JP2020110760A - Lignin dye dispersant and dye composition - Google Patents

Abstract

To provide a lignin dye dispersant that is low in staining to cloth, and is superior in dispersibility of dye at high temperature.SOLUTION: A lignin dye dispersant is provided as follows: a lignin component contains the lignin component having a partial structure shown in the following expression (5); the lignin component is a component derived from a kraft lignin; the lignin component further has a reducing saccharide; and the content of the reducing saccharide is 5.0 mass% or less. (in the general formula (5), M shows a hydrogen atom, a monovalent metal salt, or a divalent metal salt).SELECTED DRAWING: None

Description

The present invention relates to a lignin-based dye dispersant and a dye composition. More specifically, the present invention relates to a lignin-based dye dispersant containing a lignin component having a predetermined partial structure and a dye composition containing the same.

Lignin is a natural polymer component that is present in trees, and is occurring on a large scale and commercially in the paper industry using wood as a raw material. For example, kraft lignin is obtained from the kraft pulp waste liquor, and lignin sulfonic acid is obtained from the sulfite pulp waste liquor. Kraft lignin, lignin sulfonic acid, kraft lignin sulfomethylated with sulfite and formaldehyde, lignin sulfonic acid or its salt partially desulfonated, or lignin sulfonic acid or its salt purified by ultrafiltration These are widely used in a wide range of industrial fields such as dyes, hydraulic compositions (for example, cement, gypsum), inorganic and organic pigments, coal-water slurries, pesticides, pottery, mud for oilfield drilling as dispersants.

For example, Patent Document 1 discloses the use of a modified lignin sulfonate in which the amount of sulfone groups and the amount of carboxyl groups and the molecular weight are controlled as a dye dispersant. Patent Document 2 discloses the use of a graft copolymer of ligninsulfonic acid having a molecular weight distribution within a predetermined range and an acrylic or vinyl monomer as a cement dispersant. Further, Patent Document 3 discloses a graft copolymer of acrylic acid and lignin sulfonate as a mud dispersion stabilizer for oil field drilling. Patent Document 4 discloses a lignin derivative composed of a reaction product of a lignin sulfonate and a water-soluble monomer having a polyalkylene oxide chain. Patent Document 5 discloses the use of sulfonated lignin as a dye dispersant.

JP, 2002-146028, A Japanese Patent Laid-Open No. 01-145358 US Pat. No. 4,322,301 Japanese Patent No. 5769930 JP-A-60-252661

However, with the conventional lignin-based dispersant of the prior art, lignin may remain on the dyed cloth and stain the dyed cloth. In addition, when used as a dispersant for dyes for high temperature dyeing in dyeing polyester fibers and the like, since the dispersibility is not sufficient, dyeing is not performed uniformly, and there is room for improvement in dispersion stability at high temperatures.

An object of the present invention is to provide a lignin-based dye dispersant which has low stain resistance to cloth and is excellent in dye dispersibility at high temperatures.

（前記一般式（１）〜（４）中、Ｒは、Ｈ、又はＣＨ_３を示す。Ｍは、水素原子、一価金属塩、又は二価金属塩を示す）
〔２〕前記リグニン成分が、下記一般式（５）で示される部分構造（５）をさらに有する、上記〔１〕に記載のリグニン系染料分散剤。

（前記一般式（５）中、Ｍは、水素原子、一価金属塩、又は二価金属塩を示す）
〔３〕前記リグニン成分が、クラフトリグニン由来物である、上記〔１〕又は〔２〕に記載のリグニン系染料分散剤。
〔４〕前記リグニン成分が還元性糖類をさらに有し、前記還元性糖類の含有量が、５．０質量％以下である、上記〔１〕〜〔３〕のいずれかに記載のリグニン系染料分散剤。
〔５〕上記〔１〕〜〔４〕のいずれかに記載のリグニン系染料分散剤を含有する染料組成物。 As a result of diligent studies on the above problems, the present inventors have found that when a dye dispersant containing a lignin component having a predetermined partial structure is used, the stain resistance to cloth is low and the dispersibility of the dye is high at high temperatures. The present invention has been completed by discovering that the above-mentioned problems can be solved by using the dye composition of the present invention.
That is, the present inventors provide the following [1] to [5].
[1] Partial structure (1) represented by the following general formula (1), Partial structure (2) represented by the following general formula (2), Partial structure (3) represented by the following general formula (3), and A lignin-based dye dispersant containing a lignin component having at least one partial structure selected from the group consisting of the partial structure (4) represented by the general formula (4).

