JP7208784B2 - Method for producing micronized hydrophobically modified cellulose fiber - Google Patents

Description

The present invention relates to a method for producing finely divided hydrophobically modified cellulose fibers.

In the past, petroleum-derived plastic materials, which are a finite resource, were widely used, but in recent years, technologies that have less impact on the environment have come into the spotlight. Materials using cellulose fibers, particularly fine cellulose fibers, are attracting attention because of their remarkably improved mechanical properties.

Since the surface of fine cellulose fibers is usually hydrophilic, they aggregate in a hydrophobic solvent or hydrophobic resin. Therefore, when used in the above system, it is necessary to modify the fine cellulose fibers to be hydrophobic.

Several methods have been devised to modify fine cellulose fibers to be hydrophobic, but most of them involve first dispersing cellulose fibers in an aqueous system to make them finer, modifying them, and then dispersing them again in an organic solvent system. It is a method of processing.

Patent Document 1 discloses a step of dispersing cellulose having a cellulose I-type crystal structure in water, then converting the hydroxyl groups of the cellulose into substituents having a carboxyl group, and reducing the cellulose with a reducing agent; a step of replacing water, which is a dispersion medium of the cellulose, with an organic solvent; a step of hydrophobizing the cellulose after the replacement of the dispersion medium by a neutralization reaction with a specific polyetheramine; and obtaining a gel composition in which cellulose nanofibers are dispersed in an organic solvent.

Non-Patent Document 1 also discloses that bulky quaternary ammonium counterions improve the nano-dispersibility of TEMPO-oxidized cellulose in a solvent.

However, in Patent Document 1 and Non-Patent Document 1, the techniques are based on polyetheramine and quaternary ammonium counter ions, respectively, and the types of modifying groups are limited. In addition, in Patent Document 1, since a large amount of high-molecular-weight amine is used as a modifying group, the weight of the modifying group becomes excessive with respect to the weight of cellulose as described in Non-Patent Document 2, and it behaves like a plasticizer. There is a problem that the excellent physical properties of fine cellulose fibers are impaired when used as a reinforcing material for resins or the like.

Patent No. 5944564

M. Shimizu, et al. , Biomacromolecules, 15 2014 H. Soeta, et al., Composites Science and Technology, 147 2017

TECHNICAL FIELD The present invention relates to a method for producing finely divided, hydrophobically modified cellulose fibers with excellent dispersibility, in which cost reduction and process simplification are achieved.

The present invention relates to the following [1] to [5].
[1] Anion-modified cellulose fibers having an average fiber diameter of 1 μm or more and 300 μm or less, which are obtained by binding a compound having a modifying group to an anion-modified cellulose fiber, are finely divided in an organic solvent. A method for producing a hydrophobically modified cellulose fiber, wherein the compound having the modifying group is one or more amines selected from the group consisting of amines represented by the following general formulas (1) to (3), and the hydrophobic A method for producing miniaturized hydrophobically modified cellulose fibers, wherein the total mass of modifying groups in the modified cellulose fibers is 1 part by mass or more and 200 parts by mass or less per 100 parts by mass of cellulose fibers.
_NH2 - ^R1 (1)
NH—R ² R ^2′ (2)
NR ³ R ^3′ R ^3″ (3)
[R ¹ in the general formula (1) is a linear or branched saturated or unsaturated hydrocarbon group having 6 to 30 carbon atoms, and R ² and R ^2′ in the general formula (2) are the same or may be different, R ² and R ^2' are linear or branched saturated or unsaturated hydrocarbon groups having a total carbon number of 8 or more and 40 or less, and R ³ and R in general formula (3) ^3′ and R ^3″ may be the same or different, and each of R ³ , R ^3′ and R ^3″ is a linear or branched saturated or unsaturated group having a total carbon number of 9 or more and 50 or less. It is a hydrocarbon group. ]
[2] A method for producing a resin composition, comprising the step of mixing the finely divided hydrophobically modified cellulose fibers produced by the production method according to [1] above with a resin.
[3] A method for producing a resin molded product by molding the resin composition produced by the production method according to [2] above.
[4] A resin composition obtained by mixing the finely divided hydrophobically modified cellulose fibers produced by the production method described in [1] above with a resin.
[5] A resin molding obtained by molding the resin composition according to [4] above.

According to the production method of the present invention, cost reduction and process simplification are achieved, and finely divided hydrophobically modified cellulose fibers having excellent dispersibility can be produced.

The production method of the present invention includes a step of refining hydrophobically modified cellulose fibers having specific modifying groups. There is no concept of achieving further cost reduction and process simplification and obtaining an invention excellent in dispersibility by a production method focusing on a specific modifying group as in the present invention. A compound having a specific modifying group used in the present invention increases the steric repulsion when bound to cellulose fibers. becomes higher, and as a result, it is presumed that the finely divided hydrophobically modified cellulose fibers also exhibit high dispersibility.

<Method for Producing Micronized Hydrophobic Modified Cellulose Fiber>
The hydrophobically modified cellulose fibers used in the present invention can be produced by performing the steps of introducing an anionic group into the raw material cellulose fiber and introducing a modifying group in any order. The step of short fiberization treatment can be further performed regardless of the order.

[Cellulose fiber]
As the raw material cellulose fiber, it is preferable to use natural cellulose fiber from the viewpoint of environmental load. Examples of natural cellulose fibers include wood pulp such as softwood pulp and hardwood pulp; cotton pulp such as cotton linter and cotton lint; non-wood pulp such as straw pulp and bagasse pulp; These 1 types can be used individually or in combination of 2 or more types.

The average fiber diameter of the raw material cellulose fibers is not particularly limited, but from the viewpoint of handleability and cost, it is preferably 1 μm or more, more preferably 5 μm or more, still more preferably 15 μm or more, and preferably 300 μm. or less, more preferably 100 μm or less, and still more preferably 60 μm or less.

In addition, the average fiber length of the raw cellulose fiber is not particularly limited, but from the viewpoint of availability and cost, it is preferably more than 1,000 μm, more preferably 1,200 μm or more, and still more preferably 1,200 μm or more. It is 500 μm or more, preferably 10,000 μm or less, more preferably 5,000 μm or less, still more preferably 3,000 μm or less. The average fiber diameter and average fiber length of the raw material cellulose fibers can be measured according to the methods described in Examples below.

[Anion-modified cellulose fiber]
Anion-modified cellulose fibers containing anionic groups (also simply referred to as "anion-modified cellulose fibers") used in the present invention are cellulose fibers anionically modified so as to contain anionic groups.

The preferred ranges of the average fiber diameter and average fiber length of the anion-modified cellulose fibers are the same as those of the starting cellulose fibers.

The anion-modified cellulose fiber preferably has an anionic group content of 0.1 mmol/g or more, more preferably 0.5 mmol/g or more, from the viewpoint of stable miniaturization and modification group introduction, More preferably, it is 0.8 mmol/g or more. The upper limit is preferably 3 mmol/g or less, more preferably 2 mmol/g or less, still more preferably 1.8 mmol/g or less. In order to make the content of the anionic group within such a range, it can be controlled by adjusting treatment conditions such as oxidation treatment or by performing reduction treatment. The anionic group content means the total amount of anionic groups in the cellulose fibers constituting the anionic group-containing cellulose fibers, and is measured by the method described in Examples below.

