PU Foam Sealant Overview
Polyurethane foam sealant（PU Foam Sealant）, commonly known as expanding foam, foam adhesive, or PU sealant, combines aerosol technology with polyurethane foam technology. When you spray the material from the aerosol can, the foam-like polyurethane rapidly expands and reacts with moisture in the air or on the contacted substrate to form a solid foam.
The cured polyurethane foam sealant provides multiple functions, including filling gaps, bonding, sealing, thermal insulation, and sound absorption. It serves as an environmentally friendly, energy-saving, and easy-to-use building material. People widely apply it for sealing leaks, filling voids and cracks, fixing and bonding, as well as insulation and soundproofing. It works especially well for sealing and waterproofing gaps between plastic steel or aluminum alloy doors, windows, and walls, and its applications continue to expand.
Usage Instructions
Before application, remove oil, dust, and debris from the surface to be treated, and lightly spray water on it. Shake the polyurethane foam can vigorously for at least 60 seconds to ensure the material inside is well mixed.
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For gun-type PU foam sealant: invert the can, connect it to the spray gun via threaded fitting, open the flow valve, adjust the foam flow, and then spray.
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For tube-type PU foam sealant: screw the plastic nozzle tightly onto the valve thread, align the nozzle with the gap, and press the nozzle to spray.
While spraying, maintain a steady moving speed. Usually, fill the gap to about half of its volume. When filling vertical gaps, spray from bottom to top. For overhead gaps such as ceilings, due to gravity, uncured foam may drip down; it is recommended to provide temporary support until the foam cures and adheres to the gap walls, then remove the support.
After approximately 10 minutes, the foam will partially detach; it can be cut after 60 minutes. Use a knife to remove excess foam, then finish the surface with cement mortar, paint, or silicone sealant.
Precautions
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The normal operating temperature for PU foam cans is 5 to +40°C, with an optimal use temperature of 18–25°C.
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In low temperatures, it is advisable to store the product at 25–30°C for 30 minutes before use to ensure performance.
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The cured foam tolerates temperatures from -35°C to 80°C.
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PU foam sealant cures by moisture; spraying on damp surfaces speeds curing.
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Uncured foam can be cleaned with solvents; cured foam must be removed mechanically by sanding or cutting.
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Exposure to ultraviolet (UV) light causes the foam to yellow; therefore, it is recommended to coat cured foam surfaces with other materials such as cement mortar or paint.
Formulation and Preparation
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According to patent CN201611213415, a polyurethane foam sealant composition comprises (by weight):
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200 parts of a mixture of trifunctional polyether polyol, bifunctional polyester polyol, and polymethylene polyphenyl isocyanate,
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60 parts of dimethyl ether,
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6 parts of dibutyltin dilaurate,
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7 parts of silicone-based foam stabilizer,
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5 parts of a composite of chlorine trioxide and antimony oxide,
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3 parts of a mixture of polyacrylic acid, polyacrylamide, and polymethylacrylic acid hydrogels in a 1:1:1.5 weight ratio.
This formula enhances the adhesive properties of the foam by about 35% compared to conventional formulations due to the addition of the polymer hydrogel adhesive.
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Preparation involves mixing the pre-measured polyurethane prepolymer, blowing agent, catalyst, foam stabilizer, flame retardant, and adhesive at room temperature until uniform, then filling into a pressure container.
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Patent CN201410773472.0 describes a method to prepare a one-component, single-foam polyurethane foam sealant using a composite catalyst and coupling agent, accelerating gelation and molding speed. Organic solvents are added to ensure rapid foam expansion and fixing upon spraying, achieving 90–100% one-time foaming with high expansion ratio.
Synthesis of Composite Catalyst:
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In a 200 mL three-neck flask equipped with a thermostatic water bath, thermometer, dropping funnel, and mechanical stirrer, add 65.6 g of 2-methylhexanoic acid and start stirring.
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Slowly add 77 g of 1,8-diazabicyclo[5.4.0]undec-7-ene through the dropping funnel at 10°C over 30 minutes.
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Heat to 90°C for 2 hours, cool to room temperature, filter to obtain the composite catalyst.
Preparation of Polyether Mixture:
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Add raw materials into a 500 mL three-neck flask according to the formula, stir for 1 hour at room temperature to produce the polyether blend.
Preparation of PU Foam Sealant:
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Into a 750 mL aerosol can, add 300 g polyether blend and 240 g polymethylene polyphenyl isocyanate.
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Fill with 60 g dimethyl ether and 75 g butane using an aerosol filling machine.
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Shake vigorously for 3 minutes, then store at room temperature for 24 hours before use.
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The resulting single-component foam sealant samples show a one-time foaming rate of 96%, with foam dimensions approximately 4 cm wide, 3 cm high, extending up to 33 meters.
Contact Us
If you have any questions or need more information about our products and services, feel free to reach out to us through the following contact details:
Phone/WhatsAPP:
+86 15853657921
Email:
cy971109@gamil.com
Address:
No.198 Yishan Road,Dongcheng Street,Linqu County,Weifang City,Shandong Province,China
Customer Service Hours:
Available 24 hours a day, 7 days a week
