JP4367807B2

JP4367807B2 - Cleaning method

Info

Publication number: JP4367807B2
Application number: JP32581299A
Authority: JP
Inventors: 知巳岡田; 景太松下; 康也三村
Original assignee: Japan Energy Corp
Current assignee: Eneos Corp
Priority date: 1999-11-16
Filing date: 1999-11-16
Publication date: 2009-11-18
Anticipated expiration: 2019-11-16
Also published as: TW491950B; MY132651A; JP2001137792A

Description

【０００１】
【発明の属する技術分野】
本発明は、機械部品、電気電子部品、光学部品などの洗浄方法に関する。
【０００２】
【従来の技術】
電気電子部品、機械部品、精密部品、光学部品などの表面に付着した汚れの除去には、従来、各種の洗浄剤が用いられている。代表的な洗浄剤である塩素系あるいはフロン系洗浄剤は、難燃性で洗浄性に優れているため多く使用されてきた。しかし、これらは、オゾン層破壊、地球温暖化の原因物質として世界的にその使用が厳しく制限されてきており、今後更に厳しく規制されるものと予想される。類似化合物のトリクレン、塩化メチレンなども用いられてきたが塩素系溶剤のため毒性が強く健康上及び環境汚染上問題がある。このため、これらに代る洗浄剤として、これまで多くの水系又は溶媒系の洗浄剤が提案されてきている。
近年、環境汚染が少なく安全性の高い洗浄剤としてリモネン、ピネン、ジぺンテン等のテルペン類を用いた例が米国特許第４５１１４８８号明細書、特表昭６３−５０１９０８号公報（米国特許第４６４０７１９号明細書及び同第４７４０２４７号明細書）等に提案されている。しかし、リモネンに代表されるテルペン類は、特定の植物に微量含まれる天然物由来の化合物であるため高価でかつ供給量に限界があるばかりでなく、使用時の耐久性に問題がある。
また、界面活性剤に苛性ソーダやオルトケイ酸ソーダなどのビルダーを配合した水系洗浄剤もある。水系洗浄剤は洗浄力が劣る上、錆発生、光学レンズについては白やけ、青やけ等の致命的な不良の原因にもなり、更に再生が難しく専用の廃液処理設備を必要とする。
【０００３】
ピッチ（重合反応器付着物）の洗浄にN-メチルピロリドンを用いる方法が特公昭５１−２９１９５に提案されている。しかし、N-メチルピロリドンはプラスチック材料を強く劣化させるためプラスチック部分を含む対象物の洗浄には不向きであり、更に吸水性が高く経時的に劣化して洗浄力の低下、悪臭の発生、アルカリ性を示すなど問題を有している。
また、アルキルベンゼンを使用する芳香族系炭化水素系の洗浄剤が特開平６−２５８６０７号公報に、トリメチルベンゼン及びその他の特定のアルキルベンゼン混合物でリンスする方法が特許第２６１３７５５号公報に提案されている。しかし、各種アルキルベンゼン異性体を使用する方法では、アルキル基が短い場合は引火点が低く安全性に問題があり、長鎖もしくはアルキル基の数が多ければ沸点が高くなり、また混合物で沸点範囲が広くなると蒸留再生効率が低下する問題がある。また、トリメチルベンゼン混合物は軽質であるため臭気が強く洗浄の作業環境が著しく悪化する問題がある。
また、炭化水素系の洗浄剤で洗浄後、炭素数６以下のアルコール及び／又はケトンで洗浄する方法が特開平６−２３２１０５号公報に提案されているが、引火点が低いため取り扱いが難しい。最近、コスト削減及び環境汚染を低減するため、洗浄剤を通常蒸留回収（再生）して繰り返し使用（リサイクル使用）されるケースが多くなっている。この蒸留回収時や洗浄時に、特に極性物質は分解或いは酸化されて洗浄力が劣化したり、爆発性の過酸化物を生成することがある。これを防止するため、酸化防止剤を添加する例が、特開平７−２６８３９１号公報に開示されている。
【０００４】
【発明が解決しようとする課題】
以上のように従来より各種の洗浄剤及び洗浄方法が提案されているけれども、ピッチ、ワックス、松脂、油脂、機械油、グリース、ハンダフラックス、フォトレジスト、接着剤などの汚れの洗浄性、乾燥性に優れ、更にリサイクル性や作業性など環境にやさしいなど、総合的に優れた洗浄方法が依然求められている。より具体的には、
