JP6386291B2 - Manufacturing method of ceramic molded body - Google Patents

Description

  The present invention relates to a method of manufacturing a ceramic molded body that can be applied when manufacturing a ceramic sintered body used for, for example, a plug, a metal halide lamp, an electrostatic chuck, and a dome.

  Conventionally, ceramic parts made of a ceramic sintered body having high performance such as heat resistance and durability have been developed. These ceramic parts can be manufactured by sintering a ceramic molded body obtained by curing and drying a ceramic slurry.

  As a method for producing this type of ceramic molded body, for example, in Patent Document 1, an epoxy resin and an amine-based curing agent are added to a ceramic powder, and the epoxy resin and the amine-based curing agent are cured to obtain a cured wet body. Furthermore, a manufacturing method is disclosed in which a cured product (unsintered ceramic product) is formed by drying the cured wet product at an appropriate humidity to obtain a humidified dry product.

Japanese Patent No. 3692682

  Moreover, in recent years, the castability of slurry into a fine die, particularly a die having a recess of 10 mm or less (molding die), a near-net moldability (moldability to form a product shape without processing), and demolding property. Therefore, there is a demand for a method for producing a ceramic molded body excellent in the above.

  However, in the above-described prior art, the shape of the mold and the characteristics of the slurry necessary for putting into the mold are only described as good fluidity, and the specific shape and viscosity characteristics of the mold are described. , And their relationship has not been fully studied.

  Moreover, there is no description regarding the demoldability of the cured wet body after curing, the hardness of the cured wet body closely related thereto, and the near-net moldability and the warpage of the humidified dry body closely related thereto.

That is, in the above-described conventional technology, a method for producing a ceramic molded body used when producing a ceramic product has not been sufficiently studied.
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a method for producing a ceramic molded body that can easily produce an excellent ceramic product.

(1) In the present invention, as a first aspect, a slurry in which at least ceramic powder, an epoxy resin, and a curing agent are dispersed and mixed is poured into a mold, and the slurry is cured by heating and humidifying to be cured and wet. to prepare a body, the removed said curing a wetting material from the mold, then, a method of manufacturing the ceramic formed structure of the cured wet body is dried at a predetermined humidity to produce a humidifying dried body, the ceramic powder In addition, after 30 seconds after mixing the epoxy resin and the curing agent in a stoichiometric composition to make a mixture, the first viscosity at room temperature when the mixture was measured at a shear rate of 10 s ⁻¹ was 5 Pa · The ratio of the second viscosity at normal temperature to the first viscosity (second viscosity (after 10 minutes) / second) when the mixture was measured at a shear rate of 10 s ⁻¹ after 10 minutes had passed after s. 1 viscosity After 30 seconds)) is equal to or more than 1.3.

In the first aspect, the first viscosity is 5 Pa · s or less when the mixture is measured at a shear rate of 10 s ⁻¹ after 30 seconds using the material as a mixture . Accordingly, since the slurry has a low viscosity and can be easily injected into a fine mold (for example, a mold having a recess having a width of 10 mm or less), defects in which the slurry does not flow are less likely to occur. The shear rate 10 s ⁻¹ corresponds to the shear rate applied when casting is performed in a place where the mold width is 10 mm or less.
Moreover, in this 1st aspect, after 10 minutes passed , the ratio of the 2nd viscosity to the 1st viscosity at the normal temperature when the mixture was measured at a shear rate of 10 s ⁻¹ (second viscosity (after 10 minutes)) / The first viscosity (after 30 seconds) is 1.3 or less. Therefore, the usable time of the slurry, that is, the casting time is long, and the production efficiency is improved.
That is, in the first aspect, since the injection into the fine mold is easy, the defect that the slurry does not flow is less likely to occur, and the time during which the slurry can be cast is long and the production efficiency is improved. Play.
Here, room temperature indicates 25 ° C. (the same applies hereinafter).
Alternatively, the viscosity may be changed by adding a solvent to the slurry to change the viscosity. However, the more the solvent, the greater the shrinkage when producing ceramic parts from the ceramic molded body through the steps of drying, degreasing, and firing, causing cracks. Solvent-free.
The lower limit of the first viscosity is, for example, 1 Pa · s, and the lower limit of the viscosity ratio is, for example, 1 (the same applies hereinafter).
When the first viscosity is less than 1 Pa · s, the ceramic powder tends to settle, so that a density difference occurs between the upper and lower parts of the molded body, and the moldability is lowered. When the viscosity ratio is less than 1, the viscosity decreases with the passage of time, so that the curing reaction is delayed and the moldability is decreased.

