Let's talk about the analysis of the performance and application of five unsaturated polyester resins. These include low shrinkage resins, corrosion resistant resins, unsaturated polyester resins, low volatility resins, and unsaturated polyester resins WCUP.
(1) Low shrinkage resin
So-called low-shrinkage resin, which uses thermoplastic resin to reduce and ease the curing shrinkage of UPR, has been widely used in SMC manufacturing. Commonly used low shrinkage agents are polystyrene, polymethyl methacrylate and diallyl phthalate polymers. At present, in addition to the use of polystyrene and its copolymers abroad, polycaprolactone (LPS-60), modified polyurethane and butyl cellulose acetate have been developed. The Research Institute of Chemical Products of Japan Oil and Fats Co., Ltd. has studied the new low-shrinkage additive (LPAS) of UP resin. This new type contains elastic segments and segments compatible with UP resin. It is used in the molding process of UP resin SMC/BMC Medium makes the surface gloss and shrinkage of the product low, and the coloring performance is good. Ohio State University has studied the low-temperature curing UP/ST/LPAS system containing modified thermoplastic LPAS additives from dilatology, morphology and structure, and introduced Co-accelerator DVB into the low-temperature curing system, and the second Body trimethylolpropane trimethacrylate (TMPT-MA) makes the shrinkage of the resin in the curing process better controlled. Canada added thermoplastic PVAC as a low shrinkage agent LPAS to UP resin, which also solved the shrinkage problem well. Japan Showa Polymer Co., Ltd. can increase the bonding strength of unsaturated polyester composition to 2.45MPa and linear shrinkage coefficient to 0.32% by adding low shrinkage agent solids. Japan's Monsanto Industrial Chemical Company used polyvinyl acetate (DenkaASRM4) as a low-shrinkage additive to develop a molding compound with a shrinkage of only 0.096%.
(2) Corrosion-resistant resin
Corrosion-resistant resins include bisphenol A unsaturated polyester, terephthalic acid resin and rosin modified unsaturated polyester. It is reported that the 8250 vinyl ester resin developed by Ube Corporation of Japan not only has good corrosion resistance, but also has a storage period of up to 14 months. Japan uses benzene type, bisphenol A type or vinyl ester type unsaturated polyester resin to make glass fiber composite materials resistant to 25% NaCl aqueous solution. Strong and tough resins are getting more and more attention. At present, foreign countries mainly adopt the method of adding saturated resin to improve the toughness. Such as the addition of saturated polyester, styrene-butadiene rubber and carboxyl-terminated nitrile rubber. American Amoco Chemical Co., Ltd. adopts a resin made by the reaction of unsaturated polyester containing hydroxyl group at the end and diisocyanate, its toughness can be increased by 2 to 3 times, and the trade name is Xycon. The SD resin developed by Japan Showa Polymer Company has good toughness and can be widely used to manufacture artificial marble. In Brazil, APTS is modified by graft copolymerization to modify unsaturated polyester resins containing glycidyl methacrylate (GMA) to obtain resins with high impact strength and glass fiber reinforced resins. The University of Poland found that as the TDI content increases, the viscosity of the unsaturated polyester resin modified by TDI increases. When the TDI mass fraction reaches 3%, the resin has good thixotropy. When 4,4-dimaleimidodiphenylmethane (BM) is added to the resin for modification, the compressive strength of the modified resin is increased to 159MPa, the glass transition temperature is 184°C, and the decomposition temperature is increased to 280°C At the same time, the curing speed is accelerated accordingly.
(3) Low water absorption unsaturated polyester resin
Regarding the low water absorption type unsaturated polyester resin, Germany made IR radiation-cured unsaturated polyester resin, which has a short curing residence time of the composite material during IR radiation curing, and the water absorption rate of the product is reduced.
