本文介绍了涂料检测的目的，以及影响涂料成品质量的因素。探讨了涂料检测的局限性。通过检测实例说明选用适宜的检测方法，可既快又省地帮助客户分析解决涂料应用过程中产生的问题。
0引言
随着我国涂料工业的不断发展壮大，以及涂料产品应用范围的拓展和延伸，涂料的用户群也在不断增加。限于专业知识等方面的原因，不少用户在涂料的使用过程中会产生各种问题，所以涂料产品的检测越来越受到重视。我国的涂料检测标准主要分方法标准和产品标准两类。其中方法标准是指针对某一项性能的检测方法，可分为专用检测方法和通用检测方法；产品标准是综合涂料产品的主要性能，并统一规定其技术指标的标准，可分为国家标准、行业标准和企业标准。
1涂料检测的目的
（1）采用各种光谱仪、色谱仪、电子显微镜等分析仪器对涂料以及原材料的组成进行成分剖析，测定相关参数，有助于涂料研发工作的进行。
（2）生产厂家通过涂料生产过程中对涂料产品的各项主要性能指标的检测，有助于其进行生产中控以及成品质量控制。
（3）通过对不同涂料产品的相同性能指标的检测，获得一系列检测数据，从而进行不同涂料产品的比较，有助于涂料产品的研发、成果鉴定以及产品的筛选。如一些重大工程的涂料产品投标检测、新产品的鉴定检测、涂料用户的供应商筛选检测。
（4）通过对涂料产品进行国家强制标准以及一些相关标准的检测，以确定产品合格与否，有助于涂料行业进行质量控制以及产业政策落实。如国家和省市每年的涂料产品监督抽查检测，以及涂料行业的生产许可证检测等。
（5）通过选用适宜的检测方法，有助于分析检测涂料的产品质量，解决实际应用中产生的问题。如许多用户在涂料使用前为确认产品质量而进行的第三方检测。
2涂料检测的局限性
目前涂料检测在涂料产品的质量控制、研发、政府监督检验、筛选、成果鉴定等方面受到重视。但由于涂料产品的特殊性，一些用户在实际应用过程中产生了问题，有时却难以通过相关的检测进行分析和判断。
For the manufacturer, the coating is a finished product, but for the user, the coating is a semi-finished product, which can only be called a finished product after the coating is completed and the film is formed. Factors that affect the quality of finished coatings include: substrate (substrate material, substrate pretreatment, etc.); construction (construction equipment and methods, coating maintenance, etc.); coating (coating type, coating quality, coating supporting system, etc.) ). However, the adopted paint product standard is to test the performance index of the paint itself under uniform conditions, and cannot fully consider the influence of various situations in the actual application of the paint. When many users encounter paint application problems, they want to find the cause of the problem through testing, but they often encounter many problems. Some paints with problems have no relevant product standards; some test results that apply the relevant paint product standards cannot help analyze and solve question. This is due to the limitations of testing standards and methods, and it is not possible to carry out relevant testing on the entire process of coating application. This requires the testing agency to suggest the most suitable testing methods and means to the user according to the actual situation of the coating application to help them analyze and solve the problem. A few detection examples are selected below to illustrate that choosing an appropriate detection method can solve the problem of coating application quickly and economically.
3 detection examples
3.1 Example 1
3.1.1 Situation analysis
There was a coating corrosion phenomenon shortly after the opening of a building. The user chose fluororesin coatings, and the main characteristics of fluororesin coatings are excellent weather resistance and salt spray resistance. However, the physical samples sent by customers corroded. Seriously, some parts of the substrate have also been corroded. According to the situation reported by the customer and the situation of the sample, it may not be the fluororesin coating used in the actual construction. We use pyrolysis GC-MS method, assisted by infrared spectroscopy, to analyze and confirm whether the sample is fluororesin coating.
3.1.2 Test results
The test results of the physical samples are shown in Table 1.
3.1.3 Result analysis
Due to the serious corrosion of the physical sample and the unsatisfactory surface condition of the sample, it is not possible to only use the qualitative method of film-forming resin-infrared spectroscopy, but to use the more accurate pyrolysis GC method. Through the combined use of these two methods, a more accurate conclusion is drawn, which proves that the actual coating is not fluororesin coating.
