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陽極沉積法和陰極沉積法的區(qū)別

1577 人參與 2011年11月21日 00:57 分類 : 電泳工藝電泳原理評論

? Anodic Versus Cathodic?????????? 陽極沉積法和陰極沉積法的區(qū)別

Based upon the method of deposition, two types of electropaint have been developed: anodic and cathodic. The anodic types were commercialized first for two reasons:

基于沉積的電泳方式，已經(jīng)開發(fā)了陽極電泳漆和陰極電泳漆兩種類型的電泳漆陽極電泳漆首先投入正式生產(chǎn)有兩個原因： The earlier resin technology was based on resins which contained acid groups. These could be neutralized to allow them to become soluble in water. 早期的樹脂制造技術(shù)都是以含酸基團的樹脂為基礎(chǔ)，中和后，他們可以溶于水。 When the solubilized resin was deposited, it regained its acidic function. This acidity permits ready crosslinking (curing) when the coating is baked. 當水溶性樹脂沉積后，它可以恢復(fù)其酸性基團的功能。當此涂層被烘干時，這種酸性基團可使漆膜其迅速交聯(lián)（固化）。 The ability to produce a cathodic-type resin was available long before the resins were introduced commercially in 1975. Two major problems had to be overcome before commercialization became possible: 陰極電泳漆的樹脂在1975年陽極型樹脂商品化之前很長一段時間內(nèi)就有能力制造了，但其正式投產(chǎn)之前要克服以下兩個主要的問題。 A method was needed to make alkaline polymers cure at temperatures low enough to ensure body integrity. 降低堿性聚合物固化的溫度，同時還要確保漆膜的均一性。 The corrosivity of the bath solution had to be reduced. 必須降低槽液的腐蝕性。 The process of curing thermosetting resins is called "crosslinking".? During this process, which is driven by heat, the relatively small molecules deposited are chemically intertwined to form a single uniform film. 熱固型樹脂的固化過程稱為交聯(lián)，這個過程是以熱為動力，較小分子的沉積膜經(jīng)化學交聯(lián)形成一個完整的表面。. The reactions involved in crosslinking deposited film depend upon the film's chemical environment. The structures that are obtained by these curing reactions are essential for the practical value of the coating. Reaction conditions also determine bake time, temperature and, therefore, energy consumption. 電泳漆膜交聯(lián)的反應(yīng)取決于涂膜的化學反應(yīng)環(huán)境，靠這些固化反應(yīng)獲得的涂膜結(jié)構(gòu)，對其防腐性能]具有真正的實際價值。反應(yīng)的條件也決定了烘干時間及溫度，以及消耗能源。 Anodic electrocoats usually have a pH of approximately 9.0; however, the deposited film is, in contrast, highly acidic. Acid catalyzed crosslinking reactions can be used with little difficulty. 陽極電泳槽液一般pH約為9，可沉積涂層卻是高酸性。酸催化的交聯(lián)反應(yīng)比較容易進行。 The situation is somewhat different for cathodic materials. As with anodic resins, the crosslinking can be either internal or external. Because of the alkaline nature of the uncured cationic film, external linking reactions are sluggish. 對陰極電泳就有所不同了，陽離子樹脂的交聯(lián)反應(yīng)可以在內(nèi)部或外部進行，但因未固化陰離子涂膜具有堿性，所以外部交聯(lián)反應(yīng)較緩慢。 Internal crosslinking is carried out by urethane groups mixed with the cathodic resin. These crosslinkers are stable in water at normal bath temperature but become reactive at curing temperatures.? Special procedures are used to ensure that these crosslinkers will not react at bath temperature to cause instability. 內(nèi)部的交聯(lián)是靠與陽離子樹脂混合的氨基甲酸脂基團進行的。這些交聯(lián)劑于正常槽液溫度下在水中很穩(wěn)定，但在固化溫度下就變得活潑起來。