Hebei Messi Biology Co., Ltd. stated that surface modification is an important means to improve the application performance of magnesium hydroxide, improve applicability, expand the market and dosage. In the future, functionalization and specialization will become the main trend in the development of magnesium hydroxide. The market demand for this kind of surface modified magnesium hydroxide will be increasing.
1. Why does magnesium hydroxide need to be surface modified?
(1) Improve the dispersion of magnesium hydroxide
Ultrafine refinement is an important way to improve the quality of magnesium hydroxide, but the smaller the particle size of magnesium hydroxide, the higher the surface energy, the stronger the adsorption, and the more serious the agglomeration phenomenon. Through surface modification, the modifier can be directionally adsorbed on the surface of magnesium hydroxide, so that the surface has charge characteristics. Due to the repulsion of the same charge, magnesium hydroxide is not easy to agglomerate, thus achieving good dispersion in the matrix.
(2) Improve magnesium hydroxide compatibility
Through surface modification, the interfacial compatibility and affinity between magnesium hydroxide and organisms can be increased, thereby improving its product performance with composite materials such as rubber or plastics. For example: Magnesium hydroxide treated with titanate coupling agent has good compatibility with polymer molecules. At the same time, because the titanate coupling agent can form a molecular bridge between magnesium hydroxide molecules and polymer molecules, it enhances the interaction between organic polymers or resins and magnesium hydroxide, which can significantly improve thermoplastic composites. Mechanical properties of materials, such as impact strength, tensile strength, bending strength and elongation.
(3) Reduce the oil absorption value of magnesium hydroxide
Surface modification is an important means to reduce the oil absorption value of powder. After surface modification of magnesium hydroxide, the aggregated particles are reduced, the dispersion is improved, and the gaps between particles are reduced. At the same time, the coverage of the modified molecules on the surface of magnesium hydroxide reduces the gaps within the particles, and this coverage also changes the The surface properties of magnesium hydroxide weaken the surface polarity, reduce the friction between particles, and improve the lubricity, so they are packed more closely, the packing density increases, and the oil absorption value decreases.
(4) Expand the high-end application market of magnesium hydroxide
Magnesium hydroxide without surface modification has poor compatibility, is easy to agglomerate, and has poor application effects. As the dosage increases, these shortcomings become more obvious. Through surface modification, magnesium hydroxide has good interface affinity and reduced oil absorption value. It can be better used in high-end fields such as plastics, coatings, rubber, papermaking, sealants, and breathable films to improve product quality and further reduce the cost of application enterprises. production costs.
(5) Give magnesium hydroxide more functional properties
Magnesium hydroxide without surface modification can only be used as a traditional filling material, and its application fields and dosage will be subject to certain restrictions. Through surface modification, magnesium hydroxide becomes a multifunctional modifier. Magnesium hydroxide coated with silica can partially replace silica and supplement certain performance deficiencies of silica; magnesium hydroxide coated with metal can improve some special properties of rubber products; surface Magnesium hydroxide coated with titanium dioxide can replace titanium dioxide to a certain extent;
(6) Increase the added value of magnesium hydroxide products
At present, my country has excess production capacity of ordinary magnesium hydroxide, and competition for low-price products is fierce. After surface modification, the use effect of magnesium hydroxide is significantly improved, the user experience is good, and the product price will naturally increase.
(7) Comply with the development trend of magnesium hydroxide industry
The industry has classified ordinary magnesium hydroxide as a backward product, and will continue to increase its elimination efforts in the future.
2. In what fields can modified magnesium hydroxide be used?
(1) Polyvinyl chloride (PVC)
Compared with ordinary magnesium hydroxide, the particles of modified magnesium hydroxide are evenly distributed in the original particle state without agglomeration. It has excellent compatibility and dispersibility with PVC resin, is easy to plasticize, does not stick to rollers, and has excellent processing performance. , which is conducive to improving processing efficiency, and the breaking strength and elongation at break of the product are significantly improved, and the physical and mechanical properties are good.
