JP2019210203A - Oil-in-water type emulsion, method for producing oil-in-water type emulsion, and method for forming coating film - Google Patents

Abstract

To provide a stable emulsion which, by providing a coating film, can efficiently display excellent characteristics inherent to fluorine-containing organopolysiloxane.SOLUTION: The oil-in-water type emulsion comprises composite particles having a configuration where an oil content is absorbed into a self-assembled micelle type aggregate having a space formed inside, where in each of the composite particles, self-assembled micelle type aggregates coat a surface of an oil droplet. The self-assembled type aggregates are formed by fumed silica particles formed by low order aggregates of fumed silica particles with each other through non-chemical bonds, where a total mole number ratio, given by (number of moles of surface hydrophilic group totaled over entire fumed silica particles)/(number of moles of surface hydrophobic group totaled over entire fumed silica particles) is in a predetermined numerical range.SELECTED DRAWING: Figure 1

Description

  TECHNICAL FIELD The present invention relates to an oil-in-water emulsion and a method for producing an oil-in-water emulsion, and more specifically, an oil-in-water emulsion having a fluorine-containing organopolysiloxane as an oil component and a method for producing an oil-in-water emulsion. And a method of forming a film for forming a predetermined film thickness.

Organopolysiloxane is known to have excellent properties such as stability, heat resistance, water resistance, oil resistance, water repellency, flexibility, and gas permeability, which are essentially derived from the chemical structure.
Among the above properties, fluorocarbons, in which hydrogen atoms of hydrocarbons are partially replaced with fluorine atoms, are organopolysiloxanes that have ordinary stability, heat resistance, water resistance, oil resistance, and water repellency, such as dimethylpolysiloxane. It is known to be even better than siloxane. Further, it is known that fluorocarbon has characteristic properties such as oil repellency, which are not found at all in ordinary organopolysiloxanes. However, although fluorocarbon has such excellent properties, its use as a material has been limited due to its too hard property and too dense property.
Therefore, by introducing a fluorocarbon structure into the skeleton of the organopolysiloxane, the characteristics of the fluorocarbon can be exhibited while maintaining the basic characteristics of the organopolysiloxane or without significantly damaging it.

For example, stability, heat resistance, water resistance, oil resistance, and water repellency can be improved while maintaining the flexibility of organopolysiloxane, so that it satisfies the required characteristics that cannot be achieved with organopolysiloxane alone. It becomes possible. In addition, while maintaining the flexibility of the organopolysiloxane, it is possible to obtain a property of oil repellency that cannot be exhibited at all by the organopolysiloxane. Furthermore, the problem of organopolysiloxane can be relatively solved. For example, bubbles generated by organopolysiloxane can be eliminated by organopolysiloxane introduced with fluorocarbon. In addition, the foam caused by the mineral oil can be eliminated by the organopolysiloxane introduced with fluorocarbon. Moreover, introduction of fluorocarbon makes it possible to harden the too soft physical properties of organopolysiloxane, to prevent the property of migrating from the resin, and the like.
Conversely, it can be understood that the introduction of organopolysiloxane relatively exceeds the characteristics of fluorocarbons that are too hard and too dense.
Hereinafter, an organopolysiloxane having a fluorocarbon introduced onto the skeleton is referred to as a fluorine-containing organopolysiloxane.

For the above reasons, fluorine-containing organopolysiloxanes are in various forms such as oil, rubber, and resin, and in various forms such as bulk, solution, dispersed liquid (or suspension), and film, Applications are expected to demonstrate their excellent properties for various applications.
As the fluorine-containing organopolysiloxane increases the content of the fluorocarbon, the degree to which the above characteristics are superior to that of a normal organopolysiloxane is exceeded. However, if the content is excessively increased, the softness of ordinary organopolysiloxane and the texture are sacrificed in the case of fiber treatment. Therefore, the amount of fluorine introduced usually has an upper limit. It was necessary to determine the fluorine content in balance with drawing out the desired characteristics.

  Already in the form of oil, it can be applied in bulk form as it is, and it has excellent stability, water resistance, and oil resistance, so water and oily stains in paints, mold release agents, fiber treatment agents, and leather surface treatment agents. It is used as a component to prevent the adhesion of It is also used as an excellent water repellent. Even in cosmetic applications, it is used for the purpose of making it difficult for cosmetic collapse to occur for aqueous and oily components such as sebum and sweat.

In order to maximize the characteristics of the fluorine-containing organopolysiloxane, it is necessary to use it as a coating mode. Because the properties such as excellent stability, heat resistance, water resistance, oil resistance, water repellency and oil repellency are on the base material from the viewpoint of protecting the base material, modifying it, and adding functionality to the base material surface. It is because it is necessary to form as a film.
However, it is extremely difficult to develop applications in the form of a film. The reason for this is that the fluorine-containing organopolysiloxane cannot be made into an aqueous solution or water dispersion due to the remarkable water repellency and oil repellency, and when the fluorocarbon content in the fluorine-containing organopolysiloxane is above a certain level, This is because the organic solvent solution or suspension cannot be formed because the solubility in water is not sufficient, so that a film cannot be formed by coating or the like, or the film forming property is not sufficient. Therefore, until now, the use of fluorine-containing organopolysiloxane has been remarkably limited. Or the development of the application was not progressing.

As described above, since the coating mode is the most suitable application mode, the intermediate stage of the fluorine-containing silicone is not limited as long as the final coating mode can be ensured. For example, it seems that a thin and uniform film can be formed by a method such as plasma CVD. However, a dispersion such as an emulsion is more advantageous as an intermediate stage due to device and cost constraints.
Furthermore, for environmental and health reasons, it is preferable to supply the product in an aqueous system. Furthermore, to add a fluorine-containing organopolysiloxane to an aqueous formulation such as an aqueous paint or cosmetic, an oil-in-water type There is a need as an emulsion form.
Since it is necessary to store in the form of an oil-in-water emulsion in order to apply in the form of coating, the stability of the oil-in-water emulsion at the beginning and over time is extremely important.

  However, it is difficult to add fluorine-containing silicone oil to aqueous formulations. Therefore, it is dissolved in organic solvents and blended into paints, etc. Recently, from the viewpoint of ensuring a safe working environment and environmental burden, it is required to change the dispersion medium from organic solvent to aqueous. There is an increasing demand for emulsion compositions. In addition, even in cosmetic applications, water-based prescriptions are demanded for a refreshing feel. Furthermore, fluorine-containing silicone oils are not compatible with most substances, and even organic solvents are not sufficiently compatible. Therefore, there are problems with stable product storage and application uniformity in various applications.

On the other hand, for example, Patent Documents 1 and 2 disclose a silicone emulsion having a structure containing a polyether group and having compatibility with an aqueous formulation. Patent Document 3 discloses a silicone emulsion having a hydrophilic property and a lipophilic property by having a carboxylic acid ester moiety and a polyether structure.
However, although having these modified sites in the structure allows it to be added to an aqueous formulation, there has been a problem that the water resistance and oil resistance inherent in fluorine-containing silicone cannot be expressed.

Pickering emulsions in which silicone oil and other silicone substances are emulsified with fumed silica particles are known. Such a pickering emulsion is an oil-in-water emulsion in which composite particles composed of oil droplets constituting the core and fumed silica particles present on the surface of the oil droplets that are the interface between the oil phase and the water phase are combined. It takes the form which exists in an emulsified state in an aqueous phase as a particle group.
By forming an emulsion without using an organic surfactant, these compounds eliminate the harmful effects of organic surfactants that are harmful to the environment, and provide silica as a functional agent in an aqueous system rather than as a particle. In view of the fact that it is possible, various applications such as pharmaceuticals, foodstuffs, and antifoaming agents are expected as oil-in-water emulsions.
However, the conventional pickering emulsion has the following technical problems.

  Patent Documents 4 to 6 disclose pickering emulsions in which oil is emulsified with fumed silica. However, these documents do not disclose specific parameters for exhibiting the stability of the pickering emulsion and specific methods for ensuring the stability. Further, in these documents, as a method for producing a pickering emulsion, it is described that the addition timing of the oil phase, the aqueous phase, and the fumed silica can be in any order. However, when the oil phase is added simultaneously with the aqueous phase, it is difficult to produce a pickering emulsion as long as the fluorine-containing organopolysiloxane has both water repellency and oil repellency.

In particular, Patent Document 5 discloses a pickering oil-in-water emulsion, an aqueous dispersion of fumed silica as a premise thereof, and mentions the balance between the hydrophilicity and hydrophobicity of fumed silica.
However, for the following reasons, from the viewpoint of exerting the surfactant function, only the balance between hydrophilicity and hydrophobicity, that is, hydrophilicity / hydrophobicity, is paid attention to. Pickering oil-in-water emulsion or water dispersion of silica From the viewpoint of body stability, we do not focus on hydrophilicity / hydrophobicity.
First, it has been pointed out that conventional surfactants have insufficient adhesion of oil components to the mold because the emulsion does not easily break when sprayed onto the mold. It is stated that the oil-in-water emulsion needs to be destroyed due to its special characteristics when used as a mold release agent, which ensures the stability of the pickering oil-in-water emulsion or silica aqueous dispersion. Is a retrograde.
Second, as a method for producing an oil-in-water emulsion, when silica particles that do not have a balance between hydrophilicity and hydrophobicity and do not have a surfactant function are used, a surfactant may be added together with silica. In the case of using silica particles in which the balance between hydrophilicity and hydrophobicity is used, only silica may be added, or an oil component may be added after forming an aqueous dispersion of silica. It is described that oil may be added simultaneously with water.

As described above, Patent Document 5 discloses an oil-in-water pickering emulsion composed of an aqueous phase, an oil phase, and silica particles based on such an aqueous dispersion. With respect to the above, it is described that the silica particles may be used together with the surfactant, and that the oil phase may be added simultaneously with the water phase and the silica particles and stirred, so that the stability of the pickering emulsion is ensured. However, it did not disclose specific parameters and a production method for the above, and did not indicate the possibility of a pickering emulsion containing a fluorine-containing organopolysiloxane as an oil.
For this reason, conventionally, there has been no idea for producing an emulsion of a fluorine-containing organopolysiloxane, and no studies have been conducted for that purpose.

