Wenzhou Jinjiu Packaging Machinery Co., Ltd. - electronic album

Release date：2022-04-13 The author：Ms.Lin Click:

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, which has achieved a good reputation, mainly including products with high, medium and low viscosity and customized products of different colors. This article introduces some common knowledge about hot melt adhesive products, and we will learn and exchange together.

1. Glue line curing in advance

It is often caused by too little glue or improper temperature setting

Consequence: unpacking or false bonding

2. Curing speed is too slow

It is often caused by too much glue, too high temperature / pump pressure, too large nozzle diameter, uneven pressure of packaging machine and so on.

Consequence: the cost of unpacking / false bonding / glue use increases

3. Nozzle or hose blocked

Cause: the hot melt adhesive is too sticky; Producing carbides or gels; There are foreign matters in the rubber cylinder

resolvent:

① Raise the temperature or adopt low viscosity hot melt adhesive

② Clean the glue spraying system or reduce the temperature and change the glue

③ Clean the glue cylinder and add glue in a standardized way

4. Dripping and flowing glue

Cause: the nozzle is dirty and damaged; There are foreign matters and wear in the nozzle valve; Loose installation and air leakage of solenoid valve; Unstable air pressure and undervoltage

resolvent:

① Cleaning nozzle ② maintenance or replacement ③ reinstallation confirmation ④ resetting and inspection meet the requirements

5. Hot melt adhesive splash

Cause: the glue pressure is too high; The temperature is too high; Viscosity is too low; Incorrect nozzle position

resolvent:

① Adjust the air pressure of the rubber pump of the rubber machine to reduce the pressure;

② Reduce the temperature;

③ Reduce the temperature and reduce the distance between the spray gun and the object;

④ Change nozzle position

6. Carbonization of hot melt adhesive

Cause: the temperature of rubber cylinder is too high; Carbonization on the side wall of the rubber cylinder; Hot melt adhesive oxidation; Large temperature control range and out of control

resolvent:

① Fill up the rubber in the rubber cylinder according to the technical documents;

② Upper cover of rubber cylinder;

③ Maintenance or replacement;

④ Lower the temperature

7. Hot melt gel

Reason: two immiscible adhesives are mixed; overheated; Unstable hot melt adhesive

resolvent:

① Clean the rubber cylinder, change the rubber in a standardized way and find suppliers;

② Reduce the temperature, clean the rubber cylinder and find suppliers;

③ Clean the rubber cylinder and find the supplier

8. Bubbles in hot melt adhesive

Cause: the vacuum of hot melt adhesive is not well prepared; The production process does not match the packaging

Solution: contact the supplier and change the glue

9. Unstable spray pattern

Cause: light sensing object and control are not well adjusted; The set temperature is inaccurate; Dirty and damaged nozzle

resolvent:

① Readjustment;

② Contact the supplier to set the correct temperature;

③ Cleaning, overhaul and replacement

10. Hot melt adhesive drawing

Cause: the operating temperature is too low; The glue temperature in the tank is too low; The spraying time does not match the speed of the carton; Nozzle switch is worn; Old glue exceeds the service life in the glue tank

resolvent:

① Increase the temperature (Note: too high temperature will affect the thermal stability of the glue);

② Pre heating;

③ Machine adjustment;

④ Clean and repair the nozzle;

⑤ Clean the system and add new hot melt adhesive

11. Hot melt adhesive cannot flow out evenly from the nozzle (glue spraying)

Cause: nozzle blockage; Insufficient air pressure in multiple groups of nozzles; Operating temperature too low

resolvent:

① Cleaning, overhaul and replacement;

② Check the quality of hot melt adhesive, carbonization, impurities and glue change;

③ Check the air pressure stability of the spray gun, and check the nozzle and nozzle;

④ Raise the temperature and contact the supplier for correct heating

12. Smoke from hot melt adhesive

Cause: the operating temperature is too high; Temperature control out of control; The thermal stability of hot melt adhesive is too poor

resolvent:

① Reduce the temperature and find suppliers;

② Replace out of control components and find the equipment supplier;

③ Standardize glue change and find suppliers

13. Poor adhesion

reason:

① The hot melt adhesive is mainly on one side of the substrate due to insufficient glue amount or low operating temperature;

② Because the hot melt adhesive is then affected in the semi molten state, there is adhesive on both sides of the substrate, but there are many cured fine "feet";

③ The bonded surface is not in contact or not in good contact, and the hot melt adhesive surface is smooth;

④ Bonding is easy to be separated. It is usually due to improper selection of adhesive.

resolvent:

① Increase coating thickness or temperature;

② Check whether the pressure is good, reduce the operating temperature, or use the adhesive with fast curing speed;

③ Adjust the pressure to ensure good contact with the substrate during the cooling process of hot melt adhesive;

14. Poor penetration of hot melt adhesive

Reason: the temperature is too low; The adhesive layer is too thin; Paperboard surface is coated (e.g. wax or oil)

resolvent:

① Raise the temperature;

② Increase the temperature and pipeline pressure, and increase the amount of glue;

③ Hot melt adhesives with different properties can be used, or the surface of paperboard can be treated

Other precautions for the use of hot melt adhesive

1. Do not overtemperature the colloid, and do not heat it more than 180 ℃ without the permission of the supplier;

2. Do not mix different kinds of hot melt adhesives;

3. Clean the environment around the hot melt adhesive machine at any time and keep it unblocked and hygienic;

4. Wear gloves and safety mask or glasses when adding hot melt adhesive or maintaining and cleaning hot melt adhesive. Be careful when adding hot melt adhesive to avoid splashing hot melt adhesive and scalding personnel;

5. Feed regularly to maintain the liquid level. If the liquid level is too low, it is easy to splash during feeding, resulting in personnel scalding;

6. Prepare a bucket of cold water next to the hot melt glue machine for soaking in case of personnel scalding, so as to reduce the injury;

7. Place the hot melt adhesive and its peripheral equipment below the eye level as far as possible;

8. If the position of the hot melt adhesive machine is too high, a platform shall be installed to facilitate personnel operation.