KR101594541B1 - Method for preparing ceramic sheet, ceramic complex sheet, and releasing agent for preparing ceramic sheet - Google Patents

Abstract

The present invention relates to a method of laminating and baking various ceramic sheets including ferrite sheets in a large quantity. According to the present invention, environment friendly ceramic sheets can be manufactured by using a dispersion including ceramic powder with an average aspect ratio (A/R) of 2 to 5 as a releasing agent. In addition, the ceramic sheets of the present invention have excellent releasing properties between the ceramic sheets, thereby being useful for applying to various sintered ceramic sheets including sintered ferrite sheets. The preparation method of the present invention comprises the steps of: (a) preparing at least two green ceramic sheets; (b) applying the releasing agent to at least one side of each of the green ceramic sheets; (c) laminating the ceramic sheets so as to have the surface with a releasing agent applied come in touch with the other green sheet; and (d) heat-treating the laminated green ceramic sheets.

Description

Technical Field [0001] The present invention relates to a ceramic sheet, a ceramic composite sheet, and a release agent for use in the production of a ceramic sheet. BACKGROUND OF THE INVENTION 1. Field of the Invention [0001]

The present invention relates to a method for producing a ceramic sheet by laminating and firing a large amount of various ceramic sheets including a ferrite sheet, a ceramic composite sheet, and a release agent for producing a ceramic sheet.

Ceramic sheets have been used as materials for various fields including electronic devices due to their excellent heat resistance and insulating properties. As an example, ferrite sheets have excellent magnetic characteristics in addition to the inherent characteristics of ceramics, and are used for the purpose of absorbing electromagnetic waves radiated or intruding into electronic devices.

Various ceramic sheets including a ferrite sheet are used as a sintered body subjected to a sintering process. For the sintering process, the raw material powder of the ceramic sheet is appropriately mixed with a binder, a plasticizer and a solvent to form a sheet, and then sintered at high temperature on a plate such as an alumina material often called a setter See Patent Registration No. 10-0218839).

Such a firing process is very inefficient when the ceramic sheet is performed one sheet at a time. Therefore, in order to fuse a large amount of ceramic sheets at one time, a plurality of ceramic sheets are laminated and fired. However, in this case, there is a problem that the stacked ceramic sheets stick together during the high-temperature firing process.

In order to solve this problem, there has been developed a method of laminating a ceramic sheet having a roughness at the time of laminating the ceramic sheet. However, in this case, when the ceramic sheets are stacked in three or more sheets of 100 탆 or less and fired, There is a problem of sticking to each other.

Japanese Patent No. 3,865,363 discloses a method for forming a coating film by applying powder on a setter in order to prevent fusion of a setter and a sintered body during sintering. However, this method has a disadvantage in that a separate coating film must be formed to complicate the process and increase the product cost.

[Patent Document 1] Korean Patent Registration No. 10-0218839

[Patent Document 2] Japanese Patent No. 3,865,363

Accordingly, an object of the present invention is to provide a process for producing an eco-friendly ceramic sheet excellent in releasability without affecting the physical properties of the ceramic sheet even after firing.

Another object of the present invention is to provide a release agent for use in the production of ceramic sheets.

Still another object of the present invention is to provide a ceramic composite sheet including the above ceramic sheet.

In order to achieve the above object,

(a) preparing two or more ceramic green sheets;

(b) applying a release agent to at least one surface of each ceramic green sheet;

(c) stacking the two or more ceramic green sheets so that the surfaces of the ceramic green sheets coated with the release agent are in contact with other ceramic green sheets; And

(d) heat treating the laminated ceramic green sheets,

Wherein the mold release agent comprises a ceramic powder having an average aspect ratio (A / R) of 2 to 5.

To achieve these and other objects, the present invention provides a release agent for the production of ceramic sheets, comprising ceramic powders having an average A / R of 2 to 5.

According to another aspect of the present invention, there is provided a ceramic sheet comprising a ceramic sheet on which a mold release agent composed of ceramic powder having an average A / R of 2 to 5 is dispersed on at least one side; And a polymer film layer formed on at least one side of the ceramic sheet.

