Softening inspection of coated plastic components

对于塑料基体上涂覆的有机涂层,它们相互接触可能容易受到增塑剂从塑料组分迁移到有机涂层中,引起表面软化現象而影响质量.所以,对于塑料基体上的有机涂层通常需测定其软化性能.本方法适用于测定在特殊的暴露条件下,有机涂层表面被塑料组分软化的相对程度,但不适用于在该试验条件下检验可以渗出增塑剂的塑料组成.      '

1、试验仪器

涂层软化性测定,可采用涂层硬度试验仪来进行.该仪器由两只扁平投常青铜环组成.较铬环由仪器的支架固定,支架上支撑着画个泡管式水平仪,并由环的顶部嵌上一只垂直的螺钉.泡管式水平仪用来测量硬度试验仪程动的振幅,振幅的变化速率被用来作为试验表面软化的标准.

硬度试验仪应装有明亮的玻璃罩,使其在箱作期间不受空气流动的影响.（相关仪器：硬度计）

2、 试验条件

(1)试样.应在23℃±2Ct:和50%±5%相对湿度下放置40 h以上.在有争议情况下,其公差应为±1 ℃和±2%相对湿度.

(2)试验温度及相对湿度,除非在测试方法中另有规定,通常为23℃ ±2℃和50% ±5%相对湿度的标准实验室大气条件下进行.有争议时,其公差为±1℃和±2%相对湿度.

3、试样准备

 (1)塑料样板需要从一块平滑、均匀的薄板上切下50mm x100mm x 0.25mm的片,浮凸或不均匀的样板可以改成平滑薄板的形式.

(2)有机涂层的样板需要是除在玻璃板上,干膜厚度为 0.025 一0.05前.        

(3)According to有机除料的类型,按所建议的条件特法层干燥或固化,或两者同时进行.用于本测试中的仅是那些无针孔、不井裂、无橋度或无其他缺陷的涂层.

4、硬度仪的校正

(1) Place the Tester on the flat glass of the horizontal test bench for calibration. After adjusting to the level, start to swing the instrument, so that the air bubbles on the left tube are slightly re-injected into the mark. Cover the cover, and when the left tube is on the When the bubbles on the right tube just don’t reach the mark, start counting (starting from zero), and when the bubbles on the right tube just don’t reach the mark, stop counting.

(2) The Hardness Tester should complete 50 swings back and forth within 60 s, 5 s. If the swing times are not 50 times, adjust the angle of the bubble tube on the left until the correct value is given. For the time required for 50 swings, It can be adjusted by changing the magnetic code on the vertical spiral geometry.

5. Test steps

(1) For each plastic composition to be tested, prepare two organic coating samples, and test them after one week.

(2) According to the hardness correction method, measure the initial hardness value of the commercial block painted sample in the direction parallel to the length of the sample, multiply the number of swings back and forth by 2, and obtain the corresponding hardness value.     

(3) In an oven at 50°C, heat the sample (plastic sample and painted sample) for 30 , min, carefully place the warm plastic sample on the surface of the organic layer, and use rubber to break the roots to ensure that the two pieces The uniform contact between the samples should be done carefully to prevent air or dust particles from remaining on the plastic samples.                                    

(4) Use packaging aluminum foil or other soft film as the interlayer material, sea rubber to cover the plastic sample, then cover the glass plate, add enough magnetic code to make the mass reach 900 g

(including the glass rice bowl on the top). In order to accelerate the balance of the overall temperature, the magnetic code and the glass rice bowl must be preheated at 5o℃ for 1 h before use.

(5) Put the above-pressed sample in an oven at 50°C, keep it warm for 4 hours, and then tear it apart, so that the plastic sample is kept in the sterile atmosphere for later use.

(6) According to the test conditions, after the painted sample is placed for 4~24 hours, the hardness value is measured by the same method as the hardness correction.

(7) Press the sample again and send it back to the general box. Oven at 50°C for 20 h, and then measure the degree.