JP6519032B1 - Method of producing microemulsion of polymerizable monomer and method of producing microresin emulsion - Google Patents

Abstract

PROBLEM TO BE SOLVED: A "subcritical emulsification method" for obtaining an emulsion having uniform particle diameter by micronizing and emulsifying a monomer in water under milder conditions by utilizing the property that subsupercritical water dissolves an oil component. To provide a method for producing a microemulsion of monomers, and to establish and provide a basic technology of “subcritical emulsion polymerization method” for resinizing the microemulsion of monomers. A method for producing a microemulsion of a polymerizable monomer, in which an oil droplet consisting of an oil component containing a polymerizable monomer is finely emulsified in water, comprising the oil component and water. Dissolve the oil component in water by mixing it at a temperature above the boiling point of water and below the critical temperature of water that can dissolve the oil component, followed by quenching while adding an emulsifier to microemulsify the oil droplets The manufacturing method of the microemulsion of the polymerizable monomer which uses the nonionic emulsifier which has a cloud point as said emulsifier, when obtaining a thing. 【Selection chart】 None

Description

  The present invention relates to a method for producing a nanosized microemulsion of a polymerizable monomer, and a microresin emulsion for obtaining an emulsion of nanosized resin particles from the microemulsion obtained by the production method , Also referred to as micro resin emulsion). More specifically, a method of producing a microemulsion of a polymerizable monomer having a uniform particle size, which is useful as an intermediate, using water in a state above the boiling point and below the critical point of water, the microemulsion The present invention relates to a technique for providing a method for producing a fine resin emulsion having a uniform particle diameter by polymerizing a polymerizable monomer (hereinafter also referred to as a monomer) contained in a substance.

  As a method of obtaining an emulsion (emulsion) obtained by mixing a substance insoluble in a solvent in a fine state in the solvent, mechanical stirring with a homomixer or the like is general. For example, when mixing oil (oil) with water as a solvent, it is carried out that the large oil droplets are refined by mechanical stirring of the mixture of water, oil component and emulsifier to obtain an emulsion. ing. However, while an oil-in-water (O / W) emulsion in which oil droplets are dispersed in water in a finer and more uniform state is required in recent years, the average of the emulsion is increased by the conventional mechanical emulsification method. It is difficult to miniaturize the particle size to nanosize. In addition, when refining to nano size by mechanical emulsification method, long processing time and huge energy are required, it can not be said that it is an industrially advantageous method, and the average particle diameter of the emulsion is nano size It is very useful if there is a method that can be miniaturized up to industrially.

  On the other hand, in recent years, new emulsification techniques have been studied using the characteristics of water. In the case of water, near the critical point (the critical temperature is 374 ° C., the critical pressure is 22.1 MPa), the density changes continuously and largely due to a slight pressure change. For example, the ability to "dissolve" as a solvent (solvency) closely correlates with the density of water, so even if the temperature is the same, it is necessary to rapidly change the solvency by changing only a slight pressure. Can. In principle, it is possible to control various physical properties of water widely, with pressure and temperature only as operating factors. In particular, supercritical water, which is an intermediate between gas and liquid, "supercritical water" can dissolve organic substances, so it is an industrially important organic solvent whose conventional use is problematic. It is also expected as a new solvent to replace. Also, above all, water itself is a non-toxic, inexpensive solvent that is abundant in nature, and from now on it is expected that the direction toward environmentally-friendly technology will be further strengthened, so “supercritical water” Technologies that make use of can be extremely useful. Even though it is a special environment such as high temperature and high pressure, "supercritical water", which is a "water" but expresses characteristics completely different from solid, liquid and gas, is attractive enough to realize a sustainable society It is highly expected as one of the basic technologies for

  As a technique using the above-mentioned "supercritical water", for example, a method for producing an emulsion using a homogeneous solution of water and a water-insoluble substance, which is obtained under high temperature and high pressure conditions near the gas / liquid critical point of water, It is proposed (patent document 1). This technology is an emulsification technology which does not require mechanical stirring by a general homomixer or the like, and is an unprecedented new emulsification technology which utilizes the characteristics of water under the limit, and its use is expected.

Patent No. 5943455 gazette

  The inventors of the present invention can utilize the characteristic that the supercritical water disclosed in the above-mentioned technology dissolves oil droplets, and can miniaturize a monomer in water, and further, an emulsion having a uniform particle size. It is recognized that it is extremely useful if it is obtained stably. As described above, if an emulsion having a fine and uniform particle diameter can be easily obtained, which can not be easily obtained by the conventional mechanical emulsification method, its use is expected. For example, in the conventional mechanical emulsification method, fine aqueous resin particles have been produced by charging a raw material such as a monomer and water into a kettle, stirring and emulsifying for a long time, and then performing polymerization treatment while stirring. If the monomers can be finely divided and emulsified in water to a uniform particle size by using the above-mentioned technology, the kettle and the stirrer become unnecessary, and the stirring time required for the conventional emulsification becomes basically unnecessary. Furthermore, if the emulsification process of raw materials such as monomers and the polymerization process of polymerizing the obtained composite oil droplets can be performed by a continuous flow method in a series of flow operations, it is possible to produce fine aqueous resin particles in a short time. It is considered to be

  However, what is actually studied in Patent Document 1 mentioned above is water and a linear saturated hydrocarbon having a carbon chain length of 10 to 14, such as decane, dodecane and tetradecane, which are relatively stable in heat resistance. It is not possible to apply the technique using this "supercritical water" to a monomer which is a substance having a radically polymerizable unsaturated group as it is a substance. For example, in the technology of Patent Document 1, the treatment temperature of water and saturated hydrocarbon such as decane is 440 ° C. for mixing water and saturated hydrocarbon, and 445 for mixing water, saturated hydrocarbon and surfactant for mixing It is considered that decomposition or the like occurs in a substance such as a monomer which is extremely high in temperature and is inferior in heat resistance and reactive as compared to such dodecane and the like. In other words, no study has been made to apply the above-mentioned new emulsification technology using "supercritical water" to many types of oil-soluble organic compounds, but at least it is a ratio to dodecane such as monomers. In order to apply it to a material having poor heat resistance, there is a problem of achieving micronization and emulsification in water at a lower treatment temperature.

