JP2019188376A - Adsorption agent, manufacturing method of adsorption agent and wallpaper - Google Patents

Abstract

To provide an adsorption agent easy to handle while maintaining adsorptivity of a cellulose nanofiber without requiring a treatment at a high temperature to obtain the adsorption agent, a manufacturing method of the adsorption agent, and a wallpaper containing the adsorption agent.SOLUTION: An adsorption agent 5 includes at least one kind of a polymer particle 3 and a fine cellulose 1 covering at least part of a surface of the polymer particle 3, and contains a composite particle in which the polymer particle 3 and the fine cellulose 1 are in an inseparable state.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an adsorbent using fine cellulose, a method for producing the same, and a wallpaper containing the adsorbent.

  Building materials such as wallpaper require an adsorbent that adjusts the humidity in the environment and adsorbs odorous substances, allergic substances, VOC (Volatile Organic Compounds), etc., from the viewpoint of the living environment. It is coming.

  For example, as shown in Patent Document 1, a humidity control building material using aluminum hydroxide and / or magnesium hydroxide has been reported so far. Aluminum oxide and / or magnesium oxide obtained by dehydrating aluminum hydroxide and / or magnesium hydroxide has a porous structure and can mainly absorb and release hydrophilic gas containing water vapor. Patent Document 2 discloses that mesoporous silica obtained using shale as a starting material is useful as a humidity control agent. Patent Document 3 reports a moisture-absorbing / releasing material using a water-absorbing polymer as a moisture-absorbing / releasing material having a high moisture absorption rate and moisture releasing rate. Furthermore, Patent Document 4 reports a deodorization dehumidifier containing a deodorizing and dehumidifying agent obtained by mixing a dehumidifying agent and a deodorizing agent. Deodorizing chemicals include white coal such as Bincho charcoal, oak white charcoal, oak white charcoal, black charcoal such as Ikeda charcoal, Sakura charcoal, oga charcoal, coconut husk charcoal, open hearth charcoal, dry distillation charcoal, bamboo charcoal, bean charcoal, briquette, and these. Activated carbon is used. These deodorizing agents have both a deodorizing function and a moisture absorbing function (humidity adjusting function). Since they absorb moisture together with the dehumidifying agent, the moisture absorption speed is improved and the deodorizing function is demonstrated compared to the case of using the dehumidifying agent alone. can do.

However, in order to obtain the above-mentioned humidity control agent, heat treatment at a high temperature is necessary. In Patent Document 1, dehydration is performed by heating at 200 ° C. or more and 500 ° C. or less, and in Patent Document 2, baking is performed at a temperature exceeding 700 ° C. Processing is in progress. In Patent Document 3, a polymerization reaction is carried out within a temperature range of 150 to 300 ° C. in order to obtain a water-absorbing polymer. In patent document 4, although said charcoal is utilized as a deodorizing chemical | medical agent, in order to manufacture charcoal, the heat processing at high temperature is generally required. Therefore, enormous energy is required to obtain these adsorbents.
Thus, it is strongly desired to provide an adsorbent that can be synthesized by a simple method that does not require treatment at a high temperature.

In recent years, attempts have been actively made to refine cellulose fibers in wood until at least one side of the structure is on the order of nanometers, and use them as novel functional materials.
For example, as disclosed in Patent Document 5, it is disclosed that fine cellulose fibers, that is, cellulose nanofibers (hereinafter also referred to as CNF) can be obtained by repeating mechanical treatment with wood blender or wood grinder on wood cellulose. Yes. CNF obtained by this method has been reported to have a short axis diameter of 10 to 50 nm and a long axis diameter ranging from 1 μm to 10 mm. This CNF is 1/5 lighter than steel, has a strength five times higher, and has an enormous specific surface area of 250 m ² / g or more, so it is expected to be used as a resin reinforcing filler and adsorbent. ing.

  In addition, attempts have been actively made to produce CNF by chemically treating cellulose fibers in wood in advance so as to be easily refined, and then refining by a low energy mechanical treatment similar to a home mixer. Although the method of the said chemical treatment is not specifically limited, The method of introduce | transducing an anionic functional group into a cellulose fiber and making it easy to refine | miniaturize is preferable. By introducing an anionic functional group into the cellulose fiber, the solvent can easily enter between the cellulose microfibril structures due to the osmotic pressure effect, 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 subjecting the fine fiber surface of cellulose to a phosphoric esterification treatment using a phosphoric esterification treatment. ing. Patent Document 6 discloses a method for carrying out carboxymethylation by reacting cellulose with monochloroacetic acid or sodium monochloroacetate in a high-concentration alkaline aqueous solution. Alternatively, a carboxy group may be introduced by directly reacting a carboxylic anhydride compound such as maleic acid or phthalic acid gasified in an autoclave with cellulose.

  Also, a method for selectively oxidizing the surface of cellulose fine fibers using 2,2,6,6-tetramethylpiperidinyl-1-oxy radical (TEMPO), which is a relatively stable N-oxyl compound, as a catalyst. Has also been reported (see, for example, Patent Document 7). Oxidation reaction using TEMPO as a catalyst (TEMPO oxidation reaction) can be chemically modified in an environmentally friendly manner that proceeds in water, at room temperature, and at normal pressure. When applied to cellulose in wood, there is a reaction inside the crystal. Without proceeding, only the alcoholic primary carbon possessed by 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 individual cellulose microfibril units in a solvent by the osmotic pressure effect accompanying ionization of carboxy groups selectively introduced on the crystal surface by TEMPO oxidation. Can be obtained). CSNF exhibits high dispersion stability derived from surface carboxy groups. Wood-derived CSNF obtained from wood by TEMPO oxidation reaction is a structure having a high aspect ratio with a minor axis diameter of around 3 nm and a major axis diameter ranging from several tens of nanometers to several micrometers, and its aqueous dispersion and molded article Has been reported to have high transparency.

As an application of such refined cellulose, for example, in Patent Document 8, wallpaper using cellulose nanofiber adsorbs allergens such as humidity control performance to adjust the humidity in the room and odorous substances and formaldehyde generated in the room. It has been reported to have adsorption performance.
Here, for the practical application of CNF, the problem is that the solid content concentration of the obtained CNF dispersion is as low as about 0.1 to 5%. For example, when trying to transport a finely divided cellulose dispersion, it is equivalent to transporting a large amount of solvent, so that there is a problem that the transportation cost rises and the business property is remarkably impaired. In addition, when used as an additive for resin reinforcement, there are problems that the addition efficiency is deteriorated due to low solid content and that it is difficult to make a composite when water as a solvent is not compatible with the resin. Further, when handling in a water-containing state, the water-containing CNF dispersion may be spoiled, so measures such as refrigeration storage and antiseptic treatment are required, and the cost may increase.

However, if the solvent of the refined cellulose dispersion is simply removed by heat drying or the like, the refined cellulose will aggregate, keratinize or form a film, and it will be difficult to develop a stable function as an additive. 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 a factor that impairs the business.
Thus, since handling itself of CNF in the state of a dispersion itself becomes a cause which impairs business property, providing the new handling mode which can handle CNF easily is desired strongly.

Patent No. 6193113 JP 2006-232612 A Patent No. 6007665 Japanese Patent No. 4519609 JP 2010-216021 A International Publication No. 2014/088072 JP 2008-001728 A Patent No. 6048494

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, and a new adsorbent that can be easily handled while maintaining the adsorptivity of cellulose nanofibers without requiring treatment at a high temperature in order to obtain an adsorbent, and its It aims at providing the manufacturing method of an adsorbent, and the wallpaper containing the adsorbent.