(2) Polypropylene (PP)
Using coupling agent tetrahydrofuran homopolyether (PTHF) to modify the surface of light magnesium hydroxide can reduce the oil absorption value and contact angle of magnesium hydroxide. The modified magnesium hydroxide is filled into polypropylene and is well dispersed in polypropylene, which can alleviate the downward trend of tensile strength to a certain extent.
(3) High density polyethylene (HDPE)
The aluminate coupling agent is used to mechanochemically modify heavy magnesium hydroxide. The aluminate coupling agent has a certain bonding effect on the surface of the magnesium hydroxide particles, and the dispersion of the modified magnesium hydroxide particles is significantly improved. ; As the amount of modified magnesium hydroxide in high-density polyethylene (HDPE) increases, the wear and friction work of the composite material decreases, the anti-friction performance increases, and the tensile strength and impact strength increase respectively.
(4) Low density polyethylene (LDPE)
Using stearic acid and aluminate, the modified magnesium hydroxide has good activation index and oil absorption. The modified magnesium hydroxide is filled into low-density polyethylene (LDPE), and the composite material has good mechanical properties.
(5)ABS plastic
After surface modification of nano-magnesium hydroxide, the dispersibility in organic media is improved, and the surface changes from hydrophilic to lipophilic. When used in ABS resin, it can improve the mechanical properties of ABS resin, such as impact Strength, tensile strength, surface hardness, flexural strength and thermal properties such as heat deflection temperature.
(6) Polyester (PBAT)
The surface of magnesium hydroxide is modified using a double-layer coupling agent coating method. The modified magnesium hydroxide composite products have good comprehensive mechanical properties. In the composite material, the modified magnesium hydroxide particles are completely infiltrated and coated by the PBAT resin matrix, without dissolution, and the mutual fluidity between the two is improved.
(7) Radiation cross-linked ethylene propylene diene monomer rubber (EPDM)
Magnesium hydroxide is modified in situ using a titanate coupling agent with unsaturated functional groups, and the dispersion of the modified magnesium hydroxide is improved; in radiation cross-linked EPDM, the surface of the modified magnesium hydroxide is combined with the oleic acid group EPDM produces a chemical reaction, allowing magnesium hydroxide to participate in the cross-linked network of EPDM, improving the tensile strength, 100% elongation stress and Shore A hardness of the composite material, making magnesium hydroxide have the unique properties of radiation cross-linked EPDM Reinforcement.
(8) Polylactic acid (PLA)
The surface of magnesium hydroxide is modified by a coupling agent to increase the specific surface area of magnesium hydroxide, thus increasing the contact area with the matrix. When subjected to stress, more silver streaks and plastic deformation areas will be generated, absorbing a large amount of energy. In order to achieve the purpose of toughening and strengthening.
(9) PVC coated fabric
Modified heavy magnesium hydroxide can improve the compatibility of the polyvinyl chloride paste resin compound system. When used in the same amount as ordinary heavy calcium, it can obtain a lower viscosity and enhance the adhesion with the polyester base cloth. The cooperative effect can reduce the amount of adhesive and at the same time improve the feel of the coating material. With a 40% increase in usage, there will be no adverse impact on the material’s processing performance, physical and mechanical properties, and thermal welding performance.
(10) Polyvinyl chloride (PVC) fire hose
Compared with ordinary magnesium hydroxide, modified magnesium hydroxide particles are evenly distributed in the state of primary particles without agglomeration, and some of them exist in the state of nanoparticles. Therefore, filling in polyvinyl chloride (PVC) fire pipes can not only improve the system’s Processing performance, and gives the product better physical and mechanical properties to achieve the effect of toughening and reinforcement.
(11) PVC cable materials and flame retardant masterbatch
Use aluminate, titanate coupling agent, stearic acid to modify heavy magnesium hydroxide, and use this heavy magnesium hydroxide composite filler to prepare PVC cable materials and flame retardant masterbatch, with excellent performance, and the composite The use of modifiers will become one of the development trends in surface modification of heavy magnesium hydroxide.
