JP2020076002A - Sustained-release composite particle, method for producing the same, and dry powder - Google Patents

Abstract

To provide: a novel easy-to-handle sustained-release composite particle that can maintain the effect of functional components for a long period of time while maintaining the characteristics of cellulose nanofiber; a method for producing said sustained-release composite particle; and a dry powder body containing said sustained-release composite particle.SOLUTION: The sustained-release composite particle 9 is a composite particle having a coating layer 2 composed of a micronized cellulose 1 on the surface of a core particle 3 containing at least one kind of polymer. The functional component is contained in the coating layer 2. The core particle 3 and the micronized cellulose 1 are combined and in an inseparable state.SELECTED DRAWING: Figure 2

Description

  The present invention relates to sustained release composite particles containing a functional component, a method for producing sustained release composite particles, and a dry powder containing the above sustained release composite particles.

  In recent years, attempts have been actively made to reduce the size of cellulose fibers in wood until at least one side of the structure is on the order of nanometers and use them as a novel functional material.

For example, Patent Document 1 discloses that micronized cellulose, that is, cellulose nanofibers (hereinafter, also referred to as CNF) can be obtained by repeating mechanical treatment of wood cellulose with a blender or a grinder. It has been reported that the CNF obtained by this method has a short axis diameter of 10 to 50 nm and a long axis diameter of 1 μm to 10 mm. This CNF is 5 times lighter than steel and 5 times stronger, and has an enormous specific surface area of 250 m ² / g or more, so it is expected to be used as a filler for resin reinforcement or as an adsorbent. ing.

  Further, attempts have been made actively to produce CNF by chemically treating the cellulose fibers in the wood in advance so as to facilitate the miniaturization, and then miniaturizing the cellulose fibers by a low-energy mechanical treatment such as a household mixer. The method of the chemical treatment is not particularly limited, but a method of introducing an anionic functional group into the cellulose fiber to facilitate micronization is preferable. By introducing an anionic functional group into the cellulose fiber, the solvent easily penetrates due to the osmotic effect between the cellulose microfibril structures, and the energy required for refining the cellulose raw material can be greatly reduced. The method for introducing the anionic functional group is not particularly limited. For example, Non-Patent Document 1 discloses a method for selectively performing a phosphoric acid esterification treatment on the surface of cellulose fine fibers using a phosphoric acid esterification treatment. ing. Further, Patent Document 2 discloses a method of carrying out carboxymethylation by reacting cellulose with monochloroacetic acid or sodium monochloroacetate in a highly concentrated alkaline aqueous solution. Further, it is described that a carboxylic acid anhydride compound such as maleic acid or phthalic acid gasified in an autoclave may be directly reacted with cellulose to introduce a carboxy group.

  Further, a method of selectively oxidizing the surface of fine fibers of cellulose by using 2,2,6,6-tetramethylpiperidinyl-1-oxy radical (TEMPO), which is a relatively stable N-oxyl compound, as a catalyst Have also been reported (see, for example, Patent Document 3). The oxidation reaction that uses TEMPO as a catalyst (TEMPO oxidation reaction) can be chemically modified in an environmentally friendly manner that proceeds in water, at room temperature, and atmospheric pressure. When applied to cellulose in wood, the reaction does not occur inside the crystals. Without proceeding, only the alcoholic primary carbon of the cellulose molecular chain on the crystal surface can be selectively converted into a carboxy group.

  Cellulose single nanofibers (hereinafter also referred to as CSNF) dispersed in a solvent into individual cellulose microfibril units by an osmotic pressure effect caused by ionization of carboxy groups selectively introduced on the crystal surface by TEMPO oxidation. It is possible to obtain). CSNF exhibits high dispersion stability derived from the carboxy groups on the surface. Wood-derived CSNF obtained from wood by a TEMPO oxidation reaction is a structure having a high aspect ratio with a short axis diameter of about 3 nm and a long axis diameter of several tens of nm to several μm. Is reported to have high transparency. Further, Patent Document 4 reports that a laminated film obtained by coating and drying a CSNF dispersion has gas barrier properties.

  Here, in practical application of CNF, the problem is that the solid content concentration of the obtained micronized cellulose dispersion (also referred to as CNF dispersion) is as low as about 0.1 to 5%. For example, when it is attempted to transport a finely divided cellulose dispersion, there is a problem in that a large amount of solvent is transported, so that the transportation cost rises and the businessability is significantly impaired. In addition, when used as an additive for reinforcing a resin, there are problems that the addition efficiency is deteriorated due to a low solid content, and that compounding becomes difficult when water as a solvent is not compatible with the resin. Further, when handled in a water-containing state, the water-containing CNF dispersion may be putrefaction, so that measures such as refrigerating storage and antiseptic treatment are required, which may increase cost.

However, if the solvent is simply removed from the CNF dispersion by heat drying or the like, the micronized cellulose aggregates, keratinizes, or forms a film, making it difficult to achieve stable function as an additive. I will end up. Furthermore, since the solid content concentration of CNF is low, a large amount of energy is applied to the solvent removal process itself by drying, which is also a cause of impairing the business.
As described above, handling CNF in a dispersion state itself impairs its businessability. Therefore, it is strongly desired to provide a new handling mode in which CNF can be easily handled.
As exemplified above, various studies have been made on the development of highly functional members such as CNF or CSNF, which are carbon neutral materials, that impart new functionality to micronized cellulose.

  On the other hand, various types of microparticles and microcapsules have been put into practical use as functional materials in various fields. Usually, microparticles are particles of microsize order formed of various polymers, and are used as, for example, fillers, spacers, abrasives, and the like. As a conventional method for producing a resin powder, for example, a method for producing a resin by emulsifying a monomer using a surfactant, or a method of cooling a lump of resin at a low temperature of -50 to -180 ° C. A method of obtaining fine powder by mechanical pulverization / classification (Patent Document 5) and the like can be mentioned. However, in the former case, for example, in each process such as stirring operation, transfer, addition of auxiliary agent, coating, etc., foam trouble due to foaming may occur, production efficiency may be reduced, and wastewater load due to outflow of surfactant from the system. Is also a problem. Further, the latter has a problem that, for example, crushing / classifying work requires a lot of time, and the shape of the powder is not uniform.

Further, it has been attempted to impart and develop further functionality by forming a microcapsule structure in which microparticles are used as a core substance and the surface of the particles is covered with a wall film. Specifically, for example, by incorporating a functional material such as a magnetic substance, a drug, a pesticide, a fragrance, an adhesive, an enzyme, a pigment, a dye into a core substance and then microencapsulating the functional material, the functional material is obtained. Can be protected and the release behavior can be controlled. It is also possible to further add a functional material to the wall film itself that covers the core substance. However, microcapsules exert the effect of the core substance by destroying the wall membrane that covers the core substance, but since the effect is released at the moment when the wall membrane is destroyed, the efficacy is continuously maintained. Is difficult. In addition, since the microcapsules are easily broken during processing, there is a problem that they are poor in handleability. In order to solve this problem, there is a method of supporting a functional substance on porous fine particles and coating the surface thereof with a curable compound to protect the functional substance (see Patent Document 6). However, in this method, since the surface of the porous fine particles is coated with a curable substance, agglomerates are generated during curing and the dispersibility is poor.
As described above, it is strongly desired to provide a new handling mode in which microparticles excellent in sustained release and dispersibility can be easily handled.

JP, 2010-216021, A International Publication No. 2014/088072 JP, 2008-001728, A International Publication No. 2013/042654 JP 2001-288273 A JP, 2009-012996, A

Noguchi Y, Homma I, Matsubara Y. Complete nanofibrillation of cellulose prepared by phosphorylation. Cellulose. 2017; 24: 1295.10.1007 / s10570-017-1191-3

  The present invention has been made in view of such circumstances, while maintaining the characteristics of the cellulose nanofibers, it is possible to maintain the effect of the functional component for a long period of time, easy-release sustained release composite particles, An object of the present invention is to provide a method for producing sustained-release composite particles and a dry powder containing the sustained-release composite particles.

  In order to solve the problem, the sustained-release composite particles according to one embodiment of the present invention include a core particle containing at least one type of polymerizable monomer or polymer, and at least a part of the surface of the core particle, and a fine particle. A coating layer composed of derivatized cellulose, at least the coating layer among the core particles and the coating layer, containing a functional component, the micronized cellulose and the core particles are bound and inseparable. The point is that it is in the state of.

The method for producing sustained-release composite particles according to one aspect of the present invention includes a first step of defibrating a cellulose raw material in a solvent to obtain a dispersion of finely divided cellulose, and at least one polymerization in the dispersion. A second step of covering at least a part of the surface of a droplet containing a polymerizable monomer or polymer with the micronized cellulose, and stabilizing the droplet containing the at least one type of polymerizable monomer or polymer as an emulsion;
In a state where at least a part of the surface of the droplet containing the at least one type of polymerizable monomer or polymer is covered with the micronized cellulose, the droplet containing the at least one type of polymerizable monomer or polymer is solidified. By making it a core particle, at least a part of the surface of the core particle is covered with the micronized cellulose, and the third step of making the core particle and the micronized cellulose inseparable, and the core particle A fourth step of imparting a functional component to the above-mentioned micronized cellulose for coating the surface.
The dry powder according to one aspect of the present invention contains the above-mentioned sustained release composite particles and has a solid content of 80% or more.

  According to one aspect of the present invention, while maintaining the characteristics of the cellulose nanofibers, the effect of the functional component can be maintained for a long period of time, and the sustained-release composite particles that are easy to handle and the sustained-release composite particles thereof. It is possible to provide a manufacturing method and a dry powder containing the sustained-release composite particles.

It is a schematic diagram of the composite particle concerning the embodiment of the present invention. An O / W type Pickering emulsion using CNF according to an embodiment of the present invention, a composite particle obtained by solidifying a polymerizable monomer or a polymer inside the emulsion, and a functional component in a coating layer of the composite particle. FIG. 3 is a schematic view of sustained-release composite particles obtained by adding 3 is a result of spectral transmission spectrum measurement of an aqueous dispersion of micronized cellulose obtained in Example 1. It is a result of performing steady-state viscoelasticity measurement using a rheometer on the aqueous dispersion of micronized cellulose obtained in Example 1. FIG. 3 is a diagram (SEM image) showing a result of observing the sustained-release composite particles obtained in Example 1 with a scanning electron microscope (SEM). FIG. 3 is a diagram (SEM image) showing the results of observing the sustained-release composite particles obtained in Example 1 at a high magnification with a scanning electron microscope (SEM).

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
However, in each of the drawings described below, portions corresponding to each other are denoted by the same reference numerals, and overlapping portions will not be described below as appropriate. In addition, the present embodiment exemplifies a configuration for embodying the technical idea of the present invention, and does not specify the material, shape, structure, arrangement, size, etc. of each part to the following. The technical idea of the present invention can be variously modified within the technical scope defined by the claims described in the claims.

<Composite particles>
First, the composite particles 4 according to the embodiment of the present invention will be described.
FIG. 1 shows a composite particle 4 having a coating layer 2 composed of micronized cellulose 1 (hereinafter, also referred to as cellulose nanofiber, CNF) on at least a part of the surface of a core particle 3 containing at least one kind of polymer. It is a schematic diagram.
In addition, in this specification, "micronized cellulose" means a fibrous cellulose having a number average minor axis diameter in the range of 1 nm or more and 1000 nm or less in the minor axis diameter.

The composite particles 4 to be a sustained-release composite particle contain a core particle 3 which is a particle containing at least one kind of polymerizable monomer or polymer, and at least a part of the surface of the core particle 3 is formed by the micronized cellulose 1. It has a structured coating layer 2. The core particles 3 and the micronized cellulose 1 are bonded to each other and are in an inseparable state. The composite particle 4 contains a functional component in at least the coating layer 2 of the core particle 3 and the coating layer 2.
It is preferable that the coating layer 2 is provided on 60% or more, preferably 90% or more of the surface of the core particles 3. By providing the coating layer 2 in an amount of 60% or more of the surface of the core particles 3, the dispersibility of the composite particles is improved and the functional component can be sufficiently added.

