JP2008300679A - Method for manufacturing piezoelectric body, and ink jet recording head using the piezoelectric body - Google Patents

Abstract

A method for manufacturing a piezoelectric body with high uniformity and an ink jet recording head are provided.
A method for producing a metal oxide obtained by drying and solidifying a solution containing a metal component and an organic component that form a piezoelectric body made of metal oxide, and heating the solid content at a crystallization temperature or higher. In the method for producing a piezoelectric body, the method includes a step of contacting the supercritical fluid and removing an organic component before the step of heating to a temperature equal to or higher than the crystallization temperature. An ink jet recording head comprising ink ejection means for ejecting ink by vibrating a diaphragm by displacement of a piezoelectric element using a piezoelectric body manufactured by the above method.
[Selection] Figure 2

Description

  The present invention relates to a method for manufacturing a metal oxide piezoelectric body that can be expected to be applied to a piezoelectric device, and an ink jet recording head using the piezoelectric body.

  Conventionally, metal oxides have been widely used in various industries, and are widely used as functional materials and functional films with a wide variety of properties. For example, a conductive film, a semiconductor material, a sensor material, an insulating film, a piezoelectric body, and the like can be given.

  In particular, the piezoelectric body has a property capable of converting electrical energy into mechanical energy, and is used in an inkjet printer, an ultrasonic motor, a fuel injector, and the like. Research into non-volatile memories that take advantage of the properties of spontaneous polarization and high dielectric constant is also underway.

  Such a piezoelectric body is formed by molding and baking metal oxide powder, forming a metal oxide film on a substrate by sputtering, or a sol-gel liquid or metal organic compound comprising a metal alkoxide, an organic compound, and a solvent. The above solution can be applied on a substrate or dried as it is and solidified to be heated and crystallized.

  In the method of manufacturing from the sol-gel solution and the metal compound solution, the metal can be easily mixed and homogenized, so that it is possible to manufacture a complex composite oxide more easily than other methods. Has been.

  In any method, the solid content before firing includes alcohols, solvents, plasticizers, acidic substances, alkaline substances, polymer compounds, and other organic compounds coordinated to metals as organic components.

  These organic components are unnecessary when crystallized and must be removed in the process before crystallization. As a removal method, a method of removing a binder by supercritical treatment from a mixture of a powder and a binder has been reported (see Patent Document 1).

In addition, a method for performing supercritical processing on a thin film on a substrate has been reported (see Patent Document 2).
In particular, if it is removed efficiently before crystallization, the firing temperature can be lowered and the time can be shortened.
JP-A 61-155265 Japanese Patent Laid-Open No. 2-113525

  However, the above-mentioned method for removing the binder only describes the method for removing the binder from the mixture of the powder and the binder, and can be applied as it is when the piezoelectric body is produced from the sol-gel solution or the metal organic compound solution. It is difficult to do.

  In the method of performing supercritical processing on a thin film on a substrate, a method using supercritical processing is described in the method of forming a silicon oxide thin film on a semiconductor substrate. Only a method for producing a silicon oxide thin film by a solution method or a CVD method is described.

The production of bulk bodies such as moldings and particles by drying and solidifying from a sol-gel solution or a metal organic compound solution, followed by heating and crystallization is not described.
SUMMARY OF THE INVENTION The present invention solves the above-described conventional problems. A bulk body of a piezoelectric body is produced by drying and solidifying a sol-gel solution or a metal organic compound solution forming a piezoelectric body, and then heating and crystallizing. In this case, by efficiently removing the organic component from the precursor containing the metal component and the organic component before crystallization, the crystallization firing temperature is lowered and the time is shortened, and a highly uniform piezoelectric body is obtained. A method of manufacturing is provided.

  The present invention also provides an ink jet recording head using a highly uniform piezoelectric body obtained by the above manufacturing method.

  A method for producing a metal oxide that solves the above problems includes a step of drying and solidifying a solution containing a metal component and an organic component that form a piezoelectric body made of metal oxide, and heating the solid content at a temperature equal to or higher than the crystallization temperature. In the method for producing a metal oxide obtained by the step, the method includes a step of removing an organic component by contacting with a supercritical fluid before the step of heating to a temperature higher than the crystallization temperature.

  An ink jet recording head that solves the above problems includes an ink ejection unit that ejects ink by vibrating a vibration plate by displacement of a piezoelectric element using a piezoelectric body manufactured by the above method. Features.

