JP2865709B2 - Electrostrictive effect element and method of manufacturing the same - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated electrostrictive element in which a large displacement is generated at a low voltage and an interlayer distance is extremely small, and a method of manufacturing the same.

[Prior art] Conventionally, as an actuator, a motor that operates by an electromagnetic force, a motor that converts the rotation of the electromagnetic motor into a linear motion by a combination of gears, a voice coil that combines an electromagnetic coil and a spring, and the like are known. It is typical. These actuators are widely used in all machines for high-speed continuous rotation and positioning.
In recent years, needs for new conversion elements have been rapidly increasing, mainly in fields such as optical precision machines and semiconductor elements. For example, requirements for processing accuracy of optical equipment such as lasers and cameras, positioning accuracy in semiconductor manufacturing equipment, and adjustment of optical path length in optics and astronomy have already reached the level of 1 micron or less. Obviously, it will be more and more severe.

Recently, actuators that use the piezoelectric effect and electrostriction effect as new actuators that do not use electromagnetic force are in the spotlight, and there is great expectation for their future potential in the electronics ceramics market to expand into new genres. Have been.

Conventionally, an electrostrictive effect element having a multilayer chip capacitor structure has been manufactured by the following method. First, the raw material composition is mixed and calcined, a suitable binder and a solvent are mixed with the calcined powder, and a thin film is formed using the mixture by a doctor blade method. A metal electrode is printed on this thin film and laminated. Every other metal electrode plate in this laminate is connected to an external electrode, and one system is positive and the other system is negative. In this manufacturing method, the area of the overlapping portion of the positive and negative electrode plates must be smaller than the total cross-sectional area,
Therefore, in the peripheral portion, a portion where the electrode plates do not overlap occurs. When a voltage is applied between the electrode plates of such an electrostrictive effect element,
The electric field strength is large in the overlapping portion of the electrode plates, but the electric field strength in the peripheral portion is weak. For this reason, there is a disadvantage that the displacement amount of the peripheral portion is small, and the displacement amount of the whole element is smaller than desired. In addition, stress concentration occurs at the boundary between the deformed portion and the non-deformed portion due to this, and there is a disadvantage that the element itself is broken due to long-time application or repeated application.
For this reason, it is difficult to use the conventional manufacturing method of the multilayer chip capacitor as it is.

As a method for solving the above disadvantages, Japanese Patent Laid-Open No.
No. 15579, using an electrophoresis method, an electrostrictive element characterized by forming an inorganic insulating layer on the entire surface or every other electrode exposed on the side end surface of the laminated electrostrictive element Is disclosed. When such a manufacturing method is used, the above-mentioned disadvantages are eliminated. However, although it is most preferable that the insulator adheres only to the electrode near the side end surface of the laminated electrostrictive effect element so that the insulating layer does not hinder the electrostrictive effect or the insulating layer itself is broken. The inorganic insulating layer adheres widely to the ceramic body because of its good compatibility with the ceramic body.Therefore, the distance between the layers must be at least 100 microns so that the insulating layers attached to the electrodes exposed on the side end surfaces do not continue with each other. No. However, if the interlayer is more than 100 microns,
In order to apply an electric field of 10 kV / cm to this electrostrictive effect element, 1
A high voltage of 00V is required.

[Problems to be Solved by the Invention] In recent years, since an electrostrictive effect element which can be driven at a low voltage and has a large displacement amount is required, it is apparent that a smaller distance between layers is preferable. However, as described above, as long as the inorganic insulator is used, the interlayer distance is limited to 100 microns. Further, in the above-mentioned Japanese Patent Application Laid-Open No. 59-115579, it has been considered that practical use as insulation of an electrostrictive element in which insulation with an organic substance has low adhesion to ceramics and metal and a high electric field is applied is difficult. Is described. Such a laminated electrostrictive element capable of obtaining a large displacement at a low voltage and a method of manufacturing the same have not yet been put to practical use.

An object of the present invention is to utilize an organic insulator and to reduce the interlayer distance to 10
An object of the present invention is to provide a laminated electrostrictive effect element capable of achieving a large displacement amount at a low voltage, and a method of manufacturing the same.

