JP2020143405A - Manufacturing methods of dispersion, structure and crosslinked structure involving fine cellulose fiber - Google Patents

Abstract

To provide manufacturing methods of a dispersion and a structure giving an organic fiber product (sheet, molding, etc.) having good moldability (especially, shape followability to a molding die), mechanical strength, water resistance and solvent resistance, and a crosslinked structure formed from the structure and usable as products of various kinds.SOLUTION: Provided herein are: a manufacturing method of a dispersion involving a fine cellulose fiber having an average fiber diameter of 2 nm or over and 1000 nm or under, an organic fiber having an average fiber diameter of more than 3000 nm, a blocked polyisocyanate, and water; a manufacturing method of a structure involving a fine cellulose fiber having an average fiber diameter of 2 nm or over and 1000 nm or under, an organic fiber having an average fiber diameter of more than 3000 nm, and a blocked polyisocyanate; and a manufacturing method of a crosslinked structure obtained by crosslinking the structure.SELECTED DRAWING: None

Description

The present invention relates to a method for producing a dispersion, a structure and a crosslinked structure containing fine cellulose fibers and organic fibers.

In recent years, from the viewpoint of environmental protection, it has been proposed to manufacture various articles (for example, sheets, molded products, etc.) using materials having a small environmental load at the time of manufacture, use, and / or disposal. For example, a molded product made of a material mainly composed of organic fibers has advantages such as light weight and low disposal cost. In particular, if the organic fiber is a biodegradable material such as a cellulosic fiber, the molded product itself becomes a material that meets modern needs from the viewpoint of sustainability. For example, Patent Document 1 is a resin-impregnated paper in which the outer container is a composite container in which the outer container is mainly made of paper and the inner container is mainly made of plastic and the lid material is sealed, and the outer container is impregnated with an interlayer strength enhancer of paper. A composite container characterized by being composed of is described, and an isocyanate-based resin is referred to as an interlayer strength enhancer.

Various paper strength enhancers have been conventionally proposed as methods for increasing the mechanical strength of paper (that is, a sheet-like material containing cellulose fibers as main components), and Patent Document 2 describes (a) a hydrophilic group. It also contains a water-soluble heat-reactive urethane prepolymer having an isocyanate group blocked by a blocking agent that dissociates by heat treatment, and (b) a cationic compound that enhances the cationic property of the urethane prepolymer in an aqueous solution. A wet paper strength enhancer characterized by the above is described. Further, in recent years, fine cellulose fibers obtained by beating and crushing cellulosic fibers at a high level to make them finer (fibrillated) to a fiber diameter of 1 μm or less have attracted attention, and as fine cellulose fiber sheets having excellent various physical properties such as water resistance. Patent Document 3 is composed of fine cellulose fibers having an average fiber diameter of 2 nm or more and 1000 nm or less, the weight ratio of the fine cellulose fibers is 50% by weight or more and 99% by weight, and the aggregate of block polyisocyanate has the weight of the fine cellulose fibers. A fine cellulose fiber sheet containing 1 to 100% by weight as a weight ratio is described.

Japanese Unexamined Patent Publication No. 2014-168340 Japanese Unexamined Patent Publication No. 2003-138497 International Publication No. 2015/008868

In order to obtain articles (sheets, molded articles, etc.) useful for a wide range of applications by using a molding material mainly composed of organic fibers alone (that is, without requiring a combination with other members (lamination, etc.)). It is desirable that the molding material has various properties (for example, moldability (particularly shape followability to a molding mold), mechanical strength, water resistance and solvent resistance) required for an article. Is done. The container described in Patent Document 1 includes an outer container mainly made of paper, but has a complicated structure of a combination of an outer container and an inner container, and there is room for improvement in terms of cost and convenience. There is. Further, Patent Document 2 provides a paper strength enhancer in which the adsorption rate of the urethane prepolymer to the cellulose fiber is improved by increasing the cationic property of the water-soluble urethane prepolymer by the combined use of the cationic compound, and Patent Document 3 provides. , By using the block polyisocyanate, fine cellulose fiber sheets having various excellent physical properties are provided, and the techniques described in these documents have good moldability (particularly shape followability to a molding mold). It does not provide a molding material that provides an article having mechanical strength, water resistance and solvent resistance.

The present invention solves the above-mentioned problems and provides an organic fiber-based article (sheet, molded product, etc.) having good moldability (particularly shape followability to a molding mold), mechanical strength, water resistance, and solvent resistance. It is an object of the present invention to provide a dispersion and a structure, and a method for producing a crosslinked structure formed from the structure and used as various forms of articles.

As a result of diligent studies to solve the above problems, the present inventors can solve the above problems with a dispersion containing fine cellulose fibers having a specific average fiber diameter, organic fibers having a specific average fiber diameter, and blocked polyisocyanate. We found that and completed the present invention.
The present invention includes the following aspects.

[1] A method for producing a dispersion containing fine cellulose fibers, organic fibers, and blocked isocyanate.
A method comprising mixing fine cellulose fibers having an average fiber diameter of 2 nm or more and 1000 nm or less, organic fibers having an average fiber diameter of more than 3000 nm, block polyisocyanate, and water.
[2] The method according to the above aspect 1, wherein the dispersion contains the blocked polyisocyanate in an amount of 0.1 part by mass to 120 parts by mass with respect to 100 parts by mass of the fine cellulose fiber.
[3] The method according to the above aspect 1 or 2, wherein the blocked polyisocyanate is a cationic blocked polyisocyanate.
[4] The mass ratio of the fine cellulose fibers to the organic fibers (fine cellulose fibers / organic fibers) in the dispersion is 0.2 / 99.8 to 30/70.
The method according to any one of the above aspects 1 to 3, wherein the solid content ratio of the dispersion is 0.1% by mass to 55% by mass.
[5] The method according to any one of the above aspects 1 to 4, wherein the organic fiber contains a fiber having at least a hydroxyl group and / or an amide group on the surface.
[6] The method according to any one of the above aspects 1 to 5, wherein the organic fiber contains a cellulose fiber.
[7] Any of the above aspects 1 to 6, wherein the mixing is carried out by mixing fine cellulose fibers, blocked polyisocyanate and water to prepare a premix, and then mixing the premix with organic fibers. The method described in.
[8] Any of the above aspects 1 to 7, wherein the mixing is carried out by mixing fine cellulose fibers, organic fibers and water to prepare a premix, and then mixing the premix with blocked polyisocyanate. The method described in.
[9] The method according to any one of the above aspects 1 to 8, wherein the mixing is carried out at a temperature of 5 ° C to 60 ° C.
[10] A dispersion preparation step of preparing a dispersion by the method according to any one of the above aspects 1 to 9.
A structure comprising a concentration step of dehydrating the dispersion to form a hydrous concentrate, and a structure forming step of drying the hydrous concentrate at 80 ° C. or higher and 120 ° C. or lower to form a structure. Production method.
[11] A structure in which a dispersion is prepared by the method according to any one of the above aspects 1 to 9, and the dispersion is dried at 80 ° C. or higher and 120 ° C. or lower to form a structure. A method of manufacturing a structure, including a forming step.
[12] The method according to the above aspect 10 or 11, wherein the structure is a sheet or a molded product.
[13] The method according to any one of aspects 10 to 12, wherein the blocked polyisocyanate is uniformly distributed in the structure.
[14] A dispersion preparation step of preparing a dispersion by the method according to any one of the above aspects 1 to 9.
A concentration step in which the dispersion is dehydrated to form a hydrous concentrate, and the hydrous concentrate is dried at 80 ° C. or higher and 120 ° C. or lower, and the block in the block polyisocyanate is blocked following or at the same time as the drying. A crosslinked structure comprising a crosslinked structure forming step of crosslinking the blocked polyisocyanate with the fine cellulose fibers and / or the organic fibers by heating above the desorption temperature of the group to form a crosslinked structure. Production method.
[15] A dispersion preparation step of preparing a dispersion by the method according to any one of the above aspects 1 to 9, and drying the dispersion at 80 ° C. or higher and 120 ° C. or lower, following the drying or the drying. At the same time, the crosslinked structure is formed by cross-linking the blocked polyisocyanate with the fine cellulose fibers and / or the organic fibers by heating at a temperature higher than the desorption temperature of the blocking group in the blocked polyisocyanate. A method for producing a crosslinked structure, which comprises a forming step.
[16] The method according to aspect 14 or 15, wherein the crosslinked structure has a wet / dry strength ratio of 0.4 to 1.2.
[17] The method according to any one of the above aspects 14 to 16, wherein the heating is performed at a temperature of 130 ° C to 220 ° C.

According to the present invention, dispersions and structures, and structures that provide organic fiber-based articles with good moldability (particularly shape followability to molding molds), mechanical strength, water resistance and solvent resistance. Provided are methods of making a crosslinked structure formed from and usable as articles of various forms.

Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these aspects.

One aspect of the present invention is a fine cellulose fiber having an average fiber diameter of 2 nm or more and 1000 nm or less (hereinafter, also simply referred to as a fine cellulose fiber) and an organic fiber having an average fiber diameter of more than 3000 nm (hereinafter, also simply referred to as an organic fiber). ), A method for producing a dispersion containing blocked polyisocyanate and water, fine cellulose fibers having an average fiber diameter of 2 nm or more and 1000 nm or less, organic fibers having an average fiber diameter of more than 3000 nm, and blocked polyisocyanate. Provided is a method for manufacturing a structure containing the mixture. In one aspect, the structure may be formed with the dispersion. Further, one aspect of the present invention provides a method for producing a crosslinked structure obtained by crosslinking the structure.

According to the structure containing the combination of the fine cellulose fibers and the organic fibers, the fine cellulose fibers function as a filler by being dispersed between the organic fibers, and have better mechanical strength as compared with the case where the fine cellulose fibers are not contained, for example. Obtainable. However, since the fine cellulose fibers easily aggregate due to their fine structure, it is not possible to sufficiently obtain the effect of improving the physical properties of the fine cellulose fibers simply by combining the fine cellulose fibers with the organic fibers. Further, since the fine cellulose fiber is hydrophilic in nature, it is not always suitable as a filler for articles that require water resistance. Further, a molding material that simply combines fine cellulose fibers and organic fibers does not have sufficient moldability (particularly shape followability to a molding mold). When the fine cellulose fibers and the organic fibers are combined, the present inventors have (1) prevented the aggregation of the fine cellulose fibers and satisfactorily disperse and intervene between the organic fibers by the presence of the blocked polyisocyanate. 2) Water resistance is obtained mainly by using fine cellulose fibers as a scaffold, and (3) good moldability (particularly shape followability to a molding mold) is imparted to a structure as a molding material. I found.

The blocked polyisocyanate is a compound having a structure in which the isocyanate groups of the polyisocyanate (that is, a polyfunctional compound having two or more isocyanate groups per molecule) are blocked by the blocking groups, and is substantially non-reactive at room temperature. On the other hand, above the desorption temperature of the blocking group, two or more free isocyanate groups are generated per molecule, and the reaction with a functional group having reactivity with the isocyanate group (for example, a functional group having active hydrogen) is carried out. Form a bridge structure. The fine cellulose fiber has a hydroxyl group which is a functional group having reactivity with the isocyanate group, but the blocked polyisocyanate retains the blocking group in the dispersion or the structure, so that it does not react with the fine cellulose fiber. However, it is adsorbed on the fine cellulose fibers and functions as a dispersant for the fine cellulose fibers, and contributes to uniform dispersion of the fine cellulose fibers among the organic fibers. When the dispersion or structure is heated above the desorption temperature of the blocking group, the polyisocyanates and the fine cellulose fibers and the polyisocyanate are chemically bonded to each other, and the polyisocyanate-polyisocyanate and the polyisocyanate- A crosslinked structure between the fine cellulose fibers is formed. When the organic fiber has a functional group having active hydrogen, a crosslinked structure between the polyisocyanate and the organic fiber is also formed. Due to the above-mentioned crosslinked structure formed by the use of blocked polyisocyanate, the fine cellulose fibers maintain the fine structure in the crosslinked structure (that is, while avoiding aggregation of the fine cellulose fibers), and a stable three-dimensional network. Further, it is made water resistant by reducing the number of hydroxyl groups (due to the reaction with the isocyanate group), so that the physical properties of the crosslinked structure can be improved more remarkably.

In the crosslinked structure of the present embodiment, the fine cellulose fibers spreading between the organic fibers are not only dispersed between the organic fibers but also form a three-dimensional network by the crosslinked structure derived from the blocked polyisocyanate. Therefore, it can be molded with a complicated shape and can have good mechanical strength, water resistance and solvent resistance. Therefore, the crosslinked structure of the present embodiment includes, for example, various containers for food, various containers used as daily necessities, stationery, packaging materials, packaging materials, board materials such as decorative boards, interior products, and the like. It can be suitably applied to the application. Hereinafter, examples of dispersions, structures, crosslinked structures, and methods for producing these will be described.

<Dispersion and its manufacturing method>
The dispersion produced in the present embodiment contains fine cellulose fibers having an average fiber diameter of 2 nm or more and 1000 nm or less, organic fibers having a fiber diameter of more than 3000 nm, block polyisocyanate, and water.

In one embodiment, the dispersion may contain 0.01-15% by weight of fine cellulose fibers, 0.02 to 30% by weight of organic fibers, 0.0001 to 10% by weight of blocked polyisocyanate, and water.

(Fine cellulose fiber)
The fine cellulose fibers have an average fiber diameter of 2 nm or more and 1000 nm or less. Here, the average fiber diameter of the fine cellulose fibers means the average fiber diameter recognized from the SEM image or the TEM image of the surface, and the measurement thereof is in accordance with the evaluation means described in International Publication No. WO2006 / 4012. Cellulose with an average fiber diameter of less than 2 nm has no clear difference from molecular chains such as hemicellulose dissolved in water, so its physical properties (strength, rigidity, dimensional stability, etc.) as fine fibers are structural. Not enough as a body reinforcement. On the other hand, cellulose having an average fiber diameter of more than 1000 nm does not have a sufficient effect of being uniformly distributed among organic fibers and functioning as a reinforcing material. From the viewpoint of obtaining good physical properties as a reinforcing material, the average fiber diameter is preferably 10 nm or more, more preferably 15 nm or more, still more preferably 20 nm or more, and the fine cellulose fibers are uniformly distributed among the organic fibers for reinforcement. From the viewpoint of functioning well as a material, it is preferably 800 nm or less, more preferably 600 nm or less, and further preferably 500 nm or less.

The fine cellulose fiber may be either a short fiber (staple) or a continuous long fiber (filament), but is preferably a short fiber.

The degree of polymerization (DP) of the fine cellulose fibers is preferably 100 or more and 12,000 or less. The degree of polymerization of the fine cellulose fibers is the number of repetitions of the glucose ring forming the cellulose molecular chain. The degree of polymerization of the fine cellulose fibers is measured by measuring the viscosity of the copper ethylenediamine solution by the copper ethylenediamine method. The viscosity average degree of polymerization DP is obtained from the following viscosity formula. Here, [η] is the intrinsic viscosity.
DP = 175 × [η]
When the degree of polymerization of the fine cellulose fibers is 100 or more, the tensile strength and elastic modulus of the fibers themselves are improved, and as a result, the mechanical strength and handleability of the structure are improved. The degree of polymerization is more preferably 150 or more, still more preferably 300 or more. There is no particular upper limit to the degree of polymerization of the fine cellulose fibers, but since it is practically difficult to obtain cellulose having a degree of polymerization exceeding 12,000, the degree of polymerization is usually 12,000 or less, and it is easy to handle and industrial. From the viewpoint of practical implementation, it is preferably 8,000 or less, more preferably 6,000 or less.

