JP2016176055A - Microfibrillated cellulose and composite body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide developed microfibrillated cellulose with developed microfibril particularly usable, e.g., to an additive for imparting strength to a sheet-shaped matter, a synthetic resin and an inorganic structural material.SOLUTION: Provided is microfibrillated cellulose capable of unevenly distributed on the water face side by the adsorption of a hydrophobization agent in water, in which the concentration dependence of viscosity is represented by the following numerical equation (1) and β is 2.0 or higher, and also provided is a composite body obtained by using the microfibrillated cellulose: η=αexp(βC) (1)(η denotes viscosity; α denotes an extrapolation value at a concentration of 0%; β denotes a parameter(s) regarding concentration dependence; and C denotes a concentration).SELECTED DRAWING: Figure 6

Description

  The present invention relates to microfibrillated cellulose and composites.

  Microfibrillated cellulose is a general term for fibers having a fiber diameter of about 30 nm to 300 nm obtained by mechanically defibrating plant pulp or the like with a high-pressure homogenizer, a ball mill, a refiner, a mortar mill, or the like. The fibrillation state of microfibrillated cellulose is roughly classified into the following three types.

(A) Pulp remains as a trunk component, and fibrils are formed on both ends and surfaces of the trunk.
(B) Although the trunk portion is also an aggregate of fibrillated products, it can still be observed as long fibers.
(C) The state in which the whole is microfibrillated.

  Microfibrillated cellulose is used as a sheet-like material formed only with microfibrillated cellulose, or a sheet-like material formed by mixing with synthetic fibers or inorganic fibers. It is also used as an additive for imparting strength to synthetic resins and inorganic structural materials, as an additive in food, cosmetics, and medical products, and as a filtering material (for example, see Patent Documents 1 to 4). It is considered that there is a suitable microfibrillation state depending on various application fields.

  As the pulp is defibrated, the fibrillated state continuously changes from the state (A) through the state (B) to the state (C), and microfibrillated cellulose having developed microfibrils. Go to change. In order to determine the fibril state, for example, when observed with a scanning electron microscope (SEM), the state (C) can be easily determined because there is almost no trunk component. The fibrillation state is generally defined by Canadian freeness. However, even if the Canadian freeness value is the same, the fibrillation state may be different when the SEM is observed, and states (A) to (C ) Are all observed. In addition, the fibrillation state can be defined by the fiber diameter, fiber length, aspect ratio (fiber length / fiber diameter), and the like. However, in the states (A) and (B), the defibration is in the middle of the continuous change, and it is not sufficient to define only the fiber diameter, fiber length, and aspect ratio (fiber length / fiber diameter). is there.

  Moreover, the fibrillation state may be defined by the viscosity. For example, the B-type viscosity (60 rpm, 20 ° C.) of an aqueous dispersion in 1% (w / v) of microfibrous cellulose having a viscosity of 3000 mPa · s or higher when suspended in water at a concentration of 2% by mass. ) Of 10 to 3000 Pa · s is disclosed (for example, see Patent Documents 7 to 8). However, the states (A) to (C) cannot be discriminated from the measured viscosity values alone, and it was difficult to determine the microfibrillation state suitable for various fields of use.

JP 2012-102509 A JP 2014-169202 A Japanese Patent No. 3641690 Japanese Patent No. 3578570 JP 2004-274661 A Japanese Patent No. 5017668 JP 2007-231438 A JP 2012-207133 A

  An object of the present invention is to obtain developed microfibrillated cellulose, and in particular, it can be used as an additive for imparting strength to sheet-like materials, synthetic resins and inorganic structural materials, and the like. It is to provide a microfibrillated cellulose having microfibrils.

  It has been found that the above problems can be solved by the present invention described below.

(I) It is possible to be unevenly distributed on the water surface side by adsorbing a hydrophobizing agent in water, and the concentration dependency of viscosity is represented by the following formula (1), and β is 2.0 or more , Microfibrillated cellulose.
η = αexp (βC) (1)
(Η is viscosity, α is an extrapolated value at a concentration of 0%, β is a parameter for concentration dependency, and C is a concentration.)

(II) A composite of the microfibrillated cellulose described in (I) above and water glass.
(III) A composite of microfibrillated cellulose and gypsum as described in (I) above.
(IV) A composite of the microfibrillated cellulose described in (I) above and an organosilicate compound-derived siloxane.
(V) A composite of the microfibrillated cellulose described in (I) above and inorganic fibers made of basic magnesium sulfate.
(VI) A composite of the microfibrillated cellulose described in (I) above and a resin.

  In the present invention, developed microfibrillated cellulose can be obtained, and in particular, it can be used as an additive for imparting strength to a sheet-like material, synthetic resin or inorganic structural material.

In comparative example 1-1, it is an optical microscope photograph in the state where linter pulp was dispersed in water. In Comparative Example 1-2, it is the SEM image observed by making the linter pulp after grinding into a sheet. In Example 1-1, it is the SEM image observed by making the linter pulp after defibration into a sheet. In Example 1-1, it is the SEM image observed by making the linter pulp after defibration into a sheet. In Example 1-2, it is the SEM image observed by making the linter pulp after defibration into a sheet. In Example 1-3, it is the SEM image observed by making into a sheet | seat the linter pulp after defibration. It is the graph showing the density | concentration dependence of the viscosity measured in Examples 1-1 to 1-3 and Comparative Examples 1-1 to 1-3. It is the SEM image which observed the composite_body | complex of the microfibrillated cellulose and resin in Example 6-1.

[Microfibrillated cellulose]
The microfibrillated cellulose of the present invention can be unevenly distributed on the water surface side by adsorbing a hydrophobizing agent in water, and the concentration dependency of viscosity is expressed by the following formula (1), where β is It is a microfibrillated cellulose which is 2.0 or more.

  η = αexp (βC) (1)

(Η is viscosity, α is an extrapolated value at a concentration of 0%, β is a parameter for concentration dependency, and C is a concentration.)

