WO2007088974A1

WO2007088974A1 - Method of imparting water repellency and oil resistance with use of cellulose nanofiber

Info

Publication number: WO2007088974A1
Application number: PCT/JP2007/051810
Authority: WO
Inventors: Tetsuo Kondo; Wakako Kasai
Original assignee: Kyushu University, National University Corporation
Priority date: 2006-02-02
Filing date: 2007-02-02
Publication date: 2007-08-09
Also published as: JP2014050835A; JP5690387B2; JPWO2007088974A1; JP5419120B2

Abstract

A method of reforming, including the steps of obtaining a cellulose-nanofiber-containing treating liquid by opposed collision treatment of cellulose fiber derived from herbaceous plant or bacterial cellulose, impregnating a base material with the treating liquid and/or applying the treating liquid onto the surface of the base material, and drying to thereby attain forming of a cellulose nanofiber coating on the surface of the base material. Especially suitable example of the base material is paper. Further, there is provided a cellulose-nanofiber-containing coating composition produced by opposed collision treatment of cellulose fiber derived from herbaceous plant or bacterial cellulose.

Description

Specification

Method for imparting water repellency and oil resistance using cellulose nanofibers

Technical field

The present invention relates to a method for imparting water repellency and oil resistance using cellulose nanofibers. More specifically, the present invention relates to the use of a non-terrier cellulose anti-collision treated product for coating the surface of paper or the like. The present invention is particularly useful for protecting the surface of a molded product for food storage paper.

Background art

[0002] One type of acetic acid bacterium produces a gel-like cellulose membrane outside the cell when cultured. The cellulose produced by this fungus is called bacterial cellulose. Bacterial Cellulose is secreted as highly crystalline ribbon-like cellulose nanofibers with an average width of about 50 nm and a thickness of about 10 nm. A gel called a nano-sized network pelicle forms a random network immediately after secretion. A film is formed.

[0003] As a method of using nocteria cellulose, it is considered to use a gel-like membrane as it is. Utilizing the fine mesh structure and good water retention, its use in separation membranes and medical cosmetic pads has been studied. There is also an attempt to improve the strength and the like of the material by pulverizing the gel film into a mechanical treatment and kneading it into the material.

[0004] Further, the following has been proposed as a technique for using bacterial cellulose for coating the material surface. For example, Patent Document 1 discloses a coating liquid characterized by containing bacterial cellulose and a surfactant, and a recording medium using the coating liquid. Patent Document 2 discloses a coating liquid characterized by containing a chitosan salt and a divalent or higher ionic substance in an aqueous cellulose dispersion, and a recording medium using the same. Patent Document 3 discloses an organic fiber pulp obtained by fibrillating organic fibers, characterized in that bacterial cellulose is fixed to at least a part of the surface thereof. Patent Document 4 includes a solubilized cellulose obtained from bacterial cellulose produced by stirring culture, a coating composition or composite containing a solubilized cellulose, and a solubilized cellulose. Molding composition An article or composite is disclosed.

[0005] The present inventors have so far cultivated cellulose-producing bacteria on a cellulose template that is molecularly oriented in a uniaxial direction, whereby bacterial cellulose nanofibers secreted by fungi have been aligned in the orientation direction. As a result, we succeeded in constructing a three-dimensional sheet structure in which nanofibers are oriented in one direction instead of a pellicle (Non-patent Document 1 and Patent Document 5). .

[0006] On the other hand, the present inventors have succeeded in water-soluble soot by opposing collision of microcrystalline cellulose fibers (degree of polymerization of about 200) derived from the cell wall of a persimmon (Patent Document 6).

Patent Document 1: Japanese Patent Laid-Open No. 2004-249573

Patent Document 2: JP 2005-162897 A

Patent Document 3: Japanese Patent Laid-Open No. 2005-194648

Patent Document 4: Japanese Patent Laid-Open No. 10-77302

Patent Document 5: JP 2002-142796

Patent Document 6: JP 2005-270891

Non-patent literature 1: Kondo, T., Nojiri, M., Hishikawa, Y., Togawa, E., Romanovicz, D. an d Brown, Jr., RM, Bio-directed epitaxial nanodeposition of polymers on oriented macromolecular templates, Proc. Natl. Acad. Sci. USA, 99 (22), 14008—14013 (2002) Disclosure of the Invention

[0007] When trying to use nocteria cellulose, nangu pellicle (membrane) is usually used for the nanofiber itself. However, the present inventors considered that it is necessary to take out the nocteria cellulose as nanofibers in order to expand the use of the nocteria cellulose. In addition, according to the study by the present inventors, it is clear that the crystal surface of the nocteria cellulose nanofiber has a triclinic crystal structure called cellulose I alpha (alpha), which is different from plant-derived cotton. (Unpublished). Therefore, as described above, if it can be taken out as a nanofiber, it can be expected as a fiber expressing new properties.