  The present invention efficiently removes an organic component from a precursor including a metal component and an organic component forming a piezoelectric body before crystallization, thereby lowering the crystallization firing temperature and achieving high uniformity. A method of manufacturing a metal oxide and a piezoelectric body can be provided.

  The present invention can also provide an ink jet recording head using a highly uniform piezoelectric body obtained by the above manufacturing method.

Hereinafter, the present invention will be described in detail.
The method for manufacturing a piezoelectric body according to the present invention is obtained by drying and solidifying a solution containing a metal component and an organic component that form a piezoelectric body made of metal oxide, and heating the solid content at a crystallization temperature or higher. The method for producing a metal oxide includes a step of removing an organic component by contacting with a supercritical fluid before the step of heating to a temperature higher than the crystallization temperature.

The supercritical fluid is preferably water or carbon dioxide in a supercritical state.
The metal component forming the piezoelectric body is preferably at least one selected from lead, zirconia, titanium, bismuth, alkali metal, and alkaline earth metal.

Hereinafter, the form of the piezoelectric body embodying the present invention will be described in detail.
The piezoelectric body is made of a crystallized metal oxide of ferroelectric or paraelectric. As a composition, a system mainly composed of lead zirconate titanate (hereinafter referred to as “PZT”) or a system in which lanthanum, manganese, niobium, or the like is added to PZT is known.

  Lead-free systems include oxides based on potassium, sodium and niobium, oxides based on calcium, bismuth and titanium, and oxides based on bismuth, sodium and titanium. Etc.

In the method of forming a piezoelectric body of the present invention, a molded product or particles of a piezoelectric body are produced by drying and solidifying a solution of a metal organic compound that forms the piezoelectric body, and then heating and crystallizing the solution.
The metal oxide solution comprises a solution containing a hydrolyzable compound of each component metal as a raw material, a partial hydrolyzate thereof or a partial polycondensate thereof. Further, the piezoelectric body is formed by further drying and solidifying the metal oxide solution, followed by firing at a temperature equal to or higher than the crystallization temperature to cause crystallization. As the raw material hydrolyzable metal compound, an organic compound such as a metal alkoxide, a partial hydrolyzate or a partial polycondensate thereof is generally used.

  More specifically, an example of a metal oxide solution using Pb (lead), La (lanthanum), Zr (zirconia), and Ti (titanium) as the metal used for the piezoelectric body will be described. First, an alkoxide such as Pb, La, Zr, Ti, and / or a metal salt is dissolved in a solvent, and then water is added to cause hydrolysis.

  Solvents used include alcohol solvents such as methanol, ethanol, n-propanol, isopropanol, n-butanol, s-butanol and t-butanol, ether solvents such as tetrahydrofuran and 1,4-dioxane, and 2-methoxyethanol. Cellosolve such as 2-ethoxyethanol, 1-methoxy-2-propanol, polyhydric alcohols such as diethylene glycol monoethyl ether, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether, diethylene glycol monobutyl ether acetate, N, N-dimethylformamide, Examples thereof include amide solvents such as N, N-dimethylacetamide and N-methylpyrrolidone, and nitrile solvents such as acetonitrile. Of these, alcohol solvents are preferred. The amount of the solvent used is usually 5 to 200 times mol, preferably 10 to 100 times mol with respect to the metal alkoxide. If the amount of the solvent is too large, metal aggregation and precipitation are likely to occur, and if it is too small, the heat generated during hydrolysis becomes intense.

  Pb alkoxide compounds include lead 2-ethoxyethoxysite, lead methoxide, lead ethoxide, lead n-propoxysite, lead i-propoxysite, lead n-butoxysite, lead i-butoxysite, lead t. -Butoxysite, and other various alkoxides and alkyl-substituted products thereof.

  In addition, inorganic salt compounds of Pb, specifically chloride, nitrate, phosphate, sulfate and the like, and organic salt compounds specifically include formate, acetate, propionate, oxalate, citrate, Various carboxylates such as malates, hydroxycarboxylates, and acetylacetonate complexes may be mixed with a solvent to synthesize alkoxides in the system. For La, Mg, Zr, Ti, and Nb, the same alkoxide compound or inorganic salt can be used. These alkoxide solutions or inorganic salts of Pb, La, Mg, Zr, Ti, and Nb are dissolved in the solvent and hydrolyzed to polymerize to obtain a piezoelectric solution.

