Dye Dispersant

Abstract

A dye dispersant containing a composition obtained through sulfo-methylation of lignin, wherein the composition contains 1.5-4.5 mass% of Na2SO4 and has a S-content of 1.0-6.0 mass% in a group represented by formula (1): -SO3M (in formula (1), M represents a hydrogen atom, a monovalent metal salt, or a divalent metal salt).

Description

[Technical Field]

[0001] The present invention relates to a dye dispersant containing a composition obtained by sulfomethylating lignin. [Background technology]

[0002] Lignin is a natural polymer component found in trees and is produced commercially on a large scale in the papermaking industry, which uses wood as a raw material. For example, kraft lignin is obtained from kraft pulp waste liquor, soda lignin is obtained from soda cooking liquor, and lignosulfonic acid is obtained from sulfite pulp waste liquor. Kraft lignin and lignosulfonic acid, or kraft lignin sulfomethylated with sulfite and formaldehyde, and lignosulfonic acid or lignosulfonic acid salts partially desulfonated or purified by ultrafiltration, are widely used as dispersants in a wide range of industrial fields, including dyes, hydraulic compositions (e.g., cement, gypsum), inorganic and organic pigments, coal-water slurries, pesticides, ceramics, and oil field drilling mud.

[0003] For example, Patent Document 1 discloses the use of modified lignin sulfonates with controlled sulfonic and carboxyl group contents and molecular weights as dye dispersants. Patent Document 2 discloses the use of graft copolymers of lignin sulfonic acid and acrylic or vinyl monomers with a specific molecular weight distribution as cement dispersants. Patent Document 3 discloses a graft copolymer of acrylic acid and lignin sulfonate as a dispersion stabilizer for oilfield drilling mud. Patent Document 4 discloses a lignin derivative formed from a reaction product of lignin sulfonate and a water-soluble monomer having a polyalkylene oxide chain. Patent Documents 5 and 6 disclose the use of sulfonated lignin as a dye dispersant. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-146028 [Patent Document 2] Japanese Patent Application Publication No. 01-145358 [Patent Document 3] U.S. Patent No. 4,322,301 [Patent Document 4] Patent No. 5769930 [Patent Document 5] Japanese Patent Application Publication No. 60-252661 [Patent Document 6] Japanese Patent Application Publication No. 2019-189776 DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0005] However, the conventional lignin-based dispersants described above have the drawback that lignin remains on dyed fabrics, causing discoloration and staining of the dyed fabrics. Furthermore, when used as a dye dispersant for high-temperature dyeing in dyeing polyester fibers and the like, the dispersibility is insufficient, resulting in poor uniformity of dyeing, and there is room for improvement in dispersion stability at high temperatures.

[0006] Therefore, an object of the present invention is to provide a lignin-based dye dispersant that has low staining properties on fabrics and excellent dye dispersibility at high temperatures. [Means for solving the problem]

[0007] As a result of extensive investigations into achieving these objectives, the inventors have discovered that a dye dispersant containing a composition in which lignin is sulfomethylated, and that the composition contains Na2SO4, has low staining properties to fabrics, thereby achieving the above objectives.

[0008] That is, the present invention provides the following inventions. [1] A dye dispersant containing a composition obtained by sulfomethylating lignin, the composition comprising: Formula (1): -SO3M (wherein M represents a hydrogen atom, a monovalent metal salt, or a divalent metal salt) The dye dispersant contains 1.0 to 6.0 mass % of S in the group represented by the formula: and 1.5 to 4.5 mass % of Na2SO4. [2] The dye dispersant according to [1], wherein the raw material lignin for the composition obtained by sulfomethylating lignin is kraft lignin. [3] The dye dispersant according to [1], wherein the raw material lignin for the composition obtained by sulfomethylating lignin is soda lignin. [Effects of the Invention]

