JPS58183936A - Granulation of ceramic powder - Google Patents

Abstract

PURPOSE:To obtain a granule easily collapsible during press molding and excellent in mold releasability, by a method wherein a mixture of a high molecular emulsion and polyvinyl alcohol are compounded in the fine particle of a ceramics stock material as a particle binder and the obtained sludge is subjected to spray drying. CONSTITUTION:A mixture consisting of, on the basis of a solid component, 1-4% high molecular emulsion (e.g., polyacrylic ester) and 0.1-0.8% polyvinyl alcohol is compounded in the fine particle of a ceramics stock material as a particle binder and the obtained sludge is subjected to spray drying. Because thus obtained granule is easily collapsible during press molding and mold releasability thereof is excellent, a molded product is reduced in surface defficiency and one with high density is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for granulating a nine-cell powder that has a high packing density in a mold and has excellent mold releasability during press molding using an apparatus.

The raw material powder granules (hereinafter referred to as granules) K used for press forming of molds have a high roundness that increases the packing density to obtain a dense sintered body, and also have a high roundness of sintered crystals. Excellent deafening properties with smooth rounding of the surface are required, and this is especially strongly required for aluminum substrates used as integrated circuit boards using thick film printing.

The above-mentioned aluminum substrate is made of high-purity aluminum with a high aluminum content. - There is a demand for finer gaps, and along with this, tolerances for smoothness of the substrate surface and defects such as bits are gradually becoming stricter.

Defects that occur on the surface of the substrate described above may be due to recesses that occur outside the granules of the press-formed product when the fine particles of the raw material are once made into a slurry and are manufactured by spray drying, and the granules are hard and difficult to crush. Because of the granules attached to the INK and peeled off from the compact, or the crushed pieces of the granules, the organic binder used to granulate the raw material fine particles by jet drying is granulated, making the granules easy to crush, and having a high separation. The contradictory characteristics of having moldability are required,
It has not been possible to obtain a binder that satisfies both properties at the same time.

The present invention simultaneously solves the above-mentioned contradictory problems and has succeeded in granulating nine granules by spray drying that do not collapse and roar during press molding and have excellent mold release properties.
The 4I method involves blending a polymeric emulsion into a slurry using a mixture of polyvinyl alcohol as a particle binder and fine particles of ivy as a raw material.

In the present invention, the reason for using the Tamemolecular emulsion and polyvinyl alcohol together as the particle binder is as follows.
Considering that the 1t1i property is greatly affected by the particle binder's affinity for the metal surface of the metal part and the porcelain surface of the aluminum plate, we first applied various types of polyols known as conventional particle binders.
- The metal surface of the metal lid (steel material) and the setter group 1 [K] have a certain degree of fragility, as shown in the figure, polyacrylic acid ester (1), polyvinyl acetate (C),
Polymethacrylic acid ester (D), polyacrylic v (
While polymer emulsions such as E) are difficult to wet with alcoholic FFI devices, they are easy to rub against metals, while divinyl alcohol (M) exhibits the opposite characteristics.
Ta. In this way, the nine granules granulated using an emulsion of a polymer that is easily wetted with metal have the disadvantage that they are soft and easily crushed, while the nine granules granulated using polyvinyl alcohol are hard, crushable, and thin. On the other hand, this is based on the discovery that it not only has excellent mold releasability, but also has a unique high film-forming property that oozes out to the outside and forms a thin film during granulation.

Examples Alona (18 Wa Light Metal AI-/j) j-Anhydrous silicon II (Hayashi Pure Chemical Reagent Grade 1) JOf Calcium Suboxide (Rice Pharmaceutical Reagent Grade 1) 7/f Magnesium Vertical Acid (Katayama Chemical Reagent Grade 7) Sanko f is used as a raw material powder,
In this, Bolivier Arsul (Nippon Gosei (J-77)
Jjf, an emulsifier containing 10% of polyacrylic acid ester as a polymer emulsion (the same applies hereinafter) (Japanese pure dielimer 8E-j10); a particle binder consisting of lOJf;
Add t of water, mix and crush for 73 hours in a bowl with an internal volume of 4 t to form a slurry, which is then mixed at a gas temperature of g.
170℃, disk diameter/10-φ, 4100'RPIL
The granules according to the present invention were obtained by spray drying under the conditions of 10% per second, and the 9 granules were granulated under the same conditions except that polyacrylic acid ester was used as the particle binder except for polyvinyl alcohol, and 10Jt was used as the particle binder. (Comparative product 1) and granules granulated under the same conditions using only polyvinyl alcohol (779) without using polyacrylic acid ester (Comparative product 2) were molded onto a Kota x Kota x 2m substrate using a /l0OK4/dCJ mold press. Table ls1 shows the results of the baked crystals obtained by molding and firing these three molded products in an electric furnace at JJO° C. for 1 hour with constant ## characteristics.

