Discussion on the compatibility of coating resin

Mixing between different polymers to improve the performance of the material is a widely used method. Mixed resins are used earlier in coating products than in polymer materials. However, the structure of coating resin is complex, and mostly thermoo-solidity, theoretical research is relatively small, in recent years, with the development of coating technology, its resin microstructure, morphology and viscosity elasticity and other aspects of the study is increasingly in-depthAlthough most of the basic theories and methods in this regard come from the polymer discipline, but compared with polymer, coating resin has its characteristics, and the requirements of coating properties and polymer materials are also different, so the study of the compatible coating resin mix is very important, can provide a basis for the development of new products.1 resin compatible effect on performance In order to meet the various properties of coatings on different substrates, coating resins need to be mixed with different resins. For example, aolic acid/amino, aolic acid/epoxy, epoxy/acrylic, etc., which is well known. With the development of the coating industry and the increasing demand for coating performance, new coating resin mixing systems, such as polyester/acrylic, fluorocarbon/acrylic, acrylic/silicone (organic/inorganic hybrid resin), as well as self-layering coatings, liquid crystal lattic resins, etc., have become one of the directions of coating resin development
generally speaking, the mixed effect between different resins can have a great impact on all aspects of the parts. For liquid coatings, the solubility of
(1) resins
hybrid resins in organic solvents is different from that of single resins. The solvent's solubility parameters need to be adjusted to change the composition of the mixed solvent in order to obtain a transparent resin solution.at the same concentration of(the viscosity of the 2-year-old resin solution
the viscosity of the mixed resin and the viscosity of a single resin are often different, the reasons are more complex, and the resin structure, molecular weight, composition ratio, etc., to be carefully adjusted, otherwise it will affect the construction.(3) storage stability of the resin solution
the solution system of the mixed resin, phase separation may occur during storage, resulting in precipitation, or uneven solution. It is also possible that changes in the condensed state structure may occur during storage, resulting in changes in performance.From the physical performance of the coating, may affect the following aspects:(1) paint film appearance
mixed resin coating, in the drying process, due to the resin shrinkage is different, may re-create phase separation, so that the dry paint film produces orange peel, paint film uneven, lighting and other paint diseases.(2) paint film impact strength, hardness, scratching and corrosion prevention and other properties
the purpose of resin mixing is to expect to produce positive synergies in performance, to achieve satisfactory comprehensive performance, such as poor mixing effects, may produce negative synergies, the results are counterproductive. This is particularly important for functional coatings.It is worth noting that the addition of curing agents, such as a curing agent in a single resin has a good solubility, but in the mixed resin may dissolve poorly, affecting the curing effect, resulting in poor paint film performance. The same coating additives such as anti-drying agents, anti-orange peels, leveling agents and mixed resins also have compatible problems, otherwise it will affect the effect of use, should be carefully selected and formulated.concept of 2 resin (polymer) compatiblecompared to polymers used in polymers of polymeric materials, coating resins have their own characteristics. Generally speaking, the thermosolytic resin relative to the molecular weight is relatively low, usually below 10000, molecular chain with amorphoous groups, often amorphoous polymers, curing process through the chemical reaction between the official energy groups cross-linked into a membrane, these are conducive to the mixing of different resins, improve its compatible.considering the compatibleness of several different polymers, there are roughly three cases: (1) is completely incompatible.
no matter what method is used to mix, such as mixing or solution mixing, the resulting mixture is phased, can only reflect the performance of their respective polymers, do not produce synergies. It is often used as a composite material in polymer materials. In coating products, the use of this nature to develop self-layering coatings, a construction can get both primer and finish, avoid the use of medium coating, conducive to energy conservation and environmental protection.(2) a fully compatible system, also known as a errical phase system.
