Common problems with silicone and other materials bonding

Because the silicone material with good resistance to high and low temperature performance, can maintain between ℃ to 60 ℃ - 300 good stability, but also has excellent electrical insulation, weather resistance, resistance to ultraviolet ozone, and high permeability, and high transparency, and high tear strength, and good liquidity, easy to processing molding, etc, gradually replacing the rubber and plastic in many applications.At present, silica gel is widely used in automobile, electronics, construction and daily necessities.

Below to explain the silicone products in the production and processing process and other materials often encountered problems of adhesion.Generally speaking, the operation personnel, machine, base material, operation method and operation link are related to the bonding effect.

Generally, adhesives on the market (also known as: treating agent, interface agent, primer, glue, viscosity enhancer, backglue, etc.) are basically divided into two types: quick-drying type and slow-drying type or high-temperature bonding and normal temperature bonding.

Quick-drying type is generally applied with silicone primer and instant glue.It widely used in the silicone adhesive metal (carbon steel, stainless steel, copper, aluminum, and it has a coating of metal silicon (ABS/PC/PVC/PP/PPE/TPU/PPS/PBT/PET/PA/PMMA/PPS/CAB, etc.), silicone adhesive acrylic, silicone adhesive rubber, silicone adhesive ceramic, silicone adhesive bakelite, silicone adhesive material such as fabric.For silicone metal bonding, the direct effect can only achieve the bonding firm effect, but can not withstand the requirements of too high, such as factory time resistance to high temperature and pressure, water boiling, salt spray, and ultraviolet ozone resistance test.But for silicone adhesive plastic, glue model is quite a lot, the most typical representative is P+R mobile phone keys.Are generally using silicone adhesive PC/ABA/PC and BAS/TPU material mixture, first started in this field is South Korea loctite 770 series treating agent is developed, with instant glue good solves the silica gel and plastic adhesive can't give such as resistance to high temperature and high pressure water salt fog test (test the length of time is relative, the original mobile phone do better).Silicone bonded silica gel also has the above problems.In addition, it needs to be noted that no matter silicone bonded metal, silicone bonded plastic, silicone bonded silicone or silicone bonded material, there will be hardening and whitening phenomenon.

Hardening refers to the silica gel and the bonding surface of the silica gel lost more elasticity and toughness, hardening, but the applicable glue is not the same degree of hardening.Whitening is specific to different treatment agents.Therefore, we need to choose our own treatment agent and quick-drying glue according to the requirements during production.

The other is the hot curing of silicone and other materials after bonding.That is to say, when forming silica gel to bond metal/plastic/silica gel, after coating the glue, after heating, so that the glue quickly curing.The heating temperature varies according to the glue, the curing time is different, and the bonding effect is also different.On the market, some products need to be prevented from curing by heated glue for a period of time (generally 12 hours to maximize the bonding effect), while others can be cured quickly by heated glue and achieve the highest bonding effect.The kl-301a /B developed by connebon technology co., ltd. has this feature and absolutely no smell at all.For some products with high requirements (high temperature and pressure resistance, ultraviolet ozone resistance, etc.), mass production can be achieved quickly, avoiding many inconvenience caused by slow drying process, such as rebound, dislocation, and saving large area of production site, which can effectively reduce the production cost of customers.Another aspect is the silicone and other materials hot vulcanization molding, widely used in silicone bonding metal, ABS/PC, nylon, epoxy resin, baked-wood and other hard substrate.

High temperature vulcanizing agent (double two-five) is recommended for silicone bonding metal. The vulcanizing temperature is between 170 ° c and 190 ° c. The curing speed is relatively fast.

In the process of hot bonding between silica gel and metal, the problem of unstable bonding often occurs. The main reasons for this kind of problem are as follows: 1. The metal surface is not treated clean.2. Silica gel is not evenly coated or repeatedly brushed, which may affect the bonding effect.Brush the glue evenly once on the surface to be glued, or soak the parts in the glue, or spray the glue evenly on the surface to be glued.3, drying: this point is very key, generally use room temperature drying and heating dry method.Generally, it takes a long time to dry at room temperature, so it needs to be put into operation in advance. The drying time varies according to the nature of products.The way of baking is in line with most products. Heating can make the moisture in the glue evaporate faster, and maintain the temperature of the bonded parts, improve the molecular activity of the treated metal surface, and achieve better bonding effect.4. Finally, silicon rubber and metal are put into the mold for molding.5. One point that should be paid special attention to is that after coating the glue, do not put it in the place where there is a lot of dust, and try to avoid the contact between the hands of employees and the bonding surface during the whole operation, because sweat on the hands will have a great impact on the bonding effect.If contact cannot be avoided, leather gloves or gloves are recommended.

Silicone hot adhesive plastic, most of the products are silicone adhesive nylon, silicone adhesive PC, silicone adhesive ABS.Silicone adhesive nylon is generally used double 25 high temperature vulcanization, speed up production, silicone and PC and ABS hot bonding must use platinum vulcanizing agent, medium and low temperature vulcanization, vulcanization temperature control under 150℃ and 110℃ (to see how much plastic can withstand temperature without deformation), other operating methods and adhesive metal basically the same.But here is a point to pay special attention to: it is to pay special attention to the drying, because the plastic has the characteristics of water absorption, processing if not baked dry on the effect of bonding is particularly large, especially easy to appear bubbles sticky, connect not firm, spots and other conditions.Therefore, the plastic material is usually bought back in the sun for a period of time, or stored in the warehouse when it is taken out of the oven to bake for a period of time to dehumidify and remove impurities (when heating some impurities will occur decomposition and release, also have an impact on the adhesion).

Finally, the back glue (silicone adhesive double-sided adhesive, adhesive, 3M adhesive).The adhesive of silica gel and double-sided adhesive is widely used in silicone rubber gasket and sealing ring, which can play a good role of anti-slip, anti-shock and sealing.But the process of bonding will often encounter the situation of weak bonding.This situation generally from: 1, whether the silica gel is clean; 2.2. Whether the glue brush is evenly applied;3. Whether the glue is dry;4. Whether the adhesive paper is 3M adhesive;5. Silica gel material, etc.

KANGLIBANG is to creat solution for your problem with bonding silicone, welcome customer inquiry to us.