The present invention has been made to solve the above problems, and an adsorbent according to one embodiment of the present invention includes at least one kind of polymer particles and fine cellulose that covers at least a part of the surface of the polymer particles. And an adsorbent containing composite particles in which the polymer particles and the refined cellulose are inseparable.
The method for producing an adsorbent according to an aspect of the present invention includes a first step in which a cellulose raw material is defibrated in a solvent to obtain a fine cellulose dispersion, and at least one of the surfaces of resin droplets in the dispersion. A second step of stabilizing the resin droplet as an emulsion by covering the portion with the micronized cellulose, and the resin droplet in a state where at least a part of the surface of the resin droplet is covered with the micronized cellulose To obtain composite particles in which at least a part of the surface of the polymer particles is covered with the fine cellulose and the polymer particles and the fine cellulose are inseparable. A process for producing an adsorbent comprising three steps.
The wallpaper which concerns on 1 aspect of this invention is a wallpaper containing the above-mentioned adsorption agent.

  According to one aspect of the present invention, a new adsorbent that is easy to handle while maintaining the adsorptivity of cellulose nanofibers without requiring treatment at a high temperature to obtain the adsorbent and a method for producing the adsorbent In addition, wallpaper containing the adsorbent can be provided.

It is the schematic of the adsorbent obtained by superposing | polymerizing the O / W type pickering emulsion using CNF which concerns on 1st embodiment of this invention, and the polymerizable monomer inside an emulsion. It is the enlarged view of the end surface which cut | disconnected the principal part of the wallpaper which concerns on 2nd embodiment of this invention. 2 is a result of spectral transmission spectrum measurement of an aqueous dispersion of fine cellulose obtained in Example 1. FIG.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. However, the same reference numerals are given to portions corresponding to each other in the drawings to be described below, and description of the overlapping portions will be omitted 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, dimensions, and the like of each part as follows. The technical idea of the present invention can be variously modified within the technical scope defined by the claims described in the claims.

<Adsorbent>
First, the adsorbent 5 composed of composite particles including finely divided cellulose and polymer particles according to the first embodiment of the present invention will be described. FIG. 1 is a schematic view of an adsorbent 5 obtained by polymerizing an O / W type Pickering emulsion using cellulose nanofiber (hereinafter also referred to as CNF or cellulose) 1 and a polymerizable monomer inside the emulsion. The term “micronized cellulose” as used herein means fibrous cellulose having a number average minor axis diameter in the range of 1 nm to 1000 nm in terms of minor axis diameter.

The adsorbent 5 includes at least one kind of polymer particles 3, has a coating layer composed of the finely divided cellulose 1 on the surface of the polymer particles 3, and the polymer particles 3 and the finely divided cellulose 1 are combined to be inseparable. It is an adsorbent in the state of. That is, the adsorbent 5 has at least one kind of polymer particles 3 and fine cellulose 1 covering at least a part of the surface of the polymer particles 3, and the polymer particles 3 and the fine cellulose 1 are in an inseparable state. Contains some composite particles.
As shown in FIG. 1, the fine cellulose 1 is adsorbed on the interface of the monomer droplets 2 dispersed in the dispersion liquid 4, thereby stabilizing the O / W-type pickering emulsion and maintaining the stabilized state inside the emulsion. The adsorbent 5 using the emulsion as a template is produced by polymerizing the monomer.

  “Inseparable” as used herein refers to, for example, an operation of purifying and washing the adsorbent 5 by centrifuging the dispersion containing the adsorbent 5 to remove the supernatant and redispersing it by adding a solvent. Even after repeated washing with a solvent by filtration and washing using a membrane filter, the refined cellulose 1 and the polymer particles 3 are not separated, and the coating state of the polymer particles 3 with the refined cellulose 1 is maintained. It means to be drunk. The coating state can be confirmed by, for example, observing the surface of the adsorbent 5 with a scanning electron microscope. In addition, although the binding mechanism of the refined cellulose 1 and the polymer particles 3 in the adsorbent 5 is not clear, since the adsorbent 5 is prepared using an O / W emulsion stabilized by the refined cellulose 1 as a template, Since the polymerization reaction of the monomer proceeds in a state where the finely divided cellulose 1 is in contact with the monomer droplet 2 inside the emulsion, in the composite particle obtained after the polymerization, the finely divided cellulose 1 existing on the surface of the polymer particle 3 serving as the core It is expected that at least a part of the polymer particles 3 is taken in. For the above reasons, it is assumed that the finely divided cellulose 1 is physically fixed to the polymer particles 3 after polymerization, and finally the polymer particles 3 and the finely divided cellulose 1 reach an inseparable state.

Here, the O / W type emulsion is also referred to as oil-in-water type, and water is a continuous phase in which oil is dispersed as oil droplets (oil particles). .
In addition, the refined cellulose 1 in the present embodiment is not particularly limited, but it is preferable that at least a part of the refined cellulose 1 is crystallized, and has an anionic functional group on the crystal surface of the refined cellulose 1. The content of the anionic functional group is preferably 0.1 mmol or more and 5.0 mmol or less per 1 g of cellulose. When the content of the anionic functional group is less than 0.1 mmol per 1 g of cellulose, for example, it may be difficult to refine the cellulose. Moreover, when content of the said anionic functional group exceeds 5.0 mmol per 1g of cellulose, for example, the crystal structure of cellulose may be destroyed and it may become difficult to disperse as CNF.
Furthermore, it is preferable that the refined cellulose 1 has a fiber shape derived from a microfibril structure. Specifically, the refined cellulose 1 is fibrous, the number average minor axis diameter is 1 nm to 1000 nm, the number average major axis diameter is 50 nm or more, and the number average major axis diameter is the number average minor axis diameter. It is preferable that it is 5 times or more. Moreover, it is preferable that the crystal structure of the refined cellulose 1 is cellulose I type.

Moreover, in order for the adsorbent 5 to have humidity control performance, it is preferable that the refined cellulose 1 has a hygroscopic property and a moisture releasing property. Furthermore, it is preferable that the polymer particle 3 also has a hygroscopic property and a moisture releasing property, and can further improve the humidity control performance of the adsorbent. “Hygroscopic” as used herein means, for example, the property of adsorbing water vapor or the like in the outside air to at least one of the refined cellulose 1 and the polymer particles 3, for example, in an atmosphere having a relative humidity of 0% at 25 ° C. When the mass of the adsorbent 5 having a constant weight is X ₁ g and the mass of the adsorbent 5 after being brought into contact with air having a relative humidity of 10% or more and less than 100% at 25 ° C. for 4 hours is X ₂ g, 100 × It means that the moisture absorption rate from the start of moisture absorption represented by (X ₂ −X ₁ ) / (X ₁ × 4) to 4 hours later is 0.6% / hour or more. The term “moisture release” as used herein means, for example, the property of releasing water vapor or the like adsorbed on at least one of the refined cellulose 1 and the polymer particles 3 into the outside air. The mass of the adsorbent 5 constant in an atmosphere of% is X ₃ g, and the mass of the adsorbent 5 after being brought into contact with air having a relative humidity of 0% or more and less than 90% at 25 ° C. for 4 hours is X ₄ g. It means that the moisture release rate from the start of moisture release represented by −100 × (X ₄ −X ₃ ) / (X ₃ × 4) to 4 hours later is 0.6% / hour or more. .

