阅读说明：本技术 一种力学性能可控的可反应中空微球及其制备方法 (Reactable hollow microsphere with controllable mechanical property and preparation method thereof ) 是由 刘仁 孙冠卿 姜林萍 于 2021-08-31 设计创作，主要内容包括：本发明公开了一种力学性能可控的可反应中空微球及其制备方法,属于中空微球制备技术领域。本发明结合Pickering乳液模板法与UV光固化技术于一体,中空微球的粒径和壁厚将通过油相组成比、乳化转速的改变实现,其表面所带反应基团可通过油相光敏反应物获得,而其力学性能将通过树脂体系的调配或壁厚的调控实现。本发明的中空微球,粒径5-50μm,表面带有可反应的环氧集团、光敏双键基团,减缩模量可实现10MPa-300M Pa,硬度可实现10mMPa-300M pa,适用于于光固化涂料、胶黏剂,电子束固化涂料、胶黏剂等。(The invention discloses a reactable hollow microsphere with controllable mechanical property and a preparation method thereof, belonging to the technical field of hollow microsphere preparation. The invention combines the Pickering emulsion template method and the UV light curing technology into a whole, the grain diameter and the wall thickness of the hollow microsphere are realized by changing the oil phase composition ratio and the emulsifying rotating speed, the reaction group carried on the surface of the hollow microsphere can be obtained by an oil phase photosensitive reactant, and the mechanical property of the hollow microsphere is realized by the blending of a resin system or the regulation and control of the wall thickness. The hollow microsphere has the particle size of 5-50 mu M, has reactive epoxy groups and photosensitive double bond groups on the surface, can reduce the modulus to 10MPa-300Mpa, has the hardness to 10mMPa-300 Mpa, and is suitable for photocureable coatings, adhesives, electron beam curing coatings, adhesives and the like.)

1. A preparation method of a reactable hollow microsphere with controllable mechanical property is characterized by comprising the following steps:

s1, preparing a water phase: the water phase is an aqueous solution containing a co-stabilizer;

s2, preparing an oil phase: the oil phase is a liquid phase containing a photocuring material, stable particles and an oil-soluble solvent, the photocuring material comprises a photocuring resin, a photocuring reactive diluent and a photoinitiator, and the stable particles are functional silica particles;

s3, mixing the water phase with the oil phase, and forming water-in-oil O/W droplets through high-speed dispersion and emulsification;

s4, the O/W liquid drop is pre-cured and/or cured through a light curing device, and the reactive substance for light curing in the oil phase is cured to form the hollow microsphere.

2. The method according to claim 1, wherein the co-stabilizer comprises one or more of alkylphenol ethoxylates, fatty alcohol polyoxyethylene ethers, fatty amine polyoxyethylene ethers, nonionic aids using glycerin as a basic raw material, and polymeric aids.

3. The method according to claim 1, wherein the light-curable resin comprises any one or a combination of two or more of acrylate, acrylic acid derivative, methacrylate and methacrylate derivative, preferably the light-curable resin comprises any one or a combination of two or more of epoxy (meth) acrylate, polyester (meth) acrylate, polyether (meth) acrylate, amino acrylate, urethane (meth) acrylate and photosensitive acrylate resin;

the photo-curing reactive diluent comprises an acrylate compound which contains 1 or more than 1 acrylate group in the structure, has the average molecular weight of less than 3000 and the viscosity of less than 9000 cp;

the photoinitiator comprises a substance capable of initiating the polymerization of acrylate substances under the irradiation of ultraviolet light or visible light;

the functional silica particles comprise any one or the combination of more than two of acrylic double-bond silica, amino silica, mercapto silica and epoxy modified silica;

the oil-soluble solvent comprises any one or the combination of more than two of alkanes, ketones and esters.

4. The method as claimed in claim 1, wherein the photo-curable material comprises, by mass, 10 to 80 parts of a photo-curable resin, 20 to 80 parts of a photo-curable reactive diluent, and 0.1 to 10 parts of a photoinitiator.

5. The method of claim 1, wherein the light curable material further comprises a thermoplastic resin comprising a combination of any one or more of an acrylic resin, a polyester resin, and an epoxy resin.

6. The method according to claim 1, wherein in the O/W emulsion, the volume ratio of the water phase to the oil phase is 1:1 or 1:2 or 1:3 or 1:4 or 1:5 or 1:10 or 2:1 or 3:1 or 4:1 or 5:1 or 9:1 or 10: 1;

the high-speed dispersion is carried out by adopting a high-speed dispersion machine, and the rotating speed of the high-speed dispersion machine is any one of 5Krpm-10Krpm, 5Krpm-15Krpm, 10Krpm-15Krpm, 15Krpm-20Krpm and 15Krpm-20 Krpm;

the high-speed dispersion time is 3-10 min.

7. Hollow microspheres produced according to any one of claims 1 to 6, wherein the hollow microspheres comprise a shell structure and a cavity comprising a coating surrounded by the shell structure, wherein the shell structure is derived from the oil phase and the coating in the cavity is derived from the water phase.

8. The hollow microsphere of claim 7, wherein the average particle size of the hollow microsphere is any one of: 5-10 μm, 5-20 μm, 10-30 μm, 20-40 μm, 20-50 μm;

the average diameter of the hollow structure of the hollow microspheres is at most 93% of the average particle diameter of the hollow microspheres.