  Microfibrillated cellulose is a refined cellulose structure obtained by mechanically defibrating plant pulp or the like in water. Examples of plant pulp include woody pulp such as kraft pulp, dissolved pulp (DP), and dissolved kraft pulp (DKP) using hardwood (L material) and coniferous material (N material). Also, non-wood pulp such as straw, hemp and cotton can be mentioned. Since the plant pulp that is easily microfibrillated is a high-purity α-cellulose body, DP and DKP are preferable in the case of woody pulp, and cotton and cotton linter are preferable in the case of non-woody pulp.

  In order to obtain microfibrillated cellulose, the pulp is first dispersed in water and mechanically pulverized, and the fibers of the pulp are defibrated to form microfibrils. A suitable method for defibrating the pulp is a method of cutting the fiber with a disc refiner, a stone mill type grinder or the like, and defibrating with a high-pressure homogenizer, a ball mill, an underwater counter collision method, or the like. Further, among high-purity α-cellulose bodies, pulp having a cellulose body having a high molecular weight such as cotton or cotton linter has already been microfibrillated at the stage of cutting fibers by a disc refiner, a grinding machine or the like.

  In any case, the pulp is fibrillated and microfibrillated while the fiber length is reduced. The defibrated fiber diameter has a large distribution of about 30 nm to 300 nm, and further, the defibrated portion remains and has a complicated fibrillated state. The fibrillation state of microfibrillated cellulose is roughly classified into the following three types.

(A) Pulp remains as a trunk component, and fibrils are formed on both ends and surfaces of the trunk.
(B) Although the trunk portion is also an aggregate of fibrillated products, it can still be observed as long fibers.
(C) The state in which the whole is microfibrillated.

  The microfibrillated cellulose of the present invention can be unevenly distributed on the water surface side by adsorbing a hydrophobizing agent in water. This method is a method for determining the presence or absence of developed microfibrils. Specifically, a minute amount of a hydrophobizing agent is added in water and shaken. Then, the microbubble part embraces the generated bubbles, and the entire fiber is lifted to the water surface side (is unevenly distributed). Such cellulose that is unevenly distributed on the water surface side has developed microfibrils, so when used as an additive for imparting strength to sheet-like materials, synthetic resins and inorganic structural materials, other components It is easy to obtain effects such as excellent miscibility with and improved strength.

  Hydrophobizing agents include hydrocarbon solvents such as hexane and heptane, aromatic solvents such as benzene, toluene, and xylene, and terpene solvents such as terpene and limonene. Is a more preferable material because it is excellent in bubble property.

  The amount of the hydrophobizing agent added to cellulose is preferably 0.01% by mass or more and 300% by mass or less, and more preferably 0.1% by mass or more and 200% by mass or less of cellulose. Within this concentration range, the effect of easily determining the presence or absence of developed microfibrils is more manifested.

  Since the fibrillated state changes continuously, it is difficult to uniquely define this complex fibrillated state. In the present invention, it has been found that the concentration dependency of viscosity is effective in defining this fibrillation state.

  The viscosity in a state where microfibrillated cellulose is dispersed in water strongly depends on the concentration itself in a low concentration region, and depends on the state of entangled microcellulose in a high concentration region. The boundary between the two regions often exists between 0.1 and 0.6% by mass. In the region where the concentration is high, the viscosity of the pulp that does not form microfibrils or the pulp (A) that forms a very small amount of microfibrils has a correlation between linear and secondary with respect to the concentration. When the microfibril develops and shifts to the state (B) or (C), the concentration becomes correlated with a value exceeding the second order. In particular, in a state where microfibrils are formed around a trunk derived from pulp, there is a correlation exceeding the third order. However, when defibration further progresses and the fiber length is cut, the microfibrillated fibers are separated from each other, and the concentration correlation decreases again to approach the second order.

  Viscosity measurement methods include rotational viscometers that measure from torque fluctuations of rotating bodies, Ostwald viscometers that are measured by dropping inside narrow tubes, orifice viscometers, falling ball viscometers, bubble viscometers, and vibration viscometers. However, it is preferable to use a rotational viscometer (B-type rotational viscometer) in order to compare the viscosities of cellulose dispersions when the cellulose has a large structure.

  The rotational viscometer measures the shear stress when the dispersion is displaced as a change in torque. Since the microfibril portion has a high specific surface area and has a strong interaction via water, the shear stress at the time of displacement reflects the interaction of the microfibril. In particular, important information on the microfibril portion can be obtained from the data of the rotational viscometer in the region of the concentration of 0.1 mass% to several mass% where the interaction becomes significant.

In the present invention, the concentration dependence of the viscosity of this portion is described as in equation (1).
η = αexp (βC) (1)

(Η is viscosity, α is an extrapolated value at a concentration of 0% by mass, β is a parameter for concentration dependence, and C is a concentration.)

  β contains the form factor of cellulose. As described above, β in the pulp not forming microfibrils or the pulp (A) in which a very small amount of microfibrils is formed is about 1.0 to 1.5. When microfibrillation proceeds slightly, β exceeds 2.0. And in the state which microfibril formed in the circumference centering on the trunk derived from a pulp, it will exceed 3.0. On the other hand, when pulverization of cellulose proceeds simultaneously with defibration, β returns to the vicinity of 2.0 again. Such a change in which β exceeds 3 is considered to be due to a synergistic effect of the correlation between the microfibril portion and the correlation between the remaining pulp-derived non-microfibrillated stem components, and the fibrillation has progressed sufficiently. In a state where no component remains, the β value is about 2 to 2.5. Cellulose that has undergone microfibrillation with β returning to near 2.0 has a property of embedding bubbles with a hydrophobizing agent and floating on the water surface side. On the other hand, when microfibrillation progresses slightly and β is in the vicinity of 2.0 or exceeds 2.0, it does not have the property of floating on the water surface side. Whether or not it is a developed microfibrillated cellulose is important that it can be unevenly distributed on the water surface side by adsorbing a hydrophobizing agent in water at the same time that β is 2.0 or more.