According to the present invention, by using a release agent comprising a ceramic powder having an average A / R of 2 to 5, an eco-friendly ceramic sheet excellent in releasability between ceramic sheets and a laminated body thereof can be produced. It is useful in various sintered ceramic sheet fields.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 shows a process for producing a ceramic sheet and a ceramic sheet laminate according to an example of the present invention.
2 is a cross-sectional view of a ceramic sheet laminate according to an example of the present invention.
3 (A) is an SEM image of a general alumina powder and (B) is an SEM image of an alumina powder having an average A / R of 2 to 5. FIG.

Manufacturing method of ceramic sheet

The method for producing a ceramic sheet according to the present invention comprises the steps of: (a) preparing two or more ceramic green sheets; (b) applying a releasing agent to at least one surface of the ceramic green sheet; (b) applying a release agent to at least one surface of each ceramic green sheet; (c) stacking the two or more ceramic green sheets so that the surfaces of the ceramic green sheets coated with the release agent are in contact with other ceramic green sheets; And (d) heat treating the laminated ceramic green sheet, wherein the mold release agent comprises a ceramic powder having an average aspect ratio (A / R) of 2 to 5.

The present invention is characterized in that after step (c), the laminated ceramic green sheet is fired and then separated to obtain a sintered sheet, And forming a polymer film layer on one side or both sides of the obtained sintered sheet.

Hereinafter, the method for producing the ceramic sheet of the present invention will be described in detail.

In this specification, where an element is described as being formed "on" or "under" another element, the terms "directly" or " Indirectly "formed < / RTI >

(a) Preparation of ceramic green sheet

This step is a step of preparing two or more ceramic green sheets to be laminated.

The ceramic green sheet used in this step includes all kinds of sheets including ceramic components, and is not particularly limited, but may be, for example, a fired ceramic sheet.

As an example, the ceramic green sheet may be a ceramic sheet having magnetism. As a preferred example, the ceramic green sheet may be a ceramic sheet containing a ferrite-based component such as Ni-Cu-Zn-based, Ni-Zn-based, Mg-Zn-based or Mn-Zn-based ferrite. In this case, the ceramic sheet may further contain a magnetic component other than the ferrite component, for example, permalloy, sendust and the like.

The ceramic green sheet can be produced by molding a solution containing a ceramic raw material powder into a sheet form and drying it. For example, the ferrite powder may be appropriately mixed with a binder, a plasticizer and a solvent, and then molded into a ferrite green sheet by a process such as tape casting.

The ceramic green sheet may be a thin film or a thick ceramic sheet, and the thickness is not particularly limited. For example, the ceramic sheet may have a thickness of 40 [mu] m to 1,000 [mu] m.

(b) Application and drying of release agent

This step is a step of applying and drying the release agent on at least one side of each of the ceramic green sheets prepared above.

<Release Agent>

In the present invention, the release agent comprises a ceramic powder having an average A / R of 2 to 5, preferably 2.5 to 4. SEM photographs of general alumina powders and alumina powders having an average A / R of 2 to 5 are shown in FIGS. 3 (A) and 3 (B).

According to the present invention, the shape of the ceramic powder is spherical particles, that is, particles having a high average A / R ratio in the longitudinal / transverse direction, that is, an average A / R of 1 or more, 2 to 5, more preferably 2.5 to 4, increases the layered property of the sheet and increases the degree of separation between the sheets after firing, thereby improving the productivity and reducing the amount of defective sheets after sintering.

According to the present invention, when the releasing agent contains a ceramic powder having an average A / R of 2 to 5, the amount of the A / R is greater than that of the ceramic green sheet existing up / It is possible to prevent the phenomenon of adhesion after the heat treatment because of a small contact area. On the other hand, when the A / R ratio exceeds 5, the release agent is oriented horizontally and the longer axis direction lies horizontally, which leads to an increase in the contact area, thereby reducing the sheet-to-sheet spacing.

Thus, the release agent of the present invention preferably comprises a ceramic powder having an average A / R of 2 to 5, preferably 2.5 to 4, rather than spherical particles.