9. The hollow microsphere of claim 7, wherein the shrinkage modulus of the hollow microsphere is from 10MPa to 173MPa, the hardness of the hollow microsphere is from 10MPa to 300 MPa;

the surface of the hollow microsphere is provided with a reactive group, and the reactive group comprises any one or more of a photosensitive double bond, an epoxy group, a hydroxyl group, a carboxyl group, a sulfydryl group and an alkynyl group.

10. Use of hollow microspheres according to any one of claims 7-9 in the field of coatings, inks and adhesives.

Technical Field

The invention belongs to the technical field of hollow microsphere preparation, and particularly relates to a hollow microsphere with controllable mechanical property and a preparation method thereof.

Background

The hollow microsphere consists of a shell material and an internal cavity, wherein the internal cavity is a hollow cavity, and the mechanical property of the external shell material can be adjusted. The hollow microspheres have wide application fields, such as biomedicine, coating, building materials and other fields which are closely related to life.

The basic reason of the shrinkage problem of the material in the curing and forming process is that van der Waals force among molecules participating in curing reaction is converted into covalent bond effect, the distance among the molecules is reduced, and the problems of size shrinkage, deflection and deformation, even stress cracking and the like are presented macroscopically, so that the service life of the material is influenced, and even the safety of lives and properties is damaged. At present, reducing the shrinkage rate of thermosetting and photocuring coating materials becomes an important problem to be solved urgently in the field of coating industry. In recent years, researchers have addressed this problem by adding inorganic fillers, intumescent monomers, and improved curing processes to the resin formulation. However, these methods have obvious problems that the inorganic filler is added in a large amount and does not participate in the curing reaction of the coating, which reduces the use performance of the coating; the preparation method of the expansion monomer is expensive, the economic applicability is poor, and the popularization and the application in the industrial field are difficult; however, the shrinkage rate cannot be reduced fundamentally though the curing process is improved and the like.

Therefore, it is necessary to develop a new technology to solve the problem of curing shrinkage of the coating.

Disclosure of Invention

In order to solve the problem of curing shrinkage, the invention provides the reactive hollow microsphere with controllable mechanical property and the preparation method thereof. The prepared hollow microspheres can realize the adjustment of the mechanical property of the wall material of the hollow microspheres from elastic deformation to plastic deformation.

A first object of the present invention is to provide a method for preparing a reactive hollow microsphere having controllable elastic properties, the method comprising the steps of:

s1, preparing a water phase: the water phase is an aqueous solution containing a co-stabilizer;

s2, preparing an oil phase: the oil phase is a liquid phase containing a photocuring material, stable particles and an oil-soluble solvent, the photocuring material comprises a photocuring resin, a photocuring reactive diluent and a photoinitiator, and the stable particles are functional silica particles;

s3, mixing the water phase with the oil phase, and forming water-in-oil O/W droplets through high-speed dispersion and emulsification;

s4, the O/W liquid drop is pre-cured and/or cured through a light curing device, and the reactive substance for light curing in the oil phase is cured to form the hollow microsphere.

In one embodiment, the co-stabilizer includes, but is not limited to, any one or a combination of two or more of alkylphenol ethoxylates, fatty alcohol ethoxylates, fatty amine ethoxylates, nonionic aids using glycerin as a basic raw material, and polymeric aids.

In one embodiment, the co-stabilizer in the aqueous phase may be an alkylphenol polyoxyethylene ether: nonylphenol polyoxyethylene ether, octylphenol polyoxyethylene ether, bis, tributylphenol polyoxyethylene ether, alkylphenol polyoxyethylene ether, phenethylphenol polyoxypropylene polyoxyethylene ether, benzylphenol polyoxyethylene ether, bis, tribenzylphenol polyoxyethylene ether, benzyldimethylphenol polyoxyethylene ether, dibenzylcumylphenol (also called dibenzylphenol) polyoxyethylene ether, benzyldiphenol polyoxypropylene polyoxyethylene ether, phenethylphenol polyoxyethylene ether, phenethylcumylphenol polyoxyethylene ether, phenethyl diphenol polyoxyethylene ether, phenethyl cumylphenol polyoxyethylene ether, phenethyl diphenol polyoxyethylene ether, phenethyl naphthol polyoxyethylene ether, and phenethylnaphthol polyoxyethylene ether.

In one embodiment, the co-stabilizer in the aqueous phase may be fatty alcohol polyoxyethylene ether and its similar products, lauryl alcohol polyoxyethylene ether) isooctyl polyoxyethylene ether, stearyl alcohol polyoxyethylene ether isotridecyl alcohol polyoxyethylene ether, fatty alcohol polyoxyethylene ether, phenethyl phenol polyoxyethylene ether, phenethyl phenyl phenol polyoxyethylene ether, phenethyl biphenol polyoxyethylene ether, and the like.

In one embodiment, the co-stabilizer in the aqueous phase may be a fatty amine polyoxyethylene ether, a fatty amine (also called alkylamine) polyoxyethylene ether, a fatty amide polyoxyethylene ether, an alkylamine oxide, a quaternary amine alkoxide, and the like.

In one embodiment, the co-stabilizer in the aqueous phase may be a nonionic auxiliary agent with glycerin as a basic raw material, diglycerin and fatty acid ester, diglycerin polypropylene glycol ether, glycerol polyoxyethylene ether polyoxypropylene ether fatty acid ester.

