Method for synthesizing water-soluble polyester without catalyst

Abstract

The invention relates to a method for synthesizing water-soluble polyester without a catalyst. The method comprises the following steps: (1) preparing dicarboxylic acid, dihydric alcohol and dibasic acid salt; wherein (n1 + n3): n2 = (1.02-3): 1, n1 is the amount of substance of dicarboxylic acid, n2 is the amount of substance of dihydric alcohol, and n3 is the amount of substance of dibasic acid salt; (2) carrying out esterification reaction in an inert atmosphere at the reaction temperature of 80-220 DEG C for 1-20 hours; and (3) carrying out condensation polymerization under a vacuum condition at the reaction temperature of 220-300 DEG C for 1-10 hours. According to the synthesis method disclosed by the invention, environmental and health risks brought by a traditional catalyst are avoided, the prepared polyester not only has good stability and performance in the chemical structure, but also fully considers environmental friendliness and safety in the production process; the novel polyester materials are non-toxic and harmless, and conform to the concepts of green economy and sustainable development.

Description

Technical Field

[0001] The invention belongs to the technical field of polyester synthesis, and particularly relates to a method for synthesizing water-soluble polyester without a catalyst. Background Art

[0002] Synthetic polymer materials have become indispensable general materials in modern society due to their light weight, low cost, excellent corrosion resistance and durability. They are widely used in packaging, construction, transportation, electronics and other fields. These materials have good mechanical properties, chemical stability and convenient processing, and meet various industrial needs, so they are widely used in daily life. However, the raw materials of most synthetic polymer materials come from petroleum-derived compounds, such as polyethylene PE, polypropylene PP and polyethylene terephthalate PET. While these plastic products improve the quality of life, they also bring challenges in environmental sustainability.

[0003] Although these synthetic materials have significant advantages and wide applications in many fields, they also have significant disadvantages. First, the recycling process of these materials is very difficult, mainly due to their complex chemical structure and diverse processing methods, resulting in an imperfect recycling system and high processing costs. Secondly, since the degradation cycle of most synthetic polymer materials is extremely long, they are not naturally degradable in the environment and are prone to long-term accumulation in the natural environment, forming a large amount of plastic waste. A large amount of untreated plastic waste not only occupies a large amount of land resources, but also causes serious pollution to natural ecosystems such as water bodies, soil and air, and further poses a potential threat to wildlife and human health. Therefore, the non-degradability and difficulty of recycling of synthetic polymer materials have become major challenges facing current environmental protection and sustainable development.

[0004] At present, although aliphatic polyesters have good biodegradability, their degradation cycle is long, especially in unsuitable environmental conditions (such as dry or sterile environments), and they are difficult to degrade. In addition, aliphatic polyesters generally have low water solubility and cannot be dissolved in water or have low solubility, so they are usually not suitable for water-based applications, which limits their use in some fields that require water-soluble materials.

[0005] In addition, the synthesis process of aliphatic polyesters usually relies on the introduction of metal catalysts to promote the polymerization reaction and increase the molecular weight of polyesters. However, the use of such metal catalysts may lead to metal residues of the catalyst, which may bring potential risks and hazards to human health and the ecological environment, and at the same time limit their application in high-end fields. As early as 1929, Carothers, a pioneer in the field of polymer chemistry, systematically studied the preparation of polyesters by direct polyesterification of dicarboxylic acids and diols in the absence of catalysts. In polyesterification, this system can promote the increase of molecular weight through the autocatalytic effect of dicarboxylic acids. However, Carothers encountered major challenges in maintaining a balanced carboxyl to hydroxyl ratio during polyesterification, which is crucial for obtaining high molecular weight polyesters. At the same time, the reduction of terminal carboxyl groups in the late stage of polyesterification further hindered the success of the synthesis. Subsequently, the industry adopted transesterification using excess alcohol as a synthesis method. This method helps to achieve an equimolar ratio between functional groups through the exchange of small alcohol molecules. Due to the absence of autocatalytic carboxyl groups and the high activation energy associated with transesterification, heavy metal catalysts are required to improve the reaction efficiency. Generally speaking, the process of removing metal catalyst residues in polyester requires the use of organic solvents, which not only significantly increases production costs, but also may introduce solvent residue problems, thereby creating new environmental and safety hazards. Therefore, how to fundamentally eliminate toxic metal catalyst residues in polyester while maintaining the lowest cost remains a major challenge in current polyester synthesis. Summary of the invention

[0006] Based on the above-mentioned shortcomings and deficiencies in the prior art, one of the objects of the present invention is to at least solve one or more of the above-mentioned problems in the prior art. In other words, one of the objects of the present invention is to provide a method for synthesizing water-soluble polyester without catalyst that meets one or more of the above-mentioned needs.

