WO2024164579A1 - Acid-dyeable copolyester and preparation method therefor - Google Patents

Abstract

The present invention relates to an acid-dyeable copolyester and a preparation method therefor. The preparation method comprises: using a one-pot method to prepare a mixture of BHET and quaternized BHET, then performing a polycondensation reaction to prepare an acid-dyeable copolyester; The process for preparing the mixture of BHET and quaternized BHET comprises: first using protonic acid and Lewis acid to perform synergistic catalysis, and using paraformaldehyde to perform monochloromethylation on BHET to obtain a mixture of BHET and monochloromethylated BHET, and then performing quaternization modification on the mixture to obtain a mixture of BHET and quaternized BHET; the product is a random copolymer, and the molecular chain is composed of an M₁ repeating unit and an M₂ repeating unit. The preparation method of the present invention is simple, the product of the present invention can be dyed by acid dyes at normal temperature and normal pressure, has high dye uptake, high color fastness and good thermal stability, and can undergo mixed dyeing with natural fibers such as cotton, wool, and silk.

Description

A kind of acid dyeable copolyester and preparation method thereof Technical Field

The invention belongs to the technical field of polyester functional modification and synthesis, and relates to an acid dyeable copolyester and a preparation method thereof.

Background Art

Polyester is the most widely used and important type of chemical fiber product in the modern textile industry. It has excellent mechanical properties, physical properties, thermal properties and excellent dimensional and structural stability. It is widely used in clothing, home textiles, agriculture and industry. However, since it is a hydrophobic synthetic fiber, it lacks functional groups that can bind to dyes, making it difficult to dye. Usually, it can only be dyed with disperse dyes, and must be dyed under high temperature and high pressure or with the help of a carrier. The cost is high, the dye is highly toxic, the waste liquid treatment is complicated, and it also pollutes the environment. Therefore, polyester needs to be dyed and modified. At present, the main dyeing modified polyesters are cationic dye-dyable polyester modified (CDP) (including high temperature and high pressure type and normal pressure boiling dyeing type) and acid anion dye-dyable polyester modified (ADP). Among them, CDP has been industrialized, but CDP usually needs to be dyed under high temperature conditions of 120-135°C. For the dyeing of wool/polyester blended fabrics, stripe dyeing is usually required separately. The dyeing process is complicated and energy consumption is high, and high temperature and high pressure conditions will cause fiber strength loss. Acid dyes can dye polyester fibers and can be dyed in the same bath as wool, silk, etc., which can simplify the dyeing process. Acid anionic dyes are inexpensive, have a complete color spectrum, and bright colors. They have good application prospects. Once industrialized, they will greatly improve economic and social benefits, which is especially important for the dyeing of polyester-wool blended fabrics.

Patent CN106008942A proposes an imidazole-based anion dye-dyeable modified copolyester masterbatch and its preparation, using N-2-(3,5-dicarboxyphenyl)ethyl-N'-methylimidazolium chloride as the third comonomer, carrying out polycondensation reaction, and using copolymerization to connect the imidazole group to the polyester molecular chain. The positively charged nitrogen ions in the imidazole group serve as dyeing seats on the polyester molecular chain, and combine with the sulfonate ions in the acid anion dye to achieve acid anion dyeability. The polyester fiber obtained by this method has a breaking strength of 3.32cN/dtex and a breaking elongation of 24%. At normal pressure and 90°C, the dyeing rate of the acid dye methyl blue can reach 93%. Although the copolymerization and grafting of nitrogen-containing third monomers (N-2-(3,5-dicarboxyphenyl)ethyl-N'-methylimidazolium chloride) onto polyester macromolecular segments provides dyeing sites that can react with acid dyes, this type of copolymer has the problem of poor thermal stability, resulting in poor color fastness of the dyed fibers, thus restricting the industrial development of this third monomer copolymerization modification method.

Patent CN1433446A proposes to prepare an acid-dyeable polyester blend by melt blending polyester, secondary amine or secondary amine salt and a variety of additives (additives are used to improve compatibility). The method is used to spin and weave socks samples. The dyeing rate can reach up to 85.4% in a Lanaset acid dyeing bath at 100°C for 90 minutes. Patent CN1291081C combines polyamide and polyethylene-methacrylate into a polyester acid-dyeable composite additive, adds it to a polyester compound, and obtains acid-dyeable polyester fibers through blending and spinning. The carboxyl groups in polyethylene-methacrylate can undergo esterification reactions with the end groups of polyester and polyamide, respectively, to improve the compatibility of esters and amides. The polyester fiber obtained by this method is boil-dyed at 100°C in a CI acid yellow acid dyeing bath. 60min, the dyeing rate can reach 83%. However, in order to prepare acid-dyeable polyester blends by adding polyamide, it is necessary to improve the compatibility between polyester and polyamide by adding compatibilizers, additives, etc., which increases the blending cost on the one hand, and on the other hand, the microstructure of the blended polyester still presents two phases. During spinning, polyamide microfilaments will be formed, resulting in a decrease in the mechanical properties of the fiber, making it difficult to meet the requirements of industrial spinning speed.

