Research And Development Trend Of Flame-Retardant Decking Materials
Plastic-wood composite PVC decking materials (plastic-wood) refer to thermoplastic polymer materials such as PE (polyethylene), PVC (polyvinyl chloride), PP (polypropylene) and their copolymers, and wood fiber materials such as wood flour and plant hulls. Raw materials, composite materials made by molding methods such as injection molding and pressing. It has the advantages of both polymer and wood fiber materials, and can partially or completely replace wood for building materials, furniture and packaging. However, the wood fibers and polymers that make up the composite materials are flammable materials, making almost all plastic wood flammable. Once caught in a fire, it may cause disasters and cause serious losses to people’s property and life safety. Therefore, plastics The flame retardant research of wood composites is imperative.
Flame retardant treatment method of plastic wood PVC decking
Adding method refers to the direct mixing of flame retardant with wood fiber materials and resin materials, and then through certain molding methods to prepare flame retardant plastic-wood composite materials. This is currently the most conventional flame-retardant treatment method for plastic wood. APP, Al(OH) 3 etc. generally use this treatment method. The coating method refers to the flame retardant, etc., made into a slurry and coated on the surface of plastic wood to achieve the purpose of heat insulation and oxygen isolation. This method is simple to operate and has little effect on material performance, but once the flame-retardant layer is damaged, the flame-retardant effect is also invalid. In view of the fact that the coating method may cause the flame retardant performance to fail, most of the flame retardants currently use the additive method.
Synergistic flame retardant refers to the compounding of two or more flame retardants in a certain proportion into a composite flame retardant. After adding them to plastic wood, it can overcome the poor anti-dripping and smoke suppression effects of a single flame retardant, The shortcomings of low flame retardant performance. The intumescent flame retardant currently used combines acid source, gas source and carbon source, and has a synergistic flame-retardant effect by itself, especially the use of APP is the most typical. Other types of flame retardants are widely used in wood and plastic flame retardant, but they are rarely seen in plastic wood flame retardant applications. Therefore, effective reference can be drawn from the research on flame retardancy of materials and plastics.
The flame retardant treatment research of plastic wood PVC decking is still in its infancy. During the processing, there are still many problems to be solved.
1) Most flame retardants are additive powder materials, which are generally very polar, have a hydrophilic group, and are incompatible with the lipophilic polymer matrix. When the amount of addition is small, the flame retardant effect cannot be achieved; the amount is large at this time, it is easy to produce voids with the substrate interface, which reduces the physical and mechanical properties of plastic wood.
2) The flame retardant of plastic wood not only involves wood flame retardant and polymer material flame retardant, but also related to the interaction of the two. The flame retardant situation is very complicated, so that some flame retardants suitable for wood or plastic cannot be directly applied Regarding the flame retardancy of plastic-wood, studies have shown that the flame retardancy of APP for plastic-wood composites is different from that of plastics. Adding PER to plastics can significantly improve the flame-retardant properties of APP, while in plastic-wood, no flame retardant increase of PER has been observed. This is because the wood fiber material of plastic wood acts as a carbon source. The research on the flame-retardant mechanism of plastic wood has just started, so far there is no clear report.
3) The efficiency of a single flame retardant is low, and it has a great impact on the physical and mechanical properties of polymer materials. The synergy of multiple flame retardants is a hot spot, but interaction or other new effects may occur during the compounding process of various flame retardants. The problem, the discussion of the synergy mechanism and the modification of flame retardants appear to be very critical.
In order to improve the flame-retardant effect of plastic-wood PVC decking and solve the problems encountered in its processing, further research on the modification of plastic-wood flame retardants should be made in the future. It is necessary to comprehensively consider various influencing factors to lay a solid foundation for expanding the application of WPC in other industries.
1) Nano technology: Nano materials have surface effects, quantum size effects and small size effects. Making flame retardants into nano materials can make them superior in performance to conventional flame retardants, that is, they have high flame retardancy and good properties. Interface compatibility.
2) Graft modification technology: The purpose of grafting modified flame retardant is to interact with the hydrophilic functional groups on the surface of the flame retardant through the chemical coupling agent to make the flame retardant change from hydrophilic to hydrophobic and enhance flame retardancy. The compatibility of the agent material with the polymer matrix improves its dispersibility in the plastic wood to compensate for the adverse effects of the addition of the flame retardant on the original performance of the plastic wood.
3) Microcapsule technology: Microcapsule technology refers to the use of natural or synthetic polymers as capsule materials to coat solid, liquid and gaseous substances to form microcapsules with a core-shell structure with a certain particle size range. Through this technology, the physical and chemical properties of the core material in fthe capsule can be well protected from being damaged, and the impact of toxic substances on the environment or human body can be reduced. It is conceivable that the flame retardant can be coated in the capsule shell of the organic wall material, which can be effective Improve the compatibility of the flame retardant with the matrix of the composite material and enhance the flame retardant treatment effect.
