Glycidyl Methacrylate (GMA) is a monomer with both an acrylate double bond and an epoxy group. The acrylate double bond has high reactivity and can undergo self-polymerization or copolymerization with many other monomers; while the epoxy group can react with hydroxyl, amino, carboxyl or acid anhydride to introduce more Functional groups, thereby bringing more functionality to the product. Therefore, GMA is widely used in organic synthesis, polymer synthesis, polymer modification, composite materials, UV curing materials, coatings, adhesives, leather, chemical fiber papermaking, printing and dyeing, etc.
Glycidyl methacrylate and its application GMA technical indicators
The CAS number of GMA is 106-91-2, molecular weight 142.15, density 1.068@25ºC, viscosity 2.7cps@15.5ºC, boiling point 189ºC, flash point 85ºC, refractive index 1.4473. It is a colorless, transparent and low-viscosity liquid at room temperature, soluble in common organic solvents but insoluble in water. Due to the use of epichlorohydrin in the production process, there is usually a small amount of epichlorohydrin remaining in the product.
GMA has the typical smell of acrylate and is irritating to the skin and eyes. Both liquids and gases are flammable. Polymerization may occur at higher temperatures, so a polymerization inhibitor must be added.
Synthesis of glycidyl methacrylate and its application GMA
The synthesis of GMA usually adopts a one-step method of phase transfer or a two-step method of esterification and ring closure.
The one-step method has simple operation and short reaction time, but requires the entire reaction system to be anhydrous, requires high purity of the sodium salt, and has the disadvantages of excessive dosage of epichlorohydrin and complicated subsequent processing. Most companies such as the American Dow Company and domestic Runao Chemicals use a one-step process. The one-step method is to first perform an acid-base neutralization reaction between methacrylic acid and sodium hydroxide or sodium carbonate in an organic solvent to prepare sodium methacrylate. After drying, in the presence of a phase transfer catalyst, it is then mixed with epichlorohydrin according to the After a certain proportion of dehydration, reaction at high temperature, distillation under reduced pressure and water washing, the GMA product is obtained.
The two-step method is to first perform a ring-opening esterification reaction between methacrylic acid and epichlorohydrin under the action of a ring-opening catalyst to generate 2-hydroxy-3-chloropropyl methacrylate. Then, 2-hydroxy-3-chloropropyl methacrylate is subjected to dehydrochlorination ring-closure reaction in the presence of sodium hydroxide solid or aqueous solution, or is refluxed in an acetone solution of potassium carbonate to obtain the product.
In addition, there are methods such as catalytic transesterification method, lipase catalytic synthesis method, selective epoxidation method and epoxy group transfer reaction method.
Figure 1 Schematic diagram of the reaction between epoxy group and amine group, carboxyl group and hydroxyl group
Glycidyl methacrylate and its applications Application of GMA in powder coatings
Acrylic powder coating is a major category of powder coatings. According to the different curing agents used, it can be divided into: hydroxyl acrylic resin, carboxyl acrylic resin, glycidyl acrylic resin, and amido acrylic resin. Among them, glycidyl acrylic resin is the most commonly used powder coating resin. It can be formed into films with curing agents such as polyhydroxy acids, polyamines, polyols, polyhydroxy resins, and hydroxy polyester resins.
GMA-type acrylic resin is usually synthesized by free radical polymerization of methyl methacrylate, glycidyl methacrylate, butyl acrylate, and styrene, and dodecyl dibasic acid is used as the curing agent. Powder coating has good properties. The synthesis process can use benzoyl peroxide (BPO) and azobisisobutyronitrile (AIBN) or their mixture as initiators. The amount of GMA has a great impact on the performance of the coating film. If the dosage is too small, the cross-linking degree of the resin will be low, the cured cross-linking points will be few, the cross-linking density of the coating film will be insufficient, and the impact resistance of the coating film will be poor.
Glycidyl methacrylate and its applications Application of GMA in polymer modification
Due to the presence of a highly active acrylate double bond, GMA can be grafted onto polymers, and the epoxy groups carried by GMA can react with a variety of other functional groups to form functionalized polymers. . GMA can be grafted to modified polyolefins using methods such as solution grafting, melt grafting, solid phase grafting, and radiation grafting, or it can also form functionalized copolymers with ethylene, acrylates, etc. These functionalized polymers can be used as toughening agents to toughen engineering plastics or as compatibilizers to improve the compatibility of blend systems.
