JP4953511B2 - Foundry sand composition - Google Patents

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JP4953511B2
JP4953511B2 JP2001033136A JP2001033136A JP4953511B2 JP 4953511 B2 JP4953511 B2 JP 4953511B2 JP 2001033136 A JP2001033136 A JP 2001033136A JP 2001033136 A JP2001033136 A JP 2001033136A JP 4953511 B2 JP4953511 B2 JP 4953511B2
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fine particles
foundry sand
sand composition
average particle
hollow spherical
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JP2002239681A (en
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雅之 加藤
茂夫 仲井
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Kao Corp
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Kao Corp
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Description

【0001】
【発明の属する技術分野】
本発明は、流動性が改善された鋳物砂組成物に関し、複雑な鋳型や高強度の鋳型の造型に適した鋳物砂組成物に関するものである。なお、本発明において、鋳型とは中子をも含むものである。
【0002】
【従来の技術】
鋳型は、一般的に、種々の形状の模型(木型、発泡型、金型、中子型、割り型等の型と言われるもの全てを含む。)に鋳物砂組成物を充填し成形して造型される。鋳物砂組成物は、多くの場合、珪砂等の耐火性粒状骨材と粘結剤とを含有しており、この粘結剤によって耐火性粒状骨材相互間を結合させ、所定強度の鋳型を造型する。なお、場合によっては、鋳物砂組成物中に粘結剤が含有されておらず、耐火性粒状骨材だけで鋳型を造型することもある。
【0003】
ところが、模型が複雑な形状をしていると、鋳物砂組成物の充填が不良となることがあった。特に、鋳物砂組成物中に粘結剤が含有されていると、鋳物砂組成物の流動性が低下しやすく、充填不良となりやすい。従来、このような場合は、(i)熟練工による手作業によって手込め充填する方法、(ii)振動造型の場合は、強力な振動を与えて充填する方法、(iii )ブロー造型の場合は、強力なエアーブローによって充填する方法、等が講じられている。
【0004】
しかしながら、(i)の方法は、現在、鋳型造型の熟練工が少なく、かつ手作業であるため鋳型の生産効率が低下する、また、(ii)及び(iii )の方法は、骨材が模型に染み付き(模型に埋入し)、模型の抜き取りが困難になったり、模型として発泡型を使用した場合には、発泡型が破損或いは変形し、鋳型造型が不能になるということがある。
【0005】
このような欠点を解決するため、鋳物砂組成物の流動性を向上させ、その充填性を向上させる方法が種々提案されている。例えば、鋳物砂組成物中に流動性向上剤として、フッ素系界面活性剤を含有させる方法(特開平2−299741号公報)、脂肪族化合物を含有させる方法(特開平3−134067号公報)、界面活性剤や潤滑剤を含有させる方法(特開平10−216895号公報)等が提案されている。これら各方法は、いずれも、界面活性剤等の化学的特性を利用して、流動性を改善しようというものである。
【0006】
【発明が解決しようとする課題】
そこで、本発明者は、前記各方法とは全く異なった原理で、鋳物砂組成物の流動性を改善すべく、種々検討したところ、耐火性粒状骨材の粒径に対して、一定の粒径を持つ非中空球状微粒子を添加すれば、鋳物砂組成物の流動性が改善されることを見出した。つまり、所定の大きさの耐火性粒状骨材と所定の大きさの非中空球状微粒子とを混合すれば、全体としての鋳物砂組成物の流動性が改善されることを見出したのである。これは、耐火性粒状骨材と非中空球状微粒子との物理的相互作用で、鋳物砂組成物の流動性が改善されるというものであり、前記各方法とは、その原理が異なるものである。
【0007】
【課題を解決するための手段】
本発明は、平均粒径が100〜5000μmである耐火性粒状骨材100質量部に対して、平均粒径0.1〜50μmであり、その素材がシリカ,シリコーン系樹脂,アルミナ,ガラス,ムライト,ポリエチレン,ポリプロピレン,ポリスチレン,(メタ)アクリル酸系樹脂及びフッ素系樹脂よりなる群から選ばれたものである非中空球状微粒子が0.01〜1.0質量部配合されてなり、該耐火性粒状骨材の平均粒径をφとしたとき、該非中空球状微粒子の平均粒径が、φ/8〜φ/5000である鋳物砂組成物に関するものである。
【0008】
本発明で用いる耐火性粒状骨材としては、従来公知のものであれば、どのようなものでも使用することができる。例えば、珪砂、ジルコン砂、クロマイト砂、オリビン砂、ムライト砂等を使用することができる。耐火性粒状骨材の平均粒径は、100〜5000μmであり、特に200〜600μm程度が好ましい。耐火性粒状骨材の形状は任意であって良いが、球形の骨材を用いると、非中空球状微粒子との相乗作用で、より流動性の向上を図ることができる。耐火性粒状骨材の平均粒径は、JIS Z 2602記載の方法に準じ、メッシュによる篩い分けで、質量基準の50%径として求めたものである。なお、本発明で言う耐火性粒状骨材とは、主骨材を意味するものであり、主骨材に若干量添加される補助骨材は、本発明では任意の添加剤の範疇に属するものである。
【0009】
本発明において、流動性向上剤としての役割を果たすのは、非中空球状微粒子である。ここで、非中空球状微粒子の意味内容は、以下のとおりである。「非中空」とは、中空ではなく、中実ということである。中空微粒子を用いると、鋳物砂組成物の充填時に、微粒子が破損したり変形しやすく、流動性向上を図れなくなるので、本発明では用いることができない。また、破損或いは変性しなくても、中空微粒子はクッション作用があり、鋳物砂組成物の流動性を阻害しやすいので、本発明では用いることができない。「球状」ということは、表面に角がなくて、所定の曲率で丸くなっているということである。角があると、微粒子が耐火性粒状骨材相互間に存在していても、骨材相互間の滑りが悪くなり、流動性向上を図れないので、本発明では用いることができない。「微粒子」というのは、耐火性粒状骨材よりもその大きさが小さい粒子ということである。
