Common Application Issues of Composite Films
应用工艺
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2025-02-17
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FAQ
A：（1）Inconsistent thickness of the composite film leads to uneven shrinkage rates.
（2）Excessive sealing temperature or prolonged sealing time.
（3 ) Inadequate cooling causing wrinkles at the sealing area.
（4） Insufficient curing time or temperature, or the influence of residual solvents.
（5） Poor heat resistance of the surface or inner layer film causing shrinkage and wrinkles.
（6） Improper control of the tension matching of the composite substrates during the lamination process, leading to residual stress after curing and setting, which is more likely to occur when the composite film is thinner.
A：（1）The PU dye is a blue solution that can dye the polyurethane adhesive layer blue upon contact. In the flexible packaging industry, PU dye can be used to determine which layer of the separated composite film the polyurethane adhesive layer is attached to, helping to analyze the causes of poor delamination strength.
（2）Infrared spectroscopy test: Reflective infrared testing basic spectrum, accumulate a basic spectrum database of different raw material films, and comparative analysis can determine which film layer the adhesive is on.
A：（1）Low adhesive application, not enough to penetrate all the ink, resulting in fine and uniform spots over the entire composite film area. The solution is to appropriately increase the adhesive application and adjust the lamination temperature and pressure.
（2） Poor cleanliness of the application and lamination rollers, with adhesive or other foreign objects on the rollers, resulting in local intermittent and recurring spots. For this phenomenon, the distance between recurring spots can be measured to identify which roller has foreign objects, and then clean it.
（3）Uneven tension in the substrate film, causing folding before entering the lamination roller, resulting in poor local lamination effect, bubbles, and macroscopically appearing as white spots. White spots caused by this reason can be solved by adjusting the guide roller angle before lamination to flatten the film before entering; replacing the film roll; and appropriately adjusting the tension.
（4）Improper pressure setting at the lamination or adhesive application area. Solution: Adjust the pressure.
（5）Poor compatibility between the ink and the adhesive, in which case only a suitable adhesive or ink can be replaced.
A：An adhesive that forms a strong bond through heating and melting, moisture curing, characterized by fast bonding and high strength.
A：Ordinary adhesives cure by cooling, while PUR cures through both cooling and moisture chemical reaction, thus having higher heat resistance, solvent resistance, and bonding strength.
A：Metals, plastics, wood, fabrics, leather, etc., especially suitable for mixed bonding between different materials.
A：It does not contain organic solvents, and no harmful substances are released after curing, meeting environmental standards such as RoHS.
A：Special heating equipment is needed; it needs to be sealed and moisture-proof after opening; clean the material surface before bonding.
A：Although PUR hot melt adhesive is widely used and has significant performance advantages, some drawbacks in comprehensive performance have limited its application development. Improving these existing issues will be the research direction for the next step in PUR hot melt adhesive.
（1）Improve the initial adhesion of products;
（2）Reduce the melt viscosity and application temperature to save energy;
（3）Improve the high-temperature resistance and flame retardancy of products to expand their application range;
（4）Reduce the creep of products, improve their mechanical strength and chemical resistance, and enhance their hydrolysis resistance and moisture and heat resistance;
（5）Build rapid and automated production lines.
A：（1）In terms of raw materials: whether the resin indicators are qualified, whether the curing agent is matched; HAA type polyester curing with TGIC does not reach complete curing; the supplier, purity, and batch of the curing agent; the ratio of resin, pigments, and fillers; whether extrusion is sufficient; whether curing conditions meet the design.
（2）In terms of powder coating application: pretreatment of the substrate; coating is generally done within 4 hours after derusting and sandblasting; whether the size and thickness of the workpiece, curing temperature, and time meet the design; whether the film thickness is too thick, generally 60~80um is optimal.
