Method for producing modified cellulose fiber filter cake

Abstract

The present invention relates to a method for producing a modified cellulose fiber filter cake, which comprises a step of subjecting a dispersion containing modified cellulose fibers to solid-liquid separation under the condition that the centrifugal force of a centrifuge is 50 G or more and 600 G or less. According to the present invention, a new method for producing a resin composition containing modified cellulose fibers, and a new method for producing a modified cellulose fiber filter cake, a short-fibered anionic modified cellulose fiber filter cake, a modified cellulose fiber, or a fine cellulose fiber that can be used in the production method can be provided.

Description

Technical Field

[0001] The invention relates to a method for preparing a modified cellulose fiber filter cake. Background Art

[0002] Conventionally, plastic materials derived from petroleum, which is a limited resource, have been widely used. However, in recent years, technologies that reduce the burden on the environment have attracted attention. Against this background, materials using cellulose fibers, which are biomass that exists in large quantities naturally, have attracted attention.

[0003] The dispersion of cellulose fibers has high viscosity, so if the dispersion of cellulose fibers is mixed with a coating material containing a resin, the viscosity increases significantly, making coating difficult. Therefore, a method of reducing the viscosity of the dispersion of cellulose fibers by shortening the fiber length of the cellulose fibers is known.

[0004] For example, as a method for short-fiberizing cellulose fibers, Patent Document 1 discloses a method of severing sugar chains of anion-modified cellulose fibers by thermally decomposing them with a solvent containing water.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: WO2019 / 235557 Summary of the invention

[0008] The present invention relates to the following [1] to [6].

[0009] [1] A method for producing a modified cellulose fiber cake, comprising the step of subjecting a dispersion containing modified cellulose fibers to solid-liquid separation under the condition that the centrifugal force of a centrifuge is 50 G or more and 600 G or less (step A).

[0010] [2] A method for producing a short-fibered anionically modified cellulose fiber filter cake, comprising: subjecting the anionically modified cellulose fibers to a thermal decomposition treatment at a temperature of 50° C. to 230° C. to obtain short-fibered anionically modified cellulose fibers; and

[0011] A step of subjecting the dispersion containing the short-fibered anionic-modified cellulose fibers to solid-liquid separation under the condition that the centrifugal force of a centrifuge is 50 G or more and 600 G or less (step A).

[0012] [3] A method for producing modified cellulose fibers, comprising: a step of introducing a modifying group into the modified cellulose fibers in the filter cake obtained by the production method described in [1] above, or into the short-fibered anionic modified cellulose fibers in the filter cake obtained by the production method described in [2] above.

[0013] [4] A method for producing fine cellulose fibers, wherein the average fiber length of the fine cellulose fibers is greater than 50 nm and less than 300 nm, the method comprising: a step of subjecting a modified cellulose fiber cake obtained by the production method described in [1] above, a short-fibered anionic modified cellulose fiber cake obtained by the production method described in [2] above, or a modified cellulose fiber obtained by the method described in [3] above to a micronizing process.

[0014] [5] A method for producing a resin composition, comprising: mixing a modified cellulose fiber cake produced by the production method described in [1] above, a short-fibered anionic modified cellulose fiber cake produced by the production method described in [2] above, a modified cellulose fiber produced by the method described in [3] above, or a fine cellulose fiber produced by the production method described in [4] above with a resin.

[0015] [6] A method for producing a resin composition, comprising: a step of mixing a modified cellulose fiber cake obtained by the production method described in [1] above or a short-fibered anionic modified cellulose fiber cake obtained by the production method described in [2] above, a modifying compound, and a resin. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a cross-sectional view of a decanter centrifuge. DETAILED DESCRIPTION

[0017] When a solvent containing water is used, it cannot be uniformly mixed with a resin used in a coating or the like, and therefore, the medium of the cellulose fibers needs to be replaced from water to an organic solvent. This is particularly evident in the case of short-fibered cellulose fibers.

[0018] In the process of replacing the solvent, the replacement process is usually carried out multiple times. Therefore, the amount of solvent used increases, which not only increases the cost of the solvent itself but also the cost of disposing of the solvent after use. Therefore, a more efficient method is sought.

[0019] Therefore, the present invention relates to a new method for producing a resin composition containing modified cellulose fibers, and in particular, a new method for producing a modified cellulose fiber cake, a short-fibered anionic modified cellulose fiber cake, a modified cellulose fiber, or a fine cellulose fiber that can be used in the production method.

[0020] According to the present invention, a more effective new method for producing a resin composition containing modified cellulose fibers, and in particular a more effective new method for producing a modified cellulose fiber cake, a short-fibered anionic modified cellulose fiber cake, a modified cellulose fiber, or a fine cellulose fiber that can be used in the production method can be provided.

[0021] [Method for producing modified cellulose fiber filter cake]

[0022] The method for producing a modified cellulose fiber cake of the present invention comprises a step of subjecting a dispersion containing modified cellulose fibers to solid-liquid separation under the condition that the centrifugal force of a centrifuge is 50 G to 600 G (step A).

[0023] [Modified cellulose fiber]

[0024] Modified cellulose fibers can be obtained by using cellulose fibers as raw materials, introducing substituents for modification, preferably anionic groups, by known methods, and then shortening the fibers. Cellulose fibers used as raw materials are preferably natural cellulose fibers from environmental perspectives, and examples thereof include wood pulps such as coniferous tree pulp and broadleaf tree pulp; cotton pulps such as cotton lint and lint; non-wood pulps such as straw pulp and bagasse pulp; bacterial cellulose, etc. As substituents, anionic groups are preferred, and as anionic groups, from the perspective of sugar chain severance efficiency, carboxyl groups, sulfonic acid groups, and phosphoric acid groups are preferred, and carboxyl groups are more preferred.

[0025] In addition, the carboxymethylated pulp can be mechanically defibrated, beated, and dissociated in advance, and used as modified cellulose fiber at the stage where the average fiber diameter is 500 nm or more. However, from the viewpoint of the dispersibility of the composition, it is preferred to perform short fiberization. As a treatment method, for example, the water dispersion of the above-mentioned pulp can be preliminarily subjected to a high concentration (more than 20% by weight) by dehydration or the like, and then subjected to a beating treatment; the water dispersion can be subjected to a low concentration (less than 20% by weight) and then subjected to a mechanical treatment such as beating or dissociation; or the water dispersion can be dehydrated and dried, and then subjected to a mechanical defibration or beating treatment, or dry pulverization, etc.