【0010】
本発明においては、耐火性粒状骨材の大きさに対する、非中空球状微粒子の大きさに特徴がある。即ち、耐火性粒状骨材の平均粒径をφとしたとき、非中空球状微粒子の平均粒径がφ/8〜φ/5000、好ましくはφ/15〜φ/500であるということである。非中空球状微粒子の平均粒径がφ/8よりも大きいと、鋳物砂組成物の流動性の向上が不十分であり、好ましくない。また、非中空球状微粒子の平均粒径がφ/5000よりも小さい場合も、鋳物砂組成物の流動性の向上が不十分であり、好ましくない。
【0011】
非中空球状微粒子の平均粒径は、0.1〜50μmである。更に1〜30μmの範囲で選定するのが好ましい。この程度の平均粒径の非中空球状微粒子が、最も良く流動性向上に寄与するからである。なお、非中空球状微粒子の平均粒径は、レーザー回折計を用いて、質量基準の50%径として求めた。
【0012】
非中空球状微粒子としては、非中空であること、球状であること、所定の平均粒径を持つことの他、その素材として、シリカ,シリコーン系樹脂,アルミナ,ガラス,ムライト、ポリエチレン,ポリプロピレン,ポリスチレン,(メタ)アクリル酸系樹脂又はフッ素系樹脂が用いられる。無機材料では変形が少ない利点があり、有機材料では注湯時に熱分解し消失する利点がある。なお、有機材料の場合は、その軟化点が50℃以上、好ましくは80℃以上のものが良い。軟化点が50℃未満であると、鋳物砂組成物の混練時や造型時に、非中空球状微粒子が変形したり、粘着性を呈したりして、鋳物砂組成物の流動性が低下する恐れがある。また、素材表面がシリコン系化合物で処理されている非中空微粒子、好ましくはシリコーン系樹脂微粒子又はシリカ微粒子表面が珪素化合物を主体とする処理剤でシリコン処理された無機微粒子を用いるのが好ましい。これらは、流動性の向上と共に、得られる鋳型の圧縮強度の向上も見られ、好ましいものである。なお、珪素化合物を主体とする処理剤としては、ヘキサメチルジシラザン,トリメチルクロルシラン,トリメチルエトキシシラン,アリルフェニルジクロルシラン等のシランカップリング剤やシリコーンオイル等の珪素化合物を主体とする処理剤が用いられる。
【0013】
非中空球状微粒子の配合量は、耐火性粒状骨材100質量部に対して、0.01〜1.0質量部であ、0.05〜0.5質量部であるのがより好ましい。非中空球状微粒子の配合量が0.01質量部未満であると、鋳物砂組成物の流動性向上効果が不十分となる傾向が生じる。また、非中空球状微粒子の配合量が1.0質量部を超えると、得られる鋳型の強度が低下する傾向が生じたり、造型時に非中空球状微粒子が飛散する傾向が生じる。
【0014】
本発明に係る鋳物砂組成物中には、更に粘結剤が含有されているのが好ましい。即ち、鋳物砂組成物中に粘結剤が含有されている場合、特にその流動性が低下しやすいため、粘結剤含有鋳物砂組成物に本発明を適用するのが好ましい。粘結剤としても、従来公知のものであればどのようなものでも用いることができ、例えば、フラン樹脂,水溶性フェノール樹脂,耐火性粒状骨材表面に被覆されたノボラック型フェノール樹脂(シェル用粘結剤)、フェノールウレタン樹脂、水ガラス、粘土等を用いることができる。
【0015】
また、本発明に係る鋳物砂組成物中には、鋳肌をよくするため、砂落としをよくするため、すくわれ防止等の目的で、従来公知の各種の添加剤を含有させてもよい。例えば、補助骨材,石炭粉,ピッチ粉,コークス粉,黒鉛粉末,澱粉質添加剤,繊維素質添加剤,フッ素系界面活性剤,脂肪族活性剤,潤滑油等を適当量添加しても良い。
【0016】
本発明に係る鋳物砂組成物を、模型に充填して造型する方法としては、従来公知の造型法であればどのようなものでも採用でき、例えば、振動機を用いた振動造型法,エアーを用いたブロー造型法,圧力差を利用する減圧造型法,手込め造型法等を採用することができる。本発明に係る鋳物砂組成物の場合、手込め造型法よりも、機械を用いた振動造型法,ブロー造型法,減圧造型法等の方が、その効果が顕著である。また、本発明に係る鋳物砂組成物は、自硬性鋳型,ガス硬化性鋳型,フルモールド鋳型,シェルモールド鋳型等の鋳型の種別を問わず、適用しうるものであり、また粘結剤を含まない鋳型にも適用することができる。特に、本発明に係る鋳物砂組成物は、耐火性粒状骨材に大きな運動エネルギーを与えなくとも造型しうるので、複雑な形状をした中子の造型や、発泡模型を使用して造型する場合に有利である。
【0017】
【実施例】
以下、実施例に基づいて本発明を説明するが、本発明は実施例に限定されるものではない。本発明は、耐火性粒状骨材の粒径に対して、一定の粒径を持つ非中空球状微粒子を添加すれば、鋳物砂組成物の流動性が改善されるとの知見に基づくものとして、解釈されるべきである。
【0018】
実施例1
フリーマントル珪砂(平均粒径511μm)8kgに、フラン樹脂(花王クエーカー社製、340B)40gとフラン樹脂用硬化剤(花王クエーカー社製、C−21)16gを添加して、キッチンミキサーにて混練した。更に、非中空球状微粒子(電気化学工業社製、球状シリカ微粒子FB−6D、平均粒径6.9μm)8gを添加し混練して、鋳物砂組成物を得た。
【0019】
実施例2〜9
実施例1で用いた非中空球状微粒子に代えて、以下の非中空球状微粒子を用いる他は、実施例1と同様にして鋳物砂組成物を得た。実施例2は、信越化学工業社製、球状シリコーン系樹脂微粒子X−52−854、平均粒径0.8μmの非中空球状微粒子を使用した。実施例3は、信越化学工業社製、球状シリコーン系樹脂微粒子KMP590、平均粒径2.0μmの非中空球状微粒子を使用した。実施例4は、東芝シリコーン社製、球状シリコーン系樹脂微粒子トスパール3120、平均粒径12.0μmの非中空球状微粒子を使用した。実施例5は、信越化学工業社製、球状シリカ微粒子(表面をシリコン処理したもの)KMP105、平均粒径0.8μmの非中空球状微粒子を使用した。実施例6は、信越化学工業社製、球状シリカ微粒子(表面をシリコン処理したもの)KMP110、平均粒径1.9μmの非中空球状微粒子を使用した。実施例7は、電気化学工業社製、球状シリカ微粒子FB−60、平均粒径22.7μmの非中空球状微粒子を使用した。実施例8は、東芝バロティーニ社製、ガラスビーズEMB−10、平均粒径6.0μmの非中空球状微粒子を使用した。実施例9は、平均粒径50.0μmのガラスビーズを非中空球状微粒子として使用した。
【0020】
比較例1〜7
