A kind of aqueous polyurethane preparation method based on anionic azo hydrophilic chain extender
First, technical field
It is specifically a kind of hydrophilic based on anionic azo the present invention relates to a kind of preparation method of aqueous polyurethane
The aqueous polyurethane preparation method of chain extender, belongs to water-base polyurethane material technical field.
2nd, background technology
Aqueous polyurethane production at present uses the normal of the non-functionals such as bishydroxymethyl propionic acid, Diaminoalkyl sulfonate
With hydrophilic chain extender, production feature aqueous polyurethane, which is also needed to be blended or is copolymerized, adds other functional materials or monomer.
As the existing method for making polyurethane have azo characteristic can be divided into two kinds of host-guest system type and response type.Host-guest system type side
, only need to be by mixing part azo micromolecular compound into polyurethane matrix, actually with this although method technique is simple
It is a mixture made from method, small molecule azo-compound therein is not only adulterated dense due to the consistency problem with matrix
The problems such as spending and be limited, and the migration in mixture material can often occur during use, oozed out from material, causes material property
Reduce;Response type method is the monomer using azo micromolecular compound as polymerisation, passes through the active official of azo-compound
It can roll into a ball to participate in polymerizeing and obtain the polyurethane containing azo chromophore structure.
Chinese patent 201310573640.7 discloses a kind of prepares azo-type aqueous polyurethane by azo dihydric alcohol
Method, this method substitute small molecule glycol chain extender using azo dihydric alcohol and prepare target material, solve blending azo
Compound causes the problems such as material resistance to migration difference, but azo dihydric alcohol addition by raw material proportioning (polyurethane synthesize in isocyanic acid
For the mol ratio of ester and hydroxyl typically between 0.8-1.2, the addition of azo dihydric alcohol can increase the hydroxyl in polyurethane proportioning rapidly
Base content) limitation it is very big, in the patent azo dihydric alcohol only partly or entirely substitute polyurethane synthesis small molecule dihydric alcohol,
Content is up to 15wt% to azo dihydric alcohol in non-aqueous non-solvent material in aqueous polyurethane.To ensure polyurethane material
Middle introducing more amount azo-compound, must now reduce the additions of other chain extenders such as hydrophilic chain extender to ensure W-response
Proportioning, the parameters such as aqueous polyurethane emulsion stability, particle diameter, outward appearance can be influenceed again by reducing hydrophilic chain extender addition.Due to adding
After the azo dihydric alcohol for entering water resistance, the azo component of water resistance enters aqueous polyurethane milk-globule electric double layer knot after self-emulsifying process
The inside of structure, the weak ultraviolet light of penetrability are difficult to be irradiated to the azo group inside milk-globule, influence the suitable anti-of azo group
Isomerization efficiency (under the ultraviolet light of specific wavelength, the azobenzene of anti-configuration is changed into the percentage of cis-configuration),
It is difficult to reach 100%.In a word, the method has certain limitation for synthesizing azo-type anion aqueous polyurethane.
3rd, the content of the invention
It is an object of the invention to provide a kind of aqueous polyurethane preparation side based on anionic azo hydrophilic chain extender
Method, using a kind of hydrophilic chain extender containing azo chromophore, this hydrophilic chain extender collection commonly uses hydrophilic chain extender and mill base, idol
Nitrogen functional characteristic partly or entirely substitutes conventional hydrophilic chain extender and small molecule glycol chain extender, so as to synthesize in one
Side chain azo-type anion aqueous polyurethane emulsion.The inventive method can not only substantially reduce the dosage of hydrophilic chain extender, and
And a kind of azo group can be obtained and be located at polyurethane side chain, during the self-emulsifying of aqueous polyurethane emulsion is formed, azo
Functional unit is distributed in the double electrical layerses surface of milk-globule particle formation, and emulsion colorfulness is high, and ultraviolet light can be easy to
It is irradiated to the azo functional group positioned at electric double layer surface and cis-trans isomerism effect occurs, there is good stimulating responsive, leads to
Stimulation oversaturation response change polyurethane milk-globule particle size, can as ultraviolet light, visible ray, thermal response nano-carrier.Such
Macromolecule emulsion has certain application prospect in terms of functional coating, off-color material, medicine even load thing are controlled release.