In one embodiment, the co-stabilizer in the aqueous phase may be a polymer-type assistant, such as alkylphenol ethoxylate-formaldehyde condensate, aralkyl phenol ethoxylate-formaldehyde condensate, phenethylphenol ethoxylate-formaldehyde condensate, cumyl phenol ethoxylate-formaldehyde condensate, benzyl phenol ethoxylate-formaldehyde condensate, biphenol ethoxylate-formaldehyde condensate, polyvinyl alcohol with 98-99% of complete hydrolysis and with a degree of hydrolysis of 88-89% of partial hydrolysis, polyoxyethylene polyoxypropylene block copolymer, ethylene oxide-butylene oxide copolymer, ethylene oxide-propylene oxide-butylene oxide copolymer, polymeric carboxylate: polyacrylic acid, sodium polyacrylate, polyacrylamide, alkylphenol polyoxyethylene ether formaldehyde condensate sulfate, alkyl naphthalene sulfonic acid formaldehyde condensate and the like, phenolsulfonic acid naphthalene sulfonic acid formaldehyde condensate sodium salt, phenolformaldehyde condensate sulfonic acid sodium salt, phenol-urea-formaldehyde condensate sulfonate, methyl cellulose and derivatives thereof, xanthan gum, sodium desugared lignin sulfonate and the like.

In one embodiment, the stabilizing particles, also referred to as Pickering stabilizers, may be any one or a combination of two or more of acrylic double bond silica, amino silica, mercapto silica, and epoxy modified silica.

In one embodiment, the light curable resin includes, but is not limited to, any one or a combination of two or more of acrylate, acrylic acid derivative, methacrylate, and methacrylate derivative, and preferably, the light curable resin includes any one or a combination of two or more of epoxy (meth) acrylate, polyester (meth) acrylate, polyether (meth) acrylate, amino acrylate, urethane (meth) acrylate, and photosensitive acrylate resin.

In one embodiment, the photocurable resin is a (meth) acrylate. The (meth) acrylates are intended to mean the corresponding acrylates, i.e. derivatives of acrylic acid, and methacrylates, i.e. derivatives of methacrylic acid.

In one embodiment, the photocurable resin includes, but is not limited to, any one or a combination of two or more of epoxy (meth) acrylate, polyester (meth) acrylate, polyether (meth) acrylate, amino acrylate, urethane (meth) acrylate, and photosensitive acrylate resin.

In one embodiment, the epoxy acrylate includes, but is not limited to, bisphenol a type epoxy acrylate, hydrogenated bisphenol a type epoxy acrylate, bisphenol F type epoxy acrylate, hydrogenated bisphenol F type epoxy acrylate, novolac epoxy acrylate, epoxidized oil acrylate, and modified epoxy acrylates that retain the photocuring function resulting from modification of these resins. The modified epoxy acrylate includes, but is not limited to, alcohol-modified epoxy acrylate, acid-or anhydride-modified epoxy acrylate, urethane-modified epoxy acrylate, silicone-modified epoxy acrylate, fluorine-containing monomer-modified epoxy acrylate, and the like.

In one embodiment, the epoxy acrylate is specifically bisphenol a type epoxy acrylate, bisphenol F type epoxy acrylate, fatty acid modified epoxy acrylate, or the like.

In one embodiment, the polyester (meth) acrylates include, but are not limited to, polyester acrylates containing different polyacids and different polyols and polyester (meth) acrylates resulting from modification of these resins. The modified polyester acrylate comprises polyurethane modified polyester acrylate, polyether modified polyester acrylate, organic silicon modified polyester acrylate, fluorine-containing monomer modified polyester acrylate and the like.

In one embodiment, the polyester acrylate is specifically silicone modified polyester acrylate, polyurethane modified polyester acrylate, polyether modified polyester acrylate, or the like.

In one embodiment, the polyether acrylates include, but are not limited to, polyether acrylates of varying chain lengths made from ethylene glycol, propylene glycol, tetrahydrofuran, and polyether acrylates resulting from modification of these resins. The modified polyether acrylate comprises polyurethane modified polyether acrylate, organic silicon modified polyether acrylate, fluorine-containing monomer modified polyether acrylate and the like. Specifically, the acrylate may be silicone-modified polyether acrylate, urethane-modified polyether acrylate, or the like.

In one embodiment, the amino acrylate includes, but is not limited to, urea formaldehyde acrylate, melamine formaldehyde acrylate, benzoguanamine formaldehyde acrylate, and amino acrylates modified from these resins.

In one embodiment, the urethane acrylate includes, but is not limited to, aliphatic urethane acrylates, alicyclic urethane acrylates, aromatic urethane acrylates, and urethane acrylates modified from these resins. The modified urethane acrylate comprises organosilicon modified urethane acrylate, polyether modified urethane acrylate, fluorine-containing monomer modified urethane acrylate and the like.

In one embodiment, the photosensitive acrylate resin includes, but is not limited to, glycidyl (meth) acrylate modified acrylate resins, maleic anhydride modified acrylate resins, and the like.

In one embodiment, the acrylic resin includes a polymer obtained by copolymerizing any one or more of (meth) acrylic acid, styrene, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, ethylhexyl acrylate, isobornyl (meth) acrylate, glycidyl (meth) acrylate, a fluorine-containing acrylate monomer, and a silicon-containing acrylate monomer.

