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    Home > Coatings News > Paints and Coatings Market > General knowledge of coating: Research Progress of zero VOC acrylate coating

    General knowledge of coating: Research Progress of zero VOC acrylate coating

    • Last Update: 2020-04-03
    • Source: Internet
    • Author: User
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    The main contents are as follows: [Abstract] the article analyzes several main sources of VOC in waterborne coatings, introduces the testing standards and realization ways of zero VOC waterborne acrylic coatings, and expounds the technical means of eliminating VOC from the aspects of emulsion synthesis, film forming auxiliaries, defoamers, thickening agents and fungicides, and finally puts forward the prospect for the further development of zero VOC acrylate coatings [Key words] zero VOC; waterborne coating; acrylate [Chinese Library Classification No.] TQ [document identification code] a [Article No.] 1007-1865 (2014) 03-0 Application scope and advantages of roller ceramic coating Recommended introduction: the surface of ceramic rubber plate used for roller ceramic coating is cast into durable rubber plate by hundreds of independent small ceramic pieces Each ceramic piece has raised characteristics Under general conveyor belt pressure, thousands of unique cast bumps can produce positive traction, prevent slipping and extend the service life of conveyor belt roller At the same time, the bottom layer adopts high-quality rubber, which has strong elasticity and can play a good impact resistance role The scope of application of roller ceramic coating is one three six 83857180 (the same as V) 1 Roller coating in extremely harsh working environment 2 The belt joint is not suitable for fixing with iron buckle; 3 It is suitable for leather Home of coatings: [Abstract] the article analyzes several main sources of VOC in waterborne coatings, introduces the testing standards and realization ways of zero VOC waterborne acrylic coatings, and expounds the technical means of eliminating VOC from the aspects of emulsion synthesis, film forming auxiliaries, defoamers, thickening agents and fungicides, and finally puts forward the prospect for the further development of zero VOC acrylate coatings [Key words] zero VOC; waterborne coating; acrylate [Chinese classification number] TQ [document identification code] a [article number] 1007-1865 (2014) 03-0083-02 VOC is the abbreviation of volatile organic compounds With the increasing awareness of environmental protection, the characteristics of zero VOC and low odor have become an important development direction of waterborne coatings [1] In this paper, the technical means of waterborne zero VOC, low odor acrylate coating are reviewed 1 Zero VOC paint emulsion synthesis process 1.1 improve monomer conversion Residual monomer in emulsion polymerization system is one of the main sources of VOC and odour In order to get zero VOC coating, it is necessary to increase monomer conversion rate to reduce the residual monomer content There are two methods: one is to choose different initiation type; the other is to optimize the process, including the acceleration of initiator and monomer drop, polymerization temperature and polymerization time There are two main types of initiation: thermal initiation and redox initiation [2 ~ 3], the latter is lower than the former in the temperature required to obtain free radicals, thus improving monomer conversion [4] From the point of formulation design, the best ratio can be determined by examining the monomer conversion and the ratio of redox system In addition, the monomer transformation can be more thorough by removing the residual single step According to the theory of polymerization, in a certain range, the reaction rate increases with the increase of reaction temperature The results show that in the later stage of heat preservation, the proper increase of polymerization temperature is conducive to the increase of monomer conversion and further reduction of residual monomer content 1.2 the minimum film forming temperature is a reflection of the film formation performance without using film forming AIDS Emulsion formation is actually the fusion of emulsion particles, which requires emulsion particles to have enough fluidity at the film forming temperature When the vitrification temperature is low, although the film forming performance is good, the hardness, wear resistance and pollution resistance of the obtained film are poor; when the vitrification temperature is high, the corresponding construction temperature is high, at this time, although the film hardness is high and the mechanical property is good, but the film forming is incomplete, and its water resistance and adhesion are poor In order to improve the glass transition temperature and reduce the minimum film forming temperature, the traditional method is to add film forming AIDS, so that the emulsion can enhance fluidity and form a complete film in the process of film formation However, the use of film forming AIDS inevitably introduces the problem of VOC Therefore, it is necessary to develop new technical means to obtain zero VOC coating with good comprehensive performance 1.2.1 core shell emulsion polymerization process, from the perspective of "molecular design", uses core shell emulsion polymerization process to obtain "hard core soft shell" latex particles, thereby effectively reducing the minimum film forming temperature The characteristics of the structural particles are: the glass transition temperature of the shell polymer is low, when the film is formed