[0007] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions:

[0008] A method for synthesizing water-soluble polyester without a catalyst comprises the following steps:

[0009] (1) ingredients of dicarboxylic acid, diol and dibasic acid salt; wherein, (n1+n3):n2=(1.02-3):1, n1 is the amount of substance of dicarboxylic acid, n2 is the amount of substance of diol, and n3 is the amount of substance of dibasic acid salt;

[0010] (2) conducting an esterification reaction under an inert atmosphere at a temperature of 80 to 220° C. for a reaction time of 1 to 20 h;

[0011] (3) Carry out polycondensation reaction under vacuum conditions, with the reaction temperature being 220 to 300° C. and the reaction time being 1 to 10 hours.

[0012] As a preferred embodiment, the molar ratio of the dicarboxylic acid to the dibasic acid salt is 0.9-60.

[0013] As a preferred embodiment, the structural formula of the dicarboxylic acid is:

[0014]

[0015] Among them, R1 is an aliphatic hydrocarbon having 1 to 36 carbon atoms, an aromatic hydrocarbon, or an ether having a repeating unit of -CH2CH2O-, -CH2CH2CH2O- or -CH2CH2CH2CH2O- and an average molecular weight of 200 to 6000.

[0016] As a preferred embodiment, the dibasic acid includes malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, tetradecanedioic acid, hexadecanedioic acid, octadecanedioic acid, methylmalonic acid, 2-butyl suberic acid, 2-propylmalonic acid, 2-methylglutaric acid, 3-methylglutaric acid, 3-methylhexanedioic acid, maleic acid, fumaric acid, itaconic acid, isopropylmalonic acid, 2,3-dibromosuccinic acid, para- One or more of phthalic acid, isophthalic acid, orthophthalic acid, 5-methylisophthalic acid, phenylsuccinic acid, benzymalonic acid, furandicarboxylic acid, pyridinedicarboxylic acid, cyclohexanedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, dimer acid, hydrogenated dimer acid, hydrogenated dimer oleic acid, dimer linoleic acid, dimer linolenic acid, dimer myristic acid, polyethylene glycol terminated with carboxyl groups at both ends, polypropylene glycol terminated with carboxyl groups at both ends, and polytetrahydrofuran terminated with carboxyl groups at both ends.

[0017] As a preferred embodiment, the structural formula of the diol is:

[0018]

[0019] Among them, R2 is an aliphatic hydrocarbon with 2 to 36 carbon atoms, an aromatic hydrocarbon, or an ether with a repeating unit of -CH2CH2O-, -CH2CH2CH2O- or -CH2CH2CH2CH2O- and an average molecular weight of 200 to 6000.

[0020] As a preferred embodiment, the diol includes one or more of ethylene glycol, propylene glycol, butylene glycol, pentanediol, hexanediol, heptanediol, octanediol, nonanediol, decanediol, undecanediol, dodecanediol, tetradecanediol, terephthalic acid alcohol, isophthalic acid alcohol, o-phthalic acid alcohol, furan dimethanol, furan dimethanol, pyridine dimethanol, cyclohexanedimethanol, catechol, resorcinol, hydroquinone, 1,3-adamantanediol, phenyl glycol, polyethylene glycol, polypropylene glycol, and polytetrahydrofuran.

[0021] As a preferred embodiment, the structural formula of the dibasic acid salt is:

[0022]

[0023] or

[0024] X 2 -Y 2+

[0025] Wherein, R3 is an aliphatic hydrocarbon having 1 to 36 carbon atoms, an aromatic hydrocarbon, or an ether having a repeating unit of -CH2CH2O-, -CH2CH2CH2O-, or -CH2CH2CH2CH2O- and an average molecular weight of 200 to 6000, X- or X 2 - is an anion, Y + or Y 2+ It is a cation.

