Can white oil be added to the potting compound? What are the effects of white oil-doped silicone electronic potting compounds?

The price of silicone electronic potting glue in the market is high and low, and the price of some electronic potting glue is far lower than the average market price. Why? Is their technology advanced and can effectively control production costs? In fact, the reason is that they add low-cost white oil to the potting compound material, which controls costs and disrupts the market.

What is white oil?

White oil, also called white mineral oil, is a special deep-refined mineral oil. Transparent, colorless, odorless, chemically inert, the basic substances are saturated hydrocarbons, aromatic hydrocarbons, etc., and the molecular weight is usually between 250 and 450. The boiling point is generally within 150 °C. It is widely used in daily chemical, pharmaceutical, food, rubber and plastic, agriculture and other industries.

Why does adding white oil reduce production costs?

Because the price of white oil is relatively low. For example, the general market price of silicone oil is 30 yuan/kg, while the price of white oil is only 10 yuan/kg. On the premise of ensuring the acceptance quality of electronic potting glue, 20% white oil can be added, then doping The glue cost of white oil is 26 yuan/kg. In this way, by adding an appropriate proportion of white oil, the price of electronic potting glue can be reduced and the potting glue market can be seized.

What is the effect of electronic potting compounds with added white oil?

We know that silicone oil is a polymer material with a siloxane structure and has organic and inorganic properties, while white oil is an organic polymer with a carbon structure and has no inorganic properties. Since white oil is chemically inert, it does not participate in the cross-linking reaction of organic silica gel.

When the silicone is cured, the free white oil slowly seeps out of the glue. Once the electronic potting compound doped with white oil is used on electronic products such as driving power supply, the following situations may occur:

  1. Various physical properties are poor, such as tensile strength and tear strength will decrease;
  2. The ability of heat dissipation and flame retardancy is poor, and it is difficult to effectively improve the heat dissipation capacity and safety factor of electronic products, which is prone to accidents;
  3. Poor high and low temperature resistance, poor weather resistance, and easy cracking of the colloid, allowing rainwater to penetrate into the electronic components from the cracks, reducing the moisture-proof ability of electronic products, and causing electronic components to fail;
  4. The electrical performance and insulation ability are poor, which affects the anti-electromagnetic interference ability of electronic components after potting, and is prone to failure.

How to detect whether white oil is added to electronic potting compound?

Since the boiling point of white oil is relatively low, less than 150 °C, and the boiling point of silicone oil is around 200 °C, the simple method in the laboratory is to test the volatile content of the uncured or cured potting compound. The test method is: oven at 150 °C After baking for 3 hours, the weight difference after volatilization was measured. The volatile matter of normal electronic potting glue is less than 1%, and the volatile matter of added white oil is greater than 5%. When the volatile content is abnormally high, it can be judged that white oil is added to the electronic potting compound.

In short, when we choose electronic potting glue, we can’t blindly covet cheap prices, we must consider the comprehensive selection of product quality and company services.

Which Kind Of Potting Compound Is Good For Pouring On Electronic Components?

With the rapid development of electronic products, the precision of electronic products has been continuously improved, and many electronic components will generate a lot of heat during use. If this heat is not dissipated in time, it is easy to cause high temperature and overheating of electronic components, resulting in failure and affecting electronic and electrical products. service life.

Therefore, efficient heat dissipation has become the focus of the design, especially on chip processors, LEDs, and power packs. In order to solve this problem, electronic thermal conductive potting compound is generally poured into electronic products as a thermal conductive material, so as to efficiently conduct the heat inside the electronic product to the heat dissipation shell, thereby improving the safety and service life of the electronic product.

There are generally three kinds of potting compounds suitable for pouring on electronic components, namely: epoxy resin potting compound, polyurethane material potting glue and silicone material potting glue (here we call it electronic thermal conductivity potting). Plastic closures). Among them, the most suitable for potting in electronic products is silicone potting compound, because other materials have some unavoidable defects.

The potting compound of epoxy resin material has weak resistance to cold and heat changes. Once it is impacted by cold and heat, the colloid will crack, and moisture such as rainwater and condensation will easily penetrate into the electronic components through the cracks, resulting in electronic components. The device is disconnected, which seriously affects the use of electronic products. Polyurethane potting glue, because of its high toxicity, is easy to cause allergic symptoms, so it is necessary to pay great attention to the production and production.