  Furthermore, in order to industrially utilize the above-mentioned technique using supercritical water, the characteristics of the fine emulsion with uniform particle diameter obtained by the above technique are maintained, and the subsequent use It will be necessary to be able to carry out the treatment in the state of the above-mentioned good microemulsion. On the other hand, according to the study of the present inventors, even if a fine emulsion having fine and uniform particle diameters is obtained, the particles are easily united after that and can not be maintained in a good state. Needs to develop a technology that makes it possible to keep the state of a fine emulsion with fine and uniform particle size as long as possible, and the solution to this point is the development of a new technology using supercritical water. Recognized that it is essential to

  Therefore, the object of the present invention is to establish a new technology capable of micronizing and emulsifying a monomer in water under milder conditions than supercritical water and obtaining an emulsion with uniform particle sizes. It is an object of the present invention to provide a process for producing a microemulsion of monomers applicable to many types of oil-soluble organic compounds. Specifically, water in a state capable of dissolving an oil component containing a monomer, which is above the boiling point of water and below the critical temperature (in the present invention, water in this state is referred to as “subcritical water” or “subcritical water” Establish a new emulsification method using subcritical water that can produce a microemulsion of monomers under processing temperature conditions lower than the technology using “supercritical water” by using It is in. Further, the object of the present invention is to establish the above-mentioned new emulsification method, and realize the fine emulsion of the fine and uniform particle diameter of the monomer, which was difficult in the prior art, and further, the polymerization thereafter. It is possible to provide a microemulsion of monomers, which can realize that the state of oil droplets which are fine and uniform in particle diameter can be maintained for a long time with an oil droplet containing a concentration of a monomer which can be used in the process. To establish the basic technology for manufacturing A further object of the present invention is to develop a new emulsification method capable of providing the above-mentioned excellent monomer microemulsion, thereby enhancing industrial applicability and producing a microemulsion prepared by the new emulsification method. It is an object of the present invention to find out a basic technology for making it possible to obtain an emulsion of nano-sized fine resin particles from a material.

The problems described above are achieved by the present invention described below. That is, the present invention
[1] A method for producing a microemulsion of a polymerizable monomer, wherein oil droplets composed of an oil component containing a polymerizable monomer are finely emulsified in water,
The oil component is dissolved in water by mixing the oil component and water in a state where the oil component can be dissolved, at a temperature above the boiling point of water and below the critical temperature of water, and then quenched while adding an emulsifier. The present invention provides a method for producing a microemulsion of a polymerizable monomer, wherein a nonionic emulsifier having a cloud point is used as the emulsifier when obtaining the microemulsion of the oil droplets.

As a preferable form of the manufacturing method of the microemulsion of the polymerizable monomer of this invention, the following is mentioned.
[2] The method according to the above [1], wherein the addition of the nonionic emulsifier having a cloud point is performed under the temperature condition higher than the cloud point.
[3] The method according to [1] or [2], wherein the nonionic emulsifier having a cloud point comprises two or more nonionic emulsifiers having different cloud points.
[4] The process according to any one of [1] to [3], wherein the polymerizable monomer is an acrylic monomer, and the SP value of the oil component is 8.0 to 10.0.
[5] The method according to [4], wherein the acrylic monomer contains 0.1% by mass or more of an acrylic monomer having a hydrophilic functional group.
[6] The method for producing [5], wherein the hydrophilic functional group is a carboxy group or a hydroxy group.
[7] The method according to any one of the above [1] to [6], wherein the particle diameter of the microemulsion is 20 nm to 400 nm.

  The present invention relates, as another embodiment, a method for producing an emulsion of fine resin particles, which is a method for producing a microemulsion of a polymerizable monomer according to any one of the above [1] to [7]. Hereinafter, the emulsion of fine resin particles is obtained by polymerizing the polymerizable monomer contained in the microemulsion from the microemulsion of the polymerizable monomer obtained by the “subcritical emulsification method”). (Hereinafter, also referred to as “subcritical emulsion polymerization method”) to provide a method for producing a microresin emulsion. As a preferred embodiment, the method for producing a microresin emulsion according to the above [8], which polymerizes at the temperature below the cloud point of the nonionic emulsifier during the polymerization, may be mentioned.

  According to the present invention, oil components such as monomers which are solvent-insoluble substances are used in the prior art which requires mechanical stirring when mixed in a fine state in the solvent to obtain an emulsion. The need for a kettle or stirrer that eliminates the need for a long stirring time required for the emulsification operation is eliminated. The characteristics of the subcritical water are effectively utilized, and the monomer is simply finely divided and emulsified in water in a short time. There is provided a method for producing a microemulsion of monomers. Further, according to the present invention, when obtaining a microemulsion of the monomer, the monomer is finely divided and emulsified in water at a lower temperature, which is important to expand the application range of the monomer species, An optimal monomer selection method is established for obtaining a microemulsion of monomers that is important to realize the effect. Furthermore, according to the production method of the present invention, the microemulsion of the formed monomer is an oil droplet having a concentration that can be used in the step of polymerizing the monomer thereafter, and the coalescence of oil droplet particles formed after emulsification is effective. It is possible to provide a microemulsion of monomers which can be kept in the form of oil droplets which are finely suppressed and which have a fine and uniform particle size for a relatively long time. More specifically, according to the present invention, a microemulsion of monomers can be rapidly obtained, for example, by treating an acrylic monomer, which is a raw material such as a paint or an adhesive, under milder conditions. Since coalescence of oil droplet particles is effectively suppressed, it is possible to realize a new technology in which a microresin emulsion can be obtained by further polymerizing the monomers in the obtained microemulsion. That is, according to the present invention, it is possible to obtain a fine emulsion of fine and uniform particles of a monomer obtained by effectively using subcritical water, and a minute resin emulsion comprising the polymer thereof. The basic technology for maintaining the properties realized by the microemulsion of

It is a state diagram of water. It is a schematic diagram of the apparatus for implementing the subcritical emulsification method used by this invention. Particle size distribution of micro-sized particles of acrylic monomer obtained by conventional mechanical stirring / emulsification (mixer emulsification) and particle size distribution of emulsion of acrylic monomer obtained by carrying out the production method of the present invention It is a figure which shows the difference. FIG. 2 is a view showing the relationship between the processing temperature and the average particle size of the microemulsion of 2 ethylhexyl acrylate (2EHA) monomer obtained in Example 1. It is a figure which shows the relationship of processing temperature and average particle diameter of the micro-emulsion of the butyl acrylate (BA) monomer obtained in Example 2. FIG. It is a figure which shows the relationship of processing temperature and an average particle diameter of the microemulsion of 2 types of 2EHA and BA which were obtained in Example 3 and which were obtained. It is a figure which shows the relationship of the process temperature and average particle diameter of the microemulsion of 2 types of the 2 types of monomers of a cyclohexyl methacrylate (CHMA) and 2EHA obtained in Example 4. FIG. It is a figure which shows the relationship of processing temperature and an average particle diameter of the microemulsion of 2 types of monomers of CHMA and BA obtained in Example 5. FIG. It is a figure which shows the relationship of the process temperature and average particle diameter of the microemulsion of 3 types of monomers of CHMA, 2EHA, and methacrylic acid (mAAc) obtained in Example 6. It is a figure which shows the relationship of the processing temperature and average particle diameter of the microemulsion of 3 types of monomers, BA, ethyl acrylate (EA), and styrene (ST), obtained in Example 7. It is a figure which summarizes the relationship between the SP value of each raw material monomer obtained by implementing the manufacturing method of this invention, and its optimal processing temperature.