Summary of the invention

The purpose of the present invention is to solve the problems existing in the prior art and provide an acid dyeable copolyester and a preparation method thereof.

To achieve the above object, the technical solution adopted by the present invention is as follows:

A method for preparing an acid dyeable copolyester, comprising preparing a mixture of BHET and quaternized BHET by a one-pot method, carrying out a polycondensation reaction, and obtaining the acid dyeable copolyester by discharging, cooling, pelletizing and drying.

The preparation process of the mixture of BHET and quaternized BHET is as follows: firstly, using protonic acid and Lewis acid to synergistically catalyze, using paraformaldehyde to monochloromethylate BHET to obtain a mixture of BHET and monochloromethylate BHET, and then quaternizing the mixture to obtain a mixture of BHET and quaternized BHET;

The molar ratio of BHET, paraformaldehyde and Lewis acid is 1:0.65-1:1.3-1.5, and the mass ratio of BHET to protonic acid is 1:0.65-0.85; monochloromethylation means that only one position on the aromatic ring of BHET is chloromethylated; the temperature of the monochloromethylation reaction is 50-70°C, and the time is 5-8h;

The temperature of the polycondensation reaction is 250-280°C, the absolute pressure is 30-100 Pa, and the time is 2-4 hours.

The quaternized BHET prepared by the present invention contains a long-chain side group. When BHET and the quaternized BHET are subjected to a polycondensation reaction, the molecular weight of the product (acidic dyeable copolyester) is difficult to reach the level of ordinary PET due to the steric hindrance effect. The present invention solves this problem by reasonably regulating the temperature, absolute pressure and time of the polycondensation reaction, and obtains an acidic dyeable copolyester with a molecular weight close to that of ordinary PET.

The reaction equation of the present invention is as follows.

As the preferred technical solution:

In the method for preparing the above-mentioned acid dyeable copolyester, the steps for preparing the mixture of BHET and quaternized BHET are as follows:

(a) Monochloromethylation reaction;

After paraformaldehyde, Lewis acid, protonic acid and BHET are mixed, they are heated and stirred for monochloromethylation reaction to obtain a mixture of BHET and monochloromethylated BHET; the specific process is: paraformaldehyde, Lewis acid, protonic acid and BHET are added into a reaction kettle, heated and stirred, and after the reaction is completed, a partial monochloromethylation product is obtained;

(b) quaternization reaction;

The mixture of all BHET and monochloromethylated BHET obtained in step (a) is uniformly mixed with an ethylene glycol solution of trimethylamine, the pH value is adjusted to 8-9.5 with an alkali solution, and the mixture is heated and stirred to carry out a quaternization reaction. After the reaction is completed, a mixture of BHET and quaternized BHET is obtained.

The method for preparing an acid dyeable copolyester as described above, wherein in step (a), the degree of polymerization of the paraformaldehyde is 5 to 15; the protonic acid is concentrated hydrochloric acid with a concentration of 36 to 38 wt%, or is a mixture of concentrated sulfuric acid with a concentration of 60 to 70 wt% and concentrated hydrochloric acid with a concentration of 36 to 38 wt%, and the mass of the concentrated sulfuric acid is less than 20 wt% of the mass of the concentrated hydrochloric acid; the Lewis acid is tin chloride or ammonium chloride; and the yield of the monochloromethylation reaction is 30 to 50%;

In step (b), the concentration of trimethylamine in the ethylene glycol solution of trimethylamine is 40-45wt%; the temperature of the quaternization reaction is 50-80°C, and the time is 2-4h; the molar ratio of the raw material BHET in step (a) to the raw material trimethylamine in step (b) is 1:0.85-1.0.

The present invention also provides an acid dyeable copolyester prepared by the method for preparing an acid dyeable copolyester as described in any one of the above items, which is a random copolymer, and the molecular chain is composed of _M1 repeating units and _M2 repeating units, and the structural formula of the _M1 repeating unit is The structural formula of the _M2 repeating unit is

As the preferred technical solution:

The acid dyeable copolyester as described above has a glass transition temperature of 73-75°C, a melting point of 240-245°C, a crystallinity of 35-40%, an intrinsic viscosity of 0.52-0.58 dL/g, and a number average molecular weight of 15,000-16,000 g/mol.

