The current situation and development trend of desiccants for water-based coatings in China.

0 Introduction . Although the amount of additives used in water-based coatings is small, it has a great effect. Generally speaking, many problems encountered in the production, construction and application of water-based coatings can be solved by additives, of which desiccants are one of the more important additive varieties. China is a large country of building coating production, of which latex paint is the largest and most important variety. Latex paint on the demand for desiccant, and increasing year by year, so the development of de-foaming agent is very important.reform and opening up, China's water-based coating additive products, especially desiccant is almost blank. Since the German BYK company's additives first entered our country, the magic function of water-based coating additives began to get the first, and Japan's Libang coatings company in mainland China launched latex paint, its use of performance and application effects to the industry praise, so that China's paint industry has developed latex paint, has become a hot spot in China's paint industry at that time. In the process of latex paint research and development, people deeply appreciate from practice, if you want to do a good job of latex paint, water-based paint additives, especially deblisters are essential. However, at that time, most of the deboulants from abroad, the price is very expensive, so only do-it-yourself, the desolation of the manufacturing technology in hand, in order to put latex paint to market, and occupy a place. Soon, China has a lot of domestic desobbists products, although compared with similar products abroad, there are still some gaps in performance, but these desiccants close to the market, suitable for national conditions, and therefore well received by customers. Since the reform and opening up, China's desiccant products from nothing, from weak to strong, basically many varieties of desobbists abroad now also have in our country, which is a remarkable progress. The following is a brief description of the current situation and development trend of desculating agents for water-based coatings in China.1 The current variety and limitations of defoulants there are many varieties of defoiling agents currently used, while water-based coatings use defogants in three main categories: mineral oils, with a market share of 80%; Among them, mineral oil defoiling agent is the most cost-effective, the use is more common, can be used in the vast majority of flat light and semi-light latex paint, but its foaming and defoiling effect is not as good as polysilica and polyether defoiling agent. Mineral oil deblisters are basically composed of carriers (mostly hydrocarbon oil or water), water-repugnant particles (wax, silicone oil, hydrophobic silica and fatty acids or polyurethanes, etc.), emulsifying agents or expanders (fatty acids, dehydrated yams (sugar) alcohol esters, etc.), of which carriers account for 75% to 80%, water-repugnant particles account for 10% to 15%, emulsifying agents or expanders account for 5% to 10%.the main defrosting material into the foam system, so that it spreads to the bubble film, play the role of carrying and dilution. It has a greater impact on the deblistering properties and durability of defrosting agent, is a low surface pressure substance, has suitable incompatibness with the foam system, and easily rises to the surface of the foam system; In the formulation mainly plays an active role, emulsifying agent or expander is used to adjust the compatibility of active ingredients in the coating system, so that compatibility and incompatibility to achieve balance, to ensure the rapid diffusion of active ingredients and rapid penetration of the coating surface, so that the active ingredients immediately play a deblistering effect. In addition, mineral oil deblisters contain small amounts of stabilizers or preservatives.polysilioxane defoulants include polydimethylsiloxane defoulants and modified polydimethylsiloxane defoulants, collectively known as silicone defoulants. Among them, polydimethylsilioxane defoiling agent is a non-volatile oily liquid with a polymerization of tens to hundreds, stable physical and chemical properties, with very low surface tens of surface tens of thousands, and modified polydimethylsiloxane defoulants have suitable hydro-hydro and oil-friendly balance values. For example, the use of organic fluorine modified polydimethylsilioxane-type defoulant, it is a very low surface pressure, excellent defoiling ability of defoiling agent. Although the surface pressure of polysilicae defoiling agent is low, defoulation and anti-foaming ability is very strong, does not affect the gloss, but the use is not at that time, will produce coating