Adhesives
Adhesive, any substance that is capable of holding materials together in a functional manner by surface attachment that resists separation. In the performance of adhesive joints, the physical and chemical properties of the adhesive are the most important factors. Also important in determining whether the adhesive joint will perform adequately are the types of adherend (that is, the components being joined-e.g., metal alloy, plastic, composite material) and the nature of the surface pretreatment or primer. These three factors-adhesive, adherend, and surface-have an impact on the service life of the bonded structure. The mechanical behaviour of the bonded structure in turn is influenced by the details of the joint design and by the way in which the applied loads are transferred from one adherend to the other.
Advantages of Adhesives
Adhesives bond dissimilar and hard to bond materials
Adhesives can bond hard to bond materials such as low surface energy plastics, oily metal and silicone rubber.
Adhesives bond and seal simultaneously
Using adhesives to bond two surfaces helps seal out water, moisture, dirt and other environmental contaminants. Because the seal has adhesive properties, there is no need for a separate mechanical fastener.
Adhesives reduce stress concentration at screw and rivet points
Mechanical fastening requires drilling holes, and attachment at each hole concentrates stress at that point. Because adhesives and tapes bond over an area rather than points, they disperse the load over the entire bond area.
Adhesives can impact production efficiency
Incorporating adhesives and tapes into the manufacturing process can improve efficiency by eliminating process steps, failure rates, and time of assembly. Adhesives and tapes can increase speed, reduce cost, reduce labor hours and streamline operations.
Adhesives improve appearance
Adhesives provide virtually invisible fastening to keep surfaces smooth and clean with no visible screws, rivet heads or protruding nuts and bolts. Adhesives also save the time and cost of refinishing welding burn marks.
Adhesives and tapes can reduce vibration, fatigue and noise
Because adhesives and tapes are viscoelastic, they are energy absorptive and improve the impact, vibration and fatigue performance of your design.
Why Choose US
Our factory:Hangzhou Weitong Nanomaterials Co., Ltd. is an innovative enterprise focusing on the field of nanomaterials, founded in 2015. Our factory has an efficient production capacity and is able to produce a wide range of high-quality products.
Our product:Our range of NVP-based products covers various series tailored to different industries. This includes the homopolymer series (K15-K120), copolymer series (VA64 powder, V64E, VA64W, 73W, 37E, 37W), and cross-linked series (PVPP XL-10, PVPP-10, povidone-iodine pvpI). These products find applications across diverse sectors, serving as stabilizers, dispersants, coatings, inks, and adhesives.
Quality control:We have the ISO9001 certificate, and we strictly follow GMP production standards for production.
Good after-sale service:We have a sound after-sales service system, so whatever you have any doubt about the product, you can strictly contact us, we will give you a satisfied plan.
①Natural adhesive
It is derived from substances found in nature. Including starch, protein, dextrin, animal glue, shellac, hide glue, rosin and other biological adhesives; also includes mineral adhesives such as asphalt.
②Synthetic adhesive
Mainly refers to artificially synthesized substances, including inorganic adhesives such as water glass, and organic adhesives such as synthetic resin and synthetic rubber.
Use characteristics
①Water-soluble adhesive
Adhesives that use water as solvent mainly include starch, dextrin, polyvinyl alcohol, carboxymethyl cellulose, etc.
②Hot melt adhesive
It is a solid adhesive that is melted by heating. General thermoplastic resins can be used, such as polyurethane, polystyrene, polyacrylate, ethylene-vinyl acetate copolymer, etc.
③Solvent-based adhesive
An adhesive that is insoluble in water but soluble in a certain solvent. Such as shellac, butyl rubber, etc.
④Emulsion type adhesive
Most of them are suspended in water, such as vinyl acetate resin, acrylic resin, chlorinated rubber, etc.
⑤Solvent-free liquid adhesive
It is in the form of viscous liquid at room temperature, such as epoxy resin, etc.
How Do Adhesives Work
The working of adhesive depends on the types of bonding process used to attach the surfaces to each other. Mechanical adhesion and chemical adhesion are two types of bondings that can be used to stick one surface to another with adhesives.
Usually, surfaces that need to be attached with the help of adhesives, have a lot of micropores. These pores when filled with adhesives act as grips to keep another surface attached to them. This is called mechanical adhesion. With mechanical adhesion, the adhesives are in liquid form. The liquid adhesives will gradually penetrate the pores during the drying and curing process. You should also keep in mind that mechanical bonding is dependent on the surface roughness and surface energy of the substrates to be bonded. The higher the surface energy and roughness of a substance, the stronger is the bond.