  The method for producing the composite particles 4 is not particularly limited, but for example, an O / W type Pickering emulsion using the finely divided cellulose 1 is formed, and the droplets inside the emulsion are solidified to form solid core particles. As a result, the core particles 3 and the micronized cellulose 1 are bonded to each other to obtain the composite particles 4 in an inseparable state. By using the micronized cellulose 1, droplets can be formed without using an additive such as a surfactant, and the composite particles 4 having high dispersibility can be obtained.

The “individual” in the present specification means, for example, an operation of centrifuging a dispersion liquid containing the composite particles 4 to remove a supernatant, and further refining and washing the composite particles 4 by adding a solvent and redispersing the mixture. Alternatively, even after the operation of repeatedly washing with a solvent by filtration washing with a membrane filter is repeated, the finely divided cellulose 1 and the core particles 3 do not separate, and the state of coating of the finely divided cellulose 1 on the core particles 3 is Means to be kept.
The above "not separated" refers to, for example, the case where 90% or more is not separated.
The coating state can be confirmed, for example, by observing the surface of the composite particle 4 with a scanning electron microscope.

In the composite particles 4, the binding mechanism between the micronized cellulose 1 and the core particles 3 is not clear, but it is presumed as follows. That is, the composite particles 4 are produced using the O / W emulsion stabilized by the micronized cellulose 1 as a template. Therefore, the droplets are solidified in a state where the micronized cellulose 1 is in contact with the droplets inside the emulsion. As a result, in the composite particles 4 obtained after solidification, it is expected that at least a part of the micronized cellulose 1 existing on the surface of the core particles 3 will be taken into the inside of the core particles 3. For the above reasons, it is presumed that the finely divided cellulose 1 is physically fixed to the solidified core particles 3 and finally the core particles 3 and the finely divided cellulose 1 reach an inseparable state.
Here, the O / W type emulsion is also referred to as an oil-in-water type, and has water as a continuous phase in which oil is dispersed as oil droplets (oil particles). ..

Moreover, since the composite particles 4 of the present embodiment are produced by using the O / W type emulsion stabilized by the micronized cellulose 1 as a template, the shape of the composite particles 4 is a spherical shape derived from the O / W type emulsion. The feature is that Specifically, it is an embodiment in which the coating layer 2 made of the micronized cellulose 1 is formed on the surface of the spherical core particle 3 with a relatively uniform thickness.
The average thickness of the coating layer 2 is measured, for example, by fixing the composite particles 4 with an embedding resin, cutting with a microtome, and observing with a scanning electron microscope. Specifically, the average thickness of the coating layer 2 is calculated by randomly measuring the thickness of the coating layer 2 in the cross-sectional image of the composite particles 4 in the image at 100 locations on the image, and taking the average value of the measured values. it can.

Further, the composite particles 4 of the present embodiment are characterized in that they are uniformly coated with the coating layer 2 having a relatively uniform thickness. Specifically, the variation coefficient of the thickness value of the coating layer 2 described above is preferably 0.5 or less, and more preferably 0.4 or less. When the variation coefficient of the thickness value of the coating layer 2 containing the micronized cellulose 1 exceeds 0.5, for example, it may be difficult to collect the composite particles 4.
Furthermore, it is preferable that the micronized cellulose 1 has a fiber shape derived from a microfibril structure. Specifically, the micronized cellulose 1 is fibrous, has a number average minor axis diameter of 1 nm or more and 1000 nm or less, a number average major axis diameter of 50 nm or more, and a number average major axis diameter of several average minor axis diameter. It is preferably 5 times or more. The crystal structure of the micronized cellulose 1 is preferably cellulose type I.

<Method for producing sustained-release composite particles>
FIG. 2 shows an example of a method for producing the sustained-release composite particles 9 of this embodiment. The sustained-release composite particles 9 according to the present embodiment can be manufactured by performing the following first to fourth production steps.
The first step is a step of defibrating the cellulose raw material in a solvent to obtain a dispersion liquid 6 of the micronized cellulose 1.
The second step is a step of covering at least a part of the surface of the droplet 5 in the dispersion liquid 6 of the micronized cellulose 1 with the micronized cellulose 1 to stabilize the droplet 5 as an emulsion.
In the third step, at least a part of the surface of the core particle 3 is obtained by solidifying the droplet 5 into the core particle 3 in a state where at least a part of the surface of the droplet 5 is covered with the micronized cellulose 1. In which the core particles 3 and the micronized cellulose 1 are inseparable.
The fourth step is a step of imparting at least one kind of functional component to the micronized cellulose 1 covering the core particles 3.

The sustained-release composite particles 9 obtained by the above production method are obtained as a dispersion in a solvent. Furthermore, by removing the solvent from the dispersion liquid, the sustained-release composite particles 9 are obtained as a dry solid (dry powder).
The method for removing the solvent is not particularly limited, and the excess solvent is removed by, for example, a centrifugal separation method or a filtration method, and then heat-dried in an oven to obtain a dry solid. At this time, the obtained dry solid does not form a film or an aggregate and is obtained as a finely textured powder (dry powder). The reason for this is not clear, but it is presumed as follows.

  That is, it is generally known that when the solvent is removed from the micronized cellulose dispersion, the micronized celluloses are strongly aggregated and formed into a film. On the other hand, in the case of the dispersion liquid containing the sustained-release composite particles 9, since the micronized cellulose 1 is a true spherical composite particle immobilized on the surface, the micronized cellulose 1 aggregates with each other even if the solvent is removed. Instead, they only contact at points between the composite particles. Therefore, it is considered that the dried solid substance is obtained as a finely textured powder. Further, since the sustained-release composite particles 9 do not aggregate with each other, it is easy to redisperse the sustained-release composite particles 9 obtained as a dry powder in the solvent again, and the sustained-release composite particles after the redispersion are also possible. 9 shows the dispersion stability derived from the micronized cellulose 1 bonded to the surface of No. 9.

  The dry powder of the sustained-release composite particles 9 is a dry solid substance containing almost no solvent and being redispersible in the solvent. Specifically, the dry powder has a solid content of 80% or more. It is preferably 90% or more, more preferably 95% or more. By adopting the present invention, the solid content can be 95% or more. In this embodiment, the solvent can be almost removed from the dispersion liquid containing the sustained release composite particles 9. Therefore, the dry powder of the sustained-release composite particles 9 of the present embodiment has preferable effects from the viewpoints of, for example, reduction of transportation cost, prevention of decay, improvement of addition rate, and improvement of kneading efficiency with resin. When the solid content rate is set to 80% or more by the drying treatment, the micronized cellulose 1 easily absorbs moisture, and therefore moisture in the air may be adsorbed and the solid content rate may decrease with time. However, in view of the technical idea of the present invention, which is characterized in that the sustained-release composite particles 9 are easily obtained as a dry powder and can be re-dispersed, a dry powder containing the sustained-release composite particles 9 can be obtained. Any dry solid matter produced by the method for producing a dry solid matter including the step of adjusting the solid content to 80% or more is defined as being included in the technical scope of the present invention.

Below, each process of the 1st process-4th process is demonstrated in detail.
(First step)
The first step is a step of defibrating the cellulose raw material in a solvent to obtain a micronized cellulose dispersion.
In the first step, first, various cellulose raw materials are dispersed in a solvent to form a suspension.
The concentration of the cellulose raw material in the suspension is preferably 0.1% or more and less than 10%. If the concentration of the cellulose raw material in the suspension is less than 0.1%, the amount of the solvent is excessive and the productivity tends to be deteriorated, which is not preferable. Further, if the concentration of the cellulose raw material in the suspension is 10% or more, the suspension rapidly thickens as the cellulose raw material is defibrated, and uniform defibration treatment tends to be difficult, which is not preferable. ..

  The solvent used for preparing the suspension preferably contains 50% or more of water. If the proportion of water in the suspension is less than 50%, the dispersion of the finely divided cellulose 1 tends to be hindered in the step of defibrating the cellulose raw material to be described later in a solvent to obtain a finely divided cellulose dispersion. .. A hydrophilic solvent is preferred as the solvent contained in addition to water. The hydrophilic solvent is not particularly limited, but for example, alcohols such as methanol, ethanol and isopropanol, and cyclic ethers such as tetrahydrofuran are preferable. If necessary, in order to improve the dispersibility of the cellulose and the finely divided cellulose 1 to be produced, for example, the pH of the suspension may be adjusted. Examples of the alkaline aqueous solution used for pH adjustment include sodium hydroxide aqueous solution, lithium hydroxide aqueous solution, potassium hydroxide aqueous solution, ammonia aqueous solution, tetramethylammonium hydroxide aqueous solution, tetraethylammonium hydroxide aqueous solution, tetrabutylammonium hydroxide aqueous solution, Examples thereof include organic alkali such as benzyltrimethylammonium hydroxide aqueous solution. As the alkaline aqueous solution used for pH adjustment, an aqueous sodium hydroxide solution is preferable in terms of cost and the like.

In the first step, subsequently, the suspension is subjected to a physical defibration treatment to make the cellulose raw material fine.
The method of physical defibration is not particularly limited, for example, high pressure homogenizer, ultrahigh pressure homogenizer, ball mill, roll mill, cutter mill, planetary mill, jet mill, attritor, grinder, juicer mixer, homomixer, ultrasonic waves. Mechanical treatments such as homogenizers, nanogenizers, underwater counter collisions, etc. may be mentioned. By performing such a physical defibration treatment, the cellulose in the suspension is micronized, and a dispersion liquid of micronized cellulose (micronized cellulose 1) until at least one side of its structure is in the nanometer order. Can be obtained. Further, the number average minor axis diameter and number average major axis diameter of the obtained micronized cellulose 1 can be adjusted by the time and the number of times of the physical defibration treatment at this time.
As described above, a dispersion of cellulose 1 (micronized cellulose dispersion) is obtained in which at least one side of the structure is in the nanometer order. The obtained dispersion can be used as it is, or after diluting or concentrating it, as a stabilizer for an O / W type emulsion described later.

  Usually, the micronized cellulose 1 has a fiber shape derived from a microfibril structure. Therefore, the micronized cellulose 1 used in the production method of the present embodiment preferably has a fiber shape in the range shown below. That is, the shape of the micronized cellulose 1 is preferably fibrous. In the fibrous micronized cellulose 1, the number average minor axis diameter in the minor axis diameter may be 1 nm or more and 1000 nm or less, and preferably 2 nm or more and 500 nm or less. Here, when the number average minor axis diameter is less than 1 nm, it is difficult to carry out the stabilization of the emulsion and the polymerization reaction using the emulsion as a template, since it is not possible to have a highly crystalline rigid micronized cellulose structure. Tend to be. On the other hand, when the number average minor axis diameter of the minor axis diameters exceeds 1000 nm, the size becomes too large to stabilize the emulsion, so that it tends to be difficult to control the size and shape of the obtained composite particles 4. is there. The number average major axis diameter is not particularly limited, but it is preferably 5 times or more the number average minor axis diameter. If the number average major axis diameter is less than 5 times the number average minor axis diameter, it tends to be difficult to sufficiently control the size and shape of the composite particles 4, which is not preferable.

  The number average minor axis diameter of micronized cellulose is obtained as an average value by measuring the minor axis diameter (minimum diameter) of 100 fibers by observation with a transmission electron microscope and atomic force microscope. On the other hand, the number average major axis diameter of micronized cellulose is obtained as an average value by measuring the major axis diameter (maximum diameter) of 100 fibers by observation with a transmission electron microscope and atomic force microscope, for example.