shrink holes, poor re-painting and other ills.polyether debugs are suitable and incompatible products obtained by selectively modifiing some polymers, mainly used in some systems with high compatible requirements. For example, there is incompatibness between acrylic and epoxy resins. To this end, consciously change the polarity of the polymer, relative molecular mass and its distribution, so that it is "insoluble" and "insoluble" between the appropriate balance, so that the resulting defrosting agent products compared with silicone-type deblisters, its inlubility is better, and will not stabilize the foam, which is the characteristics of polyether desmodants, but often there will be weak or even no problems, so its market demand share is less.2 A new generation of de-foaming agents and their characteristics the above-mentioned de-foaming agents are traditional de-foaming agents, their de-foaming substances are water insoluble substances, the need to add the right amount of emulsifying agents, extenders, etc. so that they are quickly and equally dispersed in water-based coatings in order to play its de-foaming role. If for some reason, such as water dilution before coating this common construction method, will make emulsifying agent from the surface of the deblistering substance, so that insoluble de-foaming substances can easily produce shrink holes on the coating surface, which is a common disadvantage of traditional deblistering agents. In addition, for the high viscosity coating system to achieve a more ideal deblistering effect is very difficult, because the high viscosity system makes the flow of liquid between bubbles become difficult, while the membrane wall of the bubble has a certain thickness, it is difficult to break, so that the paint film will produce a large number of pinholes. Therefore, it is necessary to develop a new type of desobbizer to solve the problem that traditional desobbists can not solve.people were inspired by the structure of a new type of Gemini surfactant, a substance formed by connecting groups of chemical bonds between two or more monosome surfactants. For example, the two alkyl single-stranded single-head base of ordinary surfactants at the ion head base by chemical bonds connected together, so that the resulting special structure has certain special properties, especially with higher surf activity and other materialization characteristics. The structural schematic of gemini surfactants is as follows:This structure is characterized by: (1) at least 2 hydrophobic chains and 2 hydrophobic-based; 2 hydrophobic base in molecules can be different; (4) according to the interval chain, can be divided into rigid and flexible structure, and because it contains hybrid atoms, its hydrophobic and hydrophobic capacity can be different, it can be divided into hydrophobic and hydrophobic two categories; (5) most of the Gemini surfactants have 2 identical hydrophobic chain and hydrophobic base.In view of Gemini surfactant technology, the desmoulbicizer is designed to resemble a mesh-like supermoleal structure, so that it has a lot of anchor point, but also has a certain self-emulsification effect, so there is no need to use emulsifiers, there will be no emulsifier caused by the shrinkage problem, and such a structure can make it have a certain wetting effect on the substrate, so it can be appropriate to reduce the amount of moisturizer. This is a major change in water-based defoaming agents, known as molecular-grade defoamers, such as Corning's FoamStar defoaming agent series, where FoamStar®A 12 is an enhanced mineral oil-based defoamer for a variety of high-gloss pure propylene, phenyl and acetate coatings, the advantages of which are: (1) add more than traditional antifouling Bubble agent low 1/3 or even 1/2, the cost can be reduced by at least 20% ;(2) during storage period will not appear ordinary mineral oil-type deblister layering problems;. FoamStar®A 34 is a mineral-free oil polysilica compound for a wide range of high-gloss water-based pure propylene, phenyl and acetate coatings, as well as water-based wood coatings, the advantages of which are: (1) in the high-gloss coating system difficult to defoam significantly, without affecting the system Gloss; (2) good compatible in application, (3) faster than ordinary desiccant bubble breaking speed, breaking fine foam effect is significant, (4) can be used in white water-based coating system, (5) during the storage period will not appear ordinary mineral oil deblister layering problems.
FoamStar®MF 324 is a segmented polymer free of silicones, mineral oils, solvents and solid compounds, and is an efficient liquid defoamer for water-based wood coatings, industrial coatings and automotive coatings, delivering excellent long-lasting stability without loss of gloss or transparency.
