Water-based polyurethane is mainly used in leather processing, textile printing and dyeing, paper industry, architectural coatings, adhesives, etc., almost all of them are flammable materials. If these materials are used without flame retardant treatment, they will inevitably cause fire Security risks. The flame retardant of waterborne polyurethane is one of the important directions of the functionalization of waterborne polyurethane. At present, most researches on reactive flame retardant waterborne polyurethanes use halogen-containing polyether polyols as reactive monomers or halogen-containing small molecule glycols as chain extenders to participate in the synthesis, because halogen-containing flame retardants The flame retardant effect is good, which can meet the flame retardant needs of many polyurethane products, so it still occupies a dominant position until now, but it will generate more smoke and toxic corrosive gases (such as hydrogen bromide) during the combustion process. This gas is very dangerous in a fire because it spreads extremely fast, which seriously hinders the firefighters' fighting work and causes great harm to people's lives and property. In this paper, through the hard segment modification of waterborne polyurethane, the flame retardant component frc-5 n, p is connected to the polyurethane molecular chain, and let it participate in the reaction as a chain extender for waterborne polyurethane reaction, so that not only n, p Synergistic flame retardant purpose, and it can synthesize waterborne polyurethane with good performance and inherent flame retardancy. Research shows that the waterborne polyurethane synthesized with it has better flame retardant effect, and the prepared emulsion has better stability and High temperature resistance has great research significance in practical applications.
Polyether 210 (n-210), isophorone diisocyanate (ipdi) as the basic monomer, using frc-5 as a chain extender, the flame retardant elements n, p are introduced into the waterborne polyurethane by hard segment modification In this paper, a series of flame-retardant water-based polyurethanes with different degrees of modification were synthesized. The effect of the amount of frc-5 on the flame retardant and thermal properties of waterborne polyurethane was studied. The results show that chain extension with frc-5 can improve the flame retardancy and thermal stability of waterborne polyurethane.
The flame retardant mechanism of frc-5 is as follows: during combustion, the phosphate ester decomposes to form a non-flammable liquid film of phosphoric acid, the boiling point of which can reach 300 ° C. At the same time, the phosphoric acid is further dehydrated to form metaphosphoric acid, and the metaphosphoric acid is polymerized to form polymetaphosphoric acid. In the process, not only the covering layer generated by phosphoric acid plays a covering effect, but also because the generated polymetaphosphoric acid is a strong acid and a strong dehydrating agent, it dehydrates and carbonizes the polymer, which changes the mode of the polymer combustion process and A carbon film is formed on the surface to isolate the air, thereby exerting a strong flame retardant effect. When n is added, since p and n can promote the carbonization reaction together, the synergistic flame retardance of n and p is better than that of p alone.
Test part
1. Test materials
Polyether n-210, chemically pure, Shandong Dongda Chemical; isophorone diisocyanate (ipdi), chemically pure, Beijing Xizhong Chemical Plant; frc-5, industrial products, Qingdao Lianmei Chemical; dimethylolpropane Acid (dmpa), chemically pure, Beijing Lin's refined new materials; diethylene glycol (ex), chemically pure, Shanghai Gaoqiao Chemical Factory; dibutyltin dilaurate (t-12), stannous octoate (t-9) ), Analytically pure, Beijing No. 3 Chemical Factory; triethylamine (tea), analytically pure, Shanghai Ningxin Chemical Reagent Factory; acetone.
2. Synthesis process
The polyether n-210 and ipdi after vacuum dehydration are metered into a three-necked flask, mixed evenly, and then heated to about 90 ° C. After 2 hours of reaction, add appropriate amount of hydrophilic chain extender (dmpa), chain extender diethylene glycol (ex), appropriate amount of acetone and a few drops of catalyst (t-12, t-9). Appropriate amount of flame retardant chain extender frc-5, the temperature continues to be maintained at about 70 ℃, after 5h the reaction is over and the material is discharged. The prepolymer is neutralized with an appropriate amount of triethylamine and then added with water to emulsify at high speed to obtain an emulsion.
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