Transparent unsaturated polyester resin, developed by Kao Corporation of Japan has a tensile strength of 44.1MPa, a transmittance of 48%, and has good
Heat-resistant bisphenol A type transparent unsaturated polyester resin artificial marble. The unsaturated polyester resin with low free styrene residue has been developed by Japan NOF United Company with a good anti-yellowing unsaturated polyester resin, which can be used as FRP, SMC, BMC resin, benzene residue after curing at 130 ℃ The ethylene mass fraction is only 0.03%. PET-type unsaturated polyester resin has more achievements. The United States and Egypt used PET (polyethylene terephthalate) waste alcoholysis to synthesize unsaturated polyester resin. By adjusting the reaction, the curing temperature can be 74～ At 90℃, the curing time is only a few minutes to more than 20 minutes of unsaturated polyester resin. South Korea synthesized a series of unsaturated polyester resins obtained from various alcoholysis products, and controlled the alcoholysis degree of PET through various alcohol compositions, and controlled the gel time and brittleness of PET unsaturated polyester resins. Used in SMC and BMC. Foamed unsaturated polyester resin also leaps into the eye. Unsaturated polyester resin as a matrix of foam plastic has better toughness and strength than foamed PS, and is easier to process than foamed PVC. Adding flame retardants can also make it flame retardant and It is resistant to aging and its cost is lower than that of foamed polyurethane plastic. Foaming unsaturated polyester resin foam mainly uses chemical foaming agent. There is not much literature on the use of physical blowing agents. The physical blowing agent is mainly freon but pollutes the environment. Chemical blowing agents mainly include: isocyanates, azos, sulfonyl hydrazides, carbonate anhydrides.
(4) Low volatility resin
There are many varieties of low volatility resin and gel coat resin. Low volatility resin is 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: adding surface film forming agent to reduce styrene volatilization; using high boiling point cross-linking agent to replace styrene; using cyclopentadiene and its derivatives in combination with uPR to make the low molecular mass, so as to achieve Reduce the use of benzene
The purpose of ethylene. Foreign BYK Chemie Company has developed a new type of auxiliary agent LPX-5500, which can reduce the styrene volatilization by 70-90%. Gel coat resin is a special resin for making gel coat layer of FRP products. Styrene is still the most suitable monomer currently used for UP resins. However, styrene has a high vapor pressure at room temperature and is easy to volatilize, especially in the process of making the gel coat layer of glass fiber reinforced plastic products by hand lay-up or injection molding process, and the backing reinforcement layer. When its vapor concentration exceeds a certain amount (>50ug/g), it will irritate people's eyes, nose and mucous membranes and cause symptoms such as dizziness and nausea. Therefore, the development of low-styrene dispersible gel coat resin is very necessary and of great practical significance. American Sartomer Technology Company developed a low VOC UPR composition containing maleic anhydride monomers, and used in gel coatings, adhesives, laminating resins or molding resins. The United States and Germany have developed unsaturated (styrene) monomer-free unsaturated polyester resins and their compositions, which can be used in opening casting, gel coating, and electronics industries, respectively.
(5) WCUP of water-containing unsaturated polyester resin
Water-containing unsaturated polyester resin WCUP is emerging. Water-containing unsaturated polyester resin WCUP is a new type of resin with water as filler that came out in the 1950s. In addition to its remarkable low-cost characteristics, this resin also has many excellent properties, such as small heat release during curing, small volume shrinkage, flame retardant and easy processing and molding. It can be used in artificial wood, decorative materials, foam products, porous materials, building materials, polyester concrete, infiltrating agents and coatings. In 1967, Horie et al. reported for the first time the preparation of stable aqueous unsaturated polyester resin emulsions with alkaline materials such as sodium hydroxide. This method is called the polyester salt formation method. In recent years, the use of dynamic methods to study multiphase/multicomponent polymer systems has been cited internationally.
With great attention, Nguven-Thue et al. studied the relationship between dynamic rheological behavior and morphological structure. Since then, such research has become a hotspot in the research of many polymer systems. Kicko-walczak, Ewa reviewed the latest developments in unsaturated polyester resins that meet EU requirements.
Compared with the international industry, although China's unsaturated polyester resin industry has developed rapidly in the past 10 years, it still has a large gap compared with foreign countries. It has a small production scale and low product quality. There are only about 500 varieties and models, and there is a shortage of raw materials. The quality of some new raw materials does not meet the requirements, the investment in the development of new varieties and technologies is not enough, and the collaboration between scientific research institutes and production application units needs to be further strengthened