The silicone-based potting compound has excellent electrical properties and insulating properties. It can be used in electronic components to ensure that the components will not interfere with each other, which can effectively improve the stability of electronic products, and can also play a role in thermal conductivity and flame retardant. , Waterproof and shockproof.

Under normal circumstances, the indicators for measuring electronic thermal conductive potting compounds mainly include the following aspects:

Firstly: Thermodynamic properties – thermal conductivity

Thermal conductivity is an important parameter to measure the thermal conductivity of thermally conductive materials. The higher the thermal conductivity, the better the thermal conductivity and heat dissipation effect, and the heat generated by the components can be quickly dissipated. When other conditions are constant, the higher the thermal conductivity, the better the electronic thermal conductive thermal potting compound.

Secondly: Electrical Properties – Dielectric Strength, Volume Resistivity and Dielectric Constant

Of the three properties of interest are dielectric strength (sometimes also expressed in terms of breakdown voltage) and volume resistivity.

Dielectric strength is a measure of the electrical strength of a material as an insulator. It is defined as the maximum voltage a unit thickness can withstand when a specimen is broken down, expressed as volts per unit thickness. The greater the dielectric strength of a substance, the better its quality as an insulator.

Volume resistivity is the resistance of a material to current per unit volume, which is used to characterize the electrical properties of a material. Generally, the higher the volume resistivity, the higher the effectiveness of the material as an electrically insulating component.

The dielectric constant is used to measure the ability to interfere in electromagnetic fields.

Thirdly: Physical properties – fluidity, density and adhesion

Because the electronic thermal conductive potting compound is fluid, it has a certain fluidity, and the popular thermal potting compound can be used to fill the gap with smaller pores and increase the volume of the thermal conduction and heat dissipation contact surface.

Density (specific gravity) is also an indicator of special concern for electronic thermal conductive potting compounds. Generally, under the same thermal conductivity, the lower the specific gravity, the better. The lower the proportion, it is used in industries such as automotive power supply, which can effectively improve energy efficiency.

The electronic thermal conductive potting compound has a certain viscosity, which can firmly bond the heating device and the heat sink together, so the viscosity is also an important indicator to consider the performance of the thermal conductive electronic potting compound.

What is Silicone Adhesive?

What Is Silicone Adhesive?

Silicone adhesive is a kind of special adhesive, which is composed of high molecular weight linear polysiloxane mixed with filler and other additives. According to the curing temperature, it can be divided into three categories: high temperature curing, room temperature curing and low temperature curing. Among them, the room temperature curing type is composed of polysiloxane containing terminal hydroxyl groups with fillers, crosslinking agents and other additives. It is simple to operate, easy to use, and has high bonding strength. Due to its excellent properties such as high temperature resistance, low temperature resistance, insulation, waterproof and weather resistance, it is widely used in spacecraft, aircraft manufacturing, electrical and electronic component manufacturing, construction, medical and health care, etc.

Introduction to the characteristics of silicone adhesives

  1. Single component, easy to use;
  2. Applicable to different vulcanization processes (plate vulcanization, vacuum vulcanization, injection machine vulcanization);
  3. Strong activity, high bonding strength, good high temperature resistance, no toxic ingredients;
  4. It has high modulus, impact resistance, vibration resistance, strong activity, high bonding strength, good high temperature resistance, good thermal stability, UV resistance; ozone resistance to chemical media, moisture resistance, weather resistance (ozone, sunlight), resistance to Chemical (acids, alkalis, oils), resistance to biological (fungal) attack, excellent electrical properties and other properties, no toxic ingredients.

The main function of silicone adhesives is to be used as glue for bonding silicone/rubber materials. Then, what main uses can silicone rubber adhesives be used in various industries?

  1. Industrial applications in electronic appliances.

Because silicone rubber has good electrical properties, and the temperature change has little effect on electrical properties, and has waterproof, moisture-proof and sealing properties, it is ideal for coating, encapsulation, pouring, casting, and horizontal plastics for electronic and electrical components. Material.

