for construction is widely accepted as the waterproof sealing material widely used in interior and exterior decoration of various buildings. However, with the rapid development of silicone sealants
for construction, such as colloid hardening, embrittlement and chalking, oil leakage, cracking of joints, failure of insulating glass unit parts, structural bonding deterioration, etc. appear. Part of the reason is that due to the vicious competition in the market, many manufacturers have added plasticizers in the production of silicone sealants
for construction, but a large part is due to consumers' lack of understanding of product performance or improper operation of the constructors. Affects the overall performance of silicone
The following is a basic introduction to the silicone sealant
for construction and some misunderstandings and improper methods during the purchase and use.
A. Characteristics of silicone sealant
Silicone sealant refers to the sealant produced by linear polysiloxane as the main raw material, also known as silicone sealant. The polymer backbone of the silicone sealant is mainly composed of silicon-oxygen-silicon bonds. During the curing process, the cross-linking agent reacts with the base polymer to form a network-like Si-Q-Si skeleton structure. Compared with other organic polymer sealants (such as polyurethane sealant, acrylic sealant, polysulfide sealant, etc.), the most remarkable feature is excellent high temperature resistance and weather resistance.
B. Classification of building silicone
m sealant: Most of the silicone sealant
used in construction is a room temperature vulcanization (RTV) condensation type curing system, that is, it does not need to be heated during curing, and can be cured at room temperature, during curing. Some small molecules will be released.
1. Classification according to curing system:
According to the type of small molecules released during curing, the silicone sealant
for building construction can be mainly divided into deacetic acid type, deketone type, dealcohol type, and dealuamine type.
2. Classification according to the number of components:
According to the number of components of the product, silicone sealants
for building construction can be generally divided into two categories: single component silicone rubber
and two component silicone rubber
(2) Hidden dangers in the production process of silicone sealant
for construction: Nowadays, due to the disorderly development of the domestic market, the market is viciously competitive. In addition, due to the rising raw materials and increasingly fierce competition, many enterprises and even famous enterprises, in order to pursue profits, the cost of reducing the product is reduced by reducing the cost. The main reason is to add plasticizer to change the brightness of the appearance and increase the selling point.
2) Adding additives to add more fillers and reduce costs.
3) Use recycled raw materials such as base rubber, silicone oil, etc. to hit the market at low prices. At least 80% of the silicone sealant
products used in construction that are now on the market add more or less plasticizer-white oil. White oil, liquid paraffin oil, is a colorless, odorless, odorless, non-fluorescent transparent oily liquid obtained by high pressure hydrotreating of petroleum lubricating oil fractions. It is flammable and volatile; white oil is physically added for building construction. Silicone sealant: Features one can reduce the amount of silicone base polymer, reduce product cost, improve extrusion, softness and brightness. Hazard--cure speed is slowed down, oil leakage is polluted, the surface is easy to wrinkle, sticky dust is accumulated, and the mechanical properties are low with the continuous precipitation of white oil, and the rubber joint becomes hard, shrink, debonded and cracked in half a year. It will bring serious hidden dangers to the quality of the project.
3. What should I pay attention to when purchasing silicone sealant for construction?
1) Recognize the brand. Effective registered trademarks, clear image recognition, reasonable price positioning, and perfect after-sales service are the criteria for the recognition of branded products.
2) Look at the packaging. When you look at the carton, there is no product name, factory name, specification, origin, color, date of manufacture, whether there is a certificate of conformity, quality guarantee, or product inspection report in the carton. Second, look at the use, usage, precautions of the plastic bottle, etc. Clear and complete; three to see if the net content is accurate, the manufacturer must indicate the specification and net content on the bottle.
3) Gum quality.First smell the odour, second compare the gloss, third check the particles, fourth look at the bubbles, fifth check the solidification, sixth exam the tensile and stamps.