通過采用一些特殊的處理工藝，確保這些交聯(lián)劑不會在槽液溫度起反應(yīng)而引起槽液的不穩(wěn)定性。 Although numerous types of resins may be suitable for electrodeposition, the most common ones are thermosetting. Thermosetting resins fuse or melt when baked into a hard, uniform, solvent-resistant film. 雖然多種樹脂都可以適用于電泳涂裝，但最常見的是熱固型的熱固型的樹脂在烘干時融合或融化成為一堅硬，均勻的耐溶劑涂膜。 Resin chemists must ensure that the resin has particular properties of hardness, flexibility, adhesion, water-and-chemical resistance, pigment wetting, and others. To be used as an electropaint, the resin must also have the following characteristics: 研發(fā)人員必須確保樹脂具有硬度，柔韌性，附著力，耐水及化學品性，顏料濕潤性及其它特性。用于制造電泳漆的樹脂還必須具備如下特性： It must be soluble or dispersible to form a stable solution even when subjected to a wide variety of production conditions. 樹脂必須可溶解或分散成一種穩(wěn)定的溶液，可以適應(yīng)多種生產(chǎn)條件。 It must deposit onto an electrode to form a smooth, dense, insulating, wet film which also contains pigment. 樹脂必須能沉積在一個電極上，形成一光滑，致密，絕緣，并含有顏料的濕涂膜。 It must be able to coat a part which is complex in shape. 必須能夠泳涂外形復(fù)雜的工件。 It must resist re-dissolution when rinsed. 必須在沖洗時不再被溶解掉。 It must become mechanically and chemically stable upon baking so that the resulting film can fulfill its protective and/or decorative requirements. 經(jīng)烘干后的涂膜具有機械及化學穩(wěn)定性，以滿足保護和（或）裝飾的需要。 Although the principle of electrodeposition gained acceptance with the anodic systems, it was not until the cathodic method was developed that electrodeposition became the common method for priming automobiles. The cathodic method has the following advantages: 雖然電泳涂裝的原理是從陽極電泳系統(tǒng)獲得的，但是直到開發(fā)出了陰極電泳涂裝法以后，電泳涂裝才成為汽車涂底漆普遍采用的方法。陰極電泳漆有以下優(yōu)點： It achieves corrosion resistance at low film thickness. 較低的膜厚具有良好的防腐蝕性。 It permits throwpower to interior surfaces without penalty of over-build on exterior surfaces. 保證工件內(nèi)表面泳透力的同時，外表面上涂膜也不會過厚。 It achieves bimetallic joint corrosion resistance required by the increased use of galvanized metal. 雙金屬復(fù)合層也能獲得良好的防腐蝕性，可適應(yīng)日益擴大的鍍鋅鋼板用量的需求。 It possesses saponification resistance and long-term adhesion retention over an entire galvanized body panel. 它具有耐皂化性，在全鍍鋅的車身板上可長期保持其附著力。 It requires substantially less electrical consumption for deposition and, as a result, less refrigeration for cooling. 電泳本身耗電量少，從而用于冷卻的冷量也少。 It achieves gloss and hold-out with and without spray primers. 本身具有足夠的光澤度，可噴涂或不噴涂中涂，同時在沒有中涂的情況下也不影響面漆的亮度。 The prime advantage for cathodic systems, however, is superior corrosion protection. With anodic electrodeposition, metallic ions from the part being coated often become included in the deposited film. This condition results from anode reactions when current is applied. The presence of the iron ion in the film provides a readily available site for rust to start. In addition, when deposited, cationic resins are alkaline in nature and tend to be natural corrosion inhibitors. 其實，陰極電泳的最主要優(yōu)點還是防腐蝕性非常優(yōu)良。材用陽極電泳時，由于通電時的陽極反應(yīng)從被涂工件上溶下的金屬離子常常包含在漆膜中，。在漆膜中存在的鐵離子就成了開始生銹的誘因。另外，沉積時，陽粒子樹脂呈堿性，這樣就成為天然的緩蝕劑。

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