1. The B component has the phenomenon of particle agglomeration and pulverization

If component B has particles agglomerated and pulverized, there are two reasons: one is that the upper layer has already appeared before use. This is because the packaging and sealing is not good, and the crosslinking agent or coupling agent in component B is all It is an active compound that is easy to react with moisture in the air, and the batch should be returned to the manufacturer. The second is to stop the machine during use, and the phenomenon of particle agglomeration and pulverization occurs when the machine is turned on again, indicating that the pressure plate of the glue spreader and the rubber material are not well sealed, and the equipment should be contacted to solve the problem.

2. The glue output speed of the glue machine is slow

When the product is used for the first time, the glue output speed of the glue machine is too slow. There are three possible reasons: (1) The fluidity of component A is poor, (2) the pressure plate is too large, and the gas source pressure is not enough. When it is determined to be the cause (1) or cause (3), we can solve it by adjusting the pressure of the glue gun; when it is determined to be the cause (2), ordering barrels with matching calibers can solve the problem. If the glue output speed slows down during normal use, it may be that the mixing core and filter are blocked. Once found, the equipment needs to be cleaned in time.

3. The breaking time is too fast or too slow

The breaking time of structural adhesive refers to the time for the colloid to change from paste to elastomer after mixing, and it is generally tested every 5 minutes. There are three factors that affect the dry curing of the rubber sheet: (1) The influence of the ratio of A and B components, etc.; (2) Temperature and humidity (the influence of temperature is the main one); (3) The formula of the product itself is defective.

The solution for reason ⑴ is to adjust the ratio. Increasing the proportion of component B can shorten the curing time and make the adhesive layer harder and brittle; while reducing the curing agent ratio will prolong the curing time, the adhesive layer will become softer, and the toughness will increase and the strength will be increased. reduce. Generally, the volume ratio of A:B component can be adjusted between (9～13:1). The higher the ratio of B component, the faster the reaction speed and the short breaking time. If the reaction is too fast, it will affect the time of trimming and stopping the gun. Too slow will affect the total drying time of the colloid. The breaking time is generally adjusted between 20 and 60 minutes. The performance of the colloid after curing in this ratio range is basically the same. In addition, when the construction temperature is too high or too low, we can appropriately reduce or increase the proportion of component B (curing agent), so as to achieve the purpose of adjusting the surface drying and curing time of the colloid. If the problem is with the product itself, the product needs to be replaced.

4. "Flower glue" appears in the glueing process

Flower gum is produced due to the uneven mixing of the A/B component colloids, and it appears as partial white streaks. The main reasons are: (1) The pipeline of component B of the glue dispenser is blocked; (2) The static mixer has not been cleaned for a long time; (3) The scale is loose and the glue output speed is uneven; (4) The equipment process parameters are not adjusted by changing the manufacturer or the brand; for the reasons (1), (2), It can be solved by cleaning the equipment; for the reason (3), you need to check the proportional controller and make appropriate adjustments.

5. Skinning or vulcanization of the colloid occurs during the glueing process

When the two-component glue is partially cured during the mixing process, the glue shot by the glue gun will appear skinning or vulcanization. When there is no abnormality in the curing and glue output speed, but the glue is still crusted or vulcanized, it may be that the equipment has been down for a long time, the glue gun has not been cleaned or the gun has not been washed thoroughly, and the skin or vulcanized glue needs to be rinsed Construction after cleaning.

6. Air bubbles are trapped in the glue

Generally speaking, the colloid itself has no air bubbles. The air bubbles contained in the colloid are most likely to be mixed with air during transportation or construction, such as: ⑴ Exhaust gas is not cleaned when replacing the rubber bucket; ⑵ The components are pressed after the machine is on the machine. Not pressed down, resulting in incomplete evacuation. Therefore, drain the bubbles thoroughly before use, and operate the glue dispenser correctly during use to ensure a seal to prevent air from entering. If it is suspected that the product itself contains bubbles, it can be judged by the butterfly test.

7. Poor adhesion to the substrate

Sealant is not a universal glue, so it cannot guarantee good adhesion to all substrates in practical applications. With the diversification of substrate surface treatment methods and new processes, the bonding speed and bonding effect of sealants and substrates are also different.

There are three forms of failure of the bonding interface between the structural adhesive and the substrate. One is cohesive failure, that is, adhesion and cohesion; the other is adhesion failure, that is, adhesion and cohesion. The third is both failure modes. If the bond failure area is less than or equal to 20%, it is qualified, and if the bond failure area exceeds 20%, it is unqualified; when the bond failure area exceeds 20%, it is an undesirable phenomenon in practical applications. There may be six reasons why the structural adhesive does not stick to the substrate:

⑴ The substrate itself is difficult to bond, such as PP and PE. Due to their high molecular crystallinity and low surface tension, they cannot form molecular chain diffusion and entanglement with most substances, so they cannot form a strong interface at the interface. Adhesion;

⑵The product has a narrow bonding range and can only work on part of the substrate;

⑶ The maintenance time is not enough. Normally, after the two-component structural glue is used, it should be cured for at least 3 days, while the single-component should be cured for 7 days. If the temperature and humidity of the curing environment are low, the curing time needs to be extended.

⑷The ratio of A and B components is wrong. When using a two-component product, the user must mix the ratio of base gum and curing agent in strict accordance with the ratio required by the manufacturer, otherwise there may be problems in the early curing, or the adhesion, weather resistance and durability in the later stage of use. problem;

⑸ The substrate is not cleaned as required. Because the dust, dirt and impurities on the surface of the substrate will hinder the bonding, it must be strictly cleaned before use to ensure that the structural adhesive is well bonded to the substrate.

⑹The primer is not applied as required. The use of primer on the surface of aluminum profiles for pretreatment can shorten the bonding time while improving the water resistance and durability of the bonding. Therefore, in actual engineering applications, we must use the primer correctly and strictly avoid degumming caused by improper use.

8. Incompatible with accessories

The reason for the incompatibility with the accessories is that the sealant has a physical or chemical reaction with the accessories in contact, which causes the hazards such as discoloration of the structural adhesive, non-stick to the substrate, decreased performance of the structural adhesive, and shortened life of the structural adhesive.

Summary: Silicone structural adhesive has excellent properties such as high strength, high stability, excellent aging resistance, high temperature resistance, etc., and is widely used in the structural bonding of building curtain walls. The compatibility test and adhesion test of the glass, aluminum and accessories should be checked before the construction of the silicone structural adhesive. The construction process should be carried out in strict accordance with the requirements of each link, so as to achieve the effect of the structural adhesive and ensure the quality of the project.