With the upgrading and transformation of industrial products, the demand for hot melt adhesive products is also increasing rapidly. Tianxiang Technology provides users with polyurethane hot melt adhesive products for various specific purposes, and has achieved a good reputation, mainly including high, medium and low viscosity. Products and customized products in different colors. This article introduces some common sense about hot melt adhesive products, and learns and communicates with you.
      1. The glue line is cured in advance
It is often caused by too little glue or improper temperature setting.
Consequences: Unboxing or false bonding
      2. The curing speed is too slow
It is often caused by too much glue, the temperature/pump pressure is adjusted too high, the nozzle diameter is too large, and the pressure of the packaging machine is uneven.
Consequences: unpacking / false bonding / increased cost of glue
      3. The nozzle or hose is blocked
Reason: hot melt adhesive is too sticky; carbide or gel is produced; foreign matter in glue tank, etc.
Solution:
①Increase the temperature or take another low-viscosity hot melt adhesive
②Clean the glue spraying system or lower the temperature and change the glue
③Clean the glue tank and standardize the glue addition
      4. Drop, flow glue
Reasons: The nozzle is dirty and damaged; there are foreign objects and wear in the nozzle valve; the solenoid valve is loosely installed and leaks; the air pressure is unstable and underpressure
Solution:
①Clean the nozzle ②Check or replace ③Reinstallation confirmation ④Reset and check to meet the requirements
      5. Hot melt adhesive splash
Reason: glue pressure is too high; temperature is too high; viscosity is too low; nozzle position is incorrect
Solution:
①Adjust the air pressure of the glue pump of the melter to reduce the pressure;
② lower the temperature;
③ Reduce the temperature and reduce the distance between the spray gun and the object;
④Change the nozzle position
      6. Hot melt adhesive carbonization
Reasons: The temperature of the glue tank is too high; carbonization on the side wall of the glue tank; oxidation of the hot melt adhesive; large temperature control range, out of control
Solution:
① The glue tank is filled with glue, and the glue is added according to the technical documents;
②The upper cover of the plastic tank;
③ overhaul or replacement;
④ Lower the temperature
      7. Hot melt glue
Reason: mixing of two incompatible adhesives; overheating; unstable hot melt adhesive
Solution:
①Clean the glue tank, standardize the glue change, and find a supplier;
② Lower the temperature, clean the glue tank, and find a supplier;
③Clean the glue tank and find a supplier
      8. There are bubbles in the hot melt adhesive
Reason: hot melt adhesive vacuum is not done well; production process and packaging are not matched
Solution: contact the supplier, change the glue
      9. Unstable spray pattern
Reason: the light-sensitive object and control are not adjusted well; the set temperature is not accurate; the nozzle is dirty and damaged
Solution:
① readjust;
② Contact the supplier to set the correct temperature;
③Cleaning, overhauling and replacing
      10. Hot melt adhesive drawing
Reasons: operating temperature is too low; glue temperature in the tank is too low; injection time does not match the speed of the carton; nozzle switch is worn; old glue exceeds the service life in the glue tank
Solution:
①Increase the temperature (note: too high temperature will affect the thermal stability of the glue);
② pre-heating;
③ Adjust the machine;
④ Clean and repair nozzles;
⑤Clean the system and add new hot melt adhesive
      11. The hot melt adhesive cannot flow out evenly from the nozzle (spraying glue)
Causes: Nozzle clogged; Insufficient air pressure in multiple sets of nozzles; Operating temperature too low
Solution:
①Cleaning, overhauling and replacing;
②Check the quality of hot melt adhesive, carbonization, impurities, and glue replacement;
③ Check the air pressure stability of the spray gun, check the nozzles and nozzles;
④Increase the temperature and contact the supplier for correct heating
      12. Hot melt adhesive smokes
Reason: The operating temperature is too high; the temperature control is out of control; the thermal stability of the hot melt adhesive is too poor
Solution:
①Reduce the temperature and find a supplier;
②Replace out-of-control components and find equipment suppliers;
③Standardized replacement of glue, looking for suppliers
      13. Poor bonding
reason:
①The amount of glue is not enough or the operating temperature is low, so that the hot melt adhesive is mainly on one side of the substrate;
②Because the hot melt adhesive is then affected when it is in a semi-molten state, there is glue on both sides of the substrate, but there are many solidified thin "feet";
③ The surface to be bonded is not in contact or the contact is not good, and the surface of the hot melt adhesive is smooth;
④The bonding is easy to be separated. Often it is due to the poor choice of adhesive.
Solution:
①Increase the coating thickness or increase the temperature;
② Check whether the pressing is good, lower the operating temperature, or use an adhesive with a fast curing speed;
③ Adjust the pressure to ensure that the substrate is in good contact during the cooling process of the hot melt adhesive;
      14. Hot melt adhesive does not penetrate well
Reason: The temperature is too low; the glue layer is too thin; the surface of the cardboard is coated (such as wax or oil)
Solution:
①Increase the temperature;
②Increase the temperature and pipeline pressure to increase the amount of glue applied;
③You can try hot melt adhesives with different properties, or treat the surface of the cardboard
      Other precautions for the use of hot melt adhesive
1. Do not overheat the colloid, and do not heat it over 180°C without the permission of the supplier;
2. Do not mix different types of hot melt adhesives;
3. Clean up the environment around the hot melt adhesive machine at any time, and keep it clean and hygienic;
4. When adding hot-melt adhesive or maintaining and cleaning hot-melt adhesive, you should wear gloves and safety mask or glasses, and be careful when adding material, so as to avoid hot-melt adhesive splashing and causing burns to personnel;
5. Add material regularly to maintain the liquid level. If the liquid level is too low, it is easy to cause splashing during feeding, resulting in burns to personnel;
6. Prepare a bucket of cold water next to the hot melt glue machine in case the person is unfortunately scalded and soaked to reduce the injury;
7. Place the hot melt adhesive and its peripheral equipment below the eye level as much as possible;
8. If the position of the hot melt glue machine is too high, a platform should be installed to facilitate the operation of personnel.