The preparation method of aqueous polyurethane of the present invention, it is characterised in that:With anionic azo hydrophilic chain extender part or
Replacing whole is cloudy with diisocyanate, macromolecule dihydric alcohol reaction generation azo-type often with hydrophilic chain extender, small molecule dihydric alcohol
Ion aqueous polyurethane.
The anionic azo hydrophilic chain extender includes carboxylic acid type azo hydrophilic chain extender and/or sulfonic acid type azo is hydrophilic
Chain extender;
The structural formula of the carboxylic acid type azo hydrophilic chain extender is:
The structural formula of the sulfonic acid type azo hydrophilic chain extender is:
The preparation method of aqueous polyurethane of the present invention, comprises the following steps:
Macromolecule dihydric alcohol is dehydrated 0.5-1.5 hours in 110-130 DEG C, diisocyanate is then added, in 70-100
Anionic azo hydrophilic chain extender, conventional hydrophilic chain extender, glycol chain extender, two bays are added after DEG C reaction 2-4 hours
Sour dibutyl tin (DBTDL) and stannous octoate, add solvent, are reacted 1-4 hours at 60-90 DEG C, and reaction end is cooled to 30-
60 DEG C, add ethylenediamine base ethyl sulfonic acid sodium and carry out chain extension, then add sodium hydroxide under conditions of high speed shear and 0-40 DEG C
And triethylamine, water and diamine chain extenders are added after reacting 1-5 minutes, reaction solution is transferred to rotary evaporation after stirring 5-30 minutes
Instrument, solvent is sloughed under 40-50 DEG C, 0.01MPa vacuum conditions, azo-type anion aqueous polyurethane emulsion is made;It is described molten
Agent is acetone or butanone;
The addition of each raw material is formed as follows by mass fraction:
The macromolecule dihydric alcohol is selected from polyadipate -1,4- butyl glycol ester diols (PBA), polycaprolactone diols
(PCL), PCDL (PCDL), PTMG dihydric alcohol (PTMG), poly (propylene carbonate) dihydric alcohol (PPC) or
Polypropylene glycol (PPG);
The diisocyanate is selected from toluene di-isocyanate(TDI) (TDI), methyl diphenylene diisocyanate (MDI), different Buddhist
That ketone diisocyanate (IPDI) or hexamethylene diisocyanate (HDI);
The conventional hydrophilic chain extender is selected from dihydromethyl propionic acid (DMPA), bishydroxymethyl butyric acid (DMBA) or tartaric acid
(TA);
The glycol chain extender is selected from ethylene glycol (EG), 1,4- butanediols (BDO), 1,6-HD (HDO) or a contracting
Diethylene glycol (DEG);
The diamine chain extenders are selected from ethylenediamine (EDA) or IPD (IPDA).
The anionic azo hydrophilic chain extender that the present invention uses includes carboxylic acid type azo hydrophilic chain extender and/or sulfonic acid type
Azo hydrophilic chain extender;
The preparation process of carboxylic acid type azo hydrophilic chain extender is as follows:
1) the 2- amino terephthalic acid (TPA)s of 100 mass parts are added in there-necked flask, then add 500-1000 mass parts
Water be sufficiently stirred to form solution, 10-20 mass parts concentrated hydrochloric acids (mass concentration 36-38%) are then slowly added dropwise and arrive there-necked flask
In, control system temperature is 0-5 DEG C, the mass parts 50wt% of fast drop 38 (mass concentration, similarly hereinafter) sodium nitrite solution, is protected
Hold ice-water bath conditioned response 1-2 hours, generate the diazonium salt solution of 2- amino terephthalic acid (TPA)s;
2) by 102 mass parts N, N- dihydroxyethylbenzenands amine solvent is in 100-300 mass parts Methanols and 0-10 mass parts acetic acid
Middle formation N, N- dihydroxy ethyl aniline solution, the diazonium salt solution that 2- amino terephthalic acid (TPA)s made from step 1) are then added dropwise arrive
In N, N- dihydroxy ethyl aniline solution, dripped off in 0.5-1h;Utilize the pH value of 1mol/L sodium hydroxide solutions regulation mixed solution
For 4-6, it is added dropwise to complete rear keeping body and ties up to reaction 2-4 hours at 0-5 DEG C, last regulation system pH value is 4-8, and second is used after filtering
Alcohol, which washs and is dried under vacuum to constant weight, obtains carboxylic acid type azo hydrophilic chain extender, and its chemical name is N, N- dihydroxy ethyls -4-
(3 ', 6 '-dicarboxyl acidic group phenylazo) aniline.