<Method for producing adsorbent>
Next, the manufacturing method of the adsorption agent of this embodiment is demonstrated. In the method for producing an adsorbent according to the present embodiment, a cellulose raw material is defibrated in a solvent to obtain a dispersion 4 of fine cellulose 1 (first process), and in the dispersion 4 of fine cellulose 1 Coating at least a part of the surface of the polymerizable monomer droplet 2 with the micronized cellulose 1 and stabilizing the polymerizable monomer droplet 2 as an emulsion (second step); In a state where at least a portion is coated with the finely divided cellulose 1, the polymerizable monomer droplets 2 are polymerized to form the polymer particles 3, whereby at least a part of the surface of the polymer particles 3 is covered with the finely divided cellulose 1. And a step of obtaining composite particles in which the polymer particles 3 and the refined cellulose 1 are inseparable (third step).

  The adsorbent 5 obtained by the above production method is obtained as a dispersion. Further, it is obtained as a dry solid by removing the solvent. The method for removing the solvent is not particularly limited, and for example, excess water can be removed by a centrifugal separation method or a filtration method, and further dried by heat in an oven to obtain a dry solid. At this time, the obtained dry solid does not form a film or an aggregate, but is obtained as a fine powder. The reason for this is not clear, but it is generally known that when the solvent is removed from the refined cellulose dispersion, the refined cellulose strongly aggregates and forms a film. On the other hand, in the case of the dispersion containing the adsorbent 5, since the fine cellulose 1 is a true spherical adsorbent immobilized on the surface, the fine cellulose 1 is not agglomerated even if the solvent is removed. It is thought that the dry solid is obtained as a fine powder because it is only in contact with the points between the agents. In addition, since there is no aggregation between the adsorbents 5, it is easy to re-disperse the adsorbent 5 obtained as a dry powder in the solvent again, and the finer particles bonded to the surface of the adsorbent 5 after the re-dispersion. The dispersion stability derived from cellulose 1 is shown.

  Note that the dry powder of the adsorbent 5 is a dry solid material characterized in that it contains almost no solvent and can be redispersed in the solvent. Specifically, the solid content rate may be 80% or more. Further, it can be 90% or more, and can be 95% or more. Since the solvent can be almost removed, for example, favorable effects are obtained from the viewpoints of reducing transportation costs, preventing spoilage, improving the addition rate, and improving the kneading efficiency with the resin. In addition, when the solid content rate is increased to 80% or more by drying treatment, the adsorbent 5 has a hygroscopic property, so that moisture in the air may be adsorbed and the solid content rate may decrease with time. However, since the adsorbent 5 is characterized by having a moisture-releasing property, the solid content can be increased to 80% or more again by exposing the adsorbent 5 to drying conditions.

Below, each process is demonstrated in detail.
(First step)
The first step is a step in which a cellulose raw material is defibrated in a solvent to obtain a fine cellulose dispersion. 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 solvent is excessive and the productivity tends to be impaired, which is not preferable. Further, if the concentration of the cellulose raw material in the suspension is 10% or more, the suspension is rapidly thickened along with the defibration of the cellulose raw material, and it tends to be difficult to perform a uniform defibrating process. . The solvent used for preparing the suspension preferably contains 50% or more of water. When the proportion of water in the suspension is less than 50%, the dispersion of the fine cellulose 1 tends to be inhibited in the step of defibrating the cellulose raw material described later in a solvent to obtain a fine cellulose dispersion. . Moreover, as a solvent contained other than water, a hydrophilic solvent is preferable. 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, the pH of the suspension may be adjusted, for example, in order to increase the dispersibility of the cellulose and the refined cellulose 1 to be produced. 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, And organic alkalis such as benzyltrimethylammonium hydroxide aqueous solution. A sodium hydroxide aqueous solution is preferable from the viewpoint of cost.

  Subsequently, the suspension is physically defibrated to refine the cellulose raw material. The method of physical fibrillation treatment is not particularly limited. For example, a high pressure homogenizer, an ultra high pressure homogenizer, a ball mill, a roll mill, a cutter mill, a planetary mill, a jet mill, an attritor, a grinder, a juicer mixer, a homomixer, and an ultrasonic homogenizer. , Nanogenizer, mechanical treatment such as underwater collision. By performing such a physical defibrating treatment, the cellulose in the suspension is refined, and a dispersion of cellulose (micronized cellulose) 1 that is refined until at least one side of its structure is on the order of nanometers. Can be obtained. Further, the number average minor axis diameter and the number average major axis diameter of the fine cellulose 1 obtained can be adjusted by the time and number of times of physical fibrillation treatment at this time.

As described above, a dispersion of cellulose 1 (a refined cellulose dispersion) that is refined until at least one side of the structure is on the order of nanometers is obtained. The obtained dispersion can be used as a stabilizer for an O / W emulsion, which will be described later, as it is or after being diluted, concentrated or the like.
Moreover, the refined cellulose dispersion may contain other components other than the components used for adjusting the pH and cellulose as long as the effects of the present invention are not impaired. The other components are not particularly limited, and can be appropriately selected from known additives depending on the use of the adsorbent 5 and the like. Specifically, humidity control agents, organometallic compounds such as alkoxysilanes or hydrolysates thereof, inorganic layered compounds, inorganic needle minerals, antifoaming agents, inorganic particles, organic particles, lubricants, antioxidants, Antistatic agent, UV absorber, stabilizer, magnetic powder, alignment accelerator, plasticizer, crosslinking agent, magnetic substance, pharmaceutical, agricultural chemical, fragrance, adhesive, enzyme, pigment, dye, deodorant, metal, metal oxidation And inorganic oxides. When the humidity control agent is contained, the humidity control performance of the adsorbent 5 can be changed depending on the content of the humidity control agent.

  Usually, since the refined cellulose 1 has a fiber shape derived from a microfibril structure, the refined cellulose 1 used in the production method of the present embodiment preferably has a fiber shape in the following range. That is, the shape of the refined cellulose 1 is preferably fibrous. Further, the fibrous refined cellulose 1 may have a number average minor axis diameter of 1 nm or more and 1000 nm or less, preferably 2 nm or more and 500 nm or less in terms of minor axis diameter. Here, if the number average minor axis diameter is less than 1 nm, a highly crystalline rigidly refined cellulose fiber structure cannot be obtained, and it is difficult to carry out the stabilization of the emulsion and the polymerization reaction using the emulsion as a template. Tend to be. On the other hand, if the number average minor axis diameter exceeds 1000 nm in the minor axis diameter, the size becomes too large to stabilize the emulsion, and thus it tends to be difficult to control the size and shape of the resulting adsorbent 5. is there. Further, the number average major axis diameter is not particularly limited, but is preferably 5 times or more the number average minor axis diameter. It is not preferable that the number average major axis diameter is less than 5 times the number average minor axis diameter because it tends to be difficult to sufficiently control the size and shape of the adsorbent 5.

In addition, the number average short axis diameter of the refined cellulose fiber is obtained, for example, by measuring the short axis diameter (minimum diameter) of 100 fibers by observation with a transmission electron microscope or atomic force microscope, and obtaining the average value. . On the other hand, the number average major axis diameter of the refined cellulose fiber is obtained as an average value by measuring the major axis diameter (maximum diameter) of 100 fibers by observation with a transmission electron microscope or atomic force microscope, for example. .
The type and crystal structure of cellulose that can be used as a raw material for the refined cellulose 1 are not particularly limited. Specifically, as a raw material comprising cellulose I-type crystals, for example, in addition to wood-based natural cellulose, non-wood-based natural cellulose such as cotton linter, bamboo, hemp, bagasse, kenaf, bacterial cellulose, squirt cellulose, and valonia cellulose Can be used. Furthermore, the regenerated cellulose represented by the rayon fiber which consists of a cellulose II type crystal | crystallization, and a cupra fiber can also be used. From the viewpoint of easy material procurement, it is preferable to use wood-based natural cellulose as a raw material. The wood-based natural cellulose is not particularly limited, and for example, those generally used for producing cellulose nanofibers such as softwood pulp, hardwood pulp, and waste paper pulp can be used. Softwood pulp is preferred because it is easy to refine and refine.