at a lower temperature, the hard core diffuses to the surface of the film and the shell polymer blends with each other to ensure the hardness of the film In addition, the shell material selects hydrophilic monomer, and the core material selects hydrophobic monomer, which can maintain emulsion stability and water resistance of paint film at the same time A low VOC styrene acrylic emulsion was prepared by Chen and [5] The paint film has high glass transition temperature and low film forming temperature The mechanism of core-shell emulsion polymerization was discussed by Matsumoto et al [6] Wood et al [7] developed a new polyvinylidene fluoride / acrylic mixed emulsion paint, which has good weather resistance and adhesion, and low VOC content, and is especially suitable for decorative coating of indoor machine building metal components At present, some related emulsion products abroad, such as BASF's S551 and LDM7460, have achieved better performance The core shell emulsion polymerization process usually contains self crosslinking design, so that the emulsion can be formed at low temperature The main method is to add organosilicon, methacrylic acid, N-hydroxymethylacrylamide, diacetone acrylamide, Hydroxy Acrylate, cyclic carbonate and other functional monomers in the core and shell, so that the core and shell can form self crosslinked film at low temperature through grafting, interpenetrating network and ion bonding 1.2.2 soft and hard emulsion mixing technology is a physical modification method A mixture of different Tg of two or more than two monomers can be mixed in a certain proportion, and a low MFT and a series of Tg mixed emulsions can be obtained The emulsions can maintain good film formation and film properties However, this method has the defects of poor compatibility between soft and hard emulsion, and even leads to uneven distribution of [9] on the surface of the paint film 1.3 the commonly used pH regulators using low VOC pH regulators are ammonia, organic amines, etc Compared with ammonia, AMP-95 can reduce the taste At the same time, compared with ammonia water, AMP-95 can achieve the same pH with relatively less dosage At the same time, its effective use is low, so it reduces the VOC increase of coating At present, the pH regulator with low VOC needs further development 2 The use of low VOC coating auxiliaries 2.1 the use of high-efficiency and low odor film-forming auxiliaries currently used are diethanol ether, propylene glycol ether, Texanol alcohol ester, benzyl alcohol, etc., which will cause the production of coating VOC Table 1 is the comparison results of the use performance of each film forming aid [10] Therefore, less dosage, better performance and odorless film-forming auxiliaries need to be developed Table 1 the performance of different film forming auxiliaries 2.2 use of new defoamer acrylic emulsion paint, including silicone, silicone oil and polyether, but it does not bear high temperature and strong alkali, and has poor dispersion in emulsion Silicone oil mixed defoamer can not only achieve good antifoaming effect, but also only use 0.1% ~ 0.3% of the coating, which can reduce VOC Polyether modified organosilicon can improve the water solubility of organosilicon defoamer, which has the advantages of non-toxic, tasteless, strong inverse solubility, good self-emulsification, chemical stability and thermal stability With the shortage of petroleum resources, a new type of defoamer with multi-function, high efficiency, strong adaptability and small dosage will be an important development direction in the future 2.3 thickening agents commonly used in new emulsion thickeners include associative and non associative thickeners The disadvantage of associated thickener is that it will cause VOC emission, be sensitive to pH, emulsifier and so on, and the thermal stability is also difficult to predict Non associative thickeners include cellulose ethers and alkali swelling acrylic emulsion The former will make the coating have good workability and appearance, will not increase VOC, but will reduce the water resistance of the coating Therefore, the two thickeners are often mixed to make the coating have comprehensive performance in storage stability, workability and film appearance 2.4 the commonly used bactericide for waterborne acrylate coating is isothiazolinone compound The compound does not contain formaldehyde and organic solvent, and the dosage is 0.1% ~ 0.2% of the coating At present, different kinds of nano bactericides begin to appear, such as TiO2, ZnO and so on Compared with organic fungicides, nano fungicides can prolong the period of effective mildew control and reduce the production of VOC But the latter is more effective The ideal antiseptic should have the characteristics of low VOC, wide spectrum and high efficiency, good compatibility and appropriate cost In the trend of low carbon and environmental protection, zero VOC and low odor are the important development direction of acrylate coating At present, the acrylic emulsion technology used in environmental protection in domestic and abroad is basically monopolized by large foreign companies, and relevant products are reported in China, but the related technologies are not mature enough Therefore, the development of zero VOC, low odor waterborne acrylate coating products is of great significance Home of coatings is specialized in coatings, diatom mud, paint coating, coating technology, fire retardant coating news and coating, diatom mud, paint coating, coating technology, fire retardant coating decoration knowledge and decoration renderings,
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