What is a high temperature sealant? How long does the high temperature sealant take to dry? Basic overview of high temperature sealant

Basic overview of high temperature sealants

High temperature sealant, as the name suggests, is used for bonding and sealing protection in the environment under high temperature conditions. It is a one-component silicone paste sealant, industrial use, high-quality sealing compound, suitable for smooth and flat sealing surface ( Butt joints) with high temperature and pressure conditions.

Silicone high temperature sealant is a high temperature sealing adhesive made of organic silica gel as the main body, defoamer, leveling agent, curing agent and other polymer materials.

The limit of high temperature resistance of sealant

  1. High temperature resistant sealant is a high temperature resistant silicone sealant, which can be continuously maintained at -65°C without affecting performance. It can withstand high temperature intermittently, has long-lasting elasticity, good high temperature sealing function and high electrical insulation function , Excellent anti-oil, anti-grease and anti-vibration properties, it is a special colloid that has strong interstitial ability, wide operating temperature range, high pressure resistance, corrosion resistance and oil-carrying conditions.
  2. A variety of special additives are added to the high temperature-resistant sealant, and the inorganic structural adhesive with high temperature resistance to 538 ℃ is prepared by mixing. Drops or shortens due to changes in heat and cold.
  3. The fully cured silicone sealant can continue to be useful when the temperature reaches 204°C (400oF), but when the temperature is as high as 218°C (428oF), the useful time will be shortened.
  4. It is a silicone structural sealant, and its construction temperature range should be controlled between 5-40 °C. After full curing, its useful temperature should be kept at 204 degrees, and its useful life will be shortened when it exceeds 218 degrees.
  5. The high temperature sealant can be used in the temperature range of -55℃ to 200℃, and the higher temperature should not exceed 250℃ in a short time.

How long does the high temperature sealant take to dry?

  1. Sticking time

Different properties of silicone surface dry time and curing time are not the same. Acid glue, neutral transparent glue should generally be 10 minutes, neutral variegated glue should generally be 30 minutes.

  1. Curing time

(1) The curing time of the high temperature sealant increases with the increase of the bonding thickness. For example, the acid sealant with a thickness of 12 mm may take 3 to 4 days to fully solidify, but in this process, it is generally 24 hours The inner 3mm outer layer is cured.

(2) If the place where the sealant is used is partially or completely closed, the curing time is determined by the tightness of the seal. In an absolutely airtight place, it is possible to remain uncured forever.

How to use high temperature sealant

  1. Put the rubber nozzle on the hose, and then cut the nozzle obliquely;
  2. Clean the surface of the product material, and apply glue on the bonding and sealing position of the product;
  3. Aim at the bonding part and paste it, and press it to fit tightly;
  4. The initial positioning time is about 15-30 minutes, and the test is done after 24 hours.

What should I pay attention to when using high temperature sealant?

  1. The bonding surface should be kept dry and tidy, and there should be no residue of dust or oil.
  2. Cut the beak according to the actual needs, try not to cut it as large as possible, so as to avoid waste.
  3. The adhesive layer needs to be scraped flat before the surface is dry. Once cured, it will not be able to be scraped.
  4. After the sealant is completely cured, cut off the excess part directly with a blade.

Some industries do not have special requirements for the temperature resistance of sealants, and ordinary sealants can be selected. If the temperature of the working environment is too high, ordinary products cannot resist high temperature, and high temperature sealant can be used. It can be used for a long time at high temperature and will not be easily melted.

What is adhesive? What are the main physical properties and testing standards of adhesives?

What is adhesive?

The use of adhesives is used in all aspects of life and production, such as adhesives for electronic components, adhesives for automotive interior parts, adhesives for packaging materials, surface bonding of shoe materials and other construction or decorative materials; then what are adhesives? What are the main physical properties and testing standards of adhesives?
Adhesion (bonding, bonding, gluing, gluing) refers to the technology in which the surfaces of homogenous or dissimilar objects are joined together with an adhesive, which has the characteristics of continuous stress distribution, light weight, or sealing, and low temperature for most processes. Adhesive bonding is especially suitable for the connection of different materials, different thicknesses, ultra-thin specifications and complex components.
A class of natural or synthetic, organic or inorganic substances that can connect two or more parts or materials through interfacial adhesion and cohesion, collectively referred to as adhesives, also known as adhesives , customarily referred to as glue. In short, an adhesive is a substance that binds the adherends together through adhesion. “Adhesive” is a generic standard term.