The anionic group contained in the anion-modified cellulose fiber includes, for example, a carboxy group, a sulfonic acid group, a phosphoric acid group, and the like, and from the viewpoint of efficiency of introduction into the cellulose fiber, the carboxy group is preferable.
Examples of ions (counter ions) that form pairs of anionic groups in anion-modified cellulose fibers include, for example, metal ions such as sodium ions, potassium ions, calcium ions and aluminum ions generated in the presence of alkali during production, and these metal ions. Examples include protons generated by substituting ions with acids.

(Step of introducing anionic group)
The anion-modified cellulose fiber used in the present invention can be obtained by subjecting the target cellulose fiber to an oxidation treatment or an anionic group addition treatment to introduce at least one or more anionic groups for anion modification. .
Cellulose fibers to be anion-modified include raw material cellulose fibers. From the viewpoint of dispersibility, cellulose fibers (hereinafter referred to as short fibers It is also called a modified cellulose fiber.) is preferably used.

(i) Introduction of carboxyl groups as anionic groups into cellulose fibers Methods for introducing carboxyl groups into cellulose fibers as anionic groups include, for example, a method of oxidizing hydroxyl groups of cellulose to convert them into carboxyl groups, and A method of reacting at least one selected from the group consisting of a compound having a carboxyl group in a hydroxyl group, an acid anhydride of a compound having a carboxyl group, and derivatives thereof may be mentioned.

The method of oxidizing the hydroxyl groups of cellulose is not particularly limited, but for example, 2,2,6,6-tetramethyl-1-piperidine-N-oxyl (TEMPO) is used as a catalyst, sodium hypochlorite or the like is used. A method of reacting an oxidizing agent and a bromide such as sodium bromide for oxidation treatment can be applied. For more details, the method described in JP-A-2011-140632 can be referred to.

By subjecting the cellulose fiber to oxidation treatment using TEMPO as a catalyst, the hydroxymethyl group (--CH ₂ OH) at the C6 position of the cellulose structural unit is selectively converted to a carboxy group. In particular, this method is advantageous in that it is excellent in the selectivity of the hydroxyl group at the C6 position to be oxidized on the surface of the raw material cellulose fiber and that the reaction conditions are mild. Therefore, a preferred embodiment of the anion-modified cellulose fiber in the present invention is a cellulose fiber having a carboxy group at the C6 position of the cellulose structural unit. In this specification, such cellulose fibers are sometimes referred to as "oxidized cellulose fibers".

Although the compound having a carboxy group to be used for introducing the carboxy group into the cellulose fiber is not particularly limited, specific examples thereof include halogenated acetic acid. Halogenated acetic acid includes chloroacetic acid and the like.

Acid anhydrides of compounds having carboxy groups and derivatives thereof for use in introducing carboxy groups into cellulose fibers are not particularly limited, but maleic anhydride, succinic anhydride, phthalic anhydride, adipic anhydride, etc. Examples include acid anhydrides of dicarboxylic acid compounds, imidized acid anhydrides of compounds having a carboxy group, and derivatives of acid anhydrides of compounds having a carboxy group. These compounds may be substituted with hydrophobic groups.

(ii) In the case of introducing a sulfonic acid group or a phosphoric acid group as an anionic group into cellulose fibers As a method for introducing a sulfonic acid group as an anionic group into cellulose fibers, there is a method of adding sulfuric acid to cellulose fibers and heating the same. mentioned.

Methods for introducing a phosphate group as an anionic group into cellulose fibers include a method of mixing powder or an aqueous solution of phosphoric acid or a phosphoric acid derivative with cellulose fibers in a dry or wet state, or a method of adding phosphoric acid to a dispersion of cellulose fibers. A method of adding an aqueous solution of an acid or a phosphoric acid derivative can be used. When these methods are employed, dehydration treatment, heat treatment, and the like are generally performed after mixing or adding a powder or aqueous solution of phosphoric acid or a phosphoric acid derivative.

[Hydrophobic modified cellulose fiber]
The hydrophobically-modified cellulose fiber in the present invention is selected from the group consisting of amines as compounds having modifying groups on the anionic groups of anion-modified cellulose fibers, i.e., primary amines, secondary amines and tertiary amines. It is a cellulose fiber having an average fiber diameter of 1 μm or more and 300 μm or less, which is formed by bonding one or more kinds of amines.

The average fiber diameter of the hydrophobically-modified cellulose fibers is 1 μm or more, preferably 5 μm or more, more preferably 15 μm or more from the viewpoint of dispersibility, while it is 300 μm or less, preferably 100 μm or less from the same viewpoint. and more preferably 60 μm or less. The average fiber length of the hydrophobically modified cellulose fibers is preferably 1,000 µm or more, more preferably 1,200 µm or more, and still more preferably 1,500 µm or more, from the viewpoints of dispersibility, availability, and economy. On the other hand, from the same viewpoint, it is preferably 10,000 μm or less, more preferably 5,000 μm or less, and still more preferably 3,000 μm or less. The average fiber diameter and average fiber length of the hydrophobically modified cellulose fibers can be measured according to the methods described in Examples below.

From the viewpoint of dispersibility, the total mass of the modifying groups in the hydrophobically-modified cellulose fibers is 1 part by mass or more, preferably 10 parts by mass or more, more preferably 15 parts by mass with respect to 100 parts by mass of cellulose fibers. Department or above. On the other hand, from the viewpoint of expressing reinforcing performance such as strength when the fiber is applied to resin etc., it is 200 parts by mass or less, preferably 150 parts by mass or less, more preferably 100 parts by mass of cellulose fiber. is 100 parts by mass or less. In this specification, the total mass of modifying groups in the hydrophobically-modified cellulose fiber can be determined by the method described in Examples below.

From the viewpoint of improving dispersibility, the average bonding amount of modifying groups in hydrophobically modified cellulose fibers is preferably 0.01 mmol/g or more, more preferably 0.05 mmol/g or more, and still more preferably 0.1 mmol/g. /g or more, more preferably 0.3 mmol/g or more, and still more preferably 0.5 mmol/g or more. Further, from the viewpoint of reactivity, it is preferably 3 mmol/g or less, more preferably 2.5 mmol/g or less, still more preferably 2 mmol/g or less, still more preferably 1.8 mmol/g or less. , more preferably 1.5 mmol/g or less. When two or more arbitrary modifying groups are simultaneously introduced into the cellulose fibers as modifying groups, the average amount of bonding of the modifying groups is preferably within the above range for the total amount of the modifying groups introduced.

From the viewpoint of dispersibility, the introduction rate of the modifying group in the hydrophobically-modified cellulose fiber is preferably 5% or more, more preferably 10% or more, and still more preferably 15% or more, for any modification group. , from the viewpoint of reactivity, it is preferably 100% or less, more preferably 60% or less, and still more preferably 50% or less.