molecular-level contact between different resins is a solution system that treats one resin as a solvent and the other as a solute. Because it is difficult for polymers to dissolve each other, this system is relatively small in polymeric materials, typical of polyphenyl ether/polystyrene, PVC/butyl rubber and other blends. Such systems often produce synergies and are a way to develop new materials. However, this system has been used in coatings for decades, the most typical is the aliclicyptic/amino system. Because the molecular weight of paint resin is relatively low, there are many polar groups in the molecule, the interaction between molecules is strong, it is easier to achieve the ghed phase system. Drunk acid resin is easy to mix with a variety of resin characteristics, widely used in conjunction with other resins, to produce good synergies, improve the comprehensive performance of the coating. 1 The relationship between two-phase mixed free energy and composition the compatibleness of the characteristic polymer mix, the common methods are the determination of glass temperature (Tg) and electro-mirror observation. For example, from Figure 2 to the sample A/B mixed Tg measurement results can be found, if completely incompatible system, respectively, respectively, the respective Tg temperature, such as fully compatible ion system, then a single Tg temperature, such as partial compatible system, two Tg temperature close to each other, in general, two Tg temperature close, compatible is good. for some compatible systems, the situation is complex, the degree of compatible and compatible effect, relying only on the determination of Tg temperature is not sufficient, but also need to be morphological observation and performance determination. Moreover, the coating resin is often thermostat, cross-linked into a membrane, with differential thermal analysis (DSC) or dynamic sticky spectrometry (DMA) determination, often more idle, the need for appropriate sample-making methods. At the same time, a comprehensive performance survey can finally evaluate the effect of confuse. Figure 2A and B glass temperature changes 3 Methods to improve the compatible of mixed resins Improving the compatible of mixed resins is very important to improve the performance of coating and the development of new coating products, while different process conditions will seriously affect the effect of confumarization, so to test the performance and structural characteristics, i which needs to dry paint film morphological observation. In order to improve the compatible between polyester/amino resin and silicone resin, the composition of polyester/amino/silicone hybrid resin coating is studied to improve the compatible between polyester/amino resin and silicone resin, so that the alkyl on silicone becomes hydroxyl, which helps to react with amino resins. From the scanning electroscope (SEM) to the lacquer membrane morphology observation (see Figure 3), it can be found that silicone-free polyester / ammonia paint film, is a ion phase system, silicone after the addition of continuous phase and dispersion phase, the content of less than 12.4wt%, the silicone phase particle size is less than 1 m, the content increased step by step, silicone particle size also increased. At the same time, it can be seen that silicones are evenly dispersed in the polyester/ammonia continuous phase and have good compatibness at less than 12.4wt%. It is concluded that when the silicone content is 11.4wt%, the scratch resistance of the paint film can be improved because the silicone resin is present on the surface of the paint film. figure 3 The form of polyester/amino/silicone coating coating film with different silicone content butt co- polymerization is an effective method to improve resin compatible. Incompatible two resins, such as the use of a thing method, on the molecules of one resin to join another resin, can effectively prevent phase separation, and can be used in the preparation of water-based coatings. acrylic (ester) mixed monomer, the use of free-based triggers, and unsaturated polyester resin thing reaction, to obtain unsaturated resin / acrylic resin thing co-polymer, by added amine into salt, can be prepared water dispersion coating. There are two glassy temperatures available from the DSC assay, but SEM (scanning electroscope) observed the paint film sample and found excellent compatibleness (Figure 4). At the same time has a good paint film physical performance.
4 Unsaturated polyester clinging acrylic coating coating film SEM form The overspending polymer of polyester-amide structure, reacting with polyurethane prepolymer, obtains a hybrid coating of two-phase structure, and can make water dispersion, which can be clearly observed from SEM continuous phase and dispersion phase, as shown in Figure 5. The particle size of the dispersed phase is about 50nm, which can be seen to have excellent compatibleness and to obtain good paint film performance.
5 Polyester-Alamy Overspending Polymer Branch polyurethane SEM form The reaction between polyester-alamide overspending polymer end base and polyethyl dimethyl ether (average molecular position 550) was studied to obtain the thyroid polymer. SEM observation can also see the two-phase structure, as shown in Figure 6, the dispersed phase particles are also about 50nm. Hydro-hydrophobic polyglycol is incompatible with hydrophobic polyester, but its compatible can be greatly improved by latte, preventing further phase-splits. Figure 6 Overspending Polyester-Alamy Branch Polyglycol SEM Form using a similar method, in the overspending resin end-base branch fluorocarbons, obtained a polyester/fluorocarbon hybrid resin, from the DSC determination has two glassy temperature, can be seen to be partially compatible multiphase system, the resulting paint film has good physical properties, and improve the hydrophobic properties of the paint film. 7 Fluorocarbon branching overspending resin DSC diagram there are many ways to improve the compatible between different resins. In the preparation or formulation of coating resin, the addition of a capacity enhancer (paint additive) can be used to improve compatible, it is an interface agent, the structure of two different ends of the resin, so that one resin is well dispersed in the other resin. Using different types of curing agents, the two resins are interconnected to form inter-through network resins, and multi-phase structure can be obtained, which can avoid further phase separation, thus obtaining positive synergies in performance and improving the physical performance of the coating. 4 Conclusions development of coating technology provides a solid basis for improving the quality and performance of coating products. In recent years, leaping progress has been made in the basic research of coatings, mainly in terms of performance requirements, reasonable molecular design, the application of modern equipment to characterise the structure, in-depth understanding of the relationship between structure and performance: from the point of view of material science, the study of the physical properties of dry paint film, such as static and dynamic viscosity, surface resistance, corrosion resistance and optical properties and electrical properties, etc., is bound to promote the development and performance of coating products.