(1) Purpose and definition.
When printing food packaging such as candy and bread, after printing, it needs to be impregnated with hot-melt wax to maintain the quality of the food. Therefore, it is required that the ink does not change color and does not bleed in hot-melt wax. performance.
Although there are many kinds of waxes used for impregnation, paraffin wax is mostly used for the wax resistance test of Zumuding oil plastics.
(2) Appliances and materials.
1. Utensils.
(1) Minor Ink Knife.
(2) Squeegee.
(3) Test tube and metal test tube rack, the outer diameter of the test tube is 1.5 cm, and the length is 10 cm.
(4) Small tweezers.
(5) Oven.
2. Materials.
(1) Scratch sample paper.
(2) Paraffin (white, melting point 60-80 ℃).
(3) Method.
Scratch a sample according to the determination of color, but leave no thick ink layer, and let it dry at room temperature.
Cut the ink scraping sample into a small strip with a width of about t15 cm and a length of about 10 cm. Put half the length of paraffin in the test tube, and place it in an oven at 115±2°C together with the test tube rack. After all the paraffin in the test tube is melted, put the ink scraping sample cut into small strips into the test tube and make half of it submerged in the melted paraffin, and start timing at the same time.
After 5 minutes, take the test tube out of the oven, use tweezers to take out the ink and scrape H, and drop the residual wax on the paper strip back into the test tube while it is hot.
After the wax has cooled down, observe the degree of dyeing of the paraffin wax and the degree of color change . Then grade according to the regulations listed in the table.
(4) Matters needing attention.
1. The drying degree of the ink scraping sample has an influence on the test result.
2. Among the grades, grade 5 is the best and grade 1 is the worst. When grading, if the degree of paraffin wax staining does not match the degree of change of the oil silk scraping sample, the worse one of the two is used for evaluation.
3. The change of paraffin wax after heating should also be considered, which can be verified by doing a blank test.
4. The wax layer on the ink scraping sample should not remain too thick, which will affect the observation and judgment.
5. In general practice, it is often not divided into 5 grades (grades), because as long as the paraffin wax is dyed, the wax resistance of the ink is poor.
