How to choose UV resin (EA article)

UV resin, also known as UV polymer, is the most important material to form UV coating film, they are activated by the light trigger molecules after cross-linking into different density mesh structure, so that UV coating has a variety of different physical forces Academic performance, such as: high hardness, high softness, better substrate binding, low yellow performance, high weather resistance, UV coating engineers will often according to his need to obtain the coating performance to comprehensively screen out the appropriate UV lymer.
commonly used UV low polymer from the molecular structure of the distinction, we can be summarized as: epoxy acrylates low polymer, polyurethane acrylates low polymer, urethane low polymer, polyester acrylates low polymer, pure acrylic low polymer and other special structures of acrylic low polymer. We are through the principle of structural division to the commonly used UV lymer products theoretical explanation and performance brief, to find out the theoretical basis to support its performance, from deepening the understanding of related products . It should be pointed out that UV lymer in the same structure category can also be divided into different types of official energy products, the number of official groups is different, the formation of mesh structure tightness is not consistent. The official energy group refers to the resin can occur cross-linking reaction of the active group, in a single molecule, the more official number, the more dense the coating film formed after curing, but also the easier it is to obtain a higher hardness of the paint film, but at the same time, because of the increase in the number of cross-base groups, in the process of low polymer curing will also increase the shrinkage, which can easily lead to the coating in the drying process stress release blocked or adhesion decline.
UV coating formulator after setting the comprehensive performance of the coating, according to the different structure and the performance of the property group of lymer to screen out the appropriate product matching, in order to obtain a balanced coating, to complete the design of the UV coating formulation. The degree of understanding of UV polymer properties of different structures and different official groups has become the most basic professional quality of the relevant practitioners, and in most cases, when using UV resin products, it is necessary to understand and learn from the molecular structure of UV polymers, so as to quickly clarify the performance differences of different products in structure, so as to achieve optimal screening. More should be from the overall grasp of various types of UV resins in different UV coatings in the role of the rationale, to help solve different problems. Below will be different structures of UV property classification explanation, convenient for a quick and clear understanding of its characteristics.
one. Epoxy acrylic low polymer
acryptonate low polymer (referred to as "EA") is currently the most widely used, the largest amount of light-cured low polymer, the most common by bisphenol A epoxy resin (128 epoxy) and acrylates, but also with phenolic epoxy and acrylates products, these products will have higher heat resistance. Epoxy acrylic low-polypolymer is characterized by a faster curing speed and higher film hardness, while gloss and plumpness are relatively excellent, the price is relatively low, become an indispensable low-polypolymer material in many UV formulations.
-type epoxy acrylic resin, which was first used in the field of UV curing, is made of bisphenol A epoxy (128 epoxy) and acrylic, which are esterified by an open ring under the action of a catalyst. Such a low concentration we used to call it "standard bisphenol A type epoxy acrylic low polypolymer", it is synthesized because of the viscosity is relatively large, in order to meet the characteristics of downstream customers easy to build, manufacturers often add a certain amount of active monomer before the factory to dilute, the most commonly used is to join TPGDA monomer, the market often see products such as Taiwan Changxing: 621A-80, Jiangsu Sanmu 6105D-80. It is also the most important basic photocuring material, showing film-forming characteristics, high hardness, high gloss, rapid curing, heat resistance and good chemical resistance. At the same time, this kind of lysate also has some structural film defects, such as: rigid structure caused by the curing after the brittleness, after the film paint film yellowing and so on.
In the actual use of the process, synthesis engineers according to the molecular properties of EA resin, by adjusting the structure of different esters to achieve certain performance optimization purposes, the following according to the market common modified epoxy synthesis technology to carry out theoretical analysis and performance elaboration, in order to market there is a theoretical explanation of the basis.
1. After the initial reaction with biphenol A epoxy, the synthetic circuit can increase the molecular weight of the epoxy propylene low polymer, and the modified epoxy acrylate low polymer is made with a higher ratio of "standard bisphenol Type A epoxy acrylic low polymer "better flexibility, in the process of film-forming reduced brittleness, at the same time, with the increase in molecular weight, the distribution density of double bonds and chromatic groups in the resin is also greatly reduced, it can obtain a better resistance to the characteristics of yellowing modified epoxy products. So we often see some modified epoxy resins with low yellowing on the market, most of which are generated by such synthetic routes. They all retain the structural characteristics of bisphenol A epoxy resin benzene ring and side chain hydroxyl, after the modified also retain the thermal stability of EA resin and better pigment affinity and so on.
Our DAY-158 epoxy resin is a large molecular acid produced by a special structure of acrylic to modifie biphenol A epoxy resin, it has a larger molecular weight than the general modified epoxy and more excellent film-forming softness, by introducing a high Elastic acrylic structure after the EA resin, it has a more excellent adhesion, so that the film is characterized by: soft and has a certain degree of stretch (general modified epoxy resin can achieve better softness, but most do not have extendable properties), heat resistance and very strong adhesion.
