Synthesis of macromolecular dyes with high monomer conversion rate by grafting polymerization and its application

Abstract

This invention discloses the synthesis and application of a high monomer conversion rate macromolecular dye using grafting polymerization. The invention employs a grafting method to prepare macromolecular dyes that retain intrinsic coloring ability similar to small molecule dyes after macromolecularization. The first step uses Solvent Red 195 and Solvent Orange 107 as monomer raw materials, reacting them with methanol, tetrahydrofuran, and an aqueous sodium hydroxide solution to obtain a hydrolysis product. The hydrolysis product is then acidified to obtain a carboxylic acid product. This carboxylic acid product reacts with thionyl chloride to obtain an acyl chloride product, which then reacts with polyester polyol PS310, polyvinyl alcohol, or polyamide curing agent 651 to obtain a high monomer conversion rate macromolecular dye. This invention prepares a high monomer conversion rate macromolecular dye using grafting polymerization, mitigating the problem of decreased monomer conversion rate after dye molecule macromolecularization.

Description

Technical Field

[0001] This invention belongs to the field of dye preparation technology, specifically relating to the synthesis and application of high monomer conversion rate macromolecular dyes using grafting as a polymerization method. Background Technology

[0002] Traditional small-molecule dyes, due to their small molecular weight and weak binding to substrates, generally suffer from problems such as easy migration, poor weather resistance, low fixation rate, and serious pollution of dyeing and printing wastewater, making it difficult to meet the performance requirements of high-end coatings, inks, and functional textiles. Macromolecular dyes, by covalently fixing chromophores to polymer chains, can fundamentally solve the problems of dye migration and precipitation, significantly improving color fastness and environmental adaptability, and have become the core development direction of the dye industry. Graft polymerization, as the mainstream technical route for preparing macromolecular dyes, introduces active sites into the polymer backbone, allowing dye monomers or modified chromophores to be chemically bonded in the form of side chains, offering advantages such as flexible structural design and adjustable performance. However, existing grafting processes generally suffer from bottlenecks such as low monomer conversion rate, low grafting efficiency, and harsh reaction conditions. The monomer conversion rate in most systems is only maintained in the range of 70% to 85%, and unreacted monomers not only increase post-processing costs and separation difficulties but also cause raw material waste and environmental pollution. Therefore, developing graft polymerization processes with high monomer conversion rates to achieve efficient bonding of dye molecules and simplified product purification is of great practical significance for promoting the industrial application of macromolecular dyes.

[0003] Chinese patent CN109134774B discloses a method for polymerizing the reactive black dye KN-B. Its core innovation lies in designing a tertiary amine-type functional initiator containing the dye chromophore. This initiator utilizes a redox system of the tertiary amine and persulfate to generate active free radicals at room temperature, bidirectionally initiating the polymerization of water-soluble or oil-soluble monomers, allowing the dye molecules to be embedded in the polymer chain in situ. The key advantages of this technology are its fast polymerization rate, high monomer conversion rate, and the absence of organic solvents and emulsifiers in the reaction system, aligning with green chemistry principles. Furthermore, the functionalization and polymerization processes do not interfere with each other, and the dye content in the polymer can be precisely controlled by adjusting the monomer dosage. However, its limitations are also significant: the amount of functional initiator used is as high as 20% to 100% of the monomer mass, far exceeding the amount used by conventional initiators, significantly increasing raw material costs; the initiator synthesis steps are complex and only applicable to vinyl sulfone dyes with specific structures, lacking versatility; simultaneously, the introduction of the tertiary amine structure may negatively affect the color and lightfastness of some dyes, limiting the application range of the product.