[0026] As a known embodiment for producing anionic modified cellulose fibers, a method using 2,2,6,6,-tetramethyl-1-piperidine-N-oxide (TEMPO) as a catalyst as described in WO2019 / 235557 can be cited. In this production method, natural cellulose fibers are preferably used as raw cellulose fibers, and TEMPO is used as a catalyst, thereby introducing carboxyl groups as anionic groups into cellulose fibers.

[0027] [Short Fibrosis]

[0028] By subjecting the cellulose fibers to a cleavage treatment of sugar chains, the anionically modified cellulose fibers can be shortened.

[0029] As a method for cutting sugar chains, short-fibered anionic modified cellulose fibers can be obtained by subjecting anionic modified cellulose fibers to a thermal decomposition treatment preferably at a temperature of 50° C. or higher and preferably at a temperature of 230° C. or lower. The temperature conditions are preferably 70° C. or higher, and more preferably 80° C. or higher, from the viewpoint of productivity, and more preferably 220° C. or lower, and more preferably 200° C. or lower, from the viewpoint of suppressing excessive decomposition.

[0030] The modified cellulose fibers thus obtained and used in step A are pre-fiberized modified cellulose fibers, preferably pre-fiberized anionic modified cellulose fibers. The average fiber length of the pre-fiberized modified cellulose fibers thus obtained is preferably 50 μm or more, more preferably 150 μm or more, from the viewpoint of productivity, and is preferably 500 μm or less, more preferably 300 μm or less, from the viewpoint of dispersibility of the modified cellulose fibers in the resin composition.

[0031] Therefore, a preferred embodiment of the method for producing a modified cellulose fiber filter cake of the present invention is the following method for producing a short-fibered anionic modified cellulose fiber filter cake, which comprises:

[0032] A step of obtaining short-fibered anionically modified cellulose fibers by subjecting the anionically modified cellulose fibers to a thermal decomposition treatment at a temperature of 50° C. to 230° C.; and

[0033] A step of subjecting the dispersion containing the short-fibered anionic-modified cellulose fibers to solid-liquid separation under the condition that the centrifugal force of a centrifuge is 50 G or more and 600 G or less (step A).

[0034] The thermal decomposition treatment is carried out in a state where anionic denatured cellulose fibers are mixed or dispersed in a medium. As the medium preferably used, water, N,N-dimethylformamide (DMF), ethanol, isopropyl alcohol (IPA), methyl ethyl ketone (MEK), ethyl acetate, toluene, cyclohexanone, etc. can be listed, and one of them or two or more of them can be used in combination. Among them, from the viewpoint of operability and cost, a solvent containing water is preferred. In a solvent containing water, the proportion of water in the solvent is preferably 50% by mass or more, more preferably 80% by mass or more, further preferably 95% by mass or more, and further preferably 100% by mass, from the viewpoint of operability and cost.

[0035] [Process A]

[0036] The modified cellulose fiber dispersion thus obtained can be used in step A. The modified cellulose fibers provided in step A are preferably anionic modified cellulose fibers, more preferably anionic modified cellulose fibers subjected to TEMPO oxidation treatment, and even more preferably anionic modified cellulose fibers subjected to TEMPO oxidation treatment and short-fiberized.

[0037] As the medium used in the dispersion, water, N,N-dimethylformamide (DMF), ethanol, isopropanol (IPA), methyl ethyl ketone (MEK), ethyl acetate, toluene, cyclohexanone, etc. can be preferably listed, and one of them or two or more can be used in combination. Among them, from the viewpoint of operability and cost, it is preferably a solvent comprising water. In the solvent comprising water, the proportion of water in the solvent is preferably 50% by mass or more, more preferably 80% by mass or more, more preferably 95% by mass or more, and more preferably 100% by mass from the viewpoint of operability and cost.

[0038] The content of the modified cellulose fiber in the dispersion is obtained as the solid content. From the viewpoint of productivity, the solid content in the dispersion is preferably 0.1% by mass or more, more preferably 1.0% by mass or more, and even more preferably 5.0% by mass or more. On the other hand, although the upper limit is not particularly limited, from the viewpoint of handleability, it is preferably 80% by mass or less, more preferably 60% by mass or less, and even more preferably 40% by mass or less.

[0039] The content of the modified cellulose fibers in the dispersion was measured by the method described in the examples described later.

[0040] In step A, solid-liquid separation of the dispersion containing modified cellulose fibers is performed using a centrifuge.

[0041] From the viewpoint of reducing the water concentration in the resin composition, the centrifugal force of the centrifuge is 50 G or more, preferably 80 G or more, and more preferably 200 G or more. On the other hand, from the viewpoint of discharging the cellulose fiber cake out of the centrifuge, the centrifugal force is 600 G or less, preferably 550 G or less, and more preferably 400 G or less.

[0042] In the present specification, the centrifugal force of the centrifuge can be set to a desired level by adjusting the rotation speed of the drum.

[0043] As the centrifuge that can be used in step A, various types of known centrifuges can be used. In addition, a centrifuge that operates intermittently or a continuous centrifuge that can operate continuously can be used, but a continuous centrifuge is preferred from the viewpoint of operating efficiency.

[0044] Specific examples of centrifuges that can be used in step A include intermittent centrifuges such as siphon type, basket type, and separation plate type centrifuges. Continuous centrifuges include decanter type, decone type, multistage type, and separation plate type centrifuges. Among these, from the viewpoint of operating efficiency, multistage type centrifuges are preferred, decone type and decanter type centrifuges are more preferred, and decanter type centrifuges are further preferred.

[0045] Figure 1 It is a diagram schematically showing a cross section of a decanter centrifuge.

[0046] For example, in the case of a dispersion containing short-fibered anionic modified cellulose fibers as modified cellulose fibers, it is supplied to a decanting centrifuge as a supply slurry 1. In the decanting centrifuge, centrifugal force can be applied to the dispersion by rotating the drum 2, and the solid and liquid in the dispersion can be separated. In addition, the dispersion containing an increased content of short-fibered anionic modified cellulose fibers is slowly transferred to the filter cake discharge port by rotating the screw 3 at a speed slightly slower than that of the drum, and recovered as a filter cake 4. On the other hand, the dispersion after most of the fiber components are removed is recovered as a separated liquid 5.