As the fine cellulose fiber, either a chemically modified (that is, unmodified) fiber or a chemically modified fiber can be used. Typical chemical modifications include esterification (eg, acetate esterification, nitrate esterification, or sulfate esterification) and etherification (eg, methyl ether) of some or most of the hydroxyl groups present on the surface of the fine cellulose fibers. Alkyl ether, carboxymethyl ether typified by carboxy ether, or cyanoethyl ether typified by cyano ether), oxidation (for example, the carboxyl group (acid) of the hydroxyl group at the 6-position of the glucose ring by the TEMPO oxidation catalyst. (Including molds and salts) oxidation) and the like. In a preferred embodiment, it is desirable that the fine cellulose fiber has a hydroxyl group remaining on the surface in consideration of the reactivity with the blocked polyisocyanate. That is, the fine cellulose fiber is preferably a fiber whose surface is not chemically modified, but a hydroxyl group remains on the surface even if the fiber is chemically modified such as an acetyl group, a carboxyl group, and a phosphate ester group. If so, it can be suitably used as a fine cellulose fiber used in the present invention.

The mass ratio of the fine cellulose fibers to the total mass of the dispersion is preferably 0.1% by mass or more and 5% by mass or less. When the mass ratio of the fine cellulose fibers is 0.1% by mass or more, a uniform structure can be produced with high productivity. On the other hand, when the mass ratio of the fine cellulose fibers is 5% by mass or less, the viscosity of the dispersion does not become too high and a uniform structure can be easily produced. Therefore, the mechanical strength and water resistance of the obtained crosslinked structure are obtained. It is easy to keep good and the handleability is also good. The mass ratio of the fine cellulose fibers is more preferably 0.15% by mass or more and 4% by mass or less, and further preferably 0.2% by mass or more and 3% by mass or less.

Examples of the raw material of the fine cellulose fiber include so-called wood pulp such as softwood pulp and hardwood pulp, and non-wood pulp. Examples of non-wood pulp include cotton-derived pulp such as cotton linter pulp, hemp-derived pulp, bagasse-derived pulp, kenaf-derived pulp, bamboo-derived pulp, and straw-derived pulp. Cotton-derived pulp, hemp-derived pulp, bagasse-derived pulp, kenaf-derived pulp, bamboo-derived pulp, and straw-derived pulp are cotton lint or cotton linter, and hemp-based abaca (for example, most of them are from Ecuador or the Philippines). , Zaisal, bagasse, kenaf, bamboo, straw, etc., means purified pulp obtained through a purification process and a bleaching process for the purpose of removing lignin and hemicellulose by cooking treatment. In addition, purified products such as seaweed-derived cellulose and sea squirt cellulose can also be used as raw materials for fine cellulose fibers. Further, the cut yarn of the regenerated cellulose fiber and the cut yarn of the cellulose derivative fiber can be used as the raw material of the fine cellulose fiber, and the cut yarn of the ultrafine yarn of the regenerated cellulose or the cellulose derivative obtained by the electrospinning method is also the fine cellulose fiber. It can be used as a raw material or as a fine cellulose fiber itself. Among these, refined pulp derived from cotton lint or cotton linter, hemp-based abaca (mostly from Ecuador or the Philippines), zeal, bagasse, kenaf, bamboo, straw, etc. is a fine cellulose fiber with a long fiber length. Is particularly preferable because it is easy to obtain and has a high reinforcing effect as a filler due to entanglement.

Next, a method for refining the cellulose fiber will be described. It is preferable that the cellulose fibers are miniaturized through a pretreatment step, a beating treatment step and a miniaturization step. In the pretreatment step, it is effective to make the raw material pulp into a state in which it is easy to be finely divided by autoclave treatment under water impregnation at a temperature of 100 to 150 ° C., enzyme treatment, or a combination thereof. These pretreatments not only reduce the load of the miniaturization treatment, but also discharge the impurity components such as lignin and hemicellulose existing on the surface and gaps of the microfibrils constituting the cellulose fibers to the aqueous phase, resulting in fineness. Since it also has the effect of increasing the α-cellulose purity of the converted fibers, it may be effective in improving the heat resistance of the fine cellulose fiber non-woven fabric.

In the beating treatment step, the raw material pulp is solidified in an amount of 0.5% by mass or more and 4% by mass or less, preferably 0.8% by mass or more and 3% by mass or less, and more preferably 1.0% by mass or more and 2.5% by mass or less. It is dispersed in water so that it has a partial concentration, and fibrillation is highly promoted by a beating device such as a beater or a disc refiner (double disc refiner). When using a disc refiner, if the clearance between discs is set as narrow as possible (for example, 0.1 mm or less) and processing is performed, extremely high-level beating (fibrillation) proceeds, so a high-pressure homogenizer or the like is used. The conditions of the miniaturization process can be relaxed and may be effective.

The preferred degree of beating process is defined as follows. In the study by the present inventors, the CSF value (indicating the degree of beating of cellulose, evaluated by the Canadian standard freshness test method for pulp defined in JIS P 8121) decreased with time as the beating treatment was performed. It was confirmed that once it became close to zero, it tended to increase again when the beating treatment was continued. In order to prepare the fine cellulose fiber which is the raw material of the non-woven fabric structure of the present embodiment, it was pretreated. As a result, it was found that it is preferable to once the CSF value is close to zero, and then continue the beating process until the CSF value is increased. In the present disclosure, the CSF value in the process of decreasing the CSF value from the unbeaten solution is expressed as *** ↓, and the CSF value in the tendency of increasing after becoming zero is expressed as *** ↑. In the beating process, the CSF value is preferably at least zero, more preferably CSF30 ↑. In the aqueous dispersion prepared at such a beating degree, fibrillation is highly advanced, and a homogeneous sheet made of fine cellulose fibers having a number average fiber diameter of 1000 nm or less can be obtained. At the same time, the obtained fine cellulose fiber sheet tends to have improved tensile strength probably because of the increase in the adhesion points between the cellulose microfibrils. In addition, a highly beaten aqueous dispersion having a CSF value of at least zero or a value of *** ↑ increases in uniformity, and can reduce clogging in the subsequent miniaturization treatment by a high-pressure homogenizer or the like. There is an efficiency advantage.

In the production of the fine cellulose fibers, it is preferable to carry out a micronization treatment with a high-pressure homogenizer, an ultra-high-pressure homogenizer, a grinder or the like, following the beating step described above. The solid content concentration in the aqueous dispersion at this time is 0.5% by mass or more and 4% by mass or less, preferably 0.8% by mass or more and 3% by mass or less, more preferably 1.0, according to the beating treatment described above. It is mass% or more and 2.5 mass% or less. When the solid content concentration is in this range, clogging does not occur and efficient miniaturization processing can be achieved.

Examples of the high-pressure homogenizer to be used include NS type high-pressure homogenizer of Niro Soabi Co., Ltd. (Italy), Lanier type (R model) pressure type homogenizer of SMT Co., Ltd., and high-pressure homogenizer of Sanwa Machinery Co., Ltd. Any device other than these may be used as long as it is a device capable of performing miniaturization by a mechanism substantially similar to these devices. The ultra-high pressure homogenizer means a high-pressure collision type miniaturization machine such as a microfluidizer of Mizuho Kogyo Co., Ltd., a nanomizer of Yoshida Kikai Kogyo Co., Ltd., and an ultimateizer of Sugino Machine Co., Ltd. Any device other than these may be used as long as it is a device that performs miniaturization with almost the same mechanism. Examples of the grinder type miniaturization device include a pure fine mill manufactured by Kurita Kikai Seisakusho Co., Ltd. and a stone mill type grinding type represented by Super Mascoroider manufactured by Masuyuki Sangyo Co., Ltd., which are almost the same as these devices. Any device other than these may be used as long as the device is miniaturized by the mechanism of.

The average fiber diameter of the fine cellulose fibers is determined by the conditions of the micronization treatment using a high-pressure homogenizer or the like (selection of equipment, operating pressure and number of passes) or the pretreatment conditions before the micronization treatment (for example, autoclave treatment, enzyme treatment, beating). It can be controlled by processing, etc.).

When, for example, a fiber whose surface is chemically modified is used as the fine cellulose fiber, various surface chemical treatments are performed according to the purpose, so that, for example, some or most of the hydroxyl groups present on the surface of the fine cellulose fiber can be removed. , Acetate ester, nitrate ester, sulfuric acid ester, etc., or alkyl ether typified by methyl ether, carboxy ether typified by carboxymethyl ether, cyano ether typified by cyanoethyl ether, etc. , Can be appropriately prepared and used. Further, for example, when a cellulosic fine fiber in which the hydroxyl group at the 6-position is oxidized by a TEMPO oxidation catalyst to become a carboxyl group (including acid type and salt type) is used, high energy such as a high-pressure homogenizer is necessarily required. It is not necessary to use a micronizer, and a dispersion of fine cellulose can be obtained. For example, as described in the literature (A. Isogai et al., Biomacromolecules, 7, 1687-1691 (2006)), 2,2,6,6-tetramethylpiperidinooxy in an aqueous dispersion of natural cellulose. A catalyst called TEMPO such as radical and an alkyl halide coexist, an oxidizing agent such as hypochlorous acid is added thereto, and the reaction is allowed to proceed for a certain period of time. After purification treatment such as washing with water, a normal mixer is used. By applying the treatment, a dispersion of fine cellulose fibers can be obtained very easily.
In one aspect, two or more kinds of fine cellulose fibers having different raw materials, fibrillation degree, surface chemical treatment and the like may be combined at an arbitrary ratio.

(Organic fiber)
The dispersion contains organic fibers having an average fiber diameter of more than 3000 nm. The average fiber diameter of the organic fibers is more than 3000 nm (3 μm), preferably 3.5 μm or more, more preferably 4 μm or more, from the viewpoint of maintaining a viscosity suitable for mixing the dispersion, and the fine cellulose fibers are fillers. From the viewpoint of uniformly dispersing and functioning as a fiber, it is preferably 30 μm or less, more preferably 27 μm or less, and further preferably 25 μm or less.

The organic fiber preferably has a functional group having active hydrogen (for example, a hydroxyl group, an amide group, an amino group, a carboxyl group, a thiol group, etc.). In a preferred embodiment, the organic fiber comprises or consists of fibers having at least a hydroxyl group and / or an amide group on the surface. Preferable examples of organic fibers having hydroxyl groups and / or amide groups are cellulose fibers, starch fibers, chitin fibers, chitosan fibers and other polysaccharide fibers (poly-α-1,3-glucan, poly-β-1,3- In addition to glucan, etc.), cellulose acetate fibers, polyamide fibers (PA-6 fibers, PA-6, 6 fibers, PA-12 fibers, aromatic polyamide fibers such as Kevlar fibers, etc.), polyvinyl alcohol fibers (vinyl acetate, etc.) (Including copolymers having monomer units) and the like. In particular, when polysaccharide fibers such as cellulose fibers are used, most of them are highly oriented fibers derived from nature. Therefore, when the fine fibers are branched by fibrillation treatment such as beating treatment, the fine cellulose fibers are used. It is particularly preferable because it facilitates interaction such as entanglement. Similarly, a polyamide fiber having high orientation is preferable because the entanglement effect can be increased by a fibrillation treatment such as beating treatment, but the effect of the present invention is effectively exhibited even when used without beating treatment. In some cases. The mass ratio of the organic fiber having a hydroxyl group and / or the amide group to the total mass of the organic fiber is preferably 20% by mass or more, more preferably 30% by mass or more in that the organic fiber can be satisfactorily crosslinked with the blocked polyisocyanate. , More preferably 40% by mass or more. The mass ratio may be 100% by mass, but from the viewpoint of obtaining the advantage (for example, imparting water resistance to the structure) by using a fiber having no hydroxyl group and / or amide group, for example, 95% by mass or less, or 90% by mass. % Or less, or 85% by mass or less.

The mass ratio of the organic fiber to the total mass of the dispersion is preferably 5 to 65% by mass, more preferably 8 to 55% by mass, and further preferably 10 to 50% by mass from the viewpoint of handleability at the time of manufacturing the structure. is there.

The mass ratio of the fine cellulose fibers to the organic fibers (fine cellulose fibers / organic fibers) in the dispersion is preferably 0.2 / 99 from the viewpoint that the fine cellulose fibers penetrate between the organic fibers and show a good reinforcing effect. It is .8 to 30/70, more preferably 0.5 / 99.5 to 25/75, and even more preferably 1/99 to 20/80.

The solid content ratio of the dispersion is preferably 1% by mass or more, more preferably 3% by mass or more, still more preferably 5% by mass or more, and preferably 55% by mass or less from the viewpoint of handleability of the dispersion. It is preferably 50% by mass or less, more preferably 40% by mass or less.

(Block polyisocyanate)
The dispersion comprises a blocked polyisocyanate. The blocked polyisocyanate is (1) having a polyisocyanate compound such as a polyisocyanate and a polyisocyanate derivative as a basic skeleton, and (2) blocking the isocyanate group with a blocking group to prevent the reaction between the isocyanate group and water. (3) Does not react with functional groups having active hydrogen at room temperature (specifically, 30 ° C. or lower), (4) Block groups are desorbed by heat treatment above the desorption temperature, and active isocyanate groups are regenerated. It is a compound that reacts with a functional group having active hydrogen to form a bond. The polyisocyanate means a polyfunctional isocyanate having two or more isocyanate groups. Similarly, blocked polyisocyanate means a polyisocyanate in which an isocyanate group is blocked by a blocking group. By heating the blocked polyisocyanate in the dispersion and in the structure at a temperature equal to or higher than the desorption temperature of the blocking group, the blocked polyisocyanate is cured by itself, and at the same time, the fine cellulose fiber and the organic fiber according to one embodiment (functional group having active hydrogen) are formed. When it has), it forms a crosslinked structure.

The blocked polyisocyanate is selected from compounds in which the isocyanate group of a polyisocyanate (that is, a compound having two or more isocyanate groups in the molecule) is replaced with a blocking group. Examples of the basic skeleton of the polyisocyanate include aromatic polyisocyanates, alicyclic polyisocyanates, and aliphatic polyisocyanates. Of these, alicyclic polyisocyanates and aliphatic polyisocyanates are more preferable from the viewpoint of less yellowing.

Examples of the aromatic polyisocyanate include 2,4-toluene diisocyanate, 2,6-toluene diisocyanate and its mixture (TDI), diphenylmethane-4,4'-diisocyanate (MDI), and naphthalene-1,5-diisocyanate. , 3,3-Dimethyl-4,4-biphenylenediocyanate, crude TDI, polymethylenepolyphenyldiisocyanate, crude MDI, phenylenediocyanate, xylylene diisocyanate and other aromatic diisocyanates.
Examples of the alicyclic polyisocyanate include alicyclic diisocyanates such as 1,3-cyclopentane diisocyanate, 1,3-cyclopentene diisocyanate, and cyclohexane diisocyanate.
Examples of the aliphatic polyisocyanate include aliphatic diisocyanates such as trimethylene diisocyanate, 1,2-propylene diisocyanate, butylene diisocyanate, pentamethylene diisocyanate, and hexamethylene diisocyanate.