[0004] Chinese patent CN202411413829 proposes a method for preparing biomass guar gum macromolecular dyes. First, oxidically modified guar gum is used as a backbone, and then polyacrylamide-acrylic acid-guar gum copolymers are prepared via free radical copolymerization with acrylamide and acrylic acid. Then, amino active sites are introduced through a Hofmann degradation reaction, and finally, the reactive dye is grafted onto the biomass macromolecular backbone. This method uses naturally renewable guar gum as a raw material, resulting in low raw material costs and environmental friendliness. The product exhibits good acid and alkali resistance, heat stability, and fabric hand feel, with a dyeing fixation rate reaching 3-4 levels. However, this process has obvious shortcomings: the overall process is a three-step process, the copolymerization reaction takes 8 hours, and with the addition of degradation and grafting processes, the production cycle is lengthy; the natural molecular weight distribution of guar gum is uneven, resulting in poor batch stability of product structure and performance; the grafting efficiency is highly dependent on the content of skeletal amino groups, and when the molar ratio of dye to amino groups is 1:1, the grafting efficiency is only about 65%, and the monomer conversion rate in the copolymerization stage is about 87.7%, which still has room for improvement and is difficult to meet the requirements of high conversion rate and high efficiency in industrial production.

[0005] Therefore, it is necessary to prepare a dye with high monomer conversion rate, simple production process, and suitable for factory use. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides the synthesis and application of a high monomer conversion rate macromolecular dye using grafting as a polymerization method. It offers a polymeric dye with high monomer conversion rate that is well compatible with polymers such as PET, and the raw materials are readily available. The preparation method is simple and suitable for industrial production.

[0007] To achieve the above objectives, this invention provides the synthesis and application of two high monomer conversion rate macromolecular dyes using grafting as a polymerization method, the structural formulas of which are shown below:

[0008] The preparation method includes the following steps: (1) Dissolve the monomer dye in a mixed solvent, add an alkaline solution, and remove the solvent after the reaction to obtain the hydrolysis product; (2) The hydrolysis product is dissolved and acidified to obtain a carboxylic acid product; (3) After the carboxylic acid product is dissolved, it is mixed with thionyl chloride solution to react and give the acyl chloride product; (4) After dissolving the acyl chloride product in a solvent, add polyester and react at room temperature to obtain a reaction solution; after evaporating the reaction solution to dryness, obtain polyester macromolecular dye.

[0009] The monomer dyes mentioned in step (1) are Solvent Red 195 and Solvent Orange 107; the mixed solvent is methanol and tetrahydrofuran mixed in a volume ratio of 4-8:1.

[0010] The molar ratio of the monomer dye to the alkali in step (1) is 1:1-1.5; the concentration of the alkali solution is 3-5 mol / L; the alkali is selected from sodium hydroxide or potassium hydroxide; the reaction temperature is 40-80 ℃ and the reaction time is 6-12 h.

[0011] The acidification in step (2) is to acidify with hydrochloric acid until the pH value is stable at 5-6; the concentration of the hydrochloric acid is 0.8-1.5 mol / L.

[0012] The molar ratio of the carboxylic acid product to thionyl chloride in step (3) is 1:(1-10).

[0013] In step (4), the solvent is selected from ethyl acetate and dichloromethane; The polyester is selected from any one of polyurethane curing agent 651, polyester polyol PS310, polyvinyl alcohol, and polyamide curing agent 651; the molar ratio of the epoxidation product to the polyester is 1:0.5-1.5.

[0014] As a preferred embodiment, the present invention also provides the synthesis and application of two high monomer conversion rate macromolecular dyes using grafting as a polymerization method, achieved through the following methods:

[0015]

[0016] The preparation method includes the following steps: (1) Dissolve the monomer dye in a mixed solvent, add an aqueous sodium hydroxide solution, and remove the solvent after the reaction to obtain the hydrolyzed sodium acid product; (In preparation method 1, the aqueous sodium hydroxide solution only provides an alkaline environment and converts the original ester base into sodium acid, which can be replaced by other bases such as potassium hydroxide).

[0017] (2) The hydrolysis product is dissolved and acidified by adding hydrochloric acid aqueous solution to obtain carboxylic acid products; (In preparation method 2, hydrochloric acid aqueous solution only provides an acidic environment and converts the original sodium acid into carboxylic acid, which can be replaced by other acids such as acetic acid.) (3) The carboxylic acid product is mixed and dissolved with thionyl chloride solution to react and obtain the acyl chloride product; (in preparation method 3, thionyl chloride is used as both a solvent and a reactant).

