針(zhen)對電(dian)泳(yong)(yong)(yong)鋁材黃變現象(xiang)的(de)原因總結出以(yi)下幾點(dian)：電(dian)泳(yong)(yong)(yong)涂(tu)漆(qi)本(ben)身；氧(yang)(yang)化導電(dian)不良；電(dian)泳(yong)(yong)(yong)前水洗不徹底；固化過(guo)度；氧(yang)(yang)化槽液被硝酸污染。

1．氧化時(shi)導(dao)電不良(liang)引(yin)起的黃變(bian)現(xian)象

型材(cai)與(yu)導(dao)電(dian)(dian)桿接觸(chu)不良(liang)，接點(dian)處的電(dian)(dian)阻就(jiu)會(hui)大(da)增，型材(cai)端頭就(jiu)會(hui)發熱，氧(yang)化膜生(sheng)成(cheng)過(guo)快并(bing)伴(ban)有(you)燒灼現(xian)象(xiang)，甚(shen)至出現(xian)氧(yang)化膜的粉化。這(zhe)時(shi)的氧(yang)化膜有(you)些(xie)渾(hun)濁，顏色出現(xian)黃(huang)變(bian)，如果再進行電(dian)(dian)泳生(sheng)產就(jiu)會(hui)出現(xian)非常明顯的黃(huang)變(bian)現(xian)象(xiang)。這(zhe)種黃(huang)變(bian)現(xian)象(xiang)一(yi)般情況下一(yi)排(pai)里只有(you)幾支，并(bing)且基本(ben)上都是出現(xian)在型材(cai)的端頭。因此，一(yi)定(ding)要采取措施來保證型材(cai)與(yu)導(dao)電(dian)(dian)桿接觸(chu)良(liang)好。

2．電(dian)泳前水洗不徹底(di)引起的黃變現(xian)象

氧(yang)(yang)(yang)化(hua)(hua)膜(mo)(mo)(mo)(mo)是蜂窩狀的(de)，其多孔(kong)(kong)狀的(de)結構(gou)就決定了氧(yang)(yang)(yang)化(hua)(hua)膜(mo)(mo)(mo)(mo)孔(kong)(kong)中會(hui)(hui)殘(can)留(liu)硫(liu)酸。眾所(suo)周知，用來電泳(yong)的(de)型材(cai)如(ru)果水洗(xi)不(bu)徹底，就很有可能(neng)出現(xian)黃(huang)變(bian)(bian)(bian)現(xian)象。對于這(zhe)種(zhong)(zhong)黃(huang)變(bian)(bian)(bian)現(xian)象，一(yi)般(ban)都認為(wei)是氧(yang)(yang)(yang)化(hua)(hua)膜(mo)(mo)(mo)(mo)孔(kong)(kong)里的(de)酸根(gen)與(yu)電泳(yong)漆(qi)(qi)反應從(cong)(cong)而(er)(er)使電泳(yong)漆(qi)(qi)膜(mo)(mo)(mo)(mo)發(fa)(fa)生的(de)黃(huang)變(bian)(bian)(bian)，對于這(zhe)種(zhong)(zhong)認識(shi)，不(bu)敢茍同，因(yin)為(wei)這(zhe)種(zhong)(zhong)黃(huang)變(bian)(bian)(bian)不(bu)是漆(qi)(qi)膜(mo)(mo)(mo)(mo)發(fa)(fa)生的(de)黃(huang)變(bian)(bian)(bian)，而(er)(er)是氧(yang)(yang)(yang)化(hua)(hua)膜(mo)(mo)(mo)(mo)的(de)黃(huang)變(bian)(bian)(bian)。正常(chang)的(de)氧(yang)(yang)(yang)化(hua)(hua)膜(mo)(mo)(mo)(mo)是清(qing)澈(che)、透(tou)(tou)明(ming)(ming)的(de)，如(ru)果氧(yang)(yang)(yang)化(hua)(hua)膜(mo)(mo)(mo)(mo)孔(kong)(kong)里殘(can)留(liu)較多的(de)硫(liu)酸根(gen)，高溫(wen)(wen)情況(kuang)下，氧(yang)(yang)(yang)化(hua)(hua)膜(mo)(mo)(mo)(mo)就會(hui)(hui)與(yu)硫(liu)酸根(gen)發(fa)(fa)生反應，從(cong)(cong)而(er)(er)使清(qing)澈(che)、透(tou)(tou)明(ming)(ming)的(de)氧(yang)(yang)(yang)化(hua)(hua)膜(mo)(mo)(mo)(mo)變(bian)(bian)(bian)得渾濁，透(tou)(tou)明(ming)(ming)性(xing)(xing)下降；同時再加(jia)上電泳(yong)漆(qi)(qi)膜(mo)(mo)(mo)(mo)的(de)高透(tou)(tou)明(ming)(ming)性(xing)(xing)，對光線的(de)高反射性(xing)(xing)，從(cong)(cong)而(er)(er)使這(zhe)種(zhong)(zhong)缺陷得到進一(yi)步放(fang)大(da)，就形(xing)成所(suo)說的(de)黃(huang)變(bian)(bian)(bian)。因(yin)此(ci)，電泳(yong)前的(de)幾道水洗(xi)非常(chang)關鍵，不(bu)僅要保(bao)證水洗(xi)水質，還(huan)要保(bao)證水洗(xi)溫(wen)(wen)度和水洗(xi)時間。

