Low-melting-point red disperse dye as well as preparation method and application thereof

Abstract

The invention provides a low-melting-point red disperse dye as well as a preparation method and application thereof, and particularly relates to the technical field of dye chemical industry. The low-melting-point red disperse dye has a # imgabs0 # structure, and in the formula, R1 is nitro, chlorine, bromine or cyano; r2 is alkyl of C1-C6 or hydrogen; r3 is an alkyl group of C1 to C6; r4 is an alkylene group of C1 to C6; and R5 is an alkyl group of C1 to C6. The melting point of the low-melting-point red disperse dye ranges from 106 DEG C to 108 DEG C and is lower than the dyeing temperature, and due to the low-melting-point characteristic, the low-melting-point red disperse dye can directly and effectively dye polyester fibers and blended fabrics of the polyester fibers under the condition of not depending on traditional dispersing agents. The dye disclosed by the invention not only has the advantages in melting point, but also has very excellent dyeing performance which is specifically shown in the following aspects: the color fastness to washing is grade 4-5, the color fastness to perspiration is grade 4, the color fastness to sublimation is grade 3-4, the color fastness to sunlight is grade 5-6, and the performance is excellent.

Description

Technical Field

[0001] The invention relates to the technical field of dye chemical industry, in particular to a low melting point red disperse dye and a preparation method and application thereof. Background Art

[0002] Disperse dyes have a simple molecular structure and do not contain water-soluble groups. They have extremely low solubility in water and usually exist in a non-ionic state. This type of dye needs to rely on the role of a dispersant during the dyeing process to ensure that the dye is evenly dispersed in the dye solution. Disperse dyes are mainly used for dyeing synthetic fibers such as polyester fibers, acetate fibers, and polyamide fibers. They are usually dyed using a high temperature and high pressure method, with a dyeing temperature of about 130°C and a time control of 30 to 60 minutes.

[0003] Since disperse dyes have extremely poor water solubility, they rely almost entirely on the hydrophilic dye colloids formed by dispersants to achieve dispersion in water. However, most disperse dyes have a high melting point, between about 140 and 200°C, which means that even at a dyeing temperature of 130°C, it is difficult for the dye to melt completely. During the heating, insulation and cooling stages of the dyeing process, the dye colloids may break due to the influence of high temperature and shear force of the dye solution, resulting in a decrease in the binding energy between the dye and the dispersant. Free dye crystals tend to aggregate to form larger dye aggregates due to their high melting point and repulsion by water. This situation may lead to a decrease in the color, brightness and color fastness of the fabric. In severe cases, it may also combine with suspended matter such as polyester oligomers and cilia in the dye solution to form tar-like substances, resulting in tar spots on the fabric that cannot be removed.

[0004] In addition, dispersants used in the production of disperse dyes may contain harmful substances such as quinoline, polycyclic aromatic hydrocarbons, and formaldehyde, which are the focus of environmental protection issues. With the increasingly stringent environmental protection regulations, these issues have gradually received attention.

[0005] At present, although there is no clear solution in the industry, the market urgently needs a new type of red disperse dye, which should have a lower melting point and reduce the dependence on dispersants while maintaining excellent dyeing properties. Such dyes will help reduce environmental pollution and improve dyeing efficiency and quality.

[0006] In view of this, the present invention is proposed. Summary of the invention

[0007] One of the purposes of the present invention is to provide a low melting point red disperse dye to alleviate the technical problems in the prior art that the red disperse dye has a high melting point, must be combined with a dispersant to complete dyeing, and has poor dyeing performance at high temperatures.

[0008] A second object of the present invention is to provide a method for preparing a low melting point red disperse dye.

[0009] The third object of the present invention is to provide a low melting point red disperse dye for use in dyeing or printing polyester fibers and their blended fiber products.

[0010] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0011] The first aspect of the present invention provides a low melting point red disperse dye having a structure shown in Formula I:

[0012]

[0013] Among them, R1 is nitro, chlorine, bromine or cyano; R2 is C1-C6 alkyl or hydrogen; R3 is C1-C6 alkyl; R4 is C1-C6 alkylene; R5 is C1-C6 alkyl.

