News Details
Polyurethane chain extender
2017-2-25 14:34:10
Polyurethane chain extender, in the process of polyurethane foam, the stand or fall of chain extender use sometimes directly influence the reliability of the bubble, affect the quality of products. Polyurethane (pu) is composed of rigid chain segments and flexible chain segment block copolymer; Rigid chain segments and the composition of flexible chain segment, in addition to the associated with polyethylene glycol and isocyanate, at the same time, the choice of chain extender and use also has a direct influence on the formation of them.
Chain extender refers to can cause chain extension, expansion of compounds. In polymer formation, mainly for the double functional group of chemicals. In the synthesis of polyurethane chain extender has the following features:
(1) low molecular binary or ternary or quaternary compounds can make polyurethane reaction system such as chain extender and crosslinking quickly.
(2) they have with the characteristics of the reaction system for chemical reaction, low molecular weight, reaction and lively, the isocyanate and polyethylene glycol system constitute a strong reaction competition risk, they can very effectively adjust reaction system response speed; Can use different varieties of crosslinking agent and dosage, adjust the reactant growth process parameters such as viscosity, make it adapt to the requirement of processing.
(3) the use of chain extender to participate in and enter the polymerization in the owner chain reaction, can be certain features of the chain extender molecules group structure in the main chain of the polyurethane, can affect the performance of polyurethane.
The classification of the chain extender
According to the chemical structure of chain extender basic can be divided into alcohol and amine compound, its functionality, are all 2 or less than 4. With the rapid development of polyurethane industry, chain extension agent varieties are also increasing rapidly, but the actual use is still glycol or secondary amine low molecular compounds. Specific classification is as follows:
Polyols: ethylene glycol, propylene glycol, 1, 4 - butanediol, A reduction of diethylene glycol, glycerin, trimethylolpropane alicyclic alcohols, such as: 1, 4 - cyclohexanol diol, hydrogenated bisphenol A
Aromatic alcohols: 2, hydroquinone and methyl phenyl glycol double - beta hydroxy ethyl ether, resorcinol hydroxyl ether glycol amine, diethanolamine, triethanolamine, methyl diethanolamine
2 amine: 2 ethyl toluene diamine, 3, 5 - dimethyl sulfonium toluene diamine
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
Other: alpha glycerin allyl ether, glycidyl allyl ether, dicumyl peroxide, sulphur
Dihydroxy methyl butyric acid (DMBA) as a new generation of hydrophilic chain extender, structure and DMPA are similar, but it can shorten the reaction time, lower energy consumption, save energy and its superior product performance, make the aqueous polyurethane dispersions in leather coating, adhesive, coating, etc, get more extensive application.
Found in the experiment, DMBA and DMPA on the dissolution behavior of polymer polyols is influenced by the relative molecular mass of polymer polyols is small, but the melting temperature of both have very big difference. DMPA solution temperature is 145 ~ 145 ℃, lower than the temperature, again slowly precipitation, and the temperature is 80 ℃, the dissolution of DMBA once dissolved, lower temperature without precipitation phenomenon. This due to the low melting point DMBA (Tm = 108 ~ 113 ℃), while the melting point of DMPA is higher (Tm = 175 ~ 188 ℃).
DMPA system in terms of reactivity is still strong after 6 h NCO absorption peak, while still can see reaction in a bottle with a small amount of undissolved DMPA. And NCO based absorption peak after 5 h DMBA system has not obvious, suggesting that the DMBA with NCO reaction quickly. This is because the DMBA dissolved in the polymer polyol temperature is 80 ℃, and system reaction temperature is 80 ℃, the entire reaction in homogeneous system; Secondly, DMPA with DMBA of differences in the molecular structure, DMBA because of increased carbon chain a methylene (CH2), carboxyl and hydroxyl distance increased, hydroxy reaction with isocyanate base space steric hindrance.
DMBA polyurethane emulsion film tensile strength and elongation at break than DMPA polyurethane, but 50% modulus is low. Reason lies in the molecular structure of the DMBA, large side chain - CH2COO - hinders the accumulation of the polyurethane hard segment hard segment pyramiding degree difference, to dissolve the hard segment itself in the soft segment matrix degree is high, hard segment hard segment in the micro area reduced, these factors to cause a decline in modulus, however, low modulus can lead to larger elongation at break, in turn, large elongation and soft segment further causes stress, results in high tensile strength.