In this regard, the applicant of the present application disclosed in Patent Document 7 that the lower aggregates of the inorganic particle group form high-order aggregates by non-chemical bonds and are dispersed in water, such as fumed silica particles. In water dispersions and oil-in-water pickering emulsions that add oils based on such water dispersions, find a mechanism of stability adjustment by exchange (rearrangement) or movement (orientation) at the aggregate level Yes.
More specifically, in the aqueous dispersion in which the lower aggregates of the inorganic particle group form high-order aggregates by non-chemical bonds and are dispersed in water, exchange at the aggregate level (rearrangement) ) Or migration (orientation) produces hydrophilic rich aggregates, hydrophobic rich aggregates, and intermediate aggregates (self-micellar aggregates), self-micellar aggregates, water dispersions, and such It has been discovered that it is important for the stability of an oil-in-water pickering emulsion in which oil is added based on an aqueous dispersion.
However, no investigation has been made as to whether or not an oil-in-water pickering emulsion containing a fluorine-containing organopolysiloxane having super water repellency or super oil repellency can be formed.
This is because it was not expected that an oil-in-water pickering emulsion using a fluorine-containing organopolysiloxane having super water repellency or super oil repellency as an oil could be formed. It is shown.

In addition, there was no attempt to apply fluorine-containing organopolysiloxane as a film formation on the substrate, but fluorine-containing organopolysiloxane was not dispersed at all in water, and even organic solvents were not sufficiently compatible For this reason, in the coating film, the setting and uniformity of the film thickness according to the purpose could not be obtained.
In addition, there is an environmental and safety problem because the product cannot be provided in water.

JP 2012-207078 A JP 2013-028745 A JP 2011-026498 A JP 2005-126722 A JP, 2006-121230, A JP2012-500766A Japanese Patent No. 6312234

In view of the above technical problems, the object of the present invention is to provide a shape of the film, thereby effectively exhibiting the original excellent properties of fluorine-containing organopolysiloxane, and an oil-in-water type containing a stable fluorine-containing silicone. It is to provide an emulsion and a method for producing the same.
In view of the above technical problems, an object of the present invention is to provide an oil-in-water emulsion that is stable even when a fluorine-based silicone having high water and oil repellency is used as an oil phase, and a method for producing the same.
In view of the above technical problems, the object of the present invention is to protect and modify the base material by utilizing a stable oil-in-water emulsion having a water- and oil-repellent fluorinated silicone as an oil phase. An object of the present invention is to provide a method for forming a coating film that can obtain a desired coating film thickness depending on the use by imparting functionality to the substrate surface.

  Therefore, none of the prior arts disclosed a specific method for obtaining a fluorine-containing silicone emulsion that solves the above problems, a method for producing the same, and a method for forming a film using the emulsion.

As a result of intensive studies to achieve the above object, the present inventors have determined that the number of moles of surface hydrophilic groups in each of the fumed silica particles group is the total number of moles over the fumed silica particle group / the surface hydrophobicity in each. By setting the total mole number ratio, which is the total mole number over the fumed silica particle group of the number of moles of the group, within a predetermined numerical range, a self-micellar aggregate is formed, and the fluorine-containing organolump which is an oil component therein It has been found that a stable oil-in-water emulsion is produced containing a composite particle population in the form of inhaled polysiloxane.
That is, regardless of the mass proportion of the amount of oil and the amount of fumed silica, when producing an aqueous dispersion of fumed silica and an aqueous phase, sufficient shear is applied to the produced aqueous dispersion. By adding oil droplets later, a stable emulsion is formed so as to be sucked into the produced aqueous dispersion even when fluorine-containing organopolysiloxane having high water and oil repellency is used as the oil phase. It is based on the discovery that overturns the conventional common sense.

  In addition, in order to obtain an oil-in-water emulsion (Pickering emulsion) by coating oil droplets with a self-micelle aqueous dispersion of fumed silica particles, a shear rate greater than a predetermined value mainly at the stage of the aqueous dispersion. By promoting the rearrangement of the primary aggregates between the secondary aggregates and / or the orientation of the primary aggregates in the secondary aggregates, the variation in the degree of hydrophobicity between the composite particles can be reduced. It was found that a more stable and uniform oil-in-water emulsion was produced.

The present invention has been made based on these findings.
That is, the emulsion of the present invention is a fumed silica particle group in which the lower aggregates of the fumed silica particle group form high-order aggregates by non-chemical bonds, and the number of moles of surface hydrophilic groups in each is Fumes at the secondary aggregation level, wherein the total number of moles over the fumed silica particle group / the total number of moles of the surface hydrophobic group in each mole ratio over the fumed silica particle group in the total number of moles over the fumed silica particle group is within a predetermined numerical range. A high-density portion of the hydrophilic-rich lower aggregate formed by the silica gel particles is in contact with the aqueous phase, and a high-density portion of the hydrophobic-rich lower aggregate is in contact with another hydrophobic-rich lower aggregate, A composite particle group in which oil is sucked into a self-micellar aggregate that forms a space therein, and the oil contains an organopode having an average composition represented by the general formula (1) Is a siloxane, in ^{_{R 1 a R 2 b SiO (}} 4-a-b) / 2 (1) [ Formula (1), ^{R 1} may be different even in the same in the molecule, substituted or An unsubstituted or saturated monovalent hydrocarbon group having 1 to 25 carbon atoms, a substituted or unsubstituted aromatic group having 6 to 30 carbon atoms, a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, or a hydrogen atom; R ² may be the same or different in the molecule, and is a saturated or unsaturated monovalent hydrocarbon group having 1 to 25 carbon atoms, or an aromatic group having 6 to 30 carbon atoms, and at least one carbon. The above hydrogen atom is a hydrocarbon group substituted with a fluorine atom, b is a positive number other than 0, and a + b is 0.3 or more and less than 2.5] Characterized in that the agglomerates cover the surface of the oil droplets Is a medium-oil-in-water emulsion.

That is, in the emulsion production method and the film formation method of the present invention, a hydrophobic rich silica raw material having a surface silanol group hydrophobized and a hydrophilic rich silica raw material having a surface silanol group remaining are mixed at a predetermined ratio. The total number of moles over the fumed silica particle group of the number of moles of surface hydrophilic groups in each of the fumed silica particle groups / the number of moles of surface hydrophobic groups in each of the fumed silica particle groups Preparing a fumed silica particle group having a secondary aggregation level so that the total mole ratio, which is the total mole number over the group, falls within a predetermined numerical range;
The prepared secondary agglomeration level fumed silica particles are added to water and sheared at a predetermined shear rate, thereby exchanging the secondary agglomeration level fumed silica particles at the primary agglomeration level and / or. By promoting the orientation at the primary flocculation level in the fumed silica particles at the secondary flocculation level, the high-density portion of the hydrophilic-rich lower aggregates by the fumed silica particles at the secondary flocculation level is Producing an aqueous dispersion comprising self-micellar aggregates that contact and form a space therein;
Forming an emulsion by adding oil into the resulting aqueous dispersion and allowing the oil to be sucked into the self-micellar agglomerates; and
The oil component is an organopolysiloxane having an average composition represented by the general formula (1),
R ¹ _a R ² _b SiO _{(4-ab) / 2} (1)
[In formula (1), R ¹ may be the same or different in the molecule, and is a substituted or unsubstituted C1-C25 saturated or unsaturated monovalent hydrocarbon group, substituted or unsubstituted. An aromatic group having 6 to 30 carbon atoms, a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, or a hydrogen atom, and R ² may be the same or different in the molecule, and may have 1 to 25 carbon atoms. A saturated or unsaturated monovalent hydrocarbon group, or an aromatic group having 6 to 30 carbon atoms, wherein a hydrogen atom on at least one carbon is substituted with a fluorine atom, and b is not 0 Positive number, a + b is 0.3 or more and less than 2.5], whereby composite particles in the form of oil contained in self-micellar aggregates formed by a group of fumed silica particles at the secondary aggregation level Oil-in-water emal characterized by containing groups Depending on the protection of the base material, the modification of the base material, and the addition of the function to the surface of the base material using the oil-in-water emulsion produced by the previous manufacturing method. A method for forming a film, comprising: forming a film having a predetermined film thickness on a surface of a substrate.

  The organopolysiloxane preferably does not contain a hydrophilic functional group.

  The emulsion of the present invention produces an aqueous dispersion containing stable self-micellar aggregates at the stage of preparation of the aqueous dispersion and forms an emulsion by sucking oil into the aggregates. It is possible to emulsify fluorine-containing organopolysiloxane having both water repellency and oil repellency that cannot be formed, and there are few restrictions on the ratio of the amount of oil to silica, and introduction of fluorocarbon into fluorine-containing organopolysiloxane A stable emulsion with few ratio constraints can be formed.

The emulsion of the present invention can apply a predetermined film thickness uniformly to the substrate by selecting the concentration of oil in the emulsion, the molecular weight of the oil, and the like, so that water repellency, oil repellency, heat resistance, weather resistance, antifouling As an improvement in properties of ordinary organopolysiloxanes in terms of properties, addition of functions, or improvement of functions, it is possible to form a coating for protecting, modifying, or adding functions to the surface of a substrate. Therefore, desired characteristics can be exhibited in various applications. Also, sufficient stability can be obtained for storage as an emulsion to form a coating.
However, in the ratio of the amount of oil and the amount of silica, and the ratio of substituents in the fluorine-containing organopolysiloxane, in the case of coatings for resin and rubber, after ensuring the stability of the emulsion, In order to make it possible to set the desired film thickness, the oil concentration in the emulsion is determined under each condition in the combination of the ratio between the amount of oil and the amount of silica and the ratio of substituents in the fluorine-containing organopolysiloxane. It is necessary to design the desired film thickness by selecting the molecular weight of the oil and other factors.

  Details of the oil-in-water emulsion containing the fluorine-containing organopolysiloxane of the present invention, a method for producing the same, and a method for forming a film using the emulsion of the present invention will be described below.