[0014] Furthermore, R1 is nitro, chlorine, bromine or cyano; R2 is C1-C4 alkyl or hydrogen; R3 is C1-C4 alkyl; R4 is C1-C4 alkylene; R5 is C1-C4 alkyl.

[0015] Furthermore, R1 is nitro, chlorine or cyano; R2 is methyl, ethyl or hydrogen; R3 is methyl, ethyl or propyl; R4 is methylene, ethylene or propylene; R5 is methyl, ethyl or propyl.

[0016] The second aspect of the present invention provides a method for preparing the low melting point red disperse dye, comprising the following steps:

[0017] A. Adding compound 2 represented by formula II into the first acid solution, and then adding a diazotizing agent to carry out diazotization reaction to obtain a diazo liquid;

[0018]

[0019] B. dropwise adding the diazo solution and the compound 3 represented by formula III into the second acid solution for coupling reaction, followed by filtering, washing and drying to obtain the low melting point red disperse dye;

[0020]

[0021] Among them, R1 is nitro, chlorine, bromine or cyano; R2 is C1-C6 alkyl or hydrogen; R3 is C1-C6 alkyl; R4 is C1-C6 alkylene; R5 is C1-C6 alkyl.

[0022] Furthermore, the first acid solution is an aqueous sulfuric acid solution.

[0023] Preferably, the concentration of the aqueous sulfuric acid solution is 55 to 85%, preferably 60 to 80%.

[0024] Preferably, the acid in the second acid solution includes at least one of sulfuric acid, hydrochloric acid and acetic acid.

[0025] Furthermore, the diazotization reagent includes nitrosyl sulfuric acid.

[0026] Preferably, the molar ratio of the acid in the first acid solution, the compound 2 and the diazotizing agent is (2-6):1:(1-1.2), preferably (3-5):1:(1-1.1).

[0027] Preferably, the molar ratio of the compound 3 to the compound 2 is (1-1.2):1, preferably (1-1.1):1.

[0028] Furthermore, the temperature of the diazotization reaction is 0 to 50°C, preferably 10 to 40°C.

[0029] Preferably, the diazotization reaction time is 1 to 4 hours, preferably 1 to 3 hours.

[0030] Preferably, the coupling reaction temperature is 0-25°C, preferably 0-10°C.

[0031] Preferably, the coupling reaction time is 1 to 5 hours, preferably 1 to 3 hours.

[0032] Preferably, the pH of the coupling reaction is 1-5, preferably 2-4.

[0033] Furthermore, the preparation method of the compound 3 is: uniformly mixing the compound 4 represented by formula IV and the compound 5 represented by formula V, and then adding a base and a catalyst to carry out a condensation reaction to obtain the compound 3;

[0034]

[0035] Formula V: CIR4COOR5

[0036] Among them, R2 is a C1-C6 alkyl group or hydrogen; R3 is a C1-C6 alkyl group; R4 is a C1-C6 alkylene group; R5 is a C1-C6 alkyl group.

[0037] Preferably, the molar ratio of the compound 4 to the compound 5 is 1:(1-5), preferably 1:(2-4).

[0038] Furthermore, the alkali includes at least one of anhydrous sodium carbonate, sodium hydroxide and sodium bicarbonate.

[0039] Preferably, the molar ratio of the base to the compound 4 is (1-3):2, preferably (1-2):2.

[0040] Preferably, the catalyst comprises at least one of sodium bromide, potassium iodide and potassium bromide.

[0041] Preferably, the molar ratio of the catalyst to the compound 4 is 1:(2-6), preferably 1:(3-5).

[0042] Preferably, the temperature of the condensation reaction is 0 to 200°C, preferably 50 to 150°C.

[0043] Preferably, the condensation reaction time is 3 to 20 hours, preferably 3 to 15 hours.

[0044] The third aspect of the present invention provides the use of the low melting point red disperse dye in dyeing or printing polyester fiber and its blended fiber products.