In one embodiment, the polyesters include, but are not limited to, polyesters containing different polyacids and different polyols and polyester resins resulting from modification of these resins. The modified polyester resin comprises polyurethane modified epoxy resin, polyether modified polyester resin, organic silicon modified polyester resin, fluorine-containing monomer modified polyester resin and the like.

In one embodiment, the epoxy resin includes, but is not limited to, bisphenol a type epoxy resins, novolac epoxy resins, and modified epoxy resins thereof. The modified epoxy resin includes, but is not limited to, alcohol-modified epoxy resin, acid-or acid anhydride-modified epoxy resin, polyurethane-modified epoxy resin, silicone-modified epoxy resin, fluorine-containing monomer-modified epoxy resin, and the like.

In one embodiment, the photocurable reactive diluent includes, but is not limited to, a class of acrylate compounds having 1 or more acrylate groups in the structure, an average molecular weight of less than 3000, and a viscosity of less than 9000 cp.

In one embodiment, the photocurable reactive diluent may be: beta-hydroxyethyl (meth) acrylate, isobornyl (meth) acrylate, tetrahydrofuran acrylate, 2-phenoxyethyl acrylate, 1, 6-hexanediol di (meth) acrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, glycidyl methacrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, ethoxylated trimethylolpropane tri (meth) acrylate, propoxylated trimethylolpropane tri (meth) acrylate, caprolactone-modified trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, ethoxylated pentaerythritol tetra (meth) acrylate, isobornyl (meth) acrylate, poly (2-phenoxyethyl) acrylate, poly (1, 6-hexanediol di (meth) acrylate, poly (propylene glycol di (meth) acrylate, poly (meth) acrylate, poly (meth) acrylate, Propoxylated pentaerythritol tetra (meth) acrylate, caprolactone-modified pentaerythritol tetra (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, caprolactone-modified ditrimethylolpropane tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, ethoxylated dipentaerythritol penta (meth) acrylate, propoxylated dipentaerythritol penta (meth) acrylate, caprolactone-modified dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, ethoxylated dipentaerythritol hexa (meth) acrylate, propoxylated dipentaerythritol hexa (meth) acrylate, caprolactone-modified dipentaerythritol hexa (meth) acrylate, bisphenol A di (meth) acrylate, bisphenol F di (meth) acrylate, ethoxylated bisphenol A di (meth) acrylate, and mixtures thereof, Ethoxylated bisphenol F di (meth) acrylate, propoxylated bisphenol a di (meth) acrylate, propoxylated bisphenol F di (meth) acrylate, caprolactone-modified bisphenol a di (meth) acrylate, caprolactone-modified bisphenol F di (meth) acrylate, ethoxylated hydrogenated bisphenol a di (meth) acrylate, ethoxylated hydrogenated bisphenol F di (meth) acrylate, propoxylated hydrogenated bisphenol a di (meth) acrylate, propoxylated hydrogenated bisphenol F di (meth) acrylate, caprolactone-modified hydrogenated bisphenol a di (meth) acrylate, caprolactone-modified hydrogenated bisphenol F di (meth) acrylate, and the like.

In one embodiment, the photoinitiator includes, but is not limited to, a class of materials that initiate polymerization of acrylate species upon exposure to ultraviolet or visible light.

In one embodiment, the photoinitiator includes, but is not limited to, 2-hydroxy-methylphenylpropane-1-one, 1-hydroxycyclohexyl phenyl ketone, benzoin ethyl ether, benzoin propyl ether, 2-methyl-1- (4-methylthiophenyl) -2-morpholinyl-1-propanone, benzoin dimethyl ether, camphorquinone, 1-phenyl-1, 2-propanedione, 2,4, 6-trimethylbenzoyl diphenylphosphine, bis (2, 6-dimethoxybenzoyl) -2,4, 4-trimethylphenylphosphine oxide, isopropylthioxanthone, bis (1- (2, 4-difluorophenyl) -3-pyrrolyl) titanocene, and 2-benzyl-2-methylamino-1- (4-morpholinophenyl) -1-butanone, and the like .

In one embodiment, the photocurable material further comprises a thermoplastic resin.

In one embodiment, the thermoplastic resin includes, but is not limited to, any one or a combination of two or more of acrylic resin, polyester resin, and epoxy resin.

In one embodiment, the photocurable resin in the photocurable material is bisphenol a type epoxy acrylate, epoxidized soybean oil acrylate, photocurable reactive diluent trimethylolpropane triacrylate and tetrahydrofuran acrylate, and the photoinitiator is 2-hydroxy-2-methyl-1-phenyl-1-acetone.

In the invention, the photo-curing material releases free radicals under the irradiation condition of ultraviolet light or visible light by the photoinitiator, so as to initiate the cross-linking reaction between double bonds of acrylic ester between the photo-curing resin and the reactive diluent, and the thermoplastic resin is an inert component.

In one embodiment, the oily solvent includes any one or a combination of two or more of alkanes, ketones, and esters, wherein alkane solvents such as n-heptane, iso-heptane, and the like, ketone solvents such as acetone, n-butyl ketone, and the like, and ester solvents such as γ -butyrolactone, ethyl acetate, butyl acetate, and the like.