▲１▼ピッチ、接着剤などの洗浄の難しい汚れの除去が可能である。
▲２▼プラスチック部分などの有機材料への影響が少ない
▲３▼光学レンズなどの無機材料への影響が少ない
▲４▼環境保全上の問題（オゾン層破壊、地球温暖化、土壌汚染等）や制限がない
▲５▼使用に際しての人体への影響、悪臭などが少ない
▲６▼洗浄剤の供給上の問題が少ない
▲７▼洗浄剤の繰り返し再利用が可能である（省資源、低コスト）
といった課題を満足する洗浄方法が求められている。
【０００５】
本発明は、上述のような従来技術の持つ諸問題を解決することを課題とするものであり、汎用性の高い洗浄剤を用いながら、高い洗浄効果を示し、しかも、洗浄対象物に悪影響を及ぼさず、高い環境保全性（低公害、良好な作業環境）、洗浄剤の再生回収を含む洗浄経済性に優れた洗浄方法を提供することを課題とする。
【０００６】
【課題を解決するための手段】
本発明は、（Ａ）炭素数１０〜１６の１環又は２環の芳香族系炭化水素を９５重量％以上含有する第１の洗浄剤で工業部品および製品を洗浄する第１の洗浄を行い、（Ｂ）次いで、炭素数１０〜１４のノルマルパラフィンを９５重量％以上含有し、第１の洗浄剤の５％留出温度よりも少なくとも３０℃低い９５％留出温度を有する第２の洗浄剤で前記被洗浄物を洗浄する第２の洗浄を行い、（Ｃ）その後、被洗浄物を乾燥する洗浄方法である。更に、好ましくは、第１の洗浄剤は、５％留出温度が１８０℃以上、９５％留出温度が３１５℃以下であり、第２の洗浄剤は、５％留出温度が１１０℃以上であり、９５％留出温度が２８０℃以下である。また、第１の洗浄剤及び第２の洗浄剤は共に５％留出温度と９５％留出温度の差が４０℃以下であることが好ましい。
【０００７】
かかる構成とした本発明の洗浄方法は、高い洗浄性を示し、短時間で洗浄後の乾燥処理ができ、しかも、高い環境保全性（低公害、良好な作業環境）を有する。また、洗浄後の洗浄剤はそれぞれ容易に高純度で再生回収し、リサイクル使用ができるので、経済性にも優れる。用途として、自動車、機械、電子・電気機器などの部品の洗浄に有用であり、特に、光学レンズ、プリズム等の洗浄に好適である。
【０００８】
【発明の実施の形態】
本願発明の第１の洗浄における第１の洗浄剤は、芳香族系炭化水素、ナフテン系炭化水素あるいはそれらの混合物を５０重量％以上、好ましくは９５重量％以上含有する。第１の洗浄剤は、５％留出温度１８０℃以上、更には１９５℃以上、９５％留出温度３１５℃以下の蒸留性状を有することが好ましく、また、５％留出温度と９５％留出温度との温度差が４０℃以下であることが好ましい。
蒸留性状において、沸点、特に５％留出温度が低くなると、第２の洗浄剤に持ち込まれた際に第２の洗浄剤との分離が難しくなる。また、沸点、特に９５％留出温度が高くなると、蒸留再生してリサイクル使用する場合、蒸留で回収しにくくなり、さもなければ再生のコストが高くなるので好ましくない。更に、沸点範囲、すなわち５％留出温度と９５％留出温度との温度差を４０℃以下、特には３０℃以下、更には１０℃以下にすると、蒸留再生が容易になり、回収率が向上するのでより好ましい。
【０００９】
第１の洗浄剤として、芳香族系炭化水素及びナフテン系炭化水素は、何れも化合物単品を用いることもできるが、範囲を持った沸点を有するそれぞれの混合物、あるいは芳香族系炭化水素及びナフテン系炭化水素の混合物を使用できる。芳香族系炭化水素及びナフテン系炭化水素以外のものが含まれていても良いが、芳香族系炭化水素及びナフテン系炭化水素の特性を維持するためにこれらを５０重量％以上、好ましくは８０重量％以上、特に好ましくは９５重量％以上含有する。
芳香族系炭化水素としては、炭素数１０〜１６の１環又は２環の芳香族系炭化水素（アルキルベンゼン、ナルタレン又はアルキルナフタレン）が好ましく、更にはナルタレン及び／又はアルキルナルタレンを３０重量％以上含有するものが好ましい。直鎖のアルキル基を有するアルキルベンゼンが好ましい。また、ナフテン系炭化水素としては、炭素数１０〜１６の２環のナフテン系炭化水素、特にアルキルデカリンが好ましく使用できる。
【００１０】