[0047] The supply flow rate of the supplied slurry 1 can be set to a desired level by, for example, connecting a supply pump (not shown) to a decanter centrifuge.

[0048] For example, the supply flow rate of the supply slurry 1 when using a decanting centrifuge is preferably 500L / h or less, more preferably 300L / h or less, and further preferably 100L / h or less from the viewpoint of extending the residence time of the supply slurry in the device to improve the separability and avoid the cellulose fibers from flowing out into the separation liquid. On the other hand, from the viewpoint of improving productivity, it is preferably 100L / h or more, more preferably 300L / h or more, and further preferably 500L / h or more. In addition, the above-mentioned preferred range can be appropriately changed according to the size of the device.

[0049] By using the centrifugal separator as described above, solid-liquid separation of the dispersion can be achieved, and a modified cellulose fiber cake can be produced.

[0050] In this specification, "solid-liquid separation" refers to removing the solvent component in the dispersion of modified cellulose fibers to increase the content of modified cellulose fibers. Since the concentration of modified cellulose fibers or modified cellulose fibers in the resin composition can be increased, the solid content in the filter cake after solid-liquid separation is preferably more, specifically, preferably 5% by mass or more, more preferably 9% by mass or more, more preferably 15% by mass or more, and more preferably 20% by mass or more. On the other hand, from the viewpoint of handleability, the solid content is preferably 80% by mass or less, more preferably 60% by mass or less, and more preferably 40% by mass or less.

[0051] [transsexual]

[0052] The modified cellulose fiber filter cake obtained by the manufacturing method of the present invention can be directly incorporated into the resin because the moisture content is fully reduced. In addition, the denaturation in the modified cellulose fiber filter cake here can use various substituents, preferably denaturation by anionic groups. In addition, it is also possible to carry out a process of shortening the chain length of the modified cellulose fiber in advance. In addition, it is also possible to further bond the modifying groups to the cellulose fiber filter cake that has been short-fibered and anion-modified to make modified cellulose fibers. It is also possible to incorporate it into the resin after such treatment. In addition, it is also possible to further refine the short-fibered anion-modified cellulose fiber filter cake or the modified cellulose fiber and incorporate it into the resin.

[0053] On the other hand, in the production method of the present invention, carboxylated (oxidized) cellulose may be used as chemically modified cellulose. For example, cellulose raw material may be reacted with a cationizing agent such as glycidyltrimethylammonium chloride, 3-chloro-2-hydroxypropyltrialkylammonium hydride or a halohydrin type thereof and an alkali metal hydroxide (sodium hydroxide, potassium hydroxide, etc.) as a catalyst in the presence of water or an alcohol having 1 to 4 carbon atoms to obtain cationically modified cellulose.

[0054] [Method for producing modified cellulose fibers]

[0055] The modified cellulose fiber of the present invention can be produced by a known method. The modified cellulose fiber is a cellulose fiber derivative in which a modifying group is further bonded to a denatured cellulose fiber.

[0056] More specifically, a compound having a desired modifying group (modifying compound) is reacted with the modified cellulose fibers or short-fibered anionic modified cellulose fibers in the filter cake obtained by the above-mentioned production method of the present invention to introduce the modifying group into the cellulose fibers, thereby obtaining modified cellulose fibers.

[0057] When the bonding mode between the modified cellulose fiber and the modifying compound is an ionic bond, the modifying compound may include primary amines, secondary amines, tertiary amines, quaternary ammonium compounds, phosphonium compounds, etc. In these compounds, various hydrocarbon groups such as chain saturated hydrocarbon groups, chain unsaturated hydrocarbon groups, cyclic saturated hydrocarbon groups, and aromatic hydrocarbon groups, or copolymerization sites, etc. may be introduced as modifying groups. These groups or sites may be introduced alone or in combination of two or more.

[0058] When the bonding mode is a covalent bond, an appropriate modifying compound is used according to the modified anionic group or modified hydroxyl group. In the case of modifying anionic groups, for example, primary amines and secondary amines are preferably used as modifying compounds, for example, via amide bonds. In the case of modifying via ester bonds, alcohols such as butanol, octanol and dodecanol are preferably used as modifying compounds. In the case of modifying via urethane bonds, isocyanate compounds are preferably used as modifying compounds. In these compounds, various hydrocarbon groups such as chain saturated hydrocarbon groups, chain unsaturated hydrocarbon groups, cyclic saturated hydrocarbon groups and aromatic hydrocarbon groups, or copolymerization sites, etc. can be introduced as modifying groups. These groups or sites can be introduced alone or in combination with more than two kinds.

[0059] In the case of modifying a hydroxyl group, for example, when modified via an ester bond, it is preferred to use, as a modifying compound, for example, anhydrides (such as acetic anhydride, propionic anhydride), acyl halides (such as octanoyl chloride, lauroyl chloride and stearyl chloride). In the case of modifying via an ether bond, as a modifying compound, it is preferred that, for example, epoxy compounds (such as oxiranes and alkyl glycidyl ethers), alkyl halides and their derivatives (such as methyl chloride, ethyl chloride and chlorooctadecane) are used. In the case of modifying via an urethane bond, it is preferred to use, for example, an isocyanate compound as a modifying compound. In these compounds, various hydrocarbon groups such as chain saturated hydrocarbon groups, chain unsaturated hydrocarbon groups, cyclic saturated hydrocarbon groups and aromatic hydrocarbon groups, or copolymerization sites, etc., can be introduced as modifying groups. These groups or sites can be introduced alone or in combination with two or more.

[0060] [Method for producing fine cellulose fibers]

[0061] The modified cellulose fiber filter cake, short-fibered anionic modified cellulose fiber filter cake or modified cellulose fiber obtained by the manufacturing method of the present invention can be further subjected to micronization treatment as required and used as nano-scale micro-cellulose fibers (nanofibers). As further micronization treatment, mechanical micronization treatment using a dissociator, a beater, a low-pressure homogenizer, a high-pressure homogenizer, a grinder, a cutting mill, a ball mill, a jet mill, a short-shaft extruder, a double-shaft extruder, an ultrasonic mixer, a household juicer, etc. can be cited.