The acid dyeable copolyester as described above has an acid dye uptake rate of ≥96% when the acid dyeable copolyester slice is dyed at room temperature and pressure (80-85° C., 0.1 MPa); the acid dyeable copolyester is spun, wound and stretched to obtain the acid dyeable copolyester fiber, the spinning speed is 3500-6000 m/min (it can be seen that the acid dyeable copolyester of the present invention can meet the requirements of industrial spinning speed), the breaking strength of the acid dyeable copolyester fiber is ≥4 cN/dtex, and when dyed at room temperature and pressure, the acid dye uptake rate is ≥94%, the color fastness to washing is ≥4 level, the color fastness to rubbing is ≥4 level, and the strength loss after dyeing is 4-6%.

The principle of the present invention is as follows:

The chloromethylated quaternary ammonium modified BHET contains a stable quaternary ammonium salt structure, which does not react during the polycondensation process, and the molecular structure of the benzene ring in the synthesized polyester molecular chain is completely retained. When dyeing with acid dyes, the quaternary ammonium group acts as an alkaline dyeing seat, and the positively charged nitrogen ions are very easy to combine with the anionic groups (sulfonic acid group, carboxylic acid group) in the dye by ionic bonds. At the same time, the alkyl groups on the side chains of the oligomers can combine with the dye molecules through intermolecular forces and van der Waals forces, making the dye The molecules can be firmly adsorbed on the polyester molecules. Therefore, dyeing can also be carried out at room temperature and pressure, showing good dyeing performance. The method has a simple synthesis process, a high reaction yield, good spinnability of polyester chips, simple conditions for obtaining polyester fiber dyeing, and a high dyeing rate and uniformly dyed product can be obtained at room temperature and pressure. It is suitable for industrial production and can be used to make a variety of polyester products, such as worsted fabrics, decorative fabrics, spunbond fabrics, films, etc.

Beneficial Effects

(1) The one-pot process adopted in the present invention is simple to operate, has low energy consumption, is suitable for industrial production, and the introduction of quaternary ammonium groups on part of BHET has little effect on the polycondensation reaction activity of BHET and the chemical stability and physical and mechanical properties of the copolyester finally obtained;

(2) The acid dyeable copolyester of the present invention can be dyed with acid dyes at room temperature and pressure, has a high dye uptake rate, and has good color fastness. The acid dyeable copolyester fiber spun has good mechanical properties, and the fiber strength loss after dyeing is small.

DETAILED DESCRIPTION

The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

The test method for the yield of the monochloromethylation reaction in the following embodiments is as follows: After the chloromethylation reaction is completed, the reaction is cooled, separated in a separatory funnel, the organic layer is washed 3 to 4 times with a 10 wt% sodium carbonate aqueous solution and distilled water, respectively, then dried with anhydrous sodium sulfate, filtered, and finally distilled under reduced pressure to obtain a monochloromethylation product, and the yield is calculated by weighing;

Wherein, _m1 is the weight of monochloromethylation product, g, _M1 is its relative molecular mass, g/mol; _m0 is the weight of BHET input, g, and _M0 is its relative molecular mass, g/mol.

The method for dyeing the acid dyeable copolyesters prepared in the following embodiments at normal temperature and pressure is as follows:

Slice dyeing: add 1 g of acid dyeable copolyester slices into a dyeing reaction tube, put it into a dye vat, and dye it with a dye preparation solution at 90°C under normal pressure (0.1 MPa) for 30 minutes; wherein, the bath ratio of the acid dyeable copolyester slices to the dye preparation solution is 1:40, the pH value of the dye preparation solution adjusted with acetic acid is 4, the dye preparation solution consists of an acid dye and water, and the acid dye (acid lake blue A, acid brilliant green 3GM, Pula red B, acid methyl blue, etc.) is 2.0 owf% of the mass of the acid dyeable copolyester slices.

Fiber dyeing: Weigh 5g of fiber and wet it with distilled water, then squeeze out the water, add distilled water in a water bath according to a bath ratio of 1:40, add 2.0owf% of the fiber mass of acid dye (acid lake blue A, acid brilliant green 3GM, Pula red B, Acid methyl blue, etc.), and adjust the pH value to 4 with acetic acid. Then, at room temperature, put the fiber into distilled water, keep the temperature constant for 10 minutes, then increase the temperature to 80°C at a rate of 2°C/min, and dye for 30 minutes under normal pressure (0.1MPa). After dyeing, wash and dry.

The detection methods of the relevant properties of the acid dyeable copolyesters in the following examples are as follows:

Detection method of glass transition temperature: dry the acid dyeable copolyester slices thoroughly, weigh 5 mg of the sample, and complete DSC sample preparation, heat the sample on a hot plate, heat and melt at 270°C for 4 minutes, and immediately quench in liquid nitrogen after the end; then use a differential scanning calorimeter to test the thermal properties, and the test conditions are set as follows: heat from room temperature to 280°C at a rate of 10°C/min, hold for 1 minute, and then cool to room temperature after the end.

