KR100303610B1 - Manufacturing Method of Ceramics Thick Film by Solvent Washing - Google Patents

Abstract

The present invention relates to a method for producing a ceramic thick film in which water is replaced with an organic solvent by preparing a thick film by a tape casting method using water as a solvent and then washing the thick film in an undried state with an organic solvent. The organic solvent used in this method is preferably a solvent which is easily mixed with water, has high hygroscopicity and does not react with the polymer contained in the thick film, and typical examples thereof include ethanol, methanol, acetone, and the like.

By using such a solvent washing method, the drying speed of the ceramic thick film process is improved, and the phenomenon of thick film splitting is greatly reduced, so that various tape casting methods can be converted into water-based water systems in the industrial field. Environmental problems caused by organic solvents will be solved and help improve the working environment.

Description

Manufacturing Method of Ceramics Thick Film by Solvent Washing

The present invention relates to a method for producing a ceramic thick film by an improved water based tape casting method. More specifically, the present invention provides a solvent washing method of replacing the water in the ceramic thick film with another organic solvent by washing with an organic solvent in the process of drying the ceramic thick film passing through the blade in the aqueous tape casting method, which is a typical method for manufacturing a ceramic thick film. It is related with the manufacturing method of the ceramic thick film used.

Tape casting is a widely used method for producing ceramic thick films. In accordance with the trend of thin film thinning in the ceramics industry, ceramic thick films have recently been used in various fields, and tape casting is mainly used for their manufacture. This tape casting method can be classified into two types depending on the solvent used. An aqueous tape casting method using water as a solvent and a non-aqueous tape casting method using an organic solvent as a solvent are examples.

In the past, non-aqueous systems were mainly used in the manufacturing process of tapes in the industrial field. However, non-aqueous systems are not only harmful to the human body, but are also expensive and have to be converted into aquatic systems due to the increasing interest in environmental pollution. have. However, in the case of the water system, many problems arise due to the characteristics of the water. The strong polarity of the water and the high surface energy can cause the dispersibility of the slurry and the cracking of the dried tape, and the low volatilization rate of the water leads to an increase in drying time. Therefore, despite many recent studies on water based tape casting, it has been difficult to apply to industrial sites requiring continuous processes. In order to overcome this problem, studies have been actively conducted to solve the problems of dispersion and drying speed in water-based tape casting. As a result, the problem of dispersion in the aqueous tape casting method has been improved to some extent through the development of various dispersants and binders. On the other hand, in order to increase the drying rate in the water-based tape casting method, it is possible to use a method by heating, in the case of water-based tape breakage phenomenon appears when the drying rate is increased. Therefore, the increase in the drying rate by heating has the disadvantage of not being able to produce a stable tape. In addition, continuous cracking of the tape when the drying temperature is increased makes continuous casting impossible on existing industrial sites. That is, the problem of increasing the drying speed in the water-based tape casting method still remains a problem to be solved.

Thus, the present inventors have conducted a study to increase the drying rate in the water-based tape casting method, as a result of producing a thick film using a tape casting method using water as a solvent and then using an organic solvent for the thick film of the undried state By washing and substituting water with an organic solvent, it has been found that the thick film drying rate can be increased and the present invention has been completed.

It is an object of the present invention to provide a method for producing a ceramic thick film by an aqueous tape casting method, in which the drying rate is increased.

1 is a tape casting process diagram according to the method of the present invention.

FIG. 2 is a graph showing the weight loss of a tape due to volatilization of the solvent, versus drying time, according to Examples 1-3. FIG.

The object of the present invention is achieved by replacing the water with an organic solvent by washing the thick film with an organic solvent in the process of drying the ceramic thick film through a blade after producing a ceramic thick film by tape casting method using water as a solvent. Can be.

That is, the inventors found that the water-based slurry does not split due to an increase in the drying temperature because the amount of water is initially increased after passing through the blade of the tape caster, whereas the water inside the thick film is dried after the water present on the surface is dried. From the beginning, the phenomenon of cracking appeared, which was found to be due to the fact that the surface energy of water is higher than that of other solvents. Therefore, it was found that not only the cracking phenomenon can be suppressed by replacing with a solvent having a low surface energy, but also that the drying rate can be improved when the volatilization rate of the solvent to be substituted is high.

Hereinafter, the present invention will be described in detail with reference to the drawings.