Charge ratio of each metal, for example Pb, La, Zr, when using a _{Ti, Pb (1-x)} La x (Zr y Ti 1-y) 1-x O 3 ( where, 0 ≦ x <1 0 ≦ y ≦ 1), but since Pb disappears during the firing process, the amount of Pb is preferably increased in advance during the preparation of the coating liquid. _{Specifically, Pb (1-x) La} x (Zr y Ti 1-y) 1-x O 3 ( where, 0 ≦ x <1,0 ≦ y ≦ 1) the molar ratio of the Pb 5% It may be increased in the range of 30% or less.

  The hydrolysis of the solution containing the metal alkoxide and / or metal salt uses, for example, 0.05 to 8 moles of water of the metal alkoxide and / or metal salt, more preferably 0.5 moles. Double or more and 4 mol times or less of water is used. For this hydrolysis, an acid catalyst and / or a base catalyst may be used. Preferably, a metal salt, a halide, a mineral acid such as sulfuric acid, nitric acid or hydrochloric acid, or an organic acid such as acetic acid is used.

  After hydrolysis of the metal composition solution, the solvent having a boiling point of 100 ° C. or lower is completely removed, and the solvent having a boiling point of 100 ° C. or higher is added in an amount of 50% or higher. As the solvent used, cellosolve such as 1-methoxy-2-propanol, 2-ethoxyethanol, 3-methoxy-3-methylbutanol, diethylene glycol monoethyl ether, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether, diethylene glycol monobutyl ether Examples include polyhydric alcohols such as acetate, and fragrance oils such as terpineol, pine oil, and lavender oil. A cellosolve solvent is preferable. Further, cellulose derivatives such as ethyl cellulose and hydroxypropyl cellulose, polymer resins such as polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl butyral, polymethyl methacrylate, rosin, rosin derivatives and the like may be used for the purpose of improving the stability of the solution. .

The above solution is solidified by drying the solvent. Solidification may be performed while casting into a desired mold, or may be made into powder or fine particles by crushing after drying.
For drying the solvent, a dryer, a dryer, a hot plate, a tubular path, an electric furnace, or the like can be used.

Subsequently, the molded product, powder, and fine particles of the piezoelectric body are immersed in a supercritical fluid to remove organic components.
In the present invention, the organic component is an organic solvent, metal salt, halide, mineral acid such as sulfuric acid, nitric acid and hydrochloric acid, organic acid such as acetic acid, and cellulose derivatives such as ethyl cellulose and hydroxypropyl cellulose. It refers to polymer resins such as polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl butyral, polymethyl methacrylate, polymer compounds such as rosin and rosin derivatives, and organic substances produced in the reaction during the preparation of the solution.

  A fluid in a supercritical state will be described. FIG. 1 is a phase diagram showing the state of a substance in relation to temperature and pressure. As shown in FIG. 1, a substance can take three states: gas, liquid, and solid depending on changes in temperature and pressure. The boundary between gas and liquid is a vapor pressure curve, the boundary between gas and solid is a sublimation curve, and the boundary between liquid and solid is a melting curve.

  Above the critical point inherent to the substance, the gas-liquid interface disappears, the liquefaction phenomenon disappears, and it exists as a high-density gas state. A substance that exists in such a state is called a supercritical fluid.

Carbon dioxide has a temperature of 31.0 ° C. or higher and a pressure of 7.38 × 10 ⁶ Pa (72.9 atm) or higher, and water has a temperature of 374.2 ° C. or higher and a pressure of 2.21 × 10 ⁷ Pa (218. It becomes a supercritical fluid at 3 atm or higher.

  A supercritical fluid has a viscosity close to that of a gas and a dissolving power close to that of a liquid. Therefore, the supercritical fluid is very effective for removing organic components from a precursor of a piezoelectric body by the solution method. The form of the precursor may be a molded body, powder or fine particles.

After the removal of the organic component by the supercritical fluid is completed, the main body is further fired in the range of 500 ° C. or higher and 800 ° C. or lower to obtain a piezoelectric body.
Next, the ink jet recording head of the present invention will be described.

  An ink jet recording head according to the present invention is characterized in that it includes an ink ejecting means for ejecting ink by vibrating a vibration plate by displacement of a piezoelectric element using a piezoelectric body manufactured by the above method. .