(Subcritical water)
Next, the present invention will be described in more detail by way of preferred embodiments for carrying out the invention. First, in the present invention, which is referred to as "subcritical water or subcritical water", which can be used in the present invention and capable of dissolving an oil component containing a polymerizable monomer (monomer), the critical temperature of water or more than the boiling point of water Water under the condition of "less than" is described. Subcritical water, as shown in the phase diagram of water in FIG. 1, is a liquid in a temperature range from the boiling point (100 ° C.) at normal pressure to the critical temperature (374 ° C.) before becoming supercritical water. This is realized by treating water with high temperature and high pressure, and the appearance refers to the state of water that holds a liquid, but is given much higher energy than ordinary liquid water molecules. Subcritical water has properties such as a low relative dielectric constant and a large ion product, which are completely different from the state of water in ordinary liquid. As shown in FIG. 1, the end point of the gas-liquid coexistence line is the critical point (374 ° C., 22.1 MPa), and the hot water in the region where the temperature is relatively low near the critical point It is critical water. This "subcritical water", like supercritical water, has properties that ordinary waters do not have, such as dissolving or hydrolyzing nonpolar organic compounds.

  The inventors of the present invention have, for example, an oil component containing a monomer when water is brought to a state of 20 MPa or more, preferably 22 MPa or more and above the boiling point of water, preferably 200.degree. C. or more and below the critical temperature (374.degree. It can be dissolved in “subcritical water” and then quenched with the addition of a specific emulsifying agent, at a lower emulsification treatment temperature without using mechanical means, which is the purpose of the present invention. The monomer can be micronized and emulsified in water in the form of oil droplets with uniform particle diameter, and moreover, it is suppressed that the micronized particles are coalesced in a short time and large particles are produced I found that I could get the effect. As described above, since it is possible to effectively suppress the coalescence of the particles, for example, when the manufactured microemulsion of the monomer is polymerized in the next step, the obtained polymer is kept in a finely divided state It will be possible to

  The present invention makes it possible to finely emulsify in oil an oil droplet consisting of an oil component containing a monomer by means of the above-mentioned "subcritical water" property and to keep the state stable by an unconventional method. Related to new technologies. As described above, according to the technical feature of the present invention, in particular, the use of a nonionic emulsifier having a cloud point in combination with the formation of an oil droplet consisting of an oil component containing a monomer enables the refined oil droplet particles to be produced in a short time. The point is that it is possible to suppress the occurrence of the union. Furthermore, as a technical feature of the present invention, as a preferable form, when the monomer is an acrylic monomer, the SP value in the oil component containing the acrylic monomer as the raw material is 8.0 to 10.0. By adjusting as described above, it is found that it is possible to obtain a microemulsion of oil droplets consisting of the above-mentioned oil component, which is made finer and emulsified in a state where the particle diameter is uniform.

<Production equipment for subcritical water>
The schematic schematic flowchart of the apparatus for implementing the "subcritical emulsification method" performed by the manufacturing method of the microemulsion of the monomer of this invention in FIG. 2 was shown. This apparatus, as shown in FIG. 2, includes a mixing section including an inflow path for respectively flowing in two liquids of water and an oil component containing a monomer, and a mixer in which the inflowing liquids are merged. And a supercritical / subcritical process section (subcritical process section in FIG. 2) for bringing water into a supercritical state or a subcritical state by setting the temperature to an appropriate high temperature and high pressure disposed subsequent to the mixing section. And a specific emulsifying agent is added to the solution obtained from the process, and the mixture is rapidly cooled (quenched) to form an emulsion by phase separation of water and a monomer while suppressing particle coalescence. And a part.

  By using the apparatus as described above, the oil component containing the monomer is instantly dissolved in the subcritical water in the subcritical process part. Then, by adding an emulsifier having a cloud point in the next cooling part and quenching it, microparticles having a uniform particle diameter are rapidly formed, and furthermore, the formed microparticles can be produced in a short time. There is obtained a microemulsion consisting of oil droplets containing the monomer targeted by the present invention, in which coalescence is effectively suppressed. According to the apparatus of the configuration shown in FIG. 2, water having a unique property of a supercritical state or a subcritical state appearing in a high temperature / high pressure extreme environment can be obtained. In the production method of the present invention, among the water showing the unique property, by utilizing the water in the subcritical state milder than the supercritical state, the industrial application aimed at the present invention It is possible to obtain a microemulsion consisting of oil droplets containing a monomer which is finely divided and emulsified in a state where the particle diameter is uniform, and in which particles are effectively prevented from being coalesced in a short time. Is realized. In the present invention, various experiments were carried out using the supercritical emulsification apparatus “SFW-E40S” designed and manufactured by AKICO, and as a result of intensive investigations, the method of producing the microemulsion of the monomer of the present invention was achieved. is there.

  FIG. 3 shows the case where fine particles of an acrylic monomer are obtained by the conventional mechanical stirring emulsification (mixer emulsification) and the emulsion (oil droplets) of the acrylic monomer by the subcritical emulsification method of the present invention. When obtained, the difference in particle size distribution was shown. Specifically, a 1: 1 mixture solution of cyclohexyl methacrylate (CHMA) and 2-ethylhexyl acrylate (2EHA) was used as a raw material monomer. The amount of the emulsifier having a cloud point was 25% of the raw material monomer. The emulsification conditions in the above-described apparatus for carrying out the subcritical emulsification method were a temperature of 350 ° C. × a pressure of 25 MPa (subcritical condition), and the emulsification time was 5 seconds. Moreover, the emulsification conditions of the mechanical stirring emulsification which is a conventional method were set to 5000 rpm x 30 minutes.

  As shown in FIG. 3, in the time of about 30 minutes in the conventional method, the emulsion obtained has a broad peak of 4000 to 10000 nm and a sharp peak at 500 to 600 nm, and a large particle diameter It has been found that it becomes an emulsion of monomers of various particle sizes, including those having a broad particle size distribution. On the other hand, in the subcritical emulsification method performed in the present invention, it was confirmed that an emulsion of a monomer having a sharp peak in the vicinity of 100 nm can be obtained without any large particle diameter being included.

  As described above, as a result of intensive research aimed at achieving the object of the present invention, the inventors of the present invention have found that a novel emulsification method (subcritical emulsification method (subcritical emulsification) is completely different from the conventional principle of mechanical agitation. Found the law). As a result, oil droplets consisting of an oil component containing a monomer are finely emulsified in water, and in particular, the occurrence of coalescence of the particles after formation is suppressed, and the oil having a uniform particle diameter in water stably. We succeeded in producing a microemulsion of monomers required to obtain a microresin emulsion having the same properties, which is micronized and emulsified in the state of droplets.

  On the other hand, in the conventional emulsification method by mechanical stirring, water and oil are stirred, mixed and emulsified by mechanical stirring power, and even if sufficiently stirred for several minutes to several tens of minutes, oil of about 500 nm to 5000 nm It is only possible to make drops. For this reason, in order to make it finer than this, mechanical stirring needs to be performed over a longer time. Further, even if the refining process is performed for a longer time, the particle size distribution of the fine particles becomes a broad particle size distribution as shown in FIG. It will not be a uniform emulsion with On the other hand, in the technique of Patent Document 1 using "supercritical water" mentioned above, the application example thereof is different from the present invention directed to monomers, and a linear saturated chain having a carbon chain length of 10 to 14 In the case of using hydrocarbon and further using supercritical water having a temperature higher than that of the subcritical water used in the present invention, although different in this point, from mixing into supercritical water to preparation of an emulsion It is said that a minute oil droplet of about 40 nm to about 500 nm can be formed in only 10 seconds to a few tens of seconds without any mechanical stirring. FIG. 3 shows the result of confirmation of this point using an oil component containing a monomer and using “subcritical water” in which the conditions are milder than “supercritical water”.