[0009] The dye dispersant of the present invention has lower staining properties to fabrics and can exhibit high dye dispersion performance at high temperatures compared to conventional lignin-derived dye dispersants. Furthermore, the lignin-based dye dispersant of the present invention has low staining properties to fabrics and can exhibit good dispersibility even when subjected to high-temperature dyeing, and therefore can exhibit higher dye adsorption properties than conventional lignin-based dye dispersants. In other words, the lignin-based dye dispersant of the present invention has low staining properties to fabrics and excellent dye dispersibility at high temperatures. DETAILED DESCRIPTION OF THE INVENTION

[0010] The dye dispersant of the present invention contains a composition in which lignin is sulfomethylated. <Raw material lignin> Lignins that can be used as raw materials for the sulfomethylated lignin of the present invention include kraft lignin, soda lignin, soda-anthraquinone lignin, organosolv lignin, explosive lignin, lignosulfonic acid, and sulfuric acid lignin. Of these, kraft lignin and soda lignin are preferred. These raw material lignins may be used alone or in combination of two or more.

[0011] (Kraft lignin) Kraft lignin can be used as the raw material lignin in the present invention. Kraft lignin is also known as thiolignin or sulfate lignin. Kraft lignin may be prepared or commercially available. Kraft lignin can be prepared using an alkaline solution of kraft lignin, powdered kraft lignin obtained by spray-drying an alkaline solution of kraft lignin to produce a powder, or acid-precipitated kraft lignin obtained by precipitating an alkaline solution of kraft lignin with an acid.

[0012] (soda lignin) In the present invention, soda lignin can be used as the raw lignin. Soda lignin can be prepared from black liquor obtained by cooking wood chips with caustic soda (NaOH). The liquor ratio of wood chips to cooking liquor during cooking can be, for example, 1.0 to 40 L / g.

[0013] In the soda cooking of the present invention, various cooking aids can be used in addition to caustic soda (NaOH). For example, quinone can be added in an amount of 0.01 to 5% by mass per bone-dry chips.

[0014] The quinones used are known quinone compounds, hydroquinone compounds, or precursors thereof as cooking aids, and at least one compound selected from these can be used, including, for example, anthraquinone, dihydroanthraquinone, tetrahydroanthraquinone, methylanthraquinone, sugar compounds, or precursors thereof.

[0015] The obtained cooking liquor may be used as soda lignin as it is, or lignin purified from it may be used as soda lignin. Powdered soda lignin, which is obtained by spray-drying an alkaline solution of soda lignin (or the obtained cooking liquor) to powder it, and acid-precipitated soda lignin, which is obtained by precipitating an alkaline solution of soda lignin with an acid, can also be used.

[0016] The alkaline solution of kraft lignin or soda lignin can be obtained by known methods such as those described in JP-A-2000-336589, but is not limited to these methods.

[0017] As the acid-precipitated kraft lignin obtained by precipitating an alkaline solution of kraft lignin with an acid, powdery acid-precipitated kraft lignin obtained by methods such as those described in WO2006 / 038863, WO2006 / 031175, and WO2012 / 005677 can be used, but is not limited to these methods. Acid-precipitated soda lignin obtained by precipitating an alkaline solution of soda lignin with an acid can also be obtained as powdery acid-precipitated soda lignin by following the aforementioned method for producing acid-precipitated kraft lignin. Furthermore, the method for producing acid-precipitated soda lignin is not limited to these methods.

[0018] <Method for sulfomethylation of lignin> In the present invention, a composition obtained by sulfomethylating lignin is used as a dye dispersant. In the sulfomethylation reaction of lignin, a sulfone group is generally introduced into the C6-C3 unit of lignin at the position shown in formula (2) below. Formula (2) shows the C6-C3 unit, which is a partial structure of lignin. That is, the reaction indicated by the arrow on the left introduces a sulfone group into the α-position, and is generally called sulfonation. In the reaction indicated by the arrow on the right, a sulfone group is introduced into the 4-position of the aromatic nucleus via formaldehyde, in addition to the α-position.

