What Is a Sealant?
Sealants are materials that are applied and filled into gaps and seams to make buildings and pipes waterproof and airtight.
It is used not only for professional use at construction sites but also for general use as an emergency treatment for repairing cracks in exterior walls and leaks in roofs. Various types of sealants are available at home improvement stores, and the material is easy to obtain.
The term “sealing material” includes sealants, which are liquid or paste solvents, as well as sealing tape, rubber packing, and other shaped materials.
Uses of Sealants
Sealants are used to strengthen airtightness and waterproofing in a wide range of locations, including building exteriors, interiors, and piping. They are also used to prevent joint misalignment caused by temperature changes, vibration, and pressure.
In general buildings, sealants are mainly used in the following areas:
- Kitchen, bathroom, washbasin, and other water areas
- Gaps between window sashes and exterior walls
- Joints between exterior wall materials
In other words, sealants are used and effective in areas of the building where there is a risk of water leakage, where there is a risk of water intrusion into the building, and where components are buffered and at risk of damage.
In addition, it is also used at the joints of piping, such as water pipes and gas pipes, to protect them from water and gas leaks. Sealants used for water pipes, hot-water pipes, and other water supply piping for drinking water should not only be airtight but also have excellent anti-corrosion and anti-corrosion properties.
Principle of Sealants
The principle of sealants is to fill and bond gaps and joints at the point of application by curing the raw polymer in a variety of ways.
There are two processes involved in curing a sealant:
- Component Model
Pre-mixed type with ingredients to cure raw polymer - Binary Component Type
A type that cures by kneading two components together
One-component sealants have the advantage of being stable in quality, with little under-mixing or poor curing, and being cartridge-type, making them less labor intensive. However, they take time to dry.
The advantage of two-component sealants is that the strength and speed of curing can be controlled depending on the environmental conditions of the application site. However, they are labor intensive, requiring an agitator or special applicator. In addition, since it relies on the operator’s knack, there is variation in quality.
Types of Sealant
There are two types of sealants: one-component and two-component. The one-component type is further divided into the following three major types:
1. Moisture Cure Type
Moisture cure type cures when the raw polymer reacts with moisture in the air. This is the most common type of sealant. Silicone-based, modified silicone-based, polyurethane-based, and polysulfide-based sealants are available.
2. Dry-Curing Type
The dry-curing type is a sealant with strong adhesive strength because the raw polymer hardens as it dries. Acrylic and butyl rubber types are available.
3. Non-Hardening Type
The non-hardening type forms a film on the surface in reaction to oxygen, but does not harden internally. When sealants were first used, this non-hardening type was the mainstream. Oil-based caulking materials correspond to this type. Since it does not have excellent weather resistance, care should be taken when using it.
Other Information on Sealants
Raw Materials for Sealants
Each type of sealant has the following characteristics:
- Silicon-Based
Relatively inexpensive, durable, and fast drying with excellent adhesion, but cannot be over coated after use. - Modified Silicon
Wide range of materials available, paint can be over coated, but price is slightly higher - Urethane
Very durable and can be painted over, but is sensitive to UV rays - Acrylic
Water-based solvent can be used in wet areas and can be painted over, but is less durable
In light of these characteristics, it is important to select the appropriate sealant according to the location and application.