実施例1で用いた非中空球状微粒子に代えて、以下の微粒子を用いる他は、実施例1と同様にして鋳物砂組成物を得た。比較例1は、山森土本鉱業所製、不定形シリカ微粒子シリカA−3、平均粒径7.0μmの非中空不定形微粒子を使用した。比較例2は、山森土本鉱業所製、不定形シリカ微粒子シリカA−1、平均粒径17.0μmの非中空不定形微粒子を使用した。比較例3は、日本アエロジル社製、球状シリカ微粒子アエロジル130、平均粒径0.016μmの非中空球状微粒子を使用した。比較例4は、ムライト社製、球状ムライト微粒子セラビーズ1750、平均粒径75.0μmの非中空球状微粒子を使用した。比較例5は、平均粒径100μmのガラスビーズを非中空球状微粒子として使用した。比較例6は、日本フェライト社製、中空球状アルミナ微粒子Filite 52/7 FG、平均粒径100μmの中空球状微粒子を使用した。
また、比較例7は、非中空球状微粒子を使用しない他は、実施例1と同様にして得られた鋳物砂組成物である。
【0021】
実施例1〜9及び比較例1〜7で得られた鋳物砂組成物の流動性を評価するため、以下の試験を行った。まず、図1に示すような、略U字状の中空部(A−B−C)を持つ箱体を準備した。図1中、PSは発泡ポリスチレン体であり、表面にはPC100(花王クエーカー社製、塗型剤)が塗布されている。また、この箱体の寸法は、L1が8cm、L2が20cm、L3が17cm、L4が8cm、L5が8cm、L6が12cmである。この箱体の中空部Aに入るだけ、鋳物砂組成物を投入し、振動を開始した。振動を1分間行うと、鋳物砂組成物は中空部Bへ移動し、中空部Aの上部に空間が生じた。この空間に更に鋳物砂組成物を、全部で8kgとなるように投入し、今度は10分間振動を与えた。そうすると、鋳物砂組成物は、箱体の中空部Cに入って行き、図1に示すような状態(山状)となった。そして、発泡ポリスチレン体の底面から、山状鋳物砂組成物の頂上までの距離をaとし、山状鋳物砂組成物の裾までの距離をbとし、その平均値〔(a+b)/2〕を求め、これを充填高さ(cm)とし、その結果を表1に示した。充填高さが高いほど、鋳物砂組成物の流動性が良好であることを示している。なお、上記した振動は、東洋機械製作所製の垂直面真円運動振動機を用い、振動条件1.5G、振幅0.4mmで行った。
【0022】

Figure 0004953511
【0023】
表1の結果から明らかなように、実施例1〜9で得られた鋳物砂組成物は、比較例1〜7で得られたいずれの鋳物砂組成物よりも、充填高さが高く、流動性に優れていることが分かる。
【0024】
実施例10、11及び比較例8
実施例1で用いた非中空球状微粒子に代えて、以下の微粒子を用いる他は、実施例1と同様にして鋳物砂組成物を得た。実施例10は、日本精化社製、球状ポリエチレン微粒子フロービーズLE1080、平均粒径6.0μmの非中空球状微粒子を使用した。実施例11は、花王社製、球状架橋ポリスチレン微粒子PB−200、平均粒径8.0μmの非中空球状微粒子を使用した。比較例8は、日本精化社製、不定形ポリエチレン微粒子フローセンUF−80、平均粒径25.0の非中空不定形微粒子を使用した。
【0025】
実施例10、11及び比較例8で得られた鋳物砂組成物の流動性を評価するため、実施例1と同様の試験を行い、充填高さを求めた。そして、その結果を表2に示した。
Figure 0004953511
表2の結果から明らかなように、実施例10及び11で得られた鋳物砂組成物は、比較例で得られたいずれの鋳物砂組成物よりも、充填高さが高く、流動性に優れていることが分かる。
【0026】
実施例12及び比較例9
フラン樹脂及びフラン樹脂用硬化剤を使用しない他は、実施例1と同様にして鋳物砂組成物を得た(実施例12)。また、非中空球状微粒子を使用しない他は、実施例12と同様にして鋳物砂組成物を得た(比較例9)。そして、実施例12及び比較例9に係る鋳物砂組成物について、実施例1と同様の試験を行った。但し、実施例12及び比較例9に係る鋳物砂組成物は、無バインダーであるので、もともと流動性が良く、実施例1で評価した充填高さの値で流動性を評価するのが困難である。そこで、充填高さが7cmになるまでの時間を測定した。その結果、実施例12は80秒であり、比較例9は105秒であった。従って、実施例12に係る鋳物砂組成物の方が、比較例9に係るものよりも、流動性に優れていることが分かる。
【0027】
実施例13及び比較例10
実施例6で使用したフリーマントル珪砂に代えて、サンパール♯40(山川産業社製、マグネシウムスラグ、平均粒径455μm)を用いる他は、実施例6と同一の方法で鋳物砂組成物を得た(実施例13)。球状シリカ微粒子(表面をシリコン処理したもの)KMP110を使用しない他は、実施例6と同一の方法で鋳物砂組成物を得た(比較例10)。そして、実施例13及び比較例10に係る鋳物砂組成物について、その全投入量を9.2kgとする他は、実施例1と同様の試験を行い、充填高さを求めた。その結果、実施例13においては10.8cmであり、比較例10においては6.3cmであった。このことから、球状の耐火性粒状骨材を用いた場合でも、流動性が向上していることが分かる。
【0028】
実施例14
フラン再生砂(フラン鋳型の鋳物砂を再生したもの、平均粒径(414μm)2kgに、フラン樹脂(花王クエーカー社製、340B)14gとフラン樹脂用硬化剤(花王クエーカー社製、C−14)7gを添加して、キッチンミキサーにて混練した。更に、非中空球状微粒子(信越化学工業社製、球状シリコーン系樹脂微粒子KMP590、平均粒径2.0μm)2gを添加し混練して、鋳物砂組成物を得た。
【0029】
実施例15、16及び比較例11
実施例14で用いた非中空球状微粒子に代えて、以下の非中空球状微粒子を用いる他は、実施例14と同様にして鋳物砂組成物を得た(実施例15及び16)。実施例15は、信越化学工業社製、球状シリカ微粒子(表面をシリコン処理したもの)KMP110、平均粒径1.9μmの非中空球状微粒子を使用した。実施例16は、電気化学工業社製、球状シリカ微粒子FB−6D、平均粒径6.9μmの非中空球状微粒子を使用した。また、比較例11は、微粒子を用いない他は、実施例14と同様にして鋳物砂組成物を得た。
【0030】
実施例14〜16及び比較例11に係る鋳物砂組成物を用いて、φ50mm×50cmの大きさの鋳型圧縮強度測定用テストピース(圧縮強度測定用鋳型)を手込めで作成し、1日経過後の鋳型圧縮強度を測定した。また、このテストピースの重量と体積から、密度(充填密度:g/cm3)を求めた。この結果を表3に示した。なお、鋳型圧縮強度及び密度の測定は、25℃下において行った。
【0031】
Figure 0004953511
この結果から明らかなように、実施例14〜16で得られた鋳型は、比較例11で得られた鋳型に比べて、鋳物砂組成物の流動性が良いため、充填密度が高くなっていることが分かる。また、実施例14及び15で得られた鋳型は、比較例11で得られた鋳型に比べて、圧縮強度も向上していることが分かる。
【0032】
実施例17及び比較例12