  The type and crystal structure of cellulose that can be used as the raw material for the micronized cellulose 1 are not particularly limited. Specifically, examples of the raw material composed of cellulose type I crystals include, in addition to wood-based natural cellulose, non-wood-based natural cellulose such as cotton linter, bamboo, hemp, bagasse, kenaf, bacterial cellulose, ascidian cellulose, and baronia cellulose. Can be used. Further, regenerated cellulose typified by rayon fibers and cupra fibers composed of cellulose type II crystals can also be used. It is preferable to use wood-based natural cellulose as a raw material from the viewpoint of easy material procurement. The wood-based natural cellulose is not particularly limited, and for example, softwood pulp, hardwood pulp, waste paper pulp, and the like that are generally used for producing cellulose nanofibers can be used. Softwood pulp is preferred because it is easily refined and refined.

Furthermore, it is preferable that the raw material of the micronized cellulose 1 is chemically modified. More specifically, it is preferable that an anionic functional group is introduced on the crystal surface of the raw material of the micronized cellulose 1. This is because the introduction of an anionic functional group on the surface of the cellulose crystals facilitates the infiltration of the solvent between the cellulose crystals due to the osmotic effect, and facilitates the miniaturization of the cellulose raw material.
The type and introduction method of the anionic functional group introduced into the crystal surface of cellulose are not particularly limited, but a carboxy group or a phosphate group is preferable. A carboxy group is more preferable because it is easily introduced selectively onto the surface of the cellulose crystal.

  The method of introducing a carboxy group onto the fiber surface of cellulose is not particularly limited. As a method of introducing a carboxy group, specifically, carboxymethylation may be performed, for example, by reacting cellulose with monochloroacetic acid or sodium monochloroacetate in a high-concentration alkaline aqueous solution. Alternatively, a carboxylic acid anhydride compound such as maleic acid or phthalic acid gasified in an autoclave may be directly reacted with cellulose to introduce a carboxy group. Furthermore, under relatively mild conditions of water system, while maintaining the structure as much as possible, in the presence of N-oxyl compounds such as TEMPO, which has high selectivity for the oxidation of alcoholic primary carbon, a co-oxidizing agent is used. The method used may be used. Oxidation using an N-oxyl compound is more preferable for the selectivity of the site for introducing a carboxy group and the reduction of environmental load.

  Here, as the N-oxyl compound, for example, TEMPO (2,2,6,6-tetramethylpiperidinyl-1-oxy radical), 2,2,6,6-tetramethyl-4-hydroxypiperidine- 1-oxyl, 4-methoxy-2,2,6,6-tetramethylpiperidine-N-oxyl, 4-ethoxy-2,2,6,6-tetramethylpiperidine-N-oxyl, 4-acetamido-2, 2,6,6-tetramethylpiperidine-N-oxyl and the like can be mentioned. Among them, TEMPO having high reactivity is preferable. The amount of the N-oxyl compound used may be a catalyst amount and is not particularly limited. Usually, it is 0.01% by mass or more and 5.00% by mass or less based on the solid content of the wood-based natural cellulose to be oxidized.

  Examples of the oxidation method using an N-oxyl compound include a method in which wood-based natural cellulose is dispersed in water and an oxidation treatment is performed in the presence of an N-oxyl compound. At this time, it is preferable to use a co-oxidizing agent together with the N-oxyl compound. In this case, in the reaction system, the N-oxyl compound is sequentially oxidized by the cooxidant to generate an oxoammonium salt, and the oxoammonium salt oxidizes the cellulose. According to this oxidation treatment, the oxidation reaction proceeds smoothly even under mild conditions, and the introduction efficiency of carboxy groups improves. When the oxidation treatment is performed under mild conditions, it is easy to maintain the crystal structure of cellulose.

  As the co-oxidizing agent, for example, halogen, hypohalous acid, halogenous acid or perhalogenic acid, or a salt thereof, halogen oxide, nitrogen oxide, peroxide, etc., it is possible to promote the oxidation reaction. Any oxidizing agent can be used if it exists. Sodium hypochlorite is preferred because of its ready availability and reactivity. The amount of the co-oxidant used may be an amount capable of promoting the oxidation reaction and is not particularly limited. Usually, it is 1% by mass or more and 200% by mass or less based on the solid content of the wood-based natural cellulose to be oxidized.

  Further, at least one compound selected from the group consisting of bromide and iodide may be used in combination with the N-oxyl compound and the co-oxidizing agent. This allows the oxidation reaction to proceed smoothly and improves the efficiency of introducing the carboxy group. As such a compound, sodium bromide or lithium bromide is preferable, and sodium bromide is more preferable in terms of cost and stability. The amount of the compound used may be an amount capable of promoting the oxidation reaction and is not particularly limited. Usually, it is 1% by mass or more and 50% by mass or less based on the solid content of the wood-based natural cellulose to be oxidized.

The reaction temperature of the oxidation reaction is preferably 4 ° C. or higher and 80 ° C. or lower, and more preferably 10 ° C. or higher and 70 ° C. or lower. If the reaction temperature of the oxidation reaction is lower than 4 ° C., the reactivity of the reagent tends to be low and the reaction time tends to be long. When the reaction temperature of the oxidation reaction exceeds 80 ° C., a side reaction is promoted to lower the molecular weight of cellulose as a sample, and the highly crystalline and rigid micronized cellulose structure is collapsed. As a stabilizer for an O / W emulsion. It tends to be difficult to use.
The reaction time of the oxidation treatment can be appropriately set in consideration of the reaction temperature, the desired amount of carboxy groups and the like and is not particularly limited, but is usually 10 minutes or more and 5 hours or less.

  The pH of the reaction system during the oxidation reaction is not particularly limited, but is preferably 9 or more and 11 or less. When the pH is 9 or higher, the reaction can proceed efficiently. If the pH exceeds 11, a side reaction may proceed and the decomposition of cellulose as a sample may be accelerated. Further, in the oxidation treatment, the pH in the system is lowered due to the formation of carboxy groups as the oxidation progresses. Therefore, it is preferable to keep the pH of the reaction system at 9 or more and 11 or less during the oxidation treatment. As a method of maintaining the pH of the reaction system at 9 or more and 11 or less, for example, a method of adding an alkaline aqueous solution according to the decrease in pH can be mentioned.

Examples of the alkaline aqueous solution include sodium hydroxide aqueous solution, lithium hydroxide aqueous solution, potassium hydroxide aqueous solution, ammonia aqueous solution, tetramethylammonium hydroxide aqueous solution, tetraethylammonium hydroxide aqueous solution, tetrabutylammonium hydroxide aqueous solution, and benzyltrimethylammonium hydroxide. Examples include organic alkalis such as aqueous solutions. A sodium hydroxide aqueous solution is preferable in terms of cost and the like.
The oxidation reaction by the N-oxyl compound can be stopped, for example, by adding alcohol to the reaction system. At this time, the pH of the reaction system is preferably kept within the above range. As the alcohol to be added, for example, low molecular weight alcohols such as methanol, ethanol and propanol are preferable in order to quickly complete the reaction, and ethanol is particularly preferable in terms of safety of by-products produced by the reaction.

The reaction liquid after the oxidation treatment may be directly subjected to the refining process. However, in the reaction solution after the oxidation treatment, in order to remove the catalyst such as N-oxyl compound, impurities, etc., it is preferable to recover the oxidized cellulose contained in the reaction solution and wash it with a cleaning solution. Recovery of the oxidized cellulose can be carried out by a known method such as filtration using a glass filter or a nylon mesh having a pore size of 20 μm. Pure water is preferable as the cleaning liquid used for cleaning the oxidized cellulose.
When the obtained TEMPO oxidized cellulose is subjected to a defibration treatment, cellulose single nanofibers (CSNF) having a uniform fiber width of about 3 nm are obtained. When CSNF is used as a raw material for the finely divided cellulose 1 of the composite particles 4, the particle size of the resulting O / W emulsion tends to be uniform due to its uniform structure.

As described above, the CSNF used in the present embodiment can be obtained by the step of oxidizing the cellulose raw material and the step of making the cellulosic material into a dispersion liquid.
Moreover, as content of the carboxy group introduce | transduced into CSNF, 0.1 mmol / g or more and 5.0 mmol / g or less are preferable, and 0.5 mmol / g or more and 2.0 mmol / g or less are more preferable. Here, if the amount of carboxy groups is less than 0.1 mmol / g, the solvent invasion effect due to the osmotic effect does not work between the cellulose microfibrils, so that it tends to be difficult to miniaturize and uniformly disperse the cellulose. is there. In addition, when the amount of carboxy groups exceeds 5.0 mmol / g, the molecular weight of cellulose microfibrils is lowered due to a side reaction accompanying the chemical treatment, so that a highly crystalline rigid micronized cellulose structure cannot be obtained, and O / It tends to be difficult to use as a stabilizer for W emulsions.

(Second step)
In the second step, the dispersion liquid 6 of the micronized cellulose 1 is used. Specifically, in the dispersion liquid 6, at least a part of the surface of the droplet 5 is coated with the micronized cellulose 1, and the droplet 5 Is a step of stabilizing as an emulsion.
In the second step of this embodiment, specifically, at least one kind of polymerizable monomer or polymer having no affinity for the micronized cellulose dispersion obtained in the first step was obtained in the first step. There is a step of adding it to the micronized cellulose dispersion and dispersing it as droplets 5 in the micronized cellulose dispersion. Further, the second step has a step of coating at least a part of the surface of the droplet 5 with the micronized cellulose 1 to prepare an O / W type emulsion stabilized by the micronized cellulose 1.

  Examples of the method for producing an O / W emulsion include a method in which a polymerizable monomer containing an initiator is added to a finely divided cellulose dispersion to form an emulsion, and a polymer which is solid at room temperature is added to the finely divided cellulose dispersion. A method of adding what is dissolved in a solvent with low compatibility to a micronized cellulose dispersion to form an emulsion, adding a polymer that is solid at room temperature to the micronized cellulose dispersion, and heating it to a temperature at which the polymer has fluidity or higher. There is a method of melting and emulsifying. In either method, it is preferable that the polymerizable monomer or polymer to be added is incompatible with the micronized cellulose dispersion. When they are compatible, it tends to be difficult to form polymer droplets in the micronized cellulose dispersion, and it becomes difficult to obtain a composite.

The polymerizable monomer used in the present embodiment, a polymer monomer, having a polymerizable functional group in its structure, is a liquid at room temperature, is not completely compatible with water, It is not particularly limited as long as it can form a polymer (polymer) by a polymerization reaction. The polymerizable monomer has at least one polymerizable functional group. The polymerizable monomer having one polymerizable functional group is also referred to as a monofunctional monomer. A polymerizable monomer having two or more polymerizable functional groups is also called a polyfunctional monomer. The type of polymerizable monomer is not particularly limited, but examples thereof include (meth) acrylic monomers and vinyl monomers. It is also possible to use a polymerizable monomer having a cyclic ether structure such as an epoxy group or an oxetane structure (eg, ε-caprolactone, etc.).
The expression "(meth) acrylate" indicates that both "acrylate" and "methacrylate" are included.
Alternatively, a mixture of a polymerizable monomer containing an initiator and a compound having biodegradability may be added to the micronized cellulose dispersion liquid to emulsify it to obtain stabilized droplets as an emulsion. By setting it as such an aspect, it becomes possible to provide the sustained-release composite particle which can maintain the effect of a functional component for a long period, maintaining the characteristic of a cellulose nanofiber.

