JPH04120204A - Supercritical dewaxing method - Google Patents

Supercritical dewaxing method

Info

Publication number
JPH04120204A
JPH04120204A JP2239294A JP23929490A JPH04120204A JP H04120204 A JPH04120204 A JP H04120204A JP 2239294 A JP2239294 A JP 2239294A JP 23929490 A JP23929490 A JP 23929490A JP H04120204 A JPH04120204 A JP H04120204A
Authority
JP
Japan
Prior art keywords
binder
supercritical
molded body
degreasing
supercritical gas
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
JP2239294A
Other languages
Japanese (ja)
Inventor
Hidekazu Nishikawa
西川 英一
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Sumitomo Heavy Industries Ltd
Original Assignee
Sumitomo Heavy Industries Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Sumitomo Heavy Industries Ltd filed Critical Sumitomo Heavy Industries Ltd
Priority to JP2239294A priority Critical patent/JPH04120204A/en
Publication of JPH04120204A publication Critical patent/JPH04120204A/en
Pending legal-status Critical Current

Links

Abstract

PURPOSE:To increase the rate of dewaxing by adding a specified org. solvent as an entrainer to a supercritical gas when a binder in a molded body of fine ceramic powder is removed by utilizing the supercritical gas. CONSTITUTION:Powder of a metal, fine ceramic, etc., is mixed with a binder and molded. A supercritical gas such as CO2 or chlorofluoro-carbon having a gaseous state at ordinary temp. and pressure is brought into contact with the resulting molded body to extract and remove the binder. At this time, an org. solvent such as pentane, hexane, cyclohexane, carbon tetrachloride, toluene, benzene or chloroform is added to the supercritical gas so as to increase the rate of extraction and to shorten the time required to dewax the molded body.

Description

【発明の詳細な説明】 [発明の目的コ (産業上の利用分野) 本発明はファインセラミックスや金属などの粉末にバイ
ンダーを混合して加圧成形された成形体を焼成して焼結
体を製造する方法において、焼成の前工程として成形体
からバインダーを効率的に除去する方法に関する。
[Detailed Description of the Invention] [Purpose of the Invention (Industrial Application Field) The present invention is a method for producing a sintered body by mixing a powder of fine ceramics, metal, etc. with a binder, and firing a compact formed by pressure. The present invention relates to a method for efficiently removing a binder from a molded body as a pre-baking step in a manufacturing method.

(従来の技術) 従来、焼結体の製造においては、金属、セラミックスな
どからなる材料粉末を加圧成形したものを焼成すること
により製造されている。このとき、材料粉末の加圧成形
に先立って材料粉末に塑性を付与して取扱いのための強
度をあげる目的で5〜30%程度の有機バインダーが添
加される。一般に、有機バインダーには熱可塑性樹脂、
ワックス、高級アルコール等が用いられる。しかし、こ
のようにバインダーを添加した成形体をそのまま焼成す
ると、バインダーが急激に気泡化し、成形体はたちまち
膨張し変形を起こす。このため、焼成するには成形体か
ら加熱などの処理によりバインダーを除去する必要があ
る。
(Prior Art) Conventionally, sintered bodies have been manufactured by press-molding material powders made of metals, ceramics, etc. and then firing them. At this time, prior to pressure molding of the material powder, about 5 to 30% of an organic binder is added for the purpose of imparting plasticity to the material powder and increasing its strength for handling. Generally, organic binders include thermoplastic resins,
Wax, higher alcohol, etc. are used. However, when a molded body to which a binder is added is fired as it is, the binder rapidly becomes bubbles, and the molded body immediately expands and deforms. Therefore, in order to perform firing, it is necessary to remove the binder from the molded body through treatment such as heating.

本出願人は、焼成前に成形体からバインダーを除く方法
として、超臨界ガスの持つ化学的親和力を利用する方法
を出願している(特開昭61−155265号公報参照
)。臨界温度以上、臨界圧力以上の状態をもつ超臨界ガ
スは密度が増大しているので、成形体内のバインダーに
対して溶剤として強力に作用し、溶解して連行する。こ
のように、超臨界脱脂法は焼成前の成形体に超臨界ガス
を接触させ、バインダーを溶出するものである。
The present applicant has applied for a method that utilizes the chemical affinity of supercritical gas as a method for removing the binder from a molded body before firing (see Japanese Patent Laid-Open No. 155265/1982). Since the supercritical gas, which has a temperature above the critical temperature and a pressure above the critical pressure, has an increased density, it acts strongly as a solvent on the binder in the molded body, and dissolves and entrains the binder. In this manner, the supercritical degreasing method involves bringing a supercritical gas into contact with a molded article before firing to elute the binder.