[0019] Formula (2) [ka]

[0020] The method for obtaining the sulfomethylated lignin composition of the present invention is not particularly limited, but it can be obtained, for example, by adding sulfite and / or bisulfite and aldehydes and treating for a certain period of time. The total mass ratio of sulfite and bisulfite to lignin is preferably 1 to 50 mass%. The reaction temperature is in the range of 50 to 200°C, preferably 80 to 170°C, and more preferably 100 to 160°C. The reaction time is, for example, in the range of 30 minutes to 24 hours. The pH during the reaction is preferably 8 or higher.

[0021] The sulfomethylated lignin composition used in the present invention must have an S content of 1.0 to 6.0 mass% in the sulfonic acid (salt) group represented by -SO3M (in formula (1), M represents a hydrogen atom, a monovalent metal salt, or a divalent metal salt). If the S content of the sulfonic acid (salt) group is less than 1.0 mass%, the hydrophilicity of the sulfomethylated lignin composition is too low, resulting in poor staining resistance and dye dispersibility. On the other hand, if the S content exceeds 6.0 mass%, the hydrophilicity of the sulfomethylated lignin composition is too high, resulting in poor dye dispersibility. Furthermore, M in formula (1) represents a hydrogen atom, a monovalent metal salt, or a divalent metal salt, and is not particularly limited. These may be one or a mixture of two or more types, but it is particularly preferred that M is sodium, or contains sodium.

[0022] The S content of the group represented by -SO3M (in formula (1), M represents a hydrogen atom, a monovalent metal salt, or a divalent metal salt) refers to the content of sulfur atoms contained in -SO3M (in formula (1), M represents a hydrogen atom, a monovalent metal salt, or a divalent metal salt) relative to the solid content of the composition. Specifically, it is a value calculated from the following formula (3): Formula (3): S content of sulfonic acid (salt) groups (mass%) = total S content (mass%) - inorganic S content (mass%) (In formula (3), the S content indicates the S content relative to the solid content of the composition.) In formula (3), the total S content is the total amount of S contained in the composition and can be determined by ICP atomic emission spectrometry. The inorganic S content can be calculated as the sum of the SO, SO, and SO contents determined by ion chromatography.

[0023] The dye dispersant of the present invention must contain Na2SO4, and the content must be 1.5 to 4.5 mass% based on the solid content of the composition. The Na2SO4 content is preferably 1.5 to 4.3 mass%. If the Na2SO4 content exceeds 4.5 mass%, the dye dispersibility will deteriorate. If the Na2SO4 content is less than 1.5 mass%, the staining property on fabric will deteriorate.

[0024] Na2SO4 may be added to the composition obtained by sulfomethylating lignin, or may be added before sulfomethylating lignin, or the composition may contain Na2SO4 as a by-product of the sulfomethylation reaction.

[0025] The Na2SO4 content is a value calculated from the SO4 content determined by ion chromatography using the following formula (4). Formula (4): Na2SO4 content (mass%) = SO4 content (mass%) x 142 / 96 Where 142 is the molecular weight of Na2SO4, and 96 is the molecular weight of SO4

[0026] The weight-average molecular weight of the sulfomethylated lignin composition is preferably 3,000 to 30,000, more preferably 3,000 to 22,000. If the molecular weight is outside the above range, the dye dispersibility at high temperatures will deteriorate. The method for measuring the weight-average molecular weight is not particularly limited, but it can be measured, for example, by the following method.

[0027] (Example of molecular weight measurement method) The weight-average molecular weight is measured, for example, by gel permeation chromatography (GPC). The GPC measurement may be performed by a known method using pullulan as the equivalent under the following conditions.

[0028] Measuring device: Tosoh Columns used: Shodex Column OH-pak SB-806HQ, SB-804HQ, SB-802.5HQ Eluent: 1.0% sodium tetraborate, 0.3% isopropyl alcohol aqueous solution Eluent flow rate; 1.00mL / min Column temperature: 50°C Measurement sample concentration: 0.2% by mass Standard substance: Pullulan (Showa Denko) Detector: UV detector (Tosoh) Calibration curve; pullulan standard [Example]

[0029] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to the following examples, and can be practiced with appropriate modifications within the scope of the spirit of the preceding and following descriptions, all of which are included in the technical scope of the present invention. In the examples, % means % by mass, and parts means parts by weight, unless otherwise specified.