A：（1）Raw material aspects: Polyester resins are synthesized from high molecular weight polyols and polyacids, with fewer residual small molecules, resulting in less smoke; economic products have slightly higher residual small molecules due to synthetic raw materials; small molecule substances such as benzoin and PE, PA wax powder, and other additives mainly volatilize and decompose when heated; different components of the matting agent release small molecules during the reaction; the curing agent for polyurethane powder coatings is of the blocked type, which will unblock during the reaction process, releasing a large amount of blocking catalysts, moisture absorption of materials, and other additives and contents.
（2）Powder coating application aspects: Powder moisture absorption, oven ventilation, low environmental air pressure.
A：（1）Raw material aspects: Low glass transition temperature (Tg) of polyester resin, powder storage temperature close to Tg, softening and sticking together; the higher the resin content, the more obvious, appropriate reduction of resin content, and increase of pigments and fillers; types, suppliers, and batches of curing agents; Tg reduction during TGIC curing; high acid value/hydroxyl value, high activity, poor storage; poor storage of PU and heat transfer compared to other systems; matting agents, brightening agents, catalysts, etc., involved in the reaction, shortened gelation time, poor powder storage, and deterioration; benzoin and wax powder, other additives and contents.
（2）Powder coating application aspects: Powder coating particle size is too fine; whether thoroughly cooled after grinding; whether the storage environment for finished powder is dry and cool, environmental temperature and humidity; whether the temperature is too high during transportation; whether in contact with high temperatures at the coating site, etc.
A：（1）The weather resistance of polyester resins directly affects the weather resistance of powder coatings, with the total content of IPA, TPA, and antioxidants in polyester synthetic monomers.
（2）The content of resin and pigments and fillers in powder coatings, with higher content effectively improving the weather resistance of powder coatings.
（3）The type of powder coating selected, the pretreatment method of the coated substrate, surface treatment quality, coating thickness, baking conditions, and other coating processes directly affect the salt spray resistance of the coating film.
A：（1） Raw material aspects: Whether the resin indicators are qualified, unmelted, difficult to disperse impurities, etc.; economic polyesters have poor anti-interference performance due to the use of small molecule alcohol acids and other factors; whether anti-interference additives are added in the formula; HAA, PU system products release water molecules and blockers during the curing process.
（2） Powder coating application aspects: Inadequate pretreatment before processing, whether already contaminated; workpiece rust, moisture, secondary surface contamination; whether thoroughly cleaned when switching systems from different manufacturers; whether the compressed air is clean, with oil, moisture; whether the recovery system is cleaned; whether there are grease, lubricating oil, and other heat-volatile substances in the hanger and oven; whether there are dust, grease pollution sources in the external environment; incompatibility of powder coatings from different manufacturers.
A：Keep away from frost and direct sunlight. Store in a cool, dry environment with a temperature range of 5℃-35℃. Do not exceed a storage period of 6 months.
A：After opening, immediately seal it. Under conditions with an environmental temperature of 5℃-35℃, it can be stored stably for 4 months
A：After opening, immediately seal it. Under conditions with an environmental temperature of 5℃-35℃, it can be stored stably for 6 months.
A：4-6 hours. The usage time generally should not exceed 6 hours. Adhesive that has been used for more than 6 hours should be promptly cleaned up and thrown away. Do not pour it back into the original packaging or mix it with the next batch of adhesive.
A：15-25℃. Bonded samples should not be placed in high-temperature environments after preparation, as this may cause warping, rebounding, and edge lifting. The temperature should also not be too low, otherwise, the curing time of the adhesive will need to be extended, and the increase in cohesive strength will be slow. Incomplete curing due to low temperature can lead to poor bonding.
A：Insufficient surface treatment: The presence of oil, dust, oxides, or mold release agents on the substrate surface leads to reduced adhesion. Improper adhesive selection: Large differences in the coefficient of thermal expansion between epoxy adhesive and substrates (such as plastics, metals, silicones, etc.), or high hardness and poor toughness after curing, leading to stress cracking. Inadequate curing conditions: Curing temperature, time, or humidity do not meet the requirements (e.g., incomplete curing at low temperatures). Environmental factors: Long-term high temperature and humidity, thermal cycling, chemical corrosion, or mechanical vibration leading to interface failure. Internal stress issues: Curing shrinkage of the potting adhesive or substrate deformation generates internal stress, causing delamination.