  The inventors have found that it is important for the stability of the emulsion to form an oil-in-water pickering emulsion by adding oil based on an aqueous dispersion in which fumed silica particles are dispersed in water. Based on the fact that the formation mechanism of the composite particle structure of fumed silica particles and oil in the pickering emulsion is unique due to the cohesiveness of the silica particles, the stability of the oil-in-water pickering emulsion only In addition, as a parameter for evaluating the stability of an aqueous dispersion in which fumed silica particles are dispersed in water, the so-called total mole ratio of surface hydrophilic groups and surface hydrophobic groups of fumed silica particles and variations in the total mole ratio By focusing on the above, it is possible to relax the restrictions on the choice of fumed silica particles and oil as the starting materials. Rutotomoni, compatibility between stability and properties of the aqueous dispersion according to the application is based on that it is possible to adjust the composite particle structure in the emulsion according to the application.

The fumed silica particles have a multi-dimensional aggregated structure. Therefore, the balance between the hydrophilic group and the hydrophobic group on the surface can be controlled according to the aggregation level, or the aggregation unit can be recombined. Therefore, in carrying out the present invention, the stability and uniformity of the aqueous dispersion can be controlled most effectively.
In addition, since the fumed silica particles have a porous structure, the surface area is increased, and the functions of association and adsorption are increased, so that an aqueous dispersion can be generated more stably and uniformly. In addition, since the functions of associating and adsorbing to various oils are increased, it is advantageous when transferring to a pickering emulsion.

In the fumed silica particles, the primary particles as the smallest unit are usually about 5 to 30 nanometers in size, and the primary particles aggregate to form primary aggregates, that is, secondary particles. . The size of the primary aggregate is usually about 100 to 400 nanometers. Since primary particles are fused by chemical bonds, it is usually difficult to separate primary aggregates. Further, the primary aggregates form an aggregated structure, which is referred to as secondary aggregate, that is, tertiary particles. The size of the secondary aggregate is about 10 μm. The aggregation form between the primary aggregates in the secondary aggregates is usually due to not a chemical bond but a hydrogen bond or other associative cohesive force. Therefore, if some external force is applied, it is possible to separate a part or all of the secondary aggregates up to the primary aggregate level. For example, a certain amount of shearing force is applied in water. The separated secondary aggregates are aggregated again as secondary aggregates when an external force is applied.
In the description of the present invention, the first and second agglomerates may be appropriately referred to as silica particle groups at the first and second agglomeration levels.
The fumed silica particles have the highest level of aggregation when the secondary aggregates are often in powder form. However, secondary aggregates can further aggregate in the water dispersion situation. The force for separating the agglomerates can be separated with a weaker force than the force for separating the secondary aggregates.
However, the aggregation level of the primary aggregate and the secondary aggregate is not always clearly formed. For example, the aggregation level in the middle stage between the primary aggregate and the secondary aggregate is also included. It may be distributed and mixed to some extent. Such a distribution including the width of the distribution is referred to as a primary aggregate and a secondary aggregate.
Incidentally, fumed silica particles are also known to take a network structure, particularly at the secondary aggregation level, which may be easy to use as inorganic particles for pickering emulsions.

  The state of the aqueous dispersion of fumed silica particles according to the present invention in water and the method for producing the aqueous dispersion will be described below. In the description, the use of the terms primary aggregation level and secondary aggregation level means that the level of aggregation is not 100% but only about the aggregation level.

Fumed silica particles use fumed silica that has a hydrophobic part on the surface and silanol groups, so that the surface tension of the fumed silica particles is set in the region necessary for surface activity. Even if no agent is present, it can be stabilized by being disposed at the oil phase / water phase interface of the oil droplets.
The ratio of silanol on the fumed silica surface remaining after silylation with respect to the silanol group before silylation is preferably in the range of 20 to 80%. When the residual ratio of silanol is less than 20% or exceeds 80%, the function corresponding to the surfactant at the oil phase / water phase interface cannot be exhibited. Silylation or silanol residue can be determined by measuring the carbon content by elemental analysis or by measuring the remaining amount of reactive silanol groups on the fumed silica surface. The silica particles used for the preparation may contain particles whose entire surface is silylated or particles whose entire surface is not silylated. However, it can be used if the overall silylation rate is within the above range and the necessary emulsifying function can be expressed.
The ratio of the residual silanol groups in the fumed silica particles does not need to be adjusted to the above value at the raw material stage. A method is also possible in which hydrophilic fumed silica and hydrophobic fumed silica are weighed as the total molar ratio and homogenization is attempted in the emulsion preparation stage.

The fumed silica particles used in the present invention must be in the form of particles, not a block. Moreover, the state of the primary aggregate which the primary particle aggregated, or the state of the secondary aggregate which further aggregated the primary aggregate may be sufficient. The particle size is not particularly limited, but in general, the particle size is preferably within the following range. The primary particle size is in the range of about 1 to 100 nm, the primary aggregate is in the range of about 50 nm to 1 μm, and the secondary aggregate is in the range of about 1 to 100 μm.
When the particle size is too small, it is difficult to obtain industrially, and when the particle size is too large, the fumed silica particles are easily settled.

FIG. 1 shows what aggregates can be formed when fumed silica particles are dispersed in water. In the present specification, for convenience, the terms hydrophilic rich aggregate, hydrophobic rich aggregate, and self-micellar aggregate are used. Self-micellar aggregates are a new concept found in the present invention. The relationship between these three types of aggregates is as follows.
When the molar ratio of the hydrophilic group / hydrophobic group on the surface of the fumed silica particles is rich in hydrophilic groups, the silica particles are easily dissolved in water because the silica particle surface and water are compatible with each other. In many cases, it does not agglomerate alone and is stably dissolved in water alone. The viscosity of the aqueous dispersion is low and the thixotropy is low. Such an aggregate will be referred to as a hydrophilic rich aggregate.
When the molar ratio of the hydrophilic group / hydrophobic group on the surface of the fumed silica particle is rich in hydrophobic groups, the silica particle surface and water are less compatible with each other. Since the particles are to be arranged, the silica particles tend to aggregate. Aggregates in which a large number of secondary aggregates 14 gather in water are formed. Therefore, the viscosity of the aqueous dispersion increases and the thixotropy increases. In this state, the stability of the aqueous dispersion is not good. The settling of silica particles tends to occur with time. Such aggregates will be referred to as hydrophobic rich aggregates. This state has already been used as a thickener or thixotropic agent as hydrophobic fumed silica. However, there is a restriction that the user must disperse the silica particles in water and immediately put it into the target material.
When the molar ratio of the hydrophilic group / hydrophobic group on the surface of the fumed silica particles is in a region between the hydrophilic rich aggregate and the hydrophobic rich aggregate, the primary aggregate having a relatively high hydrophilicity in the secondary aggregate 14. It is possible to form an aggregate in which the high density part of the aggregate 10 is in contact with the aqueous phase and the high density part of the primary aggregate 12 having a relatively high hydrophobicity is in contact with other secondary particles. Since it is an aggregated form similar to a normal surfactant self-micelle, it will be referred to as a self-micellar aggregate. In this state, the number of secondary aggregates 14 is limited to a small number, and the size of the aggregates is naturally uniform, so that a stable and uniform aqueous dispersion is obtained. Since the concentration of the hydrophilic group is high on the outside of the self-micellar aggregate, that is, the portion in contact with the aqueous phase, sufficiently high stability according to the hydrophilic rich aggregate can be obtained. It is much more stable than hydrophobic rich aggregates. Since there is a space 16 inside the self-micellar aggregate and it is a lipophilic environment, it is easy to take in the oil from the outside. The viscosity and thixotropy of self-micellar aggregates are intermediate properties between hydrophilic rich aggregates and hydrophobic rich aggregates. Surfactant self micelles are formed when the surfactant becomes surplus in relation to the oil to be emulsified, but in fumed silica particles, it depends on the concentration, regardless of the presence of oil. It is difficult to be affected and can be formed.

In the case of a surfactant, the surfactant interacts sufficiently with water molecules at a low concentration and dissolves in a single molecule or single ion state (monodispersed state). The concentration in the dispersed state becomes a saturated concentration, and subsequent surfactants associate to form supramolecules or self-organized bodies, which are so-called self-micelles. Self-micelles usually have an association structure with the hydrophilic part on the outside and the hydrophobic part on the inside.
Similarly, in the water dispersion state of silica at the secondary aggregation level, the present inventors similarly have self-micellar aggregates having an associated structure in which such a hydrophilic portion is on the outside and a hydrophobic portion is on the inside if the saturation concentration is exceeded. Note that is formed. However, the saturation concentration is considerably lower than that of the surfactant.

  These three types of aggregates are defined relative to each other as follows. Hydrophobic rich agglomerates are fumed silica particles that have a high level of agglomeration and exhibit high hydrophobicity as thixotropy compared to self-micelle aggregates and hydrophilic rich aggregates. Agglomerates of particles and hydrophilic rich aggregates are fumed silica particle aggregates that are hydrophobic enough to dissolve in water compared to self-micellar aggregates and hydrophobic rich aggregates, and the aggregation level is Low fumed silica particle mass, self-micellar agglomerates are aggregates of fumed silica particles that are more hydrophobic on the inside and more hydrophilic on the outside than hydrophobic rich and hydrophilic rich aggregates. It is expressed and is a mass of fumed silica particles located between hydrophobic-rich aggregates and hydrophilic-rich aggregates, with space inside and lipophilic, from the outside Minute is the incorporation structure which tends.

  In order to produce an aqueous dispersion of fumed silica particles, it is difficult to spontaneously dissolve or disperse the raw silica particles in water, regardless of the type of agglomerates. It is necessary to use a device that gives It can be produced using an ordinary mixer, for example, a homogenizer, a colloid mill, a homomixer, a high-speed stator rotor stirring device or the like.