  FIG. 2 is a schematic view showing an embodiment of the ink jet recording head of the present invention. In FIG. 2, a part of an ink jet printer head in which a piezoelectric body is used as an actuator is shown enlarged. The basic configuration of the ink discharge means is composed of a head base 16, a diaphragm 14, and a piezoelectric element 17 using a piezoelectric body. The piezoelectric element 17 includes an upper electrode 11, a piezoelectric body 12, and a lower electrode 13. The head base 16 includes a plurality of ink nozzles 15 that eject ink, a large number of ink paths (not shown) that individually communicate with the respective ink nozzles 15, and a large number that individually communicate with the respective ink paths. An ink chamber (not shown) is formed. A vibration plate 14 is attached so as to cover the entire upper surface of the head base 16, and the upper surface openings of all ink chambers of the head base 16 are closed by the vibration plate 14. A piezoelectric element 17 for applying a vibration driving force to the vibration plate 14 is formed on the vibration plate 14 at a position corresponding to each ink chamber. Then, a voltage is applied from the power source 18 to the desired piezoelectric element 17 so as to displace the piezoelectric element 17 and vibrate the diaphragm 14 at that portion. As a result, the volume of the ink chamber corresponding to the vibration of the vibration plate 14 changes, and ink is pushed out from the ink nozzles 15 through the ink path to perform printing.

  The method for manufacturing the piezoelectric material has been described with an example using Pb (lead), La (lanthanum), Zr (zirconia), and Ti (titanium). However, the piezoelectric material to which the present invention is applied is also applied to combinations of other metal species. The body can be manufactured. For example, Bi (bismuth) -Na (sodium) -Ti oxide system, Ba (barium) -Ti (titanium) oxide system, K (potassium) -Na (sodium) -Nb (niobium) oxide system In the same way, oxides of Ca (calcium) -Bi (bismuth) -Ti (titanium) are also manufactured using the manufacturing method of the present invention regardless of the shape of film, lump (bulk) or the like. It is possible.

Hereinafter, the present invention will be described with reference to more specific examples.
Example 1
Zirconia tetra n-butoxide 0.52 mol, titanium n-butoxide 0.48 mol, 1-methoxy-2-propanol 10.0 mol were mixed, and then lead acetate hydrate 1.20 mol and lanthanum acetate hydrate 0.01 mol Were mixed and further heated to compound the raw metal compounds with each other. Next, 3 mol of water, 1.0 mol of acetic acid, and 4.0 mol of ethanol were added to perform a hydrolysis reaction. At that time, 1.0 mol of octylic acid was added. Thereafter, the solvent having a boiling point of 100 ° C. or lower was completely removed by a rotary evaporator, and 1-methoxy-2-propanol was added to prepare a metal oxide concentration of 20 wt%.

This solution was transferred to a petri dish and left to dry at room temperature of 25 ° C. for 4 days. Furthermore, it dried on a 100 degreeC hotplate, and obtained solid content was grind | pulverized and it was set as particle | grains.
The particles are treated with a supercritical fluid of carbon dioxide at a temperature of 35 ° C. and a pressure of 8.10 Pa (80 atm) for 5 minutes.

  The particles treated with the supercritical fluid are molded with a press and fired in an electric furnace at 700 ° C. for 2 hours to obtain the piezoelectric body of the present invention.

Example 2
In Example 1, the supercritically treated particles are fired in an electric furnace at 700 ° C. for 2 hours without being molded by a press machine to obtain the piezoelectric particles of the present invention.

Example 3
In Example 1, the solution was put into quartz glass having a depth of 10 mm, a width of 10 mm, and a length of 20 mm and dried.

  After drying, the solid content (thickness 2.5 mm, width 10 mm, length 20 mm) is taken out of the quartz glass and treated with a supercritical fluid of carbon dioxide at a temperature of 35 ° C. and a pressure of 8.10 Pa (80 atm) for 15 minutes.

Further, the piezoelectric body of the present invention is obtained by firing in an electric furnace at 700 ° C. for 2 hours.
From the measurement of the X-ray diffraction pattern, it was found that perovskite crystals were growing, and a lead titanate zirconate piezoelectric body could be manufactured. The test piece was cut and the X-ray diffraction pattern near the center was measured in the same manner, but there was no difference from the diffraction pattern on the surface.

