金属加工用アミン乳化剤とpH緩衝剤

金属加工液用アミンはアルカノールアミンで、水溶性の切削液や研削液を適正pHに保ちながら、pH低下の緩衝、油の水中への乳化、鉄系金属の初期錆防止という複数の役割を同時に果たします。 Monoethanolamine (MEA, CAS 141-43-5) is the strong, low-cost pH and reserve-alkalinity builder; triethanolamine (TEA, CAS 102-71-6) adds emulsification and yellow-metal-friendly corrosion control. Target a working pH near 8.8-9.2 for most soluble fluids and dose the amine to hold it as the sump ages.

The genuine trade-off is chemical, not commercial. Alkanolamines give a sump long life and good corrosion protection, but with a nitrosating agent present, most often a nitrite-based corrosion inhibitor, secondary-amine content can form N-nitrosamines, a documented metalworking-fluid concern flagged by NIOSH. Primary amines such as MEA form unstable nitroso species; residual diethanolamine in a tertiary-amine grade is the principal precursor. Do not combine nitrite inhibitors with amine-based fluids, and confirm regulatory status for your application and jurisdiction.

Boric acid (CAS 10043-35-3) rounds out the group as an inorganic pH buffer and reserve-alkalinity aid, not an amine, and provides the mild biocidal action that helps hold sump pH and limit spoilage. Keep total water hardness in view, because hard make-up water shifts both pH and emulsion stability. Monitor pH and refractometer concentration weekly, and top up the amine package before pH falls below about 8.5 rather than after corrosion appears.

• 水溶性切削・研削油剤におけるpH管理と予備アルカリ度の確保
• 水溶性油剤およびセミシンセティック系クーラントの水中油型乳化
• 液中での鉄系金属・銅合金の防食
• 緩衝作用と微生物制御によるクーラント液寿命の延長
• 水溶性油剤濃縮物の製造における脂肪酸の中和

• Monoethanolamine u2014 PubChem
• Triethanolamine u2014 PubChem
• Boric acid u2014 PubChem