  As a compounding quantity of the fumed silica particle in an aqueous dispersion, the range of 0.1-30.0 mass% is preferable with respect to the aqueous dispersion composition whole quantity, and it is more preferable that it is the range of 0.2-10 mass%. preferable. When the blending amount is less than 0.1% by mass, aggregation may not proceed. When the blending amount exceeds 30.0% by mass, the viscosity increases, and thus the proper range of the stirring device is exceeded.

The cohesive force between the primary aggregates of fumed silica particles is released when a specific shear force is applied, and agglomerates again when the shear is stopped. Accordingly, in the production of the aqueous dispersion, the primary aggregate can be exchanged between the separate secondary aggregates if a specific shear is applied. Thereby, the ratio of the hydrophilic-rich primary aggregate and the hydrophobic-rich primary aggregate in one secondary aggregate can be changed. The exchange of the primary aggregate between such secondary aggregates is referred to as rearrangement.
In order to cause rearrangement, it is preferable to apply a shear rate of 7500 s ⁻¹ or more. If the shear rate is less than 7500 s ⁻¹ , sufficient rearrangement will not occur. There is no upper limit of the shear rate for causing rearrangement, but if it exceeds 100,000 s ⁻¹ , troubles on the apparatus are likely to occur, and the water dispersion is heated to evaporate the moisture, In some cases, problems such as decomposition may occur, which is not preferable.
Sufficient rearrangement facilitates the exchange of primary aggregates between secondary aggregates, so the hydrophilicity in the secondary aggregates of fumed silica particles throughout the aqueous dispersion system. The ratio of rich primary aggregates to hydrophobic rich primary aggregates becomes more uniform.
In addition, when a shear rate sufficient to cause rearrangement is applied to the aggregate of silica particles, movement of the primary aggregate may occur in the same secondary aggregate, and the arrangement may be changed. . When self-micellar aggregates are formed, as shown in FIG. 1, the hydrophobic primary aggregates may be oriented in the direction of aggregation of the two particles.

As schematically shown in the above description and FIG. 1, the type of aggregate that is most easily generated varies depending on the degree of hydrophilicity / hydrophobicity of the fumed silica particles.
More specifically, the total number of moles over the number of moles of surface hydrophilic groups in each group of fumed silica particles / the number of moles of surface hydrophobic groups in each group of fumed silica particles. If the total mole ratio, which is the total number of moles across the group, is less than or equal to the predetermined lower limit, hydrophobic rich aggregates are mainly produced. And if a total molar ratio is more than a predetermined upper limit, a hydrophilic rich aggregate will mainly produce | generate. And if a total molar ratio is more than a predetermined minimum and below an upper limit, ie, a predetermined numerical range, a self-micellar aggregate will mainly produce | generate. The lower limit of the total molar ratio is approximately 20/80, and the upper limit is approximately 80/20.

In the present invention, it was unexpectedly discovered that the state of the fumed silica as a starting material is not restricted if a shearing force of a certain level or more is applied to cause rearrangement of the fumed silica particles. That is, in the raw material stage, the total number of moles over the number of moles of surface hydrophilic groups in each of the fumed silica particle groups over the number of fumed silica particle groups / the number of moles of surface hydrophobic groups in each of the fumed silica particle groups As long as the total mole ratio, which is the total mole number over the group, is set to 20/80 or more and / or 80/20 or less, the type of silica of the raw material is not limited. It may be hydrophilic silica particles in which silanol groups on the surface remain or hydrophobic silica particles in which silanol groups on the surface have been subjected to a hydrophobization treatment, and these may be arbitrarily mixed and used. Moreover, the fumed silica hydrophobized by arbitrary ratios may be sufficient. Commercially available fumed silica particles can be used. Alternatively, hydrophilic silica particles may be hydrophobized by a known method of treating with halogenated organosilicon such as methyltrichlorosilane, alkoxysilanes such as dimethyldialkoxysilane, silazane, or low molecular weight methylpolysiloxane. it can.
The above silica particles are preferably fine powder having a specific surface area of ^{2 to} 350 m ² / g in a dry state, and particularly preferably 50 to 300 m ² / g.
As the raw material, fumed silica particles of the type described above can be used, but in the raw material stage, the total number of moles per fumed silica particle group of the number of moles of surface hydrophilic groups in each fumed silica particle group / fumed silica particle group It is necessary to set the total mole number ratio, which is the total mole number over the fumed silica particle group of the number of moles of the surface hydrophobic group in each of the above, to 20/80 or more and / or 80/20 or less.

The pickering emulsion according to the present invention includes a composite particle group in which oil is sucked into a self-micelle aggregate formed by fumed silica particles of a secondary aggregate, and each composite particle group includes self-micelles. An oil-in-water emulsion in which the agglomerates coat the surface of the oil droplets. Since the inside of the self-micellar aggregate disclosed in Patent Document 7 is a lipophilic environment, it has been known that oils including ordinary organopolysiloxane are taken in. However, in the present invention, surprisingly, even in the formation stage of the pickering emulsion, even in the fluorine-containing organopolysiloxane having high water repellency and oil repellency, under conditions equivalent to those of ordinary organopolysiloxane such as shearing, It was found that the emulsion was stabilized by being sucked into the self-micellar aggregates formed in the aqueous dispersion formation stage.
The fact that self-micelle aggregates are stable in aqueous dispersions is also basically applicable to pickering emulsions. The oil droplets are coated with self-micellar aggregates to produce a pickering emulsion that is stable, uniform, and reproducible. The secondary aggregate of fumed silica is said to have a size of about 10 μm in a normal existence form. However, in the oil-in-water emulsion according to the present invention, a lump of spherical silica particles is coated, and one lump is often about 0.1 μm to several μm. Therefore, even if it is called a secondary aggregate, there is a possibility that a small part includes a primary aggregate and an aggregate in the middle stage from the primary to the secondary. Alternatively, it is considered that secondary aggregates are formed more densely than generally present.

The oil contained in the oil-in-water emulsion composition of the present invention is a fluorine-containing organopolysiloxane having an average composition formula represented by the general formula (1).
R ¹ _a R ² _b SiO _{(4-ab) / 2} (1)
[In formula (1), R ¹ may be the same or different in the molecule, and is a substituted or unsubstituted C1-C25 saturated or unsaturated monovalent hydrocarbon group, substituted or unsubstituted. An aromatic group having 6 to 30 carbon atoms, a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, or a hydrogen atom, and R ² may be the same or different in the molecule, and may have 1 to 25 carbon atoms. A saturated or unsaturated monovalent hydrocarbon group, or an aromatic group having 6 to 30 carbon atoms, wherein a hydrogen atom on at least one carbon is substituted with a fluorine atom, and b is not 0 A positive number, a + b is 0.3 or more and less than 2.5]
a and b are numerical values related to the order of the siloxane bond, and if a + b is 2.0, the organopolysiloxane represents a straight-chain siloxane. In the present invention, since a + b is 0.3 or more and less than 2.5, the organopolysiloxane may be in any form such as oil, rubber, resin, and curable composition.

Specifically, the organic group R ¹ is a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a t-butyl group, a pentyl group, a neopentyl group, a hexyl group, a 2-ethylhexyl group, or a heptyl group. Group, octyl group, nonyl group, decyl group, dodecyl group and other alkyl groups; cyclopentyl group, cyclohexyl group, cycloheptyl group and other cycloalkyl groups; phenyl group, tolyl group, xylyl group, biphenyl group, naphthyl group and other aryl groups group; a benzyl group, phenylethyl group, phenylpropyl group, an aralkyl group such as a methyl benzyl _{group; -CH 2 -CH 2 -CH 2 -N} 2, -CH 2 -CH 2 -CH 2 -NH (CH 3), _{-CH 2 -CH 2 -CH 2 -N (} CH 3) 2, -CH 2 -CH 2 -NH-CH 2 -CH 2 -NH 2 _{, -CH 2 -CH 2 -CH 2 -NH} (CH 3), - CH 2 -CH 2 -CH 2 -NH-CH 2 -CH 2 -NH 2, -CH 2 -CH 2 -CH 2 -NH- _{CH 2 -CH 2 -N (CH 3} ) 2, -CH 2 -CH 2 -CH 2 -NH-CH 2 -CH 2 -NH (CH 2 CH 3), - CH 2 -CH 2 -CH 2 -NH A nitrogen-containing hydrocarbon represented by —CH ₂ —CH ₂ —N (CH ₂ CH ₃ ) ₂ , —CH ₂ —CH ₂ —CH ₂ —NH—CH ₂ —CH ₂ —NH (cyclo-C ₆ H ₁₁ ) Group: a chloromethyl group, a 2-bromoethyl group, a 3,3,3-trifluoropropyl group, a 3-chloropropyl group in which part or all of the hydrogen atoms in the hydrocarbon group are substituted by a halogen atom, a cyano group or the like , Chlorophenyl group, dibromo Examples thereof include substituted hydrocarbon groups such as an phenyl group, a tetrachlorophenyl group, a difluorophenyl group, a β-cyanoethyl group, a γ-cyanopropyl group, and a β-cyanopropyl group.
Particularly preferred organic groups are a methyl group and a phenyl group.
In addition, a substituent that causes a curing reaction, for example, an unsaturated hydrocarbon group such as a vinyl group or an allyl group, hydrogen bonded to a silicon atom, or the like may be contained.

The organic group R ² is a saturated or unsaturated monovalent hydrocarbon group having 1 to 25 carbon atoms or an aromatic group having 6 to 30 carbon atoms, and specifically, the saturated or unsaturated group exemplified as R ^1. In the saturated monovalent hydrocarbon group or aromatic group, an organic group in which a hydrogen atom on at least one carbon is substituted with a fluorine atom.

The molar number a per silicon atom 1 mol organic group R ¹ in the organopolysiloxane, moles b of silicon atoms per mole of the organic radical R ² is, b is a positive number not 0, a + b is 0. If it is 3 or more and less than 2.5, it will not be limited.
a + b is preferably 0.8 or more and less than 2.2. If the ratio is less than 0.8, the ratio of the tetrafunctional resin will increase, making it difficult to produce an emulsion because it is solid, and if it is 2.2 or more, the silane component will increase and the volatility will increase, making it difficult to apply to various applications. is there.
The ratio of the organic group R ^{1 and the} organic group R ² , that is, a / b is not limited, but is preferably 5/95 or more and less than 95/5. When the ratio is less than 5/95, the properties as a normal organopolysiloxane, such as flexibility, are not sufficiently exhibited. When the ratio is 95/5 or more, the content of fluorine-containing organic groups is small. This is because the characteristics cannot be sufficiently extracted.