  1. Application in construction industry.

It has good adhesion and weather resistance to building materials, so it can glue and seal door and window glass, tunnels, subways, porcelain anvils, stones, cement, metal frames, etc. The application effect is good, but due to the high domestic cost, it is not suitable for large-scale use.

  1. Applications in aerospace and aircraft manufacturing.

Due to the excellent high temperature resistance and low temperature performance of room temperature vulcanized silicone rubber, it is used as an adhesive seal in aircraft doors and windows, space navigation observation windows, etc. Glass glued.

In addition, silicone rubber adhesives are also widely used in the automotive industry, shipbuilding industry, etc., especially in the “sewing” that can be used in medical equipment, human organ surgery, etc.

What is sealant? What are the types of sealants? Classification of sealants

What is sealant?

Sealant refers to a sealing material that deforms with the shape of the sealing surface, is not easy to flow, and has a certain adhesiveness. It is an adhesive used to fill configuration gaps for sealing. It has the functions of anti-leakage, waterproof, anti-vibration, sound insulation and heat insulation.

Classification of sealants

One. Classification by sealant base material

Rubber type: This type of sealant is based on rubber, and commonly used rubbers include polysulfide rubber, silicone rubber, polyurethane rubber, neoprene rubber and butyl rubber.

Resin type: This type of sealant is based on resin, and commonly used resins include epoxy resin, phenolic resin, polyacrylic resin, unsaturated polyester resin, polyvinyl chloride resin, etc.

Oil-based type: This type of sealant is based on oil, and the commonly used oils are various vegetable oils (such as linseed oil, castor oil, and tung oil, and animal oil, etc.).

Two. Classification by sealant vulcanization method

Wet air vulcanized sealant: This type of sealant is vulcanized with moisture in the air, and it mainly includes one-component polyurethane, silicone rubber and polysulfide rubber. The polymer base material contains active groups, which can react with water in the air to form cross-linking bonds, so that the sealant is vulcanized into a network structure.

Chemical vulcanization sealants: Two-component polyurethane, silicone rubber, polysulfide rubber, neoprene and epoxy resin sealants belong to this category, and are generally cured at room temperature; some one-component chlorosulfone Polyethylene and neoprene sealants and polyvinyl chloride sol paste sealants must be vulcanized by chemical reaction under heating conditions.

Heat transfer sealant: PVC resin dispersed with plasticizer, and sealant with bitumen-containing rubber are two different types of heat transfer systems. Vinyl plasticizers are liquid suspensions at room temperature and harden by heating to solidify, while rubber-asphalt sealants are hot-melt.

Oxidation-hardening sealant: Surface-drying sealant for inlaying or mounting glass, based on dry or semi-dry vegetable or animal oils, which may be refined polymerized, blown or chemically modified.

Solvent volatilization coagulation type sealant: sealant based on non-viscous polymer after solvent volatilization. This type of sealant mainly includes butyl rubber, high molecular weight polyisobutylene, acrylate with a certain degree of polymerization, chlorosulfonated polyethylene And sealants such as neoprene.

Three. According to the performance of sealant after construction

Curing sealant: It can be divided into two types: rigid sealant and flexible sealant;

a) Rigid sealants form hard solids after vulcanization or solidification, and rarely have elasticity; some varieties of such sealants play both sealing and bonding functions, and their representative sealants are epoxy resin, polyester resin Resin-based sealants such as polyacrylates, polyamides and polyvinyl acetate.

b) Flexible sealants remain soft after vulcanization, and they are generally based on rubber elastomers; the flexibility varies greatly, and the hardness is in the range of 10 to 80. Some varieties of this type of sealant are pure rubber, and most of them have good adhesive properties.

Non-curing sealant: This type of sealant is a soft setting sealant that remains non-drying after construction. Usually a paste, it can be applied to the joint with a scraper or a brush, and many sealants of different viscosities and different properties can be formulated.

Four. Classification by sealant form

Paste sealant: This type of sealant is basically used in static joints, and the service life is generally 2 years or more. Three main materials are usually used: oil and resin, polybutene, and asphalt.