In one embodiment, the components in the oil phase comprise 10 to 80 parts of oil-soluble solvent, generally 10 to 80 parts of light-curable resin, generally 20 to 80 parts of light-curable reactive diluent, and generally 0.1 to 10 parts of photoinitiator.

In one embodiment, the photocurable material contains, by mass, usually 10 to 80 parts of a photocurable resin; the photo-curing reactive diluent is usually 20-80 parts; the photoinitiator is usually 0.1 to 10 parts. The addition amount of the light-cured resin and the mechanical property of the obtained hollow microsphere are in an inverse correlation relationship, namely, the mechanical property of the obtained hollow microsphere, including the shrinkage modulus and the hardness, are reduced along with the increase of the addition amount of the light-cured resin. Therefore, the controllability of the mechanical property of the hollow microsphere can be realized by controlling the addition amount of the light-cured resin.

In one embodiment, the photo-curing material comprises, by mass, 20-50 parts of a photo-curing resin, 20-60 parts of a photo-curing reactive diluent, and 2-5 parts of a photoinitiator.

In one embodiment, the photocurable material comprises, by mass, usually 20 to 30 parts of a photocurable resin, usually 20 to 30 parts of a photocurable reactive diluent, and usually 2 to 4 parts of a photoinitiator.

In one embodiment, the viscosity of the oil phase (mesophase) ranges from 1 to 9000 cp; wherein, optionally, the viscosity ranges from 20-1000 cp.

In one embodiment, the aqueous phase further comprises a surfactant, wherein the surfactant comprises anionic surfactants such as sodium dodecyl sulfate and the like, cationic surfactants, and nonionic surfactants, polymeric surfactants and the like.

In one embodiment, the O/W emulsion is prepared such that the water-oil ratio, i.e., the volume ratio of the water phase to the oil phase, is any one of 1:1, 1:2, 1:3, 1:4, 1:5, 1:10, 2:1, 3:1, 4:1, 5:1, 9:1, and 10: 1.

In one embodiment, the volume ratio of water to oil, i.e. the water phase to the oil phase, in the preparation of the O/W emulsion is 9:1 or 10: 1.

In one embodiment, the oil phase has a tension in the range of 1mN/m to 60 mN/m; wherein, optionally, the tension is in the range of 15mN/m to 45 mN/m.

In one embodiment, the high-speed disperser has any one of a speed of 5Krpm-10Krpm, 5Krpm-15Krpm, 10Krpm-15Krpm, 15Krpm-20Krpm, and 15Krpm-20 Krpm.

In one embodiment, the high speed dispersion time is 3-10 min.

In one embodiment, the light emitted from the light curing device includes a wavelength band within the range of 256-500 nm.

In one embodiment, the light curing device emits ultraviolet or visible light with a wavelength in the range of 256-500 nm.

In one embodiment, the energy density of the irradiation of the light curing device is 10 to 200mj/cm²。

In one embodiment, the method for preparing reactive hollow microspheres with controllable mechanical properties further comprises centrifuging the fully solidified hollow microspheres multiple times by direct ethanol washing to remove residues.

In one embodiment, the aqueous phase is an aqueous solution containing a surfactant.

In one embodiment, the aqueous phase is an aqueous solution containing 1% to 2% (m/v) polyvinyl alcohol (PVA).

The second purpose of the present invention is to provide a reactive hollow microsphere with controllable mechanical properties, which is prepared by the method described in any of the above embodiments.

In one embodiment, the hollow microsphere comprises a shell structure and a cavity containing a coating, wherein the cavity is formed by surrounding the shell structure, the shell structure is obtained by reacting an oil phase, particularly a light-cured material, and the coating in the cavity is obtained by the water phase and can be water or an aqueous solution.

In one embodiment, the average particle size of the microcapsules may be 5 to 50 μm.

In one embodiment, the average particle size of the microcapsules may be 5 to 10 μm, 5 to 20 μm, 10 to 30 μm, 20 to 40 μm, 20 to 50 μm.

In one embodiment, the hollow structures of the hollow microspheres have an average diameter of at most 93% of the average particle diameter of the hollow microspheres.

In one embodiment, the average diameter of the hollow structure of the hollow microspheres is 70% to 93% of the average particle diameter of the hollow microspheres.

In one embodiment, the mechanical properties of the hollow microspheres include reduced modulus and hardness.

In one implementation, the mechanical properties of the hollow microspheres are inversely related to the addition amount of the polyurethane acrylic resin.

In one embodiment, the hollow microspheres may have a modulus of shrinkage reduction of from 10MPa to 300M Pa.

In one embodiment, the reduced modulus of the hollow microspheres may be 20MPa to 173M Pa.

In one implementation, the hollow microspheres may have a hardness of 10mMPa to 300 Mpa.

In one embodiment, the hollow microspheres may have a hardness of 10MPa to 190 MPa.

In one embodiment, the hollow microspheres have reactive groups on their surface.

In one embodiment, the reactive groups on the surface of the hollow microsphere comprise photosensitive double bonds, epoxy groups, hydroxyl groups, carboxyl groups, sulfydryl groups and alkynyl groups. The reactive groups are grafted on, and experiments show that the groups can be matched with a resin system, so that the surfaces of the hollow microspheres form reactive groups capable of participating in photocuring and can participate in curing and crosslinking of other systems.

The third purpose of the present invention is to provide an application of the reactive hollow microsphere with controllable mechanical properties, which is applied to the fields of paint, ink, adhesive, etc.