On the other hand, biomass resources such as cellulose and chitin are polysaccharides having a dalcoviranose skeleton. This sugar skeleton molecular structure has a parent group derived from a hydroxyl group in a direction parallel to the skeleton. Hydrophobic sites derived from CH groups exist in the direction perpendicular to the aqueous and skeleton (Fig. 1). Similarly, the cellulose natural fiber surface on which such molecules are assembled is divided into hydrophilic / hydrophobic sites having different properties. For example, if a hydrophilic surface appears on the surface of the solid, it has an affinity for water, but if the hydrophobic surface is arranged on the surface, the surface will have a water repellency similar to that of Teflon ™ (Fig. 2).

[0009] It is estimated that nano-sized natural fibers are capable of strong interaction at the interface with a partner substance having a large specific surface area. In particular, if the surface of the material is coated with natural cellulose nanofibers, this interfacial interaction with amphipathic properties (hydrophilic and hydrophobic) will be adsorbed on the surface of the material, and the resulting surface will be absorbed. The effect of fibers exhibiting the opposite properties appears. That is, it is expected that the hydrophilic surface is made more hydrophobic and the hydrophobic surface is made more hydrophilic, and the property can be changed.

[0010] The inventors of the present invention have completed the present invention, assuming that the use of nanofibers enables surface modification based on the above-described concept.

[0011] The present invention provides a method for modifying a substrate surface, which includes a step of coating cellulose nanofibers obtained by subjecting nocteria cellulose to an opposing collision treatment. In addition, the present invention provides a method for producing cellulose nanofibers including a step of subjecting bacterial cellulose to opposing collision treatment, and a treatment liquid containing cellulose nanofibers obtained by subjecting bacterial cellulose to opposing collision treatment. A cellulose nanofiber coating is provided that is formed by impregnating a material and / or applying the treatment liquid to a substrate surface and drying.

[0012] Cellulose nanofibers used for coating a substrate are not pellicles but are single nanofibers, and have an average width of 25 nm or less (preferably 20 nm or less, more preferably 15 nm or less, and even more preferably 8 to 12 nm. The average thickness is 8 to 12 nm.

In the present specification, the term “cellulose” includes vegetable cellulose, bacterial cellulose, cellulose fiber, crystalline cellulose and the like, which are not limited in origin, production method, properties, etc., unless otherwise specified.

[0014] In the present specification, "bacterial cellulose" refers to a cellulose produced by microorganisms, except for special cases, which is a polysaccharide mainly composed of cellulose 1, 4 darcoside bonds, Except where indicated, it refers to that in the form of a gel film. Nocteria cellulose can be produced by methods well known to those skilled in the art. Cellulose-producing bacteria include acetic acid bacteria such as Acetobactor pasteurianum, Acetobactor pasteurianum, and Acetobactor rancens. Sarcina ventric uli, Bacteirum xvloides, Pseudomonas spp., Agrobacterium spp., Etc. Those skilled in the art can appropriately determine the above.

In the present specification, “cellulose nanofiber” refers to a cellulose fiber having an average width and an average thickness of 100 nm or less. The average width and average thickness of the cellulose fiber can be measured by methods well known to those skilled in the art, such as a light scattering device, a laser microscope, and an electron microscope. The average width is obtained by measuring several points, for example, 10 to 200 points, preferably 30 to 80 points, of the measured length, and taking the average value. The average thickness is obtained by measuring several points, for example, 10 to 200 points, preferably 30 to 80 points, of the measured length, and taking the average value. Preferred examples of the cellulose nanofibers used in the present invention have an average width and an average thickness equal to or less than that of nocteria cellulose (for example, an average width of 25 nm or less, preferably 20 nm or less, more preferably 15 nm or less, more preferably 8-12 nm) with an average thickness of 8-12 nm.

[0016] In the present specification, "opposite collision (treatment)" refers to a case where a polysaccharide dispersion is injected from a pair of nozzles at a high pressure of 70 to 250 MPa, respectively, except for special cases. A wet pulverization method in which cellulose fibers are pulverized by colliding with each other. Details of this method are disclosed in JP-A-2005-270891 (Patent Document 1).

[0017] Opposite collision treatment is a wet atomization method that uses the collision energy of ultra-high pressure water to ultrafine the material. Compared to other pulverization methods, bead mill, jet mill, stirrer, high-pressure homogenizer, etc., it has various excellent advantages. For example, since no grinding media is used, there is no mixing of wear powder in the media, and a more uniform and sharp particle size distribution than the media agitation method is obtained. Furthermore, continuous treatment, large capacity is easy, and treatment with less contact time with the atmosphere For example, the oxidation of the product can be suppressed as much as possible. [0018] As a device for the counter collision treatment, a high-pressure washing device or a high-pressure homogenizer device for pulverization / dispersion / emulsification can be used.

[0019] During the facing collision treatment, cellulose is dispersed in water. Cellulose may be pulverized in advance if necessary. The dispersion concentration is preferably 0.1 to 10% by mass, which is preferably an appropriate concentration for passing through the pipe as a dispersion slurry.