超臨界ガスとしては、二酸化炭素、フロンなど常温、常
圧下で気体であるものを使用するのが一般的である。超
臨界ガスでバインダーを溶出、連行して除去後、減圧し
てバインダーとガスを分離して脱バインダー処理が完了
する。バインダーは回収し、再利用することが出来る。
As the supercritical gas, gases that are gaseous at room temperature and pressure, such as carbon dioxide and chlorofluorocarbons, are generally used. After the binder is eluted and removed using supercritical gas, the binder and gas are separated by reducing the pressure to complete the binder removal process. Binder can be collected and reused.

(発明が解決しようとする問題点) この超臨界ガスを利用した脱バインダー法は、脱脂を短
時間で行うと、バインダーの膨張や気泡化等により焼成
体にワレ、フクレ、反り等の変形が生じる恐れのあった
加熱脱脂法と比較して大幅な時間短縮が可能となった。
(Problems to be Solved by the Invention) This debinding method using supercritical gas can cause deformations such as cracks, blisters, and warping in the fired product due to expansion and bubble formation of the binder if degreasing is performed in a short time. Compared to the heat degreasing method, which could cause degreasing, it has become possible to significantly shorten the time.

しかしながらこの超臨界ガスを用いる方法によっても成
形体の肉厚が大きい場合は脱脂時間が長くなる傾向があ
る。例えば二酸化炭素を超臨界ガスとして用い、肉厚1
5mmのセラミックス成形体を80%脱脂するのに20
hr s以上必要である。さらに肉厚のある成形体では
もっと脱脂時間を必要とする。本発明は超臨界ガスを用
いる成形体の脱脂時間を短縮する方法を得ること目的と
するものである。
However, even with this method using supercritical gas, the degreasing time tends to be long when the thickness of the molded body is large. For example, using carbon dioxide as a supercritical gas, the wall thickness is 1
20 to degrease 80% of a 5mm ceramic molded body
More than hrs is required. Furthermore, thick molded bodies require more degreasing time. An object of the present invention is to obtain a method for shortening the degreasing time of a molded article using supercritical gas.

[発明の構成コ (問題点を解決するための手段) 本発明は、ファインセラミックス成形体の超臨界脱脂法
において、超臨界ガスにエントレーナとして有機溶媒を
添加することにより脱脂速度の向上を図る方法である。
[Structure of the Invention (Means for Solving Problems)] The present invention provides a method for improving the degreasing rate by adding an organic solvent as an entrainer to a supercritical gas in a supercritical degreasing method for fine ceramic molded bodies. It is.

エントレーナとして添加する有機溶媒はペンタン、ヘキ
サン、シクロヘキサン、四塩化炭素、トルエン、ベンゼ
ン、クロロホルム、塩化メチレン、テトラヒドロフラン
、アセトン、酢酸エチル、メタノール、エタノール、プ
ロパノール、イソプロパノール等、ないしはこれらの混
合体で、常温、常圧で液体のものが、成形体に含まれる
バインダーの種類により選択される。
The organic solvent added as an entrainer is pentane, hexane, cyclohexane, carbon tetrachloride, toluene, benzene, chloroform, methylene chloride, tetrahydrofuran, acetone, ethyl acetate, methanol, ethanol, propanol, isopropanol, etc., or a mixture thereof, at room temperature. , which is liquid at normal pressure is selected depending on the type of binder contained in the molded body.

超臨界ガスに対して添加される有機溶媒の濃度は効率を
考慮して決定する。超臨界ガスは二酸化炭素やフロンの
ような常温、常圧で気体のものを用いる。
The concentration of the organic solvent added to the supercritical gas is determined in consideration of efficiency. The supercritical gas used is one that is gaseous at room temperature and pressure, such as carbon dioxide or fluorocarbon.

(作用) 本発明の超臨界脱脂方法の構成を装置概略を示す第1図
に基づいて説明する。
(Function) The configuration of the supercritical degreasing method of the present invention will be explained based on FIG. 1 which schematically shows the apparatus.

