Unsaturated polyester resin has made rapid progress in recent years, and new products emerge in an endless stream, such as: low shrinkage resin, corrosion resistant resin, strong toughness resin, low water absorption unsaturated polyester resin, transparent unsaturated polyester resin, low free styrene Residual amount of unsaturated polyester resin, PET type unsaturated polyester resin, low volatile resin, gel coat resin, foamed unsaturated polyester resin, FRP boat special resin, heat resistant UPR resin and photocurable UPR resin.
The following is an analysis of the properties and applications of five unsaturated polyester resins. These include low shrinkage resins, corrosion resistant resins, low water absorption unsaturated polyester resins, low volatility resins, and water-unsaturated polyester resins WCUP.
(1) Low shrinkage resin
The so-called low-shrinkage resin, which uses a thermoplastic resin to reduce and alleviate the curing shrinkage of the UPR, has been widely used in the manufacture of SMC. Commonly used low shrinkage agents are polystyrene, polymethyl methacrylate and diallyl phthalate polymers. At present, in addition to polystyrene and its copolymers, polycaprolactone (LPS-60), modified polyurethane and cellulose acetate butyl ester have been developed. The Japan Oils and Fats Research Institute has studied the new low shrinkage additive (LPAS) of UP resin, which is a new type of elastic segment and a segment compatible with UP resin. It is used in the molding process of UP resin SMC/BMC. The surface of the product is low in gloss, low in shrinkage, and good in coloring performance. Ohio State University from the expansion, morphology and structure, studied the low temperature curing UP/ST/LPAS system with modified thermoplastic LPAS additive, and introduced Co-promoter DVB in the low temperature curing system, and the second single Trimethylolpropane trimethacrylate (TMPT-MA) allows for better control of shrinkage of the resin during curing. Canada's addition of thermoplastic PVAC to the low-shrinkage LPAS into the UP resin also solves the shrinkage problem. By adding a low shrinkage agent solid, Japan Showa Polymers can achieve an adhesive strength of 2.45 MPa and a linear shrinkage factor of 0.32%. Monsanto Industrial Chemical Co., Japan 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 type unsaturated polyester, phthalic acid type resin, and rosin modified unsaturated polyester. It is reported that the 8250 vinyl ester resin developed by Japan Ube Co., Ltd. not only has good corrosion resistance, but also has a storage period of up to 14 months. Japan uses a benzene type, a bisphenol A type or a vinyl ester type unsaturated polyester resin to form a glass fiber composite material resistant to a 25% NaCl aqueous solution. Strong toughness resins have received increasing attention. At present, foreign countries mainly use saturated resin to improve toughness. Such as the addition of saturated polyester, styrene butadiene rubber and carboxylated nitrile rubber. Amoco Chemical Company uses a resin made by reacting a terminal hydroxyl group-containing unsaturated polyester with a diisocyanate, which can increase the toughness by 2 to 3 times, and the brand name is Xycon. The SD resin developed by Japan Showa Polymer Co., Ltd. has good toughness and can be widely used in the manufacture of artificial marble. In Brazil, a flexible polysiloxane segment (APTS) is modified by graft copolymerization to an unsaturated polyester resin containing glycidyl methacrylate (GMA) to obtain a resin having high impact strength and a glass fiber reinforced resin. The University of Poland found that as the TDI content increases, the viscosity of the TDI-modified unsaturated polyester resin increases, and when the TDI mass fraction reaches 3%, the resin has good thixotropy. When 4,4-dimaleimidodiphenylmethane (BM) was added to the resin for modification, the compressive strength of the modified resin was increased to 159 MPa, the glass transition temperature was 184 ° C, and the decomposition temperature was increased to 280 ° C. At the same time, the curing speed is also accelerated accordingly.
(3) Low water absorption type unsaturated polyester resin
Regarding the low water-absorbent unsaturated polyester resin, the IR radiation-curable unsaturated polyester resin is made in Germany, and the curing time of the composite material is short when the IR radiation is cured, and the water absorption rate of the product is lowered.