[0020] In the counter-collision process, the dispersion liquid is ejected from a pair of nozzles at a high pressure of 70 to 250 MPa, and the jet streams collide with each other to be pulverized, but are ejected from the pair of nozzles. Adjust the angle of the high-pressure jet flow of the dispersion to adjust the number of times of pulverization by adjusting the force or the number of jets of high-pressure fluid to adjust the jet flow so that the jets collide at an appropriate angle at one point ahead of each nozzle outlet. By adjusting, the average particle length of the cellulose fibers can be pulverized to 1Z4 or less or 10 μm, while the decrease in the degree of polymerization of cellulose can also be suppressed.

[0021] The collision angle Θ can be 95 to 178 °, for example, 100 to 170 °. If it is smaller than 95 °, for example, if it is made to collide at 90 °, structurally, the collision dispersion liquid tends to generate a portion that directly collides with the wall of the chamber, and cellulose polymerization occurs in one collision. Degradation often exceeds 10%. On the other hand, when the angle is larger than 178 °, for example, when the collision is 180 °, that is, when the collision is made in the face-to-face relationship, the degree of polymerization in one collision may be severely reduced when the collision energy is large.

[0022] The number of collisions may be 1 to 200 times, for example, 5 to 120 times, -60 times, -30 times, -15 times, -10 times. If the number of pulverization is large, the decrease in the degree of polymerization of cellulose may exceed 10%.

[0023] The collision angle and Z or the number of collisions can be appropriately designed in consideration of decomposition efficiency by cellulose and the like. By adjusting the collision angle and Z or the number of collisions, the average particle length of cellulose after the collision treatment can be 1Z4 or less, 1Z5 to 1Z100, 1Z6 to 1Z50, 1 Z7 to lZ20 before treatment. Similarly, the average particle length can be 10 m or less, 0.01-9 / ζ πι, 0.1-8 ^ πι, 0.1-5 ^ πι. Cellulose fibers have a particle width perpendicular to the average particle length. This width is called the average particle width, which is also less than 10 m, 0.01 to 9 / ζ πι, and 0.1 to 8 / ζ πι by adjusting the collision angle and Ζ or the number of collisions. can do.

[0024] Since the temperature of the processed object rises as the counter-collision process repeats the number of times !, the processed object once subjected to the collision process is, for example, 4 to 20 ° C, or 5 as necessary. It may be cooled to ~ 15 ° C. Equipment for cooling can be incorporated in the opposing collision processing apparatus.

[0025] In the present invention, the average particle size is obtained by centrifuging the processed product and fractionating the supernatant as a method for taking out only the portion where the processed product has particularly strong cellulose fiber strength. Cellulose fine particles with a length of less than 1 μm can be obtained.

[0026] Further, according to the study of the present inventors, not only cellulose cellulose, but also cellulose nanofibers obtained by opposing collision treatment of pulp obtained from straw and bamboo were used. As in the case of using cellulose, the effect of modifying the substrate surface was obtained. Therefore, the present invention also includes a method for modifying a substrate surface comprising a step of coating a cellulose nanofiber obtained by subjecting a herbaceous plant-derived cellulose fiber to opposing collision; a cellulose fiber derived from a herbaceous plant; A method for producing cellulose nanofibers, including a step of carrying out a counter-collision treatment, and a counter-collision treatment of the cellulose fibers derived from herbaceous plants to obtain a treatment liquid containing the cellulose nano-fibers, impregnating the substrate with the treatment liquid And / or providing a cellulose nanofiber coating formed by applying the treatment liquid to the surface of a substrate and drying.

[0027] Herbaceous plants refer to plants that have grassy or fleshy stems that do not develop much xylem, and the above-ground parts often die within a year. There are two kinds of perennials, perennials, and evergreen leaves that have been developed with strong strength. In the herbaceous plant field, gramineous plants can be suitably used, and examples of preferred gramineous plants are bamboo and bamboo. Rag (Phragmites communis) (sometimes called oak, 葭, 蘆, 葭, reed) is a herbaceous plant belonging to the genus Gramineae reed and distributed in wetlands over temperate zones. Forces that can be divided into three to four species are generally considered the only species belonging to the genus Reed. Bamboo is a perennial herbaceous plant that belongs to the Gramineae bamboo subfamily and is distributed from the tropics to the temperate zone. Bamboo includes Horaiichita, Madatake, Mosouchita, Chishimazasa, Suzutake, and Medake.

[0028] In the present invention, the herbaceous plant-derived cellulose fiber subjected to the counter-collision treatment is obtained by using a norp (a collection of cellulose fibers taken apart) as a raw material for paper. What was obtained by the process similar to preparing may be used. In the pulp preparation process, for example, the raw material is mixed with chemicals and processed at high temperature and heat to separate the fiber and other components (such as lignin components), and the fiber is separated as necessary. Including washing.

Brief Description of Drawings

[FIG. 1] FIG. 1 is a view showing hydrophilic sites and hydrophobic sites of cellulose molecules. In molecules such as cellulose and chitin, there are hydrophilic sites derived from hydroxyl groups in the direction parallel to the skeleton, and hydrophobic sites derived from C—H groups in the direction perpendicular to the skeleton.

