JP2010211182A - Liquid crystal capsule and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tough liquid crystal capsule capable of resisting pressurization or the like during use. <P>SOLUTION: In the liquid crystal capsule constituted by including a liquid crystal material in a hollow part of a hollow capsule composed of a shell and the hollow part, the shell includes a layer composed of: a polymer of crosslinkable monomers or a copolymer of two or more crosslinkable monomers; or a copolymer of at least one crosslinkable monomer and at least one monofunctional monomer. The polymer or the copolymer contains 5 to 100 wt.%. of crosslinkable monomers. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a liquid crystal capsule and a manufacturing method thereof.

  A liquid crystal capsule in which a liquid crystal material is included in a hollow portion of a hollow capsule is used as a display material for a liquid crystal screen, electronic paper, or the like (for example, Patent Document 1).

  The liquid crystal capsules are required to have toughness that can withstand pressure during use.

International Publication WO2005 / 062119

  An object of the present invention is to provide a tough liquid crystal capsule that can withstand pressurization during use.

The present invention provides a liquid crystal capsule and a method for producing the same as described below.
Item 1. A liquid crystal capsule in which a liquid crystal material is encapsulated in a hollow portion of a hollow capsule composed of a shell and a hollow portion, wherein the shell is a polymer of a crosslinkable monomer, a copolymer of two or more crosslinkable monomers, or at least one type A liquid crystal capsule comprising a layer composed of a copolymer of a crosslinkable monomer and at least one monofunctional monomer, wherein the polymer or copolymer contains 5 to 100% by weight of a crosslinkable monomer component.
Item 2. Item 2. The liquid crystal capsule according to item 1, wherein the average particle size is 0.05 to 35 µm.
Item 3. Item 3. The liquid crystal capsule according to item 1 or 2, wherein the shell includes a layer composed of a copolymer of at least one crosslinkable monomer and at least one monofunctional monomer.
Item 4. Item 4. The liquid crystal capsule according to item 3, wherein the ratio of the crosslinkable monomer in the polymer is 5 to 95% by weight.
Item 5. Item 5. The liquid crystal capsule according to any one of items 1 to 4, comprising 10 to 90% by weight of the liquid crystal material with respect to the total amount of the liquid crystal capsule.
Item 6. (I) a liquid crystal material, (ii) a monomer component containing 5 to 100% by weight of at least one crosslinkable monomer, and 0 to 95% by weight of at least one monofunctional monomer in an aqueous dispersion stabilizer solution ( iii) Low compatibility with the polymer (PA) obtained by polymerizing or copolymerizing the monomer component, and the interfacial tension (γ ^x ) (mN / m) between the auxiliary polymer and water and the polymer ( In the relationship between the interfacial tension (γ ^y ) (mN / m) between PA) and water, the auxiliary polymer satisfying the condition of γ ^x ≧ γ ^y and (iv) a mixture of initiators are dispersed and suspended. A method for producing a liquid crystal capsule, comprising a step of performing a polymerization reaction.
Item 7. Item 7. The method according to Item 6, wherein the liquid crystal material is used in an amount of 10 to 90% by weight based on the total amount of the liquid crystal capsules.
Item 8. Item 6. A switching material for display of a display comprising the liquid crystal capsule according to any one of items 1 to 5.

  Hereinafter, the present invention will be described in detail.

[Liquid crystal capsule]
In the liquid crystal capsule of the present invention, a liquid crystal material is encapsulated in a hollow portion of a hollow capsule composed of a shell and a hollow portion, and the shell is a polymer or copolymer of at least one crosslinkable monomer, or at least one crosslinkable monomer. And a layer composed of a copolymer of at least one monofunctional monomer, and the polymer or copolymer is a liquid crystal capsule containing 5 to 100% by weight of a crosslinkable monomer component.

