JP7712834B2 - Thiol compound-containing composition - Google Patents

Description

The present invention relates to a thiol compound-containing composition and a method for producing the same.

Traditionally, plastic materials derived from petroleum, a finite resource, have been widely used, but in recent years, technologies with less impact on the environment have come into the spotlight. Against this technological background, materials made from cellulose fibers, a naturally occurring biomass that exists in great quantities, and particularly fine cellulose fibers, have been attracting attention due to their significantly improved mechanical properties.

Patent Document 1 describes a composition characterized by containing cellulose nanofibers, a resin binder, and/or an organic compound having a reactive group, and discloses that the resin binder is at least one of a hydroxyl group (-OH), a carboxyl group (-COOH), an amino group (-NH ₂ ), and a thiol group (-SH) and/or a derivative thereof, and/or an organic compound having a double bond.

JP 2015-160870 A

However, in Patent Document 1, the dispersibility of the cellulose fibers in the resin binder is not sufficient. It is believed that the use of a thiol compound-containing composition containing highly dispersible cellulose fibers leads to excellent transparency of the resulting resin composition, as well as improved strength and impact resistance.

The present invention relates to a thiol compound-containing composition that has excellent dispersibility and transparency for cellulose fibers.

The present invention relates to the following [1] to [3].
[1] A thiol compound-containing composition containing a thiol compound and a modified cellulose fiber, wherein the modified cellulose fiber has cellulose type I crystals and is one or more types selected from the group consisting of the following cellulose fiber (A) and cellulose fiber (B).
Modified cellulose fiber (A) Modified cellulose fiber having a modifying group bonded to the ionic group of a cellulose fiber containing an ionic group Modified cellulose fiber (B) Modified cellulose fiber having a modifying group bonded to a hydroxy group of a cellulose fiber [2] A method for producing a thiol compound-containing composition according to the above [1], comprising a step of micronizing modified cellulose fibers having an average fiber length of more than 500 nm in a thiol compound, wherein the modified cellulose fibers subjected to the micronization step are one or more types selected from the group consisting of the following modified cellulose fibers (A) and modified cellulose fibers (B).
Modified cellulose fiber (A): A modified cellulose fiber in which a modifying group is bonded to the ionic group of a cellulose fiber containing an ionic group. Modified cellulose fiber (B): A modified cellulose fiber in which a modifying group is bonded to the hydroxyl group of a cellulose fiber. [3] A polymerization product of the thiol compound-containing composition described in [1] above.

The present invention provides a thiol compound-containing composition that has excellent dispersibility and transparency for cellulose fibers.

As a result of intensive research into the above-mentioned problems, the inventors of the present invention have newly discovered that by blending a specific modified cellulose fiber with a thiol compound, a thiol compound-containing composition with excellent dispersibility of the modified cellulose fiber can be obtained. Although the mechanism behind this is unclear, it is presumed that this is because the specific modified cellulose has high dispersibility in thiol compounds.

[Thiolic acid-containing composition]
The thiol compound-containing composition of the present invention contains a thiol compound and modified cellulose fibers.

[Thiol compounds]
The thiol compound is not particularly limited as long as it is a compound containing a thiol group (-SH), but from the viewpoint of dispersibility, a polythiol compound having two or more thiol groups is preferred. The polythiol compound may be linear, branched, or cyclic, and may have other functional groups, such as functional groups having active hydrogen, such as amine groups and hydroxyl groups, as long as it has two or more thiol groups (-SH). Examples of such polythiol compounds with two or more functionalities include 1,2-propanedithiol, 1,3-propanedithiol, 1,2,3-propanetrithiol, 1,2,3-tris(mercaptomethylthio)propane, 1,2,3-tris(2-mercaptoethylthio)propane, 1,2,3-tris(3-mercaptopropylthio)propane, 2,5-bis(mercaptomethyl)-1,4-dithiane, pentaerythritol tetrakismercaptoacetate, pentaerythritol tetrakismercaptopropionate, trimethylolpropane trismercaptoacetate, trimethylolpropane trismercaptopropionate, 1,2,3-trimercaptopropane, 2,3-dimercapto-1-propanol, bis(mercaptomethyl)-1,4-dithiane, bis(mercaptoethyl)sulfide, bis(mercaptoethyl)disulfide, 1,2-bis(mercaptoethylthio)-3-mercaptopropane, 2,5-dimercaptomethyl-1,4-dithiane, ethylene glycol bis(3-mercaptopropionate), 4,6-bis(mercaptomethylthio)-1,3-dithiane, bis(2-mercaptoethyl)sulfide, 4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane, 5,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, etc. These may be used alone or in combination of two or more.
Further examples include polyhydric alcohol esters of mercaptocarboxylic acids, esters of monomercaptan monohydric alcohols containing polycarboxylic acids, compounds having mercaptan groups at the ends of polypropylene glycol or polyethylene glycol chains, other ester-containing polymercaptans described in U.S. Patent No. 4,126,505, propoxylated ether polythiols described in U.S. Patent No. 4,092,293, polymercaptan-containing resins having a molecular weight of 750 to 7000 described in U.S. Patent No. 3,258,495, dimercaptopolysulfide polymers described in U.S. Patent No. 2,919,255, and thiolated oligomer triglycerides. Among these, polyhydric alcohol esters of mercaptocarboxylic acids are preferred. Preferred examples of the polyhydric alcohol ester of a mercaptocarboxylic acid include trimethylolpropane trimercaptopropionate, trimethylolpropane trithiogluconate, pentaerythritol tetramercaptopropionate, pentaerythritol tetrathiogluconate, and trimethylolethane trimercaptopropionate.
The polythiol compound can be reacted with an isocyanate to produce a thiourethane resin.

The average molecular weight of the thiol compound is preferably 100 or more, more preferably 150 or more, and even more preferably 200 or more, from the viewpoint of dispersibility. Also, from the viewpoint of dispersibility, it is preferably 5000 or less, more preferably 3000 or less, and even more preferably 1000 or less. In this specification, the average molecular weight of the thiol compound is a mass average molecular weight.

[Modified cellulose fibers]
The modified cellulose fiber contained in the thiol compound-containing composition of the present invention is one or more types selected from the group consisting of the following modified cellulose fiber (A) and modified cellulose fiber (B), and preferably contains one or more modifying groups selected from the group consisting of (a) a hydrocarbon group and (b) a polymer group.
Modified cellulose fiber (A): Modified cellulose fiber in which a modifying group is bonded to the ionic group of a cellulose fiber containing an ionic group. Modified cellulose fiber (B): Modified cellulose fiber in which a modifying group is bonded to the hydroxyl group of a cellulose fiber.

From the viewpoint of reducing the environmental load, it is preferable to use natural cellulose fibers as the raw material for the modified cellulose fibers. Examples of natural cellulose fibers include wood pulps such as coniferous pulp and broadleaf pulp; cotton pulps such as cotton linters and cotton lint; non-wood pulps such as straw pulp and bagasse pulp; bacterial cellulose, etc., and these can be used alone or in combination of two or more.

The average fiber diameter and average fiber length of the raw cellulose fibers are not particularly limited. The average fiber diameter is, for example, preferably 1 μm or more from the viewpoint of availability and cost reduction, and from the same viewpoint, preferably 100 μm or less. The average fiber length is, for example, preferably 1000 μm or more from the viewpoint of availability and cost reduction, and from the same viewpoint, preferably 10000 μm or less. The average fiber diameter and average fiber length of the raw cellulose fibers can be measured by the method described in the Examples below.

<Modified cellulose fiber (A)>
The modified cellulose fiber (A) in the present invention is a modified cellulose fiber obtained by bonding a modifying group to the ionic group of a cellulose fiber containing an ionic group.

(ionic group)
The cellulose fibers containing ionic groups are cellulose fibers that have been modified so as to contain ionic groups.

Examples of the ionic group include anionic groups and cationic groups. In this specification, cellulose fibers having anionic groups are also referred to as "anion-modified cellulose fibers". Examples of the anionic group include a carboxy group, a sulfonic acid group, and a phosphate group, and examples of the cationic group include a group having an onium such as ammonium, phosphonium, or sulfonium in the group. From the viewpoint of the efficiency of introduction into the modified cellulose fiber (A), the ionic group is preferably an anionic group, and the anionic group is more preferably a carboxy group. From the viewpoint of introducing a modifying group, the anion-modified cellulose fiber is preferably an oxidized cellulose fiber or a carboxymethylated cellulose fiber, and more preferably a cellulose fiber in which the C6 position of the cellulose structural unit is a carboxy group.