The commonly used initiator for graft modification of polyolefins by GMA is dicumyl peroxide (DCP). Some people also use benzoyl peroxide (BPO), acrylamide (AM), 2,5-di-tert. Initiators such as butyl peroxy-2,5-dimethyl-3-hexyne (LPO) or 1,3-di-tert-butyl cumene peroxide. When AM is used as an initiator, it has a significant effect on reducing the degradation of polypropylene. Grafting polyolefin with GMA will lead to changes in the polyolefin structure, thereby causing changes in the surface properties, rheological properties, thermal properties, and mechanical properties of the polyolefin. GMA graft-modified polyolefin increases the polarity of the molecular chain and also increases the surface polarity. Therefore, the surface contact angle decreases as the grafting rate increases. Due to the changes in the polymer structure after GMA modification, it will also affect its crystallization properties and properties.Chemical performance.
Glycidyl methacrylate and its applications Application of GMA in resin copolymerization
Arkema’s LOTADER series products are random copolymer products of ethylene, acrylate and GMA, with a GMA content of up to 8%. It has good compatibility with polyolefin products, and has good bonding force with polycarbonates such as various polymers, metals, paper and glass.
The terpolymer of GMA, styrene, and acrylonitrile can be used as a chain extender for recycled materials such as PA, PC, PBT, and PET, and as a matting agent for alloys such as PC/ABS, PA/ABS, and PBT/ABS. Agents, as well as compatibilizers for ABS/PBT, ABS/PET, PC/ABS and other alloys.
Glycidyl methacrylate and its applications Application of GMA in UV curing resin synthesis
GMA can be used in UV light-curing resin synthesis through a variety of synthesis routes. One method is to first obtain a prepolymer containing carboxyl or amino groups on the side chain through free radical polymerization or condensation polymerization, and then use GMA to react with these functional groups to introduce photosensitive groups to obtain a photocurable resin. In the first copolymerization step, different comonomers can be used to obtain polymers with different final properties. Feng Zongcai and others synthesized hyperbranched polymers by reacting 1,2,4-trimellitic anhydride and ethylene glycol, and then introduced photosensitive groups through GMA, finally obtaining a photocurable resin with good alkali solubility. Lu Tingfeng and others used poly-1,4-butylene adipate, toluene diisocyanate, dimethylol propionic acid and hydroxyethyl acrylate to first synthesize a prepolymer with photoactive double bonds, and then introduced it through GMA More photocurable double bonds are neutralized with triethylamine to obtain a water-based polyurethane acrylate emulsion.
Figure 2 Synthesis circuit diagram of light-cured water-based polyurethane emulsion
Another method is to first copolymerize GMA and other monomers to obtain a copolymer with epoxy functional groups in the side chain, and then react acrylic acid or methacrylic acid with the epoxy functional groups to obtain a copolymer with optical properties. Cure reactive resin products.
Glycidyl methacrylate and its applications Application of GMA in UV curable powder coatings
UV curing powder coating is a new technology that combines UV curing technology with traditional powder coating curing technology. It combines the advantages of UV curing and powder coating and is widely used in materials such as medium density fiberboard (MDF) and metal. of painting.
Ultraviolet curing powder coatings can first synthesize methylpyridine carboxyl polyester, and then react with GMA and terminal carboxyl groups to produce UV curing powder coatings with photosensitive groups. Xiong Wei et al. used p-dimethylol cyclohexane and adipic acid to generate carboxyl-terminated polyester resin through esterification reaction. Zhou Shibiao et al. used free radical copolymerization of methyl methacrylate, ethyl acrylate and butyl acrylate to obtain polyester resin containing carboxyl groups. Carboxyl prepolymer. These prepolymers are then reacted with GMA to introduce photoactive groups.
Figure 3 Synthetic route of light-cured powder coating resin
Glycidyl methacrylate and its applications Application of GMA in macroporous polymers
Use GMA as the monomer, divinylbenzene (DVB) and/or triallyl isocyanurate (TAIC) as the cross-linking agent, and use toluene and n-heptane as the porogen through suspension polymerization. Macroporous copolymers can be synthesized.
Because the macroporous polymer has active epoxy groups, it is easy to be chemically modified and various adsorbents can be prepared by immobilizing ligands. For example, the solid-loaded polymyxin can treat hyperlipidemia, and the solid-loaded ornithine can treat systemic lupus erythematosus. Macroporous polymers can also be functionalized with mannitol to obtain adsorbents with polyhydroxyl groups.
In addition to the above applications, GMA can also be used in adhesives, UV pressure-sensitive adhesives, automotive coatings, water-based coatings, etc. Generally speaking, because glycidyl methacrylate (GMA) itself contains acrylate double bonds and epoxy groups, its application range is very wide.