  That is, the shell of the liquid crystal capsule of the present invention includes a layer obtained by polymerizing or copolymerizing a crosslinkable monomer or copolymerizing a crosslinkable monomer and a monofunctional monomer. Is used in an amount of about 5 to 100% by weight based on the total monomers. The layer of the polymer or copolymer of the shell has a substantially single layer structure. The shell may consist of only this layer or may have other layers.

  About 10 to 100 weight% is preferable and, as for the ratio of the crosslinkable monomer component which occupies in the polymer or copolymer which comprises the shell of the capsule of this invention, 20 to 100 weight% is more preferable. If the ratio of the crosslinkable monomer component is within the above range, it has sufficient strength and toughness and can withstand the pressure applied during use. As a result, the liquid crystal performance is maintained for a long time.

  In the liquid crystal capsule of the present invention, when the above monofunctional monomer is used as the monomer constituting the shell, the ratio of the crosslinkable monomer in the polymer is preferably about 5 to 95% by weight, and preferably 15 to 80% by weight. What is about% is more preferable.

  The average particle size of the liquid crystal capsules of the present invention is preferably about 0.05 to 35 μm, more preferably about 0.1 to 15 μm. Capsules exceeding 35 μm may become porous fine particles having no hollow part.

  This average particle diameter is an average value of particle diameters when 100 capsules are measured with an electron microscope or an optical microscope. When the average particle size is within the above range, the shell has an appropriate specific interfacial area and is easy to handle, and the shell wall has a sufficiently large relative thickness and is not easily destroyed. The average particle diameter can be adjusted by the method described later.

  Moreover, the volume ratio of the hollow part in the liquid crystal capsule of the present invention is preferably about 10 to 80%, particularly preferably about 10 to 60%. If the volume ratio of the hollow portion is within the range, the relative inclusion amount of the liquid crystal material and thus the liquid crystal performance become sufficient, and the shell wall becomes relatively thick and hardly broken.

Here, in the present specification, the “volume ratio of the hollow portion” R is calculated according to the following formula.
R (%) = (rh / rp) ³ × 100
(In the formula, rh is the radius of the hollow portion of the aromatic fine particles (1/2 of the inner diameter of the shell), and rp is the radius of the aromatic fine particles (1/2 of the outer diameter of the shell).)
The radius for calculating the volume ratio of the hollow portion is a value measured by an electron microscope or an optical microscope.

[Liquid crystal materials]
The liquid crystal material is not particularly limited as long as it is compatible with the monomer constituting the shell and hardly soluble in water.

  Such liquid crystal materials include low-molecular liquid crystals such as nematic liquid crystals, smectic liquid crystals, cholesteric liquid crystals (including chiral nematic liquid crystals), or dichroic dyes (molecular major axis direction and minor axis direction). And guest-host liquid crystals to which dyes having different absorbances are added. Among these, cholesteric liquid crystals are suitable, for example, steroidal cholesterol derivatives; chiral substances such as Schiff bases having an asymmetric carbon, azo series, ester series, and biphenyl series; Nematics such as azo, azoxy, ethane, biphenyl, terphenyl, cyclohexylcarboxylate, phenylcyclohexane, benzoate, pyrimidine, dioxane, tolane, cyclohexylcyclohexane ester, alkenyl And a liquid crystal material added to a liquid crystal or a mixture thereof.

  The content of the liquid crystal material in the liquid crystal capsule of the present invention is preferably about 10 to 90% by weight, more preferably about 40 to 80% by weight with respect to the total amount of the liquid crystal capsule. When the amount is within the above range, sufficient liquid crystal performance can be obtained, and the relative thickness of the shell wall is sufficient, so that it is difficult to be destroyed. In this specification, the ratio of the inclusion amount of the liquid crystal material can be easily obtained by calculation based on the charged weight ratio.

[Crosslinking monomer]
The crosslinkable monomer is preferably hydrophobic, but this requirement is usually met.