(2) As a second aspect of the present invention, the amine value of the curing agent is 100 or more and 200 or less.
In the second aspect, since the amine value of the curing agent is 100 or more and 200 or less, the warpage of the humidified dry body can be easily made 2.0 mm or less, and the rubber hardness of the cured wet body can be made 50 ° or more. . Thereby, it is possible to achieve both high near-net moldability and demoldability.
In addition, when the amine value of a hardening | curing agent is less than 100, since cure shrinkage becomes large, the curvature of a humidified dry body will become large and near net moldability will fall. On the other hand, when the amine value of the curing agent exceeds 200, the addition amount increases in order to add the curing agent to the epoxy resin in a stoichiometric composition, and the viscosity of the slurry increases, resulting in a fine mold. Injection becomes difficult.
The rubber hardness is defined by “JIS K6301 spring type hardness test A type”.
( 3 ) As a third aspect, the present invention is characterized in that alumina is used as the ceramic material of the ceramic powder.
Alumina is the most widely used material as a representative of fine ceramics and has mechanical strength, electrical insulation, (low) high-frequency loss, (high) thermal conductivity, heat resistance, wear resistance, and corrosion resistance. It is good. Therefore, by using alumina, there is an advantage that applicable industrial fields are expanded.

(4) As a fourth aspect of the present invention, the ceramic powder has an average particle size of 1 μm or less.
A dense structure can be obtained by using a fine powder as in the fourth embodiment. This is disclosed, for example, in “Research on imparting arbitrary shape in gel casting molding method: Dr. Koichi Yoshino, Ph.D.
(5) The present invention, as a fifth aspect, is characterized in that the mold has a width of 10 mm or less.
(6) In the present invention, as a sixth aspect, the slurry is added at least to an alumina powder and a dispersant, mixed with an alumina dispersion liquid that has been mixed and dispersed, and further added with a curing agent, It is a mixed slurry.

It is explanatory drawing which shows the state which pours a slurry into a casting mold and makes it harden | cure. It is a graph which shows the relationship between the amine value of Experimental Examples 1-5, and the rubber hardness of a hardening wet body. It is a graph which shows the relationship between the amine number of Experimental Examples 1-5, and the curvature of a humidified dry body.

Hereinafter, embodiments of the present invention will be described.
[Embodiment]
a) First, the manufacturing method of the ceramic molded body of this embodiment is demonstrated.

In the present embodiment, a ceramic molded body was manufactured in the following steps, and then a ceramic sintered body was manufactured from the ceramic molded body.
<Dispersion mixing process>
First, 3.3 g (0 of dispersant): G-700 (manufactured by Kyoeisha Chemical Co., Ltd.) with respect to 660 g of alumina powder (AES-12, Sumitomo Chemical average particle size: 0.57 μm, BET specific surface area: 6.4 m ² / g) 0.5 wt%: outer wt%).

An alumina powder having an average particle size of 1.0 μm or less can be used.
Then, ion-exchanged water was added so that the final water content was 36.6% by volume (total), put into a pot together with boulders, and rotated to mix and disperse.

<Resin mixing process>
Next, 47.3 g of an epoxy resin (EX-313 epoxy equivalent: 141, viscosity: 0.15 Pa · s) manufactured by Nagase ChemteX was added to the alumina dispersion liquid that was dispersed and mixed in the dispersion mixing step, and mixed for 10 minutes.

  Further, various kinds of curing agents (manufactured by T & K TOKA Co., Ltd.) were added in a stoichiometrically necessary amount, further mixed for 2 minutes, and then vacuum degassed for 2 minutes. This completes the slurry.

<Casting and curing process>
Next, as shown in FIG. 1, the slurry (S) is poured into the mold 1, that is, into a metal casting coated with a rectangular (width 5 mm × length 60 mm) fluororesin in plan view, Sealed with an upper mold 2 (manufactured by polycarbonate).

  Thereafter, the slurry was heated and cured under the following conditions, the upper mold 2 was removed, and the cured wet body was taken out from the mold 1. A cured wet body is formed by this curing by heating.

Heat curing conditions: 80 ° C. × 100% RH × 5 h
Temperature increase / decrease rate: 5 ° C / h
Note that RH is relative humidity.

<Drying process>
Next, the cured wet body was dried under the following conditions to prepare a humidified dry body.
That is, the humidity of the cured wet body was gradually lowered and dried under the following humidifying and drying conditions.

Humidification and drying conditions: 80 ° C. × 80% RH × 12 h → 80 ° C. × 60% RH × 12 h → 80 ° C. × 40% RH × 12 h
Temperature increase / decrease rate: 5 ° C / h
Humidity rate: 5% RH / h
<Degreasing process>
Next, the humidified dried body was degreased under the following degreasing conditions to produce a degreased body.