Has the advantages that: compared with the prior art, the preparation method integrates a Pickering emulsion template method and a UV photocuring technology to realize the preparation of the reactive hollow microsphere with controllable mechanical property, the particle size and the wall thickness of the hollow microsphere are realized by the rotating speed of a high-speed dispersion machine and the volume ratio of oil phase components, and the mechanical property is realized by the blending of a resin system or the regulation and control of the wall thickness. The method of the invention has the following advantages:

1. the preparation method is simple, the mass preparation of the hollow microspheres can be realized in a short time, and the average grain diameter is 5-30 mu m;

2. the mechanical properties of the hollow microspheres are controllable, and comprise a shrinkage reduction modulus and hardness, wherein the shrinkage reduction modulus can be 10MPa-300M Pa, and the hardness can be 10mMPa-300M Pa; and the shrinkage force of the microspheres is reduced through controllability of mechanical properties.

3. The surface of the hollow microsphere is provided with a reactive group which can participate in the curing and crosslinking of other systems.

Drawings

FIG. 1 is a schematic diagram of an electron microscope of a hollow microsphere with a smooth surface prepared in example 3 of the present invention;

FIG. 2 is a schematic diagram of an electron microscope showing hollow microspheres embedded with silica particles prepared in example 3 of the present invention.

Detailed Description

The preparation method comprises the following steps: the water phase solution, the multi-component oil phase and the stable particles are dispersed and emulsified at a high speed to form water-in-oil O/W droplets; the emulsified O/W liquid drops are irradiated by a photocuring device for curing or precuring, and the interface of the reactable substance in the oil phase is cured to form hollow microspheres; the oil phase is a liquid phase containing a photo-curable material. The method specifically comprises the following steps:

(1) preparation of an aqueous phase system: the water phase is an aqueous solution containing a co-stabilizer; in some embodiments, a surfactant may also be added to the aqueous phase.

(2) Preparing an oil phase: according to the requirements of fluid viscosity and mechanical property of the cured hollow microsphere in the preparation process of the hollow microsphere, selecting photosensitive resin (namely photocuring resin), photosensitive monomer (namely photocuring reactive diluent), photoinitiator, stable particles and oil-soluble solvent; so that the oil phase satisfies: the viscosity range of the oil phase (intermediate phase) is 1-9000cp, optionally, the viscosity range is 20-1000cp, and the oil phase needs certain fluidity, so the viscosity is not suitable to be too high; the tension of the oil phase is in the range of 1mN/m to 60mN/m, alternatively in the range of 15mN/m to 45mN/m, in order to meet the requirements of fluid viscosity and mechanical properties of the cured hollow microspheres.

(3) And (4) dripping the emulsified O/W emulsion into the solution to perform interface curing by direct UV illumination.

The present invention will be further illustrated and described in detail with reference to the following examples. The present invention will be better understood from the following examples. However, those skilled in the art will readily appreciate that the specific material ratios, process conditions and results thereof described in the examples are illustrative only and should not be taken as limiting the invention as detailed in the claims.

Example 1: influence of different emulsification rotation speeds on hollow microsphere diameter

The present example demonstrates the effect of different emulsification rotation rates on the diameter of reactive hollow microspheres with controllable mechanical properties.

The raw materials are as follows: in the water phase, the co-stabilizer is polyvinyl alcohol; in the oil phase, the solvent is butyrolactone (namely gamma-butyrolactone), the photocuring resin is polyester acrylate, the photocuring active diluent is glycidyl methacrylate, the photoinitiator is 2-hydroxy-2-methyl-1-phenyl-1-acetone, and the stable particles are acrylic double-bond silicon dioxide.

The preparation process comprises the following steps:

1. preparation of an aqueous phase system: the water phase is polyvinyl alcohol water solution with the concentration of 1 wt%.

2. Preparing an oil phase system (mass ratio): specifically, butyrolactone: glycidyl methacrylate: polyester acrylate: 2-hydroxy-2-methyl-1-phenyl-1-propanone according to 55: 21: 21: 3, and acrylic double bond silica stable particles accounting for 1 percent of the total mass fraction are uniformly mixed.

3. Preparation of Pickering emulsion: transferring 1mL of oil phase, dripping into 10mL of water phase sample bottle, emulsifying for 5min at high speed of 5Krpm, 10Krpm, 15Krpm and 20Krpm of high speed dispersion machine to form O/W emulsion drop, continuously irradiating the sample bottle for 3min with ultraviolet curing high-pressure mercury lamp to obtain interface photocuring hollow microsphere with energy density of 20mJ/cm²。

4. Separating and purifying, and directly centrifuging and washing with ethanol for three times to obtain the hollow microspheres.

The results of the particle size measurement of the resulting hollow microspheres are shown in table 1 below.

TABLE 1 influence of different emulsification rotation speeds on the diameter of hollow microspheres

High speed disperser rotational speed (Krpm)	Particle size (. mu.m)
		5	34.8±4.9
10	17.2±2.8
		15	15.9±3.0
20	13.1±2.1

From the results of table 1, it can be seen that when the high speed disperser rotation speed is varied between 5Krpm, 10Krpm, 15Krpm, 20Krpm, the prepared hollow microspheres have particle size ranging between 10-50 μm, and the particle size is negatively correlated with the high speed disperser rotation speed, since the larger the rotation speed, the more the generated shear force is, the easier the particles are sheared into small-sized droplets, and thus the smaller the particle size obtained after solidification is.