本願発明の第２の洗浄に用いる第２の洗浄剤としては、パラフィン系炭化水素を５０重量％以上含有する。これらの成分は、５％留出温度１１０℃以上、９５％留出温度２８０℃以下の蒸留性状を有することが好ましく、更には、５％留出温度と９５％留出温度との温度差が４０℃以下であることが好ましい。蒸留性状において、沸点、特に５％留出温度が低くなると、引火点が低くなるため、安全性、作業環境が悪くなる。また、沸点、特に９５％留出温度が２８０℃を越えると、乾燥性が低下し、かつ、蒸留再生してリサイクル使用する場合、蒸留で分けにくくなり、純度が低下するか、さもなければ再生のコストが高くなるので好ましくない。更に、沸点範囲、すなわち５％留出温度と９５％留出温度との温度差を４０℃以下、特には２０℃以下、更には１０℃以下にすると、蒸留再生が容易になりより好ましい。
【００１１】
パラフィン系炭化水素は、上記の蒸留性状を有する化合物の混合物、あるいは実質的に化合物単品でなるものを用いてもよい。パラフィン系炭化水素以外のものが含まれていても良いが、パラフィン系炭化水素の特性を維持するためにこれらを５０重量％以上、好ましくは８０重量％以上、特に好ましくは９５重量％以上含有するものを使用する。
パラフィン系炭化水素としては、沸点範囲を狭く調整することができるため、分岐鎖のものよりも直鎖のもの（ノルマルパラフィン）が好ましく、更に炭素数９〜１５、特に炭素数１０〜１４のノルマルパラフィンが好ましい。
【００１２】
また、本発明では、上記第１の洗浄剤と、その５％留出温度よりも少なくとも３０℃低い９５％留出温度を有する第２の洗浄剤を使用する。このように本願発明の洗浄方法は、特定の沸点範囲であり、特定の分子構造の炭化水素を組み合わせて、２段階で洗浄するものである。こうすることによって、洗浄性、乾燥性がともに優れた洗浄が可能となり、更に効率よく洗浄剤をリサイクルして使用することができる。洗浄対象となる工業部品の汚染物質としては、ピッチ、ワックス、松脂、油脂、機械油、グリース、ハンダフラックス、フォトレジスト、接着剤残物等様々なものを挙げることができる。
【００１３】
また、２種類の洗浄剤は、沸点範囲が３０℃以上異なるため、第２の洗浄剤に第１の洗浄剤が持ち込まれても、この沸点差によって容易に蒸留分離することができるので、洗浄剤のリサイクル使用を経済的に効率よく行うことができる。第１の洗浄剤に高沸点のものを使用し、第２の洗浄剤に低沸点のものを使用しているので、第１の洗浄において高沸点洗浄剤が有している高い洗浄力を利用し、その後、第２の洗浄において高沸点洗浄剤と異なる洗浄特性を利用して汚染物質を効果的に溶解除去することができる。更に、洗浄済み部品には比較的揮発性の低沸点洗浄剤のみが付着しているので、次段階の乾燥工程を効率よく、短い時間で行うことができる。
なお、第１の洗浄剤と第２の洗浄剤との組み合わせは、第１の洗浄剤として芳香族系炭化水素、第２の洗浄剤としてノルマルパラフィンの組み合わせが、良好な洗浄性を示すのでより好ましい。
【００１４】
本願発明の洗浄方法は、自動車、機械、電子・電気機器などの部品の洗浄に有用であるが、特に、ピッチ、研磨砥粒等により汚染された光学レンズ、プリズム等の光学部品の洗浄に好適である。このような光学部品を塩素系溶剤及び水系洗浄剤を用いて洗浄する場合、塩素系溶剤による環境問題、及び水系洗浄剤の使用から生じるレンズ表面の白やけ、青やけ、レンズの白化などの問題が懸念されていた。これに対して、本発明の洗浄方法をこのような光学部品の洗浄に適用すると、十分な洗浄効果が得られると共に、このような問題は完全に回避される。
【００１５】
本発明の洗浄方法をレンズなどの光学部品の洗浄に適用する好ましい態様を以下に示す。芳香族系炭化水素からなる第１の洗浄剤中に研磨済みのレンズを浸して、１０〜７０℃程度で、３０〜１５０秒間程度超音波洗浄する。第１の洗浄を行ったレンズを取り出し、パラフィン系炭化水素からなる第２の洗浄剤中に前記レンズを浸して、第１の洗浄と同じ範囲の温度、時間で超音波洗浄する。第１の洗浄後、第２の洗浄剤に浸す前に、レンズに付着する第１の洗浄剤を乾燥させることなく一部分を除去しておくことが後続の処理工程の負担を軽くする上で好ましい。こうして、洗浄後各洗浄液の汚れ具合を観察して洗浄液を交換し、汚れたものは蒸留再生して汚染物質を分離し、洗浄液は回収してリサイクル使用する。洗浄と蒸留はそれぞれバッチで処理してもよいし、両処理について、プロセス的にループを組んで連続的に処理することもできる。