Further, the refined cellulose raw material is preferably chemically modified. More specifically, an anionic functional group is preferably introduced on the crystal surface of the refined cellulose raw material. This is because the introduction of an anionic functional group on the surface of the cellulose crystal makes it easier for the solvent to enter between the cellulose crystals due to the osmotic pressure effect, and the refining of the cellulose raw material easily proceeds. Moreover, since an anionic functional group is a hydrophilic group, it contributes to the improvement of moisture absorption performance.
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. In view of ease of selective introduction to the cellulose crystal surface, a carboxy group is more preferable.

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

  Here, examples of the N-oxyl compound include 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. Among them, TEMPO having high reactivity is preferable. The amount of the N-oxyl compound used is not particularly limited, and may be an amount as a catalyst. Usually, it is about 0.01-5.0 mass% with respect to solid content of the wood type natural cellulose to oxidize.

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

As the co-oxidant, for example, it is possible to promote an oxidation reaction such as halogen, hypohalous acid, halous acid or perhalogen acid, or a salt thereof, halogen oxide, nitrogen oxide, peroxide or the like. Any oxidizing agent can be used if present. Sodium hypochlorite is preferred because of its availability and reactivity. The amount of the co-oxidant used is not particularly limited, and may be an amount that can promote the oxidation reaction. Usually, it is about 1-200 mass% with respect to solid content of the wood type natural cellulose to oxidize.
In addition to the N-oxyl compound and the co-oxidant, at least one compound selected from the group consisting of bromide and iodide may be further used in combination. Thereby, an oxidation reaction can be advanced smoothly and the introduction efficiency of a carboxy group can be improved. As such a compound, sodium bromide or lithium bromide is preferable, and sodium bromide is more preferable from the viewpoint of cost and stability. The amount of the compound used is not particularly limited, and may be an amount that can promote the oxidation reaction. Usually, it is about 1-50 mass% with respect to solid content of the wood type natural cellulose to oxidize.

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. When the reaction temperature of the oxidation reaction is less than 4 ° C., the reactivity of the reagent tends to decrease and the reaction time tends to be long. When the reaction temperature of the oxidation reaction exceeds 80 ° C., the side reaction is promoted to lower the molecular weight of the cellulose as a sample, and the highly crystalline rigid finely divided cellulose fiber structure is collapsed, and the stabilizer for the O / W emulsion. Tends to be difficult to use.
The reaction time for the oxidation treatment can be appropriately set in consideration of the reaction temperature, the desired amount of carboxy group, and the like, and is not particularly limited, but is usually about 10 minutes to 5 hours.

  The pH of the reaction system during the oxidation reaction is not particularly limited, but is preferably 9 to 11. When the pH is 9 or more, the reaction can be efficiently carried out. If the pH exceeds 11, side reactions may proceed, and the decomposition of cellulose as a sample may be accelerated. Further, in the oxidation treatment, as the oxidation proceeds, the pH in the system decreases due to the formation of a carboxy group. Therefore, it is preferable to maintain the pH of the reaction system at 9 to 11 during the oxidation treatment. Examples of a method for maintaining the pH of the reaction system at 9 to 11 include a method of adding an alkaline aqueous solution in accordance with a decrease in pH.

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. An organic alkali such as an aqueous solution may be mentioned. A sodium hydroxide aqueous solution is preferable from the viewpoint of cost.
The oxidation reaction with 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 maintained within the above range. As the alcohol to be added, for example, a low molecular weight alcohol such as methanol, ethanol, propanol or the like is preferable in order to quickly terminate the reaction, and ethanol is particularly preferable from the viewpoint of safety of by-products generated by the reaction.

The reaction solution after the oxidation treatment may be directly subjected to a refinement process, but in order to remove a catalyst such as an N-oxyl compound, impurities, etc., the oxidized cellulose contained in the reaction solution is recovered and washed with a washing solution. It is preferable. The collection 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 diameter of 20 μm. As a cleaning liquid used for cleaning oxidized cellulose, pure water is preferable.
When the obtained TEMPO-oxidized cellulose is defibrated, 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 refined cellulose 1 of the adsorbent 5, the particle size of the obtained 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 refining it 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, when the amount of carboxy group is less than 0.1 mmol / g, the solvent invasion action due to the osmotic pressure effect does not work between the cellulose microfibrils, so that it tends to be difficult to make the cellulose finely dispersed uniformly. is there. In addition, if the amount of carboxy group exceeds 5.0 mmol / g, cellulose microfibrils are reduced in molecular weight due to side reaction accompanying chemical treatment, so that a highly crystalline rigid micronized cellulose fiber structure cannot be taken. It tends to be difficult to use as a stabilizer for / W type emulsion.

(Second step)
The second step is a step of stabilizing the polymerizable monomer droplet 2 as an emulsion by coating at least a part of the surface of the polymerizable monomer droplet 2 in the dispersion 4 of the refined cellulose 1 with the refined cellulose 1. It is.
Specifically, a polymerizable monomer is added to the fine cellulose dispersion obtained in the first step, and the polymerizable monomer is further dispersed as droplets in the fine cellulose dispersion. In this step, at least a part of the surface is coated with the refined cellulose 1, and an O / W emulsion stabilized with the refined cellulose 1 is prepared.

  Although it does not specifically limit as a method of producing O / W type | mold emulsion, A general emulsification process, for example, various homogenizer processes and a mechanical stirring process can be used, Specifically, a high pressure homogenizer, an ultrahigh pressure homogenizer, a universal homogenizer, Examples include mechanical processing such as a ball mill, roll mill, cutter mill, planetary mill, jet mill, attritor, grinder, juicer mixer, homomixer, ultrasonic homogenizer, nanogenizer, underwater collision, and paint shaker. A plurality of mechanical processes may be used in combination.

For example, when an ultrasonic homogenizer is used, a polymerizable monomer is added to the fine cellulose dispersion obtained in the first step to form a mixed solvent, and 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. For example, the frequency is generally 20 kHz or higher, and the output is generally 10 W / cm ² or higher. The processing time is not particularly limited, but is usually about 10 seconds to 1 hour.

  By the ultrasonic treatment, the polymerizable monomer droplets 2 are dispersed in the finely divided cellulose dispersion and the emulsification progresses, and further, finely selectively at the liquid / liquid interface between the monomer droplets 2 and the finely divided cellulose dispersion. By adsorbing the cellulose oxide 1, the monomer droplet 2 is coated with the fine cellulose 1 to form a stable structure as an O / W emulsion. Thus, 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 the pickering emulsion is formed by the refined cellulose fiber is not clear, but cellulose has a hydrophilic site derived from a hydroxyl group and a hydrophobic site derived from a hydrocarbon group in its molecular structure. Therefore, it is considered that it is adsorbed on the liquid / liquid interface between the hydrophobic monomer and the hydrophilic solvent due to the amphiphilicity.

The O / W type emulsion structure can be confirmed, for example, by 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 fine cellulose layer formed on the surface layer of the monomer droplet 2 is not particularly limited, but is usually about 3 nm to 1000 nm. The thickness of the fine cellulose layer (coating layer) can be measured using, for example, a cryo TEM.