  As the crosslinkable monomer of the copolymer layer constituting the shell of the liquid crystal capsule of the present invention, a polyfunctional monomer having two or more polymerizable reactive groups, particularly 2 or more polymerizable double bonds (particularly 2 to 4) is used. It can be illustrated. In particular, a polyfunctional monomer having two or more polymerizable C═C double bonds (particularly 2 to 4) is preferable. For example, divinylbenzene, divinylbiphenyl, divinylnaphthalene, diallyl phthalate, triallyl cyanurate, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate and the like can be mentioned. Particularly preferred are divinylbenzene and ethylene glycol dimethacrylate, and most preferred is ethylene glycol dimethacrylate. A polyfunctional monomer can be used individually or in mixture of 2 or more types.

[Monofunctional monomer]
The monofunctional monomer is also preferably hydrophobic, but this condition is usually met.

  Examples of the monofunctional monomer include monovinyl aromatic monomers, (meth) acrylic monomers, vinyl ester monomers, vinyl ether monomers, monoolefin monomers, halogenated olefin monomers, and diolefins.

  The monovinyl aromatic monomer may be a monovinyl aromatic hydrocarbon, a vinyl biphenyl optionally substituted with a lower (C1-4) alkyl group, or a lower (C1-4) alkyl group. Good vinyl naphthalene etc. are mentioned.

  Specific examples of the monovinyl aromatic hydrocarbon include styrene, α-methylstyrene, vinyltoluene, α-chlorostyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, sodium styrenesulfonate, and the like. .

  Furthermore, vinyl biphenyl which may be substituted with a lower alkyl group, and vinyl naphthalene which may be substituted with a lower alkyl group include lower (C1-4) alkyl groups such as vinyl biphenyl, methyl group and ethyl group. And vinyl naphthalene substituted with lower (1 to 4 carbon atoms) alkyl group such as vinyl biphenyl, vinyl naphthalene, methyl group, and ethyl group. These monovinyl aromatic monomers can be used alone or in combination of two or more.

  Specific examples of the (meth) acrylic monomer include acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenyl acrylate, methyl methacrylate, methacryl Acid butyl, hexyl methacrylate, 2-ethylhexyl methacrylate, β-hydroxyethyl acrylate, γ-hydroxybutyl acrylate, δ-hydroxybutyl acrylate, β-hydroxyethyl methacrylate, γ-aminopropyl acrylate, acrylic acid γ-N, N-diethylaminopropyl and the like can be mentioned.

  Specific examples of the vinyl ester monomer include vinyl formate, vinyl acetate, vinyl propionate and the like.

  Specific examples of the vinyl ether monomer include vinyl methyl ether, vinyl ethyl ether, vinyl n-butyl ether, vinyl phenyl ether, vinyl cyclohexyl ether and the like.

  Specific examples of the monoolefin monomer include ethylene, propylene, butene-1, pentene-1, 4-methylpentene-1, and the like.

  Examples of the halogenated olefin-based monomer include vinyl chloride and vinylidene chloride.

  Furthermore, diolefins such as butadiene, isoprene, chloroprene and the like can also be included in the monofunctional monomer.

  Monofunctional monomers can be used alone or in admixture of two or more.

  As the monofunctional monomer to be copolymerized with the crosslinkable monomer, a monovinyl aromatic monomer, a (meth) acrylic monomer, a vinyl ester monomer, a vinyl ether monomer, and the like are preferable. A monovinyl aromatic monomer and a (meth) acrylic monomer are preferable. Monomers are more preferred. Of the monovinyl aromatic monomers, styrene is preferred. Among (meth) acrylic monomers, (meth) acrylic acid esters such as butyl acrylate, ethyl acrylate, and butyl methacrylate are preferred.

[Combination of crosslinkable monomer and monofunctional monomer]
Although sufficient liquid crystal material-containing particles can be obtained even with the crosslinkable monomer alone, examples of suitable combinations of the crosslinkable monomer and the monofunctional monomer include the combinations shown in Table 1 below.

[Method of manufacturing liquid crystal capsule]
The liquid crystal capsule of the present invention can be produced by various methods, for example, by the following method.