[0026] As a preferred embodiment, the dibasic acid salt includes malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanoic acid, dodecanedioic acid, tetradecanedioic acid, hexadecanedioic acid, octadecanedioic acid, methylmalonic acid, 2-butyl suberic acid, 2-propylmalonic acid, 2-methylglutaric acid, 3-methylglutaric acid, 3-methylhexanodioic acid, maleic acid, fumaric acid, itaconic acid, isopropylmalonic acid, 2,3-dibromosuccinic acid, terephthalic acid, One or more of dicarboxylic acid, isophthalic acid, phthalic acid, 5-methylisophthalic acid, phenylsuccinic acid, benzymalonic acid, furandicarboxylic acid, pyridinedicarboxylic acid, cyclohexanedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, dimer acid, hydrogenated dimer acid, hydrogenated dimer oleic acid, dimer linoleic acid, dimer linolenic acid, dimer myristic acid, polyethylene glycol terminated with carboxyl groups at both ends, polypropylene glycol terminated with carboxyl groups at both ends, polytetrahydrofuran terminated with carboxyl groups at both ends, and cationic Na + , K + , Ca 2+ Mg 2+ , Li + , Sr 2+ NH4 + 、Zn 2+ And one or more of dibasic acid salts composed of anionic carboxylate, sulfate, sulfite, nitrate, acetate, phosphate and sulfonate.

[0027] As a preferred embodiment, in the step (2), the temperature of the esterification reaction is 130 to 220° C. and the time is 6 to 10 hours.

[0028] As a preferred embodiment, in step (3), the vacuum degree is less than 30 Pa, the temperature of the polycondensation reaction is 220-260° C., and the time is 2-8 hours.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] (1) The water-soluble polyester synthesis method provided by the present invention does not contain any additive catalyst, abandons the traditional toxic metal catalyst, and successfully synthesizes a series of high molecular weight polyester materials by adopting the catalyst-free polycondensation mechanism; the synthesis method avoids the environmental and health risks brought by traditional catalysts, and the prepared polyester not only has good stability and performance in chemical structure, but also fully considers environmental friendliness and safety in the production process; these new polyester materials are non-toxic and harmless, and conform to the concept of green economy and sustainable development;

[0031] (2) The polyester material prepared by the present invention has excellent water solubility. Compared with traditional plastics, these polyesters can be degraded more efficiently through water treatment or biodegradation after use, thereby significantly reducing persistent pollution to the environment. In addition, the water solubility of polyesters also provides new possibilities for their application in multiple fields. For example, in drug delivery systems, water-soluble polyesters can achieve controlled release of drugs and improve drug bioavailability and targeting. In the field of cleaning products such as laundry beads, these polyesters can quickly dissolve in water and release active ingredients, which is in line with the development trend of modern green washing technology.

[0032] (3) Although the polyester prepared by the present invention exhibits excellent water solubility, a dynamic cross-linking structure is introduced into its molecular structure, so that it exhibits excellent mechanical properties while maintaining good solubility; this dynamic cross-linking structure can form reversible physical cross-linking points between the molecular chains of the polyester, thereby enhancing the mechanical strength, toughness and deformation resistance of the water-soluble polyester; in addition, by adjusting the feed ratio of the reactants, the mechanical properties of the polyester, including its tensile strength, elastic modulus and elongation at break, can be effectively adjusted. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 The tensile curves of the polyester obtained in Example 1 of the present invention and Comparative Example 1 are shown;

[0034] Figure 2 This is a comparison diagram of the swelling and dissolution of the polyester obtained in Example 1 of the present invention and in Comparative Example 1;

[0035] Figure 3 This is a photo of the polyester of Example 1 of the present invention being used as the outer film of laundry beads. DETAILED DESCRIPTION

[0036] The synthesis method of the water-soluble polyester without any additive catalyst of the present invention mainly involves the esterification reaction of dicarboxylic acid, diol and dibasic acid salt in an inert atmosphere and the polycondensation reaction of prepolymer under vacuum conditions, and the reaction formula is as follows:

[0037]

[0038] Wherein, R1 is an aliphatic hydrocarbon having 1 to 36 carbon atoms, an aromatic hydrocarbon, or an ether having a repeating unit of -CH2CH2O-, -CH2CH2CH2O-, or -CH2CH2CH2CH2O- and an average molecular weight of 200 to 6000;

[0039] R2 is an aliphatic hydrocarbon having 2 to 36 carbon atoms, an aromatic hydrocarbon, or an ether having a repeating unit of -CH2CH2O-, -CH2CH2CH2O-, or -CH2CH2CH2CH2O- and an average molecular weight of 200 to 6000;

[0040] R3 is an aliphatic hydrocarbon having 1 to 36 carbon atoms, an aromatic hydrocarbon, or an ether having a repeating unit of -CH2CH2O-, -CH2CH2CH2O-, or -CH2CH2CH2CH2O- and an average molecular weight of 200 to 6000;

[0041] X is carboxylic acid, sulfuric acid, sulfurous acid, nitric acid, acetic acid, phosphoric acid, or sulfonic acid;

[0042] Y is Na, K, Ca, Mg, Li, Sr, NH4, Zn.