1 shows a tape casting process using a solvent washing method. According to this process chart, first, raw materials powder, solvent water and dispersant are added in the same manner as in the general aqueous tape casting process, and each component is mixed using a method such as ball milling to make a uniform suspension. Polymers such as binders, plasticizers and antifoams are added to the suspension, followed by secondary mixing to prepare a slurry for casting. The prepared slurry is degassed to remove bubbles contained in the slurry and cast in a tape casting apparatus. Subsequently, in the process of drying the thick film passing through the blade, the thick film in the undried state is passed through an organic solvent having high volatility and low surface energy. By using the method of substituting water with another solvent in such a short time, the drying speed is improved and the tape cracking phenomenon is eliminated, so that the thick film can be dried in a sufficiently continuous process in the aqueous tape casting method.

The organic solvent used in this method is preferably a solvent which is easily mixed with water, hygroscopic and does not react with the polymer contained in the thick film. Examples thereof include methanol, ethanol, acetone, benzaldehyde, benzene, benzyl alcohol, n-butyl alcohol, With carbon tetrachloride, cyclohexane, ethyl acetate, ethylene glycol, glycerol, n-hexane, isobutyl alcohol, isopropyl alcohol, methyl ethyl ketone, n-octyl alcohol, propionic acid, n-propyl alcohol, toluene, trichloroethylene, and xylene The group selected from the group which consists of these is mentioned, and typical examples are ethanol, methanol, acetone, etc.

Table 1 shows the characteristics of the various solvents used for tape casting. In the table, water has a surface energy of 72.75 erg / cm ² , ethanol 22.75 erg / cm ² , methanol 22.5 erg / cm ² and acetone 25.1 erg / cm ² . In addition, it can be seen that most of the solvents used for the tape casting have a surface energy value of 20 erg / cm ² . Since these organic solvents are much faster than water in terms of volatilization rate, the drying rate can be improved.

Characteristic Table of Solvents Used in Tape Casting menstruum Surface energy (erg / cm) Dielectric Constant (25 ℃) Viscosity (mPas) Boiling point (℃) Volatilization Rate (g / cm ² / sx10 ⁸ , 25 ℃) Density, D ²⁰ (g / cm ³ ) Acetone 25.1 20.7 0.306 56 5830 0.781 Benzaldehyde 38.5 17.8 179.5 1.05 benzene 28.85 (20 ℃) 2.28 (20 ℃) 0.6.4 Benzyl alcohol 35.5 13.1 5.474 205.2 1.05 n-butyl alcohol 24.60 (20 ℃) 18 2.544 117.7 338 0.81 Butyl butyrate 25.7 166.4 0.872 Carbon tetrachloride 26.95 (20 ℃) 2.24 0.97 (20 ℃) Cyclohexane 25.5 (20 degrees Celsius) 2.02 (20 ° C) 0.894 4487 ethanol 22.75 (20 ℃) 24.3 1.074 78.4 1950 0.789 Ethyl acetate 23.5 6.02 0.423 77.1 4440 0.9 Ethylene glycol 48.4 38.7 16.1 197.2 1.115 Glycerol 63.4 (20 ℃) 42.5 934 290 n-hexane 18.4 1.89 (20 ℃) 0.3 68.7 5560 0.659 Isobutyl alcohol 23.0 (20 degrees Celsius) 15.8 3.096 Isopropyl Alcohol 21.4 18.3 2.038 82.3 1305 0.785 Methanol 22.5 32.63 0.544 64.6 3152 0.789 Methyl ethyl ketone 24.60 (20 ℃) 18.5 (20 ℃) 0.42 (15 ° C) 80 3620 0.805 n-octanoic acid 28 5.02 166.4 0.872 n-octyl alcohol 27.53 (20 ℃) 10.3 7.288 194.5 0.827 Propionic acid 26.7 3.3 141.1 0.993 n-propyl alcohol 23.78 (20 ° C) 20.1 2.26 (20 ℃) 97.2 0.804 toluene 28.5 2.379 0.56 110.6 1900 0.867 Trichloroethylene 3 0.545 87 1.456 water 72.75 78.54 0.89 100 One o-xylene 30.10 (20 ℃) 2.57 (20 ℃) 0.76 144.2 650 0.88

The aqueous thick film tape production method and the effect obtained therefrom by the solvent washing method of the present invention will be more clearly understood from the following examples. Of course, the scope of the present invention is not limited by this embodiment.