  Examples of monofunctional (meth) acrylic monomers include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, n-butyl (meth) acrylate, and isobutyl. (Meth) acrylate, t-butyl (meth) acrylate, glycidyl (meth) acrylate, acryloylmorpholine, N-vinylpyrrolidone, tetrahydrofurfuryl acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isobornyl ( (Meth) acrylate, isodecyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate, benzyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 3 -Methoxybutyl (meth) acrylate, ethylcarbitol (meth) acrylate, phosphoric acid (meth) acrylate, ethylene oxide modified phosphoric acid (meth) acrylate, phenoxy (meth) acrylate, ethylene oxide modified phenoxy (meth) acrylate, propylene oxide Modified phenoxy (meth) acrylate, nonylphenol (meth) acrylate, ethylene oxide modified nonylphenol (meth) acrylate, propylene oxide modified nonylphenol (meth) acrylate, methoxydiethylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, methoxypropylene glycol (Meth) acrylate, 2- (meth) acryloyloxyethyl-2-hydroxypropyl phthalate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, 2- (meth) acryloyloxyethyl hydrogen phthalate, 2- (meth) acryloyl Oxypropylhydrogenphthalate, 2- (meth) acryloyloxypropylhexahydrohydrogenphthalate, 2- (meth) acryloyloxypropyltetrahydrohydrogenphthalate, dimethylaminoethyl (meth) acrylate, trifluoroethyl (meth) acrylate, tetrafluoropropyl ( (Meth) acrylate, hexafluoropropyl (meth) acrylate, octafluoropropyl (meth) acrylate, octafluoropropyl (meth) acrylate, 2 And adamantane derivative mono (meth) acrylates such as adamantyl acrylate having a monovalent mono (meth) acrylate derived from adamantane and adamantane diol.

  Examples of the bifunctional (meth) acrylic monomer include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, butanediol di (meth) acrylate, hexanediol di (meth) acrylate, nonanediol di (meth). ) Acrylate, ethoxylated hexanediol di (meth) acrylate, propoxylated hexanediol di (meth) acrylate, diethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, polypropylene glycol di Di () such as (meth) acrylate, neopentyl glycol di (meth) acrylate, ethoxylated neopentyl glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, and hydroxypivalic acid neopentyl glycol di (meth) acrylate. Examples thereof include (meth) acrylate.

  Examples of trifunctional or higher functional (meth) acrylic monomers include trimethylolpropane tri (meth) acrylate, ethoxylated trimethylolpropane tri (meth) acrylate, propoxylated trimethylolpropane tri (meth) acrylate, and tris2-hydroxy. Tri (meth) acrylates such as ethyl isocyanurate tri (meth) acrylate, glycerin tri (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, ditrimethylolpropane tri (meth) acrylate, etc. Trifunctional (meth) acrylate compounds, pentaerythritol tetra (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, ditrimethylolpropane penta ( (3) trifunctional or higher polyfunctional (meth) acrylate compounds such as (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and ditrimethylolpropane hexa (meth) acrylate, and a part of these (meth) acrylates as an alkyl group or ε- Examples thereof include polyfunctional (meth) acrylate compounds substituted with caprolactone.

As the monofunctional vinyl-based monomer, for example, liquids which are incompatible with water at room temperature, such as vinyl ether-based, vinyl ester-based and aromatic vinyl-based monomers, particularly styrene and styrene-based monomers are preferable.
As the (meth) acrylate among the monofunctional vinyl-based monomers, for example, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, Lauryl (meth) acrylate, alkyl (meth) acrylate, tridecyl (meth) acrylate, stearyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, isobornyl (meth) acrylate, glycidyl (meth) acrylate, tetrahydrofur Furyl (meth) acrylate, allyl (meth) acrylate, diethylaminoethyl (meth) acrylate, trifluoroethyl (meth) acrylate, heptafluorodecyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth ) Acrylate, tricyclodecanyl (meth) acrylate and the like.
Further, as the monofunctional aromatic vinyl-based monomer, styrene, for example, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, ethylstyrene, isopropenyltoluene, isobutyltoluene, tert-butylstyrene. , Vinylnaphthalene, vinylbiphenyl, 1,1-diphenylethylene and the like.

Examples of the polyfunctional vinyl-based monomer include a polyfunctional group having an unsaturated bond such as divinylbenzene. A liquid that is incompatible with water at room temperature is preferable.
For example, as the polyfunctional vinyl-based monomer, specifically, (1) divinyls such as divinylbenzene, 1,2,4-trivinylbenzene, and 1,3,5-trivinylbenzene, and (2) ethylene glycol. Dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, 1,3-propylene glycol dimethacrylate, 1,4-butylene glycol dimethacrylate, 1,6-hexamethylene glycol dimethacrylate, neopentyl glycol dimethacrylate Dimethacrylates such as methacrylate, dipropylene glycol dimethacrylate, polypropylene glycol dimethacrylate, 2,2-bis (4-methacryloxydiethoxyphenyl) propane, (3) trimethylolpropane trimethacrylate, triethylolethanetrimethacrylate, etc. Trimethacrylates, (4) ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, polyethylene glycol diacrylate, 1,3-dipropylene glycol diacrylate, 1,4-dibutylene glycol diacrylate, 1,6 -Hexylene glycol diacrylate, neopentyl glycol diacrylate, dipropylene glycol diacrylate, polypropylene glycol diacrylate, 2,2-bis (4-acryloxypropoxyphenyl) propane, 2,2-bis (4-acryloxydi) Diacrylates such as ethoxyphenyl) propane, (5) trimethylolpropane triacrylate, triacrylates such as trimethylolethane triacrylate, (6) tetraacrylates such as tetramethylolmethane tetraacrylate, (7) and others, Examples thereof include tetramethylene bis (ethyl fumarate), hexamethylene bis (acrylamide), triallyl cyanurate and triallyl isocyanurate.
Specific examples of the functional styrene-based monomer include divinylbenzene, trivinylbenzene, divinyltoluene, divinylnaphthalene, divinylxylene, divinylbiphenyl, bis (vinylphenyl) methane, bis (vinylphenyl) ethane, bis (vinyl). Examples include phenyl) propane and bis (vinylphenyl) butane.

In addition to these, it is possible to use a polyether resin, a polyester resin, a polyurethane resin, an epoxy resin, an alkyd resin, a spiro acetal resin, a polybutadiene resin, a polythiol polyene resin, or the like having at least one polymerizable functional group. However, the material is not particularly limited.
The above polymerizable monomers may be used alone or in combination of two or more.
The mixing ratio of the compound having biodegradability and the polymerizable monomer is within the range of 10/90 to 85/15, preferably 15/85, in terms of the mass ratio of the compound having biodegradability / polymerizable monomer. Within the range of 70/30. When the amount of the compound having biodegradability is less than 10, biodegradability is weak, and when the amount of the polymerizable monomer is less than 15, it tends to be difficult to form a polymer.
Further, the polymerizable monomer may contain a polymerization initiator in advance. Examples of general polymerization initiators include radical initiators such as organic peroxides and azo polymerization initiators.
Examples of the organic peroxide include peroxyketal, hydroperoxide, dialkyl peroxide, diacyl peroxide, peroxycarbonate and peroxyester.

Examples of the azo polymerization initiator include ADVN and AIBN.
For example, 2,2-azobis (isobutyronitrile) (AIBN), 2,2-azobis (2-methylbutyronitrile) (AMBN), 2,2-azobis (2,4-dimethylvaleronitrile) (ADVN) 1,1-azobis (1-cyclohexanecarbonitrile) (ACHN), dimethyl-2,2-azobisisobutyrate (MAIB), 4,4-azobis (4-cyanovalerianic acid) (ACVA), 1, 1-azobis (1-acetoxy-1-phenylethane), 2,2-azobis (2-methylbutyramide), 2,2-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2- Azobis (2-methylamidinopropane) dihydrochloride, 2,2-azobis [2- (2-imidazolin-2-yl) propane], 2,2-azobis [2-methyl-N- (2-hydroxyethyl) Propionamide], 2,2-azobis (2,4,4-trimethylpentane), 2-cyano-2-propylazoformamide, 2,2-azobis (N-butyl-2-methylpropionamide), 2,2 -Azobis (N-cyclohexyl-2-methylpropionamide) and the like.

If a polymerizable monomer containing a polymerization initiator in advance is used in the second step, the polymerization initiator is contained in the polymerizable monomer droplets 5 inside the emulsion particles when an O / W emulsion is formed. In the third step, which will be described later, the polymerization reaction easily proceeds when the monomers inside the emulsion are polymerized.
The mass ratio of the polymerizable monomer and the polymerization initiator that can be used in the second step is not particularly limited, but usually, the polymerization initiator is 0.1 part by mass or more relative to 100 parts by mass of the polymerizable monomer. Is preferred. When the amount of the polymerizable monomer is less than 0.1 parts by mass, the polymerization reaction does not proceed sufficiently and the yield of the composite particles 4 tends to decrease, which is not preferable.

Use in a method to obtain a stabilized droplet as an emulsion by dissolving a polymer that is solid at room temperature in a solvent that has low compatibility with the micronized cellulose dispersion, add it to the micronized cellulose dispersion, and emulsify it. Examples of the polymer that can be used include polymers obtained by polymerizing the above-mentioned polymerizable monomers.
Further, as the solvent for dissolving the polymer that is solid at room temperature, a solvent having low compatibility with the micronized cellulose dispersion liquid is preferable. When the solubility in water is high, the solvent easily dissolves from the polymer phase into the aqueous phase, and thus emulsification tends to be difficult. If the compound is not soluble in water, the solvent cannot move from the polymer phase, and it tends to be extremely difficult to obtain composite particles. Further, the solvent for dissolving the polymer preferably has a boiling point of 90 ° C. or lower. When the boiling point is higher than 90 ° C., the micronized cellulose dispersion liquid evaporates before the solvent that dissolves the polymer, and it tends to be extremely difficult to obtain composite particles. Specific examples of the solvent that dissolves the polymer include dichloromethane, chloroform, 1,2-dichloroethane, and benzene.

  It can be used in a method of adding a polymer that is a solid at room temperature to a micronized cellulose dispersion, heating it to a temperature at which the polymer has fluidity or higher, melting it to form an emulsion, and obtaining stabilized droplets as an emulsion. Examples thereof include polymers that are solid at room temperature and have fluidity when heated. The fluidity temperature is a melting point or a glass transition temperature. The melting point or glass transition temperature of the polymer to be added is preferably 40 ° C. or higher and 90 ° C. or lower. When the melting point or glass transition temperature of the polymer is less than 40 ° C., it is difficult to solidify at room temperature, and thus it tends to be extremely difficult to obtain a composite. Further, when the melting point or glass transition temperature of the polymer is 90 ° C. or higher, it is difficult to emulsify the water, which is a solvent of the micronized cellulose dispersion liquid to be heated together, rather than dissolving the polymer, because the water is a solvent. Tend to be.

  Therefore, as the polymer that can be used in the present embodiment, specifically, poly-S-methylheptene, polydecene, polyvinyl palmitate, polyvinyl stearate, cis-1,4-polychloroprene, it cis-1,4-poly -1,3 pentadiene, it trans-1,4-poly-1,3 hexadiene, it trans-1,4-poly-1,3 heptadiene, it trans-1,4-poly-1,3 octadiene, polyhexa Examples thereof include methylene oxide, polyoctamethylene oxide, polybutadiene oxide, polytetramethylene sulfide, polypentamethylene sulfide, polyhexamethylene sulfide, polymethylene thiotetramethylene sulfide, polyethylene thiotetramethylene sulfide, and polytrimethylene disulfide.