In this specification, the average bonding amount and introduction rate of the modifying group can be adjusted by the amount of modifying group added, the type of modifying group, reaction temperature, reaction time, solvent, and the like. The average binding amount (mmol/g) and the introduction rate (%) of the modifying group refer to the amount and ratio of the modifying group introduced to the anionic groups on the surface of the hydrophobically modified cellulose fiber. The anionic group content of the hydrophobically modified cellulose fiber can be calculated by measuring according to known methods (eg, titration, IR measurement, etc.). The average bonding amount and introduction rate of the modifying group are calculated, for example, by the method described in Examples.

(Step of introducing modifying group into cellulose fiber)
The hydrophobically-modified cellulose fiber used in the present invention can be obtained by introducing a predetermined modifying group (also referred to as “modification”) into the target cellulose fiber. Cellulose fibers to be modified group-introduced are anion-modified cellulose fibers obtained through a step of introducing anionic groups into raw cellulose fibers.

The hydrophobically-modified cellulose fibers used in the present invention are preferably those obtained through a step of introducing a compound having a modifying group, which will be described later, into an anion-modified cellulose fiber in an organic solvent (referred to as "step (A)"). .

The organic solvent used in step (A) is not particularly limited as long as it dissolves the amine used. Examples include methanol, ethanol, benzyl alcohol, N,N-dimethylformamide (DMF), isopropanol (IPA), dimethyl sulfoxide (DMSO), N,N-dimethylacetamide, tetrahydrofuran (THF), diester of succinic acid and triethylene glycol monomethyl ether, acetone, methyl ethyl ketone (MEK), acetonitrile, dichloromethane, chloroform, toluene, acetic acid and the like. , these can be used alone or in combination of two or more. Furthermore, from the viewpoint of simplification of the process, it is more preferable that the organic solvent in the step (A) and the organic solvent in the micronization step are the same.

From the viewpoint of improving dispersibility in hydrophobic solvents and hydrophobic resins, a modifying group derived from a compound having a modifying group is introduced into the anionic group of the anion-modified cellulose fiber. A compound having a modifying group more preferably binds to the anionic group via an ionic bond and/or a covalent bond. From the viewpoint of dispersibility, specific bonding modes include ionic bonds with amine salts and covalent bonds such as amide bonds, ester bonds and urethane bonds.

When the binding mode is ionic bonding, a modifying group can be introduced with reference to JP-A-2015-143336. Here, the compound having a modifying group is one or more amines selected from the group consisting of amines represented by the following general formulas (1) to (3).
_NH2 - ^R1 (1)
NH—R ² R ^2′ (2)
NR ³ R ^3′ R ^3″ (3)
[R ¹ in the general formula (1) is a linear or branched saturated or unsaturated hydrocarbon group having 6 to 30 carbon atoms, and R ² and R ^2′ in the general formula (2) are the same or may be different, R ² and R ^2' are linear or branched saturated or unsaturated hydrocarbon groups having a total carbon number of 8 or more and 40 or less, and R ³ and R in general formula (3) ^3′ and R ^3″ may be the same or different, and each of R ³ , R ^3′ and R ^3″ is a linear or branched saturated or unsaturated group having a total carbon number of 9 or more and 50 or less. It is a hydrocarbon group. ]

The number of carbon atoms in R ¹ is preferably 8 or more, more preferably 10 or more, still more preferably 12 or more, from the viewpoint of dispersibility. On the other hand, from the same viewpoint, it is preferably 24 or less, more preferably 20 or less, and even more preferably 18 or less.

From the viewpoint of dispersibility, the total carbon number of R ² and R ^2' is preferably 8 or more, more preferably 10 or more, and even more preferably 12 or more. On the other hand, from the same viewpoint, it is preferably 36 or less, more preferably 30 or less, and even more preferably 24 or less.

From the viewpoint of dispersibility, the total carbon number of R ³ , R ^3′ and R ^3″ is preferably 9 or more, more preferably 10 or more, and even more preferably 12 or more. On the other hand, from the same viewpoint, it is preferably 42 or less, more preferably 36 or less, and even more preferably 24 or less.

Examples of primary to tertiary amines include dibutylamine, hexylamine, 2-ethylhexylamine, dihexylamine, trihexylamine, octylamine, dioctylamine, trioctylamine, dodecylamine, didodecylamine, stearyl Amine, distearylamine, oleylamine, octadecylamine, dimethylbehenylamine. Among these, dodecylamine, oleylamine, stearylamine, dihexylamine, and trihexylamine are preferred from the viewpoint of dispersibility.

When the binding mode is a covalent bond, for example, when modifying via an amide bond, a modifying group can be introduced with reference to JP-A-2015-143337. Here, it is preferable to use, for example, an amine represented by general formula (1) and/or an amine represented by general formula (2) as the compound having a modifying group.

When the compound having a modifying group has the chain saturated hydrocarbon group described above as the modifying group, the chain saturated hydrocarbon group may be linear or branched. From the viewpoint of improving dispersibility, the number of carbon atoms in the chain saturated hydrocarbon group is preferably 6 or more, more preferably 8 or more, and still more preferably 10 or more in one modifying group, From the same point of view, it is preferably 30 or less, more preferably 24 or less, and still more preferably 18 or less. Specific examples include hexyl group, 2-ethylhexyl group, dodecyl group, dihexyl group, trihexyl group and the like.

When the compound having a modifying group has the above-described unsaturated chain hydrocarbon group as the modifying group, the unsaturated chain hydrocarbon group may be linear or branched. From the viewpoint of improving dispersibility, the number of carbon atoms in the chain unsaturated hydrocarbon group is preferably 6 or more, more preferably 8 or more, and still more preferably 10 or more in one modifying group. , from the same viewpoint, it is preferably 30 or less, more preferably 24 or less, and still more preferably 18 or less. Specific examples include an oleyl group.

Amines represented by general formulas (1) to (3), which can provide the various modifying groups described above, can be commercially available or can be prepared according to known methods.

[Miniaturized Hydrophobic Modified Cellulose Fiber]
The term "miniaturized hydrophobically modified cellulose fibers" refers to hydrophobically modified cellulose fibers having an average fiber diameter and an average fiber length within the following ranges.
From the viewpoint of dispersibility, the average fiber diameter of the miniaturized hydrophobically modified cellulose fibers is preferably 0.1 nm or more, more preferably 0.5 nm or more, still more preferably 1 nm or more, and still more preferably 2 nm. That's it. From the same viewpoint, it is preferably 200 nm or less, more preferably 100 nm or less, even more preferably 50 nm or less, and still more preferably 20 nm or less.

From the viewpoint of dispersibility, the average fiber length of the miniaturized hydrophobically modified cellulose fibers is preferably 50 nm or longer, more preferably 80 nm or longer, and still more preferably 100 nm or longer. From the same viewpoint, it is preferably 2,000 nm or less, more preferably 1,000 nm or less, and still more preferably 800 nm or less. The average fiber diameter and average fiber length of the miniaturized hydrophobically modified cellulose fibers are measured by the methods described in Examples below.