Liquid Elastomeric Sealants: Includes liquid polymers that vulcanize to a true elastic state, which have the ability to withstand repeated seam deformation. The polymer elastomers used in elastomer sealants include liquid polysulfide rubber, mercapto-terminated polypropylene ether, liquid polyurethane, room temperature vulcanized silicone rubber, low molecular weight butyl rubber, etc.​

Hot melt sealant: Hot melt sealant, also known as thermal construction sealant, refers to a sealant based on a blend of elastomer and thermoplastic resin. This type of sealant is usually extruded directly into the seam through a certain mouth model under heating (150 ~ 200 ℃); thermal construction can improve the wetting ability of the sealant to the bonded base material, so it is suitable for most bonded bases. The material has good adhesion. Once in place, it cools to form or form a film into a strong elastomer with little shrinkage. The main materials of thermal construction sealants are mainly isobutylene polymers, EPDM rubber and thermoplastic styrene block copolymers.

Liquid sealant: This type of sealant is mainly used for the sealing of mechanical joint surfaces to replace solid sealing materials, namely solid gaskets, to prevent the leakage of mechanical internal fluids from joint surfaces. This type of sealant is usually made of polymer materials such as rubber, resin, etc. as the main material, together with fillers and other components. Liquid sealants are usually divided into four categories: non-drying adhesive type, semi-drying viscoelasticity, dry adhesion type and dry peelable type.

Why Thermal Potting Compounds Do Not Cure?

The main function of thermal potting compound (also known as “ab glue”) is to strengthen the overall performance of electronic components, improve practicability, enhance resistance to external shocks, and achieve the purpose of safe use and enhanced service life. thermal potting compound is a liquid glue with fluidity. After normal curing, it isolates dust, moisture, moisture, etc., can withstand changes in high and low temperature, and protect components to work stably. Once it cannot be cured normally, it must be solved immediately.

The non-curing of silicone encapsulant is divided into internal and external causes. Once this type of adhesive does not cure, it will not be able to effectively play the role of waterproof, moisture-proof and insulation in electronic products.

The internal cause of the non-curing of the potting compound

The bond strength of solvent-based adhesives is affected by the amount of residual solvent in the adhesive layer. When the amount of solvent is large, although the wettability is good, the cohesive strength of the adhesive decreases because the cohesive force of the adhesive decreases. When the affinity between the adhesive polymers is large, the adhesive strength increases with the volatilization of the solvent. When there is no affinity between the two, the adhesiveness of the adhesive is relatively large when some solvent is left, and the strength decreases with the volatilization of the solvent.

The external cause of the encapsulant not curing

  1. When the two-component potting compound is proportioned, the electronic scale is not accurate enough, resulting in the incorrect content of AB agent. When the A agent is too much and the B agent content is small, it cannot be cured normally.
  2. There is no stirring before use, or there is no layering of pigments and fillers during storage, resulting in curing failure.
  3. The curing time is not long enough, and the next step is carried out in a hurry.
  4. After opening, the airtightness is not good, resulting in moisture absorption and crystallization.
  5. Changes in ambient temperature lead to changes in the curing speed and fluidity of the adhesive; if the curing temperature is too low, the adhesive cannot be cured for a long time. Especially in winter, the temperature is lower and the curing time needs to be extended.
  6. Apparent curing failure affected by the treatment of bubbles on the surface of the cured product.
  7. Light-colored cured products will change in color due to the influence of curing temperature, ultraviolet light and other conditions.
  8. Various changes in the effect of curing temperature changes on the curing properties of materials.
  9. The operators of the adhesive potting glue may not design accelerated destructive aging life experiments according to the characteristics of the glue and the needs of electrical products.
  10. The adhesive has expired. After the expiration date, it may undergo qualitative changes and cannot be used normally. Check the expiration date before using and don’t use expired products.

How to solve the problem of not curing?

  1. Regularly calibrate the electronic scale, accurately weigh the AB agent, and stir evenly.
  2. After winter, the adhesive can be preheated or cured by heating.
  3. Arrange the adhesive according to the length of the shelf life, and use up the products that are about to expire to avoid waste.
  4. Keep the working environment safe and keep away from products that will react with silicone potting compounds.
  5. Store in accordance with the instructions in the manual and maintain good ventilation conditions.

In addition, every time the silicone potting compound is used, the material should be stirred evenly. Curing is a step-by-step process that will only become stronger until the surface and interior are fully cured.