The type of polymerizable monomer that can be used in the second step is a polymer monomer that has a polymerizable functional group in its structure, is liquid at room temperature, and is completely compatible with water. Those which do not dissolve and can form a polymer (polymer) by a polymerization reaction are preferred, and it is particularly preferred that they have hygroscopicity and hygroscopicity. The polymerizable monomer has at least one polymerizable functional group. A 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 referred to as a polyfunctional monomer. Although it does not specifically limit as a kind of polymeric monomer, For example, the (meth) acrylic-type monomer which is a monomer which has a (meth) acryl group, the vinyl-type monomer which is a monomer which has a vinyl group etc. are mentioned. It is also possible to use a polymerizable monomer having a cyclic ether structure such as an epoxy group or an oxetane structure (for example, ε-caprolactone, etc.).
In addition, the notation of “(meth) acrylate” indicates that both “acrylate” and “methacrylate” are included.

  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, ethyl carbitol (meth) acrylate, phosphoric acid (meth) acrylate, ethylene oxide modified phosphoric acid (meth) acrylate, phenoxy (meta) ) 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) acryloyloxypropyl hydrogen Phthalate, 2- (meth) acryloyloxypropyl hexahydrohydrogen phthalate, 2- (meth) acryloyloxypropyl tetrahydrohydrogen phthalate, dimethylaminoethyl (meth) acrylate, trifluoroethyl (meth) acrylate, tetrafluoropropyl (meth) acrylate , Hexafluoropropyl (meth) acrylate, octafluoropropyl (meth) acrylate, octafluoropropyl (meth) acrylate, 2 -Adamantane derivatives mono (meth) acrylates such as adamantyl acrylate having a monovalent mono (meth) acrylate derived from adamantane and adamantanediol.

  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, and 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 (Meth) acrylate, neopentyl glycol di (meth) acrylate, ethoxylated neopentyl glycol di (meth) acrylate, tripropylene glycol Di (meth) acrylate, di (meth) acrylate, such as hydroxypivalic acid neopentyl glycol di (meth) acrylate.

  Examples of the trifunctional or higher functional (meth) acrylic monomer include trimethylolpropane tri (meth) acrylate, ethoxylated trimethylolpropane tri (meth) acrylate, propoxylated trimethylolpropane tri (meth) acrylate, and tris 2-hydroxy. Ethyl isocyanurate tri (meth) acrylate, tri (meth) acrylate such as 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 Trifunctional or more polyfunctional (meth) such as (meth) acrylate, dipentaerythritol penta (meth) acrylate, ditrimethylolpropane penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, ditrimethylolpropane hexa (meth) acrylate Examples thereof include acrylate compounds and polyfunctional (meth) acrylate compounds in which a part of these (meth) acrylates is substituted with an alkyl group or ε-caprolactone.

The monofunctional vinyl monomer is preferably a liquid that is not compatible with water at room temperature, such as vinyl ether, vinyl ester, and aromatic vinyl, particularly styrene and styrene monomers.
Among the monofunctional vinyl monomers, as (meth) acrylate, 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 Over DOO, dicyclopentenyl (meth) acrylate, dicyclopentenyl oxyethyl (meth) acrylate, tricyclodecanyl (meth) acrylate.

Examples of monofunctional aromatic vinyl monomers include styrene, α-methyl styrene, o-methyl styrene, m-methyl styrene, p-methyl styrene, ethyl styrene, isopropenyl toluene, isobutyl toluene, tert-butyl styrene. Vinyl naphthalene, vinyl biphenyl, 1,1-diphenylethylene, and the like.
As a polyfunctional vinyl-type monomer, the polyfunctional group which has unsaturated bonds, such as divinylbenzene, is mentioned, for example. A liquid that is incompatible with water at room temperature is preferred.

  For example, specific examples of the polyfunctional vinyl monomer include (1) divinyls such as divinylbenzene, 1,2,4-trivinylbenzene, 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) Trimethacrylates such as limethylolpropane trimethacrylate, triethylolethane trimethacrylate, (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) Diacrylates such as propane and 2,2-bis (4-acryloxydiethoxyphenyl) propane, (5) Trimethylo Triacrylates such as propane triacrylate and triethylolethane triacrylate, (6) Tetraacrylates such as tetramethylolmethane tetraacrylate, (7) Other examples include tetramethylene bis (ethyl fumarate), hexamethylene bis (acrylamide) ), Triallyl cyanurate, and triallyl isocyanurate.

For example, specific functional styrenic monomers include divinylbenzene, trivinylbenzene, divinyltoluene, divinylnaphthalene, divinylxylene, divinylbiphenyl, bis (vinylphenyl) methane, bis (vinylphenyl) ethane, and bis (vinyl). Phenyl) propane, bis (vinylphenyl) butane and the like.
In addition to these, it is possible to use polyether resins, polyester resins, polyurethane resins, epoxy resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiol polyene resins, etc. having at least one polymerizable functional group. The material is not particularly limited.

The said polymerizable monomer may be used independently and may be used in combination of 2 or more type.
The mass ratio between the finely divided cellulose fiber dispersion and the polymerizable monomer that can be used in the second step is not particularly limited. For example, the polymerizable monomer is 1 part by mass or more and 50 parts by mass with respect to 100 parts by mass of the fined cellulose fiber. Part or less. If the polymerizable monomer is less than 1 part by mass, the yield of the adsorbent 5 tends to decrease, which is not preferable. If it exceeds 50 parts by mass, it is difficult to uniformly coat the polymerizable monomer droplet 2 with the fine cellulose 1. This is not preferable.
Further, the polymerization 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-cyanovaleric 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-hi Loxyethyl) 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 in which a polymerization initiator is previously contained in the second step is used, the polymerization initiator is contained in the polymerizable monomer droplet 2 inside the emulsion particles when an O / W type emulsion is formed. When the monomer inside the emulsion is polymerized in the third step described later, the polymerization reaction easily proceeds.
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 with respect to 100 parts by mass of the polymerizable monomer. preferable. If the polymerizable monomer is less than 0.1 part by mass, the polymerization reaction does not proceed sufficiently and the yield of the adsorbent 5 tends to decrease, such being undesirable.

  Moreover, other functional components other than the polymerization initiator may be contained in the polymerizable monomer in advance. Specific examples include humidity control agents, foaming agents, magnetic substances, pharmaceuticals, agricultural chemicals, fragrances, adhesives, enzymes, pigments, dyes, deodorants, metals, metal oxides, and inorganic oxides. When other functional components other than the polymerization initiator are included in the polymerizable monomer in advance, the above-mentioned functional component can be contained inside the particles when formed as the adsorbent 5, and according to the use. Functional expression is possible. In particular, when a humidity control agent is included, the humidity control performance of the adsorbent 5 can be improved because the humidity control performance of the polymer particles 3 is improved. Examples of the humidity control agent include zeolite, charcoal, diatomaceous earth, aluminum oxide, magnesium oxide, and silica gel. Moreover, when a foaming agent is contained, the polymer particle 3 can be made into a porous body, and the humidity control performance of the adsorbent 5 can be improved.

(Third step)
In the third step, the polymerizable monomer droplets 2 are polymerized to form polymer particles 3 in a state where at least a part of the surface of the polymerizable monomer droplets 2 is coated with the micronized cellulose 1, thereby miniaturizing. This is a step of obtaining composite particles in which at least a part of the surface of the polymer particles 3 is coated with the cellulose 1 and the polymer particles 3 and the refined cellulose 1 are inseparable.
The method for polymerizing the polymerizable monomer is not particularly limited, and can be appropriately selected depending on the type of the polymerizable monomer and the type of the polymerization initiator, and examples thereof include a suspension polymerization method.

