JP2021109994A - Composition for metal powder injection molding and method for producing the same - Google Patents
Composition for metal powder injection molding and method for producing the same Download PDFInfo
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本発明は、射出成形により焼結可能な金属粉末の成形体を製造し、この成形体から焼結体製品を製造する方法に用いるための金属粉末射出成形用組成物に関する。 The present invention relates to a composition for metal powder injection molding for producing a metal powder molded body that can be sintered by injection molding and using it in a method for producing a sintered body product from the molded body.
近年、複雑な形状の金属製品を成形するためには、射出成形法が利用されている。この射出成形法では、金属粉末に流動性を持たせるために種々の有機化合物及び熱可塑性樹脂を添加し、加熱混練の後、これを成形用原料として射出成形し、得られた成形体を脱脂・焼結することにより、焼結体製品を得るものである。従来から用いられている射出成形用組成物、なかでも金属粉末を用いた射出成形用組成物では多くの場合、高分子化合物としてポリエチレン、ポリプロピレン、メタクリル酸エステル共重合体及びエチレン‐酢酸ビニル共重合体、ポリアセタール、ポリスチレン等を用い、低融点化合物としてパラフィンワックス、カルナバワックス等を用いてバインダとするものであった。
特に、混練工程において、各々の高分子化合物並びに低分子化合物を各化合物の融点以上の温度において、金属粉末と混ぜ合わせることにより、金属粉末射出成形材料を得て、成形を行っている。
しかしながら、混練工程においては高融点化合物である高分子化合物と低分子化合物が均一分散することは困難であり、高分子化合物が数十ミクロン〜数百ミクロン程度の塊として残留することが多い。このことから、射出成形時において低分子化合物は分離し、金型に付着することが多く、長時間成形する場合において、金型のガス逃げ部分、突き出しピンの部分にワックス等の低融点化合物が滞留し、金型の動きを妨げ、最悪の場合には金型を破損したり、成形体中にガス逃げができないガスが滞留し、成形体にウエルド・気泡が発生する不具合が生じる。
また、脱脂、焼結時においては膨れ並びに数十〜数百ミクロン程度の気泡が生じることがある。
実際に、ポリオキシメチレン（ＰＯＭ）にポリオレフィン、ワックスを添加し、脱脂変形の少ない製品を加熱により脱脂する方法（特許文献１参照）がある。しかしながら、この方法で得られた、成形体並びに焼結体においては上記に示す欠陥が生じることが問題になっている。特にＰＯＭを有機バインダとして用いることで、脱脂時の変形を小さくできるものの、有機バインダとしてＰＯＭに併せてオレフィン樹脂を添加するため、加熱混練中にオレフィン樹脂が相分離を生じ、混練後の射出成形用組成物にオレフィン樹脂が析出し、成形時に低融点化合物が相分離を生じやすく、脱脂・焼結時に析出したオレフィン樹脂が原因となり、膨れ・気泡が発生しやすくなる。
In recent years, an injection molding method has been used to mold a metal product having a complicated shape. In this injection molding method, various organic compounds and thermoplastic resins are added in order to give fluidity to the metal powder, and after heat kneading, this is used as a raw material for molding by injection molding, and the obtained molded product is degreased. -By sintering, a sintered product is obtained. Conventionally used injection molding compositions, especially injection molding compositions using metal powder, often contain polyethylene, polypropylene, methacrylate copolymer and ethylene-vinyl acetate copolymer as polymer compounds. Combined, polyacetal, polystyrene and the like were used, and paraffin wax, carnauba wax and the like were used as low melting point compounds to form a binder.
In particular, in the kneading step, a metal powder injection molding material is obtained by mixing each high molecular compound and a low molecular compound with a metal powder at a temperature equal to or higher than the melting point of each compound, and molding is performed.
However, in the kneading step, it is difficult to uniformly disperse the high molecular weight compound which is a high melting point compound and the low molecular weight compound, and the high molecular weight compound often remains as a mass of about several tens of microns to several hundreds of microns. For this reason, low molecular weight compounds are often separated during injection molding and adhere to the mold, and in the case of long-term molding, low melting point compounds such as wax are present on the gas escape portion and the protrusion pin portion of the mold. It stays and hinders the movement of the mold, and in the worst case, the mold is damaged or gas that cannot escape gas stays in the molded body, causing a problem that welds and bubbles are generated in the molded body.
In addition, during degreasing and sintering, swelling and bubbles of several tens to several hundreds of microns may occur.
Actually, there is a method of adding polyolefin and wax to polyoxymethylene (POM) and degreasing a product having less degreasing deformation by heating (see Patent Document 1). However, there is a problem that the above-mentioned defects occur in the molded product and the sintered body obtained by this method. In particular, by using POM as an organic binder, deformation during degreasing can be reduced, but since the olefin resin is added together with POM as an organic binder, the olefin resin undergoes phase separation during heat kneading, and injection molding after kneading occurs. The olefin resin is precipitated in the composition, and the low melting point compound is likely to cause phase separation during molding, and the olefin resin precipitated during degreasing and sintering is likely to cause swelling and bubbles.
したがって、本発明は金属粉末の射出成形法において、成形時における有機バインダの分離を抑制し、射出成形時に低分子化合物の分離を防ぎ、脱脂・焼結時において焼結体の膨れ、気泡の発生を防ぎ、欠陥のない焼結体を得るために、有機バインダが均一に分散した射出成形用組成物を提供することを課題とする。 Therefore, in the injection molding method for metal powder, the present invention suppresses the separation of organic binders during molding, prevents the separation of low molecular weight compounds during injection molding, and causes swelling of the sintered body and generation of bubbles during degreasing and sintering. It is an object of the present invention to provide an injection molding composition in which an organic binder is uniformly dispersed in order to prevent the above-mentioned problems and obtain a defect-free sintered body.
本発明者らは、金属粉末と有機バインダを混合したものを原料（射出成形用組成物）として射出成形し、この射出形成体を脱脂・焼結して目的製品を得る方法において、焼結可能な金属粉末と、有機バインダとからなる射出成形用組成物において、前記有機バインダとしてポリアセタールにオレフィンをアロイ化した樹脂とエチレングリシジルメタクリレート共重合体及びポリオレフィン樹脂をあらかじめ押出機を用いて混合物を作成したものを高分子化合物として有機バインダに用いることで、射出成形時に低分子化合物の分離を防ぎ、脱脂・焼結時において焼結体の膨れ、気泡の発生を防ぎ、欠陥のない焼結体を得ることができる。 The present inventors can sinter in a method in which a mixture of metal powder and an organic binder is injection-molded as a raw material (composition for injection molding), and this injection-formed body is degreased and sintered to obtain a target product. In an injection molding composition composed of a metal powder and an organic binder, a mixture of a resin obtained by alloying an olefin with polyacetal as the organic binder, an ethylene glycidyl methacrylate copolymer, and a polyolefin resin was prepared in advance using an extruder. By using the product as a polymer compound in an organic binder, separation of low molecular weight compounds is prevented during injection molding, swelling of the sintered body and generation of air bubbles are prevented during degreasing and sintering, and a sintered body without defects is obtained. be able to.
