How To Check Whether Silicone Sealant Is Qualified?

Silicone sealant is a material with certain chemical activity. Silicone sealants on the market can be divided into one-component silicone sealants and two-component silicone sealants according to the group fraction.

The curing principle of single component silicone sealant is: absorb water molecules in the air, from the surface to the inside step by step cross-linking reaction, thereby curing to form rubber elastomer.The curing principle of the two-component silicone sealant is: After the A component (the main agent) and the B component (the catalyst) are mixed, the surface and the interior simultaneously cross-linked curing to form a rubber elastomer.Therefore, silicone sealant must be checked correctly and strictly before construction, and the following work needs to be done:

1. Confirm storage conditions and check product expiration date

Silicone sealant needs to be stored according to product requirements, and used in accordance with the specified construction process requirements during the shelf life, so that silicone sealant can play the best performance in the application. The nominal storage period of silicone sealant products is based on the provisions of relevant national standards or industry standards. Silicone sealant should be stored in a cool, dry and ventilated environment. Although in most places in the country, winter temperatures are unlikely to exceed 27 ° C, it is still necessary to avoid open storage.

Before starting, confirm the storage of the sealant, check whether the sealant is indoors, and if the project site does not have the conditions, whether it is fully protected from rain, snow, sun and other protective measures. Improper storage, expired, close to the shelf life of the product may be slow to cure or even unable to cure, part of the construction performance and product appearance will also be affected, such as thickening resulting in reduced extrudability, crust, etc.

2. Tool check

If you want to do something good, you must first improve the machine, silicone sealant construction process glue tool is one of the most important tools, glue gun intact, glue can be more smooth, more full glue.

At the same time, for the two-component structural glue used in the glue machine needs more strict inspection, before the glue injection of the equipment for comprehensive maintenance, such as pipe cleaning and cleaning, scale correction, pressure control, etc., to ensure the stable operation of the equipment, to prevent leakage, uneven mixing and the production of bubble glue.

3. Inspection appearance (single component)

For the single component sealant should first confirm its appearance, through the rubber strip or scraper visually observe whether the silicone sealant is fine, uniform without stratification, no crust, no bubbles.

4. Surface dry, anti-stick and elastic testing (single component)

Check the surface drying time, desticking time and elasticity of the one-component silicone sealant to confirm that the sealant can cure normally and has good elasticity.

1) Surface drying time:

On the film (the entry "film" provided by the industry encyclopedia) paper with a diameter of about 6mm silicone sealant; Every few minutes, gently touch the adhesive surface with clean hands; The time when the hand will not glue is called the surface drying time, under standard conditions (temperature 23±2℃, relative humidity 50±5%), the surface drying time is less than 3h. If the temperature is low or the humidity is out of range, the time will be extended. Field tests will ultimately confirm that the sealant can dry.

2) Viscosity removal time:

After 24 hours of curing, touch the rubber strip with your palm to check whether it is sticky. The time when the adhesive surface is not sticky as a whole is called the desticking time. Under the standard conditions (temperature 23±2℃, relative humidity 50±5%), the desticking time is less than 24h. If the temperature is low or the humidity is out of range, the time will be extended. The field test is ultimately to confirm that the sealant can disstick.

3) Elasticity test:

After the adhesive strip on the film paper is completely cured, tear off the sealant, slowly stretch to 100%, stay for 5S, release, determine whether there is a crack in the adhesive strip, whether it can be basically restored to the original state, and finally determine whether the elasticity is good.

5. Two-component sealant check

The two-component silicone sealant that is not used up on the gluing machine should first check whether the A and B components are contaminated, and then check whether the B components appear surface curing, stratification, etc.

If there is surface curing, the surface curing sealant can be cleaned up, and the remaining B component can still be used normally; If stratification occurs, the B component sealant can be stirred first, and then used after it is fully mixed.

Next, it is necessary to confirm the application of two-component silicone sealant in the gluing machine, including the mixing ratio of the gluing machine, the glue situation and the sealant performance after curing. In the inspection process, butterfly test, breaking time and snake test are needed to confirm the use of sealant:

1) Observe whether the A and B components produced by the glue machine are uniform by butterfly test;

2) Through the breaking time to confirm whether the applicable period of sealant meets the requirements of the standard, especially when the temperature is still low when the recent start, the breaking time will be extended to a certain extent, it is recommended that customers in the indoor close to the standard conditions to determine the breaking time;

3) Through the snake test to determine whether the glue machine can produce uniform curing sealant.

6. View data such as adhesion or compatibility test reports