The ceramic powder may be a ceramic powder of a different component (different kind) from the ceramic green sheet or a ceramic powder of the same kind. More preferably, the ceramic powder may be a ceramic powder which does not react with the ceramic green sheet. For example, the ceramic powder may include at least one kind of ceramic powder that does not react with the ceramic sheet. For example, the ceramic powder may be selected from the group consisting of alumina, tungsten, magnesia, zirconia, graphite, have. As an example, when the ceramic sheet is a ferrite sheet, the ceramic powder may be an amorphous alumina powder.

At this time, the ceramic powder may have an average particle diameter (d ₅₀ ) of 3 탆 to 10 탆. If the ceramic powder has an average particle diameter of less than 3 占 퐉, the releasing property is not good, and if the ceramic powder has an average particle diameter of more than 10 占 퐉, the releasing agent may not be removed after baking. More specifically, the ceramic powder may have an average particle diameter (d ₅₀ ) of 3 탆 to 5 탆. Here, the average particle size d ₅₀ means a particle size corresponding to 50% of the weight percentage in the particle size distribution curve.

On the other hand, the release agent of the present invention can be used after dispersing the ceramic powder in a solvent.

The solvent may be selected depending on the composition of the green sheet. For example, the solvent may be selected from the group consisting of water, ethanol, toluene, ethylene glycol (EG), triethylene glycol (TEG), polyethylene glycol (PEG), and polyvinyl alcohol It is not.

According to one embodiment of the present invention, when a ferrite green sheet such as a Ni-Zn-Cu system, a Ni-Cu system, a Ni-Zn system or a Mn-Zn system is used as the ceramic green sheet, water or ethanol By using the ceramic powder dispersed in the solvent, it is possible to maintain a clean surface state even after firing without melting the ferrite green sheet before firing.

In the present invention, the releasing agent may include the solvent and a ceramic powder having an average A / R of 2 to 5 in a weight ratio of 10: 1 to 200: 1. More specifically, the releasing agent may include the solvent and a ceramic powder having an average A / R of 2 to 5 in a weight ratio of 50: 1 to 150: 1.

<Application of release agent>

The method of applying the releasing agent onto the ceramic green sheet is not particularly limited.

As a preferred example, the application of the release agent may be performed by spraying the release agent onto the ceramic green sheet.

For example, the mold release agent may be charged into the injector and the mold release agent may be injected onto the ceramic green sheet at an appropriate pressure and height.

At this time, the jetting height of the release agent may be 100 to 500 mm, more specifically 150 to 250 mm. The injection pressure of the release agent may also be 0.5 to 5.0 bar, more specifically 1.0 to 2.0 bar. Further, the injection angle of the releasing agent may be 20 ° to 80 °, more specifically 40 ° to 60 °. Herein, the injection angle means the angle between the locus of the release agent injected from the nozzle inlet and the vertical line when a virtual vertical line descending on the sheet surface from the nozzle inlet is referred to.

As an example, the injection may be performed while the ceramic sheet is (lower) transported below the stationary injector (top). At this time, the conveying speed of the ceramic sheet may be 1 to 10 m / min, more specifically 4 to 8 m / min.

When spraying is performed in the above range of conditions, it is more advantageous to maintain the characteristics of the ceramic sheet after injection of the release agent. Particularly, when the ceramic green sheet is a ferrite sheet, it is more advantageous to maintain magnetic properties such as magnetic permeability under the above-described range.

<Drying step>

Each ceramic green sheet previously coated with the release agent can undergo a drying process.

The solvent in the release agent applied on the ceramic sheet can be removed through the drying step.

The drying method is not particularly limited, and natural drying, hot air drying, heat drying, and NIR drying are all possible. In addition, the drying time is not particularly limited, and the time for removing all the water as the solvent is sufficient. As an example, the drying may be performed by a hot air drying method at a temperature of 70 to 90 DEG C for a time of 3 seconds to 30 seconds. NIR drying can be carried out at a temperature of 70 [deg.] C to 90 [deg.] C for a time of 1 second to 10 seconds.

&Lt; Specific Example of Coating and Drying Process of Release Agent >

1 shows a manufacturing process of a ceramic sheet laminate according to an example of the present invention. The size of each component in the drawings may be exaggerated for clarity and may differ from the size actually applied.

Referring to FIG. 1, the ceramic green sheet 10 is sequentially fed through the feeding zone 100, the jetting zone 200, and the drying zone 300 while being conveyed by the conveying unit 50.