第２の洗浄後、レンズから洗浄剤を除去する必要があるが、周知の乾燥手段を適宜選択して容易に乾燥除去することができる。第２の洗浄剤は、沸点範囲が比較的低い炭化水素を使用することから、例えば、５０℃程度（４０℃〜７０℃）の温風を数分間（１〜５分）当てるだけで充分乾燥することができる。
【００１６】
本発明の洗浄方法で使用する各洗浄剤は、本発明の効果を損なわない限り、他の洗浄剤、各種の添加剤を配合することができる。他の洗浄剤成分、特に第１の洗浄剤に有用な成分としては、本発明で特定する炭化水素以外の炭化水素、各種のアルコール、ケトン、エステル、ポリエーテル、塩素を含有しないハイドロフルオロカーボン、Ｎ−メチルピロリドン、シクロヘキサノンなどが挙げられる。また、添加剤としては、酸化防止剤、殺菌剤、防黴剤、防錆剤、界面活性剤などが挙げられる。
【００１７】
【実施例】
以下、実施例に基づいて本発明をより具体的に説明する。
洗浄剤として、芳香族系洗浄剤１〜２、ナフテン系洗浄剤１〜２、パラフィン系洗浄剤１〜３、市販灯油及びＮ−メチルピロリドン（沸点：２０２℃）を用いた。これらの洗浄剤の性状を表１に示す。なお、芳香族系洗浄剤１は、ナフタレンを１４重量％、メチルナフタレンを２３重量％、炭素数１０のアルキルベンゼンを１０重量％、炭素数１１のアルキルベンゼンを２６重量％、炭素数１２のアルキルベンゼンを１３重量％含有する。芳香族系洗浄剤２は、ジメチルナフタレンを３４重量％、炭素数１３のアルキルナフタレンを４７重量％、炭素数１４のアルキルナフタレンを４重量％含有する。
【００１８】
【表１】

【００１９】
洗浄対象物（被洗浄物）としては、ピッチ（九重電気（株）製、Ｋ級３号）を溶解した３０％濃度トルエン溶液に光学ガラスを浸し、室温で乾燥することで、均一なピッチを付着させた光学ガラスを用いた。この洗浄対象物を表２に示す第１の洗浄剤及び第２の洗浄剤を用い、以下の手順で洗浄した。
【００２０】
【表２】

【００２１】
この洗浄対象物をまず第１の洗浄として第１の洗浄剤が充填された第１の洗浄槽に浸して洗浄した。第１の洗浄は、液温３０℃で超音波照射下に１２０秒間行った。次いで、第１の洗浄槽から取り出した洗浄対象物を第２の洗浄として第２の洗浄剤が充填された第２の洗浄槽に浸して洗浄した。第２の洗浄は、液温３０℃で超音波照射下に６０秒間行った。第２の洗浄槽から取り出した洗浄対象物を、１０分間立てて静置後、温風乾燥機（６０℃、２分間）で第２の洗浄剤を蒸散除去し乾燥した。
洗浄・乾燥後に、ガラス表面を肉眼により観察し、ピッチの痕跡が全く認められないものを○、少しでも痕跡のあるものを×として洗浄性を評価した。この評価結果を表２に併せて示した。
【００２２】
上述の洗浄試験を行った後、使用済み洗浄剤を蒸留再生機（東静電気（株）製、トスクリーンＤＥ−１０１Ｅ）にかけて蒸留再生を行い、蒸留再生回収性を評価した。第１の洗浄剤の蒸留再生については、洗浄対象物に付着していた汚染物質が第１の洗浄剤から分離できる場合を○、分離できない場合を×として評価し、また、第２の洗浄剤の蒸留再生については、洗浄対象物に同伴された第１の洗浄剤が第２の洗浄剤から分離できる場合を○、分離できない場合を×として評価した。この蒸留再生回収性の評価結果を表２に併せて示した。
【００２３】
表２の評価結果から、本発明の洗浄方法（実施例１〜４）は、洗浄性及び蒸留再生回収性共に満足されるものであった。一方、本発明の要件を欠く比較例１〜５は、洗浄性及び蒸留再生回収性が共に悪いか、少なくともいずれかは満足できる結果を得ることができなかった。
【００２４】
【発明の効果】
本発明は、特定の炭化水素からなる異なる種類の洗浄剤を特定の順序で使用する洗浄方法である。このため、高い環境保全性（低公害及び良好な作業環境）を有しながら、優れた洗浄性を示し、かつ、使用済み洗浄剤を容易に蒸留して再生使用できるので経済性にも優れる。各種の工業部品、製品の洗浄に、特にレンズ等の光学部品の洗浄に好適に用いることができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cleaning method for machine parts, electrical and electronic parts, optical parts, and the like.