[0018] (4) After dissolving the acyl chloride product in dichloromethane, add polyester polyol PS310 and react at room temperature to obtain a reaction solution; after evaporating the reaction solution to dryness, obtain the polyester macromolecular dye. (Dichloromethane in preparation method 4 is a solvent with good solubility after condition screening, and it can be replaced with solvents such as tetrahydrofuran).

[0019] Preferably, the monomer dyes in step (1) are Solvent Red 195 and Solvent Orange 107, and their structural formulas are shown below: .

[0020] Preferably, the mixed solvent is a mixture of methanol and tetrahydrofuran in a volume ratio of 4:1. (The volume ratio in this step is the optimal ratio for yield after condition screening. Other ratios can also yield the product, but will result in prolonged reaction time and decreased yield.) Preferably, the molar ratio of the monomer dye to sodium hydroxide in step (1) is 1:1-1.5; the concentration of the sodium hydroxide aqueous solution is 3-5 mol / L; the reaction temperature is 40-80 ℃; and the reaction time is 6-12 h.

[0021] Preferably, the ratio of the monomeric dye to the mixed solution is 0.5-2 mmol: 7-15 mL.

[0022] Preferably, the solvent used for dissolution in step (2) is pure water, and the acidification is performed by using hydrochloric acid until the pH value is stable at 5-6; after the acidification is completed, the carboxylic acid product is obtained by filtration.

[0023] More preferably, the concentration of the hydrochloric acid is 0.8-1.5 mol / L.

[0024] Preferably, the molar ratio of the carboxylic acid product to thionyl chloride in step (3) is 1:(1-10).

[0025] Preferably, in step (3), the carboxylic acid product is cooled to an environment of 0-5 °C, and then thionyl chloride solution is added dropwise; the temperature is raised to room temperature for reaction, and after the carboxylic acid product has reacted, the solvent is removed and the product is dried to obtain the crude product of acyl chloride (the reaction between carboxylic acid substances and acyl chlorides will release a lot of heat, and the reaction can be carried out at low temperature to effectively reduce the intensity of the reaction). Preferably, the molar ratio of the carboxylic acid product described in step (3) to thionyl chloride in step (4) is 1:(1-10).

[0026] Preferably, the molar ratio of the carboxylic acid product in step (4) to the polyester polyol PS310 is 1:(1-2).

[0027] This invention also provides an application of high monomer conversion rate macromolecular dyes compounded with PET using grafting as a polymerization method. The application method involves mixing the macromolecular dyes with PET, kneading and pressing to obtain composite dye sheets.

[0028] Preferably, the mass ratio of the macromolecular dye to PET is 1:100, the mixing temperature is 260-270 ℃, the mixing time is 4 min after melt mixing; the tableting temperature is 260-270 ℃, the tableting pressure is 10 MPa, and the tableting time is 1 min.

[0029] The beneficial effects of this invention are as follows: By grafting Solvent Red 195 and Solvent Orange 107 molecules into dyes with high molecular weight, they are more compatible with polymers such as PET and can withstand high temperatures of 265 ℃. This facilitates mixing and kneading with polymers such as PET, resulting in dyes suitable for plastic processing and textile printing and dyeing processes, while avoiding the impact of high temperatures on their stability and color uniformity.

[0030] This invention can obtain polymer dyes with high monomer conversion capability in a simple synthesis process, which can effectively reduce the cost of macromolecular dyes. Furthermore, the substances added in each step can be recycled, and the post-processing methods for each step are relatively simple, which greatly saves the cost of synthesis.

[0031] This invention utilizes common industrial dye solvents such as Red 195, Orange 107, sodium hydroxide, and dichloromethane to prepare dyes. These substances are inexpensive and readily available. Furthermore, the preparation steps are simple, which can greatly save costs and is suitable for large-scale factory production. Attached Figure Description

[0032] Figure 1 The infrared spectrum of Solvent Red 195 and its macromolecular dye derivative SR195-PS310 in Example 1 is shown.

