JPH0791128B2 - Method for manufacturing ceramics sintered body - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a ceramics sintered body, and in particular,
The present invention relates to a method for producing a porous ceramics sintered body having a large number of minute through holes.

(Prior Art) As a method for manufacturing this type of porous ceramics sintered body,
For example, a method is known in which a pattern of a photosensitive resin is embedded between green sheets, the photosensitive resin pattern is decomposed and disappeared by heating, and the green sheet is debindered and baked (Japanese Patent Laid-Open No. 63-99955). , Ibid 63-999
56, 63-99957 and 63-99958).
This method has the advantage that a large number of fine line patterns (fine patterns) with a line width of about 10 μm and a line spacing of about 20 μm can be formed because a pattern is formed by exposing and developing a photosensitive resin, and minute through holes are formed. There is a possibility to do it.

The green sheet used in the above-mentioned manufacturing method is made by binding ceramic powders with a general organic binder.
On the other hand, a method for producing a green sheet in which a ceramic powder is bound using a water-soluble polyurethane resin as a binder has also been proposed (JP-A-61-286261).

(Problems to be Solved by the Invention) Japanese Patent Laid-Open Nos. 63-99955 and 63-99956,
The manufacturing methods disclosed in 63-99957 and 63-99958 have the advantage that a fine line pattern can be formed as described above, but the binder in the green sheet used is generally organic. Since it is a binder, the softening and decomposition starting temperature (usually 15
At 0 to 200 ° C.), the organic binder in the green sheet also begins to soften and decompose. Therefore, the green sheet binder in contact with the fine wire pattern of the photosensitive resin flows with the ceramic powder due to the softening of the photosensitive resin and the volume change (heat shrinkage) at the time of decomposition, and the thin wire pattern is formed by disappearance. There has been a problem that the walls of the desired pores collapse and the ceramic powder enters the pores, and only a ceramic sintered body having incomplete pores containing sintering residues in the pores can be obtained.

On the other hand, the green sheet disclosed in JP-A-61-286261 is produced by using a water-soluble polyurethane resin in place of a normal organic binder, and the polyurethane resin used as the binder is a general thermoplastic resin. Since it is a polyurethane resin and is used alone, even when such a green sheet is used, the polyurethane resin flows during debinding as in the above case, the pore walls collapse, and it is still There is a problem that only a ceramics sintered body having complete voids can be obtained.

The present invention has been made in view of the above problems, and an object thereof is to be able to satisfactorily embed an organic matter pattern in the green sheet when laminating the green sheet and the organic matter pattern, and to remove the binder from the green sheet. It is an object of the present invention to provide a method for producing a ceramics sintered body capable of forming almost perfect through-holes containing no sintering residue without sometimes causing collapse of pore walls.

(Means for Solving the Problems) A method for manufacturing a ceramic sintered body of the present invention is to provide a pattern formed of an organic substance on the surface of a ceramic green sheet made of a resin binder and ceramic powder, and stack a plurality of these patterns. A method for manufacturing a ceramic sintered body having pores by burying an organic material pattern in a ceramics green sheet, heating the laminated body to eliminate the organic material pattern, and firing the laminated body, The resin binder is characterized by containing a blocked isocyanate compound having an active isocyanate group that is regenerated when the laminate is heated, a polyurethane resin, and a polyol, thereby achieving the above object.

The present invention will be described in detail below.

The ceramic green sheet used in the present invention contains a resin binder and ceramic powder, and may further contain an additive such as a colorant, a solvent and the like, if necessary. The compounding ratio of ceramic powder and resin binder is
Usually, the ceramic powder is 200 to 2000 parts by weight with respect to 100 parts by weight of the total amount of the resin binder. The green sheet can be prepared by a conventional method. For example, a predetermined amount of a resin binder is mixed in a mixture of ceramic powder and an organic solvent and uniformly kneaded, and the obtained slurry is applied to a doctor blade type green sheet making machine or the like. Obtained by supplying. In the present invention, the resin binder contains a blocked isocyanate compound having an active isocyanate group that can be regenerated by heating, a polyurethane resin, and a polyol.