/ / According to the above table, by using both polyvinyl alcohol and polyacrylic acid ester as particle binders, the product of the present invention has fewer surface defects and a high-density alumina substrate can be obtained.
Comparison product (1) with only polyacrylic acid ester compared to DK
The product O17i of the present invention has poor release properties and the number of continuous use of the mold is poor.
o K was not reached, and the comparative product using only polyvinyl alcohol had excellent mold releasability, but had many surface defects and low VLI.

The reason why the above effects are achieved in the present invention is that when the polyvinyl alcohol blended with the polyacrylic acid ester in the slurry is granulated by spray drying, it oozes out to the outside of the granules due to the high film-forming properties unique to the above-mentioned nine. The outer layer is thinly coated with debris from the ceramic raw material fine particles and the emulsifier, and has a low affinity for metals and is rich in IIII properties. This is to satisfy both requirements of releasability at the same time.

Add bulk ot% 1x to the cut surface and surface of the above finished product.
fpw7 le:1-le1po'1%, hou9191%,
When applied to a polyvinyl alcohol staining solution consisting of water and examined with a magnifying glass of 1gll0, the surface of the molded product was found to have a purple Pvum thin film. As a result, most of the granules in the inner IIO came into contact with the granules that came into instant contact with each other due to the pressure received from all four directions, forming a continuous multi-layer structure.

In addition to the above-mentioned polyacrylic acid ester, the emulsifying liquid to be mixed with polyvinyl alcohol includes polyacetic acid vinyl resin,
Alternatively, there are polyacrylic wk resins and others, and it has been confirmed that all of them have the same effects as polyacrylic esters.

Therefore, the mixing ratio of the above-mentioned polyvinyl alcohol and the emulsion tank O ceramitus raw material was within the range of polyvinyl alcohol at-alqk and emulsion solid content l-Yumeichi in terms of weight ratio, and the former polyvinyl alcohol exceeded the upper limit at- In this case, the granules are too hard and the surface OII grains in contact with the mold are crushed and separated during press molding, resulting in surface defects.On the other hand, when the lower limit is not reached, the 110 ceramic fine particles inside the granules are wrapped. The emulsion adheres to the mold and is peeled off from the molded body, causing surface defects.On the other hand, when the solid content of the emulsion is set to 7-3, the granules are difficult to crush during pressing and cause surface defects. If the temperature exceeds , the number of firing defects will increase, so it is necessary to limit the temperature to within the above range.

[Brief explanation of the drawing]

The drawing is a point graph showing the contact angles of polyvinyl alcohol used in the present invention, various emulsions, various polymers O, aluminum substrates, and gold proof metals. 1 1- ″” Mold name sword 1 (Hinbaiya) Otsu no Gi Katsuki 9 color procedural amendment (voluntary) 1945 7327 l Incident Showa! 7 cow patent m 4th! II Part No.-1 Name of the Invention Ceratus Tutus Powder O Granulation Method 3 Person Who Makes Amendment Case and 0WsS % Applicant (pre) Nippon Shishu Togyo Co., Ltd. In the specification subject to amendment, please refer to the detailed explanation of 1jIO. I am correcting ``ko4fJ'' to ``koJfJ.''

Claims (1)

[Claims] Add a polymer emulsion to the fine particles of the ceramic material at a solid content pace of 1-≠- and polyvinyl alcohol a/-6.
7- A ceramic powder O granulation method characterized by spray-drying a slurry formed by blending the mixture of 7- as a particle binder.