When the ionic group is an anionic group, the counter ion of the anionic group is one or more selected from the group consisting of metal ions and protons. The metal ion is preferably a monovalent cation, such as a lithium ion, a sodium ion, or a potassium ion. From the viewpoint of reaction efficiency with the modified cellulose fiber, a proton is preferred.

The content of ionic groups in cellulose fibers containing ionic groups is preferably 0.1 mmol/g or more, more preferably 0.4 mmol/g or more, and even more preferably 0.6 mmol/g or more, from the viewpoint of stable micronization and introduction of modifying groups. From the same viewpoint, the upper limit is preferably 3.0 mmol/g or less, more preferably 2.5 mmol/g or less, and even more preferably 2.0 mmol/g or less. When the ionic groups are anionic groups, the content of the anionic groups can be measured by the method described in the Examples below.

(modifying group)
In the modified cellulose fiber (A), a modifying group is bonded to the ionic group of the cellulose fiber containing an ionic group. The bonding mode here includes an ionic bond and a covalent bond (e.g., an amide bond, an ester bond, a urethane bond, etc.).

The modifying group in the modified cellulose fiber (A) preferably contains one or more modifying groups selected from the group consisting of (a) a hydrocarbon group and (b) a polymer group. These groups may be introduced into the modified cellulose fiber (A) either alone or in combination of two or more. From the viewpoint of dispersibility, it is preferable that (a) a hydrocarbon group and (b) a polymer group are introduced into the modified cellulose fiber (A).

The number of carbon atoms in the hydrocarbon group as the modifying group is preferably 1 or more, more preferably 2 or more, and even more preferably 3 or more, from the viewpoint of improving dispersibility and transparency, and from the same viewpoint, is preferably 30 or less, more preferably 25 or less, even more preferably 24 or less, even more preferably 20 or less, and even more preferably 18 or less. Note that the number of carbon atoms in the hydrocarbon group means the number of carbon atoms in one modifying group, unless otherwise specified.

Specific examples of chain saturated hydrocarbon groups include methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, tert-butyl, isobutyl, pentyl, tert-pentyl, isopentyl, hexyl, isohexyl, heptyl, octyl, 2-ethylhexyl, nonyl, decyl, dodecyl, tridecyl, tetradecyl, octadecyl, docosyl, and octacosanyl groups.

Specific examples of chain unsaturated hydrocarbon groups include ethylene, propylene, butene, isobutene, isoprene, pentene, hexene, heptene, octene, nonene, decene, dodecene, tridecene, tetradecene, and octadecene groups.

Specific examples of cyclic saturated hydrocarbon groups include cyclopropane, cyclobutyl, cyclopentane, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, cyclododecyl, cyclotridecyl, cyclotetradecyl, and cyclooctadecyl groups.

The aromatic hydrocarbon group is, for example, selected from the group consisting of an aryl group and an aralkyl group. In the aryl group and the aralkyl group, the aromatic ring itself may be substituted or unsubstituted.

Examples of aryl groups include phenyl groups, naphthyl groups, anthryl groups, phenanthryl groups, biphenyl groups, diphenyl groups, triphenyl groups, terphenyl groups, and groups in which these groups are substituted with the substituents described below.

Examples of aralkyl groups include benzyl groups, phenethyl groups, phenylpropyl groups, phenylpentyl groups, phenylhexyl groups, phenylheptyl groups, phenyloctyl groups, and groups in which the aromatic group of these groups is further substituted with a substituent. Other examples of aromatic hydrocarbon groups include diphenylmethyl groups, triphenylmethyl groups, and groups in which the aromatic group of these groups is further substituted with a substituent.

When the modifying group is a hydrocarbon group and the hydrocarbon group has a substituent, the substituent may be, for example, a linear or branched alkoxy group having 1 to 6 carbon atoms; a linear or branched alkoxycarbonyl group having 1 to 6 carbon atoms in the alkoxy group; a halogen atom such as a bromine atom or an iodine atom; an acyl group having 1 to 6 carbon atoms; an aralkyl group; an aralkyloxy group; an alkylamino group having 1 to 6 carbon atoms; a dialkylamino group having 1 to 6 carbon atoms in the alkyl group; a hydroxyl group, an ether, an amide, or the like. The various hydrocarbon groups mentioned above may themselves be bonded to another hydrocarbon group as a substituent.

A polymer group is a functional group containing a polymer structure. From the viewpoint of improving dispersibility, the molecular weight of the polymer group is preferably 100 or more, more preferably 200 or more, more preferably 300 or more, even more preferably 400 or more, even more preferably 600 or more, even more preferably 1,000 or more, and even more preferably 1,500 or more. From the same viewpoint, it is preferably 10,000 or less, more preferably 7,000 or less, even more preferably 5,000 or less, even more preferably 4,000 or less, even more preferably 3,500 or less, and even more preferably 2,500 or less.

From the viewpoint of improving dispersibility, the polymer group is preferably a functional group having a repeating structure linked by a structure having an oxygen atom, more preferably a functional group having a repeating structure linked by an oxygen atom, such as a polyoxyalkylene structure (alkylene oxide chain) or a polysiloxane structure (silicone chain), more preferably a polyoxyalkylene structure, and even more preferably an alkoxypolyoxyalkylene group.

From the viewpoint of ensuring the chemical stability of the modified cellulose fiber and the dispersion stability as a filler, the polyoxyalkylene structure is preferably a (co)polymer structure of one or more oxyalkylenes selected from oxyalkylenes having 2 to 8 carbon atoms, more preferably a (co)polymer structure of one or more oxyalkylenes selected from oxyalkylenes having 2 to 4 carbon atoms, even more preferably a (co)polymer structure of one or two oxyalkylenes selected from ethylene oxide (EO) and propylene oxide (PO), and even more preferably a copolymer structure in which ethylene oxide (EO) and propylene oxide (PO) are polymerized randomly or in a block form.

An example of a group containing a copolymer structure ((EO/PO) copolymer structure) in which ethylene oxide (EO) and propylene oxide (PO) are polymerized randomly or in a block form is the group shown in the following formula (i'), which can be introduced using a compound of the following formula (i).

[In the formula, ^R1 represents a hydrogen atom, a linear or branched alkyl group having 1 to 6 carbon atoms, or an aminoalkyl group thereof, EO and PO are present randomly or in a block form, a is a positive number indicating the average number of moles of EO added, and b is a positive number indicating the average number of moles of PO added. Here, "the aminoalkyl group" means a group in which one of the hydrogen atoms constituting the linear or branched alkyl group having 1 to 6 carbon atoms is substituted with an amino group. In formula (i), an alkylene group having 1 to 3 carbon atoms may be present between the amino group and EO or PO.]

When R ¹ is a linear or branched alkyl group having 1 to 6 carbon atoms, the alkyl group is preferably a methyl group, an ethyl group, an n-propyl group, or a sec-propyl group. ^{R 1} may be a hydrogen atom.

From the viewpoint of improving dispersibility and transparency, a is preferably 1 or more, more preferably 3 or more, even more preferably 6 or more, even more preferably 11 or more, even more preferably 15 or more, even more preferably 20 or more, even more preferably 25 or more, even more preferably 30 or more, even more preferably 40 or more. From the same viewpoint, a is preferably 100 or less, more preferably 90 or less, even more preferably 70 or less, even more preferably 60 or less, even more preferably 50 or less.

From the viewpoint of improving dispersibility and transparency, b is preferably 1 or more, more preferably 2 or more, and even more preferably 3 or more. From the same viewpoint, b is preferably 50 or less, more preferably 40 or less, even more preferably 30 or less, even more preferably 25 or less, even more preferably 20 or less, even more preferably 15 or less, even more preferably 10 or less, and even more preferably 5 or less.

Examples of the alkylene group having 1 to 3 carbon atoms include a methylene group, an ethylene group, and a propylene group.

The PO content (mol%) in the (EO/PO) copolymerization portion can be calculated based on the above a and b, specifically, it can be obtained by b×100/(a+b). From the viewpoint of further improving dispersibility, the PO content is preferably 1 mol% or more, more preferably 3 mol% or more, and even more preferably 5 mol% or more. From the same viewpoint, it is preferably 100 mol% or less, more preferably 90 mol% or less, even more preferably 85 mol% or less, even more preferably 75 mol% or less, even more preferably 60 mol% or less, even more preferably 50 mol% or less, even more preferably 40 mol% or less, even more preferably 30 mol% or less, and even more preferably 10 mol% or less.