Example 2: influence of different oil phase component ratios on mechanical properties of hollow microspheres

This example demonstrates the effect of different oil phase component ratios on the mechanical properties of hollow microspheres.

The raw materials are as follows: in the water phase, the co-stabilizer is polyvinyl alcohol; in the oil phase, the solvent is butyrolactone, the photocuring resin is polyurethane acrylate RY2201, the photocuring active diluent is glycidyl methacrylate, the photoinitiator is 2-hydroxy-2-methyl-1-phenyl-1-acetone, and the stable particles are acrylic double-bond silicon dioxide.

The preparation process comprises the following steps:

1. preparation of an aqueous phase system: the water phase is polyvinyl alcohol water solution with the concentration of 1 percent.

2. Preparation of oil phase (mass ratio): carrying out ultrasonic dispersion and uniform mixing on butyrolactone, polyurethane acrylate RY2201, glycidyl methacrylate and 1 part of 2-hydroxy-2-methyl-1-phenyl-1-acetone, wherein different parts of butyrolactone are added, the ratio of the polyurethane acrylate RY2201 to the glycidyl methacrylate is 1:1, and acrylic double bond silicon dioxide with the total mass fraction of 1% is added to obtain oil phases with different components;

3. transferring 1mL oil phase, dripping into 10mL water phase sample bottle, dispersing for 5min with high speed disperser 10Krpm to form O/W emulsion droplet, continuously irradiating the sample bottle with ultraviolet light-cured high pressure mercury lamp for 3min to obtain hollow microsphere with energy density of 20mJ/cm²。

4. Separating and purifying, and directly centrifuging and washing with ethanol for three times to obtain the hollow microspheres.

The results of the particle size measurement of the resulting hollow microspheres are shown in table 2 below.

TABLE 2 Effect of different oil phase Components on wall thickness of hollow microspheres

Butyrolactone (wt%)	Average particle size (. mu.m)	Wall material thickness (mum)	Wall thickness ratio (%)
				25	20.4	＞5	＞24.5
55	16.9	2-3	11-18
				75	14.7	＜1	＜7

As can be seen from Table 2, as the content of butyrolactone in the solvent increases, the average particle size of the hollow microspheres gradually decreases, and the wall thickness gradually decreases, and accordingly, the wall thickness ratio (the ratio of the wall thickness to the average particle size) gradually decreases from higher than 25.4% to less than 7%, which means that the cavity size gradually increases to 93%. Therefore, the control of the size of the cavity, namely the wall thickness of the controlled microsphere can be realized by regulating the solvent amount, and the wall thickness is an important characteristic of the elastic property of the hollow microsphere. The embodiment shows that the microspheres with different wall thicknesses under the condition of similar particle sizes can be obtained by adjusting the proportion of the solvent under the conditions of the same water phase and oil phase raw materials and the same preparation process, so that the controllable adjustment of the elasticity of the hollow microspheres is realized.

Example 3: effect of Stable particle Dispersion on hollow microsphere morphology

This example demonstrates the effect of stable particle dispersion on the morphology of hollow microspheres.

The raw materials are as follows: in the water phase, the co-stabilizer is 1% of F108; in the oil phase, the solvent is butyrolactone, the light-cured resin is polyurethane acrylate RY2201, the light-cured active diluent is tripropylene glycol diacrylate, the photoinitiator is 2-hydroxy-2-methyl-1-phenyl-1-acetone, and the stable particles are acrylic double-bond silicon dioxide.

The raw materials are the same as in example 1, and the specific preparation process is as follows:

1. preparation of an aqueous phase system: the water phase I is an aqueous solution containing 1% of F108 co-stabilizer, and the water phase II is an aqueous solution containing 1% of F108 co-stabilizer and different percentages of acrylic double bond silica particle stabilizing particles.

2. Preparing an oil phase system (mass ratio):

oil phase one: butyrolactone: polyurethane acrylate RY 2203: tripropylene glycol diacrylate: 2-hydroxy-2-methyl-1-phenyl-1-propanone according to 55: 22: 22: 1, uniformly mixing;

and (2) oil phase II: butyrolactone: polyurethane acrylate RY 2203: tripropylene glycol diacrylate: 2-hydroxy-2-methyl-1-phenyl-1-propanone according to 55: 22: 22: 1, adding the acrylic double bond silica stable particles with different mass fractions, and dispersing uniformly.

3. Preparation of hollow microspheres

(1) Water phase one + oil phase one: the water phase and the oil phase are both free of stable particles

Respectively transferring 1mL of oil phase IAdding into 9mL water phase containing stable particles with different mass percentages, emulsifying for 5min with high speed disperser 10Krpm to form O/W emulsion drop, continuously irradiating sample bottle with ultraviolet light-cured high pressure mercury lamp for 3min to obtain hollow microsphere with energy density of 20mJ/cm²；

(2) Water phase I + oil phase II: the water phase has no stable particles, and the oil phase has stable particles

Respectively transferring 1mL of the oil phase II into 9mL of the water phase I containing stable particles with different mass percentages, emulsifying for 5min by using a high-speed dispersion machine with 10Krpm to form O/W emulsion droplets, continuously irradiating a sample bottle for 3min by using an ultraviolet curing high-pressure mercury lamp to obtain hollow microspheres with the energy density of 20mJ/cm²；