[0045] Compared with the prior art, the present invention has at least the following beneficial effects:

[0046] The low melting point red disperse dye provided by the present invention has a melting point between 106°C and 108°C, which is lower than the dyeing temperature. Thanks to the low melting point characteristic, the dye can directly dye polyester fibers and their blended fabrics effectively without relying on traditional dispersants. This dyeing method not only simplifies the dyeing process, but also reduces the production cost and the risk of environmental pollution. After dyeing polyester fibers and their blended fabrics with the dye of the present invention, a bright red effect can be obtained. This dye can not only be used as a monochrome dye, but also can be combined with other disperse dyes with similar characteristics and dyeing properties to create more diverse color effects. In addition, the dye of the present invention not only has advantages in melting point, but also has excellent dyeing performance, which is specifically manifested in the following aspects: the color fastness to washing is 4 to 5 levels, the color fastness to perspiration is 4 levels, the color fastness to sublimation is 3 to 4 levels, and the color fastness to sunlight is 5 to 6 levels, with excellent performance.

[0047] The preparation method provided by the present invention has continuous process steps, simple process, lower energy consumption, and is helpful to reduce production costs and reduce the impact on the environment.

[0048] The application provided by the present invention, in view of the advantages of the above-mentioned low melting point red disperse dye, reduces the production cost of dyeing or printing, simplifies the dyeing process, improves production efficiency, improves economic benefits, and broadens its application scope in the textile industry. DETAILED DESCRIPTION

[0049] The embodiments of the present invention will be described in detail below in conjunction with the embodiments and examples, but those skilled in the art will understand that the following embodiments and examples are only used to illustrate the present invention and should not be considered to limit the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0050] The first aspect of the present invention provides a low melting point red disperse dye having a structure shown in Formula I:

[0051]

[0052] Among them, R1 is nitro, chlorine, bromine or cyano; R2 is C1-C6 alkyl or hydrogen; R3 is C1-C6 alkyl; R4 is C1-C6 alkylene; R5 is C1-C6 alkyl.

[0053] The low melting point red disperse dye provided by the present invention has a melting point between 106°C and 108°C, which is lower than the dyeing temperature. Thanks to the low melting point characteristic, the dye can directly dye polyester fibers and their blended fabrics effectively without relying on traditional dispersants. This dyeing method not only simplifies the dyeing process, but also reduces the production cost and the risk of environmental pollution. After dyeing polyester fibers and their blended fabrics with the dye of the present invention, a bright red effect can be obtained. This dye can not only be used as a monochrome dye, but also can be combined with other disperse dyes with similar characteristics and dyeing properties to create more diverse color effects. In addition, the dye of the present invention not only has advantages in melting point, but also has excellent dyeing performance, which is specifically manifested in the following aspects: the color fastness to washing is 4 to 5 levels, the color fastness to perspiration is 4 levels, the color fastness to sublimation is 3 to 4 levels, and the color fastness to sunlight is 5 to 6 levels, with excellent performance.

[0054] Typically, but not limiting, R1 can be selected from nitro, chloro, bromo or cyano; R2 can be selected from hydrogen, methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl or hexyl; R3 can be selected from methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl or hexyl; R4 can be selected from methylene, ethylene, propylene, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl or hexyl; R5 can be selected from methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl or hexyl.

[0055] It should be noted that R3 and R5 are relatively independent and can be the same group or different groups, and there is no correlation between the specific groups of the two.

[0056] Furthermore, R1 is nitro, chlorine, bromine or cyano; R2 is C1-C4 alkyl or hydrogen; R3 is C1-C4 alkyl; R4 is C1-C4 alkylene; R5 is C1-C4 alkyl.

[0057] Furthermore, R1 is nitro, chlorine or cyano; R2 is methyl, ethyl or hydrogen; R3 is methyl, ethyl or propyl; R4 is methylene, ethylene or propylene; R5 is methyl, ethyl or propyl.