Examples of the polyisocyanate derivative as the basic skeleton of the blocked polyisocyanate include active hydrogen in addition to the above-mentioned polyisocyanate multimers (for example, dimer, trimer, pentamer, heptameric, etc.). Examples thereof include reaction products obtained by reacting one kind or two or more kinds of compounds. Examples of the reaction product include an allophanate modified product (for example, an allophanate modified product produced by the reaction of polyisocyanate with alcohols) and a polyol modified product (for example, a polyol modification produced by the reaction of polyisocyanate with alcohols). Body (alcohol adduct), etc.), biuret modified product (for example, biuret modified product produced by reaction of polyisocyanate with water or amines, etc.), urea modified product (for example, produced by reaction of polyisocyanate with diamine) Urea modified product, etc.), oxadiazine trione modified product (for example, oxadiazine trione produced by the reaction of polyisocyanate with carbonic acid gas, etc.), carbodiimide modified product (carbodiimide modification produced by decarbonate condensation reaction of polyisocyanate) (Body, etc.), uretdione denatured product, uretonimine denatured product, etc.

Examples of the active hydrogen-containing compound include 1- to 6-valent hydroxyl group-containing compounds (for example, polyester polyols, polyether polyols, etc.), amino group-containing compounds, thiol group-containing compounds, carboxyl group-containing compounds, and the like. Water, carbon dioxide, etc. existing in the air or in the reaction field can also be active hydrogen-containing compounds.

Examples of 1-hexavalent alcohols (that is, polyols) include non-polymerized polyols and polymerized polyols. The non-polymerized polyol is a polyol that does not have a history of polymerization, and the polymerized polyol is a polyol obtained by polymerizing a monomer.

Examples of the non-polymerized polyol include monoalcohols, diols, triols, tetraols and the like. The monoalcohols are not particularly limited, but for example, methanol, ethanol, n-propanol, i-propanol, n-butanol, i-butanol, s-butanol, n-pentanol, n-hexanol, n-octanol, and the like. Examples thereof include n-nonanol, 2-ethylbutanol, 2,2-dimethylhexanol, 2-ethylhexanol, cyclohexanol, methylcyclohexanol, ethylcyclohexanol and the like. The diols are not particularly limited, but for example, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-propanediol. Butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 2-methyl-1,2-propanediol, 1,5-pentanediol, 2-methyl-2,3- Butanediol, 1,6-hexanediol, 1,2-hexanediol, 2,5-hexanediol, 2-methyl-2,4-pentanediol, 2,3-dimethyl-2,3-butanediol, 2- Ethyl-hexanediol, 1,2-octanediol, 1,2-decanediol, 2,2,4-trimethylpentanediol, 2-butyl-2-ethyl-1,3-propanediol, 2,2-diethyl- Examples thereof include 1,3-propanediol, fluoroglucolsin, pyrogallol, catechol, hydroquinone, bisphenol A, bisphenol F and bisphenol S. The triols are not particularly limited, and examples thereof include glycerin and trimethylolpropane. The tetraols are not particularly limited, and examples thereof include pentaerythritol, 1,3,6,8-tetrahydroxynaphthalene, and 1,4,5,8-tetrahydroxyanthracene.

The polymerized polyol is not particularly limited, and examples thereof include polyester polyol, polyether polyol, acrylic polyol, and polyolefin polyol.
The polyester polyol is not particularly limited, and is, for example, a single or a mixture of dicarboxylic acids such as succinic acid, adipic acid, sebacic acid, dimer acid, maleic anhydride, phthalic anhydride, isophthalic acid, and terephthalic acid, and ethylene glycol. Obtained by ring-opening polymerization of ε-caprolactone using a polyester polyol obtained by condensation reaction with a polyhydric alcohol such as propylene glycol, diethylene glycol, neopentyl glycol, trimethylolpropane, or glycerin alone or as a mixture, or a polyhydric alcohol. Examples thereof include polycaprolactones and the like.

The polyether polyol is not particularly limited, but for example, a hydroxide such as lithium, sodium and potassium, a strongly basic catalyst such as alcoholate and alkylamine, and a composite metal cyan compound complex such as a metal porphyrin and a zinc hexacyanocobalate complex. Polyether obtained by randomly or blocking addition of alkylene oxides such as ethylene oxide, propylene oxide, butylene oxide, cyclohexene oxide, and styrene oxide alone or a mixture to a polyvalent hydroxy compound alone or a mixture. Examples thereof include polyols and polyether polyols obtained by reacting a polyamine compound such as ethylenediamine with an alkylene oxide. Examples thereof include so-called polymer polyols obtained by polymerizing acrylamide and the like using these polyethers as a medium.

As the polyhydric alcohol compound,
(1) For example, diglycerin, ditrimethylolpropane, pentaerythritol, dipentaerythritol, etc.
(2) Sugar alcohol compounds such as erythritol, D-threitol, L-arabinitol, ribitol, xylitol, sorbitol, mannitol, galactitol, and ramnitol.
(3) For example, monosaccharides such as arabinose, ribose, xylose, glucose, mannose, galactose, fructose, sorbose, rhamnose, fucose, and ribodesource.
(4) For example, disaccharides such as trehalose, sucrose, maltose, cellobiose, gentiobiose, lactose, and melibiose,
(5) For example, trisaccharides such as raffinose, gentianose, and meletitose,
(6) For example, tetrasaccharides such as stachyose,
And so on.

Examples of the acrylic polyol include -2-hydroxyethyl acrylate, -2-hydroxypropyl acrylate, -2-hydroxybutyl acrylate and other acrylic acid esters having active hydrogen, glycerin acrylic acid monoester or methacrylic acid. Monoester, acrylic acid monoester of trimethylolpropane, methacrylic acid monoester, etc., -2-hydroxyethyl methacrylate, -2-hydroxypropyl methacrylate, -2-hydroxybutyl methacrylate, -3-hydroxypropyl methacrylate, Methyl acrylate, ethyl acrylate, isopropyl acrylate, -n-butyl acrylate, etc., which contain alone or a mixture selected from the group of methacrylic acid esters having active hydrogen such as -4-hydroxybutyl methacrylate as essential components, Acrylic acid esters such as -2-ethylhexyl acrylate, methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, -n-butyl methacrylate, isobutyl methacrylate, -n-hexyl methacrylate, and lauryl methacrylate. , Unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, itaconic acid, unsaturated amides such as acrylamide, N-methylolacrylamide, diacetoneacrylamide, and glycidyl methacrylate, styrene, vinyltoluene, vinyl acetate, acrylonitrile, Presence of a single or mixture selected from the group of other polymerizable monomers such as vinyl monomers having a hydrolyzable silyl group such as dibutyl fumarate, vinyltrimethoxysilane, vinylmethyldimethoxysilane, γ-methacryloxypropylmethoxysilane Examples thereof include acrylic polyols obtained by polymerization under or in the absence.

Examples of the polyolefin polyol include polybutadiene having two or more hydroxyl groups, hydrogenated polybutadiene, polyisoprene, and hydrogenated polyisoprene. Further, isobutanol, n-butanol, 2-ethylhexanol and the like, which are monoalcohol compounds having 50 or less carbon atoms, can be used in combination.

Examples of the amino group-containing compound include monohydrocarbylamines having 1 to 20 carbon atoms [alkylamines (butylamines and the like), benzylamines and anilines, etc.], aliphatic polyamines having 2 to 20 carbon atoms (ethylenediamine, hexamethylenediamine and the like). Diethylenetriamine, etc.), alicyclic polyamines with 6 to 20 carbon atoms (diaminocyclohexane, dicyclohexylmethanediamine, isophoronediamine, etc.), aromatic polyamines with 2 to 20 carbon atoms (phenylenediamine, tolylenediamine, diphenylmethanediamine, etc.), carbon Polycyclic polyamines of number 2 to 20 (piperazin, N-aminoethylpiperazin, etc.), alkanolamines (monoethanolamine, diethanolamine, triethanolamine, etc.), polyamide polyamines obtained by condensation of dicarboxylic acids with excess polyamines, Examples thereof include polyether polyamines, hydrazines (hydrazine and monoalkylhydrazine, etc.), dihydrazides (dihydrazide succinate, dihydrazide terephthalate, etc.), guanidine (butylguanidine, 1-cyanoguanidine, etc.), dicyandiamide, and the like.

Examples of the thiol group-containing compound include a monovalent thiol compound having 1 to 20 carbon atoms (alkyl thiol such as ethyl thiol, phenyl thiol and benzyl thiol) and a polyvalent thiol compound (ethylene dithiol and 1,6-hexanedithiol). Etc.) etc.

Examples of the carboxyl group-containing compound include a monovalent carboxylic acid compound (alkylcarboxylic acid such as acetic acid and aromatic carboxylic acid such as benzoic acid) and a polyvalent carboxylic acid compound (alkyldicarboxylic acid such as oxalic acid and malonic acid, and terephthal. Aromatic dicarboxylic acids such as acids) and the like can be mentioned.

The blocking group is added to the isocyanate group of the polyisocyanate compound to block it. This block group is stable at room temperature, but when heated to a predetermined desorption temperature (usually about 100 to about 200 ° C.), the block group is desorbed and the free isocyanate group can be regenerated.

As a blocking agent that provides a blocking group that meets these requirements,
(1) Alcohols such as methanol, ethanol, 2-propanol, n-butanol, sec-butanol, 2-ethyl-1-hexanol, 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, etc.
(2) Alkylphenol system: Mono and dialkylphenols having an alkyl group having 4 or more carbon atoms as a substituent, for example, n-propylphenol, isopropylphenol, n-butylphenol, sec-butylphenol, t-butylphenol, n. Monoalkylphenols such as −hexylphenol, 2-ethylhexylphenol, n-octylphenol, n-nonylphenol, di-n-propylphenol, diisopropylphenol, isopropylcresol, di-n-butylphenol, di-t-butylphenol, di-sec Dialkylphenols such as -butylphenol, di-n-octylphenol, di-2-ethylhexylphenol, and di-n-nonylphenol,
(3) Phenols: Phenols, cresols, ethylphenols, styrenated phenols, hydroxybenzoic acid esters, etc.
(4) Active methylene system: dimethyl malonate, diethyl malonate, methyl acetoacetate, ethyl acetoacetate, acetylacetone, etc.
(5) Mercaptan type: Butyl mercaptan, dodecyl mercaptan, etc.
(6) Acid amides: acetanilide, acetate, ε-caprolactam, δ-valerolactam, γ-butyrolactam, etc.
(7) Acid imide system: succinimide, maleate imide, etc.
(8) Imidazole system: imidazole, 2-methylimidazole, 3,5-dimethylpyrazole, 3-methylpyrazole, etc.
(9) Urea system: urea, thiourea, ethylene urea, etc.
(10) Oxime system: formaldehyde, acetaldehyde, acetoxime, methylethylketooxime, cyclohexanone oxime, etc.
(11) Amines: Diphenylamine, aniline, carbazole, di-n-propylamine, diisopropylamine, isopropylethylamine, etc.
Each of these blocking agents can be used alone or in combination of two or more.

The blocked polyisocyanate may be anionic, nonionic or cationic, but is preferably a cationic blocked polyisocyanate. Cationic block polyisocyanate is advantageous in that it is easily adsorbed on fine cellulose fibers by electrostatic interaction. That is, it is known that the surface of a general cellulose fiber is anionic (zeta potential in distilled water-30 to -20 mV) (Non-Patent Document 1 J. Brandrup (editor) and E.H. Immuno (editor). Therefore, it is preferable that the blocked polyisocyanate is cationic in terms of electrostatic interaction because of "Polymer Handbook 3rd edition" V-153 to V-155).

However, even if the blocked polyisocyanate is nonionic, it is possible to satisfactorily adsorb the blocked polyisocyanate to the fine cellulose fibers by adjusting the polymer chain length, rigidity, etc. of the hydrophilic group of the blocked polyisocyanate. is there. Further, even for a blocked polyisocyanate, such as an anionic blocked polyisocyanate, which is more difficult to adsorb due to electrostatic repulsion with fine cellulose fibers, a generally well-known cationic adsorption aid or cationic polymer is used. As a result, the blocked polyisocyanate can be adsorbed on the fine cellulose fibers.

In the dispersion, the amount of the blocked polyisocyanate with respect to 100 parts by mass of the fine cellulose fibers is preferably 0.1 part by mass or more, more preferably 0.3 parts by mass or more, from the viewpoint of obtaining the advantages of using the blocked polyisocyanate. More preferably 0.5 parts by mass or more, further preferably 1 part by mass or more, still more preferably 3 parts by mass or more, and reducing the residual unreacted blocked polyisocyanate in the crosslinked structure in the molded product. From the viewpoint of satisfactorily preventing inconveniences such as the occurrence of cracks, the amount is preferably 120 parts by mass or less, more preferably 100 parts by mass or less, and further preferably 90 parts by mass or less.

The amount of blocked polyisocyanate in the dispersion with respect to a total of 100 parts by mass of the fine cellulose fibers and organic fibers is preferably 0.5 parts by mass or more, more preferably 0.5 parts by mass or more, from the viewpoint of obtaining the advantages of using the blocked polyisocyanate. It is 1 part by mass or more, more preferably 1.5 parts by mass or more, and preferably 80 parts by mass or less, more preferably 50 parts by mass or less, from the viewpoint of reducing the residual unreacted blocked polyisocyanate in the crosslinked structure. It is more preferably 30 parts by mass or less.

The amount of blocked polyisocyanate in the dispersion is preferably 0.0001% by mass or more, more preferably 0.001% by mass or more, still more preferably 0.005, from the viewpoint of obtaining the advantages of using the blocked polyisocyanate. From the viewpoint of reducing the residual unreacted blocked polyisocyanate in the crosslinked structure, it is preferably 10% by mass or less, more preferably 6% by mass or less, still more preferably 4% by mass or less.

The blocked polyisocyanate is preferably present in the dispersion in the form of an aqueous dispersion (for example, an emulsion), in which case the dispersibility of the blocked polyisocyanate in the dispersion is better. Examples of the emulsion include a self-emulsifying emulsion and a forced emulsifying emulsion. In both the self-emulsifying type and the forced emulsifying type emulsions, anionic, nonionic or cationic hydrophilic groups are exposed on the surface.

The self-emulsifying emulsion is an emulsion obtained by directly bonding a hydrophilic compound (for example, an active hydrogen group-containing compound having an anionic group, a nonionic group or a cationic group) to a blocked polyisocyanate and emulsifying it. .. The active hydrogen group-containing compound having an anionic group is not particularly limited, and examples thereof include a compound having one anionic group and having two or more active hydrogen groups.

