Adhesives glue play an important role in modern industry and daily life, and are widely used to bond, seal and repair various materials and surfaces. Polyurethane adhesives are a common and versatile adhesive, known for their excellent adhesion properties and a variety of applications. This article will explore the manufacture, role, application and unique characteristics of PU adhesives to provide you with a comprehensive understanding.
1. Definition of polyurethane adhesives
Pu adhesive is a type of adhesive whose base material is polyurethane polymer. Polyurethane is a class of polymers that contain amino and isocyanate functional groups in their molecular structure. These functional groups are able to chemically combine with other substances in chemical reactions to form a strong bonding.
2. Classification of polyurethane adhesives
Polyurethane adhesives can be divided according to different classification standards, mainly including classification by reaction composition, classification by usage and characteristics, classification by chemical properties, curing mechanism, packaging form and function.
Classification by reaction composition
Polyisocyanate adhesives, adhesive glues containing isocyanate groups, polyurethane adhesives containing hydroxyl groups, epoxy resin adhesives, silicone modified adhesives and acrylic modified adhesives, etc. In addition, polyurethane adhesives can be further subdivided according to their oligomer polyol types, including polyether polyol based adhesive, polyester polyol based adhesive and polyolefin based adhesive, etc.
Classification by usage and characteristics
It can be divided into general adhesives, adhesives for flexible packaging, adhesives for shoes, adhesives for paper-plastic composites, construction adhesives, structural adhesive, adhesives for ultra-low temperature, foaming adhesives, anaerobic adhesives, conductive adhesives, hot melt adhesives, pressure-sensitive adhesives, sealing adhesives, water-based adhesives and adhesive sealant, etc.
Classification by chemical properties
polyurethane adhesives can be divided into reactive and non-reactive types, one-component solvent volatile type, one-component moisture curing type, two-component reactive type, hot melt type, light curing type, etc.
Classification by curing mechanism
including single-component solvent evaporation type, single-component moisture curing type, two-component reaction type, hot melt type, light curing type, etc.
Classification by packaging form
PU adhesives can be divided into single-component, two-component, or even multi-component.
Classified by whether it contains solvents
it can be divided into solvent-free liquid adhesives, hot melt adhesives, solvent-based adhesives, waterborne adhesives, etc.
Classification by function
pressure-sensitive adhesive, hot-melt adhesive, structural adhesive, putty type, permanent type, transparent type, etc.
3. Characteristics of polyurethane adhesive
Strong bonding strength, large initial bonding force, and wide application range
It can not only bond porous materials such as foam plastics, ceramics, wood, fabrics, etc., but also a variety of metals, inorganic materials, plastics, rubber and leather, etc. It is an adhesive with a wide range of applications.
3.1 Excellent chemical resistance
Polyurethane adhesive has good chemical resistance, can withstand corrosion from a variety of chemical reagents, and is not easy to age.
3.2 Good heat resistance
Pu adhesive has good heat resistance and can be used at higher temperatures.
3.3 Good shear resistance
Polyurethane adhesive has good shear resistance, can withstand various shear forces, and is not easy to shear off.
3.4 Flexible customized design
Laminating adhesives have good design flexibility and can be designed and produced according to different application scenarios to meet individual demand.
4. Application of polyurethane adhesive
Polyurethane adhesives are widely used in a wide range of fields, including automobile manufacturing, woodbonding industry, shoemaking industry, flexible packaging industry, construction and pavement industry, and other industries.
Automobile manufacturing
Polyurethane adhesives are widely used in automobile manufacturing, mainly for assembling windshields, bonding glass fiber reinforced plastics and sheet molded composite materials, etc. In addition, the bonding of automotive interior parts is also an important application field of adhesive sealants.
Woodbonding industry
The application of polyurethane adhesives in the woodworking and furniture industry is mainly to replace traditional formaldehyde-based wood adhesives to reduce environmental pollution. Its high bonding strength and excellent flexibility make it an ideal choice for the wood processing industry.
Shoemaking industry
Woodbonding adhesives are mainly used in the shoemaking industry for bonding low-polar materials, such as SBS and other materials. By adding tackifying resins for modification, polyurethane shoe adhesives with high peel strength can be developed.
Packaging industry
Laminating adhesives are widely used in the field of flexible packaging. They can bond film materials of different properties to obtain composite films for flexible packaging with various properties such as cold resistance, oil resistance, chemical resistance, transparency, and wear resistance.
Building paving industry
Polyurethane adhesives are mainly used in the building paving industry for elastic rubber mats, hard rubber floor tiles, laying plastic tracks, permeable stone pavement, etc. It is also widely used in the bonding of PVC film lamination for construction, sandwich panel production, and building waterproof coatings. Its excellent low temperature resistance, solvent resistance, aging resistance and other properties make it play an important role in building paving materials.
Other industries
In addition to the above-mentioned fields, polyurethane adhesives are also playing an increasingly important role in book binding, health equipment, bonding of aerospace equipment, protection and restoration of cultural relics, stationery, health care, etc.
5. Conclusion
In summary, with the gradual expansion of polyurethane applications and the continuous enhancement of human environmental awareness, polyurethane adhesives play an important role in many fields due to their excellent performance and wide applicability, and are one of the indispensable synthetic materials in modern industrial production.