[0033] Figure 2 The infrared spectrum of Solvent Red 195 and its macromolecular dye derivative SR195-PVA in Example 2 is shown.

[0034] Figure 3 The infrared spectrum of solvent orange 107 and its macromolecular dye derivative SO107-PS310 in Example 1 is shown.

[0035] Figure 4 The infrared spectrum of Solvent Orange 107 and its macromolecular dye derivative SO107-PVA in Example 2 is shown.

[0036] Figure 5 The standard curve fitting diagram for determining the conversion rate of polymer dye monomers based on ultraviolet-visible absorption spectroscopy in Example 1 is shown: a comparison of the standard curves of the parent dye 195 and the polyester polyol grafted dye SR195-PS310.

[0037] Figure 6The standard curve fitting diagram for determining the conversion rate of polymer dye monomers based on ultraviolet-visible absorption spectroscopy in Example 2 is shown: a comparison of the standard curves of the parent dye 195 and the polyvinyl alcohol grafted dye SR195-PVA.

[0038] Figure 7 The standard curve fitting diagram for determining the conversion rate of polymer dye monomers based on ultraviolet-visible absorption spectroscopy in Example 1 is shown: a comparison of the standard curves of the parent dye 107 and the polyester polyol grafted dye SO107-PS310.

[0039] Figure 8 The standard curve fitting diagram for determining the conversion rate of polymer dye monomers based on ultraviolet-visible absorption spectroscopy in Example 2 is shown: a comparison of the standard curves of the parent dye 107 and the polyvinyl alcohol grafted dye SO107-PVA.

[0040] Figure 9 The polyester blend sheet prepared in Example 7. Detailed Implementation

[0041] The technical solution of the present invention will be further explained and described below with reference to specific embodiments. It is worth noting that the following embodiments are only preferred embodiments of the present invention and should not be construed as limiting the present invention. The scope of protection of the present invention should be determined by the contents of the claims. Modifications and substitutions made by those skilled in the art to the technical solution of the present invention without creative effort all fall within the scope of protection of the present invention.

[0042] Example 1 (1) Hydrolysis reaction: 1 mmol of Solvent Red 195 was added to 10 mL of methanol-tetrahydrofuran mixed solvent (methanol and tetrahydrofuran volume ratio of 4:1), stirred and dissolved, and then 1.1 mmol of sodium hydroxide aqueous solution (concentration of 4 mol / L) was added. The temperature was raised to 80 ℃ and stirred for 6 h. After the reaction was completed, the solvent was removed by rotary evaporation to obtain the hydrolysis product. (2) Acidification reaction: The hydrolysis product is fully dissolved in pure water (the mass ratio of hydrolysis product to pure water is about 1:10). While stirring, 1 mol / L dilute hydrochloric acid aqueous solution is added for acidification. The pH value is adjusted to 5 and no change occurs within 3 min. Then, the product is filtered, washed with pure water, and dried to obtain carboxylic acid products. (3) Weigh 1 g of the carboxylic acid product into a 100 mL reaction flask, add 10 mmol of thionyl chloride and 1 mL of N,N-dimethylformamide under low temperature stirring, and stir until dissolved. Continue stirring at room temperature for 5 h, monitor the reaction by TLC until complete, cool, and remove the solvent by rotary evaporation under reduced pressure to obtain the acyl chloride product.

[0043] (4) Substitution reaction: Weigh 1 g of the acyl chloride product into a 100 mL reaction flask, add 20 mL of dichloromethane solution to dissolve it, and under low temperature stirring conditions, add 1 g of polyester polyol PS310 and 1 mmol of triethylamine sequentially, stirring at room temperature for 12 h. After the reaction is complete as monitored by TLC, remove the solvent by rotary evaporation under reduced pressure, add pure water and filter, and dry the filter cake to obtain polyester macromolecular dyes SR195-PS130 and SO107-PS310. (In this Example 1, polyester polyol PS310 was selected as the research object, but it can be replaced with different types of polyester polyols) The operation method is the same as above, except that the dye is replaced with solvent orange 107 to obtain polyester macromolecular dye SO107-PS310.