First, the ceramic green sheet 10 is placed on the conveying means 50 in the feeding zone 100 and conveyed at a constant speed.

The ceramic green sheet 10 is transferred to the injection zone 200. The spray zone (200) has an injector (210) at the upper end thereof. The injector 210 is charged with a release agent composed of ceramic powder dispersed in water. The injector 210 injects the release agent onto the ceramic green sheet 10 at an appropriate injection pressure.

Thereafter, the ceramic sheet 10 is conveyed to the drying zone 300. The drying zone 300 may comprise drying means and / or heating means. The release agent applied on the ceramic green sheet 10 is removed from the solvent as the solvent passes through the drying zone 300, leaving only the ceramic powder 20 having an average A / R of 2 to 5. The dried ceramic green sheet 10 is conveyed for lamination.

The injection zone 100 may have a length of 300 mm, the injection zone 200 may have a length of 300 mm, the drying zone 300 may have a length of 400 mm, and the width of the conveying unit 50 may be 400 mm.

(c)

This step is a step of laminating two or more ceramic green sheets dried earlier to produce a laminate of ceramic green sheets. At this time, it is necessary to laminate the surface of the ceramic green sheet coated with the releasing agent so as to be in contact with the other ceramic green sheets.

As a result, the ceramic powder previously applied is present between the layers of the ceramic green sheet.

The ceramic green sheet may be laminated with 2 to 40 sheets, preferably 5 to 30 sheets.

In the steps (b) and (c) of the present invention, the coating, drying and laminating may be sequentially and repeatedly performed one by one by a ceramic green sheet.

(d) Sintering step

After the above drying step, a baking step may be added.

Through the present firing step, the previously prepared laminated ceramic green sheet can be produced as a sintered ceramic sheet laminate.

The conditions of the firing process can be adjusted depending on the components of the ceramic sheet, and are not particularly limited. For example, when the ceramic green sheet is a ferrite sheet, the firing step is firstly carried out at a heating rate of 2 to 5 ° C / minute to a temperature of 25 ° C to 450 ° C and then held for 1 to 5 hours to burn the binder Followed by raising the temperature to 450 ° C to 970 ° C at a heating rate of 1 to 5 ° C / min and then maintaining the temperature for 1 to 3 hours.

The ceramic sheet laminate

After the above steps, a laminated ceramic sheet can be obtained.

1 and 2 schematically show a ceramic sheet laminate according to an example of the present invention. 1 and 2, the ceramic sheet laminate 11 includes a laminate of two or more ceramic green sheets 10, and a laminate of two or more ceramic green sheets 10, 5 ceramic powder (20).

In the sintered ceramic sheet laminate 11 of the present invention, when water is used as a solvent for the release agent, no reaction occurs between the release agent and the ceramic green sheet 10 before and after the firing, They can be easily separated without sticking to each other, and the surface of the ceramic sheet can be maintained in a clean and smooth surface state even after firing. Accordingly, when the ceramic sheet is a ceramic sheet having magnetism, the magnetic characteristics before firing can be maintained as it is after firing.

(e) Polymer resin layer forming process

After separating the sintered ceramic sheet laminate obtained in the previous step, a flexible polymer film layer may be formed on one side or both sides of the separated sintered ceramic sheet.

The step of forming the polymer film layer may be a method of laminating a previously formed flexible film, or a method of coating a raw material resin of a film on a ceramic sheet followed by drying.

The flexible film may be any polymer film having flexibility. Examples of the flexible film include polyethylene terephthalate (PET), polyethylene (PE), polyimide (PI), polycarbonate (PC) Can be a film that contains.

Further, in order to secure the adhesiveness, an adhesive layer or an adhesive layer such as an acrylic PSA, a silicone PSA or the like may be formed on one side or both sides of the flexible film and then laminated.

Accordingly, the present invention provides a ceramic sheet comprising a ceramic sheet on which a mold release agent composed of a ceramic powder having an average A / R of 2 to 5 is dispersed on at least one side; And a polymeric film layer formed on at least one side of the ceramic sheet.

Example

Hereinafter, the present invention will be described in more detail by way of examples. However, the following examples are illustrative of the present invention, and the present invention is not limited to the following examples.