(In the general formulas (1) to (4), R represents H or CH _3, and M represents a hydrogen atom, a monovalent metal salt, or a divalent metal salt.)
[2] The lignin-based dye dispersant according to the above [1], wherein the lignin component further has a partial structure (5) represented by the following general formula (5).

(In the general formula (5), M represents a hydrogen atom, a monovalent metal salt, or a divalent metal salt)
[3] The lignin-based dye dispersant according to the above [1] or [2], wherein the lignin component is derived from craft lignin.
[4] The lignin-based dye according to any one of the above [1] to [3], wherein the lignin component further has a reducing saccharide, and the content of the reducing saccharide is 5.0% by mass or less. Dispersant.
[5] A dye composition containing the lignin-based dye dispersant according to any of [1] to [4] above.

INDUSTRIAL APPLICABILITY The lignin-based dye dispersant of the present invention can exhibit higher dye-dispersing performance at high temperatures than conventional lignin-derived dye dispersants. Further, the lignin-based dye dispersant of the present invention has a low staining property on cloth, and can exhibit good dispersibility even when undergoing high-temperature dyeing, and therefore has higher dyeing properties than conventional lignin-based dye dispersants It can exert its potential. That is, the lignin-based dye dispersant of the present invention has low stain resistance to cloth and is excellent in dye dispersibility at high temperature.

Hereinafter, the present invention will be described in detail with reference to its preferred embodiments. The expression "AA to BB" means AA or more and BB or less.

[1. Lignin dye dispersant]
The lignin-based dye dispersant of the present invention is a lignin-based dye dispersant containing a lignin component having at least one partial structure selected from the group consisting of the following general formulas (1) to (4). When the lignin component has the following partial structure, it is possible to obtain a lignin-based dye dispersant having low stain resistance to cloth and good dye dispersibility at high temperatures.
The presence of the partial structures of the general formulas (1) to (4) can be confirmed using IR analysis as follows. First, the component to be measured is subjected to IR analysis to confirm the presence or absence of a peak near 1650 cm ⁻¹ derived from a carboxylate anion. Next, the component to be measured is made acidic. Then, the acidified measurement target component is subjected to IR analysis to confirm the presence or absence of a peak derived from carboxylic acid near 1700 cm ⁻¹ . If it can both confirm the peak around 1700 cm ^-1 derived from a carboxylic acid anion derived from 1650 cm ^-1 vicinity of the peak and a carboxylic acid, it can be said that the partial structure of the general formula (1) to (4) are present.

（一般式（１）〜（４）中、Ｒは、Ｈ、又はＣＨ_３を示す。Ｍは、水素原子、一価金属塩、又は二価金属塩を示す）

(In general formulas (1) to (4), R represents H or CH _3, and M represents a hydrogen atom, a monovalent metal salt, or a divalent metal salt.)

The lignin component having at least one partial structure selected from the group consisting of the above general formulas (1) to (4) is obtained, for example, by oxidizing Kraft black liquor or an alkaline solution of Kraft lignin. The details of the generation of the partial structure are described in The Chemistry of Delivery, Holzforschung, 36 (1982), pp55-64.

Examples of the oxidation treatment include air, oxygen, hydrogen peroxide, and ozone oxidation. Among them, hydrogen peroxide, air or a combination of oxygen and hydrogen peroxide is preferable.
The oxidation treatment is usually performed in a solution. Examples of the solvent include water, lower alcohols, and mixed solvents thereof. Of these, water is preferable from the viewpoint of handling. When the oxidation treatment is performed using an aqueous solution, it is preferably an alkaline aqueous solution having a pH of about 9-14.

The reaction conditions of the oxidation treatment can be appropriately adjusted according to the target proportion of the partial structure of the general formulas (1) to (4). For example, when the oxidation treatment is performed with a combination of air or oxygen and hydrogen peroxide, the following reaction conditions can be mentioned.

