The application of green antifreeze additives in water-based building coatings

"China Paint Online News News
With the continuous improvement of people's living standards and people's living room environment requirements continue to improve, latex paint industry requirements continue to be strict, how to make breakthroughs in the existing technical methods, to find new ways to solve customer environmental problems, new raw materials to replace the current market environment of some fixed, unchanged paint product concepts, has become able to lead the future development of the industry and the company's future positioning of the key.
people's concern for the environment to promote the continuous greening of coatings, the main problem facing the indoor environment today is formaldehyde and volatile organic compounds (VOCs) and other harmful substances exceeding the standard. Formaldehyde's effect on the human body is mainly concentrated in irritation, allergy and teratogenic aspects, including irritation in the skin mucous membranes and respiratory tract, allergic manifestations in dermatitis, color spots and bronchial asthma, and more serious cases can cause nasopharyngeal and other physiological tissue tumors and cancerous, long-term inhalation of pregnant women can lead to fetal death, long-term inhalation of men lead to sperm distortion or death. VOC has a smell, is irritating, and some compounds are genetically toxic.
Currently believe that VOC can cause the body's immune level disorders, affecting the central nervous system function, dizziness, headache, drowsiness, weakness, chest tightness and other conscious symptoms; In severe cases, it can damage the liver and hemag hemaging system, and a perverted reaction occurs. Therefore, if the future of interior wall coating products to reach a new height is bound to move towards environmental protection and human-friendly direction, anti-formaldehyde and low VOC and even zero VOC coating development is an inevitable trend.
At present, the domestic detection content of formaldehyde mainly has the 2005 "environmental mark product technical requirements of water-based paint", the limit of formaldehyde in the coating is 100mg/kg, while the VOC content requirement is 100g/L (withholding water), in the latest GB 18582-2008 in the "indoor decoration material interior wall paint" The requirement for formaldehyde limits in the Medium Hazardous Substances Limit is ≤100mg/kg, the VOC content is 120g/L, and the more stringent ten-ring HJ/T 201-2005 standard has been updated to the new requirements of ≤50g/L in HJ 2537-2014.
low VOC coatings on the market have become the latest concept in the industry, but water-based building coatings themselves are used by glycols as a protective agent for freezing and thawing in low-temperature environments, and these glycols are the main source of VOC, in order to be able to completely remove these substances to find With some suitable alternatives, Clariant began to study a few years ago how to achieve the same antifreeze effect by using non-low solidification points to reduce the solidification point of the system under the premise of ensuring high product performance (scrubbing resistance, stain resistance, etc. to meet GB premium requirements).
, Clariant has been working with a number of well-known architectural coatings companies to develop related low-VOC architectural coatings products, these products have maintained a leading and guide the architectural coatings market towards a new direction of sustainable development.
this paper focuses on the application of green antifreeze additives Dispersogen LFH, LFA and Genapol 2070 (PVC∈ (40,80)) in water-based building coatings.
Proof-friendly antifreeze agent action mechanism
is different from the general mechanism of reducing the solidification point to ensure the low-temperature freeze-thawing of the coating, these freeze-thaw protection agents by forming a stable spatial barrier around latex particles to make the emulsion more stable at low temperature, thereby reducing the emulsion in the low temperature environment by the system after the water into ice squeeze deformation. At the same time, because these additives have a certain hydro-friendly effect, after reducing or removing glycol-assisted solvents, the opening hours of the coating can have a certain guarantee, the paint construction effect is not great.
coating construction process opening hours do not shorten
solvents refers to glycol, propylene glycol, 200 solvent oil and other solvents, these solvents can soften or dissolve latex particles, co-film additives to promote latex paint into film. These solvents evaporate more slowly than water, thus helping to extend the opening and tying times of latex paint, thus allowing latex paint to spread on the substing and avoiding joint marks. Without the help of solvent, not only makes the emulsion drying process evaporate too fast and affects the coating film-forming, but also the excessive water evaporation rate of the coating greatly shortens the opening time between the two constructions of the coating, increasing the difficulty of construction. After a large number of tests found that the use of some relatively hydro-hydro-humidifiers can be very good water preservation, and can improve the wetting capacity of pigments, through this discovery to extend the drying time of the coating film, while by appropriately reducing the solid content and increasing the amount of cellulose thickener to improve viscosity, thereby controlling the evaporation of moisture speed. Due to the special anion structure of The two products, Dispersogen LFH and Dispersogen LFA, they have good hydro-water-friendly properties, while they evaporate with the drying of the paint film and do not remain in the coating film, thus having a small impact on the paint film performance, which is a good way to overcome the problem of the coating opening time is seriously shortened after the removal of the solvent aid.