(Step of preparing fine hydrophobic modified cellulose fibers)
In this step, the hydrophobically-modified cellulose fibers are finely treated in a specific organic solvent, and the finely-sized hydrophobically-modified cellulose fibers are obtained by the fineness treatment. In the micronization treatment step, it is preferable to perform the micronization treatment on the hydrophobically-modified cellulose fibers dispersed in the organic solvent, or on the ones from which the organic solvent has been removed, which are newly dispersed in the solvent. When the step (A) is passed through, it is more preferable to subject the particles dispersed in the same organic solvent as the organic solvent used in the step (A) to a micronization treatment. Specifically, it can be carried out with reference to the description of the miniaturization process in Japanese Patent Application Laid-Open No. 2013-151661.

(Disperser)
A well-known dispersing machine is suitable as an apparatus that can be used in the micronization treatment. For example, stirrers equipped with stirring blades, disaggregators, beaters, low-pressure homogenizers, high-pressure homogenizers, grinders, cutter mills, ball mills, jet mills, roll mills, short-screw kneaders, twin-screw kneaders, short-screw extruders, A twin-screw extruder, an ultrasonic stirrer, a domestic juicer mixer, or the like can be used. The operating conditions of the device may be appropriately set with reference to the attached instruction manual.

(organic solvent)
From the standpoint of dispersibility, the organic solvent that can be used as a dispersion medium for the micronization treatment is preferably N,N-dimethylformamide, dimethylsulfoxide, N,N-dimethylacetamide, N-methylpyrrolidone, or tetrahydrofuran (THF). , diester of succinic acid and triethylene glycol monomethyl ether, dichloromethane, chloroform, toluene, acetic acid, methanol, ethanol, benzyl alcohol, n-propanol, 2-propanol, ethylene glycol, propylene glycol, t-butyl alcohol, cyclohexanone, acetonitrile , silicone oil, 1,3-dioxolane, methyl acetate, ethyl acetate, butyl acetate, one or more organic solvents selected from the group consisting of acetone and methyl ethyl ketone, more preferably N,N-dimethyl One or more organic solvents selected from the group consisting of formamide, dimethylsulfoxide, N,N-dimethylacetamide, N-methylpyrrolidone, methanol, ethanol, benzyl alcohol, n-propanol, ethyl acetate and ethylene glycol. more preferably one or more organic solvents selected from the group consisting of N,N-dimethylformamide, dimethylsulfoxide, N,N-dimethylacetamide, and N-methylpyrrolidone.

In addition, as an organic solvent other than the above, an organic solvent having a reactive functional group can also be used. Examples of organic solvents having a reactive functional group include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, n-hexyl acrylate, and n-methacrylate. xyl, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, acrylates such as phenyl glycidyl ether acrylate; urethane prepolymers such as hexamethylene diisocyanate urethane prepolymer, phenyl glycidyl ether acrylate toluene diisocyanate urethane prepolymer; n-butyl glycidyl ether, 2-ethylhexyl glycidyl ether, glycidyl stearate, styrene oxide, phenyl glycidyl ether, nonylphenyl glycidyl ether, butylphenyl glycidyl ether, 1,6-hexanediol diglycidyl ether, ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether Glycidyl ethers such as ether; chlorostyrene, methoxystyrene, butoxystyrene, vinyl benzoic acid and the like.

Since such an organic solvent is presumed to have a high affinity with the hydrophobically modified cellulose fiber, the dispersibility of the cellulose fiber can be improved by using such an organic solvent during the preparation of the hydrophobically modified cellulose fiber and the refining treatment. As a result, it is presumed that the finely divided hydrophobically modified cellulose fibers also exhibit high dispersibility.

The organic solvent used in the present invention preferably has a dielectric constant at 25° C. of 75 or less, more preferably 55 or less, and still more preferably 45 or less, from the viewpoint of better exhibiting the effects of the present invention. On the other hand, it is preferably 1 or more, more preferably 2 or more, and still more preferably 3 or more. The dielectric constant of the organic solvent can be measured at 25° C. using a liquid dielectric constant meter Model 871 (manufactured by Nihon Luft Co., Ltd.).

The amount of the organic solvent used in the microfabrication process is not particularly limited as long as it can maintain the dispersed state of the hydrophobically modified cellulose fibers. The amount is preferably 0.01% by mass or more, and preferably 50% by mass or less.

Thus, it is possible to obtain finely divided hydrophobically modified cellulose fibers in which modifying groups are bonded to hydrophobically modified cellulose fibers. The miniaturized hydrophobically modified cellulose fibers are prepared in a dispersed state (ie, dispersion) in the organic solvent. The miniaturized hydrophobically modified cellulose fibers can be used in the form of a dispersion, or can be used in the form of a dried powder after removing the organic solvent from the dispersion by a drying treatment or the like.

The dispersion may contain optional ingredients that do not impair the effects of the present invention. The content of these optional components in the dispersion is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and still more preferably 0.5% by mass in terms of the blending amount. or more, preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less. When there are two or more optional ingredients, the amount of optional ingredients is the total amount of each optional ingredient.

The finely divided hydrophobically modified cellulose fibers produced by the production method of the present invention are excellent in dispersibility. The present invention, in which further cost reduction and process simplification of the production method can be achieved by using a compound having a specific modifying group, cannot be conceived from conventionally known inventions.

<Resin composition and its manufacturing method>
The resin composition of the present invention is obtained by mixing the finely divided hydrophobically-modified cellulose fibers produced by the above-mentioned production method with a resin, and the finely divided hydrophobically-modified cellulose fibers are produced according to the above-described production method of the present invention. manufactured by the method. Using such a resin composition, a molded article can be produced by a known molding method.

(resin)
Resins that can be used are not particularly limited, but thermoplastic resins, curable resins, cellulose-based resins, and rubber-based resins can be used, for example. Such thermoplastic resins, curable resins, cellulose resins and rubber resins may be used singly or in combination of two or more.

(Thermoplastic resin)
Thermoplastic resins include saturated polyester resins such as polylactic acid resins; olefin resins such as polyethylene resins and polypropylene resins; vinyl chloride resins, vinylidene chloride resins, styrene resins, vinyl ether resins, polyvinyl alcohol resins, polyvinyl acetal resins, and polyvinyl acetate resins. Vinyl resins such as resins; (meth)acrylic resins; polyamide resins; polycarbonate resins; polysulfone resins; These thermoplastic resins may be used alone or as a mixed resin of two or more. Among these resins, olefin resins, polycarbonate resins, (meth)acrylic resins, vinyl chloride resins and polyurethane resins are preferable because a resin composition having excellent dispersibility can be obtained. In addition, in this specification, (meth)acrylic resin means the concept including methacrylic resin and acrylic resin.

The (meth)acrylic resin preferably contains 50% by weight or more of methyl (meth)acrylate as a monomer unit based on the total monomer units of all the polymers constituting the resin, A methacrylic resin is more preferred.

A methacrylic resin can be produced by copolymerizing methyl methacrylate and other monomers copolymerizable therewith. The polymerization method is not particularly limited, and examples thereof include a bulk polymerization method, a solution polymerization method, a suspension polymerization method, a cast polymerization method (eg, a cell cast polymerization method), and the like.