Copyright: Zhang Jia Gang YaRui Chemical co.,Ltd
Chain extender refers to can cause chain extension, expansion of compounds. In polymer formation, mainly for the double functional group of chemicals. In the synthesis of polyurethane chain extender has the following features:
(1) low molecular binary or ternary or quaternary compounds can make polyurethane reaction system such as chain extender and crosslinking quickly.
(2) they have with the characteristics of the reaction system for chemical reaction, low molecular weight, reaction and lively, the isocyanate and polyethylene glycol system constitute a strong reaction competition risk, they can very effectively adjust reaction system response speed; Can use different varieties of crosslinking agent and dosage, adjust the reactant growth process parameters such as viscosity, make it adapt to the requirement of processing.
(3) the use of chain extender to participate in and enter the polymerization in the owner chain reaction, can be certain features of the chain extender molecules group structure in the main chain of the polyurethane, can affect the performance of polyurethane.
The classification of the chain extender
According to the chemical structure of chain extender basic can be divided into alcohol and amine compound, its functionality, are all 2 or less than 4. With the rapid development of polyurethane industry, chain extension agent varieties are also increasing rapidly, but the actual use is still glycol or secondary amine low molecular compounds. Specific classification is as follows:
Polyols: ethylene glycol, propylene glycol, 1, 4 - butanediol, A reduction of diethylene glycol, glycerin, trimethylolpropane alicyclic alcohols, such as: 1, 4 - cyclohexanol diol, hydrogenated bisphenol A
Aromatic alcohols: 2, hydroquinone and methyl phenyl glycol double - beta hydroxy ethyl ether, resorcinol hydroxyl ether glycol amine, diethanolamine, triethanolamine, methyl diethanolamine
2 amine: 2 ethyl toluene diamine, 3, 5 - dimethyl sulfonium toluene diamine
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
Other: alpha glycerin allyl ether, glycidyl allyl ether, dicumyl peroxide, sulphur
Dihydroxy methyl butyric acid (DMBA) as a new generation of hydrophilic chain extender, structure and DMPA are similar, but it can shorten the reaction time, lower energy consumption, save energy and its superior product performance, make the aqueous polyurethane dispersions in leather coating, adhesive, coating, etc, get more extensive application.
Found in the experiment, DMBA and DMPA on the dissolution behavior of polymer polyols is influenced by the relative molecular mass of polymer polyols is small, but the melting temperature of both have very big difference. DMPA solution temperature is 145 ~ 145 ℃, lower than the temperature, again slowly precipitation, and the temperature is 80 ℃, the dissolution of DMBA once dissolved, lower temperature without precipitation phenomenon. This due to the low melting point DMBA (Tm = 108 ~ 113 ℃), while the melting point of DMPA is higher (Tm = 175 ~ 188 ℃).
DMPA system in terms of reactivity is still strong after 6 h NCO absorption peak, while still can see reaction in a bottle with a small amount of undissolved DMPA. And NCO based absorption peak after 5 h DMBA system has not obvious, suggesting that the DMBA with NCO reaction quickly. This is because the DMBA dissolved in the polymer polyol temperature is 80 ℃, and system reaction temperature is 80 ℃, the entire reaction in homogeneous system; Secondly, DMPA with DMBA of differences in the molecular structure, DMBA because of increased carbon chain a methylene (CH2), carboxyl and hydroxyl distance increased, hydroxy reaction with isocyanate base space steric hindrance.
DMBA polyurethane emulsion film tensile strength and elongation at break than DMPA polyurethane, but 50% modulus is low. Reason lies in the molecular structure of the DMBA, large side chain - CH2COO - hinders the accumulation of the polyurethane hard segment hard segment pyramiding degree difference, to dissolve the hard segment itself in the soft segment matrix degree is high, hard segment hard segment in the micro area reduced, these factors to cause a decline in modulus, however, low modulus can lead to larger elongation at break, in turn, large elongation and soft segment further causes stress, results in high tensile strength.
Copyright: Zhang Jia Gang YaRui Chemical co.,Ltd
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