2. Open-ring esterification with acrylic or large molecular acids, such as epoxy propane or certain glycerol ethers commonly found on the market, is partially replaced with a low viscosity material containing epoxy groups. The modified epoxy resin also effectively reduces the density of rigid structures such as benzene rings, and obtains better film-forming flexibility and low shrinkage. Due to the replacement of some "128 epoxy resins", such polymers will have a lower initial viscosity and better resistance to yellowing. At the same time, with the increase of halogen group, under the guarantee of a certain curing rate, it can produce a better attachment than "standard biphenol A epoxy resin". In general, this modified EA resin, because of its low cost of use and relatively excellent film-forming properties, is wood, paper products in the field of UV coatings or ink widely used basic materials. It should be noted that in the synthesis process also used this kind of low viscosity material containing epoxy group to replace 128 epoxy for open-loop esterification reaction, so that the resulting product will have a smaller viscosity and lower cost of use, is the wood UV bottom coating and even surface coating of commonly used materials. In summary, the modified EA resins modified by such methods are generally more flexible, making up for the brittleness of the traditional standard EA resins, but also through different hydroxyl esterification materials and different structures of the acid to combine and match, to produce a good resistance to yellowing and rapid curing of modified EA products. However, it cannot be avoided that the existence of BPA structure makes some inherent performance disadvantages of resin can not be compensated, such as: weather resistance and long-lasting yellow resistance. At the same time, because the design process will have a joint reaction of different materials, so that the final product of such modified EA is not single enough, easy to lead to low polymer molecular weight distribution is too wide, the result is that many of the paint film has a high appearance requirements of the field unacceptable, such as: easy to produce surface pinholes and curing long-term placement after the coating surface hardness has a downward trend. In this case, we need to advise customers to consider using some PUA structure products to coordinate, because they will have a more common molecular structure and higher double-bond conversion rate and so on.
3. Esterification with long chain fatty acids and part of the "128 epoxy resin" increases the molecular weight of the low polymer and the length of the main chain segment, thus improving the softness of the EA resin. This modified EA resin is conducive to the wetting of pigments, increasing the resin's ability to wrap all kinds of inorance pigment fillers, so that the functionality of pigments in the coating is effectively released. Because of the relatively large molecular weight of long-chain fatty acids used, these modified EAs tend to have a higher initial viscosity than standard BPA epoxy resins, and synthetic engineers need to adjust the ratio between materials based on the desired resin viscosity. In the actual use of the process, high viscosity resin will increase the use of active monosomes, a large number of active monoidants added in the resin will affect or mask certain properties of the resin, such as low official energy monosome dilution will reduce resin film-forming fullness or reduce curing capacity. Therefore, the high viscosity and relatively slow curing properties of these disadvantages, so that such resin applications are gradually replaced by the second point of the modified EA resin. However, these resins have lower halogen content and better pigment wetting, in some UV printing ink industry is still used as the main film material.
4. The acid reacts with hydroxyl on the side chain of epoxy acrylates to produce a modified EA resin with a pyrethroid structure. The nirium-based in the molecule can effectively improve the adhesion between the resin and the substrate, in most applications, they are often used as a functional material addition, because of its high acid value of the nirch-based structure, the resin's water resistance and stability will be affected, in the general UV coating will not be widely used. However, such structures can be used as alkali-soluble photo-curing materials in the field of photoimaging or alkali-faded protective coatings.
5. The epoxy base in the "128 epoxy resin" is partially reduced by using a small amount of beramine material, and then acrylates are used to produce the amine-modified EA resin. This type of structure is designed to enhance the antioxidant sudden death ability of EA resins in the photo-curing excitation state, thus effectively improving the surface curing of the entire UV coating. Used as a hydrogen supply material in UV curing, it has a lower migration than other amine monosomes obtained by the Michael addition reaction. It should be noted that this modified EA will also make it less brittle, while the pigment wetting will be improved.
6. Phenolic epoxy resin acrylic esterification, the market application of these products are mostly for the curing film has a higher heat resistance and chemical resistance and other performance requirements, because it has a higher phenidal density than the traditional bisphenol A structure of epoxy resin, so that its rigidity and heat resistance after the film is greatly improved, the hardness and electrical properties of the curing film are much higher than bisphenol A products. It should also be noted that most of these lysogenes are poly-energy products, and bisphenol A structure epoxy resins are mostly dual-phenolic products, from this point of view, phenolic UV polymer light activity will be greatly improved, easy to form a cross-link density higher photo-curing coating. However, the raw material price of phenolic epoxy is higher, and the color of the synthetic product is deeper, it generally appears in some high-hydraulic performance requirements of UV ink or coating layer, such as: photo-curing welding ink, high temperature-resistant UV coating.
7. Epoxy-based open-loop esterification of vegetable oil containing epoxy groups is carried out to produce acrylic low-polypolymers of epoxy oil, such as epoxy soybean oil/epoxy castor oil, etc. This type of UV lysum has excellent pigment wetting and better leveling ability, and has the characteristics of halogen-free and low halogen content, low skin irritation, is one of the most common film-forming objects in early UV wood and UV paper coatings. We can perform a variety of esterification open-loop reactions in the form of Article 1 to obtain modified epoxy soybean oil acrylic low polymers of different molecular structures, thus obtaining products with different performance values. It should be noted that the use of UV lymer in epoxy soybean oil in coating formulation is mostly the use of its low cost of use, better pigment wetting and flow equality characteristics, but they generally have some defects in film-forming properties, such as: slow curing speed, film-forming properties, so in most UV formulations need to be combined with other highly reactive lysates to improve the post-film regenerative properties.
8. Other functional group modified epoxy acrylic low polymer, in addition to the above several common modified EA resins, there are some special group latte modified EA resins for functional considerations, such as: 1). In order to improve the EA resin to the metal substrate attachment, first the bisphenol A epoxy semi-esterification of acrylic, and then Phosphoric acid esterification of some unencumulated epoxy groups to produce phosphate modified EA resin; 2). In order to improve the weather and stain resistance of epoxy resins, the silicone oxygen and epoxy base with hydroxyl can be reduced, and then acrylatesized to produce silicone modified EA resin.