JPH10305416A - Method for molding non-plastic material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a molding in which a binder is uniformly dispersed. SOLUTION: The method for molding a non-plastic material is equipped with a first step to obtain a body by mixing at least, a water-soluble binder made up of a cellulose derivative, a non-plastic raw material, water and as plasticizer and a second step to mold the body to the desired shape. Further, in the first and the second step, the temperature of the body is set so that it is higher than a temperature at which the water-soluble binder is uniformly dispersed and is not higher than a temperature at which the water-soluble binder is gelled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to clay for use in electronic components such as piezoelectric ceramic components (for example, extrusion molding plastics comprising additives such as ceramic powder, water, organic binders and plasticizers). The present invention relates to a method for molding a non-plastic material.

[0002]

2. Description of the Related Art Conventional binders, ceramic powders,
Water and a plasticizer are mixed, and the clay is formed into a cylindrical shape, a cylindrical shape, or a sheet shape (plate shape) by extrusion molding.

In order to extrude a raw material having no plasticity itself such as ceramic powder, a binder for imparting fluidity is indispensable. As the binder, a cellulose derivative such as methylcellulose or hydroxypropylmethylcellulose is used. Widely used.
Cellulose derivatives have the property of being more soluble in water at lower temperatures, and therefore have been used at lower temperatures when mixed with ceramic materials and when molded.

[0004]

However, according to the above-mentioned method, the viscosity of the clay increases as the temperature becomes lower, so that it is difficult to uniformly disperse the cellulose derivative. It remains as a lump locally. Such a mass remains as a large defect in the ceramic after firing the molded body. Particularly, in the case of a ceramic electronic component or the like, there is a problem that such a defect leads to a decrease in ceramic strength, a decrease in electrical characteristics, and in some cases, a deterioration with time.

Accordingly, an object of the present invention is to provide a molded article in which a binder is uniformly dispersed.

[0006]

In order to achieve this object, a method for molding a non-plastic material according to the present invention comprises the steps of: forming a water-soluble binder comprising at least a cellulose derivative; a non-plastic raw material; water; A first step of mixing the kneaded clay to obtain a kneaded clay, and a second step of forming the kneaded clay into a desired shape. In the first step and the second step, It is characterized in that the temperature is equal to or higher than the temperature at which the water-soluble binder is uniformly dispersed, and is lower than the gelling temperature of the water-soluble binder, thereby suppressing an increase in viscosity of the clay and improving the kneading effect. By doing so, the above object can be achieved.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION According to the first aspect of the present invention, there is provided a method for producing a clay by mixing at least a water-soluble binder comprising a cellulose derivative, a non-plastic raw material, water and a plasticizer. And a second step of forming the kneaded material into a desired shape in the first step and the second step. In the first step and the second step, the temperature of the kneaded material is such that the water-soluble binder is uniform. A method for molding a non-plastic material, wherein the temperature is not lower than the dispersing temperature and lower than the gelling temperature of the water-soluble binder, and a molded article in which the water-soluble binder is uniformly dispersed can be obtained.

According to a second aspect of the present invention, there is provided the method for molding a non-plastic material according to the first aspect, wherein the temperature at which the water-soluble binder is uniformly dispersed is 10 ° C. or more. Can be obtained.

According to a third aspect of the present invention, there is provided the molding of the non-plastic material according to the first aspect, wherein the plasticizer is at least one of ethylene glycol, triethylene glycol, tetraethylene glycol, glycerin, and derivatives of these glycol compounds. It is a method that improves the fluidity of the kneaded material, prevents the temperature of the kneaded material from rising due to frictional heat,
It is possible to obtain a molded body having moderate flexibility and easy processing.

According to a fourth aspect of the present invention, in the second step, one of screw-type extrusion, piston-type extrusion, and roll-formation or a combination of two or more thereof is used as a molding method. Item 1. A method for molding a non-plastic material according to Item 1, wherein a molded article in which a water-soluble binder is uniformly dispersed can be obtained.

The invention according to claim 5 is the non-plastic material according to claim 1, wherein the cellulose derivative is at least one selected from water-soluble cellulose compounds such as methylcellulose, hydroxypropylmethylcellulose and hydroxyethylmethylcellulose. The molding method of the present invention can improve the fluidity of the clay and obtain a molded body with improved strength.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. (Embodiment 1) FIG. 1 is a characteristic diagram showing the relationship between the temperature and hardness of a kneaded material in the present embodiment.

