JP7036336B2 - Method for manufacturing composite slurry - Google Patents

Description

The present disclosure relates to composite slurries, composite materials, and methods for producing composite slurries.

Conventionally, additives have been added in order to improve the physical characteristics of a material containing a resin as a main component (see Patent Document 1).

Japanese Patent Application Laid-Open No. 2015-183021

It is conceivable to add cellulose as an additive. However, cellulose has poor dispersibility in the resin and tends to aggregate in the resin. When the cellulose aggregates, the cellulose is unevenly distributed in the material containing the resin as a main component, and the resin becomes inhomogenized. In that case, it is difficult to improve physical properties such as strength, transparency, and smoothness.

One aspect of the present disclosure is an object of the present invention to provide a composite slurry, a composite material, and a method for manufacturing a composite slurry that can be used for manufacturing a composite material having excellent physical characteristics.

One aspect of the present disclosure is a composite slurry containing inorganic oxide particles and cellulose having a fiber diameter of 100 nm or less. By using the composite slurry, which is one aspect of the present disclosure, a composite material having excellent physical characteristics can be produced.

Another aspect of the present disclosure is a composite material containing a resin, inorganic oxide particles dispersed in the resin, and cellulose having a fiber diameter of 100 nm or less dispersed in the resin. The composite material, which is another aspect of the present disclosure, has excellent physical properties.

Another aspect of the present disclosure is a composite slurry for producing a small-diameter cellulose having a fiber diameter of 100 nm or less by defibrating or modifying the cellulose, and producing a composite slurry containing the small-diameter cellulose and inorganic oxide particles. It is a manufacturing method of.

By using the composite slurry produced by the method for producing a composite slurry, which is another aspect of the present disclosure, a composite material having excellent physical characteristics can be manufactured.

FIG. 1A is an explanatory diagram showing a state in which cellulose fibers 3 are dispersed and present on the surface 1A of the substrate 1, and FIG. 1B is an explanatory diagram showing a fiber diameter d in a cross-sectional profile.

An embodiment of the present disclosure will be described.
1. 1. Composite Slurry The composite slurry of the present disclosure includes inorganic oxide particles and cellulose having a fiber diameter of 100 nm or less (hereinafter referred to as small diameter cellulose).

The composite slurry of the present disclosure can be used, for example, in the production of a composite material containing a resin. For example, a composite material containing a resin can be obtained by mixing and solidifying the composite slurry of the present disclosure and a component containing a resin. In this composite material, for example, the inorganic oxide particles and the small-diameter cellulose are uniformly dispersed in the resin. Therefore, the composite material has excellent physical properties. As excellent physical properties, for example, the strength of the composite material is high, the light transmittance of the composite material is high, the surface roughness of the composite material is low, and the like.

The inorganic oxide particles may be either acid oxide particles or basic oxide particles. Examples of the inorganic oxide particles include silica particles, titanium oxide particles, lithium oxide particles, corundum particles, magnetite particles and the like. In particular, inorganic oxide particles having a hydroxyl group are desirable because they are likely to form a bond with cellulose by a hydrogen bond or a dehydration condensation reaction.
Examples of the silica particles include porous silica particles. Examples of the porous silica particles include silica gel particles. All of the inorganic oxide particles may be silica particles, or some of the inorganic oxide particles may be silica particles.

The average particle size of the silica particles is preferably 1 nm or more and 5 μm or less, more preferably 50 nm or more and 5 μm or less, and particularly preferably 100 nm or more and 5 μm or less. When the average particle size is within these ranges, the physical properties of the composite material are further improved. The method for measuring the average particle size of the silica particles is as follows. In the range of 1 nm or more and less than 1 μm, it is a measurement method by a dynamic light scattering method. In the range of 1 μm or more and 5 μm or less, it is a measurement method by a laser diffraction & scattering method.
The small-diameter cellulose can be produced, for example, by defibrating cellulose having a fiber diameter of more than 100 nm.
The fiber diameter of the small-diameter cellulose is preferably 3 nm or more and 100 nm or less, and more preferably 10 nm or more and 60 nm or less. 3 nm is a value that is considered to be the minimum value of the structural unit of small-diameter cellulose. When the fiber diameter of the small-diameter cellulose is 100 nm or less, the transparency of the composite material is improved at the wavelength of visible light. When it is 60 nm or less, the transparency of the composite material is further improved.
Examples of the method for defibrating cellulose include a method using a disperser such as a disper and a wet pulverizer, and a method using a wet pulverizer is preferable. Examples of the wet crushing device include a ball mill, a bead mill, a hammer mill, a rod mill, a cutter mill, a millstone, a grinder, a jet mill and the like. Examples of the jet mill include a high pressure jet mill.
As a raw material for small-diameter cellulose, animal-vegetable cellulose such as plants, microorganisms and sea squirts is desirable, but polysaccharides such as chitin and chitosan may also be used. In addition, as a raw material for small-diameter cellulose, it is treated by an inorganic acid such as sulfuric acid or a catalytic reaction such as TEMPO (2,2,6,6-tetramethylpiperidine 1-oxyl). Cellulose that has been subjected to the above and cellulose that is condensed and polymerized with other compounds can also be used.

