Study On Preparation Of Phenolic Foam

The ever-increasing energy consumption represents the fast developments in people's life and technology. Thus, energy-saving outerwall with heat-insulation attracts much attention in recent years. The development of efficient wall insulation materials can effectively reduce the coal, oil, electricity and other energy consumption, and can reduce the emission of greenhouse gases, dust and other pollutants. Phenolic foam have several advantages such as light, non-toxic, fire-retardant, low smoke, low thermal conductivity, corrosion resistance, long-term durability, sound absorption, easy molding, and etc., which has great practical value.Many factors, including different ratio of raw materials, the amount of catalyst, temperature, time and others have been investigated for the performance of phenolic resin. The results show that: when formaldehyde and phenol functional group ratio is 1.2: 1, the amount of catalyst is 1% of the phenol, the reaction system is reacted at 65 ? in 3 h and at 85 ? in 2-2.5 h, reaction system is safe and efficient. The resin viscosity is 5000-7000 mPa·s and has good appropriate solid content and moderate activity. At the same time, this process does not produce any wastewater, which is environmentally friendly.In the foaming and curing process, we have concluded an optimal recipe of different kinds and ratios of different defoamers, emulsifiers, foaming agent, gradient foaming agent and a curing agent in the process of foaming. The results showed that: The best recipe should be 4‰ 5000 mPa·s silicone, 5 parts NL20, 6 parts of 30-60 ?petroleum ether, 8 parts mixed acid. In this formula, the foam density is about 55 kg/m3 with a moderate density, fine cell, high closed-cell rate, higher strength and lower water absorption ratio.In order to improve the crisp feature of phenolic foam, the effects of different amounts of toughening agent have been studied. The results showed that: when using 5 parts polyether polyols 240 as a toughening agent, the tensile strength of the foam increased significantly. Introducing 10 parts of cardanol into the phenol resin can not only enhance the toughness of the foam, but also meet the requirements of tensile strength and water absorption.Finally, a method of fabricating low viscosity resin has been designed by adding small agents to high viscosity resin. The results showed that: when adding 5 parts of viscosity reducer, resin viscosity reduced from 30000 to 5000-6000 mPa·s. The low viscosity resin has good adaptability with foaming process with good performance, like uniform density, high closed-cell rate, and high tensile strength.