A compound having biodegradability may be used instead of the polymer.
Specific examples of the biodegradable compound include pentaerythritol tetrastearate, pentaerythritol distearate, pentaerythritol tristearate, stearyl stearate, batyl stearate, stearyl stearate, myristyl myristate, cetyl palmitate. , Ethylene glycol distearate, behenyl alcohol, microcrystalline wax, paraffin wax, hydrocarbon wax, fatty acid alkyl ester, polyol fatty acid ester, mixture of fatty acid ester and wax, mixture of fatty acid ester, glycerin monopalmitate (/ monoglyceride stearate), Glycerin mono distearate (/ glycerin stearate), glycerin monoaceto monostearate (/ glycerin fatty acid ester), succinic acid aliphatic monoglyceride (/ glycerin fatty acid ester), citric acid saturated aliphatic monoglyceride, sorbitan monostearate, sorbitan fatty acid Ester, sorbitan tribehenate, propylene glycol monobehenate (/ propylene glycol fatty acid ester), stearate of pentaerythritol adipic acid polymer, pentaerythritol tetrastearate, dipentaerythritol hexastearate, stearyl citrate, pentaerythritol fatty acid Ester, glycerin fatty acid ester, ultra-light rosin, rosin-containing diol, ultra-light rosin metal salt, hydrogenated petroleum resin, rosin ester, hydrogenated rosin ester, special rosin ester, novolak, crystalline poly α-olefin, polyalkylene glycol, poly The thing which has an alkylene glycol ester, a polyoxyalkylene ether, etc. as a main component is mentioned.

  Further, the core particle 3 may contain a functional component. The functional components to be contained in the core particles 3 include fragrances, deodorants, fungicides, fertilizers, pH adjusters, pesticides, plant vitalizers, plant life-prolonging agents, pest and animal repellents, soil penetrants, nutritional components. , Plant hormones, antibacterial substances and the like. When the core particle 3 contains a functional component in advance, the above-mentioned functional component can be contained inside the particles of the sustained-release composite particle 9, and the function expression according to the application can be realized.

  The mass ratio of the micronized cellulose dispersion liquid and the polymer or the mixed liquid of the polymer and the polymerizable monomer that can be used in the second step is not particularly limited, but the polymer and the polymer are polymerized with respect to 100 parts by mass of the micronized cellulose. It is preferable that the mixed liquid of the volatile monomer is 1 part or more and 50 parts or less by mass. If the amount of the polymer or the mixed liquid of the polymer and the polymerizable monomer is less than 1 part by mass, the yield of the composite particles 4 tends to decrease, which is not preferable. Further, when the polymer and the mixed liquid of the polymer and the polymerizable monomer exceed 50 parts by mass, it tends to be difficult to uniformly coat the droplet 5 with the micronized cellulose 1, which is not preferable.

  The method for producing the O / W type emulsion is not particularly limited, but a general emulsification treatment, for example, various homogenizer treatments or mechanical stirring treatments can be used, and specifically, a high pressure homogenizer, an ultrahigh pressure homogenizer, and a universal homogenizer. Mechanical treatments such as a ball mill, a roll mill, a cutter mill, a planetary mill, a jet mill, an attritor, a grinder, a juicer mixer, a homomixer, an ultrasonic homogenizer, a nanogenizer, an underwater collision, and a paint shaker. Also, a plurality of mechanical treatments may be used in combination.

For example, when using an ultrasonic homogenizer, a polymerizable monomer is added to the micronized cellulose dispersion obtained in the first step to make a mixed solvent, and the tip of the ultrasonic homogenizer is inserted into the mixed solvent for ultrasonic treatment. carry out. The processing conditions of the ultrasonic homogenizer are not particularly limited, but for example, the frequency is generally 20 kHz or higher, and the output is generally 10 W / cm ² or higher. Although the processing time is not particularly limited, it is usually about 10 seconds to 1 hour.

  By the above-mentioned ultrasonic treatment, the droplets 5 are dispersed in the micronized cellulose dispersion and the emulsion progresses, and further the micronized cellulose 1 is selectively present on the liquid / liquid interface between the droplets 5 and the micronized cellulose dispersion. By adsorbing, the droplet 5 is covered with the micronized cellulose 1 to form a stable structure as an O / W emulsion. In this way, an emulsion in which a solid substance is adsorbed and stabilized at the liquid / liquid interface is academically called a "Pickering emulsion". As described above, the mechanism by which a Pickering emulsion is formed by micronized cellulose is not clear, but since cellulose has a hydrophilic site derived from a hydroxyl group and a hydrophobic site derived from a hydrocarbon group in its molecular structure, Since it exhibits amphipathic properties, it is considered that it is derived from the amphipathic properties and adsorbs to the liquid / liquid interface between the hydrophobic monomer and the hydrophilic solvent.

The O / W type emulsion structure can be confirmed by, for example, observation with an optical microscope. The particle size of the O / W emulsion is not particularly limited, but is usually about 0.1 μm to 1000 μm.
In the O / W emulsion structure, the thickness of the micronized cellulose layer (coating layer 2) formed on the surface layer of the droplet 5 is not particularly limited, but is usually 3 nm or more and 1000 nm or less. The thickness of the micronized cellulose layer (coating layer 2) can be measured using, for example, a cryo TEM.

(Third step)
The third step is a step of solidifying the droplets 5 to obtain the composite particles 4 in which the core particles 3 are coated with the micronized cellulose 1.
More specifically, in the third step, the surface of the core particle 3 is obtained by solidifying the droplet 5 into the core particle 3 in a state where at least a part of the surface of the droplet 5 is covered with the micronized cellulose 1. Is a step of covering at least a part of the finely divided cellulose 1 with the core particles 3 and the finely divided cellulose 1 in an inseparable state.
When the method of adding a polymerizable monomer containing an initiator to the micronized cellulose dispersion in the second step and emulsifying is used, the method of polymerizing the polymerizable monomer is not particularly limited, and the method of polymerizing the polymerizable monomer used is It can be appropriately selected depending on the type and the type of the polymerization initiator. Examples of the method for polymerizing the above-mentioned polymerizable monomer include a suspension polymerization method.

  The specific suspension polymerization method is also not particularly limited, and a known method can be used. The suspension polymerization method is carried out, for example, by stirring the stabilized O / W emulsion in which the droplets 5 containing the polymerization initiator and the polymerizable monomer prepared in the second step are covered with the micronized cellulose 1 and stabilized. It can be carried out by heating while heating. The stirring method is not particularly limited, and a known method can be used, and specifically, a disper or a stirrer can be used. Alternatively, only heat treatment may be performed without stirring. The temperature condition during heating can be set as appropriate depending on the type of polymerizable monomer and the type of polymerization initiator, but is preferably 20 degrees or more and 90 degrees or less. If the temperature during heating is less than 20 degrees, the reaction rate of polymerization tends to decrease, which is not preferable. If it exceeds 90 degrees, the finely divided cellulose dispersion tends to evaporate, which is not preferable. The time to be subjected to the polymerization reaction can be appropriately set depending on the type of the polymerizable monomer and the type of the polymerization initiator, but is usually 1 hour or more and 24 hours or less. Further, the polymerization reaction may be carried out by an ultraviolet irradiation treatment which is a kind of electromagnetic wave. In addition to electromagnetic waves, particle beams such as electron beams may be used.

In the second step, when a method of dissolving a polymer that is a solid at room temperature in a solvent having low compatibility with the micronized cellulose dispersion and adding it to the micronized cellulose dispersion to form an emulsion is used, the emulsion is heated, The polymer can be solidified by volatilizing the solvent in which the polymer is dissolved. The temperature condition at the time of heating can be appropriately set depending on the type of solvent to be dissolved, but is preferably not less than the boiling point of the solvent and not more than 90 degrees. If the temperature at the time of heating is lower than the boiling point of the solvent, the solvent slows to move to the aqueous phase, and if it exceeds 90 degrees, the finely divided cellulose dispersion tends to evaporate, which is not preferable.
In the second step, when a method in which a polymer that is solid at room temperature is added to the micronized cellulose dispersion liquid and the polymer is heated to a temperature at which it has fluidity or higher to be melted to form an emulsion, the emulsion is cooled and the polymer is cooled. The polymer can be solidified by controlling the temperature below the temperature at which the polymer has fluidity.
Through the steps described above, the true spherical composite particles 4 in which the core particles 3 are coated with the micronized cellulose 1 can be produced.

The state immediately after the completion of the solidification reaction is a state in which a large amount of water and free micronized cellulose 1 that does not contribute to the formation of the coating layer 2 of the composite particles 4 are mixed in the dispersion liquid of the composite particles 4. ing. Therefore, it is necessary to collect and purify the produced composite particles 4. As a method of collecting and purifying, washing by centrifugation or washing by filtration is preferable. As the washing method by centrifugation, a known method can be used, and specifically, the operation of precipitating the composite particles 4 by centrifugation to remove the supernatant and redispersing in the water / methanol mixed solvent is repeated. The residual solvent is removed from the precipitate obtained by the centrifugal separation to recover the composite particles 4. A known method can also be used for filtration and washing. For example, a PTFE membrane filter having a pore size of 0.1 μm is used and suction filtration is repeated with water and methanol to finally remove residual solvent from the paste remaining on the membrane filter. The composite particles 4 are removed and collected.
The method for removing the residual solvent is not particularly limited, and for example, it can be carried out by air drying or heat drying in an oven. The dried solid matter containing the composite particles 4 thus obtained does not form a film or an aggregate as described above, and is obtained as a finely textured powder.

(Fourth step)
The fourth step is a step in which a functional component can be added to the micronized cellulose 1 that covers the surface of the core particles 3.
By mixing the functional component with the composite particles 4 and adsorbing the functional component on the micronized cellulose, the functional component can be added to the micronized cellulose. Further, the coating layer 2 made of the finely divided cellulose 1 has a fine network structure in which the finely divided cellulose 1 is overlapped. Therefore, the functional component is adsorbed to the micronized cellulose 1 and the functional component intrudes and is carried in the fine mesh, so that the sustained release of the functional component in the composite particles is improved.
The functional component may be mixed with the composite particles 4 as it is, but when it is difficult to mix, the functional particles may be mixed with a solvent having an affinity for the composite particles 4 and the functional component. After imparting the functional component, the surplus functional component is removed by centrifugation or filtration to obtain the sustained-release composite particles 9 to which the functional component is imparted.

The functional component contained in the micronized cellulose 1 that coats the surface of the core particles 3 is not particularly limited, and examples thereof include perfume, deodorant, fungicide, fertilizer (biological fertilizer, chemical fertilizer, organic fertilizer, etc.), pH adjusters, pesticides (insecticides, fungicides, herbicides, etc.), plant vitalizers, plant life-prolonging agents, pest and animal repellents, soil penetrants, nutrients (minerals, etc.), plant hormones, inorganic particles (oxidation Titanium, silica, clay, etc.), antibacterial substances and the like.
By using the sustained-release composite particles 9 of the present embodiment as described above, it is possible to reduce the amount of CNF dispersion used and reduce the load on the environment.

  As the fragrance, there are natural fragrances extracted from animals and plants, chemically synthesized fragrances, and mixed fragrances prepared by mixing a plurality of kinds of fragrances. Among these, as natural flavors, for example, jasmine, rose, carnation, lilac, cyclamen, lily of the valley, violet, lavender, flowers such as oysters, orange, lemon, citrus such as lime, cinnamon, nutmeg and other spices, cypress essential oil, Examples thereof include wood essential oils such as Hiba essential oil and Japanese cedar essential oil. Examples of the synthetic fragrance include hydrocarbons such as limonene, pinene and camphene, linalool, geraniol, menthol, citronellol, alcohols such as benzyl alcohol, citral, citronellal, nonadienal, aldehydes such as benzaldehyde and cinnamic aldehyde, acetophenone, Ketones such as methylacetophenone, methylnonylketone, iron and menthone, phenols such as methylanisole and eugenol, lactones such as decalactone, nonyllactone and undecalactone, linalyl acetate, geranyl acetate, benzyl acetate, terpinyl acetate, acetic acid Examples thereof include esters such as citronellyl, methyl benzoate, ethyl benzoate, isoamyl benzoate, benzyl benzoate, methyl cinnamate and ethyl cinnamate.