That is, in an aqueous dispersion stabilizer solution,
(I) liquid crystal material,
(Ii) a monomer component containing 5 to 100% by weight of at least one crosslinkable monomer and 0 to 95% by weight of at least one monofunctional monomer;
(Iii) Low compatibility with the polymer (PA) obtained by polymerizing or copolymerizing the monomer component, and the interfacial tension (γ ^x ) (mN / m) between the auxiliary polymer and water and the polymer An auxiliary polymer that satisfies the condition of γ ^x ≧ γ ^y in the relationship with the interfacial tension (γ ^y ) (mN / m) between (PA) and water, and (iv) a mixture consisting of an initiator is dispersed, This is a method of performing a suspension polymerization reaction.

[Dispersion stabilizer]
As the dispersion stabilizer, those having a function of preventing droplets formed by dispersing a mixture of a liquid crystal material, a monomer component, an auxiliary polymer and an initiator in water from being combined can be used from a wide range.

  For example, polymer dispersion stabilizers such as polyvinyl alcohol, methyl cellulose, ethyl cellulose, polyacrylic acid, polyacrylimide, polyethylene oxide, poly (hydroxystearic acid-g-methyl methacrylate-co-methacrylic acid) copolymer, nonion -Based surfactants, anionic surfactants, amphoteric surfactants and the like. Among these, polymer dispersion stabilizers such as polyvinyl alcohol are preferable.

  The amount of these dispersion stabilizers to be used can be selected from a wide range, but is generally about 0.005 to 1 part by weight with respect to 1 part by weight of the mixture of the liquid crystal material, the monomer component, the auxiliary polymer and the initiator. The amount is preferably about 0.01 to 0.1 parts by weight.

  Further, the concentration of the dispersion stabilizer in the aqueous dispersion stabilizer solution may be appropriately selected so that the droplets do not coalesce. In general, the concentration of the aqueous dispersion stabilizer solution is preferably adjusted to about 0.05 to 5% by weight, particularly about 0.1 to 1% by weight.

[Liquid crystal materials]
The kind of liquid crystal material and the amount used are as described above.

  In addition, it is preferable to use a component that satisfies the following requirements 1) to 3) as the liquid crystal material.

That is,
1) High compatibility with monomer components.
2) Low compatibility with a polymer (PA) obtained by polymerizing or copolymerizing monomer components.
3) and the surface tension ^{(γ z) (mN / m} ) between the liquid crystal material and the water, in relation to the interfacial tension ^{(γ y) (mN / m} ) between the polymer (PA) and water, gamma Satisfy the condition of ^z ≧ γ ^y .

  When a liquid crystal material that satisfies the requirements 1) to 3) is used, an auxiliary polymer may be used, but it may not be used.

  The combination of the polymer (PA) satisfying the requirements 1) to 3) and the liquid crystal material can be easily selected by the method described later. For example, ethylene glycol dimethacrylate and monofunctional monomer which are polyfunctional monomers And a combination of a polymer obtained from butyl methacrylate and a cyanobiphenyl analog of a liquid crystal material.

  In the present specification, the compatibility between the liquid crystal material and the polymer (PA) is measured by the following method. That is, an initiator (2% by weight with respect to the monomer component) is added to a monomer component solution containing a monomer component and a liquid crystal material as raw materials for the polymer (PA), and if necessary, toluene in an appropriate weight ratio. Then, the polymerization reaction of the monomer component is caused in a nitrogen gas atmosphere at 30 ° C. This reaction is carried out in a quartz glass cell having an optical path length of 1 cm, and the light transmittance is measured over time when irradiated with light having a wavelength of 600 nm. As the concentration of the liquid crystal material is increased, the transmittance, which was about 100% at the beginning, rapidly decreases to near 0% when the polymerization time elapses due to phase separation of the polymer (PA). In this case, when the compatibility between the liquid crystal material and the polymer (PA) is low, the liquid crystal material is reduced to nearly 0%. However, when the compatibility between the liquid crystal material and the polymer (PA) is high, the transmittance is hardly reduced. Further, the lower the compatibility between the liquid crystal material and the polymer (PA), the shorter the time from the start of polymerization until the decrease in transmittance occurs.

