echemi logo
Product
  • Product
  • Supplier
  • Inquiry
    Home > Coatings News > Coating Technologies > Coating science: Analysis of the application prospects of water-based coating of water-based coatings in the field of automotive exterior plastic parts from the perspective of VOCs release and energy consumption

    Coating science: Analysis of the application prospects of water-based coating of water-based coatings in the field of automotive exterior plastic parts from the perspective of VOCs release and energy consumption

    • Last Update: 2020-05-30
    • Source: Internet
    • Author: User
    Search more information of high quality chemicals, good prices and reliable suppliers, visit www.echemi.com
    Coating industry is the key industry in the release source of industrial volatile organic matter (VOCs), whose VOC release accounts for 21.6% of the total industrial source, i.e11.9% of the total VOCs sourceChina's coatingindustry industry 13th Five-Year Plan put forward structural adjustment objectives,the product structure of the goal is to achieve good price-effective, environmentally friendly paint varieties accounted for 57% of the total production of coatings, water-based coatings as one of the main varieties of environmentally friendly paint,widely publicized will be used to replace the traditional solvent-based paintbut so far, there is no systematic comparative study of voCs release and total energy consumption for these two coating processes based on the actual running of production line data
    although in the voCs release measurement of coatings, scholars at home and abroad have done a lot of research, established the experience and physical model of VOCs release, and obtained a lot of valuable data, but many of the studies are the result of laboratory simulation (small environmental module), this paper uses the actual operation data of the plastic sheet coating line of the car exterior, through analysis 2 The VOCs release of the coating process and the various types of energy consumption (electricity, water, natural gas, etc.) in the coating process, compared the environmental protection and energy-savingof the 2 kinds of coatings,for the future promotion of water-based coating in the field of automotive exterior plastic sheeting to put forward scientific data supportVOCs release slotsthe VOCs release during coating, color paint and varnish are derived from the spray, flow, and baking processesIt should be pointed out that at present, the coating line of plastic parts of automotive exterior has not yet large-scale use of water-based varnish, this is due to the cost and part of the performance of water-based varnish and solvent-based varnish there is still a certain gap, but also because solvent-based varnish has been able to meet the mainstream environmental requirements of customers01The VOCs content in the coating the VOCs content in this section is the organic content of solvents and additives in various paint components, which does not include resin, pigment, aluminum powder and other components, because the organic components contained in the resin will not evaporate during the coating process shown in Figure 1, solvent-based paint VOCs content of 301.22g/kg, color paint 376.14g/kg, water-based paint voCs content of 46.4g/kg, color paint 88.76g/kg The VOCs content of waterquality voCs per unit mass was 15.4% of solvent-based primers The VOCs content of water-based color paint per unit was 23.6% of solvent-based color paint Figure 1 can be intuitively seen in water-based coatings instead of the vast majority of organic solvents can greatly reduce the VOCs content in the coating The VOCs content of water-based color paint is larger than that of water-based primer, mainly because the color paint system uses more solvents to ensure the dissolution of additives such as pigments and aluminum powder, resulting in a relatively large reverbeeus than primer 1 paint VOCs content
    02 coating process VOCs release figure
    2 coating process VOCs release amount shown in Figure 2, for the coating process VOCs release amount, solvent-based primer 57.79g/m2, color paint for 76.05g/m2, varnish at 104.74g/m2, water primer 3.27g/m2, paint 4.16g/m2 and varnish at 149.19g/m2 The release of VOCs in water-based primers during coating is 5.7% of solvent-based primer, and 5.5% of the release of hydro-colored paints is 5.5% of solvent-based paints This shows that the VOCs release during the coating process is not only affected by the VOCs content of the coating itself, but also by the difference in film characteristics of coating process, construction conditions and solvent-based coatings and water-based coatings 03 The thermal combustion device (RTO) According to the current industry situation, solvent-based coating and water-based coating line to the coating process released VOCs are treated by a concentrated thermal combustion device (RTO) This paper compares the efficiency of The RTO's processing of VOCs, and the results are shown in Table 1 Table 1 Thermal Combustion Device VOCs processing efficiency