特に、前記樹脂（Ａ）及び（Ｂ）からなる有機バインダを３０〜６０体積％含むとともに、この有機バインダ中の樹脂（Ａ）における高分子化合物組成比がａ：１０〜７０体積％、ｂ：１０〜４０体積％、ｃ：２０〜６０体積％とする。有機バインダの添加量を樹脂（Ａ）が３０〜７０体積％とし、（Ｂ）として融点が１２０℃以下の有機化合物３０〜７０体積％を焼結可能な金属粉末に添加し、１４０〜１９０℃の加熱混練温度で混練を行う。得られた射出成形用組成物を用いることにより、均一な射出成形体を得ることができ、欠陥の無い脱脂・焼結体を得ることができる。 In particular, the organic binder composed of the resins (A) and (B) is contained in an amount of 30 to 60% by volume, and the composition ratio of the polymer compound in the resin (A) in the organic binder is a: 10 to 70% by volume, b: It is set to 10 to 40% by volume and c: 20 to 60% by volume. The amount of the organic binder added was 30 to 70% by volume of the resin (A), and 30 to 70% by volume of the organic compound having a melting point of 120 ° C. or lower was added to the sinterable metal powder as (B), and 140 to 190 ° C. Knead at the heating kneading temperature of. By using the obtained composition for injection molding, a uniform injection-molded body can be obtained, and a degreased / sintered body without defects can be obtained.
すなわち、本発明にかかる射出成形用組成物は、焼結可能な金属粉末と、有機バインダとからなり、前記有機バインダを構成する高分子成分が、ａ：ポリオキシメチレン（ＰＯＭ）熱可塑性樹脂、ｂ：エチレングリシジルメタクリレート共重合体、ｃ：ポリプロピレンもしくはポリエチレン樹脂から選ばれた１種以上の樹脂であり、これらａ、ｂ、ｃの樹脂を１８０℃以上２２０℃以下の条件で一軸もしくは二軸押出機により得られた樹脂（Ａ）を用いることで、高分子成分ａ、ｃは相溶化剤であるｂにより、相溶化した樹脂（Ａ）を得ることができる。この樹脂Ａに対して、（Ｂ）として融点が１２０℃以下の有機化合物を用いることにより、成形体の有機バインダの均一性の向上を図るとともに、脱脂・焼結時に膨れ気泡の無い健全な焼結体を得る。 That is, the injection molding composition according to the present invention comprises a sinterable metal powder and an organic binder, and the polymer component constituting the organic binder is a: polyoxymethylene (POM) thermoplastic resin. b: One or more resins selected from ethylene glycidyl methacrylate copolymer, c: polypropylene or polyethylene resin, and these a, b, and c resins are uniaxially or biaxially extruded under the conditions of 180 ° C. or higher and 220 ° C. or lower. By using the resin (A) obtained by the machine, the resin (A) in which the polymer components a and c are compatible with the compatibilizer b can be obtained. By using an organic compound having a melting point of 120 ° C. or lower as (B) with respect to this resin A, the uniformity of the organic binder of the molded product is improved, and sound baking without swelling bubbles during degreasing / sintering is performed. Get united.
本発明にかかる射出成形用組成物によれば、脱脂・焼成後においても、変形ならびに膨れ・気泡の無い健全な焼結体を得ることができる。 According to the injection molding composition according to the present invention, a sound sintered body without deformation, swelling and air bubbles can be obtained even after degreasing and firing.
本発明にかかる高分子化合物の成分（ａ）ポリオキシメチレン（ＰＯＭ）にはホモポリマーもしくはコポリマーからなるＰＯＭ樹脂を用いることができる。及び、予めＰＯＭにオレフィン樹脂をアロイ化させたＰＯＭ等から選ばれた一種もしくは複数種類を用いる。本発明において、これら樹脂は２２０℃以上の加温雰囲気において、ジッパー分解を生じ速やかに分解し、焼結後に分解物が残留しない。このことから焼結時において、不純物として存在せずに健全な焼結体を得ることができる。しかしながら、成分（ａ）においては高分子化合物である成分（ｃ）並びに低融点化合物（Ｂ）とは相溶性が無く、射出成形時に分離を生じ、脱脂・焼結体に膨れ・割れ等の欠陥が生じる。このことから、高分子化合物成分（ａ）と高分子化合物成分（ｃ）を相溶化させる樹脂として高分子化合物成分（ｂ）を用いる。
成分（ａ）の添加量は１０〜７０体積％であり、望ましくは１５〜６０体積％であり、さらに望ましくは２０〜５０体積％である。成分（ａ）の添加量が１０体積％未満の場合には脱脂時に変形が大きく発生する。また、添加量が７０体積％よりも多い場合には脱脂時において分解ガスが急激に発生し、クラックが生じる。
As the component (a) polyoxymethylene (POM) of the polymer compound according to the present invention, a POM resin composed of a homopolymer or a copolymer can be used. In addition, one or more types selected from POM or the like in which an olefin resin is alloyed with POM in advance are used. In the present invention, these resins undergo zipper decomposition in a heated atmosphere of 220 ° C. or higher and decompose rapidly, and no decomposed product remains after sintering. From this, it is possible to obtain a sound sintered body without being present as an impurity at the time of sintering. However, the component (a) is not compatible with the polymer compound component (c) and the low melting point compound (B), and separation occurs during injection molding, resulting in defects such as swelling and cracking in the degreasing / sintered body. Occurs. For this reason, the polymer compound component (b) is used as the resin that makes the polymer compound component (a) and the polymer compound component (c) compatible with each other.
The amount of the component (a) added is 10 to 70% by volume, preferably 15 to 60% by volume, and more preferably 20 to 50% by volume. When the amount of the component (a) added is less than 10% by volume, large deformation occurs during degreasing. Further, when the addition amount is more than 70% by volume, decomposition gas is rapidly generated at the time of degreasing, and cracks occur.