  As a liquid crystal material having low compatibility with the polymer (PA), the transmittance is about 1 to 10%, preferably about 1 to 5% when the transmittance is measured by the above method. A liquid crystal material in which a decrease in the above occurs.

  In the present specification, the interfacial tension is a value measured by Dunui's platinum ring method as defined in ASTM-971-50.

  When a liquid crystal material satisfying the requirements of 1) to 3) is used, the liquid crystal material is a phase of a monomer component and a polymer (PA) obtained by polymerization or copolymerization without using an auxiliary polymer. Promote separation.

  Even without using an auxiliary polymer, the monomer component is polymerized or copolymerized into a polymer (PA) in a uniform solution of liquid crystal material, monomer component and initiator, and the polymer is adsorbed at the interface with water. In this case, the polymer (PA) is more easily adsorbed at the interface with water than the liquid crystal material, and as a result, fine particles in which the liquid crystal material is encapsulated inside the shell made of the polymer (PA) are obtained.

[Auxiliary polymer]
As the auxiliary polymer, polymers satisfying the following requirements 4) and 5) can be widely used.

That is,
4) Low compatibility with a polymer (PA) obtained by polymerizing or copolymerizing monomer components.
5) in relation to the interfacial tension ^{(γ y) (mN / m} ) between the interfacial tension (gamma ^x) and (mN / m) and the polymer (PA) and water between the auxiliary polymer and water, gamma ^x The condition of ≧ γ ^y is satisfied.

  Specifically, as the auxiliary polymer, a polymer having a lower polarity than a polymer (PA) obtained by copolymerizing a crosslinkable monomer component and a monofunctional monomer can be used.

  In this specification, the compatibility between the auxiliary polymer and the polymer (PA) is measured by using the auxiliary polymer in addition to the liquid crystal material in the method described for the compatibility between the liquid crystal material and the polymer (PA). .

  Examples of the auxiliary polymer having low compatibility with the polymer (PA) include auxiliary polymers in which the polymerization rate of the monomer component is about 0.01 to 4% and the transmittance is lowered.

  The interfacial tension is a value measured by Dunui's platinum ring method as defined in ASTM-971-50 as described above.

  The auxiliary polymer is desirably dissolved in the monomer component, but this condition is usually satisfied.

  The auxiliary polymer satisfying the requirements of 4) and 5) promotes phase separation between the monomer component and the polymer (PA) obtained by polymerization or copolymerization thereof.

  Further, in the mixture of the liquid crystal material, the monomer component, the auxiliary polymer and the initiator, the monomer component is copolymerized to become a polymer (PA), and the polymer (PA) is adsorbed at the interface with water. ) Is more easily adsorbed at the interface with water than the auxiliary polymer, and as a result, fine particles in which a liquid crystal material is encapsulated inside a shell made of polymer (PA) are obtained.

  As such an auxiliary polymer, for example, polystyrene, polymethyl methacrylate, polybutyl methacrylate, or a copolymer thereof can be used.

  The combination of the monomer component and the auxiliary polymer that satisfies the requirements of 4) and 5) can be easily selected by the above-described method. For example, the combinations in Table 2 below can be exemplified.

  The amount of the auxiliary polymer used can be appropriately selected from a wide range, but is generally about 0.01 to 0.4 parts by weight, particularly about 0.05 to 0.2 parts by weight with respect to 1 part by weight of the monomer component. It is preferable to do this.

  The molecular weight of the auxiliary polymer can usually be about tens of thousands to hundreds of thousands.