On the other hand, chemical bonding is completely different which sees the surface of a material completely bond with another material on a molecular level. It is a complex process but very effective at the same time. Chemical bonding is further categorised into two types; adsorption and chemisorption depending on the type of bond between the adhesive's molecules and the surface. Although chemical adhesives are easily available, they are not a common form of adhesive used in Industries.
How Does Surface Preparation Improve Bonding
Before adhesive bonding, it's essential to prepare the surface to obtain a strong bond.
The substrates need to be clean of contaminants, slightly rough, and have a chemical composition that favors bonding. Here's how each of these aspects contributes to a stronger bond.
Remove contaminants
Contaminants like oxides and greases can interfere with the bonding process. By removing them, you eliminate the risk of unwanted chemical reactions between the adhesive and the contaminants. You also free up surface energy, making room for more bonds between the substrate and the adhesive.
Roughen the surface
Rough surfaces have more surface area to which adhesives can adhere. They improve mechanical interlocking and create more opportunities for chemical bonds.
Modify the chemical composition
Chemical bonds can be weaker or stronger depending on the chemical composition of the surface. By adding new molecules or rearranging how atoms are configured on the surface to form new molecules, it is possible to create a more favorable surface for chemical bonding.
Adhesive Application Methods
Manual
As the name suggests, in this method, the applicator uses handheld devices and tools to apply adhesives to the surfaces. Manual adhesive application methods can include spraying, web coating, using a brush and a roller, curtain coating etc. Manual application is cost-effective and is recommended for smaller applications.
Glue Applicator
Glue applicators are handheld devices that assist you to apply adhesives uniformly and at a faster rate than manually. These applicators contain a gun fitted with a cartridge containing the adhesive. A mixing tip is attached to the front of the cartridge to eliminate the need for any manual mixing. These semi-automatic devices enable higher speed, precision and efficiency. Glue applicators are ideal for medium to large-scale applications and are commonly used in the aerospace, electronics and optical industry to fuse small and detailed pieces of equipment.
Automatic Dispensing
Automatic dispensing is ideal for fast-paced and high-volume environments where consistency and quality finish is crucial. This method is more costly as compared to the above two, however, automatic dispensing can increase efficiency, reduce waste and complete the task at a large scale. Metre-mix-dispense systems are used for two component adhesives and robotic dispensing is used for single component adhesives.
Different adhesives can be categorized by their chemistries. Below are a few examples of available chemical compositions.
Epoxy adhesives
Epoxies are a type of structural adhesive. They are highly temperature and solvent resistant and can be structurally bonded to most types of materials, such as metals, ceramics, wood and plastics.
Polyurethane adhesives
Polyurethanes are polymer-based adhesives used for constructions requiring high strength bonding and permanent elasticity. They are often offered as two-part adhesives and have many uses. Unlike epoxy adhesives, they require moisture to set, which means they can be used for projects where other types of glues are often unsuitable.
Polyurethane adhesives, such as the Adbond EX 5690, can be painted for an ideal finish, offer high flexibility and can be used in any weather. This makes polyurethanes ideal for the transport industry.
Polyimide adhesives
Polyimides are one-part synthetic polymers that usually contain solvents. They are known for their strength, heat and chemical resistance, as well as performance in extremely high temperatures, as high as 500 degrees Celsius.
They are offered in two formulations, thermoset and thermoplastic, and are often used for coating or electronic insulation.
What Are the Surface Preparation Methods
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Can bond dissimilar materials |
Adhesives can bond different types of materials together. This versatility allows for innovative designs and assemblies. |
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Add less weight to assemblies |
Adhesives typically contribute minimal additional weight to assemblies compared to mechanical fasteners or welding, which can be crucial in applications where weight is a concern, such as in the aerospace and automotive industries. |
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Provide environmental protection |
Adhesive bonds can seal against external factors like water and dust, providing environmental protection to the bonded materials. This helps enhance durability and longevity, particularly in outdoor or harsh environments. |
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Assemblies gain strong mechanical properties |
Adhesive bonds can distribute stress more evenly across bonded joints, leading to strong and durable bonds. This can result in assemblies with superior mechanical properties. |
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Can serve as thermal conductors or insulators |
Depending on the adhesive material used, adhesives can act as either thermal conductors or insulators. This property allows for precise temperature management in various applications, from electronics to automotive components. |
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Can serve as electrical conductors or insulators |
Adhesives can also be designed for electrical conductivity or insulation, making them suitable for use in electronic devices where electrical connections need to be made or protected. |
Adhesives by Physical Form
Adhesive physical form affects product application. Adhesives can be spread manually or using tools and equipment.
