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In order to thoroughly implement the important instruction spirit of the practice on the construction of production workers, skill power and safety production, and solidly do a good job in the 23rd national "safety production Month" activities, Xinhui employees are guided to actively tree safety development concept, and constantly improve safety awareness and safety skills. Xinhui Company held the "Xinhui Chemical 2024 Safety Skills PK Competition" on the afternoon of June 29. The safety skills competition has further enhanced the safety awareness of all staff and created a good safety production atmosphere. Through the form of the competition, it also inspires the enthusiasm and enthusiasm of employees to learn safety knowledge. Looking forward to the future, we will continue to strengthen the publicity and training of safety production work and promote the in-depth development of the company's safety production work. Jointly create a safe and harmonious working environment, and contribute safety forces to the high-quality development of enterprises

The initial adhesion force is the core performance indicator of polyurethane laminating adhesives for flexible packaging. It refers to the initial adhesive ability of the adhesive to quickly adhere and fix the film substrate after being coated and laminated, without the need for continuous external pressure for a short period of time. It directly determines the stability of the flexible packaging laminating process and the qualification rate of the finished products, and is a key parameter that cannot be ignored in the lamination production process.    In the dry laminating and solvent-free laminating processes of flexible packaging, insufficient initial adhesion is a common problem in the industry. The solvent-free polyurethane laminating adhesive has a low initial molecular weight and weak internal cohesion at room temperature, resulting in a slow curing reaction rate. This makes it prone to defects such as creasing, shifting, and tunneling of the laminated film, and it is very likely to cause interlayer misalignment after the rolled material is wound up, significantly increasing the waste rate. In contrast, achieving the required initial adhesion enables the film to be instantly set after lamination, ensuring smooth operation of subsequent processes such as winding and cutting, and laying a foundation for the steady improvement of the final bonding strength during the subsequent curing process.  The molecular structure of adhesives, production conditions, and the addition of additives are the three core factors influencing the initial adhesion force. The ratio of the soft and hard segments in polyurethane determines the cohesion and wettability within the adhesive. The faster the soft segment crystallizes, the better the initial adhesion. The coating temperature and environmental humidity affect the flow of the adhesive and the wetting effect on the substrate. Imbalance in temperature and humidity will directly weaken the initial bonding effect. In addition, adding appropriate tackifying resins such as rosin and terpene resins can enhance the surface activity of the adhesive, strengthen the interface bonding force with non-polar films like PE and PP, and quickly improve the initial adhesion performance.    In actual production, it is necessary to balance the initial adhesion force and the final bonding strength: blindly increasing the initial adhesion force may lead to poor fluidity of the glue, resulting in uneven coating, bubbles and other problems. By optimizing the molecular formula, adjusting the process parameters of the composite, and compounding special adhesion enhancers, the initial adhesion and the final bonding strength of the adhesive can be balanced in both directions, meeting the production requirements of different flexible packaging scenarios such as food packaging and steaming packaging.

Polyurethane laminating adhesives are the core materials in the flexible packaging laminating process. According to the formulation system, they can be divided into solvent-based and solvent-free types. These two types differ significantly in composition, process, environmental friendliness, performance during use, and cost, and are suitable for different requirements of flexible packaging production.    In terms of composition and solid content, solvent-based adhesives use ethyl acetate as the diluent. The solid content is usually not 100%, relying on the solvent to reduce the viscosity of the glue and facilitate uniform coating. Non-solvent adhesives have a 100% solid content and do not contain any volatile organic solvents. They regulate the viscosity through the ratio of raw materials and temperature control, and do not require solvent dilution.   The production process and energy consumption are significantly different. Solvent-based lamination requires a long drying tunnel, where the solvent is evaporated through high-temperature drying. This process involves high equipment investment and high energy consumption. It generates a large amount of VOCs waste gas during the production process, and the finished product is prone to solvent residue issues, posing potential food safety hazards. Non-solvent-based lamination does not require a drying process. The equipment structure is simple, and the coating and compounding can be completed at room temperature. The energy consumption is significantly reduced, and there is no exhaust gas emission throughout the process. The product has no solvent residue.  The adhesive properties and applicable scenarios have their own advantages and disadvantages. Solvent-based adhesives have excellent wetting performance, strong initial bonding strength, outstanding resistance to boiling and low temperatures, and are suitable for high-demand packaging such as high-temperature boiling bags and aluminum foil composites. Non-solvent adhesives have a slower curing speed, are sensitive to production environment humidity, have slightly weaker temperature resistance, but have higher production efficiency and are suitable for common snacks, daily chemical products, and other regular flexible packaging.    At present, environmental protection policies are continuously tightening. Non-solvent adhesives, due to their green and low-carbon advantages, have gradually become the mainstream in the industry. However, solvent-based adhesives still play an irreplaceable role in the high-end, high-temperature-resistant flexible packaging field.  