  As shown in FIG. 1, water exists in the state of gas (water vapor), liquid, solid (ice), but when the temperature and pressure are increased, high temperature and high pressure (critical point: 374 ° C., 22 MPa) (critical point ), There is no boundary between liquid and gas, and it becomes supercritical water at higher temperature and pressure. In supercritical water, although it is a liquid, there is a unique phenomenon that both the gas characteristics exist, the density decreases, and the specific inductive capacity also decreases. In supercritical water, the relative dielectric constant is lowered, so that a solvent similar to that of the solvent is generated, and the supercritical water is in the state of dissolving the oil. The relative dielectric constant of water is about 79 at room temperature, and the relative dielectric constant of monomers which are oil components is about 40 or less. Therefore, even if water and monomers are mixed under normal temperature and normal pressure, it is uniform. It is impossible to combine them, and they become separated into two phases. On the other hand, as the temperature rises, the relative dielectric constant gradually decreases, and for example, in the supercritical state at a temperature of 400 ° C. and a pressure of 25 MPa, the relative dielectric constant of water decreases to 6 and becomes equivalent to the oil component Therefore, what has been divided into the aqueous phase and the organic (oil) phase at normal temperature and pressure becomes the homogeneous phase in which water and oil are compatible in the above-mentioned supercritical state. And these means that even if it is not in the supercritical state, the compatibility with the monomer which is the oil component can be enhanced by setting the water to a high temperature and high pressure to lower the relative dielectric constant. doing.

  Under the above-mentioned recognition, the inventors of the present invention, when using water in the subcritical state, which is milder than in the supercritical state, have a lower heat resistance temperature than that targeted by the technology of Patent Document 1, and at normal temperature and pressure. It was considered that oil components containing monomers that never became a uniform phase could be emulsified in water in a good state as fine oil droplets, and the present invention was made. is there. That is, in the technology of the present invention, subcritical water which is hot water in a milder state than the high temperature / high pressure supercritical state water described above is used.

  Next, nonionic emulsifiers, monomers and polymerization initiators having a cloud point that can be used in the production method of the present invention will be described. In the present specification, the term "(meth) acrylic" means both "acrylic" and "methacrylic", and the term "(meth) acrylate" means both "acrylate" and "methacrylate". Means Moreover, these are collectively called acrylic monomers.

(emulsifier)
Among the nonionic surfactants listed below, those having a cloud point are used in the production method of the present invention. As the nonionic emulsifier having a cloud point, for example, one having a cloud point may be selected and used from polyoxyethylene alkyl ethers, polyoxyethylene alkylene derivatives, polyoxyalkylene alkenyl ethers and the like. it can. Specifically, polyoxyethylene lauryl ethers, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene myristyl ether, polyoxyethylene alkylene alkyl ether, polyoxyethylene di-styrenated phenyl Ether, polyoxyethylene polyoxypropylene glycol, etc., or nonionic surfactants such as reactive nonionic surfactants having the above-described skeleton and a polymerizable unsaturated double bond in the molecule can be mentioned. . These nonionic emulsifiers may be used alone or in combination of several kinds.

  Among the surfactants listed above, it is preferable to use one having a “cloud point” of 50 ° C. to 100 ° C. The present inventors have mixed an oil component containing monomers as described above and water in a state (subcritical water state) above the boiling point of water and below the critical temperature capable of dissolving the oil component. When a component is dissolved in subcritical water and then quenched while adding an emulsifier to obtain a microemulsion of oil droplets, using a nonionic emulsifier having a cloud point as mentioned above as an emulsifier, It has been found that the coalescence of oil droplet particles, which may occur in a short time, can be effectively suppressed, and the coalescence of minute oil droplet particles can be effectively suppressed. According to the study of the present inventors, it is further preferable to use at least two nonionic emulsifiers having different cloud points, as described above, and in this case, it is possible to suppress the generation of oil droplet particles. The more remarkable effect is obtained. Further, for example, by “quenching” at about 50 ° C./second to 200 ° C./second, it is possible to effectively suppress the formation of oil droplets to be formed and the suppression of coalescence of oil droplet particles. Specifically, after obtaining a microemulsion of oil droplets, the time until the occurrence of coalescence of oil droplet particles is observed is performed according to the constitution of the production method of the present invention to obtain a microemulsion of oil droplets. In the case of the production method of the present invention, the occurrence of coalescence of oil droplet particles is recognized in the case of the production method of the present invention in comparison between the case of the present invention and the case of obtaining a microemulsion of oil droplets without using a nonionic emulsifier having a cloud point. The time until it is done can be extended several times to 1000 times. For example, when a microemulsion of oil droplets is obtained without using a nonionic emulsifier having a cloud point, coalescence of oil droplet particles is recognized in a few seconds to a few minutes in the early case, and coalescence proceeds to separate Could occur. On the other hand, in the case of the production method of the present invention using a nonionic emulsifier having a cloud point, coalescence of oil droplet particles is not observed at least at least sufficiently, often more than one day, and in some cases, monthly. The

(Polymerizable monomer)
The polymerizable monomer (monomer) used in the production method of the present invention may be any radically polymerizable monomer, and (meth) acrylic monomers, carbonyl group-containing monomers, and the like as listed below: Any of an aromatic vinyl monomer, a nitrogen-containing monomer, and the like can be used.