A：Mainly due to the presence of additives such as dispersants, defoamers, and levelers in filled epoxy resin potting adhesives. These substances have some compatibility differences with the resin matrix and may migrate to the surface during use, forming "oil spots".
A：Pay attention to the glass transition temperature; generally, a higher glass transition temperature implies stronger heat resistance. Pay attention to the coefficient of thermal expansion; usually, resins with high coefficients of thermal expansion are prone to delamination from the substrate during temperature changes. It is recommended to choose products with as low a coefficient of thermal expansion as possible based on actual needs. Pay attention to the flame retardancy of the product; the flame retardancy directly affects the final product's flame retardancy rating. Pay attention to the flowability of the product; poor flowability may lead to insufficient bonding with internal components, further resulting in poor electrical performance. Pay attention to the breakdown voltage.
A：Pay attention to product viscosity; lower viscosity usually means better flowability. If flowability is relatively insufficient, it is recommended to preheat the product within a reasonable temperature range. Use vacuum potting technology; increasing vacuum levels can significantly reduce the probability of internal bubbles. Choose products with better adhesion to internal components to effectively avoid the formation of cracks between the adhesive and internal components.
A：Polyurethane products can react with moisture in the air to undergo cross-linking curing. Traditional polyurethanes are mainly capped with isocyanates, and the surface that comes into contact with moisture cures first, leading to a rapid increase in hardness and the formation of a hard shell in the early stages. New generation products use hydroxyl capping, which can effectively improve this issue.
A：Users often hope that the product will have excellent performance after curing, while also hoping to simplify the process as much as possible. However, from the technical requirements of the product, generally speaking, choosing a multi-stage curing process with different temperatures over a longer period often achieves better results. For example, in a three-stage process, the first two stages provide sufficient gelation time for the potting adhesive to complete steps such as bubble release and stress relief inside the product, followed by a rapid curing in the third stage to achieve better post-curing performance.
A：At room temperature and pressure, all materials can be divided into three major categories based on their volume resistivity (or conductivity): conductive materials, semiconductor materials, and insulating materials. When the volume resistivity of a material is greater than 1.0×10^7Ω·m, the material is considered an insulating material.
A：The heat resistance rating of insulating materials is defined according to the continuous operating temperature that the insulating material can withstand for 20,000 hours, meaning that its performance does not undergo undesirable changes over 20,000 hours at that temperature.
A：(1) Impregnation insulating resins can be classified based on their main components into: epoxy, alkyd, phenolic, polyester, diphenyl ether, organosilicon, and imide types.
(2) Impregnation insulating resins can be divided into solvent-containing (including low solvent) types and solvent-free types based on whether they contain solvents.
(3) Impregnation insulating resins can be classified into different heat resistance grades such as Y, A, E, B, F, H, 200, and 220 levels.
A：Impregnation insulating resins, with their adhesion, thermal conductivity, insulation, and heat resistance properties, are widely used in the manufacture of various motors, transformers, and coil windings. They provide these products with better integrity, thermal conductivity, electrical insulation, and mechanical stability, while also protecting the equipment from environmental influences.
A：The main application processes for impregnation insulating resins include: general immersion, vacuum pressure immersion, continuous immersion, drip immersion, and roll coating.
A：After aging at 80℃ for one month, the adhesion force increase rate for the polarizing film does not exceed 60%.
A：The surface resistivity of the pressure-sensitive adhesive layer is between 10^10 and 10^12 ohms/square.
A：Based on retention force data, at 85°C and 85% RH with a weight of 1kg for 20 hours, there is no sample displacement.
A：Our PSA0163-2 has excellent heat resistance and antistatic properties. Antistatic agents can be added according to specific needs, and adding a certain amount of antistatic agent will not affect the inherent heat resistance.
A：OCA for cover glass bonding, OCA for backlight modules, OCA for AF coating, etc.