From the viewpoint of improving dispersibility, the molecular weight of the (EO/PO) copolymer structure is preferably 100 or more, more preferably 200 or more, even more preferably 300 or more, even more preferably 400 or more, even more preferably 500 or more, even more preferably 600 or more, even more preferably 1,000 or more, even more preferably 1,500 or more. From the same viewpoint, it is preferably 10,000 or less, more preferably 7,000 or less, even more preferably 5,000 or less, even more preferably 4,000 or less, even more preferably 3,500 or less, even more preferably 2,500 or less.

The amine having an EO/PO copolymer structure represented by formula (i) is a modifying compound for introducing the modifying group represented by formula (i'), and details of the amine are described, for example, in Japanese Patent No. 6105139.

The amine having an EO/PO copolymer structure (also referred to as "EOPO amine") may be, for example, a commercially available product. Specific examples thereof include Jeffamine M-2070, Jeffamine M-2005, Jeffamine M-2095, Jeffamine M-1000, Jeffamine M-600, Jeffamine M-3085, Jeffamine ED-600, Jeffamine ED-900, Jeffamine ED-2003, Jeffamine D-230, Jeffamine D-400, Jeffamine D-20 ... Examples include D-4000, Jeffamine T-3000, and Jeffamine T-5000.

The average bond amount of the modifying group in the modified cellulose fiber (A) is preferably 0.01 mmol/g or more, more preferably 0.05 mmol/g or more, even more preferably 0.1 mmol/g or more, even more preferably 0.3 mmol/g or more, and even more preferably 0.5 mmol/g or more, from the viewpoint of improving dispersibility. From the same viewpoint, it is preferably 3.0 mmol/g or less, more preferably 2.5 mmol/g or less, even more preferably 2.0 mmol/g or less, even more preferably 1.8 mmol/g or less, and even more preferably 1.5 mmol/g or less. When any two or more types of modifying groups are simultaneously introduced into the modified cellulose fiber (A) as modifying groups, it is preferable that the average bond amount of the modifying groups is within the above range in terms of the total amount of the modified groups introduced.

The introduction rate of the modifying group in the modified cellulose fiber (A) is preferably 10% or more from the viewpoint of dispersibility and transparency, and is preferably 99% or less from the viewpoint of obtaining a molded product with excellent mechanical strength. When any two or more types of modifying groups are simultaneously introduced as the modifying group, it is preferable that the introduction rate is within the above range, provided that the total introduction rate does not exceed the upper limit of 100%.

The average bond amount and introduction rate of the modifying group can be adjusted by the amount and type of compound for introducing the modifying group, i.e., the modification compound, added, reaction temperature, reaction time, type of solvent, etc. The average bond amount (mmol/g) and introduction rate (%) of the modifying group refer to the amount and ratio of the modifying group introduced (bonded) to the ionic group in the modified cellulose fiber (A). For example, when the ionic group is anionic, the average bond amount and introduction rate of the modifying group are calculated by the method described in the Examples below.

(Production method of modified cellulose fiber (A))
The modified cellulose fiber (A) can be produced according to a known method without any particular limitation, as long as a modifying group can be introduced into the ionic group of the cellulose fiber containing an ionic group. For example, when the ionic group is a carboxy group, the modified cellulose fiber (A) can be produced by referring to paragraphs 0017 to 0106 of JP 2018-024967 A. In addition, a carboxy group can be introduced into the cellulose fiber by reacting a halogenated acetic acid such as chloroacetic acid, an acid anhydride of a dicarboxylic acid compound such as maleic anhydride, succinic anhydride, phthalic anhydride, and adipic anhydride, an imide of an acid anhydride of a compound having a carboxy group, a derivative of an acid anhydride of a compound having a carboxy group, or the like with the cellulose fiber. When the ionic group is a sulfonic acid group, a method of introducing a sulfonic acid group into the cellulose fiber includes a method of adding sulfuric acid to the cellulose fiber and heating it. When the ionic group is a phosphate group, the method of introducing the phosphate group into the cellulose fiber includes a method of mixing a powder or an aqueous solution of phosphoric acid or a phosphoric acid derivative with cellulose fiber in a dry or wet state, and a method of adding an aqueous solution of phosphoric acid or a phosphoric acid derivative to a dispersion of cellulose fiber. A method of introducing a modifying group includes a method of mixing a compound having a modifying group with cellulose fiber having a phosphate group. When the ionic group is a cationic group, a method of introducing a cationic group into the cellulose fiber includes a method of treating the cellulose fiber with a cationizing agent in the presence of an alkali. In addition, when producing the modified cellulose fiber (A), the aspect ratio reduction treatment and the fineness process in JP 2018-024967 A can be omitted.

<Modified cellulose fiber (B)>
The modified cellulose fiber (B) in the present invention is a modified cellulose fiber in which a modifying group is bonded to a hydroxy group of a cellulose fiber.

(modifying group)
In the modified cellulose fiber (B), the cellulose fiber and the modifying group are bonded via an ether bond. In this specification, the term "bonded via an ether bond" refers to a state in which the modifying group reacts with the hydroxyl group of the cellulose fiber to form an ether bond.

The modifying group in the modified cellulose fiber (B) is preferably a hydrocarbon group which may have a substituent. Here, examples of the hydrocarbon group which may have a substituent include saturated or unsaturated linear or branched aliphatic hydrocarbon groups, aromatic hydrocarbon groups such as a phenyl group, and alicyclic hydrocarbon groups such as a cyclohexyl group. Examples of the substituent in the hydrocarbon group which may have a substituent in the present invention include halogen atoms, oxyalkylene groups such as an oxyethylene group, and hydroxyl groups.

A preferred embodiment of such a modified cellulose fiber (B) (referred to as "embodiment 1") is, for example, a cellulose fiber having a cellulose type I crystal structure in which one or more modifying groups selected from a modifying group represented by the following general formula (1) and a modifying group represented by the following general formula (2) are bonded to the cellulose fiber via an ether bond.
-CH ₂ -CH(R ⁰ )-R ¹ (1)
-CH ₂ -CH(R ⁰ )-CH ₂ -(OA) _n -O-R ¹ (2)
[In the formulas, ^R0 in general formula (1) and general formula (2) represents a hydrogen atom or a hydroxyl group, ^R1 each independently represents a hydrogen atom or a hydrocarbon group having 1 or more carbon atoms, preferably 3 to 30 carbon atoms, n in general formula (2) represents a number of 0 to 50, and A represents a linear or branched divalent saturated hydrocarbon group having 1 to 6 carbon atoms.]

A specific example of aspect 1 is a modified cellulose fiber represented by the following general formula (3):

[In the formula, R may be the same or different and represents hydrogen or a modifying group selected from the modifying group represented by the general formula (1) and the modifying group represented by the general formula (2). However, this does not include the case where all R are simultaneously hydrogen. m is preferably an integer of 20 to 3000.]

The modified cellulose fiber (B) represented by the general formula (3) has a repeating structure of cellulose units to which the modifying group has been introduced. From the viewpoint of dispersibility, the number of repeating units, m, in the general formula (3), is preferably an integer of 20 or more and 3000 or less.

(Optionally substituted hydrocarbon group)
In the modified cellulose fiber (B) of embodiment 1, one or more modifying groups selected from the modifying groups represented by the above general formula (1) and the following general formula (2) are introduced alone or in any combination. Even if the modifying group introduced is any one of the above groups of modifying groups, the same modifying group may be introduced in each group of modifying groups, or two or more types may be introduced in combination.

From the viewpoint of dispersibility, R ⁰ in general formula (1) and general formula (2) is preferably a hydroxy group.

From the viewpoint of dispersibility, the number of carbon atoms in R ¹ in general formula (1) is preferably 25 or less. Specific examples include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a 2-ethylhexyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a hexadecyl group, an octadecyl group, an isooctadecyl group, an icosyl group, a triacontyl group, a phenyl group, and a methylphenyl group.

The number of carbon atoms in ^R1 in the general formula (2) is preferably 4 or more from the viewpoint of dispersibility, and is preferably 27 or less from the viewpoint of availability and improving reactivity. Specific examples include the same as ^R1 in the general formula (1) described above.