The (meth) acrylic monomers are not particularly limited, but any of those listed below can be used. Specifically, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, i-propyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate Sec-butyl (meth) acrylate, t-butyl (meth) acrylate, n-amyl (meth) acrylate, i-amyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n Alkyls having an alkyl group having 1 to 18 carbon atoms, such as octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, lauryl (meth) acrylate and stearyl (meth) acrylate (Meth) acrylates;
Cycloalkyl (meth) acrylates such as cyclohexyl (meth) acrylate and p-t-butylcyclohexyl (meth) acrylate;
Hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 2- (3-) hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and glycerol mono (meth) acrylate;
Hydroxypolyethylene oxide mono (meth) acrylate, hydroxypolypropylene oxide mono (meth) acrylate, hydroxy (polyethylene oxide-polypropylene oxide) mono (meth) acrylate, hydroxy (polyethylene oxide-propylene oxide) mono (meth) acrylate, hydroxy (polyethylene oxide -Polytetramethylene oxide) mono (meth) acrylate, hydroxy (polyethylene oxide-tetramethylene oxide) mono (meth) acrylate, hydroxy (polypropylene oxide-polytetramethylene oxide) mono (meth) acrylate, hydroxy (polypropylene oxide-polytetra) Methylene oxide) mono (meth) acrylate, methoxy polyethylene oxide mono ( ) Acrylate, lauroxy polyethylene oxide mono (meth) acrylate, stearoxy polyethylene oxide mono (meth) acrylate, allyloxy polyethylene oxide mono (meth) acrylate, nonyl phenoxy polyethylene oxide mono (meth) acrylate, nonyl phenoxy polypropylene oxide mono (meta) Polyalkylene oxide group-containing (meth) acrylates such as acrylate, octoxy (polyethylene oxide-polypropylene oxide) mono (meth) acrylate, nonyl phenoxy (polyethylene oxide-propylene oxide) mono (meth) acrylate, etc.
Hydroxycycloalkyl (meth) acrylates such as p-hydroxycyclohexyl (meth) acrylate;
Lactone modified hydroxyalkyl (meth) acrylates;
Aminoalkyl (meth) acrylates such as 2-aminoethyl (meth) acrylate, 2-dimethylaminoethyl (meth) acrylate, 2-aminopropyl (meth) acrylate and 2-butylaminoethyl (meth) acrylate;
Amide group-containing (meth) acrylates such as (meth) acrylamide, N-methylol acrylamide, N-butoxymethyl (meth) acrylamide; ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, butylene glycol di (meth) Multifunctional (meth) acrylates such as acrylate and trimethylolpropane tri (meth) acrylate;
Metal-containing (meth) acrylates such as zinc di (meth) acrylate;
Silicon-containing (meth) such as γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ- (meth) acryloxypropylethyldiethoxysilane, γ- (meth) acryloxypropyltriethoxysilane, etc. Acrylates;
2- (2'-hydroxy-5 '-(meth) acryloxyethylphenyl) -2H-benzotriazole, 1- (meth) acryloyl-4-hydroxy-2,2,6,6-tetramethylpiperidine, 1 -(Meth) acryloyl-4-methoxy-2,2,6,6-tetramethylpiperidine, 1- (meth) acryloyl-4-amino-4-cyano-2,2,6,6-tetramethylpiperidine, etc. , UV resistant group-containing (meth) acrylates;
Dimethylaminoethyl (meth) acrylate methyl chloride salt, allyl (meth) acrylate, glycidyl (meth) acrylate, (meth) acrylonitrile, phenyl (meth) acrylate, benzyl (meth) acrylate, isobornyl (meth) acrylate, tetrahydrofurfuryl ( Other (meth) acrylic monomers such as meth) acrylate, methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate and the like;
Based on an aldehyde or keto group such as acrolein, diacetone acrylamide, formyl styrene, vinyl methyl ketone, vinyl ethyl ketone, vinyl isobutyl ketone, pivalin aldehyde, diacetone (meth) acrylate, acetonitrile acrylate, acetoacetoxyethyl (meth) acrylate, etc. A carbonyl group-containing monomer;
Aromatic vinyl monomers such as styrene (St), methylstyrene, chlorostyrene and methoxystyrene;
Conjugated diene type monomers such as 1,3-butadiene, isoprene, 2-chloro-1,3-butadiene and the like;
Maleic anhydride, succinic anhydride, phthalic anhydride to hydroxyalkyl (meth) acrylates such as (meth) acrylic acid, acrylic acid dimer, 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate A carboxy group-containing monomer such as a reacted monomer;
Although ethylene, vinyl propionate, etc. may be mentioned, it is not limited to these. These can be used alone or in combination of two or more.

  An acrylic monomer is mentioned as a suitable monomer in the case of applying the manufacturing method of the microemulsion of this invention. The present invention is a technology applicable to general-purpose acrylic monomers, and is expected to be used in the future.

  Moreover, in order to make the oil droplet containing an acryl-type monomer into a more favorable emulsification state with the manufacturing method of the microemulsion of this invention, the acryl-type monomer which has a hydrophilic functional group in the acryl-type monomer to emulsify. Preferably, 0.1% by mass or more is contained. The hydrophilic functional group is preferably a carboxy group or a hydroxy group.

  As described later, in the present specification, the microemulsion of monomers obtained by the production method of the present invention is described by taking acrylic monomers as an example, and as described above, the application to acrylic monomers is industrial Although expected, the technology of the present invention is not necessarily limited to acrylic monomers. According to the present invention, it is possible to rapidly obtain a fine, uniform particle diameter uniform emulsion of various monomers or plural kinds of monomers as mentioned above. In addition, the microemulsion of the monomer obtained by the production method of the present invention may contain any of the above-mentioned monomers, for example, straight-chain alkanes such as heptane, oligomers, etc. (eg, polybutene type, polybutadiene It also becomes possible to produce a microemulsion consisting of composite oil droplets, in which a system, a polyester system, a polyether system, a polycarbonate system, a polyolefin system, a urethane system, a silicone system, a fluorine resin etc.) is dissolved in a monomer. The ratio of linear alkanes and oligomers in the case of composite oil droplets varies depending on the application and the like, but is preferably less than 50% by mass.

  According to the study of the present inventors, it is preferable to use, for example, a silicone oil in combination with the monomers. As silicones, it is preferable to use silicone oil or modified silicone oil. Examples of silicone oils include dialkyl silicone oils; cyclic polydialkyl siloxanes or cyclic polyalkylphenyl siloxanes; alkylphenyl siloxanes and the like. In addition, higher fatty acid modified silicone oil, methyl chlorinated phenyl silicone oil, methacryl modified silicone oil, alkyl modified silicone oil, methyl hydrogen silicone oil, amino modified silicone oil, epoxy modified silicone oil and the like can be used. Examples of commercially available silicone oils include KF-96 [10, 20, 30, 50, 500, 1000, 3000], KF-56, KF-58, and KF-54 manufactured by Shin-Etsu Chemical Co., Ltd. Ets. Also, TSF 451 series, TSF 456 series, TSF 410, 411, 440, 4420, 484, 483, 431, 433 series, THF 450 series, TSF 404, 405, 406, 451-5A, 451-10A manufactured by Toshiba Silicone Co., Ltd. 437 series, TSF 440, 400, 401, 4300, 4445, 4700, 4450, 4702, 4730 series, TSF 434, 4600 series etc., and further, HS-200 etc. manufactured by Toray Silicone Co., Ltd. In the present invention, the content ratio of silicones in the oil component used as a raw material in the case of using silicone oil etc. in combination with monomers is preferably, for example, about 5% to 20%.

  The present inventors are in the process of studying to achieve the object of the present invention, depending on the type of monomer, or even in the same type of monomer, a process to obtain a finer fine emulsion which has been made finer We found that the temperatures were different. Therefore, in order to clarify this point, tests were performed using various monomers in the above-described apparatus, and details on this point were examined. As a result, when the SP value (solubility parameter) of the oil component (monomer) is 8.0 to 10.0, it has been found that finer microemulsion can be obtained under mild conditions at lower temperatures. . The SP value for each monomer is already known, and is used, for example, when selecting a combination of highly compatible monomers, or when selecting a poor solvent and a good solvent for the monomers to be used. . Therefore, using SP values of known homopolymers, monomers having SP values of 8.0 to 10.0 may be appropriately selected and used. When a plurality of monomers are used, the SP value of the oil component (monomer) is preferably 8.0 to 10.0, more preferably 8.5 to 9.5, using these known SP values. The composition may be adjusted and used so that The present inventors also obtain a fine microemulsion in a good state under mild conditions of low temperature even when using a combination of two or more monomers adjusted so that the SP value is within the above range. I confirmed that I could do it.

