Analysis of common problems and solutions for UV (photocuring) adhesives
Published time:
2021-07-21
1. What are the differences between UV glue and other glues? UV glue initially cures in 1-5 seconds under ultraviolet light, and bonding is completed in 20-30 seconds. After irradiation, it reaches a high strength, meeting the needs of automated production lines; the second-generation acrylic structural adhesive initially cures in 1-10 seconds, but takes 24 hours to reach its maximum strength; room temperature curing epoxy structural adhesive initially cures in 10-120 minutes, and takes 7 hours to reach its maximum strength. 2. Is UV glue toxic? Why does using UV glue cause skin redness and itching? UV glue is a green, environmentally friendly, and economical chemical product. It does not contain any organic solvents and has 100% solid content. It is...
1. What are the differences between UV glue and other adhesives?
UV glue initially cures in 1-5 seconds under UV irradiation and bonding is completed in 20-30 seconds. It reaches high strength after irradiation, meeting the needs of automated production lines.
Second-generation acrylic structural adhesives initially cure in 1-10 seconds, reaching maximum strength in 24 hours; room temperature curing epoxy structural adhesives initially cure in 10-120 minutes, reaching maximum strength in 7 hours.
2. Is UV glue toxic? Why does using UV glue cause skin redness and itching?
UV glue is a green, environmentally friendly, and economical chemical product. It contains no organic solvents and is 100% solid content glue. It does not pose any toxic, carcinogenic, or pathogenic risks to the human body.
The main components of UV glue are oligomers of the acrylate series and some monomers of the acrylate series. Acrylate monomers have a certain volatility and some skin irritation. Upon initial contact, if not properly protected, direct contact or prolonged exposure to high concentrations can cause skin allergies, such as eye redness, rashes, and itching. However, after a period of adaptation, allergies and rashes will no longer occur.
Measures:
1. Maintain good ventilation.
2. Operators must wear protective clothing, glasses, masks, gloves, or finger cots.
3. Pay attention to frequent hand washing and changing clothes and gloves.
4. If the glue comes into contact with the skin or any other part of the body, immediately rinse with plenty of water and then wash with soapy water.
5. For operators with weaker body resistance, when using the glue for the first time, please take anti-allergic drugs such as Chlorphenamine, Pheniramine, Cetirizine, or Loratadine (generally available at pharmacies) for about two weeks. For those who have already developed allergies, in the early stages of allergy, avoid scratching to prevent infection of other parts of the body. First, take some anti-allergic medicine or get an anti-allergic injection; the allergic symptoms will usually disappear quickly. Please do not panic.
6. People with allergic skin or particularly poor resistance are advised to change jobs and not operate or use UV glue.
3. Why is the UV glue still not dry and sticky to the touch after being exposed to UV light for a long time?
After the glue cures, the surface of the glue contacts the air. Due to the inhibitory effect of the air, the surface of the glue cannot detach, resulting in a sticky phenomenon.
Solutions to this problem include:
1. Use higher UV intensity.
2. Use a higher photosensitizer dosage.
3. Use a faster reacting photosensitizer system.
4. Use a UV light source containing a 265nm wavelength.
4. Why does UV glue turn white after curing?
This phenomenon often occurs in the glass industry. The whitening phenomenon is actually tiny air bubbles produced in the glue layer itself. Because the glue shrinks during the curing process, if the glue layer thickness is uneven or the hardness is too high, the internal stress generated by the shrinkage cannot be released, and tiny air bubbles will appear over time, which is the whitening phenomenon we see, until the bonded material directly falls off.
Solutions to this problem include:
1. Choose a flexible formula UV glue.
2. Control the bonded glue layer to be uniform.
3. Use low-power UV lamps for initial curing to slow down the curing speed of the glue, and then use high-power UV equipment for deep curing after positioning, because the curing speed of the glue is too fast, which will increase the shrinkage rate of the glue.
5. Is it better to apply more glue when bonding with UV glue?
When bonding with UV glue, more glue is not always better. Experiments show that the thinner the glue layer, the higher the strength. Generally speaking, a glue film thickness of no more than 0.2 microns is best.
6. Does the curing speed of UV glue have a relationship with the quality of the glue?
The curing speed, especially the positioning speed of UV glue, has always been a data of concern to consumers.
Measuring the quality of UV glue is multifaceted: positioning time, curing depth, strength, and film flexibility are all aspects of assessing the quality of UV glue.
We believe that the faster the positioning speed, the greater the internal stress generated during the curing of the glue. This may lead to the detachment of the workpiece. Generally, the positioning speed should be 6 to 10 seconds.
Therefore, it is incorrect to judge the quality of the glue solely based on the curing speed. Instead, its subsequent weather resistance should be determined.
7. Does lower viscosity of UV glue mean lower strength?
The viscosity and strength of UV glue are not directly related. It is a misconception to equate viscosity with strength.
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