For the transparent unsaturated polyester resin, a bisphenol A type transparent unsaturated polyester resin artificial marble having a tensile strength of 44.1 MPa, a transmittance of 48%, and good heat resistance was developed by Kao Corporation of Japan. The unsaturated polyester resin with low free styrene residue has been developed by Japan NOF Co., Ltd. to have a good anti-yellowing unsaturated polyester resin, which can be used as FRP, SMC, BMC resin, and residual benzene after curing at 130 °C. The ethylene mass fraction is only 0.03%. PET type unsaturated polyester resin has many achievements. In the United States and Egypt, PET (polyethylene terephthalate) waste alcoholysis is used to synthesize unsaturated polyester resin, and the curing temperature can be obtained by adjusting the reaction to 74~ At 90 ° C, the curing time is only a few minutes to more than 20 minutes of optional unsaturated polyester resin. Korea has synthesized a series of unsaturated polyester resins obtained from various alcoholysis materials, and controlled the degree of alcoholysis of PET through various alcohol compositions, and controlled the gel time and brittleness of PET-type unsaturated polyester resins. Used for SMC and BMC. Foamed unsaturated polyester resin also jumps into the eye. Unsaturated polyester resin is used as the matrix foam. It has better toughness and strength than foamed PS. It is easier to process than foamed PVC. It can also be flame retardant by adding flame retardant. Anti-aging, the cost is lower than foamed polyurethane plastic. The foaming of the foamed unsaturated polyester resin mainly uses a chemical foaming agent. There are not many documents using physical blowing agents. Physical foaming agents are mainly freon but pollute the environment. The chemical foaming agents mainly include: isocyanates, azos, sulfonyl hydrazides, and carbonate anhydrides.
(4) Low volatile resin
There are many varieties of low-volatility resins and gel coat resins. Low-volatility resins are currently under development in foreign countries. The general requirement is that the styrene content in the air around the workshop must be less than 50 ug/g. The method comprises the following steps: adding a film forming agent to reduce styrene volatilization; using a high-boiling cross-linking agent instead of styrene; and combining cyclopentadiene and a derivative thereof with uPR to achieve low molecular mass, thereby achieving Reduce the purpose of using styrene. BYKChemie, a foreign company, has developed a new additive, LPX-5500, which can reduce the amount of styrene volatilization by 70-90%. Gel coat resin is a special resin for making a gel coat layer of FRP products. Styrene is still a suitable monomer for current UP resins. However, styrene has a high vapor pressure at room temperature and is easily volatilized, especially in the process of making a gel coat layer of a FRP product by a hand lay-up or a spray forming process, and being more volatile in the process of backing the reinforcing layer. When the vapor concentration exceeds a certain amount (>50ug/g), it may cause symptoms such as dizziness and nausea. Therefore, the development of low-styrene sporalen gel coat resin is very necessary and has very important practical significance. Sartomer Technologies of the United States has developed a low VOC UPR composition containing a maleic anhydride monomer and is applied to gel coats, adhesives, laminating resins or molding resins. Unsaturated polyester resins without styrene monomers and compositions thereof have been developed in the United States and Germany and can be used in open casting, gel coating and electronics industries, respectively.
(5) Water-containing unsaturated polyester resin WCUP
The water-containing unsaturated polyester resin WCUP is emerging. The water-based unsaturated polyester resin WCUP is a new type of resin made of water as a filler in the 1950s. In addition to its remarkable low cost characteristics, this kind of resin has many excellent properties, such as low heat release during curing, small volume shrinkage, flame retardancy and easy processing. It can be used in artificial wood, decorative materials, foam products, porous materials, building materials, polyester concrete, sizing agents and coatings. In 1967, Horie et al. first reported the preparation of a stable aqueous unsaturated polyester resin emulsion using an alkaline substance such as sodium hydroxide. This method is called a polyester salt formation method. In recent years, the study of multiphase/multicomponent polymer systems by dynamics has attracted great attention internationally. Nguven-Thue et al. studied the relationship between dynamic rheological behavior and morphological structure, and then such research has become more The hotspot of the rheological study of the term polymer system. Kicko-walczak, Ewa, reviews the recent advances 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, and the variety models are only about 500. The quality of some new raw materials is not up to standard, the investment in new varieties of technology is not enough, and the collaboration between research institutes and production and application units needs to be further strengthened.
Especially for many small factories and poor testing methods, product quality is difficult to be guaranteed. At present, this low-grade competition has brought many hidden dangers to China's FRP products market, which should be paid enough attention by relevant parties.