[0043] The above-mentioned dibasic acids preferably include malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, tetradecanedioic acid, hexadecanedioic acid, octadecanedioic acid, methylmalonic acid, 2-butyl suberic acid, 2-propylmalonic acid, 2-methylglutaric acid, 3-methylglutaric acid, 3-methylhexanedioic acid, maleic acid, fumaric acid, itaconic acid, isopropylmalonic acid, 2,3-dibromosuccinic acid, terephthalic acid, One or more of formic acid, isophthalic acid, phthalic acid, 5-methylisophthalic acid, phenylsuccinic acid, benzymalonic acid, furandicarboxylic acid, pyridinedicarboxylic acid, cyclohexanedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, dimer acid, hydrogenated dimer acid, hydrogenated dimer oleic acid, dimer linoleic acid, dimer linolenic acid, dimer myristic acid, polyethylene glycol terminated with carboxyl groups at both ends, polypropylene glycol terminated with carboxyl groups at both ends, and polytetrahydrofuran terminated with carboxyl groups at both ends.

[0044] The above-mentioned diols preferably include one or more of ethylene glycol, propylene glycol, butylene glycol, pentanediol, hexanediol, heptanediol, octanediol, nonanediol, decanediol, undecanediol, dodecanediol, tetradecanediol, terephthalylidene alcohol, isophthalylidene alcohol, o-phthalylidene alcohol, furan dimethanol, furan dimethanol, pyridine dimethanol, cyclohexanedimethanol, catechol, resorcinol, hydroquinone, 1,3-adamantanediol, phenyl glycol, polyethylene glycol, polypropylene glycol, and polytetrahydrofuran.

[0045] The above-mentioned dibasic acid salt preferably includes malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, tetradecanedioic acid, hexadecanedioic acid, octadecanedioic acid, methylmalonic acid, 2-butyl suberic acid, 2-propylmalonic acid, 2-methylglutaric acid, 3-methylglutaric acid, 3-methylhexanedioic acid, maleic acid, fumaric acid, itaconic acid, isopropylmalonic acid, 2,3-dibromosuccinic acid, terephthalic acid , isophthalic acid, phthalic acid, 5-methylisophthalic acid, phenylsuccinic acid, benzymalonic acid, furandicarboxylic acid, pyridinedicarboxylic acid, cyclohexanedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, dimer acid, hydrogenated dimer acid, hydrogenated dimer oleic acid, dimer linoleic acid, dimer linolenic acid, dimer myristic acid, polyethylene glycol terminated with carboxyl groups at both ends, polypropylene glycol terminated with carboxyl groups at both ends, polytetrahydrofuran terminated with carboxyl groups at both ends, one or more of the following, positive ion Na + , K + , Ca 2+ Mg 2+ , Li + , Sr 2+ NH4 + 、Zn 2+ And one or more of dibasic acid salts composed of anionic carboxylate, sulfate, sulfite, nitrate, acetate, phosphate and sulfonate.

[0046] The above-mentioned ingredients of dicarboxylic acid, diol and dibasic acid salt; wherein, (n1+n3):n2=(1.02-3):1, n1 is the amount of dicarboxylic acid, n2 is the amount of diol, n3 is the amount of dibasic acid salt; the molar ratio of dicarboxylic acid to dibasic acid salt is 0.9-60; the present invention limits the molar ratio of dicarboxylic acid, diol and dibasic acid salt to the above-mentioned range to ensure that the prepared polyester has good water solubility and mechanical properties.