3.2 Example 2
3.2.1 Situation Analysis
An automobile manufacturer found that there were many complaints about several automobile products, which mainly reflected that the gloss of the paint decreased after a period of use, which affected its appearance quality. The manufacturer has carried out a more stringent accelerated aging test on the relevant products, and the light loss rate is not very high after the test, which is inconsistent with the complaint. After understanding the relevant situation, we use the same accelerated aging test, but we use two geometric conditions of 60° and 20° in the measurement of gloss at the same time, in order to obtain a more obvious distinction.
3.2.2 Test results
The gloss test results of the samples before and after the accelerated aging test are shown in Table 2.
3.2.3 Result analysis
There are generally three geometric conditions for the measurement of gloss: 20°, 60° and 85°. The 60° geometry is suitable for all paint films and is the most commonly used, but if it is a high gloss (60° gloss higher than 70 units) paint, the 20° geometry is more suitable, because the 20° geometry is more suitable for high gloss paints. Membranes give better resolution. The car manufacturer used the geometric condition of 60°, and the loss rate of the test result is not large, but after we adopt the geometric condition of 20°, the resolution is improved, and the light loss rate obtained is far greater than the measurement result under the geometric condition of 60°. By selecting appropriate test conditions, the actual situation of gloss changes can be better restored, which is helpful for enterprises to analyze problems and facilitate them to better improve and improve product quality.
3.3 Example 3
3.3.1 Situation analysis
一轮毂生产厂家遭到客户投诉，反映使用一段时间后汽车轮毂表面清漆脱落。该生产厂进行了很多检测也没找到问题的症结所在，面临着大量退货的尴尬局面。据了解，厂家的工艺流程并未改动，但对原先的配套涂料体系作了改动。原先的配套涂料体系是：底材+粉末涂料+黑色涂料+透明清漆，改动后的配套涂料体系是：底材+粉末涂料+透明清漆。漆膜脱落说明附着力下降，但两种配套涂料体系的初始附着力相同，是在使用了一段时间后才开始出现清漆脱落现象。分析问题可能出在粉末涂料上——厂家可能选用了耐候性差的环氧粉末涂料。现在使用较多的粉末涂料主要有环氧、聚酯/环氧、聚酯、丙烯酸等品种。由于环氧树脂中含有芳香醚键，经日光（紫外线）照射后易降解断链（图1），耐候性较差，在户外使用一段时间后，就会出现失光、粉化现象，不宜用作户外面漆。分析可能是厂家在粉末涂料上直接罩涂透明清漆，汽车轮毂在户外使用一段时间后，粉末涂层出现粉化而造成涂层层间附着力下降，产生了清漆脱落现象，而原先配套的黑色涂料耐候性好就不存在此问题。
分析了可能产生问题的原因后，设计了检测方案，先测定初始附着力，然后进行人工加速老化试验，每100h检测二次附着力（涂层间）和粉化（表面涂层）情况。选用3种配套涂料体系：
A体系：底材+粉末涂料；
B体系：底材+粉末涂料+透明清漆；
C体系：底材+粉末涂料+黑色涂料+透明清漆。
3.3.2检验结果
3种配套涂料体系的检测结果见表3。
3.3.3结果分析
由表3可知：厂家用的粉末涂料耐候性不好，200h就出现了粉化；3种配套涂料体系的初始附着力都不错；100h后B体系的附着力开始下降，到200h后附着力出现了明显下降。通过检测验证了先前的分析，正是由于粉末涂层的粉化造成了涂层层间附着力下降，产生清漆脱落现象。笔者通过对问题的分析，选用了适宜的检测方法帮助厂家找出原因。同时建议厂家选用耐候性好的聚酯、丙烯酸类粉末涂料，为客户提供了解决方案。
4结语
The coating testing process is a process of simulating the actual application of coatings. A better testing solution is to select substrates similar to the actual application of coatings, similar construction conditions, and suitable testing methods and testing conditions. From the above test examples, it can be seen that the test results may be affected by the condition of the test sample, the choice of test conditions, and the supporting system of the product. Sometimes it is necessary to use several different test methods to achieve the purpose of verification. An accurate conclusion; sometimes it is necessary to select test conditions that are close to the actual situation according to the condition of the product in order to obtain a result that is close to the actual situation; sometimes it is necessary to analyze the cause of the problem and design a reasonable detection plan to verify it. Of course, there are various situations in the actual application of coatings, and the existing testing standards, methods and means sometimes cannot meet the testing requirements. In order to give customers a satisfactory result, professional testing agencies are required to choose appropriate testing methods and test conditions as much as possible to help customers analyze reasons and solve problems.