セラミックス成形体を恒温槽6内に納められている抽出
槽7内部にセットした後に二酸化炭素ボンベ1から取り
出した二酸化炭素をポンプ2により昇圧する。このとき
エントレーナタンク3よりエントレーナをポンプ4によ
り、二酸化炭素に送入する。送入するエントレーナの割
合は二酸化炭素に対して一定となるようにする。二酸化
炭素とエントレーナの混合物は熱交換器5により昇温さ
れ、抽出槽7に送られる。成形体に含まれるバインダー
は、超臨界状態にある二酸化炭素中エントレーナに溶解
する。所定の圧力を維持しながら減圧弁8を開き、大気
圧まで減圧すると、超臨界ガスに溶解したバインダー及
びエントレーナは分離槽9に捕集され、二酸化炭素は大
気に放出する。
After the ceramic molded body is set inside an extraction tank 7 housed in a constant temperature bath 6, carbon dioxide taken out from a carbon dioxide cylinder 1 is pressurized by a pump 2. At this time, the entrainer is fed into carbon dioxide from the entrainer tank 3 using the pump 4. The ratio of entrainer to be fed is made constant with respect to carbon dioxide. The mixture of carbon dioxide and entrainer is heated by a heat exchanger 5 and sent to an extraction tank 7. The binder contained in the molded body is dissolved in the entrainer in carbon dioxide in a supercritical state. When the pressure reducing valve 8 is opened to reduce the pressure to atmospheric pressure while maintaining a predetermined pressure, the binder and entrainer dissolved in the supercritical gas are collected in the separation tank 9, and carbon dioxide is released into the atmosphere.

規定時間脱脂をした後、成形体を抽出槽7から取り出す
と、脱脂体が得られる。
After degreasing for a specified time, the molded body is taken out from the extraction tank 7 to obtain a degreased body.

以上のように超臨界ガスにエントレーナとして有機溶媒
を添加させることで抽出速度の向上が図れるため、脱脂
時間が短縮される。とりわけ、肉厚のある成形体を処理
する場合に有効である。またエントレーナを添加しても
脱脂後の保形性には問題はない。
As described above, since the extraction rate can be improved by adding an organic solvent to the supercritical gas as an entrainer, the degreasing time can be shortened. This is particularly effective when processing thick molded bodies. Further, even if entrainer is added, there is no problem in shape retention after degreasing.

(実施例) 以下に本発明の実施例を示す。(Example) Examples of the present invention are shown below.

実施例1゜ アルミナ粉末100部、バインダー17部を混合した後
、射出成形機により厚さ15mmのギアを成形する。そ
の成形体を超臨界ガスに二酸化炭素、エントレーナにヘ
キサンを10wt%添加シて脱脂温度60℃、脱脂圧力
200kg/cm2脱脂時間3hrsの操作条件で脱脂
したところ、保形性も良好で脱脂率は82%であった。
Example 1 After 100 parts of alumina powder and 17 parts of a binder were mixed, a gear with a thickness of 15 mm was molded using an injection molding machine. When the molded body was degreased under the operating conditions of adding carbon dioxide to the supercritical gas and hexane to the entrainer at a degreasing temperature of 60°C, a degreasing pressure of 200 kg/cm2, and a degreasing time of 3 hrs, the shape retention was good and the degreasing rate was low. It was 82%.

この成形体を同一操作条件で超臨界状態の二酸化炭素だ
けで脱脂すると脱脂率は71%であり、脱脂率の向上が
みられた。
When this molded body was degreased using only supercritical carbon dioxide under the same operating conditions, the degreasing rate was 71%, indicating an improvement in the degreasing rate.

実施例2゜ アルミナ粉末100部、バインダー17部を混合した後
射出成形機により40X40X15mmのブロック体を
成形する。この成形体を超臨界ガスに二酸化炭素、エン
トレーナにエタノールを10wt%添加して、脱脂温度
60℃、脱脂圧力200kg/cm2の操作条件で行っ
た。その脱脂時間と脱脂率の関係を第2図に示す。図に
示すように、脱脂率80%の脱脂品を得るのに超臨界二
酸化炭素のみでは20hrS以上必要としているのに対
して、エントレーナを添加すると10hrSで十分脱脂
できる。
Example 2 After 100 parts of alumina powder and 17 parts of binder were mixed, a block of 40 x 40 x 15 mm was molded using an injection molding machine. This compact was degreased under operating conditions of 60° C. degreasing temperature and 200 kg/cm 2 degreasing pressure by adding carbon dioxide to the supercritical gas and 10 wt % ethanol to the entrainer. The relationship between the degreasing time and the degreasing rate is shown in FIG. As shown in the figure, supercritical carbon dioxide alone requires 20 hrS or more to obtain a degreased product with a degreasing rate of 80%, whereas with the addition of entrainer, 10 hrS is sufficient for degreasing.

[発明の効果コ 本発明の方法のように、超臨界脱脂法において超臨界ガ
スにエントレーナを添加して処理を行うと、超臨界ガス
単独の処理に比して脱脂速度が向上し、時間の短縮が可
能となる。とりわけ脱脂時間を多く必要とする肉厚のあ
る成形体に有効で脱脂プロセスの効率化が図れる効果が
ある。
[Effects of the invention] When an entrainer is added to the supercritical gas in the supercritical degreasing method as in the method of the present invention, the degreasing speed is improved compared to the treatment using supercritical gas alone, and the time is reduced. Shortening is possible. It is particularly effective for thick molded bodies that require a long time for degreasing, and has the effect of increasing the efficiency of the degreasing process.

