Background technology
Electronic paper technology receives extensive concern as a kind of novel technique of display at numerous areas.The sixties in last century, Iota has found the displaying principle of electrophoresis the earliest, promptly moves scattering and the refraction that realizes external light source through the orientation of numerous particles in electric field.But technology at that time can't solve the cohesion and the deposition problems of particle, so this technical scheme lies on the table.After the nineties, people such as Jacobson are applied to this area with microcapsulary, with microcapsule electronic paper technology practicability.
Current, the research to Electronic Paper internal electron ink (being the capsule-core dispersion liquid) generally is confined to double-colored particIe system, and the zeta-potential opposite in sign of the particle of two kinds of colors separately, moves under electric field action round about.Domestic research is more; Paradise like Beijing University of Chemical Technology (CN101550288A) has prepared organic red bluish-green multiple double-colored particle system that waits pigment particles and titanium oxide to form in " a kind of color electrophoresis that is used for the electric ink demonstration shows the preparation method of liquid "; Wherein red, peptide mountain valley with clumps of trees and bamboo indigo plant etc. are broken reunion through recrystallization method, and particle diameter is reduced greatly; The Zhao Xiaopeng of Northwestern Polytechnical University etc. also delivered respectively " preparation method of environment-friendly electronic ink " (CN1506416) with " blue preparing electronic ink microcapsule " (CN1506153).
Among numerous investigators, (CN1438531) such as the Xu Wang of SiPix makes the lattice array and replaces microcapsule on plastic base, realizes the little encapsulation to electrophoresis liquid.Electrophoresis particle wherein prepares through the polymer microballoon surface is coated one deck inorganic oxide coating.People such as the Albert of E-ink have also studied electrophoretic display technology and associated materials (US006017584); Wherein capsule-core dyes with oil-soluble dyes; Electrophoresis particle such as red, white adds charge control agent (charge control agent) in order to improve the electrophoresis rate of colour developing particle simultaneously through the modification of polymkeric substance parcel.
Zeta-potential is the important parameter that influences the particle performance, reflects the fineness of electrophoresis particle on the one hand, determines the electrophoretic migration speed of electrophoresis particle on the other hand.The electrophoretic velocity formula of confirming particle according to the Stokes law should be:
behind the substitution ζ, accurate calculation this shows that for
zeta-potential of particle and electrophoretic velocity are proportional.
And still do not have a kind of effective theory to make an explanation at present and instruct for zeta-potential.In general; The formation of zeta-potential and the electrostatic double layer on particle/liquid surface have close ties (work such as AYAO KITAHARA; " interfacial electric phenomenon " 1-2 page or leaf; BJ University Press's version in 1992), thus its influence factor mainly contain solvent and be dissolved in component, size of particles and shape, particle surface physics-chem characteristic of solvent etc.The characteristics of above-mentioned prior art are: the current potential of particle is lack of consistency; Its positive and negative size and solvent are in close relations, and the adding of the replacing of solvent or new component must influence the size and the symbol of zeta-potential, like carbon black bear in benzene; Add the di-isopropyl SAP 002 and do then lotus positive electricity of dispersion agent; Titanium oxide lotus positive electricity in benzene and for example, and in ETHYLE ACETATE the bear electricity, (work such as AYAO KITAHARA; " interfacial electric phenomenon " 108-109 page or leaf, BJ University Press's version in 1992) so the existing theoretical charged rule of particle in varying environment of temporarily can't grasping; Though US006017584 adds OLOA1200 as charge control agent, this material belongs to terminal and is the long chain polymer of amido, in organic solvent, becomes the positive ion acceptor and becomes the negative electricity charge control agent; And make electrophoresis particle have strong simultaneously also more stable negative electricity; But because electrophoresis capsule-core liquid often contains at least two kinds of colour developing particles, so will reach color developing effect preferably, the electrophoresis direction of particle should be opposite; When a kind of particle bear electricity, then another kind is answered lotus positive electricity.After above-mentioned charge control agent adds, the negative potential that makes all particles in the capsule-core is increased and positive potential weakens to transferring negative electricity to, thereby when improving display speed, reduced the contrast of display degree.
For overcoming above-mentioned shortcoming; The investigator who has considers to add the silane coupling agent that employing contains polymerizable double bond and amido simultaneously particle is handled; To improve the positive potential of particle, like the vinyl benzyl aminoethyl aminopropyl trimethoxysilane hydrochloride that uses among the US7532388.These reagent prices are relatively costly, are unfavorable for the industriallization extensive application.
Summary of the invention
The purpose of this invention is to provide a kind of positive electricity electrophoresis particle and preparation method thereof, to overcome the above-mentioned defective that prior art exists.
