News Details
Melamine coatings cross-linking agent
2017-2-28 21:10:07
Melamine coatings cross-linking agent, the traditional melamine resin for is and side reaction of hydroxyl group, then the main crosslinking with polyester molecules. Because of the crosslinking reaction is acid catalysis, curing temperature at 120 ℃ to 150 ℃, usually polyester resin in strong acid will influence the crosslinking reaction, however, some polyester in extremely weak acid, need another plus acid catalytic curing to enamel system.
Exist the following phenomena: in addition to melamine - polyester crosslinking reaction, butyl etherification melamine - formaldehyde resin for the polycondensation reaction. That is to say, occur from crosslinked amino resin to form melamine mesh structure. The reaction with melamine - polyester and competition for reaction at the same time.
Reaction is due butyl etherification melamine - formaldehyde resin in addition to containing butyl oxygen groups, also contains free hydrocarbon methyl groups and amine hydrogen, and all these ingredients can react. Amino resin in the event of the crosslinking, will lose some functions.
The following from the principle of amino resin to understand its nature:
The first step of the synthesis of resin was to make the melamine in the presence of catalyst reaction with formaldehyde to form more methylol melamine. Triazine ring, all of the active hydrogen atoms can be converted into hydroxyl methyl, but actually it was 2 to 6 mole of formaldehyde reaction to triazine ring, who left unreacted active hydrogen atoms by the amino. We will see in the future, the group in the process of curing reaction by the polycondensation reaction played an important role.
More methylol melamine is not very stable, only limited solubility in conventional coating solvent. Amino resin in coatings mainly crosslinking curing effect, in order to create a suitable for use in coatings cross-linking agent, general need to hydroxyl methyl and a short chain alcohol etherification reaction, in order to reduce its reactivity, and improve its with conventional film forming material and the intermiscibility of aliphatic solvents. Short chain alcohol using methanol and butanol, control and other conditions for the amount of methanol or butanol, amino resins with different etherification degree can be obtained.
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
Only the reaction with formaldehyde parts (hydroxymethyl) to alcohol sealing side, the unreacted hydrogen atoms (amino) with short chain alcohols. In addition, the reaction show all six hydroxymethyl and six alkoxy methyl alcohol reacts melamine, actually can control one to six hydroxymethyl react with alcohol. So there will be a so different kinds of amino resin.
Self-assembly of amino resin:
Amino resin molecular weight by triazine ring on the functional groups (amino and hydroxyl methyl, alkoxy) and melamine from the polycondensation between molecules or Bridges is determined. On the final application, bridging aggregation degree affected by amino resin molecular weight had a great influence on the performance of the coating.
Amino resin degree of bridge is usually with the degree of polymerization (DP) to said: DP = molecular weight/the weight of each triazine ring. Early production of amino resin are from convergent, basic DP > 3.0. Amino resin as the technology advances made since the polycondensation in finished products to a minimum possible. In the commercialization of melamine resin with low DP = 1.1.
Amino resin molecular weight of the main influence on the viscosity of coating can be reflected. DP > 2.0 of melamine resin must use solvent release to 50% - 80% solids, the viscosity of the parties to achieve can be applied. Haplotype DP in 1.1 ~ 1.5 between melamine resin is usually to 100% effective supply solid form, additional solvent paint to complete the VOC's influence is very big. Amino resin molecular weight also affects the coating curing reaction and coating properties.
Copyright: Zhang Jia Gang YaRui Chemical co.,Ltd
Exist the following phenomena: in addition to melamine - polyester crosslinking reaction, butyl etherification melamine - formaldehyde resin for the polycondensation reaction. That is to say, occur from crosslinked amino resin to form melamine mesh structure. The reaction with melamine - polyester and competition for reaction at the same time.
Reaction is due butyl etherification melamine - formaldehyde resin in addition to containing butyl oxygen groups, also contains free hydrocarbon methyl groups and amine hydrogen, and all these ingredients can react. Amino resin in the event of the crosslinking, will lose some functions.
The following from the principle of amino resin to understand its nature:
The first step of the synthesis of resin was to make the melamine in the presence of catalyst reaction with formaldehyde to form more methylol melamine. Triazine ring, all of the active hydrogen atoms can be converted into hydroxyl methyl, but actually it was 2 to 6 mole of formaldehyde reaction to triazine ring, who left unreacted active hydrogen atoms by the amino. We will see in the future, the group in the process of curing reaction by the polycondensation reaction played an important role.
More methylol melamine is not very stable, only limited solubility in conventional coating solvent. Amino resin in coatings mainly crosslinking curing effect, in order to create a suitable for use in coatings cross-linking agent, general need to hydroxyl methyl and a short chain alcohol etherification reaction, in order to reduce its reactivity, and improve its with conventional film forming material and the intermiscibility of aliphatic solvents. Short chain alcohol using methanol and butanol, control and other conditions for the amount of methanol or butanol, amino resins with different etherification degree can be obtained.
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
Only the reaction with formaldehyde parts (hydroxymethyl) to alcohol sealing side, the unreacted hydrogen atoms (amino) with short chain alcohols. In addition, the reaction show all six hydroxymethyl and six alkoxy methyl alcohol reacts melamine, actually can control one to six hydroxymethyl react with alcohol. So there will be a so different kinds of amino resin.
Self-assembly of amino resin:
Amino resin molecular weight by triazine ring on the functional groups (amino and hydroxyl methyl, alkoxy) and melamine from the polycondensation between molecules or Bridges is determined. On the final application, bridging aggregation degree affected by amino resin molecular weight had a great influence on the performance of the coating.
Amino resin degree of bridge is usually with the degree of polymerization (DP) to said: DP = molecular weight/the weight of each triazine ring. Early production of amino resin are from convergent, basic DP > 3.0. Amino resin as the technology advances made since the polycondensation in finished products to a minimum possible. In the commercialization of melamine resin with low DP = 1.1.
Amino resin molecular weight of the main influence on the viscosity of coating can be reflected. DP > 2.0 of melamine resin must use solvent release to 50% - 80% solids, the viscosity of the parties to achieve can be applied. Haplotype DP in 1.1 ~ 1.5 between melamine resin is usually to 100% effective supply solid form, additional solvent paint to complete the VOC's influence is very big. Amino resin molecular weight also affects the coating curing reaction and coating properties.
Copyright: Zhang Jia Gang YaRui Chemical co.,Ltd
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