[0062] By nanofibrillating the modified cellulose fibers obtained by the production method of the present invention, fine cellulose fibers having an average fiber length of preferably 50 nm to 300 nm and an average fiber diameter of preferably 2 nm to 10 nm can be obtained. The average fiber length, average fiber diameter, and average aspect ratio of such fine cellulose fibers can be measured using an atomic force microscope (AFM, Nanoscope III Tapping mode AFM, manufactured by Digital Instrument Corporation, using a Point Probe (NCH) manufactured by NANOSENSORS).

[0063] [Method for producing resin composition]

[0064] The cellulose fibers can be produced by mixing various cellulose fibers obtained by the above-mentioned method (ie, the modified cellulose fiber cake, the short-fibered anionic modified cellulose fiber cake, the modified cellulose fibers, and the fine cellulose fibers) with various resins, solvents, and further optional components.

[0065] From the perspective of efficiencies in the operation process, the modification treatment of (preferably anionic) modified cellulose fibers, more preferably short-fibered modified cellulose fibers, and the mixing with the resin can be performed simultaneously. In this case, a method for producing a resin composition comprising the steps of mixing the modified cellulose fiber cake obtained by the above-mentioned production method of the present invention, the short-fibered anionic modified cellulose fiber cake, the modifying compound and the resin is provided, and a micronization treatment can also be performed thereafter.

[0066] The content of the cellulose fiber (converted amount) in the resin composition is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, more preferably 1% by mass or more, and more preferably 3% by mass or more, from the viewpoint of suppressing the shrinkage during solidification of the resin containing the cellulose fiber from which the solvent component is removed from the resin composition, and imparting mechanical strength. On the other hand, from the viewpoint of avoiding the reduction of the handleability caused by the viscosity increase of the resin composition, it is preferably 20% by mass or less, more preferably 15% by mass or less, and more preferably 8% by mass or less.

[0067] In addition, cellulose fiber (converted amount) means the mass obtained by subtracting the mass of the modifying group from the mass of various cellulose fibers (i.e., modified cellulose fibers and fine cellulose fibers) to which the modifying group is bonded. The cellulose fiber (converted amount) among various cellulose fibers to which the modifying group is bonded can be measured by the method described in the Examples described later.

[0068] The resin that can be used in the resin composition is not particularly limited as long as it is a resin that has been conventionally used as a base resin for non-aqueous coating materials, and various resins can be blended.

[0069] Specific examples of the resin include alkyd resins, acrylic resins, acrylic urethane resins, melamine resins, polyurethane resins, epoxy resins, coumarone resins, urea resins, phenolic resins, vinyl chloride resins, phenoxy resins, silicone resins, fluororesins, nylon resins, styrene butadiene resins, nitrile butadiene resins, petroleum resins, rosin, drying oils, boiling oils, acetyl cellulose, nitrocellulose, and the like. Among them, acrylic resins, acrylic urethane resins, melamine resins, polyurethane resins, epoxy resins, urea resins, and phenolic resins are preferred, and epoxy resins and phenolic resins are more preferred, because a resin composition having excellent dispersibility of fine cellulose fibers can be obtained.

[0070] The content of the resin in the resin composition is preferably 1% by mass or more, more preferably 10% by mass or more, and further preferably 40% by mass or more from the viewpoint of production efficiency. On the other hand, from the viewpoint of low viscosity, it is preferably 90% by mass or less, more preferably 70% by mass or less, and further preferably 50% by mass or less.

[0071] The resin composition may further contain a solvent as necessary. Examples of the solvent in the present invention include organic solvents and organic media containing a reactive functional group.

[0072] Examples of the organic solvent include alcohols such as methanol, ethanol, isopropanol, 2-butanol, 1-pentanol, octanol, glycerol, ethylene glycol, and propylene glycol; carboxylic acids such as acetic acid; hydrocarbons such as hexane, heptane, octane, decane, and liquid paraffin; aromatic hydrocarbons such as toluene and xylene; amides such as dimethyl sulfoxide, N,N-dimethylformamide, dimethylacetamide, and acetanilide; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; and halogens such as dichloromethane and chloroform. Carbonates such as ethylene carbonate, propylene carbonate, dimethyl carbonate, and diethyl carbonate; esters such as methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl butyrate, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene sorbitol fatty acid esters, glycerol fatty acid esters, and polyoxyethylene fatty acid esters; polyethers such as polyethylene glycol and polyoxyethylene alkyl ether; silicone oils such as polydimethylsiloxane; acetonitrile, propionitrile, ester oil, salad oil, soybean oil, castor oil, etc. These can be used alone or in combination of two or more.

[0073] In addition, as organic media containing reactive functional groups, for example, there can be listed: acrylates such as methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, n-hexyl acrylate, n-hexyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, and phenyl glycidyl ether acrylate; polyurethane prepolymers such as hexamethylene diisocyanate polyurethane prepolymer, phenyl glycidyl ether acrylate toluene diisocyanate polyurethane prepolymer; glycidyl ethers such as n-butyl glycidyl ether, 2-ethylhexyl glycidyl ether, stearic acid glycidyl ether, styrene oxide, phenyl glycidyl ether, nonylphenyl glycidyl ether, butylphenyl glycidyl ether, 1,6-hexanediol diglycidyl ether, ethylene glycol diglycidyl ether, and diethylene glycol diglycidyl ether; chlorostyrene, methoxystyrene, butoxystyrene, vinyl benzoic acid, etc.

[0074] When a solvent is used, the amount of the solvent is preferably 50 parts by mass or more, more preferably 100 parts by mass or more, based on 100 parts by mass of the resin, from the viewpoint of lowering the viscosity and uniform mixing of the resin and the anionic modified cellulose fiber cake. On the other hand, from the viewpoint of production efficiency, the amount is preferably 200 parts by mass or less, more preferably 100 parts by mass or less, based on 100 parts by mass of the resin.

[0075] The resin composition may further contain additives commonly used in the field of coatings. Examples of such additives include inorganic pigments, organic pigments, dyes, curing agents, plasticizers, catalysts, mildew inhibitors, defoamers, leveling agents, pigment dispersants, sedimentation inhibitors, anti-sagging agents, tackifiers, matting agents, light stabilizers, ultraviolet absorbers, and the like.