本発明の高分子化合物成分（ｂ）としてはエチレングリシジルメタクリレート共重合体：（ＥＧＭＡ）、エチレン−アクリル酸エステル−GMA（グリシジルメタクリレート）共重合体：（ＥＧＭＡ-ＭＡ）、エチレン−ビニルアセテート−ＧＭＡ（グリシジルメタクリレート）共重合体：（ＥＧＭＡ-ＶＡ）から選ばれた１種類以上の樹脂を用いることができる。
成分（ｂ）の添加量は１０〜４０体積％であり、望ましくは１５〜３５体積％であり、さらに望ましくは２０〜３０体積％である。成分（ｂ）の添加量が１０体積％未満の場合には高分子化合物成分（ａ）と高分子化合物成分（ｃ）の相溶性が不十分となり、脱脂時において、膨れ・気泡が発生しやすくなる。また、添加量が４０体積％よりも多い場合には脱脂時の加熱分解が不十分となり、残留物が炭素化して残留しやすくなる。
The polymer compound component (b) of the present invention includes ethylene glycidyl methacrylate copolymer: (EGMA), ethylene-acrylic acid ester-GMA (glycidyl methacrylate) copolymer: (EGMA-MA), and ethylene-vinyl acetate-GMA. (Glysidyl methacrylate) copolymer: One or more kinds of resins selected from (EGMA-VA) can be used.
The amount of the component (b) added is 10 to 40% by volume, preferably 15 to 35% by volume, and more preferably 20 to 30% by volume. When the amount of the component (b) added is less than 10% by volume, the compatibility between the polymer compound component (a) and the polymer compound component (c) becomes insufficient, and swelling and bubbles are likely to occur during degreasing. Become. Further, when the addition amount is more than 40% by volume, the thermal decomposition at the time of degreasing becomes insufficient, and the residue is easily carbonized and remains.
次に、高分子化合物の成分（ｃ）としてポリプロピレンもしくはポリエチレンの一種以上が用いられる。ポリプロピレン樹脂にはホモポリマー、ランダムコポリマー及びブロックコポリマーがあるが、これらのうち、ホモポリマー及びブロックコポリマーの１種以上が望ましい。また、ポリエチレン樹脂には高密度ポリエチレンもしくは低密度ポリエチレンが用いられる。これらポリプロピレンもしくはポリエチレン樹脂は射出成形体にじん性を付与するが、混練時に単独で他の有機バインダ並びに金属粉末と加熱混練した場合には、高分子化合物である成分（ａ）と均一に相溶せず、成形体に不具合を生じるが、高分子化合物の成分（ａ）並びに（ｂ）と一緒に一軸もしくは二軸押出機を用いて材料を溶融押出することにより、高分子化合物を均一化することができる。
成分（ｃ）の添加量は２０〜６０体積％であり、望ましくは２５〜５５体積％であり、さらに望ましくは３０〜５０体積％である。
成分（ｃ）の添加量が２０体積％未満の場合には射出成形体のじん性が低下しクラックが発生しやすくなる。また、添加量が６０体積％よりも多い場合には脱脂時の変形が大きくなる。
Next, one or more types of polypropylene or polyethylene are used as the component (c) of the polymer compound. Polypropylene resins include homopolymers, random copolymers and block copolymers, of which one or more of homopolymers and block copolymers are desirable. Further, high density polyethylene or low density polyethylene is used as the polyethylene resin. These polypropylene or polyethylene resins impart toughness to the injection molded product, but when they are kneaded alone with other organic binders and metal powder during heat kneading, they are uniformly compatible with the component (a) which is a polymer compound. However, although problems occur in the molded product, the polymer compound is homogenized by melt-extruding the material together with the components (a) and (b) of the polymer compound using a single-screw or twin-screw extruder. Can be done.
The amount of the component (c) added is 20 to 60% by volume, preferably 25 to 55% by volume, and more preferably 30 to 50% by volume.
When the amount of the component (c) added is less than 20% by volume, the toughness of the injection molded product is lowered and cracks are likely to occur. Further, when the addition amount is more than 60% by volume, the deformation at the time of degreasing becomes large.
本発明の有機化合物の成分（Ｂ）としては、脂肪酸エステル、脂肪酸アミド、フタル酸エステル、パラフィンワックス、マイクロクリスタリンワックス、ポリエチレンワックス、ポリプロピレンワックス、カルナバワックス、モンタン系ワックス、ウレタン化ワックス、無水マレイン酸変性ワックス、及びポリグリコール系化合物から選ばれる１種以上を用いることができる。用いられる有機化合物の添加量が３０体積％未満の場合には、成形時の流動性が悪くなり、成形体に割れ及びクラックが生じやすくなる。また、添加量が７０体積％よりも多くなると、成形時において成形体にバリが発生しやすくなり、成形体の強度が低下する恐れがある。成分（ｃ）の添加量は３０〜７０体積％であるが、望ましい添加量は３５〜６０体積％であり、より望ましい添加量は４５〜５５体積％である。
更に成形体の流動性、靭性をさらに高めるためにアモルファスポリオレフィン樹脂、エチレン酢酸ビニル共重合体、エチレン・アクリル共重合体等のオレフィン系樹脂を添加してもよい。
The components (B) of the organic compound of the present invention include fatty acid ester, fatty acid amide, phthalic acid ester, paraffin wax, microcrystallin wax, polyethylene wax, polypropylene wax, carnauba wax, montan wax, urethanized wax, and maleic anhydride. One or more selected from modified waxes and polyglycol-based compounds can be used. When the amount of the organic compound used is less than 30% by volume, the fluidity at the time of molding is deteriorated, and cracks and cracks are likely to occur in the molded product. On the other hand, if the amount added is more than 70% by volume, burrs are likely to occur in the molded product during molding, and the strength of the molded product may decrease. The addition amount of the component (c) is 30 to 70% by volume, the desirable addition amount is 35 to 60% by volume, and the more desirable addition amount is 45 to 55% by volume.
Further, an olefin resin such as an amorphous polyolefin resin, an ethylene vinyl acetate copolymer, or an ethylene / acrylic copolymer may be added in order to further enhance the fluidity and toughness of the molded product.
本発明の有機バインダ樹脂成分（Ａ）、低融点化合物（Ｂ）の合計が、射出成形用組成物（金属粉末＋有機バインダ）全量中で３０体積％未満の場合には、成形体が脆くなりやすい。また、成分（Ａ）、（Ｂ）の合計が、射出成形用組成物全量中で６０体積％よりも多くなると、脱脂工程において変形が生じやすくなる。 When the total amount of the organic binder resin component (A) and the low melting point compound (B) of the present invention is less than 30% by volume in the total amount of the injection molding composition (metal powder + organic binder), the molded product becomes brittle. Cheap. Further, when the total of the components (A) and (B) is more than 60% by volume in the total amount of the injection molding composition, deformation is likely to occur in the degreasing step.