Here, the SP value (solubility parameter) is a physical property value defined by the square root of the cohesive energy density calculated by the following equation.
δ (SP value) = (ΣEcoh / ΣV) ^1/2

  As shown in the above equation, the SP value (solubility parameter) is calculated from the molecular structure by the Fedors estimation method, and is calculated based on the cohesive energy density and the molar molecular volume. That is, it can be defined as the above equation from the total ΣEcoh of the cohesive energy density of each functional group of the substance and the total ΣV of molar molecular volume. Although the unit of aggregation energy is often J / mol, in this specification, the SP value of the unit of J / mol was divided by the coefficient of 4.19 to use cal / mol. As the atomic group, the aggregation energy specific to the group, and the molar volume constant, the numerical values described in “RF Fedors, Polym. Eng. Sci., 14 [2], 147-154 (1974)” can be used.

(Polymerization initiator)
From the microemulsion of the monomer obtained by the method for producing the microresin emulsion of the present invention, a polymerization initiator which can be used when polymerizing the monomer contained in the microemulsion depends on the kind of the used monomer. Although it depends on the matter, it is not particularly limited, and any conventionally known one can be used. For example, polymerization initiators generally used for radical polymerization as listed below can be appropriately used.

As specific examples, persulfates such as potassium persulfate, sodium persulfate, ammonium persulfate and the like;
Azobisisobutyronitrile, 2,2′-azobis (2-methylbutyronitrile), 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (4-methoxy-2 Oil-soluble azo compounds such as 4-, 4-dimethylvaleronitrile), 2-phenylazo-4-methoxy-2,4-dimethylvaleronitrile;
2,2'-azobis {2-methyl-N- [1,1-bis (hydroxymethyl) -2-hydroxyethyl] propionamide}, 2,2'-azobis {2-methyl-N- [2- (2- 1-hydroxyethyl)] propionamide}, 2,2'-azobis {2-methyl-N- [2- (1-hydroxybutyl)] propionamide}, 2,2'-azobis [2- (5-methyl) -2-imidazolin-2-yl) propane] and salts thereof, 2,2′-azobis [2- (2-imidazolin-2-yl) propane] and salts thereof, 2,2′-azobis [2- (3) , 4,5,6-Tetrahydropyrimidin-2-yl) propane] and salts thereof, 2,2′-azobis {2- [1- (2-hydroxyethyl) -2-imidazolin-2-yl] propane} and Its salts, 2, 2 ' Zobis (2-methylpropionamidine) and its salts, 2,2'-azobis (2-methylpropyneamidine) and its salts, 2,2'-azobis [N- (2-carboxyethyl) -2-methylpropion Water-soluble azo compounds such as amidine] and salts thereof;
Organic peroxides such as benzoyl peroxide, cumene hydroperoxide, t-butyl hydroperoxide, t-butylperoxy-2-ethylhexanoate, t-butylperoxyisobutyrate and the like can be mentioned.

  These polymerization initiators can be used alone or in combination of two or more. In addition, when acceleration of the polymerization rate and low temperature polymerization at 70 ° C. or lower are desired, it is advantageous to use a reducing agent such as sodium bisulfite, ferrous sulfate or ascorbate in combination with a radical polymerization catalyst, for example. .

  Hereinafter, the present invention will be specifically described by showing an example which has reached the above conclusion. The present invention is not limited to the following examples.

Example 1 Preparation of Microemulsion of Monomer
The following liquid materials A to C were prepared.
Liquid A (water): Ion-exchanged water Liquid B (oil droplets raw material): 2-ethylhexyl acrylate (2EHA, SP value = 8.62)
Liquid C (emulsifier): 5% diluted aqueous solution of Neugen XL-100 (trade name, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., polyoxyalkylene branched decyl ether, cloud point = 79 ° C, HLB 14.7)

  Using the above-mentioned supercritical water supply apparatus "SFW-E40S" capable of supplying subcritical water to supercritical water manufactured by AKICO, a test apparatus having a configuration as shown in Fig. 2 was prepared. In this apparatus, a mixing portion of oil droplet raw materials comprising an inflow path of liquid of two raw materials and a mixer where the inflowing liquid merges and water arranged in the subsequent portion of the mixing portion is in a supercritical state or A supercritical / subcritical process part for converting to a hot water in a critical state, and a liquid obtained from the process is rapidly cooled at a rate of about 150 ° C./sec. And a cooling unit to obtain the In order to make the production method of the present invention feasible, the test apparatus used can quench the liquid in the cooling section while adding the nonionic emulsifier having a cloud point to the liquid coming out of the supercritical / subcritical process section It is a structure. The object of the present invention is to obtain a microemulsion of monomers formed by finely emulsifying, in oil, oil droplets consisting of an oil component containing monomers under milder conditions. The conditions in the process part were high temperature and high pressure at which the water temperature becomes hot water of 300 ° C. to 370 ° C. before the critical temperature. Therefore, as shown in FIG. 2, the supercritical / subcritical process part is hereinafter referred to as a subcritical process part.

  Using the apparatus configured as described above, 7.8 ml / min of water as solution A and 2 EHA (oil-droplet raw material) of solution B were allowed to flow in from the inflow path at a rate of 2.2 ml / min. In the subcritical process part, the oil droplet raw material was dissolved in water under two conditions of high temperature and high pressure where water becomes hot water of 350 ° C and high temperature and high pressure where hot water becomes 370 ° C. Subsequently, the liquid from the subcritical process unit was added at a rate of 10 ml / minute to the nonionic emulsifier solution having the cloud point of liquid C at the initial stage of formation of oil droplets in the cooling unit. As a result, when the temperature of the hot water in the subcritical process portion is 370 ° C., an oil droplet having an average particle diameter as small as 191 nm is obtained. As shown in FIG. 4a, even under the condition of hot water of 350 ° C., small oil droplets having an average particle diameter of 200 nm were obtained. In addition, the particle size distribution of the oil droplets obtained under the condition of 370 ° C. shows a sharp normal distribution (not shown), and it was confirmed that a fine and uniform emulsion was obtained. Measurement of the mean particle size and particle size distribution of the obtained oil droplets was determined by dynamic light scattering. The measurement of the average particle diameter (diameter) by the dynamic light scattering method was carried out at 25 ° C. using FPAR-1000 (trade name, manufactured by Otsuka Electronics Co., Ltd.) after diluting the emulsion with water to an appropriate concentration. .