[0030] <Kraft lignin separation> Kraft lignin was isolated by a known method. Specifically, carbon dioxide was passed through softwood (Northwood) kraft cooking black liquor to lower the pH of the black liquor to 10, and primary filtration was performed. The black liquor was redispersed in water, the pH was lowered to 2 with sulfuric acid, secondary filtration was performed, and the resulting mixture was washed with water and dried to obtain Northwood kraft lignin.

[0031] <Production Example 1> A 1-liter autoclave equipped with a reflux condenser was charged with 500 parts of a solution of natural wood kraft lignin dissolved in NaOH at pH 10 to a solids content of 20%, 8 parts of sodium sulfite, 2 parts of sodium bisulfite, and 7 parts of a 37% formaldehyde solution, and the mixture was reacted at 110°C for 120 minutes. After cooling to room temperature, a sulfomethylated product of natural wood kraft lignin (A-1) was obtained.

[0032] <Production Example 2> A 1-liter autoclave equipped with a reflux condenser was charged with 500 parts of a solution of natural wood kraft lignin dissolved in NaOH at pH 10 to a solids content of 20%, 19 parts of sodium sulfite, 1 part of sodium bisulfite, and 14 parts of a 37% formaldehyde solution, and the mixture was reacted at 120°C for 150 minutes. After cooling to room temperature, a sulfomethylated product of natural wood kraft lignin (A-2) was obtained.

[0033] <Production Example 3> A 1-liter autoclave equipped with a reflux condenser was charged with 500 parts of a solution of natural wood kraft lignin dissolved in NaOH at pH 10 to a solid content of 20%, 30 parts of sodium sulfite, and 25 parts of a 37% formaldehyde solution, and the mixture was reacted at 150°C for 180 minutes. After cooling to room temperature, a sulfomethylated product of natural wood kraft lignin (A-3) was obtained.

[0034] <Production Example 4> <Soda lignin separation> Soda lignin was isolated by a known method. Specifically, carbon dioxide was passed through softwood (Northwood) soda cooking black liquor to lower the pH to 10, and primary filtration was performed. The black liquor was redispersed in water, the pH was lowered to 2 with sulfuric acid, secondary filtration was performed, and the liquor was washed with water and dried to obtain softwood soda lignin. A 1-liter autoclave equipped with a reflux condenser was charged with 500 parts of a solution of the above-obtained soda lignin dissolved in NaOH at pH 10 to a solids content of 20%, 25 parts of sodium sulfite, and 21 parts of a 37% formaldehyde solution, and the mixture was reacted at 120°C for 180 minutes. After cooling to room temperature, a sulfomethylated product of soda lignin (A-4) was obtained.

[0035] <Comparative Manufacturing Example 1> A 1-liter autoclave equipped with a reflux condenser was charged with 500 parts of a solution of natural wood kraft lignin dissolved in NaOH at pH 10 to a solid content of 20%, 5 parts of sodium sulfite, and 14 parts of a 37% formaldehyde solution, and the mixture was reacted at 150°C for 240 minutes. After cooling to room temperature, a sulfomethylated product of natural wood kraft lignin (B-1) was obtained.

[0036] <Comparative Manufacturing Example 2> A 1-liter autoclave equipped with a reflux condenser was charged with 500 parts of a solution of natural wood kraft lignin dissolved in NaOH at pH 10 to a solid content of 20%, 20 parts of sodium sulfite, and 14 parts of a 37% formaldehyde solution, and the mixture was reacted at 140°C for 120 minutes. After cooling to room temperature, a sulfomethylated product of natural wood kraft lignin (B-2) was obtained.