高分子化合物成分（ａ）、（ｂ）、（ｃ）の混合物である樹脂成分（Ａ）の製造方法として、高分子化合物成分（ａ）、（ｂ）、（ｃ）はブレンダーを用いて予備混合の後、一軸もしくは二軸押出機を用いて最高温度１８０℃〜２００℃で樹脂を均一化する。使用する押出機は一軸押出機よりも二軸押出機を用いる方がより安定して均一化できる。また、スクリュのＬ／Ｄは２０以上のものが好ましい。また、用いるスクリュにはミキシング機構を有するものを用いることが好ましい。
押出機により得られたストランドは水冷により固化され、ペレタイザーにより、ペレット化する。
本発明の射出成形用組成物として、焼結可能な金属粉末に、樹脂成分（Ａ）、低融点化合物（Ｂ）からなる有機バインダをバッチタイプもしくは連続タイプの混練機を用いて１６０℃〜１８０℃の温度で１〜３時間程度混練し、これを数ミリの大きさに粉砕し、射出成形を行う。得られた射出成形体は不活性ガス中で５００℃〜８００℃で脱脂を行い、以後９００℃〜１５００℃の温度で不活性ガス中、還元ガス中もしくは真空中で焼結を行う。
As a method for producing the resin component (A) which is a mixture of the polymer compound components (a), (b) and (c), the polymer compound components (a), (b) and (c) are preliminarily used using a blender. After mixing, the resin is homogenized at a maximum temperature of 180 ° C. to 200 ° C. using a single-screw or twin-screw extruder. It is possible to make the extruder more stable and uniform by using a twin-screw extruder than by using a single-screw extruder. Further, the screw L / D is preferably 20 or more. Further, it is preferable to use a screw having a mixing mechanism.
The strands obtained by the extruder are solidified by water cooling and pelletized by a pelletizer.
As the composition for injection molding of the present invention, an organic binder composed of a resin component (A) and a low melting point compound (B) is mixed with a sinterable metal powder using a batch type or continuous type kneader at 160 ° C. to 180 ° C. Knead at a temperature of ° C. for about 1 to 3 hours, crush this into a size of several millimeters, and perform injection molding. The obtained injection molded product is degreased in an inert gas at 500 ° C. to 800 ° C., and then sintered in an inert gas, a reducing gas or a vacuum at a temperature of 900 ° C. to 1500 ° C.
本発明に用いられる金属粉末はステンレス、鉄系材料、チタン、銅、ニッケル等の粉末が挙げられる。本発明に用いられる金属粉末の平均粒径は１〜３０μｍが好ましい。粉末の粒径が１μｍ未満になると、成形に必要なバインダ量が多くなるために脱脂時に変形及び割れ、膨れ等の欠陥が生じやすい。また、粉末平均粒径が３０μｍを超えると、成形時に粉末とバインダが分離しやすく、また、焼結後の密度が低くなり、得られた焼結体の強度も低下する。ここで、平均粒径とは、レーザー回折・散乱法を使用した粒度分布測定装置を用いて、測定した重量累積５０％の平均径を意味する。粒度分布測定装置としては、島津製作所製 ＳＡＬＤ−２０００型を用いることができる。 Examples of the metal powder used in the present invention include powders of stainless steel, iron-based materials, titanium, copper, nickel and the like. The average particle size of the metal powder used in the present invention is preferably 1 to 30 μm. If the particle size of the powder is less than 1 μm, the amount of binder required for molding increases, so that defects such as deformation, cracking, and swelling are likely to occur during degreasing. Further, when the average powder particle size exceeds 30 μm, the powder and the binder are easily separated during molding, the density after sintering is lowered, and the strength of the obtained sintered body is also lowered. Here, the average particle size means an average diameter of 50% of the cumulative weight measured by using a particle size distribution measuring device using a laser diffraction / scattering method. As the particle size distribution measuring device, a SALD-2000 type manufactured by Shimadzu Corporation can be used.
本発明の上記組成物を射出成形し、得られた成形体を脱脂炉に入れ、処理温度１００〜６００℃の間において添加した有機バインダを除去する。脱脂速度に関しては１００〜２００℃の間を１０〜５０℃／ｈｒの昇温速度で処理することで変形の無い脱脂体を得ることができる。
脱脂後の成形体は９００〜１５００℃において焼結することにより、変形・膨れ及び割れ等の欠陥がなく、バインダからの残留カーボンが非常に少ない焼結体を短時間に得ることができる。
The above composition of the present invention is injection-molded, and the obtained molded product is placed in a degreasing furnace to remove the added organic binder at a treatment temperature of 100 to 600 ° C. Regarding the degreasing rate, a degreased body without deformation can be obtained by treating the temperature between 100 and 200 ° C. at a heating rate of 10 to 50 ° C./hr.
By sintering the molded product after degreasing at 900 to 1500 ° C., it is possible to obtain a sintered body having no defects such as deformation, swelling and cracking and having very little residual carbon from the binder in a short time.
以下、実施例及び比較例により発明をさらに説明するが、本発明はこれに限定されるものではない。 Hereinafter, the invention will be further described with reference to Examples and Comparative Examples, but the present invention is not limited thereto.
［実施例１］
樹脂成分（Ａ）として、成分（ａ）であるポリオキシメチレン樹脂（旭化成 テナックＣ９５２０）、成分（ｂ）であるエチレングリシジルメタクリレート樹脂（住友化学 ボンドファースト ＢＦ-７Ｂ）並びに成分（ｃ）であるポリプロピレン樹脂（住友ノーブレン Ｗ531Ｄ）を二軸押出機（東芝機械製TEM-26SX）を用いて、スクリュ温度を１８０℃〜２００℃に設定、スクリュ回転速度を500rpmに設定し、ペレットを作成した。
次に加圧ニーダー中に、まず、樹脂成分（Ａ）を投入し、１８０℃で溶融させた後、パラフィンワックス（低融点化合物Ｂ 融点６０℃）、カルナバワックス（低融点化合物Ｂ）及びモンタン酸ワックス（低融点化合物Ｂ Licowax E）を投入し、均一に溶融させた後、ＳＵＳ３１６Ｌ粉末（平均粒径：７μｍ）を投入して６０分間混練し、取り出した後混練物を粉砕し、射出成形用組成物を得た。次に、成形温度１８０℃の条件で射出し、図１に記載の厚さ３ｍｍ、幅１０ｍｍ、長さ６０ｍｍの成形体を得た。
成形用組成物
ＳＵＳ３１６Ｌ粉末 ５８体積％
樹脂成分（Ａ） ２１体積％
低融点化合物（Ｂ） ２１体積％
バインダ組成
樹脂成分（Ａ）
（ａ）ポリオキシメチレン ３０．０体積％
（ｂ）エチレングリシジルメタクリレート ２５．０体積％
（ｃ）ポリプロピレン ４５．０体積％
低融点化合物（Ｂ）
パラフィンワックス ８５．０体積％
カルナバワックス ７. ０体積％
モンタン酸ワックス ８．０体積％
[Example 1]
As the resin component (A), the polyoxymethylene resin (Asahi Kasei Tenac C9520) which is the component (a), the ethylene glycidyl methacrylate resin (Sumitomo Chemical Bond First BF-7B) which is the component (b), and polypropylene which is the component (c). Using a twin-screw extruder (TEM-26SX manufactured by Toshiba Machine Co., Ltd.), the resin (Sumitomo Noblen W531D) was set to a screw temperature of 180 ° C. to 200 ° C. and a screw rotation speed of 500 rpm to prepare pellets.
