The properties and applications of five unsaturated polyester resins are analyzed

(i) Low-shrink resins
so-called low-shrink resins, using thermoplastic resins to reduce and ease the curing contraction of UPR, have been widely used in SMC manufacturing. Commonly used low-shrink agents are polystyrene, polymethyl acrylates and benzodialyceride polymers. At present, in addition to the use of polystyrene and its co-polymers, but also developed polychloric acid esters (LPS-60), modified polyurethane and cellulose acetate and other

. The Japan Institute of Grease (Plant) Finished Products studied the new low shrink additive (LPAS) of UP resin, which contains elastic chain segments and chain segments that can be compatible with UP resins, and is used in the molding process of UP resin SMC/BMC, which makes the surface of the product shiny, low shrinkage, and good coloring performance. Ohio State University studied the thermoplastic LPAS additives containing modified thermoplastic LPAS to cure up/ST/LPAS systems at low temperatures, and introduced Co-promoter DVB in cryogenic curing systems, as well as secondary monoxymethyl propylene trimethyl acrylates (TMPT-MA), so that the resin contraction in the curing process is better controlled. Canada added thermoplastic PVAC as a low shrink agent LPAS to the UP resin, which also solves the contraction problem well. By adding low-shrink solids, Japan's Showa High Complex company can reduce the bonding strength of unsaturated polyester compositions to 2.45MPa, reducing the linear shrinkage factor to 0.32%. Monsanto Industrial Chemistry of Japan used ethylene poly acetate (DenkaASRM4) as a low-shrink additive to develop a molded plastic with a shrinkage rate of only 0.096%.
(ii) corrosion-resistant resins
-resistant resins have bisphenol A unsaturated polyester, benzoic acid resin and pine-modified unsaturated polyester. It is reported that the Japanese Ministry of Space developed 8250 ethylene ester resin, not only good corrosion resistance, but also storage period can reach 14 months. Japan uses styrene, biphenol A or vinyl ester-type unsaturated polyester resins to make fiberglass composites resistant to 25% NaCl aqueous solutions. Strong tough resin has been paid more and more attention, at present, foreign countries mainly use the method of adding saturated resin to improve toughness. Such as the addition of saturated polyester, butyl benzene rubber and end-steryl butyl rubber. Amoco Chemical Corporation of the United States uses end-containing unsaturated polyester and diocyanate reaction resin, its toughness can be improved by 2 to 3 times, the commercial brand name Xycon. The SD resin developed by Japan's Showa Polymers is resilient and can be widely used in the manufacture of artificial marble. Brazil modified the flexible polysilicae chain segment (APTS) to an unsaturated polyester resin containing methyl acrylic shrinkage glycerides (GMA) by copolymering by joining, resulting in a high impact strength resin and glass fiber-reinforced resin. The University of Poland found that as the TDI content increased, the viscosity of the TDI modified unsaturated polyester resin increased, and when the TDI mass score reached 3%, the resin had good tentacles. When the resin is modified with 4,4-two Malayamide-based diphenyl diphenyl methane (BM), the compression strength of the modified resin is increased to 159MPa, the glacification temperature is 184 degrees C, the decomposition temperature is increased to 280 degrees C, and the curing speed is accelerated accordingly.
(iii) Low absorbent type unsaturated polyester resin
about low absorbent type unsaturated polyester resin, Germany made of IR radiation curing unsaturated polyester resin, its solidification time of composite materials when IR radiation curing is short, product water absorption rate is reduced.
