News Details
Coating crosslinking agent affect gel time
2017-4-7 10:51:37
Coating crosslinking agent affect gel time,Crosslinking agent with different varieties, such as IPDI/HDI/TDI, MDI and so on, there are different adduct or trimer, so the market crosslinking agent of many varieties, different reactivity, gel time is different also.
Design of resin or resin choice is the most important. For some systems, such as the polyurea system or poly (aspartic acid ester, because it is - NH/NCO reaction, particularly fast reaction, lead to gel time is very short, sometimes can't construction, then the reactive diluent added to the principal agent, can react with NH unit generation - OH, so can greatly extend the gel time. PEC as PU reactive reactive diluent, and reduces the molecular weight of resin, such as the word is will lower reactivity, extend the gel time.
Crosslinking agent balance is also very important. Sometimes to dry you need to use the drier also had better use tin drier, sometimes with the use of tin drier leads to gel time shorten, can use the PDO complexing agent to put the tin metal complexing, extend the gel time, film when the PDO with solvent volatilize again, which is not particularly affect the reactivity and dry.
Solvent multi-purpose esters, ketones with less aromatic hydrocarbon, will help to extend the time of gel.
The factors affecting gel time are:
1, the molecular weight and structure of the resin, 2, crosslinking agent, the varieties and dosage of 3, drier, 4, and the type of solvent, 5, and the temperature.
1, resin molecular weight and structure factors
The resin molecular weight, the greater the reactivity, the greater the gel time will be shorter
Resin reactivity difference of reactive groups, can also lead to the gel time difference. - NH fastest, primary hydroxyl times, para hydroxy slowest.
Resin, acid value, may also affect gel time, acid value, the greater the gel time will be a little longer.
Three factors, drier
Drier certainly affect gel time
Has the greatest effect in the amine, tin
4, solvent factors
Chinese name: Diethyl toluene diamine(DETDA)
Physical and chemical properties: light yellow transparent liquid, slightly soluble in water, soluble in alcohols, ethers, ketones and other polar organic solvents, and polyether, polyester polyol compatibility.
Density 1.022
Viscosity (20 ℃) ??mPa·ss290±10
Pour Point ℃-9
Boiling point of310°C
Flash Point°C161.1°C
Solvent has a great influence on the reaction rate is, the greater the polarity of solvent, the slower the reaction of the - NCO/OH, 24 times difference between toluene and butanone, this is because the polarity solvent, can form hydrogen bond and - OH and association make slow reaction, so esters ketone solvents will make gel time extended.
Five factors, temperature,
This is obvious, has had a huge impact.
With ester, ketone and other effective solvent in a certain proportion within the scope of cooperation, "mixed solvent" has the same or even larger solvency. If one of acetic acid ethyl ester of toluene dilution value of 3.4, and half of the ethyl acetate add half of the dilution ratio of ethanol is the same as 3.4. Butyl acetate, toluene dilution value of 2.7, and half of the butyl acetate add half of the ethanol dilution ratio as high as 2.95, in most cases the ethanol price is far lower than the butyl acetate.
Add a small amount of n-butyl alcohol in alkyd resin coatings can significantly reduce the viscosity; Add a small amount of isobutanol in coating can effectively prevent coating film efflorescence, also can improve the liquidity and luster.
Methyl isobutyl ketone (MIBK) as the boiling point solvents, gives good liquidity and gloss nitrocellulose coating, and can effectively reduce the viscosity of alkyd resin coating, the addition of it will be able to improve the filling of solvent to join; In addition, the MIBK with alcohol and aromatic solvents can dissolve more effectively epoxy resin.
Copyright: Zhang Jia Gang YaRui Chemical co.,Ltd
Diethyl toluene diamine(DETDA) http://www.yaruichem.com
Design of resin or resin choice is the most important. For some systems, such as the polyurea system or poly (aspartic acid ester, because it is - NH/NCO reaction, particularly fast reaction, lead to gel time is very short, sometimes can't construction, then the reactive diluent added to the principal agent, can react with NH unit generation - OH, so can greatly extend the gel time. PEC as PU reactive reactive diluent, and reduces the molecular weight of resin, such as the word is will lower reactivity, extend the gel time.
Crosslinking agent balance is also very important. Sometimes to dry you need to use the drier also had better use tin drier, sometimes with the use of tin drier leads to gel time shorten, can use the PDO complexing agent to put the tin metal complexing, extend the gel time, film when the PDO with solvent volatilize again, which is not particularly affect the reactivity and dry.
Solvent multi-purpose esters, ketones with less aromatic hydrocarbon, will help to extend the time of gel.
The factors affecting gel time are:
1, the molecular weight and structure of the resin, 2, crosslinking agent, the varieties and dosage of 3, drier, 4, and the type of solvent, 5, and the temperature.
1, resin molecular weight and structure factors
The resin molecular weight, the greater the reactivity, the greater the gel time will be shorter
Resin reactivity difference of reactive groups, can also lead to the gel time difference. - NH fastest, primary hydroxyl times, para hydroxy slowest.
Resin, acid value, may also affect gel time, acid value, the greater the gel time will be a little longer.
Three factors, drier
Drier certainly affect gel time
Has the greatest effect in the amine, tin
4, solvent factors
Chinese name: Diethyl toluene diamine(DETDA)
Physical and chemical properties: light yellow transparent liquid, slightly soluble in water, soluble in alcohols, ethers, ketones and other polar organic solvents, and polyether, polyester polyol compatibility.
Density 1.022
Viscosity (20 ℃) ??mPa·ss290±10
Pour Point ℃-9
Boiling point of310°C
Flash Point°C161.1°C
Solvent has a great influence on the reaction rate is, the greater the polarity of solvent, the slower the reaction of the - NCO/OH, 24 times difference between toluene and butanone, this is because the polarity solvent, can form hydrogen bond and - OH and association make slow reaction, so esters ketone solvents will make gel time extended.
Five factors, temperature,
This is obvious, has had a huge impact.
With ester, ketone and other effective solvent in a certain proportion within the scope of cooperation, "mixed solvent" has the same or even larger solvency. If one of acetic acid ethyl ester of toluene dilution value of 3.4, and half of the ethyl acetate add half of the dilution ratio of ethanol is the same as 3.4. Butyl acetate, toluene dilution value of 2.7, and half of the butyl acetate add half of the ethanol dilution ratio as high as 2.95, in most cases the ethanol price is far lower than the butyl acetate.
Add a small amount of n-butyl alcohol in alkyd resin coatings can significantly reduce the viscosity; Add a small amount of isobutanol in coating can effectively prevent coating film efflorescence, also can improve the liquidity and luster.
Methyl isobutyl ketone (MIBK) as the boiling point solvents, gives good liquidity and gloss nitrocellulose coating, and can effectively reduce the viscosity of alkyd resin coating, the addition of it will be able to improve the filling of solvent to join; In addition, the MIBK with alcohol and aromatic solvents can dissolve more effectively epoxy resin.
Copyright: Zhang Jia Gang YaRui Chemical co.,Ltd
Diethyl toluene diamine(DETDA) http://www.yaruichem.com
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