  When microfibrillated cellulose that can float to the water surface side with a hydrophobizing agent and β is 2.0 or more is observed with an SEM, it is found that the fiber has a fiber length of about 100 μm and a fiber diameter of about 100 nm. In other words, since it has a very high aspect ratio exceeding 1000, when used as an additive for imparting strength to sheet-like materials, synthetic resins and inorganic structural materials, it is miscible with other components. It is easy to obtain effects such as excellent properties and improved strength.

  The composite of the microfibrillated cellulose of the present invention and various materials will be described.

[Composite of microfibrillated cellulose and water glass]
Water glass is a room temperature curable ceramic, but when it is shaped like a sheet, it is brittle and easily collapses. On the other hand, cellulose is stable in water glass and can play a role of imparting strength when combined with water glass. However, the pulp used as a raw material for paper as cellulose sometimes undergoes a shape change due to the influence of the remaining hemicellulose. Further, the fiber diameter of the pulp is 20 to 30 μm, the fiber length is several mm, and it is very large, so it is not suitable for adding to a sheet-like material or a relatively small structural material (Patent Document 1: JP, 2012-102509, A). The composite of microfibrillated cellulose and water glass of the present invention has a stable structure and can take a shape such as a sheet-like material.

Water glass is a curable inorganic agent mainly composed of sodium silicate, and is a room temperature curable ceramic. The general formula is represented by Na ₂ O.nSiO ₂ .mH ₂ O. Here, n is about 0.5 to 4.0. Water glass having n of 1 or less is called sodium orthosilicate, and the sodium component is excessive, and the curability by silicic acid may be inhibited. Usually, n is preferably 1 or more (sodium metasilicate), and more preferably n is more than 1.

  Further, when the content of silicic acid increases, a large amount of polysilicate ions are contained, and the viscosity of the aqueous solution increases, but the curing rate also increases. As a curing method, there are a method of adding an acid such as sulfuric acid or hydrochloric acid, a method of curing sodium as a carbonate by leaving it in the atmosphere.

  When the microfibrillated cellulose of the present invention and water glass are combined, a composite (sheet composite) in the form of a translucent sheet is obtained. The content of microfibrillated cellulose suitable for obtaining a sheet-like composite is preferably 5 to 90% by mass, more preferably 15 to 70% by mass with respect to the total solid content. If the content of microfibrillated cellulose is too small, the sheet-like composite may not maintain its shape and may collapse. Moreover, when there is too much microfibrillated cellulose content, it deform | transforms at the time of dry solidification, etc., and a favorable sheet-like composite body may not be obtained.

  This sheet-like composite can be produced by a method of drying after coating on a substrate, a method of casting in a container of a certain size, drying and solidifying, and the like. The thickness of the sheet composite can be appropriately selected within a range of 10 μm to 30 cm. A more preferable thickness is 20 μm to 20 cm. The sheet-like composite can be transferred to a predetermined curved surface when dried, and can be cut into a rod shape and cut into a cylindrical shape. Furthermore, several layers of thin sheet-like composites can be stacked and combined with a thermoplastic resin or a thermosetting resin.

  The composite of the microfibrillated cellulose and water glass of the present invention has a stable structure and can take a shape such as a sheet-like material. This composite is translucent and does not ignite, and can be used in civil engineering, architecture, and optical fields

[Composite of microfibrillated cellulose and gypsum]
When calcined gypsum is added with water, the combined water changes and hardens. A general gypsum boat is manufactured by mixing pulp and calcined gypsum, adding water, and further mixing and drying. However, the pulp used as a raw material for paper has a problem that it has a weak binding force with gypsum and tends to collapse when the gypsum board is made thin. For this reason, Patent Document 2 (Japanese Patent Laid-Open No. 2014-169202) proposes gypsum reinforced with microfibrillated cellulose, but microfibrillation is performed by chemical treatment, and cellulose is fine. However, there is a problem that the state of microfibrils is not sufficient to stabilize the structure by interacting with the gypsum particles. With the composite of microfibrillated cellulose and gypsum of the present invention, a composite having a high strength and a stable structure can be obtained.

  In the composite of microfibrillated cellulose and gypsum obtained by mixing the microfibrillated cellulose and calcined gypsum of the present invention, a sheet-like composite with high strength is obtained. The content of microfibrillated cellulose suitable for obtaining a sheet-like composite is preferably 5 to 90% by mass, more preferably 15 to 70% by mass with respect to the total solid content. If the content of microfibrillated cellulose is too small, the sheet-like composite may not maintain its shape and may collapse. Moreover, when there is too much microfibrillated cellulose content, it deform | transforms at the time of dry solidification, etc., and a favorable sheet-like composite body may not be obtained.

  This sheet-like composite can be produced by a method of drying after coating on a substrate, a method of casting in a container of a certain size, drying and solidifying, and the like. The thickness of the sheet composite can be appropriately selected within a range of 10 μm to 30 cm. A more preferred thickness is 20 μm to 30 cm, and even more preferred is 50 μm to 20 cm. The sheet-like composite can be transferred to a predetermined curved surface when dried, and can be cut into a rod shape and cut into a cylindrical shape. Furthermore, several layers of thin sheet-like composites can be stacked and combined with a thermoplastic resin or a thermosetting resin.

  The composite of microfibrillated cellulose and gypsum according to the present invention has high strength and can be used in fields such as civil engineering and construction.

[Composite of microfibrillated cellulose and siloxane]
When microfibrillated cellulose is made into a sheet, it becomes a translucent film, and when added to a thermoplastic resin or thermosetting resin to form a structure, it has a density lower than that of a magnesium alloy, but exhibits comparable strength. (Patent Document 3: Japanese Patent No. 3641690). However, there is a problem to use as a structure, for example, it expands when absorbed by humidity and burns when ignited.

  On the other hand, organosilicate compounds are hydrolyzed with alkoxysilane groups by the sol-gel method. By the condensation reaction of the silanol group thus generated, siloxane can gradually grow to form a structure. Silanol groups are known to react with alcoholic hydroxyl groups and have been used to modify various polymers. However, even when used on cellulose surfaces such as pulp, the entire surface is covered with oxygen. There was no shielding, and no combustion suppression effect appeared.