First, air or oxygen is blown into the solution heated to about 50 to 90°C, preferably about 60 to 80°C. The amount of air or oxygen blown is about 60 to 120 mL/min, preferably about 75 to 105 mL/min. The time for blowing air or oxygen is about 30 to 150 minutes, preferably about 60 to 120 minutes.
Next, after raising the temperature to about 70 to 120° C., preferably about 80 to 100° C., hydrogen peroxide is added to the solution. The amount of hydrogen peroxide used is about 0.5 to 10 parts by mass, preferably about 0.8 to 5 parts by mass, based on 100 parts by mass of the solid content. The reaction time after adding hydrogen peroxide is about 30 to 150 minutes, preferably about 60 to 120 minutes.
In addition, in a series of reactions, the concentration of the solid content in the solution is preferably about 15 to 30 mass %.

[Sulfomethylated lignin]
When kraft lignin is used as a raw material of the lignin-based dye dispersant and a sulfomethylation reaction is performed after the oxidation treatment, the lignin component further has a partial structure (5) represented by the following general formula (5). In the present specification, a lignin component obtained by using kraft lignin as a raw material of a lignin-based dye dispersant and performing a sulfomethylation reaction after an oxidation treatment is referred to as "sulfomethylated lignin".

（前記一般式（５）中、Ｍは、水素原子、一価金属塩、又は二価金属塩を示す）

(In the general formula (5), M represents a hydrogen atom, a monovalent metal salt, or a divalent metal salt)

In the sulfomethylation reaction of craft lignin, a sulfonic acid group is generally introduced at the position of the following general formula (6) with respect to the C ₆ -C ₃ unit of lignin. In general formula (6) shows a _C 6 -C ₃ unit is a partial structure of lignin. The reaction indicated by the arrow on the left is a reaction in which a sulfonic acid group is introduced at the α-position, and is generally called sulfonation. Further, in the reaction indicated by the arrow on the right side, a sulfonic acid group is introduced via formaldehyde at the 5-position of the aromatic nucleus in addition to the α-position.
In the lignin-based dye dispersant of the present invention, the lignin component preferably further has a partial structure obtained by the reaction indicated by the arrow on the right side (that is, partial structure (5)).

（一般式（６）中、Ｍは、水素原子、一価金属塩、又は二価金属塩を示す。）

(In the general formula (6), M represents a hydrogen atom, a monovalent metal salt, or a divalent metal salt.)

The sulfomethylated lignin has an S content of 1.0 to about ₃ SO ₃ M (provided that M represents a hydrogen atom, a monovalent metal salt or a divalent metal salt). It is preferably 6.0% by mass.
-SO ₃ M (where M represents a hydrogen atom, a monovalent metal salt, or a divalent metal salt) is the S content of the sulfonic acid (salt) group, and the solid content of the lignin-based dye dispersant. The content of sulfur atom contained in —SO ₃ M (where M represents a hydrogen atom, a monovalent metal salt, or a divalent metal salt) with respect to the content. Specifically, it is a value calculated by the following mathematical expression (7).

（数式（７）中、Ｓ含量はいずれもリグニン系染料分散剤の固形物量に対するＳ含量を示す。）

(In the formula (7), each S content represents the S content with respect to the solid amount of the lignin-based dye dispersant.)

In formula (7), the total S content is the total S content contained in the lignin-based dye dispersant, and can be quantified by ICP emission spectroscopy. The inorganic S content can be calculated as the total amount of SO ₃ content, S ₂ O ₃ content and SO ₄ content quantified by ion chromatography. However, the inorganic S content is not calculated based on the oxide content itself, but is calculated based on the S content in the oxide.

[Production of sulfomethylated lignin]
Sulfomethylated lignin may be produced by a known method. For example, it can be produced by reacting a lignin component with a sulfite and an aldehyde after the oxidation treatment.