[0058] The second aspect of the present invention provides a method for preparing the low melting point red disperse dye, comprising the following steps:

[0059] A. Adding compound 2 represented by formula II into the first acid solution, and then adding a diazotizing agent to carry out diazotization reaction to obtain a diazo liquid;

[0060]

[0061] B. dropwise adding the diazo solution and the compound 3 represented by formula III into the second acid solution for coupling reaction, followed by filtering, washing and drying to obtain the low melting point red disperse dye;

[0062]

[0063] Among them, R1 is nitro, chlorine, bromine or cyano; R2 is C1-C6 alkyl or hydrogen; R3 is C1-C6 alkyl; R4 is C1-C6 alkylene; R5 is C1-C6 alkyl.

[0064] The preparation method provided by the present invention has continuous process steps, simple process, lower energy consumption, and is helpful to reduce production costs and reduce the impact on the environment.

[0065] The reaction formula of the above reaction is:

[0066]

[0067] Furthermore, the first acid solution is an aqueous sulfuric acid solution.

[0068] Preferably, the concentration of the aqueous sulfuric acid solution is 55 to 85%, preferably 60 to 80%.

[0069] Typically but not limiting, the concentration of the aqueous sulfuric acid solution can be 55%, 60%, 65%, 70%, 75%, 80% or 85%, or any value within the range of 55% to 85%; within this preferred range, the concentration of the aqueous sulfuric acid solution can more preferably be 60%, 65%, 70%, 75% or 80%, or any value within the range of 60% to 80%.

[0070] Preferably, the acid in the second acid solution includes at least one of sulfuric acid, hydrochloric acid and acetic acid.

[0071] Furthermore, the diazotization reagent includes nitrosyl sulfuric acid.

[0072] Preferably, the molar ratio of the acid in the first acid solution, the compound 2 and the diazotizing agent is (2-6):1:(1-1.2), preferably (3-5):1:(1-1.1).

[0073] Typically, but not limiting, the molar ratio of acid: compound 2: diazotizing agent can be, for example, 2:1:1, 3:1:1, 4:1:1, 5:1:1, 6:1:1, 2:1:1.1, 3:1:1.1, 4:1:1.1, 5:1:1.1, 6:1:1.1, 2:1:1.2, 3:1:1.2, 4:1:1.2, 5:1:1.2 or 6:1:1.2, or any value within the range of (2 to 6):1:(1 to 1.2).

[0074] Preferably, the molar ratio of the compound 3 to the compound 2 is (1-1.2):1, preferably (1-1.1):1.

[0075] Typically but not limiting, the molar ratio of compound 3 to compound 2 can be, for example, 1:1, 1.1:1 or 1.2:1, or any value within the range of (1 to 1.2):1.

[0076] Preferably, the temperature of the diazotization reaction is 0 to 50°C, preferably 10 to 40°C.

[0077] Typically but not restrictively, the temperature of the diazotization reaction can be 0°C, 5°C, 10°C, 15°C, 20°C, 30°C, 40°C or 50°C, or any value in the range of 0°C to 50°C; in particular, the temperature of the diazotization reaction can preferably be 10°C, 12°C, 14°C, 16°C, 18°C, 20°C, 30°C or 40°C, or any value in the range of 10°C to 40°C.

[0078] Preferably, the diazotization reaction time is 1 to 4 hours, preferably 1 to 3 hours.

[0079] It should be noted that the progress of the diazotization reaction can be monitored by conventional testing methods in the art (such as TLC), and the disappearance of compound 2 is regarded as the end point of the reaction.

[0080] Typically but not limiting, the diazotization reaction time can be 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours or 4 hours, or any value within the range of 1 hour to 4 hours; in particular, the diazotization reaction time can preferably be 1 hour, 1.25 hours, 1.5 hours, 1.75 hours, 2 hours, 2.25 hours, 2.5 hours or 3 hours, or any value within the range of 1 hour to 3 hours.

[0081] Furthermore, the coupling reaction temperature is 0 to 25°C, preferably 0 to 10°C.

[0082] Typically but not limiting, for the coupling reaction, the temperature can be 0°C, 5°C, 10°C, 15°C, 20°C or 25°C, or any value in the range of 0°C to 25°C; in particular, the temperature of the coupling reaction is preferably 0°C, 1°C, 2°C, 3°C, 4°C, 5°C, 6°C, 7°C, 8°C or 10°C, or any value in the range of 0°C to 10°C.