[0047] The above-mentioned esterification reaction is carried out under an inert atmosphere, and the selected inert atmosphere is preferably argon. When introducing argon, the present invention does not strictly limit the gas flow rate, and the flow rate commonly used by those skilled in the art can be adopted. Among them, the temperature of the esterification reaction is preferably in the range of 80 to 220°C, more preferably 130 to 200°C; the reaction time is preferably 1 to 20 hours, more preferably 6 to 10 hours. The setting of the temperature and time range is intended to ensure that the dibasic acid and the diol can fully react and promote the efficient conduct of the esterification reaction.

[0048] In addition, the above esterification reaction is preferably carried out under stirring conditions to improve the uniformity and reaction rate of the reaction. The stirring speed is preferably >100 rpm, more preferably 200-400 rpm. Appropriate stirring helps to enhance the mixing and contact of the reactants, thereby promoting the reaction.

[0049] The polycondensation reaction is carried out under vacuum conditions, and the preferred vacuum degree is <150Pa, and more preferably <30Pa. The present invention facilitates separation of the byproduct water produced in the reaction from the polymerization system by introducing argon and establishing a vacuum negative pressure environment, thereby promoting the polymerization reaction to proceed in the forward direction. Under vacuum conditions, the temperature of the polycondensation reaction is preferably 200-300°C, and more preferably 220-260°C; the reaction time is preferably 1-10 hours, and more preferably 2-8 hours. The present invention can ensure the full progress of the reaction by precisely controlling the reaction temperature and time, thereby obtaining a polyester material with a higher molecular weight and excellent performance.

[0050] Similarly, the polycondensation reaction is also preferably carried out under stirring conditions, and the stirring speed is preferably >100 rpm, more preferably 200 to 400 rpm. Appropriate stirring can effectively improve the efficiency of the reaction, ensure the reactants are fully mixed and evenly distributed during the reaction, and thus promote the smooth progress of the polycondensation reaction.

[0051] The technical solution of the present invention is further explained below through specific embodiments.

[0052] Embodiment 1:

[0053] 1.845 kg of succinic acid (SA), 1 kg of ethylene glycol (EG) and 0.432 kg of sodium 5-sulfoisophthalic acid (5-SSIPA) (Mol feed ratio of SA:EG:5-SSIPA=0.97:1:0.1) were added to the reactor in sequence, and an inert argon gas flow was introduced into the reactor to protect the reactants from oxidation. The temperature was gradually raised to 200°C under normal pressure to carry out esterification reaction, and the stirring speed was kept above 200r / min for 9 hours to obtain a carboxyl-terminated prepolymer. After the esterification was completed, the reactor was connected to an oil pump to make the vacuum degree of the polymerization system lower than 100Pa, and the temperature was raised to 250°C to carry out ester exchange reaction, and the reaction was continued for 6 hours. Under high temperature and reduced pressure conditions, the dicarboxylic acid was continuously extracted from the polymerization system by sublimation, so that the viscosity continued to increase, and the final product, water-soluble polyester, was obtained.

[0054] According to tests, the water-soluble polyester obtained in this example can be completely dissolved in deionized water, has an intrinsic viscosity of 0.787 dL / g, a tensile strength of 20.84 MPa, and an elongation at break of 789%.

[0055] Embodiment 2:

[0056] The difference between this embodiment and embodiment 1 is that:

[0057] Only succinic acid was replaced by glutaric acid, glutaric acid 2.064 kg, ethylene glycol 1 kg, isophthalic acid-5-sodium sulfonate 0.432 kg, the Mol ratio of the three was glutaric acid: ethylene glycol: isophthalic acid-5-sodium sulfonate = 0.97:1:0.1;

[0058] Others are the same as in Example 1;

[0059] After testing, it was found that the water-soluble polyester obtained in this example can be completely dissolved in deionized water.

[0060] Embodiment 3:

[0061] The difference between this embodiment and embodiment 1 is that:

[0062] Ethylene glycol was replaced by butanediol, succinic acid 0.707 kg, butanediol 1 kg, 5-sodium sulfoisophthalic acid 0.165 kg, the Mol ratio of the three was succinic acid: butanediol: 5-sodium sulfoisophthalic acid = 0.97:1:0.1;

[0063] Others are the same as in Example 1;

[0064] After testing, it was found that the water-soluble polyester obtained in this example can be completely dissolved in deionized water.