Examples 2 to 7 Preparation of Microemulsion of Monomer
Examples 2 to 7 were also performed according to Example 1 described above. In Examples 2 to 7, the conditions of the water temperature in the subcritical process part are changed at every 20 ° C. for Example 4 and every 10 ° C. for the other Examples in the respective temperature ranges shown in Table 1 went. Table 1 summarizes the types and compositions of the raw material monomers used in Examples 1 to 7 and the SP values of the raw material monomers. Also, in Table 1, the minimum value of the average particle diameter of the particles of the obtained emulsion and the temperature at which the emulsion having this minimum particle diameter was obtained are shown in parentheses in each case using these starting monomers. Described in the writing, shown collectively.

<Relationship between Average Particle Size of Emulsion of Monomers Obtained in Examples 1 to 7 and Temperature of Subcritical Step>
FIGS. 4a to 4g show microemulsions comprising the respective temperature conditions in the subcritical step part and the respective monomers obtained at each temperature for each of the raw material monomers used in Examples 1 to 7 described above. The relationship of the average particle diameter of is shown collectively. Moreover, what plotted SP value of each raw material monomer used in Example 1-7 in FIG. 5 and the optimal processing temperature in that case was shown. This results in lower temperatures below the critical point of water when using feed monomers that are adjusted to have an SP value of 8.0 to 10.0, more preferably 8.5 to 9.5. It has been found that, under mild conditions, fine particles and a uniform, fine emulsion of monomers can be obtained.

<Evaluation of Coalescence of Particles of Microemulsion of Monomers Obtained in Examples 1 to 7>
For comparison, in each of Examples 1 to 7, in the cooling section, the nonionic value of liquid C under the condition of the water temperature in the subcritical process section where the value of the average particle size of the particles of the obtained emulsion was the minimum value. A microemulsion was prepared under the same conditions except that the system emulsifier solution was not added, and the time until the coalescence of the particles in the obtained emulsion was measured. Then, in each of Examples 1 to 7, in the case where the value of the average particle diameter of the particles of the emulsion is the minimum value, the time until the uniting of the particles in the obtained emulsion is measured is measured. Tried to do. However, in the case of the microemulsion of each comparative example, in any case, the time until the coalescence of the particles is generated is short, which makes it difficult to measure. On the other hand, in the microemulsions in the corresponding examples, no coalescence of particles occurred even after one day.

<Examples 8 and 9: Polymerization of microemulsion obtained by subcritical emulsification method-1>
By the method according to Examples 1 to 7, a liquid microemulsion (emulsion liquid) containing two kinds of monomers shown in Table 2 at a concentration of 1% was prepared. At this time, in Example 8, a 1% diluted aqueous solution of Neugen TDS-80 (trade name, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., polyoxyethylene tridecyl ether, HLB 13.3) is used as the liquid C (emulsifier) described above. In Example 9, 0.5% diluted aqueous solution of Neugen TDS-80 (Example 9) was used respectively. The inflow rate of each solution is 9.8 ml / min of water as solution A, and the solution B, which contains two monomers, is allowed to flow in at a rate of 0.2 ml / min, Subcritical emulsification was performed at a water temperature of 350 ° C. and a pressure of 25 MPa by adding C liquid at a rate of 10 ml / min at the initial stage when oil droplets began to form. Then, after confirming that no coalescence of particles occurred, 5% of Perbutyl H (trade name: manufactured by NOF CORPORATION) as a polymerization initiator was added to 250 g of the emulsion obtained by the subcritical emulsification method. 1 g of a diluted aqueous solution and 1 g of a 5% diluted aqueous solution of erythorbic acid were added, and the mixture was stirred at 80 ° C. for 2 hours for polymerization treatment to obtain a resin emulsion.

  Table 2 summarizes the average particle size of the microemulsion obtained by the subcritical emulsification method and the average particle size of the microresin emulsion obtained by the polymerization treatment obtained in Examples 8 and 9 described above. The

<Example 10: Polymerization of microemulsion obtained by subcritical emulsification method 2>
By the method according to Examples 1 to 7, a liquid nanoemulsion (emulsion) comprising two monomers shown in Table 3 was produced. At this time, a 5% diluted aqueous solution of Neugen TDS-80 (trade name, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., polyoxyethylene tridecyl ether, cloud point 60 ° C., HLB 13.3) is used as the liquid C (emulsifier) described above. did. The inflow rate of each solution is 7 ml / min of water as solution A, and the solution B formed by blending two monomers is allowed to flow in at rate of 3 ml / minute, and oil droplets are formed in the cooling unit. Liquid C was added at a rate of 10 ml / min at the initial stage where it began to be carried out, and subcritical emulsification was performed at a water temperature of 350.degree. C. and a pressure of 25 MPa. Then, after confirming that no coalescence of particles occurred, 250 g of the emulsion obtained by the above-mentioned subcritical emulsification method, 1 g of a 5% diluted aqueous solution of perbutyl H as a polymerization initiator, and 5% of erythorbic acid 1 g of diluted aqueous solution was added, and polymerization was performed under the following two types of temperature conditions. The resin emulsion polymerized by stirring at 80 ° C. for 2 hours and the resin emulsion polymerized by stirring for 8 hours at 25 ° C. were obtained.

<Example 11: Polymerization of microemulsion obtained by subcritical emulsification method-3>
By the method according to Examples 1 to 7, a liquid microemulsion (emulsion liquid) containing two kinds of monomers shown in Table 3 at a concentration of 10% was prepared. At this time, a 5% diluted aqueous solution of Neugen TDS-80 (trade name) described above was used as the above-mentioned liquid C (emulsifier). The inflow rate of each solution is 7.8 ml / min of water which is solution A, and the B solution formed by blending two kinds of monomers is allowed to flow in at a rate of 2.2 ml / min. Subcritical emulsification was performed at a water temperature of 350 ° C. and a pressure of 25 MPa by adding C liquid at a rate of 10 ml / min at the initial stage when oil droplets began to form. Then, after confirming that no coalescence of particles has occurred, 250 g of the emulsion obtained by the above subcritical emulsification method, 5 g of a 5% diluted aqueous solution of perbutyl H as a polymerization initiator, and 5% of erythorbic acid 5 g of diluted aqueous solution was added, and polymerization was carried out by stirring at a polymerization temperature of 25 ° C. for 15 hours to obtain a resin emulsion. As shown in Table 3, it was confirmed that the particle size of the particles after polymerization was smaller than the particle size of the monomer emulsion.

  Table 3 summarizes the average particle size of the microemulsion of the monomer obtained by the subcritical emulsification method and the average particle size of each microresin emulsion obtained by the polymerization treatment in the above Examples 10 and 11. .