What is the difference between sealant and general-purpose sealant?

Both sealant and general-purpose sealant have bonding function. Although both are glues, they are very different. They are mainly reflected in the following aspects. Let’s take a look!

Product structure is different

Sealant: often based on dry or non-dry viscous materials such as asphalt, natural resin/rubber or synthetic resin/rubber, combined with inert materials such as carbon black, titanium dioxide and talc, and then adding curing agent, Accelerators, etc.

General-purpose sealant: the main components are water-soluble sodium silicate and acetic acid and organic silicone.

Different application areas

Sealant: The first purpose of sealant is bonding and sealing, and it is often used in the sealing of construction, transportation, electronic instruments and parts.

General-purpose sealant: mainly used for bonding glass, bonding various glass with other materials, it is the core of building materials, mainly used for waterproof and moisture-proof exterior wall, indoor bathroom anti-mildew, flame retardant, high and low temperature resistance, etc. multiple uses. It is also widely used in home decoration, such as: sanitary ware, toilets, cosmetic mirrors in the bathroom, and the back of the wooden line.

Product works differently

Sealant: easy to flow, seal, and have certain adhesiveness. It is used to fill the configuration gap to achieve a sealing effect. It has the functions of anti-leakage, waterproof, anti-vibration, sound insulation and heat insulation, and has certain anti-aging properties. It has high bonding strength and good weather resistance.

General-purpose sealant: It dries quickly, has a heavy sour taste, is not environmentally friendly, and has poor anti-aging properties, but it will not corrode objects and has strong adhesion.

Obviously, the difference between sealant and glass glue is still very big. Only by understanding the characteristics and uses of sealant and glass can we better choose the appropriate sealant or general-purpose sealant.

What is AB glue? Introduction to the classification, characteristics and use of AB glue

What is AB glue

AB glue is another name for two-liquid mixed hardening glue. One liquid is the glue and the other is the hardener. The two liquids can be hardened when they are mixed. It does not need to be hardened by temperature, so it is a kind of room temperature hardening glue.

AB glue is a two-component adhesive with high transparency. After curing, the adhesive is perfect without traces, without heating, can be cured at room temperature, environmentally friendly and non-toxic; high bonding strength, good toughness, oil resistance, water resistance and many other advantages; cured product It has good electrical and physical properties such as good insulation, compression resistance and low shrinkage.

Classification and characteristics of AB glue

The types of AB glue can be distinguished according to the raw materials used, which can be divided into silicone AB glue, polyurethane AB glue, acrylic AB glue, epoxy resin AB glue, etc. The main functions are bonding, sealing, potting, etc., different types There is a big difference in the performance of the AB glue, and the applicable process is also very different.

Silicone AB glue: The main raw material is silicone rubber, which can conduct heat and has good insulation and sealing effect. It is mainly used for potting. Such as potting of LED modules, potting of LED lamps, potting of electronic parts, etc. The material of silicone AB glue is soft after curing. There are two forms of solid silicone rubber product and silicone gel, which can eliminate most of the mechanical stress and play a shock absorption protection effect. Physical and chemical properties are stable, with good high and low temperature resistance, and can work for a long time in the range of -50~200 °C. Excellent weather resistance, can still play a good protective role outdoors for more than 20 years, and is not easy to yellow. The mixing ratio is not fixed, there are 10:1, 2:1, 1:1, etc.

Polyurethane AB glue: The main raw material is polyurethane, which is mainly used for potting, coating, etc. Due to its advantages of adjustable performance and wide application range, it has become a product with many varieties and large output in polyurethane glue.

Acrylic AB glue: The main raw material is acrylate, mostly in a 1:1 mixing ratio, room temperature curing, fast curing, most acrylic AB glue positioning time is 3-5 minutes, hard and tough after curing, impact resistance and shock resistance Excellent dynamic performance. The main function is bonding, and it has good bonding strength to metal, hard plastic, wood, stone, ceramics, etc. Note: This type of AB glue is not good for copper, electroplated cadmium materials, PP, PE and Teflon, and has a strong smell.