[0002]
[Prior art]
Conventionally, various cleaning agents have been used to remove dirt adhered to the surfaces of electrical and electronic parts, mechanical parts, precision parts, optical parts, and the like. Chlorine-based or chlorofluorocarbon-based cleaning agents, which are representative cleaning agents, have been widely used because they are flame retardant and have excellent cleaning properties. However, their use has been severely restricted worldwide as a causative substance of ozone layer destruction and global warming, and it is expected that they will be more strictly regulated in the future. Similar compounds such as trichlene and methylene chloride have been used, but they are highly toxic due to their chlorinated solvents and have health and environmental problems. For this reason, many water-based or solvent-based cleaning agents have been proposed as alternative cleaning agents.
In recent years, examples of using terpenes such as limonene, pinene, dipentene and the like as a highly safe cleaning agent with little environmental pollution are disclosed in US Pat. No. 4,511,488 and Japanese Patent Publication No. 63-501908 (US Pat. No. 4,640,719). No. and No. 4740247). However, terpenes represented by limonene are compounds derived from natural products contained in a trace amount in a specific plant, and thus are expensive and have a limited supply amount, and have a problem in durability during use.
In addition, there are water-based cleaning agents in which a builder such as caustic soda or orthosilicate sodium is added to a surfactant. Aqueous detergents have poor detergency, and also cause rusting and fatal defects such as whitish and blueishness of optical lenses, and are difficult to regenerate and require dedicated waste liquid treatment equipment.
[0003]
Japanese Patent Publication No. 51-29195 proposes a method of using N-methylpyrrolidone for cleaning pitch (polymerization reactor deposit). However, N-methylpyrrolidone strongly degrades plastic materials and is not suitable for cleaning objects containing plastic parts.It also has high water absorption and deteriorates over time, resulting in decreased cleaning power, generation of bad odors, and alkalinity. Has problems such as showing.
Also, an aromatic hydrocarbon-based cleaning agent using alkylbenzene is proposed in JP-A-6-258607, and a method of rinsing with trimethylbenzene and other specific alkylbenzene mixture is proposed in Japanese Patent No. 2613755. However, in the method using various alkylbenzene isomers, if the alkyl group is short, the flash point is low and there is a problem in safety, and if the number of long chains or alkyl groups is large, the boiling point becomes high, and the boiling point range of the mixture is high. When it becomes wider, there is a problem that the distillation regeneration efficiency is lowered. Further, since the trimethylbenzene mixture is light, there is a problem that the odor is strong and the cleaning working environment is remarkably deteriorated.
A method of cleaning with an alcohol and / or ketone having 6 or less carbon atoms after cleaning with a hydrocarbon-based cleaning agent is proposed in Japanese Patent Application Laid-Open No. 6-232105, but is difficult to handle because of its low flash point. Recently, in order to reduce costs and reduce environmental pollution, there are many cases where cleaning agents are usually recovered by distillation (regeneration) and repeatedly used (recycled). At the time of distillation recovery and washing, particularly polar substances may be decomposed or oxidized to deteriorate the cleaning power or generate explosive peroxides. In order to prevent this, an example of adding an antioxidant is disclosed in JP-A-7-268391.
[0004]
[Problems to be solved by the invention]
As described above, various cleaning agents and cleaning methods have been proposed in the past. However, stains such as pitch, wax, pine oil, fats and oils, machine oils, greases, solder fluxes, photoresists, and adhesives can be cleaned and dried. There is still a need for a comprehensive cleaning method that is excellent in environment and environmentally friendly, such as recyclability and workability. More specifically,
(1) Dirt that is difficult to clean such as pitch and adhesive can be removed.
(2) Less impact on organic materials such as plastic parts (3) Less impact on inorganic materials such as optical lenses (4) Environmental conservation problems (depletion of the ozone layer, global warming, soil contamination, etc.) Unlimited (5) Less impact on human body, bad odor, etc. during use (6) Less problems in supplying detergent (7) Repeated reuse of detergent (resource saving, low cost)
Therefore, there is a need for a cleaning method that satisfies these problems.
[0005]
An object of the present invention is to solve the problems of the prior art as described above, and exhibits a high cleaning effect while using a highly versatile cleaning agent, and has an adverse effect on the object to be cleaned. It is an object of the present invention to provide a cleaning method that has excellent environmental conservation (low pollution, good working environment) and excellent cleaning economics including regeneration and recovery of cleaning agents.