[Initiator]
The initiator used in the method of the present invention starts polymerization of the monomer component in the droplet, and an oil-soluble polymerization initiator can be widely used. For example, azo compounds such as azobisisobutyronitrile which is a radical polymerization initiator, cumene hydroperoxide, t-butyl hydroperoxide, dicumyl peroxide, di-t-butyl peroxide, benzoyl peroxide, lauroyl peroxide, etc. Those soluble in monomers such as peroxides can be mentioned. Moreover, you may use the photoinitiator which starts superposition | polymerization by light, such as an ultraviolet-ray. Such a photopolymerization initiator is not particularly limited as long as it is oil-soluble, and includes those conventionally used.

  The amount of the initiator used is preferably about 0.005 to 0.1 part by weight, particularly about 0.01 to 0.06 part by weight, based on 1 part by weight of the monomer component.

[Dispersion process]
In the method of the present invention, a suspension polymerization is performed by dispersing a mixture containing the liquid crystal material, the monomer component, the initiator, and the auxiliary polymer in the above-described use ratio in an aqueous solution of the dispersion stabilizer.

  The liquid crystal material, auxiliary polymer and initiator are preferably dissolved in the monomer component to form a uniform solution. There is no limitation in particular as temperature at the time of mixing, For example, what is necessary is just to mix at about 0-30 degreeC.

  The liquid crystal material, monomer component, initiator and auxiliary polymer mixture thus obtained are then dispersed in an aqueous solution of the dispersion stabilizer.

  The mixture is preferably used in an amount of about 1 to 200 parts by weight, particularly about 10 to 100 parts by weight per 100 parts by weight of the aqueous dispersion stabilizer solution, but is not limited to this range. Absent.

  As the dispersion method, various known methods such as a dispersion method using mechanical shearing force such as a homogenizer or a membrane emulsification method can be employed. Although the temperature condition in the case of dispersion | distribution will not be limited if it is below the temperature which affects decomposition | disassembly of the liquid crystal material to be used and an initiator, It is preferable that it is about 0-30 degreeC.

  In the above dispersion method, the size of droplets formed by dispersing a uniform mixture of liquid crystal material, monomer component, initiator and auxiliary polymer is not monodispersed, but generally a mixture of droplets of various different particle sizes It becomes. Therefore, finally obtained liquid crystal capsules also have different particle sizes.

  On the other hand, by selecting a dispersion method, it is possible to make the size of the droplets uniform and obtain monodispersed droplets. As a method for obtaining such monodispersed droplets, for example, a method of producing monodispersed droplets by a membrane emulsification method using porous glass (SPG) or a seed swelling method (described in JP-A-8-20604). Method).

  When such monodispersed droplets having a uniform particle diameter are prepared, the finally obtained liquid crystal capsule is also monodispersed with a uniform particle diameter.

  In any case, the average particle size of the droplets may be appropriately determined according to the desired average particle size of the liquid crystal capsule, but is generally about 0.05 to 35 μm, particularly about 0.1 to 15 μm. Is preferred. By appropriately setting the viscosity of the mixture of the liquid crystal material, the monomer component, the initiator and the auxiliary polymer, the amount of the dispersion stabilizer used, the viscosity of the aqueous dispersion stabilizer solution, and the dispersion method / dispersion conditions within the above range, the droplets within the above range are used. An average particle size is obtained.

[Suspension polymerization]
In order to use the aqueous solution of the dispersion stabilizer in which a uniform mixture of the liquid crystal material, monomer component, initiator and auxiliary polymer thus obtained is subjected to suspension polymerization, the aqueous solution may be heated while stirring.

  The heating temperature is not particularly limited as long as it is a temperature that allows the monomer component to be polymerized by the initiator in the liquid droplet material, a uniform mixture of the monomer component, the initiator, and the auxiliary polymer. About -90 degreeC and especially about 40-70 degreeC are preferable.

  Suspension polymerization is performed until a desired liquid crystal capsule is obtained. The time required for suspension polymerization varies depending on the type of liquid crystal material, monomer component, and initiator used, but is generally about 3 to 48 hours.

  The suspension polymerization is preferably performed in an inert gas atmosphere such as nitrogen gas or argon gas.

  By performing suspension polymerization in this way, the monomer component is polymerized in the droplets of the mixture of the liquid crystal material, the monomer component, the initiator and the auxiliary polymer.