The specific suspension polymerization method is also not particularly limited, and can be carried out using a known method. For example, it can be carried out by heating the O / W emulsion prepared in the second step and containing the polymerization initiator-containing monomer droplets 2 coated with the micronized cellulose 1 and stabilized with stirring. The stirring method is not particularly limited, and a known method can be used. Specifically, a disper or a stirring bar can be used. Further, only heat treatment may be performed without stirring. The temperature condition during heating can be appropriately set depending on the type of polymerizable monomer and the type of polymerization initiator, but the temperature of the suspension is preferably 20 ° C. or higher and 150 ° C. or lower. If the temperature during heating is less than 20 degrees, the polymerization reaction rate tends to decrease, which is not preferable, and if it exceeds 150 degrees, the refined cellulose 1 may be modified, which is not preferable. The time for 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 about 1 to 24 hours. Further, the polymerization reaction may be carried out by ultraviolet irradiation treatment which is a kind of electromagnetic waves. In addition to electromagnetic waves, particle beams such as electron beams may be used.
Through the above-described steps, a spherical adsorbent 5 in which the polymer particles 3 are coated with the fine cellulose 1 can be produced.

The state immediately after the completion of the polymerization reaction is a state where a large amount of water and free fine cellulose 1 that does not contribute to the formation of the coating layer of the adsorbent 5 are mixed in the dispersion of the adsorbent 5. Therefore, it is necessary to collect and purify the produced adsorbent 5, and as a collection and purification method, washing by centrifugation or filtration washing is preferable. A known method can be used as a washing method by centrifugation. Specifically, the operation of sedimenting the adsorbent 5 by centrifugation, removing the supernatant, and redispersing in a water / methanol mixed solvent is repeated. The adsorbent 5 can be recovered by removing the residual solvent from the sediment obtained by centrifugation. 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 repeatedly subjected to suction filtration with water and methanol, and finally the residual solvent is further removed from the paste remaining on the membrane filter. Thus, the adsorbent 5 can be recovered.
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 material containing the adsorbent 5 thus obtained does not become a film or an aggregate as described above, but is obtained as a fine powder.

(Effects of the first embodiment)
The adsorbent 5 according to the present embodiment is an adsorbent that adsorbs a chemical substance having a high affinity with the fine cellulose 1 on the surface of the adsorbent 5. As a chemical substance having high affinity with the micronized cellulose 1, there is a compound having a hydrophilic functional group, for example, a compound having a hydroxyl group, a carboxy group, a phosphate group, a sulfonate group, an amino group, or an ether group. It is done. Especially, since it has a hygroscopic property and a moisture releasing property with respect to moisture in the air, it exhibits humidity control performance. Specifically, the mass of the adsorbent constanted in an atmosphere at 25 ° C. and 0% relative humidity is X ₁ g, and after being brought into contact with air having a relative humidity of 10% or more and less than 100% at 25 ° C. for 4 hours. When the mass of the adsorbent is X ₂ g, the moisture absorption rate from the start of moisture absorption represented by 100 × (X ₂ −X ₁ ) / (X ₁ × 4) to 4 hours later is 0.6% / It is preferable that it is more than time. Further, the adsorbent mass constantd in an atmosphere with a relative humidity of 95% at 25 ° C. is defined as X ₃ g, and the adsorption after contact with air having a relative humidity of 0% to less than 90% at 25 ° C. for 4 hours. When the mass of the agent is X ₄ g, the moisture release rate from the start of moisture release represented by −100 × (X ₄ −X ₃ ) / (X ₃ × 4) to 4 hours later is 0.6% / It is preferable that it is more than time. When the moisture absorption rate and moisture release rate are less than 0.6% / hour, the adsorbent 5 cannot exhibit sufficient moisture conditioning performance.

Furthermore, it is preferable that the equilibrium moisture absorption rate at 25 ° C. and a relative humidity of 95% is 1% or more and 15% or less. When the equilibrium moisture absorption rate is less than 1%, the adsorbent 5 tends to be difficult to exhibit sufficient humidity control performance. When the equilibrium moisture absorption rate exceeds 15%, in order to increase the proportion of the fine cellulose 1 in the adsorbent 5, it is necessary to reduce the particle size of the polymer particles 3 to 1 nm or less. It tends to be difficult to fabricate. Incidentally, equilibrium moisture moisture absorption rate is represented by _{100 × (X 3 -X 1)} / X 1.
Further, the adsorbent 5 according to the present embodiment is an adsorbent having good dispersion stability that is derived from the refined cellulose 1 on the surface of the adsorbent 5 and has high biocompatibility and does not aggregate in a solvent.

Moreover, since the dry solid substance containing the adsorbent 5 according to the present embodiment is obtained as a fine powder and there is no aggregation between particles, the adsorbent 5 obtained as a dry powder has a large specific surface area. Can do.
Moreover, according to the manufacturing method of the adsorbent 5 which concerns on this embodiment, the load to an environment is low and the manufacturing method of the novel adsorbent 5 which can be provided by a simple method can be provided.
Further, according to the adsorbent 5 according to the present embodiment, since the solvent can be almost removed, the transportation cost is reduced, the corruption risk is reduced, the addition efficiency as an additive is improved, and the kneading into the hydrophobic resin is performed. The effect of improving efficiency can be expected.

  The first embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and design changes and the like within the scope of the present invention are included. . In addition, the constituent elements shown in the first embodiment and the modifications described above can be combined as appropriate.

(Second embodiment)
Next, a second embodiment of the present invention will be described. In the following description, components that are the same as those already described are denoted by the same reference numerals and redundant description is omitted.
<Wallpaper>
The wallpaper 8 according to the present embodiment is a wallpaper including the adsorbent 5 according to the first embodiment of the present invention.
The structure of the wallpaper 8 is not particularly limited as long as it is a sheet-like structure including the adsorbent 5, but the adsorbent 5 is exposed on the outermost surface or the surface of the adsorbent 5 is a material that transmits moisture. Preferably it is covered. An example of the configuration of the wallpaper 8 is a wallpaper in which the moisture absorption layer 6 including the adsorbent 5 is provided on the upper part of the base material 7 as the wallpaper 8 shown in FIG.
The wallpaper 8 may be produced by applying a dispersion liquid containing the adsorbent 5 to the base material 7 or the like, or by forming a wallpaper composition containing the adsorbent 5. When the wallpaper 8 is produced by applying the dispersion containing the adsorbent 5, the moisture absorption layer 6 applies the dispersion containing the adsorbent 5 to the substrate 7 and removes the solvent in the dispersion by heating or the like. It is obtained by doing.

  The dispersion containing the adsorbent 5 may contain a material other than the adsorbent 5 as long as it does not impair the effects of the present invention. It does not specifically limit as said material, According to the use etc. of the wallpaper 8, it can select suitably from well-known additives. Specifically, inorganic binders such as condensates of alkoxysilanes, organic binders such as acrylic resins and vinyl chloride resins, humidity control agents, inorganic layered compounds, inorganic needle minerals, antifoaming agents, inorganic particles, Organic particles, lubricants, antioxidants, antistatic agents, UV absorbers, stabilizers, magnetic powders, alignment accelerators, plasticizers, crosslinking agents, magnetic substances, pharmaceuticals, agricultural chemicals, fragrances, adhesives, enzymes, pigments , Dyes, deodorants, metals, metal oxides, inorganic oxides and the like.

  Examples of the material of the base material 7 include nonwoven fabric, mesh, paper, pulp, polyethylene terephthalate (PET), polypropylene (PP), polyethylene terephthalate copolymer (PETG), polyvinyl chloride (PVC), glass, and silicon. May be included. Furthermore, the base material 7 may be surface-modified with, for example, indium-tin oxide (ITO) or silicon oxide (SiOx), but is not limited thereto. The substrate 7 may be transparent, opaque or reflective. Moreover, the base material 7 can have arbitrary colors, such as black and white, according to the intended purpose of the wallpaper 8. Furthermore, the base material 7 may have gloss or may not have gloss. Further, the base material 7 may be omitted.

