Thermal transfer wood grain process refers to the transfer of wood grain patterns on transfer paper or transfer film and immersion into the sprayed substrate coating on the basis of powder spraying, according to the principle of high temperature thermal sublimation, after heating and pressurizing, to form a realistic wood grain effect. Thermal transfer printing is commonly used in the following two processes:
First, glue transfer: Use glue to paste the front of the transfer paper and the substrate coating, the purpose of using glue is to make the transfer paper close to the substrate coating. The wrapped substrate is sent to the oven to bake, and the length of the baking temperature and time should be adjusted according to the characteristics of the substrate to be transferred, the depth of the texture to be transferred and the specific performance of the oven. Remove the substrate that has been transferred from the oven, tear off the heat transfer paper, and do surface cleaning.
1, advantages: suitable for different specifications of special-shaped parts, simple operation.
2, disadvantages: due to glue reasons, the transferred wood grain pattern will have a little fuzzy or glue printing. Because of zero pressure, the penetration depth of the ink is limited, and the weather resistance of the wood grain product has some impact.
Vacuum film transfer: Wrap the substrate with transfer paper, and fix the interface of the paper with high temperature stickers to prevent the wood grain heat transfer paper from being released. The substrate covered by the transfer paper is then covered with a high-temperature plastic bag, and then vacuumed from both ends of the plastic bag until the plastic bag can fully and effectively adhere to the substrate. The negative pressure of the vacuum should be properly adjusted according to the characteristics of the substrate and the negative pressure that the plastic bag can withstand, usually between 0.3 and 0.6Mpa. The purpose of using plastic bags is to make the plastic bag forced transfer paper that is already close to the substrate fully and effectively stick to the substrate through negative pressure. The base material that has been wrapped is sent to the oven to bake, and the length of the baking temperature and time should be adjusted according to the characteristics of the base material, the depth of the texture to be transferred and the specific performance of the oven. Remove the substrate that has been transferred from the oven, pull off the plastic bag from one end of the substrate, tear off the transfer paper, and do surface cleaning.
1, advantages: Because the transfer paper is directly close to the substrate coating under vacuum negative pressure, there is no intermediate medium, the wood grain products out of the transfer are clear, the color is more smooth, the ink penetration is stronger, and the weather resistance of the wood grain products is effectively improved.
2, disadvantages: not suitable for different specifications of special-shaped parts.
Parameter requirement
1, substrate spray film thickness: 60-80μm.
2, substrate spraying curing temperature and time: 200 degrees, 15 minutes. (Refer to powder coating manufacturer requirements)
3, to achieve the best weather effect transfer temperature and time:
◎ Experimental pressure plate -205 degrees, 200 seconds.
◎ Empty furnace -185 degrees above, more than 25 minutes.
◎ Glue water -210 degrees, 16 minutes. (The parameter requirements of the final transfer should be adjusted according to the thickness and plate type of the substrate, on the basis of the parameters of the ordinary wood grain transfer, the temperature is increased by 5 degrees, and the time is increased by 5 minutes)
Note: Due to the characteristics of weatherproof transfer paper, when vacuuming paper picking, the operator's paper picking technology is also more demanding. ① The transfer paper and the substrate coating must be smooth and close, otherwise it is easy to get chicken foot marks. ② If the substrate has a groove position, the operator must press the transfer paper by hand to make it close to the substrate coating, and there can be no gap between the transfer paper and the coating, otherwise there will be leakage.