Next, the resin component (A) was first put into the pressurized kneader and melted at 180 ° C., and then paraffin wax (low melting point compound B melting point 60 ° C.), carnauba wax (low melting point compound B) and montanoic acid. Wax (low melting point compound B Licowax E) is added and melted uniformly, then SUS316L powder (average particle size: 7 μm) is added and kneaded for 60 minutes. The composition was obtained. Next, injection was performed under the condition of a molding temperature of 180 ° C. to obtain a molded product having a thickness of 3 mm, a width of 10 mm and a length of 60 mm as shown in FIG.
Molding composition SUS316L powder 58% by volume
Resin component (A) 21% by volume
Low melting point compound (B) 21% by volume
Binder composition Resin component (A)
(A) Polyoxymethylene 30.0% by volume
(B) Ethylene glycidyl methacrylate 25.0% by volume
(C) Polypropylene 45.0% by volume
Low melting point compound (B)
Paraffin wax 85.0% by volume
Carnauba wax 7.0% by volume
Montanic acid wax 8.0% by volume
［実施例２］
樹脂成分（Ａ）として、成分（ａ）であるポリオキシメチレン樹脂（ポリプラスチックス ＮＷ０２）、成分（ｂ）であるエチレングリシジルメタクリレート樹脂（住友化学 ボンドファースト ＢＦ-７Ｍ）並びに成分（ｃ）であるポリプロピレン樹脂（プライムポリマー Ｊ108Ｍ）を二軸押出機（東芝機械製TEM-26SX）を用いて、スクリュ温度を１８０℃〜２００℃に設定、スクリュ回転速度を500rpmに設定し、ペレットを作成した。
次に加圧ニーダー中に、まず、樹脂成分（Ａ）を投入し、１８０℃で溶融させた後、パラフィンワックス（低融点化合物Ｂ 融点６４℃）、カルナバワックス（低融点化合物Ｂ）及びポリエチレンワックス（低融点化合物Ｂ ネオワックス）を投入し、均一に溶融させた後、ＳＵＳ３１６Ｌ粉末（平均粒径：７μｍ）を投入して６０分間混練し、取り出した後混練物を粉砕し、射出成形用組成物を得た。次に、成形温度１８０℃の条件で射出し、図１に記載の厚さ３ｍｍ、幅１０ｍｍ、長さ６０ｍｍの成形体を得た。
成形用組成物
ＳＵＳ３１６Ｌ粉末 ５８体積％
樹脂成分（Ａ） ２１体積％
低融点化合物（Ｂ） ２１体積％
バインダ組成
樹脂成分（Ａ）
（ａ）ポリオキシメチレン ３０．０体積％
（ｂ）エチレングリシジルメタクリレート ２５．０体積％
（ｃ）ポリプロピレン ４５．０体積％
低融点化合物（Ｂ）
パラフィンワックス ８５．０体積％
カルナバワックス ７. ０体積％
ポリエチレンワックス ８．０体積％
[Example 2]
The resin component (A) is a polyoxymethylene resin (polyplastics NW02) which is a component (a), an ethylene glycidyl methacrylate resin (Sumitomo Chemical Bond First BF-7M) which is a component (b), and a component (c). Using a twin-screw extruder (TEM-26SX manufactured by Toshiba Machine Co., Ltd.), a polypropylene resin (prime polymer J108M) was set to a screw temperature of 180 ° C. to 200 ° C. and a screw rotation speed of 500 rpm to prepare pellets.
Next, the resin component (A) was first put into the pressurized kneader and melted at 180 ° C., and then paraffin wax (low melting point compound B melting point 64 ° C.), carnauba wax (low melting point compound B) and polyethylene wax. (Low melting point compound B neowax) is added and melted uniformly, then SUS316L powder (average particle size: 7 μm) is added and kneaded for 60 minutes. After taking out, the kneaded product is crushed to form an injection molding composition. I got something. Next, injection was performed under the condition of a molding temperature of 180 ° C. to obtain a molded product having a thickness of 3 mm, a width of 10 mm and a length of 60 mm as shown in FIG.
Molding composition SUS316L powder 58% by volume
Resin component (A) 21% by volume
Low melting point compound (B) 21% by volume
Binder composition Resin component (A)
(A) Polyoxymethylene 30.0% by volume
(B) Ethylene glycidyl methacrylate 25.0% by volume
(C) Polypropylene 45.0% by volume
Low melting point compound (B)
Paraffin wax 85.0% by volume
Carnauba wax 7.0% by volume
Polyethylene wax 8.0% by volume
［実施例３］
樹脂成分（Ａ）として、成分（ａ）であるポリオキシメチレン樹脂（ユピタール Ｆ４０−０３）、成分（ｂ）であるエチレングリシジルメタクリレート樹脂（ロターダ ＡＸ８９００）並びに成分（ｃ）であるポリエチレン樹脂（ハイゼックス １３００Ｊ）を二軸押出機（東芝機械製TEM-26SX）を用いて、スクリュ温度を１８０℃〜２００℃に設定、スクリュ回転速度を500rpmに設定し、ペレットを作成した。
次に加圧ニーダー中に、まず、樹脂成分（Ａ）を投入し、１８０℃で溶融させた後、パラフィンワックス（低融点化合物Ｂ 融点６４℃）、カルナバワックス（低融点化合物Ｂ）及びポリエチレンワックス（低融点化合物Ｂ ネオワックス）を投入し、均一に溶融させた後、ＳＵＳ３１６Ｌ粉末（平均粒径：７μｍ）を投入して６０分間混練し、取り出した後混練物を粉砕し、射出成形用組成物を得た。次に、成形温度１８０℃の条件で射出し、図１に記載の厚さ３ｍｍ、幅１０ｍｍ、長さ６０ｍｍの成形体を得た。
成形用組成物
ＳＵＳ３１６Ｌ粉末 ５８体積％
樹脂成分（Ａ） ２１体積％
低融点化合物（Ｂ） ２１体積％
バインダ組成
樹脂成分（Ａ）
（ａ）ポリオキシメチレン ２８．０体積％
（ｂ）エチレングリシジルメタクリレート ２５．０体積％
（ｃ）ポリエチレン ４７．０体積％
低融点化合物（Ｂ）
パラフィンワックス ８０．０体積％
カルナバワックス １０. ０体積％
ポリエチレンワックス １０．０体積％
[Example 3]
As the resin component (A), the polyoxymethylene resin (Iupital F40-03) which is the component (a), the ethylene glycidyl methacrylate resin (Rotada AX8900) which is the component (b), and the polyethylene resin (HIZEX 1300J) which is the component (c). ) Was set to 180 ° C. to 200 ° C. and the screw rotation speed was set to 500 rpm using a twin-screw extruder (TEM-26SX manufactured by Toshiba Machine Co., Ltd.) to prepare pellets.