Peel strength is the core indicator for evaluating the reliability of adhesion in flexible packaging composite films. It directly determines the sealing performance, weather resistance and service life of polyurethane laminating adhesive composite products, and is widely used in flexible packaging fields such as food, cosmetics and medicine. The higher the peel strength value, the stronger the interlayer bonding force of the lamination film, and the less likely the packaging is to have quality defects such as delamination, glue separation and edge warping.    The peel strength of polyurethane laminating adhesive is mainly influenced by three factors: raw material formula, substrate condition, and lamination process. At the formula level, the molecular weight of polyols and the content of NCO directly affect the cohesion of the adhesive layer. Reasonable combination of soft and hard segments can balance the toughness of the adhesive layer and the bonding strength, and enhance the peel strength at normal temperature and after boiling. In terms of the substrate, insufficient corona treatment of the film will reduce the surface tension, and the adhesive cannot fully wet the substrate interface, directly resulting in a significant reduction in peel strength. The release agents and other additives in the film will also disrupt the interface bonding effect.  The production process is the key link in controlling the peel strength. If the curing temperature is too low, it will cause incomplete cross-linking reaction of the adhesive and insufficient curing of the adhesive layer. If the temperature is too high, internal stress will be generated, making the adhesive layer brittle and reducing the peel strength as well. At the same time, the temperature and humidity in the workshop, the amount of coating, and the compounding pressure will also affect the bonding effect. A high humidity environment is prone to cause the polyurethane laminating adhesive to fail when exposed to water, reducing the effective cross-linking points.    In actual production, it is necessary to match the substrate type with the adhesive, standardize the corona treatment procedures, precisely control the curing temperature and the amount of glue application, and isolate the interference of water vapor. Through comprehensive optimization, the peel strength of the lamination film can be stably enhanced, meeting the requirements of different working conditions such as normal temperature packaging and high-temperature boiling, and ensuring the overall performance of the flexible packaging products.

Flexible packaging polyurethane laminating adhesives are the core materials in laminated packaging production. Many people mistakenly believe that similar polyurethane laminating adhesives have similar properties and can be mixed at will. However, in fact, there are significant quality risks involved. Different models and brands of adhesives must not be mixed at will.    The first issue is the incompatibility of chemical formulations. The resin structures, active groups, and additive ratios of different polyurethane laminating adhesives are all different. When some adhesives containing special additives and solvents are mixed together, uncontrollable chemical reactions will occur, resulting in sudden increases in viscosity, delamination, precipitation, gelation, and other problems, which directly undermine the stability of the adhesive and cause it to fail and be scrapped.  Secondly, it will disrupt the equilibrium of the curing reaction. For flexible packaging, most commonly used are two-component polyurethane adhesives, where the main agent and the curing agent are in a dedicated ratio system. Mixing different adhesives will disrupt the reaction ratio between hydroxyl groups and isocyanates, resulting in incomplete curing, sticky surfaces, soft collapse inside, or excessive cross-linking leading to brittle cracking of the adhesive layer, significantly reducing the lamination bonding strength.    Furthermore, the mixture can lead to quality defects in the final product. Glue with an imbalanced formula will have problems such as packaging delamination, blistering, and detachment after curing. Its temperature resistance, moisture resistance, and aging resistance will significantly decrease, and food packaging may also have safety issues such as off-flavors and excessive impurities. At the same time, the mixed glue is prone to clogging the gluing equipment, increasing production failures and losses. Therefore, in production, it is necessary to exclusively use the corresponding model of adhesive and strictly prohibit random mixing.

The flexible packaging polyurethane laminating adhesives are classified into three types based on production line speed: low-speed, medium-speed, and high-speed composite. They are suitable for different production capacities, adhesive types, and production requirements, and have significant differences in process characteristics.  The low-speed lamination line speed is generally ≤ 80m/min, mostly for small dry lamination machines, suitable for general-purpose solvent-based PU adhesive. The glue liquid has a long opening time and a relatively high viscosity, with a large tolerance margin. The requirements for equipment temperature control and tension accuracy are low, making it suitable for small-batch, multi-specification orders. It is often used for lamination of aluminum foil, thick PE and other difficult-to-adhere substrates. The coating amount is relatively high. A gradual temperature increase during drying is sufficient. It needs to be aged for 24–48 hours. The disadvantages are low production capacity and high pressure for solvent residue control. It is only suitable for small-scale processing factories.    Medium-speed lamination zone: 80–200m/min. This is the mainstream model in the industry. Both solvent-based and conventional non-solvent PU adhesives can be used. The adhesive fluid combines leveling and initial adhesion, is suitable for conventional packaging structures of plastic-plastic and aluminum-coated, and the drying and tension control systems of the equipment are mature. The coating is uniform and stable, balancing production capacity and product quality rate. It is applicable to regular packaging bags for food and daily chemicals, taking into account production costs and efficiency. The curing period is moderate, and the ink compatibility is wide. This process is widely adopted by medium-sized and large packaging factories.  High-speed lamination line speed: 200–450m/min. Mainly uses solvent-free quick-drying PU laminating adhesive, and a few quick-drying solvent adhesives can be adapted. The adhesive has low viscosity, rapid leveling, and instantaneous wetting of the substrate. After mixing, the stability of the coating is stable, and it is suitable for high-precision metering coating equipment. The entire process is temperature-controlled for glue application, with a lower coating amount, and the curing time is shortened to 12–24 hours, significantly improving production efficiency. The requirements for the fluidity of the glue, anti-bubble resistance, and thermal stability are strict. It is suitable for large-scale standardized food packaging. The VOC emissions are lower, and it is the mainstream solution for upgrading large-scale factories.    The core differences among the three types of processes lie in the activity of the adhesive solution, the control of coating, and the efficiency of curing. Enterprises select the corresponding lamination system based on the order quantity, environmental protection requirements, and other factors.