[0037] <Comparative Manufacturing Example 3> A 1-liter autoclave equipped with a reflux condenser was charged with 500 parts of a solution of natural wood kraft lignin dissolved in NaOH at pH 10 to a solid content of 20%, 40 parts of sodium sulfite, and 30 parts of a 37% formaldehyde solution, and the mixture was reacted at 140°C for 120 minutes. After cooling to room temperature, a sulfomethylated product of natural wood kraft lignin (B-3) was obtained.

[0038] Table 1 shows the compositions obtained in Production Examples 1 to 4 and Comparative Production Examples 1 to 3.

[0039] [Table 1] In Table 1, % represents mass % relative to the solid content of the composition obtained in each production example.

[0040] <Examples 1 to 5 and Comparative Examples 1 to 4> The staining and dispersibility of the dyes shown in Table 2 on fabrics were evaluated as follows for the dye dispersants containing the sulfomethylated N-wood kraft lignin compositions of Production Examples 1 to 3 (Examples 1 to 3), the dye dispersant containing the sulfomethylated N-wood soda lignin composition of Production Example 4 (Example 4), the dye dispersant in which Na2SO4 was added to the sulfomethylated N-wood kraft lignin composition of Production Example 3 so that the amount was 3.0 mass% (A-5, Example 5), the dye dispersants containing the sulfomethylated N-wood kraft lignin compositions of Comparative Production Examples 1 to 3 (Comparative Examples 1 to 3), and the dye dispersant containing N-wood kraft lignin (Comparative Example 4).

[0041] <Fabric staining by dye dispersants> The dispersants shown in Table 2 were diluted with pure water to a concentration of 0.24% to prepare 250 mL of dispersant solution (pH 5.0). 10 g of polyester fabric was dyed for 60 minutes using a dyeing machine with the dispersant solution heated to 130°C. After dyeing, the fabric was lightly rinsed with water, dried with an iron, and the whiteness of the fabric was measured. A higher whiteness indicates lower staining and better performance.

[0042] <Dye dispersibility test> <Preparation of disperse dyes> The dispersants of the Examples and Comparative Examples were mixed with CI Disperse Blue 79.1 to a solid content of 50%, and water was added to prepare a disperse dye solution with a solid content of 35%. This disperse dye solution was crushed in a bead mill (using glass beads with a particle size of 1 mm) to prepare the disperse dye solution used in the following evaluations.

[0043] <High-temperature dispersibility of disperse dyes> The disperse dye solution was weighed and diluted with pure water to a dye concentration of 0.28% to prepare 250 mL of dye solution (pH 5.0). 10 g of polyester fabric was dyed in a dyeing machine for 10 minutes using the dye solution heated to 115°C. After dyeing, the fabric was lightly rinsed with water and visually evaluated on a 5-point scale. A higher evaluation score indicates better dispersibility.

[0044] (Evaluation points) 5: Uniformly dyed 4: Slightly poor uniformity 3: Black dots are visible 2: Many black dots 1: There are a lot of black dots The evaluation results are shown in Table 2.

[0045] [Table 2]

[0046] As shown in Table 2, the dye dispersant of the present invention has a higher whiteness and therefore less staining on fabric than the dispersant of Comparative Example 1. It also has better dye dispersibility than the dispersants of Comparative Examples 2 and 3. Furthermore, the dispersant of Comparative Example 4 has poor staining on fabric and extremely poor dye dispersibility, making it unsuitable as a dye dispersant.

Claims

1. A dye dispersant containing a composition obtained by sulfomethylating lignin, The composition comprises: Formula (1): -SO ３ M (in formula (1), M represents a hydrogen atom, a monovalent metal salt, or a divalent metal salt), The S content of the group represented by the formula (I) is 1.0 to 6.0 mass %, and Na 2 SO 4 Contains 1.5 to 3.0 mass% of The dye dispersant contains 1.5 to 3.0% by mass of Na 2 SO 4 .

2. 2. The dye dispersant according to claim 1, wherein the raw material lignin for the composition obtained by sulfomethylating lignin is kraft lignin.

3. 2. The dye dispersant according to claim 1, wherein the raw material lignin for the composition obtained by sulfomethylating lignin is soda lignin.

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