【図面の簡単な説明】[Brief explanation of the drawing]

第1図は本発明の実施例の装置概略図、第2図は本発明
の実施例における脱脂時間と脱脂率の結果を示すグラフ
である。 1・・・二酸化炭素ボンベ、2・・・ポンプ、3・・・
エントレーナタンク、4・・・ポンプ、5・・・熱交換
器、6・・・恒温槽、7・・・抽出槽、8・・・減圧弁
、9・・・分離槽、10・・・ガスメーター1CO2ボ
ンベ 2ポンプ 3エントレーナタンク 4ポンプ 5熱交喚器 6 恒温槽 7抽出槽 8 減圧弁 9 分離槽 10ガスメーター 第1図 脱脂時間 [hr] 第2図
FIG. 1 is a schematic diagram of an apparatus according to an embodiment of the present invention, and FIG. 2 is a graph showing the results of degreasing time and degreasing rate in an embodiment of the present invention. 1... Carbon dioxide cylinder, 2... Pump, 3...
Entrainer tank, 4... Pump, 5... Heat exchanger, 6... Constant temperature tank, 7... Extraction tank, 8... Pressure reducing valve, 9... Separation tank, 10... Gas meter 1 CO2 cylinder 2 Pump 3 Entrainer tank 4 Pump 5 Heat exchanger 6 Constant temperature tank 7 Extraction tank 8 Pressure reducing valve 9 Separation tank 10 Gas meter Figure 1 Degreasing time [hr] Figure 2

Claims (1)

【特許請求の範囲】[Claims] (1)金属、ファインセラミックスなどの粉末にバイン
ダーを混合して成形した成形体に超臨界ガスを接触させ
バインダーを溶出除去する超臨界脱脂法において、超臨
界ガスに有機溶媒を添加して成形体内のバインダーを溶
出除去することを特徴とする超臨界脱脂法。(2)前記
有機溶媒がペンタン、ヘキサン、シクロヘキサン、四塩
化炭素、トルエン、べンゼン、クロロホルム、塩化メチ
レン、テトラヒドロフラン、アセトン、酢酸エチル、メ
タノール、エタノール、プロパノール、イソプロパノー
ルから選択された有機溶媒、ないしは2種以上の有機溶
媒の混合体であることを特徴とする請求項1記載の超臨
界脱脂法。
(1) In the supercritical degreasing method, in which the binder is eluted and removed by contacting supercritical gas with a molded body made by mixing a binder with powder of metals, fine ceramics, etc., an organic solvent is added to the supercritical gas to form the molded body. A supercritical degreasing method characterized by eluting and removing the binder. (2) The organic solvent is selected from pentane, hexane, cyclohexane, carbon tetrachloride, toluene, benzene, chloroform, methylene chloride, tetrahydrofuran, acetone, ethyl acetate, methanol, ethanol, propanol, and isopropanol; The supercritical degreasing method according to claim 1, characterized in that it is a mixture of more than one type of organic solvent.
JP2239294A 1990-09-10 1990-09-10 Supercritical dewaxing method Pending JPH04120204A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2239294A JPH04120204A (en) 1990-09-10 1990-09-10 Supercritical dewaxing method

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2239294A JPH04120204A (en) 1990-09-10 1990-09-10 Supercritical dewaxing method

Publications (1)

Publication Number Publication Date
JPH04120204A true JPH04120204A (en) 1992-04-21

Family

ID=17042596

Family Applications (1)

Application Number Title Priority Date Filing Date
JP2239294A Pending JPH04120204A (en) 1990-09-10 1990-09-10 Supercritical dewaxing method

Country Status (1)

Country Link
JP (1) JPH04120204A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009270177A (en) * 2008-05-09 2009-11-19 National Institute Of Advanced Industrial & Technology Method for extracting removing organic binder contained in molded product containing powder material and the organic binder, from the molded product
CN103203454A (en) * 2013-03-25 2013-07-17 沈阳北真真空科技有限公司 Vacuum dewaxing system

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0313503A (en) * 1989-06-09 1991-01-22 Tokin Corp Method for degreasing molding for powder metallurgy, binder and supercritical fluid

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0313503A (en) * 1989-06-09 1991-01-22 Tokin Corp Method for degreasing molding for powder metallurgy, binder and supercritical fluid

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009270177A (en) * 2008-05-09 2009-11-19 National Institute Of Advanced Industrial & Technology Method for extracting removing organic binder contained in molded product containing powder material and the organic binder, from the molded product
CN103203454A (en) * 2013-03-25 2013-07-17 沈阳北真真空科技有限公司 Vacuum dewaxing system

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