Intrinsic viscosity test method: refer to standard GB/T 14190-2008 "Test method for fiber-grade polyester chips (PET)" to test intrinsic viscosity ([η], dL/g); dissolve the fully dried sample in a mixed solvent of phenol and 1,1,2,2-tetrachloroethane (50/50, wt/wt) to form a solution with a concentration of 0.50 g/dL; in a constant temperature water bath at 25°C, use an Ubbelohde viscometer with a capillary diameter of 0.88 mm to measure the intrinsic viscosity of the solution. The intrinsic viscosity calculation formula is as follows:

Where: [η] is the intrinsic viscosity, η _sp is the specific viscosity; t ₁ is the solution outflow time (s); t ₀ is the solvent outflow time (s); c is the solution concentration (g/dL).

Acid dye uptake detection method: After dyeing is completed according to the above dyeing method, accurately take 2mL of residual liquid from the dye solution, transfer it to a 50mL volumetric flask and dilute it to the scale with ultrapure water; at the same time, in order to avoid the absorbance change caused by other factors affecting the dye solution itself, set up a group of blank dye solutions for non-dyeing and perform the same treatment to eliminate interference. Test the absorbance _Fx at the maximum absorption wavelength λ _max = 457nm of the ultraviolet spectrophotometer, and calculate the dye uptake (%) according to the following formula:
Dyeing rate (%) = (F ₀ -F _x +F _space ) ÷ F ₀ × 100%;

Where: _Fx is the absorbance of the residual dye solution; _F0 is the absorbance of the standard dye solution (i.e., the dye solution before the fiber or slice is dyed in the above dyeing process); _Fblank is the absorbance of the blank dye solution.

Testing method for color fastness to washing: The fiber is made into a plain fabric with a warp density of 20/10cm and a weft density of 6.3/10cm. Referring to the standard GB/T 12490-2014 "Textiles - Tests for color fastness - Color fastness to household and commercial washing", the SW-12 color fastness to washing tester of Wenzhou Darong Textile Instrument Co., Ltd. is used, equipped with standard washing steel balls (diameter 6±0.5mm), and washed with pure water at a washing temperature of 40°C.

Test method for color fastness to rubbing: refer to "Textiles - Tests for Color Fastness - Color Fastness to Rubbing" (GB/T 3920-2008) for determination.

The test method of fiber breaking strength is as follows: refer to the "Test Method for Tensile Properties of Chemical Fiber Filaments" (GB/T 14344-2008); the mechanical properties of fiber multifilaments are tested using a 3356 Instron strength meter; the test conditions are: temperature (20±5)℃, relative humidity (65±5)%, clamping distance of 500mm, and tensile rate of 500mm/min; each group of samples is tested 5 times in the experiment, and the average value is taken to calculate the breaking strength.

Detection method for strength loss of fiber after dyeing: Before and after fiber multifilament dyeing, the breaking strength of the fiber is measured with reference to the "Test Method for Tensile Properties of Chemical Filament Filaments" (GB/T 14344-2008); the strength meter used is the 3356 Instron strength meter; the test conditions are: temperature (20±5)℃, relative humidity (65±5)%, clamping distance of 500mm, and tensile rate of 500mm/min; each group of samples is tested 5 times in the experiment, and the average value is taken as the breaking strength of the sample to calculate the breaking strength loss.

The acid dyeable copolyesters prepared in the following examples have a molecular chain consisting of _M1 repeating units and _M2 repeating units, and the structural formula of the _M1 repeating unit is The structural formula of the _M2 repeating unit is

Example 1

A method for preparing an acid dyeable copolyester, the specific steps are as follows:

(1) Prepare raw materials:

Paraformaldehyde: degree of polymerization is 5;

Lewis acid: tin chloride;

Protonic acid: a mixture of 60wt% concentrated sulfuric acid and 36wt% concentrated hydrochloric acid, wherein the mass of the concentrated sulfuric acid is 10wt% of the mass of the concentrated hydrochloric acid;

BHET: manufacturer Aladdin, brand number B419409;

Trimethylamine;

Ethylene glycol;

(2) Preparation of a mixture of BHET and quaternized BHET by a one-pot process:

(a) adding paraformaldehyde, Lewis acid, protonic acid and BHET into a reaction kettle, and continuously stirring at 50° C. to carry out a monochloromethylation reaction for 8 hours; after the reaction, a mixture of BHET and monochloromethylated BHET is obtained, wherein the molar ratio of BHET, paraformaldehyde and Lewis acid is 1:0.65:1.3, the mass ratio of BHET to protonic acid is 1:0.65, and the monochloromethylation reaction is The receivable rate is 30%;