The preparation process of sulfonic acid type azo hydrophilic chain extender is as follows:
1) 100 mass parts aniline -2,4- disulfonic acid are added in there-necked flask, then add the water of 500-1000 mass parts
It is sufficiently stirred to form solution, 100-150 mass parts concentrated hydrochloric acids (mass concentration 36-38%) is slowly added dropwise into there-necked flask, controls
System temperature is 0-5 DEG C, the mass parts 50wt% of fast drop 27 sodium nitrite solution, keeps ice-water bath conditioned response 1-2 small
When, the diazonium salt solution of generation aniline -2,4- disulfonic acid;
2) by 74 mass parts N, N- dihydroxyethylbenzenands amine solvent is in 100-400 mass parts Methanols and 0-10 mass parts acetic acid
Formation N, N- dihydroxy ethyl aniline solutions, the subsequent diazonium salt solution that aniline -2,4- disulfonic acid made from step 1) is added dropwise to N,
In N- dihydroxy ethyl aniline solutions, dripped off in 0.5-1h, the pH value that mixed solution is adjusted using 1mol/L sodium hydroxide solutions is
4-6, it is added dropwise to complete rear keeping body and ties up to reaction 2-4 hours at 0-5 DEG C, last regulation system pH value is 4-8, depressurizes and steams at 55 DEG C
Evaporate after -20 to -5 DEG C of cold filtrations, then washed with ethanol and obtain the hydrophilic chain extension of sulfonic acid type azo after being dried under vacuum to constant weight
Agent, its chemical name are N, N- dihydroxy ethyls -4- (2 ', 4 '-disulfonic acid base phenylazo) aniline.
Preparation method of the present invention has advantages below compared with prior art:
1st, the present invention uses anion azo hydrophilic chain extender as raw material, partly or entirely substitutes conventional hydrophilic chain extender,
Also other small molecule chain extenders can be partly or entirely substituted to prepare coloured azo-type anion aqueous polyurethane.
2nd, anion azo-type aqueous polyurethane prepared by the present invention, uncle is contained because the azo hydrophilic chain extender used removes
Outside amine structure, also containing two sulfonic acid or hydroxy-acid group, itself can be with self-contained salt, and hydrophily is stronger, azo chromophore and hydrophilic
The increase of group is linear, will not mutually limit.So it will not cause in polyurethane system caused by conventional polycondensation method
The problem of hydrophilic radical, small molecule dihydric alcohol are fed intake by considerable restraint or reduction, azo dihydric alcohol is non-aqueous in aqueous polyurethane
Content can reach 20.87wt% in property non-solvent material.
3rd, preparation method of the present invention reduces the process of production azo-type aqueous polyurethane in process of production, and it is cloudy from
When forming coloured aqueous polyurethane emulsion, due to azo chromophore, chemistry is typed into polyurethane point to sub- azo hydrophilic chain extender
In subchain, compared with small molecule dyes or pigment are directly mixed in the material of polyurethane body by routine, the poly- ammonia of the invention prepared
The polyurethane material azo chromophore that ester emulsion is formed after dehydration is evenly distributed, and is not in that surface is faded, grown dim after film forming
Phenomena such as, azo functional characteristic can persistently be kept.
4th, few aqueous polyurethane hydrophilic monomer dosage, high solids content, resistance to can be prepared using sulfonic acid type azo hydrophilic chain extender
The good coloured aqueous polyurethane of acid-base property;The azo-type aqueous polyurethane emulsion prepared using carboxylic acid type azo hydrophilic chain extender is steady
Fixed, water-tolerant, the material that sulfonic acid type is mixed to prepare with sulfonic acid type azo hydrophilic chain extender has sulfonic acid type concurrently and carboxylic acid type is water-based
Some advantages of polyurethane.
5th, using azo-type aqueous polyurethane prepared by the inventive method because azo chromophore is located at polyurethane molecular chain
Side chain, during self-emulsifying, there is the azo monomer cell distribution of strongly hydrophilic sulfonate or carboxylate structure in milk-globule particle
Surface forms stable double electrical layerses, compared with low energy (6mW/cm2) excite down reversible cis-trans isomerization configuration can occur
Change (isomerization efficiency is up to 100%).