Examples of the anionic group include a carboxyl group, a sulfonic acid group, a phosphoric acid group, and a betaine structure-containing group. More specifically, examples of the active hydrogen group-containing compound having a carboxyl group include dihydroxycarboxylic acids such as 2,2-dimethylolacetic acid and 2,2-dimethylollactic acid, for example, 1-carboxy-1,5-penti. Examples thereof include diaminocarboxylic acids such as rangeamine and dihydroxybenzoic acid, and half-ester compounds of polyoxypropylene triol and maleic anhydride and / or phthalic anhydride.

Examples of the active hydrogen group-containing compound having a sulfonic acid group include N, N-bis (2-hydroxyethyl) -2-aminoethanesulfonic acid, 1,3-phenylenediamine-4,6-disulfonic acid and the like. Be done.
In addition, examples of the active hydrogen group-containing compound having a phosphoric acid group include 2,3-dihydroxypropylphenyl phosphate and the like.
Examples of the active hydrogen group-containing compound having a betaine structure-containing group include a sulfobetaine group-containing compound obtained by reacting a tertiary amine such as N-methyldiethanolamine with 1,3-propanesulton. it can.

The active hydrogen group-containing compound having an anionic group may be a modified alkylene oxide by adding an alkylene oxide such as ethylene oxide or propylene oxide. The active hydrogen group-containing compound having an anionic group can be used alone or in combination of two or more.

The active hydrogen group-containing compound having a nonionic group is not particularly limited, and for example, a polyalkylene ether polyol containing an ordinary alkoxy group as a nonionic group is used. Ordinary nonionic group-containing polyester polyols, polycarbonate polyols and the like are also used.
As the polymer polyol, those having a number average molecular weight of 500 to 10,000, particularly 500 to 5,000, are preferably used.

The active hydrogen group-containing compound having a cationic group is not particularly limited, but is an aliphatic compound having an active hydrogen-containing group such as a hydroxyl group or a primary amino group and a tertiary amino group, for example. Examples thereof include N, N-dimethylethanolamine, N-methyldiethanolamine, N, N-dimethylethylenediamine and the like. Further, N, N, N-trimethylolamine, N, N, N-triethanolamine and the like having a tertiary amine can also be used. Of these, a polyhydroxy compound having a tertiary amino group and containing two or more active hydrogens reactive with an isocyanate group is preferable.

The active hydrogen group-containing compound having a cationic group may be a modified alkylene oxide by adding an alkylene oxide such as ethylene oxide or propylene oxide. The active hydrogen group-containing compound having a cationic group can be used alone or in combination of two or more.

The cationic group can be easily dispersed in water in the form of a salt by neutralizing with a compound having an anionic group. Examples of the anionic group include a carboxyl group, a sulfonic acid group, and a phosphoric acid group. Examples of the compound having a carboxyl group include formic acid, acetic acid, propionic acid, butyric acid, lactic acid and the like, examples of the compound having a sulfonic group include ethanesulfonic acid, and examples of the compound having a phosphoric acid group include phosphorus. Examples include acids and acidic phosphoric acid esters. A compound having a carboxyl group is preferable, and acetic acid, propionic acid, and butyric acid are more preferable. The equivalent ratio of cationic group: anionic group introduced into the blocked polyisocyanate in the case of neutralization is preferably 1: 0.5 to 1: 3, and more preferably 1: 1 to 1: 1. It is 5. Further, when a tertiary amino group is introduced, the tertiary amino group can be quaternized with dimethyl sulfate, diethyl sulfate or the like.

The ratio of the block polyisocyanate to the active hydrogen group-containing compound is such that the equivalent ratio of isocyanate groups / active hydrogen groups is preferably 1.05 to 1000, more preferably 2 to 200, and further preferably 4 to 100. The range. When the equivalent ratio is 1.05 or more, the isocyanate group content in the hydrophilic polyisocyanate does not become too low, and it is possible to avoid a decrease in the curing rate of the blocked polyisocyanate and weakening of the cured product, and also with fine cellulose fibers. By increasing the number of cross-linking points with the isocyanate group, the blocked polyisocyanate acts well as a water resistant agent and a fixing agent for fine cellulose fibers. When the equivalent ratio is 1000 or less, the effect of lowering the interfacial tension is good, and hydrophilicity is well exhibited. As a reaction method between the polyisocyanate compound (that is, a compound having two or more isocyanate groups in one molecule) and the active hydrogen group-containing compound, a method of mixing both to carry out a normal urethanization reaction is used. Can be done.

The forced emulsification type emulsion is an emulsion obtained by forcibly emulsifying block polyisocyanate with a surfactant or the like. The forced emulsification type emulsion is a well-known general emulsifier (for example, anionic surfactant, nonionic surfactant, cationic surfactant, amphoteric surfactant, polymer-based surfactant, reactive surfactant, etc.). It may be a compound emulsified and dispersed in. Among the emulsifiers, anionic surfactants, nonionic surfactants and cationic surfactants are preferable because they have low cost and good emulsification can be obtained.

Examples of the anionic surfactant include alkylcarboxylic acid salt compounds, alkyl sulfate compounds, and alkyl phosphates.
Nonionic surfactants include ethylene oxide and / or propylene oxide adducts of alcohols having 1 to 18 carbon atoms, ethylene oxide and / or propylene oxide adducts of alkylphenols, ethylene oxide and / or alkylene glycol and / or alkylenediamine. Alternatively, a propylene oxide adduct or the like can be mentioned.
Examples of the cationic surfactant include quaternary ammonium salts such as primary to tertiary amine salts, pyridinium salts, alkyl pyridinium salts, and alkyl halide quaternary ammonium salts.

The amount of these emulsifiers used is not particularly limited, but the mass ratio to 1 part by mass of the blocked polyisocyanate is preferably 0.01 parts by mass or more to obtain good dispersibility, and is preferably 0.3 parts by mass or less. It is preferable because it exhibits good water resistance and action as a functionalizing agent or a fixing agent. The amount used is more preferably 0.05 to 0.2 parts by mass.

Both the self-emulsifying type and the forced emulsifying type can contain a solvent other than water in an amount of, for example, 20% by mass or less of the water-dispersed block polyisocyanate. The solvent is not particularly limited, and examples thereof include ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol dimethyl ether, ethylene glycol, diethylene glycol, and triethylene glycol. These solvents may be used alone or in combination of two or more. From the viewpoint of dispersibility of the solvent in water, the solvent preferably has a solubility in water of 5% by mass or more, and specifically, dipropylene glycol monomethyl ether and dipropylene glycol dimethyl ether are preferable.

The average dispersed particle size of the water-dispersed block polyisocyanate is preferably 1 to 1000 nm, more preferably 10 to 500 nm, and further preferably 10 to 200 nm. The average dispersed particle size is a value measured by a static light scattering laser particle size measuring method.

(Additional ingredients)
The dispersion may further contain additional components in addition to the fine cellulose fibers, organic fibers, blocked polyisocyanates and water. Additional components include inorganic fibers, filler particles, functionalizing agents and the like.

As the inorganic fiber, glass fiber, carbon fiber or the like can be used. The amount of the inorganic fiber is such that the ratio of the inorganic fiber is 1 to 40% by mass, 2 to 30% by mass, or 3 to 20% by mass with respect to the total mass of 100% by mass of the organic fiber and the inorganic fiber. Good.

Examples of the filler particles include silica particles, alumina particles, titanium oxide particles, calcium carbonate particles, polymer particles and the like.

In one aspect, a functionalizing agent for imparting a certain function to the molded product may be contained, and the functionalizing agent includes a water-repellent processing agent, a water-repellent oil-repellent processing agent, an antibacterial polymer, an oil-based compound, and the like. One or more selected from the group consisting of thermoplastic resins, thermosetting resins, and photocurable resins. In the dispersion, the mass ratio of the functionalizing agent based on the solid content is preferably 0.1 to 20% by mass, more preferably 0.2 to 15% by mass, and further preferably 0.3 to 10% by mass. ..

Examples of the water-repellent processing agent or the water-repellent oil-repellent processing agent include various organic resins containing fluorine. In particular, a polymer of an unsaturated monomer such as a perfluoroalkyl group-containing acrylic acid ester, a methacrylate ester, an alkylacrylamide, an alkylvinyl ether, or a vinyl alkyl ketone, or the above-mentioned perfluoroalkyl group-containing unsaturated monomer and acrylic acid, acrylic. Copolymers with unsaturated monomers that do not contain perfluoroalkyl groups, such as acid esters, methacrylic acid, methacrylic acid esters, vinyl chloride, acrylonitrile, maleic acid esters, and polyoxyethylene group-containing unsaturated monomers, are preferable. Further, as a water-repellent processing agent or a water-repellent oil-repellent processing agent containing no fluorine-based compound, a silicone-based compound such as methylhydrogenpolysiloxane, dimethylsiloxane, reactive type (OH group terminal) dimethylpolysiloxane, etc. Examples thereof include compounds, waxes such as ordinary waxes, synthetic paraffin waxes, and paraffin waxes. Further, a mixture of paraffin and an acrylic acid ester-based polymer can also be utilized in order to exert a desired action and effect. Further, a wax-zyroxide compound, that is, a reaction product of the above wax compound and a zirconium compound (specifically, basic zirconium due to zirconium acetate, zirconium hydrochloride, zirconium nitrate, potassium hydroxide, etc.), alkylene urea. Examples thereof include higher fatty acid amide derivatives such as compounds (for example, octadecylethyleneurea or a modified product thereof), aliphatic amide compounds (for example, N-methylolstearyl amide or a modified product thereof). These may be used alone or may be contained in combination of two or more.

Examples of the polymer having antibacterial activity include polyhexamethylene biguanide hydrochloride, chlorohexidine, 2-acrylamide-2-methylpropansulfonic acid copolymer, polymethacrylic acid, a combination of polyacrylate and zinc sulfate, and a phosphate ester. Part of quaternary ammonium salt compound of monomer copolymer, dicyanamide / diethylenetriamine / ammonium chloride condensate, dicyandiamide / polyalkylene / polyamineammonium polycondensate, (polyβ-1,4) -N-acetyl-D-glucosamine Deacetyl compound and hexamethylenebis (reaction product of 3-chloro-2-hydroxypropyldimethylammonium chloride, acrylonitrile / acrylic acid copolymer copper crosslinked product, acrylamide-diallylamine hydrochloride copolymer, methacrylate copolymer, Examples include hydroxypropyl chitosan, crosslinked chitosan, chitosan organic acid salt, chitosan fine powder (polyglucosamine), chito fiber, chitosan, and N-acetyl-D-glucosamine. For example, these antibacterial polymers block the surface of the structure. Immobilization with a polyisocyanate is advantageous in that, as one aspect of the structure, for example, an antibacterial clothing cloth (sheet) having excellent washing resistance is provided.

The antibacterial property evaluation can be performed by, for example, the antibacterial property test method (unified method) for textile products established in JIS-1902-1998. Specifically, 2 g of a sample was placed in advance on the bottom of a closed container, and 0.2 ml of a bacterial solution of Staphylococcus aureus (test bacterial species: AATCC-6538P) diluted with 1/50 broth pre-cultured on this sample was sown. After allowing to stand in an incubator at 37 ° C. for 18 hours, add 20 mL of SCDLP medium and shake thoroughly to wash off the bacteria. This is placed on a normal agar medium, the number of bacteria is measured 24 hours later, and the antibacterial property is judged by comparing the number of bacteria with the unprocessed sample cloth carried out at the same time.
D = (Ma-Mb)-(Mc-Md)
During the ceremony
Ma: Logarithm of viable cell count after 18-hour culture of unprocessed sample (average of 3 samples)
Mb: Logarithm of viable cell count immediately after inoculation of unprocessed sample (average of 3 samples)
Mc: Logarithm of viable cell count after 18-hour culture of processed cloth culture Md: Logarithm of viable cell count immediately after inoculation of processed cloth culture D: Bacteriostatic activity value.
When the bacteriostatic activity value D ≧ 2.2, it is judged to have antibacterial properties. Therefore, it is preferable that the fine cellulose fiber sheet also has a bacteriostatic activity value D ≧ 2.2.

As the oily compound, an oily compound having a boiling point range under atmospheric pressure of 50 ° C. or higher and 200 ° C. or lower is preferable. The oily compound is preferably dispersed in the dispersion in the form of an emulsion at a concentration of 0.15% by mass or more and 10% by mass or less. The concentration of the oily compound in the dispersion is preferably 0.15% by mass or more and 10% by mass or less, more preferably 0.3% by mass or more and 5% by mass or less, and further preferably 0.5% by mass or more and 3% by mass. % Or less. Although the structure can be obtained even if the concentration of the oil-based compound exceeds 10% by mass, the amount of the oil-based compound used in the manufacturing process increases, and the necessity of safety measures and cost restrictions are associated with it. It is not preferable because it occurs. Further, when the concentration of the oily compound is 0.15% by mass or more, the air permeation resistance can be lowered, which is preferable.

Since the oily compound is removed at the time of drying (that is, at the time of manufacturing the structure), it is desirable that the oily compound can be easily removed by drying. Therefore, the boiling point of the oily compound is preferably 50 ° C. or higher and 200 ° C. or lower, and more preferably 60 ° C. or higher and 190 ° C. or lower as the boiling point under atmospheric pressure. When the boiling point is in the above range, the papermaking slurry can be easily operated as an industrial production process, and can be removed by heating relatively efficiently. If the boiling point of the oily compound under atmospheric pressure is less than 50 ° C., it is necessary to handle the papermaking slurry under low temperature control in order to handle it stably, which is not preferable in terms of efficiency. Further, if the boiling point of the oil-based compound under atmospheric pressure exceeds 200 ° C., a large amount of energy is required to heat-remove the oil-based compound in the drying step, which is also not preferable.
Further, the solubility of the oily compound in water at 25 ° C. is 5% by mass or less, preferably 2% by mass or less, more preferably 1% by mass or less, which is efficient for forming the required structure of the oily compound. It is desirable from the viewpoint of contribution.

Examples of the oily compound include hydrocarbons in the range of 6 to 14 carbon atoms, chain saturated hydrocarbons, cyclic hydrocarbons, chain or cyclic unsaturated hydrocarbons, aromatic hydrocarbons, and carbon atoms. Examples thereof include monovalent and first-class alcohols in the range of 5 to 9 carbon atoms. In particular, the fine cellulose fiber porous sheet of the present invention can be particularly preferably produced by using at least one compound selected from 1-pentanol, 1-hexanol, and 1-heptanol. This is considered to be suitable for producing a non-woven fabric having a high porosity and a fine porous structure because the oil droplet size of the emulsion is extremely small (1 μm or less under normal emulsification conditions).
These oily compounds may be blended as a single substance or a plurality of mixtures may be blended. Furthermore, the water-soluble compound may be dissolved in the papermaking slurry in order to control the emulsion properties to an appropriate state.

Examples of the surfactant include anionic surfactants such as alkyl sulfates, polyoxyethylene alkyl sulfates, alkylbenzene sulfonates and α-olefin sulfonates, alkyltrimethylammonium chloride, dialkyldimethylammonium chloride and benzalco chloride. Cationic surfactants such as nium, amphoteric surfactants such as alkyldimethylaminoacetate betaine and alkylamide dimethylaminoacetic acid betaine, and nonionic surfactants such as alkylpolyoxyethylene ether and fatty acid glycerol ester can be mentioned. It is not limited to these.