[0083] Preferably, the coupling reaction time is 1 to 5 hours, preferably 1 to 3 hours.

[0084] The progress of the coupling reaction can be monitored by conventional testing methods in the art (such as the colorimetric method), and the color development of compound 3 in slight excess is regarded as the reaction endpoint.

[0085] Typically but not limiting, the coupling reaction time can be 1 hour, 2 hours, 3 hours, 4 hours or 5 hours, or any value within the range of 1 hour to 5 hours; in particular, the coupling reaction time can preferably be 1 hour, 1.25 hours, 1.5 hours, 1.75 hours, 2 hours, 2.25 hours, 2.5 hours or 3 hours, or any value within the range of 1 hour to 3 hours.

[0086] Preferably, the pH of the coupling reaction is 1-5, preferably 2-4.

[0087] Typically but not limiting, the pH value of the coupling reaction can be 1, 2, 3, 4 or 5, or any value in the range of 1-5; in particular, the pH value is preferably 2, 3 or 4, or any value in the range of 2-4.

[0088] Furthermore, the preparation method of the compound 3 is: uniformly mixing the compound 4 represented by formula IV and the compound 5 represented by formula V, and then adding a base and a catalyst to carry out a condensation reaction to obtain the compound 3;

[0089]

[0090] Formula V: CIR4COOR5

[0091] Among them, R2 is a C1-C6 alkyl group or hydrogen; R3 is a C1-C6 alkyl group; R4 is a C1-C6 alkylene group; R5 is a C1-C6 alkyl group.

[0092] The specific reaction formula is:

[0093]

[0094] Preferably, the molar ratio of the compound 4 to the compound 5 is 1:(1-5), preferably 1:(2-4).

[0095] Typically but not limiting, the molar ratio of compound 4 to compound 5 can be, for example, 1:1, 1:2, 1:3, 1:4 or 1:5, or any value within the range of 1:(1-5).

[0096] Furthermore, the alkali includes at least one of anhydrous sodium carbonate, sodium hydroxide and sodium bicarbonate.

[0097] Preferably, the molar ratio of the base to the compound 4 is (1-3):2, preferably (1-2):2.

[0098] Typically but not limiting, the molar ratio of the base to the compound 4 can be, for example, 1:2, 2:2 or 3:2, or any value within the range of (1 to 3):2.

[0099] Preferably, the catalyst comprises at least one of sodium bromide, potassium iodide and potassium bromide.

[0100] Preferably, the molar ratio of the catalyst to the compound 4 is 1:(2-6), preferably 1:(3-5).

[0101] Typically but not limiting, the molar ratio of the catalyst to the compound 4 can be, for example, 1:2, 1:3, 1:4, 1:5 or 1:6, or any value within the range of 1:(2-6).

[0102] Preferably, the temperature of the condensation reaction is 0 to 200°C, preferably 50 to 150°C.

[0103] Typically but not limiting, the temperature of the condensation reaction can be 0°C, 25°C, 50°C, 75°C, 100°C, 125°C, 150°C, 175°C or 200°C, or any value in the range of 0°C to 200°C; in particular, the temperature of the condensation reaction is preferably 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C or 150°C, or any value in the range of 50°C to 150°C.

[0104] Preferably, the condensation reaction time is 3 to 20 hours, preferably 3 to 15 hours.

[0105] The progress of the condensation reaction can be monitored by conventional testing methods in the art (such as HPLC), and the reaction endpoint is when the reaction of compound 4 reaches ≤1%.

[0106] Typically but not limiting, the condensation reaction time can be 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours or 15 hours, or any value in the range of 3 hours to 20 hours; in particular, the condensation reaction time is preferably 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours, 5.5 hours, 6 hours, 6.5 hours, 7 hours, 7.5 hours, 8 hours, 8.5 hours, 9 hours, 9.5 hours, 10 hours, 10.5 hours, 11 hours, 11.5 hours, 12 hours, 12.5 hours, 13 hours, 13.5 hours or 14 hours, or any value in the range of 3 hours to 15 hours.