6th, using azo-type aqueous polyurethane prepared by the inventive method because azo chromophore is located at polyurethane molecular chain
Side chain, there is the azo monomer cell distribution of strongly hydrophilic sulfonate or carboxylate structure to form stabilization in milk-globule particle surface
Double electrical layerses, the particle size of polyurethane as ultraviolet light, the nano-carrier of thermal response, can be changed by stimuli responsive
(double electrical layerses have fine and closely woven micropore, can control micropore size by adjusting particle size), bears to carrier inside
Loading is controlled release etc., greatly expands the application of azo polyurethane.
4th, illustrate
Fig. 1 is based on the synthetically prepared azo-type anionic water of sulfonic acid type azo hydrophilic chain extender in the embodiment of the present invention 5
In Fu of property polyurethane (PU1, PU2, PU3) and the anion aqueous polyurethane (PU0) without sulfonic acid type azo hydrophilic chain extender
Leaf transformation infrared spectrogram.
Fig. 2 be in the embodiment of the present invention 5 the azo-type anion aqueous polyurethane emulsion (PU2) for preparing wavelength 365nm,
Radiant illumination is 6mW/cm2Different time illumination under at caused 443nm absorbance change spectrogram.
Fig. 3 is the azo-type anion aqueous polyurethane film (PU1) prepared in the embodiment of the present invention 5 by ultraviolet lighting
Penetrate contact angle variation diagram.
Fig. 4 is the azo-type anion aqueous polyurethane emulsion PU3 prepared in the embodiment of the present invention 5 in ultraviolet light
Grain size distribution after (365nm) pre-irradiation.
5th, embodiment
Embodiment 1:
By 50.00g PBA (Mn=3200) it is added in 500mL three-necked flask, it is cold after being dehydrated 1 hour at 110 DEG C
But to 55 DEG C, take 11.10g TDI to add in three-necked flask, 9.60g sulfonic acid type azos are added after 3 hours in 80 DEG C of stirring reactions
Hydrophilic chain extender, 1.50g DEG, 0.01g DBTDL and 45.00g butanone, constant temperature are cooled to after 3 hours in 70 DEG C of stirring reactions
30 DEG C, reaction solution is transferred to high speed shear dispersion machine, 4.36g TEA are added under conditions of 3000 revs/min, after reacting 5 minutes
150g water is added, 0.35g EDA are added after being stirred for 1 minute and are reacted 30 minutes, reaction solution are transferred to Rotary Evaporators, 45
DEG C, slough butanone under 0.01MPa vacuum conditions, obtain sulfonic acid type azo aqueous polyurethane emulsion.
If other conditions of the present embodiment are constant, and PBA is changed into PCL, PCDL, PTMG or PPG respectively, can obtain steady
Fixed coloured aqueous polyaminoester emulsion.
Embodiment 2:
By 160.00g PPG (Mn=2000) it is added in 1000mL three-necked flask, after being dehydrated 1 hour at 120 DEG C
60 DEG C are cooled to, takes 62.10g IPDI to add in three-necked flask, 17.20g carboxylic acid types are added after 3 hours in 90 DEG C of stirring reactions
Azo hydrophilic chain extender, 6.90g BDO, 0.01g DBTDL and 120.00g acetone, constant temperature are dropped after 3 hours in 75 DEG C of stirring reactions
Reaction solution is transferred to high speed shear dispersion machine by temperature to 30 DEG C, and 14.66g TEA are added under conditions of 3000 revs/min, reacts 5 points
580g water is added after clock, 0.90g IPDA are added after being stirred for 1 minute and are reacted 30 minutes, reaction solution is transferred to Rotary Evaporators,
Acetone is sloughed under 40 DEG C, 0.01MPa vacuum conditions, obtains carboxylic acid type azo aqueous polyurethane emulsion.
If other conditions of the present embodiment are constant, and BDO is changed into HDO, EG or DEG respectively, what can be stablized has
Color aqueous polyurethane emulsion.
If other conditions of the present embodiment are constant, and change DA into TA or DMBA, what can be stablized is coloured aqueous poly-
Urethane emulsion.