[Means for Solving the Problems] The present invention has been made to achieve the above object, and an electrostrictive effect element of the present invention has a structure in which a film or thin plate of an electrostrictive material and an internal electrode plate are alternately arranged. An end surface of the internal electrode plate is exposed at a side end surface of the element, and an exposed portion of the internal electrode plate on the side end surface and an electrostrictive material in the vicinity thereof are provided. Only above, the general formula (I) (Wherein X is a phenyl group; a biphenyl group; and at least one of the phenyl group and the biphenyl group is O, CO, S, CH
₂ , a tetravalent group selected from the group consisting of a polyphenyl group linked by at least one of C (CH ₃ ) ₂ and C (CF ₃ ) ₂ , wherein Y is a phenyl group; a biphenyl group; And at least one of the biphenyl groups is O, CO, S, SO ₂ , C
H ₂ , a divalent group selected from the group consisting of a polyphenyl group, an alkylene group, and a xylylene group bonded by at least one of C (CH ₃ ) ₂ and C (CF ₃ ) _2. Characterized in that a polyimide resin insulating layer having a repeating unit is formed.

The manufacturing method of the present invention for manufacturing the above electrostrictive effect element,
An electrostrictive element in which an end surface of the internal electrode plate is exposed at a side end surface of the electrostrictive element in which a film or a thin plate of an electrostrictive material and an internal electrode plate are alternately laminated is represented by a general formula (II) (Wherein X is a phenyl group; a biphenyl group; and at least one of the phenyl group and the biphenyl group is O, CO, S, CH
₂ , a tetravalent group selected from the group consisting of a polyphenyl group linked by at least one of C (CH ₃ ) ₂ and C (CF ₃ ) ₂ , wherein Y is a phenyl group; a biphenyl group; And at least one of the biphenyl groups is O, CO, S, SO ₂ , C
H ₂ , a divalent group selected from the group consisting of a polyphenyl group, an alkylene group, and a xylylene group bonded by at least one of C (CH ₃ ) ₂ and C (CF ₃ ) _2. The carboxyl group of the polyamic acid resin having a repeating unit is neutralized with a base, immersed in a film-forming electrophoresis bath obtained by diluting with water, and electrophoresis using the internal electrode plate of the electrostrictive effect element as an anode. To form a coating layer by depositing the polyamic acid only on the exposed portion of the internal electrode plate on the side end surface of the electrostrictive effect element and in the vicinity thereof, and then heat-treat the polyamide acid of the coating layer. The resin is imidized to give a compound of the general formula (I) (Wherein X and Y are as defined above). An insulating layer of a polyimide resin having a repeating unit represented by the following formula is formed.

The polyamic acid resin used in the production method of the present invention may be partially imidized in advance.

In the polyimide resin having the repeating unit represented by the general formula (I) and the polyamide resin having the repeating unit represented by the general formula (II), specific examples of X include the following: Further, specific examples of Y include the following: From the viewpoint of adhesion and heat resistance of the polyimide resin having the repeating unit represented by the general formula (I) to the electrostrictive element substrate, X is Or And Y is Is particularly preferred.

The above general formula (I) used in the production method of the present invention.
The polyamic acid resin having a repeating unit represented by I) has a general formula (III) (Wherein X is as defined above) and a general formula (IV) H ₂ N—Y—NH ₂ (IV) wherein Y is as defined above. Obtained by an addition reaction with diamines.

As the above tetracarboxylic anhydrides, for example,
Pyromellitic dianhydride, 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride, 2,2', 3,3'-benzophenonetetracarboxylic dianhydride, 3,3 ', 4, 4'-biphenyltetracarboxylic dianhydride, 2,2 ', 3,3'-biphenyltetracarboxylic dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, 2, 2-bis (2,3-dicarboxyphenyl) propane dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride,
Bis (3,4-dicarboxyphenyl) sulfone dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane dianhydride, bis (2,3-dicarboxyphenyl) methane dianhydride, bis (3,4-dicarboxyphenyl) methane dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride,
1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,2,
3,4-benzenetetracarboxylic dianhydride, 3,4,9,10-
Preferred are perylenetetracarboxylic dianhydride, 2,3,6,7-anthracenetetracarboxylic dianhydride, 1,2,7,8-phenanthrenetetracarboxylic dianhydride and the like. Of these, particularly preferred tetracarboxylic dianhydrides are pyromellitic dianhydride, 3,3 ′, 4,
4'-benzophenonetetracarboxylic dianhydride, 3,
3 ', 4,4'-biphenyltetracarboxylic dianhydride and bis (3,4-dicarboxyphenyl) ether dianhydride.