In general formula (2), A forms an oxyalkylene group with the adjacent oxygen atom. From the viewpoints of availability and cost, the number of carbon atoms in A is preferably 2 or more, and from the same viewpoints, preferably 4 or less. Specific examples include a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, and a hexylene group.

In general formula (2), n represents the number of moles of alkylene oxide added. From the viewpoints of dispersibility, availability, and cost, n is preferably 3 or more, and from the same viewpoints, n is preferably 40 or less.

From the viewpoint of dispersibility, the combination of A and n in general formula (2) is preferably such that A is a linear or branched divalent saturated hydrocarbon group having 2 to 3 carbon atoms, and n is a number between 0 and 20.

Specific examples of the modifying group represented by general formula (1) include, for example, pentyl, hexyl, octyl, 2-ethylhexyl, decyl, dodecyl, tetradecyl, hexadecyl, octadecyl, isooctadecyl, icosyl, propylhydroxyethyl, butylhydroxyethyl, pentylhydroxyethyl, hexylhydroxyethyl, heptylhydroxyethyl, octylhydroxyethyl, 2-ethylhexylhydroxyethyl, nonylhydroxyethyl, decylhydroxyethyl, undecylhydroxyethyl, dodecylhydroxyethyl, hexadecylhydroxyethyl, octadecylhydroxyethyl, isooctadecylhydroxyethyl, icosylhydroxyethyl, and triacontylhydroxyethyl.

Specific examples of the modifying group represented by general formula (2) include, for example, a 3-butoxy-2-hydroxypropyl group, a 3-hexoxyethyleneoxide-2-hydroxypropyl group, a 3-hexoxy-2-hydroxypropyl group, a 3-octoxyethyleneoxide-2-hydroxypropyl group, a 3-octoxy-2-hydroxypropyl group, a 6-ethyl-3-hexoxy-2-hydroxypropyl group, a 6-ethyl-3-hexoxyethyleneoxide-2-hydroxypropyl group, a 3-deoxyethyleneoxide-2-hydroxypropyl group, Examples of the alkylene oxide include 3-detoxyl-2-hydroxypropyl group, 3-undetoxyl-2-hydroxypropyl group, 3-undetoxyl-2-hydroxypropyl group, 3-dodetoxyl-2-hydroxypropyl group, 3-dodetoxyl-2-hydroxypropyl group, 3-hexadetoxyl-2-hydroxypropyl group, 3-hexadetoxyl-2-hydroxypropyl group, 3-octadetoxyl-2-hydroxypropyl group, and 3-octadetoxyl-2-hydroxypropyl group. The number of moles of alkylene oxide added may be 0 or more and 50 or less, and examples of the alkylene oxide having an oxyalkylene group such as the above-mentioned ethylene oxide include substituents having an added mole number of 10, 12, 13, and 20 moles.

(Molar Substitution (MS))
In the modified cellulose fiber (B) of embodiment 1, the molar amount (molar substitution degree: MS) of the modified group introduced per 1 mole of anhydrous glucose unit of cellulose cannot be generally limited depending on the type of the modified group, but from the viewpoint of dispersibility, it is preferably 0.0001 moles or more, more preferably 0.01 moles or more, and even more preferably 0.1 moles or more, and from the same viewpoint of having a cellulose I type crystal structure, it is preferably 1.5 moles or less, more preferably 1.2 moles or less, and even more preferably 1 mole or less. Here, when the bonded modifying group is composed of multiple types of modifying groups, the MS of the bonded modifying group is the sum of the MS of each modifying group. In this specification, the MS of the modified group in the modified cellulose fiber (B) can be measured according to the method described in the Examples below.

<Method for producing modified cellulose fiber (B)>
In the modified cellulose fiber (B) of the present invention, as described above, a modifying group, preferably a hydrocarbon group which may have the above-mentioned modifying group, is bonded to the cellulose fiber via an ether bond, and the introduction of the modifying group can be carried out according to a known method without any particular limitation. A specific example of a method for producing the modified cellulose fiber (B) of embodiment 1 will be described below.

(Method for producing modified cellulose fiber (B) of embodiment 1)
A specific example of the method for producing the modified cellulose fiber (B) of embodiment 1 is a method in which a specific compound is reacted with the raw cellulose fiber in the presence of a base.

In addition, from the viewpoint of reducing the number of manufacturing steps, pre-micronized cellulose fibers may be used as the raw cellulose fibers. In this case, the average fiber diameter is preferably 1 nm or more from the viewpoints of availability and cost. In addition, there is no particular upper limit, but from the viewpoint of handleability, it is preferably 500 nm or less.

(base)
The base is not particularly limited, but from the viewpoint of proceeding with the etherification reaction, one or more selected from the group consisting of alkali metal hydroxides, alkaline earth metal hydroxides, primary to tertiary amines, quaternary ammonium salts, imidazole and its derivatives, pyridine and its derivatives, and alkoxides are preferred. Specific examples include the bases described in paragraphs 0053 to 0058 of JP2017-053077A.

The amount of base is preferably 0.01 equivalents or more relative to the anhydrous glucose units of the raw cellulose fiber in order to promote the etherification reaction, and is preferably 10 equivalents or less in terms of production costs.

The mixing of the raw cellulose fibers and base may be carried out in the presence of a solvent. There are no particular limitations on the solvent, and examples of the solvent include water, isopropanol, t-butanol, dimethylformamide, toluene, methyl isobutyl ketone, acetonitrile, dimethyl sulfoxide, dimethylacetamide, 1,3-dimethyl-2-imidazolidinone, hexane, 1,4-dioxane, and mixtures thereof.

There are no particular limitations on the temperature or time for mixing the raw cellulose fiber and base, as long as they can be mixed uniformly.

Next, a modifying compound (also referred to as an "etherifying agent" in this specification), preferably a compound for introducing a hydrocarbon group that may have a substituent, is added to the mixture of the raw cellulose fiber and base obtained above, and the raw cellulose fiber is reacted with the compound. As such a compound, it is preferable to use a compound having a reactive cyclic structural group, and it is more preferable to use a compound having an epoxy group.

Examples of compounds to which the modifying group represented by general formula (1) can be bonded via an ether bond include the alkylene oxide compounds described in paragraphs 0079 to 0084 of JP 2017-053077 A.

Examples of compounds to which the modifying group represented by general formula (2) can be bonded via an ether bond include the glycidyl ether compounds described in paragraphs 0085 to 0091 of JP 2017-053077 A.

The amount of the modifying compound can be determined based on the desired introduction rate of the modifying group in the resulting modified cellulose fiber (B), but from the viewpoint of reactivity, it is preferably 0.01 equivalents or more relative to the anhydrous glucose units of the raw cellulose fiber, and from the viewpoint of production costs, it is preferably 10 equivalents or less.

(Etherification reaction)
The etherification reaction between the compound and the raw cellulose fiber can be carried out by mixing the two in the presence of a solvent. The solvent is not particularly limited, and the solvents exemplified as those usable in the presence of the base can be used. For details of the etherification reaction, refer to the descriptions in paragraphs 0070 to 0075 of JP 2017-053077 A.

The modified cellulose fiber (B) of embodiment 1 thus obtained may be subjected to a known micronization process, for example, a process using a high-pressure homogenizer in an organic solvent.

In either case of the modified cellulose fibers (A) and (B) above, the modified cellulose fibers can be used in the form of a dispersion, or the solvent can be removed from the dispersion by drying or other treatment to obtain dried powdery modified cellulose fibers, which can then be used. Here, "powdered" refers to a powdered form in which the modified cellulose fibers are aggregated, and does not mean cellulose particles.

Examples of powdered modified cellulose fibers include a dried product obtained by drying the cellulose fiber dispersion as is; a dried product pulverized by mechanical processing; a cellulose fiber dispersion pulverized by a known spray drying method; and a cellulose fiber dispersion pulverized by a known freeze drying method. The spray drying method is a method in which the cellulose fiber dispersion is sprayed in the air and dried.

<Characteristics of modified cellulose fibers>
The modified cellulose fiber has a cellulose type I crystal structure due to the use of natural cellulose fibers as a raw material. Cellulose type I refers to the crystalline form of natural cellulose, and cellulose type I crystallinity refers to the proportion of cellulose type I crystalline regions in the entire cellulose. The presence or absence of the cellulose type I crystal structure can be determined by the presence of a peak at 2θ=22.6° in X-ray diffraction measurement.