(12) Polyetheretherketone
Using sulfonated hyperbranched polyaryl ether ketone to modify magnesium hydroxide whiskers can improve the dispersion of magnesium hydroxide whiskers in the matrix, enhance the interaction between the two phases, and reduce the melt viscosity of the composite material in the processing temperature range. At the same time, the Young’s modulus, flexural modulus and toughness of the obtained composite materials are improved.
(13) Plastic film
Magnesium hydroxide is widely used in films. After surface treatment, magnesium hydroxide is mostly combined with the basic resin in the form of surface adsorption, physical entanglement, van der Waals forces, etc., and is dispersed evenly and has better film performance.
(14) Food plastic packaging
As an ultra-fine substance filled in plastics, nanomagnesium hydroxide has special effects in changing the performance of products. Studies have shown that nano food packaging materials have barrier, antibacterial and fresh-keeping properties, and are currently used in beer, beverages, fruits and vegetables, milk, etc. It is used in food packaging such as finished products. To obtain a filling state with good dispersion and small particle size, the nano-action energy must be weakened or reduced. At present, mechanical dispersion method is generally adopted, or by adding dispersant, drying treatment, etc.
(15) Breathable membrane
The breathable film is made by adding about 50% special magnesium hydroxide to the PE or PP carrier for blending, extruding the film and then stretching it to a certain ratio. It is widely used in pharmaceutical films, surgical gowns, and medical gloves. , women’s sanitary napkins, baby diapers, disposable sheets, cling film, composite film, cooked food packaging bags and other fields. Surface-modified magnesium hydroxide has unexpected hydrophobic properties, excellent dispersion properties, and thermal stability before it can be used in the production of breathable membranes.
(16) Room temperature vulcanization (RTV) one-component silicone rubber sealant
The surface of ultrafine magnesium hydroxide is modified using a silane coupling agent. The modified magnesium hydroxide has a better reinforcing effect on the sealant.
(17) Polyurethane sealant
Modified magnesium hydroxide is copolymerized with methyl methacrylate and silane coupling agent. The modified magnesium hydroxide has better dispersion in polyurethane. It exhibits thixotropic properties after being mixed with polyurethane, and has an impact on the mechanical properties of polyurethane. Improvement over unmodified magnesium hydroxide.
(18) Silicone glue
Nano-magnesium hydroxide can replace white carbon black to a certain extent for filling silicone glue. It is the main raw material for the production of silicone glue. As a filler and reinforcing agent for silicone glue, nano-magnesium hydroxide can greatly reduce the product quality. Cost, improve the processing performance of the product, greatly improve the mechanical properties such as tensile strength and tear strength of the glue, and control the crystal form, particle size and surface treatment of nano-magnesium hydroxide to achieve excellent thixotropic properties of the product and anti-sag properties.
(19) Rubber products
Surface-modified magnesium hydroxide has a reinforcing effect in rubber, and its reinforcing performance is comparable to that of white carbon black. It is commonly used as a reinforcing agent for white, light-colored and colored rubber products. It can be used to manufacture tire buffer layer rubber, inner tubes, bicycle inner and outer tubes, transmission belt covering rubber, hoses, tape products and rubber shoes. It is also suitable for natural rubber, SBS and latex. SBS has obvious reinforcing effect and good coloring performance.
(20) Natural rubber vulcanized rubber
Magnesium hydroxide is modified with resorcinol and hexamethylenetetramine. The mechanical properties of the modified magnesium hydroxide natural rubber vulcanizate are significantly improved compared to the unmodified magnesium hydroxide natural rubber vulcanizate. Compared with Compared with unmodified magnesium hydroxide, the elongation strength, tensile strength and tear strength of natural rubber vulcanized rubber are improved.
(21) Styrene-butadiene rubber (SBR)
When magnesium hydroxide modified with carboxylated polybutadiene (CPB) is used as a reinforcing agent for SBR, the performance of the vulcanized rubber is compared with that of unmodified magnesium hydroxide. The tensile strength is improved and the modulus stress is increased by %. Tear strength increased by %.