[0076] In relation to the above-mentioned embodiment, the present invention further discloses the following method for producing a filter cake, a method for producing modified cellulose fibers, a method for producing fine cellulose fibers, and a method for producing a resin composition.

[0077] <1> A method for producing a modified cellulose fiber filter cake comprises: a step (step A) of subjecting a dispersion containing modified cellulose fibers to solid-liquid separation under the condition that the centrifugal force of a centrifuge is 50 G or more and 600 G or less.

[0078] <2> As mentioned above <1> The production method, wherein the solid content of the modified cellulose fiber filter cake is 5% by mass or more.

[0079] <3> As mentioned above <1> or <2> In the manufacturing method, the centrifuge is a continuous centrifuge.

[0080] <4> As mentioned above <3> In the manufacturing method, the continuous centrifuge is a decanting centrifuge.

[0081] <5> As mentioned above <4> In the production method, the flow rate of supplying the modified cellulose fiber slurry to the decanter centrifuge is 100 L / h to 500 L / h.

[0082] <6> As mentioned above <1> to <5> The production method described in any one of the above, wherein the denaturation of the denatured cellulose fibers is anionic denaturation.

[0083] <7> As mentioned above <1> to <6> The production method according to any one of the preceding claims, wherein the modified cellulose fibers to be subjected to step A are in the form of modified cellulose fibers that have been previously short-fiberized.

[0084] <8> As mentioned above <7> The production method is characterized in that the average fiber length of the modified cellulose fibers that have been pre-fiberized is 50 μm to 500 μm.

[0085] <9> As mentioned above <1> to <8> The production method described in any one of the above aspects, wherein the dispersion in step A is a medium containing water.

[0086] <10> A method for producing a short-fibered anionically modified cellulose fiber filter cake, comprising: subjecting the anionically modified cellulose fibers to a thermal decomposition treatment at a temperature of 50° C. to 230° C. to obtain short-fibered anionically modified cellulose fibers; and

[0087] A step of subjecting the dispersion containing the short-fibered anionic-modified cellulose fibers to solid-liquid separation under the condition that the centrifugal force of a centrifuge is 50 G or more and 600 G or less (step A).

[0088] <11> As mentioned above <10> In the production method, the medium in the thermal decomposition treatment is a medium containing water.

[0089] <12> As mentioned above <10> or <11> In the production method, the dispersion in step A is a medium containing water.

[0090] <13> A method for producing modified cellulose fiber, comprising: <1> to <9> A step of introducing a modifying group into the modified cellulose fibers in the filter cake obtained by any one of the production methods.

[0091] <14> A method for producing modified cellulose fiber, comprising: <10> to <12> A step of introducing modifying groups into the short-fibered anionic modified cellulose fibers in the filter cake obtained by any one of the production methods.

[0092] <15> A method for producing fine cellulose fibers, wherein the average fiber length of the fine cellulose fibers is 50 nm or more and 300 nm or less, the method comprising: <1> to <9> A step of subjecting the modified cellulose fiber cake obtained by any one of the production methods to micronization.

[0093] <16> A method for producing fine cellulose fibers, wherein the average fiber length of the fine cellulose fibers is 50 nm or more and 300 nm or less, the method comprising: <10> to <12> A step of subjecting the short-fibered anionic denatured cellulose fiber cake obtained by any one of the production methods to micronization.

[0094] <17> A method for producing fine cellulose fibers, wherein the average fiber length of the fine cellulose fibers is 50 nm or more and 300 nm or less, the method comprising: <13> or <14> The modified cellulose fibers obtained by the method are subjected to a micronization process.

[0095] <18> A method for producing a resin composition, comprising: <1> to <9> A step of mixing the modified cellulose fiber cake obtained by any one of the production methods with a resin.

[0096] <19> A method for producing a resin composition, comprising: <10> to <12> The step of mixing the short-fibered anionic modified cellulose fiber cake obtained by any one of the production methods with a resin.

[0097] <20> A method for producing a resin composition, comprising: <13> or <14> The invention relates to a process for mixing the modified cellulose fiber obtained by the method with a resin.

[0098] <21> A method for producing a resin composition, comprising: <15> to <17> A step of mixing the fine cellulose fibers obtained by any one of the production methods with a resin.

[0099] <22> A method for producing a resin composition, comprising: <1> to <9> A step of mixing the modified cellulose fiber cake obtained by any one of the production methods, a modifying compound, and a resin.

[0100] <23> A method for producing a resin composition, comprising: <10> to <12> A step of mixing the short-fibered anionic modified cellulose fiber cake obtained by any one of the production methods, a modifying compound, and a resin.

[0101] <24> As mentioned above <18> to <23> The method for producing a resin composition according to any one of the above aspects, wherein the content of the cellulose fibers (in terms of amount) in the resin composition is 0.1% by mass or more and 20% by mass or less.

[0102] <25> As mentioned above <18> to <24> The method for producing a resin composition according to any one of the preceding claims, wherein the resin is selected from any one or more of acrylic resins, acrylic urethane resins, melamine resins, polyurethane resins, epoxy resins, urea resins, and phenolic resins.

[0103] <26> As mentioned above <18> to <25> The method for producing a resin composition according to any one of the above aspects, wherein the resin composition further contains a solvent.

[0104] Example

[0105] The present invention is specifically described below with reference to the examples. The examples are merely illustrative of the present invention and do not limit the present invention in any way. Parts in the examples are parts by mass unless otherwise specified. "Normal pressure" means 101.3 kPa, and "normal temperature" means 25°C.

[0106] 〔Average fiber length of various cellulose fibers〕

[0107] Add ion exchange water to the cellulose fiber to be measured to prepare a dispersion with a content of 0.01% by mass. Use a wet dispersion type image analysis particle size distribution meter (manufactured by JASCO International Co., Ltd., trade name: IF-3200) to measure the dispersion under the conditions of front lens: 2 times, telecentric zoom lens: 0.75 times, image resolution: 1.113μm / pixel, syringe inner diameter: 6515μm, gasket thickness: 1000μm, image recognition mode: Ghost, threshold: 6, analysis sample volume: 300mL, sampling: 3%. Measure more than 10,000 cellulose fibers, and calculate their average ISO fiber length as the average fiber length.