Manufacturing example : Preparation of mold release agent

Amorphous alumina powder having an average A / R and an average particle diameter (d ₅₀ ) shown in Table 1 below was mixed with distilled water at a weight ratio of 1: 100, followed by ultrasonic dispersion to prepare Releasing Agents 1 to 6.

The average A / R shows an average value of the ratio (length / short length of the major axis) of the major axes and minor axes of 30 particles after obtaining an SEM photograph of the alumina powder. The average particle diameter (d ₅₀ ) PSA (Particle Size Analyzer, Malvern, Mastersizer 3000).

Average A / R Average particle diameter (d ₅₀ ) Release Agent 1 3.3 3.9 탆 Release Agent 2 2.1 6.8 탆 Release Agent 3 2.8 5.9 탆 Release Agent 4 4.3 3.2 탆 Release Agent 5 1.2 5.5 탆 Release Agent 6 5.5 3.3 탆

Example 1: Production of ceramic sheet

(1) Production of ceramic green sheets

Ni-Cu-Zn ferrite produced by Gimix Co., Ltd. was used as a ceramic powder, and a slurry was prepared by using a synthetic binder (BKY-2155, BYK Company) in which a binder, a plasticizer and a solvent were appropriately blended. The slurry prepared by mixing the Ni-Cu-Zn ferrite and the total binder at a weight ratio of 60:40 and dispersing the mixture in a basket mill for 5 hours was cast into a 60 탆 thick ferrite green 20 sheets were prepared.

(2) Spraying and drying of the release agent

The water dispersing mold release agent 1 prepared above was charged into a sprayer having a height of 200 mm on the top. The release agent was sprayed onto the ferrite green sheet from the sprayer while the green sheet prepared in the step (1) was placed on a transfer device with a spray nozzle and transferred at a speed of 10 m / min. At this time, the spraying conditions were a spray angle of 40 ° and a spray gas pressure of 2 bar. Thereafter, the release agent sprayed on the green sheet was left for about 3 seconds until the water as a solvent was dried to obtain a green sheet coated with alumina powder.

(3) Laminating process

In step (2) above, the green sheets coated with alumina powder were laminated such that the surface of one green sheet coated with alumina powder was in contact with the other green sheets, and laminated so that the alumina powder was inserted between the green sheet layers , And finally, 20 sheets of green sheets were laminated.

(4) Firing process

The laminate obtained in the above step (3) was fired. Specifically, the temperature was raised to 450 ° C at a temperature raising rate of 0.5 ° C / minute, and the resultant was heat-treated at 450 ° C for 5 hours to burn out the binder. Then, the temperature was raised to 960 ° C at a rate of 3 ° C / Sintering reaction between ferrite powders was carried out.

The ferrite sintered sheet was separated from the sintered laminate. The ferrite sintered sheet was divided into 20 pieces out of 20 pieces. The thickness of each of the ferrite sintered sheets was 58 탆, and the permeability and investment loss were 163 and 3.1.

(5) Polymer film layer formation and roll lamination process

A PET film (thickness: 10 占 퐉) having an adhesive layer formed on one side of the ferrite sintered sheet obtained in the step (4) and a double-sided tape (adhesive component (thickness: 10 占 퐉) , Except for release paper (thickness: 78 占 퐉)) was placed and placed on a double-sided roll laminator. Then, the laminated ferrite sintered sheet was passed between a rubber plate and a press roll of a double-sided roll laminator. The interval between the rubber plate and the roll was adjusted to 1 mm and the roll lamination process was carried out at a rate of 1 m / min while applying a pressure of 2.2 MPa Respectively.

Examples 2 to 4: Preparation of ceramic sheet

A ceramic sheet was prepared in the same manner as in Example 1 except that the release agents 2 to 4 containing alumina powder having an average A / R of 2.1, 2.8 and 4.3 were used, respectively, as shown in Table 1 above.

Example 5: Production of ceramic sheet (using organic solvent dispersion release agent)

A ceramic sheet was prepared using the release agent prepared by performing the same procedure as in Example 1, except that the solvent of the release agent was dispersed in ethanol instead of water.