The method for measuring the fiber diameter of cellulose is as follows. The composite slurry containing cellulose is applied to a flat substrate and dried. As a result, as shown in FIG. 1A, the cellulose fibers 3 are dispersed and exist on the surface 1A of the substrate 1. Next, an atomic force microscope (AFM) image of the surface 1A is acquired. In the AFM image, the cross-sectional profile of the fiber in the lateral direction X shown in FIG. 1A is acquired. An example of a cross-sectional profile is shown in FIG. 1B. In the cross-sectional profile, the distance between the apex T of the cellulose fiber 3 and the reference surface 5 is defined as the fiber diameter d. The reference surface 5 is a surface obtained by extrapolating the surface 1A in the portion where the cellulose fiber 3 does not exist to the portion where the cellulose fiber 3 exists. The above fiber diameter d is measured at 150 points, and the average value thereof is taken as the cellulose fiber diameter.

The composite slurry of the present disclosure comprises a dispersion medium. Inorganic oxide particles and small-diameter cellulose are dispersed in, for example, a dispersion medium. As the dispersion medium, one having a large dielectric constant is preferable, and one having a hydroxyl group in the molecule is particularly preferable. In this case, since the dispersion stability of the inorganic oxide particles and the small-diameter cellulose in the composite slurry is improved, aggregation and precipitation are less likely to occur, and the physical properties of the composite material are further improved. Examples of the dispersion medium having a hydroxyl group in the molecule include water, alcohol, ester, ketone, carbonate, organic acid, aldehyde and the like.

The concentration of the inorganic oxide particles in the composite slurry is preferably in the range of 0.01 to 50% by mass. When it is within this range, the viscosity of the composite slurry is low, so that the composite and dispersion in the resin are promoted.
The concentration of the small diameter cellulose in the slurry is more preferably in the range of 0.01 to 15% by mass. Within this range, compounding and dispersion in the resin are further promoted.
Composite is a combination of small-diameter cellulose and inorganic oxide particles by crushing and dispersing cellulose to a small diameter and forcibly causing contact with inorganic oxide particles in a wet state in a dispersion medium. It means to put it in a state.
The composite slurry means that the small-diameter cellulose and the inorganic oxide particles are in a state of being bonded by a hydrogen bond or a dehydration condensation reaction in a dispersion medium. Dispersion in the resin means that the composite slurry is mixed and dispersed in the resin.

The ratio of the concentration of the inorganic oxide particles to the concentration of the small-diameter cellulose is preferably in the range of 0.01 to 100, more preferably in the range of 0.25 to 10, and in the range of 0.25 to 2.5. It is particularly preferable to have. Within this range, the small-diameter cellulose and the inorganic oxide particles are likely to be complexed by hydrogen bonding or dehydration condensation.
The composite slurry of the present disclosure may further contain components other than the inorganic oxide particles and the small-diameter cellulose.

2. 2. Composite Materials The composite materials of the present disclosure include resins, inorganic oxide particles, and small diameter cellulose. Inorganic oxide particles and small-diameter cellulose are dispersed in the resin. The composite material has excellent physical properties. As excellent physical properties, for example, the strength of the composite material is high, the light transmittance of the composite material is high, the surface roughness of the composite material is low, and the like.

Examples of the resin include organic polymers such as thermoplastic resins, thermosetting resins, elastomers, and rubbers. Specific examples of the resin include urethane resin, epoxy resin, (meth) acrylic resin, polyethylene resin, polypropylene resin, phenol resin, unsaturated polyester resin, polyamide resin, and polyimide resin.
The inorganic oxide particles and the small-diameter cellulose are, for example, those described in the above section "1. Composite slurry".