Without the solvent propylene glycol to ensure good antifreeze stability
from improving the stability of the paint freeze and thaw is no more than two points, one is to improve the paint freezing point, so that it is not easy to freeze in low temperature environment, the other is to improve milk Antifreeze stability of the liquid, so that even if the coating freezes at low temperature environment, emulsion will not break milk and other problems to ensure that after freezing can restore the original state, and the solvent freezing point is low, can reduce the freezing point of latex paint, improve the low temperature stability of latex paint And antifreeze capacity, glycol-aided solvents can also reduce the thickening effect of the compound-type thickener, without the solvent, we use the addition of a certain amount of liquid can protect the emulsion double electron layer structure of the surfactant to improve the antifreeze stability of the emulsion, so that the system After freezing to maintain the stability of the emulsion properties, not to appear after freezing the problem of milk breaking, need to improve the performance in this regard, the additives used must be better anchored on the surface of the emulsion and have a certain molecular weight so as to form a larger spatial resistance around the emulsion, And to ensure the overall stability of the viscosity and mobility of the system.
To ensure antifreeze properties while other properties are not affected
the main performance indicators of coatings are scrub resistance, water resistance and color display, these properties require the entire system of raw materials synergetic water-based building coatings the greatest advantage is water as a solvent, but it also makes the whole system there are more polar substances, so that the stability of the system is more difficult to adjust, Clariant anti-freeze stability help The agents Dispersogen LFH and Dispersogen LFA have little effect on scrub resistance and other properties under the premise of providing low VOC products, and because they have special chemical structures, the anchoring effect on pigments is also better, which can further improve the colorability of some building coating systems to inorganic and organic slurry and improve color compatible.
the contents and results of the
Dispersogen LFH, LFA and Genapol 2070 for medium to high-grade
coatings
Antifreeze additives Dispersogen LFH, LFA and Genapol 2070 (PVC∈ (40,80)) for the experimental content and results of high-grade coatings can be found in Table 1,2,3.
table 1 is 60% PVC, using The Papersogen LFH's coating formulations alone to compare experimental data with other formulations. From the data, it can be seen that Dispersogen LFH in 60% PVC coating formulation, can fully guarantee the system's antifreeze properties, while at the same time as little impact on the paint's scrub-resistant results, but also significantly reduce the paint in the tank VOC content.
table 2 is a comparison of the results that will be used in coating formulations in combination with Dispersogen LFH and Genapol 2070. From No. Test results from 6 and No. 7 samples show that when Used in combination with The Dispersogen LFH and Genapol 2070, the product has better fluidity and system stability after 5 cycles of freeze-thaw testing, and the product's scrub resistance is not significant.
Table 3 is the viscosity stability test results for Dispersogen LFH, LFA and Genapol 2070 at different PVC. Under different PVC conditions, The compound formulations of Dispersogen LFH, LFA and Genapol 2070 also have excellent viscosity stability, and are excellent in viscosity control and versatility under each PVC compared to general surfactants and commercially available antifreeze stabilizers.
results of the application of antifreeze additive Genapol 2070 and PEG products to high PVC products are shown in Tables 4, 5, 6 and 2.
table 4 is a performance performance of Genapol 2070 when used alone in 80% of PVC interior wall coatings (0.5% dosing). From the results, the use of Genapol 2070 alone, in the dosage of 0.5% of the situation, its scrub resistance and system viscosity stability is significantly better than ordinary surfactants, but there will still be a certain post-thickening appearance, in order to further improve the viscosity stability of the product, it and PEG products re-use.
table 5 is a viscosity performance test result for Genapol 2070 and PEG 300 when used in PVC 80% interior wall coatings. It can be seen from the results, with the use of PEG 300, its system viscosity stability is more excellent, after 3 days of circulation at -5 degrees C, there is basically no more obvious viscosity rise problem, and in the PEG300 compound system, the two additive systems in the anti-scrubbing performance has also increased, but Genapol 2070 performance in this performance is still more excellent, with or without PEG impact to ensure better results. Especially in the internal test formula, whether there is PEG difference is not very obvious. It also shows that the Genapol 2070 product itself has less impact on the scrub resistance of the coating.
Summary
Synthesis of the above experimental results can draw two conclusions: first,
, Dispersogen LFH and Dispersogen LFA is more suitable for medium- and high-level PVC coatings, its 1:1 or 2:1 ratio with Genapol 2070 products, the total dosing of 0.6% of the formula, its antifreeze and paint scrub resistance balance can be achieved better. Used in a variety of coating systems, different emulsion formulations can be fine-tuned with reference to this mixing ratio.
second, encountered a higher PVC coating system (PVC to 80% or so) formula, can be used Genapol 2070 and PEG 300 products for compounding to completely replace the original formula about 1% EG or PG, so as to improve the stability of the coating freeze and thaw. At the same time adjust the ratio with PEG 300, can reduce the impact on scrub resistance to a lower level, Genapol 2070 and PEG 300 matching ratio of 1:3, the total dosing at 0.8% is ideal, in the high PVC coating system, you can refer to this mixing ratio of different emulsion formulations for fine-tuning testing.
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