Overview
The ability of color paint coatings to resist solvent action after curing is one of the key indicators for evaluating their physicochemical properties and durability. Solvent resistant wipes provide a standardized test method for quantitatively evaluating this performance by simulating the synergistic effect of mechanical wiping and solvent erosion. This method is widely used in the evaluation of coating quality in the fields of automobiles, furniture, industrial equipment and consumer electronics, and has important reference value for predicting the performance of coatings in actual use environments.
Test Principle:
The test is based on reciprocating the cured paint surface using a wipe tip impregnated with a specific solvent under a specified load. The basic principle is that the solvent swells, softens or dissolves the paint film, and at the same time applies physical stress to mechanical friction. The paint film is evaluated by recording the number of wipes required to rub through the substrate, or by observing the change in the surface state of the paint film after a fixed number of wipes. The main instrument is composed of a load device, a reciprocating drive mechanism, a fixed specimen table and a standard wiping head. Test loads, wipe strokes and speeds must strictly follow the relevant standards.
Test parameters
The accuracy and comparability of test results are highly dependent on the control of key parameters. The main parameters include: the chemical type of solvent (such as ethanol, xylene, ethyl acetate, acetone, etc.), the wiping load, the single wiping stroke, the wiping speed, and the ambient temperature and humidity. Different industries and application scenarios correspond to different test standards, including ASTM D5402, ISO 15184, and GB/T 23989. When choosing a solvent, consider its similarity to the solvent that the coating is expected to contact or its representativeness as a strong solvent.
| Parameter categories | Typical example |
| Commonly used solvents | Ethanol, xylene, butyl acetate |
| Load range | 500 g to 1000 g |
| Evaluation method | Number of scuffs or surface condition level |
| Reference Standards | ASTM D5402, ISO 15184 |
Operation process
The operation process begins with the preparation of the specimen. The specimen should be a flat, defect-free coating sample and be cured and conditioned under standard conditions. Before testing, it is necessary to accurately weigh and install the wiping head to ensure that it is perpendicular to the surface of the specimen. Evenly impregnate the prescribed solvent onto the wiping material. After starting the instrument, the wipe head reciprocates at a constant speed at a set load. The operator needs to continuously observe the changes in the paint film, and when the paint film is rubbed through to the exposed substrate, the instrument will automatically or manually stop and record the total number of wipes. If the fixed number method is adopted, the surface gloss, color change or damage of the paint film will be evaluated immediately after the test, and the grade will be determined with reference to the standard rating chart.
Analysis of results
The results are usually expressed as "number of solvent wipes" or "solvent resistance level". The higher the number or the better the grade, indicating a higher cross-linking density, a more complete cure, or a stronger solvent resistance of the resin itself. The main factors affecting the results come from three aspects: the coating itself, such as the chemical structure of the resin, the volume concentration of the pigment, the amount of curing agent and the degree of curing; Test conditions, such as solvent polarity, wipe pressure and speed; and the quality of substrate treatment and sample preparation. Abnormal results need to be comprehensively analyzed in combination with the formula and process.
Notes:
This method is not only used for quality control and in-plant inspection of coated products, but also for optimizing resin systems, curing conditions, and formulation ratios during R&D. By comparing test data from different formulations or processes, product improvement can be effectively guided. During the test, it is necessary to pay attention to safety protection and operate volatile solvents in a well-ventilated environment. Thoroughly clean the instrument components after each test to prevent solvent residues from affecting subsequent tests. Calibrating instrument loads and strokes and regularly verifying instrument status using reference templates are necessary measures to ensure long-term data reproducibility.
Cited Literature
ASTM D5402-15, Standard Practice for Assessing the Solvent Resistance of Organic Coatings Using Solvent Rubs.
ISO 15184:2012, Paints and varnishes — Determination of film hardness by pencil test.
GB/T 23989-2009, Determination of solvent resistance to coatings.