[0006]
[Means for Solving the Problems]
In the present invention, (A) a first cleaning is performed to clean industrial parts and products with a first cleaning agent containing 95 % by weight or more of a monocyclic or bicyclic aromatic hydrocarbon having 10 to 16 carbon atoms. (B) Next, a second washing that contains 95 % by weight or more of normal paraffins having 10 to 14 carbon atoms and has a 95% distillation temperature that is at least 30 ° C. lower than the 5% distillation temperature of the first detergent. (C) A cleaning method in which the object to be cleaned is then dried. Further, preferably, the first detergent, 5% distillation temperature of 180 ° C. or more, a 95% distillation temperature of 315 ° C. or less, the second cleaning agent, 5% distillation temperature of 1 1 0 And the 95% distillation temperature is 280 ° C or lower. Moreover, it is preferable that the difference between 5% distillation temperature and 95% distillation temperature is 40 ° C. or less for both the first cleaning agent and the second cleaning agent.
[0007]
The cleaning method of the present invention configured as described above exhibits high cleaning properties, can be dried after cleaning in a short time, and has high environmental conservation (low pollution, good working environment). In addition, since the cleaning agent after cleaning can be easily recovered and recovered with high purity and can be recycled, it is excellent in economic efficiency. As an application, it is useful for cleaning parts such as automobiles, machines, and electronic / electrical devices, and is particularly suitable for cleaning optical lenses, prisms, and the like.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
The first cleaning agent in the first cleaning of the present invention contains 50% by weight or more, preferably 95% by weight or more of an aromatic hydrocarbon, a naphthenic hydrocarbon, or a mixture thereof. The first detergent preferably has a distillation property of 5% distillation temperature of 180 ° C. or higher, more preferably 195 ° C. or higher and 95% distillation temperature of 315 ° C. or lower, and 5% distillation temperature and 95% distillation temperature. It is preferable that the temperature difference with the output temperature is 40 ° C. or less.
If the boiling point, particularly the 5% distillation temperature is lowered in the distillation properties, separation from the second cleaning agent becomes difficult when brought into the second cleaning agent. In addition, when the boiling point, particularly the 95% distillation temperature, is high, when it is recycled by distillation, it is difficult to recover by distillation, otherwise the cost of regeneration is not preferable. Furthermore, when the boiling point range, that is, the temperature difference between the 5% distillation temperature and the 95% distillation temperature is 40 ° C. or less, particularly 30 ° C. or less, further 10 ° C. or less, the distillation regeneration is facilitated and the recovery rate is increased. Since it improves, it is more preferable.
[0009]
As the first cleaning agent, both aromatic hydrocarbons and naphthenic hydrocarbons can be used as single compounds, but each mixture having a boiling point with a range, or aromatic hydrocarbons and naphthenic hydrocarbons can be used. Mixtures of hydrocarbons can be used. Other than aromatic hydrocarbons and naphthenic hydrocarbons may be included, but in order to maintain the characteristics of aromatic hydrocarbons and naphthenic hydrocarbons, these are 50% by weight or more, preferably 80% by weight. % Or more, particularly preferably 95% by weight or more.
The aromatic hydrocarbon is preferably a monocyclic or bicyclic aromatic hydrocarbon having 10 to 16 carbon atoms (alkylbenzene, naltalene or alkylnaphthalene), and more preferably 30% by weight or more of naltalene and / or alkylnaltalene. What is contained is preferable. Alkylbenzene having a linear alkyl group is preferred. Moreover, as a naphthene type hydrocarbon, a C10-C16 bicyclic naphthene type hydrocarbon, especially alkyl decalin can be used preferably.
[0010]
As a 2nd cleaning agent used for the 2nd washing | cleaning of this invention, paraffin type hydrocarbon is contained 50weight% or more. These components preferably have a distillation property with a 5% distillation temperature of 110 ° C. or more and a 95% distillation temperature of 280 ° C. or less. Further, there is a temperature difference between the 5% distillation temperature and the 95% distillation temperature. It is preferable that it is 40 degrees C or less. In the distillation properties, when the boiling point, particularly the 5% distillation temperature is lowered, the flash point is lowered, so that the safety and the working environment are deteriorated. In addition, when the boiling point, particularly 95% distillation temperature exceeds 280 ° C, the drying property is lowered, and when recycled by distillation, it becomes difficult to separate by distillation, and the purity is lowered or otherwise regenerated. This is not preferable because the cost is increased. Furthermore, when the boiling point range, that is, the temperature difference between the 5% distillation temperature and the 95% distillation temperature is 40 ° C. or less, particularly 20 ° C. or less, further 10 ° C. or less, the distillation regeneration is facilitated, which is more preferable.
[0011]
As the paraffinic hydrocarbon, a mixture of compounds having the above-described distillation properties, or a substance substantially consisting of a single compound may be used. Other than paraffinic hydrocarbons may be included, but in order to maintain the characteristics of paraffinic hydrocarbons, these are contained in an amount of 50% by weight or more, preferably 80% by weight or more, and particularly preferably 95% by weight or more. Use things.
