News Details
Hydrophilic chain extender on the properties of waterborne polyurethane
2017-2-26 17:41:56
Hydrophilic chain extender on the properties of waterborne polyurethane, looked at more than the increase of the amount of DMPA the effects of particle size. During the trial, with the increase of dosage of DMPA, waterborne PUA emulsion by a milky white opaque slowly become translucent, eventually becoming solution suffused with red light.
This is because with the increase of DMPA content, the average particle size of emulsion changed: on the one hand, from the point of view of thermodynamics, the emulsion polymer in the total free energy of G is changeless, namely Δ G = gamma Δ A, when the dosage of DMPA increases (i.e., - COOH to increase), the hydrophilic polymer increases, the corollary of polymer and water interfacial tension increase with the decrease of and polymer surface area A, Y, when polymer quality must is characterized by particle size smaller.
On the other hand, due to the increase of the hydrophilic particles of water swelling properties make particle size increases, the swelling more obvious with the increase of hydrophilic. As a result, the relationship between the carboxyl content and particle size are the result of comprehensive factors, the overall effect is to make the latex particle size decreases with increasing the content of carboxyl group. So look from the appearance, emulsion become more transparent.
The effects of DMPA content on the viscosity. To study the influence of various factors on the PU dispersion viscosity. In its research system, when w (DMPA) 2.4% or less, can't form a stable emulsion, so the viscosity test data error (big); When w (DMPA) > 2.4%, with the increase of dosage of DMPA, emulsion appearance by the trend of the milky white to transparent blue emulsion viscosity has been increased. This is due to the pre polymer dispersed in water, the hydrophobic chain formation period of inward contraction nuclear emulsion particles, with carboxyl distribution of hydrophilic radical anion in the latex particle surface towards the water.
Due to particles Brownian motion, the electric double layer formed by the positive and negative ions on the particle surface, can make the hydrated ion readily dispersed in water, the emulsion stability. Along with the increase of the content of hydrophilic radical emulsion obvious changes in appearance, this is WPU particles size change caused by a macro performance (i.e. large particle size, by blocking the light, the white appearance of the emulsion is phenomenon; when reach nanoscale dispersion particle size, the light can bypass the WPU particles move on, appearance of the emulsion is transparent, blu-ray phenomenon).
According to O Lorentz electric double layer theory, the viscosity of the emulsion is not affected by the size of the dispersed particles, but by the influence of particle size were obtained. DMPA content is higher, after pre polymers into salt and water to form hydrated ion stability, at the same time, the electric double layer thickness of the hydrated ion increased, volume and enhanced interaction with water molecules, leading to the viscosity of the system increased.
Chinese name: Diethyl toluene diamine(DETDA)
Diethyltoluenediamine Raw material ：
TDA industrial, Sichuan production
Ethylene (Et) polymer grade, Shanghai production
TEA industrial imports
A reagent grade additives
When DMPA content is low, the emulsion viscosity changes along with the increase of DMPA content is not obvious, this may be related to the increase of the content of hydrophilic groups can lead to two opposite results. The increase of the hydrophilic group content on the one hand lead to enhanced hydrophilicity, make the size of the particles; On the other hand, the increase of total ion concentration, lead to the increase of total electric double layer thickness and the increase of particle volume of fluid dynamics, the particle size increases. In addition, due to the increase of the hydrophilic particles of water swelling also can make the particle size increases significantly.
When DMPA content is low, the content of hydrophilic group increase cause hydrophilicity enhanced particle size is the major factor, the emulsion viscosity change is not obvious, but when the DMPA content is higher, with the increase of content of hydrophilic group, electric double layer thickness increases and water swelling factors dominate, emulsion viscosity increases significantly.
Bonding mechanism analysis. Soaked the PMMA sheet at 80 ℃ in the EG, lauric acid tin mass fraction of 0.02%, 24 h and 48 h each took out a piece of spline, cotton dips in detergent to wash three times, to ion washed 3 times, compressed air blow dry, the static contact Angle measurement.
Not processed PMMA, 24 h and 48 h the contact Angle is 76.0 °, respectively, of the PMMA 69.9 ° and 61.9 °. Contact Angle decreased after reaction shows that PMMA surface can rise, enhanced hydrophilicity, that may occur on the surface of the ester exchange reaction, the hydroxyl group.
DMPA is the widely used hydrophilic chain extender, but DMPA high melting point (175 ~ 185 ℃), it is difficult to heat dissolved, it is added to the solvent such as N - methyl pyrrolidone (NMP), acetone, etc., NMP high boiling point, it is difficult to eliminate, after the preparation of PU and DMPA smaller solubility in acetone, need to add a lot of acetone, in the process of synthesis of ketones process trouble and not clean, bring security hidden danger to the production process.