[0065] Embodiment 4:

[0066] The difference between this embodiment and embodiment 1 is that:

[0067] The Mol ratio of succinic acid and sodium 5-sulfoisophthalate is different, succinic acid 1.94kg, ethylene glycol 1kg, sodium 5-sulfoisophthalate 0.216kg, the Mol ratio of the three is succinic acid: ethylene glycol: sodium 5-sulfoisophthalate = 1.02: 1: 0.05;

[0068] Others are the same as in Example 1;

[0069] According to tests, the water-soluble polyester obtained in this example can be completely dissolved in deionized water, has an intrinsic viscosity of 0.773 dL / g, a tensile strength of 31.09 MPa, and an elongation at break of 619%.

[0070] Embodiment 5:

[0071] The difference between this embodiment and embodiment 1 is that:

[0072] The Mol feed ratios of succinic acid and 5-sodium sulfoisophthalate are different, 1.75 kg of succinic acid, 1 kg of ethylene glycol, and 0.648 kg of 5-sodium sulfoisophthalate. The Mol ratio of the three is succinic acid: ethylene glycol: 5-sodium sulfoisophthalate = 0.92:1:0.15;

[0073] Other aspects are the same as in Example 1;

[0074] According to tests, the water-soluble polyester obtained in this example can be completely dissolved in deionized water, has an intrinsic viscosity of 0.790 dL / g, a tensile strength of 24.23 MPa, and an elongation at break of 516%.

[0075] Embodiment 6:

[0076] The difference between this embodiment and embodiment 1 is that:

[0077] The Mol feed ratios of succinic acid and 5-sodium sulfoisophthalate are different, 1.65 kg of succinic acid, 1 kg of ethylene glycol, and 0.864 kg of 5-sodium sulfoisophthalate. The Mol ratio of the three is succinic acid: ethylene glycol: 5-sodium sulfoisophthalate = 0.87:1:0.2;

[0078] Other aspects are the same as in Example 1;

[0079] According to tests, the water-soluble polyester obtained in this example can be completely dissolved in deionized water, has an intrinsic viscosity of 0.827 dL / g, a tensile strength of 26.46 MPa, and an elongation at break of 55%.

[0080] Embodiment 7:

[0081] The difference between this embodiment and embodiment 1 is that:

[0082] The Mol ratio of succinic acid and sodium 5-sulfoisophthalate is different, succinic acid 1.56kg, ethylene glycol 1kg, sodium 5-sulfoisophthalate 1.08kg, the Mol ratio of the three is succinic acid: ethylene glycol: sodium 5-sulfoisophthalate = 0.82: 1: 0.25;

[0083] Other aspects are the same as in Example 1;

[0084] According to the test, the water-soluble polyester obtained in this example can be completely dissolved in deionized water, and its intrinsic viscosity is 0.842 dL / g.

[0085] Embodiment 8:

[0086] The difference between this embodiment and embodiment 1 is that:

[0087] The Mol feed ratios of succinic acid and 5-sodium sulfoisophthalate are different, 1.465 kg of succinic acid, 1 kg of ethylene glycol, and 1.296 kg of 5-sodium sulfoisophthalate. The Mol ratio of the three is succinic acid: ethylene glycol: 5-sodium sulfoisophthalate = 0.77:1:0.3;

[0088] Other aspects are the same as in Example 1;

[0089] According to the test, the water-soluble polyester obtained in this example can be completely dissolved in deionized water, and its intrinsic viscosity is 0.870 dL / g.

[0090] Comparative Example 1:

[0091] The difference between this comparative example and Example 1 is that:

[0092] No sodium 5-sulfoisophthalate was added, succinic acid 2.036 kg, ethylene glycol 1 kg, the Mol ratio of the two was succinic acid: ethylene glycol = 1.07:1;

[0093] Others are the same as in Example 1;

[0094] After testing, it was found that the polyester obtained in this comparative example was completely insoluble in deionized water, and its intrinsic viscosity was 0.0.574 dL / g, its tensile strength was 33.52 MPa, and its elongation at break was 322%.

[0095] Comparative Example 2:

[0096] The difference between this comparative example and Example 1 is that:

[0097] Replace isophthalic acid with 5-sulfoisophthalic acid sodium salt, 1.845 kg of succinic acid, 1 kg of ethylene glycol, and 0.268 kg of isophthalic acid, and the Mol ratio of the three is succinic acid: ethylene glycol: isophthalic acid = 0.97:1:0.1;

[0098] Others are the same as in Example 1;

[0099] After testing, it was found that the polyester obtained in this comparative example could not be dissolved in deionized water at all.