Comparative Examples 1 and 2: Preparation of ceramic sheet

As in Table 1, except that a release agent 5 containing an alumina powder having an average A / R of 1.2 and a release agent 6 comprising an alumina powder having an average A / R of 5.5 were used, respectively, To prepare a ceramic sheet.

Test Example 1: Evaluation of releasability of sintered ceramic laminate

The sintered ceramic sheet laminate produced in Examples 1 to 5 and Comparative Examples 1 and 2 was separated into individual ceramic sheets to evaluate the releasability (sheet separability).

The thickness, permeability, and investment loss result of the ferrite sintered sheet separated from the laminate are shown in Table 2 below.

Thickness (㎛) Investment ratio Investment loss Dissimilarity (sheet separation degree) Example 1 58 163 3.1 20 sheets of 20 sheets Example 2 98 154.4 3.62 17 out of 20 sheets Example 3 100 149.5 2.22 20 sheets of 20 sheets Example 4 142 146.3 2.34 17 out of 20 sheets Example 5 215 172 3.93 18 sheets of 20 sheets Comparative Example 1 60 159.5 2.7 2 out of 20 Comparative Example 2 59 158.2 2.4 4 out of 20

As a result, the sintered ceramic sheet laminate of Examples 1 to 5 using the release agent in which the alumina powder having an average A / R of 2 to 5 was dispersed in water or ethanol did not stick to each other so that the ceramic sheets were easily separated, Which means that no reaction occurred between the ceramic sheets during firing.

On the other hand, in the ceramic sheet of Comparative Example 1 using the release agent 5 in which alumina powder having an average A / R of 1.2 was dispersed in water, only two sheets of 20 sheets were separated and the alumina powder having an average A / R of 5.5 was dispersed in water Of the ceramic sheet of Comparative Example 2 using the release agent 6 having the release agent 6, only 4 of the 20 sheets were separated and the releasability was not good.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, It is to be understood that the invention may be practiced within the scope of the appended claims.

10: Ceramic green sheet
11: Ceramic sheet laminate
20: ceramic powder having an average A / R of 2 to 5
50: conveying means
100: input zone
200: injection zone
210: Injector
300: Dry zone

Claims (14)

(a) preparing two or more ceramic green sheets;
(b) applying a release agent to at least one side of each of the ceramic green sheets;
(c) stacking the two or more ceramic green sheets so that the surfaces of the ceramic green sheets coated with the release agent are in contact with other ceramic green sheets; And
(d) heat treating the laminated ceramic green sheets,
Wherein the mold release agent comprises ceramic powder having an average aspect ratio (A / R) of 2 to 5,
Wherein the ceramic powder has an average particle diameter (d ₅₀ ) of 3 to 10 占 퐉.
The method according to claim 1,
Wherein the ceramic powder has an average A / R of from 2.5 to 4.
The method according to claim 1,
Wherein the ceramic powder is a heterogeneous ceramic powder which does not react with the ceramic green sheet.
delete The method according to claim 1,
Wherein the releasing agent comprises a solvent and a ceramic powder having an average A / R of 2 to 5 in a weight ratio of 50: 1 to 150: 1.
The method according to claim 1,
Wherein in step (a), the ceramic green sheet is produced by forming a solution containing a ceramic raw material powder into a sheet and drying the sheet.
The method according to claim 1,
Wherein the application of the release agent in step (b) is carried out by spraying the release agent onto the ceramic green sheet.
8. The method of claim 7,
Wherein the spraying is performed while the ceramic green sheet is transferred under a stationary injector.
9. The method of claim 8,
Wherein the spraying is performed under the conditions of an injection height of 100 to 500 mm, an injection pressure of 0.5 to 5.0 bar, and an injection angle of 20 to 80 degrees.
A ceramic powder having an average aspect ratio (A / R) of 2 to 5,
Wherein the ceramic powder has an average particle diameter (d ₅₀ ) of 3 to 10 占 퐉.
delete 11. The method of claim 10,
Wherein the ceramic powder is dispersed in a solvent.
A ceramic sheet dispersed on at least one surface of a release agent composed of ceramic powder having an average A / R of 2 to 5; And
And a polymer film layer formed on at least one surface of the ceramic sheet,
Wherein the ceramic powder has an average particle diameter (d ₅₀ ) of 3 to 10 占 퐉.
delete

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