An example of a method for sulfomethylating a lignin component is disclosed in US Pat. No. 2,680,113. In this method, the methyl sulfonation treatment of the lignin component is usually performed in the temperature range of 50 to 200°C, preferably in the temperature range of 80 to 170°C, and more preferably in the temperature range of 100 to 160°C. Be seen.
The amount of sulfite added is preferably 1 to 50% by mass based on 100% by mass of the solid content of the lignin component. If the amount of sulfite added is outside the above range, the hydrophilicity of lignin may be low and the stain resistance of the cloth may be low. On the other hand, if sulfite is added excessively, the purity of lignin is lowered, and good dye dispersibility may not be obtained in some cases.
Formaldehyde is preferable as the aldehyde, and the amount of the added aldehyde is preferably 0.25 to 12.5 mass% with respect to 100 mass% of the solid content of the lignin component. If formaldehyde is not within the above range, sulfonic acid groups may not be introduced into lignin. The pH is preferably 8 or higher.

[Methoxyl group]
Generally, a methoxyl group bonded to an aromatic nucleus exists in the structure of the lignin component. Therefore, the methoxyl group content is an index of the lignin component content.
Ordinary lignin (not subjected to oxidation treatment) usually has a methoxyl group content per solid content of 3.0 to 20.0 mass %. On the other hand, the lignin-based dye dispersant having the partial structures of the general formulas (1) to (4) has a methoxyl group content per solid content of usually 2.0% by mass or more, preferably It is 4.0 mass% or more, and more preferably 6.0 mass% or more. The upper limit is usually 20.0 mass% or less, preferably 19.5 mass% or less, and more preferably 19.2 mass% or less. When the methoxyl group content is 2.0% by mass or more, the dye dispersibility at high temperature becomes good.
In addition, in the present specification, the methoxyl group content is determined by the method of quantifying methoxyl group by the Viebock and Schwappach method (see “Lignin Chemistry Research Method”, P.336-340, 1994, published by Uni Publishing Co., Ltd.). It is the measured value.

[Reducing sugar]
The lignin-based dye dispersant of the present invention may contain a reducing saccharide. The reducing sugar refers to a sugar that exhibits reducing properties, and is a sugar that produces an aldehyde group or a ketone group in a basic solution. Examples of the reducing sugar include monosaccharides such as rhamnose, lactose, galactose, arabinose, xylose, maltose, glucose, mannose and fructose; oligosaccharides such as xylooligosaccharides and cellooligosaccharides; and disaccharides such as invert sugars of arabinose and sucrose. A polysaccharide may be mentioned.

The content of the reducing sugar is preferably 5.0% by mass or less with respect to 100% by mass of the lignin-based dye dispersant. When the content of the reducing sugar is 5.0% by mass or less, aggregation of the dye can be suppressed when the dye composition is dried.
The content of the reducing saccharide can be calculated by converting the measurement value measured by the Somogyi-Schaffer method into the glucose amount.

[Inorganic salt]
The lignin-based dye dispersant usually contains an inorganic salt. As the inorganic salt, for example, sodium sulfate, sodium sulfite, sodium chloride, magnesium sulfate, magnesium sulfite, magnesium chloride, calcium sulfate, calcium sulfite, calcium chloride, ammonium sulfate, ammonium sulfite, ammonium chloride, sodium hydroxide, sodium carbonate, sulfurized Examples include sodium. The content of the inorganic salt with respect to the solid content of the lignin-based dye dispersant is usually 1 to 25% by mass.

The Ca content (calcium atom content relative to the solid content) of the lignin-based dye dispersant is usually 0.06 mass% or less, preferably 0.05 mass% or less. The lower limit is usually 0.001 mass% or more, preferably 0.005 mass% or more.
The Na content (sodium atom content relative to the solid content) of the lignin-based dye dispersant is usually 25% by mass or less. The lower limit is usually 1% by mass or more, preferably 2% by mass or more, and more preferably 5% by mass or more.
The Mg content (magnesium atom content relative to the solid content) of the lignin-based dye dispersant is usually 0.300% by mass or less, and preferably 0.2000% by mass or less. The lower limit is usually 0.001 mass% or more, preferably 0.002 mass% or more.

The inorganic salt content, Ca content, Na content, and Mg content of the lignin-based dye dispersant can be calculated as follows. Regarding the inorganic salts, first, the sample is made into a 10% hydrochloric acid solution and treated at 100° C. for 15 minutes. Each metal ion (Ca ²⁺ , Na ⁺ , Mg ²⁺ ) was quantified by the inductively coupled plasma (ICP) method, and the quantification result was calculated by converting it to Ca content, Na content, and Mg content (mass %), respectively. obtain. Sulfate ion, sulfite ion, and thiosulfate ion are quantified by ion chromatography.