Epoxy resin AB glue: The main raw material is epoxy resin, most of which are colorless and transparent, room temperature curing, high hardness, toughness is not as good as acrylic AB glue, but the hardness is higher than it. The materials that can be bonded are also very wide. The epoxy resin AB glue that the acrylic AB glue can stick can also be bonded, and the initial curing time of the epoxy resin AB glue is more detailed, and the operation time is relatively long, which can be suitable for more bonding process. However, the viscosity of epoxy resin AB glue is greatly affected by temperature, so there is no easy control of acrylate AB glue in the process. In addition to good bonding performance, epoxy resin AB glue can also be used for potting, especially for the potting of electronic parts with high confidentiality requirements, epoxy resin AB glue is used.

How to use AB glue

  1. First of all, the surface of the object to be bonded must be clean, smooth and dry. If necessary, treat the surface according to the actual situation, such as polishing or using a treatment agent.
  2. Mix components A and B according to a certain proportion and stir evenly, and apply them to the surface of the adherend.
  3. Please wear isolation gloves when operating. In case of contact with skin or eyes, rinse immediately with water or seek medical attention.
  4. The products after bonding should be processed according to the requirements of bonding, so as not to affect the effect.
  5. If the AB glue is thick, it is a normal phenomenon and does not affect the bonding effect.
  6. When using in batches, please do a test first. Avoid affecting the bonding effect due to improper operation.

What Should i Pay Attention To When Applying Sealant?

In daily life, the application of sealant is very common. In the construction process, how to make a sealant with bright surface, uniform thickness and good sealing? For a good construction effect, in addition to purchasing a good sealant, you must have the correct glue tools and master the correct construction process.

First, The glue tool

  1. The glue gun is an indispensable tool in the glue process. Put the sealant with the cut nozzle into the glue gun, and push the handle to the bottom of the sealant to fix it.
  2. There are various thicknesses of textured paper, which are suitable for different occasions and can be found in stationery stores or hardware stores. In preparation for gluing, use masking paper to leave the distance for the final strip, and immediately tear off the masking paper after gluing and smoothing the surface. Using textured paper can not only help you print the right width, but also protect the surrounding substrate.
  3. Cut the glue nozzle obliquely, so that the glue nozzle forms an inclined surface glue outlet that is basically the same as the glue width.
  4. The scraper has a variety of different angles, such as right angle, outer rounded corner, inner rounded corner, bevel and so on. Choose the shape of the strip you want, use a spatula to scrape off any excess sealant after gluing, and you’ll have a smooth, shiny finish in no time.

These are the most basic glue tools. Of course, in addition to this, you can also use brushes, cleaners, foam wands and other tools in different environments.

Second, the construction process

How should the substrate surface be treated prior to sealing?

The area of the substrate that the sealant contacts must be kept clean, dry and free from dust, dirt, rust, grease and other contaminants. Non-porous substrates must be cleaned with a clean white lint-free cotton cloth and solvent. Wipe off residual solvent with a clean dry cloth as soon as possible before it evaporates. Before applying glue, cut the nozzle of the cartridge, then install the nozzle, and cut the nozzle to the desired size. The sealant can be applied in dots or layers and requires exposure to moisture in the air to cure.

What should be paid attention to when applying glue?

  1. Before use, be sure to clean the substrate surface so as not to affect its sealing effect. If the substrate surface is uneven, or there are problems such as deformation, the substrate surface needs to be repaired and other treatments to ensure the smoothness of the substrate surface.
  2. When applying glue, you need to choose the appropriate construction method and construction tools according to the object to be pasted. If you only apply a small amount of sealant, you can use a brush and other tools to apply it manually. If you want to apply a lot, you can use a spray gun, etc. tool to spray, so that you can have a better coating effect.
  3. When smearing, the sealant should be applied evenly. If the cured glue is of different heights, there will be certain gaps, and it is easy to hide dirt and dirt, which will affect its bonding effect to a certain extent.
  4. After the sealant is applied, the excess glue needs to be trimmed to ensure the aesthetics of the material. Be careful not to peel off the entire adhesive layer when trimming.

The above is an analysis of the matters that need to be paid attention to when using sealant. In addition to purchasing a good sealant, it is necessary to have the correct gluing tools and master the correct construction process and precautions in order to achieve a good gluing effect. .