フリーマントル珪砂(平均粒径511μm)2kgに、自硬性用水溶性アルカリフェノール樹脂(花王クエーカー社製、S660)30gと水溶性アルカリフェノール樹脂用硬化剤(花王クエーカー社製、Q×140)6gを添加して、キッチンミキサーにて混練した。更に、非中空球状微粒子(信越化学工業社製、球状シリカ微粒子(表面をシリコン処理したもの)KMP110、平均粒径1.9μm)2gを添加し混練して、鋳物砂組成物を得た(実施例17)。
また、非中空球状微粒子を用いない他は、実施例17と同様にして鋳物砂組成物を得た(比較例12)。
【0033】
実施例17及び比較例12に係る鋳物砂組成物を用いて、実施例14と同様に、φ50mm×50cmの大きさの鋳型圧縮強度測定用テストピース(圧縮強度測定用鋳型)を手込めで作成し、1日経過後の鋳型圧縮強度を測定した。また、実施例14と同様に、このテストピースの密度(充填密度:g/cm3)を求めた。この結果、実施例17では、圧縮強度が2.53MPaで、充填密度が1.69g/cm3であった。比較例12では、圧縮強度が2.43MPaで、充填密度が1.65g/cm3であった。この結果から、実施例17で得られた鋳型は、比較例12で得られた鋳型に比べて、鋳物砂組成物の流動性が良いため、充填密度が高くなっており、更に圧縮強度も高くなっていることが分かる。
【0034】
実施例18及び比較例13
6号珪砂(平均粒径266μm)2kgに、炭酸ガス硬化用水溶性アルカリフェノール樹脂(花王クエーカー社製、C800)60gを添加して、キッチンミキサーにて混練した。更に、非中空球状微粒子(信越化学工業社製、球状シリカ微粒子(表面をシリコン処理したもの)KMP105、平均粒径0.8μm)6gを添加し混練して、鋳物砂組成物を得た(実施例18)。
また、非中空球状微粒子を用いない他は、実施例18と同様にして鋳物砂組成物を得た(比較例13)。
【0035】
実施例18及び比較例13に係る鋳物砂組成物を用いて、炭酸ガスを通気させることにより、水溶性アルカリフェノール樹脂を硬化させて、φ50mm×50cmの大きさの鋳型圧縮強度測定用テストピース(圧縮強度測定用鋳型)を作成し、直ちに鋳型圧縮強度を測定した。また、このテストピースの密度(充填密度:g/cm3)を求めた。この結果、実施例18では、圧縮強度が2.79MPaで、充填密度が1.42g/cm3であった。比較例13では、圧縮強度が2.50MPaで、充填密度が1.35g/cm3であった。この結果から、実施例18で得られた鋳型は、比較例13で得られた鋳型に比べて、鋳物砂組成物の流動性が良いため、充填密度が高くなっており、更に圧縮強度が高くなっていることが分かる。
【0036】
実施例19及び比較例14
フラタリー珪砂(平均粒径246μm)100質量部に、フランウォームボックス用樹脂(花王クエーカー社製、730)1.6質量部、フランウォームボックス用硬化剤(花王クエーカー社製、FC−310)0.48質量部及びフランウォームボックス用添加剤(花王クエーカー社製、J−20)0.1質量部を添加して、混練した。更に、非中空球状微粒子(信越化学工業社製、球状シリカ微粒子(表面をシリコン処理したもの)KMP105、平均粒径0.8μm)0.1質量部を添加し混練して、鋳物砂組成物を得た(実施例19)。
また、非中空球状微粒子を用いない他は、実施例19と同様にして鋳物砂組成物を得た(比較例14)。
【0037】
実施例19及び比較例14で得られた鋳物砂組成物を、予め180℃に加熱した25mm×25mm×250mmの金型内に加熱空気と共に吹き込んで充填し、10秒間焼成して鋳型を得た。焼成後、1日経過後の抗折強度と充填密度を測定した。その結果、実施例19で得られた鋳型の抗折強度は6.54MPaで、充填密度は1.532g/cm3であった。一方、比較例14で得られた鋳型の抗折強度は6.34MPaで、充填密度は1.501g/cm3であった。従って、実施例19で得られた鋳型は、比較例14で得られた鋳型に比べて、鋳物砂組成物の流動性が良いため、充填密度が高くなっており、更に圧縮強度が高くなっていることが分かる。
【0038】
【発明の効果】
以上説明したように、本発明に係る鋳物砂組成物は、耐火性粒状骨材と、この耐火性粒状骨材の平均粒径に対して、所定比の平均粒径を持つ非中空球状微粒子とを含有するもので、非中空球状微粒子の介在によって、耐火性粒状骨材が流動しやすくなる。従って、模型に鋳物砂組成物を充填しやすくなると共に、模型の形状が複雑であっても、その複雑な空間部にも充填しやすくなり、全体として充填密度が高く、複雑な鋳型を製造しやすくなるという効果を奏する。また、模型に鋳物砂組成物を充填する際、組成物に過大な運動エネルギーを与えることなく、充填しうるので、模型への鋳物砂組成物の染み付きを防止しうると共に、模型が発泡模型のような場合には、模型の変形や破損をも防止しうるという効果を奏する。
【図面の簡単な説明】
【図1】鋳物砂組成物の流動性を評価するために用いた箱体の模式的斜視図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a foundry sand composition with improved fluidity, and more particularly to a foundry sand composition suitable for molding a complex mold or a high-strength mold. In the present invention, the mold includes a core.
[0002]
[Prior art]
The mold is generally formed by filling a molding sand composition into models of various shapes (including all types of molds such as wooden molds, foam molds, molds, core molds, and split molds). And molded. In many cases, the molding sand composition contains a refractory granular aggregate such as silica sand and a binder, and the refractory granular aggregate is bonded to each other by the binder to form a mold having a predetermined strength. Molding. In some cases, the foundry sand composition does not contain a binder, and the mold may be formed only from the refractory granular aggregate.