(b) uniformly mixing the mixture of all BHET and monochloromethylated BHET obtained in step (a) with an ethylene glycol solution of trimethylamine, adjusting the pH value to 8 with an alkali solution, and carrying out a quaternization reaction at 50° C. with constant stirring for 2 hours; after the reaction is completed, a mixture of BHET and quaternized BHET is obtained, wherein the concentration of trimethylamine in the ethylene glycol solution of trimethylamine is 40wt%, and the molar ratio of the raw material BHET in step (a) to the raw material trimethylamine in step (b) is 1:0.85;

(3) Preparation of acidic dyeable copolyesters:

The mixture of BHET and quaternized BHET obtained in step (2) is subjected to polycondensation reaction at a temperature of 250° C. and an absolute pressure of 30 Pa for 2 hours, and then discharged, cooled, pelletized and dried to obtain an acidic dyeable copolyester.

The final acid dyeable copolyester has a number average molecular weight of 15000 g/mol, a glass transition temperature of 73°C, a melting point of 240°C, a crystallinity of 35%, and an intrinsic viscosity of 0.52 dL/g;

When the acid dyeable copolyester chips are dyed at room temperature and pressure, the dyeing rate of the acid dye (acid lake blue A) is 96%;

The fiber made from acid dyeable copolyester (fineness 459.7D/192f) has a breaking strength of 4cN/dtex. When dyed at room temperature and pressure, the acid dye (acid lake blue A) dyeing rate is 94%, the color fastness to washing is level 4, the color fastness to rubbing is level 4, and the strength loss after dyeing is 6%.

Example 2

A method for preparing an acid dyeable copolyester, the specific steps are as follows:

(1) Prepare raw materials:

Paraformaldehyde: degree of polymerization is 5;

Lewis acid: tin chloride;

Protonic acid: a mixture of 65wt% concentrated sulfuric acid and 37wt% concentrated hydrochloric acid, wherein the mass of the concentrated sulfuric acid is 15wt% of the mass of the concentrated hydrochloric acid;

BHET: manufacturer Aladdin, brand number B419409;

Trimethylamine;

Ethylene glycol;

(2) Preparation of a mixture of BHET and quaternized BHET by a one-pot process:

(a) adding paraformaldehyde, Lewis acid, protonic acid and BHET into a reaction kettle, and performing a monochloromethylation reaction at 58° C. with continuous stirring for 8 hours; after the reaction, a mixture of BHET and monochloromethylated BHET is obtained, wherein the molar ratio of BHET, paraformaldehyde and Lewis acid is 1:0.65:1.4, the mass ratio of BHET to protonic acid is 1:0.75, and the yield of the monochloromethylation reaction is 35%;

(b) uniformly mixing the mixture of all BHET and monochloromethylated BHET obtained in step (a) with an ethylene glycol solution of trimethylamine, adjusting the pH value to 9 with an alkali solution, and carrying out a quaternization reaction at 65° C. with constant stirring for 3.5 h; When the process is finished, a mixture of BHET and quaternized BHET is obtained, wherein the concentration of trimethylamine in the ethylene glycol solution of trimethylamine is 43 wt %, and the molar ratio of the raw material BHET in step (a) to the raw material trimethylamine in step (b) is 1:0.95;

(3) Preparation of acidic dyeable copolyesters:

The mixture of BHET and quaternized BHET obtained in step (2) was subjected to polycondensation reaction at a temperature of 265° C. and an absolute pressure of 45 Pa for 3.5 hours, and then discharged, cooled, pelletized and dried to obtain an acidic dyeable copolyester.

The number average molecular weight of the finally obtained acid dyeable copolyester is 15500 g/mol, the glass transition temperature is 73.8°C, the melting point is 242.1°C, the crystallinity is 36.1%, and the intrinsic viscosity is 0.54 dL/g;

When the acid dyeable copolyester chips are dyed at room temperature and pressure, the dyeing rate of the acid dye (acid lake blue A) is 96.4%;

The fiber made from acid dyeable copolyester (fineness 456.4D/192f) has a breaking strength of 4.2 cN/dtex. When dyed at room temperature and pressure, the dyeing rate of acid dye (acid lake blue A) is 94.5%, the color fastness to washing is level 4, the color fastness to rubbing is level 4, and the strength loss after dyeing is 5.5%.