Next, the resin component (A) was first put into the pressurized kneader and melted at 180 ° C., and then paraffin wax (low melting point compound B melting point 64 ° C.), carnauba wax (low melting point compound B) and polyethylene wax. (Low melting point compound B neowax) is added and melted uniformly, then SUS316L powder (average particle size: 7 μm) is added and kneaded for 60 minutes. After taking out, the kneaded product is crushed to form an injection molding composition. I got something. Next, injection was performed under the condition of a molding temperature of 180 ° C. to obtain a molded product having a thickness of 3 mm, a width of 10 mm and a length of 60 mm as shown in FIG.
Molding composition SUS316L powder 58% by volume
Resin component (A) 21% by volume
Low melting point compound (B) 21% by volume
Binder composition Resin component (A)
(A) Polyoxymethylene 28.0% by volume
(B) Ethylene glycidyl methacrylate 25.0% by volume
(C) Polyethylene 47.0% by volume
Low melting point compound (B)
Paraffin wax 80.0% by volume
Carnauba wax 10.0% by volume
Polyethylene wax 10.0% by volume
［比較例１］
加圧ニーダー中に樹脂成分（Ａ）として、成分（ａ）であるポリオキシメチレン樹脂（旭化成 テナックＣ９５２０）、成分（ｂ）であるエチレングリシジルメタクリレート樹脂（住友化学 ボンドファースト ＢＦ-７Ｂ）並びに成分（ｃ）であるポリプロピレン樹脂（住友ノーブレン Ｗ531Ｄ）を用いて、１８０℃で溶融させた後、パラフィンワックス（低融点化合物Ｂ 融点６０℃）、カルナバワックス（低融点化合物Ｂ）及びモンタン酸ワックス（低融点化合物Ｂ Licowax E）を投入し、均一に溶融させた後、ＳＵＳ３１６Ｌ粉末（平均粒径：７μｍ）を投入して６０分間混練し、取り出した後混練物を粉砕し、射出成形用組成物を得た。次に、成形温度１８０℃の条件で射出し、図１に記載の厚さ３ｍｍ、幅１０ｍｍ、長さ６０ｍｍの成形体を得た。
成形用組成物
ＳＵＳ３１６Ｌ粉末 ５８体積％
樹脂成分（Ａ） ２１体積％
低融点化合物（Ｂ） ２１体積％
バインダ組成
樹脂成分（Ａ）
（ａ）ポリオキシメチレン ３０．０体積％
（ｂ）エチレングリシジルメタクリレート ２５．０体積％
（ｃ）ポリプロピレン ４５．０体積％
低融点化合物（Ｂ）
パラフィンワックス ８５．０体積％
カルナバワックス ７. ０体積％
モンタン酸ワックス ８．０体積％
[Comparative Example 1]
In the pressurized kneader, as the resin component (A), the polypropylene resin (Asahi Kasei Tenac C9520) which is the component (a), the ethylene glycidyl methacrylate resin (Sumitomo Chemical Bond First BF-7B) which is the component (b), and the component ( After melting at 180 ° C. using polypropylene resin (Sumitomo Noblen W531D) which is c), paraffin wax (low melting point compound B melting point 60 ° C.), carnauba wax (low melting point compound B) and montanic acid wax (low melting point). Compound B Licowax E) was added and melted uniformly, then SUS316L powder (average particle size: 7 μm) was added and kneaded for 60 minutes. After taking out, the kneaded product was crushed to obtain an injection molding composition. rice field. Next, injection was performed under the condition of a molding temperature of 180 ° C. to obtain a molded product having a thickness of 3 mm, a width of 10 mm and a length of 60 mm as shown in FIG.
Molding composition SUS316L powder 58% by volume
Resin component (A) 21% by volume
Low melting point compound (B) 21% by volume
Binder composition Resin component (A)
(A) Polyoxymethylene 30.0% by volume
(B) Ethylene glycidyl methacrylate 25.0% by volume
(C) Polypropylene 45.0% by volume
Low melting point compound (B)
Paraffin wax 85.0% by volume
Carnauba wax 7.0% by volume
Montanic acid wax 8.0% by volume
［比較例２］
加圧ニーダー中に、樹脂成分（Ａ）として、成分（ａ）であるポリオキシメチレン樹脂（ポリプラスチックス ＮＷ０２）、成分（ｂ）であるエチレングリシジルメタクリレート樹脂（住友化学 ボンドファースト ＢＦ-７Ｍ）並びに成分（ｃ）であるポリエチレン樹脂（ハイゼックス １３００Ｊ）を用いて、１８０℃で溶融させた後、パラフィンワックス（低融点化合物Ｂ 融点６４℃）、カルナバワックス（低融点化合物Ｂ）及びポリエチレンワックス（低融点化合物Ｂ ネオワックス）を投入し、均一に溶融させた後、ＳＵＳ３１６Ｌ粉末（平均粒径：７μｍ）を投入して６０分間混練し、取り出した後混練物を粉砕し、射出成形用組成物を得た。次に、成形温度１８０℃の条件で射出し、図１に記載の厚さ３ｍｍ、幅１０ｍｍ、長さ６０ｍｍの成形体を得た。
成形用組成物
ＳＵＳ３１６Ｌ粉末 ５８体積％
樹脂成分（Ａ） ２１体積％
低融点化合物（Ｂ） ２１体積％
バインダ組成
樹脂成分（Ａ）
（ａ）ポリオキシメチレン ３０．０体積％
（ｂ）エチレングリシジルメタクリレート ２５．０体積％
（ｃ）ポリエチレン ４５．０体積％
低融点化合物（Ｂ）
パラフィンワックス ８５．０体積％
カルナバワックス ７. ０体積％
ポリエチレンワックス ８．０体積％
実施例１〜３及び比較例１〜２より得られた射出成形体を脱脂炉内に設置し、窒素ガスを室温から５０℃/ｈｒの昇温速度で１５０℃まで昇温した。以後、窒素ガス雰囲気で１５０℃〜２００℃までを昇温速度３０℃／ｈｒで昇温し１時間保持し、２００℃から４００℃までを昇温速度３０℃／ｈｒで昇温後、４００℃から６００℃までを１２０℃/ｈｒで昇温後、炉冷した（脱脂加熱時間：合計約１５時間）。脱脂を終えた成形体はアルゴン雰囲気下で室温から２００℃／ｈｒで徐々に昇温し、最高温度１３５０℃で２時間保持し、焼結を行った。実施例１〜３においては焼結体に膨れ、クラックのない健全な焼結密度９７％以上の焼結体が得られた。しかしながら、比較例１，２においては焼結体内部に５０〜１００ミクロン程度の気泡が生じ、焼結密度においても９６％以下であった。
図２（ＳＥＭ写真）は実施例１におけるバインダの混合状況を示す。また、図３（ＳＥＭ写真）には比較例１のバインダ混合状況を示す。実施例１ではバインダは均一に溶融し分散していることが確認されたが、比較例１ではＰＰが繊維状に析出しており、これが焼結時に膨れ、気泡の原因になったと考えられる。
[Comparative Example 2]
In the pressurized kneader, as the resin component (A), the polyoxymethylene resin (polyplastics NW02) which is the component (a), the ethylene glycidyl methacrylate resin (Sumitomo Chemical Bond First BF-7M) which is the component (b), and After melting at 180 ° C. using the polyethylene resin (Hi-Zex 1300J) which is the component (c), paraffin wax (low melting point compound B melting point 64 ° C.), carnauba wax (low melting point compound B) and polyethylene wax (low melting point). Compound B neowax) was added and melted uniformly, then SUS316L powder (average particle size: 7 μm) was added and kneaded for 60 minutes. After taking out, the kneaded product was crushed to obtain an injection molding composition. rice field. Next, injection was performed under the condition of a molding temperature of 180 ° C. to obtain a molded product having a thickness of 3 mm, a width of 10 mm and a length of 60 mm as shown in FIG.