Examples of the above diamines include 3,3'-diaminobenzophenone, 1,3-bis (3-aminophenoxy) benzene, 4,4'-bis (3-aminophenoxy) biphenyl, and 2,2-bis [4- (3-aminophenoxy) phenyl] propane, 2,2-bis [4- (3-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, bis [4- (3- Meta-position diamines such as amino [phenoxy) phenyl] sulfide, bis [4- (3-aminophenoxy) phenyl] ketone, and bis [4- (3-aminophenoxy) phenyl] sulfone; Alternatively, two or more kinds are used in combination.

The reaction between the tetracarboxylic anhydride and the diamine is usually performed in an organic solvent. As the organic solvent, for example, N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, 1,3-dimethyl-2-imidazolidinone, N, N-diethylacetamide, N, N-dimethylmethoxyacetamide, dimethylsulfoxide, pyridine, dimethylsulfone, hexamethylphosphoramide, tetramethylurea, N-methylcaprolactam, tetrahydrofuran, m-dioxane, p
-Dioxane, 1,2-dimethoxyethane, bis (2-methoxyethyl) ether, 1,2-bis (2-methoxyethoxy) ethane, bis [2- (2-methoxyethoxy)
Ethyl] ether and the like. These organic solvents may be used alone or in combination of two or more. The reaction temperature is usually about 200 ° C. or lower, −20 ° C. or higher, preferably 50 ° C. or lower, −10 ° C. or higher, and more preferably about 0 ° C. or higher, about room temperature. The reaction pressure is not particularly limited, and the reaction can be sufficiently performed at normal pressure. The reaction time may vary depending on the type of the solvent, the reaction temperature and the diamine or acid dianhydride used, but it is usually 2 to 40 hours, preferably 4 to 24 hours for the reaction to be carried out for a time sufficient to complete the formation of the polyamic acid. About an hour is enough.

The polyamic acid solution thus obtained is a solution containing 5 to 40% by weight, particularly preferably 10 to 30% by weight of polyamic acid, and has a logarithmic viscosity of 0.5 to 4 dl / g (35 ° C., temperature 0.5 g / m 2
l, the value measured with N, N-dimethylacetamide), particularly preferably 0.6 to 2.5 dl / g, the water solubility described below,
Also, it is desirable because the polyimide film properties after the heat treatment are excellent.

In the production method of the present invention, the polyamic acid resin having a repeating unit represented by the above general formula (II) is prepared by adding a base, for example, an amine or an alkali metal ion in the presence of water, so that the COOH group becomes COO ^- ion. And can be dissolved in water or can be stably dispersed in colloid, and can be precipitated and insolubilized by electrophoresis on the laminated electrostrictive effect element as an anode.

Examples of the base include ammonia: secondary amines such as dialkylamine, diethanolamine, and morpholine: triethylamine, tributylamine, triethanolamine, triisopropanolamine, dimethylethanolamine, dimethylisopropanolamine, diethylethanolamine, dimethylbenzylamine, and the like. Tertiary amines: Inorganic bases such as caustic soda and caustic potash are used, but tertiary amines are particularly preferable in view of stability after dilution with water and properties of a coating film obtained.

The amount of base required for imparting water dilutability is 30 to 110 mol% based on the carboxyl equivalent of the polyamic acid to be neutralized.
In general, and particularly preferably 40 to 100 mol%. By performing the neutralization in this manner, the polyamic acid becomes completely water-soluble or partially solubilized to become a suspended state and becomes water-dilutable. In any case, by neutralizing the polyamic acid and diluting it with water so as to have a resin concentration of the following degree, an electrophoretic bath for forming a film comprising a polyamic acid aqueous solution capable of electrophoresis treatment and You can do it.