(Curable resin)
As the curable resin, a photocurable resin and/or a thermosetting resin are preferable.
A photocurable resin undergoes a polymerization reaction by using a photopolymerization initiator that generates radicals and cations when irradiated with active energy rays such as ultraviolet rays and electron beams.

Examples of the photopolymerization initiator include acetophenones, benzophenones, ketals, anthraquinones, thioxanthones, azo compounds, peroxides, 2,3-dialkyldione compounds, disulfide compounds, thiuram compounds, and fluoroamines. compounds and the like. More specific examples include compounds described in paragraph 0113 of JP-A-2018-024967.

A photopolymerization initiator can polymerize, for example, monomers (monofunctional monomers, polyfunctional monomers), oligomers or resins having reactive unsaturated groups.

Examples of monofunctional monomers include (meth) acrylic monomers such as (meth) acrylic acid esters, vinyl monomers such as vinylpyrrolidone, isobornyl (meth) acrylate, adamantyl (meth) acrylate, and the like. Examples thereof include (meth)acrylates having a crosslinked cyclic hydrocarbon group. Polyfunctional monomers include polyfunctional monomers having about 2 to 8 polymerizable groups, and bifunctional monomers include, for example, ethylene glycol di(meth)acrylate, propylene glycol di(meth) ) di(meth)acrylate having a crosslinked cyclic hydrocarbon group such as acrylate. Tri- to octa-functional monomers include, for example, glycerin tri(meth)acrylate.

Examples of oligomers or resins having reactive unsaturated groups include (meth)acrylates of bisphenol A-alkylene oxide adducts, epoxy (meth)acrylates (bisphenol A type epoxy (meth)acrylates, novolac type epoxy (meth)acrylates, etc.). , polyester (meth)acrylate (e.g., aliphatic polyester type (meth)acrylate, aromatic polyester type (meth)acrylate, etc.), urethane (meth)acrylate (polyester type urethane (meth)acrylate, polyether type urethane (meth)acrylate) acrylate, etc.), silicone (meth)acrylate, and the like. These oligomers or resins may be used together with the above monomers.

A photocurable resin is preferable from the viewpoint of obtaining a resin composition or a molded article having few aggregates and excellent transparency.

Thermosetting resins include, for example, epoxy resins, phenol resins, phenoxy resins, urea resins, melamine resins, unsaturated polyester resins, diallyl phthalate resins, polyurethane resins, silicon resins and polyimide resins. A thermosetting resin can be used individually by 1 type or in combination of 2 or more types. Among these, epoxy resins, phenol resins, phenoxy resins, urea resins, melamine resins, unsaturated polyester resins, and polyurethane resins are preferred because they give dispersions with excellent dispersibility. , polyurethane resin is more preferred.

When using the resin component, it is preferable to use a curing agent. By blending the curing agent, the molded article obtained from the resin composition can be strongly molded, and the mechanical strength can be improved. The amount of the curing agent to be blended may be appropriately set according to the type of resin and/or the type of curing agent used.

(Cellulose resin)
Cellulose-based resins include organic acid esters such as cellulose mixed acylates such as cellulose acetate (cellulose acetate) and cellulose acetate propionate; inorganic acid esters such as cellulose nitrate and cellulose phosphate; organic acids such as cellulose nitrate acetate; mixed acid esters; cellulose ether esters such as acetylated hydroxypropyl cellulose; The cellulose acetate includes cellulose triacetate (acetyl substitution degree of 2.6 to 3), cellulose diacetate (acetyl substitution degree of 2 or more and less than 2.6), and cellulose monoacetate. Cellulose-based resins may be used alone or in combination of two or more.

(rubber resin)
Further, in the present invention, a rubber-based resin can be used as the resin. In order to increase the strength of rubber-based resins, products containing inorganic fillers such as carbon black and silica are widely used as reinforcing materials, but it is thought that there is a limit to the reinforcing effect. However, it is possible to provide a dispersion and a molded article (rubber) with excellent mechanical strength and heat resistance because it has excellent dispersibility in a resin composition obtained by blending a rubber-based resin into the dispersion. is considered to be

As the rubber-based resin, diene-based rubber and non-diene-based rubber are preferable.
Examples of diene rubbers include natural rubber, polyisoprene rubber, polybutadiene rubber, styrene-butadiene copolymer rubber, butyl rubber, butadiene-acrylonitrile copolymer rubber, chloroprene rubber and modified natural rubber. Examples of modified natural rubber include epoxidized natural rubber and hydrogenated natural rubber. Non-diene rubbers include butyl rubber, ethylene-propylene rubber, ethylene-propylene-diene rubber, urethane rubber, silicone rubber, fluororubber, acrylic rubber, polysulfide rubber, epichlorohydrin rubber, and the like. These can be used individually or in combination of 2 or more types.

In summary, the resin contained in the resin composition is selected from the group consisting of olefin resins, polyurethane resins, polycarbonate resins, (meth)acrylic resins, epoxy resins, phenolic resins, phenoxy resins, vinyl resins and rubber resins. are preferably one or more.

The amount of the resin in the resin composition of the present invention cannot be unconditionally determined depending on the desired physical properties of the molded article and the molding method, but from the viewpoint of exhibiting the inherent performance of the resin, it is preferably 10 in terms of the blending amount. % by mass or more, more preferably 20% by mass or more, more preferably 30% by mass or more, and even more preferably 40% by mass or more. 9% by mass or less, more preferably 99% by mass or less, more preferably 90% by mass or less, and even more preferably 80% by mass or less.

The amount of the finely divided hydrophobically modified cellulose fibers in the resin composition of the present invention cannot be unconditionally determined depending on the desired physical properties of the resin composition and the molding method, but from the viewpoint of exhibiting the addition effect of the finely divided hydrophobically modified cellulose fibers. , preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, still more preferably 0.5 parts by mass or more, still more preferably 1 part by mass, based on 100 parts by mass of the resin, in terms of the compounding amount On the other hand, it is preferably 100 parts by mass or less, more preferably 50 parts by mass or less, still more preferably 30 parts by mass or less, still more preferably 10 parts by mass or less.

(other ingredients)
In addition to the above components, the resin composition of the present invention includes a plasticizer, a crystal nucleating agent, a filler (inorganic filler, organic filler), a hydrolysis inhibitor, a flame retardant, an antioxidant, hydrocarbon waxes, and Lubricants that are anionic surfactants, ultraviolet absorbers, antistatic agents, antifogging agents, light stabilizers, pigments, antifungal agents, antibacterial agents, foaming agents, surfactants; starches, polysaccharides such as alginic acid; Natural proteins such as gelatin, glue, and casein; inorganic compounds such as tannin, zeolite, ceramics, and metal powders; fragrances; flow control agents; leveling agents; It can be contained within a range that does not impair the effect. Similarly, other polymer materials and other resin compositions can be added within a range that does not impair the effects of the present invention.