Examples of the thermoplastic resin include styrene resin, acrylic resin, aromatic polycarbonate resin, aliphatic polycarbonate resin, aromatic polyester resin, aliphatic polyester resin, aliphatic polyolefin resin, cyclic olefin resin, and polyamide. Examples thereof include based resins, polyphenylene ether-based resins, thermoplastic polyimide-based resins, polyacetal-based resins, polysulfone-based resins, and amorphous fluorine-based resins. The number average molecular weight of these thermoplastic resins is generally 1000 or more, preferably 5000 or more and 5 million or less, and more preferably 10,000 or more and 1 million or less. These thermoplastic resins may be contained alone or in combination of two or more. When two or more kinds of thermoplastic resins are contained, the refractive index of the resin can be adjusted by the content ratio, which is preferable. For example, when polymethyl methacrylate (refractive index about 1.49) and acrylonitrile styrene (acrylonitrile content about 21%, refractive index about 1.57) are contained at 50:50, a resin having a refractive index of about 1.53 can be obtained. ..

The thermosetting resin is not particularly limited, and specific examples thereof include an epoxy resin, a thermosetting modified polyphenylene ether resin, a thermosetting polyimide resin, a urea resin, an allyl resin, and a silicon resin. Benzoxazine resin, phenol resin, unsaturated polyester resin, bismaleimide triazine resin, alkyd resin, furan resin, melamine resin, polyurethane resin, aniline resin, and other industrially used resins and two or more of these resins are mixed. Examples thereof include the obtained resin. Among them, epoxy resin, allyl resin, unsaturated polyester resin, vinyl ester resin, thermosetting polyimide resin and the like have transparency and are therefore suitable for use as an optical material.
Examples of the photocurable resin include epoxy resins containing a latent photocationic polymerization initiator. These thermosetting resins or photocurable resins may be contained alone or in combination of two or more.

The thermosetting resin and photocurable resin mean substances having a relatively low molecular weight that are liquid, semi-solid, solid, or the like at room temperature and exhibit fluidity at room temperature or under heating. These can be insoluble and insoluble resins formed by forming a network-like three-dimensional structure while causing a curing reaction or a cross-linking reaction by the action of a curing agent, a catalyst, heat or light to increase the molecular weight. Further, the cured resin product means a resin obtained by curing the thermosetting resin or the photocurable resin.

The curing agent and curing catalyst are not particularly limited as long as they are used for curing a thermosetting resin or a photocurable resin. Specific examples of the curing agent include polyfunctional amines, polyamides, acid anhydrides, and phenolic resins, and specific examples of the curing catalyst include imidazole and the like, which are used alone or as a mixture of two or more of the present invention. It may be contained in.

The above-mentioned functionalizing agent is preferably bonded to the blocked polyisocyanate, and for this purpose, it is preferable to perform a heat treatment for the blocked polyisocyanate to form a chemical bond (covalent bond) as described later. By chemically binding the blocked polyisocyanate to the fine cellulose fibers and also binding to the functionalizing agent, the functionalizing agent is immobilized inside and / or on the surface of the crosslinked structure of the present embodiment. As a result, the function derived from the functionalizing agent is well maintained even after long-term use in water, for example.

The mass ratio of water in the dispersion is preferably 45% by mass or more and 99.9% by mass or less. For example, when the dispersion is used as a papermaking slurry, the mass ratio of water does not make the viscosity excessively high, and fine cellulose fibers and organic fibers can be uniformly dispersed in the dispersion, so that a structure having a uniform structure can be obtained. In terms of points, it is preferably 55% by mass or more, more preferably 70% by mass or more, and the drainage time at the time of forming the structure is not excessively lengthened, the productivity is improved, and the uniformity of the structure is improved. In this respect, it is preferably 99.9% by mass or less, more preferably 99.4% by mass or less, and further preferably 99.2% by mass or less. Further, for example, when the dispersion is used as a coating slurry, the mass ratio of water is preferably 80% by mass or more and 99.5% by mass or less, and more preferably 85% by mass or more and 99% by mass or less.

The dispersion of the present embodiment provides good formability that allows the formation of crosslinked structures of complex shapes. For example, the dispersion is formed into a sheet by a papermaking method or a wet cake molded product is formed by a suitable mold making machine and dried and heat-treated, or molded into an appropriate shape by a pulp molding method and then dried and heat-treated. Therefore, the molded product of the present invention can be produced. Although it is important to adjust the viscosity of the dispersion during these moldings, the viscosity is adjusted to be suitable for the molding method. For example, even when the degree of freedom of dispersion casting is high as in sheeting, the appropriate viscosity differs depending on whether the sheet is thin or thick in the papermaking method (thicker sheets are preferably dispersions with higher solid content and higher viscosity). .. Further, in the case of molding by the coating method, a dispersion having a high solid content and a high viscosity is preferable as compared with the papermaking method, considering the load in the subsequent drying step. In the case of the pulp molding method, it is preferable to use a dispersion having a higher concentration (for example, 10% by mass or more) than that of the papermaking method or the coating method. When the concentration is increased to reduce the drying load, the viscosity becomes high, but the dispersion of the present invention can have high thixotropy (the property of reducing the viscosity by adding shear), so that the dispersion is subjected to appropriate shearing. Can flow to form the shape of the molded body.

The dispersion is produced by a method including mixing fine cellulose fibers having an average fiber diameter of 2 nm or more and 1000 nm or less, organic fibers having an average fiber diameter of more than 3000 nm, block polyisocyanate, and water. For mixing, for example, (1) fine cellulose fibers, blocked polyisocyanate, and water are mixed to prepare a premix, and then the premix and organic fibers (organic fibers alone or in the form of an organic fiber aqueous dispersion or the like may be used. ), Or (2) mixing fine cellulose fibers, organic fibers and water to prepare a premix, and then mixing the premix with blocked polyisocyanate.
Can be done by.

Of the methods (1) and (2) above, the method (1) mixes the blocked polyisocyanate with the fine cellulose fibers prior to the organic fibers, so that the blocked polyisocyanates are mixed with the fine cellulose fibers. It is preferable because it can be adsorbed in a larger amount (that is, selectively), and the dispersibility improving effect and the cross-linking effect of the fine cellulose fibers by the blocked polyisocyanate are improved. In particular, when the block polyisocyanate is a cationic block polyisocyanate and has an electrostatic interaction with the fine cellulose fiber, or when the affinity between the block polyisocyanate and the fine cellulose fiber is high, the method (1) can be used. Pre-adsorbing the blocked polyisocyanate on the fine cellulose fibers is extremely advantageous in localizing the blocked polyisocyanates around the fine cellulose fibers. On the other hand, even in the method (2) above, since the fine cellulose fiber has a larger surface area per unit mass than, for example, an organic fiber due to its fine structure, it is considerably out of the total amount of blocked polyisocyanate. It is possible to adsorb the ratio to the fine cellulose fibers, and for example, when the blocked polyisocyanate is adsorbed to both the fine cellulose fibers and the organic fibers, the method (2) above may be advantageous. Therefore, the order of addition and the mode of addition of each component in the production of the dispersion may be appropriately designed according to the type and amount of the components contained in the dispersion, the use of the dispersion, and the like.

For example, when a plurality of types of additives are added, a system in which the additives aggregate with each other (for example, a cationic polymer and an anionic polymer are present in the dispersion, and these form an ion complex). In the system), the dispersion state of the dispersion, the zeta potential, and the like may change depending on the order in which the additives are added. The amount and order of addition of the additives are appropriately selected according to the desired dispersion state of the dispersion.

The device for uniformly mixing and dispersing the components of the dispersion is appropriately selected according to the viscosity and state of the dispersion. For example, when the dispersion has a low viscosity (in a fluid state), a disperser such as an agitator, a homomixer, a pipeline mixer, and a blender that can wait for a cutting function, a high-pressure homogenizer, and the like can be mentioned. When the dispersion has a high viscosity to the extent that there is no fluidity, it is preferable to use various kneaders that are driven at a low speed. However, when an emulsion such as water-dispersible block polyisocyanate is used, a high-pressure homogenizer, a grinder-type micronizer, a stone mill-type grinding device, etc. are used from the viewpoint of preventing the emulsion from collapsing due to excessive shear stress. Is preferably not used.

The mixing temperature is preferably 5 ° C. or higher, 7 ° C. or higher, or 9 ° C. or higher from the viewpoint of mixing efficiency, and preferably 60 ° C. or lower or 55 ° C. or lower from the viewpoint of preventing the reaction of blocked isocyanate. , Or 50 ° C. or lower.

<Structure and its manufacturing method>
One aspect of the present invention provides a method for producing a structure, which comprises fine cellulose fibers having an average fiber diameter of 2 nm or more and 1000 nm or less, organic fibers having an average fiber diameter of more than 3000 nm, and blocked polyisocyanate.
In one aspect, the method of manufacturing the structure
Dispersion preparation step of preparing a dispersion by the above-mentioned method for producing a dispersion,
It includes a concentration step of dehydrating the dispersion to form a hydrous concentrate, and a structure forming step of drying the hydrous concentrate (preferably drying at 80 ° C. or higher and 120 ° C. or lower) to form a structure. ..
In one aspect, the method of manufacturing the structure
Dispersion preparation step of preparing a dispersion by the above-mentioned method for producing a dispersion,
The structure-forming step of drying the dispersion (preferably at 80 ° C. or higher and 120 ° C. or lower) to form a structure is included.

That is, when forming the structure, the dispersion is once dehydrated (that is, concentrated) by injection or the like and then molded and dried, and the dispersion is molded as it is without the step of dehydrating (that is, concentrating). , Two methods for drying are effective respectively. In the former case, the solid content ratio of the dispersion is preferably in the range of 0.1% by mass to 20% by mass, more preferably 0.2% by mass to 15% by mass, from the viewpoint of the degree of freedom of molding by papermaking. .. In the latter case, the solid content ratio of the dispersion is preferably in the range of 10% by mass to 55% by mass, more preferably 15% by mass to 45% by mass from the viewpoint of viscosity suitable for molding. In either case, if an appropriate mold for molding is used, it is possible to form not only a sheet but also a structure having a complicated shape. Here, preferred embodiments of each of the fine cellulose fibers, organic fibers, blocked polyisocyanates, and additional components, and preferred amounts and ratios thereof, may be similar to those exemplified in the production of the dispersion. For example, the structure contains block polyisocyanate in an amount of preferably 0.1 part by mass to 30 parts by mass with respect to 100 parts by mass of the fine cellulose fiber. The mass ratio of the fine cellulose fibers to the organic fibers in the structure (fine cellulose fibers / organic fibers) is 0.2 / 99.8 to 30/70.

(Dispersion preparation process)
In this step, a dispersion is obtained by the method described above as a method for producing the dispersion.

(Structure formation process)
In the structure forming step, the dispersion can be dehydrated and dried by a manufacturing method, a coating method, or the like, or the dispersion can be directly dried (that is, without going through the dehydration step) to form a structure. The structure may be formed alone or laminated on another member (for example, a sheet), and in the latter case, a coating method is preferable.
In the papermaking method, after the step of preparing the papermaking slurry (as the dispersion of the present disclosure), the papermaking slurry is filtered on a porous substrate and dehydrated (that is, concentrated) while using wet paper (as a hydrous concentrate). The structure can be manufactured through a step of forming (papermaking step) and a step of drying the wet paper to obtain a dried molded body (drying step). After that, the crosslinked structure can be further produced through a heat treatment step of desorbing the blocking group from the blocked polyisocyanate and advancing the crosslinking reaction by heat treatment of the dry sheet.

In the coating method, after the step of preparing a coating slurry or a highly viscous dispersion (as the dispersion of the present disclosure), a member (for example, an organic polymer sheet) is set on a flat or complex-shaped mold. After applying the coating slurry on top by spray coating, gravure coating, dip coating, etc., or spreading a highly viscous dispersion like paper clay (pulp molding method), all of them are directly from the wet state (pulp molding method). That is, the structure can be produced by a step of drying (without going through a concentration step of dehydrating). After that, a crosslinked structure can be produced through a heat treatment step.

Hereinafter, an example of the manufacturing procedure of the structure and the crosslinked structure will be described by taking the case of the papermaking method as an example.

Papermaking process In the papermaking process, the papermaking slurry is filtered to form wet paper. From the viewpoint of the production efficiency of the structure, the filtration time at the time of filtration may be, for example, 60 seconds or less, preferably 30 seconds or less, and more preferably 10 seconds or less. The evaluation of the drainage time is carried out as follows. Paper machine prepared by using a batch type paper machine (manufactured by Kumagai Riki Kogyo Co., Ltd., automatic square sheet machine 25 cm x 25 cm, 80 mesh) with a metal mesh equivalent to 80 mesh as a guide, with a structure of 50 g / m ² The slurry is charged, and then papermaking (dehydration) is performed with the degree of pressure reduction with respect to atmospheric pressure set to 4 KPa. The time required for dehydration at this time is measured as the drainage time.
The drainage time of the papermaking slurry can also be adjusted by increasing or decreasing the degree of decompression.

In the papermaking method, any paper machine equipped with a mesh-sized wire that dehydrates the papermaking slurry and retains the fine cellulose fibers and organic fibers can be used. When obtaining a sheet as a paper machine, it is preferable to use a paper machine such as an inclined wire type paper machine, a long net type paper machine, or a circular net type paper machine to obtain a sheet-like structure with few defects. Can be done. Whether the paper machine is a continuous type or a batch type, it may be used properly according to the purpose. When producing a molded product having a complicated shape (for example, a bottle or a box), a mold having a dehydratable mesh surface mounted on the entire surface of the molded product is used, and the slurry is poured into the mold and then dehydrated. After (that is, concentrated) to form a wet paper molded body having a complicated shape, it is dried to form a structure.

In the present embodiment, in the case of forming a composite of a structure and an additional member in order to manufacture a composite of the crosslinked structure and an additional member (for example, an organic polymer sheet), the additional member Can be used as a support for papermaking. In this case, as the wire or filter cloth of the paper machine, a material that can satisfy the requirements related to the yield ratio and the amount of water permeation in combination with the support is selected.

In dehydration by the papermaking process, high solid differentiation progresses and wet paper is obtained. The solid content of the wet paper is controlled by the suction pressure (wet suction or dry suction) of the papermaking and the pressing process, and the solid content concentration is preferably 6% by mass or more and 50% by mass or less, more preferably the solid content. Adjust the concentration to a range of 8% by mass or more and 45% by mass or less. If the solid content of the wet paper is lower than 6% by mass, the wet paper does not have independence and problems in the process are likely to occur. Further, dehydration to a concentration in which the solid content of the wet paper exceeds 50% by mass is not preferable because cracks are likely to occur in the wet paper.