  As the deodorant, diphenols such as catechol, 4-methylcatechol, 5-methylcatechol, resorcinol, 2-methylresorcinol, 5-methylresorcinol and hydroquinone; 4,4′-biphenyldiol, 3,4 Biphenyl diols such as'-biphenyl diol; catechins such as catechin, epicatechin, epigallocatechin, and epicatechin gallate; catechol derivatives such as dopa, dopamine, chlorogenic acid, caffeic acid, paracoumaric acid, and tyrosine. Plant-derived polyphenols extracted from plants; examples include coffee, apple, grape, teas (green tea, roasted tea, black tea, oolong tea, mate tea, etc.), persimmon, soybean, cacao, rosemary, aloe, etc. ..

Examples of pesticides include insecticides, fungicides, herbicides, insecticides, plant growth regulators, attractants and repellents.
Insecticides include azoxybenzene, anabasine, alamite, aldrin, allethrin, isoxathion, isothioate, ethione, ethyl thiomethone, endrin, orthodichlorobenzene, carbam, cartap, calvinphos, chlorpicrin, chlorpyrifos, chlorphenamidine, chlorpropyrate, chlor. Benzylate, chloromethanesulfonic acid amide, sodium fluorosilicate, quelsen, salicione, ethylene oxide, propylene oxide, geoallyl, dioxacarb, dimethoate, methyl bromide, tricyclohexyltin hydroxide, tarbam, diazinon, thiomethone, tetradiphone, terodrine , Bamidothione, Calcium arsenate, Lead arsenate, Prochronol, Propaphos, Promecarb, Benzoepine, Benzomate, Phosalone, Formothione, Mecarbam, Mesomil, Methaldehyde, Methyldimetone, Menazone, Methyl iodide, Zinc phosphide, Aluminum phosphide, APC, DDVP, MEP, PMP, etc. are mentioned.

  Examples of fungicides include ambam, sulfur, echlomezol, triphenyltin chloride, tripropyltin chloride, nickel chloride, benzalkonium chloride, basic copper chloride, basic copper sulfate, captan, guanidine, griseofulvinne, chloramphenicol. , Triphenyltin acetate, tributyltin acetate, nickel acetate, sodium hypochlorite, diclozoline, cycloheximide, dicron, dithianon, zineb, dimethylambam, diram, triphenyltin hydroxide, streptomycin, cellocidin, difortane, thiadiazine, thiabendazole. , Thiophanate, thiophanate methyl, triazine, nitrostyrene, novobiocin, validamycin, hydroxyisoxazole, farbum, folpet, propikel, propineb, benomyl, polyoxine, polycarbamate, formaldehyde, manzeb, manneb, methylam, MAF, PCP and the like. ..

  Herbicides include ioxynil, adiprothrin, ashram, atrazine, ametrine, alachlor, sodium ethylxanthate, calcium chlorate, sodium chlorate, oxadiazone, cledazine, clotizole, clomethoxynil, sodium cyanate, diquat, ciduron, diphenamide, Cimetrin, ammonium sulfamate, terbacil, desmethrin, tetrapion, triethazine, trifluralin, nitraline, vernalate, paracholate, picloram, picloram, phenothiole, phenmedipham, butachlor, propisamide, bromacil, promethrin, bethrozine, pebrate, molinate, linuron, linuron. Copper sulfate, lenacyl, ACN, DBN, etc. are mentioned.

Examples of the rodenticide include antu, yellow phosphorus, chlorofacinone, thallium acetate, silyloside, thiosemicarbazide, sodium monofluoroacetate, thallium sulfate, zinc phosphide and the like.
Examples of the plant growth regulator include indole butyric acid, ooxyethylene rapeseed oil alcohol, orthonitrophenol, gibberellin, α-naphthylacetamide, polybutene, maleic acid hydrazide, α-methoxymethylnaphthalene, and oxyquinoline sulfate.
Examples of the attractant, repellent, and the like include churure, cresol, ferric oxide, diallyl disulfide, cycloheximide, quicklime, calcium carbonate, thiuram, tetrahydrothiophene, β-nautol, methyleugenol and the like.

Examples of fertilizers include urea, potassium sulfate, potassium phosphate, potassium chloride, ammonium sulfate, ammonium phosphate, ammonium nitrate, ammonium chloride and the like. In particular, it is preferable to use a chemical slow-release fertilizer. Chemically slow-acting fertilizers are mainly those that have been chemically treated to suppress the solubility of nitrogen fertilizers. It is difficult to dissolve in water and is slowly converted to inorganic nitrogen in the soil to exert a fertilizer effect. By incorporating the chemical slow-release fertilizer in the composite particles 4, the fertilization effect can be further controlled.
As the chemical slow-release fertilizer, for example, ureaform (UF) made from urea and aldehydes as raw materials, methylolurea, acetaldehyde condensed urea (CDU), isobutyraldehyde condensed urea (IB), glyoxal condensed urea, and lime nitrogen are used as raw materials. Examples include guanylurea sulfate, oxalic acid diester, and oxamide prepared from ammonia.

(Effects of the embodiment)
The sustained-release composite particle 9 according to the present embodiment can maintain the characteristics of the micronized cellulose 1 on the surface of the sustained-release composite particle 9 while maintaining the effect of the functional component for a long period of time, and is easy to handle. It is a new sustained-release composite particle.
Further, a dry solid (dry powder) containing the sustained-release composite particles 9 according to the present embodiment is obtained as a finely textured powder, and particles do not aggregate. Therefore, it is easy to redisperse the sustained-release composite particles 9 obtained as a dry powder in the solvent again, and even after the redispersion, the finely divided cellulose 1 bonded to the surface of the sustained-release composite particles 9 can be obtained. It shows the dispersion stability derived from the coating layer.

Further, according to the method for producing sustained-release composite particles 9 according to the present embodiment, it is possible to provide a novel method for producing sustained-release composite particles 9 that can be provided by a simple method.
Further, according to the dry solid matter (dry powder) containing the composite of the micronized cellulose 1 according to the present embodiment, the dry solid matter can be provided in the solvent in a redispersible form.
Further, according to the sustained-release composite particles 9 of the present embodiment, most of the solvent can be removed, so that the transportation cost can be reduced, the risk of spoilage can be reduced, the efficiency of addition as an additive can be improved, and the hydrophobic resin can be used. The effect of improving the kneading efficiency can be expected.

  Although the embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and includes design changes and the like without departing from the scope of the present invention. Further, the constituent elements shown in the above-described first embodiment and modification can be appropriately combined and configured.

Hereinafter, the present invention will be described in detail based on examples, but the technical scope of the present invention is not limited to these examples. In each of the following examples, "%" indicates mass% (w / w%) unless otherwise specified.
<Example 1>
(First step: a step of obtaining a cellulose nanofiber dispersion liquid)
(TEMPO oxidation of wood cellulose)
70 g of softwood kraft pulp was suspended in 3500 g of distilled water, a solution of 0.7 g of TEMPO and 7 g of sodium bromide in 350 g of distilled water was added, and the mixture was cooled to 20 ° C. 450 g of an aqueous solution of sodium hypochlorite having a concentration of 2 mol / L and a density of 1.15 g / mL was added dropwise thereto to start an oxidation reaction. The temperature in the system was always kept at 20 ° C., and the decrease in pH during the reaction was kept at pH 10 by adding 0.5N sodium hydroxide aqueous solution. When the total amount of sodium hydroxide added to the mass of cellulose reached 3.50 mmol / g, about 100 mL of ethanol was added to stop the reaction. Then, filtration washing with distilled water was repeated using a glass filter to obtain oxidized pulp.

(Measurement of carboxy group content of oxidized pulp)
Oxidized pulp and reoxidized pulp obtained by the above TEMPO oxidation were weighed in an amount of 0.1 g in terms of solid content and dispersed in water at a concentration of 1%, and hydrochloric acid was added to adjust the pH to 2.5. Then, the amount of carboxy groups (mmol / g) was determined by the conductivity titration method using a 0.5 M aqueous sodium hydroxide solution. The result was 1.6 mmol / g.

(Defibration process of oxidized pulp)
1 g of oxidized pulp obtained by the above-mentioned TEMPO oxidation was dispersed in 99 g of distilled water, and finely treated with a juicer mixer for 30 minutes to obtain a CSNF aqueous dispersion having a CSNF concentration of 1%. The CSNF dispersion was put in a quartz cell having an optical path length of 1 cm, and a spectral transmission spectrum was measured using a spectrophotometer (“UV-3600” manufactured by Shimadzu Corporation). The result is shown in FIG.
As is clear from FIG. 3, the CSNF aqueous dispersion showed high transparency. Further, the number average minor axis diameter of CSNF contained in the CSNF aqueous dispersion was 3 nm, and the number average major axis diameter was 1110 nm. Furthermore, steady-state viscoelasticity measurement was performed using a rheometer. The result is shown in FIG. As is clear from FIG. 4, the CSNF dispersion showed thixotropic properties.

(Second step: Step of producing O / W emulsion)
Next, 1 g of 2,2-azobis-2,4-dimethylvaleronitrile (hereinafter, also referred to as ADVN), which is a polymerization initiator, with respect to 10 g of divinylbenzene (hereinafter, also referred to as DVB), which is a polymerizable monomer. Dissolved. When the entire amount of the DVB / ADVN mixed solution was added to 40 g of the CSNF dispersion having a CSNF concentration of 1%, the DVB / ADVN mixed solution and the CSNF dispersion were separated into two layers in a highly transparent state.
Next, the shaft of the ultrasonic homogenizer was inserted from the liquid surface of the upper layer in the mixed liquid in which the two layers were separated, and the ultrasonic homogenizer treatment was performed for 3 minutes under the conditions of a frequency of 24 kHz and an output of 400 W. The appearance of the mixed solution after the treatment with the ultrasonic homogenizer was in the form of a cloudy emulsion. One drop of the mixed solution was dropped on a slide glass, enclosed with a cover glass, and observed with an optical microscope. As a result, countless emulsion droplets of about 1 to several μm were generated and the dispersion was stabilized as an O / W emulsion. Was confirmed.

(Third step: a step of obtaining composite particles 4 coated with CNF by a polymerization reaction)
The O / W type emulsion dispersion was subjected to a water bath at 70 ° C. using a water bath and treated for 8 hours while stirring with a stir bar to carry out a polymerization reaction. After 8 hours of treatment, the dispersion was cooled to room temperature. There was no change in the appearance of the dispersion before and after the polymerization reaction. The obtained dispersion liquid was treated with a centrifugal force of 75,000 g (g is gravitational acceleration) for 5 minutes to obtain a precipitate. The supernatant was removed by decantation to collect the precipitate, which was then repeatedly washed with pure water and methanol using a PTFE membrane filter with a pore size of 0.1 μm. The purified / recovered material thus obtained was redispersed at a concentration of 1%, and the particle size was evaluated using a particle size distribution meter (NANOTRAC UPA-EX150, Nikkiso Co., Ltd.). As a result, the average particle size was 2.1 μm. Next, the purified / collected product was air-dried and further vacuum-dried at room temperature of 25 ° C. for 24 hours to obtain a dry powder (composite particles 4) having a fine texture.

(Fourth step: a step of adding a functional component to the coating layer of the composite particles 4)
5 g of the obtained composite particles was added to an aqueous solution obtained by mixing 20 g of water with a solution of 2 g of limonene as a fragrance in 10 g of methanol and mixed for 24 hours while stirring with a magnetic stirrer. The composite particles immersed in the aqueous solution were filtered using a PTFE membrane filter having a pore size of 0.1 μm, and the collected product was air-dried for 48 hours to obtain sustained-release composite particles 9.

(Shape observation with a scanning electron microscope)
The results of observing the obtained dry powder with a scanning electron microscope are shown in FIGS. 5 and 6. As is clear from FIG. 5, the O / W type emulsion droplets were used as a template to carry out the polymerization reaction, so that a myriad of spherical sustained-release composite particles 9 derived from the shape of the emulsion droplets were formed. Was confirmed. Further, as shown in FIG. 6, it was confirmed that the surface was uniformly covered with CNF having a width of several nm. In addition, the surface of the sustained-release composite particles 9 is uniformly and uniformly coated with the micronized cellulose 1 even though it is repeatedly washed by filtration. As described above, in the sustained-release composite particle 9 according to the present invention, the core particle 3 inside the sustained-release composite particle 9 and the CNF which is the micronized cellulose 1 may be bound to each other, and the core particle 3 and the fine particles 3 It was shown that the cellulose and the cellulose 1 are inseparable.