Flexible packaging polyurethane laminating adhesive is the core material for the production of composite packaging in industries such as food and daily chemicals. The stability of adhesion directly determines the quality of the packaging products. During practical operations, by controlling the four key aspects well, common problems such as delamination, stickiness, and odors can be effectively avoided, ensuring the qualified rate of production.    1. Surface treatment of the substrate. Before bonding, it is necessary to thoroughly remove dust, oil stains, release agents, and other impurities from the surface of the substrate (such as films and aluminum foil), and eliminate any residual moisture. Contaminants can damage the bonding interface, hinder the penetration and bonding of the adhesive, and easily cause poor adhesion and local delamination. In such cases, a special solvent can be used for wiping, and the construction can be carried out after the substrate is completely dry.  2. Control of solvents and ratios. The ethyl acetate solvent used for dilution should be of high purity, with the content of water and alcohols meeting the requirements. This is to prevent the consumption of the curing agent from causing incomplete curing of the adhesive layer. At the same time, the main agent and curing agent should be mixed in accordance with the standard ratio. It is strictly prohibited to arbitrarily increase or decrease the ratio. Different types of adhesive cannot be mixed, to avoid problems such as adhesive liquid failure and residual odors.    3. Construction temperature and humidity control. Polyurethane laminating adhesive is highly sensitive to environmental conditions. High temperature and high humidity will accelerate the consumption of the curing agent, resulting in incomplete drying or sticky glue layers. Low temperature will slow down the cross-linking reaction, leading to insufficient bonding strength and excessive solvent residues. During production, it is necessary to maintain appropriate temperature and humidity. The process parameters should be adjusted according to the weather conditions to meet the requirements of composite production.    4. Gel solution aging management. The gel solution prepared has an expiration period and must be used within the specified time. Excessive standing of the gel solution can lead to cross-linking failure and abnormal viscosity. At the same time, ensure the sealed and moisture-proof storage of the gel solution to prevent the introduction of water vapor and impurities, thereby ensuring the quality stability of the composite products from the source.

Flexible packaging polyurethane laminating adhesive is the core material of food, daily chemical and outdoor packaging lamination molding, and its weatherability directly determines the service life and stability of lamination film, which is the key index to measure the comprehensive quality of adhesive. When packaging is stored, transported and used outdoors, it is often affected by ultraviolet radiation, alternating temperature and humidity, damp-heat aging and other environmental factors, and it is prone to problems such as yellowing of adhesive layer, decrease of peeling strength, delamination and degumming, etc., and excellent weather resistance can effectively avoid such quality defects. The difference of weather resistance of polyurethane laminating adhesive comes from molecular structure design. The conventional aromatic polyurethane adhesive has high bonding strength and excellent cost performance, but the molecular structure has aging groups, which are prone to oxidative degradation and yellowing after long-term illumination. It is only suitable for indoor ordinary packaging scenes. However, the aliphatic polyurethane laminating adhesive does not contain unsaturated aging bonds, and has outstanding anti-ultraviolet and anti-humid aging capabilities. After curing, the adhesive layer is transparent and stable, and it is not easy to yellow and crack, which is suitable for outdoor packaging, long-term fresh-keeping packaging and other weather-resistant demand scenarios.   The industry often verifies its weatherability through QUV accelerated aging test and moist heat cycle test. After long-term aging test, high-quality modified products can still maintain stable adhesive strength and flexibility. At present, by optimizing the ratio of polyols, improving the catalyst system and adding weather-resistant additives, the environmental adaptability of adhesives can be further improved, taking into account the bonding performance and durability stability, and meeting the long-term use requirements of high-end flexible packaging.