(3) Water phase two + oil phase one: the water phase has stable particles, and the oil phase has no stable particles

Respectively transferring 1mL of the first oil phase into 9mL of the second water phase containing stable particles with different mass percentages, emulsifying for 5min by using a high-speed dispersion machine with 10Krpm to form O/W emulsion droplets, continuously irradiating a sample bottle for 3min by using an ultraviolet curing high-pressure mercury lamp to obtain hollow microspheres with the energy density of 20mJ/cm²；

(4) Water phase two + oil phase two: the water phase and the oil phase both have stable particles

Respectively transferring 1mL of oil phase II containing different acrylic acid double bond silicon dioxide into 9mL of water phase II, emulsifying for 5min with high speed disperser 10Krpm to form O/W emulsion droplet, continuously irradiating sample bottle with ultraviolet light curing high pressure mercury lamp for 3min to obtain hollow microsphere with energy density of 20mJ/cm²。

4. Washing and centrifuging for three times by using ethanol, and purifying to obtain the hollow microspheres with different shapes.

The results of the morphology test of the obtained hollow microspheres are shown in table 3 below.

TABLE 3 Effect of Stable particle Dispersion on hollow microsphere morphology

Sample name	Particle size (. mu.m)	Morphology of
			Water phase one + oil phase one	15.8	The microsphere has smooth surface
Water phase I and oil phase II	14.3	The surface of the microsphere is embedded with silicon dioxide colloidal particles
			Water phase two + oil phase one	16.1	The microsphere has smooth surface
Water phase two + oil phase two	14.9	The surface of the microsphere is embedded with silicon dioxide colloidal particles

As can be seen from the results in table 3, the hollow microspheres were obtained by photopolymerization regardless of whether the silica particles were placed in the aqueous phase or the oil phase, but the morphology was greatly different.

When no silica was present in the oil phase, as in tests (1) and (3), the surface of the microspheres was smooth, either when the silica particles were placed in the aqueous phase or when no silica particles were present in the aqueous phase, as shown in FIG. 1, indicating that the surface was not embedded with silica;

when the silica was placed in the oil phase, as in tests (2) and (4), the microspheres were embedded with silica on their surface, regardless of whether the aqueous phase contained silica particles, as shown in FIG. 2.

The results of this example show that silica particles are placed in the oil phase to obtain microspheres with silica embedded in their surface. The silica may be modified with reactive groups such as epoxy, double bonds, etc., so that the microspheres are also reactive.

Example 4: preparation of hollow microsphere with controllable mechanical property

The embodiment tests the influence of the type and the dosage of the light-cured resin on the appearance of the hollow microspheres.

The raw materials are as follows: in the water phase, the co-stabilizer is polyvinyl alcohol, and the anion is sodium dodecyl sulfate; in the oil phase, the solvent is butyrolactone, the light-cured resin is polyurethane acrylate, the light-cured active diluent is glycidyl methacrylate, the photoinitiator is 2-hydroxy-2-methyl-1-phenyl-1-acetone, and the stable particles are acrylic double-bond silicon dioxide.

The preparation process comprises the following steps:

1. preparation of an aqueous phase system: the water phase comprises 1 wt% of polyvinyl alcohol aqueous solution and 1 wt% of sodium dodecyl sulfate.

2. Preparing an oil phase system (mass ratio): 55 parts of butyrolactone, 22 parts of glycidyl methacrylate, 10, 22 and 40 parts of urethane acrylate, 1 part of 2-hydroxy-2-methyl-1-phenyl-1-acetone and 1 percent of acrylic double bond silicon dioxide stable particles are mixed uniformly.

3. Respectively transferring 1mL of oil phase containing polyurethane acrylate with different contents, dripping into a water phase sample bottle, emulsifying for 3min with a high-speed disperser 10Krpm to form O/W emulsion droplets, irradiating the emulsion with an ultraviolet light-cured high-pressure mercury lamp to obtain hollow microspheres with an energy density of 20mJ/cm²。

5. Separating and purifying, washing with ethanol, centrifuging for three times, and filtering to obtain hollow microspheres.

The morphology and mechanical properties of the hollow microspheres were measured as shown in table 4 below.

TABLE 4 influence of polyurethane resin on mechanical Properties of microspheres

From the results in table 4, it can be seen that by changing the weight parts of the urethane acrylate, the surfaces of the obtained hollow microspheres, i.e., microcapsules, are all embedded with silica gel particles, and better mechanical properties are obtained. And with the increase of the addition amount of the polyurethane acrylic resin, the mechanical properties including the shrinkage modulus and the hardness are reduced, and according to the results of the addition amounts of the three polyurethane acrylic resins in the embodiment, the calculation shows that when the addition amount of the polyurethane acrylic resin is 10-80 parts, the shrinkage modulus of the hollow microspheres can reach 173MPa at most, and the hardness can reach 190MPa at most. The results of this example show that by controlling the addition amount of the urethane acrylic resin, the mechanical properties of the hollow microsphere, including the shrinkage modulus and the hardness, can be controlled, that is, the controllability of the mechanical properties of the hollow microsphere is achieved.

The above description is only of the preferred embodiments of the present invention, and it should be noted that: although the present invention has been described with reference to preferred embodiments, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.