彩涂板的开裂和剥落原因

彩涂板涂膜隆起成泡或破裂成皮。开裂、起泡、脱落的缺陷通常在彩涂卷重新开卷时或在客户使用过程中发现。

开裂现象通常是在彩涂板的使用过程中发现可目测的裂纹或裂缝，裂纹从小到大，最终导致彩涂板膜层被完全破坏。脱落现象通常是涂层从钢带表面成片状掉下，伴有局部或全部剥落的现象。

根据剥落程度可分:直径约5mm以下很薄的小片局部脱落称为鳞片剥落，呈直径在5mm 以上比较大片的局部剥落称为皮壳剥落，比彩涂板皮壳剥落更大的脱落(或撕下)称脱皮剥落，上涂层与底涂层之间脱落称为层间剥落。
产生原因:
(1)涂层前处理不当，基板有蜡、油、水等，向外扩散时其压力把漆膜鼓起，特别是透气性差的产品，影响了层间的附着力;
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(2)底涂层未干就覆盖面涂层，致使底面两层间的附着力变差，或完全丧失了附着力;(3)涂层前表面处理后至涂层施工的间歇时间过长;
(4)涂层内部存有针孔、漏涂以及气泡等缺陷，使涂膜要承受应力，特别在急冷过程、涂膜疲劳过程等应力存在时，容易发生膜层开裂;
(5)涂层不适当，底涂层或面涂层过厚;
(6)涂料选择不当或底面层涂料不匹配，引起层间附着力不良，涂料的力学性能不好，柔韧性不佳，使膜层在受温度剧变或压缩外力时产生开裂。
排除方法: 不城
(1)涂层前基板确保无蜡、油、水等杂物并且表面没裂缝;(2)确保底涂层完全固化后再涂面涂层;
(3)应选择配套性良好的底面层涂料品种，以提高涂层间的附着力，施工时应按工要求严格控制底面涂层的厚度;细动资里到期热
(4)严格控制上机涂料的质量，避免涂料施工时产生“针孔”、“气泡”等缺陷;

(5) 彩涂卷在下线后切忌立即使用于温度变化急剧的场合。

The film swells into bubbles or breaks into skin. The defects of cracking, blistering and falling off are usually found in the rewinding of color coated coil or in the process of customer use.

Cracking phenomenon is usually found in the use of color coated sheet can be visually observed cracks or cracks, cracks from small to large, eventually leading to the film was completely destroyed. The peeling off phenomenon is usually that the coating falls off the surface of the steel strip in flakes, accompanied by partial or total peeling off.

According to the degree of peeling off, it can be divided into: local peeling off of small pieces with a diameter of less than 5mm is called scale peeling off, local peeling off with a diameter of more than 5mm is called shell peeling off, peeling off (or tearing off) larger than shell peeling off is called peeling off, and peeling off between the upper coating and the primer is called interlayer peeling off.

The causes are as follows

(1) Improper pre-treatment of coating results in wax, oil and water on the substrate. When it diffuses outward, the pressure will bulge the film, especially for products with poor air permeability, which affects the adhesion between layers;

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(2) When the primer is not dry, it covers the surface coating, resulting in poor adhesion between the two layers or complete loss of adhesion（ 3) The intermittent time from surface treatment before coating to coating construction is too long;

(4) There are pinholes, missed coating and bubbles in the coating, which make the coating bear stress, especially in the process of rapid cooling and film fatigue;

(5) Improper coating, too thick primer or top coating;

(6) Improper selection of coating or mismatching of bottom coating result in poor adhesion between layers, poor mechanical properties and poor flexibility of coating, which leads to cracking of coating when subjected to drastic temperature change or external compression force.

Exclusion: no city

(1) Before coating, the substrate shall be free of wax, oil, water and other impurities, and the surface shall be free of cracks（ 2) Ensure that the primer is completely cured before the top coat is applied;

(3) In order to improve the adhesion between the coatings, it is necessary to select the type of primer coating with good matching, and strictly control the thickness of the primer coating according to the construction requirements; Maturity fever in small mobile capital

(4) Strictly control the quality of coating to avoid pinhole, bubble and other defects;

(5) Color coated coil should not be used immediately in the situation of sharp temperature change after offline.