  With the composite of the microfibrillated cellulose and siloxane of the present invention, an effect that it is difficult to burn can be obtained.

  The siloxane according to the present invention is an organic silicate compound-derived siloxane. The organic silicate compound is a compound that generates a silanol group by hydrolysis, and the following four types are known.

Here, R is an alkyl group such as methyl, ethyl and propyl, R ₁ , R ₂ and R ₃ are alkyl groups such as methyl, ethyl, propyl, n-butyl and stearyl, alkenyl groups such as allyl group, benzyl and phenyl An unsaturated hydrocarbon group such as

  In an organic silicate compound, an alkenyl group (Si—OR) is hydrolyzed in water containing an acid or an alkali to form a silanol group (Si—OH). Next, silanol groups undergo a condensation reaction to form siloxane (Si—O—Si), which is polymerized. In the condensation reaction, it also reacts with an alcoholic hydroxyl group, so that it is combined with a hydroxyl group on the surface of the microfibrillated cellulose, and siloxane is formed on the surface of the microfibrillated cellulose.

  The microfibrillated cellulose of the present invention has developed microfibrils, and a siloxane structure that grows after hydrolysis can develop while adsorbing on the surface of the microfibrillated cellulose, and can coat the surface. The obtained composite of microfibrillated cellulose and siloxane has a combustion suppressing effect.

  A method for producing a composite of microfibrillated cellulose and siloxane of the present invention will be described. The organic silicate compound is first dispersed or dissolved in water using a solvent compatible with water such as alcohol. After that, when a reaction catalyst such as hydrochloric acid is added and the siloxane is grown in the presence of the microfibrillated cellulose, the siloxane is adsorbed on the surface of the microfibrillated cellulose to form a siloxane-derived silanol group. It becomes possible.

  Next, the solvent and water are removed by casting or filtration, and the sheet is made into a sheet, the microfibrils of microfibrillated cellulose are brought into close contact with each other, heated and dried, and the final condensation reaction is completed. Between fibrils is fixed. The amount of the organic silicate compound added at this time is preferably 2 to 300 parts by mass, more preferably 10 to 100 parts by mass with respect to 100 parts by mass of cellulose.

  The obtained composite is a sheet-like composite, and the thickness can be freely adjusted in the range of 10 μm to 30 cm. A more preferable thickness is 20 μm to 20 cm. This sheet-like composite can be transferred to a curved surface by being held on a predetermined curved surface when dried. It is also possible to cut it into a rod shape and cut it into a cylindrical shape. Furthermore, several layers of thin sheet-like composites can be stacked and combined with a thermoplastic resin or a thermosetting resin.

  The composite of the microfibrillated cellulose and siloxane of the present invention hardly burns, and can be used for optical materials, building materials, civil engineering materials and the like.

[Composite of microfibrillated cellulose and inorganic fiber made of basic magnesium sulfate]
Inorganic fiber made of basic magnesium sulfate is easy to dissolve in the living body and has the advantage that it does not remain in the lungs even if aspirated. It is used as a reinforcing material for compounding with resin, and for speakers, etc. (Patent Document 4: Japanese Patent No. 3578570, Patent Document 5: Japanese Patent Application Laid-Open No. 2004-274661). Furthermore, there has been proposed a fire-resistant sheet-like material that does not generate cracks by being combined with water glass (Patent Document 6: Japanese Patent No. 5017668). However, the density of the obtained sheet-like material was approximately 0.94, and it was not a low-density and lightweight sheet-like material.

  According to the composite of the microfibrillated cellulose of the present invention and the inorganic fiber made of basic magnesium sulfate, it has a stable structure, and a low-density composite can be obtained, such as civil engineering, architecture, filtration, etc. Can be used in the field.

The microfibrillated cellulose of the present invention is cellulose that is unevenly distributed on the water surface side and has developed microfibrils. Fully developed microfibrillated cellulose has a wide distribution of fiber diameters and fiber lengths, with the fiber diameter of the microfibril portion being about 30 nm to 300 nm and the fiber length being about 50 to 500 μm. Since this microfibrillated cellulose has an active hydrophilic portion that is flexible and has a hydroxyl group on its surface, it can be captured while entwining basic magnesium sulfate fibers. Since the trapped basic magnesium sulfate fibers are fixed to each other, it is possible to maintain a void in the drying step and maintain a low-density structure. The low density in the present invention is from 0.1 to 0.8 g / cm ³ , more preferably from 0.2 to 0.6 g / cm ³ .

  In addition to basic magnesium sulfate fibers and microfibrillated cellulose, the composite of the present invention can be combined with a reactive inorganic material as a fixing agent. Examples of the reactive inorganic material include boric acid, borates, organic zirconium compounds, water glass, calcined gypsum, and organic silicate compounds. In particular, water glass is a preferred material from the viewpoint of being inexpensive and non-combustible and having excellent water resistance.

  Microfibrillated cellulose is made in water and prepared as a dispersion in which water is the medium. In order to obtain the composite of the present invention, a mixed solution is prepared by mixing basic magnesium sulfate fibers with a dispersion having a concentration of 0.5% by mass to 3% by mass. The mixing amount of the microfibrillated cellulose with respect to the basic magnesium sulfate fiber is preferably 0.2% by mass to 30% by mass, and more preferably 1% by mass to 10% by mass. If the mixing amount of microfibrillated cellulose is too small, the structure of basic magnesium sulfate fibers cannot be maintained, the density is improved, and it may be difficult to obtain a low-density composite. Moreover, when there is too much mixing amount of microfibrillated cellulose, the interaction between microfibrillated cellulose is reflected strongly and it may be difficult to obtain a low density composite body.