    solvent-based coating line RTO inlet VOCs concentration of 2062.38 mg/m3, RTO inlet air volume of 20200m3/h; After RTO treatment, the export concentration is up to standard, so the environmental protection advantages of the water-based coating production line are not fully reflected energy consumption is relatively 01 the production process energy consumption in the coating production process, from the ingredients, grinding dispersion, paint color, filtration to filling and other processes have energy consumption (Figure 3) Different energy consumption between different units can not be directly superimposed, so in the calculation line can always time-consuming, electricity consumption, water consumption, gas consumption, steam consumption are converted into kilograms of standard coal (kgec) The total energy consumption of solvent-based coatings used in 3 solvent-based production lines is 0.16 kgec/kg, and the water-based coating is 0.20kgec/kg The total energy consumption of water-based coatings is 125% of the drop-in type Solvent-based paint consumption of 0.30kWh/kg, water consumption of 1.9L/kg, gas consumption of 0.04m3/kg, steam consumption of 0.8 kg/kg: water-based paint power consumption of 0.48kWh/kg, water consumption of 2.8L/kg, gas consumption of 0.04m3/kg, steam consumption of 0.94 kg/kg Water-based paint consumption is 160% of solvent-based coatings this is mainly because water-based coatings than solvent-based coatings on the temperature control requirements more stringent, so in the production process of water-based coatings outside the cylinder will increase the temperature-based water bath device, resulting in water-based paint consumption is greater than solvent-based coatings, water-based paint water consumption is 147.4% solvent-based coatings, because water-based coatings as a solvent solvent, and solvent-based paint production water consumption is greater than solvent-based coatings The gas consumption of water-based coating is 100% of solvent-based coating, and the steam consumption of water-based paint is 117.5% of solvent-based coating, which is not very different in the production process of these two kinds of coatings Figure 3 energy consumption 02 coating process energy consumption
    Figure 4 coating process energy consumption shown in Figure 4, solvent-based coating process total energy consumption of 1.13kgec/m2, water-based coating 1.74kgec/m2 The total energy consumption of water-based coatings is 154% solvent-based Solvent-based coating stele consumption of 3.75kWh/m2, water-based paint power consumption of 8.31kWh/m2, water-based paint power consumption is 221.6% of solvent-based coatings Solvent-based paint water consumption is 30.08L/m2, water-based paint water consumption is 39.28L/m2, water consumption is 130.6% of solvent-based coatings Solvent-based paint gas consumption is 0.50m3/m2, water-based paint gas consumption is 0.53m3/m2, gas consumption is 106% of solvent-based coatings water-based coatings consume more energy than solvent-based coatings in terms of electricity consumption, which is about twice as much as solvent-based coatings, mainly because of the evaporation potential heat of water, 2260J/gcal/g, is 5 times the majority of organic solvents used in solvent-based coatings (e.g toluene is 412.7J/g, xylene is 347.4J/g, g) And the water volatilization rate is slow, the relative evaporation is 20% to 30% of commonly used organic solvents (relative evaporation (butyl s 100) water is 38 (36), toluene is 200, xylene is 114) The above characteristics of water require the addition of new equipment or processes (oven, leveling chamber) to speed up the drying of water Before drying, pre-drying (heating) section should be added, so that the wet paint film non-volatile sub-nV to reach more than 80%, and then dry at high temperature The main function of pre-drying is to make the surface coating of the exterior plastic parts dewatering degree to a certain extent in order to carry out subsequent coating, if not volatile sub-score (NV) less than 80%, in the drying process, the moisture of the water-based primer paint into gaseous volume expansion, will be its surface of the organic varnish coating to the top and produce bubble defects the second water-based paint construction work is poor, the construction environment temperature and humidity range is narrow The optimum humidity when painting is (65 to 5), in the air conditioning system temperature and humidity control, humidity control is more important than temperature control, humidity is too high, spray painting is easy to produce flow hanging phenomenon, humidity is too low, paint surface will lose light The best paint ingesting environment in the paint booth is the temperature (23 to 3) , if the temperature is too high, the atomized paint grain quickly dries out, the fluidity of the paint film becomes worse, the temperature is too low, the solvent volatilization is not fast enough, there will be a flow ingesting phenomenon To this end, the air conditioning system of the paint booth is required to have the function of cooling, heating and pure water spray humidification , pre-drying and temperature and humidity regulation make the water-based coating process increase the power consumption and water consumption In addition, the need for new pre-drying (flash drying) equipment, resulting in increased occupation of production area, water corrosion requirements paint