News Details
High - solid paint crosslinking agent
2017-6-30 15:58:33
High - solid paint crosslinking agent
The volatile organic compounds (VOC) in coatings are becoming more and more concerned about air pollution. Reduce the amount of solvent, the development of high solid coatings, is the important direction of coatings research, high solid coatings is difficult to have a precise definition, general solvent-based thermosetting coating now, under the requirements of viscosity, the solid content (weight) is in commonly 40%, 60%, and the so-called high solid coatings of solids in 60% - 60%.
Due to the difference between the film and the amount of pigment, the high solid content indexes differ widely. For example, for high - level primer for PVC, high solid content means solid content (volume) is 50%, while high gloss finish or varnish for PVC is more than 75%. This indicator may not seem very difficult at first glance, especially for macromolecular workers, and it is often thought that as long as the molecular weight of the film is reduced, it can be achieved.
Actually otherwise, because of high solid coatings not only has to solve the problem of high and low viscosity, and at the same time ensure that film and coating performance can reach the level of general solvent thermosetting coating or higher, this is a very complicated subject. The earliest use of drying oil or some oily coating is high solid coatings, they don't add or just add a few solvent, but the coating quality is not high, now it is not possible to paint level down to the level of oil paint.
The so-called high - solid paint should be a high - quality paint. This paper mainly discusses the effects of various factors on the viscosity of high solid coatings and low polymer solutions, as well as various problems in preparation and application of high solid coatings.
High solid paint viscosity. The effect of molecular weight and molecular weight distribution on viscosity. It is well known that under the fixed concentration, the viscosity of polymer solution and decreased with the decrease of molecular weight, for coating, discussed under fixed viscosity, solid content more intuitive: the relationship of polymer concentration and molecular weight, molecular weight, polymer solution concentration increased. It is obvious that a polymer with low molecular weight must be synthesized to increase the concentration.
On the other hand, the same average molecular weight polymer, because of the molecular weight distribution, their viscosity is very different. For the viscosity of the polymer melt, when M exceeds a certain value, due to the winding between the polymer molecules, the x value is higher, is about 3-4, for the high solids oligomer, generally do not occur around problems, generally between 1-2 x value.
Chinese name: Diethyl toluene diamine(DETDA)
Chinese alias: aryl, aryl diethyl - aryl - methyl-p-phenylenediamine
English name: Benzenediamine, ar, ar-diethyl-ar-methyl-English aliases:Diethyltoluenediamine; ar, ar-Diethyl-ar-methylbenzenediamine;Diethylmethylbenzenediamine;
CAS No. :68479-98-1
EINECS No. :270 -877-4
Molecular formula: C11H18N2
Molecular Weight: 178.28
Boiling point: 310 ℃
Refractive index: 1.581
Flash Point: > 140 ℃
Inchi: InChI = 1/C11H18N2/c1-4-8-6-7 (3) 10 (12) 11 (13) 9 (8) 5-2/h6H ,4-5,12-13H2 ,1-3H3 density : 1.022
Risk Codes: R10; R35
RIDADR: UN 3082
Safety instructions: S2; S26; S39; S61
Packing Group: III
Hazard Class: 6.1
Then, the following calculation can be used for the following calculation: the molecular weight (Mn) of the two kinds of Numbers (Mn) is a low polymer of 1000, the first kind of molecular weight distribution is single disperse, namely, Mw/Mn = 1, and its viscosity is eta = 1Pa · s. If x is equal to 1, you can get LGK is equal to negative 3. The second kind of low polymer is a polydisperse low polymer, if Mw/Mn = 3, then its Mw = 3000, as calculated by the above equation, eta = 3Pa · s, if x = 2.0, then the second polymer's eta = 9Pa · s.
It is not difficult to see that the molecular weight distribution becomes wider and the viscosity increases significantly. By the way, the contribution of molecular weight different polymer molecules to Mw and Mn is different, and Mn is sensitive to molecular weight, while Mw is sensitive to molecular weight. In addition, the polymer with low molecular weight may be volatile at high temperature curing, which actually reduces the solid content.
The effect of glass temperature and functional groups on viscosity. The decrease of molecular weight can lead to an increase in free volume, as the number of chain ends increases, making the chain movement easier. The increase in free volume can decrease the Tg, which can be an explanation for the decrease of molecular weight and viscosity decline. And of course the Tg is not only related to the molecular weight, but also the structure.
Generally speaking, the polarity increases, the Tg of the polymer increases, and the viscosity increases. We discussed in front of the lower molecular weight, viscosity drop, this is just a general situation, we have ignored as high solid coatings film forming polymer, not only requires low molecular weight, and the requirements of these low molecular weight molecules can have plenty of functional groups, to form crosslinked structure in the film.
The lower the molecular weight, the more the active functional groups are required in the same weight of polymer, and the increase in the relative amount of the functional group will increase the Tg and viscosity.
When we consider reducing the molecular weight of a polymer, the opposite effect must be considered, so the molecular weight cannot be reduced indefinitely. , on the other hand, the increase of the content of functional groups such as hydroxyl increased, the corresponding crosslinking agent (e.g., HMMM) must also increase, when the crosslinking reaction so release of the amount of volatile molecules also increases, which in turn increases the amount of volatile organic compounds from the opposite side.