In addition, if a method is used in which papermaking is performed on a wire or a mesh in a mold, the water in the obtained wet paper is replaced with an organic solvent in the step of replacing the wet paper with an organic solvent, and the paper is dried, the paper becomes porous after drying. Since it becomes a structure, for example, heat insulating properties can be imparted to the structure. For details of this method, refer to Pamphlet 2006/004012 published by the present inventors.
In addition, in the case of manufacturing a composite of a crosslinked structure and an additional member (for example, an organic polymer sheet), when the additional member (for example, an organic polymer sheet) is used as a support, for example, a wire is used. The support is placed on the set paper machine, a part of the water constituting the papermaking slurry is dehydrated (papermaking) on the support, and wet paper is laminated on the support and integrated. A multilayer sheet composed of a multilayer structure having at least two layers or more can be produced. In order to produce a multi-layered sheet having three or more layers, a support having a multi-layered structure of two or more layers may be used. Further, a structure having two or more layers may be paper-made in multiple stages on the support to form a multi-layer sheet having three or more layers.

Drying Step The wet-like material (wet paper, etc.) obtained in the above-mentioned papermaking or coating step becomes the structure of the present embodiment by evaporating water in the drying step by heating. In the drying process, in the case of a sheet-like structure, if a fixed-length drying type dryer that can dry water is used with a fixed length such as a drum dryer or pin tenter, the air permeation resistance It is preferable because a structure having a high value can be stably obtained. On the other hand, when producing a molded product having a complicated shape, a wet structure once molded with a mold is removed from the mold as in the pulp molding method, and a dryer such as a hot air dryer is used to batch or continuously. It may be dried. The drying temperature may be appropriately selected depending on the conditions, but is preferably in the range of 45 ° C. or higher and 180 ° C. or lower, more preferably 60 ° C. or higher and 150 ° C. or lower, and further preferably 80 ° C. or higher and 120 ° C. or lower. Breathable structures can be manufactured. The air permeability of the structure can be controlled by the composition ratio of the fine cellulose fibers and the organic fibers constituting the dispersion, and the lower the mass ratio of the fine cellulose fibers, the higher the air permeability of the structure. The drying temperature is preferably 80 ° C. or higher, 85 ° C. or higher, or 90 ° C. or higher from the viewpoint of drying efficiency (particularly from the viewpoint of increasing the evaporation rate of water to obtain good productivity), and the reaction of blocked isocyanate. From the viewpoint of prevention, prevention of thermal denaturation of the hydrophilic polymer constituting the structure, and prevention of reduction of energy efficiency that affects cost, the temperature is preferably 120 ° C. or lower, 115 ° C. or lower, or 110 ° C. or lower. For example, it is also effective to first perform low-temperature drying at a temperature of 100 ° C. or lower, and then perform multi-stage drying at a temperature of more than 100 ° C. to obtain a highly uniform structure.
The structure can be formed by the above procedure.

In one aspect, the structure is a sheet or molded body. The average thickness of the sheet or molded product may be, for example, 10 to 50,000 μm, or 20 to 40,000 μm, or 30,000 to 30,000 μm. The molded body may have various shapes such as a box shape, a bottle shape, a bowl shape, or a shape in which complicated irregularities are applied thereto, and the thickness of the molded body is, for example, the minimum thickness (that is, the thickness in the molded body). Is the smallest thickness), and may be, for example, 5 to 45,000 μm, or 10 to 40,000 μm, or 15 to 35,000 μm.

In a preferred embodiment, the blocked polyisocyanate is uniformly distributed in the structure in the planar and thickness directions. In the present disclosure, "blocked polyisocyanate is uniformly distributed in the planar direction and the thickness direction in the structure" is defined as follows.
Homogeneity in the plane direction means that the ratio (W1 / W2) of the amount of blocked polyisocyanate (W1) to the amount of cellulose (W2) at an arbitrary point on the surface of the structure is always constant. Here, "always constant" is a coefficient of variation in which the variation of W1 / W2 at any of the four locations is 50% or less when four regions of 1 cm × 1 cm are selected on the surface of the structure. Means that.
Further, the uniformity in the thickness direction means that the ratio of the amount of blocked polyisocyanate to the amount of cellulose in each of the upper part, the middle part, and the lower part when the structure is divided into three equal parts in the thickness direction is the same. When the structure is a molded body having a complicated shape, the thickness direction is determined on a surface capable of sampling four 1 cm × 1 cm regions of the molded body. Here, "same" means that four 1 cm × 1 cm regions are selected on the surface of the structure, and the average of the upper W1 / W2, the average of the middle W1 / W2, and the lower part at any four locations. When the average of W1 / W2 is calculated, it means that the variation of the three average values is a coefficient of variation of 50% or less.

The coefficient of variation of the block polyisocyanate distribution in the plane direction and the thickness direction is preferably 50% or less. When the coefficient of variation is 50% or less, the physical properties such as tensile strength (drying and wetting) and biodegradability are better than those of a structure containing the same amount of blocked polyisocyanate and having a coefficient of variation of more than 50%. is there. The coefficient of variation is a value representing relative variation, and can be calculated by the following formula: coefficient of variation (CV) = (standard deviation / arithmetic mean) × 100.

In the structure, the ratio of the amount of blocked polyisocyanate (W1) to the amount of cellulose (W2) can be obtained, for example, by three-dimensional composition analysis by TOF-SIMS accompanied by sputter etching. TOF-SIMS can analyze the elemental composition and chemical structure of the polar surface of a sample. When a sample is irradiated with a primary ion beam under an ultra-high vacuum, secondary ions are emitted from the polar surface (1 to 3 nm) of the sample. By introducing secondary ions into a time-of-flight (TOF type) mass spectrometer, a mass spectrum of the sample electrode surface can be obtained. At this time, by suppressing the primary ion irradiation dose to a low level, surface components can be detected as molecular ions having a chemical structure and partially cleaved fragments, and information on the elemental composition and chemical structure in the plane direction of the polar surface can be detected. Is obtained. At this time, by repeating sputtering etching with a sputtering etching gun and measurement of secondary ions with a primary ion gun, information on the elemental composition and chemical structure in the depth direction can be obtained, and the composition and chemical structure can be analyzed in three dimensions. ..

The calculation of W1 / W2 by TOF-SIMS is carried out as follows, for example. Samples of 0.5 cm square are collected at four equally divided parts in the 1 cm × 1 cm structure. A three-dimensional TOF-SIMS composition analysis of the four samples is performed. The ratio of the amount of blocked polyisocyanate to the amount of cellulose is the count number (C1) of m / z = 26 (fragment ion: CN) derived from block polyisocyanate and m / z = 59 (fragment ion: C ₂ H ₃ ) derived from cellulose. O ₂ ) It can be obtained as W1 / W2 = C1 / C2 from the count number (C2). For example, CNO (m / z = 42) may be used as a fragment ion derived from another blocked polyisocyanate. Further, for example, C ₃ H ₃ O ₂ (m / z = 71) may be used as another cellulose-derived fragment ion. The observed fragment ions are not limited to the above-mentioned fragment ions because they may differ depending on the composition of the blocked polyisocyanate, the difference in the raw material of cellulose, and the like.
The measurement conditions of TOF-SIMS used are as follows, for example.

(Measurement condition)
Equipment used: nanoTOF (manufactured by ULVAC-PHI)
Primary ion: Bi ₃ ⁺⁺
Acceleration voltage: 30 kV
Ion current: Approximately 0.1 nA (as DC)
Analytical area: 200 μm x 200 μm
Analysis time: Approximately 6 sec / cycle
Detected ions: Negative ions Neutralization: Use electron gun (sputtering conditions)
Spatter ion: Ar2500 ⁺
Acceleration voltage: 20kV
Ion current: Approximately 5nA
Sputter area: 500 μm x 500 μm
Sputtering time: 60 sec / cycle
Neutralization: Use an electron gun

<Crosslinked structure and its manufacturing method>
One aspect of the present invention provides a method for producing a crosslinked structure obtained by crosslinking the blocked polyisocyanate of the structure of the present disclosure described above.
In one aspect, the method for producing a crosslinked structure is
Dispersion preparation step of preparing a dispersion by the above-mentioned method for producing a dispersion,
A concentration step of dehydrating the dispersion to form a hydrated concentrate, and drying the hydrated concentrate (preferably at 80 ° C. or higher and 120 ° C. or lower), followed by or at the same time as the drying, block poly. The step of forming a crosslinked structure is included, in which the blocked polyisocyanate and the fine cellulose fibers and / or organic fibers are crosslinked to form a crosslinked structure by heating at a temperature higher than the desorption temperature of the blocking group in the isocyanate.
In one aspect, the method for producing a crosslinked structure is
The dispersion preparation step of preparing the dispersion by the above-mentioned method for producing a dispersion, and the dispersion are dried (preferably dried at 80 ° C. or higher and 120 ° C. or lower), and the drying is followed by or at the same time as the drying. It includes a crosslinked structure forming step of crosslinking the blocked polyisocyanate with fine cellulose fibers and / or organic fibers to form a crosslinked structure by heating the blocked polyisocyanate at a temperature higher than the desorption temperature of the blocking group.

In one embodiment, cross-linking is performed between polyisocyanates derived from blocked polyisocyanates and / or with polyisocyanates derived from blocked polyisocyanates and fine cellulose fibers and / or organic fibers (typically fine cellulose fibers and optionally organic fibers). Is formed between. In a typical embodiment, the blocked polyisocyanate-derived structure exists as an aggregate in the crosslinked structure. Such an aggregate is remarkably formed when a crosslinked structure is produced using, for example, a dispersion containing the above-mentioned aqueous dispersion type block polyisocyanate as the block polyisocyanate. The aggregate is formed on the fine cellulose fibers and optionally on the organic fibers in the form of a coating film in one embodiment.

When the blocked polyisocyanate is heated at a predetermined desorption temperature or higher according to the blocking group, the blocking group is desorbed to generate a free isocyanate group, and the isocyanate group is a functional group having active hydrogen in the system. It reacts with a group (hydroxyl group, amide group, amino group, thiol group, carboxyl group, etc.) to form a covalent bond. Since the fine cellulose fibers have at least hydroxyl groups, these covalent bonds are formed at least three-dimensionally with respect to the fine cellulose fibers. When the organic fiber has a functional group having active hydrogen, a three-dimensional covalent bond is also formed with respect to the organic fiber. The formation of such a covalent bond imparts good mechanical strength, water resistance and solvent resistance to the crosslinked structure, and elutes the blocked polyisocyanate and the polyisocyanate derived thereto (for example, in water or in a solvent). Elution) is suppressed.

(Dispersion preparation process)
In this step, a dispersion is obtained by the method described above as a method for producing the dispersion.

(Crosslinked structure forming step (heat treatment step))
In this step, following drying (this drying may be carried out in the same manner as the drying of the dispersion described above in the method for producing a structure) or at the same time as drying, at a temperature equal to or higher than the desorption temperature of the blocking group in the blocked polyisocyanate. By heating the block polyisocyanate, fine cellulose fibers and / or organic fibers (typically fine cellulose fibers and optionally organic fibers) are crosslinked.

For example, when the structure is in the form of a sheet, the heat treatment step is a type of heat treatment in which the width is fixed, such as a drum dryer or a pin tenter, from the viewpoint of uniform heat treatment and suppression of shrinkage of the structure due to heating. It is preferable to use a long-drying heat treatment device. When a dryer such as a drum dryer is used, the feed rate can be adjusted and the roll diameter can be adjusted. When the structure is a molded body having a complicated shape that is not in the form of a sheet, the dried solid in the state of being mounted on the mold may be heat-treated while the mold is mounted, or the dried solid may be heat-treated from the mold after drying (molding). The body) may be removed and heat-treated in a free state with a hot air treatment device such as an electric heating type. Similar to the case of the sheet shape, in the former case, the heat treatment is performed at a fixed length, which may be preferable from the viewpoint of ensuring the uniformity of physical properties and preventing the occurrence of cracks.

As described above, the blocked polyisocyanate is stable at room temperature, but the isocyanate group is regenerated by heat treatment above the desorption temperature of the blocking group, and a chemical bond with a functional group having active hydrogen can be formed. The heating temperature varies depending on the blocked polyisocyanate used, but is preferably 130 ° C. or higher and 220 ° C. or lower, more preferably 140 ° C. or higher and 210 ° C. or lower, and the temperature is higher than the desorption temperature of the block group. At a heating temperature lower than the desorption temperature of the block group, the isocyanate group is not regenerated and the crosslinking reaction does not proceed. On the other hand, when heated above 220 ° C., fine cellulose fibers and blocked polyisocyanates, and depending on the type, organic fibers may be thermally deteriorated and colored, so 220 ° C. or lower is preferable.

The heating time is preferably 5 seconds or more and 10 minutes or less, and more preferably 7 seconds or more and 3 minutes or less. If the heating temperature is sufficiently higher than the desorption temperature of the block groups, the heating time can be shortened.

The dry tensile strength of the crosslinked structure per 50 g / m ² basis weight is preferably 5 N / 15 mm or more. The dry tensile strength of the crosslinked structure is affected by the magnitude of the basis weight, but when the dry tensile strength per 50 g / m ^{2 of} the basis weight is 5 N / 15 mm or more, the crosslinked structure is less likely to be damaged, which is preferable. The dry tensile strength per 50 g / m ² basis weight is more preferably 7 N / 15 mm or more, still more preferably 10 N / 15 mm or more. On the other hand, there is no particular upper limit of the dry tensile strength per 50 g / m ² basis weight, but from the viewpoint of ease of manufacture, it is preferably 300 N / 15 mm or less, more preferably 250 N / 15 mm or less, still more preferably 220 N / 15 mm or less. is there. The dry tensile strength is measured after being stored for 24 hours in an environment controlled at room temperature of 20 ° C. and humidity of 50% RH in accordance with JIS P 8113. As the measurement sample, a test sheet described later is used.

The wet tensile strength of the crosslinked structure per 50 g / m ² basis weight is preferably 3 N / 15 mm or more. The wet tensile strength of the crosslinked structure is affected by the magnitude of its basis weight, but when the wet tensile strength per 50 g / m ^{2 of} the basis weight is 3N / 15 mm or more, even when the crosslinked structure is used in a liquid, it is used. Hard to break. The wet tensile strength per basis weight of 50 g / m ² is more preferably 5 N / 15 mm or more, still more preferably 7 N / 15 mm or more. On the other hand, there is no particular upper limit of the wet tensile strength per 50 g / m ² basis weight, but from the viewpoint of ease of manufacture, it is preferably 300 N / 15 mm or less, more preferably 250 N / 15 mm or less, still more preferably 220 N / 15 mm or less. is there. The wet tensile strength is determined by immersing a test sheet prepared in the same manner as the dry tensile strength test sheet in a container filled with water in an amount sufficient to immerse the sheet for 5 minutes, and then determining the dry tensile strength. It is a value of tensile strength when measured by the same method.

As a test sheet as a measurement sample of dry tensile strength and wet tensile strength, a sheet prepared by the following procedure is used. That is, from the dispersion of the present embodiment used as the material of the crosslinked structure to be measured, a sheeting method (papermaking method, coating method, etc.) corresponding to the molding method of the crosslinked structure to be measured has a grain size of 50 g / m ^2. The crosslinked structure sheet of No. 1 is prepared, and the sheet cut into a length of 20 cm and a width of 15 mm is used as a test sheet. The crosslinked structure of the present embodiment is obtained after undergoing a dehydration step, a drying step, and a heat treatment step in some cases with respect to the dispersion of the present embodiment, but the strength of the crosslinked structure having a complicated shape is the said. It may vary depending on the site of the crosslinked structure. Therefore, in the present disclosure, the dry tensile strength and the wet tensile strength of the crosslinked structure are defined by the values obtained by the above method for convenience.