Polyurethane laminating adhesive is a commonly used bonding material. It has strong adhesion and quick curing properties. If it accidentally comes into contact with the skin, do not panic. Mastering the correct handling method can effectively prevent skin irritation, redness, swelling and allergic reactions.    If adhesive gets on your skin, you need to deal with it immediately. Before the adhesive has fully dried, quickly use a clean cloth or tissue to gently wipe away the excess adhesive from the surface, reducing the amount of residue. Then, use flowing water together with mild soap or hand sanitizer to repeatedly wash the affected area for 1-3 minutes. Most of the un-solidified adhesive can be basically removed. Never rub or tear the adhesive forcefully, as this may damage the skin's surface and cause damage or infection.  If the glue has solidified and formed lumps, there is no need to forcibly remove it. You can gently wipe the glue surface with medical alcohol, insect repellent oil or a special glue remover. Wait until the solidified glue softens, then gently peel it off. Rinse the skin with clean water and finally apply hand cream and moisturizing lotion to soothe the skin. Do not use strong corrosive solvents such as banana water or acetone to wipe directly to prevent skin burns.    After the treatment, it is necessary to observe the skin condition. If there are symptoms such as redness, itching, stinging, rash, etc. indicating an allergic or irritating reaction, cold compresses should be applied repeatedly for relief. If the symptoms are severe, seek medical attention immediately. When using polyurethane laminating adhesive, it is recommended to wear gloves for protection to avoid skin contact risks from the source.

Before using the flexible packaging polyurethane laminating adhesive, a pre-test must be conducted. This is a crucial process in ensuring product quality, avoiding production risks, and meeting industry standards in the flexible packaging composite production. It is by no means an optional step. Even if the adhesive parameters meet the factory standards, it cannot be directly put into mass production.    The production of flexible packaging is influenced by multiple factors such as the substrate, ink, production equipment, temperature and humidity, etc. The compatibility of adhesives varies greatly under different working conditions. The lubricants in the film, residual solvents from printing, and the material properties of different brands of substrates all interfere with the bonding effect, and problems such as delamination, blistering, and failure to meet the peel strength standards are prone to occur. At the same time, the curing effect and viscosity state of polyurethane laminating adhesives will also change with the environment. The product instructions alone cannot adapt to the production conditions on site.    Industry regulations clearly stipulate that when new materials are put into production, the base material or ink is replaced, or process parameters are adjusted, small sample tests must be conducted. The routine tests include core items such as bonding strength, compatibility, and curing performance, which can effectively verify the process compatibility and identify bonding risks. For special flexible packaging such as food and medicine, the pre-test can also verify the material safety and ensure that the products comply with regulatory standards.    In conclusion, pre-testing is a fundamental step for controlling product quality, reducing losses, and avoiding compliance risks. It is also a necessary prerequisite for the large-scale production of flexible packaging polyurethane laminating adhesives.  

The curing process of flexible packaging polyurethane laminating adhesives is essentially a process where isocyanates and hydroxyl groups undergo cross-linking reactions to form a dense adhesive layer. The curing times of different adhesives on the market vary significantly, and the core reason lies in the multiple influences of the formulation system, ratio, and environmental conditions.    The formulation of the adhesive itself is the core influencing factor. Different products use different types of polyols and isocyanate raw materials, resulting in significant differences in reaction activity. Aromatic isocyanates have a faster reaction rate and shorter curing time, while aliphatic isocyanates have a milder reaction and slower curing speed. At the same time, the type and dosage of catalysts directly regulate the reaction speed. The catalytic efficiency of catalysts such as bismuth-based and organic tin-based is different, precisely altering the curing cycle of the adhesive.  The component ratio can also cause differences in curing. The ratio of components A and B in two-component polyurethane adhesives determines the molar ratio of NCO and OH groups. An imbalanced ratio will directly slow down the progress of the cross-linking reaction and prolong the curing time. Under standard ratios, the reaction is more complete and the curing efficiency is higher.    In addition, environmental temperature and humidity are important external factors. Polyurethane curing is a temperature-sensitive reaction. The higher the temperature, the faster the molecular movement and the higher the curing efficiency. In a low-temperature environment, the curing process will be significantly delayed. Appropriate humidity can assist in the curing process, but excessive humidity can easily trigger side reactions, which will instead affect the curing effect and cause unstable curing time. The combination of multiple factors ultimately leads to significant differences in the curing time of different flexible packaging polyurethane laminating adhesives.  