The organopolysiloxane may be a fluorine-containing organopolysiloxane that satisfies the above conditions, and its chemical structure, molecular weight, or characteristics are not limited. Moreover, the form may be any form such as liquid, solid, flakes, and powder.
Moreover, either a single component or a mixture of two or more components may be used.

It is preferable that neither the organic group R ¹ nor the organic group R ² contains a hydrophilic substituent such as a hydroxyl group, a carboxyl group, an amino group, or an alkoxy group. This is because, in the intended use, the water repellency and water resistance inherent to the fluorine-containing organopolysiloxane are sacrificed.

  The organopolysiloxane is preferably fluidized after being homogenized as a whole. Since the organopolysiloxane is mainly a solid resin or the like, if the emulsification is difficult as it is, the organopolysiloxane is given fluidity and can be emulsified with fumed silica particles. The homogenization method is not limited, but is performed by mixing in a normal apparatus or other methods. The degree of fluidity is not particularly limited, but the viscosity after homogenization of the whole organopolysiloxane is preferably lower. The upper limit of the viscosity is approximately 100,000 mPa · s although it varies depending on the apparatus used.

When the main component as the organopolysiloxane is a resin having low fluidity, it is preferable to contain an organopolysiloxane or fluorine-containing silicone oil having a relatively low viscosity. Thereby, fluidization occurs after the entire organopolysiloxane is homogenized. The viscosity at 25 ° C. is preferably 1 to 2,000,000 mPa · s. More preferably, it is 1-100,000 mPa * s, Most preferably, it exists in the range of 1-50000 mPa * s. When it is less than 1 mPa · s, and when it exceeds 2000000 mPa · s, emulsification is difficult and a stable aqueous dispersion cannot be obtained. The proportion of low-viscosity organopolysiloxane in the organopolysiloxane is not limited, but if it is too large, the proportion of fluorine-containing silicone may decrease in the final use such as cosmetics, and the desired characteristics may not be sufficient. There is.
The structure of such a component may be anything as long as it is within the above conditions, but dimethylpolysiloxane is preferred from the viewpoint of availability, economic efficiency, and chemical stability. For example, liquid linear or cyclic dimethylpolysiloxane is exemplified.

  The preferable content of the organopolysiloxane in 100 parts by mass of the emulsion is in the range of 20 to 80 parts by mass. If the amount is less than 20 parts by mass, sufficient emulsification accuracy cannot be obtained, and the yield also decreases. If the amount exceeds 80 parts by mass, the viscosity of the aqueous emulsion increases and the handleability deteriorates. More preferably, it exists in the range of 30-70 mass parts.

In the individual composite particles present in the oil-in-water emulsion according to the invention, self-micelle aggregates of fumed silica particles coat the oil droplets. In that case, it may have coat | covered with the layer of each secondary aggregate, and may form the several layer of secondary aggregate. Alternatively, there may be a portion that is not partially covered with fumed silica particles.
A part of the secondary aggregate in contact with the oil droplet is embedded in the oil droplet. The degree of embedding varies depending on the degree of polarity of the oil component and the molar ratio between the hydrophilic group and the hydrophobic group on the surface of the fumed silica secondary aggregate. When the polarity of the oil droplet is close to that of the secondary aggregate, for example, when the silicone is an oil droplet, when the polarity of the surface of the secondary particle is close to that of silicone, the degree of embedding becomes large because of the high affinity. . Conversely, when the polarity difference is large, the degree of embedding is small.
In order for the pickering emulsion to exist stably, it is said that it is important to take an optimum value for the contact angle determined by the three of inorganic particles, oil droplets and water. In the oil-in-water emulsion of the present invention, the degree to which the secondary aggregates of fumed silica particles are embedded in the oil droplets is mainly determined by the above mechanism, but in the process of completing the emulsion, 2 The primary aggregates in the secondary aggregates move, and primary particles with high hydrophobicity are oriented in the direction of the oil droplets, which may cause a polarity gradient in the secondary particles. Since the emulsion exists most stably, an optimum contact angle may be obtained by determining the degree of embedding by adjusting the degree of inclination described above by itself.
Further, the secondary aggregate can move under an appropriate shearing force even after the emulsion is formed. It is possible to move the surface of the oil droplets to obtain a uniform interval, and to make the state of lamination uniform. Furthermore, a part can go back and forth between other composite particles.

The coating of oil droplets with secondary agglomerates of fumed silica particles includes a partial coating in addition to a full coating. The index indicating the degree of coating may be the result of observing the thickness or morphology of the silica layer. However, by taking up the amount of coating this time, the characteristics can be controlled as a more practical degree of coating. The characteristics refer to characteristics (e.g., stability) as an emulsion, and characteristics such as film homogeneity when used after forming a film.
The amount of the silica particle coating layer on the surface can be parameterized as the weight of fumed silica particles per unit area of the surface of the oil droplet.
In the present invention, the amount of the silica coating layer can be controlled by the treatment amount of the silica particles with respect to the surface area calculated from the particle size of the composite particles. This amount is preferably in the range of 2.0 × 10 ^{−9 to} 3.2 × 10 ⁻⁶ kg / m ² . If it is less than 2.0 × 10 ⁻⁹ kg / m ² , blocking of the composite particles in water or after film formation occurs, and if it exceeds 3.2 × 10 ⁻⁶ kg / m ² , for reasons such as excess silica, Undesirable phenomena for specific applications, such as embrittlement of the protective film, and contamination by excess silica in the emulsion or after the formation of the film, etc.

The particle size of the individual composite particles present in the oil-in-water emulsion according to the invention is influenced by the mass ratio of fumed silica particles to the total amount of oil. The higher the ratio, the smaller the particle size. However, within the preferable range of the silica coating layer described above, the particle size is approximately 10 μm regardless of the type of oil. Although it is larger than the particle size of the emulsion emulsified with a normal organic surfactant, it is stable and uniform at this particle size, and when applied to various applications, it is generally about 100 μm or less as a pickering emulsion. A diameter is suitable. When the particle diameter exceeds 100 μm, the stability of the emulsion is decreased, and when the composite particles are used in the form of a film, for example, in cosmetic applications, the size of the powder becomes an area where the tactile sensation is felt. Is not preferable.
The variation in the particle size of the composite particles present in the oil-in-water emulsion according to the present invention is small. This is because the surface of the oil droplet is covered with self-micelle aggregates of fumed silica particles. Since the self-micellar agglomerates of the water dispersion are uniform, the action on the oil droplets is uniformed, so that the variation in particle size is reduced.

The oil-in-water emulsion according to the present invention can be produced by using a stirrer similar to the apparatus used for producing an aqueous dispersion of fumed silica particles.
In order to coat the surface of the oil droplets with the self-micellar aggregates of fumed silica particles, in order, first, the self-micellar aggregates of fumed silica particles are formed, and then the oil is added. There is a need. This is because, when the oil is first added, a self-micellar aggregate of fumed silica particles is not formed, so that an oil-in-water emulsion that is the target pickering emulsion cannot be formed.
Therefore, in the production method, as a first step, the total number of moles over the fumed silica particle group of the number of moles of surface hydrophilic groups in each of the fumed silica particle groups / the mole of surface hydrophobic groups in each of the fumed silica particle groups. A secondary aggregation level fumed silica particle group is prepared so that the total mole number ratio, which is the total number of moles over a number of fumed silica particle groups, falls within a predetermined numerical range. In order to make the total molar ratio within the predetermined value range, the molar ratio is adjusted with the raw material fumed silica as in the method for producing the self-micellar aggregate of the aqueous dispersion.
Next, as a second stage, the prepared secondary agglomerated level fumed silica particles are added to water and sheared at a predetermined shear rate, thereby causing primary agglomeration between the secondary agglomerated level fumed silica particles. Exchange at the level and / or the orientation at the primary aggregation level in the fumed silica particles at the secondary aggregation level, thereby promoting the average value of the total mole ratio and the secondary particles constituting the fumed silica particle group Water containing self-micellar aggregates of fumed silica particles at the secondary aggregation level so that the difference between the molar ratio of the number of moles of surface hydrophilic groups / the number of moles of surface hydrophobic groups in each of the particles is less than a predetermined value Create a dispersion. In order to cause rearrangement, it is preferable to apply a shear rate of 7500 s ⁻¹ or more.
Next, as a third stage, an oil is added to the produced aqueous dispersion to form an emulsion. At this time, an appropriate shear rate is applied in the stirring device, and it takes time to apply shear appropriately so that the self-micellar aggregates uniformly cover the surface of the oil droplets and uniformly form a structure as composite particles. The shear rate is not required to be 7500 s ⁻¹ or more at which rearrangement occurs, and usually about several thousand s ⁻¹ is sufficient.

As described above, in the present invention, a self-micellar aggregate that forms a space inside is prepared at the stage of preparing the aqueous dispersion of fumed silica, and then fluorine that is an oil component in the space inside the self-micellar aggregate is formed. A stable pickering emulsion can be formed by sucking the organopolysiloxane. This makes it possible to obtain a stable emulsion of fluorine-containing organopolysiloxane, which could not form an emulsion at all according to the conventional concept. Moreover, sufficient stability of the initial stage and time-lapse | temporality as an emulsion for forming a film with respect to a base material can be acquired.
In this regard, it is considered that a mechanism that cannot be explained by the conventional idea that fluorine-containing organopolysiloxane (oil) is not taken into the self-micellar aggregate, which is an oleophilic environment. Fluorine-containing organopolysiloxane (oil) is adsorbed inside the self-micellar agglomerates, such as physical adsorption. Estimated to be sucked into.