[Weight average molecular weight]
The weight average molecular weight of the lignin-based dye dispersant is preferably 3,000 to 30,000, more preferably 3,000 to 20,000. When the weight average molecular weight is in the above range, the dye dispersibility at high temperature becomes good.
The weight average molecular weight of the lignin-based dye dispersant is measured by gel permeation chromatography (GPC). More specifically, the weight average molecular weight of the lignin-based dye dispersant is a value measured by a known method of pullulan conversion under the following GPC measurement conditions.

Measuring device: Tosoh product column: Shodex Column OH-pak SB-806HQ, SB-804HQ, SB-802.5HQ
Eluent: Na tetraborate 1.0%, isopropyl alcohol 0.3% aqueous solution Eluent flow rate: 1.00 ml/min
Column temperature: 50°C
Measurement sample concentration; 0.2% by mass
Standard material: Pullulan (Showa Denko)
Detector: UV detector (280 nm) (made by Tosoh Corporation)
Calibration curve; Pullulan standard

[material]
Examples of raw materials for the lignin-based dye dispersant of the present invention include kraft lignin, soda lignin, soda-anthraquinone lignin, organosolv lignin, explosive lignin, lignin sulfonic acid, and sulfuric acid lignin. Among these, craft lignin is preferable. That is, the lignin-based dye dispersant is preferably derived from Kraft lignin.

The raw material of the lignin-based dye dispersant usually contains a reducing saccharide. Reducing sugars generally remain in the process of kraft cooking woody biomass. The raw material of the lignin-based dye dispersant usually contains a reducing saccharide in a content of 20.0 mass% or less.

[Craft lignin]
Kraft lignin can be used as a raw material for the lignin-based dye dispersant. Kraft lignin is also referred to as thiolignin and Sulfate lignin as aliases. As the craft lignin, a prepared product may be used or a commercially available product may be used. As the prepared ones, a UF treatment liquid of kraft black liquor, an alkaline solution of kraft lignin, a powdered kraft lignin obtained by spray drying an alkaline solution of kraft lignin, and an alkaline solution of kraft lignin were precipitated with an acid Acid precipitated kraft lignin can be used.

The alkaline solution of kraft lignin can be obtained by a known method as described in JP-A-2000-336589, for example. However, the alkaline solution of kraft lignin is not limited to those obtained by these methods.

Acid-precipitated kraft lignin obtained by precipitating an alkaline solution of kraft lignin with an acid is described in, for example, WO 2006/038863, WO 2006/031175, and WO 2012/005677. The powdery acid-precipitated kraft lignin obtained by the method described above is included. However, acid-precipitated kraft lignin is not limited to those obtained by these methods.

The weight average molecular weight of kraft lignin is preferably 3,000 to 30,000, more preferably 3,000 to 20,000. When the weight average molecular weight is in the above range, it can be used as a lignin component capable of preparing a lignin-based dye dispersant having good dye dispersibility at high temperatures. The weight average molecular weight of kraft lignin can be measured in the same manner as the above-mentioned method for measuring the weight average molecular weight of the lignin component.

[2. Dye composition]
The dye composition of the present invention contains the above-mentioned lignin-based dye dispersant. Examples of the dye used in combination with the lignin-based dye dispersant include C.I. I. Azo disperse dyes such as Disperse Red 17, C.I. I. Examples thereof include disperse dyes that are used by being dispersed in a solvent, such as anthraquinone disperse dyes such as Disperse Red 60.
The material to be dyed is not particularly limited, and may be cloth or paper. However, a material obtained through a high temperature dyeing step (for example, 100° C. or higher, 110° C. or higher, 120° C. or higher) is preferable, and synthetic fiber (for example, polyester, acetate, nylon) is more preferable. The temperature condition during the high temperature dyeing step is not particularly limited, but the amount of the lignin-based dye dispersant added to the dye is preferably 1% by mass or more and more preferably 5% by mass or more based on the weight of the dye in the dye solution. preferable. The upper limit is preferably 100% by mass or less, and more preferably 70% by mass or less.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the present invention is not limited to the following Examples, and appropriate changes are made within a range compatible with the gist of the preceding and following description. It is also possible to carry out the present invention, and all of them are included in the technical scope of the present invention. In the examples, "%" indicates "mass %" and "parts" indicates "parts by weight" unless otherwise specified. The physical property values are measured by the above-mentioned methods.

