The Development of The New Unsaturated Polyester!

      In recent years, the research progress of unsaturated polyester resin in foreign countries is rapid, and new products are emerging in an endless stream. For example: Low shrinkage resin, corrosion resistant resin, strong toughness resin, low water absorption unsaturated polyester resin, transparent unsaturated polyester resin, low free styrene residual unsaturated polyester resin, PET unsaturated polyester resin, low volatility resin, gel coat resin, foam unsaturated polyester resin, glass fiber reinforced plastic boat resin, heat resistant UPR resin and light curing UPR resin . The following will be some new unsaturated polyester resin performance and application analysis. These include low shrinkage resin, corrosion resistant resin, low water absorption type unsaturated polyester resin, low volatility resin, water unsaturated polyester resin WCUP. 

      The so-called low shrinkage resin, the use of thermoplastic resin to reduce and moderate the curing shrinkage of UPR, has been widely used in SMC manufacturing. The commonly used low shrinkage agents are polystyrene, polymethyl methacrylate and diallyl phthalate polymer. At present, in addition to polystyrene and its copolymers, polycaprolactone (LPS-60), modified polyurethane and cellulose acetate butyl ester have been developed abroad. The new low shrinkage additive (LPAS) of UP resin has been studied by the Japanese Oil and Oil Research Institute. This new type of LPAS contains elastic segments and can be compatible with UP resin. It is used in the molding process of UP resin SMC/BMC, which makes the product surface gloss, low shrinkage rate and good coloring performance. The Ohio State University in the United States studied the low temperature curing UP/ST/LPAS system containing modified thermoplastic LPAS additives from dilatation, morphology and structure, and introduced co-accelerator DVB and the second monomer trimethylol propane trimethacrylate (TMPT-MA) into the low temperature curing system. The shrinkage of the resin during the curing process can be better controlled. In Canada, thermoplastic PVAC as a low shrinkage agent LPAS was added to the UP resin, which also solved the shrinkage problem well. By adding a low shrinkage agent solid, the bonding strength of the unsaturated polyester component can reach 2.45MPa, and the linear shrinkage coefficient can be reduced to 0.32%. Japan's Monsanto Industrial Chemical company used polyvinyl acetate (DenkaASRM4) as a low shrinkage additive to develop a shrinkage of only 0.096% of the molding plastics. 

      Two, corrosion resistant resin Corrosion resistant resins are bisphenol A type unsaturated polyester, phthalic acid type resin and rosin modified unsaturated polyester. It is reported that the 8250 vinyl ester resin developed by the Japanese Ube Company not only has good corrosion resistance, but also has a storage period of 14 months. In Japan, glass fiber composites resistant to 25%NaCl solution were prepared by using resorcine-type, bisphenol A type or vinyl ester type unsaturated polyester resins, respectively. Strong and ductile resin has been paid more and more attention. At present, the method of adding saturated resin is mainly used in foreign countries to improve toughness. Such as adding saturated polyester, styrene butadiene rubber and carboxylated nitrile butadiene rubber. The United States Amoco chemical company uses the end of the hydroxy-containing unsaturated polyester and diisocyanate reaction made of resin, its toughness can be increased by 2 to 3 times, the product brand Xycon. The SD resin developed by Showa Polymer Company in Japan has good toughness and can be widely used in the manufacture of artificial marble. In Brazil, unsaturated polyester resin containing glycidyl methacrylate (GMA) was modified by graft copolymerization of flexible polysiloxane segments (APTS) to obtain resin with high impact strength and glass fiber reinforced resin. Polish University found that with the increase of TDI content, the viscosity of TDI-modified unsaturated polyester resin increased, and when the TDI mass fraction reached 3%, the resin had good thixotropy. When 4, 4-dimaleimide diphenylmethane (BM) was added to the modified resin, the compressive strength of the modified resin was increased to 159MPa, the glass transition temperature was 184℃, the decomposition temperature was 280℃, and the curing speed was also accelerated. 