As a method of forming an organic pattern on the surface of the green sheet, various pattern forming methods can be adopted. If a fine line pattern is not required, a resin having good thermal decomposability may be dissolved in a solvent to form a predetermined pattern by a screen printing method or the like.If a fine line pattern is required, the photosensitive resin film may be green. A predetermined pattern may be formed by laminating on a sheet, exposing and developing. As the organic material used for pattern formation, any material may be selected, but it is preferably 150 to 250.
Those that soften and decompose at ℃ are used.

Laminate multiple green sheets with patterns,
Then, it is preferable to perform thermocompression bonding. The thermocompression bonding may be carried out by a conventional method such as hot pressing, and the thermocompression bonding temperature may be arbitrarily selected as long as it is lower than the active isocyanate group regeneration temperature of the blocked isocyanate compound, but preferably 50 ° C to 150 ° C. It is in the range of ° C.

Next, the obtained laminate is heated to eliminate the organic material pattern, and the laminate is baked to remove the binder. Here, in the debinding process of the laminate, 25 ° C / hr
Gradually raise the temperature at the following rate, and finally reach 500 to 600
It is preferable to keep at 0 ° C for a long time. At that time, in the temperature range where the resin binder contained in the green sheet causes a crosslinking reaction, it is particularly desirable to raise the temperature extremely slowly at a temperature rising rate of 10 ° C./hr or less, and the temperature range is 120 to 200.
It is desirable that the temperature is ° C. The firing method after the binder removal may be appropriately determined depending on the ceramic powder used, but a firing method at 900 to 1650 ° C for 1 to 5 hours is usually preferable. In this way, the portion of the pattern where the organic material pattern disappears becomes a hole, and a ceramic sintered body having a large number of holes is obtained.

Next, the blocked isocyanate compound, polyurethane resin and polyol contained in the resin binder will be described in more detail.

The blocked isocyanate compound is obtained by blocking the isocyanate group of polyisocyanate having two or more active isocyanate groups in the molecule with a blocking agent,
The active isocyanate group is temporarily inactivated. The regeneration temperature of the active isocyanate group can be adjusted by changing the type of the blocking agent, and is arbitrarily set in a temperature range higher than the thermocompression bonding temperature of the green sheet, for example, 60 ° C. or higher is preferable. Below 60 ° C, the reactivity of the isocyanate group is extremely low. The blocked isocyanate compound is preferably a polyisocyanate containing 1.0 mmol / g or more of active isocyanate groups in the molecule, which is blocked with a blocking agent.

Examples of the polyisocyanate include, for example, triresin diisocyanate, diphenylmethane diisocyanate,
Hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, dicyclohexylmethane diisocyanate and modified substances thereof are preferably used, and examples of the blocking agent for temporarily deactivating the active isocyanate group include phenol, Phenol-based compounds such as nitrophenol, alcohol-based compounds such as methanol and ethanol, oxime-based compounds such as acetaldoxime and methylethylketoxime are preferably used.
If the blocking agent is an active hydrogen compound and produces a stable addition compound with low reactivity at the thermocompression bonding temperature of the green sheet (usually 60 ° C.) or lower by reaction with an isocyanate group, the above compound It is not limited to.

The polyurethane resin is used as a resin binder of a green sheet together with a blocked isocyanate compound and a polyol, and it is preferable that the polyurethane resin has the ability to form a green sheet even when the blocked isocyanate compound and the polyol are in an unreacted state. Further, those having softening fluidity at the time of thermocompression bonding are preferable. In particular, the number average molecular weight of the polyurethane resin is preferably 10 ⁴ to 10 ⁶ , and one having an active hydroxyl group in the molecule of 0.01 to 1.0 mmol / g is preferable, and more preferably 0.02 to 0.5 mmol / g. If the number average molecular weight of the polyurethane resin is smaller than the above range, the ability to form a sheet is reduced. That is, when forming a green sheet, since a large amount of ceramic powder is contained in the sheet with respect to the resin binder, the mechanical strength of the sheet is likely to decrease when the number average molecular weight of the polyurethane resin is small. Further, if the number average molecular weight of the polyurethane resin is too large, the solvent solubility is lowered. The above number average molecular weight is a value measured by GPC analysis. The usable polyurethane resin is not limited to the number average molecular weight in the above range, and may be out of this range in the part where the mechanical strength of the sheet is allowed. Further, when the amount of active hydroxyl groups contained in the polyurethane resin is too small, the reactivity with the isocyanate compound is poor, the crosslinking does not proceed sufficiently during heating and the heat resistance is insufficient, and collapse of the pore wall occurs, and If the amount is too large, the crosslinking reaction will proceed excessively, resulting in very brittleness, and the collapse of the pore wall will easily occur. Examples of the component constituting the main chain of the polyurethane resin include polyester, polyether, epoxy, acrylic, and the like, and polyester is preferable from the viewpoint of heat resistance.