(Evaluation of redispersibility)
When the dry powder of sustained-release composite particles 9 of Example 1 was added to pure water at a concentration of 1% and redispersed with a stirrer, it was easily redispersed and no aggregation was observed. When the particle size was evaluated using a particle size distribution meter, the average particle size was 2.1 μm as before drying, and there was no signal indicating aggregation in the data of the particle size distribution meter.
From the above, the sustained-release composite particles 9 according to the present invention can be obtained as powder without being formed into a film by drying and have good redispersibility even though the surface thereof is coated with CNF. It was shown that.

<Example 2>
Example 2 was carried out under the same conditions as in Example 1 except that diethylene glycol diacrylate (trade name FA-222A, Hitachi Chemical Co., Ltd., hereinafter also referred to as FA-222A) was used in place of DVB. The sustained-release composite particles 9 according to 1 above were produced and various evaluations were performed in the same manner.
<Example 3>
The same as Example 1 except that the phosphoric acid esterified CNF dispersion liquid obtained by performing the phosphoric acid esterification treatment according to Non-Patent Document 1 cited as the prior art document was used instead of the TEMPO oxidation in Example 1. Under the conditions of, the sustained-release composite particles 9 according to Example 3 were produced, and various evaluations were performed in the same manner.

<Example 4>
As a polymer forming the core particles 3, 6 g of polystyrene (hereinafter referred to as PS) was dissolved in 4 g of dichloromethane (boiling point: 39.6 ° C.). The total amount of the polylactic acid / dichloromethane mixed solution was added to 40 g of the CSNF dispersion liquid used in Example 1.
Next, the above-mentioned mixed liquid was subjected to an ultrasonic homogenizer treatment for 3 minutes under the conditions of a frequency of 24 kHz and an output of 400 W in the same manner as in Example 1 to obtain an O / W type emulsion dispersion liquid.
Next, the O / W type emulsion dispersion was placed in a hot water bath at 70 ° C. using a water bath and treated for 8 hours while stirring with a stirrer to volatilize dichloromethane. After the treatment for 8 hours, the above dispersion liquid was treated in the same manner as in Example 1 to obtain a dry powder (composite particles 4).
Next, 5 g of the obtained composite particles were added to an aqueous solution obtained by mixing 20 g of water with a solution of 2 g of limonene dissolved in 10 g of methanol, and mixed for 24 hours while stirring with a magnetic stirrer. The composite particles immersed in the aqueous solution were filtered using a PTFE membrane filter having a pore size of 0.1 μm, and the collected product was air-dried for 48 hours to prepare sustained release composite particles 9 according to Example 4, and various evaluations were performed in the same manner. Carried out.

<Example 5>
Sustained release according to Example 5 under the same conditions as in Example 4 except that polymethyl methacrylate (hereinafter, also referred to as PMMA) was used in place of PS and chloroform was used in place of dichloromethane. Composite particles 9 were prepared and various evaluations were performed in the same manner.

<Example 6>
As a polymer forming the core particles 3, 10 g of polyhexamethylene oxide (hereinafter, also referred to as PHMO, melting point: 58 ° C.) was added to 40 g of the CSNF dispersion liquid used in Example 1.
Next, the above mixed solution was heated to 80 ° C. using a water bath to melt PHMO, and then subjected to ultrasonic homogenizer treatment for 3 minutes under the conditions of a frequency of 24 kHz and an output of 400 W as in Example 1. , An O / W type emulsion dispersion was obtained.
Next, the O / W emulsion dispersion was cooled to room temperature.
Finally, the dispersion was treated in the same manner as in Example 1 to obtain a dry powder (composite particles 4).
Next, 5 g of the obtained composite particles were added to an aqueous solution obtained by mixing 20 g of water with a solution of 2 g of limonene dissolved in 10 g of methanol, and mixed for 24 hours while stirring with a magnetic stirrer. The composite particles immersed in the aqueous solution were filtered using a PTFE membrane filter having a pore size of 0.1 μm, and the collected product was air-dried for 48 hours to prepare sustained-release composite particles 9 according to Example 6, and various evaluations were performed in the same manner. Carried out.

<Example 7>
The sustained release composite particles 9 according to Example 7 were prepared under the same conditions as in Example 1 except that epigallocatechin (derived from green tea) was used as the deodorant in place of limonene as the fragrance in Example 1. It was produced and various evaluations were performed in the same manner.
<Example 8>
In place of TEMPO oxidation in Example 7, a CM-modified CNF dispersion liquid obtained by performing a carboxymethylation (hereinafter, also referred to as CM conversion) treatment according to Patent Document 2 cited as a prior art document was used. Under the same conditions as in Example 7, sustained-release composite particles 9 according to Example 8 were produced and various evaluations were performed in the same manner.

<Comparative Example 1>
An attempt was made to produce sustained-release composite particles 9 according to Comparative Example 1 under the same conditions as in Example 1 except that pure water was used instead of the CSNF dispersion liquid in Example 1.
<Comparative example 2>
An attempt was made to produce sustained-release composite particles 9 according to Comparative Example 1 under the same conditions as in Example 2 except that an aqueous solution of carboxymethyl cellulose (hereinafter also referred to as CMC) was used in place of TEMPO oxidation in Example 1. It was
<Comparative example 3>
The sustained-release composite particles 9 according to Comparative Example 3 were prepared under the same conditions as in Example 1 except that an 8% aqueous solution of polyvinyl alcohol (hereinafter, also referred to as PVA) was used in place of the CSNF dispersion liquid in Example 1. Tried to make.

<Comparative example 4>
Preparation of sustained-release composite particles 9 according to Comparative Example 4 under the same conditions as in Example 1 except that a commercially available polystyrene particle (trade name: Estapol, Corefront) was used at a concentration of 1%. Tried.
<Comparative Example 5>
An attempt was made to produce sustained-release composite particles 9 according to Comparative Example 5 under the same conditions as in Example 4 except that xylene (boiling point: 144 ° C.) was used instead of dichloromethane in Example 4.
<Comparative example 6>
The sustained-release composite according to Comparative Example 6 was used under the same conditions as in Example 6 except that polybutyl acrylate (glass transition temperature: −54 ° C., melting point: 48 ° C.) was used instead of PHMO in Example 6. Attempts were made to produce particles 9.

<Comparative Example 7>
Sustained release according to Comparative Example 6 under the same conditions as in Example 7 except that polycarbonate (hereinafter, also referred to as PC. Glass transition temperature: 150 ° C., melting point: 250 ° C.) was used instead of PHMO in Example 6. Attempts were made to prepare the hydrophilic composite particles 9.
<Comparative Example 8>
Sustained release composite particles 9 according to Comparative Example 8 under the same conditions as in Example 10 except that a 5% aqueous solution of sodium lauryl sulfate (hereinafter, also referred to as SLS) was used in place of the CSNF dispersion liquid in Example 10. I tried to make.
<Example 9>
In the second step of Example 1, 3 g of cellulose acetate butyrate (trade name CAB-55 1-0.2 or less, also referred to as CAB), which is a compound having biodegradability, and 7 g of DVB were used as polymerization initiators. One gram of ADVN was dissolved. Except for the step of adding the total amount of the CAB / DVB / ADVN mixed solution to 40 g of CSNF dispersion liquid having a CSNF concentration of 1%, the sustained-release composite particles 9 according to Example 9 were produced under the same conditions as in Example 1. I tried.

<Example 10>
In Example 9, polybutylene succinate (trade name BioPBS, Mitsubishi Chemical, hereinafter also referred to as PBS) instead of CBA, and diethylene glycol diacrylate (trade name FA-222A, Hitachi Chemical, hereinafter, FA-222A) instead of DVB. (Hereinafter also referred to as "."), The sustained-release composite particles 9 according to Example 10 were produced under the same conditions as in Example 9, and various evaluations were similarly performed.
<Example 11>
The same as Example 9 except that the phosphoric acid esterified CNF dispersion liquid obtained by performing the phosphoric acid esterification treatment according to Non-Patent Document 1 cited as the prior art document was used instead of the TEMPO oxidation in Example 9. Under the conditions of, the sustained-release composite particles 9 according to Example 11 were produced, and various evaluations were performed in the same manner.

<Example 12>
As a compound having biodegradability, 6 g of polylactic acid (trade name: Terramac TE4000, hereinafter referred to as PLA) was dissolved in 4 g of dichloromethane (boiling point: 39.6 ° C.). The total amount of the polylactic acid / dichloromethane mixed solution was added to 40 g of the CSNF dispersion liquid used in Example 1.
Next, the above-mentioned mixed liquid was subjected to an ultrasonic homogenizer treatment for 3 minutes under the conditions of a frequency of 24 kHz and an output of 400 W in the same manner as in Example 1 to obtain an O / W type emulsion dispersion liquid.
Next, the O / W type emulsion dispersion was placed in a hot water bath at 70 ° C. using a water bath and treated for 8 hours while stirring with a stirrer to volatilize dichloromethane. After the treatment for 8 hours, the above dispersion liquid was treated in the same manner as in Example 1 to obtain a dry powder (composite particles 4).
Next, 5 g of the obtained composite particles were added to an aqueous solution obtained by mixing 20 g of water with a solution of 2 g of limonene dissolved in 10 g of methanol, and mixed for 24 hours while stirring with a magnetic stirrer. The composite particles immersed in the aqueous solution were filtered using a PTFE membrane filter having a pore size of 0.1 μm, and the collected product was air-dried for 48 hours to prepare sustained release composite particles 9 according to Example 4, and various evaluations were performed in the same manner. Carried out.

<Example 13>
Example 12 was carried out under the same conditions as in Example 12, except that polycaprolactone (trade name: TONE, UCC, hereinafter also referred to as PCL) was used in place of polylactic acid, and chloroform was used in place of dichloromethane. The sustained-release composite particle 9 according to No. 13 was produced, and various evaluations were performed in the same manner.

<Example 14>
As a compound having biodegradability, 10 g of stearic acid (melting point: 69.6 ° C.) was added to 40 g of the CSNF dispersion liquid used in Example 9.
Next, the mixed solution was heated to 80 ° C. using a water bath to melt the stearic acid, and then subjected to ultrasonic homogenizer treatment for 3 minutes under the conditions of a frequency of 24 kHz and an output of 400 W as in Example 1. Conducted to obtain an O / W type emulsion dispersion.
Next, the O / W emulsion dispersion was cooled to room temperature.
Finally, the dispersion was treated in the same manner as in Example 9 to obtain a dry powder (composite particles 4).
Next, 5 g of the obtained composite particles were added to an aqueous solution obtained by mixing 20 g of water with a solution of 2 g of limonene dissolved in 10 g of methanol, and mixed for 24 hours while stirring with a magnetic stirrer. The composite particles immersed in the aqueous solution were filtered using a PTFE membrane filter having a pore size of 0.1 μm, and the collected product was air-dried for 48 hours to prepare sustained-release composite particles 9 according to Example 14, and various evaluations were performed in the same manner. Carried out.

<Example 15>
The same as Example 14 except that paraffin wax (trade name: paraffin wax 135 ° F., melting point: 57.2 ° C., Sankei Sangyo Co., Ltd., hereinafter also referred to as paraffin) was used in place of stearic acid. Under the conditions of, the sustained-release composite particles 9 according to Example 15 were produced, and various evaluations were performed in the same manner.
<Example 16>
The sustained release composite particles 9 according to Example 16 were prepared under the same conditions as in Example 1 except that epigallocatechin (derived from green tea) was used as the deodorant in place of limonene as the fragrance in Example 9. It was produced and various evaluations were performed in the same manner.

