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Adhesive Technology
PU Foams
Main applications: thermal, acoustic, and water insulation
PU foam (polyurethane foam) is created by mixing polyol and isocyanate. When exposed to moisture, the material expands and cures into a rigid, cuttable foam.
Key properties:
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Excellent adhesion
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Resistant to chemicals (oil, fuel, seawater, etc.)
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Paintable
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Cuttable
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Plasterable
PU foams are available in aerosol form, in both one- and two-component versions.
One-component types:
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Adapter (manual use)
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Gun-grade (more precise application, less material loss)
Lower-cost foams typically contain a higher proportion of open cells, resulting in reduced insulation performance. The insulating capacity depends on the gas composition within the कोश and the ratio of closed cells.
Application guidelines:
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Surface pre-moistening is essential
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Additional moistening after application is required
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For gaps larger than 5 cm, apply in multiple layers
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Fill joints only up to approx. 50% due to expansion
Curing time: approx. 2–3 hours
PU foam is not UV-resistant, therefore it must be protected from direct sunlight.
Storage:
Shelf life is significantly reduced at higher temperatures.
At 50°C, ageing occurs up to 7 times faster than at 20°C.
Above 50°C, the product may become hazardous.
Silicones
Silicone sealants are used to fill joints with a flexible, UV-resistant material.
They cure at room temperature through moisture exposure, and curing speed increases with humidity and temperature.
Types:
- Acetic cure silicones
- Release acetic acid during curing
- Highly corrosive
- Neutral cure silicones
- Release alcohol during curing
- Suitable for sensitive applications (electronics)
- Properties: excellent adhesion, UV-, acid- and alkali-resistant, water-repellent
- Not paintable
Sanitary silicones contain fungicides, making them ideal for bathrooms, kitchens, and humid environments.
Acrylic
Acrylic sealants are suitable for filling joints in:
- Walls
- Metal surfaces
- Wooden structures
They can be painted after curing.
Adhesives
Adhesive bonding is a permanent, non-movable joint, typically removable only by destruction.
It enables the joining of identical or different solid materials. The quality of the bond depends on the interaction between the adhesive and the substrate surfaces.
Adhesive technology is widely used both in everyday applications and industrial processes such as laminating or coating.
Classification of adhesives:
- By chemical structure (natural or synthetic polymers)
- By physical properties (liquid or solid)
- By bonding mechanism (chemical or physical curing)
- By application type
Common synthetic adhesive types:
- Epoxy resins
- Polyesters
- Polyurethanes
- Phenolic and amino resins
- Acrylics and methacrylates
- Cyanoacrylates (instant adhesives)
- Vinyl-based adhesives
- Polyamides
- Silicone resins
Overview
Advantages of Adhesive Bonding
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Suitable for a wide range of materials
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Minimal deformation
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No structural alteration (unlike welding)
Limitations
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Bond strength may decrease over time
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Generally lower long-term reliability compared to mechanical fastening
Bonding Process
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Surface preparation (cleaning, sanding, chemical treatment)
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Adhesive preparation (mixing if required)
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Application (spreading, dipping, rolling, spraying)
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Assembly and fixing of components
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Curing
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Post-processing (removal of excess adhesive, cleaning)