Degreasing conditions: 400 ° C x 2h
Temperature increase rate: 2.5 ° C / h
<Baking process>
Next, the degreased body was fired and sintered under the following firing conditions to produce a ceramic sintered body.

Firing conditions: 1600 ° C x 6h
Temperature increase rate: 25 ° C / h
The manufacturing method described above is a method for manufacturing a ceramic molded body capable of easily manufacturing an excellent ceramic product, as shown in the following experimental examples.

For example, it has excellent effects such as excellent near-net moldability and demoldability, and further excellent fillability into a fine mold, particularly a mold having a place having a width of 10 mm or less.
b) Next, an experimental example performed to confirm the effect of the method for producing a ceramic molded body of the present embodiment will be described.

  In this experimental example, using the curing agent shown in the following Table 1, samples of the present invention (Experimental Examples 1 to 5) were prepared as shown in the following Table 2 by the manufacturing method of the embodiment described above. The characteristics shown in FIG.

  Specifically, the “viscosity”, “viscosity ratio”, “warping of the humidified dry body”, “near net formability”, “rubber hardness of the cured wet body”, “(cured) The “demoldability” and “fillability of (slurry)” were investigated. Moreover, comprehensive evaluation was performed from those results. The results are shown in Table 2.

<Measurement method of viscosity>
The viscosity was measured at normal temperature (25 ° C.) at a shear rate of 10 s ⁻¹ . This shearing speed corresponds to the shearing speed when casting.

Viscosity measuring device: Rheometer (Rheometric Scientific)
Viscosity evaluation method: Couette method Jig dimensions: Bob (φ25mm) / Cup (φ27mm)
Slurry input amount: 8ml
<Measurement method of warpage of humidified dry body>
A sample of the humidified dried body having the following sample shape was prepared. And the curvature was calculated | required using the following measuring apparatus.

Sample shape: φ80mm x T (thickness) 5mm
Using DEGIMICRO STAND (MS-1C, manufactured by Nikon), the thickness of the humidified dried body was measured at five points, and the difference between the maximum value and the minimum value was defined as a warp.

<Near net formability>
A sample of a cured wet body having the following sample shape was produced, and the sample was fired to produce a ceramic sintered body. And the shape of a hardening wet body and a ceramic sintered compact was measured, and the near net moldability was determined.

Sample shape: φ80mm x T (thickness) 5mm
Specifically, the shapes of the cured wet body and the ceramic sintered body were measured, and when the ceramic sintered body was contracted in a similar shape from the cured wet body, ○, and when the deformed and not similar shape was × did.

  In addition, whether it shrunk in a similar shape was determined by measuring two orthogonal diameters (a certain diameter and two diameters perpendicular to the diameter) and thickness with a caliper. That is, when the diameters of two places perpendicular to the ceramic sintered body are equal and the diameter contracts at the same rate as the thickness of the cured wet body, it shrinks in a similar shape. Judged. On the other hand, if the diameters of two orthogonal parts of the ceramic sintered body are not equal, or if the diameter does not shrink at the same rate as the thickness change compared to the diameter of the cured wet body, it will be deformed and similar Judged that it was not in shape.

<Measurement method of rubber hardness>
Using the following rubber hardness meter, a sample of the cured wet body used in the determination of the near net moldability was pressed in the thickness direction, and the rubber hardness was measured.

Rubber hardness tester [Type of TECLOCK: GS-706 (JIS K6301 spring type hardness test A type), measuring range: 0-100 °, scale: 1 °, spring accuracy: ± 8gf (± 1 °)]
<Demoldability>
A cured wet body having the same dimensions was produced using a mold having the following sample shape. And when it was able to take out from a type | mold, without deform | transforming after hardening, it set as (circle) and the case where it was unable to do.

Sample shape: φ50mm x T (thickness) 10mm
<Fillability>
The slurry was filled to a depth of 5 mm in a mold having a width of 5 mm, a length of 60 mm, and a depth of 5 mm. Then, it was cured, demolded, and the filling property was evaluated.

The case where it was filled without a gap was marked as ◯, and the case where the filling was insufficient was marked as x.
<Comprehensive evaluation>
The near-net moldability, demoldability, and filling properties were all marked with ◎, among them, x was one, and x was two.

  In addition, as for the product number of a hardening | curing agent, Experiment Examples 1-4 has shown the product number by T & K TOKA Corporation, and Experiment Example 5 has shown the chemical name.

As is clear from the experimental examples described above, it is obvious that the experimental examples 1 to 5 of the present invention have excellent effects.
(1) Specifically, in Experimental Examples 1 to 5, as a result of evaluating the warpage of the humidified dried body, in Experimental Examples 1 to 4, the warpage was as small as 1.5 mm or less, and the near net formability was good. . On the other hand, in Experimental Example 5, the warp of the humidified dried body was 3.3 mm larger, and the near net moldability was poor.