Molding composition SUS316L powder 58% by volume
Resin component (A) 21% by volume
Low melting point compound (B) 21% by volume
Binder composition Resin component (A)
(A) Polyoxymethylene 30.0% by volume
(B) Ethylene glycidyl methacrylate 25.0% by volume
(C) Polyethylene 45.0% by volume
Low melting point compound (B)
Paraffin wax 85.0% by volume
Carnauba wax 7.0% by volume
Polyethylene wax 8.0% by volume
The injection molded products obtained from Examples 1 to 3 and Comparative Examples 1 and 2 were placed in a degreasing furnace, and the nitrogen gas was heated from room temperature to 150 ° C. at a heating rate of 50 ° C./hr. After that, the temperature is raised from 150 ° C. to 200 ° C. at a heating rate of 30 ° C./hr for 1 hour in a nitrogen gas atmosphere, and the temperature is raised from 200 ° C. to 400 ° C. at a heating rate of 30 ° C./hr, and then 400 ° C. After raising the temperature from to 600 ° C. at 120 ° C./hr, the mixture was cooled in a furnace (defatting heating time: about 15 hours in total). The degreased molded product was gradually heated from room temperature at 200 ° C./hr under an argon atmosphere, held at a maximum temperature of 1350 ° C. for 2 hours, and sintered. In Examples 1 to 3, the sintered body swelled, and a sound sintered body having no cracks and having a sintering density of 97% or more was obtained. However, in Comparative Examples 1 and 2, bubbles of about 50 to 100 microns were generated inside the sintered body, and the sintering density was 96% or less.
FIG. 2 (SEM photograph) shows the mixing state of the binder in Example 1. Further, FIG. 3 (SEM photograph) shows the binder mixing state of Comparative Example 1. In Example 1, it was confirmed that the binder was uniformly melted and dispersed, but in Comparative Example 1, PP was precipitated in a fibrous form, which was considered to have swelled during sintering and caused air bubbles.
［実施例４〜１１、比較例３〜６］
さらに、有機バインダ成分を種々変更して実験を行った。用いた有機バインダの組成を表１に、射出成形用組成物の組成と結果を表２に示す。なお、混練の条件、脱脂の条件並びに焼結の条件は実施例１〜３に準じて行った。成形体の肉厚については図１に記載の３ｍｍで行った。
有機バインダ成分表（体積％）
樹脂成分（Ａ）
ポリオキシメチレン：ＰＯＭ（ポリプラスチックス ＮＷ０２）
エチレングリシジルメタクリレート：ＥＧＭＡ（住友化学 ボンドファースト ＢＦ-７Ｂ）
ポリプロピレン：ＰＰ（プライムポリマー Ｊ108Ｍ）
ポリエチレン：ＰＥ（ハイゼックス １３００Ｊ）
低融点化合物（Ｂ）
モンタン酸ワックス：Mｗａｘ、カルナバワックス：Ｃｗａｘ
パラフィンワックス：Ｐｗａｘ、ポリエチレンワックス：ＰEＷａｘ
Furthermore, the experiment was carried out by changing various organic binder components. The composition of the organic binder used is shown in Table 1, and the composition and result of the injection molding composition are shown in Table 2. The kneading conditions, degreasing conditions, and sintering conditions were the same as in Examples 1 to 3. The wall thickness of the molded product was 3 mm as shown in FIG.
Organic binder composition table (% by volume)
Resin component (A)
Polyoxymethylene: POM (Polyplastics NW02)
Ethylene glycidyl methacrylate: EGMA (Sumitomo Chemical Bond First BF-7B)
Polypropylene: PP (Prime Polymer J108M)
Polyethylene: PE (Hi-Zex 1300J)
Low melting point compound (B)
Montanic acid wax: Mwax, carnauba wax: Cwax
Paraffin wax: Pwax, Polyethylene wax: PEWax
試料１〜８に関しては高分子化合物成分を本発明の範囲内で配合し、樹脂（Ａ）とし、低融点化合物（Ｂ）を本発明の範囲内で配合した。試料９〜１２に関しては樹脂（Ａ）の配合を本発明の配合範囲外とし、樹脂（Ａ）と低融点化合物（Ｂ）の配合については本発明の範囲内とした。また、金属粉末（ＳＵＳ316Ｌ）と有機バインダの配合は本発明範囲内とした。樹脂（Ａ）の配合を本発明の配合範囲外とした９〜１２の配合を用いた有機バインダでは健全な焼結体を得ることはできなかった。 For Samples 1 to 8, the polymer compound component was blended within the range of the present invention to form the resin (A), and the low melting point compound (B) was blended within the range of the present invention. For Samples 9 to 12, the compounding of the resin (A) was out of the compounding range of the present invention, and the compounding of the resin (A) and the low melting point compound (B) was within the range of the present invention. The composition of the metal powder (SUS316L) and the organic binder was within the scope of the present invention. A sound sintered body could not be obtained with an organic binder using a composition of 9 to 12 in which the composition of the resin (A) was out of the compounding range of the present invention.