[0107] The third aspect of the present invention provides the use of the low melting point red disperse dye in dyeing or printing polyester fiber and its blended fiber products.

[0108] The application provided by the present invention, in view of the advantages of the above-mentioned low melting point red disperse dye, reduces the production cost of dyeing or printing, simplifies the dyeing process, improves production efficiency, improves economic benefits, and broadens its application scope in the textile industry.

[0109] When used, the red disperse dye can be directly processed according to conventional methods (such as sand milling, spray drying) without adding a dispersant.

[0110] The polyester fibers referred to include polyethylene terephthalate fibers (polyester) and their blends with cotton, viscose, spandex and other materials. These are common polyester fibers and their blended products.

[0111] Blended fiber products can be in common forms such as fibers, yarns, fabrics, knitwear or nonwovens.

[0112] The present invention is further illustrated below by specific examples and comparative examples, however, it should be understood that these examples are only used for more detailed description and should not be understood as limiting the present invention in any form. The raw materials used in the examples and comparative examples of the present invention, if no specific conditions are specified, are carried out under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used without indicating the manufacturer are all conventional products that can be purchased commercially. The LC-MS data described in the present invention are obtained by testing with a Waters UPLC-SQD liquid-mass spectrometer (the mobile phase is an acetonitrile / water system, 60%-90% acetonitrile V / V, and the column temperature is 40°C).

[0113] Example 1

[0114] This embodiment provides a compound 3-1, whose structural formula is shown in the following formula III-1:

[0115]

[0116] Among them, R2 is methyl, R3 is ethyl, R4 is methylene, and R5 is methyl.

[0117] The preparation method is as follows:

[0118] 1. Add 0.2 mol of N-ethyl-m-toluidine to a 250 mL three-necked flask, then add 0.5 mol of methyl chloroacetate under stirring, stir evenly, add 0.15 mol of anhydrous sodium carbonate and 0.05 mol of potassium iodide, stir evenly, and slowly heat to 120°C. Control the temperature at 115-120°C for 6 hours, take a sample and test and analyze the N-ethyl-m-toluidine ≤1%, and the condensation reaction is complete.

[0119] 2. Then cool down and add 100 mL of water. Stir evenly and then heat to 60-70°C. Let stand while hot to separate the layers. Collect the organic phase and distill under reduced pressure to 100°C to remove water and excess methyl chloroacetate to obtain compound 3-1 with a purity of more than 98%.

[0120] Embodiments 2 to 6

[0121] Examples 2 to 6 provide different compounds 3, respectively, and the corresponding groups, purity and structure identification data are shown in Table 1 below.

[0122] Table 1

[0123]

[0124] Example 7

[0125] This embodiment provides a low melting point red disperse dye, the structural formula of which is shown in the following formula I-1:

[0126]

[0127] Among them, R1 is cyano, R2 is methyl, R3 is ethyl, R4 is methylene, and R5 is methyl.

[0128] The preparation method is as follows:

[0129] 1. Add 20.38g of sulfuric acid to a 100mL three-necked flask, add 7.28g of water while stirring, cool to 20-25℃, add 8.16g of o-cyano-p-nitroaniline, then slowly add 17.46g of nitrosyl sulfuric acid at a temperature of 20-25℃, add dropwise for about 45-60min, and after addition, keep warm at 20-25℃ for 2-3h to obtain diazo solution.

[0130] 2. Then, the compound 3-1 provided in Example 1 was added dropwise within 1 hour for coupling reaction, the reaction temperature was controlled to 0-5°C with ice, and the coupling was completed at 0-5°C for 2 hours, and the mixture was stirred naturally to room temperature, filtered, washed with water, and dried to obtain 17.77 g of dye filter cake containing compound I-1, with a yield of 93.3%.

[0131] 3. Take 25 g of compound Ⅰ-1 and 37.5 g of water and grind them with a sand mill. After grinding, spray dry them to obtain a low melting point red disperse dye.

[0132] Example 8-24

[0133] According to the preparation method of Example 7, compound 3 of Examples 1-6 was selected to obtain a low melting point red disperse dye of the corresponding structure. The specific groups, purity and structure identification data are shown in Table 2.