  The total number of moles over the fumed silica particle group in the number of moles of surface hydrophilic groups in each of the fumed silica particle groups / the total number of moles over the fumed silica particle group in the number of moles of surface hydrophobic groups in each of the fumed silica particle groups. It is important for making a stable and uniform pickering emulsion that self-micellar aggregates are formed centrally by setting a certain mole ratio within a predetermined range. The state of self-micellar aggregates (for example, the degree of embedding of secondary aggregates in the oil droplets at the interface) in individual composite particles in which self-micellar aggregates are coated on the oil droplet surface is as uniform as possible. It is preferable. If the variation is small, the cooperation between the self-micelle aggregates becomes stronger, and the composite particles tend to be more stable. This stabilizes the entire composite particle group, and also reduces the variation in state between individual composite particles.

In order to reduce the dispersion | variation between secondary aggregates, it is made | formed by the 2nd step in said manufacturing method. The small variation in the degree of hydrophobicity (hydrophilicity) between the secondary aggregates also reduces the variation in the degree of embedding of the secondary aggregates in contact with the oil droplets in each self micelle aggregate. The variation in the degree of hydrophobicity (hydrophilicity) for each secondary aggregate is stable if it is within 60% of the positive mass relative to the average value of the variation in the degree of hydrophobicity (hydrophilicity) of all secondary aggregates. An oil-in-water emulsion is formed.
In order to reduce the variation between the secondary aggregates, particles having a hydrophilic group hydrophobized at a specific hydrophobization rate are used as the raw fumed silica particles without causing rearrangement by applying shear. It can be achieved even if it is used. However, this method is expensive to manufacture. Even without using such special silica particles, commercially available and inexpensive hydrophilic fumed silica particles and hydrophobic fumed silica particles are used as raw materials, and the mass ratio is adjusted so as to achieve a predetermined total molar ratio. This is because it can be produced by a simple method.

Even if the variation in the degree of hydrophobicity (hydrophilicity) of the secondary aggregate is not significantly reduced, it is possible to reduce the variation in the state of the composite particles by promoting the orientation at the primary aggregation level in the fumed silica particles at the secondary aggregation level. It can also be reduced. As the orientation progresses, the concentration of the hydrophobic group increases in the vicinity of the portion in contact with the oil droplet interface in the secondary aggregate, and conversely, the concentration of the hydrophilic group increases in the vicinity of the portion in contact with the aqueous phase. This is because both the affinity with the water phase can be efficiently performed.
When the variation in the degree of hydrophobicity (hydrophilicity) of the secondary aggregate is reduced and the orientation at the primary aggregation level in the fumed silica particles at the secondary aggregation level is advanced, a synergistic effect is exhibited, More stable and uniform composite particles can be produced.

  In terms of the variation among the composite particles, it is also important to set the mass ratio of the fumed silica particles and the oil content. As described above, the coating thickness of the silica particles on the surface of the oil droplets should be as small as possible among the composite particles. For this purpose, the mass of the silica particles is preferably set in the above-described range of the stable coating amount with respect to the mass of the oil component.

From the above, the oil-in-water emulsion of the present invention is different from the pickering emulsions disclosed in Patent Documents 4 to 7 in the prior art, and is premised on the importance of shearing in the formation stage of the aqueous dispersion from the viewpoint of ensuring the stability of the emulsion. However, since fluorine-containing organopolysiloxane is water- and oil-repellent, conventional fluorine-containing organopolysiloxane (oil) may not be taken into the lipophilic self-micelle aggregate. Fluorine-containing organopolysiloxane can also be emulsified by completely overturning the common technical knowledge of those skilled in the art and allowing oil to be sucked into the self-micellar dispersion. Furthermore, it is possible to produce a stable emulsion over a wide range without restricting the ratio of the amount of oil to silica.
Moreover, the surprising result that the introduction | transduction rate of the fluorocarbon in fluorine-containing organopolysiloxane, ie, ratio a / b in the above-mentioned formula (2), can produce a stable emulsion in a very wide range was also obtained. . Among various applications, for example, in applications that impart water repellency to the substrate surface, it is sufficient that the structure of the fluorocarbon is aggregated only on the extreme surface. It is necessary to increase the amount of introduction. According to the present invention, an emulsion capable of forming a stable film for various different uses can be prepared.

In the preparation of the emulsion of the present invention, if the oil used in the present invention does not have sufficient fluidity, more preferably an organopolysiloxane or a fluorine-containing organopolysiloxane having a viscosity of 1 to 2,000,000 mPa · s at 25 ° C. It is preferable that the whole oil component is fluidized by homogenization and then the oil component is dispersed in water with fumed silica particles. As a result, when it is difficult to emulsify the oil component such as a solid resin or an elastomer, the emulsification can be performed by bringing the whole into fluidity by contacting with the fluorine-containing organopolysiloxane. Therefore, fluorine-containing organopolysiloxane that has been difficult to emulsify can also exist in an emulsion state, and the problem can be effectively solved.
Further, as a more preferable production method, a powder solid obtained by fluidizing with a polyorganosiloxane or the like is added to an aqueous dispersion of fumed silica particles and subjected to mechanical shearing to obtain the emulsion. . In this case, as long as the powdered solid dissolved by organopolysiloxane or the like can be charged into the dispersion of fumed silica particles and fumed silica particles in water, the dispersion process of fumed silica particles and water, and the powder solids Either of the fluidizing steps using organopolysiloxane or the like may be performed first.

The emulsion of the present invention includes polyoxyalkylene alkyl ethers such as polyoxyethylene tridecyl ether, polyoxyethylene hexadecyl ether, polyoxyethylene octadecyl ether, and polyoxyethylene hydrogenated castor oil as long as the object of the present invention is not impaired. In addition, nonionic surfactants such as polyoxyethylene sorbitanate, and ionic surfactants such as sodium lauroylglutamate Na dilauroylglutamate lysine can be contained.
The amount of the surfactant is preferably 0.1 parts by mass or less, more preferably 0.06 parts by mass or less, in 100 parts by mass of the emulsion. If the amount exceeds 1 part by mass, the environment will be adversely affected and the cohesive strength of the fumed silica particles will be reduced, impairing the storage stability of the product and the handleability during dilution.

  The fluorine-containing silicone emulsion of the present invention is not particularly limited, but it is preferable to use ion-exchanged water, preferably pH 2 to 12, more preferably pH 4 to 10.

  The particle size of the emulsion particles of the fluorine-containing organopolysiloxane emulsion of the present invention is not particularly limited, but is preferably 100 μm or less. When the particle diameter exceeds 100 μm, the particle size is excessive, and the stability of the emulsion particles is impaired. In the present invention, the average particle size can be measured by a particle size distribution measuring device N4Plus manufactured by Coulter.

  As described above, the fluorine-containing organopolysiloxane emulsion of the present invention can stably control the particle size by the fluorine-containing organopolysiloxane and the fumed silica particles and its production method, and can narrow the variation in the particle size. As a result, storage stability and stability during application development are increased. Moreover, even when the emulsion particles are isolated, there is a possibility of giving high characteristics derived from the shape of the emulsion particles.

The fluorine-containing organopolysiloxane emulsion according to the present invention can be easily coated on various substrates by various coating techniques to form a film. That is, the oil-in-water emulsion can be used to protect the substrate, modify the substrate, or impart a function to the surface of the substrate. Although the thickness of the coating film depends on the type and purpose of the substrate, a desired coating film of any thickness can be formed from nanometer order to millimeter order. Since it is via an emulsion, the coating thickness uniformity is also good. Since it is supplied in an aqueous system, it can be applied not only to industrial base materials but also to human bodies and other base materials that are not suitable for application of organic solvents. Moreover, even if the surface shape is uneven, curved or irregular, it can be coated.
The emulsion according to the present invention may be coated as it is, diluted with water, or may be coated after mixing with another drug or composition.

Since the fluorine-containing organopolysiloxane emulsion according to the present invention can form a film on various substrates, the surface tension, which is an essential property of the fluorine-containing organopolysiloxane, is small, and the intermolecular force is small. High heat resistance, high insulation, high dielectric constant, etc., coupled with the state of the coating, water repellency, oil repellency, heat resistance, cosmetic performance, antifouling, weather resistance, release, long-term stability, insulation or high Since performance such as a dielectric constant can be exhibited, it is possible to protect the substrate, modify the substrate, or provide functionality to the surface of the substrate.
In this case, the fluorine-containing organopolysiloxane emulsion can be used in any form such as oil, rubber or resin. The curable composition may be coated to form a film and then cured.

Using the oil-in-water emulsion produced according to the present invention, a coating with a predetermined film thickness set according to any of protection of the substrate, modification of the substrate and imparting a function to the surface of the substrate is applied to the substrate. By taking the step of forming on the surface, desired properties can be obtained in various applications.
That is, it becomes possible to obtain characteristics and new applications that could not be obtained by conventional fluorine-containing silicone solutions of organic solvents or oil-like coating.

An example of setting the film thickness when the fluorine-containing organopolysiloxane emulsion according to the present invention is applied to the use for protecting a substrate will be described.
As the substrate, transparent or opaque substrates such as glass, plastic, resin, metal, alloy, cement, paper, ceramic inorganic material, concrete, mortar, wood, paper products, rubber, electronic parts, food packaging agents, Alternatively, there may be mentioned painted surfaces of exteriors such as automobiles, trains, airplanes, ships, etc., interior-related substrates such as floors and carpets, human skin and bio-related substrates. In the case where such a substrate deteriorates due to moisture, heat, light, etc. due to the environment or other causes, a protective coating agent such as various protective coating agents can be obtained by forming a film of the fluorine-containing organopolysiloxane emulsion according to the present invention on these substrates. It can be applied to the protection of substrates for cosmetics.
In this case, if the film has no dirt, is easy to remove dirt, does not have fingerprints, has water repellency and oil repellency, various antifouling coating agents, such as water resistance, oil resistance, moisture resistance, corrosion prevention, If it has chemical resistance and waterproofness, it can be applied as various building material protective materials and as a makeup agent if the skin is protected from ultraviolet rays. These are merely examples, and possible uses are not limited to these. In any application, the protection of the substrate can be stably maintained.
For the purpose of protecting the substrate, it is necessary to coat the fluorine-containing organopolysiloxane emulsion film as uniformly as possible on the surface of the substrate as much as possible. If the coating film is defective or has a thin portion that does not perform the protective function, the desired protective effect may not be obtained. Since the fluorine-containing organopolysiloxane emulsion of the present invention has no restrictions on the oil content and the oil viscosity, these elements can be optimized to design a desired film thickness. Further, when the surface of the substrate is not flat, it is necessary to fill the gap. Therefore, it is preferable to select an optimum application method among coating, dipping, scanning and the like according to the purpose.