When the mass of the small-diameter cellulose contained in the composite material is 1 part by mass, the mass of the inorganic oxide particles contained in the composite material is preferably in the range of 0.01 to 100 parts by mass. When it is within this range, the dispersibility of the small-diameter cellulose and the inorganic oxide particles in the resin is good, and it becomes difficult to aggregate in the resin. As a result, the physical properties such as strength, transparency, and smoothness of the composite material are further improved.

The composite material of the present disclosure can be produced, for example, by mixing and solidifying the composite slurry of the present disclosure and a component containing a resin. Examples of the component containing a resin include a resin emulsion, a resin and a resin raw material that become liquid at room temperature or by heating, and a resin whose viscosity is lowered by heating.

3. 3. Method for Producing Composite Slurry In the method for producing a composite slurry of the present disclosure, small-diameter cellulose having a fiber diameter of 100 nm or less is produced by defibrating or modifying cellulose, and contains the small-diameter cellulose and inorganic oxide particles. Produce a composite slurry. Examples of the method for defibrating cellulose include a method using a wet pulverizer.
As used herein, defibration or modification includes mechanical defibration and chemical defibration.

The wet pulverizer, the small-diameter cellulose, and the inorganic oxide particles are, for example, those described in the above section "1. Composite slurry".
In the method for producing a composite slurry of the present disclosure, for example, it is preferable to supply a mixture containing cellulose and inorganic oxide particles to a wet pulverizer and defibrate the cellulose to produce small-diameter cellulose.
In this case, for example, even if a mixture containing the previously reduced-diameter cellulose and the inorganic oxide particles is supplied to the wet pulverizer, the small-diameter cellulose secondarily aggregated in the dispersion medium is dissolved, so that the small-diameter cellulose and the inorganic are dissolved. A composite slurry can be formed with oxide particles.
For example, cellulose can be defibrated to produce small-diameter cellulose, and inorganic oxide particles can be made finer. In this case, since a bond is generated between the small-diameter cellulose and the inorganic oxide particles by hydrogen bonding or dehydration condensation, the physical characteristics of the composite material produced by using the obtained composite slurry can be further improved.
Further, the already finely divided inorganic oxide particles or the inorganic oxide particles having an average particle size of 1 μm or more and 5 μm or less may be supplied to the wet pulverizer. In this case, the inorganic oxide particles may or may not be miniaturized in the wet pulverizer.

The method for producing the composite slurry of the present disclosure is preferably a method for producing a composite slurry by wet pulverization. The wet pulverizer used in the manufacturing method by wet pulverization is preferably a high pressure jet mill. The control pressure in the high-pressure jet mill is preferably 50 MPa or more, more preferably 150 MPa or more. In this case, the above-mentioned bond between the small-diameter cellulose and the inorganic oxide particles can be obtained, and the production time of the small-diameter cellulose can be shortened.

4. Example (4-1) Production of composite slurry Cellulose powder and fine powdered silica gel were prepared. This cellulose powder is trade name: Theoras (registered trademark) FD-101 manufactured by Asahi Kasei Corporation. The average particle size of the cellulose powder is about 40 μm. The fine powder silica gel is a trade name: Silysia 350 manufactured by Fuji Silysia Chemical Ltd. The fine powder silica gel has an average particle size of 3.9 μm and a specific surface area of 300 m ² / g.

A dispersion liquid in which cellulose powder and fine powdery silica gel were dispersed was supplied to a high-pressure jet mill. The mass ratio of the cellulose powder to the fine powdered silica gel in the dispersion is 1: 0.25. The high-pressure jet mill is manufactured by Yoshida Kikai Kogyo Co., Ltd. Product name: NanoVeta. The control pressure of the high pressure jet mill is 150 MPa.

Cellulose powder was defibrated by a high-pressure jet mill to produce small-diameter cellulose. In addition, the fine powder silica gel was further refined. As a result, a composite slurry S1 containing finely divided fine powder silica gel and small-diameter cellulose was obtained. The fiber diameter of the small-diameter cellulose was 10 to 20 nm. The average particle size of the finely divided silica gel was 160 to 175 nm.