[0003]
However, when the model has a complicated shape, filling of the foundry sand composition may be poor. In particular, when a binder is contained in the foundry sand composition, the fluidity of the foundry sand composition is likely to decrease, and poor filling tends to occur. Conventionally, in such a case, (i) a method of manually filling by a skilled worker, (ii) in the case of vibration molding, a method of filling with strong vibration, (iii) in the case of blow molding, A method of filling by a powerful air blow is taken.
[0004]
However, since the method (i) currently has few skilled mold makers and is a manual work, the production efficiency of the mold is reduced. In the methods (ii) and (iii), the aggregate is used as a model. When the stain is embedded (embedded in the model), it becomes difficult to remove the model, or when the foaming mold is used as the model, the foaming mold may be damaged or deformed, and the mold making may become impossible.
[0005]
In order to solve such drawbacks, various methods for improving the fluidity of the foundry sand composition and improving the filling property have been proposed. For example, a method of containing a fluorosurfactant as a fluidity improver in a foundry sand composition (JP-A-2-299741), a method of containing an aliphatic compound (JP-A-3-134667), A method of incorporating a surfactant or a lubricant (Japanese Patent Laid-Open No. 10-216895) has been proposed. Each of these methods is intended to improve fluidity by utilizing chemical properties such as a surfactant.
[0006]
[Problems to be solved by the invention]
Therefore, the present inventor made various studies to improve the fluidity of the foundry sand composition on the basis of completely different principles from the above-mentioned methods. It has been found that if non-hollow spherical fine particles having a diameter are added, the fluidity of the foundry sand composition is improved. That is, it has been found that the fluidity of the foundry sand composition as a whole can be improved by mixing a refractory granular aggregate of a predetermined size and non-hollow spherical fine particles of a predetermined size. This is a physical interaction between the refractory granular aggregate and the non-hollow spherical fine particles, and the fluidity of the foundry sand composition is improved. The principle of each method is different. .
[0007]
[Means for Solving the Problems]
The present invention is, with respect to the average particle size of the refractory granular aggregate 100 parts by weight is 100~5000Myuemu, Ri average particle size 0.1~50μm der, the material is silica, silicone resin, alumina, glass, Non-hollow spherical fine particles selected from the group consisting of mullite, polyethylene, polypropylene, polystyrene, (meth) acrylic acid resin and fluorine resin are blended in an amount of 0.01 to 1.0 parts by mass, and the fire resistance This relates to a foundry sand composition in which the average particle size of the non-hollow spherical fine particles is φ / 8 to φ / 5000, where φ is the average particle size of the porous granular aggregate.
[0008]
As the refractory granular aggregate used in the present invention, any conventionally known aggregate can be used. For example, quartz sand, zircon sand, chromite sand, olivine sand, mullite sand and the like can be used. The average particle diameter of the refractory granular aggregate is 100 to 5000 μm , and particularly preferably about 200 to 600 μm. The shape of the refractory granular aggregate may be arbitrary, but if a spherical aggregate is used, the fluidity can be further improved by synergistic action with the non-hollow spherical fine particles. The average particle diameter of the refractory granular aggregate is determined as a 50% diameter based on mass by sieving with a mesh in accordance with the method described in JIS Z2602. The fire-resistant granular aggregate in the present invention means the main aggregate, and the auxiliary aggregate added to the main aggregate in a small amount belongs to the category of any additive in the present invention. It is.
[0009]
In the present invention, the non-hollow spherical fine particles play a role as a fluidity improver. Here, the meaning content of the non-hollow spherical fine particles is as follows. “Non-hollow” means solid rather than hollow. When hollow fine particles are used, the fine particles are easily damaged or deformed when the molding sand composition is filled, and the fluidity cannot be improved, so that it cannot be used in the present invention. Further, even if they are not damaged or denatured, the hollow fine particles have a cushioning action and are liable to hinder the fluidity of the foundry sand composition, and therefore cannot be used in the present invention. “Spherical” means that the surface has no corners and is rounded with a predetermined curvature. If there are corners, even if fine particles are present between the refractory granular aggregates, slippage between the aggregates deteriorates and fluidity cannot be improved, and therefore cannot be used in the present invention. “Fine particles” means particles that are smaller in size than refractory granular aggregates.
[0010]
The present invention is characterized by the size of the non-hollow spherical fine particles relative to the size of the refractory granular aggregate. That is, when the average particle diameter of the refractory granular aggregate is φ, the average particle diameter of the non-hollow spherical fine particles is φ / 8 to φ / 5000, preferably φ / 15 to φ / 500. If the average particle diameter of the non-hollow spherical fine particles is larger than φ / 8, the improvement of the fluidity of the foundry sand composition is insufficient, which is not preferable. Moreover, when the average particle diameter of the non-hollow spherical fine particles is smaller than φ / 5000, the improvement of the fluidity of the foundry sand composition is insufficient, which is not preferable.
[0011]
The average particle diameter of the non-hollow spherical fine particles is 0.1 to 50 μm . Furthermore, it is preferable to select in the range of 1 to 30 μm. This is because the non-hollow spherical fine particles having an average particle size of this level most contribute to the improvement of fluidity. The average particle diameter of the non-hollow spherical fine particles was determined as a 50% diameter based on mass using a laser diffractometer.
[0012]
Non hollow spherical fine particles, it is non-hollow, it is spherical, other have a predetermined average particle size, as the material, silica, silicone resin, alumina, glass, mullite, polyethylene, polypropylene, polystyrene , (Meth) acrylic acid resins or fluorine resins are used. Inorganic materials have the advantage of less deformation, and organic materials have the advantage of thermally decomposing and disappearing during pouring. In the case of an organic material, the softening point is 50 ° C. or higher, preferably 80 ° C. or higher. When the softening point is less than 50 ° C., the non-hollow spherical fine particles may be deformed or become sticky during kneading or molding of the foundry sand composition, which may reduce the fluidity of the foundry sand composition. is there. The non-hollow particles material surface has been treated with a silicon compound, preferably to use a silicon-treated inorganic fine particles with a treating agent is silicone resin particles or silica fine particle surface mainly containing silicon compound. These are preferable because the flowability is improved and the compression strength of the resulting mold is improved. In addition, as a processing agent mainly composed of a silicon compound, a processing agent mainly composed of a silicon compound such as a silane coupling agent such as hexamethyldisilazane, trimethylchlorosilane, trimethylethoxysilane, or allylphenyldichlorosilane, or silicone oil. Is used.