［比較例７］
樹脂成分（Ａ）として、成分（ａ）であるポリオキシメチレン樹脂（旭化成 テナックＣ９５２０）、成分（ｂ）であるエチレングリシジルメタクリレート樹脂（住友化学 ボンドファースト ＢＦ-７Ｂ）並びに成分（ｃ）ではないポリスチレン樹脂（ＰＳＪ ６７９）を二軸押出機（東芝機械製TEM-26SX）を用いて、スクリュ温度を１８０℃〜２００℃に設定、スクリュ回転速度を500rpmに設定し、ペレットを作成した。
次に加圧ニーダー中に、まず、樹脂成分（Ａ）を投入し、１８０℃で溶融させた後、パラフィンワックス（低融点化合物Ｂ 融点６０℃）、カルナバワックス（低融点化合物Ｂ）及びモンタン酸ワックス（低融点化合物Ｂ Licowax E）を投入し、均一に溶融させた後、ＳＵＳ３１６Ｌ粉末（平均粒径：７μｍ）を投入して６０分間混練し、取り出した後混練物を粉砕し、射出成形用組成物を得た。次に、成形温度１８０℃の条件で射出し、図１に記載の厚さ３ｍｍ、幅１０ｍｍ、長さ６０ｍｍの成形体を得た。
成形用組成物
ＳＵＳ３１６Ｌ粉末 ５８体積％
樹脂成分（Ａ） ２１体積％
低融点化合物（Ｂ） ２１体積％
バインダ組成
樹脂成分（Ａ）
（ａ）ポリオキシメチレン ３０．０体積％
（ｂ）エチレングリシジルメタクリレート ２５．０体積％
（ｃ）ポリスチレン ４５．０体積％
低融点化合物（Ｂ）
パラフィンワックス ８５．０体積％
カルナバワックス ７. ０体積％
モンタン酸ワックス ８．０体積％
樹脂成分（Ａ）のうち、成分（ｃ）に該当しないポリスチレン樹脂を用いた場合には、図４（ＳＥＭ写真）に示す通り、成形体にクラックが生じ、界面にポリスチレン樹脂が分離析出していることが確認された。このことから成分（ｃ）にはポリオレフィン樹脂を用いることにより、均一な有機バインダ組成になることが写真１に示す通り確認された。
[Comparative Example 7]
As the resin component (A), the polyoxymethylene resin (Asahi Kasei Tenac C9520) which is the component (a), the ethylene glycidyl methacrylate resin (Sumitomo Chemical Bond First BF-7B) which is the component (b), and polystyrene which is not the component (c). Using a twin-screw extruder (TEM-26SX manufactured by Toshiba Machine Co., Ltd.), the resin (PSJ 679) was set to a screw temperature of 180 ° C. to 200 ° C. and a screw rotation speed of 500 rpm to prepare pellets.
Next, the resin component (A) was first put into the pressurized kneader and melted at 180 ° C., and then paraffin wax (low melting point compound B melting point 60 ° C.), carnauba wax (low melting point compound B) and montanoic acid. Wax (low melting point compound B Licowax E) is added and melted uniformly, then SUS316L powder (average particle size: 7 μm) is added and kneaded for 60 minutes. The composition was obtained. Next, injection was performed under the condition of a molding temperature of 180 ° C. to obtain a molded product having a thickness of 3 mm, a width of 10 mm and a length of 60 mm as shown in FIG.
Molding composition SUS316L powder 58% by volume
Resin component (A) 21% by volume
Low melting point compound (B) 21% by volume
Binder composition Resin component (A)
(A) Polyoxymethylene 30.0% by volume
(B) Ethylene glycidyl methacrylate 25.0% by volume
(C) Polystyrene 45.0% by volume
Low melting point compound (B)
Paraffin wax 85.0% by volume
Carnauba wax 7.0% by volume
Montanic acid wax 8.0% by volume
When a polystyrene resin that does not correspond to the component (c) is used among the resin components (A), cracks occur in the molded product as shown in FIG. 4 (SEM photograph), and the polystyrene resin is separated and precipitated at the interface. It was confirmed that there was. From this, it was confirmed as shown in Photo 1 that a uniform organic binder composition was obtained by using a polyolefin resin for the component (c).
本発明を用いることで、焼結可能な金属粉末を用いて、欠陥の無い健全な複雑形状の焼結体を得ることがでた。このことから、焼結体内部における膨れ・気泡の発生が大きな問題となる医療関連部品、自動車部品、通信機器部品への活用が促進すると思われる。 By using the present invention, it was possible to obtain a sintered body having a sound complex shape without defects by using a metal powder that can be sintered. From this, it is expected that the utilization for medical-related parts, automobile parts, and communication equipment parts, in which the generation of swelling and air bubbles inside the sintered body is a big problem, will be promoted.
本発明の有機化合物の成分（Ｂ）としては、脂肪酸エステル、脂肪酸アミド、フタル酸エステル、パラフィンワックス、マイクロクリスタリンワックス、ポリエチレンワックス、ポリプロピレンワックス、カルナバワックス、モンタン系ワックス、ウレタン化ワックス、無水マレイン酸変性ワックス、及びポリグリコール系化合物から選ばれる１種以上を用いることができる。用いられる有機化合物の添加量が３０体積％未満の場合には、成形時の流動性が悪くなり、成形体に割れ及びクラックが生じやすくなる。また、添加量が７０体積％よりも多くなると、成形時において成形体にバリが発生しやすくなり、成形体の強度が低下する恐れがある。成分（Ｂ）の添加量は３０〜７０体積％であるが、望ましい添加量は３５〜６０体積％であり、より望ましい添加量は４５〜５５体積％である。
更に成形体の流動性、靭性をさらに高めるためにアモルファスポリオレフィン樹脂、エチレン酢酸ビニル共重合体、エチレン・アクリル共重合体等のオレフィン系樹脂を添加してもよい。
The components (B) of the organic compound of the present invention include fatty acid ester, fatty acid amide, phthalic acid ester, paraffin wax, microcrystallin wax, polyethylene wax, polypropylene wax, carnauba wax, montan wax, urethanized wax, and maleic anhydride. One or more selected from modified waxes and polyglycol-based compounds can be used. When the amount of the organic compound used is less than 30% by volume, the fluidity at the time of molding is deteriorated, and cracks and cracks are likely to occur in the molded product. On the other hand, if the amount added is more than 70% by volume, burrs are likely to occur in the molded product during molding, and the strength of the molded product may decrease. The addition amount of the component (B) is 30 to 70% by volume, the desirable addition amount is 35 to 60% by volume, and the more desirable addition amount is 45 to 55% by volume.
Further, an olefin resin such as an amorphous polyolefin resin, an ethylene vinyl acetate copolymer, or an ethylene / acrylic copolymer may be added in order to further enhance the fluidity and toughness of the molded product.
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