The above polyol has an active hydroxyl group in the molecule of 0.1 to 20 mmlo / g
It is preferably contained, and more preferably 0.5-10 mmol /
It is g. Examples of such a polyol include polyethylene adipate, polyhexamethylene adipate,
Examples thereof include polyester polyols such as polycaprolactone, polyoxypropylene diols, polytetramethylene glycol ethers, polyether polyols such as polyoxyethylene diols, epoxy polyols and acrylic polyols. Of these, polyester polyols are particularly preferably used from the viewpoint of heat resistance.

When the amount of active hydroxyl groups contained in the polyol decreases,
The crosslink density with an isocyanate group when heated is lowered, heat resistance becomes insufficient and the collapse of the pore wall is likely to occur, and conversely, when it is increased, it becomes brittle and the collapse of the pore wall is likely to occur.

The mixing ratio of each component is preferably 3 to 40 parts by weight of polyol and 3 to 60 parts by weight of blocked isocyanate compound with respect to 100 parts by weight of polyurethane resin. Within this range, the mixing ratio may be arbitrarily changed. The fluidity of the binder can be adjusted when the green sheet is pressed. When the blending amount of the polyol and the blocked isocyanate compound with respect to the polyurethane resin is less than the above range, a residue may remain in the pores. That is, when the amount of the polyol blended is too small, the crosslinking with the isocyanate is not sufficiently performed during the binder removal, and the effect of binding and holding the ceramic powder becomes small. Further, if the blending amount of the polyurethane resin is too small, the green sheet forming ability tends to decrease, the handleability of the green sheet decreases, and the sintering residue may remain in the pores.

Then, a pattern of an organic material is formed on the surface of the green sheet prepared by using the resin binder having the above composition, and a plurality of these are laminated by thermocompression bonding, and at this thermocompression bonding, the isocyanate of the block isocyanate compound of the binder is formed. Since the groups do not undergo a crosslinking reaction while being inactivated, the green sheets have preferable fluidity, and the pattern of the organic material can be well embedded between the green sheets. The fluidity of the binder can be freely adjusted by changing the composition of the resin binder, that is, the type and / or the mixing ratio of the polyurethane resin, the polyol, and the blocked isocyanate compound. You will be able to choose freely compared to the binder.

Also, the thermocompression-bonded laminated body is supplied to a heating furnace, and the temperature is 10 ° C / hr.
When the temperature is slowly raised to the treatment temperature of the binder removal at the following heating rate, the active hydroxyl groups of the polyol and polyurethane resin react with the isocyanate groups of the blocked isocyanate compound to form a three-dimensional network structure of the binder,
It becomes a resin with excellent heat resistance. Therefore, when the organic material of the pattern starts to soften / decompose, the binder does not cause softening flow and holds the ceramic powder in a bonded state, so that the pore wall does not collapse as the volume of the pattern decreases. . Therefore, after the binder is removed, the temperature is further increased and the firing is performed to obtain a ceramics sintered body having complete through holes containing no sintering residue.

(Examples) The present invention will be described below with reference to Examples.

