Detailed answers to common problems and solutions of two-component sealing adhesive

Two component silicone sealantCrosslinking occurs through over addition reactions and solidifies into high-performance elastomers. It consists of two liquid parts, A and B. Group A is black or white, while component B is white. When the two components are fully mixed by weight, the mixed liquid will solidify into a soft elastic material. It can be cured at room temperature or accelerated at temperatures below 80 ℃, with no significant shrinkage or temperature rise during curing. However, there are many aspects that need to be paid attention to during the operation, otherwise it will cause various problems with the cured sealant. Today, the advanced technology editor of the two-component sealant manufacturer has compiled the common problems and solutions of two-component sealant in daily use.

How to avoid the generation of bubbles?

1. It is recommended to use products with low viscosity and long operating time, which can eliminate air before the material solidifies.

2. Keep the curing temperature below 45 ℃ to avoid excessive temperature that may prevent the pores from being expelled.

How to determine the ratio?

Firstly, check the configuration and usage requirements in the product manual. Generally speaking, the dosage of curing agent and changes in environmental temperature and humidity have a significant impact on the curing speed. An increase in the amount of curing agent will accelerate the curing reaction. Therefore, the curing speed can usually be adjusted by increasing or decreasing the dosage of curing agent, and the recommended dosage is generally between 10:0.8-10:1.2 (mass ratio). If it is necessary to change the ratio, a simple experiment should be conducted on changing the mixing ratio before application.

How to remove residual cured silicone gel?

Before the two-component thermal conductive sealing adhesive is cured, a sharp knife (or clean cotton cloth) can be used to scrape off the uncured gel, and then the remaining material can be cleaned with solvents such as isopropanol. After the adhesive is cured, it can be scraped off as much silicone as possible with a small knife, and then various residues can be removed using solvents (120 # solvent oil, alcohol, xylene, acetone, etc.), soaked and decomposed.

What should I do if the main agent settles

If the two-component epoxy resin sealant is left for too long (more than half a month), the filler may settle. For example, if component A is separated into separate buckets, there may be a layer of colorless transparent silicone oil on the surface. If not stirred evenly, the surface color may be grayish, the operation time may be too long, the surface may become sticky, the cured product color may be grayish, and the cured product may be brittle. So before use, it is necessary to stir component A, especially up and down, thoroughly mixing.

Why does simultaneous gluing result in some curing and others not curing

Uneven mixing of two-component epoxy sealant can cause slow or incomplete local curing. For example, the curing time of the glue mixed in the same batch is not consistent, some cure quickly, while others take a long time to cure; After curing, there are grooves on the surface of the adhesive, and the adhesive inside the grooves does not cure; The phenomenon of complete non solidification appears locally. It is necessary to strengthen the stirring, with a stirring time of about 2-5 minutes, to ensure that the glue is completely mixed evenly. When using stirring, attention should be paid to whether the stirring can drive all the glue materials.

Common problems in using two-component sealing adhesive dispensing machine

1. The component A must be stirred evenly before being injected into the dispensing machine component bucket.

2. After a problem occurs, customers can be requested to manually apply glue according to the operating procedures. If the glue can cure normally, then check if there are any abnormalities in the dispensing machine or matching.

3. When dispensing with the machine, check whether the dispensing ratio of the two rubber hoses is accurate and whether there is sediment blocking the valve in the curing agent tank. Clean the curing agent tank and conduit; Regularly replace the desiccant in the curing agent vent valve.

4. Pay attention to whether the vent valve is open during gluing to avoid affecting the dispensing pressure.

5. Newer dispensing machines come with their own cleaning system, so it is important to ensure that the cleaning agent is thoroughly cleaned during dispensing.

Precautions for using two-component condensation sealant

1. The main agent should be stirred evenly before use.

2. Before the adhesive is cured, it should not come into contact with rainwater, solvents, etc.

3. If a matte effect is required, the module must be placed in a well ventilated environment.

4. Before using the same container for glue dispensing, the residue inside the container must be cleaned thoroughly, and any unused materials must be resealed.

5. When it is necessary to attach to a certain material (such as PC, PCB, etc.), it must be used after conducting application experiments in advance. Depending on the situation at that time, sometimes the material may need to be cleaned.

6. In most cases, silicone rubber can be used normally between minus 40 and 200 degrees Celsius, but under higher or lower temperature conditions, in addition to higher requirements for adhesion or sealing materials, the curing performance of the adhesive itself also changes and needs to be fully tested before use.