Main physical properties of adhesive

  1. Operation time
    Maximum time interval between adhesive mixing and pairing of parts to be bonded
  2. Initial curing time
    Time to Removable Strength Allows Adequate Strength for Handling Bonds, including Moving Parts from Fixtures
  3. Complete curing time
    Time required to achieve final mechanical properties after adhesive mixing
  4. Storage period
    Under certain conditions, the adhesive can still maintain its handling properties and the storage time of the specified strength
  5. Bonding strength
    Under the action of external force, the stress required to make the interface between the adhesive and the adherend in the adhesive part break down or its vicinity
  6. Shear strength
    Shear strength refers to the shear force that the unit bonding surface can withstand when the bonding part is damaged, and its unit is expressed in MPa (N/mm2)
  7. Uneven pull-off strength
    The maximum load that the joint can bear when subjected to uneven pull-off force, because the load is mostly concentrated on two edges or one edge of the adhesive layer, and the force is per unit length rather than per unit area, and the unit is KN/m
  8. Tensile strength
    Tensile strength, also known as uniform pull-off strength and positive tensile strength, refers to the tensile force per unit area when the adhesive is damaged by force, and the unit is expressed in MPa (N/mm2).
  9. Peel strength
    Peel strength is the maximum load per unit width that can withstand when the bonded parts are separated under the specified peeling conditions, and its unit is expressed in KN/m

Common test items for adhesives

  1. Physical properties
    General properties: thickness; viscosity; water resistance
    Mechanical Testing: Tensile Properties; Peel Strength; Tensile Shear Strength; Compressive Shear Strength; Horizontal and Vertical Tack
    Burning performance: horizontal burning; vertical burning; glow wire burning
    Electrical properties: surface and volume resistivity of insulating materials; surface resistivity of anti-static materials; dielectric strength, breakdown voltage; withstand voltage
  2. Aging test
    Rapid UV aging; xenon lamp aging; temperature and humidity aging; salt spray aging; appearance and performance evaluation after aging
  3. Component analysis
    Principal component qualitative analysis; full component qualitative analysis; full component quantitative analysis; ash content
  4. Reliability
    Temperature and humidity cycle; temperature shock; waterproof and dustproof; vibration test

Current relevant standards for adhesives

  1. GB 18581-2009 Limits of Hazardous Substances in Solvent-Based Wood Coatings for Interior Decoration Materials
  2. GB/T 2791-1995 Adhesive T peel strength test method flexible material to flexible material
  3. GB/T 27934.3-2011 Process control and testing methods for lamination of paper printed matter
  4. GB/T 2794-2013 Determination of Adhesive Viscosity Single Cylinder Rotational Viscometer Method
  5. GB/T 16585-1996 Vulcanized rubber artificial weathering (fluorescent ultraviolet lamp) test method
  6. GB/T 7124-2008 Adhesive Shear Strength
  7. ASTM D 1781-1998 Adhesive Roller Peel Test Method

Adhesives are widely used in various fields of the national economy and have become indispensable for the development of the national economy due to their advantages of realizing the connection of the same or dissimilar materials, no stress concentration at the joint, high bonding strength, and easy to realize automatic chemical operation. chemical products.

What is the above ie adhesive? What are the main physical properties and testing standards of adhesives? For more information about adhesives, log in to the Thermal Adhesives Network (www.coolthermo.com) to inquire!

What is the role of electronic potting compound? Why do electronic products use potting glue for potting protection?

With the vigorous development of the electronic industry, people pay more attention to the stability of products, and have more stringent requirements for the weather resistance of electronic products. Therefore, more and more electronic products now need to be potted, and the potted electronic products can enhance their performance. Waterproof ability, shock resistance and heat dissipation performance, protect electronic products from the erosion of natural environment and prolong their service life. Today, CoolThermo will explain to you what is the role of electronic potting glue? Why do electronic products use potting glue for potting protection?

Electronic potting glue can strengthen the integrity of electronic devices, improve the resistance to external shock and vibration; improve the insulation properties between internal components and lines, which is conducive to the miniaturization and light weight of devices; avoid direct exposure of components and lines, and improve the device waterproof and moisture-proof performance. It has been widely used in the manufacturing of electronic devices and is an indispensable and important insulating material in the electronic industry.

With the rapid development of electronic products, the precision of electronic products is also continuously improved, which can easily cause the junction temperature of electronic components to overheat, cause electronic products to malfunction, and affect the service life of electronic products. In order to solve this situation, manufacturers generally pour electronic potting glue into electronic products as a thermal conductive material to efficiently conduct the temperature inside the electronic product to the heat dissipation shell, thereby improving the heat dissipation capacity of the electronic product. It can be seen that one of the reasons for the use of potting glue in electronic products is that in addition to the shock resistance of the cured package, it must also have good thermal conductivity and heat resistance.

It is worth mentioning that the use of potting glue for electronic products is because the potting glue has excellent performance characteristics during the potting process and after it is fully cured. When potting, the viscosity is small, the impregnation is strong, and it can be filled with components and caulking. The glue of each component is easy to store and has a long pot life. It is suitable for large-scale automatic production line operations. During the curing process, the powder components such as fillers settle very quickly. Small and not layered. After complete curing, it has the properties of flame retardant, weather resistance, thermal conductivity, high and low temperature resistance, waterproof and so on. The cured product has excellent electrical and mechanical properties, good heat resistance, low water absorption and linear expansion coefficient.

