The method of using special silicone heat transfer hot melt glue is as follows:
Material preparation and mixing
Silicone mixing: Mix silicone and curing agent in a ratio of 100:2, add 8-10% color paste and mix well to ensure uniform color and no particles.
Hot melt glue dilution: Use toluene or cyclohexanone to dilute the hot melt glue and adjust to a suitable viscosity for screen printing.
Printing silicone layer
Screen the prepared silicone onto a high-temperature resistant release film (such as PET silicone special film) through a screen. After screen printing once, bake until the surface is dry. Repeat printing until the required thickness and color effect are achieved, and finally bake it thoroughly dry.
Screen plate selection: 80-120 mesh screen for thick plate printing, 300 mesh screen for dot effect printing.
Printing coating glue
Mix the silicone heat transfer coating glue evenly in a ratio of 100:3(for reverse transfer) or 100:5(for positive transfer), print it on the silicone surface, wait for 5 minutes after each printing, bake it dry and then repeat printing to ensure that the glue layer evenly covers the silicone surface.
Printing hot melt glue layer
Print the diluted hot melt glue on the surface of the silicone, print 6-8 times, wait 5 minutes after each printing, bake until the surface is dry, and ensure that the thickness of the hot melt glue layer is uniform and there are no bubbles.
Baking and curing
Put the printed film into the oven, first bake at 80℃ for 20-30 minutes, and then bake at 150℃ for 30 minutes to ensure that the glue is fully cured and there is no solvent residue.
Environmental protection requirements: The finished product after baking must be free of solvent smell, otherwise it needs to continue to bake until it is odorless to avoid delamination of silicone and hot melt adhesive.
Transfer operation
Use a heat press machine to reverse the film to the surface of the carrier such as cloth, the pressing temperature is 150℃, and the pressing time is 6-8 seconds (some processes require 30 seconds, which needs to be adjusted according to the specific glue).
Note: The hot melt glue must be printed on the silicone in a wet state, otherwise stratification will occur; when the weather is hot, some delay agent can be added appropriately.
Differences between positive transfer and reverse transfer processes
Positive transfer: first print hot melt glue, then print coating glue, and finally print silicone layer, which is suitable for products that require glossy surface or special effects.
Reverse transfer: first print silicone layer, then print coating glue, and finally print hot melt glue, which is suitable for products that require matte or double-layer effects.