transparent unsaturated polyester resin, the extrusive strength of 44.1MPa developed by Japan Flower King Company, transmission rate of 48%, and has good heat resistance of bisphenol type A transparent unsaturated polyester resin artificial marble. The unsaturated polyester resin with low free styrene residue has been developed by Japan's NOF joint company with good anti-yellow variant unsaturated polyester resin, which can be used as FRP, SMC, BMC resin, 130 degrees C cured after residual styrene mass fraction of only 0.03%. PET type unsaturated polyester resin results more, the United States and Egypt with PET (polythyl xylene glycol esters) waste alcohol solution synthesis of unsaturated polyester resin, through the adjustment reaction can be obtained curing temperature of 74 to 90 degrees C, curing time is only a few minutes to more than 20 minutes can be arbitrarily selected unsaturated polyester resin. South Korea synthesized a series of unsaturated polyester resins obtained by various alcohol solutions, and through a variety of alcohol compositions to control pet's alcoholization degree, control PET type unsaturated polyester resin gel time and brittleness, successfully used in SMC and BMC. Foaming unsaturated polyester resin also jumped into view, unsaturated polyester resin as a base of foam, toughness, strength than foam PS better, processing than foam PVC is easier, add flame retardants, etc. can also make it flame retardant and anti-aging, the cost is lower than foam polyurethane plastic. Foaming unsaturated polyester resin foaming mainly uses chemical foaming agent. There is little literature on the use of physical foaming agents. Physical foaming agents are mainly Freon but pollute the environment. Chemical foaming agents are: isocyanate, acetic nitrogen, sulfonate, carbonate.
(iv) low volatile resins
more varieties of low volatile resins and rubber coating resins. Low volatile resin is currently being developed abroad, the general requirement is that the workshop around the air styrene content must be less than 50ug/g. The method is: add epidural forming agent to reduce styrene volatility; The styrene was replaced by adding a high boiling point crosslinker; The use of cyclodialyene and its derivatives combined with uPR, so that low molecular quality, so as to reduce the use of styrene. Foreign BYK Chemie company developed a new additive LPX-5500, can reduce styrene volatilization by 70 to 90%. Plastic clothing resin is a special resin for the production of glass and steel products. Styrene is still the most suitable monosome for UP resin selection. However, styrene at room temperature steam pressure is high, easy to volatilization, especially in the use of hand paste or injection molding process to make fiberglass products, and the backing of the reinforced layer process is more volatile. When its vapor concentration exceeds a certain amount (>50ug/g), it stimulates the mucous membranes of the eye and nose to cause dizziness, nausea and other symptoms. Therefore, it is very necessary and of great practical significance to develop low styrene distributive rubber resin. Sartomer Technologies of the United States has developed a low VOC UPR component containing Malay anhydride monomer and applies it to gel coatings, adhesives, laminated resins or molded resins. The United States and Germany have developed unsaturated polyester resins and their components without monomers, which can be used in open casting, gel coatings and electronics industries respectively.
(v) water-containing unsaturated polyester resin WCUP
water-containing unsaturated polyester resin WCUP is emerging. Water-containing unsaturated polyester resin WCUP is a new type of resin made from water introduced in the 1950s. In addition to its significant low cost characteristics, the resin also has many excellent performance, such as low heat release when curing, small volume shrinkage, flame retardant and easy to mold. It can be used in man-made wood, decorative materials, foam products, porous materials, building materials, polyester concrete, immersion agents and coatings. In 1967, Horie et al. first reported the preparation of a stable water-containing unsaturated polyester resin emulsion using alkaline substances such as sodium hydroxide, a method known as polyester salting. In recent years, the study of multiphase/multi-part polymer system with dynamic method has attracted great attention in the world, Nguven-Thue and so on have studied the relationship between dynamic fluid behavior and morphological structure, and since then such research has become the focus of many polymer system fluidization research. Kicko-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 in the past 10 years, although the development of rapid, but compared with foreign countries, the gap is still large, small production scale, low product quality, variety models only about 500, raw materials shortage, some new raw materials quality can not meet the requirements, new varieties of technology development investment is not enough, research institutes and production application units to be further strengthened collaboration.
In particular, many small factories, poor detection means, product quality is difficult to be guaranteed, the current low-quality competition to China's glass and steel products market brings a lot of hidden dangers, should cause the relevant parties to pay enough attention.
。