<Separation of craft lignin>
Kraft lignin was separated by a known method. That is, carbon dioxide was passed through the softwood (N material) kraft cooking black liquor to lower the pH of the black liquor to 10, and then primary filtration was performed. After redispersing the primary filtrate in water, the pH was lowered to 2 using sulfuric acid, and secondary filtration was performed. Then, the secondary filtered product was washed with water and dried to obtain N-material craft lignin.

<Production Example 1>
A solution was prepared by dissolving N-material craft lignin at pH 10 with NaOH so that the solid content was 20%. While stirring 500 parts of the prepared solution at 70° C., air was blown at 60 ml/min for 90 minutes, 3.33 parts of 30% hydrogen peroxide was added, and oxidation treatment was performed at 90° C. for 1 hour to obtain an oxidation treatment solution ( N-1) was obtained.
A 1 L autoclave equipped with a reflux condenser was charged with 500 parts of the oxidation treatment liquid (N-1), 10 parts of sodium sulfite, and 7 parts of 37% formaldehyde solution, and a sulfomethylation reaction was carried out at 140° C. for 120 minutes. After cooling to room temperature, a sulfomethylated product of N-material craft lignin (A-1) was obtained as a lignin-based dye dispersant.

<Production Example 2>
A 1 L autoclave equipped with a reflux condenser was charged with 500 parts of the oxidation treatment liquid (N-1), 20 parts of sodium sulfite, and 14 parts of a 37% formaldehyde solution, and a sulfomethylation reaction was carried out at 140° C. for 120 minutes. After cooling to room temperature, a sulfomethylated N-material kraft lignin (A-2) was obtained as a lignin-based dye dispersant.

<Production Example 3>
While stirring 500 parts of N material kraft cooking black liquor (pH 11) (solid content 20%) at 70° C., oxygen was blown thereinto at 60 ml/min for 90 minutes, and then 13.33 parts of 30% hydrogen peroxide was added to the mixture to give 90 parts. Oxidation treatment was performed at 1° C. for 1 hour to obtain an oxidation treatment liquid (N-2).
A 1 L autoclave equipped with a reflux condenser was charged with 500 parts of the oxidation treatment liquid (N-2), 5 parts of sodium sulfite, and 3.5 parts of 37% formaldehyde solution, and a sulfomethylation reaction was performed at 140° C. for 120 minutes. After cooling to room temperature, a sulfomethylated product (A-3) of N-material kraft cooking black liquor was obtained as a lignin-based dye dispersant.

<Production Example 4>
A 1 L autoclave equipped with a reflux condenser was charged with 500 parts of the oxidation treatment liquid (N-2), 20 parts of sodium sulfite, and 14 parts of a 37% formaldehyde solution, and a sulfomethylation reaction was performed at 140° C. for 120 minutes. After cooling to room temperature, a sulfomethylated product (A-4) of N-material kraft cooking black liquor was obtained as a lignin-based dye dispersant.

<Production Examples 5 to 8>
In the above Production Examples 1 to 4, sulfomethylation was carried out without performing oxidation treatment to obtain sulfomethylated products (A-5) to (A-8).
Table 1 shows a part of the composition of each lignin component obtained in Production Examples 1 to 4. The presence of the partial structures represented by the general formulas (1) to (4) was confirmed by IR analysis. More specifically, first, the sample was subjected to IR analysis to confirm the presence or absence of a peak near 1650 cm ⁻¹ derived from a carboxylate anion. The sample was then acidified. Then, the acidified sample was subjected to IR analysis to confirm the presence or absence of a peak near 1700 cm ⁻¹ derived from carboxylic acid. The peak around 1650 cm ⁻¹ is a region where the peaks of aromatic nuclei overlap. Therefore, by the peak around 1650 cm ^-1 is shifted in the vicinity of 1700 cm ^-1 by acidification may confirm the presence of the partial structure.
In addition, in Table 1, "%" represents the mass% with respect to the solid content of the lignin-based dye dispersant obtained in each example.