[FIG. 2] FIG. 2 is a diagram showing the influence of the orientation angle of the glucose ring on the surface on the surface characteristics. If hydrophilic surface appears on the surface of solid, it has affinity to water. If hydrophobic surface is arranged on the surface, the surface will have the same water repellency as Teflon ™.

[FIG. 3] FIG. 3 includes photographs showing changes in bacterial cellulose nanofibers before and after the oncoming collision treatment. It was found that the network structure of the nanofibers in the pellicle was destroyed by the facing collision treatment and dispersed in water as a single fiber instead of the pellicle. The TEM photographic power was also found to be a fiber with a cross-sectional shape close to a square, with the width of the nanofibers reduced to about 10 and 1/4.

[FIG. 4] FIG. 4 is a photograph of water repellency (water contact angle) measured on the surface of a filter paper coated with bacterial cellulose subjected to counter collision. In the case of untreated filter paper, it was possible to obtain a contact angle of 51 ° by the coating process because of the strong suction of water into the filter paper and the inability to measure the contact angle.

[FIG. 5] FIG. 5 is a photograph of the surface of a filter paper coated with bacterial cellulose subjected to counter collision treatment when tested for oil resistance. When the salad oil mixed with red and dye (Zudan IV) was dropped, and the surface at that time was observed, the untreated filter paper quickly penetrated and oozed out on the backside. Although it spread on the surface of the filter paper, it did not penetrate and the oil oozed out on the back side.

[Fig. 6] Fig. 6 is a photograph when the oil resistance of a filter paper surface coated with a microcrystalline cellulose fiber derived from a plant subjected to opposing collision treatment was tested. From the left, the number of applications is 1, 3, and 5. Salad oil permeated immediately, and those with a coating frequency of more than 3 times were filmed and peeled off the filter paper. [FIG. 7] FIG. 7 is a photograph of the oil resistance of the filter paper surface coated with bacterial cellulose defibrated with a homogenizer. From left to right, the number of applications is 1, 3, and 5. Salad oil penetrated immediately.

[FIG. 8] FIG. 8 is a photograph of the bacterial cellulose treated with facing collisions when spread on a PET film. Bacterial cellulose adhered well to the PET film.

[Fig. 9] Fig. 9 is a photograph of the microcrystalline cellulose fiber that has been subjected to opposing collision treatment, developed on a PET film. The development was peeled off the film.

[Fig. 10] Fig. 10 is a photograph of the surface of the filter paper coated with bacterial cellulose subjected to the counter-impact treatment, when the water resistance was tested. When a 1% solution of blue stain (Coomassie brilliant blue R-250) was added dropwise and the surface at that time was observed, the untreated filter paper quickly penetrated and exuded to the back side. Although the solution spread on the surface of the filter paper, it did not permeate and did not penetrate into the back side.

[FIG. 11] FIG. 11 is a photograph of the water repellency (water contact angle) of PE, PP, and PET coated with bacterial cellulose subjected to opposing collision treatment. The coating treatment made the contact angle smaller and made it hydrophilic.

[FIG. 12] FIG. 12 is a photograph of water and oil resistance tests on the filter paper surface coated with the cellulose nanofibers that were subjected to opposing collision treatment. When a 1% aqueous solution of blue stain (Coomassie brilliant blue R-250) was dropped, the solution spread on the surface of the filter paper but did not permeate, and water did not ooze out on the back side. (Left photo). In addition, when salad oil mixed with a red dye (Zudan IV) was dropped, the salad oil spread on the filter paper surface but did not penetrate, and the oil did not ooze out on the back side (right photo).

[FIG. 13] FIG. 13 is a photograph of the surface of the filter paper coated with the bamboo-derived cellulose nanofibers subjected to the counter collision treatment when tested for water resistance and oil resistance. When a 1% aqueous solution of blue stain (Coomassie brilliant blue R-250) was added dropwise, a slight oozing of water into the filter paper was observed, but the rate of soaking was slow (left photo). Moreover, when salad oil mixed with red dye (Zudan IV) was dropped, no soaking into the filter paper was observed (right photo). [FIG. 14] FIG. 14 is a photograph of the coating composition when tested for water resistance and oil resistance. The oil resistance and water repellency were maintained as in Example 1.

BEST MODE FOR CARRYING OUT THE INVENTION

[0030] [Coating method]

In the present invention, when the substrate surface is coated with a cellulose nanofiber coating (“coating” t), the method is not particularly limited, but the liquid is usually impregnated with the substrate ( Dipping) or applying the liquid to the substrate surface and drying. The impregnation and application may be performed in combination or repeatedly. There are no particular restrictions on the application means, and air spray, brush, roller, etc. can be used. Drying can be performed by heat drying, forced drying, and Z or room temperature drying.