Air Products' acetylene glycol molecular-grade deblisters are both wetting and de-foaming agents, their varieties are Surfynol®MD20, 100% active, silicone-free liquid products based on Gemini surfactant technology, which can reduce the dosage of other additives, and make surface defects as small as possible, long-lasting, easy to add, with good compatible, non-layering. It is used with other wetting agents with enhanced effect, a wide composite range, can eliminate micro-bubbles, solvent-free, temperature, pH (1 to 13) stability, suitable for automotive raw equipment preparation coatings (OEM coatings), wood coatings, industrial maintenance coatings, metal coatings, paper coatings and architectural coatings, as well as printing and dyeing inks, moisturizers and so on. Surfynol®DF37 is a non-ionized acetylene glycol deblister, 100% active, allowing water-based coatings to minimize the formation of mesh during impregnation and to promote the wetting of low-energy surfaces such as plastics and contaminated or misprocessed materials.Agitan-type desablishing agent introduced by Germany's Mingling Chemical Group is a VOC-free (volatile organic compound) variety, of which Agitan®315 is a modified non-ionic fatty acid complex, hydrophobic A blend of silicon dioxide and pharmaceutical-grade liquid paraffin for water-based emulsion systems, especially in low-odor and non-polluting formulations, which have good compatibleity with all commonly used substituts, with a dosing of 0.1% to 0.5%; Agitan E 255 is an emulsified polysilicae copolymer in water with excellent stability and defoculation persistence, can be mixed with water in any proportion, and can be found in alkaline and acidic environments (p It is mainly used in building coatings, industrial coatings and wood coatings, as well as in the preparation of printing and dyeing inks and adhesives, and is generally used in 0.05% to 0.5%. Through the ultra-dispersion process, hydrophobic parts can be evenly dispersed into the carrier, thus creating a super-stable de-foaming agent, so that the combination of dispersants / emulsification agents to achieve the best, such as Haimies products Serdas7010, Serdas 7540 and Serdas 7580, these de-foaming agents have excellent storage stability, excellent de-foaming capacity. Serdas7010 no VOC, is hydrophobic wax in mineral oil ultra-stable dispersion, and contains a special silicone substance, it not only deblisters efficient, and long-lasting, and can even give the system a good emulsification, the system's scrub resistance has a small impact, with excellent storage stability, can be used in water-based adhesives, fillers and sealants, its dosage of 0 .2% to 0.5%, Serdas 7540 is an organic ester deblister, free of mineral oils and silicones, can be directly used in water-based coating systems, especially for surface-prone coating systems, such as high-gloss latex paint and low pigment content coating system, in water is very easy to emulsify into a uniform dispersion system, especially for low-viscosity coating systems. During coating production, painting, canning and construction, the Serdas 7540 is able to condense tiny bubbles in the system to the surface, thereby inhibiting foam production with a dosing of 0.2% to 0.5%, and Serdas 7580 is an organic ester free of silicones and mineral oils. Liquid desiccant, very easy to emulsify in the water-based system, has excellent emulsion stability, suitable for transparent coatings, such as water-based furniture paint and parquet floor paint, especially for condensation, flocculation sensitive system, it has the least risk of surface defects and adhesion loss, dosage of 0.2% to 0.5%.3 China's demand for desiccants and their development trends China's production of desticants about 40 manufacturers, its total production of about 1,000 t. China's construction coating production in 2015 was 5.38 million t, a growth rate of 4.2%. Desiccant is an essential raw material in the formulation of architectural coatings, with an average addition of 0.3%, then in 2015 the required desobbists for architectural coatings is 16,000t, it is estimated that the future dosage will increase, the current production of desticants in China is far from meeting market demand. At the same time, China's desiccant technology compared with foreign countries there is no small gap, especially in high-performance water desiccant is still blank, so it is necessary to strengthen research and development to meet market demand. In view of the current situation and market demand of water-based desmoulizers in China, research and development needs to be carried out in the following areas in the future: (1) the development of new high-activity desmoticants, such as molecular-grade desmoist,ultra-stable desmouldifiers; (3) Development of powerful anti-foaming agents for high-viscosity, high-elastic coatings; (4) development of compounding techniques for de-foaming agents, such as polyether and silicone compounding techniques; water-soluble or oil-soluble polyethers and silicone-containing polyethers; compounding techniques for silicone compounds and surfactants; and (5) new varieties of polyether and silicone-based desulbants..