Example 3

A method for preparing an acid dyeable copolyester, the specific steps are as follows:

(1) Prepare raw materials:

Paraformaldehyde: degree of polymerization is 10;

Lewis acid: tin chloride;

Protonic acid: a mixture of 70wt% concentrated sulfuric acid and 38wt% concentrated hydrochloric acid, wherein the mass of the concentrated sulfuric acid is 20wt% of the mass of the concentrated hydrochloric acid;

BHET: manufacturer Aladdin, brand number B419409;

Trimethylamine;

Ethylene glycol;

(2) Preparation of a mixture of BHET and quaternized BHET by a one-pot process:

(a) adding paraformaldehyde, Lewis acid, protonic acid and BHET into a reaction kettle, and performing a monochloromethylation reaction at 70° C. with continuous stirring for 5 hours; after the reaction, a mixture of BHET and monochloromethylated BHET is obtained, wherein the molar ratio of BHET, paraformaldehyde and Lewis acid is 1:0.75:1.42, the mass ratio of BHET to protonic acid is 1:0.82, and the yield of the monochloromethylation reaction is 45%;

(b) uniformly mixing the mixture of all BHET and monochloromethylated BHET obtained in step (a) with an ethylene glycol solution of trimethylamine, adjusting the pH value to 9.2 with an alkali solution, and carrying out a quaternization reaction at 75° C. with constant stirring for 3 hours; after the reaction is completed, a mixture of BHET and quaternized BHET is obtained, wherein the concentration of trimethylamine in the ethylene glycol solution of trimethylamine is 43wt%, and the molar ratio of the raw material BHET in step (a) to the raw material trimethylamine in step (b) is 1:0.98;

(3) Preparation of acidic dyeable copolyesters:

The mixture of BHET and quaternized BHET obtained in step (2) is subjected to polycondensation reaction at a temperature of 250° C. and an absolute pressure of 45 Pa for 4 hours, and then discharged, cooled, pelletized and dried to obtain an acidic dyeable copolyester.

The final acid dyeable copolyester has a number average molecular weight of 15300 g/mol, a glass transition temperature of 73.5°C, a melting point of 241.7°C, a crystallinity of 36%, and an intrinsic viscosity of 0.53 dL/g;

When the acid dyeable copolyester chips are dyed at room temperature and pressure, the dyeing rate of the acid dye (acid brilliant green 3GM) is 97.2%;

The fiber made from acid dyeable copolyester (fineness 457.3D/192f) has a breaking strength of 4.15 cN/dtex. When dyed at room temperature and pressure, the dyeing rate of acid dye (acid brilliant green 3GM) is 95.0%, the color fastness to washing is level 4-5, the color fastness to rubbing is level 4-5, and the strength loss after dyeing is 5.87%.

Example 4

A method for preparing an acid dyeable copolyester, the specific steps are as follows:

(1) Prepare raw materials:

Paraformaldehyde: degree of polymerization is 10;

Lewis acid: ammonium chloride;

Protonic acid: concentrated hydrochloric acid with a concentration of 36wt%;

BHET: manufacturer Aladdin, brand number B419409;

Trimethylamine;

Ethylene glycol;

(2) Preparation of a mixture of BHET and quaternized BHET by a one-pot process:

(a) adding paraformaldehyde, Lewis acid, protonic acid and BHET into a reaction kettle, and performing a monochloromethylation reaction at 50° C. with continuous stirring for 8 hours; after the reaction, a mixture of BHET and monochloromethylated BHET is obtained, wherein the molar ratio of BHET, paraformaldehyde and Lewis acid is 1:0.8:1.48, the mass ratio of BHET to protonic acid is 1:0.85, and the yield of the monochloromethylation reaction is 40%;

(b) uniformly mixing the mixture of all BHET and monochloromethylated BHET obtained in step (a) with an ethylene glycol solution of trimethylamine, adjusting the pH value to 8 with an alkali solution, and carrying out a quaternization reaction at 60° C. with constant stirring for 3.5 hours; after the reaction is completed, a mixture of BHET and quaternized BHET is obtained, wherein the concentration of trimethylamine in the ethylene glycol solution of trimethylamine is 40wt%, and the molar ratio of the raw material BHET of step (a) to the raw material trimethylamine of step (b) is 1:0.85;

(3) Preparation of acidic dyeable copolyesters:

The mixture of BHET and quaternized BHET obtained in step (2) is subjected to polycondensation reaction at a temperature of 270° C. and an absolute pressure of 50 Pa for 2.5 hours, and then discharged, cooled, pelletized and dried to obtain an acidic dyeable copolyester.

The number average molecular weight of the finally obtained acid dyeable copolyester is 15200 g/mol, the glass transition temperature is 73.2°C, the melting point is 241.3°C, the crystallinity is 35.5%, and the intrinsic viscosity is 0.525 dL/g;

When the acid dyeable copolyester chips are dyed at room temperature and pressure, the dyeing rate of the acid dye (acid brilliant green 3GM) is 97%;

The fiber made from acid dyeable copolyester (fineness 458.3D/192f) has a breaking strength of 4.1 cN/dtex. When dyed at room temperature and pressure, the dyeing rate of acid dye (acid brilliant green 3GM) is 94.8%, the color fastness to washing is level 4, the color fastness to rubbing is level 4, and the strength loss after dyeing is 5.3%.