[0031] [Example of substrate and application of the present invention to paper and paper products]

According to the present invention, it is possible to coat an organic base material surface such as plastic, wood and paper; an inorganic base material surface such as concrete, stone, glass and ceramic; and a metal surface such as iron and aluminum. Preferred examples of substrates to be coated and modified according to the present invention are paper, polyethylene terephthalate, polyethylene, polypropylene. An example of a particularly suitable substrate is paper.

[0032] In the present specification, "paper" refers to a product made by intertwining and attaching plant fibers and other fibers, except in special cases. The form can be any, such as a paperboard, a molded product, and the like, with no particular limitations on the raw material, the type of fiber constituting, and the proportion of blending. Norp mold is also included. Further, it may contain a fungicidal component other than fibers, an antibacterial component and the like.

[0033] On the paper surface, the cellulose nanofibers are 0.01 to 30 g / m ² (preferably 0.05 to ²⁰ g / m ² , more preferably 0.1 to 10 g / m ² , more preferably 0.2 to 5 g / m ^2. ) To cover the substrate surface. As the coating method, various methods used for coating the substrate, such as application by dipping or spraying, can be applied.

[0034] When the coating of the present invention is applied to a substrate having a hydrophobic surface (water repellency) such as PET, the surface of the substrate is modified to be hydrophilic. If it is hydrophilic, it can be printed on the coated substrate with aqueous ink or pencil.

[0035] In the present invention, a part or the whole of the surface is coated with a cellulose nanofiber coating. A paper product or a molded article made of paper; the cellulose nanofiber coating impinges bacterial cellulose on the opposite surface to obtain a treatment liquid containing cellulose nanofibers, and the treatment liquid is impregnated with a substrate. And the paper product or the molded article made of paper, which is formed by applying Z or the treatment liquid to the surface of the substrate and drying.

[0036] Examples of paper products or molded articles include food containers (for example, bento containers), tableware (paper cups, m.), Bags, cards, books, magazines, printing paper, stationery Printing paper, adhesive paper, filter, etc.

[0037] The present invention is also a method for imparting water repellency or hydrophilicity, or oil and fat resistance to the surface of a substrate such as paper products or paper moldings; water resistance or hydrophilicity, and oil and fat resistance. Is imparted by coating part or all of the surface of a substrate such as a paper product or a paper molded product with a cellulose nanofiber coating; the cellulose nanofiber coating is formed of bacterial cellulose or gramineous Plant-derived cellulose fibers are subjected to opposing collision treatment to obtain a treatment liquid containing cellulose nanofibers, the treatment liquid is impregnated with a substrate, and Z or the treatment liquid is applied to the substrate surface and dried. The above method is provided.

[0038] By the treatment of the present invention, various resistances, particularly resistance to penetration of liquids and gases, can be imparted to the paper. Resistance to liquids includes water repellency, oil and fat resistance (oil resistance and oil resistance), and water resistance. Each evaluation method is well known to those skilled in the art. These evaluations are usually performed not only immediately after the landing of water droplets or oil droplets on the surface, but also after the landing for several hours depending on the intended use. Good. According to the study of the present inventors, even the most wet and porous filter paper can be easily imparted with oil resistance by spraying, and this oil resistance does not change even after several hours after landing. won.

[0039] As a result of the evaluation, when an effect suitable for the intended use is not recognized, it can be improved by modifying the coating method. For example, if sufficient water repellency cannot be obtained by wiping one to several times by spraying, it can be improved by immersion in a coating solution or repeated spraying.

[0040] [Coating composition] The present invention also provides a coating composition comprising cellulose nanofibers obtained by opposing collision treatment of cellulose fibers derived from nocteria cellulose or herbaceous plants. The coating composition of the present invention can be used as a paint or as an ink.

[0041] The coating composition of the present invention may contain water, a pigment, and various additives as a developing agent in addition to cellulose nanofibers as a film-binding component. Examples of pigments include inorganic pigments, lakes, colored pigments, extender pigments, and glitter pigments. Examples of additives include dispersants, emulsifiers, suspending agents, color separation inhibitors, drying agents, Anti-sagging agents, leveling agents, plasticizers, anti-fogging agents, antifoaming agents, fireproofing agents, antiseptics, antifungal agents, disinfectants, and agents for imparting slipperiness to the coating film can be mentioned.

[0042] The coating composition of the present invention can be applied to the surface of various base materials and the surface of an old coating film. Examples of the base material surface include organic base material surfaces such as plastic, wood, and paper; concrete, stone, glass, Surfaces of inorganic base materials such as ceramics; metal surfaces such as iron and aluminum can be listed. Old coatings include acrylic resin, acrylic urethane resin, polyurethane resin, fluorine resin, silicon acrylic Examples include old coatings such as rosin, vinyl acetate, epoxy, and alkyd resins. The coating composition of the present invention can also be used in combination with an undercoat material and an overcoat material. The coating method of the coating composition of the present invention is not particularly limited, and can be performed by immersion, air spray, brush, roller or the like.

