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Solutions to common problems in the use of water based PU adhesives

1. Training for factory management personnel?
First, on-site management personnel were trained in the concept of water-based glue. Secondly, pay attention to: training on drying conditions, brushing specifications, fit and quality inspection standards.

2. How to solve the problem of degumming when using water based PU adhesives?
(1) Observation and analysis of the area where the degumming occurred, whether the material does not adhere to the surface due to the poor treatment of the surface treatment agent. If the adhesive film is peeled off due to the poor surface treatment agent, it is recommended to replace the surface treatment agent.
(2) If there is glue on both sides but there is stringing, it is usually caused by too thick glue or poor drying.
(3) For more complicated technical problems, the technician of the glue supplier should be consulted in time to request technical support.

3. How to make up the glue when small area degumming occurs?
The method of replenishing is the same as the method of replenishing oily glue. Because water-based PU glue dries slowly and is easy to build up, it is generally not recommended to use water-based PU glue as the replenishing solution. You can choose ordinary oily glue and hardener as the replenishment. Together.

4. How to use water-based PU glue to strengthen it?
(1) Due to the insufficient wetting effect of water-based PU adhesive on some materials, a reinforcing process is usually used to strengthen the adhesion of the adhesive film.
(2) Reinforcing agents usually use oily low-viscosity, high-penetration PU products, which can achieve good reinforcement effects.
(3) Reinforcing agent is generally used before brushing the water-based PU adhesive after finishing the treatment agent. Each process must be dried before the next process can be performed.

5. How to clean up the coating of water-based PU adhesive that is too high or over the line?
(1) When it is too high, wipe it off in time, it is very easy to handle, and when it is difficult to clean up individual materials, it can be wiped clean with an engraving machine or raw film.
(2) The upper of the shoe can be cleaned in the same way. It is not recommended to use organic solvents to clean the glue line, as it is very easy to cause the glue to break open.

6. What should I do after accidentally contacting water-based PU glue with eyes or other parts of the body?
(1) After splashing water-based PU glue into the eyes, please rinse with water immediately. If you still have any discomfort, please seek medical treatment in time, but it will not cause significant damage to the eyes.
(2) No mucous membrane injury caused by skin contact
(3) There is basically no inhalation hazard, and it will not cause harm to the human respiratory system and nerve center.
(4) There is no case of occupational hazards in a single long-term exposure.

7. How to judge visually that the water-based PU adhesive has failed?
(1) Water-based PU glue is a milky white viscous liquid under normal conditions, with uniform colloid viscosity and homogeneous dispersion.
(2) If the top is thin and the bottom is thick, or obvious delamination and other phenomena are surface demulsification, that is, storage has failed.
(3) Glue that has failed storage needs to be re-tested to determine whether it can be used.

8. Do I need to change the equipment to apply water-based PU adhesive?
No, existing equipment is sufficient.
The joint can increase the instant activation lamp.

9. What adjustments need to be made to the production line for the application of water-based PU adhesive?
(1) Flow rate: Slowly reduce the line speed, usually the drying time of water-based PU glue is 4-5 minutes.
(2) Temperature: Increase the temperature appropriately, about 5 degrees higher than the original standard.

10. What adjustments do the presses need to make?
The pressure of the original press is adjusted to more than 40 kilograms to ensure uniform pressure at each point of force. The pressing time is adjusted to 8-10 seconds to ensure sufficient pressing time.

11. Why is the pressure and pressing time higher than the oily glue?
Because the initial crystallization of water-based PU adhesive is slow, its initial adhesion will be slightly weaker than that of oil-based adhesive. In order to improve this weak point and avoid poor adhesion at the tension position, it is necessary to increase the pressure and increase the pressing time.

12. Why can't the quality inspector in the back section buckle the fitting surface of the shoes vigorously?
Because the initial strength of water-based PU adhesive is slightly weaker and the reaction speed with the hardener is slow, the just-adhesive rubber surface is less resistant to external force damage. It is recommended to just place the fitted shoes for a while to check the quality, and avoid pressing the shoe upper immediately.

13. Do I need to change the inspection standard when using water-based PU adhesive?
There is no need to change the original inspection standards, but it is necessary to pay attention to the small differences between water-based PU glue inspection and oil-based glue inspection.

14. What matters should be noticed when using water-based PU glue for quality inspection?
(1) It is recommended to check the quality of shoes just after being fitted * 30 minutes later, or wait until the shoe body is completely frozen and then check. (2) Large external forces are still easy to peel off the initial bonding surface, so the inspection method must be controlled, but the inspection standard is not reduced.
(3) After 12 hours, the adhesive strength of water-based PU adhesive has basically recovered, and the tensile value is equivalent to that of oily adhesive, but the tensile value after 48 hours is usually 10% higher than that of oily adhesive.