With the arrival of cold air, it is already winter in many areas, and the viscosity of adhesives will increase and the curing speed will slow down in cold weather. If you do not understand the relevant changes and adjust the process in time, customers are easy to use anomalies, and even cause quality accidents. In the low temperature environment, how to better play the use of glue effect?
Precautions and suggestions for using glue in Winter
With the arrival of cold air, it is already winter in many areas, and the viscosity of adhesives will increase and the curing speed will slow down in cold weather. If you do not understand the relevant changes and adjust the process in time, customers are easy to use anomalies, and even cause quality accidents. In the low temperature environment, how to better play the use of glue effect?
01-One-component room temperature cured organic silicone
Common phenomenon：
①The curing speed is slow at low temperature, and the dry and cold environment may lead to no curing for several days；
②In winter, the temperature decreases and the bonding strength is affected under the same curing time；
③In autumn and winter, glue that is thinner and dries quickly occasionally wrinkles；
④The surface of the transparent glue is foggy or matte.
Measures：
①Increase the temperature and humidity of the adhesive curing environment, such as using air conditioners, humidifiers, etc., pay attention to the influence of humidity.
②Extend the curing time or increase the temperature to solve the problem. At low temperatures, the surface activity of the substrate decreases, and the bonding process requires the glue and the substrate to adsorb each other to form a bonding relay. The glue can be reheated or preheated after baking, but pay attention to avoid excessive temperature to shorten the operation time.
③Due to the low humidity and temperature drop, the surface layer of the glue dries faster, while the inner layer solidifies slowly, resulting in a tension difference between the inner and outer layers, which is easy to lead to the uneven surface of the final film formation, and may wrinkle. It is recommended to apply glue in a constant temperature (about 25 ° C) and high humidity environment, and avoid shaking or wind blowing. Can be covered to reduce the impact of air flow.
④Extend the rest time after applying glue, and ensure that the curing environment is free of dust.
02-Two component organic silicone
Common phenomenon：
①The lower the temperature, the viscosity of the adhesive increases and the mixing becomes difficult;
②The lower the temperature, the slower the curing speed.
Measures：
①Raise ambient temperature
②Increase the mixing time and intensity；
03-Thermal grease/thermal gel
Common phenomenon：
①As the temperature decreases, the adhesive will thicken, making dispensing or screen printing more difficult
Measures：
①Air conditioning constant temperature workshop operation, control the ambient temperature；
②Increase the dispensing pressure, choose a larger dispensing needle, slow down the dispensing speed, adjust the screen printing parameters.
04-UV shadowless glue
Common phenomenon：
①As the viscosity of adhesive increases, the dispensing parameters should be adjusted；
②In winter, the film becomes hard and brittle;
③The substrate temperature is low, the bonding strength is reduced, and the parts fall off.
Measures：
①In the constant temperature workshop, adjust the preset temperature appropriately, even if the same temperature is set, the actual workshop temperature in winter and summer will be different;
②The substrate is first warmed in an environment above 25℃ for more than 3 hours, and the temperature return speed of different materials will be different; Substrate in 50 ~ 60℃ oven baking for half an hour better effect; The material should be kept warm and used as soon as possible;
③Apply adhesive between the two substrates as close as possible; Some applications can appropriately increase the dispensing amount;
④Flexible products, handle gently after applying glue to avoid falling or bending.
05-Thermosetting adhesive
Common phenomenon：
①The adhesive force of the product decreases in winter
②The viscosity of the glue will become thick, difficult to glue
Measures：
①Since the temperature of the bonded plate and lens will become lower in winter, the heat absorption of the glue in the middle will become less, and it is recommended that the temperature can be appropriately increased to increase the heat absorption of the glue when used.
②If the ink on the plate is not fully effective curing, the possibility of volatilization in winter will change more, which will reduce the adhesion of the plate, it is recommended to increase the temperature and extend the time for bonding curing.
③As the temperature decreases, the viscosity of the glue will thicken. It is recommended to increase the air pressure and dispensing temperature during the dispensing process.
06-PUR hot melt adhesive
Common phenomenon：
①When the temperature is lower, the opening time will be shortened, and the wettability of the substrate will be poorer, affecting the adhesion；
②When the dispensing amount is small and the base material is a metal with better heat dissipation, the adhesive force is prone to decline or even non-adhesive phenomenon；
③In winter, when the ambient humidity is low, the curing of PUR hot melt adhesive is slow.
Measures：
①Shorten the operation time as much as possible, quickly fit and maintain pressure after dispensing, avoid cold wind blowing into the colloid；
②Increase the melt temperature by about 10 ° C. Set the melt temperature according to TDS recommendations and actual operations.
③ Control the use of ambient temperature above 20℃, or preheat the substrate at about 30℃;
④ The length of the dispensing needle tip exposed to the outside of the heating sleeve should not exceed 3mm;
⑤ Use a humidifier to increase the ambient humidity.
07-Epoxy resin potting adhesive
Common phenomenon:
①The lower the temperature, the higher the viscosity of the glue, which will lead to the difficulty of mixing or dispensing the adhesive;
②The lower the temperature, the slower the curing speed, some 24 hours can not reach the hardness and bonding strength;
③A well-cured adhesive may be harder and more brittle than at higher temperatures;
④Part of the epoxy resin glue will crystallize under certain conditions, and it will change from a fluid dynamic to a solidified state, which looks like it is cured.
Measures：
①Appropriately increase the mixing time and intensity;
②Preheat properly before use. For example, low temperature oven baking, hot blower blowing, pre-soaking in warm water at 30 ~ 40℃ and other methods. However, the preheating temperature can not be too high to prevent the reaction after mixing, thus affecting the appearance and bonding strength. It is ideal when the material temperature can be preheated to about 25℃;
③Appropriately increase the ambient temperature of curing after mixing, such as opening air conditioning;
④The adhesive that crystallizes can be baked in an environment of about 50℃-70℃, and can be used normally after the appearance returns to its original state.
08-Instant glue
Common phenomenon：
①The curing speed slows down;
②Some quick-drying glue bleaching can become more severe.
Measures：
①The curing speed is slow, mainly related to the low humidity in the environment, or the substrate is acidic, and the accelerator can be used to clean the surface of the substrate;
②Increased ambient temperature (optimal temperature 25∽30℃); Strengthen ventilation; Do not rush into the next process before the glue cures;
③Control the dispensing amount, try not to overflow; If there is overflow, the accelerator can be dropped to accelerate curing;
④Choose a quick-drying glue with low bleaching.
09-Anaerobic adhesive
Common phenomenon：
①The viscosity increases, affecting the dispensing parameters；
②The curing speed is slow, the initial solidification time and the complete curing time are extended;
③Too low temperature leads to incomplete curing, resulting in decreased bond strength.
Measures：
①Adjust dispensing parameters；
②In the constant temperature workshop construction operation, or after dispensing into the warm environment of the constant temperature room；
③Use accelerators or extend the curing wait time；
④The adhesive and the substrate are used in a warm environment such as an air-conditioned room in advance. It is not recommended to directly heat the adhesive itself to avoid deterioration or solidification of the adhesive due to excessive temperature.