[0043] Most of the conventional coating compositions, even if used as water-based coatings, require a VOC (volatile organic compound) component that is one of the causes of sick house syndrome. The coating composition can be configured to be free of VOCs. Such a coating composition of the present invention is mainly used for interior materials that require a texture (does not generate VOCs) or materials that are used in contact (for example, welfare materials for the elderly, used in hospitals). Particularly suitable for metal substitute materials). Specific examples include architectural interior materials, automotive interior materials, food packaging, and plastic trays.

[0044] The coating composition of the present invention has a coating film formed on the substrate due to the strong adsorptivity of the nanocellulose fibers to the substrate surface and the anchor effect on the material surface of the pigment component used together. It is thought that the surface can be strongly coated. Therefore, the coating composition of the present invention can be configured such that the coating film exhibits sufficient durability. [0045] With the coating composition of the present invention, painting or dyeing and oil resistance and water repellency treatment can be simultaneously performed.

[Surface structure and properties of cellulose nanofibers]

According to the present invention, cellulose nanofibers and cellulose nanofiber coatings are provided. Cellulose cellulose has recently been reported to exhibit biocompatibility not found in cotton wool. This is because the difference in the structure of the surface reflects the difference in the effect on the cells at the contact surface. It seems to show that. As described above, the surface of the nocteria cellulose takes a crystal form called I al pha (alpha) in which the aggregate state is triclinic even if it is composed of the same cellulose molecules. On the other hand, the molecular morphology of the plant-derived surface takes the form of a monoclinic crystal called I beta, so the surface properties of nanofibers differ. The conventional plant cellulose fiber and the bacterial cellulose nanofiber according to the present invention have a difference in the arrangement of the constituent molecules, and as a result, the aggregation state of the molecules on the fiber surface is different, and therefore the properties exhibited by the fiber surface are different. Conceivable. According to the study by the present inventors, the same effect as in the case of using the opposite treatment product of nocteria cellulose was not obtained with the opposite treatment product of the crystalline cellulose fiber derived from the woody plant (see Comparative Example). In addition, the same effect as that obtained when the opposite treatment product of bacterial cellulose was used was not obtained by the treatment with the high-pressure homogenizer of nocteria cellulose. The treatment with a high-pressure homogenizer may be useful from the viewpoint of water-solubilization of cellulose, but naturally it involves physical molecular cleavage, so that cellulose is reduced in molecular weight and the degree of polymerization is reduced. However, oncoming collisions act to tear off the molecules and the degree of polymerization does not decrease much. And the aggregation state of the molecules on the fiber surface is expected to differ depending on the treatment method. Therefore, nano-sized considerations produce fibers with different surface properties depending on the treatment method, even if the starting material is the same. Opposing collision treatment technology is important in that it is a non-destructive operation of molecular structure without lowering the degree of polymerization.

[0047] In this sense, the present application provides the property that only bacterial cellulose that has been subjected to facing collision treatment can be expressed at the present time. The present invention makes use of the surface properties of nanofibers. At present, the surface structure and size of a bacterial cell mouth that has been subjected to an appropriate number of counter-collision treatments are the same as the parents of cellulose molecules and their aggregates. It ’s medium! The potential characteristics will be expressed more clearly! /!

[0048] The present invention also provides a property resulting from the molecular aggregation state (crystallinity and packing state) of the fiber surface of the cellulose fiber derived from the herbaceous plant subjected to the counter collision treatment. It is the same in terms of plant origin, and it is the same crystalline structure of cell mouth fiber derived from bamboo and bamboo, and cellulose fiber of wood (wood). It is thought that the properties exhibited by the fiber surface are different. Therefore, the surface activity effect of nanofibers due to underwater collision will also be different. Cellulose fibers derived from herbs that are softer and less crystalline than wood and cotton fibers have a lot of fluffing of nanofibers on the surface when facing each other, resulting in an extremely large specific surface area. It is thought that it becomes easy to adsorb to the material. As a result, in the surface modification of the base material, the same excellent effect as that of the bacterial cellulose nanofiber is exhibited.

Example

[Example 1]

Acetobactor xylinum (3 ~ Gluconacetobactor xvnnus) (producing strain: ATCC 53582) was cultured (the preparation method of the medium for bacterial cellulose culture is Hestrin, S. & Schramm, M. ( 1954) According to Biochem. T. 58, 345—352.) The obtained cellulose pellicle was cut into lcm square size as it was, suspended in water, Manufactured), pressure 200mPa, number of collisions

A suspension of cellulose nanofibers was obtained by applying the suspension 34 times to a solid concentration of about 0.4%.

[0050] <Coating of filter paper surface with suspension>

The filter paper surface was coated with nanofibers by using filter paper as a base material, dipping in a suspension of cellulose nanofibers and drying at 105 ° C. The coating amount is 2-3g / m 7 hot.