An example of setting the film thickness when the fluorine-containing organopolysiloxane emulsion according to the present invention is applied to the modification of a substrate will be described.
The base material is basically the same as the type of base material in the protective application. In this case, it is used as a modifier that improves the water repellency, heat resistance, etc. that the substrate originally has, or a modifier that further increases the insulation and dielectric constant of the substrate. Application to various electronic components is possible. These are merely examples, and possible uses are not limited to these. In any application, the reforming characteristics can be stably maintained.
For the purpose of modifying the substrate, it is necessary to set the film thickness of the fluorine-containing organopolysiloxane emulsion according to the purpose. Since the fluorine-containing organopolysiloxane emulsion of the present invention has no restrictions on the oil content and the oil viscosity, these elements can be optimized to design a desired film thickness. Further, when the surface of the substrate is not flat, it is necessary to fill the gap. Therefore, it is preferable to select an optimum application method among coating, dipping, scanning and the like according to the purpose.

An example of setting the film thickness in the case where the fluorine-containing organopolysiloxane emulsion according to the present invention is applied to the application of a function to the substrate surface will be described.
The base material is basically the same as the type of base material in the protective application. In this case, if the base material originally does not have oil repellency, it can be used as various make-up agents if it has oil repellency, or it does not easily permeate sebum, it does not easily permeate sweat. If it has oil resistance and heat resistance, it can be applied as a release agent if it has the property of repelling resin as a paint and not adhering after curing. These are merely examples, and possible uses are not limited to these. In any application, the characteristics can be maintained stably.
For the purpose of imparting a function to the surface of the substrate, it is necessary to set the film thickness of the fluorine-containing organopolysiloxane emulsion according to the purpose. Since the fluorine-containing organopolysiloxane emulsion of the present invention has no restrictions on the oil content and the oil viscosity, these elements can be optimized to design a desired film thickness. When applying a fluorine-containing organopolysiloxane emulsion alone to a base material, the optimization of the above-mentioned elements is central. However, when applying a fluorine-containing organopolysiloxane emulsion to paints and cosmetics, After grasping the relationship between the solid content concentration and viscosity of the liquid mixture and the film thickness, the conditions according to the purpose are optimized. Further, when the surface of the substrate is not flat, it is necessary to fill the gap. Therefore, it is preferable to select an optimum application method among coating, dipping, scanning and the like according to the purpose.

  In any case, in the setting of the film thickness, the ratio of the amount of oil and the amount of silica and the ratio of substituents in the fluorine-containing organopolysiloxane are used for coatings for resins and rubbers. In this case, in order to ensure the desired film thickness while ensuring the stability of the emulsion, a combination of the ratio between the amount of oil and the amount of silica and the ratio of substituents in the fluorine-containing organopolysiloxane is one of the combinations. Under each condition, it is necessary to design a desired film thickness by selecting the concentration of oil in the emulsion, the molecular weight of the oil, and the like.

  When the fluorine-containing organopolysiloxane emulsion according to the present invention forms a coating on various substrates, in most cases fumed silica particles remain in the coating. In this case, for example, in the case of application to an antifouling coating agent, viscoelasticity is expressed due to the presence of silica. Can improve makeup prevention and smoothness, and in the case of paint, the heat resistance and toughness of the coating are improved. In many cases, the properties are improved by the presence of silica, such as the ability to increase sustainability.

  When the film is cured, the cured protective film can be formed by curing at room temperature or by heating. This cured protective film has high hardness and high flexibility, has good water repellency, heat resistance, weather resistance, scratch resistance and antifouling properties, and has adhesiveness.

  Moreover, the fluorine-containing organopolysiloxane emulsion composition according to the present invention can provide excellent antifoaming performance as various antifoaming agents. The composition can be applied to the antifoaming scene as it is, diluted, or mixed with another drug. This is because the excellent low surface tension inherent in the fluorine-containing organopolysiloxane can be exhibited. Moreover, the defoaming sustainability outstanding from the stability can also be exhibited.

  The fluorine-containing organopolysiloxane emulsion according to the present invention can be used as it is in water-based paints, antifoaming agents, cosmetics and the like, so that it can be used without special consideration in terms of environment and work.

  Next, the present invention will be described by way of examples. In addition, this invention is not limited by this. The contents of the fumed silica used in the examples are as follows, and the evaluation method for the composition in the oil-in-water emulsion of the fumed silica particles of the present invention and the comparative example was performed as follows. .

<Contents of fumed silica>
The silica used in the examples and comparative examples of the present invention is silica 1 to 3 shown in Table 1, and all are fumed silica (dry silica). The contents are as shown in Table 1.

<Particle size measurement method>
The particle size of the oil-in-water emulsion particles obtained in Examples and Comparative Examples was measured using a laser diffraction scattering particle size distribution measuring device (trade name “LS-230”) manufactured by Beckman Coulter, and the average particle size was measured. showed that.

<Stability and uniformity evaluation method>
In the method for evaluating the stability of the oil-in-water emulsions obtained in Examples and Comparative Examples, 30 g of a sample was put in a 50 ml screw tube, and the presence or absence of sedimentation separation was confirmed after one month of storage at room temperature. The emulsion was also checked for the presence of creaming. In addition, it was confirmed by visual inspection whether there was any large particulate matter or whether the side had turbidity, and the uniformity was confirmed.
Evaluation criteria;
◎: No creaming or sedimentation separation, uniform, ○: Slight creaming, sedimentation separation, very slightly non-uniformity, △: Creaming, sedimentation separation, non-uniform tendency, ×: Creaming, sedimentation separation ,Unevenness.

<Water repellency evaluation method>
On the glass plate, the oil-in-water emulsions obtained in Examples and Comparative Examples were diluted twice with water and applied using a bar coater to form a coating film having a thickness of about 30 μm, and air-dried sufficiently. After that, contact angle measurement with water was performed as a water repellency evaluation. If the contact angle is 90 degrees or more, the water repellency is good.

<Methods for producing water dispersions and oil-in-water emulsions in Examples and Comparative Examples>
In each Example and Comparative Example, an aqueous dispersion was obtained with the formulation amount and production conditions shown in Table 2. Further, an oil-in-water emulsion was prepared via the water dispersion according to the prescribed amount shown in the same table.
The evaluation results of the oil-in-water emulsion are shown in Table 3.

As a first step, 2.5 g of hydrophilic fumed silica (“Silica 1”) and 2.5 g of hydrophobic fumed silica (“Silica 2”) were charged into a 500 mL stainless steel beaker. The deionized water 45g was thrown here, and the silica water dispersion was obtained by stirring at 3,000 rpm for 2 minutes using Ultraturrax. The shear rate at that time was about 11,000 s ⁻¹ .
Subsequently, as a second stage, 50 g of a fluorine-containing organopolysiloxane having a viscosity of 1000 mPa · s (available under the name AF98 / 1000 from Wacker Chemie (Munich, Germany)) is added and stirred at 1,500 rpm for 2 minutes. Thus, a low-viscosity white oil-in-water emulsion was obtained. The shear rate at that time was about 4,600 s ⁻¹ .

  A water dispersion and a low-viscosity white oil-in-water emulsion were obtained in the same manner as in Example 1, except that 1 g of silica 1 and 4 g of silica 2 were added.

  A water dispersion and a low-viscosity white oil-in-water emulsion were obtained in the same manner as in Example 1, except that 4 g of silica 1 and 1 g of silica 2 were added.

Partially hydrophobized hydrophilic fumed silica (“silica 3”) 5 g was charged into a 500 mL stainless steel beaker. The deionized water 45g was thrown here, and the silica water dispersion was obtained by stirring at 3,000 rpm for 2 minutes using Ultraturrax.
Subsequently, 50 g of a fluorine-containing organopolysiloxane having a viscosity of 1000 mPa · s (available under the name AF98 / 1000 from Wacker Chemie (Munich, Germany)) was added, and the mixture was stirred at 1,500 rpm for 2 minutes. A viscous white oil-in-water emulsion was obtained.

  A water dispersion and a low-viscosity white oil-in-water emulsion were obtained in exactly the same manner as in Example 1, except that the stirring time in the second stage was 1 minute.

An aqueous dispersion and a low-viscosity white oil-in-water emulsion were obtained in exactly the same manner as in Example 1, except that the stirring in the second stage was 500 rpm. The shear rate at that time was about 1,500 s ⁻¹ .

  A water dispersion and a low-viscosity white oil-in-water emulsion were obtained in the same manner as in Example 1 except that the stirring time in the first stage was 1 minute.

  The oil-in-water emulsion obtained in Example 1 was diluted twice with water on a metal glossy iron plate having a smooth surface and no rust, and a film having a thickness of 30 μm was formed using a bar coater. When this plate was exposed outdoors for one month, the surface was greatly rusted without the coat, whereas the initial metallic luster was maintained with the coat.

  The oil-in-water emulsion obtained in Example 1 was diluted twice with water on a steel plate coated with an acrylic melamine resin, and a film having a thickness of 30 μm was formed using a bar coater. When this plate was immersed in water at room temperature for 1 week, the resin swelled without the coat, whereas the initial resin state was maintained with the coat.

  After 5% of the oil-in-water emulsion obtained in Example 1 was put into a commercially available UV-protective makeup agent and stirred well, the glass test piece was diluted 2 times with water using a bar coater. The coating was applied with a thickness of about 30 μm. When this specimen was immersed in water at room temperature for 1 hour and measured for SPF (sun protection factor), SPF was reduced to 70% without coating, whereas SPF was initial with coating. It was reduced to 90%, exceeding the preferable level of 80%.