The waterproof function in the performance of potting glue can be effectively reflected in some electronic products. For example, in the process of washing clothes, electronic products such as mobile phones are more likely to slip into the water. etc. The injury is undoubtedly fatal while filling the electronic potting compound. It can prevent moisture from entering the battery, memory, and motherboard. Of course, there are differences in the waterproof performance of different brands of electronic potting compounds, so it is very important to buy high-quality electronic potting compounds. Solutions, the strength is trustworthy.

Electronic products are sometimes used in environments with relatively large vibrations, and electronic potting compounds have good elasticity, which can effectively improve the shock resistance of electronic products. In a relatively large vibration environment, electronic products still maintain good performance. Electronic potting glue not only has the functions mentioned above, but also has the functions of dustproof and heat dissipation. This ensures that the electronic product is used in an excellent environment, which is very helpful for extending the service life of the electronic product.

What is the function of the above electronic potting glue? Why do electronic products use potting glue for potting protection? For more information about potting adhesives, please visit www.coolthermo.com to view!

What are condensation and addition silicone potting compounds? What is the difference between the two?

Silicone potting adhesives are divided into one-component and two-component potting adhesives according to the main materials and additives, and can be divided into condensation-type and addition-type potting adhesives according to the curing reaction. So today let’s talk about what are condensation and addition silicone potting compounds? What is the difference between the two?

Under normal circumstances, the potting compounds for waterproofing are condensed, and the addition-type potting compounds are generally used for thermally conductive potting. Condensation type potting glue shrinks greatly, at the same time will release a certain amount of alcohol, and the curing time is also very long, so the addition type is more environmentally friendly, the addition type potting glue can be food-grade, and can be cured at room temperature cured.

What is a silicone condensation potting compound?

Silicone condensation type potting compound is a kind of silicone rubber that is cured by moisture in the air and mixed catalyst. The curing time mainly depends on the amount of catalyst. The more the amount of catalyst, the faster the curing speed. However, shrinkage and by-products are released during curing.

Compared with the traditional condensation-type potting silicone rubber, the addition type silicone potting compound has no small molecular by-products in the vulcanization process, the cross-linking structure is easy to control, the shrinkage rate of the vulcanized product is small, and the product process performance is superior. It can be vulcanized at room temperature, and it can be vulcanized under heating conditions, and it can be quickly vulcanized in deep layers. The product has good processing performance, low viscosity, good fluidity, can be poured, can be pumped and statically mixed, and has the advantages of simplified process, fast, high efficiency and energy saving The advantages. Therefore, it has developed rapidly since its emergence, and there is a trend to replace condensed silicone potting materials.

What is a silicone addition type potting compound?

Addition type potting compounds are cured with a curing agent, and no by-products are produced during the curing process. Once the curing agent is added, they will cure on their own, even in an airtight container, and do not require exposure to the atmosphere to do so. The silicone two-component addition type potting compound can be cured at room temperature. If necessary, the curing speed can be accelerated by heating, and will not have any adverse effect on the cured colloid. One-part addition silicones usually require heat to cure.

It is also important to note that uncured compounds should avoid contact with the following chemicals during mixing or production: nitrogen, sulfur, phosphorus, arsenic, organotin curing agents, stabilizers, epoxy curing agents, vulcanized rubber and condensed silicone , otherwise it will inhibit curing and lead to incomplete curing.

Silicone addition potting compounds also require a good chemical balance to achieve the proper physical properties of the cured colloid. Therefore, both components should be thoroughly mixed before weighing out. At the same time, the correct mixing ratio is also very important. Mixing of two different batches of compounds is not recommended as they are usually produced in sets.

The Difference Between Condensation and Addition Silicone Potting Compounds

Firstly. Curing depth

After the two components of the addition type potting glue are mixed evenly, the glue is poured, and the curing process is consistent as a whole, that is to say, the thicker the glue is, the thicker the overall curing is. Moisture participates in the reaction, curing is carried out from the surface to the interior, and the curing depth is related to moisture and time, so in application, it is generally not suitable for condensation-type potting compounds to fill or encapsulate products with deep or thick thickness.

Secondly. heating application

Increasing the curing speed of the silicone potting compound can improve the production efficiency, so many users increase the baking process, which greatly speeds up the time of the next process, but this process is only suitable for the use of the addition type silicone potting compound, and the condensation type The curing of the encapsulant requires two key conditions, namely moisture and catalyst, which have no obvious relationship with temperature.

Thirdly. the adhesive properties

When the silicone potting compound needs to have certain adhesive properties during the application process, the condensed silicone potting compound is preferred, which has good bonding properties with most materials and will not have edge debonding. Phenomenon, the addition type of silicone is slightly worse.

In addition to the above differences, for example, condensed silicone encapsulant is stronger than addition type in terms of anti-toxicity; for food-related applications, addition type is selected, and there is no molecular volatilization. If you need to further explain the application selection and application problems between the two in detail, please leave a message to Nuofeng NFION, and we will definitely answer it for you.

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