[0051] How the surface condition of the filter paper coated with the nanofibers changed was determined by the surface structure. The evaluation was attempted by paying attention to the correlation between the structure and the improvement of hydrophobicity or oil resistance. First, using the contact angle method, the contact angle of water was measured to examine the hydrophobicity of the surface. As a method, 1 μ 1 of ultrapure water was dropped and the measurement was made 1 second after landing on the filter paper. In addition, oil resistance is obtained by mixing red oil (Zudan IV) with salad oil (manufacturer J-Oil Mills, product name AJINOMOTO Salad Oil 1500g Eco Bottle, raw material name edible soybean oil, edible rapeseed oil) and dripping into filter paper. investigated.

[0052] Results:

Bacterial Cellulose Nanofiber Suspension>

In order to investigate the effect of the opposing collision treatment, especially the influence on the fiber width size, the morphology of the cellulose nanofibers in the suspension was observed with a transmission electron microscope (TEM). Figure 3 shows a TEM photograph. It was found that the nanofiber network structure in the pellicle was destroyed and dispersed in water as a single fiber rather than a pellicle. Furthermore, bacterial cellulose nanofibers usually have a width of 40-60 nm and a thickness of 10 nm. After the impact treatment, the nanofiber width is reduced to about 10 ηm, about 1/4, and the cross-section is nearly square. It became clear that TEM photography power became.

[0053] From this, the fiber adsorption on the filter paper surface by purely the interaction between the nanofiber surface and the filter paper surface forms a pellicle, which is significantly better than the case of bacterial nanofibers. it was thought. That is, since the filter paper is hydrophilic, the hydrophilic side of the nanofibers is adsorbed on the surface, and the hydrophobic side is directed to the air side, so that the surface is considered to be hydrophobic.

0 Influence with water (water repellency):

The contact angle of the surface of the filter paper immersed in the suspension was measured (Fig. 4). In the case of untreated filter paper, the suction of water into the filter paper was so strong that the contact angle could not be measured. However, with the filter paper that has been soaked, the suction of water was significantly slowed, the contact angle could be measured, and a numerical value of 51 ° could be obtained with a single soaking treatment, giving hydrophobicity. it was thought.

[0055] The contact angle of water is 20 ° for glass and 45 for stainless steel. And 70 for aluminum. (Refer to DuPont HP HYPERLINK "http://www.dupont.co.jp/tc/seinou/" http://www.duDont.co.iD/tc/seinou/). Compared with these values, the 51 ° value of the filter paper that had been soaked was considered to have the same water repellency as stainless steel.

[0056] ii) Effect with oil (oil resistance):

Oil (salad oil) was dropped onto the filter paper surface, and the surface at that time was observed (Fig. 5). Ordinary filter paper penetrated quickly and oozed out to the back, although not as much as water. However, for the filter paper that had been soaked, the salad oil spread on the surface of the filter paper but did not penetrate, and the oil did not ooze out on the back side. This showed oil resistance.

[Comparative Example 1]

Plant-derived cellulose microcrystalline fibers (Funacel II: average particle size 80 micrometers: Funakoshi Co., Ltd.) are subjected to opposing collision treatment (30 collisions, suspension solid concentration about 0.5%), The suspension obtained by subjecting to the same conditions as in Example 1 was applied to the filter paper by spraying, dried at 105 ° C., and the oil resistance of the filter paper was tested (FIG. 6).

[0058] The salad oil immediately penetrated the filter paper. In addition, when the number of times of coating was more than 3,000 times, the coated material turned into a film and peeled off the filter paper. This was thought to be due to the fact that the interaction of the cellulose used with the filter paper was weaker than that of bacterial cellulose.

[0059] Furthermore, the suspension obtained by treating bacterial cellulose with a homogenizer (product name: Hiscotron, manufactured by Microtec •-Thion) at 20,000 rpm for 5 minutes was applied by spraying, and the other conditions were as in Examples. The oil resistance of the filter paper was tested in the same way as in Fig. 1 (Fig. 7).

[0060] The salad oil immediately penetrated the filter paper. In addition, it was difficult and evenly applied to the surface of the filter paper as compared with the case of opposing collision treatment.

[Example 2]

The bacterial cellulose suspension obtained in Example 1 was developed on a PET film (FIG. 8). The bacterial cellulose subjected to the counter collision treatment was in good contact with the PET film. Other than paper, PET, PP, PE, and other substrates could be coated with bacterial cellulose.

[Comparative Example 2]

The suspension of plant-derived microcrystalline fibers obtained in Comparative Example 2 was developed on a PET film (FIG. 9). The developed material peeled off the film. [Example 3]

Filter paper obtained by spraying the bacterial cellulose suspension that had been subjected to the counter-treatment 34 times in the same manner as in Example 1 and air-drying it 15 times, and finally drying at 40 ° C for about 1 hour. The water resistance of was evaluated.

[0064] A solution of Coomassie (registered trademark) brilliant blue R-250 dissolved in 1% water was dropped onto a filter paper, and the surface was observed (FIG. 10).

[Example 4] Contact angle measurement of a synthetic polymer film coated with nanocellulose

Sample preparation:

1. First, nanocellulose was sprayed onto a synthetic polymer (PE, PP, PET) film, then air-dried, and then dried at 40 degrees for 30 minutes to 1 hour.