<Comparative Example 1>
5 g of hydrophilic fumed silica (“Silica 1”) was placed in a 500 mL stainless steel beaker. The deionized water 45g was thrown here, and the silica water dispersion was obtained by stirring at 3,000 rpm for 2 minutes using Ultraturrax.
Subsequently, 50 g of a fluorine-containing organopolysiloxane having a viscosity of 1000 mPa · s (available under the name AF98 / 1000 from Wacker Chemie (Munich, Germany)) is added, and the emulsion is stirred for 2 minutes at 1,500 rpm. However, the oil-in-water property was not sufficient.

<Comparative example 2>
An overall white liquid was obtained in exactly the same manner as in Comparative Example 1, except that 5 g of hydrophobic fumed silica (“silica 2”) was added instead of 5 g of hydrophilic fumed silica (“silica 1”). In addition, the oil-in-water property in a state of being separated into an aqueous phase as a continuous phase and an oil phase as a dispersed phase was not sufficient.

<Comparative Example 3>
2.5 g of hydrophilic fumed silica (“Silica 1”) and 2.5 g of hydrophobic fumed silica (“Silica 2”) were charged into a 500 mL stainless steel beaker. The deionized water 45g was thrown here, and the silica water dispersion was obtained by stirring at 500 rpm for 2 minutes using Ultraturrax. The shear rate at that time was about 1,900 s ⁻¹ .
Subsequently, 50 g of fluorine-containing organopolysiloxane having a viscosity of 1000 mPa · s (available under the name AF98 / 1000 from Wacker Chemie (Munich, Germany)) was added, and the whole was stirred at 1,500 rpm for 2 minutes. Although a white liquid was obtained, the oil-in-water property in a state where it was separated into an aqueous phase as a continuous phase and an oil phase as a dispersed phase was not sufficient.

<Comparative example 4>
As a first step, 50 g of fluorine-containing organopolysiloxane with a viscosity of 1000 mPa · s (Wakker Chemie AF98 / 1000 was charged into a 500 mL stainless steel beaker. The oil-in-water emulsion was obtained by stirring at 900 rpm for 2 minutes, and the shear rate was about 5,700 s ⁻¹ .
Subsequently, as a second step, 2.5 g of hydrophilic fumed silica (“silica 1”) and 2.5 g of hydrophobic fumed silica (“silica 2”) were added and stirred at 3,000 rpm for 2 minutes. The shear rate at that time was about 11,000 s ⁻¹ .
Although an entire white liquid was obtained, the oil-in-water property in a state of being separated into an aqueous phase as a continuous phase and an oil phase as a dispersed phase was not sufficient.

<Comparative Example 5>
2.5 g of hydrophilic fumed silica (“silica 1”), 2.5 g of hydrophobic fumed silica (“silica 2”) and 50 g of fluorine-containing organopolysiloxane having a viscosity of 1000 mPa · s (Wakker Chemie AF98 / 1000) Into a 500 mL stainless steel beaker, 45 g of deionized water was added at the same time and stirred for 2 minutes at 3,000 rpm using an Ultraturrax, with a shear rate of about 11,000 s ⁻¹ .
Although an entire white liquid was obtained, the oil-in-water property in a state of being separated into an aqueous phase as a continuous phase and an oil phase as a dispersed phase was not sufficient.

<Summary of preparation results of water dispersion and oil-in-water emulsion>
As shown in Tables 2 and 3, the total number of moles of the surface hydrophilic groups in each of the silica particles at the raw material fumed silica stage over the particle groups, and the surface hydrophobic groups in each of the particles When the ratio of the total number of moles across the number of moles of particles was in the range of 26/74 to 74/26, stable water dispersions and oil-in-water emulsions were formed. However, when the molar ratio was 90/10, the water dispersion was stable, but a stable oil-in-water emulsion was not formed. At a molar ratio of 10/90, neither the aqueous dispersion nor the emulsion was stable.
Even when the molar ratio was 50/50, when the shear rate was low, neither the aqueous dispersion nor the emulsion was stable.
In all cases where the shear rate was sufficiently large, the variation in the degree of hydrophobicity of the surface at the secondary aggregation level was sufficiently small, but when the shear rate was not sufficient, the variation was large.
The oil-containing fluorine-containing organopolysiloxane was sucked in at a shear rate significantly lower than the shear rate applied during the preparation of the water dispersion. It is thought that it shifted to an emulsion (Pickering emulsion).
After mixing silica, water and oil at the same time, and mixing water and oil, it was confirmed that neither silica mixing nor stable emulsion could be achieved. Further, it was confirmed that the main dispersion may be used for the aqueous dispersion and the auxiliary shear may be used for the emulsion. On the basis of these, formation of self-micellar aggregates in the aqueous dispersion is inferred.
It was confirmed that the overall molar ratio and variation fluctuated in order to ensure the stability of the emulsion according to the cohesiveness of silica.
With regard to shearing, where the rearrangement is necessary for the stability of the emulsion, the shearing time is not limited as long as the shearing speed is a predetermined value or more, but the shearing speed and the shearing time are related to the adjustment of the composite particle specifications. It was confirmed.

The emulsion of the present invention can give a film shape to a fluorine-containing organopolysiloxane, which has been impossible in the past, so that it is water repellent, oil repellent, heat resistant, cosmetic performance, antifouling, weather resistant, mold release. , Long-term stability, insulation or high dielectric constant can be provided. Therefore, it improves the characteristics in various industrial uses such as protective coating and cosmetic use, which have been impossible or insufficient, and general uses, and enables the development of new uses.
Because it does not save or reduce the use of organic surfactants, it can be present in the form of environmental problems, stable production, and stable emulsions, and it is free of organic surfactants and can be supplied in water. It is also useful from the viewpoint of hypoallergenicity as a cosmetic raw material that is directly applied to the skin, and may be advantageously used in many industries.

In the embodiment, it is a schematic diagram showing what aggregates can be formed when fumed silica particles are dispersed in water, and the size of the aggregates is exaggerated for clarity. .

10 Hydrophilic rich primary aggregate 12 Hydrophobic rich primary aggregate 14 Secondary aggregate 16 Space

Claims (3)

The fumed silica particle group in which the lower aggregates of the fumed silica particle group form high-order aggregates by non-chemical bonds, and the total number of moles of surface hydrophilic groups in each fumed silica particle group The number of moles / the number of moles of the surface hydrophobic group in each is formed by the fumed silica particle group of the secondary aggregation level in which the total mole number ratio that is the total mole number over the fumed silica particle group is within a predetermined numerical range. Self-micelles in which the high-density part of the hydrophilic-rich lower aggregate is in contact with the aqueous phase and the high-density part of the hydrophobic-rich lower aggregate is in contact with other hydrophobic-rich lower aggregates to form a space inside Including a group of composite particles in a form in which oil is sucked into the internal aggregate,
The oil component is an organopolysiloxane having an average composition represented by the general formula (1),
R ¹ _a R ² _b SiO _{(4-ab) / 2} (1)
[In formula (1), R ¹ may be the same or different in the molecule, and is a substituted or unsubstituted C1-C25 saturated or unsaturated monovalent hydrocarbon group, substituted or unsubstituted. An aromatic group having 6 to 30 carbon atoms, a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, or a hydrogen atom, and R ² may be the same or different in the molecule, and may have 1 to 25 carbon atoms. A saturated or unsaturated monovalent hydrocarbon group, or an aromatic group having 6 to 30 carbon atoms, wherein a hydrogen atom on at least one carbon is substituted with a fluorine atom, and b is not 0 A positive number, a + b is 0.3 or more and less than 2.5]
Each of the composite particle groups is an oil-in-water emulsion characterized in that self-micellar aggregates cover the surface of oil droplets. The molar ratio of surface hydrophilic groups in each of the fumed silica particle groups is obtained by mixing a hydrophobic rich silica raw material in which silanol groups on the surface are hydrophobized with a hydrophilic rich silica raw material in which silanol groups remain on the surface in a predetermined ratio. A total number of moles ratio that is a total number of moles across the fumed silica particle group of moles of surface hydrophobic groups in each of the fumed silica particle group. Preparing a fumed silica particle group of secondary aggregation level so that
The prepared secondary agglomeration level fumed silica particles are added to water and sheared at a predetermined shear rate, thereby exchanging the secondary agglomeration level fumed silica particles at the primary agglomeration level and / or. By promoting the orientation at the primary flocculation level in the fumed silica particles at the secondary flocculation level, the high-density portion of the hydrophilic-rich lower aggregates by the fumed silica particles at the secondary flocculation level is Producing an aqueous dispersion comprising self-micellar aggregates that contact and form a space therein;
Forming an emulsion by adding oil into the resulting aqueous dispersion and allowing the oil to be sucked into the self-micellar agglomerates; and
The oil component is an organopolysiloxane having an average composition represented by the general formula (1),
R ¹ _a R ² _b SiO _{(4-ab) / 2} (1)
[In formula (1), R ¹ may be the same or different in the molecule, and is a substituted or unsubstituted C1-C25 saturated or unsaturated monovalent hydrocarbon group, substituted or unsubstituted. An aromatic group having 6 to 30 carbon atoms, a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, or a hydrogen atom, and R ² may be the same or different in the molecule, and may have 1 to 25 carbon atoms. A saturated or unsaturated monovalent hydrocarbon group, or an aromatic group having 6 to 30 carbon atoms, wherein a hydrogen atom on at least one carbon is substituted with a fluorine atom, and b is not 0 A positive number, a + b is 0.3 or more and less than 2.5]
Thus, a method for producing an oil-in-water emulsion, comprising a composite particle group in a form in which an oil component is contained inside a self-micellar aggregate formed by fumed silica particle groups at a secondary aggregation level.   Using the produced oil-in-water emulsion according to claim 2, a coating having a predetermined film thickness set according to any of protection of the substrate, modification of the substrate and imparting a function to the surface of the substrate A method for forming a coating, comprising the step of forming on a surface of a substrate.

Images