  After mixing the aqueous dispersion of microfibrillated cellulose and basic magnesium sulfate fiber while maintaining fluidity, it is molded into a sheet or board by the casting method, extrusion method, etc., and then heated and dried. As a result, a composite is obtained. The thickness of the composite can be appropriately selected within the range of 1 mm to 50 cm, more preferably 10 mm to 20 cm. The sheet-like or board-like composite can be transferred to a curved surface by being held on a predetermined curved surface during drying. It is also possible to cut it into a rod shape and cut it into a cylindrical shape. Furthermore, several layers of thin sheet-like composites can be stacked and combined with a thermoplastic resin or a thermosetting resin.

[Composite of microfibrillated cellulose and resin]
A material obtained by microfibrillating cellulose (referred to as cellulose microfibril or microfibrillated cellulose) has a specific gravity of 1.5 and a bending strength of 200 MPa or more, and a high strength comparable to a magnesium alloy can be obtained. It is also disclosed that a composite with a thermosetting resin or a thermoplastic resin can also be produced (Patent Document 1: Japanese Patent No. 3641690). However, at present, it has been difficult to determine a fibrillated state suitable for a composite of microfibrillated cellulose and a resin. In the composite of the microfibrillated cellulose and the resin of the present invention, a composite having excellent strength can be obtained.

  Examples of the resin according to the present invention include polyolefins such as polyethylene, polypropylene (PP) and acid-modified polypropylene; polystyrenes; halogen resins such as acrylic resins represented by polymethyl methacrylate and polyvinyl chloride; thermosetting resins and the like. Can be mentioned. Polyolefins that are excellent in various properties and can be kneaded at a relatively low temperature are preferred resins.

  The microfibrillated cellulose of the present invention is a cellulose that is unevenly distributed on the water surface side, and has developed microfibrils. Therefore, when added to a resin, effects such as improvement in strength are easily obtained.

  The microfibrillated cellulose having the characteristics in the present invention is made into a predetermined concentration by removing excess water by a centrifugal separation method or a pressure dehydration method, and is kneaded with a resin using a biaxial kneader or a Henschel mixer. A complex is obtained. The content of microfibrillated cellulose in the composite is preferably 5% by mass to 90% by mass, and more preferably 10% by mass to 70% by mass with respect to the total solid content. If the content of microfibrillated cellulose is small, strength properties may not be improved. If the content is too high, fluidity may be reduced, and injection molding may be difficult. The obtained composite can be formed into a molded product by an injection molding method or an extrusion molding method.

  EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited to these at all.

[Preparation of microfibrillated cellulose]
(Comparative Example 1-1)
Using a mixer, linter pulp (cellulose) was dispersed in water at a concentration of 2.0% by mass. FIG. 1 is an optical micrograph observing the fiber state at this time. Next, using a B-type rotational viscometer (manufactured by Toki Sangyo Co., Ltd., rotor No. 3, rotation speed 60 rpm, temperature 23 ° C.), the concentration dependency of the viscosity from 0.1% by mass to 2.0% by mass. Was measured. FIG. 7 is a graph showing the concentration dependency of the viscosity measured in Examples 1-1 to 1-3 and Comparative Examples 1-1 to 1-3. The extrapolated value (α value) at a concentration of 0% by mass was 12.6, and the shape factor (β value) was 1.34. The average fiber length of the pulp was measured by an optical measurement method (Metso Automation Co., Ltd., using Kayani Fiber Lab fiber length measuring instrument. Length weighted average value) and found to be 1.1 mm. Next, linter pulp is dispersed in water at a concentration of 0.2% by mass, put into a stoppered graduated cylinder, hexane is added so as to be 20% by mass with respect to cellulose, and shaken vigorously. The pulp gradually settled over time.

(Comparative Example 1-2)
A 2.0 mass% aqueous dispersion of linter pulp (cellulose) was pulverized with a mass collider (registered trademark, manufactured by Masuko Sangyo Co., Ltd., 12-inch grinding wheel 46 mesh, rotational speed 1500 rpm) to pulverize pulp fibers. FIG. 2 is an SEM image obtained by observing the pulverized linter pulp as a sheet. The concentration dependency of the viscosity from 0.6% by mass to 1.2% by mass was measured. The α value was 29.1 and the β value was 1.75. The average fiber length was 0.7 mm. From the SEM image, it was found that a part of the microfibril was formed, but the generated part was slight. Next, the pulp pulverized product is dispersed in water at a concentration of 0.2% by mass, put into a stoppered graduated cylinder, hexane is added so as to be 20% by mass with respect to cellulose, and shaken vigorously. Allowed to stand. Some of the pulverized pulp floated on the water surface side and some cellulose retained air bubbles, but the other pulverized pulp gradually settled.

(Comparative Example 1-3)
Using a mixer, disperse Celish (registered trademark) KY-100G made by Daicel Finechem, which is a commercially available microfibrillated cellulose, with water, and at a concentration of 0.3 mass% to 1.0 mass%, the viscosity concentration Dependency was measured. The α value was 18.1 and the β value was 3.4. Next, it was dispersed in water at a concentration of 0.2% by weight, put into a stoppered graduated cylinder, hexane was added so as to be 20% by weight with respect to cellulose, vigorously shaken, and then allowed to stand. . Some of the microfibrillated cellulose floated on the water surface side and some of the cellulose retained air bubbles, but other microfibrillated cellulose gradually settled.

(Example 1-1)
Linter pulp (cellulose) concentration 3.0 mass% aqueous dispersion was pulverized with a mascolloider (registered trademark, manufactured by Masuko Sangyo Co., Ltd., 12-inch grinding wheel 80 mesh, rotational speed 1500 rpm) to defibrate the fibers. 3 and 4 are SEM images obtained by observing the linter pulp after defibration as a sheet. When the concentration dependency of the viscosity from 0.6% by mass to 1.2% by mass was measured, the α value was 42.7 and the β value was 2.11. Although the average fiber length was 0.2 mm, there were many unmeasureable materials. From the SEM image of FIG. 4, it can be seen that the microfibril portion is sufficiently formed and the remaining amount of the trunk portion is small. Next, the pulp defibrated material is dispersed in water at a concentration of 0.2% by mass, put into a stoppered graduated cylinder, hexane is added so as to be 20% by mass with respect to cellulose, and shaken vigorously. Then, when allowed to stand, the entire amount floated to the water surface side and was unevenly distributed.