[0100] Comparative Example 3:

[0101] The difference between this comparative example and Example 1 is that:

[0102] Sodium benzenesulfonate was replaced by sodium 5-sulfoisophthalate, 2.036 kg of succinic acid, 1 kg of ethylene glycol, and 0.29 kg of sodium benzenesulfonate, and the Mol ratio of the three was succinic acid: ethylene glycol: sodium benzenesulfonate = 1.07:1:0.1;

[0103] Others are the same as in Example 1;

[0104] After testing, it was found that the polyester obtained in this comparative example could not be dissolved in deionized water at all.

[0105] Comparative Example 4:

[0106] The difference between this comparative example and Example 1 is that:

[0107] The acid-alcohol feed ratio is different, with the acid in excess in Example 1 and the alcohol in excess in Comparative Example 4;

[0108] 1.619 kg of succinic acid, 1 kg of ethylene glycol, and 0.379 kg of 5-sodium sulfoisophthalate. The Mol ratio of the three is succinic acid: ethylene glycol: 5-sodium sulfoisophthalate = 0.97: 1.14: 0.1;

[0109] After testing, although the polyester obtained in this comparative example can be dissolved in deionized water, due to the excessive amount of alcohol used in the reaction process and the absence of a catalyst, the efficiency of the esterification reaction is low, the reaction is not fully advanced, and the molecular weight of the obtained polyester is relatively low. In addition, the low molecular weight directly affects the chain structure and cross-linking degree of the polyester, resulting in poor mechanical properties, especially in terms of tensile strength and elongation at break, and its application is greatly limited.

[0110] In addition, a universal testing machine was used to test the mechanical properties of the water-soluble polyester and PES obtained in Example 1 and Comparative Example 1. The tensile curves obtained by the test are as follows: Figure 1 As shown in the figure, from the analysis results of the tensile curve, it can be seen that the tensile curve of the polyester in Comparative Example 1 shows typical crystalline characteristics, which is manifested as a relatively clear yield point and relatively low elongation, indicating that it is mainly composed of a semi-crystalline phase and has a high structural rigidity; after the addition of the dibasic acid salt, the tensile curve clearly shows the characteristics of an elastomer, which is specifically manifested as a relatively gentle stress-strain relationship and a large elongation in the curve, indicating that the introduction of the dibasic acid salt leads to the formation of a cross-linked structure between the polymer segments. The formation of cross-linking points effectively enhances the three-dimensional structural stability of the polymer network and significantly improves its elastic properties, thereby improving the flexibility and deformation ability of the material.

[0111] Tensile strength: measured according to the measurement method specified in ISO 527-2 Plastic tensile properties test method, where the tensile rate is 50mm / min;

[0112] Elongation at break: measured according to the measurement method specified in ISO 527-2 Test method for tensile properties of plastics, where the tensile rate is 50 mm / min;

[0113] The dissolution and swelling experiments of Example 1 and Comparative Example 1 were carried out using chloroform solvent. The results are as follows: Figure 2The results show that Comparative Example 1 can be completely dissolved in chloroform, while Example 1 can only swell but not dissolve in chloroform, and Example 1 can be melt-processed into dumbbell-shaped splines at high temperatures, which indicates that Example 1 has a cross-linked structure at low temperatures and exhibits thermoplasticity at high temperatures due to the cleavage of ionic bonds. This further verifies that while Example 1 has good water solubility, its cross-linked structure also provides Example 1 with good mechanical properties.

[0114] Given the excellent water-solubility of this material, it has shown wide application potential in the field of laundry beads. Specifically, this material can be used as the outermost film of laundry beads to ensure that they can dissolve quickly when exposed to water, thereby effectively releasing the cleaning ingredients in them. Figure 3 As shown, using this material as the outer film can ensure that the laundry beads can be quickly dissolved during use, and have good water solubility and environmental friendliness. This application can not only improve the washing effect, but also optimize the convenience and environmental friendliness of the laundry beads. Therefore, this material has important practical application value in the production process of laundry beads.

[0115] In view of the numerous embodiments of the scheme of the present invention, the raw materials, dosages and process parameters involved can be selected within the limited range according to actual needs. The experimental data of each embodiment is huge and numerous, which is not suitable for listing and describing one by one here, but the contents to be verified and the final conclusions obtained in each embodiment are similar. Therefore, the verification contents of each embodiment will not be described one by one here.