  In the obtained monomer component copolymer (PA), the phase separation is promoted by the presence of the liquid crystal material or the auxiliary polymer, and as a result, a shell having a single layer structure, that is, a polymer (PA) is formed. Is done. On the other hand, the hollow portion is in a state in which a liquid crystal material and possibly an auxiliary polymer are included.

The liquid crystal capsules thus obtained may be used in the form of a dispersion, or after being filtered and washed with water as necessary, can be used for various purposes in the form of powder. In the case of obtaining a liquid crystal capsule in the form of powder by drying the dispersion, under conditions of temperature and pressure at which the liquid crystal material does not evaporate, for example, a temperature of about 0 to 50 ° C. and a pressure of about 10 ³ to 10 ⁵ Pa Can be dried. The fine particles can also be dried by natural evaporation, reduced pressure treatment, or the use of a desiccant such as silica gel.

  The liquid crystal capsule of the present invention is excellent in strength and toughness because the ratio of the crosslinkable monomer component in the polymer or copolymer layer constituting the shell is as large as 5 to 100% by weight, and used as a display material or a switching material. In addition, it has sufficient practical durability. In particular, when the liquid crystal capsule is used as a display switching material for a display, it not only has excellent durability, but also has excellent display characteristics, switching characteristics, and the like, and therefore can be suitably used.

  The method for producing a liquid crystal capsule of the present invention does not have a complicated process and can produce a tough liquid crystal capsule easily and efficiently.

It is a polarizing microscope photograph of the liquid crystal capsule manufactured in Example 1 of this invention (observation temperature [i] 25 degreeC). It is a polarizing microscope photograph of the liquid crystal capsule manufactured in Example 1 of this invention (observation temperature [ii] 60 degreeC). It is a polarizing microscope photograph of the liquid crystal capsule manufactured in Example 1 of this invention (observation temperature [iii] 25 degreeC). Liquid crystal-encapsulated capsule particles when the liquid crystal capsule produced in Example 1 of the present invention was subjected to repeated temperature increase / decrease (35 ° C. to 75 ° C.) (operation speed: 5 ° C./min) (11 .15 mg) differential scanning calorimetry curve.

  Next, although an Example is given and this invention is demonstrated in more detail, this invention is not limited to these.

Example 1
In 37 g of ion-exchanged water in which 0.37 g of polyvinyl alcohol is dissolved, 3 g of liquid crystal (trade name “E-7”, manufactured by Fluoromaterial Co., Ltd.), 0.3 g of polystyrene (molecular weight 200,000) (10% by weight with respect to the monomer) and An emulsion (dispersion liquid) is prepared by dispersing 3 g of ethylene glycol dimethacrylate (EGDM) monomer in which 0.12 g of benzoyl peroxide (4% by weight with respect to the monomer) is dissolved by a membrane emulsification method (membrane pore diameter 0.8 μm). did. When the emulsion was observed with an optical microscope in this state, the ethylene glycol dimethacrylate / liquid crystal / benzoyl peroxide droplets were spherical and had a particle size of about 3 to 4 μm. The emulsion was then allowed to react at 70 ° C. for 24 hours while stirring in a seal.

  The polymer obtained by the polymerization reaction was filtered and then dried to obtain liquid crystal capsule fine particles. The average particle diameter of the fine particles was 3 μm.

  When these fine particles were observed using an optical microscope and an ultrathin section of the fine particles was observed using a transmission microscope, hollow fine particles having a void at the center were observed. Moreover, when the observation temperature was continuously changed with a polarizing microscope from [i] 25 ° C. → [ii] 60 ° C. → [iii] 25 ° C., the core portion always showed polarization at 25 ° C. On the other hand, it was confirmed that no polarization was exhibited at 60 ° C. From this, it was confirmed that the liquid crystal capsule obtained in Example 1 has a switching function. It was confirmed by differential scanning calorimetry (Seiko Instruments Inc., DSC6200, operation speed 5 ° C./min) that the inclusion was a liquid crystal. That is, in the differential scanning calorimetry, the operation of 35 ° C. → 75 ° C. → 35 ° C. is taken as one cycle, and as a result of continuous measurement of 100 cycles, endothermic and exothermic peaks are observed in the temperature rising and cooling processes, respectively. The amount of heat measured was always about 1 Joule / g-liquid crystal, and the liquid crystal properties of the liquid crystal capsule were maintained. Moreover, when toughness was evaluated, it showed excellent toughness.