Example 5

A method for preparing an acid dyeable copolyester, the specific steps are as follows:

(1) Prepare raw materials:

Paraformaldehyde: degree of polymerization is 15;

Lewis acid: ammonium chloride;

Protonic acid: concentrated hydrochloric acid with a concentration of 37wt%;

BHET: manufacturer Aladdin, brand number B419409;

Trimethylamine;

Ethylene glycol;

(2) Preparation of a mixture of BHET and quaternized BHET by a one-pot process:

(a) adding paraformaldehyde, Lewis acid, protonic acid and BHET into a reaction kettle, and performing a monochloromethylation reaction at 68° C. with continuous stirring for 7 hours; after the reaction, a mixture of BHET and monochloromethylated BHET is obtained, wherein the molar ratio of BHET, paraformaldehyde and Lewis acid is 1:0.68:1.4, the mass ratio of BHET to protonic acid is 1:0.68, and the yield of the monochloromethylation reaction is 47%;

(b) uniformly mixing the mixture of all BHET and monochloromethylated BHET obtained in step (a) with an ethylene glycol solution of trimethylamine, adjusting the pH value to 9.5 with an alkali solution, and carrying out a quaternization reaction at 80° C. with constant stirring for 2.5 hours; after the reaction is completed, a mixture of BHET and quaternized BHET is obtained, wherein the concentration of trimethylamine in the ethylene glycol solution of trimethylamine is 43.5wt%, and the molar ratio of the raw material BHET of step (a) to the raw material trimethylamine of step (b) is 1:0.88;

(3) Preparation of acidic dyeable copolyesters:

The mixture of BHET and quaternized BHET obtained in step (2) is subjected to polycondensation reaction at a temperature of 275° C. and an absolute pressure of 40 Pa for 3.5 hours, and then discharged, cooled, pelletized and dried to obtain an acidic dyeable copolyester.

The final acid dyeable copolyester has a number average molecular weight of 15700 g/mol, a glass transition temperature of 74°C, a melting point of 243°C, a crystallinity of 37%, and an intrinsic viscosity of 0.56 dL/g;

When the acid dyeable copolyester chips are dyed at room temperature and pressure, the dyeing rate of acid dye (Pura Red B) is 97.5%;

The fiber made from acid dyeable copolyester (fineness 456.3D/192f) has a breaking strength of 4.2 cN/dtex. When dyed at room temperature and pressure, the dyeing rate of acid dye (Pra Red B) is 95.4%, the color fastness to washing is level 4-5, the color fastness to rubbing is level 4-5, and the strength loss after dyeing is 5.7%.

Example 6

A method for preparing an acid dyeable copolyester, the specific steps are as follows:

(1) Prepare raw materials:

Paraformaldehyde: degree of polymerization is 15;

Lewis acid: ammonium chloride;

Protonic acid: concentrated hydrochloric acid with a concentration of 38wt%;

BHET: manufacturer Aladdin, brand number B419409;

Trimethylamine;

Ethylene glycol;

(2) Preparation of a mixture of BHET and quaternized BHET by a one-pot process:

(a) adding paraformaldehyde, Lewis acid, protonic acid and BHET into a reaction kettle, and performing a monochloromethylation reaction at 70° C. with continuous stirring for 6 hours; after the reaction, a mixture of BHET and monochloromethylated BHET is obtained, wherein the molar ratio of BHET, paraformaldehyde and Lewis acid is 1:1:1.5, the mass ratio of BHET to protonic acid is 1:0.85, and the yield of the monochloromethylation reaction is 50%;

(b) uniformly mixing the mixture of all BHET and monochloromethylated BHET obtained in step (a) with an ethylene glycol solution of trimethylamine, adjusting the pH value to 8.5 with an alkali solution, and carrying out a quaternization reaction at 80° C. with constant stirring for 4 hours; after the reaction is completed, a mixture of BHET and quaternized BHET is obtained, wherein the concentration of trimethylamine in the ethylene glycol solution of trimethylamine is 45wt%, and the molar ratio of the raw material BHET in step (a) to the raw material trimethylamine in step (b) is 1:1.0;

(3) Preparation of acidic dyeable copolyesters:

The mixture of BHET and quaternized BHET obtained in step (2) is subjected to polycondensation reaction at a temperature of 280° C. and an absolute pressure of 30 Pa for 3 hours, and then discharged, cooled, pelletized and dried to obtain an acidic dyeable copolyester.