[0013]
The amount of non-hollow spherical fine particles, to the refractory granular aggregate 100 parts by weight of 0.01 to 1.0 parts by mass der is, more preferably 0.05 to 0.5 parts by weight. When the blending amount of the non-hollow spherical fine particles is less than 0.01 parts by mass, the fluidity improving effect of the foundry sand composition tends to be insufficient. On the other hand, when the blending amount of the non-hollow spherical fine particles exceeds 1.0 part by mass, the strength of the obtained mold tends to decrease, or the non-hollow spherical fine particles tend to scatter during molding.
[0014]
The foundry sand composition according to the present invention preferably further contains a binder. That is, when the binder is contained in the foundry sand composition, the fluidity is particularly likely to be lowered. Therefore, the present invention is preferably applied to the binder-containing foundry sand composition. As the binder, any conventionally known binder can be used. For example, a furan resin, a water-soluble phenol resin, a novolac type phenol resin coated on the surface of a refractory granular aggregate (for a shell) Binder), phenol urethane resin, water glass, clay and the like can be used.
[0015]
The foundry sand composition according to the present invention may contain conventionally known various additives for the purpose of preventing scuffing and the like in order to improve the casting surface and sand removal. For example, an appropriate amount of auxiliary aggregate, coal powder, pitch powder, coke powder, graphite powder, starchy additive, fiber base additive, fluorosurfactant, aliphatic activator, lubricating oil, etc. may be added. .
[0016]
As a method for molding a molding sand composition according to the present invention by filling a model, any conventionally known molding method can be adopted. For example, a vibration molding method using a vibrator, air can be used. The blow molding method used, the reduced pressure molding method using the pressure difference, the manual molding method, etc. can be employed. In the case of the foundry sand composition according to the present invention, the effects of the vibration molding method using a machine, the blow molding method, the reduced pressure molding method and the like are more remarkable than the manual molding method. The foundry sand composition according to the present invention is applicable regardless of the type of mold such as a self-hardening mold, a gas-curing mold, a full mold mold, and a shell mold mold, and contains a binder. It can be applied to molds that do not exist. In particular, since the foundry sand composition according to the present invention can be molded without giving large kinetic energy to the refractory granular aggregate, it is possible to mold a core having a complicated shape or a foam model. Is advantageous.
[0017]
【Example】
EXAMPLES Hereinafter, although this invention is demonstrated based on an Example, this invention is not limited to an Example. The present invention is based on the knowledge that if the non-hollow spherical fine particles having a constant particle size are added to the particle size of the refractory granular aggregate, the fluidity of the foundry sand composition is improved. Should be interpreted.
[0018]
Example 1
40 g of furan resin (manufactured by Kao Quaker, 340B) and 16 g of furan resin curing agent (K-21, manufactured by Kao Quaker, C-21) are added to 8 kg of free mantle silica sand (average particle size 511 μm) and kneaded with a kitchen mixer. did. Furthermore, 8 g of non-hollow spherical fine particles (manufactured by Denki Kagaku Kogyo Co., Ltd., spherical silica fine particles FB-6D, average particle size 6.9 μm) were added and kneaded to obtain a foundry sand composition.
[0019]
Examples 2-9
A casting sand composition was obtained in the same manner as in Example 1 except that the following non-hollow spherical fine particles were used instead of the non-hollow spherical fine particles used in Example 1. In Example 2, spherical silicone resin fine particles X-52-854 manufactured by Shin-Etsu Chemical Co., Ltd. and non-hollow spherical fine particles having an average particle diameter of 0.8 μm were used. In Example 3, spherical silicone resin fine particles KMP590 manufactured by Shin-Etsu Chemical Co., Ltd. and non-hollow spherical fine particles having an average particle size of 2.0 μm were used. In Example 4, non-hollow spherical fine particles having an average particle size of 12.0 μm and spherical silicone resin fine particles Tospearl 3120 manufactured by Toshiba Silicone Co., Ltd. were used. In Example 5, spherical silica fine particles (surface-treated silicon) KMP105 manufactured by Shin-Etsu Chemical Co., Ltd., non-hollow spherical fine particles having an average particle size of 0.8 μm were used. Example 6 used Shin-Etsu Chemical Co., Ltd., spherical silica fine particles (surface treated with silicon) KMP110, non-hollow spherical fine particles having an average particle size of 1.9 μm. In Example 7, spherical silica fine particles FB-60 manufactured by Denki Kagaku Kogyo Co., Ltd., non-hollow spherical fine particles having an average particle size of 22.7 μm were used. In Example 8, non-hollow spherical fine particles having an average particle diameter of 6.0 μm and glass beads EMB-10 manufactured by Toshiba Ballotini Co., Ltd. were used. In Example 9, glass beads having an average particle diameter of 50.0 μm were used as non-hollow spherical fine particles.
[0020]
Comparative Examples 1-7
A foundry sand composition was obtained in the same manner as in Example 1 except that the following fine particles were used instead of the non-hollow spherical fine particles used in Example 1. In Comparative Example 1, non-hollow amorphous fine particles having an average particle diameter of 7.0 μm and amorphous silica fine particle silica A-3 manufactured by Yamamori Tsuchimoto Mining Co., Ltd. were used. Comparative Example 2 used non-hollow amorphous fine particles having an average particle diameter of 17.0 μm, manufactured by Yamamori Tsuchimoto Mining Co., Ltd., amorphous silica fine particles silica A-1. In Comparative Example 3, spherical silica fine particles Aerosil 130 manufactured by Nippon Aerosil Co., Ltd. and non-hollow spherical fine particles having an average particle diameter of 0.016 μm were used. In Comparative Example 4, spherical mullite fine particle Cera beads 1750 manufactured by Mullite Co., Ltd., and non-hollow spherical fine particles having an average particle diameter of 75.0 μm were used. In Comparative Example 5, glass beads having an average particle diameter of 100 μm were used as non-hollow spherical fine particles. In Comparative Example 6, hollow spherical fine particles having a hollow spherical alumina fine particle Filite 52/7 FG and an average particle size of 100 μm manufactured by Nippon Ferrite Co., Ltd. were used.
Comparative Example 7 is a foundry sand composition obtained in the same manner as in Example 1 except that non-hollow spherical fine particles are not used.