Embodiment 3:
By 80.00g PTMG (Mn=2000) it is added in 500mL three-necked flask, it is cold after being dehydrated 1 hour at 120 DEG C
But to 60 DEG C, take 35.10g IPDI to add in three-necked flask, 2.30g carboxylic acid type azos are added after 3 hours in 90 DEG C of stirring reactions
Hydrophilic chain extender, 5.5g dihydromethyl propionic acids, 6.90g HDO, 0.01g DBTDL and 70.00g butanone, constant temperature is in 75 DEG C of stirrings
Reaction is cooled to 30 DEG C after 3 hours, and reaction solution is transferred into high speed shear dispersion machine, 5.39g is added under conditions of 3000 revs/min
TEA, reaction add 290g water after 5 minutes, Rotary Evaporators are transferred to after being stirred for 1 minute, in 45 DEG C, 0.01MPa vacuum conditions
Under slough butanone, obtain carboxylic acid/coloured aqueous polyaminoester emulsion of sulfonic acid mixed type.
Embodiment 4:
By 50.00g PTMG (Mn=2000) it is added in 500mL three-necked flask, it is cold after being dehydrated 1 hour at 120 DEG C
But to 60 DEG C, take 25.10g IPDI to add in three-necked flask, 3.80g carboxylic acid type azos are added after 3 hours in 90 DEG C of stirring reactions
Hydrophilic chain extender, 8.4g carboxylic acid type azos hydrophilic chain extender, 4.10g BDO, 0.01g DBTDL and butanone 35.00g, constant temperature exist
75 DEG C of stirring reactions are cooled to 30 DEG C after 3 hours, reaction solution are transferred into high speed shear dispersion machine, under conditions of 3000 revs/min
5.86g TEA are added, reaction adds 210g water after 5 minutes, and 0.28g EDA are added after being stirred for 1 minute and are reacted 30 minutes, will be anti-
Answer liquid to be transferred to Rotary Evaporators, butanone is sloughed under 45 DEG C, 0.01MPa vacuum conditions, obtain carboxylic acid/sulfonic acid mixed type colored water
Property polyaminoester emulsion.
If other conditions of the present embodiment are constant, and change TEA into sodium hydroxides, what can be stablized is coloured aqueous poly-
Urethane emulsion.
If other conditions of the present embodiment are constant, and change IPDI into MDI, TDI or HDI, what can be stablized is coloured
Aqueous polyurethane emulsion.
Embodiment 5:
By 56.00g number-average molecular weights MnFor 2000 PTMG be dehydrated 1 hour at 110 DEG C after be cooled to 50 DEG C, Ran Houjia
Enter 22.23g IPDI, 6.03g DMPA, 0.89g sulfonic acid type azo hydrophilic chain extenders are added after 2 hours in 90 DEG C of stirring reactions
(BAPBDA), 1.80g BDO, 0.05g dibutyl tin laurates, 0.05g stannous octoates and 85.00g butanone.Constant temperature is at 70 DEG C
Stirring reaction is cooled to 25 DEG C after 5 hours, reaction solution is transferred into high speed shear dispersion machine, added under conditions of 3000 revs/min
5.0g TEA, reaction 5 minutes after add 200g water, be stirred for that reaction solution is transferred into Rotary Evaporators after 5 minutes, 50 DEG C,
Butanone is sloughed under 0.01MPa vacuum conditions, that is, is obtained solid containing (non-aqueous non-solvent material and water-based poly- ammonia in aqueous polyurethane
The mass ratio of ester emulsion) it is 30.3%, DMPA and azo the hydrophilic chain extender non-aqueous non-solvent material in aqueous polyurethane
Middle content is respectively 6.94% and 1.02% azo-type anion aqueous polyurethane emulsion PU2.
Table 1
Such as keep other conditions constant, BAPBDA replacing wholes DMPA (mol ratio replacement) can equally be obtained into azo-type
Anion aqueous polyurethane emulsion PU4.Such as keep other conditions constant, according to the formula rate of table 1, adjust BDO's and BAPBDA
The ratio between amount of material, it is respectively 0.51% and 1.53% that aqueous polyurethane PU0 and the BAPBDA content without BAPBDA, which is made,
Anion azo aqueous polyurethane PU1, PU3.Wt% is that BAPBDA accounts for non-aqueous non-solvent material in aqueous polyurethane in table 1
The percentage of quality.Such as keep other conditions constant, can by adjust PTMG, IPDI, DMPA and BAPBDA material amount it
Than the side chain for obtaining BAPBDA content differences (0.2-20.87%) in non-aqueous non-solvent material in aqueous polyurethane is even
Nitrogen type anion aqueous polyurethane emulsion.