[0108] [Anionic group content of anionic modified cellulose fibers and short-fibered anionic modified cellulose fibers]

[0109] Take 0.5g of the dry mass of the cellulose fiber of the object to be measured into a 100mL beaker, add ion exchange water or a mixed solvent of methanol / water = 2 / 1, and make a total of 55mL. Add 5mL of 0.01M sodium chloride aqueous solution to it to prepare a dispersion. Stir the dispersion until the cellulose fibers are fully dispersed. Add 0.1M hydrochloric acid to the dispersion and adjust the pH to 2.5-3. Use an automatic titrator (made by DKK-TOA Corporation, trade name: AUT-701) to drop 0.05M sodium hydroxide aqueous solution into the dispersion with a waiting time of 60 seconds, and measure the conductivity and pH values ​​every 1 minute. Continue to measure until the pH is about 11 to obtain a conductivity curve. Calculate the sodium hydroxide titration amount from the conductivity curve, and calculate the anionic group content of the cellulose fiber of the object to be measured by the following formula.

[0110] Anionic group content (mmol / g) = sodium hydroxide titration × sodium hydroxide aqueous solution concentration (0.05M) / mass of cellulose fiber to be measured (0.5g)

[0111] [Solid content in various suspensions or filter cakes after solid-liquid separation]

[0112] The measurement was performed using a halogen moisture meter (manufactured by Shimadzu Corporation, trade name: MOC-120H). Specifically, 1 g of the sample was measured every 30 seconds at a constant temperature of 150°C, and the value when the mass loss reached 0.1% or less was defined as the solid content.

[0113] [Amount of cellulose fibers in various cellulose fibers to which modifying groups are bonded (converted amount)]

[0114] The amount (converted amount) of cellulose fibers in various cellulose fibers to which a modifying group is bonded is the amount of cellulose fibers after removing the modifying group from the various cellulose fibers to which a modifying group is bonded.

[0115] The amount (converted amount) of cellulose fibers in various cellulose fibers to which a modifying group is bonded is measured by the following method.

[0116] (1) When there is only one "modifying compound" added

[0117] The cellulose fiber amount (converted amount) was calculated by the following formula E.

[0118] <Formula E>

[0119] Cellulose fiber amount (converted amount) (g) = mass of various cellulose fibers to which the modifying groups are bonded (g) / [1 + modifying compound (g / mol) × bonding amount of the modifying group (mmol / g) × 0.001]

[0120] (2) When there are two or more "modifying compounds" added

[0121] The amount of cellulose fibers (converted amount) was calculated by taking into account the molar ratio of each compound (that is, the molar ratio when the total molar amount of the added compounds is taken as 1).

[0122] [Preparation of anionic modified cellulose fibers]

[0123] Preparation Example 1 (oxidized pulp of broadleaf trees)

[0124] First, 100 g of natural cellulose fiber was fully stirred with 9900 g of ion exchange water, and then 1.6 g of TEMPO, 10 g of sodium bromide, and 28.4 g of sodium hypochlorite were added to 100 g of the pulp mass. A constant pH titration (pH stud titration) was performed using an automatic titrator (manufactured by DKK-TOA Corporation, trade name: AUT-701), and 0.5 M sodium hydroxide was added dropwise to maintain the pH at 10.5. After reacting for 60 minutes (20°C), the addition was stopped to obtain anion-modified cellulose fiber. Dilute hydrochloric acid was added to the obtained anion-modified cellulose fiber to convert the counter ion from sodium ion to proton, and then the fiber was fully washed with ion exchange water, followed by dehydration to obtain anion-modified cellulose fiber with a solid content of 30.1% by mass. The average fiber length of the anion-modified cellulose fiber was 1003 μm, and the carboxyl content was 1.3 mmol / g.

[0125] Details of the raw materials and the like used in Production Example 1 are shown below.

[0126] Natural cellulose fiber: bleached kraft pulp from eucalyptus hardwood (manufactured by CENIBRA)

[0127] TEMPO: Made by ALDRICH, free radical, 98% by mass

[0128] Sodium hypochlorite: Made by Wako Pure Chemical Industries, Ltd.

[0129] Sodium bromide: Made by Wako Pure Chemical Industries, Ltd.

[0130] Example 1

[0131] In a reaction tank with an anchor paddle, 4.15 kg of the anionically modified cellulose fibers obtained in Preparation Example 1 were added in terms of absolute dry weight, and ion exchange water was added until the mass of the treated liquid reached 25 kg. The treated liquid was stirred at 95° C. under normal pressure for 12 hours to react, thereby obtaining an aqueous suspension of short-fibered anionically modified cellulose fibers. The average fiber length of the short-fibered anionically modified cellulose fibers was 157 μm.

[0132] The obtained aqueous suspension of short-fibered anionic modified cellulose fibers was supplied to a decanting centrifuge and continuously operated with a centrifugal force of 300G and a supply flow rate of 500L / h to the decanter, thereby performing solid-liquid separation. When a stable state was reached, a filter cake with a solid content of 22.9% by mass was obtained.

[0133] 12.92 g of acetone and 0.56 g of polyether monoamine were added to 3.60 g of the obtained filter cake, and the mixture was stirred at room temperature for 30 minutes to obtain an acetone dispersion of modified cellulose fibers (hereinafter referred to as CNF) in which EOPO groups were bonded to the carboxyl groups of short-fibered anionic modified cellulose fibers via ionic bonds. The EOPO group refers to a group having a structure in which ethylene oxide (EO) and propylene oxide (PO) are polymerized in a random or block form.

[0134] 12.92 g of bisphenol A type liquid epoxy resin was added to the CNF dispersion and stirred at room temperature for 30 minutes to prepare a coating as a resin composition. The mass ratio of epoxy resin to acetone in the coating was 1:1, and the content of CNF in the coating was 6 mass %.

[0135] Details of the raw materials and the like used in Example 1 are as follows.

[0136] Polyether monoamine: Jeffamine M-2070 (manufactured by HUNTSMAN, EO / PO (molar ratio) 32 / 10, molecular weight 2000)

[0137] Bisphenol A type liquid epoxy resin: jER828 (manufactured by Mitsubishi Chemical Corporation, molecular weight 370)

[0138] Example 2

[0139] A filter cake having a solid content of 17.3% by mass was obtained in the same manner as in Example 1 except that the solid-liquid separation was carried out under the conditions of a centrifugal force of 100 G and a supply flow rate to the decanter of 100 L / h.