(Example 1-2)
A 4.0 mass% aqueous dispersion of linter pulp (cellulose) was pulverized with a mass collider (registered trademark, manufactured by Masuko Sangyo Co., Ltd., 12-inch grinding wheel 80 mesh, rotational speed 1500 rpm) to defibrate the fibers. FIG. 5 is an SEM image obtained by observing the linter pulp after defibration as a sheet. The concentration dependency of the viscosity from 0.6% by mass to 1.2% by mass was measured. The α value was 24.6, and the β value was 2.61. The average fiber length was 0.25 mm, but there were many unmeasurable materials. From the SEM image of FIG. 5, it can be seen that the microfibril portion is sufficiently formed and the fibers having a long trunk portion remain. Next, the pulp defibrated material is dispersed in water at a concentration of 0.2% by mass, put into a stoppered graduated cylinder, hexane is added so as to be 20% by mass with respect to cellulose, and shaken vigorously. Then, when allowed to stand, the entire amount floated to the water surface side and was unevenly distributed.

(Example 1-3)
The dispersion of linter pulp (cellulose) having a concentration of 1.5% by mass was pulverized with a mascolloider (registered trademark, manufactured by Masuko Sangyo Co., Ltd., 6-inch grinding wheel 80 mesh, rotational speed 1500 rpm) to pulverize the fibers. FIG. 6 is an SEM image obtained by observing the pulverized linter pulp as a sheet. The concentration dependency of the viscosity from 0.6% by mass to 1.2% by mass was measured. The α value was 59.3, and the β value was 2.42. The average fiber length was 0.2 mm or less. From FIG. 6, it can be seen that a microfibril portion is formed and a long pulp portion remains. Next, the pulp pulverized product is dispersed in water at a concentration of 0.2% by mass, put into a stoppered graduated cylinder, hexane is added so as to be 20% by mass with respect to cellulose, and shaken vigorously. When allowed to stand, the entire amount floated to the water surface side and was unevenly distributed.

[Composite of microfibrillated cellulose and water glass]
(Examples 2-1 to 2-3)
The microfibrillated cellulose prepared in Examples 1-1 to 1-3 and dispersed in water was concentrated to a concentration of 17% by mass using a centrifuge. This is referred to as concentrates 2-1 to 2-3. While stirring the concentrates 2-1 to 2-3, water glass (n = 2: silicic acid molar ratio is 2) is added to adjust the mass ratio of cellulose / water glass to 4/6. did. Next, the sheet was stretched with an extruder to prepare a wet sheet having a thickness of 20 cm, and dried in a drier to obtain translucent sheet-like composites 2-1 to 2-3 having a thickness of 2 cm. Although the sheet-like composites 2-1 to 2-3 were ignited, they were blackened but did not ignite.

(Examples 2-4 to 2-6)
To the concentrates 2-1 to 2-3 prepared in Examples 2-1 to 2-3, the same water glass as that used in Example 2-1 was mixed in the same ratio, and TPX (registered trademark, methyl) was mixed. It was cast on a petripolymer petri dish and then dried to obtain a translucent sheet-like composite having a thickness of 30 μm. As in Examples 2-1 to 2-3, no ignition occurred even when ignited.

(Comparative Examples 2-1 to 2-3)
The microfibrillated cellulose prepared in Comparative Examples 1-1 to 1-3 and dispersed in water was concentrated to a concentration of 17% by mass using a centrifuge. This is referred to as comparative concentrates 2-1 to 2-3. While stirring the comparative concentrates 2-1 to 2-3, water glass (n = 2: silicic acid molar ratio is 2) is added so that the mass ratio of cellulose / water glass becomes 4/6. It was adjusted. Next, the sheet was stretched by an extruder to prepare a wet sheet having a thickness of 20 cm and dried in a dryer. In Comparative Examples 2-1 and 2-2, the structure was broken during drying, and a sheet-like composite was not obtained. In Comparative Example 2-3, a sheet-like composite was obtained, but ignited when ignited.

(Comparative Examples 2-4 to 2-6)
To the comparative concentrates 2-1 to 2-3 prepared in Comparative Examples 2-1 to 2-3, the same water glass as used in Example 2-1 was mixed in the same ratio, and TPX (registered trademark, It was cast on a petri dish made of (methylpentene polymer) and dried to produce a 30 μm thick translucent sheet composite, but it collapsed during drying and could not be taken out.

[Composite of microfibrillated cellulose and gypsum]
(Examples 3-1 to 3-3)
The microfibrillated cellulose prepared in Examples 1-1 to 1-3 and dispersed in water was concentrated to a concentration of 17% by mass using a centrifuge. This is referred to as concentrates 3-1 to 3-3. While stirring the concentrates 3-1 to 3-3, water and calcined gypsum were added to adjust the mass ratio of cellulose / calcined gypsum to 4/6. Next, the sheet was stretched with an extruder to produce a wet sheet having a thickness of 20 cm and dried in a drier to obtain sheet-like composites 3-1 to 3-3 having a thickness of 2 cm and high strength. .

(Examples 3-4 to 3-6)
The same calcined gypsum used in Example 3-1 was mixed with the concentrates 3-1 to 3-3 prepared in Examples 3-1 to 3-3 at the same ratio, and TPX (registered trademark, methyl) was mixed. A sheet-shaped composite 3-4 to 3-6 having a thickness of 60 [mu] m was obtained after casting on a petripolymer petri dish.

(Comparative Example 3-1)
Cellulose chemical pulverized product manufactured by Asahi Kasei Chemicals Co., Ltd. (trade name: Theolas (registered trademark) ST-100 (average fiber length 50 μm)) is dispersed in water at a concentration of 0.2% by mass and charged into a closed graduated cylinder. Then, hexane was added so as to be 20% by mass with respect to the cellulose, shaken vigorously, and then allowed to stand still, but the cellulose was all precipitated.