Copyright: Zhang Jia Gang YaRui Chemical co.,Ltd
This is because with the increase of DMPA content, the average particle size of emulsion changed: on the one hand, from the point of view of thermodynamics, the emulsion polymer in the total free energy of G is changeless, namely Δ G = gamma Δ A, when the dosage of DMPA increases (i.e., - COOH to increase), the hydrophilic polymer increases, the corollary of polymer and water interfacial tension increase with the decrease of and polymer surface area A, Y, when polymer quality must is characterized by particle size smaller.
On the other hand, due to the increase of the hydrophilic particles of water swelling properties make particle size increases, the swelling more obvious with the increase of hydrophilic. As a result, the relationship between the carboxyl content and particle size are the result of comprehensive factors, the overall effect is to make the latex particle size decreases with increasing the content of carboxyl group. So look from the appearance, emulsion become more transparent.
The effects of DMPA content on the viscosity. To study the influence of various factors on the PU dispersion viscosity. In its research system, when w (DMPA) 2.4% or less, can't form a stable emulsion, so the viscosity test data error (big); When w (DMPA) > 2.4%, with the increase of dosage of DMPA, emulsion appearance by the trend of the milky white to transparent blue emulsion viscosity has been increased. This is due to the pre polymer dispersed in water, the hydrophobic chain formation period of inward contraction nuclear emulsion particles, with carboxyl distribution of hydrophilic radical anion in the latex particle surface towards the water.
Due to particles Brownian motion, the electric double layer formed by the positive and negative ions on the particle surface, can make the hydrated ion readily dispersed in water, the emulsion stability. Along with the increase of the content of hydrophilic radical emulsion obvious changes in appearance, this is WPU particles size change caused by a macro performance (i.e. large particle size, by blocking the light, the white appearance of the emulsion is phenomenon; when reach nanoscale dispersion particle size, the light can bypass the WPU particles move on, appearance of the emulsion is transparent, blu-ray phenomenon).
According to O Lorentz electric double layer theory, the viscosity of the emulsion is not affected by the size of the dispersed particles, but by the influence of particle size were obtained. DMPA content is higher, after pre polymers into salt and water to form hydrated ion stability, at the same time, the electric double layer thickness of the hydrated ion increased, volume and enhanced interaction with water molecules, leading to the viscosity of the system increased.
Chinese name: Diethyl toluene diamine(DETDA)
Diethyltoluenediamine Raw material ：
TDA industrial, Sichuan production
Ethylene (Et) polymer grade, Shanghai production
TEA industrial imports
A reagent grade additives
When DMPA content is low, the emulsion viscosity changes along with the increase of DMPA content is not obvious, this may be related to the increase of the content of hydrophilic groups can lead to two opposite results. The increase of the hydrophilic group content on the one hand lead to enhanced hydrophilicity, make the size of the particles; On the other hand, the increase of total ion concentration, lead to the increase of total electric double layer thickness and the increase of particle volume of fluid dynamics, the particle size increases. In addition, due to the increase of the hydrophilic particles of water swelling also can make the particle size increases significantly.
When DMPA content is low, the content of hydrophilic group increase cause hydrophilicity enhanced particle size is the major factor, the emulsion viscosity change is not obvious, but when the DMPA content is higher, with the increase of content of hydrophilic group, electric double layer thickness increases and water swelling factors dominate, emulsion viscosity increases significantly.
Bonding mechanism analysis. Soaked the PMMA sheet at 80 ℃ in the EG, lauric acid tin mass fraction of 0.02%, 24 h and 48 h each took out a piece of spline, cotton dips in detergent to wash three times, to ion washed 3 times, compressed air blow dry, the static contact Angle measurement.
Not processed PMMA, 24 h and 48 h the contact Angle is 76.0 °, respectively, of the PMMA 69.9 ° and 61.9 °. Contact Angle decreased after reaction shows that PMMA surface can rise, enhanced hydrophilicity, that may occur on the surface of the ester exchange reaction, the hydroxyl group.
DMPA is the widely used hydrophilic chain extender, but DMPA high melting point (175 ~ 185 ℃), it is difficult to heat dissolved, it is added to the solvent such as N - methyl pyrrolidone (NMP), acetone, etc., NMP high boiling point, it is difficult to eliminate, after the preparation of PU and DMPA smaller solubility in acetone, need to add a lot of acetone, in the process of synthesis of ketones process trouble and not clean, bring security hidden danger to the production process.
Copyright: Zhang Jia Gang YaRui Chemical co.,Ltd
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