Flexible packaging polyurethane laminating adhesives are key materials in the production of flexible packaging lamination. Due to their excellent flexibility, high bonding strength, and wide adaptability to substrates, they are widely used in packaging fields such as food, medicine, and cosmetics. According to the solvent system, formulation structure, and construction characteristics, the industry mainstream classifies them into three major categories: solvent-based, non-solvent-based, and water-based polyurethane laminating adhesives. The performance and application scenarios of each type of product vary significantly.    Solvent-based polyurethane laminating adhesives are a traditional mainstream category, divided into single-component and two-component types. The two-component type is used by mixing the main agent and the curing agent in a specific ratio, and undergoes a cross-linking reaction to solidify. It has strong adhesion, excellent resistance to high and low temperatures, and outstanding resistance to boiling. It can meet the requirements of high-temperature sterilization, refrigerated storage, etc., for high-end packaging. The single-component type does not require mixing, is simple to operate, and has wide applicability. It is mostly used in ordinary dry-type lamination packaging. This category has mature technology and stable composite effects. It is still the preferred choice for high-end functional flexible packaging to this day.  Solvent-free polyurethane laminating adhesive is the core product of current green production. It does not contain organic solvents, and there is no VOC emission during the construction process, no residue, and it is highly safe. It cures at room temperature, has a fast curing speed, simple production process, and can effectively improve production efficiency and reduce production costs. The product has balanced comprehensive performance and is suitable for most food and daily necessities soft packaging laminating scenarios. It is currently the main alternative product for the environmental upgrade in the packaging industry.    The water-based polyurethane laminating adhesive uses pure water as the dispersion medium. It is non-toxic, odorless, environmentally friendly, and has extremely high safety. There is no risk of being flammable or explosive. Compared with the previous two types of products, it has slightly weaker water resistance and bonding strength, and average weather resistance. It is not suitable for high-temperature, humid, and high-strength usage scenarios. It is mainly used in lightweight, normal-temperature ordinary soft packaging, and is compatible with lightweight and low-demand packaging composite processes.

Safety is the bottom line of enterprise development, the cornerstone of production and operation, and the solid guarantee for every employee to work safely.   In order to further strengthen the staff's awareness of safety in production, consolidate the company's emergency response capability, comprehensively test the practicality and completeness of fire-fighting facilities and emergency equipment, and enhance the self-rescue, mutual rescue and cooperative rescue capabilities of employees in response to emergencies such as fire, material leakage and accidental injury. At 14:30 pm on May 26th, 2026, Xinhui Chemical organized a comprehensive emergency rescue drill for all employees in the company's workshops and squares in the first half of 2026. All employees of the company participated in the whole process, and all employees were promoted. This drill adheres to the principle of "actual combat simulation, promoting learning through practice, promoting prevention through practice, and covering all employees", and conducts all-round and comprehensive drills around the core contents such as fire emergency response, chemical leakage emergency response, personnel evacuation and escape, fire equipment operation, and medical emergency rescue, so as to effectively build a "firewall" for the company's safety production.   1. Careful deployment, careful preparation, build a safe foundation. This drill is well prepared in the early stage, with clear division of labor and responsibility to people. The company specially set up a drill working group, with the chief commander, deputy chief commander and drill consultant, and subdivided into ten special working groups: plot guidance group, logistics support group, information liaison group, fire fighting and rescue group, leakage rescue group, alert evacuation group, medical rescue group and photography group. Each department has its own duties and cooperated closely, and completed various preparations such as site investigation, material inventory, process rehearsal and personnel division in advance.   A complete set of emergency materials and equipment, such as dry powder fire extinguishers, foam fire extinguishers, smoke bombs, walkie-talkies, emergency medicine boxes, fire fighting suits, stretchers, etc., were provided on site, which provided solid logistical support and technical support for the safe, standardized and orderly development of the drill and ensured that the drill was close to actual combat and effective.   2.Real-life simulation and actual combat, full-process emergency response drill The drill site simulates complex sudden safety accidents such as sudden fire and material leakage in the workshop, and completely restores the real emergency disposal scene. With the trigger of simulated danger, the whole set of emergency procedures started quickly, and all emergency teams responded quickly and synchronized. Information liaison group: report danger, contact assembly and simulate alarm at the first time to ensure efficient and smooth information; Fire fighting and rescue team: go to the scene quickly to carry out initial fire investigation and fighting, and effectively control the spread of fire; Leak rescue team: wear light chemical protective clothing and carry out on-site rescue operations in strict accordance with the plugging plan;   Alert evacuation group: quickly delimit the alert area, orderly guide all employees to evacuate safely and assemble in an orderly manner, and put an end to risks such as crowding and detention; Medical rescue group: stand by at any time to carry out emergency rescue work such as emergency investigation, wound treatment and temporary dressing for simulated injured people.   In strict accordance with the emergency plan process, all staff responded quickly, standardized operation and cooperated in an orderly manner, and successfully completed the whole process drills of danger reporting, initial disposal, emergency rescue and plugging, alert isolation, evacuation of all staff and rescue of the wounded, which fully demonstrated Xinhui staff's efficient emergency literacy and tacit cooperation ability.   3.Practical teaching empowers everyone to master emergency skills.   The drill is not only simulation, but also practical operation, landing and full mastery. At the drill site, the company's safety director and security squad leader will carry out special fire safety training, giving detailed explanations on fire prevention common sense, initial fire judgment, key points of on-site emergency treatment, matters needing attention in escape and self-help, etc. At the same time, it focuses on the application scenarios, operation formulas and standardized use steps of commonly used fire fighting equipment such as dry powder fire extinguishers and foam fire extinguishing devices. Abandon formal drills, adhere to everyone's hands-on, everyone's hands-on practice, and employees of all departments experience fire fighting operations on the spot in turn, teaching by hands, and correcting mistakes face to face, so as to ensure that every employee really understands, learns, can use and dares to use them, and thoroughly consolidate the grassroots emergency response capability.     4. Summarize and improve the quality, and build a long-term security line.   At the end of the drill, the general manager of the company made a comprehensive review and summary comment on this comprehensive emergency drill for all staff. The orderly organization, active participation of all staff and efficient cooperation of all groups were affirmed, and professional analysis and guidance were provided for the detailed problems and weak links in the exercise. The meeting emphasized that there is no trivial matter in safety production, and emergency drills are not acting, but normalized safety compulsory courses. All employees should take this drill as an opportunity to deeply understand the importance of safety in production, master the skills of emergency self-rescue and mutual rescue, and turn the results of the drill into conscious actions for daily safety performance. All departments should continue to compact safety responsibilities, carry out hidden danger investigation and emergency training in a normal way, fill in safety shortcomings, and build a solid defense line for enterprise safety production.   5. Promote safety through practice and stick to the initial escort development.   Safety is more important than Mount Tai, and prevention begins before it happens.   This comprehensive emergency rescue drill for all staff further improved the company's emergency handling process, tested the actual combat ability and coordination level of emergency teams, and comprehensively improved the fire safety awareness, risk prevention awareness and emergency self-help ability of all staff.   In the future, Xinhui Chemical will always adhere to the safety production concept of "safety first, prevention first and comprehensive treatment", regularly carry out various safety training and emergency drills, constantly optimize the emergency management system, lay a solid foundation for safety production, and take rigorous attitude and solid measures to protect the personal safety of employees and ensure the stable, safe and high-quality development of enterprises!   Safety is no small matter, alarm bells are ringing, always practice and be ready, and take precautions!