Example 4
Potassium ethoxide, sodium ethoxide and pentaethoxyniobium corresponding to a metal composition of K / Na / Nb = 0.55 / 0.55 / 1 were mixed in an equal weight mixed solvent of ethanol and 2-methoxyethanol. K and Na were 10% excess of the desired piezoelectric composition. This solution was refluxed at 125 ° C. for 6 hours to obtain a KNN solution.

This solution was dried in quartz glass having a depth of 10 mm, a width of 10 mm, and a length of 20 mm.
After drying, the solid content (thickness 1.8 mm, width 10 mm, length 20 mm) is taken out of the quartz glass and treated with a supercritical fluid of water at a temperature of 400 ° C. and a pressure of 2.33 × 10 ⁷ Pa (230 atm) for 5 minutes. To do.
Further, the piezoelectric body of the present invention is obtained by firing in an electric furnace at 700 ° C. for 2 hours.

Example 5
An embodiment of an ink jet recording head will be described.

  FIG. 3 is a process diagram showing an example of a method for producing an ink jet recording head of the present invention. As shown in FIG. 3A, a part of the back surface is hollowed out into a circle having a diameter of 5 mm (the surface side remains 30 μm in thickness). A film was formed. Next, the piezoelectric body 3 obtained in Example 3 is cut into a diameter of 5 mm, and bonded with a conductive adhesive so that the surface of the cut-out portion is aligned, and an upper electrode 4 is provided to provide a piezoelectric body. An element was obtained (FIG. 3B).

  A nozzle 5 (orifice diameter 100 μm) as shown in FIG. 3C was attached to this piezoelectric element, and an introduction tube 6 for introducing ink was further provided to obtain an ink jet recording head.

Evaluation of Inkjet Recording Head Inkjet ink was introduced from the introduction tube into the inkjet recording head produced above to fill the ink chamber. Next, an AC voltage of 1 to 20 kHz and 150 V was applied between the upper electrode and the lower electrode, and the state of ink ejection was observed with a microscope. As a result, ink droplets could be discharged with good uniformity.

  In addition, the above-described piezoelectric element can be used not only in the piezoelectric element of the ink jet recording head but also in devices such as an ultrasonic motor and a fuel injector.

Comparative Example 1
In Example 3, a piezoelectric material is manufactured in the same manner except that supercritical processing is not performed.
From the measurement of the X-ray diffraction pattern, it was found that not only the perovskite but also a pyrochlore type crystal was grown, and it did not have sufficient performance for use as a piezoelectric body. In particular, the growth of pyrochlore was remarkable in the center.

  Thereafter, the pyrochlore type crystals disappeared and became perovskite by baking at 800 ° C. for 2 hours.

  According to the present invention, in a precursor containing a metal component and an organic component that form a piezoelectric body, the organic component is efficiently removed before crystallization, the firing temperature is lowered, and a highly uniform metal oxide is obtained. It becomes possible to provide a piezoelectric body.

  Further, it can be used for an ink jet recording head using such a highly uniform piezoelectric body.

It is a phase diagram which shows the state of a substance by the relationship between temperature and pressure. 1 is a schematic view showing an embodiment of an ink jet recording head of the present invention. It is process drawing which shows an example of the manufacturing method of the inkjet recording head of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2 Lower electrode 3 Piezoelectric body 4 Upper electrode 5 Nozzle 6 Ink introduction tube 11 Upper electrode 12 Piezoelectric body 13 Lower electrode 14 Vibration plate 15 Nozzle 16 Head base 17 Piezoelectric element

Claims (4)

  In a method for producing a metal oxide obtained by drying and solidifying a solution containing a metal component and an organic component that form a piezoelectric body by metal oxide and heating the solid content at a temperature higher than the crystallization temperature, crystallization is performed. A method for manufacturing a piezoelectric body comprising a step of removing an organic component by contacting with a supercritical fluid before the step of heating to a temperature or higher.   The method for manufacturing a piezoelectric body according to claim 1, wherein the supercritical fluid is water or carbon dioxide in a supercritical state.   3. The piezoelectric body according to claim 1, wherein the metal component forming the piezoelectric body is at least one selected from lead, zirconia, titanium, bismuth, alkali metal, and alkaline earth metal. 4. Production method.   An ink discharge means for discharging ink by vibrating a vibration plate by displacement of a piezoelectric element using a piezoelectric body manufactured by the method according to claim 1 is provided. Inkjet recording head.

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