From the viewpoint of dispersibility, the cellulose I type crystallinity of the modified cellulose fiber is preferably 30% or more, more preferably 35% or more, even more preferably 40% or more, and even more preferably 45% or more. From the viewpoint of the cost of the cellulose raw material used, it is preferably 95% or less, more preferably 90% or less, even more preferably 85% or less, and even more preferably 80% or less. In this specification, the cellulose I type crystallinity of cellulose fibers, modified cellulose fibers, etc. is specifically measured by the method described in the Examples below.

From the viewpoint of improving production efficiency and mechanical properties, the average fiber length of the modified cellulose fiber is preferably 10 nm or more, more preferably 20 nm or more, and even more preferably 50 nm or more, while from the viewpoint of dispersibility, it is preferably 500 nm or less, more preferably 400 nm or less, and even more preferably 300 nm or less. The average fiber length of the modified cellulose fiber can be measured by the method described in the examples below.

From the viewpoint of improving production efficiency and mechanical properties, the average fiber diameter of the modified cellulose fiber is preferably 1 nm or more, more preferably 2 nm or more, and even more preferably 3 nm or more, and from the viewpoint of dispersibility, it is preferably 30 nm or less, more preferably 20 nm or less, even more preferably 10 nm or less, and even more preferably 5 nm or less. The average fiber diameter of the modified cellulose fiber can be measured by the method described in the examples below.

The average aspect ratio of the modified cellulose fiber is preferably 1 or more, more preferably 5 or more, even more preferably 8 or more, and even more preferably 35 or more, from the viewpoint of production efficiency and improvement of mechanical properties, and is preferably 100 or less, more preferably less than 100, even more preferably 80 or less, even more preferably 55 or less, and even more preferably 50 or less, from the viewpoint of dispersibility. The average aspect ratio of the modified cellulose fiber can be measured by the method described in the examples below.

The content of the thiol compound in the thiol compound-containing composition of the present invention is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more, from the viewpoint of containing the thiol compound. Also, from the viewpoint of containing the modified cellulose fiber, it is preferably 99.9% by mass or less, more preferably 99% by mass or less, and even more preferably 98% by mass or less.

The content of the modified cellulose fiber in the thiol compound-containing composition of the present invention is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and even more preferably 1% by mass or more, from the viewpoint of the expression of the effect of the modified cellulose fiber, and is preferably 50% by mass or less, more preferably 30% by mass or less, and even more preferably 10% by mass or less, from the viewpoint of dispersibility.

The mass ratio of modified cellulose fiber/thiol compound in the thiol compound-containing composition of the present invention is preferably 0.001 or more, more preferably 0.005 or more, and even more preferably 0.01 or more, from the viewpoint of expression of the effect of the modified cellulose fiber, and is preferably 0.3 or less, more preferably 0.2 or less, and even more preferably 0.1 or less, from the viewpoint of dispersibility.

When two or more types of modified cellulose fibers are used, the content of the modified cellulose fibers refers to the total amount, and when two or more types of thiol compounds are used, the content of the thiol compounds refers to the total amount. The content of modified cellulose fibers in the thiol compound-containing composition and the mass ratio of modified cellulose fiber/thiol compound use the cellulose fiber (equivalent amount) in the modified cellulose fiber, so as not to include the modifying group.

The thiol compound-containing composition of the present invention may optionally contain components such as plasticizers, fillers, pigments, thixotropic agents, process oils, reinforcing materials, aggregates, hardening accelerators, flame retardants, thickeners, leveling agents, polymerization catalysts, internal mold release agents, light stabilizers, UV absorbers, antioxidants, color inhibitors, and dyes. These other components may be used alone or in combination of two or more.

[Method for producing a thiol compound-containing composition]
The method for producing the thiol compound-containing composition of the present invention is not particularly limited, but a preferred example is a production embodiment that includes a step of micronizing modified cellulose fibers having an average fiber length of more than 500 nm in a thiol compound.

In this manufacturing embodiment, the modified cellulose fiber subjected to the micronization treatment is one or more selected from the group consisting of the modified cellulose fiber (A) and the modified cellulose fiber (B). In addition, from the viewpoint of dispersibility, it is preferable to use modified cellulose fiber whose average fiber length is shortened to within the range of 1 μm to 1000 μm as the modified cellulose fiber subjected to the micronization treatment. The average fiber length of such short fiber cellulose fiber is preferably 10 μm or more, more preferably 20 μm or more, even more preferably 30 μm or more, even more preferably 50 μm or more, and also preferably 1000 μm or less, more preferably 800 μm or less, even more preferably 500 μm or less, even more preferably 400 μm or less. In addition, the average fiber diameter is preferably 1 μm or more, more preferably 3 μm or more, even more preferably 5 μm or more, and also preferably 300 μm or less, more preferably 100 μm or less, even more preferably 60 μm or less.

A known method can be used for the fiber shortening treatment, and the target cellulose fiber can be shortened by alkaline hydrolysis treatment, acid hydrolysis treatment, hydrogen peroxide treatment, ultraviolet treatment, electron beam treatment, hot water decomposition treatment, mechanical treatment, enzyme treatment, etc. The modified cellulose fiber to be subjected to the fine fiber shortening treatment may be shortened before or after the introduction of the above-mentioned modifying group or ionic group. For example, there is a manufacturing mode in which ionic groups are introduced into the raw cellulose fiber, followed by fiber shortening treatment, and then modifying groups are introduced, and the resulting shortened modified cellulose fiber is finely treated in a thiol compound.

Suitable examples of devices that can be used in the micronization treatment include known dispersing machines. For example, a stirrer equipped with stirring blades, a disintegrator, a beater, a low-pressure homogenizer, a high-pressure homogenizer, a grinder, a cutter mill, a ball mill, a jet mill, a roll mill, a single-shaft kneader, a twin-shaft kneader, a single-shaft extruder, a twin-shaft extruder, an ultrasonic stirrer, a home juicer mixer, etc. can be used. The operating conditions of the device may be appropriately set by referring to the attached instruction manual.

The thiol compound-containing composition of the present invention has excellent dispersibility for modified cellulose fibers, and can therefore be suitably used for the production of thioester resin compositions and thiourethane resin compositions. The polymerization product of the thiol compound-containing composition of the present invention will be described below.

[Polymerization product of thiol compound-containing composition]
The polymerization product of the thiol compound-containing composition in the present invention is preferably at least one selected from the group consisting of a thioester resin composition and a thiourethane resin composition.

When the polymerization product of the thiol compound-containing composition is a thioester resin composition, the desired thioester resin composition can be obtained by selecting an aromatic polycarboxylic acid (having two or more carboxyl groups in the molecule) such as terephthalic acid, 2,6-naphthalenedicarboxylic acid, etc., or an aliphatic polycarboxylic acid (having two or more carboxyl groups in the molecule) such as adipic acid, sebacic acid, (iso)phthalic acid, etc., according to the desired physical properties and reactivity, and carrying out an appropriate polymerization reaction according to a conventional method.

When the polymerization product of the thiol compound-containing composition is a thiourethane resin composition, the desired thiourethane resin composition can be obtained by selecting an isocyanate (having two or more isocyanate groups in the molecule) such as an aromatic isocyanate such as tolylene diisocyanate or diphenylmethane diisocyanate, or an aliphatic isocyanate such as pentamethylene diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, isophorone diisocyanate, or tetramethylxylylene diisocyanate, depending on the desired physical properties and reactivity, and carrying out an appropriate polymerization reaction according to a conventional method.

The amount of modified cellulose in the polymerization product of the thiol compound-containing composition of the present invention is, in terms of the blend amount, preferably 0.05% by mass or more, more preferably 0.1% by mass or more, and even more preferably 0.15% by mass or more, in terms of cellulose (not including modifying groups, etc.), from the viewpoint of physical property expression. Also, from the viewpoint of handleability, it is preferably 35% by mass or less, more preferably 25% by mass or less, and even more preferably 15% by mass or less.

The catalyst can be appropriately selected depending on the type of resin. For example, in the case of a thiourethane composition, catalysts include Lewis acids, tertiary amines, organic acids, and amine-organic acid salts. The catalysts may be used alone or in combination of two or more.

The proportion of catalyst can be appropriately selected depending on the type of curing agent, etc., but is preferably 0.01 to 100 parts by mass per 100 parts by mass of the thiol compound-containing composition, for example.