[0044] Example 2 The method and steps 1 and 2 are the same as in Example 1, except that the polyester polyol PS310 in step (4) is replaced with polyvinyl alcohol to obtain polyester macromolecular dyes SR195-PVA and SO107-PVA.

[0045] Example 3 The method and steps are the same as in Example 1, except that the polyester polyol PS310 in step (4) is replaced with polyether polyol 330 to obtain polyester macromolecular dyes SR195-330 and SO107-330.

[0046] Example 4 The method and steps are the same as in Example 1, except that the polyester polyol PS310 in step (4) is replaced with polyethylene glycol to obtain polyester macromolecular dyes SR195-PEG and SO107-PEG.

[0047] Comparative Example 1 The methods and steps 1 and 2 are the same as in Example 1.

[0048] (3) Weigh 1 g of carboxylic acid product (the carboxylic acid product varies depending on the dye monomer) into a 100 mL reaction flask. Under stirring at room temperature, add polyester polyol PS310 and 1 mmol triethylamine in a mass ratio of 1:1 to the carboxylic acid product, and stir at room temperature for 12 h. After the reaction is complete as monitored by TLC, remove the solvent by rotary evaporation under reduced pressure, add pure water and filter. Dry the filter cake to obtain polyester macromolecular dyes SR195-PS130-1 and SO107-PS310-1.

[0049] Example 5 The macromolecular dyes obtained in the above examples and comparative examples were detected by infrared spectroscopy and gel permeation chromatography.

[0050] Table 1. Gel permeation chromatography data of macromolecular dye derivatives

[0051] Figures 1 to 4 The infrared spectral characterization results verify the success of the dye macromolecularization grafting reaction. All grafted products fully retain the characteristic absorptions of the dye bulk: the SR195 series in the 2270~2210 cm⁻¹ range. -1 The SO107 series retains the characteristic stretching vibration of the cyano group (C≡N) at 1600 cm⁻¹. -1 The skeletal vibrational peaks of the nearby aromatic rings and conjugated double bonds demonstrate that the core structures of the two types of chromophores were not destroyed during the grafting reaction. The PS310 graft product showed a peak at 1730 cm⁻¹. -1 A strong ester carbonyl absorption peak appears nearby, at 1250–1100 cm⁻¹. -1 The COC ether bond stretching vibration was significantly enhanced, corresponding to the successful introduction of phthalate linker and long-chain polyethylene glycol structure. The PVA graft product also showed a similar effect at 1730 cm⁻¹. -1 The presence of a characteristic peak of ester carbonyl at [location] confirms that the dye is linked to the PVA chain via an ester bond; simultaneously, [peaks are observed] at 3500–3300 cm⁻¹. -1 The absorption peak of hydroxyl groups was significantly enhanced at 1100 cm⁻¹. -1 The broadening and increased intensity of the CO stretching vibration peak in the vicinity match the numerous hydroxyl and ether bonds in the PVA backbone, confirming that the macromolecular chain has been successfully grafted onto the dye molecule.

[0052] Table 1 confirms that all target products successfully achieved macromolecular modification of the dyes. The PVA-grafted series products had the highest number-average molecular weight, with SR195-PVA and SO107-PVA reaching Mn values ​​of 701710 and 635271, respectively. The Mn values ​​of the PS310, PS330, and PEG-grafted series products were concentrated in the range of 18276–27237. The dispersibility index (PDI) of all products was in the range of 1.15–1.83, indicating a narrow overall molecular weight distribution and good controllability of the grafting reaction. SO107-PEG exhibited the lowest PDI (1.15), demonstrating the best product uniformity.