Further, by changing the mass ratio of the cellulose powder and the fine powder silica gel in the dispersion liquid supplied to the high pressure jet mill, the mass ratio of the fine powder silica gel and the small diameter silica gel is different from that of the composite slurry S1. Manufactured. Table 1 shows the mass ratio of the fine powder silica gel and the small diameter cellulose in the composite slurries S1 to S5.

（４－２）複合材料の製造と評価（その１）
ウレタン樹脂エマルジョンと、複合スラリーＳ１～Ｓ５のいずれかとを混合し、混合物をシリコン容器に投入し、乾燥させることで、複合材料のフィルムを得た。複合材料は、ウレタン樹脂と、ウレタン樹脂中に分散した微粉末状シリカゲルと、ウレタン樹脂中に分散した小径セルロースとを含む。以下では、複合スラリーＳｉを用いて製造したフィルムを、フィルムＦｉとする。ｉは１～５のいずれかである。

(4-2) Manufacture and evaluation of composite materials (Part 1)
The urethane resin emulsion and any one of the composite slurries S1 to S5 were mixed, the mixture was placed in a silicon container, and dried to obtain a film of the composite material. The composite material includes a urethane resin, fine powdered silica gel dispersed in the urethane resin, and small-diameter cellulose dispersed in the urethane resin. In the following, the film produced by using the composite slurry Si will be referred to as film Fi. i is any one of 1 to 5.

Table 2 shows the mass ratios of the fine powder silica gel and the small diameter cellulose in the films F1 to F5. The unit of the mass ratio is mass% with the total mass of the film as 100. Table 2 also shows the types of composite slurries used in the production of each film.

フィルムＦ１～Ｆ５の全光線透過率を測定した。その測定結果を上記表２に示す。フィルムＦ１～Ｆ５のいずれにおいても全光線透過率は高かった。

The total light transmittance of the films F1 to F5 was measured. The measurement results are shown in Table 2 above. The total light transmittance was high in all of the films F1 to F5.

As a comparative example, an additive was added to the urethane resin to produce a film (hereinafter referred to as film R). The types and amounts of additives were varied. The thickness of the film R is the same as the thickness of the films F1 to F5. Then, the total light transmittance of the film R was measured. Table 3 shows the measurement results of the total light transmittance for each type and blending amount of the additive in the film R. The unit of total light transmittance is%.

表３において、「未処理シリカ」は、高圧ジェットミルによる処理を行っていない微粉末状シリカゲルである。「処理シリカ」は、高圧ジェットミルによる処理を１０回繰り返した微粉末状シリカゲルである。「処理シリカ」の平均粒径は１μｍ以下である。「未処理セルロース」は、高圧ジェットミルによる処理を行っていないセルロース粉末である。「処理セルロース」は、高圧ジェットミルによる処理を１回行ったセルロース粉末である。表３における添加量の単位は、フィルムの全質量を１００とする質量％である。表３において、「no data」は、混合しても材料が均一にならないため、フィルムを形成できないことを意味する。

In Table 3, "untreated silica gel" is fine powdered silica gel that has not been treated with a high-pressure jet mill. "Treatment silica" is fine powder silica gel that has been treated with a high-pressure jet mill 10 times. The average particle size of "treated silica" is 1 μm or less. "Untreated cellulose" is a cellulose powder that has not been treated with a high pressure jet mill. "Treatment cellulose" is a cellulose powder that has been treated once with a high-pressure jet mill. The unit of the addition amount in Table 3 is mass% with the total mass of the film as 100. In Table 3, "no data" means that the film cannot be formed because the material is not uniform even when mixed.

In the film R, when the blending amount of the additive was increased, the total light transmittance decreased sharply. Further, when untreated cellulose or treated cellulose was added as an additive, gel formation was observed when the resin and the additive were mixed, and the dispersibility of the additive in the resin was poor. As a result, the total light transmittance of the film R was significantly reduced.

From the above results, it was confirmed that the films F1 to F5 have higher total light transmittance than the film R.
The reason for this is presumed as follows. The films F1 to F5 contain fine powdered silica gel and small-diameter cellulose. There are many silanol groups on the surface of fine powdered silica gel. Small diameter cellulose has a hydroxyl group. By defibrating and breaking the bonds between the cellulose fibers, the surface area of the small-diameter cellulose is increased and the number of hydroxyl groups is further increased. When the fine powder silica gel and the small diameter cellulose are mixed, the small diameter cellulose is bonded on the surface of the fine powder silica gel due to the bond between the silanol group and the hydroxyl group to form composite fine particles. In the resin, the composite fine particles are less likely to aggregate than in the case where only cellulose is present, and are uniformly dispersed in the resin. As a result, the total light transmittance of the films F1 to F5 becomes high.