As the paraffinic hydrocarbon, since the boiling point range can be adjusted narrowly, a straight chain (normal paraffin) is preferable to a branched chain, and further, a normal number of 9 to 15 carbon atoms, particularly a normal number of 10 to 14 carbon atoms. Paraffin is preferred.
[0012]
In the present invention, the first cleaning agent and a second cleaning agent having a 95% distillation temperature that is at least 30 ° C. lower than the 5% distillation temperature are used. As described above, the cleaning method of the present invention has a specific boiling range, and combines two hydrocarbons having a specific molecular structure for cleaning in two stages. By doing so, it is possible to perform cleaning with excellent cleaning properties and drying properties, and it is possible to recycle and use the cleaning agent more efficiently. Examples of contaminants of industrial parts to be cleaned include various things such as pitch, wax, pine resin, oil and fat, machine oil, grease, solder flux, photoresist, adhesive residue and the like.
[0013]
Also, since the two types of cleaning agents differ in boiling point range by 30 ° C. or more, even if the first cleaning agent is brought into the second cleaning agent, it can be easily separated by distillation due to this boiling point difference. The recycling of the agent can be carried out economically and efficiently. Since the first cleaning agent has a high boiling point and the second cleaning agent has a low boiling point, the high cleaning power of the high boiling point cleaning agent is used in the first cleaning. Then, in the second cleaning, contaminants can be effectively dissolved and removed by using cleaning characteristics different from those of the high boiling point cleaning agent. Further, since only the relatively volatile low-boiling detergent is adhered to the cleaned parts, the drying process in the next stage can be performed efficiently and in a short time.
The combination of the first cleaning agent and the second cleaning agent is more preferable because the combination of aromatic hydrocarbons as the first cleaning agent and normal paraffin as the second cleaning agent shows good detergency. preferable.
[0014]
The cleaning method of the present invention is useful for cleaning parts such as automobiles, machines, and electronic / electric equipment, but is particularly suitable for cleaning optical parts such as optical lenses and prisms contaminated by pitch, abrasive grains, etc. It is. When cleaning such optical components with chlorinated solvents and aqueous cleaners, environmental problems caused by chlorinated solvents, and problems such as whitening of the lens surface, blue tingling, and whitening of lenses resulting from the use of aqueous cleaners There was concern. On the other hand, when the cleaning method of the present invention is applied to the cleaning of such an optical component, a sufficient cleaning effect can be obtained and such a problem can be completely avoided.
[0015]
A preferred embodiment in which the cleaning method of the present invention is applied to cleaning of optical components such as lenses will be described below. The polished lens is immersed in a first cleaning agent made of aromatic hydrocarbon, and is ultrasonically cleaned at about 10 to 70 ° C. for about 30 to 150 seconds. The lens subjected to the first cleaning is taken out, and the lens is immersed in a second cleaning agent made of paraffinic hydrocarbon, and is ultrasonically cleaned at the same temperature and time as the first cleaning. It is preferable to remove a part of the first cleaning agent adhering to the lens without drying after the first cleaning and before immersing in the second cleaning agent in order to reduce the burden of the subsequent processing steps. . In this way, after cleaning, the cleaning solution is observed by replacing the cleaning solution, and the contaminated material is distilled and regenerated to separate contaminants, and the cleaning solution is collected and recycled. Washing and distillation may be processed in batches, or both processes can be processed continuously in a loop.
After the second cleaning, it is necessary to remove the cleaning agent from the lens. However, it is possible to easily remove the cleaning agent by appropriately selecting a known drying means. Since the second cleaning agent uses hydrocarbons having a relatively low boiling range, for example, it can be sufficiently dried by applying hot air of about 50 ° C. (40 ° C. to 70 ° C.) for several minutes (1 to 5 minutes). can do.
[0016]
Each cleaning agent used in the cleaning method of the present invention can be blended with other cleaning agents and various additives as long as the effects of the present invention are not impaired. Other components useful for the cleaning agent, particularly the first cleaning agent include hydrocarbons other than the hydrocarbons specified in the present invention, various alcohols, ketones, esters, polyethers, chlorine-free hydrofluorocarbons, N -Methylpyrrolidone, cyclohexanone and the like. Examples of additives include antioxidants, bactericides, antifungal agents, rust inhibitors, and surfactants.
[0017]
【Example】
Hereinafter, based on an Example, this invention is demonstrated more concretely.