Example 2
Liquid crystal capsule fine particles were obtained in the same manner as in Example 1, except that the amount of polystyrene used was 0.18 g (6% by weight based on the EGDM monomer).

  The average particle diameter, shell thickness, volume ratio of the hollow portion, and toughness were the same as those of the fine particles obtained in Example 1.

Example 3
In Example 1, liquid crystal capsule fine particles were obtained in the same manner as in Example 1 except that the molecular weight of polystyrene was 40,000.

  The average particle diameter, shell thickness, volume ratio of the hollow portion, and toughness were the same as those of the fine particles obtained in Example 1.

Example 4
Liquid crystal capsule fine particles were obtained in the same manner as in Example 1 except that the amount of benzoyl peroxide used was 0.03 g (1 wt% based on the EGDM monomer).

  The average particle diameter, shell thickness, volume ratio of the hollow portion, and toughness were the same as those of the fine particles obtained in Example 1.

Example 5
In Example 1, liquid crystal capsule fine particles were obtained in the same manner as in Example 1 except that 2.7 g of ethylene glycol dimethacrylate and 0.3 g of butyl methacrylate were used as monomers.

  The average particle diameter, shell thickness, volume ratio of the hollow portion, and toughness were the same as those of the fine particles obtained in Example 1.

  The liquid crystal capsules of the present invention are used as display materials and switching materials such as liquid crystal screens and electronic paper.

Claims (8)

  A liquid crystal capsule in which a liquid crystal material is encapsulated in a hollow portion of a hollow capsule comprising a shell and a hollow portion, wherein the shell is a polymer of a crosslinkable monomer, a copolymer of two or more crosslinkable monomers, or at least one type A liquid crystal capsule comprising a layer composed of a copolymer of a crosslinkable monomer and at least one monofunctional monomer, wherein the polymer or copolymer contains 5 to 100% by weight of a crosslinkable monomer component.   The liquid crystal capsule according to claim 1, having an average particle diameter of 0.05 to 35 μm.   The liquid crystal capsule according to claim 1 or 2, wherein the shell includes a layer composed of a copolymer of at least one crosslinkable monomer and at least one monofunctional monomer.   The liquid crystal capsule according to claim 3, wherein a ratio of the crosslinkable monomer in the polymer is 5 to 95% by weight.   The liquid crystal capsule according to any one of claims 1 to 4, comprising 10 to 90% by weight of the liquid crystal material with respect to the total amount of the liquid crystal capsule. In an aqueous dispersion stabilizer solution,
(I) liquid crystal material,
(Ii) a monomer component containing 5 to 100% by weight of at least one crosslinkable monomer and 0 to 95% by weight of at least one monofunctional monomer;
(Iii) Low compatibility with the polymer (PA) obtained by polymerizing or copolymerizing the monomer component, and the interfacial tension (γ ^x ) (mN / m) between the auxiliary polymer and water and the polymer In the relationship with the interfacial tension (γ ^y ) (mN / m) between (PA) and water, an auxiliary polymer that satisfies the condition of γ ^x ≧ γ ^y and (iv) a mixture of initiators are dispersed and suspended. A method for producing a liquid crystal capsule, comprising a step of carrying out a turbid polymerization reaction.   The method according to claim 6, wherein the liquid crystal material is used in an amount of 10 to 90% by weight based on the total amount of the liquid crystal capsules.   A display switching material for a display, comprising the liquid crystal capsule according to claim 1.

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