<Example 17>
In place of the TEMPO oxidation in Example 16, a CM-modified CNF dispersion liquid obtained by performing a carboxymethylation (hereinafter, also referred to as CM conversion) treatment according to Patent Document 2 cited as a prior art document was used. Under the same conditions as in Example 16, sustained-release composite particles 9 according to Example 17 were produced and various evaluations were performed in the same manner.
<Comparative Example 9>
An attempt was made to produce sustained-release composite particles 9 according to Comparative Example 9 under the same conditions as in Example 10 except that pure water was used instead of the CSNF dispersion liquid in Example 10.
<Comparative Example 10>
An attempt was made to produce sustained-release composite particles 9 according to Comparative Example 10 under the same conditions as in Example 10 except that an aqueous solution of carboxymethyl cellulose (hereinafter also referred to as CMC) was used in place of TEMPO oxidation in Example 10. It was

<Comparative Example 11>
The sustained release composite particles 9 according to Comparative Example 11 were prepared under the same conditions as in Example 10 except that an 8% aqueous solution of polyvinyl alcohol (hereinafter, also referred to as PVA) was used in place of the CSNF dispersion liquid in Example 10. Tried to make.
<Comparative Example 12>
Comparative Example 12 was prepared under the same conditions as in Example 9 except that a dispersion liquid in which commercially available polylactic acid microparticles (trade name Trepal PLA, Toray) was dispersed at a 1% concentration was used instead of the composite particles of the present invention. Attempts were made to produce the release composite particles 9.
<Comparative Example 13>
An attempt was made to produce sustained-release composite particles 9 according to Comparative Example 13 under the same conditions as in Example 13 except that xylene (boiling point 144 ° C.) was used instead of dichloromethane in Example 13.
<Comparative Example 14>
Preparation of sustained-release composite particles 9 according to Comparative Example 14 was attempted under the same conditions as in Example 15 except that oleic acid (melting point: 13.4 ° C.) was used instead of stearic acid in Example 15. ..

<Comparative Example 15>
Comparison was carried out under the same conditions as in Example 15 except that an amide wax (trade name ITOHWAX-J630, melting point: 135 ° C., Sankei Sangyo, hereinafter referred to as ITOWAX) was used in place of stearic acid in Example 15. An attempt was made to produce sustained release composite particles 9 according to Example 15.
<Comparative Example 16>
Sustained-release composite particles 9 according to Comparative Example 16 were subjected to the same conditions as in Example 18, except that a 5% aqueous solution of sodium lauryl sulfate (hereinafter, also referred to as SLS) was used in place of the CSNF dispersion liquid in Example 18. I tried to make.

The evaluation results using the above Examples and Comparative Examples are summarized in Tables 1 to 4 below.
Table 1 shows examples and comparative examples in which limonene was used as a perfume as a functional component for composite particles having a polymerizable monomer or polymer as a core particle.
Table 2 shows examples and comparative examples in which epigallocatechin was used as a deodorant as a functional component for composite particles having a polymerizable monomer or polymer as a core particle.
Table 3 shows Examples and Comparative Examples in which limonene was used as the perfume as a functional component for the composite particles having the biodegradable resin as the core particles.
Table 4 shows Examples and Comparative Examples in which epigallocatechin was used as the deodorant as the functional component for the composite particles having the biodegradable resin as the core particles.

In addition, in Tables 1 to 4, the emulsion stabilizer is an additive used for stabilizing the O / W emulsion in the second step, and for example, the micronized cellulose in the present embodiment. 1 corresponds.
〔Evaluation criteria〕
In Tables 1 and 3, the possibility of the second step was determined as follows.
◯: O / W type emulsion can be formed. X: O / W type emulsion cannot be formed. Whether or not the third step was possible was determined as follows.
◯: True spherical particles that were used as the emulsion template in the third step were obtained. X: The above particles were not obtained. Redispersibility was determined as follows.
◯: The obtained sustained-release composite particles were dispersed in the solvent (water) without agglomeration ×: Agglomerated without dispersion

Regarding the evaluation of fragrance, 1 g of the sustained-release composite particles was put into a 500 ml Erlenmeyer flask and allowed to stand for 24 hours in an atmosphere of temperature of 25 ° C. and humidity of 50%. An evaluation was made.
○: Aroma can be felt from inside the flask ×: Aroma cannot be felt from inside the flask

Further, regarding the evaluation of deodorant property, 1 g of the sustained-release composite particles and 0.1 g of ammonia were put into a 500 ml Erlenmeyer flask, the flask was covered with a lid, and the flask was left standing for 2 hours in a sealed state. Was smelled and the deodorant property was evaluated.
◯: Ammonia odor cannot be felt from inside the flask ×: Ammonia odor can be felt from inside the flask

In addition, the hatched notation in each cell in the comparative examples in Tables 1 and 3 indicates that the process cannot be performed during the process, and the subsequent process is not performed.
As is clear from the evaluation results of Examples 1 to 6 in Table 1, aroma is imparted regardless of the type of the micronized cellulose 1 (TEMPO-oxidized CNF, phosphoric acid esterified CNF) or the type of core particles. It was confirmed that the sustained-release composite particles 9 described above can be produced, and the solution of the problems in the present invention is successful.

As is clear from the evaluation results of Examples 8 to 15 in Table 3, biodegradability is exhibited irrespective of the type of finely divided cellulose 1 (TEMPO-oxidized CNF, phosphate esterified CNF) or the type of core particles. Then, it was confirmed that the sustained-release composite particles 9 imparted with aroma could be prepared, and that the solution of the problem in the present invention was successful.
On the other hand, in Comparative Examples 1 and 9, the second step could not be performed. Specifically, even if the ultrasonic homogenizer treatment was performed, the monomer layer and the CNF dispersion liquid layer remained in a separated state of two layers, and it was impossible to produce the O / W emulsion itself.

  Further, in Comparative Examples 2 and 10, it was possible to form the O / W type emulsion in the second step. It is considered that this was because CMC exhibited an amphipathic property like micronized cellulose, and thus functioned as a stabilizer for the emulsion. However, when the polymerization reaction was carried out in the subsequent third step, the emulsion collapsed, and composite particles using the O / W emulsion as a template could not be obtained. The reason for this is not clear, but since CMC is water-soluble, it is highly likely that it is fragile as a coating layer for maintaining the emulsion shape during the polymerization reaction, and therefore, the emulsion collapsed during the polymerization reaction. Conceivable.

Further, in Comparative Examples 3 and 11, the polymer could be polymerized in the third step and could be recovered as a powder, but the obtained powder had poor redispersibility and aroma.
Further, in Comparative Example 4, although commercially available PS fine particles having a similar structure and not coated with CNF were used, it was not possible to observe a state in which finely divided cellulose was coated on the surface of the fine particles by observing the shape by SEM. ..
Further, in Comparative Example 12, although commercially available PLA fine particles having a similar structure and not coated with CNF were used, it was not possible to observe a state in which fine particle cellulose was coated on the surface of the fine particles by observing the shape by SEM. ..

Further, in Comparative Example 5 and Comparative Example 13, it was possible to form the O / W emulsion in the second step. However, in removing xylene in the third step, since the CNF dispersion liquid uses water, the temperature cannot be higher than the boiling point of xylene, so that the droplet 5 cannot be solidified and the composite particle 4 cannot be solidified. Couldn't get
In Comparative Example 6, it was possible to form the O / W emulsion in the second step. However, in the third step, even when cooled to room temperature, polybutyl acrylate did not solidify, the droplet 5 could not be solidified, and the composite particle 4 could not be obtained.

Further, in Comparative Example 14, it was possible to form the O / W type emulsion in the second step. However, oleic acid did not solidify even when cooled to room temperature in the third step, the droplet 5 could not be solidified, and the composite particle 4 could not be obtained.
Further, in Comparative Example 7, since the temperature cannot be higher than the boiling point of water used in the CNF dispersion liquid in the second step and PC cannot be melted, an O / W emulsion is formed. I couldn't.

Further, in Comparative Example 15, the temperature cannot be higher than the boiling point of water used for the CNF dispersion liquid in the second step, and ITOWAX cannot be melted, so that an O / W emulsion is formed. I couldn't.
As is clear from the evaluation results of Examples 7 and 8 and Examples 15 and 16 in Tables 2 and 4, the deodorant property was not affected by the type of the micronized cellulose 1 (TEMPO-oxidized CNF, CM-modified CNF). It was confirmed that the sustained-release composite particles 9 provided with No. 1 can be produced, and the solution of the problems in the present invention is successful.
On the other hand, in Comparative Examples 8 and 15, the polymer could be polymerized in the third step and recovered as a powder, but the obtained powder had poor redispersibility and deodorant properties.

  The sustained-release composite particles of the present invention are preferable from the viewpoint of industrial implementation, such that the addition efficiency as an additive and the kneading efficiency with a resin are improved, and also contribute to cost reduction from the viewpoint of improving transport efficiency and preventing decay. The effect is obtained. Further, the present composite particles can be added with a functional component by utilizing the characteristics of the finely divided cellulose on the surface of the particles. , Plant life-prolonging agents, pest and animal repellents, soil penetrants, nutritional components, plant hormones, antibacterial substances, etc.

1 Micronized Cellulose 2 Coating Layer 3 Core Particle 4 Composite Particle 5 Droplet (Polymerizable Monomer Droplet, Polymer Droplet)
6 dispersion liquid 7 functional component, dispersion medium containing functional component 8 coating layer containing functional component 9 sustained-release composite particles

Claims (6)

A core particle containing at least one type of polymerizable monomer or polymer,
Covering at least a part of the surface of the core particles, and having a coating layer composed of micronized cellulose,
At least the coating layer among the core particles and the coating layer, containing a functional component,
The sustained-release composite particles, wherein the micronized cellulose and the core particles are bonded and in an inseparable state.   The sustained-release composite particle according to claim 1, wherein the core particle contains the polymer, and the core particle containing the polymer contains a compound having biodegradability.   As the functional ingredient, a fragrance, a deodorant, a fungicide, a fertilizer, a pH adjuster, a pesticide, a plant vitalizing agent, a plant life-prolonging agent, a pest and animal repellent, a soil penetrant, a nutritional ingredient, a plant hormone or an antibacterial agent. 3. The sustained-release composite particles according to claim 1 or 2, which contains at least one of the active substances. A first step of defibrating a cellulose raw material in a solvent to obtain a dispersion of finely divided cellulose;
Using the dispersion obtained in the first step, at least a part of the surface of the droplet containing at least one type of polymerizable monomer or polymer is covered with the micronized cellulose to stabilize the droplet as an emulsion. A second step of
At least the surface of the core particle is obtained by solidifying the droplet stabilized in the second step in a state where at least a part of the surface of the droplet is covered with the micronized cellulose to form a core particle. A third step of covering a part of the cellulose with the micronized cellulose and making the core particles and the micronized cellulose inseparable;
A fourth step of imparting a functional component to the micronized cellulose coating the surface of the core particle, the method for producing sustained-release composite particles. In the second step,
The step of adding a polymerizable monomer containing an initiator to the dispersion of the micronized cellulose to form an emulsion, a polymer that is solid at room temperature is dissolved in a solvent having low compatibility with the dispersion of the micronized cellulose. The step of adding to the dispersion of the micronized cellulose to emulsify, and adding the polymer that is solid at room temperature to the dispersion of the micronized cellulose and heating the polymer to a temperature at which it has fluidity or higher to melt the emulsion. The method for producing sustained-release composite particles according to claim 4, wherein the droplets stabilized as the emulsion are obtained by using any one of the steps of making the emulsion stable. A dry powder containing the sustained-release composite particles according to any one of claims 1 to 3, and having a solid content of 80% or more.