Copyright: Zhang Jia Gang YaRui Chemical co.,Ltd
Diethyl toluene diamine(DETDA) http://www.yaruichem.com
The volatile organic compounds (VOC) in coatings are becoming more and more concerned about air pollution. Reduce the amount of solvent, the development of high solid coatings, is the important direction of coatings research, high solid coatings is difficult to have a precise definition, general solvent-based thermosetting coating now, under the requirements of viscosity, the solid content (weight) is in commonly 40%, 60%, and the so-called high solid coatings of solids in 60% - 60%.
Due to the difference between the film and the amount of pigment, the high solid content indexes differ widely. For example, for high - level primer for PVC, high solid content means solid content (volume) is 50%, while high gloss finish or varnish for PVC is more than 75%. This indicator may not seem very difficult at first glance, especially for macromolecular workers, and it is often thought that as long as the molecular weight of the film is reduced, it can be achieved.
Actually otherwise, because of high solid coatings not only has to solve the problem of high and low viscosity, and at the same time ensure that film and coating performance can reach the level of general solvent thermosetting coating or higher, this is a very complicated subject. The earliest use of drying oil or some oily coating is high solid coatings, they don't add or just add a few solvent, but the coating quality is not high, now it is not possible to paint level down to the level of oil paint.
The so-called high - solid paint should be a high - quality paint. This paper mainly discusses the effects of various factors on the viscosity of high solid coatings and low polymer solutions, as well as various problems in preparation and application of high solid coatings.
High solid paint viscosity. The effect of molecular weight and molecular weight distribution on viscosity. It is well known that under the fixed concentration, the viscosity of polymer solution and decreased with the decrease of molecular weight, for coating, discussed under fixed viscosity, solid content more intuitive: the relationship of polymer concentration and molecular weight, molecular weight, polymer solution concentration increased. It is obvious that a polymer with low molecular weight must be synthesized to increase the concentration.
On the other hand, the same average molecular weight polymer, because of the molecular weight distribution, their viscosity is very different. For the viscosity of the polymer melt, when M exceeds a certain value, due to the winding between the polymer molecules, the x value is higher, is about 3-4, for the high solids oligomer, generally do not occur around problems, generally between 1-2 x value.
Chinese name: Diethyl toluene diamine(DETDA)
Chinese alias: aryl, aryl diethyl - aryl - methyl-p-phenylenediamine
English name: Benzenediamine, ar, ar-diethyl-ar-methyl-English aliases:Diethyltoluenediamine; ar, ar-Diethyl-ar-methylbenzenediamine;Diethylmethylbenzenediamine;
CAS No. :68479-98-1
EINECS No. :270 -877-4
Molecular formula: C11H18N2
Molecular Weight: 178.28
Boiling point: 310 ℃
Refractive index: 1.581
Flash Point: > 140 ℃
Inchi: InChI = 1/C11H18N2/c1-4-8-6-7 (3) 10 (12) 11 (13) 9 (8) 5-2/h6H ,4-5,12-13H2 ,1-3H3 density : 1.022
Risk Codes: R10; R35
RIDADR: UN 3082
Safety instructions: S2; S26; S39; S61
Packing Group: III
Hazard Class: 6.1
Then, the following calculation can be used for the following calculation: the molecular weight (Mn) of the two kinds of Numbers (Mn) is a low polymer of 1000, the first kind of molecular weight distribution is single disperse, namely, Mw/Mn = 1, and its viscosity is eta = 1Pa · s. If x is equal to 1, you can get LGK is equal to negative 3. The second kind of low polymer is a polydisperse low polymer, if Mw/Mn = 3, then its Mw = 3000, as calculated by the above equation, eta = 3Pa · s, if x = 2.0, then the second polymer's eta = 9Pa · s.
It is not difficult to see that the molecular weight distribution becomes wider and the viscosity increases significantly. By the way, the contribution of molecular weight different polymer molecules to Mw and Mn is different, and Mn is sensitive to molecular weight, while Mw is sensitive to molecular weight. In addition, the polymer with low molecular weight may be volatile at high temperature curing, which actually reduces the solid content.
The effect of glass temperature and functional groups on viscosity. The decrease of molecular weight can lead to an increase in free volume, as the number of chain ends increases, making the chain movement easier. The increase in free volume can decrease the Tg, which can be an explanation for the decrease of molecular weight and viscosity decline. And of course the Tg is not only related to the molecular weight, but also the structure.
Generally speaking, the polarity increases, the Tg of the polymer increases, and the viscosity increases. We discussed in front of the lower molecular weight, viscosity drop, this is just a general situation, we have ignored as high solid coatings film forming polymer, not only requires low molecular weight, and the requirements of these low molecular weight molecules can have plenty of functional groups, to form crosslinked structure in the film.
The lower the molecular weight, the more the active functional groups are required in the same weight of polymer, and the increase in the relative amount of the functional group will increase the Tg and viscosity.
When we consider reducing the molecular weight of a polymer, the opposite effect must be considered, so the molecular weight cannot be reduced indefinitely. , on the other hand, the increase of the content of functional groups such as hydroxyl increased, the corresponding crosslinking agent (e.g., HMMM) must also increase, when the crosslinking reaction so release of the amount of volatile molecules also increases, which in turn increases the amount of volatile organic compounds from the opposite side.
Copyright: Zhang Jia Gang YaRui Chemical co.,Ltd
Diethyl toluene diamine(DETDA) http://www.yaruichem.com
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