Below are the different physical forms available.
Paste
Adhesive pastes are often high in viscosity, thereby making them difficult to spread during the curing period. They are ideal for adhesions requiring gap filling and are usually applied with the use of tools, such as a caulking gun.
Film
Adhesive films are available in rolls or pre-cut lengths or shapes, provide easy application, and have no pot-life restrictions. They are available in thicknesses between 2 and 8 mm for different applications.
Liquid
Liquid is the most common form of adhesive. They are one of the easiest to apply but can leak or sag during the curing process. They often take longer to cure but can be applied in thin layers to help this process.
Pellets
Adhesives in the form of pellets are typically hot melt or thermosetting adhesives. These must usually be inserted into a hot melt gun or melted and sprayed.
Adhesives by Load Bearing Capability
The load bearing capability of an adhesive indicates how well it can hold different substrates together. They can be separated into three categories.
Structural
Structural adhesives are offered as pastes, liquids and films. They are strong and usually used below their glass transition temperature (Tg), the temperature at which polymer transitions into a soft and rubbery material.
Some well-known structural adhesives are epoxies, cyanoacrylates, urethanes and acrylics.
Non-structural
Non-structural adhesives are used for light loads or in more aesthetic applications. Both non-structural and semi-structural adhesives are much more cost-efficient alternatives to structural adhesives, but they are not suitable for all types of projects. Non-structural adhesives are often used as secondary fasteners in more long-term attachments rather than as a main adhesive.
Semi-structural
Semi-structural adhesives are ideal for less critical applications, though they still offer more strength and support than non-structural adhesives. They can therefore be used to replace either structural or non-structural adhesive applications, depending on the project.
Industrial adhesives are made up of a range of organic compounds that are combined in specific formulations to produce adhesives with a variety of properties. These properties can range from water-based adhesives to polyolefins, ethylene-vinyl acetate (EVA), polyurethanes, and more.
Water-based adhesives are made from a mixture of water-soluble polymers and other organic compounds. They are commonly used in industries where low toxicity and easy clean-up are important, such as in the paper and packaging industry.
Polyolefins, such as polyethylene and polypropylene, are another type of industrial adhesive that is commonly used in the packaging industry. They are made from polymers derived from hydrocarbons and are known for their excellent adhesion to a wide range of substrates.
Ethylene-vinyl acetate (EVA) is a type of industrial adhesive that is used in a range of industries, including footwear, packaging, and automotive. EVA is made from a copolymer of ethylene and vinyl acetate and is known for its flexibility and toughness.
Polyurethanes are another type of industrial adhesive that is commonly used in industries such as construction, automotive, and electronics. They are made from polyols and diisocyanates and offer excellent adhesion to a wide range of substrates, as well as resistance to water and chemicals.
What Industries Make Use of Industrial Adhesive
Thanks to the wide range of compatible materials, industrial adhesives are used in virtually all industries that perform some kind of construction or manufacturing. Here are a few examples of industries that make use of industrial adhesives.
Automotive industry
Industrial adhesives are typically used in the manufacturing of vehicles. It’s used to bond certain components together, and can also be used to create seals on components like door panels and windshields.
Aerospace industry
The aerospace industry uses industrial adhesives to securely bond and seal components. This can include aircraft panels, windows, and other important areas that may be subject to extreme conditions during flight. The properties of industrial adhesives help the final product become resistant to extreme temperatures, adverse weather, and environmental factors.
Packaging industry
Industrial adhesive can be used to seal packaging. This can include boxes, cartons, crates, and even plastic packaging. It can be used in small amounts to seal consumer products, or in larger quantities for big items.
Electronics industry
The electronics industry uses smaller quantities of industrial adhesive to bond and seal electronic components. This can include circuit boards and their related components, or sealing different areas of an electronic device to protect it from humidity and dust. Industrial adhesive can also be used as part of a larger project that utilizes electronics, such as protecting the internals of a vehicle or a specialized piece of machinery.
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