[0134] Table 2

[0135]

[0136]

[0137] Comparative Example 1

[0138] This comparative example provides a dark red PUD-SD-BS original dye (without dispersant), the structural formula of which is as follows:

[0139]

[0140] Comparative Example 2

[0141] This comparative example provides a sauce red PUD-4BS-BS original dye (without dispersant), the structural formula of which is as follows:

[0142]

[0143] Comparative Example 3

[0144] This comparative example provides a deep red PUD-SD-BS commercial dye (containing a dispersant), wherein the mass ratio of the original dye to the dispersant is 1:1.5.

[0145] Comparative Example 4

[0146] This comparative example provides a maroon red PUD-4BS-BS commercial dye (containing a dispersant), wherein the mass ratio of the original dye to the dispersant is 1:1.5.

[0147] Test Example 1

[0148] Take 0.5 g of the disperse dye of Example and Comparative Examples 1-2 and dissolve it in 500 ml of DMF to form a dye solution, absorb 50 ml of the suspension and mix it with 50 ml of water, adjust the pH value of the dye bath to 4-5 with acetic acid, heat it to 60°C, put 5 g of polyester fiber cloth in each, heat it to 130°C within 30 minutes, keep it warm for 50 minutes, cool it down, wash it with water, perform reduction cleaning, and finally pickle it, wash it with water, and dry it.

[0149] The dyed fabric sample of Example 7 was used as a standard to test the dyeing strength of the polyester fiber fabric. The results are shown in Table 3 below.

[0150] Test Example 2

[0151] 0.5 g of the disperse dye of Comparative Example 3-4 was dissolved in 500 ml of water to form a dye suspension. According to the method of Test Example 1, the dyed fabric sample of Example 7 was used as a standard to level the fabric to the same depth. The results are listed in Table 3.

[0152] Table 3

[0153]

[0154]

[0155] In Table 3, "inaccurate intensity" refers to the uneven phenomenon of the fabric sample during the dyeing process, resulting in different shades of color. This uneven dyeing makes the test results inaccurate. Specifically, darker areas may show higher intensity values, while lighter areas may show lower intensity values. Therefore, such test results cannot truly reflect the dyeing effect, and its data has no reference value. In the dyeing intensity, "1.37%" means that the weight of the dye is 1.37wt% relative to the weight of the fabric, and "1.26%" means that the weight of the dye is 1.26wt.% relative to the weight of the fabric.

[0156] It can be seen from Table 3 above that the red disperse dyes of Examples 7-24 have a relatively low melting point of 106-108°C, and can melt in the dye solution and evenly adhere to the fabric at a dyeing temperature below 130°C. There is no need to use a dispersing agent to disperse the dye, and there are no dyeing spots or color spots on the dyed fabric. However, the deep red PUD-SD-BS original dye (without dispersant) of Comparative Example 1 and the soy sauce red PUD-4BS-BS original dye (without dispersant) of Comparative Example 2 have higher melting points. Without the use of a dispersant, dyeing spots and color spots appear on the dyed fabric. The results are far inferior to those of the disperse dyes of the present invention. Comparative Examples 1 and 2 must rely on more dispersants to achieve the same dyeing effect.

[0157] Test Example 2

[0158] The dyed fabric samples of the embodiment and the comparative example were tested for their color fastness to washing, perspiration, sunlight and sublimation respectively according to ISO 105C10 C (3), ISO 105E04, ISO 105B02 and GB / T 5718-1997. The test results are recorded in Table 4.

[0159] Table 4

[0160]

[0161] The values ​​in the above table for wash resistance, perspiration resistance, sunlight resistance and sublimation color fastness refer to grades.

[0162] It can be seen from the results in Table 4 that the red disperse dye of the present invention also has excellent dyeing performance and dyeing fastness.

[0163] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A low melting point red disperse dye, characterized in that: It has the structure shown in formula I: Among them, R1 is nitro, chlorine, bromine or cyano; R2 is C1-C6 alkyl or hydrogen; R3 is C1-C6 alkyl; R4 is C1-C6 alkylene; R5 is C1-C6 alkyl.