Fig. 1 is for the synthetically prepared azo-type anion aqueous polyurethane (PU1, PU2, PU3) of the present embodiment and without sulfonic acid
The Fourier transform infrared spectroscopy figure of the anion aqueous polyurethane (PU0) of type azo hydrophilic chain extender.Find out the spy of polyurethane
Sign absworption peak is located at 3334cm respectively-1(νN-H)、2856-2949cm-1(νCH2andνCH3)、1714cm-1(νC=O) and 1114cm-1
(νC-O-C) place;In azo-type anion aqueous polyurethane spectrogram, all characteristic absorption peaks of polyurethane are not only can be seen that, it is also aobvious
1570cm is shown-1And 1415cm-1The characteristic absorption peak at (phenyl ring in azo-compound structure) place, illustrates that sulfonic acid type azo is hydrophilic
Chain extender take part in reaction in synthetically prepared polyurethane completely.
Azo chromophore part in azo anion aqueous polyurethane PU2 strands has typical photic configuration isomery
Characteristic.Accompanying drawing 2 is azo anion aqueous polyurethane emulsion PU2 in wavelength 365nm, radiant illumination 6mW/cm2Illumination under
443nm or so place's absorbances caused by the transisomer of azobenzene structure part changes to the configuration of cis-isomer
Change.As the absorbance at extension, 443nm or so the place of irradiation time is gradually reduced;Irradiate in 0-10 minutes, absorbance
Value is rapid to be reduced;About after 16 minutes, absorbance change very little, at the 34th minute, the apparent colour of emulsion was from during firm irradiation
Orange-yellow to be changed into colourless, absorbance no longer changes substantially.After self-emulsifying process, the azo component position with hydrophilic radical
Outside polyurethane milk-globule, i.e., the azo monomer cell distribution with strongly hydrophilic sulfonate structures is formed in milk-globule particle surface
Stable double electrical layerses, by ultraviolet light, the azobenzene of anti-configuration is completely reformed into cis structure in the extremely short time
Type, cis-trans isomerization efficiency reach 100%.Stop irradiation after, due to molecular thermalmotion, azobenzene structure be partially in energy compared with
The cis-isomer of high state gradually changes to transisomer again, and this reversible cis-trans isomerization change is final to make emulsion again
Apparent colour from it is colourless be changed into it is orange-yellow.Azo in description of test azo polyurethane strand manufactured in the present embodiment
Chromophore has typical photic configuration isomery characteristic, and with 100% isomerization efficiency.
Take a certain amount of azo aqueous polyurethane emulsion to pour on clean glass plate, be put at level and place one week, allow breast
Moisture in liquid slowly volatilizees, and is then placed in baking oven 60 DEG C of dryings two days to constant weight, azo aqueous polyurethane milk-globule film is made,
Its thickness is between 100-120 μm.Table 2 is azo-type anion aqueous polyurethane film (PU1, PU2, PU3 manufactured in the present embodiment
And PU4), after by 365nm ultraviolet lights 20 minutes, the contact angle of film reduces polyurethane film.Fig. 3 is this implementation
PU1 films prepared by example pass through ultraviolet lighting polyurethane film contact angle variation diagram, and polymer film is made to locate under 365nm ultraviolet lightings
For reason after 10 minutes, contact angle is reduced to 77.84 ° from 81.31 °.Milk-globule film is after the irradiation of 365nm ultraviolets, due to cis-structure
Formation, cis isomeric effect molecule and the dipole moment change and structural rearrangement effect of trans-azobenzene, cause Static Water to connect
Feeler reduces.
Table 2
Fig. 4 is particle diameters of the azo aqueous polyurethane emulsion PU4 manufactured in the present embodiment after ultraviolet light (365nm) pre-irradiation
Distribution map, as can be seen from the figure the configuration of azo double bond be transformed into cis-configuration from trans, which results in milk-globule particle
The change in footpath, illustrate that the emulsion has good ultraviolet light response.It is water-based being formed because azo group is located at polyurethane side chain
During the self-emulsifying of polyaminoester emulsion, azo functional unit is distributed in the double electrical layerses surface of milk-globule particle formation, ultraviolet
Light can be easy to the azo functional group being irradiated to positioned at electric double layer surface and cis-trans isomerism effect occurs.Meanwhile from molecule
From the perspective of accumulation, even closer accumulation mode is more readily formed in the anti-configuration of azo double bond.And cis-structure is then anti-
It.So after ultraviolet light, the particle diameter of emulsion particle increases, while particle diameter distribution broadens.