<Example 1>

First, a uniform suspension of PZT [Pb (Zr _0.52 Ti _0.48 ) O ₃ ] raw material powder (100 g), water (45 g), antifoaming agent (2-3 drops) and dispersing agent (0.7 cc) was prepared, followed by PVA PZT ceramics slurry was prepared using (4.5 g) as binder and PEG (2 g) as plasticizer. Subsequently, the PZT thick film was prepared by fixing the height of the blade to 0.5 mm, and the film was cut and maintained in ethanol for about 2 minutes, and then dried at room temperature. As a result of drying, the degree of handling was possible within 30 minutes. This result is shown in FIG.

Comparative Example 1

The tape with water not washed in ethanol after casting under the same conditions as in Example 1 was dried after 4 hours. This result is shown in FIG.

<Example 2>

Membrane was prepared and dried according to the same procedure as in Example 1 except that it was maintained in methanol instead of ethanol for about 2 minutes. This result is shown in FIG.

<Example 3>

Membrane was prepared and dried according to the same procedure as in Example 1 except that it was held in acetone for about 2 minutes instead of ethanol. This result is shown in FIG.

<Example 4>

First, a uniform suspension of PZT raw material powder (100 g), water (45 g), antifoaming agent (2-3 drops) and dispersant (0.7 cc) was prepared, followed by PEG (2 g) with PVA (4.5 g) as a binder. ) As a plasticizer to prepare a PZT ceramic slurry. Subsequently, the PZT thick film was prepared by fixing the height of the blade to 0.3 mm, and the film was cut and maintained in ethanol for about 1 minute, and then dried at room temperature. As a result of drying, the degree of handling was possible within 10 minutes.

Comparative Example 2

After casting under the same conditions as in Example 4, the tape with water not washed in ethanol was dried after 5 hours.

Example 5

Membrane was prepared and dried according to the same procedure as in Example 4 except that it was maintained in methanol instead of ethanol for about 1 minute.

Comparative Example 3

The tape with water not washed in methanol after casting under the same conditions as in Example 5 was dried after 5 hours.

<Example 6>

The membrane was prepared and dried according to the same procedure as in Example 4 except that the membrane was kept in acetone for about 1 minute instead of ethanol.

<Comparative Example 4>

After casting under the same conditions as in Example 6, the tape containing unwashed water in acetone was dried after 5 hours.

<Example 7>

The membrane was prepared and dried according to the same procedure as in Example 4 except that the membrane was kept in benzene instead of ethanol for about 1 minute.

Comparative Example 5

After casting under the same conditions as in Example 7, the tape with water not washed in benzene was dried after 5 hours.

<Example 8>

The membrane was prepared and dried according to the same procedure as in Example 4 except that the membrane was kept in carbon tetrachloride instead of ethanol for about 1 minute, and drying to a degree capable of handling was performed within 30 minutes.

Comparative Example 6

After casting under the same conditions as in Example 8, the tape containing unwashed water in carbon tetrachloride was dried after 5 hours.

Example 9

The membrane was prepared and dried according to the same procedure as in Example 4 except that the membrane was kept in cyclohexane instead of ethanol for about 1 minute, and drying to a degree capable of handling was performed within 30 minutes.

Comparative Example 7

After casting under the same conditions as in Example 9, the tape with water not washed in cyclohexane was dried after 5 hours.

In a real industrial field, the drying temperature is high, so it can be dried faster, and drying will be possible within minutes if the optimum drying conditions are selected to handle the dried tape.

According to the method for producing an aqueous thick film of ceramics by the solvent washing method of the present invention, the drying speed of the manufacturing process is improved, and the phenomenon of thick film splitting is significantly reduced. Therefore, in place of the aqueous tape casting method using an organic solvent that is harmful to the human body and causes environmental pollution, the aqueous tape casting method can be applied in a particularly continuous process to industrial sites.

Claims (2)

A method for producing a ceramic thick film by an aqueous tape casting method, wherein the thick film is washed with an organic solvent in the process of drying the ceramic thick film that has passed through the blade. The organic solvent of claim 1, wherein the organic solvent is methanol, ethanol, acetone, benzaldehyde, benzene, benzyl alcohol, n-butyl alcohol, carbon tetrachloride, cyclohexane, ethyl acetate, n-hexane, isobutyl alcohol, isopropyl alcohol, methyl ethyl ketone , n-octyl alcohol, n-propyl alcohol, toluene, xylene.