First, 10 parts by weight of a hydroxypropylmethylcellulose as a water-soluble binder, 5 parts by weight of glycerin as a plasticizer, and 14 parts by weight of water are added to 100 parts by weight of a non-plastic piezoelectric ceramic material powder and mixed. Obtain kneaded clay.

Next, the kneaded clay is stored (aged) in a refrigerator at a temperature of 5 ° C. for 12 hours, and then the equipment is cooled by a vacuum kneading machine so that the temperature of the kneaded clay is in a range of 15 ° C. to 20 ° C. While mixing (kneading).

Next, the kneaded material is cooled by a screw-type vacuum extruder with a device having a width of 100 mm and a thickness of 50 mm while cooling the equipment so that the temperature of the kneaded material is in the range of 15 ° C. to 20 ° C.
It was formed into a 0 μm sheet. Cooling of the vacuum kneader and the vacuum extruder was performed by passing cooling water having a water temperature of 8 ° C. through the barrel of the equipment and the inside of the screw.

The sheet-like molded body thus formed was punched into a predetermined shape, the binder was removed in an electric furnace, and then fired to obtain a ceramic thin plate. Next, this ceramic thin plate was polished to a thickness of 300 μm, and was 7 mm wide and 20 mm long.
It was processed into a rectangular shape of mm to obtain a sample for strength measurement, and a strength test was performed by a three-point bending method.

FIG. 1 shows the relationship between the temperature and the hardness of the clay. The hardness of the kneaded clay was evaluated using a clay hardness meter manufactured by Nippon Insulators.

FIG. 1 shows that when the temperature of the clay is less than 10 ° C., the viscosity of the clay rapidly increases due to an increase in viscosity.

At 55 ° C. or higher in FIG. 1, the cellulose derivative as a binder gels, and the clay hardness sharply increases.

Therefore, during kneading and molding, it is preferable to control the temperature of the kneaded material to be not less than 10 ° C. at which the cellulose derivative as a water-soluble binder is uniformly dispersed and less than the gelling temperature of cellulose.

(Embodiment 2) The temperature of the clay is 20 ° C. to 3 ° C.
Except that the temperature is controlled at 0 ° C., a sheet-shaped molded body having the same shape is prepared in the same process as in (Embodiment 1), and baked and processed in the same manner to obtain a sample having the same shape as (Embodiment 1). It was prepared and subjected to a three-point bending strength test.

(Comparative Example 1) As Comparative Example 1, kneading and molding were performed in the same manner as in (Embodiment 1) except that the temperature of the kneaded clay was controlled at 2 ° C to 7 ° C to form a molded body. A sample for a three-point bending test was prepared in the same manner as in (Embodiment 1), and a strength test was performed.

(Comparative Example 2) As Comparative Example 2, when kneading and molding were performed by flowing hot water through equipment so that the temperature of the kneaded material was close to the gelling temperature of hydroxypropylmethylcellulose (about 55 ° C). On the other hand, the kneaded material hardness rapidly increased due to the gelation of hydroxypropylmethylcellulose, and the temperature increased remarkably due to frictional heat, and the kneading and shaping could not be performed because of the evaporation of the moisture in the kneaded material.

With respect to the molded articles of (Embodiment 1), (Embodiment 2) and (Comparative Example 1), undissolved hydroxypropylmethylcellulose was stained with an ethanol solution of methylene blue and observed with a microscope. The results are shown in (Table 1).

[0025]

[Table 1]

Further, the results of the strength tests performed on the fired and processed samples by the three-point bending method are shown in Table 1 together.

Further, in each of the above embodiments and the comparative example, when comparing the current value of the motor of the vacuum kneader as a measure of the load applied to the equipment, in the first embodiment, 3 amps, In the case of mode 2), the current was 2.5 amps, but in the case of (comparative example 1), the current significantly increased to 7 amps. In Comparative Example 2, the rated value of the equipment is 1
Because it exceeded 0 amps and the clay did not come out,
The experiment was interrupted.

As is evident from Table 1, in the sheet-like molded article prepared by kneading and extruding the kneaded clay at 10 ° C. or more and below the gelling temperature of the cellulose derivative according to the present invention, the dispersion of the cellulose derivative is sufficient. Performed, no undissolved cellulose derivative is seen.