The conventional ordinary polyurethane adhesive laminated  packaging bags are not recommended for long-term outdoor use in the open air. They can only be temporarily stored in a shaded area. Customized products with weather-resistant formulas can be stored outdoors for a long time.    The PU laminated rubber layers of ordinary flexible packaging are mostly of polyester-based systems, and their water resistance and UV resistance are relatively weak. The ultraviolet rays in outdoor sunlight continuously damage the molecular chains of the rubber layers, causing yellowing and a decrease in internal cohesion within a short period. In high-temperature environments combined with high humidity from rain and moisture, the polyester structure is prone to hydrolysis and softening, resulting in film delamination, gum detachment, and bag rupture. The temperature range of these conventional products is limited. Excessive summer sun exposure can cause the rubber layers to creep, while low-temperature frost can make the rubber membranes hard and brittle, cracking. The repeated expansion and contraction caused by temperature differences between day and night will accelerate the separation of the composite layers.  If it is to be used outdoors, the polyether type weather-resistant polyurethane laminating adhesive needs to be replaced. The adhesive mixture should be compounded with UV absorbers and hydrolysis stabilizers. At the same time, the outer layer should use PE or BOPP weather-resistant base material that is added with UV-resistant masterbatch. The aluminum foil lamination type has better outdoor durability as the aluminum layer can block UV rays.    Unmodified ordinary packaging bags can only be temporarily stored outdoors in a shady and rainproof area for a short period. When stored outdoors, they usually lose their effectiveness within 3 to 8 months. Customized weather-resistant models can achieve stable outdoor use for 1 to 3 years, meeting the outdoor packaging needs of agricultural supplies and industrial raw materials. 