The wet / dry strength ratio is a value calculated by the following formula from the above dry tensile strength and wet tensile strength.
Wet / dry strength ratio (%) = (wet tensile strength) / (dry tensile strength) x 100

The wet / dry strength ratio of the crosslinked structure is preferably 0.4 to 1.2. The wet / dry strength ratio is preferably 0.4 or more, more preferably 0.5 or more, and further, from the viewpoint of obtaining a crosslinked structure having good durability even when the crosslinked structure is used in a liquid such as water. The wet / dry strength ratio is preferably 1.2 or less, preferably 0.6 or more, and from the viewpoint that the ratio of resin such as blocked polyisocyanate of organic fibers increases and the structure is not different from that of plastic. , More preferably 1.1 or less, still more preferably 1.0 or less.

In one aspect, the crosslinked structure may be biodegradable to cellulase. Cellulase is a general term for enzyme proteins that catalyze the hydrolysis reaction of β-1,4 glucoside bonds in cellulose molecular chains. Cellulase is produced by microorganisms such as bacteria and insects, and is widely present in the biological world and easily available. Various types of cellulase are known, and by selecting an appropriate type, cellulose can be efficiently hydrolyzed to glucose units. However, from the viewpoint of industrial use of cellulosic materials, cellulase is an entity that significantly deteriorates the materials. Therefore, it is preferable that the crosslinked structure of the present embodiment has biodegradability resistance to cellulase.

As a method for quantitatively evaluating the biodegradability of the crosslinked structure of the present embodiment to cellulase, for example, a cellulase mixture containing endoglucanase, exoglucanase, and β-glucosidase is used to promote the hydrolysis of cellulose and react. An example is a method of evaluating by quantifying the amount of glucose in a liquid. The amount of glucose produced can be quantified by the glucose oxidase method. In addition, quantification using a kit such as Glucose Test Wako II manufactured by Wako Pure Chemical Industries, Ltd. is also possible. If the amount of glucose produced is small, it means that the hydrolysis reaction of cellulose is difficult to proceed, and it can be said that the biodegradability is high. That is, the following formula:
Glucose yield (%) = (glucose production) / (absolute dry mass of sample) x 100
Can be used to determine the glucose yield. And the biodegradability index is as follows:
Biodegradability index = 1 / (glucose yield / 100)
Can be evaluated using. The higher the biodegradability index, the lower the biodegradability.
The biodegradability index of the crosslinked structure is preferably twice or more the biodegradability index of the comparative crosslinked structure containing no blocked polyisocyanate. Such a high biodegradability index is particularly advantageous in applications such as water treatment filters that are expected to be used in an environment where cellulase may be present.

In the crosslinked structure, parent / hydrophobicity may be appropriately controlled. The parent-hydrophobicity of the crosslinked structure is defined as, for example, when a hydrophilic compound or a hydrophobic compound is applied onto the crosslinked structure or impregnated with the crosslinked structure for a predetermined purpose according to the application. It greatly affects the coating amount or impregnation amount of the hydrophilic compound or hydrophobic compound, and the operability of coating or impregnation. Further, the crosslinked structure has an application to a separation membrane utilizing its parent / hydrophobicity. In particular, the degree of hydrophobicity of the crosslinked structure obtained by heat-treating the structure varies considerably depending on the type and amount of the blocked polyisocyanate added. Therefore, it is possible to control the parent-hydrophobicity of the crosslinked structure by selecting or designing an appropriate blocked polyisocyanate.

Further, adding a compound having a hydrophobic or water-repellent property that the blocked polyisocyanate can react with as a component in the dispersion is also a means for improving the wet / dry strength ratio or controlling the parent-hydrophobicity. It is valid. Examples of the contained compound having a hydrophobic or water-repellent property include various organic resins containing fluorine. In particular, a polymer of an unsaturated monomer such as a perfluoroalkyl group-containing acrylic acid ester, a methacrylate ester, an alkylacrylamide, an alkylvinyl ether, or a vinyl alkyl ketone, or the above-mentioned perfluoroalkyl group-containing unsaturated monomer and acrylic acid or acrylic. Copolymers with unsaturated monomers that do not contain perfluoroalkyl groups, such as acid esters, methacrylic acid, methacrylic acid esters, vinyl chloride, acrylonitrile, maleic acid esters, and polyoxyethylene group-containing unsaturated monomers, are preferable. Further, as a water-repellent processing agent or a water-repellent oil-repellent processing agent containing no fluorine-based compound, a silicone-based compound such as methylhydrogenpolysiloxane, dimethylsiloxane, or reactive (OH group-terminated) dimethylpolysiloxane is wax-based. There are compounds, waxes such as ordinary wax, synthetic paraffin wax, paraffin wax and the like. There are many synthetic paraffins having a low melting point and a high melting point, but paraffin wax having a high melting point is preferable. Further, a modified product in which an acrylic acid ester-based polymer coexists with paraffin can also be utilized in order to exert a desired action and effect. Further, a wax-zyroxide compound, that is, a reaction of the above-mentioned wax compound with a zirconium compound, specifically, a basic zirconium with zirconium acetate, zirconium hydrochloride, zirconium nitrate, potassium hydroxide or the like, or an alkylene urea compound. For example, octadecylethyleneurea or a modified product thereof, an aliphatic amide compound, for example, N-methylol stearyl amide, or a higher fatty acid amide derivative such as a modified product thereof may be mentioned. These may be used alone or may be contained in combination of two or more.

There are several methods for evaluating parental / hydrophobicity, and the method may be selected according to the purpose. In addition, since parent / hydrophobicity is a relative index, it is determined by comparing with the reference substance. For example, using a sheet composed of only fine cellulose fibers and organic fibers as a reference substance, the parent / hydrophobicity of the sheet to which block polyisocyanate and various functionalizing agents are added is determined. As an evaluation method, for example, static contact angle measurement of water droplets can be mentioned. 4 μL of distilled water (20 ° C.) is dropped, and the static contact angle 1 second after the drip is measured with an automatic contact angle meter (for example, trade name: “DM-301”, manufactured by Kyowa Surface Chemistry Co., Ltd.). At this time, it can be said that the smaller the static contact angle is, the more hydrophilic it is, and the larger the static contact angle is, the more hydrophobic it is. Another method is to measure the time it takes for a water droplet to absorb a liquid. This is a method in which 4 μL of distilled water (20 ° C.) is dropped and the time required for the droplets to be absorbed is measured. It is judged that the longer the water is absorbed, the more hydrophobic it is.

The crosslinked structure of the present embodiment can be controlled to a desired air permeation resistance. For example, the air permeation resistance is defined as a value corresponding to a sheet having a basis weight of 50 g / m ² like the tensile strength, and may be 5 to 990000 sec / 100 ml, 10 to 800,000 sec / 100 ml, or 15 to 700,000 sec / 100 ml.

The control of the air permeation resistance can be changed by selecting the average fiber diameter of the fine cellulose fiber and the organic fiber used, and the mixing ratio of a plurality of types of fibers having different average fiber diameters. The smaller the average fiber diameter, the denser the crosslinked structure can be formed. However, the air permeation resistance can be significantly changed by selecting the type of blocked polyisocyanate and the amount added.

The air permeation resistance is 100 ml of air permeation time using a Garley type densometer (manufactured by Toyo Seiki Co., Ltd., model GB2C) for samples with an air permeation resistance of 1,000 sec / 100 ml or less. Means the result of measuring. For the measurement, 10 points are measured at various different positions on one sheet sample obtained by cutting out a sheet having a basis weight of 50 g / m ^{2 of the} crosslinked structure from the crosslinked structure, and the average value is used. The range of air permeation resistance that can be measured by this measuring method is between 1 and 1,800 sec / 100 ml due to the limitation of the time required for measurement. For samples with an air permeability resistance of 1,000 sec / 100 ml or more, the Oken type air permeability resistance tester (manufactured by Asahi Seiko Co., Ltd., model EG01) was measured at room temperature, and the average value of 10 points was calculated. Take.

<Composite and its manufacturing method>
One aspect of the present invention provides a composite of the above-mentioned crosslinked structure and additional members. In one aspect, the composite is a laminate of a crosslinked structure sheet and an organic polymer sheet as an additional member (hereinafter, also simply referred to as an organic polymer sheet). In one aspect, in such a laminated body, the mechanical strength such as tensile strength is further strengthened by the organic polymer sheet, and the handleability as a sheet can be improved. The laminate is particularly suitable for various food containers, daily necessities, various containers used as stationery, packaging materials, packaging materials, board materials such as decorative boards, interior products, and the like. The material of the organic polymer sheet is not particularly specified, but the required performance such as the shape, hardness, mechanical properties, thermal properties, durability, water resistance, and air permeation resistance of the target laminate is not specified. , Or is appropriately selected depending on the use of the laminate. In one embodiment, it is preferred that the crosslinked structure and additional members are chemically crosslinked with a blocked polyisocyanate. From this point of view, as the material of the additional member, a material having a functional group having active hydrogen, specifically, cellulose, nylon, polyvinyl alcohol, polycarboxylic acid or the like is preferable. In the case of a material having no functional group having active hydrogen (for example, polyolefin such as polyethylene and polypropylene, polyester such as polyethylene terephthalate, etc.), the functional group is subjected to surface activation treatment such as corona discharge treatment and plasma treatment. Can be introduced. In the composite, for example, after laminating a structure (that is, a structure before cross-linking) and an additional member, the block polyisocyanate is crosslinked under the above-mentioned conditions, and the crosslinked structure and the additional member are linked to the lock polyisocyanate. It can be produced by a method of obtaining a composite crosslinked by the crosslinked body of the above, a method of laminating a crosslinked structure and an additional member, or the like.

Hereinafter, the present invention will be specifically described with reference to examples. The main measured values of physical properties were measured by the following methods.

(1) Average Fiber Diameter of Fine Cellulose Fibers A wet paper sheet is prepared from a dispersion liquid gradually replaced with tert-butanol with respect to an aqueous dispersion composed of fine cellulose fibers by a filtration method, dried, and used for fiber diameter evaluation. I got a sample of. The surface of the evaluation sample was observed with a scanning electron microscope (SEM) at a magnification of 1000 to 100,000 times according to the average fiber diameter of the fine fibers. From the obtained SEM image, the fiber diameter of each fiber was measured, and the number average value was taken as the average fiber diameter.

(2) Metsuke The basis weight of the sheet was calculated according to JIS P 8124.

(3) Dry-wet strength ratio of tensile strength As described above, the dry-wet strength of the corresponding molded product was measured for the sample prepared as a sheet having a basis weight of 50 g / m ² from the same dispersion by the same method.
First, the evaluation of the tensile strength at the time of drying was performed on 10 samples having a width of 15 mm using a desktop horizontal tensile tester (No. 2000) of Kumagaya Riki Kogyo Co., Ltd. according to the method defined in JIS P 8113. The measurement was performed, and the average value was taken as the drying strength (N / 15 mm). Further, by the same method, the sheet was immersed in a container filled with water sufficient to immerse the sheet for 5 minutes, and 10 samples were measured, and the average value was taken as the wet strength (N / 15 mm).
From the dry strength and wet elongation evaluated above, the following formula:
Wet / wet strength ratio (%) = (wet strength) / (dry strength) x 100
Calculated by Here, neither the dry strength nor the wet strength is converted into the equivalent of a basis weight of 10 g / m ² .
When the dry-wet intensity ratio was 70% or more, it was evaluated as ◯, when it was 50% or more and less than 70%, it was evaluated as Δ, and when it was less than 50%, it was evaluated as ×.

(4) Dry-wet strength ratio after solvent immersion A 25 cm × 25 cm sample was immersed in a container filled with iso-butanol for one day. Then, the sample was dried under vacuum and room temperature, and the dry-wet strength ratio of tensile strength was calculated by the above method. When the dry-wet intensity ratio was 70% or more, it was evaluated as ◯, when it was 50% or more and less than 70%, it was evaluated as Δ, and when it was less than 50%, it was evaluated as ×.

(5) Evaluation of Distribution of Block Polyisocyanate in Structure Sheet First, a 1 cm square sample was collected by selecting any four locations in a 25 cm × 25 cm sheet. Three-dimensional TOF-SIMS composition analysis was performed on the four samples.
[Uniformity in the plane direction]
Count number (C1) of m / z = 26 (fragment ion: CN) derived from blocked polyisocyanate and count number (C2) of m / z = 59 (fragment ion: C ₂ H ₃ O ₂ ) derived from cellulose of four samples ), C2 was standardized (C1 / C2). The uniformity in the plane direction was evaluated as ◯ when the coefficient of variation of the C1 / C2 value of each sample was less than 50% and x when it was 50% or more.
[Uniformity in the thickness direction]
For the four samples, C1 / C2 of the upper part, the middle part, and the lower part when the sheet was divided into three equal parts in the thickness direction was calculated. C1 and C2 are the count number (C1) of m / z = 26 (fragment ion: CN) derived from blocked polyisocyanate and the count number (C2) of m / z = 59 (fragment ion: C ₂ H ₃ O ₂ ) derived from cellulose. ). Furthermore, the average of four C1 / C2 for each of the upper part, the middle part, and the lower part was calculated. At this time, the uniformity in the thickness direction was evaluated as ◯ when the coefficient of variation for the three average values was less than 50% and × when it was 50% or more.

The measurement conditions for TOF-SIMS are as follows.
(Measurement condition)
Equipment used: nanoTOF (manufactured by ULVAC-PHI)
Primary ion: Bi ₃ ⁺⁺
Acceleration voltage: 30 kV
Ion current: Approximately 0.1 nA (as DC)
Analytical area: 200 μm x 200 μm
Analysis time: Approximately 6 sec / cycle
Detected ions: Negative ions Neutralization: Use electron gun (sputtering conditions)
Spatter ion: Ar2500 ⁺
Acceleration voltage: 20kV
Ion current: Approximately 5nA
Sputter area: 500 μm x 500 μm
Sputtering time: 60 sec / cycle
Neutralization: Use an electron gun

(6) Evaluation of initial static contact angle The initial static contact angle of the sample before and after the pretreatment is dropped on the sheet with 4 μL of distilled water (20 ° C.), and the contact angle 1 second after landing is automatically contacted. The measurement was performed by taking a video using an angle meter (trade name: "DM-301", manufactured by Kyowa Surface Chemistry Co., Ltd.). The initial contact angle of 90 ° or more was evaluated as ◯, 30 ° or more and less than 90 ° was evaluated as Δ, and the initial contact angle of less than 30 ° was evaluated as ×.
(7) Evaluation of hydrophobicity (liquid absorption time)
4 μL of distilled water (20 ° C.) is dropped onto the fine cellulose fiber sheet, and the time required for the droplets to be absorbed is measured. It was judged that the longer the water was absorbed, the more hydrophobic it was.
(8) Air permeation resistance Humidity was adjusted in an atmosphere of room temperature of 20 ° C. and humidity of 50% RH. The humidity-controlled sample is a Garley type denso meter (manufactured by Toyo Seiki Co., Ltd., model GB2C) or a Wangken type air permeability resistance tester (manufactured by Asahi Seiko Co., Ltd., model EG01) with an air permeability resistance of 10 points. The measurement was performed, and the average value was taken as the air permeation resistance of the sample.

