烷基糖苷廣泛用于日用化學工業,在金屬防護業中也占有重要地位。表面活性劑可(ke)使金(jin)屬防護(hu)效(xiao)果更(geng)佳,能節省材(cai)料及能源,并解決一系列實際(ji)問題。目前,隨著國內外表面活性劑(ji)工業(ye)水平的迅速發展,其應用技術已成(cheng)為金(jin)屬防護(hu)業(ye)的熱點(dian)之(zhi)一。
表面(mian)(mian)活性(xing)劑(ji)也稱界(jie)面(mian)(mian)活性(xing)劑(ji),是指(zhi)一-些在低濃度下可(ke)以大幅度降低界(jie)面(mian)(mian)張力的(de)有(you)機化合物(wu)。其分子中同時含有(you)親水(shui)(shui)的(de)極性(xing)基(ji)團(tuan)(如(ru)- COOH,- OH,- NH2、- OSO3、- SO3,- CONH2,醚鍵- 0-等)和憎水(shui)(shui)(親油(you))的(de)非極性(xing)基(ji)團(tuan)(如(ru)各(ge)類C- H鏈烴基(ji))。
按表(biao)面(mian)(mian)(mian)活(huo)性劑(ji)的結構(gou)可分為(wei)(wei)陰離(li)子(zi)型、陽離(li)子(zi)型、非(fei)離(li)子(zi)型和兩性型四(si)種類(lei)型。表(biao)面(mian)(mian)(mian)活(huo)性劑(ji)分子(zi)中(zhong)(zhong)不(bu)對稱(cheng)的兩親(qin)結構(gou),決定(ding)了其在溶(rong)(rong)液中(zhong)(zhong)的界面(mian)(mian)(mian)吸(xi)附、定(ding)向排列(lie)及形(xing)成膠束的基本(ben)性質,結果都是(shi)使界面(mian)(mian)(mian)張力降低,體(ti)系趨于穩(wen)定(ding)。表(biao)現出潤(run)濕(shi)、乳化、洗滌、滲透(tou)、增溶(rong)(rong)及起(qi)泡等特(te)性。利用(yong)表(biao)面(mian)(mian)(mian)活(huo)性劑(ji)的諸多特(te)性,在金屬防護(hu)中(zhong)(zhong)可作(zuo)為(wei)(wei)酸洗、除油、電鍍、封閉(bi)、低溫(wen)磷(lin)化、緩蝕及環保中(zhong)(zhong)的各類(lei)功能(neng)型添加劑(ji)。作(zuo)用(yong)機理均為(wei)(wei)吸(xi)附,但(dan)使用(yong)條件(jian)不(bu)同(tong),效(xiao)果也就不(bu)同(tong)。
表面(mian)(mian)活性(xing)劑加入(ru)到一般酸洗液(ye)中(zhong)得(de)到光(guang)(guang)亮酸洗液(ye),可以代替傳統的(de)(de)(de)高鉻、高氮、污(wu)染嚴(yan)重(zhong)的(de)(de)(de)光(guang)(guang)亮浸(jin)蝕(shi)液(ye)。表面(mian)(mian)活性(xing)劑的(de)(de)(de)作(zuo)(zuo)用(yong)在(zai)于(yu)其吸(xi)附于(yu)工(gong)件(jian)(jian)表面(mian)(mian)并形成阻擋吸(xi)附膜。由于(yu)工(gong)件(jian)(jian)的(de)(de)(de)抖動,溶液(ye)的(de)(de)(de)對流和擴散作(zuo)(zuo)用(yong),造成微(wei)觀(guan)凸(tu)出部(bu)位(wei)(wei)的(de)(de)(de)吸(xi)附膜較凹(ao)陷(xian)部(bu)位(wei)(wei)容易脫附,而使凸(tu)出部(bu)位(wei)(wei)的(de)(de)(de)銹蝕(shi)及(ji)氧化皮被(bei)酸集中(zhong)溶解,且溶解速度大于(yu)凹(ao)陷(xian)部(bu)位(wei)(wei)。往(wang)復的(de)(de)(de)吸(xi)附、脫附和溶解,還使工(gong)件(jian)(jian)表面(mian)(mian)的(de)(de)(de)微(wei)觀(guan)劃痕也被(bei)填平,得(de)到平整光(guang)(guang)亮的(de)(de)(de)基材表面(mian)(mian)。表面(mian)(mian)活性(xing)劑起到了(le)整平、光(guang)(guang)亮緩蝕(shi)的(de)(de)(de)作(zuo)(zuo)用(yong)。
電鍍(du)工(gong)(gong)業中,工(gong)(gong)件在進行電鍍(du)、油(you)(you)(you)(you)漆、氧(yang)化等工(gong)(gong)序前均需要除(chu)油(you)(you)(you)(you)、酸(suan)洗(xi)和拋光(guang)預處理。通常采用(yong)的(de)堿性(xing)除(chu)油(you)(you)(you)(you)液,溫度較高時(shi)才(cai)能(neng)達到(dao)理想的(de)除(chu)油(you)(you)(you)(you)效果。若(ruo)在除(chu)油(you)(you)(you)(you)液中加入表(biao)(biao)面(mian)(mian)活性(xing)劑(ji),利用(yong)其乳(ru)化、洗(xi)滌特性(xing),即表(biao)(biao)面(mian)(mian)活性(xing)劑(ji)的(de)兩親(qin)基團(tuan)吸附于(yu)油(you)(you)(you)(you)水界面(mian)(mian)上,極性(xing)基指向(xiang)(xiang)水,非極性(xing)基指向(xiang)(xiang)油(you)(you)(you)(you)污,定向(xiang)(xiang)排列,降(jiang)低(di)油(you)(you)(you)(you)-水間的(de)界面(mian)(mian)張力,使金屬表(biao)(biao)面(mian)(mian)的(de)油(you)(you)(you)(you)污分(fen)散、懸(xuan)浮(fu),脫離工(gong)(gong)件表(biao)(biao)面(mian)(mian)并(bing)不再吸附于(yu)工(gong)(gong)件上。因此(ci)可提高除(chu)油(you)(you)(you)(you)效果及除(chu)油(you)(you)(you)(you)速度并(bing)實(shi)現低(di)溫除(chu)油(you)(you)(you)(you)。