What Are The Reasons For The Unevenness Of Silicone Adhesive Sealants After Curing?

The functions of silicone adhesive sealants mainly include applications such as bonding, fixing, filling and sealing between materials, and most applications that have special requirements on the surface after curing are filling and protection, and the general requirement is smoothness. For example, in the lighting industry, if If the surface is not flat, the light generated will change, so what happens to the uneven surface after the silicone adhesive sealant is cured? What are the reasons for this problem, CoolThermo Technology will share with you according to the actual application case.

Displacement/Vibration

When silicone adhesive sealant is used to fill and seal fixed components or other components, it must be ensured that the bottom is completely filled with glue after filling, because during the curing process, the bottom glue still has a certain fluidity due to the long curing time. The structural problem is not filled. When the surface is crusted and dried, the glue at the bottom will be displaced, which will cause the surface to be uneven after the glue is cured. In addition, the filled product should try to avoid collision and vibration.

Thickness

The silicone adhesive sealant is used for filling. If the sizing is too thin, the curing process is also the process of the volume change of the glue, and there will be a certain shrinkage rate and internal stress. The hardness of the silicone adhesive sealant itself is low, plus If the glue is too thin, it may cause shrinkage and wrinkling. Increasing the filling thickness can effectively solve this problem.

To sum up, what should I do if the surface is uneven after the silicone adhesive sealant is filled and cured? In fact, it is very easy to solve. Reapply a layer of glue on the surface to fill in the uneven surface. Before rework, confirm whether the glue has been deeply cured and completely before applying glue.

Can Silicone Adhesive Sealants Be Used For Plastic Bonding? What Are The Reasons Why Silicone Adhesives Are Not Sticky To Plastics?

Recently, a customer asked on the official website of CoolThermo Technology whether silicone adhesive sealant can be used for plastic bonding? The answer is yes. Silicone bonding sealants are adhesives for silicone materials that can bond metals, plastics, rubber, glass ceramics and other materials. Widely used in aerospace, aircraft manufacturing, electronic industry, machining, automobile manufacturing, construction, medical and so on.

What is the reason why silicone adhesives are not sticky to plastics?

Silicone adhesive sealant does not stick to plastic mainly because it has no adhesion, peeling off the colloid, no glue residue on the plastic, or little glue residue locally. If the application of silicone adhesive sealant is in a non-adherent state, the function that can be exerted will be greatly weakened, and in severe cases, there will be no application performance. So what are the reasons why silicone adhesive sealants are not sticky to plastics? Today, NFION will explain to you the following.

Substrate contamination

One of the key factors for the adhesion of silicone adhesive sealants is the adhesive area. The smaller the adhesive area, the smaller the corresponding adhesion. For example, during the storage process of the product, it is affected by dust and moisture in the air. The contamination of the adhesive will cause the bonding surface to be unclean. When the adhesive is used for bonding, the actual bonding surface of the adhesive in contact with the material is greatly reduced. In severe cases, it may not stick at all, so silicone bonding is used. Before glueing, it is necessary to check the cleanliness of the plastic surface or the storage process to ensure the cleanliness.

Material problem

Everyone should know that common plastics include PC, ABS, PVC, PP, PE, etc. If these plastics are involved in excessive waste in the production process, resulting in impure components, some components are analyzed, residual or seepage on the surface of the plastic, As a result, when using silicone to bond the sealant, the glue cannot contact the surface of the material. This is the possible reason why the same type of glue has good adhesion sometimes at the user’s place, and sometimes not at all. In fact, the comparison and verification method is relatively simple. Use alcohol to treat the surface, and then apply glue after the alcohol evaporates, and then you can know the effect.

Selection problem

Silicone adhesive sealants are classified into dealcoholization type, deoxime type, deacidification type, deacetone type, etc. by type. Each type of silicone adhesive sealant has different adhesion to different plastics. Therefore, when you choose to use silicone adhesive sealants, you must make accurate selections according to your own plastic materials. After choosing a good product, the precautions for use are very critical, such as the environment and the curing state, which will affect the adhesion.

CoolThermo Technology has been engaged in adhesive products for the electronic industry for more than ten years. It has rich experience in performance research, application solutions, industry positioning, etc. of silicone adhesive sealants. Share learning.

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