That is, when the warp is 2 mm or less, it is understood that the near net formability is excellent.
(2) Further, as a result of evaluating the rubber hardness and demoldability of the cured wet body, Experimental Examples 1 to 3 and 5 had good demoldability when the rubber hardness was 59 ° or more. On the other hand, Experimental Example 4 did not have good demoldability. This is because in Example 4, the rubber hardness of the cured wet body was as small as 46 ° and was too soft and collapsed when demolding.

That is, it can be seen that when the rubber hardness is 50 ° or more, the mold release property is excellent.
Therefore, both the near net moldability and the demoldability can be achieved when the humidified dry body has a warp of 2 mm or less and the cured wet body has a rubber hardness of 50 ° or more.

(3) FIG. 2 and FIG. 3 show the relationship between the rubber hardness of the cured wet body and the warpage of the humidified dried body with respect to the amine values of Experimental Examples 1 to 5, respectively.
FIG. 2 shows that when the amine value is high (Experimental Example 4), the rubber hardness of the cured wet body tends to be low. This is presumably because the crosslinking density is lowered when the amine value is high. On the contrary, as shown in FIG. 3, when the amine value is low (Experimental Example 5), it is found that the crosslinking shrinkage becomes too high, so that the curing shrinkage increases. Therefore, when the amine value is low, warpage of the humidified dried body is increased and the near net moldability is lowered.

From these results, it can be seen that the range excellent in both near-net moldability and demoldability is 100 to 200 in terms of amine value.
(4) In addition, the experimental examples 1 to 3 were superior and inferior, and the experimental example 1 was particularly suitable in terms of filling properties. In Experimental Examples 2 and 3, the initial first viscosity is as high as 5 Pa · s or more, and the second viscosity (after 10 minutes) / first viscosity (after 30 seconds)> 1.3. Since the increase in viscosity was large, it is considered that the filling property is lower than that of Experimental Example 1.

In addition, this invention is not limited to the said embodiment and experiment example at all, and it cannot be overemphasized that it can implement with a various aspect in the range which does not deviate from this invention.
(1) For example, as the average particle diameter of the ceramic powder to be used, those having a range of 1 μm or less can be appropriately used.

(2) As the ceramic powder, for example, zirconia can be adopted in addition to alumina.
(3) As the epoxy resin, various resins that can be cured by reacting with a curing agent can be employed. For example, a glycidyl ether type epoxy resin, a glycidyl ester type epoxy resin, a glycidyl amine type epoxy resin, an aliphatic epoxy resin, an alicyclic epoxy resin, or the like can be employed.

  (4) As the curing agent, various curing agents that react and cure with an epoxy resin can be employed. For example, latent curing agents such as primary, secondary, and tertiary amine compounds, polyamide resins, imidazoles, polymercaptan curing agents, acid anhydrides, and dicyandiamide can be employed.

1 ... Mold 2 ... Upper mold S ... Slurry

Claims (6)

A slurry in which at least ceramic powder, an epoxy resin, and a curing agent are dispersed and mixed is poured into a mold, and the slurry is cured by heating while humidifying to produce a cured wet body, and the cured wet body is produced from the mold. taking out the body, then, a method of manufacturing the ceramic formed structure of the cured wet body is dried at a predetermined humidity to produce a humidifying dried body,
30 seconds after mixing the epoxy resin and the curing agent in a stoichiometric composition in addition to the ceramic powder to make a mixture, the mixture was measured at a shear rate of 10 s ⁻¹ at room temperature. The viscosity is 5 Pa · s or less, and after 10 minutes have passed, the ratio of the second viscosity at normal temperature to the first viscosity (second viscosity (10 minutes) when the mixture is measured at a shear rate of 10 s-1 (After) / first viscosity (after 30 seconds)) is 1.3 or less.   The method for producing a ceramic molded body according to claim 1, wherein the curing agent has an amine value of 100 or more and 200 or less.   The method for producing a ceramic molded body according to claim 1 or 2, wherein alumina is used as the ceramic material of the ceramic powder.   The average particle diameter of the said ceramic powder is 1 micrometer or less, The manufacturing method of the ceramic molded body of any one of Claims 1-3 characterized by the above-mentioned. The method for producing a ceramic molded body according to any one of claims 1 to 4, wherein the mold has a width of 10 mm or less. The slurry is a slurry obtained by adding a solvent to at least an alumina powder and a dispersing agent, mixing an epoxy resin in an alumina dispersion liquid that has been mixed and dispersed, and further adding a curing agent and mixing. The manufacturing method of the ceramic molded body of any one of 1-5.