       On the low water absorption type unsaturated polyester resin, Germany made of IR radiation curing unsaturated polyester resin, the curing residence time of the composite material is short when IR radiation curing, and the water absorption of the product is reduced. Transparent unsaturated polyester resin, by the Japanese Kao company developed A tensile strength of 44.1MPa, transmission of 48%, and has good heat resistance of bisphenol A transparent unsaturated polyester resin artificial marble. The unsaturated polyester resin with low free styrene residue has been developed by Japan NOF joint company with good anti-yellowing type unsaturated polyester resin, which can be used as FRP, SMC, BMC resin, and the residual styrene mass fraction after 130℃ curing is only 0.03%. PET type unsaturated polyester resin results are more, the United States and Egypt with PET(polyethylene terephthalate) waste alcohol hydrolysis synthesis of unsaturated polyester resin, by adjusting the reaction can be obtained curing temperature of 74 ~ 90℃, curing time is only a few minutes to more than 20 minutes can be arbitrarily selected between unsaturated polyester resin. South Korea has synthesized a series of unsaturated polyester resins obtained by various alcoholysis, and through various alcohol components to control the degree of PET alcoholysis, control the gel time and brittleness of PET unsaturated polyester resin, successfully used in SMC and BMC. Foaming unsaturated polyester resin also jumped into the eye, unsaturated polyester resin as a matrix of foam plastic, toughness, strength is better than foam PS, processing is easier than foam PVC, adding flame retardants can also make its flame retardant and aging resistance, the cost is lower than foam polyurethane plastic. Foaming unsaturated polyester resin is mainly foamed by chemical foaming agents. There is not much literature on the use of physical blowing agents. The main physical blowing agent is freon, but it pollutes the environment. Chemical blowing agents mainly include: isocyanates, azo, sulfonyl hydrazides, carbonic anhydrides.

        Four, low volatile resin Low volatile resin and gelcoat resin varieties more. Low volatile resins are currently being developed abroad, the general requirement is that the styrene content in the air around the workshop must be less than 50ug/g. The method is as follows: adding the surface film forming agent to reduce the volatilization of styrene; High boiling point crosslinker was added instead of styrene. By combining cyclopentadiene and its derivatives with uPR, the low molecular mass can be achieved to reduce the use of styrene. Foreign BYKChemie company developed a new additive LPX-5500, which can reduce the volatilization of styrene by 70 ~ 90%. Gelcoat resin is a special resin for making gelcoat layer of FRP products. Styrene is still the most suitable monomer for UP resins at present. However, the vapor pressure of styrene at room temperature is high and it is easy to volatilize, especially in the process of gelcoat and backing reinforcement layer of FRP products made by hand paste or jet molding. When its vapor concentration exceeds a certain amount (> 50ug/g) can irritate the human eye and nose mucosa, causing dizziness, nausea and other symptoms. Therefore, the research and development of low styrene sporadic gelcoat resin is very necessary and has very important practical significance. American Sartomer Technology company has developed low VOC UPR components containing maleic anhydride monomer, and applied to gel coatings, adhesives, laminating resins or molding resins. The United States and Germany have developed unsaturated polyester resin and its components without (styrene) monomers, which can be used in open casting, gel coatings and electronics industries, respectively.

       Five, water-containing unsaturated polyester resin WCUP water-containing unsaturated polyester resin WCUP is rising. Aqueous unsaturated polyester resin WCUP is a new type of resin with water as filler that came out in the 1950s. In addition to its significant low-cost characteristics, the resin has many excellent properties, such as low heat release during curing, small volume reduction, flame retardant and easy processing and forming. It can be used in artificial wood, decorative materials, foam products, porous materials, building materials, polyester concrete, wetting agents and coatings. In 1967, Horie et al. reported for the first time the preparation of stable aqueous unsaturated polyester resin emulsion with alkaline substances such as sodium hydroxide, which was called the polyester salt process. In recent years, the study of polyphase/multi-component polymer systems by dynamic method has attracted great attention in the world. Nguven-Thue et al studied the relationship between dynamic rheological behavior and morphological structure, and subsequently this kind of research has become a hot spot in the study of rheology of many polymer systems. Kick-walczak, Ewa reviews the latest developments in unsaturated polyester resins that meet EU requirements. Compared with the international industry, China's unsaturated polyester resin industry has developed rapidly in the past 10 years, but the gap is still large compared with foreign countries, the production scale is small, the product quality is low, the variety model is only about 500, the shortage of raw materials, the quality of some new raw materials cannot meet the requirements, and the investment in the development of new varieties of technology is not enough. Collaboration between research institutes and production and application units needs to be further strengthened. In particular, many small factories, poor testing means, product quality is difficult to be guaranteed, the current low-grade competition to China's FRP product market has brought a lot of hidden dangers, should cause enough attention to the relevant parties.