[0066] 2. Next, nanocellulose was dropped onto the film and applied to the entire film surface using a wire bar (a product in which a stainless steel wire was precisely wound around a precision shaft). It was air dried and then dried at 40 degrees for 30 minutes to 1 hour.

[0067] 3. The operation in 2 was repeated 2 to 5 times for contact angle measurement.

[0068] The contact angle measurement conditions were the same as in Example 1.

[0069] ¾:

The results are shown below and in FIG.

[0070] [Table 1]

(Average value when measured four times) Contact angle (degree) The coating made the contact angle lower and the surface more hydrophilic. This property did not change even after several hours after landing.

[Example 5] Coating of cellulose nanofiber derived from oak

It was confirmed that water resistance and oil resistance were imparted to the filter paper when cellulose nanofibers derived from oil were used for coating.

1. Pear pulp was loosened by stirring in water to prepare a suspension of pear.

2. This was subjected to an oncoming collision. The conditions were the same as in Example 1, using an optimizer (manufactured by Suginomashin), pressure 200 raPa, number of collisions 34 times, and solid concentration of suspension about 0.4 ° /. It was.

3. The treatment liquid of the oil subjected to the counter collision treatment was coated on the filter paper in the same manner as in Example 1.

4. Water resistance test and oil resistance test were performed on the coated filter paper.

[0072] The results are shown in FIG.

[Example 6] Coating of bamboo-derived cellulose nanofibers

Bamboo force Using the obtained pulp, the filter paper was coated in the same manner as in Example 4, and water resistance and oil resistance tests were conducted.

[0074] The results are shown in FIG.

Replacement paper (Rule 26) [Example 7] Coating composition

A blue dyeing agent (Coomassie brilliant blue R-250) was added to the cellulose nanofiber suspension with 34 collisions obtained in Example 1 to a concentration of 0.1% to obtain a coating composition. this

Then, it was applied to the surface of the filter paper by spraying and subjected to oil resistance and water repellency tests.

The results are shown in FIG. The oil resistance and water repellency were maintained as in Example 1. From this, it was considered that by using the cellulose nanofiber suspension, coating or dyeing and oil-resistant / water-repellent treatment can be performed simultaneously.

Claims

The scope of the claims

[1] Nocteria cellulose or herbaceous plant-derived cellulose fibers are subjected to opposing collision treatment to obtain a treatment liquid containing cellulose nanofibers, the treatment liquid is impregnated with a base material, and Z or the treatment liquid is used as a base material. A method for modifying a substrate surface, comprising a step of coating the surface of a substrate with a cellulose nanofiber coating formed by applying to the surface and drying.

[2] Average width of 25 nm or less (preferably 20 nm or less, more preferably 15 nm or less, more preferably

A method for modifying the surface of a substrate, comprising a step of coating with cellulose nanofibers having an average thickness of 8 to 12 nm.

[3] The modification method according to claim 1 or 2, wherein the substrate is paper, polyethylene terephthalate, polyethylene, or polypropylene.

[4] 0.01-30 g / m ^{2 of} cellulose nanofibers (preferably 0.05-20 g / m ² , more preferably 0.1

The modification method according to claim 3, wherein the substrate surface is coated at -10 g / m ² , more preferably 0.2-5 g / m ² ).

[5] It imparts water repellency or hydrophilicity, water resistance and Z or oil resistance to the substrate.

The reforming method according to claim 4.

[6] The method according to claim 6, for protecting the surface of a molded product made of food storage paper.

[7] A paper product or a paper molding, part or all of which is coated with a cellulose nanofiber coating;

The cellulose nanofiber coating force and bacterial cellulose are subjected to opposing collision treatment to obtain a treatment liquid containing cellulose nanofibers, the treatment liquid is impregnated with a substrate, and / or the treatment liquid is applied to the substrate surface, And the said paper product or paper-made molding formed by drying.

[8] A method of imparting water resistance and oil resistance to paper products or paper moldings;

The provision of water resistance and oil resistance is by covering part or all of the surface of the paper product or paper molding with a cellulose nanofiber coating;

Cellulose nanofiber coating strength Cellulose fibers derived from bacterial cellulose or herbaceous plants are subjected to opposing collision treatment to obtain a treatment liquid containing cellulose nanofibers, the treatment liquid is impregnated with a base material, and Z or the treatment liquid is used. Form by applying to substrate surface and drying The method as defined above.

[9] A method for producing cellulose nanofibers, comprising a step of subjecting cellulose fibers derived from nocteria cellulose or herbaceous plants to opposing collision treatment.

[10] Cellulose fibers derived from bacterial cellulose or herbaceous plants are subjected to opposing collision treatment to obtain a treatment liquid containing cellulose nanofibers, the treatment liquid is impregnated with a substrate, and Z or the treatment liquid is applied to the substrate surface. A cellulose nanofiber coating formed by applying to and drying.

[11] A coating composition comprising cellulose nanofibers obtained by opposing collision treatment of cellulose fibers derived from nocteria cellulose or herbaceous plants.