The polyamic acid resin thus precipitated is subjected to a heat treatment to obtain a compound of the general formula (I) (Wherein X is as defined above) is converted to a polyimide resin having a repeating unit represented by the following formula:

The polyimide resin insulating layer obtained as described above has an insulating layer thickness of about 50 μm, has a dielectric strength of 1000 V or more, and has excellent adhesion to metal. In addition, since the wettability with ceramics, which has been a problem so far, is smaller than that of the inorganic insulating layer, the insulating layer adheres only in the vicinity of the side end surface, and the distance between the layers can be extremely reduced as compared with the conventional one. is there.

Example 1 In a reaction vessel equipped with a stirrer, a reflux condenser and a nitrogen inlet tube, 53.0 g (0.25 mol) of 3,3'-diaminobenzophenone was dissolved in 240 ml of N, N-dimethylacetamide. To this solution was added powder of 78.6 g (0.244 mol) of 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride,
The mixture was stirred for 24 hours to obtain a polyamic acid solution. The logarithmic viscosity of the obtained polyamic acid was 0.6 dl / g. 39.1 g of dimethylethanolamine (90 mol% based on carboxyl equivalent) was gradually added to the polyamic acid solution, and the mixture was stirred at room temperature for 20 minutes. An aqueous acid solution was prepared (resin concentration 10% by weight).

Further, with respect to the sample of the laminated body, one in which metal electrodes were exposed at every other end face and all metal electrodes were exposed at the other end face was prepared in advance. A silver electrode was baked on the side where the metal electrode was exposed every other layer, and a lead wire was connected with solder. The aqueous solution was put into a plastic tank, used as an electrophoresis bath for forming a film, and the laminate to be coated was infiltrated with the anode and a lead wire was connected to the anode. Electrophoresis was performed by applying a voltage at 100 V for 20 seconds. Thereafter, the laminate was taken out, washed with water, and subjected to heat treatment at 150 ° C. for 2 hours and 280 ° C. for 2 hours to perform dry imidization. Next, the laminate was cut in the middle, a silver electrode was applied to the side where the imide resin insulating film was attached, and a lead wire was attached. By performing the same operation, a laminate having insulating layers on the left and right for each electrode was obtained. It was confirmed that the thickness of this insulating layer was about 50 microns and the dielectric strength was 1000 V or more.

Example 2 In a container equipped with a stirrer, a reflux condenser and a nitrogen inlet tube,
2,2-bis [4- (3-aminophenoxy) phenyl]
41.0 g (0.1 mol) of propane and 200 ml of N, N-dimethylacetamide were charged, cooled to around 0 ° C., and a powder of 21.8 g (0.1 mol) of pyromellitic dianhydride was added under a nitrogen atmosphere. The mixture was stirred at around ° C for 2 hours. Next, the solution was returned to room temperature and stirred under a nitrogen atmosphere for about 20 hours.
The logarithmic viscosity of the polyamic acid thus obtained was 1.5 dl / g. Triethylamine 2 in this polyamic acid solution
0.2 g (relative to carboxyl equivalent 100 mol%)
After stirring at room temperature for 97 hours, 973 g of water was gradually added with stirring to dilute to prepare a polyamic acid aqueous solution (resin concentration: 5% by weight).

A sample of the laminated body was prepared in the same manner as in Example 1, and an insulating layer was provided in the same manner as in Example 1 using this sample and the above-mentioned polyamic acid aqueous solution. This insulating layer has a thickness of 50μ and 10
It had a dielectric strength of 00V or more.

Example 3 In a container equipped with a stirrer, a reflux condenser and a nitrogen inlet tube,
2,2-bis [4- (3-aminophenoxy) phenyl]
Add 41.0 g (0.1 mol) of propane and 219.6 g of N, N-dimethylacetamide, and add 3,3 ', 4,
4'-benzophenonetetracarboxylic dianhydride 31.6 g
(0.098 mol) in a dry solid state while paying attention to the rise in solution temperature, and reacted at room temperature for 23 hours. The logarithmic viscosity of the polyamic acid thus obtained was 0.70 dl / g. Triethanolamine in this polyamic acid solution
14.6 g (relative to carboxyl equivalent 50 mol%) was gradually added,
The mixture was stirred for 2 hours at 40 ° C., and 117.2 g of water was gradually added thereto with stirring for dilution to prepare a polyamic acid aqueous solution (resin concentration: 15% by weight).