[Other ingredients]
The polymerization product of the thiol compound-containing composition of the present invention may contain, for example, plasticizers, crystal nucleating agents, fillers (inorganic fillers, organic fillers), hydrolysis inhibitors, flame retardants, antioxidants, lubricants such as hydrocarbon waxes and anionic surfactants, ultraviolet absorbers, antistatic agents, antifogging agents, light stabilizers, pigments, mildew inhibitors, antibacterial agents, foaming agents, internal release agents, coloring inhibitors, surfactants; starches, polysaccharides such as alginic acid; natural proteins such as gelatin, glue, and casein; inorganic compounds such as tannins, zeolites, ceramics, and metal powders; fragrances; flow regulators; leveling agents; conductive agents; ultraviolet light dispersants; deodorants, etc., within the range that does not impair the effects of the present invention. Furthermore, it is also possible to add other polymer materials and other compositions within the range that does not impair the effects of the present invention.

The polymerization product of the thiol compound-containing composition of the present invention can be molded by appropriately using a known molding method such as coating molding, extrusion molding, injection molding, press molding, cast molding, or solvent casting.

The present invention will be specifically explained below with reference to examples and comparative examples, but the present invention is not limited to the following examples. Note that "normal pressure" refers to 101.3 kPa, and "normal temperature" refers to 25°C.

[Average fiber diameter, average fiber length, and average aspect ratio of anionically modified cellulose fibers, shortened anionically modified cellulose fibers, and finely refined modified cellulose fibers]
Deionized water or DMF is added to the cellulose fibers or the thiol compound-containing composition containing the cellulose fibers to prepare a dispersion having a concentration of 0.0001% by mass, and the dispersion is dropped onto mica and dried to obtain an observation sample. The fiber height (difference in height between the area where the fibers are present and the area where the fibers are not present) of the cellulose fibers in the observation sample is measured using an atomic force microscope (AFM, Nanoscope III Tapping mode AFM, manufactured by Digital Instrument Co., Ltd., and the probe is Nanosensors Point Probe (NCH)). At that time, 100 cellulose fibers are randomly extracted from a microscope image in which the cellulose fibers can be confirmed, and the number average fiber diameter is calculated from the fiber heights. The average fiber length is calculated from the distance in the fiber direction. The average aspect ratio is calculated from the average fiber length/average fiber diameter.

[Average fiber diameter and average fiber length of raw cellulose fibers]
Deionized water is added to the cellulose fibers to be measured to prepare a dispersion with a content of 0.01% by mass. The dispersion is measured using a wet dispersion type image analysis particle size distribution meter (manufactured by Jusco International, product name: IF-3200) under the following conditions: front lens: 2x, telecentric zoom lens: 1x, image resolution: 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 cellulose fibers are measured, and the average ISO fiber diameter and average ISO fiber length are calculated as the average fiber diameter and average fiber length, respectively.

[Solid content in dispersion]
The measurement is performed using a halogen moisture meter (manufactured by Shimadzu Corporation; product name "MOC-120H"). Measurements are performed every 30 seconds for 1 g of sample at a constant temperature of 150°C, and the value at which the mass loss is 0.1% or less of the initial amount of the sample is regarded as the solid content.

[Anionic Group Content of Anionically Modified Cellulose Fibers and Modified Cellulose Fibers]
A cellulose fiber to be measured having a dry mass of 0.5 g is placed in a beaker, deionized water or a mixed solvent of methanol/water = 2/1 (volume ratio) is added to make a total of 55 mL, and 5 mL of 0.01 M sodium chloride aqueous solution is added thereto to prepare a dispersion. The dispersion is stirred until the cellulose fiber to be measured is sufficiently dispersed. 0.1 M hydrochloric acid is added to the dispersion to adjust the pH to 2.5 to 3, and an automatic titrator (manufactured by DKK-TOA Corporation, product name "AUT-701") is used to drop a 0.05 M sodium hydroxide aqueous solution into the dispersion under the condition of a waiting time of 60 seconds, and the conductivity and pH values are measured every minute. The measurement is continued until the pH is about 11, and a conductivity curve is obtained. The sodium hydroxide titration amount is determined from this conductivity curve, and the anionic group content of the cellulose fiber to be measured is calculated by the following formula.
Anionic group content (mmol/g) = [titration amount of sodium hydroxide aqueous solution (mL) × concentration of sodium hydroxide aqueous solution (0.05 M)] / [mass of cellulose fiber to be measured (0.5 g)]

[Average bond amount and introduction rate of modifying groups in modified cellulose fiber (A)]
The average bond amount of the modifying group is determined by the following IR measurement method, and the average bond amount and introduction rate are calculated by the following formula. Specifically, in the IR measurement, the infrared absorption spectrum of the dried modified cellulose fiber is measured by the ATR method using an infrared absorption spectrometer (IR) (Nicolet 6700, manufactured by Thermo Fisher Scientific), and the average bond amount and introduction rate of the modifying group are calculated by formulas A and B. The following shows the case where the anionic group is a carboxy group, that is, the case of oxidized cellulose fiber. The "peak intensity at 1720 cm ^-1 " below is the peak intensity derived from a carbonyl group. In the case of an anionic group other than a carboxy group, the value of the wave number can be appropriately changed to calculate the average bond amount and introduction rate of the modifying group.
<Formula A-1 (in the case of ionic bond)>
Average amount of modified groups bonded (mmol/g)=a×(b−c)÷b
a: Carboxy group content of oxidized cellulose fiber (mmol/g)
b: Peak intensity at 1720 cm ⁻¹ of oxidized cellulose fiber c: Peak intensity at 1720 cm ⁻¹ of modified cellulose fiber <Formula A-2 (in the case of amide bond)>
Average amount of modified group bonded (mmol/g) = d - e
d: Carboxy group content of oxidized cellulose fiber (mmol/g)
e: Carboxylic group content of modified cellulose fiber (mmol/g)
<Formula B>
Modification group introduction rate (mol%) = 100 x f/g
f: average bond amount of modifying group (mmol/g)
g: Carboxy group content of oxidized cellulose fiber (mmol/g)

[Degree of introduction of substituents (MS) in modified cellulose fiber (B)]
First, the mass (mass%) of the substituents contained in the cellulose to be measured is calculated according to the Zeisel method, which is known as a method for analyzing the average number of moles of alkoxy groups added to a cellulose ether, as described in Analytical Chemistry, Vol. 51, No. 13, 2172 (1979), "The 15th Revised Japanese Pharmacopoeia (section on the analysis method for hydroxypropyl cellulose)" and the like. The procedure is as follows.
(i) Add 0.1 g of n-tetradecane to a 200 mL measuring flask and fill up to the mark with hexane to prepare an internal standard solution.
(ii) 70 mg of the purified and dried cellulose to be measured and 80 mg of adipic acid are precisely weighed into a 10 mL vial, and 2 mL of hydroiodic acid is added and the vial is then sealed.
(iii) The mixture in the vial is heated in a block heater at 160° C. for 1 hour while being stirred with a stirrer tip.
(IV) After heating, inject 2 mL of the internal standard solution and 2 mL of diethyl ether into the vial, successively, and stir at room temperature for 1 minute.
(v) The upper layer (diethyl ether layer) of the mixture separated into two phases in the vial is analyzed by gas chromatography (manufactured by Shimadzu Corporation, product name: GC2010Plus).
(vi) Analyze in the same manner as (ii) to (v), except that the cellulose to be measured is changed to 5 mg, 10 mg, or 15 mg of the etherification agent used to modify it, and prepare a calibration curve for the etherification agent.
(vii) The substituents contained in the cellulose to be measured are quantified based on the prepared calibration curve and the analysis results of the cellulose to be measured. The analytical conditions are as follows:

Column: Agilent Technologies, product name: DB-5 (12 m, 0.2 mm x 0.33 μm)
Column temperature: 30° C. (10 min hold) → 10° C./min → 300° C. (10 min hold)
Injector temperature: 300°C
Detector temperature: 300°C
Amount injected: 1 μL

Next, the molar substitution (MS) is calculated from the introduced mass of the obtained substituent using the following formula (1) or (2).
Formula (1): When one type of substituent is introduced, MS=(W/Mw)/((100-W)/162.14)
W: Mass (% by mass) of the substituent introduced into the modified cellulose fiber
Mw: Molecular weight of the introduced etherification agent (g/mol)