  Next, the chemical pulverized product of cellulose and calcined gypsum were mixed while adding water to adjust the mass ratio of cellulose / calcined gypsum to 4/6. Next, a wet sheet having a thickness of 20 cm was produced by stretching with an extruder and dried in a drier. However, the structure was broken during drying, and a sheet-like composite was not obtained.

(Comparative Example 3-2)
The same chemical pulverized product of cellulose and calcined gypsum used in Comparative Example 3-1 were mixed while adding water, and mixed so that the mass ratio of cellulose / calcined gypsum was 4/6, and TPX (Registered trademark, methyl pentene polymer) After casting on a petri dish, drying was attempted to obtain a sheet-like composite having a thickness of 60 μm. However, the sheet-like composite collapsed during drying and could not be taken out.

(Comparative Examples 3-3 to 3-5)
The microfibrillated cellulose prepared in Comparative Examples 1-1 to 1-3 and dispersed in water was concentrated to a concentration of 17% by mass using a centrifuge. This is referred to as comparative concentrates 3-1 to 3-3. While stirring the comparative concentrates 3-1 to 3-3, water and calcined gypsum were added to adjust the mass ratio of cellulose / calcined gypsum to 4/6. Next, the sheet was stretched with an extruder to produce a wet sheet having a thickness of 20 cm and dried in a dryer to obtain a sheet-like composite having a thickness of 2 cm. However, the structure was broken during drying. Thus, a sheet-like composite was not obtained.

(Comparative Examples 3-6 to 3-8)
The same calcined gypsum used in Example 3-1 was mixed with the comparative concentrates 3-1 to 3-3 produced in Comparative Examples 3-3 to 3-5 at the same ratio, and TPX (registered trademark, After casting on a petri dish made of (methylpentene polymer), it was dried to obtain a sheet-like composite having a thickness of 60 μm, but it collapsed during drying and could not be taken out.

[Composite of microfibrillated cellulose and siloxane]
(Example 4-1)
As an organic silicate compound, 40 parts by mass of tetraethyl orthosilicate was mixed with 200 parts by mass of ethanol / water (mass ratio 6/4 mixed solvent), and 0.1 part by mass of hydrochloric acid was added. This mixed solution was added to 1000 parts by mass of the microfibrillated cellulose dispersion (concentration: 2.5% by mass) of Example 1-1 and heated at 60 ° C. for 12 hours to obtain a mixed solution.

  The obtained mixed solution was filtered and washed on a filter paper, and the filtered product was dried at 80 ° C. for 4 hours to obtain a sheet-like composite having a thickness of 200 μm. When this sheet composite was ignited, the ignited portion was blackened but did not spread.

(Examples 4-2 to 4-3)
A sheet composite was prepared in the same manner as in Example 4-1, except that the microfibrillated cellulose of Examples 1-2 to 1-3 was used instead of the microfibrillated cellulose of Example 1-1. Obtained. When this sheet composite was ignited, the ignited portion was blackened but did not spread.

(Comparative Example 4-1)
A sheet-like composite was obtained in the same manner as in Example 4-1, except that the cellulose of Comparative Example 1-1 was used instead of the microfibrillated cellulose of Example 1-1. The body could not be made into a sheet and became a fluffy composite. When this fluffy composite was ignited, it was burned out.

(Comparative Examples 4-2 to 4-3)
A sheet-like composite was prepared in the same manner as in Example 4-1, except that the microfibrillated cellulose of Comparative Examples 1-2 to 1-3 was used instead of the microfibrillated cellulose of Example 1-1. Obtained. When this sheet composite was ignited, it was burned out.

[Composite of microfibrillated cellulose and inorganic fiber made of basic magnesium sulfate]
(Example 5-1)
To 60 parts by mass of the microfibrillated cellulose dispersion (concentration 1% by mass) prepared in Example 1-1, basic magnesium sulfate fiber (manufactured by Ube Materials Co., Ltd., trade name: Mosheidi (registered trademark)) 6 A part by mass was added and mixed well, and this was cast and dried to prepare a board-like composite having a 50 mm square and a thickness of 10 mm. The mass was 6 g, the density was 0.24 g / cm ³ , and the density was low.

(Example 5-2)
To 60 parts by mass of the microfibrillated cellulose dispersion (concentration 1% by mass) prepared in Example 1-1, 6 parts by mass of basic magnesium sulfate fiber (manufactured by Ube Material Co., Ltd., trade name: Mosheidi (registered trademark)). And 3 parts sodium silicate (manufactured by Fuji Chemical Co., Ltd., concentration 38% by mass) are added, mixed thoroughly, cast and dried, and a 50 mm square, 10 mm thick board A shaped composite was prepared. The mass was 7.5 g, the density was 0.30 g / cm ³ , and the density was low. The boat-like composite ignited but did not burn.

(Example 5-3)
A board-shaped composite was produced in the same manner as in Example 5-1, except that the microfibrillated cellulose prepared in Example 1-2 was used instead of the microfibrillated cellulose prepared in Example 1-1. did. The mass was 6.5 g, the density was 0.26 g / cm ³ , and the density was low.

(Example 5-4)
A board-shaped composite was produced in the same manner as in Example 5-1, except that the microfibrillated cellulose prepared in Example 1-3 was used instead of the microfibrillated cellulose prepared in Example 1-1. did. The mass was 5.5 g, the density was 0.22 g / cm ³ , and the density was low.

(Comparative Example 5-1)
A board-like composite was produced in the same manner as in Example 5-1, except that the cellulose prepared in Comparative Example 1-1 was used instead of the microfibrillated cellulose prepared in Example 1-1. The mass was 24 g, and the density was 0.96 g / cm ³ , which was a high density.

(Comparative Example 5-2)
A board-shaped composite was produced in the same manner as in Example 5-1, except that the microfibrillated cellulose prepared in Comparative Example 1-2 was used instead of the microfibrillated cellulose prepared in Example 1-1. did. The mass was 23 g, and the density was 0.92 g / cm ³ , which was a high density.