From Table 2, the lignin components of Production Examples 1 to 4 were confirmed to have a peak near 1700 cm ⁻¹ derived from a carboxylic acid by IR analysis of the acidified sample. Therefore, it is understood that the lignin components of Production Examples 1 to 4 have the partial structures represented by the general formulas (1) to (4). On the other hand, regarding the lignin components of Production Examples 5 to 8, when IR analysis was performed on the acidified sample, a peak near 1700 cm ⁻¹ derived from carboxylic acid could not be confirmed. Therefore, it is understood that the lignin components of Production Examples 5 to 8 do not have the partial structures represented by the general formulas (1) to (4).

<Examples 1 to 6, Comparative Examples 1 to 4>
A lignin-based dye dispersant having a partial structure represented by General Formulas (1) to (4) of Production Examples 1 to 4 (Examples 1 to 6), and General Formulas (1) to (of Production Examples 5 to 8). Each of the lignin-based dye dispersants having no partial structure represented by 4) (Comparative Examples 1 to 4) was evaluated. The methods for evaluating the high temperature dispersibility of the dyes shown in Table 3 and the stain resistance on the cloth are described below.

<Preparation of disperse dye solution>
C. I. Disperse Red 60 was mixed with the lignin-based dye dispersants of Examples and Comparative Examples so that the solid content addition rate was 40%, and water was added to prepare a disperse dye solution having a solid content of 35%. This disperse dye solution was crushed by a bead mill (using glass beads having a particle diameter of 1 mm) to prepare a disperse dye solution used for the following evaluation.

<High temperature dispersibility of disperse dye solution>
The prepared disperse dye solution was weighed and diluted with pure water to a dye content of 0.24% to prepare 250 ml (pH 5.0) of a dyeing solution. 10 g of polyester cloth was dyed with a dispersant solution heated to 115° C. for 10 minutes with a dyeing machine. The dyed cloth was lightly washed with water and visually evaluated in the following 5 grades. It can be evaluated that the higher the evaluation point is, the better the dispersibility is.
The results are shown in Table 2.

(Evaluation points)
5: Evenly dyed 4: Somewhat poor uniformity 3: Black spots visible 2: Many black spots 1: Many black spots

<Cloth stain resistance of dye dispersant>
The lignin-based dye dispersants of Examples and Comparative Examples were diluted with pure water to 0.24% to prepare 250 ml of dispersant solution (pH 5.0). 10 g of polyester cloth was dyed with a dispersant solution heated to 130° C. for 60 minutes using a dyeing machine. The dyed cloth was lightly washed with water and dried with an iron to measure the whiteness of the cloth. It can be evaluated that the higher the whiteness, the lower the stain resistance and the better performance.
The results are shown in Table 3.

As shown in Table 3, it can be seen that the lignin-based dye dispersant of the present invention has a high dye dispersibility at high temperature and a high whiteness, and thus has a low staining property on cloth.

Claims (5)

The partial structure (1) represented by the following general formula (1), the partial structure (2) represented by the following general formula (2), the partial structure (3) represented by the following general formula (3), and the following general formula ( A lignin-based dye dispersant containing a lignin component having at least one partial structure selected from the group consisting of the partial structure (4) represented by 4).

(In the general formulas (1) to (4), R represents H or CH _3, and M represents a hydrogen atom, a monovalent metal salt, or a divalent metal salt.) The lignin-based dye dispersant according to claim 1, wherein the lignin component further has a partial structure (5) represented by the following formula (5).

(In the general formula (5), M represents a hydrogen atom, a monovalent metal salt, or a divalent metal salt) The lignin-based dye dispersant according to claim 1 or 2, wherein the lignin component is a product derived from craft lignin. The lignin component further has a reducing sugar,
The lignin-based dye dispersant according to any one of claims 1 to 3, wherein the content of the reducing saccharide is 5.0% by mass or less. A dye composition containing the lignin-based dye dispersant according to any one of claims 1 to 4.