booth, pre-drying room with stainless steel materials will also lead to increased investment 03 Total energy consumption total energy consumption of solvent-based coatings (the sum of water, electricity, natural gas and steam consumption during the production process and coating process) is 1.19kgec/m2, and the total energy consumption of water-based coatings is 1.84kgec/m2 The total energy consumption of water-based coatings is 155% solvent-based, about 55% more than solvent-based coatings The production process of water-based coating required by the thermostatic water bath control device and water consumption of water as a solvent, coating process water-based coating line to add pre-drying process and primer, color paint, varnish spray room are set up after the smoothing and baking room and the need to consume more electricity to control the spray room temperature humidity to ensure that the water-based paint paint film quality caused the water-based paint color energy than solvent-based paint Figure 5 total energy consumption from the point of view of VOCs release during the coating process, water-based coatingthan e However, however, after using RTO treatment, the VOCs release of solvent-based and water-based coatings can be up to standard From the point of view of total energy consumption, water-based coatings consume about 55% more energy than solvent-based coatings we should take these factors, including energy consumption and carbon emissions, into account when promoting the use of water-based coatings, as well as the possibility of other environmentally friendly coatings being used in our country In terms of policy guidance, we can also consider the environmental protection and energy-saving nature of various coatings Water-based coatings are not the only means, high solids, solvent-free, powder, UV photocuring and other environmentally friendly coatings can also be an important direction for future development In particular, high solid sub-coating, its equipment environmental requirements are not as high as water-based coatings, the existing solvent-based coating line does not need much transformation Therefore, the high solid solvent-based coating process for a large number of domestic environmental requirements for solvent-based old line transformation of enterprises, can also be discussed as a potential alternative China is a big automobile country, in the current large-scale use of plastic parts to replace metal parts of the trend, automotive exterior plastic parts coating also has a broad market prospects To improve the overall performance of water-based coatings, we need to work together with water-based coatings related to all aspects It is necessary not only to make a breakthrough in the research on the limitations of water-based coatings themselves (e.g film-forming properties, coating processes), but also to further enhance their energy-saving while developing the resins, additives and other materials associated with them in the water-based development and improvement of their environmental protection source: Coatings Industry Editor: Shenzhen Coatings Technology Association statement: This number of reprints, sharing, statements, views to maintain neutral, the purpose is only for industry exchanges, copyright owned by the original author If involved in copyright and intellectual property rights and other infringement issues, please contact the background of this number, immediately delete the content processing Shenzhen Coatings Technology Institute leading the industry to the global deep coating introduction: according to the Shenzhen Science and Technology Association (2012) No 13 "on the approval of the establishment of the Shenzhen Institute of Coatings Technology" and the Shenzhen Civil Affairs Bureau (2012) No 265 "on the establishment of the Shenzhen Coatings Technology Society registration approval" and other documents Shenzhen Coatings Technology Society was officially established in Shenzhen on April 28, 2012 The establishment conference of the Institute of Coatings Technology gathered more than 400 well-known enterprises in the national paint industry and related people, attracting more than 200 well-known enterprises at home and abroad to join the Coatings Society
    This article is an English version of an article which is originally in the Chinese language on echemi.com and is provided for information purposes only. This website makes no representation or warranty of any kind, either expressed or implied, as to the accuracy, completeness ownership or reliability of the article or any translations thereof. If you have any concerns or complaints relating to the article, please send an email, providing a detailed description of the concern or complaint, to service@echemi.com. A staff member will contact you within 5 working days. Once verified, infringing content will be removed immediately.

    Contact Us

    The source of this page with content of products and services is from Internet, which doesn't represent ECHEMI's opinion. If you have any queries, please write to service@echemi.com. It will be replied within 5 days.

    Moreover, if you find any instances of plagiarism from the page, please send email to service@echemi.com with relevant evidence.