The plasticizer is not particularly limited, and includes conventional plasticizers such as polyvalent carboxylic acid esters such as phthalates, succinates and adipates, and fatty acid esters of aliphatic polyols such as glycerin. Specifically, plasticizers described in JP-A-2008-174718 and JP-A-2008-115372 are exemplified.

In addition, when the resin composition of the present invention contains a rubber-based resin, carbon black or silica commonly used in the rubber industry may optionally be added as components other than the above as long as the object of the present invention is not impaired. Reinforcing fillers such as, various chemicals such as vulcanizing agents, vulcanization accelerators, anti-aging agents, anti-scorch agents, zinc white, stearic acid, process oils, vegetable oils, plasticizers for tires, and other general rubbers Various additives blended for use can be blended in conventional general amounts.

(Method for producing resin composition)
The resin composition of the present invention can be produced by mixing each component, that is, the finely divided hydrophobically modified cellulose fibers and the resin with a high-pressure homogenizer. Alternatively, these components are stirred with a Henschel mixer, a rotation-revolution stirrer, or the like, or melt-kneaded using a known kneader such as a closed kneader, a single-screw or twin-screw extruder, and an open-roll kneader. It can also be prepared by

<Molded body>
The molded article can be prepared by appropriately using a known molding method such as extrusion molding, injection molding, press molding, cast molding or solvent casting using a resin composition. Since the resin composition of the present invention is excellent in the dispersibility of the finely divided hydrophobically modified cellulose fibers, the mechanical strength of various resin products, which are moldings, is improved as compared with conventional products. Therefore, the molded article can be suitably used for various purposes.

Applications for which the resin composition and molded article can be used are not particularly limited, but examples include transparent resin materials, three-dimensional modeling materials, cushioning materials, repair materials, adhesives, adhesives, sealing materials, heat insulating materials, sound absorbing materials, and artificial leather materials. , paints, electronic materials, packaging materials, tires, automobile parts, and fiber composite materials. Among these, transparent resin materials, adhesives, pressure-sensitive adhesives, artificial leather materials, paints, electronic materials, and fiber composite materials are particularly preferable from the viewpoint of obtaining molded articles with excellent transparency, and from the viewpoint of strength development. Three-dimensional modeling materials, cushion materials, repair materials, sealing materials, heat insulating materials, sound absorbing materials, tires, and automobile parts are preferred.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples. It should be noted that this example is merely an illustration of the present invention and does not imply any limitation. Parts in the examples are parts by weight unless otherwise specified. "Atmospheric pressure" means 101.3 kPa, and "room temperature" means 25°C.

[Average Fiber Diameter and Average Fiber Length of Cellulose Fibers, Anionic Group-Containing Cellulose Fibers, Chopped Cellulose Fibers, and Hydrophobically Modified Cellulose Fibers]
Ion-exchanged water is added to the cellulose fibers to be measured to prepare a dispersion having a content of 0.01% by mass. Using a wet dispersion type image analysis particle size distribution meter (manufactured by Jusco International Co., Ltd., trade name: IF-3200), the dispersion is measured with a front lens of 2x, a telecentric zoom lens of 1x, and an image resolution of 0.835 μm/pixel. , syringe inner diameter: 6515 μm, spacer thickness: 500 μm, image recognition mode: ghost, threshold: 8, analysis sample amount: 1 mL, sampling: 15%. 100 or more cellulose fibers are measured, the average ISO fiber diameter is calculated as the average fiber diameter, and the average ISO fiber length is calculated as the average fiber length.

[Average fiber diameter and average fiber length of miniaturized hydrophobically modified cellulose fiber]
Ion-exchanged water or a mixed solvent of methanol/water=2/1 is added to the finely divided hydrophobically modified cellulose fibers to prepare a dispersion having a content of 0.0001% by mass. An atomic force microscope (AFM, Nanoscope III Tapping mode AFM, manufactured by Digital Instruments Co., Ltd., the probe is Nanosensors Point Probe (NCH ) is used to measure the fiber height of the cellulose fibers in the observation sample. At that time, 100 or more cellulose fibers are extracted from a microscope image in which the cellulose fibers can be confirmed, and the average fiber diameter is calculated from the fiber heights. Calculate the average fiber length from the distance in the fiber direction.

[Anionic group content of anionic group-containing cellulose fiber, short cellulose fiber, and hydrophobically modified cellulose fiber]
Take 0.5 g of dry mass of cellulose fiber to be measured in a 100 mL beaker, add ion-exchanged water or a mixed solvent of methanol/water = 2/1 to make a total of 55 mL, and add 5 mL of 0.01 M sodium chloride aqueous solution. to prepare a dispersion. The dispersion is stirred until the cellulose fibers are well dispersed. Add 0.1 M hydrochloric acid to this dispersion to adjust the pH to 2.5 to 3, and wait for 0.05 M sodium hydroxide aqueous solution using an automatic titrator (manufactured by Toa DKK Co., Ltd., trade name: AUT-710). It is added dropwise to the dispersion for 60 seconds, and the conductivity and pH values are measured every minute. The measurement is continued until the pH reaches about 11, and a conductivity curve is obtained. From this conductivity curve, the titration amount of sodium hydroxide is obtained, and the anionic group content of the cellulose fiber to be measured is calculated by the following formula.
Anionic group content (mmol/g) = sodium hydroxide titration amount x sodium hydroxide aqueous solution concentration (0.05M)/mass of cellulose fiber to be measured (0.5g)

[Solid content in dispersion or dispersion]
A halogen moisture meter (manufactured by Shimadzu Corporation, trade name: MOC-120H) is used. A 1 g sample is measured at a constant temperature of 150° C. every 30 seconds, and the value at which the mass reduction becomes 0.1% or less is taken as the solid content.

[Average bonding amount and introduction rate (ionic bond) of modifying group of hydrophobically modified cellulose fiber]
The bonding amount of the modifying group is determined by the following IR measurement method, and the average bonding amount and introduction ratio are calculated by the following formula. Specifically, the IR measurement is performed by measuring the dried hydrophobically modified cellulose fiber by the ATR method using an infrared absorption spectrometer (IR) (manufactured by Thermo Fisher Scientific, trade name: Nicolet 6700). The average bonding amount and introduction rate of the modifying group are calculated by the formula. The following shows the case where the anionic group is a carboxy group. The “1720 cm ⁻¹ peak intensity” below is the peak intensity derived from the carbonyl group. In the case of an anionic group other than the carboxyl group, the peak intensity value may be appropriately changed to calculate the average bonding amount and introduction ratio of the modifying group.
Average binding amount of modifying group (mmol/g) = [Carboxy group content of cellulose fiber before introducing modifying group (mmol/g)] × [(Peak intensity at 1720 cm ^-1 of cellulose fiber before introducing modifying group - Hydrophobicity 1720 cm ⁻¹ peak intensity of modified cellulose fiber)/1720 cm ⁻¹ peak intensity of cellulose fiber before introduction of modifying group]
Peak intensity at 1720 cm ⁻¹ : Peak intensity derived from carbonyl group of carboxylic acid Modification group introduction rate (%)={Average amount of modification group bound (mmol/g)/Carboxy group in cellulose fiber before introduction of modification group Content (mmol/g)}×100