[0140] To 3.18 g of the obtained filter cake were added 13.22 g of acetone and 0.37 g of the above-mentioned polyether monoamine to obtain a dispersion of the CNF.

[0141] 13.22 g of the bisphenol A type liquid epoxy resin was added to the CNF dispersion and stirred at room temperature for 30 minutes to prepare a coating. The mass ratio of epoxy resin to acetone in the coating was 1:1, and the content of CNF in the coating was 4 mass %.

[0142] Example 3

[0143] A filter cake having a solid content of 23.5% by mass was obtained in the same manner as in Example 2 except that the solid-liquid separation was carried out under the condition of a centrifugal force of 400 G.

[0144] To 3.52 g of the obtained filter cake were added 12.96 g of acetone and 0.56 g of the above-mentioned polyether monoamine to obtain a dispersion of the CNF.

[0145] 12.96 g of the bisphenol A type liquid epoxy resin was added to the CNF dispersion and stirred at room temperature for 30 minutes to prepare a coating. The mass ratio of epoxy resin to acetone in the coating was 1:1, and the content of CNF in the coating was 6 mass %.

[0146] Example 4

[0147] A filter cake having a solid content of 20.1% by mass was obtained in the same manner as in Example 2 except that the solid-liquid separation was carried out under the condition of a centrifugal force of 500 G.

[0148] To 3.42 g of the obtained filter cake were added 13.06 g of acetone and 0.46 g of the above-mentioned polyether monoamine to obtain a dispersion of the CNF.

[0149] 13.06 g of the bisphenol A type liquid epoxy resin was added to the CNF dispersion and stirred to prepare a coating. The mass ratio of the epoxy resin to acetone in the coating was 1:1, and the content of CNF in the coating was 5 mass %.

[0150] Example 5

[0151] A filter cake having a solid content of 12.1% by mass was obtained in the same manner as in Example 1 except that the supply amount of the short-fibered anionic modified cellulose fibers having a different average chain length and the aqueous suspension thereof was changed to carry out solid-liquid separation.

[0152] To 3.37 g of the obtained filter cake were added 13.18 g of acetone and 0.27 g of the above-mentioned polyether monoamine to obtain a dispersion of the CNF.

[0153] 13.18 g of the bisphenol A type liquid epoxy resin was added to the CNF dispersion and stirred to prepare a coating. The mass ratio of the epoxy resin to acetone in the coating was 1:1, and the content of CNF in the coating was 3 mass %.

[0154] Example 6

[0155] A filter cake having a solid content of 13.1% by mass was obtained in the same manner as in Example 5 except that the solid content (% by mass) in the aqueous suspension of the short-fibered anionic denatured cellulose fibers was changed to 2% by mass.

[0156] To 3.14 g of the obtained filter cake were added 13.29 g of acetone and 0.28 g of the above-mentioned polyether monoamine to obtain a dispersion of the CNF.

[0157] 13.29 g of the bisphenol A type liquid epoxy resin was added to the CNF dispersion and stirred to prepare a coating. The mass ratio of the epoxy resin to acetone in the coating was 1:1, and the content of CNF in the coating was 3 mass %.

[0158] Comparative Example 1

[0159] By the same method as in Example 1, an aqueous suspension of short-fibered anionic modified cellulose fibers was obtained.

[0160] Without performing solid-liquid separation of the aqueous suspension, 12.39 g of acetone and 0.17 g of the polyether monoamine were added to 5.06 g of an aqueous suspension of short-fibered anionic denatured cellulose fibers (solid content: 5.0 mass %) to obtain a CNF dispersion.

[0161] 12.39 g of the bisphenol A type liquid epoxy resin was added to the CNF dispersion and stirred at room temperature for 30 minutes to prepare a coating. The mass ratio of epoxy resin to acetone in the coating was 1:1, and the content of CNF in the coating was 2 mass %.

[0162] Comparative Example 2

[0163] Solid-liquid separation was attempted in the same manner as in Example 2 except that the solid-liquid separation was carried out under the condition of a centrifugal force of 700 G. However, no filter cake was discharged from the decanter centrifuge.

[0164] Comparative Example 3

[0165] Solid-liquid separation was attempted in the same manner as in Example 2 except that the solid-liquid separation was carried out under the condition of a centrifugal force of 3100 G. However, no filter cake was discharged from the decanter centrifuge.

[0166] The specifications of the decanting centrifuges used in the above-mentioned embodiments and comparative examples are as follows. The main components of the decanting centrifuges are basically the same as those of Figure 1 Consistent.

[0167] Machine name: Decantation centrifuge

[0168] Model: PTM006 (manufactured by Basara Industry Co., Ltd.)

[0169] Main motor: 3.7kW, 200V, 13.8A, INV

[0170] Differential motor: 1.5kW, 200V, 6.0A, INV

[0171] Maximum centrifugal force: 3100G

[0172] The specifications of the supply pump used in the above-mentioned Examples and Comparative Examples for supplying the aqueous suspension to the decanter type centrifuge are as follows.

[0173] Machine name: HEISHIN MOHNO pump

[0174] Model: NHL15PUN (manufactured by Hyoshin Equipment Co., Ltd.)

[0175] Motor: 0.2kW, 200V, 1.5A, INV

[0176] Maximum supply flow: 800L / h

[0177] The dischargeability of the filter cake from the decanter centrifuge was evaluated based on the following criteria.

[0178] Dischargeability ⊚: When the cake was continuously discharged from the cake discharge port, the dischargeability was evaluated as ⊚.

[0179] Dischargeability ○: When the cake was intermittently discharged from the cake discharge port, the dischargeability was evaluated as ○.

[0180] Dischargeability ×: When the cake was not discharged from the cake discharge port, the dischargeability was evaluated as ×.

[0181] The uniformity of the coating was evaluated according to the following criteria.

[0182] Uniformity ○: When the resin was uniformly dissolved and the coating was transparent as confirmed by visual observation, it was evaluated as uniformity ○.