When the flexible packaging film is laminated with polyurethane adhesive, irregular white spots and white dots often appear on the surface of the finished product, seriously affecting the appearance and quality of the packaging. This problem is not caused by a single factor. It mainly lies in four aspects: chemical reaction, process operation, material matching, and equipment environment. It is a common quality issue in the production of flexible packaging laminating.    The production of gas through chemical side reactions is the main cause of the formation of white spots. The isocyanate groups in the polyurethane curing agent are extremely sensitive to water. If the glue and the diluent ethanol contain excessive moisture, or if the humidity in the workshop is too high, the moisture will react with the adhesive to form carbon dioxide micro-bubbles. These tiny bubbles are enclosed within the film composite layer. After the material is cured and shaped, dense white spots will form, which is also the most common defect-causing factor in production.  Improper process operation will aggravate the problem of white spots. Insufficient glue application and excessively high glue viscosity will result in poor leveling of the glue layer, local glue shortage and uneven coating, which will cause gaps during bonding and form white spots. Insufficient composite pressure and uneven film tension will prevent the composite roller from completely removing the air in the interlayer, resulting in residual air spots. At the same time, insufficient oven temperature and incomplete drying will cause solvent residue to trigger local whitening.    Material matching and equipment issues should also not be overlooked. If the compatibility between the ink and the polyurethane laminating adhesive is poor, or if the covering rate of the light-colored ink is insufficient, local whitening and grayish-white spots will occur. If the corona treatment of the film is not up to standard or surface additives are released, it will reduce the wetting property of the adhesive layer, resulting in inaccurate bonding. In addition, foreign substances adhered to the surface of the gluing roller and the composite roller will cause regular local white spots, affecting the qualification rate of the finished products.

The two-component polyurethane laminating adhesive consists of the main agent and the curing agent. The ratio directly determines the degree of cross-linking reaction and is the core factor affecting the bonding quality. An imbalanced ratio will damage the performance of the adhesive layer in terms of curing, bonding, and weather resistance.    The amount of curing agent is insufficient, resulting in a lack of crosslinking groups. The resin cannot fully react and cure. The adhesive layer remains sticky for a long time and does not dry completely. The internal cohesion significantly decreases, and it is prone to delamination under force. At the same time, the water resistance and solvent resistance of the adhesive layer deteriorate. It is also prone to softening and peeling when heated. When the amount of curing agent is excessive, the excess curing agent remains in the gel and slowly precipitates later, causing the adhesive layer to crack and shrink, develop wrinkles, and create gaps at the bonding interface, thereby reducing the peel strength.  Precise proportioning enables the hydroxyl groups and isocyanate groups to react chemically in a complete manner according to the stoichiometry, forming a dense and stable network molecular structure. The hardness and toughness of the adhesive layer are balanced, making it suitable for composite substrates such as soft plastics and aluminum foil, meeting the requirements for high-speed composite production of packaging materials. Deviation in the proportion will also affect the curing rate. Imbalance in the proportion or excessive curing can result in bubbles, pinholes, or prolonged curing time, delaying the production process.    Furthermore, if the ratio is out of control, it can release small molecular by-products. The composite product may experience bubbling and have an unpleasant smell, which does not meet the safety standards for food and pesticide packaging. Only by strictly following the manufacturer's ratio for material addition can the bonding effect be stabilized, the loss of defective products be reduced, and the long-term stability of the product be guaranteed.

The curing agent for flexible packaging two-component PU glue is mainly composed of modified products of polyisocyanates. It is selected in three major systems: solvent-based, non-solvent-based, and dedicated for boiling treatment. The main types are aromatic and aliphatic.    The most commonly used solvent-based dry bonding adhesive is the TMP-TDI addition product, which is formed by the addition of toluene diisocyanate and trimethylolpropane. It is diluted with ethyl acetate to a solid content of 75%, featuring high cost-effectiveness and moderate curing speed. It is suitable for normal PET, BOPP, and CPP temperature-composite packaging. The ratio is mainly masterbatch: curing agent = 100:5-8. After 36-72 hours of curing, it is ready for molding. It is the standard curing agent for ordinary snack packaging bags. For products that can withstand boiling water and high-temperature steaming, the TMP-MDI addition product is used. Its molecular structure is regular, with a higher crosslinking density, and it is resistant to media and high temperatures. It is suitable for aluminum foil and nylon steaming bag composites.    The solvent-free soft packaging adhesive curing agent is a high NCO aromatic MDI prepolymer. It is 100% solvent-free, has high viscosity at room temperature and excellent flowability when heated for coating. When combined with polyester polyol as the main agent, it is suitable for high-speed solvent-free laminating machines. It is mainly used for food aluminum-coated film laminating. The low free monomer grade can meet the food-grade compliance requirements.    The high-end transparent and yellow-resistant packaging uses HDI tri-functional aliphatic curing agent, which does not yellow and is resistant to aging. It is mainly used in daily care products and high-end transparent soft packaging, and its cost is higher than that of the aromatic system. The water-based soft packaging adhesive is paired with hydrophilic modified isocyanate curing agent, which is mixed in water for use. It focuses on being environmentally friendly and low in VOC.