[Average bond amount and introduction ratio (amide bond) of modifying group of hydrophobically modified cellulose fiber]
The average bonding amount of the modifying group is calculated by the following formula. The following shows the case where the anionic group is a carboxy group. In the case of an anionic group other than a carboxyl group, the carboxyl group is replaced with the anionic group, and the average binding amount and introduction rate of the modifying group can be calculated.
Average bonding amount of modifying group (mmol/g) = carboxy group content in cellulose fiber before modification group introduction (mmol/g) - carboxy group content in cellulose fiber after modification group introduction (mmol/g)
Modification group introduction rate (%) = {average bonding amount of modification group (mmol/g)/carboxy group content in cellulose fiber before introduction of modification group (mmol/g)} x 100

[Total parts by mass of modifying groups per 100 parts by mass of cellulose raw material in hydrophobically modified cellulose fiber]
The mass of the modifying group is calculated from the "average bonding amount of the modifying group of the hydrophobically-modified cellulose fiber" and the molecular weight of the modifying compound, and the mass of the cellulose raw material is the following "cellulose fiber (converted amount)" below. Calculate as follows.

[Cellulose fiber (converted amount) in hydrophobically modified cellulose fiber]
The cellulose fiber (converted amount) in the hydrophobically modified cellulose fiber is measured by the following method.
(1) When only one type of modifying compound is added The amount of cellulose fiber (converted amount) is calculated by the following formula A.
<Formula A>
Amount of cellulose fiber (converted amount) (g)=mass of hydrophobically modified cellulose fiber (g)/[1+molecular weight of modifying compound (g/mol)×binding amount of modifying group (mmol/g)×0.001]

(2) When two or more types of modifying compounds are added, considering the molar ratio of each modifying compound (that is, the molar ratio when the total molar amount of the modifying compounds to be added is 1), Calculate the amount of fiber (converted amount).

When the binding mode between the cellulose fiber and the modifying compound is an ionic bond, the "molecular weight of the modifying compound" in the above formula A means that the modifying compound is a primary amine, secondary amine or tertiary amine. In the case of a class amine, it refers to the "molecular weight of the entire modifying compound".
On the other hand, when the bonding mode between the cellulose fiber and the modifying compound is an amide bond, in the above formula A, the "molecular weight of the modifying compound" means that the modifying compound is a primary amine or a secondary amine. , “(molecular weight of the entire compound having a modifying group) −18”.

[Preparation of anion-modified cellulose fibers]
Preparation Example 1 (coniferous oxidized pulp)
Bleached kraft pulp of softwood (manufactured by Fletcher Challenge Canada, trade name "Machenzie", 650 ml of CSF) was used as the natural cellulose fiber. As TEMPO, a commercial product (manufactured by ALDRICH, Free radical, 98% by mass) was used. As sodium hypochlorite, a commercial product (manufactured by Wako Pure Chemical Industries, Ltd.) was used. As sodium bromide, a commercial product (manufactured by Wako Pure Chemical Industries, Ltd.) was used.

First, 100 g of bleached softwood kraft pulp fiber is sufficiently stirred with 9900 g of ion-exchanged water, and then 1.6 g of TEMPO, 10 g of sodium bromide, and 28.4 g of sodium hypochlorite are added in this order to 100 g of the pulp mass. added. Using pH stat titration with an automatic titrator (manufactured by Toa DKK Co., Ltd., trade name: AUT-701), 0.5 M sodium hydroxide was added dropwise under sufficient stirring to maintain the pH at 10.5. After the reaction was carried out for 120 minutes (20° C.), the dropwise addition of sodium hydroxide was stopped to obtain oxidized pulp. The obtained oxidized pulp was thoroughly washed with deionized water until the conductivity of the filtrate measured by a compact electrical conductivity meter (LAQUAtwin EC-33B, manufactured by Horiba, Ltd.) was 200 μs/cm or less, and then dehydrated. to obtain anion-modified cellulose fibers with a solid content of 34.6%. The anion-modified cellulose fibers had an average fiber diameter of 40 μm, an average fiber length of 2022 μm, and a carboxy group content of 1.56 mmol/g.

(Compound with modifying group)
As a compound having a modifying group for introducing a modifying group into the above anion-modified cellulose fibers, the following was used.
Dodecylamine, oleylamine, stearylamine, dihexylamine and trihexylamine: all commercially available reagents Propylamine, dipropylamine, triethylamine: all commercially available reagents EOPO amine: amine obtained in Comparative Production Example 1 shown below

Comparative Production Example 1 (Production of amine having an EO/PO copolymer moiety (EOPO amine))

Production Example 1 (Production of amine having an EO/PO copolymer moiety (EOPO amine))
132 g (1 mol) of propylene glycol tertiary butyl ether was charged in a 1 L autoclave, heated to 75° C., 1.2 g of flaky potassium hydroxide was added and stirred until dissolved. Next, 1541 g of ethylene oxide (EO) and 35 g of propylene oxide (PO) were reacted at 110° C. and 0.34 MPa, and then 7.14 g of magnesium silicate (manufactured by Dallas Group, trade name: Magnesol 30/40) was added. 0.16 g of di-tertiary-butyl-p-cresol was added to the resulting product, mixed, and then filtered to obtain a polyether that was an EO/PO copolymer. rice field.

On the other hand, a 1.250 mL tubular reactor filled with a catalyst of nickel oxide/copper oxide/chromium oxide (molar ratio: 75/23/2) (Wako Pure Chemical Industries, Ltd.) was charged with the polyether obtained above (8. 4 mL/min), ammonia (12.6 mL/min) and hydrogen (0.8 mL/min) were fed respectively. The vessel temperature was maintained at 190° C. and the pressure at 14 MPa. The crude effluent from the vessel was then distilled off at 70° C. and 3.5 mmHg for 30 minutes. 200 g of the resulting aminated polyether and 93.6 g of 15% aqueous hydrochloric acid solution were charged to a flask and the reaction mixture was heated at 100° C. for 3.75 hours to cleave the tertiary butyl ether with acid. The product was then neutralized with 144 g of 15% aqueous potassium hydroxide solution. The neutralized product was then distilled off under reduced pressure at 112° C. for 1 hour and filtered to obtain a monoamine having an EO/PO copolymer moiety represented by formula (i). In the obtained monoamine, the EO/PO copolymerization part and the amine were directly bonded, and _R1 in formula (i) was a hydrogen atom.

The molecular weight of the amine copolymerization part is 1541 [EO molecular weight (44) × EO addition mole number (35)] + 464 [PO molecular weight (58) × PO addition mole number (8.0)] + 58 [in the starting material PO partial molecular weight (propylene glycol)] = 2063
was rounded to 2000.

