portion.

[Effects of the Invention] As explained above, in the present invention, a polyimide resin obtained by the reaction of biphenyldetracarboxylic dianhydride and p-phenylenediamine is used as the heat-resistant resin formed on the metal support. Moreover, since a polyimide resin having a Si group in a part of the main chain of this polyimide resin is used at least on the metal support side, the adhesion with the metal support and heating resistor is significantly improved, and heat resistance is improved. As a result, it is possible to provide a thermal head that is highly reliable, inexpensive, and compact.

[Brief explanation of the drawing]

FIG. 1 is an enlarged sectional view showing the main parts of a thermal head according to an embodiment of the present invention, and FIGS. Figures 3 and 4, which are cross-sectional views showing structural examples containing Si groups in the molecular structure, respectively show the adhesion strength and thermal decomposition initiation temperature as a function of the amount of bis-aminosiloxane or silane coupling agent added. It is a graph. 1...Metal substrate 2...Heat-resistant resin layer 3...
...Heating resistor 4...Heating part 5...Individual electrode 6...・・Common electrode 7・・・・・・・・・・・ Anti-oxidation film and wear-resistant film Applicant Toshiba Corporation Patent attorney Sa Suyama - Go to Figure 1 Go to 1 Go to 1 (a) (b )fart
to 1 (C) (d) ~1 βJ Figure 2 (: Figure 3 Field Figure 4

Claims (7)

[Claims] (1) a metal support, a heat-resistant resin layer containing an imide component formed on the metal support, and a large number of heating resistors formed on the heat-resistant resin layer containing the imide component;
In a thermal head comprising a conductor connected to each of these heating resistors, the heat-resistant resin layer containing the imide component is made of polyimide obtained by a reaction of biphenyltetracarboxylic dianhydride and p-phenylenediamine. A thermal head characterized in that the metal support side of the heat-resistant resin layer containing at least the imide component is made of a polyimide resin having a Si group in a part of the main chain of the polyimide resin. (2) The polyimide resin is formed through a cyclodehydration reaction of a polyamic acid obtained by a ring-opening addition reaction of biphenyltetracarboxylic dianhydride and p-phenylenediamine, and A polyamic resin obtained by a ring-opening addition reaction of a polyimide resin partially containing Si groups with a diamine obtained by substituting a portion of the biphenyltetracarboxylic anhydride and p-phenylenediamine with a diamine containing Si groups. The thermal head according to claim 1, which is formed through a dehydration cyclization reaction of an acid. (3) The diamine having a Si group is represented by the general formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (In the formula, R is a divalent organic group and R' is a monovalent organic group.) 3. The thermal head according to claim 1 or 2, wherein the thermal head is bisaminodisiloxane. (4) The thermal head according to claim 3, wherein in the formula, R is an alkylene group and R' is an alkyl group. (5) At least the heating resistor side of the heat-resistant resin layer is made of a silane compound having an amino bond and a silane bond having a urea bond in a polyamic acid obtained by a ring-opening addition reaction of biphenyltetracarboxylic dianhydride and p-phenylenediamine. Claim 1, characterized in that the polyamic acid is formed through a dehydration cyclization reaction of a polyamic acid to which at least one compound is added as a silane coupling agent component.
The thermal head according to any one of items 1 to 4. (6) The silane compound having an amino bond is γ-aminopropyltriethoxysilane, N-phenyl-γ-
The thermal head according to claim 5, characterized in that it is any one of aminopropyltrimethoxysilane. (7) The thermal head according to claim 5, wherein the silane compound having a urea bond is γ-ureidopropyltrimethoxysilane.