What are the main advantages of MDI adhesive?
Guide: Judging from the development trend in recent ten years abroad, with the improvement of formaldehyde emission control requirements in various countries, MDI adhesive will be favored by more and more manufacturers.
At present, the mainstream adhesives in the wood-based panel industry mainly include urea formaldehyde adhesive, phenol formaldehyde adhesive, melamine formaldehyde adhesive and MDI adhesive. Under the premise of meeting different occasions and performance requirements, different rubber types have their unique characteristics and advantages.
According to the development trend of the past decade abroad, with the improvement of formaldehyde emission control requirements in various countries, MDI adhesive will be favored by more and more manufacturers. According to statistics, more than 70% of North American OSB manufacturers use MDI adhesive to produce, and the trend of switching from urea formaldehyde to phenol formaldehyde is increasingly obvious.
According to the application characteristics of MDI adhesive, its main advantages are shown in the following aspects: 1. The adhesive is formaldehyde free. MDI is a class of substances chemically named polyphenylmethane diisocyanate, and is one of the most important raw materials for preparing polyurethane. With the dual advantages of rubber and plastic, polyurethane is widely used in chemical industry, light industry, textile, architecture, home appliances, building materials, transportation, medical treatment, aerospace and other fields. Its excellent physical and chemical properties and safety performance enable it to be used in all aspects of our lives, including clothing fibers, refrigerator insulation, architectural decoration, and even implanted in human organs in medical treatment. Because MDI adhesive does not contain formaldehyde and has very low volatility, it can greatly avoid the harm of chemicals to human body during the production process. The boards produced by MDI adhesive are solidified at high temperature to form stable chemicals, which will not release formaldehyde and other organic chemicals, thus eliminating environmental pollution during product use. 2. The bonding principle of MDI adhesive with low sizing amount is different from that of traditional tri aldehyde adhesive. Traditional trialdehyde adhesive is physical bonding, while MDI is chemical bonding. The – NCO group in MDI can react with water in wood and – OH in cellulose to form stable chemicals. From the microscopic point of view, it can make the materials form intermolecular crosslinking, thus reducing the traditional “surface bonding” to “point bonding”, greatly reducing the amount of adhesive used. Generally speaking, according to different OSB grades, the MDI usage is 9-24kg/m?, It is only 1/4 – 1/5 of the traditional tri aldehyde adhesive. 3. Short hot pressing cycle Due to the chemical reaction characteristics of MDI adhesive, it can also accelerate the curing speed of adhesive, reduce the hot pressing time, and improve the production efficiency. From the application experience of OSB manufacturers in North America, the curing speed of MDI is at least 30% faster than that of urea formaldehyde adhesive, and it has more obvious advantages than that of phenol formaldehyde adhesive. In addition, MDI can also provide fast curing special products according to customer needs, so as to help customers achieve higher production efficiency and better product quality. 4. The excellent performance of the board can be easily introduced due to the above chemical bonding characteristics of MDI adhesive, and the performance of the board produced by the MDI adhesive will greatly exceed that of the adhesive based on the traditional physical bonding principle. The micro transformation from van der Waals force to chemical bond force has greatly improved the internal bonding force and waterproof and moisture-proof performance of the board. Some studies have shown that the static bending strength and creep property of MDI oriented structural board are far superior to those of urea formaldehyde adhesive, which is inseparable from its initial static bending strength and strong moisture resistance. 5. Considering the low cost and above advantages, MDI has a good cost performance from the perspective of sizing amount, hot pressing time and physical properties of products. At the same time, with the price of MDI becoming more reasonable, the price competitive advantage is gradually obvious, which has also become a major reason for European and American OSB manufacturers to choose MDI. Of course, there are also a series of problems in the application of MDI, such as the sticking problem, the demand for precise sizing control, and the storage characteristics of MDI itself. These have been effectively solved through years of practical production. At present, there are a variety of mold release agents that can be used together to solve the problem of sticking plates; In terms of sizing control, with the efforts of equipment manufacturers, it has also been effectively controlled; The storage and use of MDI, from the perspective of MDI manufacturers, has rich experience and complete sets of solutions to help customers jointly complete product switching. It is believed that MDI will become a competitive adhesive product on the development path of wood-based panels in China in the future, which can meet the special needs of users and create value for users.