Examples 1 and 2 (parts by weight) Alumina powder (average particle size 2 μm) 230 Glass frit powder (MgO—SiO ₂ —CaO system, average particle size 0.8)
μm) 12 Black colorant (Solvent Black7) 1.5 Methyl ethyl ketone 140 The above mixture and a predetermined amount of the resin binder shown in Table 1 below were supplied to an alumina ball mill and kneaded for 3 hours to obtain a slurry. This slurry was supplied to a doctor blade type green sheet making machine, coated on a polyethylene terephthalate film and dried to produce a 100 μm 100 mm green sheet having a thickness of 50 μm.

The green sheet and photosensitive resin film (dry film resist “Photowell” manufactured by Sekisui Chemical Co., Ltd., heat 25 μm, supporting film polyethylene terephthalate) were heat laminated to the photosensitive resin film supporting film with fine wire. Attach a negative photomask with a pattern, and irradiate 40 m of UV light at a distance of 50 cm from a 3 kw high-pressure mercury lamp.
It was exposed to J / cm ² . Then, the support film of the photosensitive resin film is peeled off, and a 1% by weight aqueous solution of sodium carbonate at 30 ° C. is sprayed at 1 kg / cm ² for development to form a fine line pattern having a line width of 25 μm and a line interval of 25 μm on the surface of the green sheet. did.

Green sheet The fine line pattern is formed by peeling off the support film is laminated 500 sheets, 80 ℃, 30kg / cm ²
By pressing for 1 minute under the conditions described above, a 120 x 120 x 20 mm laminated body is prepared, and this laminated body is sliced perpendicular to the laminating surface
A 3 mm slice was obtained.

The obtained sliced body is put in a heating furnace and heated at a temperature rising rate of 5 ° C./hr, and held at 180 ° C. for 5 hours to cure the green sheet binder, and then at a temperature rising rate of 10 ° C./hr. The temperature is raised and kept at 500 ° C for 5 hours to eliminate the fine line pattern of the photosensitive resin and to remove the binder, and further 200 ° C / hr.
By heating at 1650 ° C. for 2 hours at a heating rate of 1 to obtain a porous ceramics sintered body having a large number of independent pores on one surface to the other surface.

Table 1 shows the results of observing the pore cross section of this porous ceramics sintered body with a scanning electron microscope.

Comparative Examples 1 and 2 The mixture used in Example I and the specified amount of green sheet binder shown in Table 1 below were mixed in an alumina ball mill to prepare a mixture.
The mixture was kneaded for a time to obtain a slurry, and thereafter, a porous ceramics sintered body was obtained in the same manner as in Example 1. The results of observing the cross section of the pores of this ceramic sintered body with a scanning electron microscope are also shown in Table 1 below.

As shown in Table 1 above, in Examples 1 and 2, ceramic sintered bodies having 25 μm square complete through holes containing no sintering residue were obtained.

On the other hand, in Comparative Examples 1 and 2, the pore walls partially collapsed during debinding and firing, and through holes were not formed.

Comparative Example 3 Except that polyvinyl butyral resin was used as a binder instead of the green sheet binder shown in Table 1 used in Example 1 and the blending amount was 30 parts by weight of polyvinyl butyral resin to 230 parts by weight of alumina powder. A porous ceramics sintered body was obtained in the same manner as in Example 1.

When the pores of this ceramic sintered body were observed with a scanning electron microscope, through pores were not formed due to debinding and the collapse of the pore wall during firing.

(Effects of the Invention) The present invention prevents the collapse of pore walls when debindering a laminate obtained by laminating green sheets on which patterns of organic materials are formed by heating as described above, and includes a sintering residue. It has the effect of efficiently manufacturing ceramics sintered bodies with through holes of various sizes and shapes, and manufactures component devices made of ceramics sintered bodies that require through holes, such as inkjet nozzles and ceramic filters. Very suitable for

Claims (1)

[Claims] 1. A ceramic green sheet comprising a resin binder and ceramic powder is provided with a pattern formed of an organic substance on the surface, a plurality of the patterns are laminated to embed the organic pattern in the ceramic green sheet, and the laminate is formed. While heating to eliminate the organic pattern,
A method for producing a ceramics sintered body having pores by firing the laminate, wherein the resin binder comprises a blocked isocyanate compound having an active isocyanate group regenerated when the laminate is heated, and a polyurethane resin. And a polyol.