(Comparative Example 5-3)
Instead of the microfibrillated cellulose prepared in Example 1-1, the same method as in Example 5-1, except that a commercially available microfibrillated cellulose manufactured by Daicel Finechem, Selish (registered trademark) KY-100G was used. Thus, a board-like composite was produced. The mass was 22 g, and the density was 0.88 g / cm ³ , which was a relatively high density.

  According to the present invention, a composite of basic magnesium sulfate fiber and microfibrillated cellulose having a low density and a stable structure could be obtained.

[Composite of microfibrillated cellulose and resin]
(Comparative Example 6-1)
The pulp dispersion prepared in Comparative Example 1-1 and dispersed in water was concentrated to a concentration of 30% by mass using a centrifuge. This is referred to as comparative concentrate 6-1. Next, using the comparative concentrate 6-1 with the following composition, the microfibrillated cellulose and the resin were placed in a biaxial kneader with a vent and kneaded, but the microfibrillated cellulose was unevenly distributed, Injection molding was not possible.

<Combination>
Microfibrillated cellulose 10 parts by mass (solid content conversion)
PP (manufactured by Prime Polymer, trade name: J3053HP) 88 parts by mass Acid-modified PP (manufactured by Mitsubishi Chemical, trade name: Modic (registered trademark) P928) 2 parts by weight

(Comparative Example 6-2)
The microfibrillated cellulose prepared in Comparative Example 1-2 and dispersed in water was concentrated to a concentration of 20% by mass using a centrifuge. This is referred to as comparative concentrate 6-2. Next, using the comparative concentrate 6-2, the same composition as in Comparative Example 6-1 was used, and the microfibrillated cellulose and the resin were put into a biaxial kneader with a vent and kneaded to prepare a resin composite. This resin composite was injection-molded to produce a dumbbell piece having a width of 10 mm and a thickness of 4 mm according to JIS standard K7171, and tested using a product name: AutoCom (registered trademark) / AC-100 manufactured by TS When the bending characteristics were measured at a speed of 2 mm / min and a distance between fulcrums of 64 mm, the bending strength was 38 MPa and the bending elastic modulus was 1500 MPa.

(Comparative Example 6-3)
A commercially available microfibrillated cellulose, Daicel Finechem, Serish (registered trademark) KY-100G and resin used in Comparative Example 1-3, the same formulation as Comparative Example 6-1 and a vented twin-screw kneader And kneaded to prepare a resin composite. This resin composite was injection-molded to produce a dumbbell piece having a width of 10 mm and a thickness of 4 mm according to JIS standard K7171, and tested using a product name: AutoCom (registered trademark) / AC-100 manufactured by TS When the bending characteristics were measured at a speed of 2 mm / min and a fulcrum distance of 64 mm, the bending strength was 35 MPa and the bending elastic modulus was 1400 MPa.

(Example 6-1)
The microfibrillated cellulose prepared in Example 1-1 and dispersed in water was concentrated to a concentration of 15% by mass using a centrifuge. This is referred to as concentrate 6-1. Next, using the concentrate 6-1, the microfibrillated cellulose and the resin having the same composition as the comparative example 6-1 were put into a biaxial kneader with a vent and kneaded to prepare a resin composite. This resin composite was injection-molded to produce a dumbbell piece having a width of 10 mm and a thickness of 4 mm according to JIS standard K7171, and tested using a product name: AutoCom (registered trademark) / AC-100 manufactured by TS When the bending characteristics were measured at a speed of 2 mm / min and a distance between fulcrums of 64 mm, the bending strength was 42 MPa and the bending elastic modulus was 1800 MPa. FIG. 8 is an SEM image in which a portion of the dumbbell piece is cut and the surface thereof is observed. It was confirmed that the microfibrillated cellulose was spread in the resin, and from the results of bending strength and bending elastic modulus, a resin composite having higher performance than the comparative example could be obtained.

(Example 6-2)
The microfibrillated cellulose prepared in Example 1-2 and dispersed in water was concentrated to a concentration of 15% by mass using a centrifuge, and kneaded in the same manner as in Example 6-1. The body was made. This resin composite was injection-molded to produce a dumbbell piece having a width of 10 mm and a thickness of 4 mm in accordance with JIS standard K7171, and the bending characteristics were measured. The bending strength was 40 MPa and the bending elastic modulus was 1700 MPa. A resin composite could be obtained.

(Example 6-3)
The microfibrillated cellulose prepared in Example 1-3 and dispersed in water was concentrated to a concentration of 15% by mass using a centrifuge, kneaded in the same manner as in Example 6-1, and resin composite The body was made. This resin composite was injection-molded to produce a dumbbell piece having a width of 10 mm and a thickness of 4 mm in accordance with JIS standard K7171, and the bending characteristics were measured. A resin composite could be obtained.

  The microfibrillated cellulose having developed microfibrils obtained in the present invention is used as a sheet-like material formed only with microfibrillated cellulose, or a sheet-like material formed by mixing with synthetic fibers or inorganic fibers. The Further, it can be used as an additive for imparting strength to a synthetic resin or an inorganic structural material, an additive or a filtering material in the fields of food, cosmetics and medical products.

Claims (6)

A microfibril that can be unevenly distributed on the water surface side by adsorbing a hydrophobizing agent in water, has a concentration dependency of viscosity expressed by the following formula (1), and β is 2.0 or more. Cellulose.
η = αexp (βC) (1)
(Η is viscosity, α is an extrapolated value at a concentration of 0%, β is a parameter for concentration dependency, and C is a concentration.)   A composite of the microfibrillated cellulose according to claim 1 and water glass.   A composite of microfibrillated cellulose according to claim 1 and gypsum.   A composite of the microfibrillated cellulose according to claim 1 and an organosilicate compound-derived siloxane.   A composite of the microfibrillated cellulose according to claim 1 and inorganic fibers made of basic magnesium sulfate.   A composite of the microfibrillated cellulose according to claim 1 and a resin.