[0053] Example 6 After the macromolecular dye is polymerized, a concentration curve is plotted based on the UV absorbance at different polymer concentrations. The slope of the concentration curve for this macromolecular dye is A. i Given that the slope of the dye monomer concentration curve before polymerization is A0, the monomer conversion rate can be calculated using the following formula:

[0054] The theoretical color development rate is the ratio of the raw material molecules to the total amount of all reactants.

[0055] Table 2. Data on the effective color rendering rate of macromolecular dye derivatives.

[0056] The results, as shown in Tables 1 and 2, indicate that the relative molecular mass of the macromolecular dyes obtained by grafting polymerization is highly correlated with the mass of the main chain of the grafted macromolecular segment, and the morphology is significantly influenced by the main chain. For example, polyester polyol PS310 is a viscous liquid, and the macromolecular dyes grafted onto it are mostly in an elastomer state, unable to become block or powder solids. The grafting method used in Examples 1-4 is simple, requiring no temperature change during polymerization, and the final monomer conversion rate test shows that the actual conversion rate of the dye after the grafting reaction is not significantly different from the theoretical conversion rate. This results in lower costs for subsequent processing and use compared to the dyes obtained in the comparative examples, making them suitable for subsequent industrial production.

[0057] Example 7 Take 1 part by weight of the polysiloxane dye prepared in the above examples and comparative examples, and mix it with 100 parts by weight of polyethylene terephthalate. Melt it at 265 °C and then knead it for 4 min. After kneading, take it out and place it in a tablet press. Preheat it at 265 °C for 4 min, then hot press it at 10 MPa for 1 min, and then cold press it at room temperature for 1 min to obtain polyester mixed sheets.

Claims

1. A high monomer conversion rate macromolecular dye polymerized by grafting, characterized in that: Its structural formula is shown below: 。 2. The method for preparing high monomer conversion rate macromolecular dyes using grafting polymerization as described in claim 1, characterized in that: This can be achieved using the following method: The preparation method includes the following steps: (1) Dissolve the monomer dye in a mixed solvent, add an alkaline solution, and remove the solvent after the reaction to obtain the hydrolysis product; (2) The hydrolysis product is dissolved and acidified to obtain a carboxylic acid product; (3) After the carboxylic acid product is dissolved, it is mixed with thionyl chloride solution to react and give the acyl chloride product; (4) After dissolving the acyl chloride product in a solvent, add polyester and react at room temperature to obtain a reaction solution; after evaporating the reaction solution to dryness, obtain polyester macromolecular dye.

3. The preparation method according to claim 2, characterized in that: The monomer dyes mentioned in step (1) are Solvent Red 195 and Solvent Orange 107; the mixed solvent is methanol and tetrahydrofuran mixed in a volume ratio of 4-8:

1.

4. The preparation method according to claim 2, characterized in that: The molar ratio of the monomer dye to the alkali in step (1) is 1:1-1.5; the concentration of the alkali solution is 3-5 mol / L; the alkali is selected from sodium hydroxide or potassium hydroxide; the reaction temperature is 40-80 ℃ and the reaction time is 6-12 h.

5. The preparation method according to claim 2, characterized in that: The acidification in step (2) is to acidify with hydrochloric acid until the pH value is stable at 5-6; the concentration of the hydrochloric acid is 0.8-1.5 mol / L.

6. The preparation method according to claim 2, characterized in that: The molar ratio of the carboxylic acid product to thionyl chloride in step (3) is 1:(1-10).

7. The preparation method according to claim 2, characterized in that: The solvent mentioned in step (4) is selected from ethyl acetate and dichloromethane.

8. The preparation method according to claim 2, characterized in that: The polyester mentioned in step (4) is selected from any one of polyurethane curing agent 651, polyester polyol PS310, polyvinyl alcohol, and polyamide curing agent 651; the molar ratio of the epoxidation product to the polyester is 1:0.5-1.

5.

9. The application of a macromolecular dye prepared by the method according to any one of claims 1-8 as a dyeing material.

10. The application of a high-dyeing-capacity macromolecular dye compounded with PET using grafting as a polymerization method as a composite dye sheet.

Images