(4-3) Manufacture and evaluation of composite materials (Part 2)
The urethane resin emulsion and the composite slurry S3 were mixed to prepare a raw material liquid. The raw material liquid was applied onto the glass surface using a film applicator to produce a composite material film F6. The arithmetic mean roughness Ra of the 260 μm square region on this film F6 was measured using a laser microscope. The arithmetic mean roughness Ra was 14 nm.

Further, a test piece having a width of 10 mm and a thickness of 1 mm was prepared from the film F6. The maximum tensile load of this test piece was measured using a tensile tester. The tensile tester is a small tabletop tester manufactured by Tokyo Koki. The maximum tensile load was 2600N.

As a comparative example, untreated cellulose was added to the urethane resin to produce film R1. The amount of untreated cellulose added is 1% by mass. Further, as a comparative example, untreated silica was added to the urethane resin to produce film R2. The amount of untreated silica added is 1% by mass. The unit of the addition amount is mass% with the total mass of the film as 100.

The arithmetic mean roughness Ra of the 260 μm square region on the film R1 was measured. The arithmetic mean roughness Ra was 332 nm. The arithmetic mean roughness Ra of the 260 μm square region on the film R2 was measured. The arithmetic mean roughness Ra was 85 nm.

As a comparative example, a film R3 made of only urethane resin was produced. For the film R3, the maximum tensile load was measured by the same method as described above. The maximum tensile load was 2160N.

From the above results, it was confirmed that the film F6 had a smaller arithmetic mean roughness Ra than the films R1 to R2. Further, it was confirmed that the film F6 has a larger maximum tensile load than the film R3.

The reason for this is presumed as follows. The film F6 contains fine powdered silica gel and small-diameter cellulose. As described above, small-diameter cellulose is bonded to the surface of fine powdered silica gel to form composite fine particles. The composite fine particles are uniformly dispersed in the resin. As a result, the arithmetic average roughness Ra of the film F6 is small, and the maximum tensile load of the film F6 is large.

5. Other Embodiments Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments, and can be variously modified and implemented.

(1) The composite material may have a form other than the film. Examples of the form other than the film include a molded product, a fiber, and the like. The composite material may be, for example, a paint, a lens material, a material for an aircraft or a transport machine, a material for a robot, a building material, a material for a household appliance, or the like. Examples of materials for aircraft and transport aircraft include windows and light covers. Moreover, as a material of a home electric appliance, for example, a touch panel, a screen and the like can be mentioned.
(2) The function of one component in each of the above embodiments may be shared by a plurality of components, or the function of the plurality of components may be exerted by one component. Further, a part of the configuration of each of the above embodiments may be omitted. Further, at least a part of the configuration of each of the above embodiments may be added or substituted with respect to the configuration of the other embodiments. It should be noted that all aspects included in the technical idea specified from the wording described in the claims are embodiments of the present disclosure.

(3) In addition to the above-mentioned composite slurry, composite material, and method for producing a composite slurry, the present disclosure can be realized in various forms such as a product containing the composite material as a component and a method for manufacturing the composite material.

1 ... Substrate, 1A ... Surface, 3 ... Fiber, 5 ... Reference plane

Claims (3)

A mixture containing cellulose and silica particles is supplied to a wet pulverizer, and the cellulose is defibrated using the wet pulverizer to produce small-diameter cellulose having a fiber diameter of 100 nm or less.
A method for producing a composite slurry, which comprises the small-diameter cellulose and the silica particles, and the mass ratio of the silica particles to the mass of the small-diameter cellulose is 0.25 or more and 2.5 or less. The method for producing a composite slurry according to claim 1 .
A method for producing a composite slurry in which the cellulose is defibrated to produce the small-diameter cellulose and the silica particles are miniaturized. The method for producing a composite slurry according to claim 1 or 2 .
The wet crusher is a high pressure jet mill.
A method for producing a composite slurry having a control pressure of 150 MPa or more in the high-pressure jet mill.

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