Method of the present invention comprises the steps:
(1) with silane-modified pigment particles, in solvent, under the initiator effect, carry out copolymerization with vinylbenzene with to vinyl chloride, obtain copolyreaction liquid;
Described silane-modified pigment particles is for silane coupler modified pigment particles;
Said pigment particles includes but not limited to more than one in titanium oxide, silicon-dioxide, aluminium sesquioxide, chromic oxide, cupric oxide, red stone, plumbous oxide or the powder blue;
Method of modifying can be consulted document " silane coupling agent is to the nano titanium oxide Study on Surface Modification " " Journal of Inorganic Materials " the 21st volume the 2nd interim reported method;
Said silane coupling agent is KH-570;
The chemical name of KH-570 is Y-(methacryloxypropyl) propyl trimethoxy silicane, adopts the commercially available prod;
Said initiator includes but not limited to peroxide radical initiator or azo type free base initiator;
Preferred BPO or Diisopropyl azodicarboxylate;
Cinnamic consumption is with respect to 5%~1000%, preferred 50%~200% of the quality of said silane-modified pigment particles;
To the consumption of vinyl chloride with respect to 0.1%~10% of above-mentioned vinylbenzene quality, preferred 0.5%~2%;
The consumption of initiator is with respect to the vinylbenzene that adds with to 0.01%~10% of vinyl chloride total mass, and preferred 0.1%~1%;
Described solvent includes but not limited to benzene, toluene, chlorobenzene, ETHYLE ACETATE, ethyl ester butyl ester or acetone, preferred toluene; Solvent load is with respect to vinylbenzene with to 20%~1000% of vinyl chloride total mass;
Temperature of reaction is 30~120 ℃, and preferred 60~90 ℃, the reaction times is 0.5~48 hour, preferred 2~12 hours;
(2) the copolyreaction liquid that tertiary amine is added step (1) gained reacts, and from reaction product, collects said positive electricity electrophoresis particle then;
Described tertiary amine includes but not limited to Trimethylamine 99, triethylamine, Tributylamine or trioctylamine, preferred triethylamine or Tributylamine; The tertiary amine consumption is with respect to 20%~1000%, preferred 50%~200% of the molar weight of vinyl chloride;
Temperature of reaction is 30~120 ℃, and preferred 60~90 ℃, the reaction times is 0.5~48 hour, preferred 2-12 hour.
The positive electricity electrophoresis particle of method preparation of the present invention adopts more cheap reagent to vinyl chloride, and pigment particles is carried out the positive electricity modification; After pigment particles surface grafting polymerization thing; Introduce quaternary ammonium salt group again, can avoid the decomposition of quaternary ammonium salt in the long-time polymerization process of high temperature, simultaneously can be through regulating ratio to vinyl chloride; Regulate the different ratios of quaternary ammonium salt, thereby regulate the zeta-potential of particle easily.The pigment particles of positive electricity modification of the present invention, zeta-potential is higher in organic solvent commonly used, and therefore, electrophoretic velocity is also better under the electric field, can be applicable to electrophoretype Electronic Paper aspect.
Embodiment
Embodiment 1
Adopt document " silane coupling agent is to the nano titanium oxide Study on Surface Modification " " Journal of Inorganic Materials " the 21st volume the 2nd interim reported method, with the nanometer Ti0 of KH-570 to coating through silicon oxide surface
2Carry out the method for modification 200g titanium oxide (Du Pont's board-R960 type) pigment particles is carried out silane coupling agent KH-570 modification, hot analysis revealed, titanium dioxide surface is enclosed with the silane coupling agent KH-570 of 4% quality after the modification;
In reaction flask, add the titanium oxide of the above-mentioned KH-570 modification of 100g, add 20g vinylbenzene, 2g to vinyl chloride, 2g Diisopropyl azodicarboxylate, 200g toluene, stir down 50 ℃ of reactions 24 hours;
In the above-mentioned reaction solution, do not lower the temperature, add triethylamine 0.5g, stir down 50 ℃ of reactions 24 hours, after products therefrom is centrifugal, with after the ETHYLE ACETATE washing again whiz get white positive electricity modified particle.Hot analysis revealed, white positive electricity modified particle is coated with the organism of 15% quality.