[0021]
In order to evaluate the fluidity of the foundry sand compositions obtained in Examples 1 to 9 and Comparative Examples 1 to 7, the following tests were performed. First, a box having a substantially U-shaped hollow portion (ABC) as shown in FIG. 1 was prepared. In FIG. 1, PS is a foamed polystyrene body, and PC100 (a coating agent made by Kao Quaker) is applied to the surface. The dimensions of this box are L 1 is 8 cm, L 2 is 20 cm, L 3 is 17 cm, L 4 is 8 cm, L 5 is 8 cm, and L 6 is 12 cm. As long as it entered the hollow portion A of the box, the casting sand composition was charged and vibration was started. When the vibration was carried out for 1 minute, the foundry sand composition moved to the hollow part B, and a space was created above the hollow part A. The foundry sand composition was further introduced into this space so that the total amount was 8 kg, and this time, vibration was applied for 10 minutes. As a result, the foundry sand composition entered the hollow portion C of the box and became a state (mountain shape) as shown in FIG. And, the distance from the bottom of the expanded polystyrene body to the top of the chevron casting sand composition is a, the distance to the hem of the chevron casting sand composition is b, and the average value [(a + b) / 2] This was determined as the filling height (cm), and the results are shown in Table 1. The higher the filling height, the better the fluidity of the foundry sand composition. The vibration described above was performed using a vertical circular motion vibrator manufactured by Toyo Kikai Seisakusho under vibration conditions of 1.5 G and an amplitude of 0.4 mm.
[0022]
Figure 0004953511
[0023]
As is clear from the results in Table 1, the foundry sand compositions obtained in Examples 1 to 9 have a higher filling height and flow than any of the foundry sand compositions obtained in Comparative Examples 1 to 7. It turns out that it is excellent in property.
[0024]
Examples 10 and 11 and Comparative Example 8
A foundry sand composition was obtained in the same manner as in Example 1 except that the following fine particles were used instead of the non-hollow spherical fine particles used in Example 1. In Example 10, spherical polyethylene fine particle flow beads LE1080 manufactured by Nippon Seika Co., Ltd. and non-hollow spherical fine particles having an average particle size of 6.0 μm were used. In Example 11, spherical cross-linked polystyrene fine particles PB-200 manufactured by Kao Corporation and non-hollow spherical fine particles having an average particle size of 8.0 μm were used. In Comparative Example 8, non-hollow amorphous fine particles having an average particle diameter of 25.0, produced by Nippon Seika Co., Ltd., irregular polyethylene fine particle FLOWSEN UF-80, were used.
[0025]
In order to evaluate the fluidity of the foundry sand compositions obtained in Examples 10 and 11 and Comparative Example 8, the same test as in Example 1 was performed to determine the filling height. The results are shown in Table 2.
Figure 0004953511
As is apparent from the results in Table 2, the foundry sand compositions obtained in Examples 10 and 11 have a higher filling height and superior fluidity than any of the foundry sand compositions obtained in the comparative examples. I understand that
[0026]
Example 12 and Comparative Example 9
A foundry sand composition was obtained in the same manner as in Example 1 except that the furan resin and the curing agent for furan resin were not used (Example 12). A foundry sand composition was obtained in the same manner as in Example 12 except that non-hollow spherical fine particles were not used (Comparative Example 9). And about the foundry sand composition which concerns on Example 12 and Comparative Example 9, the test similar to Example 1 was done. However, since the foundry sand compositions according to Example 12 and Comparative Example 9 have no binder, the fluidity is originally good, and it is difficult to evaluate the fluidity with the value of the filling height evaluated in Example 1. is there. Therefore, the time until the filling height reached 7 cm was measured. As a result, Example 12 was 80 seconds and Comparative Example 9 was 105 seconds. Therefore, it turns out that the direction of the foundry sand composition according to Example 12 is superior in fluidity to that according to Comparative Example 9.
[0027]
Example 13 and Comparative Example 10
A foundry sand composition was obtained in the same manner as in Example 6 except that Sunpearl # 40 (manufactured by Yamakawa Sangyo Co., Ltd., magnesium slag, average particle size of 455 μm) was used instead of Fremantle quartz sand used in Example 6. (Example 13). A molding sand composition was obtained in the same manner as in Example 6 except that spherical silica fine particles (surface treated with silicon) KMP110 were not used (Comparative Example 10). And about the foundry sand composition which concerns on Example 13 and Comparative Example 10, the test similar to Example 1 was conducted except the total input amount having been set to 9.2 kg, and filling height was calculated | required. As a result, it was 10.8 cm in Example 13, and 6.3 cm in Comparative Example 10. This shows that the fluidity is improved even when a spherical refractory granular aggregate is used.
[0028]
Example 14
Furan reclaimed sand (regenerated fur sand casting, average particle size (414 μm) 2 kg, furan resin (Kao Quaker, 340B) 14 g and furan resin curing agent (Kao Quaker, C-14) 7 g was added and kneaded with a kitchen mixer, and 2 g of non-hollow spherical fine particles (Shin-Etsu Chemical Co., Ltd., spherical silicone resin fine particles KMP590, average particle size 2.0 μm) were added and kneaded to form sand. A composition was obtained.
[0029]
Examples 15 and 16 and Comparative Example 11
A casting sand composition was obtained in the same manner as in Example 14 except that the following non-hollow spherical fine particles were used instead of the non-hollow spherical fine particles used in Example 14 (Examples 15 and 16). In Example 15, spherical silica fine particles (surface treated with silicon) KMP110 manufactured by Shin-Etsu Chemical Co., Ltd., non-hollow spherical fine particles having an average particle size of 1.9 μm were used. In Example 16, non-hollow spherical fine particles having an average particle diameter of 6.9 μm, spherical silica fine particles FB-6D manufactured by Denki Kagaku Kogyo Co., Ltd. were used. Moreover, the comparative example 11 obtained the foundry sand composition like Example 14 except not using microparticles | fine-particles.
[0030]
Using the foundry sand compositions according to Examples 14 to 16 and Comparative Example 11, a test piece for measuring mold compressive strength (compressed mold for measuring compressive strength) having a size of φ50 mm × 50 cm was prepared by hand and one day later. The mold compressive strength was measured. Further, the density (filling density: g / cm 3 ) was determined from the weight and volume of the test piece. The results are shown in Table 3. The mold compression strength and density were measured at 25 ° C.
[0031]
Figure 0004953511
As is apparent from the results, the molds obtained in Examples 14 to 16 have a higher packing density because the casting sand composition has better fluidity than the mold obtained in Comparative Example 11. I understand that. In addition, it can be seen that the molds obtained in Examples 14 and 15 have improved compressive strength as compared with the mold obtained in Comparative Example 11.
[0032]
Example 17 and Comparative Example 12
30 g of water-soluble alkali phenol resin for self-hardening (S660, manufactured by Kao Quaker Co., Ltd.) and 6 g of a curing agent for water-soluble alkali phenol resin (manufactured by Kao Quaker Co., Ltd., Q × 140) are added to 2 kg of Fremantle quartz sand (average particle size 511 μm) And kneaded with a kitchen mixer. Further, 2 g of non-hollow spherical fine particles (manufactured by Shin-Etsu Chemical Co., Ltd., spherical silica fine particles (surface treated with silicon) KMP110, average particle size 1.9 μm) were added and kneaded to obtain a casting sand composition (implementation) Example 17).