2. The low melting point red disperse dye according to claim 1, characterized in that R1 is nitro, chlorine, bromine or cyano; R2 is C1-C4 alkyl or hydrogen; R3 is C1-C4 alkyl; R4 is C1-C4 alkylene; R5 is C1-C4 alkyl.

3. The low melting point red disperse dye according to claim 1, characterized in that R1 is nitro, chlorine or cyano; R2 is methyl, ethyl or hydrogen; R3 is methyl, ethyl or propyl; R4 is methylene, ethylene or propylene; R5 is methyl, ethyl or propyl.

4. A method for preparing a low melting point red disperse dye according to any one of claims 1 to 3, characterized in that: The following steps are involved: A. Adding compound 2 represented by formula II into the first acid solution, and then adding a diazotizing agent to carry out diazotization reaction to obtain a diazo liquid; B. dropwise adding the diazo solution and the compound 3 represented by formula III into the second acid solution for coupling reaction, followed by filtering, washing and drying to obtain the low melting point red disperse dye; Among them, R1 is nitro, chlorine, bromine or cyano; R2 is C1-C6 alkyl or hydrogen; R3 is C1-C6 alkyl; R4 is C1-C6 alkylene; R5 is C1-C6 alkyl.

5. The preparation method according to claim 4, characterized in that: The first acid solution is an aqueous solution of sulfuric acid; Preferably, the concentration of the aqueous sulfuric acid solution is 55 to 85%, preferably 60 to 80%; Preferably, the acid in the second acid solution includes at least one of sulfuric acid, hydrochloric acid and acetic acid.

6. The preparation method according to claim 4, characterized in that: The diazotizing agent includes nitrosyl sulfuric acid; Preferably, the molar ratio of the acid in the first acid solution, the compound 2 and the diazotizing agent is (2-6):1:(1-1.2), preferably (3-5):1:(1-1.1); Preferably, the molar ratio of the compound 3 to the compound 2 is (1-1.2):1, preferably (1-1.1):

1.

7. The preparation method according to claim 4, characterized in that: The temperature of the diazotization reaction is 0 to 50°C, preferably 10 to 40°C; Preferably, the diazotization reaction time is 1 to 4 hours, preferably 1 to 3 hours; Preferably, the coupling reaction temperature is 0 to 25°C, preferably 0 to 10°C; Preferably, the coupling reaction time is 1 to 5 h, preferably 1 to 3 h; Preferably, the pH of the coupling reaction is 1-5, preferably 2-4.

8. The preparation method according to any one of claims 4 to 7, characterized in that: The preparation method of the compound 3 is: uniformly mixing the compound 4 represented by formula IV and the compound 5 represented by formula V, and then adding a base and a catalyst to carry out a condensation reaction to obtain the compound 3; Formula IV: Formula V: CIR4COOR5; Wherein, R2 is a C1-C6 alkyl group or hydrogen; R3 is a C1-C6 alkyl group; R4 is a C1-C6 alkylene group; R5 is a C1-C6 alkyl group; Preferably, the molar ratio of the compound 4 to the compound 5 is 1:(1-5), preferably 1:(2-4).

9. The preparation method according to claim 8, characterized in that: The base comprises at least one of anhydrous sodium carbonate, sodium hydroxide and sodium bicarbonate; Preferably, the molar ratio of the base to the compound 4 is (1-3):2, preferably (1-2):2; Preferably, the catalyst comprises at least one of sodium bromide, potassium iodide and potassium bromide; Preferably, the molar ratio of the catalyst to the compound 4 is 1:(2-6), preferably 1:(3-5); Preferably, the temperature of the condensation reaction is 0 to 200°C, preferably 50 to 150°C; Preferably, the condensation reaction time is 3 to 20 hours, preferably 3 to 15 hours.

10. Use of the low-melting-point red disperse dye according to any one of claims 1 to 3 or the low-melting-point red disperse dye prepared by the preparation method according to any one of claims 4 to 9 in dyeing or printing polyester fiber and its blended fiber products.

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