(22) Semi-steel radial tire inner liner
Adding modified magnesium hydroxide to the inner sealing layer of semi-steel radial tires can improve the air tightness of the rubber and has little impact on the flexural resistance and processing properties of the rubber. Judging from the tire factory test results, the airtightness of the inner liner using modified magnesium hydroxide is improved compared to the ordinary inner liner, while the cost is reduced, and the high-speed and durability performance of the tire are not affected.
(23) Papermaking filler
Starch-coated modified magnesium hydroxide is used as papermaking filler. The modified magnesium hydroxide has strong shear resistance and high retention rate, which makes the paper sheet have higher strength performance and significantly slows down the decline in strength performance. .
(24) Reconstituted tobacco leaves
Sodium hexametaphosphate and citric acid are used to modify magnesium hydroxide. The ash content of the modified magnesium hydroxide added to reconstituted tobacco leaves is higher than that of commercial magnesium hydroxide. Conventional smoke indicators and sensory evaluation results are better than Ordinary magnesium hydroxide.
(25) Powder coating
Modified magnesium hydroxide plays a skeleton role in powder coatings, which can increase the thickness of the coating and improve the wear resistance and durability of the coating. Generally, modified magnesium hydroxide is more expensive than other inorganic fillers, so it can reduce the cost of powder coatings while increasing its powder coating rate and spraying area.
(26) Latex paint
Modified nano-magnesium hydroxide is used to prepare PVC latex coatings. The surface of the coating with modified nano-magnesium hydroxide is smooth and dense, and the stain resistance, wash resistance, aging resistance and other properties are greatly improved. Improvement, among which the nano-magnesium hydroxide modified with stearic acid and sodium sulfonate has a greater impact on tensile strength, while the nano-magnesium hydroxide modified with stearic acid and titanate has a greater impact on stain resistance and wash resistance. The impact is significant.
(27) Electrophoretic paint
Hydrated fluorosilicic acid is used to modify magnesium hydroxide. The surface of the modified magnesium hydroxide is covered with a mixture of amorphous silicon and calcium fluoride to form a dense film, which greatly enhances the acid resistance of magnesium hydroxide and can be used for Weakly acidic anodic electrophoretic paint.
(28) Anti-stone chip primer for PVC car chassis
Magnesium hydroxide modified by fatty acids or fatty acid salts has good thixotropy and is used in anti-stone chip primers for PVC automobile chassis. It has good thixotropy and yield value.
(29) Ink
The ink prepared with modified magnesium hydroxide has better body and viscosity, good printing performance, fast drying, and no side effects. Due to the small particles, it is used in ink products to show excellent dispersion, transparency, excellent gloss and hiding power, as well as excellent ink absorption and drying properties, so the prints are fine and the dots are complete. Especially after resin binders are widely used in inks, modified magnesium hydroxide has almost replaced other fillers due to its excellent stability.
(30)Toothpaste
Silicon dioxide is used to coat micron-sized spherical magnesium hydroxide particles, and the toothpaste abrasive agent magnesium hydroxide is surface modified to obtain the same wear value. When the wear value is the same, the modified magnesium hydroxide is added to the toothpaste, and the fluorine Chemical compatibility has been significantly improved.
(31) Daily necessities
Adding magnesium hydroxide to cosmetics can make the products delicate and smooth; as an additive, it can be made into makeup setting powder, which can eliminate the brightness of foundation powder, protect the adhesion of the skin, and has moderate oil absorption and anti-sweat effects; used for smoothness Powder, does not irritate the skin, has uniform color and certain covering power.
(32) Artificial granite
Surface-modified magnesium hydroxide has low oil absorption value and is an important raw material for artificial stone.
(33) Composite conductive powder
By coating and modifying magnesium hydroxide, its acid resistance in acidic environments can be improved; then compounding magnesium hydroxide with polyaniline to prepare composite conductive powder can not only give magnesium hydroxide good conductivity, but also It can improve the defects of simple polyaniline being difficult to process and form, and has broad application prospects.
(34) Lubricating oil
Adding modifiers during the digestion process to produce active nano-magnesium hydroxide can reduce the negative impact of surfactants on lubricating oil and improve the dispersion stability of nano-magnesium hydroxide in lubricating oil, thereby improving its anti-wear and friction-reducing properties. .