As cleaning agents, aromatic cleaning agents 1-2, naphthene cleaning agents 1-2, paraffin cleaning agents 1-3, commercial kerosene and N-methylpyrrolidone (boiling point: 202 ° C.) were used. Table 1 shows the properties of these cleaning agents. In addition, the aromatic detergent 1 is 14% by weight of naphthalene, 23% by weight of methylnaphthalene, 10% by weight of alkylbenzene having 10 carbon atoms, 26% by weight of alkylbenzene having 11 carbon atoms, and 13% of alkylbenzene having 12 carbon atoms. Contains by weight. The aromatic cleaning agent 2 contains 34% by weight of dimethylnaphthalene, 47% by weight of alkylnaphthalene having 13 carbon atoms, and 4% by weight of alkylnaphthalene having 14 carbon atoms.
[0018]
[Table 1]

[0019]
As an object to be cleaned (object to be cleaned), a uniform pitch can be obtained by immersing the optical glass in a 30% concentration toluene solution in which pitch (Kuju Electric Co., Ltd., K grade 3) is dissolved and drying at room temperature. Adhered optical glass was used. This cleaning object was cleaned by the following procedure using the first cleaning agent and the second cleaning agent shown in Table 2.
[0020]
[Table 2]

[0021]
The object to be cleaned was first immersed and cleaned in a first cleaning tank filled with a first cleaning agent as the first cleaning. The first cleaning was performed for 120 seconds under ultrasonic irradiation at a liquid temperature of 30 ° C. Next, the object to be cleaned taken out from the first cleaning tank was immersed in a second cleaning tank filled with a second cleaning agent for cleaning as a second cleaning. The second cleaning was performed for 60 seconds under ultrasonic irradiation at a liquid temperature of 30 ° C. The object to be cleaned taken out from the second cleaning tank was stood still for 10 minutes, and then the second cleaning agent was removed by evaporation with a hot air dryer (60 ° C., 2 minutes) and dried.
After cleaning and drying, the surface of the glass was observed with the naked eye, and the cleaning property was evaluated with ○ indicating that no trace of pitch was observed, and X indicating even a slight trace. The evaluation results are also shown in Table 2.
[0022]
After performing the above-described cleaning test, the used cleaning agent was subjected to distillation regeneration by applying it to a distillation regenerator (manufactured by Tosei Denshi Co., Ltd., Tosushien DE-101E), and the distillation regeneration recovery property was evaluated. Regarding distillation regeneration of the first cleaning agent, the case where the contaminants adhering to the object to be cleaned can be separated from the first cleaning agent is evaluated as ○, and the case where it cannot be separated is evaluated as ×, and the second cleaning agent Regarding the distillation regeneration, the case where the first cleaning agent entrained in the object to be cleaned can be separated from the second cleaning agent was evaluated as ◯, and the case where it could not be separated was evaluated as ×. The evaluation results of the distillation regeneration recovery properties are also shown in Table 2.
[0023]
From the evaluation results of Table 2, the cleaning method of the present invention (Examples 1 to 4) was satisfactory in both cleaning properties and distillation regeneration recovery properties. On the other hand, Comparative Examples 1 to 5 lacking the requirements of the present invention have poor cleaning properties and distillation regeneration recoverability, or at least one of them cannot obtain satisfactory results.
[0024]
【The invention's effect】
The present invention is a cleaning method in which different types of cleaning agents comprising specific hydrocarbons are used in a specific order. For this reason, while having high environmental conservation (low pollution and a good working environment), it exhibits excellent cleaning properties, and since the used cleaning agent can be easily distilled and reused, it is excellent in economic efficiency. It can be suitably used for cleaning various industrial parts and products, particularly for cleaning optical parts such as lenses.

Claims

(A) First cleaning is performed to clean industrial parts and products with a first cleaning agent containing 95 wt% or more of a monocyclic or bicyclic aromatic hydrocarbon having 10 to 16 carbon atoms , and (B) The second cleaning agent contains 95 % by weight or more of normal paraffin having 10 to 14 carbon atoms and has a 95% distillation temperature at least 30 ° C. lower than the 5% distillation temperature of the first cleaning agent. A cleaning method characterized by performing second cleaning for cleaning an object, and (C) then drying the object to be cleaned.

The 5% distillation temperature of the first cleaning agent is 180 ° C. or higher, the 95% distillation temperature is 315 ° C. or lower, and the 5% distillation temperature of the second cleaning agent is 110 ° C. or higher; The cleaning method according to claim 1, wherein the 95% distillation temperature is 280 ° C or lower.

The cleaning method according to claim 1 or 2, wherein the difference between the 5% distillation temperature and the 95% distillation temperature between the first cleaning agent and the second cleaning agent is 40 ° C or less.

The cleaning method according to claim 1, wherein the first cleaning agent and / or the second cleaning agent used for cleaning is distilled and reused.