<Example 12: Polymerization of microemulsion obtained by subcritical emulsification method 4>
By the method according to Examples 1 to 7, a liquid nanoemulsion (emulsion) comprising two monomers shown in Table 4 was produced. At this time, a 22.5% diluted aqueous solution of Neugen TDS-80 (trade name, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., polyoxyethylene tridecyl ether, cloud point 60 ° C., HLB 13.3) as the above-mentioned liquid C (emulsifier) It was used. The inflow rate of each solution is 15 mL / min of water which is solution A, and two monomers of CHMA and 2EHA and silicone oil KF-96-50cs (trade name: Shin-Etsu Chemical Co., Ltd.), Liquid B was mixed at a ratio of 45:45:10 and allowed to flow at a rate of 15 ml / min, and liquid C was added at a rate of 15 ml / min at the initial stage when oil droplets began to form in the cooling section. Subcritical emulsification was performed at a water temperature of 350 ° C. and a pressure of 25 MPa. After confirming that no coalescence of particles occurred, 100 g of the emulsion obtained by the above-mentioned subcritical emulsification method was 3 g of a 5% diluted aqueous solution of perbutyl H as a polymerization initiator and 5% of erythorbic acid. 3 g of diluted aqueous solution was added, and the mixture was stirred at 25 ° C. for 15 hours to obtain a resin emulsion subjected to polymerization treatment.

  Table 4 summarizes the average particle size of the microemulsion of the monomer obtained by the subcritical emulsification method and the average particle size of the microresin emulsion obtained by polymerization treatment obtained in Example 12 above. The

<Comparative Example 1: Preparation of an emulsion prepared by changing the emulsification conditions of Example 1 to supercritical conditions>
As a comparison of Example 1, an emulsion of monomers was prepared under the same conditions as Example 1 except that the emulsification temperature conditions were changed from subcritical conditions to 440 ° C. as supercritical conditions.

  Table 5 shows the properties of the emulsion of the monomer obtained in Comparative Example 1 above. As a result, from the results of Example 1 shown in Table 1 and Comparative Example 1 shown in Table 5, the microemulsion of the monomer obtained by the subcritical emulsification method showed that the coalescence of the particles occurred under the supercritical emulsification condition. It turned out that it generate | occur | produced in a short time and a favorable microemulsion was not obtained.

Comparative Examples 2 and 3 Polymerization of Emulsion Produced by Conventional Mechanical Stirring
As a comparison of Examples 8 and 9, polymerization of the emulsion (emulsion liquid) of the monomer produced by the conventional mechanical stirring was performed. In the comparative example, the monomer and the emulsifier were added to ion exchanged water so that the monomer concentration and the emulsifier concentration were the same as those performed in the methods of Examples 8 and 9 described above, and the mixture was stirred at 5000 rpm × 30 minutes with a mixer. The emulsion was prepared. To 250 g of the resulting emulsion of monomers, 1 g of a 5% diluted aqueous solution of perbutyl H and 1 g of a 5% diluted aqueous solution of erythorbic acid are added as polymerization initiators, and polymerization is carried out by stirring at 80 ° C. for 2 hours, Resin emulsions of Comparative Examples 1 and 2 were obtained. Table 6 summarizes the average particle sizes of the microresin emulsions obtained by the polymerization treatment, obtained in the above Comparative Examples 2 and 3.

  From the results of Examples 8 and 9 shown in Table 2 and Comparative Examples 2 and 3 shown in Table 6, a polymerization initiator is added to the microemulsion of monomers obtained by the subcritical emulsification method, It was found that the resin emulsion obtained had a smaller average particle size than the resin emulsion obtained by polymerizing the monomer emulsion obtained by the conventional method.

  As described above, according to the present invention, when the emulsification process is performed using a subcritical emulsification method using an oil component containing a monomer as a raw material, mild conditions are used rather than using “supercritical water”. The emulsion is stable and can be emulsified, so that a microemulsion consisting of oil droplets containing a monomer having a finer and uniform particle size distribution can be obtained without decomposition of the poor heat resistant monomer. The production method of the present invention is the first example in which an emulsion of acrylic monomers is obtained under mild conditions at a temperature lower than 374 ° C., which is the critical point of water, and the particle coalescence occurring thereafter is effectively suppressed. It is. That is, in the technique of Patent Document 1 mentioned above, as described above, the oil is treated with supercritical water such as dodecane which is a saturated hydrocarbon, at 440 ° C. or higher, and this point is completely different. .

  The ability to lower the dissolution temperature of water and the monomer of the oil component is extremely important in order to obtain the microemulsion of monomers with poor heat resistance targeted by the present invention. That is, it is assumed that the microemulsion containing an oil-soluble monomer such as an acrylic monomer, which is the object of the present invention, as an oil component is polymerized by a series of operations to obtain fine and uniform polymer particles. If the monomers are thermally decomposed in the step of obtaining a microemulsion, polymer design can not be performed. The time for compatibilization of the monomer of the oil droplet raw material and water, which is carried out by the production method of the present invention, is from several seconds to ten seconds, which is extremely short. However, even in that case, it is expected that decomposition of the monomer will occur, and it is desirable to obtain a microemulsion under mild conditions as low as possible, while according to the production method of the present invention, under milder conditions, Fine and uniform microemulsion (oil droplets) containing monomers which could not be realized by the conventional production method can be obtained, and moreover, it can be effectively suppressed that the oil droplets become united in a short time, It is possible to maintain the state of the emulsion for a relatively long time. For this reason, when the microemulsion (oil droplets) is polymerized in a series of operations subsequent to this, it is possible to make it have a fine particle size. For this reason, it is expected to obtain polymer particles showing finer and uniform particle size distribution which could not be realized by the prior art by using the subcritical emulsification method of the present invention, and the development of its use is Be expected.

Claims (7)

A method for producing a microemulsion of a polymerizable monomer, wherein oil droplets composed of an oil component containing a polymerizable monomer are finely emulsified in water,
The polymerizable monomer is an acrylic monomer,
The AburaNaru component, said oil component by mixing with water in a subcritical state is dissolved in water, when then obtaining a quenched with the addition of emulsifier micro emulsion of the oil droplets, as the emulsifier A method for producing a microemulsion of a polymerizable monomer comprising using a nonionic emulsifier having a cloud point.   The method for producing a microemulsion of a polymerizable monomer according to claim 1, wherein the addition of the nonionic emulsifier having a cloud point is carried out under a temperature condition higher than the cloud point.   The method for producing a microemulsion of a polymerizable monomer according to claim 1, wherein the nonionic emulsifier having a cloud point comprises two or more nonionic emulsifiers having different cloud points. Manufacturing method for a micro emulsion of the polymerizable monomer according to any one of claims 1 to 3 SP value of 8.0 to 10.0 before Symbol oil component. The method for producing a microemulsion of a polymerizable monomer according to claim 4, wherein the acrylic monomer contains 0.1% by mass or more of an acrylic monomer having a carboxy group or a hydroxy group. A method of producing a microresin emulsion for obtaining an emulsion of microresin particles, which is a polymerizable single particle obtained by the method of producing a microemulsion of a polymerizable monomer according to any one of claims 1 to 5. A method for producing a microresin emulsion, comprising obtaining an emulsion of microresin particles by polymerizing a polymerizable monomer contained in the microemulsion from a microemulsion of a monomer. The method for producing a micro-resin emulsion according to claim 6 , wherein the polymerization is carried out at a temperature equal to or lower than the cloud point of the nonionic emulsifier.