Means for applying the dispersion containing the adsorbent 5 to the base material 7 and the like include, for example, brush coating, brush coating, glazing, bar coater, knife coater, doctor blade, screen printing, spray coating, spin coater, applicator, roll Coating methods such as coater, flow coater, centrifugal coater, ultrasonic coater, (micro) gravure coater, dip coating, flexographic printing, potting, and scraping treatment can be used. Then, it may be transferred. Moreover, you may perform the application | coating of the dispersion liquid containing the adsorbent 5 not only once but multiple times. When the dispersion liquid containing the adsorbent 5 contains a solvent, it is necessary to remove the solvent by heating and drying at a temperature at which the solvent can be removed.
In FIG. 2, the wallpaper 8 is composed of the hygroscopic layer 6 and the base material 7, but a functional layer can be provided as long as the hygroscopicity of the wallpaper 8 is not impaired. Examples of the role of the functional layer include preventing the moisture absorption layer 6 from being damaged and preventing the moisture absorption layer 6 from becoming dirty.

(Effect of the second embodiment)
According to the wallpaper 8 according to the present embodiment, a chemical substance having a high affinity with the fine cellulose 1 can be adsorbed as in the first embodiment. Moreover, since it has a hygroscopic property and a moisture releasing property especially with respect to moisture in the air, it exhibits humidity control performance.
The second embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and design changes and the like within a scope not departing from the gist of the present invention are included. . In addition, the components shown in the second embodiment described above can be combined as appropriate.

[Example]
EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, the technical scope of this invention is not limited to these Examples. In each of the following examples, “%” indicates mass% (w / w%) unless otherwise specified.

[Various evaluations]
(1) Humidity control performance The adsorbents obtained in Examples 1 to 7 and Comparative Examples 1 to 3 described below were evaluated as follows. The results are summarized in Table 1.
Moisture absorption rate: The adsorbent obtained in each example was weighed in an atmosphere of 0% relative humidity at 25 ° C. and then weighed 100 g (referred to as X ₁ g). The constant weight of adsorbent, the mass after contacting for four hours and 95% relative humidity air at 25 ° C., measured as _{X 2} g, from _{100 × (X 2 -X 1)} / (X 1 × 4) The moisture absorption rate was calculated.
Moisture release rate: The X ₂ g adsorbent was weighed at a relative humidity of 95%, and the mass was measured (referred to as X ₃ g). The mass after the constant weight adsorbent was brought into contact with air having a relative humidity of 0% at 25 ° C. for 4 hours was measured as X ₄ g, and −100 × (X ₄ −X ₃ ) / (X ₃ × 4) The moisture release rate was calculated.
Equilibrium moisture absorption: Using the above measurement data, the equilibrium moisture absorption was calculated from 100 × (X ₃ −X ₁ ) / X ₁ .

(2) Adsorbability to odorous substances The adsorbents obtained in Examples 1 to 7 and Comparative Examples 1 to 3 described below were evaluated as follows. The results are summarized in Table 2.
Evaluation method: 10 g of the adsorbent obtained in each example was weighed and placed in a 500 mL sealed bottle together with cotton soaked with 3 drops of 0.1N ammonia water, and allowed to stand for 1 week. After that, I opened the lid and smelled it.

(3) Adsorbability with respect to dye The following evaluation was performed on the adsorbents obtained in Example 7 and Comparative Examples 1 to 4 described below. The results are summarized in Table 3.
Evaluation method: 50 mL of a 0.05% Congo red aqueous solution was placed in a 100 mL sealed bottle, and 10 g of the adsorbent obtained in each example was added, followed by stirring for 1 hour. The aqueous solution whose stirring was completed was treated with a centrifugal force of 75,000 g for 5 minutes, and the color of the supernatant was observed. However, the commercially available CNF of Comparative Example 3 was 10 to 35% water-containing, and the amounts of Congo Red and water used were adjusted in order to match the evaluation and concentration of Example 7 and Comparative Examples 1-2 and 4. .

<Example 1>
(First step: step of obtaining a cellulose nanofiber dispersion)
(TEMPO oxidation of wood cellulose)
70 g of softwood kraft pulp was suspended in 3500 g of distilled water, and a solution of 0.7 g of TEMPO and 7 g of sodium bromide dissolved in 350 g of distilled water was added and cooled to 20 ° C. 450 g of sodium hypochlorite aqueous solution having a concentration of 2 mol / L and a density of 1.15 g / mL was added dropwise thereto to initiate 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 a 0.5N aqueous sodium hydroxide solution. When the total amount of sodium hydroxide added reached 3.50 mmol / g with respect to the mass of cellulose, about 100 mL of ethanol was added to stop the reaction. Thereafter, filtration and washing with distilled water were repeated using a glass filter to obtain oxidized pulp.

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

(Oxidized pulp defibration treatment)
1 g of oxidized pulp obtained by the above TEMPO oxidation was dispersed in 99 g of distilled water and refined with a juicer mixer for 30 minutes to obtain a CSNF aqueous dispersion having a CSNF concentration of 1%. FIG. 3 shows the results of measuring the spectral transmission spectrum using a spectrophotometer (manufactured by Shimadzu Corporation, “UV-3600”) after putting the CSNF dispersion in a quartz cell having an optical path length of 1 cm. As is apparent from FIG. 3, the CSNF aqueous dispersion showed high transparency. 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, as a result of performing steady-state viscoelasticity measurement using a rheometer, the CSNF dispersion showed thixotropic properties.

(2nd process: The process of producing O / W type emulsion)
Next, 1 g of 2,2-azobis-2,4-dimethylvaleronitrile (hereinafter also referred to as ADVN) as a polymerization initiator is used per 10 g of divinylbenzene (hereinafter also referred to as DVB) as a polymerizable monomer. Dissolved. When the total 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, an ultrasonic homogenizer shaft was inserted from the upper surface of the mixed liquid in the state where the two layers were separated, and an 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 ultrasonic homogenizer treatment was like a cloudy emulsion. When a drop of the mixture is dropped on a slide glass, sealed with a cover glass, and observed with an optical microscope, countless emulsion droplets of about 1 to several μm are formed and dispersed and stabilized as an O / W emulsion. Was confirmed.

(3rd process: The process of obtaining the adsorption agent 5 coat | covered with CNF by polymerization reaction)
The O / W emulsion dispersion was used in a 70 ° C. hot water bath using a water bath and treated for 8 hours while stirring with a stirrer to carry out a polymerization reaction. After the treatment for 8 hours, 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 was treated with a centrifugal force of 75,000 g (g is gravitational acceleration) for 5 minutes to obtain a sediment. The supernatant was removed by decantation, and the precipitate was collected, and further washed repeatedly with pure water and methanol using a PTFE membrane filter having 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.). The average particle size was 2.2 μm. Next, the purified / collected product was air-dried and further subjected to a vacuum drying treatment at room temperature of 25 ° C. for 24 hours, whereby a fine dry powder (adsorbent 5) was obtained.

<Example 2>
Adsorbent 5 was produced under the same conditions as in Example 1 except that diethylene glycol diacrylate (trade name FA-222A, Hitachi Chemical, hereinafter also referred to as FA-222A) was used instead of DVB in Example 1. In the same manner, the evaluation was performed.
<Example 3>
Example 1 was the same as Example 1 except that hexanediol diacrylate (trade name A-HD-N, Shin-Nakamura Chemical Co., Ltd., hereinafter also referred to as A-HD-N) was used instead of DVB. The adsorbent 5 was produced under the same conditions and evaluated in the same manner.

