Polyurethane foam (PU foam), the full name of which is single-component polyurethane foam sealant, is a moisture-curing, multi-purpose elastic sealing material, commonly known as foaming agent, foaming glue or PU sealant. It is made by combining aerosol technology with polyurethane foam technology by filling components such as polyurethane prepolymer, foaming agent, and catalyst into a pressure-resistant aerosol can. When the material is sprayed out of the can, it expands rapidly and reacts with the moisture in the air or matrix to solidify, forming a foam structure with functions such as caulking, bonding, sealing, heat insulation, and sound absorption. It is an environmentally friendly, energy-saving, and convenient building material.
1.Core functions
Filling function
After curing, a stable foam structure is formed, which can effectively fill irregular spaces such as gaps in doors and windows and cavities in walls. It is especially suitable for sealing between plastic steel or aluminum alloy doors and windows and walls.
Sealing function
With its elasticity and water resistance, it can prevent the penetration of gas, liquid and dust, and is widely used in scenes such as waterproof plugging and pipeline sealing.
Bonding function
It has strong bonding force to a variety of materials such as wood, metal, glass, plastic, etc., and can be used in industrial fields such as automotive lamp bonding, electrical appliance caulking, furniture fixing, etc.
Additional effects
The cured foam also has the characteristics of heat insulation, sound insulation, sound absorption, etc., and is often used for building insulation and equipment noise reduction.
3. Composition and curing principle
Main raw materials: polyurethane prepolymer (generated by the reaction of polyisocyanate compounds and polyether/polyester polyols), foaming agent, catalyst and solvent.
Curing principle:
Polyurethane foam is cured by reacting with moisture in the air. The isocyanate component inside it combines with water to form solid particles and releases CO₂ gas, which promotes the expansion of the foam.
The curing process depends on the ambient humidity. High humidity can accelerate the reaction; at the same time, air circulation is required to ensure sufficient contact with moisture.
Curing conditions:
Temperature: The optimal curing temperature is 20℃–30℃. Too low temperature will delay the reaction.
Humidity: The higher the humidity, the faster the curing speed.
Ventilation: Avoid closed environments and ensure air circulation.
4. Product types and construction
Polyurethane foam glue is divided into two types: tube type and gun type:
Tube type: comes with a disposable hose, easy to operate, suitable for small-scale repairs.
Gun type: requires a special spray gun, high precision, suitable for professional construction scenarios (such as large-area caulking).
5. Application areas
Construction industry: door and window installation caulking, wall sealing and plugging, roof waterproofing, insulation and sound insulation layer construction.
Industrial manufacturing: bonding of automotive lamps and parts, caulking of electrical housings, and sealing of freezers/storage rooms.
Other areas: fixing sand table models, garden scenery, furniture repair, etc.
6. Environmental protection and advantages
Polyurethane foam glue is non-toxic, pollution-free, and meets environmental protection standards. Its fast curing and multifunctional characteristics significantly improve construction efficiency while reducing energy consumption. It is an indispensable high-efficiency material in modern construction and industry.
Summary: From home decoration to industrial manufacturing, polyurethane foam has become a “jack of all trades” in cross-field applications due to its excellent filling, sealing and bonding properties. Correctly mastering its curing conditions and construction methods can maximize its performance advantages.