(9) Film thickness With respect to a sample whose humidity was adjusted in an atmosphere of room temperature of 20 ° C. and humidity of 50% RH, the thickness of 10 points was measured with an automatic micrometer manufactured by Hibridge Seisakusho, and the average value was taken as the thickness of the sample.

<Production Example 1 of Fine Cellulose Fiber Slurry>
As a raw material, linter pulp, which is a natural cellulose obtained from Japan Pulp and Paper Co., Ltd., was used and immersed in water so that the linter pulp was 4% by mass. Then, heat treatment was carried out at 130 ° C. for 4 hours in an autoclave, and the obtained swollen pulp was washed with water a plurality of times to obtain purified linter pulp impregnated with water. Then, the obtained purified linter pulp was dispersed in water so as to have a solid content of 1.5% by mass to obtain a dispersion of 400 L. An SDR14 type lab refiner (pressurized DISK type) manufactured by Aikawa Iron Works Co., Ltd. was used as a disc refiner device, and 400 L of the aqueous dispersion was beaten for 20 minutes with a clearance of 1 mm between the discs. Following that, the beating process was continued under the condition that the clearance was reduced to a level close to almost zero. Sampling was performed over time, and the CSF value of the Canadian standard freshness test method (hereinafter referred to as CSF method) for pulp defined in JIS P 8121 was evaluated for the sampled slurry. As a result, the CSF value decreased over time. Then, it became close to zero once. It was confirmed that the CSF value tended to increase as the beating process was continued. The beating process was continued under the above conditions for 10 minutes after the clearance was set to near zero to obtain a beating slurry having a CSF value of 100 ml or more. The obtained beating water slurry was finely divided 5 times at an operating pressure of 100 MPa using a high-pressure homogenizer (NS015H manufactured by Niro Soabi Co., Ltd.) as it was, and the fine cellulose fiber slurry S1 (solid content concentration: 1. 5% by mass) was obtained. The average fiber diameter of the fine cellulose fibers contained in S1 was 102 nm.

<Production Example 2 of Fine Cellulose Fiber Slurry>
As a raw material, LBKP, which is a softwood pulp obtained from Japan Pulp and Paper Co., Ltd., was used. LBKP was put into water so as to be 1.5% by mass, swollen and dispersed by a pulper treatment, and then beaten by the same method as in Production Example 1 to obtain a slurry of cellulose fine fibers (solid content concentration: 1). 5.5% by mass) was obtained. The CSF value was 50 ml or more after passing through zero and continuing the beating process. The beating slurry was refined 5 times with a high-pressure homogenizer at an operating pressure of 100 MPa in the same manner as in Production Example 1 to obtain a fine cellulose fiber slurry S2 (solid content concentration: 1.5% by mass). The average fiber diameter of the fine cellulose fibers contained in S2 was 85 nm.

<Example of organic fiber slurry production>
As a raw material, LBKP, which is a softwood pulp obtained from Japan Pulp and Paper Co., Ltd., was used. LBKP was put into water so as to be 1.5% by mass, swollen and dispersed by a pulper treatment, and then the clearance between the discs was set to 1 mm in the same manner as in Production Example 1, and 400 L of the aqueous dispersion was prepared by 20. The beating treatment was carried out for 1 minute to obtain a slurry of cellulose fibers having a CSF value of about 550 ml (solid content concentration: 1.5% by mass). The slurry was filtered and concentrated to obtain a cellulose fiber / aqueous dispersion D0 having a solid content of 40% by mass. The average fiber diameter of the cellulose fibers contained in S1 was about 18 μm when observed with an optical microscope.

<Example of Dispersion Preparation for Molding>
10 parts by mass of fine cellulose fiber / aqueous dispersion S1 and cationic block polyisocyanate (trade name "Meikanate WEB", manufactured by Meisei Chemical Works, Ltd.) in a stirring tank filled with water in advance with respect to 100 parts by mass of fine cellulose fiber. A corresponding amount was added to bring the fine cellulose concentration to 0.5% by mass, and the mixture was stirred with an agitator for 5 minutes. Further, while continuing stirring with the agitator, the cellulose fiber / water dispersion D0 was added so that the fine cellulose fiber / cellulose fiber mass ratio was 10/90, and the stirring with the agitator was performed for 5 minutes after the addition of D0 to obtain the dispersion SA1. Got

Under the preparation conditions of SA1, the fine cellulose fiber / aqueous dispersion S1 was used as S2, and the other preparation method was the same as the preparation of SA1 to obtain the dispersion SA2.

Under the preparation conditions of SA1, the cationic block polyisocyanate (trade name "Meikanate WEB", manufactured by Meisei Chemical Works, Ltd.) was used as a nonionic block polyisocyanate (trade name "NY30", manufactured by NICCA CHEMICAL CO., LTD.) The preparation method was the same as the preparation of SA1, and the dispersion SA3 was obtained.

In the preparation conditions of SA1, the amount of blocked isocyanate is 5 parts by mass, 90 parts by mass or 15 parts by mass, the mass ratio of fine cellulose fibers / cellulose fibers is 5/95 or 20/80, and the other preparation method is SA1. Dispersions SA4, SA5 and SA6 were obtained in the same manner as in the preparation.

Under the preparation conditions of SA1, the dispersion RA1 was obtained in the same manner as in the preparation of SA1 by other preparation methods without adding the cationic block polyisocyanate.

10 parts by mass of fine cellulose fiber / aqueous dispersion S1 and cationic block polyisocyanate (trade name "Meikanate WEB", manufactured by Meisei Chemical Works, Ltd.) in a stirring tank filled with water in advance with respect to 100 parts by mass of fine cellulose fiber. A corresponding amount was added to make the fine cellulose concentration 0.5% by mass, and the mixture was stirred with an agitator for 5 minutes to obtain a dispersion RA2.

Cellulose fiber / aqueous dispersion D0 and cationic block polyisocyanate (trade name "Meikanate WEB", manufactured by Meisei Chemical Works, Ltd.) are placed in a stirring tank filled with water in advance, equivalent to 10 parts by mass with respect to 100 parts by mass of cellulose fibers. The amount and water were added to bring the fine cellulose concentration to 5% by mass, and the mixture was stirred with an agitator for 5 minutes to obtain a dispersion RA3.

Table 1 shows the preparation conditions for the dispersion for the molded product.

[Examples 1 to 6]
Using a batch paper machine (manufactured by Kumagai Riki Kogyo Co., Ltd., automatic square sheet machine), pour the dispersion liquid SA1 onto a square metal wire (25 cm x 25 cm, 80 mesh) to make a paper machine with a basis weight of 50 g / m ² . went. A wet paper was prepared with a decompression degree of 4 KPa with respect to the suction (decompression device) atmospheric pressure, and then a dehydration press was carried out and dried with a drum dryer set at 100 ° C. to obtain a sheet-shaped sample SB1. Then, the cross-linking treatment was carried out by heat treatment for 5 minutes in a constant length state with a hot air dryer set at 170 ° C. to obtain a sheet-shaped structure SB1 (Example 1).

The molding dispersion SA1 in Example 1 was replaced with SA2, SA3, SA4, SA5, and SA6, and the sheet-shaped structure SB2 having a basis weight of 50 g / m ^{2 was used in} the same manner as the structure SB1 (Example 2). , SB3 (Example 3), SB4 (Example 4), SB5 (Example 5), SB6 (Example 6) were obtained.

For each of the structures SB1 to SB6 obtained in Examples 1 to 6, the average film thickness, the dry-wet intensity ratio, the dry-wet intensity ratio after immersion in the solvent, and the distribution evaluation of the blocked polyisocyanate in the structure sheet were evaluated according to the above-mentioned method. The plane direction and thickness direction), initial contact angle, hydrophobicity (water absorption time), and air permeation resistance were evaluated. The results are shown in Table 2. All of SB1 to SB6 were excellent in visual homogeneity, and were excellent in water resistance and hydrophobicity.

[Example 7]
Box-shaped (planar size: 100 mm x 100 mm, height: 30 mm, container thickness (clearance) 5 mm for all surfaces) mold container (in the center of the plane direction) with dehydration mesh placed on all outer surfaces A conduit for injecting the dispersion is provided), and after injecting the dispersion SA1 from the conduit, decompression dehydration treatment is performed on the outside of the mesh surface with a decompression degree to atmospheric pressure of 4 KPa to deposit a wet paper layer on the mesh surface. Wet paper was formed, and then the entire mold was dried in a hot air dryer at a temperature of 100 ° C., the mold was disassembled, and the dried molded product was taken out. The molded product was further heat-treated in a hot air dryer at 170 ° C. for 5 minutes in a free state to obtain a foil-shaped structure SB7. The average thickness in the plane direction and the height direction was measured with respect to SB7. In addition, the initial contact angle, hydrophobicity (water absorption time), and air permeation resistance of the flat surface were evaluated. SB7 is a uniform and durable box in both the plane direction and the thickness direction, and no swelling was visually confirmed even when immersed in water.

[Comparative Examples 1 to 3]
In the method for producing the sheet-like structure SB1 in Example 1, the dispersions SA1 were designated as the dispersions RA1, RA2, and RA3, respectively, and the sheet-like structure RB1 with a sheet texture of 50 g / m ² (Comparative Example 1) was prepared by the same method. RB2 (Comparative Example 2) and RB3 (Comparative Example 3) were obtained. However, in papermaking from the dispersion RA2 containing only fine cellulose fibers, PET / nylon blended plain fabric (manufactured by Shikishima Kambas, NT20) is placed on a square metal wire (25 cm x 25 cm, 80 mesh) used in batch papermaking. ) Was installed as a filter cloth, and the dispersion RA2 was injected into a paper machine from above, and papermaking was carried out.

For each of the structures RB1 to RB3 obtained in Comparative Examples 1 to 3, the average film thickness, the dry-wet intensity ratio, the dry-wet intensity ratio after immersion in the solvent, and the distribution evaluation of the blocked polyisocyanate in the structure sheet were evaluated according to the above-mentioned method. The plane direction and thickness direction), initial contact angle, hydrophobicity (water absorption time), and air permeation resistance were evaluated. The results are shown in Table 2. All of RB1 to SB3 were excellent in visual homogeneity, but except for RB2, it was found that the sheets were clearly inferior in water resistance and hydrophobicity to the above-mentioned SB1 to SB6. Further, in RB2, it took a long time of 420 seconds to obtain a self-supporting wet paper in the dehydration process by suction, and it was less than 60 seconds to obtain a self-supporting wet paper. It was found that there was a difficulty in productivity as compared with other examples and comparative examples.

[Comparative Example 4]
The dispersion SA1 in Example 7 was designated as RA3, and a foil-type structure RB4 was obtained. The average thickness in the plane direction and the height direction was measured with respect to RB4. In addition, the initial contact angle, the degree of hydrophobicity (water absorption time), and the air permeation resistance of the flat surface (bottom surface) were evaluated. The RB4 was a uniform and durable box in both the plane direction and the thickness direction, but even when immersed in water, swelling occurred clearly visually, and some structural collapse was observed, resulting in a structure with poor water resistance. It turned out to be.

Since the crosslinked structure obtained from the dispersion and the structure of the present disclosure has excellent moldability, mechanical strength, water resistance and solvent resistance at the same time, various containers for foods, daily necessities, etc. It can be suitably applied to a wide range of applications such as various containers used as stationery, packaging materials, packaging materials, board materials such as decorative boards, and interior products. In particular, when cellulose fiber is used as the organic fiber, it can be used as a material having high sustainable environmental compatibility.

Claims (17)

A method for producing a dispersion containing fine cellulose fibers, organic fibers, and blocked isocyanate.
A method comprising mixing fine cellulose fibers having an average fiber diameter of 2 nm or more and 1000 nm or less, organic fibers having an average fiber diameter of more than 3000 nm, block polyisocyanate, and water. The method according to claim 1, wherein the dispersion contains the blocked polyisocyanate in an amount of 0.1 parts by mass to 120 parts by mass with respect to 100 parts by mass of the fine cellulose fibers. The method according to claim 1 or 2, wherein the blocked polyisocyanate is a cationic blocked polyisocyanate. The mass ratio of the fine cellulose fibers to the organic fibers (fine cellulose fibers / organic fibers) in the dispersion is 0.2 / 99.8 to 30/70.
The method according to any one of claims 1 to 3, wherein the solid content ratio of the dispersion is 0.1% by mass to 55% by mass. The method according to any one of claims 1 to 4, wherein the organic fiber contains a fiber having at least a hydroxyl group and / or an amide group on the surface. The method according to any one of claims 1 to 5, wherein the organic fiber contains a cellulose fiber. The mixture according to any one of claims 1 to 6, wherein the mixing is carried out by mixing fine cellulose fibers, block polyisocyanate and water to prepare a premix, and then mixing the premix with organic fibers. The method described. The mixture according to any one of claims 1 to 7, wherein the mixing is carried out by mixing fine cellulose fibers, organic fibers and water to prepare a premix, and then mixing the premix with blocked polyisocyanate. The method described. The method according to any one of claims 1 to 8, wherein the mixing is carried out at a temperature of 5 ° C to 60 ° C. Dispersion preparation step, wherein the dispersion is prepared by the method according to any one of claims 1 to 9.
A structure comprising a concentration step of dehydrating the dispersion to form a hydrous concentrate, and a structure forming step of drying the hydrous concentrate at 80 ° C. or higher and 120 ° C. or lower to form a structure. Production method. A structure forming step of preparing a dispersion by the method according to any one of claims 1 to 9, and drying the dispersion at 80 ° C. or higher and 120 ° C. or lower to form a structure. A method of manufacturing a structure, including steps. The method according to claim 10 or 11, wherein the structure is a sheet or a molded product. The method according to any one of claims 10 to 12, wherein the blocked polyisocyanate is uniformly distributed in the structure. Dispersion preparation step, wherein the dispersion is prepared by the method according to any one of claims 1 to 9.
A concentration step in which the dispersion is dehydrated to form a hydrous concentrate, and the hydrous concentrate is dried at 80 ° C. or higher and 120 ° C. or lower, and the block in the block polyisocyanate is blocked following or at the same time as the drying. A crosslinked structure comprising a crosslinked structure forming step of crosslinking the blocked polyisocyanate with the fine cellulose fibers and / or the organic fibers by heating above the desorption temperature of the group to form a crosslinked structure. Production method. A dispersion preparation step of preparing a dispersion by the method according to any one of claims 1 to 9, and drying the dispersion at 80 ° C. or higher and 120 ° C. or lower, following the drying or with the drying. At the same time, by heating at a temperature higher than the desorption temperature of the blocking group in the blocked polyisocyanate, the blocked polyisocyanate and the fine cellulose fibers and / or the organic fibers are crosslinked to form a crosslinked structure. A method for producing a crosslinked structure, which comprises a step. The method according to claim 14 or 15, wherein the wet / dry strength ratio of the crosslinked structure is 0.4 to 1.2. The method according to any one of claims 14 to 16, wherein the heating is performed at a temperature of 130 ° C to 220 ° C.