Rock wool boards (also known as mineral wool boards) play a vital role in the fields of building exterior wall insulation and fire barrier, industrial equipment insulation, fire door cores, ship bulkheads, etc. due to its excellent fire performance (Class A non-combustible), excellent sound absorption and noise reduction capability, good thermal insulation effect and stable chemical properties. However, rock wool board itself has loose texture, porous fibers, low surface strength, and a certain degree of hydrophobicity, which brings challenges to its reliable bonding with various types of substrates (such as concrete, steel plates, brick walls, etc.). Polyurethane adhesive with its unique performance, is becoming a solution to the rock wool board bonding problems, building safe and efficient thermal insulation and fire prevention system of choice.
Core advantages of polyurethane adhesive in rock wool board bonding:
Strong penetration anchoring force and porous adaptability:
Polyurethane adhesive has good fluidity, infiltration and permeability, can penetrate into the fiber pores of the rock wool board, forming a strong “mechanical anchoring” effect, to overcome the low strength of the rock wool surface, difficult to bond the problem.
The cohesion formed after curing and the grip on the rock wool fibers work together to provide far more than cement-based bonding mortar initial bonding strength and final bonding strength.
Excellent flexibility and stress dispersion ability:
The cured polyurethane adhesive layer has high elasticity and toughness, and can effectively absorb and buffer the substrate and rock wool board between the deformation due to temperature differences, structural settlement, wind pressure and vibration of the stress generated.
This feature significantly reduces the risk of cracking, hollowing and peeling common to rigid bonding (such as cement mortar), especially for high-rise buildings or parts with large structural deformation.
Excellent weathering and environmental resistance:
Wide temperature stability: in the range of -40 ℃ to +90 ℃ (or even higher, depending on the specific product) can maintain good adhesive properties and elasticity, to adapt to the cold and hot environment.
Resistance to moisture and heat aging: stable performance in humid environments, not easy due to moisture absorption leading to a significant decline in bonding strength, to protect the long-term reliability of the system.
Freeze-thaw cycle resistance: strong resistance to freeze-thaw cycle, suitable for cold and cold regions.
(Part of the formula) has a certain degree of UV resistance.
Efficient construction and economy:
Convenient construction: Usually use the tube with the glue gun point sticking or strip sticking, the operation is simple and fast, relatively low technical requirements for workers.
Moderate opening time: Provide enough time for the operation to adjust the positioning of the plate.
Relatively fast curing speed: shorten the waiting time, improve the construction efficiency, especially in the low temperature environment compared with cement mortar obvious advantages.
Controlled dosage and reduced waste: The dotted frame or strip method allows precise control of the amount of adhesive used, avoiding the waste and weight gain associated with full cement mortar bonding.
Reduced load: The self-weight of the bonding layer is much lower than that of cement mortar, resulting in a lower load on the building structure.
Compatibility and fire safety:
High-quality polyurethane adhesive itself has good flame retardancy (usually up to class B), and the combination with class A non-combustible rock wool boards will not reduce the fire rating of the overall system, and meet the requirements of the building fire code (e.g. GB 8624).
After curing, the performance is stable, non-toxic and tasteless (in line with environmental standards such as GB 18583).
Typical application scenario:
Building exterior wall insulation fire isolation zone: in the exterior wall insulation system using organic insulation materials (such as EPS/XPS), according to the specification requirements in the door and window openings, between layers and other locations set rock wool fire isolation zone, polyurethane adhesive is pasted rock wool isolation zone to the base wall of the efficient and reliable way.
Curtain wall fireproof blocking and thermal insulation: used in the curtain wall between layers, doors and windows around the parts of the rock wool fireproof thermal insulation board paste.
Industrial equipment and pipeline insulation: rock wool insulation board/felt is firmly pasted on metal tanks, pipelines and equipment shells.
Adhesion of core board of fireproof door: as the adhesion material of rock wool core material and door board inside the fireproof door.
Fireproof and heat insulation of ship’s compartment: Paste rock wool boards for fireproof and heat insulation of bulkhead and ceiling.
Indoor fireproof partitions and ceilings: Paste rock wool boards in the area where fireproof and sound insulation are needed.
Key points of rock wool board bonding construction:
Base surface treatment:
Substrate (concrete, plaster, metal plate, etc.) must be solid, flat, dry, clean, free of oil, floating ash, mold releasing agent, loose material. Serious unevenness needs to be leveled.
If necessary, interface agent can be painted to enhance the strength of the grass-roots level or improve the bonding.
Rock wool board processing:
Ensure that the boards are dry, clean and undamaged. Prevent from rain and excessive squeezing during transportation and storage.
Key Steps: Surface Enhancement Treatment: For standard rock wool boards, it is highly recommended due to its easy shedding of surface fibers and low strength:
The use of double-sided composite reinforcement layer of rock wool board: such as glass fiber mesh or inorganic slurry with a layer of rock wool board, the surface of such boards can be directly glued bonding.
Or on-site brush special interface agent: in the ordinary rock wool board paste surface brush a layer of polymer interface agent (such as acrylic) with enhancement and sealing effect, closed surface fibers, improve the strength of the polyurethane adhesive to provide a good bonding substrate. This is an important part to ensure the reliability of bonding.
Glue application method:
Point frame method (preferred recommended): Along the rock wool board around the edge of the application of continuous adhesive strips (width usually ≥ 5cm), the formation of the border; in the middle of the board evenly spread a number of bonding points (diameter ≥ 10cm, the number of depending on the size of the board, usually ≥ 6). Ensure that the effective bonding area of ≥ 50% (specifically in line with the design and specification requirements, such as fire isolation zone is usually required ≥ 50%).
Strip bonding method: Apply several strips of adhesive tape (width and spacing in accordance with the requirements) in parallel on the rock wool board. Suitable for excellent flatness of the substrate.
Strictly prohibit only a small amount of glue in the center of the board.
Adhesion and compaction:
Paste the glued rock wool boards quickly (within the open time) to the predetermined position.
Press hard and evenly, and slightly knead and slide to ensure that the adhesive is in full contact with the base and the rock wool board, and the gel is partially pressed into the rock wool fibers.
Check the flatness with a ruler in time and adjust the misalignment.
Curing environment and maintenance:
During construction and curing, the ambient temperature should be 5℃-35℃, avoid rain, frost and direct sunlight on the uncured gel.
Ensure good ventilation to promote curing.
Avoid strong shock or vibration during the initial curing period (usually within 24 hours).
Auxiliary fixing:
For the rock wool fire barrier or large-size rock wool panels on the exterior walls of high-rise buildings, in addition to polyurethane adhesive bonding, mechanical anchors (e.g., special heat preservation nails) must be used for auxiliary fixing in accordance with specifications and design requirements to ensure system safety. Anchor installation should be carried out after the initial curing of the adhesive.
Summarize:
Polyurethane adhesive through its excellent penetration anchoring ability, excellent flexibility, reliable weather resistance and convenient construction characteristics, successfully solved the rock wool board, a porous, low-strength materials bonding problems. It is not only the key material to improve the construction efficiency and quality of rock wool insulation and fire prevention system, but also the core element to ensure the long-term safe and stable operation of the system. Especially in the application of critical safety parts such as the fire separation zone of the external wall of the building, the selection of high-performance polyurethane adhesive and strict adherence to the construction specifications, including the surface enhancement treatment, the point frame method of adhesive application, the necessary mechanical anchoring, is an important cornerstone for the construction of high-efficiency, durable, fire-safety enclosure structure. The importance of polyurethane adhesives in the bonding of rock wool panels will become more and more prominent as the requirements for energy efficiency and fire safety in buildings continue to improve.