About-Q&A
- What is the process flow for adhesive repairing? a. The process of adhesive repairing with water-based PU adhesives is identical to the method of adhesive repairing with solvent-based products.
b. Use solvent-based adhesive together with a “hardener” for adhesive repairing.
- Can water-based PU adhesives be used on light colored/white colored shoes? Since the water-based PU adhesive is resistant to yellowing, usage on light colored or white colored shoes is not a problem.
- Can the water-based PU adhesive be used on hard materials? Under the correct conditions, it is able to satisfy the requirements of shoe manufacturers using materials such as hard nylon, hard TPU, etc.
- Can the hardener for water-based PU adhesive be omitted? No! The hardener increases the initial bonding strength of the adhesive and improves its heat resistance, degradation resistance, and water decomposition resistance performance. During formation and sole processing, the hardener is definitely required.
- Can the water-based PU adhesive and the solvent-based PU adhesive be bonded together? Yes. After drying, the composition properties of water-based PU adhesives are identical to that of solvent-based adhesives. Therefore, there is no problem bonding the two adhesives together.
- Does your company have color water-based paste for the water-based PU adhesive to suit the color of the shoes? GRECO has developed water-based color pastes that can be mixed with water-based PU adhesives.
- What adhesive brushes are suitable for applying water-based PU adhesive? Either use a toothbrush or paintbrush when applying the adhesive.
- How long before the brush needs to be replaced? To avoid uneven application, the adhesive brush should be replaced once every 1 – 2 hours. It is suggested to use different color brushes to prevent confusion.
- How long is the usage time of ”POT LIFE” water-based PU adhesive? a. After the addition of the hardener, water-based PU adhesives can be used for 3~4 hours. Its usage time is longer than that of solvent-based PU adhesives.
b. After mixing the adhesive, it is suggested to finish using it within two hours. Because if the placement time without use is too long, its properties are likely to be affected by the environment.
- From its appearance, how can you determine if the water-based PU adhesive is normal or not? If you can observe a separation of the layers or frozen parts in the adhesive, you should contact GRECO’s technicians before handling.
- If skin or eyes are exposed to water-based PU adhesive, what are the treatment procedures? Immediately use water to wash adhesive off the exposed skin area. If your eyes are exposed to the water-based PU adhesive, do not rub your eyes with your hands. Use an eye cleaner with water to rinse your eyes for 10 – 15 minutes, followed by medical treatment. (Please refer to details in the MSDS).
- Is it required to pre-heat the shoe materials before applying the water-based PU adhesive? Pre-heating the shoe materials is helpful to the bonding effect of both solvent-based and water-based adhesives.
- After bonding with the use of water-based PU adhesives, how long is needed before continuing the production process? Depending on the tension, normally, 4 hours after cooling or 24 hours if left at room temperature.
- Does the humidity influence the ration of hardener added to water-based PU adhesives? No. Water-based PU adhesives use water as a solvent, and therefore the humidity won't effect the cross-linking. When hardeners are mixed with water-based PU adhesives, cross-linking is slower than those mixed with solvent-based PU adhesives. Moreover, the cross-linking process continues even when all the water has evaporated.
- During production, what happens if the oven temperature is too low when using water-based adhesive? When the temperature is too low, the drying of the water-based adhesive would be incomplete. An insufficient activation temperature would result in poor bonding.
- If the surface of the water-based PU adhesive forms film, what should be done? The film on the surface of the water-based PU adhesive is because the PU resin’s physical property has been changed. Please remove the film and handle it according to the relevant waste disposal regulations.
- GRECO’s water-based PU adhesive has a shiny blue appearance. Does this affect the adhesives performance? This is caused by the reflection of the light via the PU particle resin, and does not cause yellowing or affect the adhesives performance.
- If the weather temperature is too high, it is likely to produce drawing (silky) strings! How should be done? a. The oven temperature cannot be too high. It shall be controlled at 55~60℃.
b. Mix the water-based PU adhesive uniformly for 10 minutes and add the appropriate amount of hardener (5%).
c. After the water-based PU adhesive is mixed completely, it should be used within 2 hours of mixing completion.
- The drying time of water-based PU adhesive is longer. To avoid influencing the production, can the oven temperature be increased in order to lessen the drying time? Normal drying criteria: Drying for 3~5 minutes under 50~60℃ can dry the adhesive completely. An increase in the oven temperature may have negative effects on the bonding, and the consumption required to increase the thermal energy can also be an environmental pollutant.
- Compared with solvent-based adhesive, why is water-based PU adhesive more likely to form glue clogs on the brush? This is because the solid content of PUD is three times higher than S/B PU. Therefore, it is more likely to form glue clogs on the brush.
- Can water-based PU adhesive be mixed with traditional PU adhesive for use? No. Due to the compatibility issue of the water-based PU adhesive and the solvent-based adhesive, they may separate into layers.
- How long does it take for water-based PU adhesives and hardener to cross-link? 48 hours.
- Can the water used for washing the water-based PU adhesive container be drained directly after cleaning? Since the water contains the PU resin, in principle, it shouldn’t be drained directly (but alum can be used for sedimentation).
- Why are water-based PU adhesives prone to generating glue clogs during the application onto rubber materials? Most of Rubber Primers are acidic, and are likely to cause water-based PU adhesive to form glue clogs on the brush.