A foundry sand composition was obtained in the same manner as in Example 17 except that non-hollow spherical fine particles were not used (Comparative Example 12).
[0033]
Using the foundry sand composition according to Example 17 and Comparative Example 12, as in Example 14, a mold compression strength measurement test piece (compression strength measurement mold) having a size of φ50 mm × 50 cm was prepared manually. The mold compressive strength after 1 day was measured. Moreover, the density (filling density: g / cm 3 ) of this test piece was determined in the same manner as in Example 14. As a result, in Example 17, the compressive strength was 2.53 MPa, and the packing density was 1.69 g / cm 3 . In Comparative Example 12, the compressive strength was 2.43 MPa, and the packing density was 1.65 g / cm 3 . From this result, the mold obtained in Example 17 has a higher packing density and a higher compressive strength because the casting sand composition has better fluidity than the mold obtained in Comparative Example 12. You can see that
[0034]
Example 18 and Comparative Example 13
To 2 kg of No. 6 silica sand (average particle size: 266 μm), 60 g of a water-soluble alkali phenol resin for curing carbon dioxide (C800, manufactured by Kao Quaker) was added and kneaded with a kitchen mixer. Furthermore, 6 g of non-hollow spherical fine particles (manufactured by Shin-Etsu Chemical Co., Ltd., spherical silica fine particles (surface treated with silicon) KMP105, average particle size 0.8 μm) were added and kneaded to obtain a molding sand composition (implementation) Example 18).
A foundry sand composition was obtained in the same manner as in Example 18 except that the non-hollow spherical fine particles were not used (Comparative Example 13).
[0035]
Using the foundry sand composition according to Example 18 and Comparative Example 13, the water-soluble alkali phenol resin was cured by aeration of carbon dioxide gas, and a test piece for measuring the mold compressive strength having a size of φ50 mm × 50 cm ( A mold for compressive strength measurement) was prepared, and the mold compressive strength was measured immediately. Moreover, the density (packing density: g / cm 3 ) of this test piece was determined. As a result, in Example 18, the compressive strength was 2.79 MPa, and the packing density was 1.42 g / cm 3 . In Comparative Example 13, the compressive strength was 2.50 MPa and the packing density was 1.35 g / cm 3 . From this result, the mold obtained in Example 18 has a higher packing density and higher compressive strength because the casting sand composition has better fluidity than the mold obtained in Comparative Example 13. You can see that
[0036]
Example 19 and Comparative Example 14
100 parts by mass of flattery silica sand (average particle size: 246 μm), 1.6 parts by mass of furan worm box resin (Kao Quaker, 730), furan worm box curing agent (Kao Quaker, FC-310) 48 parts by mass and 0.1 part by mass of an additive for furan worm box (J-20, manufactured by Kao Quaker) were added and kneaded. Furthermore, 0.1 parts by mass of non-hollow spherical fine particles (manufactured by Shin-Etsu Chemical Co., Ltd., spherical silica fine particles (surface treated with silicon) KMP105, average particle size 0.8 μm) were added and kneaded to obtain a molding sand composition. Obtained (Example 19).
A foundry sand composition was obtained in the same manner as in Example 19 except that the non-hollow spherical fine particles were not used (Comparative Example 14).
[0037]
The foundry sand compositions obtained in Example 19 and Comparative Example 14 were blown into a 25 mm × 25 mm × 250 mm mold preheated to 180 ° C. with heated air and baked for 10 seconds to obtain a mold. . After firing, the bending strength and packing density after 1 day were measured. As a result, the mold strength of the mold obtained in Example 19 was 6.54 MPa, and the packing density was 1.532 g / cm 3 . On the other hand, the bending strength of the mold obtained in Comparative Example 14 was 6.34 MPa, and the packing density was 1.501 g / cm 3 . Therefore, the mold obtained in Example 19 has a higher packing density and a higher compressive strength because the fluidity of the foundry sand composition is better than the mold obtained in Comparative Example 14. I understand that.
[0038]
【Effect of the invention】
As explained above, the foundry sand composition according to the present invention comprises a refractory granular aggregate and non-hollow spherical fine particles having an average particle diameter of a predetermined ratio with respect to the average particle diameter of the refractory granular aggregate. The refractory granular aggregate becomes easy to flow due to the inclusion of non-hollow spherical fine particles. Therefore, it becomes easy to fill the model with the foundry sand composition, and even if the shape of the model is complex, it is easy to fill the complex space, and the overall packing density is high, and a complicated mold is manufactured. There is an effect that it becomes easy. In addition, when the casting sand composition is filled into the model, it can be filled without giving excessive kinetic energy to the composition, so that it is possible to prevent the casting sand composition from sticking to the model and the model is made of the foam model. In such a case, there is an effect that deformation and breakage of the model can be prevented.
[Brief description of the drawings]
FIG. 1 is a schematic perspective view of a box used for evaluating the fluidity of a foundry sand composition.

Claims (3)

平均粒径が100〜5000μmである耐火性粒状骨材100質量部に対して、平均粒径0.1〜50μmであり、その素材がシリカ,シリコーン系樹脂,アルミナ,ガラス,ムライト,ポリエチレン,ポリプロピレン,ポリスチレン,(メタ)アクリル酸系樹脂及びフッ素系樹脂よりなる群から選ばれたものである非中空球状微粒子が0.01〜1.0質量部配合されてなり、該耐火性粒状骨材の平均粒径をφとしたとき、該非中空球状微粒子の平均粒径が、φ/8〜φ/5000である鋳物砂組成物。Relative refractory granular aggregate 100 parts by weight of the average particle diameter of 100~5000Myuemu, Ri average particle size 0.1~50μm der, the material is silica, silicone resin, alumina, glass, mullite, polyethylene, Non-hollow spherical fine particles selected from the group consisting of polypropylene, polystyrene, (meth) acrylic acid resins, and fluorine resins are blended in an amount of 0.01 to 1.0 parts by mass, and the refractory granular aggregate A foundry sand composition in which the average particle size of the non-hollow spherical fine particles is φ / 8 to φ / 5000, where φ is the average particle size. 更に粘結剤を含有する請求項1記載の鋳物砂組成物。  The foundry sand composition according to claim 1, further comprising a binder. 非中空球状微粒子の素材表面がシリコン系化合物で処理されている請求項1又は2に記載の鋳物砂組成物。Foundry sand composition according to claim 1 or 2 material surface of the non-hollow spherical fine particles are treated with a silicon compound.
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