Formula (2): When two types of substituents are introduced, MS ₁ =(W ₁ /Mw ₁ )/((100-W ₁ -W ₂ )/162.14)
MS ₂ = (W ₂ /Mw ₂ )/((100-W ₁ -W ₂ )/162.14)
MS ₁ : Molar substitution of the first substituent
MS ₂ : Molar substitution of the second substituent
W ₁ : Mass (% by mass) of the first type of substituent introduced into the modified cellulose fiber
_W2 : Mass (mass%) of the second type of substituent introduced into the modified cellulose fiber
Mw ₁ : Molecular weight of the first etherification agent introduced (g/mol)
_Mw2 : Molecular weight of the second etherification agent introduced (g/mol)

[Cellulose fiber (equivalent amount) in modified cellulose fiber]
The cellulose amount (equivalent amount) in the modified cellulose fiber is the amount of cellulose in the modified cellulose fiber excluding the modifying group. In the modified cellulose fiber of the present invention, the formula weight of the modifying group may be considerably larger (for example, larger than the molecular weight of glucose), so in this specification, when it is appropriate to describe the modified cellulose fiber without considering the difference in the formula weight of the modifying group, the amount (equivalent amount) of cellulose constituting the modified cellulose fiber is expressed instead of the amount of the modified cellulose fiber.
The amount of cellulose fiber (converted amount) in the modified cellulose fiber is measured by the following method.

(1) When one type of “modifying compound” is added, the amount of cellulose fiber (converted amount) is calculated by the following formula E.
<Formula E>
Amount of cellulose fiber (equivalent amount) (g) = mass of modified cellulose fiber (g) / [1 + molecular weight of modifying compound (g/mol) × average bond amount of modifying group (mmol/g) × 0.001]
(2) When two or more types of “modifying compounds” are added, the amount of cellulose fiber (equivalent amount) is calculated taking into account the molar ratio of each compound (i.e., the molar ratio when the total molar amount of the added compounds is taken as 1).

In addition, when the bonding mode between the cellulose fiber and the modifying compound is an ionic bond, in the above formula, the "molecular weight of the modifying compound" refers to the "molecular weight of the entire modifying compound including the copolymer portion" when the modifying compound is a primary amine, secondary amine or tertiary amine, and refers to "(molecular weight of the entire modifying compound including the copolymer portion) - (molecular weight of the anionic component)" when the compound having a modifying group is a quaternary ammonium compound or a phosphonium 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, when the modifying compound is a primary amine or a secondary amine, the "molecular weight of the modifying compound" is "(the molecular weight of the entire compound having the modifying group, including the copolymer portion) - 18."

[Confirmation of crystal structure in various cellulose fibers]
The crystal structure of various cellulose fibers such as modified cellulose fibers is confirmed by measurement under the following conditions using an X-ray diffractometer (MiniFlex II, manufactured by Rigaku Corporation).
The measurement conditions are as follows: X-ray source: Cu/Kα-radiation, tube voltage: 30 kv, tube current: 15 mA, measurement range: diffraction angle 2θ = 5 to 45°, X-ray scan speed: 10°/min. The measurement sample is prepared by compressing the cellulose fiber to be measured into a pellet with an area of 320 mm ² × thickness of 1 mm. The crystallinity of the cellulose I type crystal structure is calculated from the obtained X-ray diffraction intensity based on the following formula C.

<Formula C>
Cellulose I type crystallinity (%) = [(I _22.6 -I _18.5 ) / I _22.6 ] × 100
(In the formula, _I22.6 represents the diffraction intensity of the lattice plane (002 plane) (diffraction angle 2θ=22.6°) in X-ray diffraction, and _I18.5 represents the diffraction intensity of the amorphous portion (diffraction angle 2θ=18.5°).)

On the other hand, when the degree of crystallinity obtained by the above formula C is 35% or less, from the viewpoint of improving the calculation accuracy, it is preferable to calculate based on the following formula D in accordance with the description on pages 199-200 of the "Wood Science Experiment Manual" (edited by the Japan Wood Research Society; published in April 2000).
Therefore, when the degree of crystallinity obtained by the above formula C is 35% or less, the value calculated based on the following formula D can be used as the degree of crystallinity.

<Formula D>
Cellulose I type crystallinity (%) = [Ac / (Ac + Aa)] x 100
[In the formula, Ac is the sum of the peak areas of the lattice planes (002 plane) (diffraction angle 2θ=22.6°), (011 plane) (diffraction angle 2θ=15.1°) and (0-11 plane) (diffraction angle 2θ=16.2°) in X-ray diffraction, Aa is the peak area of the amorphous portion (diffraction angle 2θ=18.5°), and each peak area is determined by fitting the obtained X-ray diffraction chart with a Gaussian function.]

Preparation Example 1 (Preparation of Anion-Modified Cellulose Fibers)
Bleached coniferous kraft pulp (Fletcher Challenge Canada, trade name "Machenzie", CSF 650 ml) was used as the natural cellulose fiber. A commercially available product (ALDRICH, Free radical, 98 mass%) was used as the TEMPO. A commercially available product (FUJIFILM Wako Pure Chemical Industries, Ltd.) was used as the sodium hypochlorite. A commercially available product (FUJIFILM Wako Pure Chemical Industries, Ltd.) was used as the sodium bromide.

First, 100 g of bleached softwood kraft pulp fiber was thoroughly stirred with 9900 g of deionized water, and then 1.25 g of TEMPO, 12.5 g of sodium bromide, and 28.4 g of 5% by mass sodium hypochlorite were added in this order to 10 g of the pulp. 0.5 M sodium hydroxide was added dropwise using a pH stud to maintain the pH at 10.5. After the reaction was carried out for 120 minutes (20°C), the addition of sodium hydroxide was stopped to obtain oxidized pulp. The obtained oxidized pulp was thoroughly washed with deionized water and then dehydrated. The anionic group of the obtained anion-modified cellulose fiber was a carboxyl group, and the carboxyl group content was 1.3 mmol/g. The average fiber diameter of the oxidized cellulose fiber was 41 μm, and the average fiber length was 1058 μm.

Preparation Example 2 (Preparation of Short Anion-Modified Cellulose Fibers)
A vial equipped with a magnetic stirrer and a stirring bar was charged with 7.2 g (absolute dry mass) of the oxidized cellulose fibers obtained in Preparation Example 1, and deionized water was added until the mass of the treatment liquid reached 360 g. The resulting mixture was stirred at 95°C for 24 hours and then subjected to a dehydration treatment to obtain short fiber anion-modified cellulose fibers. The anionic groups of the obtained anion-modified cellulose fibers were carboxy groups, and the carboxy group content was 1.3 mmol/g. The average fiber diameter of the short fiber cellulose fibers was 41 μm, and the average fiber length was 133 μm.

Example 1
In a beaker equipped with a magnetic stirrer and a stirrer, 0.17 g of the short fiber anion-modified cellulose fiber obtained in Preparation Example 2 was charged in an absolute dry mass. Then, 0.21 g of aliphatic polyetheramine (manufactured by Huntsman, USA, trade name: Jeffamine M-2070) was charged and dissolved in 10 g of acetone. The resulting mixture was stirred at room temperature (25 ° C) for 1 hour to obtain a cellulose fiber composite in which aliphatic polyetheramine was bonded to the anion-modified cellulose fiber. Then, 8 g of a thiol compound (manufactured by Fuji Pharmaceutical Wako Pure Chemical Industries, number: pentaerythritol tetrakis (3-mercaptopropionate), molecular weight 488, hereinafter abbreviated as "PETM") was added and stirred for another 1 hour at 25 ° C. Using a high-pressure homogenizer (manufactured by Yoshida Kikai Kogyo Co., Ltd., Nanovaita L-ES), it was subjected to dispersion treatment 5 times at 150 MPa. The solvent was removed from the resulting dispersion to obtain a thiol compound-containing composition containing modified cellulose fibers and PETM. The modified cellulose fibers in the thiol compound-containing composition had an average fiber diameter of 4 nm, an average fiber length of 160 nm, an average aspect ratio of 40, an average bond amount of 1.27 mmol/g, and a cellulose I-type crystal structure.

Example 2
A thiol compound-containing composition was obtained in the same manner as in Example 1, except that 0.11 g of an aliphatic polyetheramine (manufactured by Huntsman, USA, product name: Jeffamine M-1000) was charged as the amine in Example 1. The average binding amount was 1.27 mmol/g.