[0183] Uniformity ×: When the coating material was visually confirmed to be white turbid due to precipitation of the resin, the uniformity was evaluated as ×.

[0184] Table 1 shows the main conditions and results of Examples and Comparative Examples.

[0185] [Table 1]

[0186] Table 1

[0187]

[0188] As shown in Table 1, in Examples 1 to 6, the filter cakes discharged from the decanting centrifuge were sufficiently concentrated, and the uniformity of the coating was good even in the formulation in which CNF was blended at a high concentration relative to the resin. On the other hand, since there was no solid-liquid separation in Comparative Example 1, the coating had no uniformity even when the CNF concentration in the coating was 2% by mass. In Comparative Examples 2 and 3, since the centrifugal force became high, the filter cake was not discharged from the decanting centrifuge, and the coating could not be prepared at all.

[0189] In addition, the upper limit concentration of CNF in the coating indicates the concentration that can be uniformly mixed in the epoxy resin, and the higher the concentration, the better. Compared with the comparative example, the embodiment shows a 2 to 3 times better value, which can be considered to improve the resin properties (mechanical strength such as elastic modulus, shrinkage suppression during curing) when the solvent is removed from the coating to make a cured resin compared to the case of mixing in the coating.

[0190] Industrial Applicability

[0191] The (preferably anionic) modified cellulose fibers, preferably short-fibered modified cellulose fibers, obtained by the production method of the present invention can be used as a reinforcing agent for imparting mechanical strength to various coatings and the like, and as a shrinkage inhibitor during curing.

[0192] Explanation of symbols

[0193] 1 Supply slurry

[0194] 2 Rotating drum

[0195] 3 screw

[0196] 4. Recover filter cake

[0197] 5. Recover the separation liquid

Claims

1. A method for producing a modified cellulose fiber filter cake, wherein: The method comprises step A, wherein a dispersion containing pre-fiberized modified cellulose fibers having an average fiber length of 50 μm or more and 500 μm or less is subjected to solid-liquid separation under the condition that the centrifugal force of a centrifuge is 100 G or more and 500 G or less, and the centrifuge is a continuous centrifuge. The continuous centrifuge is a decanting centrifuge.

2. The manufacturing method according to claim 1, wherein: The content of the modified cellulose fibers in the dispersion is 2% by mass or more as a solid content.

3. The manufacturing method according to claim 1 or 2, wherein: The modified cellulose fiber filter cake has a solid content of 5% by mass or more.

4. The manufacturing method according to claim 1 or 2, wherein: The cellulose fiber as a raw material of the modified cellulose fiber is at least one selected from the group consisting of softwood pulp, hardwood pulp, cotton linter, cotton lint, straw pulp, bagasse pulp, and bacterial cellulose.

5. The manufacturing method according to claim 1, wherein: The flow rate of the modified cellulose fiber slurry supplied to the decanter centrifuge is 100 L / h or more and 500 L / h or less.

6. The manufacturing method according to claim 1 or 2, wherein: The denatured cellulose fibers are denatured by introducing anionic groups into the denatured cellulose fibers.

7. The manufacturing method according to claim 6, wherein: The anionic group is one or more selected from the group consisting of a carboxyl group, a sulfonic acid group, and a phosphoric acid group.

8. The manufacturing method according to claim 1 or 2, wherein: The modified cellulose fibers used in step A are anionic modified cellulose fibers that have been subjected to TEMPO oxidation treatment and short-fiberized.

9. The manufacturing method according to claim 1 or 2, wherein: The anionically modified cellulose fibers are subjected to a thermal decomposition treatment under a temperature condition of 50° C. to 230° C. to obtain short-fibered anionically modified cellulose fibers.

10. The manufacturing method according to claim 1 or 2, wherein: The dispersion in step A is a medium containing water.

11. The manufacturing method according to claim 1 or 2, wherein: The anionically modified cellulose fibers used in step A are pre-fiberized anionically modified cellulose fibers obtained by subjecting the anionically modified cellulose fibers to a thermal decomposition treatment at a temperature of 50° C. to 230° C.

12. A method for producing modified cellulose fibers, wherein: include: A step of introducing a modifying group into the modified cellulose fibers in the filter cake obtained by the production method according to any one of claims 1 to 11.

13. A method for producing fine cellulose fibers, wherein: The average fiber length of the fine cellulose fibers is 50 nm or more and 300 nm or less, and the production method comprises: A step of subjecting a modified cellulose fiber cake obtained by the production method according to any one of claims 1 to 11 or a modified cellulose fiber obtained by the method according to claim 12 to micronization.

14. A method for producing a resin composition, wherein: include: A step of mixing a modified cellulose fiber cake obtained by the production method according to any one of claims 1 to 11, a modified cellulose fiber obtained by the method according to claim 12, or a fine cellulose fiber obtained by the production method according to claim 13 with a resin.

15. A method for producing a resin composition, wherein: include: A step of mixing the modified cellulose fiber cake obtained by the production method according to any one of claims 1 to 11, a modifying compound, and a resin.

16. The manufacturing method according to claim 14, wherein: The content of the cellulose fibers in the resin composition is 0.1% by mass or more and 20% by mass or less in terms of conversion amount, The converted amount of cellulose fibers refers to the mass obtained by subtracting the mass of the modifying group from the mass of each cellulose fiber to which the modifying group is bonded.

17. The manufacturing method according to claim 14 or 16, wherein: The resin is one or more selected from the group consisting of acrylic resin, acrylic urethane resin, melamine resin, polyurethane resin, epoxy resin, urea resin and phenolic resin.

18. The manufacturing method according to claim 14 or 16, wherein: The resin composition further contains a solvent.

19. The manufacturing method according to claim 15, wherein: The content of the cellulose fibers in the resin composition is 0.1% by mass or more and 20% by mass or less in terms of conversion amount, The converted amount of cellulose fibers refers to the mass obtained by subtracting the mass of the modifying group from the mass of each cellulose fiber to which the modifying group is bonded.

20. The manufacturing method according to claim 15 or 19, wherein: The resin is one or more selected from the group consisting of acrylic resin, acrylic urethane resin, melamine resin, polyurethane resin, epoxy resin, urea resin and phenolic resin.

21. The manufacturing method according to claim 15 or 19, wherein: The resin composition further contains a solvent.

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