Preparation Example 2 (Hydrophobic-modified cellulose fiber using the anion-modified cellulose fiber of Preparation Example 1)
Into a beaker equipped with a magnetic stirrer and a stirring bar, 0.15 g of the anion-modified cellulose fibers obtained in Preparation Example 1 was charged in absolute dry mass. Subsequently, dodecylamine was charged in an amount corresponding to 1 mol of amino group per 1 mol of carboxy group of the anion-modified cellulose fiber, and dissolved in 75 g of MEK as a solvent. The reaction solution was reacted at room temperature (25° C.) for 1 hour to obtain an MEK suspension of hydrophobically modified cellulose fibers in which amino groups were bonded to anion-modified cellulose fibers (solid content: 0.2% by mass).

Example 1
The MEK suspension of the hydrophobically modified cellulose fibers obtained in Preparation Example 2 was stirred with a homogenizer (manufactured by Primix, trade name: TK Robomix) at 5000 rpm for 5 minutes, and then stirred with a high-pressure homogenizer (manufactured by Yoshida Kikai Co., Ltd.). , trade name: NanoVita L-ES) at 100 MPa for 10 passes. By this treatment, a dispersion (solid content: 0.2% by mass) of finely divided hydrophobically modified cellulose fibers dispersed in MEK was obtained.

Examples 2 to 5 (change of compounds having modifying groups)
Except for using each compound shown in Table 1 instead of dodecylamine as a compound having a modifying group, the same treatment as in Preparation Example 2 and Example 1 was performed to obtain a dispersion of finely divided hydrophobically modified cellulose fibers (solid content of 0.2% by weight) was obtained.

Example 6 (Modification/dispersion at high content)
The same treatment as in Preparation Example 2 and Example 5 was performed except that the amount of solvent in Preparation Example 2 was changed from 75 g to 30 g to obtain a dispersion of finely divided hydrophobically modified cellulose fibers (solid content: 0.5% by mass). ).

Example 7 (change of solvent type)
The same treatment as in Preparation Example 2 and Example 5 was performed except that the type of solvent in Preparation Example 2 was changed from MEK to DMF, and a dispersion of finely divided hydrophobically modified cellulose fibers (solid content: 0.2 mass %) was obtained. The average fiber diameter of this miniaturized hydrophobically modified cellulose fiber was 2.3 nm, and the average fiber length was 539 nm.

Comparative Examples 1 to 4 (change of compound type having a modifying group)
The same treatments as in Preparation Example 2 and Example 1 were performed except that the type of compound having a modifying group in Preparation Example 2 was changed from dodecylamine to the compounds shown in Table 2 to obtain a dispersion of finely divided hydrophobically modified cellulose fibers. (solid content 0.2% by mass) was obtained. The amount of the compound having a modifying group in Comparative Example 4 was an amount corresponding to 0.13 mol of amino group per 1 mol of carboxy group of the anion-modified cellulose fiber.

The properties of the resulting finely divided hydrophobically modified cellulose fibers were evaluated according to the method of Test Example 1 below. The results are shown in Tables 1-2.

Test Example 1 (dispersion stability test)
The obtained dispersion of finely divided hydrophobically modified cellulose fibers was allowed to stand at room temperature for 1 day, and the transparency and the presence or absence of precipitates were visually confirmed and evaluated based on the following evaluation criteria.
Evaluation A: Transparent state or slightly cloudy state, no precipitate Evaluation B: Partial precipitation confirmed Evaluation C: Complete separation, total amount precipitated Dispersion stability is evaluated in the order of A>B>C The dispersion stability A indicates excellent dispersion stability, and the dispersion stability B indicates dispersion stability to the extent that practical use is not hindered.

From Tables 1 and 2, by selecting an amine having a series and an alkyl chain length within the range of the present invention as a compound having a modifying group, it is possible to obtain good results from pulp raw materials regardless of the fiber length of raw cellulose and the type of solvent. It has been found that it is possible to prepare dispersions of finely divided, hydrophobically modified cellulose fibers dispersed in Moreover, compared to the case of using a quaternary ammonium salt as a compound having a modifying group, when using the specific primary to tertiary amines used in this example as a compound having a modifying group, the obtained Although the dispersibility of the finely divided hydrophobically modified cellulose fibers was expected to be low, it was found that the dispersibility of the finely divided hydrophobically modified cellulose fibers obtained according to the method of the present invention was surprisingly excellent. rice field.
On the other hand, as shown in Comparative Examples 1 to 4, when an amine having a short chain length of a hydrocarbon group or a polymeric amine having a limited amine salification rate is selected, dispersion stability and The nanodispersibility was found to be low.

Since the finely divided hydrophobically modified cellulose fibers obtained by the production method of the present invention have high dispersibility in organic solvents, the dispersion and resin composition containing the finely divided hydrophobically modified cellulose fibers are Transparent resin materials, 3D modeling materials, cushion materials, repair materials, adhesives, adhesives, sealants, heat insulating materials, sound absorbing materials, artificial leather materials, paints, electronic materials, packaging materials, tires, automobile parts, fiber composite materials It can be suitably used as a mechanical strength improver for various resin products such as.

Claims (6)

A step of finely treating hydrophobically modified cellulose fibers having an average fiber diameter of 1 μm or more and 300 μm or less, which are obtained by binding a compound having a modifying group to an anionic group of anion-modified cellulose fibers, in an organic solvent using a high-pressure homogenizer. , a method for producing a finely divided hydrophobically modified cellulose fiber, wherein the compound having the modifying group is one or more amines selected from the group consisting of amines represented by the following general formulas (1) to (3), A method for producing miniaturized hydrophobically modified cellulose fibers, wherein the total mass of modifying groups in the hydrophobically modified cellulose fibers is 1 part by mass or more and 200 parts by mass or less per 100 parts by mass of cellulose fibers.
_NH2 - ^R1 (1)
NH—R ² R ^2′ (2)
NR ³ R ^3′ R ^3″ (3)
[R ¹ in the general formula (1) is a linear or branched saturated or unsaturated hydrocarbon group having 6 to 30 carbon atoms, and R ² and R ^2′ in the general formula (2) are the same or may be different, R ² and R ^2' are linear or branched saturated or unsaturated hydrocarbon groups having a total carbon number of 8 or more and 40 or less, and R ³ and R in general formula (3) ^3′ and R ^3″ may be the same or different, and each of R ³ , R ^3′ and R ^3″ is a linear or branched saturated or unsaturated group having a total carbon number of 9 or more and 50 or less. It is a hydrocarbon group. ] 2. The production method according to claim 1, wherein the compound having the modifying group binds to the anionic group of the anion-modified cellulose fiber via an ionic bond and/or a covalent bond. The production method according to claim 1 or 2, wherein the anionic group contains one or more groups selected from the group consisting of a carboxy group, a phosphoric acid group and a sulfonic acid group. A method for producing a resin composition, comprising the step of mixing the finely divided hydrophobically modified cellulose fibers produced by the production method according to any one of claims 1 to 3 with a resin. Claim 4, wherein the resin is one or more selected from the group consisting of olefin resins, polyurethane resins, polycarbonate resins, (meth)acrylic resins, epoxy resins, phenolic resins, phenoxy resins, vinyl resins and rubber resins. A method for producing the resin composition according to 1. 6. A method for producing a resin molded product obtained by molding the resin composition produced by the method for producing a resin composition according to claim 4 or 5.