<Example 4>
Adsorbent 5 was produced under the same conditions as in Example 1, except that 2,2-azobis-isobutyronitrile (hereinafter also referred to as AIBN) was used as the polymerization initiator instead of ADVN in Example 1. In the same manner, the evaluation was performed.
<Example 5>
In Example 1, instead of TEMPO oxidation, a C-merified CNF dispersion obtained by carrying out carboxymethylation (hereinafter also referred to as CM conversion) treatment according to Patent Document 6 cited as the prior art document was used. Produced the adsorbent 5 under the same conditions as in Example 1 and evaluated in the same manner.

<Example 6>
In Example 1, instead of TEMPO oxidation, Example 1 was used except that a phosphate esterified CNF dispersion obtained by performing a phosphate esterification treatment according to Non-Patent Document 1 listed as the prior art document was used. The adsorbent 5 was produced under the same conditions as those described above and evaluated in the same manner.
<Example 7>
In Example 1, instead of CSNF dispersion obtained from softwood kraft pulp, adsorbent 5 was produced under the same conditions as in Example 1 using commercially available CNF (Serish PC110T, Daicel FineChem) and evaluated in the same manner. Carried out.

<Comparative Example 1>
Evaluation similar to Example 1 was implemented using the commercially available styrene-divinylbenzene copolymer microbeads (particle diameter 4.5 micrometers, technochemical) instead of the adsorbent which concerns on this embodiment.
<Comparative example 2>
Instead of the adsorbent according to the present embodiment, commercially available microcrystalline cellulose (pure cellulose CF-1 for column chromatography, Whatman) was subjected to vacuum drying treatment at room temperature of 25 ° C. for 24 hours, and the same evaluation as in Example 1 was performed. Carried out.

<Comparative Example 3>
Instead of the adsorbent according to this embodiment, a commercially available CNF (Serish PC110T, Daicel FineChem) was subjected to a vacuum drying treatment at room temperature of 25 ° C. for 24 hours, and the same evaluation as in Example 1 was performed. However, the evaluation of the adsorptivity to the dye was used without vacuum drying treatment.
<Comparative example 4>
By spray coating commercially available CNF (Serish PC110T, Daicel FineChem) on commercially available styrene-divinylbenzene copolymer microbeads (particle diameter 4.5 μm, technochemical) instead of the adsorbent according to this embodiment, The microbead surface was coated with CNF. After vacuum drying at room temperature of 25 ° C. for 24 hours, the adsorptivity to the dye was evaluated in the same manner as in Example 1.

  The evaluation results using the above Examples and Comparative Examples are listed in Tables 1 to 3 below.

In Tables 1 to 3, the emulsion stabilizer is an additive used to stabilize the O / W emulsion in the second step. For example, the refined cellulose 1 in this embodiment is Equivalent to.
As is apparent from the evaluation results of Examples 1 to 7 in Table 1, depending on the type of refined cellulose 1 (TEMPO oxidized CNF, CCM CNF, phosphate esterified CNF), or the type of monomer and the type of initiator, It was confirmed that the humidity control performance changed. This may be because the affinity of the adsorbent for moisture has changed. Moreover, as shown to Tables 2-3, it was confirmed that it also shows adsorptivity with respect to ammonia and dye which are odor substances.

On the other hand, in Comparative Example 1, a commercially available microbead having a similar structure and not coated with CNF was used, but no mass change due to moisture absorption was observed, and the adsorptivity to ammonia and dye was low. This is thought to be because the particles do not contain finely divided cellulose that exhibits adsorptivity.
In Comparative Example 2, commercially available microcrystalline cellulose was used, but it was confirmed that the humidity control performance and the adsorptive power to ammonia and dyes were low. Since the specific surface area of microcrystalline cellulose is smaller than the adsorbents produced in Examples 1 to 7, it is considered that the adsorptivity is low.

In Comparative Example 3, commercially available CNF was used, but the humidity control performance and the adsorptivity to ammonia were low. Commercially available CNF can be obtained with water content, but it is considered that if it is dried to remove water, it forms a film and the specific surface area becomes small. Further, in the evaluation of the adsorptivity to the dye, it was confirmed that CNF did not precipitate by centrifugation, so that a colorless and transparent supernatant could not be obtained, and it was difficult to use as an adsorbent.
In Comparative Example 4, an adsorbent obtained by coating commercially available microbeads with commercially available CNF was used, but it was confirmed that the adsorptive power to the dye was low. This is thought to be due to the fact that CNF and microbeads exhibiting adsorptive properties are not inseparable, so that CNF was eluted in the aqueous solution. Since CNF does not precipitate by centrifugation, a colorless and transparent supernatant is used. It is expected that it could not be obtained.

  The adsorbent of the present invention, which does not require high-temperature treatment to obtain an adsorbent, maintains the adsorptivity of cellulose nanofibers and is easy to handle, has a function of conditioning and deodorizing. It can be used for wallpaper.

1 Cellulose nanofiber (refined cellulose)
2 Monomer droplet (polymerizable monomer droplet)
3 Polymer particles 4 Dispersion liquid 5 Adsorbent 6 Absorbent layer 7 Base material 8 Wallpaper

Claims (10)

  Characterized in that it comprises at least one kind of polymer particles and finely divided cellulose covering at least a part of the surface of the polymer particles, and comprising composite particles in which the polymer particles and the finely divided cellulose are inseparable. Adsorbent.   The adsorbent according to claim 1, wherein the refined cellulose has hygroscopicity and hygroscopicity. The mass of the adsorbent constantized in an atmosphere at 25 ° C. and 0% relative humidity is X ₁ g, and the adsorbent after contacting with air having a relative humidity of 10% or more and less than 100% at 25 ° C. for 4 hours. When the mass is X ₂ g, the moisture absorption rate from the start of moisture absorption represented by 100 × (X ₂ −X ₁ ) / (X ₁ × 4) to 4 hours later is 0.6% / hour or more. The adsorbent according to claim 1 or 2, wherein The mass of the adsorbent constanted in an atmosphere of 95% relative humidity at 25 ° C. is X ₃ g, and the adsorbent after being brought into contact with air having a relative humidity of 0% or more and less than 90% at 25 ° C. for 4 hours. When the mass is X ₄ g, the moisture release rate from the start of moisture release represented by the formula −100 × (X ₄ −X ₃ ) / (X ₃ × 4) to 4 hours later is 0.6% / hour. It is the above, Adsorbent of any one of Claims 1-3 characterized by the above-mentioned.   The adsorbent according to any one of claims 1 to 4, wherein an equilibrium moisture absorption rate at 25 ° C and a relative humidity of 95% is in the range of 1% to 15%. At least a portion of the micronized cellulose is crystallized;
The adsorbent according to any one of claims 1 to 5, wherein an anionic functional group is introduced on a crystal surface of the fine cellulose.   The adsorbent according to any one of claims 1 to 6, wherein the polymer particles include a component having hygroscopicity and moisture desorption.   The adsorbent according to any one of claims 1 to 7, wherein at least one of hydrophilic gas, odorous substance, pigment, allergic substance and volatile organic compound is adsorbed. A first step in which a cellulose raw material is defibrated in a solvent to obtain a finely divided cellulose dispersion;
A second step of covering at least a part of the surface of the resin droplets in the dispersion with the micronized cellulose and stabilizing the resin droplets as an emulsion;
In a state where at least a part of the surface of the resin droplet is covered with the micronized cellulose, the resin droplet is cured to form a polymer particle, so that at least a part of the surface of the polymer particle is the micronized. And a third step of obtaining composite particles that are covered with cellulose and in which the polymer particles and the finely divided cellulose are inseparable from each other.   A wallpaper comprising the adsorbent according to any one of claims 1 to 8.

Images