Embodiment 2
Adopt document " silane coupling agent is to the nano titanium oxide Study on Surface Modification " " Journal of Inorganic Materials " the 21st volume the 2nd interim reported method, with the nano-TiO of KH-570 to coating through silicon oxide surface
2Carry out the method for modification, to 200g Tong Ge ?(PBK-528 of pigment ltd type is reined in by section) pigment particles carry out silane coupling agent KH-570 modification, hot analysis revealed, after the modification Tong Ge ?be coated with the silane coupling agent KH-570 of 3% quality;
In reaction flask, add the above-mentioned KH-570 modification of 100g Tong Ge ?, add 500g vinylbenzene, 2.5g to vinyl chloride, 0.5g BPO, 500g toluene, stir down 100 ℃ of reactions 2 hours;
In the above-mentioned reaction solution, do not lower the temperature, add Tributylamine 15g, stir down 100 ℃ of reactions 3 hours, after products therefrom is centrifugal, with after the toluene wash again whiz get black positive electricity modified particle.Hot analysis revealed, black positive electricity modified particle is coated with the organism of 22% quality
Embodiment 3
Adopt document " silane coupling agent is to the nano titanium oxide Study on Surface Modification " " Journal of Inorganic Materials " the 21st volume the 2nd interim reported method, with the nano-TiO of KH-570 to coating through silicon oxide surface
2Carry out the method for modification, 200g cobalt chrome blue (PB-536 of pigment ltd type is reined in by section) pigment particles is carried out silane coupling agent KH-570 modification, hot analysis revealed, the cobalt chrome blue is coated with the silane coupling agent KH-570 of 3% quality after the modification;
In reaction flask, add the above-mentioned KH-570 modification of 100g Tong Ge ?, add 100g vinylbenzene, 2.5g to vinyl chloride, 1g BPO, 500g ETHYLE ACETATE, stir down 70 ℃ of reactions 12 hours;
In the above-mentioned reaction solution, do not lower the temperature, add Tributylamine 3g, stir down 70 ℃ of reactions 12 hours, after products therefrom is centrifugal, with after the ETHYLE ACETATE washing again whiz get blue positive electricity modified particle.Hot analysis revealed, blue positive electricity modified particle is coated with the organism of 17% quality.
Embodiment 4
Adopt document " silane coupling agent is to the nano titanium oxide Study on Surface Modification " " Journal of Inorganic Materials " the 21st volume the 2nd interim reported method, with the nano-TiO of KH-570 to coating through silicon oxide surface
2Carry out the method for modification, 200g cobalt chrome blue (PB-536 of pigment ltd type is reined in by section) pigment particles is carried out the KH-570 modification, hot analysis revealed, the cobalt chrome blue is coated with the silane coupling agent of 3% quality after the modification;
In reaction flask, add the above-mentioned KH-570 modification of 100g Tong Ge ?, add 100g vinylbenzene, 5g to vinyl chloride, 1g BPO, 500g ETHYLE ACETATE, stir down 70 ℃ of reactions 12 hours;
In the above-mentioned reaction solution, do not lower the temperature, add Tributylamine 6g, stir down 70 ℃ of reactions 12 hours, after products therefrom is centrifugal, with after the ETHYLE ACETATE washing again whiz get blue positive electricity modified particle.Hot analysis revealed, blue positive electricity modified particle is coated with the organism of 16% quality.
Embodiment 5
(1) gets the white positive electricity modified particle 0.02g that embodiment 1 prepares, mix and ultra-sonic dispersion 5min, obtain homodisperse liquid with the 20ml orthodichlorobenzene.
(2) the obtained dispersion liquid of step (1) is got 0.5ml, add in the quartz colorimetric utensil, and insert the Dipcell electrode.According to the working specification of Malvern ZS90 type potentiometer, measure the zeta-potential of this sample three times, averaging is 40mV.
(3) get the black positive electricity modified particle 0.02g that embodiment 2 prepares, mix and ultra-sonic dispersion 5min, obtain homodisperse liquid with 20ml toluene.
(4) the obtained dispersion liquid of step (3) is got 0.5ml, add in the quartz colorimetric utensil, and insert the Dipcell electrode.According to the working specification of Malvern ZS90 type potentiometer, measure the zeta-potential of this sample three times, averaging is 90mV.
(5) get the blue positive electricity modified particle 0.02g that embodiment 3 prepares, mix and ultra-sonic dispersion 5min, obtain homodisperse liquid with the 20ml zellon.
(6) the obtained dispersion liquid of step (5) is got 0.5ml, add in the quartz colorimetric utensil, and insert the Dipcell electrode.According to the working specification of Malvern ZS90 type potentiometer, measure this sample for three times, averaging is 70mV.
(7) get the blue positive electricity modified particle 0.02g that embodiment 4 prepares, mix and ultra-sonic dispersion 5min, obtain homodisperse liquid with the 20ml zellon.
(8) the obtained dispersion liquid of step (7) is got 0.5ml, add in the quartz colorimetric utensil, and insert the Dipcell electrode.According to the working specification of Malvern ZS90 type potentiometer, measure this sample for three times, averaging is 100mV.
Can find out from above-mentioned test result; Adopt the pigment particles of positive electricity modification of the present invention, can regulate the different ratios of quaternary ammonium salt through regulating ratio to vinyl chloride; Thereby regulate the zeta-potential of particle easily, zeta-potential is higher in organic solvent commonly used; Because the zeta-potential and the electrophoretic velocity of particle are proportional, electrophoretic velocity is also better under the electric field, can be applicable to electrophoretype Electronic Paper aspect.
Top description and instance disclose several method of the present invention and material, but the invention is not restricted to above-mentioned specific examples, and it comprises all improvement and variation in the spirit and scope of the present invention that limited in claims of the present invention.