3．氧化(hua)槽液(ye)被(bei)硝酸污染而(er)引起(qi)的黃變(bian)現(xian)象(xiang)

為了達到(dao)較好(hao)(hao)的(de)(de)(de)(de)(de)除灰效果，在中(zhong)和槽里(li)添加(jia)一定(ding)比例的(de)(de)(de)(de)(de)硝(xiao)酸(suan)(suan)(suan)本無可厚非，但(dan)是如果中(zhong)和后(hou)水(shui)(shui)洗(xi)控制不好(hao)(hao)，硝(xiao)酸(suan)(suan)(suan)就會(hui)被(bei)帶到(dao)氧(yang)(yang)(yang)(yang)化(hua)(hua)槽，氧(yang)(yang)(yang)(yang)化(hua)(hua)槽里(li)的(de)(de)(de)(de)(de)硝(xiao)酸(suan)(suan)(suan)根(gen)達到(dao)一定(ding)濃度(du)時，就會(hui)對(dui)(dui)氧(yang)(yang)(yang)(yang)化(hua)(hua)造(zao)成一定(ding)的(de)(de)(de)(de)(de)影響，甚至引起電(dian)泳型材的(de)(de)(de)(de)(de)黃(huang)變。氧(yang)(yang)(yang)(yang)化(hua)(hua)過程中(zhong)，進(jin)(jin)入氧(yang)(yang)(yang)(yang)化(hua)(hua)膜(mo)孔(kong)中(zhong)的(de)(de)(de)(de)(de)硝(xiao)酸(suan)(suan)(suan)根(gen)會(hui)對(dui)(dui)氧(yang)(yang)(yang)(yang)化(hua)(hua)膜(mo)起到(dao)刻蝕(shi)作用(yong)(yong)，腐蝕(shi)氧(yang)(yang)(yang)(yang)化(hua)(hua)膜(mo)的(de)(de)(de)(de)(de)阻(zu)擋層(ceng)(ceng)，使氧(yang)(yang)(yang)(yang)化(hua)(hua)膜(mo)孔(kong)變深，進(jin)(jin)而(er)改變膜(mo)孔(kong)的(de)(de)(de)(de)(de)結(jie)構。這種(zhong)腐蝕(shi)對(dui)(dui)氧(yang)(yang)(yang)(yang)化(hua)(hua)膜(mo)產生兩種(zhong)影響：1、氧(yang)(yang)(yang)(yang)化(hua)(hua)膜(mo)的(de)(de)(de)(de)(de)阻(zu)擋層(ceng)(ceng)變薄，與(yu)鋁基體接合的(de)(de)(de)(de)(de)緊密性變差，進(jin)(jin)而(er)造(zao)成氧(yang)(yang)(yang)(yang)化(hua)(hua)膜(mo)的(de)(de)(de)(de)(de)附著力降低。2、在正常水(shui)(shui)洗(xi)條件(jian)下，很難把膜(mo)孔(kong)中(zhong)的(de)(de)(de)(de)(de)硫酸(suan)(suan)(suan)根(gen)除去。這種(zhong)條件(jian)下所生產的(de)(de)(de)(de)(de)電(dian)泳型材同(tong)樣會(hui)有黃(huang)變現(xian)象。怎樣來避免這種(zhong)黃(huang)變現(xian)象呢？在燙洗(xi)槽前(qian)的(de)(de)(de)(de)(de)純水(shui)(shui)槽中(zhong)添加(jia)中(zhong)和劑，調PH值8~9.5，水(shui)(shui)洗(xi)2~3分鐘，用(yong)(yong)胺(an)根(gen)中(zhong)和氧(yang)(yang)(yang)(yang)化(hua)(hua)膜(mo)孔(kong)中(zhong)的(de)(de)(de)(de)(de)硫酸(suan)(suan)(suan)根(gen)，再進(jin)(jin)行電(dian)泳生產，就不會(hui)出現(xian)黃(huang)變現(xian)象了。