The final acid dyeable copolyester has a number average molecular weight of 16000 g/mol, a glass transition temperature of 75°C, a melting point of 245°C, a crystallinity of 40%, and an intrinsic viscosity of 0.58 dL/g;

When the acid dyeable copolyester chips were dyed at room temperature and pressure, the dyeing rate of acid dye (Pra Red B) was 97.8%;

The fiber made from acid dyeable copolyester (fineness 440D/192f) has a breaking strength of 6.5 cN/dtex. When dyed at room temperature and pressure, the dyeing rate of acid dye (Pra Red B) is 95.8%, the color fastness to washing is level 4-5, the color fastness to rubbing is level 4-5, and the strength loss after dyeing is 4%.

Claims (6)

A method for preparing an acidic dyeable copolyester, characterized in that a mixture of BHET and quaternized BHET is prepared by a one-pot method, and then a polycondensation reaction is carried out to obtain the acidic dyeable copolyester; The preparation process of the mixture of BHET and quaternized BHET is as follows: firstly, using protonic acid and Lewis acid to synergistically catalyze, using paraformaldehyde to monochloromethylate BHET to obtain a mixture of BHET and monochloromethylate BHET, and then quaternizing the mixture to obtain a mixture of BHET and quaternized BHET; The molar ratio of BHET, paraformaldehyde and Lewis acid is 1:0.65-1:1.3-1.5, and the mass ratio of BHET to protonic acid is 1:0.65-0.85; monochloromethylation means that only one position on the aromatic ring of BHET is chloromethylated; the temperature of the monochloromethylation reaction is 50-70°C, and the time is 5-8h; The polymerization degree of the paraformaldehyde is 5 to 15; the protonic acid is concentrated hydrochloric acid with a concentration of 36 to 38 wt%, or a mixture of concentrated sulfuric acid with a concentration of 60 to 70 wt% and concentrated hydrochloric acid with a concentration of 36 to 38 wt%, wherein the mass of the concentrated sulfuric acid is less than 20 wt% of the mass of the concentrated hydrochloric acid; the Lewis acid is tin chloride or ammonium chloride; The temperature of the polycondensation reaction is 250-280°C, the absolute pressure is 30-100 Pa, and the time is 2-4 hours. The method for preparing an acidic dyeable copolyester according to claim 1, characterized in that the preparation steps of the mixture of BHET and quaternized BHET are as follows: (a) Monochloromethylation reaction; After paraformaldehyde, Lewis acid, protonic acid and BHET are mixed, the mixture is heated and stirred to perform a monochloromethylation reaction to obtain a mixture of BHET and monochloromethylated BHET; (b) quaternization reaction; The mixture of all BHET and monochloromethylated BHET obtained in step (a) is uniformly mixed with an ethylene glycol solution of trimethylamine, the pH value is adjusted to 8-9.5 with an alkali solution, and the mixture is heated and stirred to carry out a quaternization reaction. After the reaction is completed, a mixture of BHET and quaternized BHET is obtained. The method for preparing an acidic dyeable copolyester according to claim 2, characterized in that in step (a), the yield of the monochloromethylation reaction is 30-50%; In step (b), the concentration of trimethylamine in the ethylene glycol solution of trimethylamine is 40-45wt%; the temperature of the quaternization reaction is 50-80°C, and the time is 2-4h; the molar ratio of the raw material BHET in step (a) to the raw material trimethylamine in step (b) is 1:0.85-1.0. The acidic dyeable copolyester prepared by the method for preparing an acidic dyeable copolyester according to any one of claims 1 to 3 is characterized in that it is a random copolymer, the molecular chain is composed of _M1 repeating units and _M2 repeating units, and the structural formula of the _M1 repeating unit is The structural formula of the _M2 repeating unit is The acidic dyeable copolyester according to claim 4, characterized in that the acidic dyeable copolyester has a glass transition temperature of 73 to 75°C, a melting point of 240 to 245°C, a crystallinity of 35 to 40%, an intrinsic viscosity of 0.52 to 0.58 dL/g, and a number average molecular weight of 15,000 to 16,000 g/mol. The acid dyeable copolyester according to claim 4 is characterized in that when the acid dyeable copolyester chips are dyed at room temperature and pressure, the acid dye uptake is ≥96%; the acid dyeable copolyester is spun, wound and stretched to obtain the acid dyeable copolyester fiber, the spinning speed is 3500-6000 m/min, the breaking strength of the acid dyeable copolyester fiber is ≥4 cN/dtex, when dyed at room temperature and pressure, the acid dye uptake is ≥94%, the color fastness to washing is ≥4 level, the color fastness to rubbing is ≥4 level, and the strength loss after dyeing is 4-6%.