1. Raw Material Composition The flexible packaging polyurethane laminating adhesive is composed of polyols and isocyanates as the core raw materials, forming a two-component system of main agent and curing agent. The main agent mostly uses polyester polyols and polyether polyols, and is adjusted with additives to regulate the wetting property. The curing agent is mainly composed of isocyanate adducts. According to the type of solvent, it can be classified into solvent-based, solvent-free, and water-based types. The solvent-free products do not contain organic solvents, while the water-based ones use pure water as the solvent, which is suitable for environmental protection production requirements. A small amount of leveling agents and antioxidants are added to improve the storage and coating performance.    2. Functional Characteristics The product is cross-linked and cured into a gel layer through the interaction of hydroxyl groups and isocyanate groups. It has excellent bonding strength, is resistant to both high and low temperatures, and can withstand the erosion of oils, acids, and alkalis. The gel layer is flexible and transparent, does not corrode printing inks, and possesses excellent hydrolysis resistance and heat sealing adaptability. The solvent-free version has low VOC and no residual solvents, complies with food safety standards, is compatible with high-speed laminators, has controllable curing speed, and is less prone to bubble formation, wrinkling, and delamination, and is suitable for laminating films of varying thickness.    3. Application Scenarios It is widely used in the composite of flexible packaging substrates such as plastic films, aluminum foils, and paper-plastic. In the food industry, it is applied to packaging for snacks, meat products, frozen ingredients, and dairy products. In the cosmetics industry, it is suitable for packaging of laundry detergents and skin care products in flexible tubes. In the pharmaceutical industry, it is used for pharmaceutical composite films and outer packaging of infusion bags. For pesticides and chemical products, its corrosion resistance is utilized to manufacture anti-corrosion composite bags. With the advancement of environmental policies, solvent-free and water-based polyurethane laminating adhesives gradually replace traditional solvent-based products and have become the mainstream bonding material for soft packaging composites.

Pesticide packaging serves as a crucial barrier to ensure the safety of pesticide storage, transportation and use. Polyurethane laminated adhesive, with its outstanding comprehensive performance, has become the core bonding material for modern pesticide composite packaging, safeguarding the stability and safety of pesticide packaging.    Pesticides generally have corrosive and penetrating properties, and they require extremely high standards for the media resistance, sealing, and bonding strength of packaging materials. Polyurethane laminated adhesives are suitable for various common base materials used in pesticide packaging, such as PET, PE, aluminum foil, and nylon. They have good wetting properties and strong adhesion, enabling stable multi-layer material bonding. This effectively enhances the overall structural strength of the packaging and prevents it from splitting or being damaged. At the same time, after curing, they have outstanding resistance to chemical corrosion and anti-permeation properties, which can resist the erosion of pesticide solutions, prevent leakage and volatilization of the pesticide solution, and eliminate the problems of pesticide pollution and loss of efficacy.  Compared with traditional adhesives, the special pesticide packaging polyurethane laminating adhesive has strong initial adhesion and excellent composite stability. It is suitable for mainstream packaging processes such as dry composite and solvent-free composite, meeting the requirements of large-scale production. Moreover, the new solvent-free polyurethane laminating adhesive is environmentally friendly, complies with industry safety standards, and does not release harmful substances, ensuring the safety of pesticide storage and reducing the environmental harm caused by packaging waste.    With the upgrading of pesticide packaging towards lightweighting, compositing and greening, the technical advantages of polyurethane laminating adhesives have become increasingly prominent, and have already become an important foundational material for promoting the quality improvement and upgrading of the pesticide packaging industry.

Water-based polyurethane laminating adhesive uses water as the dispersion medium. With advantages such as environmental friendliness, safety, and stable performance, it has now become one of the mainstream materials in the field of soft packaging composites, aligning with the development trend of green transformation in the industry.    This laminating adhesive has no volatile harmful solvents, has a low odor, and excellent flame retardancy. During production and use, it does not cause air pollution. It meets the hygiene requirements for packaging in the food and daily chemical industries. It is particularly suitable for processing products such as food soft packaging bags and daily-use composite films. In terms of adhesive performance, it has excellent adhesion to common flexible packaging substrates such as PE, PP, PET, and aluminum foil. The bonding strength of the composite products is high, it is resistant to bending and low temperature, and can adapt to subsequent packaging processes such as cutting, heat sealing, and storage.  From the perspective of process compatibility, water-based polyurethane laminating adhesive can be matched with conventional dry composite equipment. It has uniform coating, good leveling performance, and a moderate curing speed, balancing production efficiency and product appearance. At the same time, it has outstanding flexibility, and the composite film is less likely to have delamination or wrinkling problems, and can also meet some functional packaging requirements such as water boiling resistance and steam boiling resistance.    With stricter environmental regulations, the flexible packaging industry has gradually phased out solvent-based adhesives and the application scope of water-based polyurethane laminating adhesives has continued to expand. Currently, its main drawback lies in the fact that there is still room for improvement in terms of temperature resistance and water resistance. The industry is also constantly optimizing the formula to further enhance the comprehensive performance, promoting its deep penetration in the high-end flexible packaging field.