For this reason, in the ceramic piezoelectric element obtained by sintering the compact, no defect such as large pores of 30 μm or more was observed inside, and the strength of the comparative sample (Comparative Example 1) prepared by the conventional method was not increased. It is improved as compared with (Comparative Example 2).

Further, since the load on the equipment can be significantly reduced, a great effect can be obtained in molding the ceramic material.

In (Embodiment 1) and (Embodiment 2), a vacuum kneader using piezoelectric ceramic material powder as a non-plastic material, hydroxypropylmethyl cellulose as a water-soluble binder, and glycerin as a plasticizer is used. The kneaded clay was produced by using the above method, and the molding was performed using a screw type vacuum extrusion molding machine, but the same effect can be obtained as follows.

(1) As the non-plastic material, alumina, ferrite material, ceramic material and the like are also used.

(2) Instead of hydroxypropylmethylcellulose as the water-soluble binder, one of water-soluble cellulose compounds such as methylcellulose, hydroxypropylmethylcellulose and hydroxyethylmethylcellulose or a combination of two or more thereof is used.

(3) Instead of glycerin, at least one derivative of a glycol compound such as ethylene glycol, triethylene glycol or tetraethylene glycol or a combination of two or more thereof is used as the plasticizer.

(4) Mixing (kneading) is performed using a three-roll mill. (5) For molding, not only a screw type extruder, but also a piston type extruder or a roll extruder is used. Further, the shape of the molded body is not limited to the sheet shape, but may be a cylindrical shape or a cylindrical shape.

If the temperature of the clay at the time of kneading and extrusion exceeds 30 ° C., the temperature rises at an accelerated rate due to an increase in frictional heat, and it becomes difficult to control the temperature to an appropriate temperature. Is more preferably 10 ° C. or more and 30 ° C. or less.

Further, the optimum hardness of the clay for extrusion molding depends on the equipment, but is preferably about 2 to 13 as measured by a clay hardness meter manufactured by Nippon Insulator.

Further, by using the molded articles prepared in (Embodiment 1) and (Embodiment 2),
A ceramic piezoelectric element having high strength even after firing and having no internal structural defects can be obtained.

The same effect can be obtained not only for the ceramic piezoelectric element, but also for a ceramic electronic component which is required to have no strength and no internal structural defects such as a capacitor, a varistor, and a thermistor.

The present invention is applicable not only to ceramic electronic parts but also to electronic parts using ferrite, alumina substrates, and the production of alumina resistance bars.

[0041]

According to the present invention, a molded article in which a water-soluble binder is uniformly dispersed can be obtained.

By firing this molded body, a sintered body having high strength and free from internal structural defects can be obtained. Without any significant deterioration.

[Brief description of the drawings]

FIG. 1 is a characteristic diagram showing a relationship between temperature and hardness of kneaded clay in one embodiment of the present invention.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08L 1/00 C09J 101/28 C09J 101/28 C04B 35/00 108

Claims (5)

[Claims] 1. A first step of mixing a water-soluble binder comprising at least a cellulose derivative, a non-plastic raw material, water and a plasticizer to obtain a clay, and then forming the clay into a desired shape. And the second step, wherein the temperature of the clay is equal to or higher than a temperature at which the water-soluble binder is uniformly dispersed and lower than a gelling temperature of the water-soluble binder in the first step and the second step. A method for molding a non-plastic material, characterized in that: 2. The method for molding a non-plastic material according to claim 1, wherein the temperature at which the water-soluble binder is uniformly dispersed is 10 ° C. or higher. 3. The method for molding a non-plastic material according to claim 1, wherein the plasticizer is at least one of ethylene glycol, triethylene glycol, tetraethylene glycol, glycerin, and derivatives of these glycol compounds. 4. The method of claim 1, wherein in the second step, the method of forming the clay is one of screw extrusion, piston extrusion, and roll molding, or a combination of two or more thereof. Molding method of non-plastic material. 5. The cellulose derivative is at least one selected from water-soluble cellulose compounds such as methylcellulose, hydroxypropylmethylcellulose and hydroxyethylmethylcellulose.
3. The method for molding a non-plastic material according to 1.).