A sample of the laminated body was prepared in the same manner as in Example 1, and an insulating layer was provided in the same manner as in Example 1 using this sample and the above-mentioned polyamic acid aqueous solution. This insulating layer has a thickness of 50μ and 10
It had a dielectric strength of 00V or more.

Examples 4 to 19 Change the type and amount of diamine, the amount of N, N-dimethylacetamide, the type and amount of tetracarboxylic dianhydride, the amount of dimethylethanolamine used for neutralization, and the amount of water used for dilution. The other operations were the same as in Example 1.

The amount of dimethylethanolamine used for neutralization was calculated from 90% by weight of carboxyl equivalent,
The amount of water used for dilution was calculated to be a resin concentration of 10% by weight. In the table, PMDA is pyromellitic anhydride, BTDA is 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride, ODPA is bis (3,4-dicarboxyphenyl) ether dianhydride, and BPDA is 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride is shown.

In each case, the insulating layer had a thickness of 50 μm and a dielectric strength of 1000 V or more.

[Effects of the Invention] According to the present invention, it has been impossible to reduce the thickness of one layer of the laminate to 100 μm or less.
It is now possible to make a micron. In addition, organic materials have not been noticed as having poor insulating properties, but surprisingly, use of a polyimide resin has increased the insulating power to a level comparable to inorganic materials.

Claims (2)

(57) [Claims] 1. An electrostrictive effect element in which a film or thin plate of an electrostrictive material and an internal electrode plate are alternately laminated, wherein an end face of the internal electrode plate is exposed at a side end face of the element. Only on the exposed portion of the internal electrode plate on the side end face and on the electrostrictive material in the vicinity thereof, the general formula (I) (Wherein X is a phenyl group; a biphenyl group; and at least one of the phenyl group and the biphenyl group is O, CO, S, CH
₂ , a tetravalent group selected from the group consisting of a polyphenyl group linked by at least one of C (CH ₃ ) ₂ and C (CF ₃ ) ₂ , wherein Y is a phenyl group; a biphenyl group; And at least one of the biphenyl groups is O, CO, S, SO ₂ , C
H ₂ , a divalent group selected from the group consisting of a polyphenyl group, an alkylene group, and a xylylene group bonded by at least one of C (CH ₃ ) ₂ and C (CF ₃ ) _2. An electrostrictive effect element, wherein an insulating layer of a polyimide resin having a repeating unit is formed. 2. An electrostrictive element in which an end face of the internal electrode plate is exposed at a side end face of the electrostrictive element in which a film or a thin plate of an electrostrictive material and an internal electrode plate are alternately laminated. General formula (I
I) (Wherein X is a phenyl group; a biphenyl group; and at least one of the phenyl group and the biphenyl group is O, CO, S, CH
₂ , a tetravalent group selected from the group consisting of a polyphenyl group linked by at least one of C (CH ₃ ) ₂ and C (CF ₃ ) ₂ , wherein Y is a phenyl group; a biphenyl group; And at least one of the biphenyl groups is O, CO, S, SO ₂ , C
H ₂ , a divalent group selected from the group consisting of a polyphenyl group, an alkylene group, and a xylylene group bonded by at least one of C (CH ₃ ) ₂ and C (CF ₃ ) _2. The carboxyl group of the polyamic acid resin having a repeating unit is neutralized with a base and immersed in an electrophoresis bath for film formation obtained by diluting with water, and electrophoresis using the internal electrode plate of the electrostrictive effect element as an anode. To form a coating layer by depositing the polyamic acid only on the exposed portion of the internal electrode plate on the side end surface of the electrostrictive effect element and in the vicinity thereof, and then heat-treat the polyamide acid of the coating layer. The resin is imidized to give a compound of the general formula (I) The method for producing an electrostrictive effect element according to claim 1, wherein an insulating layer of a polyimide resin having a repeating unit represented by the following formula (where X and Y are as defined above) is formed.