4．化過度引起(qi)的黃變(bian)現象(xiang)

目前(qian)市場(chang)上所(suo)使用電泳(yong)漆(qi)(qi)(qi)(qi)基(ji)本(ben)都是(shi)(shi)在(zai)(zai)180℃X30min條(tiao)(tiao)件(jian)下烘(hong)烤固化(hua)的(de)(de)(de)。在(zai)(zai)正(zheng)常(chang)條(tiao)(tiao)件(jian)下，漆(qi)(qi)(qi)(qi)膜基(ji)本(ben)上不(bu)(bu)會發生(sheng)黃(huang)變(bian)(bian)。但(dan)是(shi)(shi)有(you)(you)的(de)(de)(de)廠(chang)(chang)家(jia)固化(hua)爐溫(wen)(wen)(wen)度很不(bu)(bu)均勻，局部溫(wen)(wen)(wen)度甚至相差(cha)30℃以(yi)上；有(you)(you)的(de)(de)(de)廠(chang)(chang)家(jia)固化(hua)爐的(de)(de)(de)溫(wen)(wen)(wen)控系(xi)統差(cha)，實際溫(wen)(wen)(wen)度與顯(xian)示溫(wen)(wen)(wen)度相差(cha)太大，質量(liang)較差(cha)的(de)(de)(de)電泳(yong)漆(qi)(qi)(qi)(qi)在(zai)(zai)這種(zhong)條(tiao)(tiao)件(jian)下黃(huang)變(bian)(bian)現象非(fei)常(chang)明顯(xian)，甚至像著(zhu)了色似的(de)(de)(de)。質量(liang)好的(de)(de)(de)電泳(yong)漆(qi)(qi)(qi)(qi)對這種(zhong)極端(duan)條(tiao)(tiao)件(jian)的(de)(de)(de)承受能力比較強，有(you)(you)的(de)(de)(de)電泳(yong)漆(qi)(qi)(qi)(qi)即使在(zai)(zai)230℃的(de)(de)(de)條(tiao)(tiao)件(jian)下烘(hong)烤，也不(bu)(bu)會發生(sheng)黃(huang)變(bian)(bian)現象。為了防止黃(huang)變(bian)(bian)的(de)(de)(de)產生(sheng)，爐溫(wen)(wen)(wen)的(de)(de)(de)均勻性(xing)、溫(wen)(wen)(wen)控系(xi)統的(de)(de)(de)靈敏性(xing)是(shi)(shi)必(bi)需(xu)的(de)(de)(de)，使用質量(liang)好的(de)(de)(de)電泳(yong)漆(qi)(qi)(qi)(qi)也是(shi)(shi)必(bi)要的(de)(de)(de)。

5．電泳漆本(ben)身引(yin)起的黃變現象

陽極電(dian)泳(yong)(yong)漆主要是(shi)(shi)由丙烯酸樹(shu)脂(zhi)和胺(an)基樹(shu)脂(zhi)組成的。電(dian)泳(yong)(yong)型材在烘烤過程中，樹(shu)脂(zhi)發生(sheng)交聯反應(ying)，生(sheng)成平整、透明的涂(tu)(tu)膜。但是(shi)(shi)有(you)些電(dian)泳(yong)(yong)漆廠家由于生(sheng)產工藝(yi)的不(bu)成熟(shu)，或者是(shi)(shi)為(wei)了降低成本(ben)使(shi)用(yong)(yong)質量(liang)較(jiao)差的化工原料，從(cong)而(er)導致其固(gu)化范圍(wei)比較(jiao)窄。烘烤稍(shao)(shao)有(you)不(bu)足，漆膜硬度不(bu)夠；烘烤稍(shao)(shao)稍(shao)(shao)過了頭，漆膜就會發生(sheng)黃變，給(gei)生(sheng)產管理帶來一定(ding)(ding)的困難。所以(yi)建議大家還是(shi)(shi)選(xuan)用(yong)(yong)產品質量(liang)穩定(ding)(ding)、有(you)一定(ding)(ding)知名度的涂(tu)(tu)料供應(ying)商。而(er)追夢馬(ma)電(dian)泳(yong)(yong)漆，多年從(cong)業經驗，是(shi)(shi)您的不(bu)二選(xuan)擇！