Example 3
A thiol compound-containing composition was obtained in the same manner as in Example 1, except that 0.21 g of an aliphatic polyetheramine (manufactured by Huntsman, USA, product name: JEFFAMINE M-2095) was used as the amine in Example 1. The average binding amount was 1.27 mmol/g.

Example 4
A thiol compound-containing composition was obtained in the same manner as in Example 1, except that 0.17 g of an aliphatic polyetheramine (manufactured by Huntsman, USA, product name: JEFFAMINE M-2070) and 0.01 g of octylamine (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were used as the amine in Example 1. The average bond amount was 0.67 mmol/g.

Example 5
A beaker equipped with a magnetic stirrer and a stirring bar was charged with 3.12 g of the short fiber anion-modified cellulose fiber obtained in Preparation Example 2 in terms of absolute dry mass. Then, 8.01 g of aliphatic polyetheramine (manufactured by Huntsman, USA, trade name: JEFFAMINE M-2070), 0.71 g of condensing agent 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMT-MM), and 0.13 g of N-methylformaldehyde (NMM) were charged and dissolved in 85 g of DMF, and the reaction solution was reacted at room temperature (25 ° C.) for 14 hours. After the reaction was completed, the mixture was filtered, washed with deionized water to remove the DMT-MM salt, and washed and solvent-substituted with acetone to obtain a cellulose fiber composite in which aliphatic polyetheramine was linked to fine cellulose fiber via an amide bond. Thereafter, 0.51 g of the cellulose fiber composite in which the aliphatic polyetheramine was linked via an amide bond was added in absolute dry mass, and 8 g of a thiol compound (PETM) was added, and the mixture was stirred for another hour at 25°C. Using a high-pressure homogenizer (Yoshida Kikai Kogyo Co., Ltd., Nanovater L-ES), the mixture was subjected to a dispersion treatment five times at 150 MPa. The solvent was removed from the resulting dispersion to obtain a thiol compound-containing composition containing modified cellulose fiber and PETM. The average binding amount was 0.98 mmol/g.

Example 6
A thiol compound-containing composition was obtained in the same manner as in Example 5, except that 4.00 g of an aliphatic polyetheramine (manufactured by Huntsman, USA, product name: JEFFAMINE M-1000) was used as the amine in Example 5. The average binding amount was 1.02 mmol/g.

Example 7
A beaker equipped with a magnetic stirrer and a stirring bar was charged with 3.12 g of the short fiber anion-modified cellulose fiber obtained in Preparation Example 2 in terms of absolute dry mass. Then, 4.86 g of aliphatic polyetheramine (manufactured by Huntsman, USA, trade name: JEFFAMINE M-1000), 2.47 g of condensing agent 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMT-MM), and 0.49 g of N-methylformaldehyde (NMM) were charged and dissolved in 71 g of DMF, and the reaction solution was reacted at room temperature (25 ° C.) for 14 hours. After the reaction was completed, the mixture was filtered, washed with deionized water to remove the DMT-MM salt, and washed and solvent-substituted with acetone and DMF to obtain a cellulose fiber composite in which aliphatic polyetheramine was linked to fine cellulose fibers via amide bonds. Subsequently, 1.56 g of cellulose fiber composite in which aliphatic polyetheramine is linked via an amide bond was dissolved in absolute dry mass, 0.63 g of aromatic amine (Tokyo Chemical Industry Co., Ltd., tritylamine), 1.47 g of DMT-MM, 0.25 g of NMM, and 35 g of DMF, and the reaction solution was reacted at room temperature (25 ° C.) for 14 hours. After the reaction was completed, the mixture was filtered, washed with deionized water to remove the DMT-MM salt, and washed and solvent-substituted with acetone to obtain a cellulose fiber composite in which aliphatic polyetheramine and aromatic amine were linked via an amide bond to the fine cellulose fiber. Then, 0.17 g of cellulose fiber composite in which aliphatic polyetheramine and aromatic amine were linked via an amide bond were added in absolute dry mass, and 8 g of a thiol compound (PETM) was added, and the mixture was stirred for another hour at 25 ° C. Using a high-pressure homogenizer (Yoshida Machinery Co., Ltd., Nanovaita L-ES), the mixture was subjected to dispersion treatment five times at 150 MPa. The solvent was removed from the resulting dispersion to obtain a thiol compound-containing composition containing the modified cellulose fiber and PETM. The average bond amount was 1.04 mmol/g.

Example 8
A thiol compound-containing composition was obtained in the same manner as in Example 7, except that 0.51 g of diphenylpropylamine (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.) was added instead of tritylamine in Example 7. The average bond amount was 1.03 mmol/g.

Example 9
A thiol compound-containing composition was obtained in the same manner as in Example 7, except that 9.71 g of JEFFAMINE M-2095 (manufactured by Huntsman, USA, trade name: JEFFAMINE M-1000) was used instead of JEFFAMINE M-1000, and 0.31 g of diphenylpropylamine was used instead of tritylamine. The average binding amount was 1.04 mmol/g.

Comparative Example 1
A thiol compound-containing composition was obtained in the same manner as in Example 1, except that the aliphatic polyetheramine was not added.

Test Example 1 (Transparency Evaluation Test)
The thiol compound-containing compositions obtained in each of the Examples and Comparative Examples were used to measure the light transmittance of the dispersion and evaluate its transparency as follows. The light transmittance was measured at room temperature and normal pressure.
Specifically, 3 mL of the thiol compound-containing composition was placed in a quartz cell with an optical path length of 10 mm, and immediately, the absorbance at a wavelength of 660 nm was measured using a double beam spectrophotometer ("U-2910" manufactured by Hitachi High-Tech Science Corp.) The medium used in the preparation of each dispersion was used as a blank (i.e., light transmittance 100%), and the light transmittance (%) was calculated from the absorbance of each dispersion.

From Table 1, it can be seen that the thiol compound-containing compositions of Examples 1 to 9, which contained modified cellulose fibers, all had superior dispersibility and transparency compared to Comparative Example 1, which contained unmodified cellulose fibers.

The thiol compound-containing composition of the present invention can be suitably used as a curing agent for epoxy resins, and for the production of thiourethane resin compositions and thioester resin compositions.

Claims (10)

A thiol compound-containing composition containing a thiol compound and a modified cellulose fiber, wherein the modified cellulose fiber has cellulose type I crystals and is one or more types selected from the group consisting of the following cellulose fibers (A):
Modified cellulose fiber (A) Modified cellulose fiber in which a modifying group is bonded to the ionic group of a cellulose fiber containing an ionic group. The thiol compound-containing composition according to claim 1, wherein the thiol compound is a polythiol compound having two or more thiol groups. A thiol compound-containing composition containing a thiol compound and modified cellulose fibers, wherein the thiol compound is a polythiol compound having two or more thiol groups, and the modified cellulose fibers have cellulose type I crystals and are one or more types selected from the group consisting of the following cellulose fibers (B):
Modified cellulose fiber (B) Modified cellulose fiber in which a modifying group is bonded to the hydroxyl group of a cellulose fiber. The thiol compound-containing composition according to any one of claims 1 to 3, wherein the aspect ratio of the modified cellulose fiber is 100 or less. The thiol compound-containing composition according to any one of claims 1 to 4, wherein the fiber length of the modified cellulose fiber is 500 nm or less. The thiol compound-containing composition according to claim 1 or 2 , wherein the ionic group is a carboxy group. The thiol compound-containing composition according to any one of claims 1 to 6, wherein the modifying group contains one or more selected from the group consisting of (a) a hydrocarbon group and (b) a polymer group. A method for producing a thiol compound-containing composition according to any one of claims 1 to 7, comprising a step of micronizing modified cellulose fibers having an average fiber length of more than 500 nm in a thiol compound, wherein the modified cellulose fibers subjected to the micronization step are one or more types selected from the group consisting of the following modified cellulose fibers (A) and modified cellulose fibers (B).
Modified cellulose fiber (A): Modified cellulose fiber in which a modifying group is bonded to the ionic group of a cellulose fiber containing an ionic group. Modified cellulose fiber (B): Modified cellulose fiber in which a modifying group is bonded to the hydroxyl group of a cellulose fiber. A polymerization product of the thiol compound-containing composition according to any one of claims 1 to 7. The polymerization product of the thiol compound-containing composition according to claim 9, which is a thioester composition or a thiourethane composition.