[0116] The above description is only a detailed description of the preferred embodiments and principles of the present invention. For ordinary technicians in this field, according to the ideas provided by the present invention, there will be changes in the specific implementation methods, and these changes should also be regarded as the protection scope of the present invention.

Claims

1. A method for synthesizing water-soluble polyester without a catalyst, characterized in that: The following steps are involved: (1) ingredients of dicarboxylic acid, diol and dibasic acid salt; wherein, (n1+n3):n2=(1.02-3):1, n1 is the amount of substance of dicarboxylic acid, n2 is the amount of substance of diol, and n3 is the amount of substance of dibasic acid salt; (2) conducting an esterification reaction under an inert atmosphere at a temperature of 80 to 220° C. for a time of 1 to 20 hours; (3) Carry out polycondensation reaction under vacuum conditions at a temperature of 200 to 300° C. for 1 to 10 hours.

2. The method according to claim 1, characterized in that The molar ratio of the dicarboxylic acid to the dibasic acid salt is 0.9-60.

3. The method according to claim 1, characterized in that The structural formula of the dicarboxylic acid is: Among them, R1 is an aliphatic hydrocarbon having 1 to 36 carbon atoms, an aromatic hydrocarbon, or an ether having a repeating unit of -CH2CH2O-, -CH2CH2CH2O- or -CH2CH2CH2CH2O- and an average molecular weight of 200 to 6000.

4. The method according to claim 3, characterized in that The dibasic acids include malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, tetradecanedioic acid, hexadecanedioic acid, octadecanedioic acid, methylmalonic acid, 2-butyl suberic acid, 2-propylmalonic acid, 2-methylglutaric acid, 3-methylglutaric acid, 3-methylhexanedioic acid, maleic acid, fumaric acid, itaconic acid, isopropylmalonic acid, 2,3-dibromosuccinic acid, terephthalic acid One or more of 1,2-dimethyl-2-nitropropene, 1,4-naphthalene dicarboxylic acid, 2,6-naphthalene dicarboxylic acid, dimeric acid, hydrogenated dimeric acid, hydrogenated dimeric oleic acid, dimeric linoleic acid, dimeric linolenic acid, dimeric myristic acid, polyethylene glycol terminated with carboxyl groups at both ends, polypropylene glycol terminated with carboxyl groups at both ends, and polytetrahydrofuran terminated with carboxyl groups at both ends.

5. The method according to claim 1, characterized in that The structural formula of the diol is: Among them, R2 is an aliphatic hydrocarbon with 2 to 36 carbon atoms, an aromatic hydrocarbon, or an ether with a repeating unit of -CH2CH2O-, -CH2CH2CH2O- or -CH2CH2CH2CH2O- and an average molecular weight of 200 to 6000.

6. The method according to claim 5, characterized in that The diols include one or more of ethylene glycol, propylene glycol, butylene glycol, pentanediol, hexanediol, heptanediol, octanediol, nonanediol, decanediol, undecanediol, dodecanediol, tetradecanediol, terephthalylidene alcohol, isophthalylidene alcohol, o-phthalylidene alcohol, furan dimethanol, furan dimethanol, pyridine dimethanol, cyclohexanedimethanol, catechol, resorcinol, hydroquinone, 1,3-adamantanediol, phenyl glycol, polyethylene glycol, polypropylene glycol, and polytetrahydrofuran.

7. The method according to claim 1, characterized in that The structural formula of the dibasic acid salt is: Wherein, R3 is an aliphatic hydrocarbon having 1 to 36 carbon atoms, an aromatic hydrocarbon, or an ether having a repeating unit of -CH2CH2O-, -CH2CH2CH2O-, or -CH2CH2CH2CH2O- and an average molecular weight of 200 to 6000, and X - or X 2- is an anion, Y + or Y 2+ It is a cation.

8. The method according to claim 7, characterized in that The dibasic acid salts include malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, tetradecanedioic acid, hexadecanedioic acid, octadecanedioic acid, methylmalonic acid, 2-butyl suberic acid, 2-propylmalonic acid, 2-methylglutaric acid, 3-methylglutaric acid, 3-methylhexanedioic acid, maleic acid, fumaric acid, itaconic acid, isopropylmalonic acid, 2,3-dibromosuccinic acid, terephthalic acid, Isophthalic acid, phthalic acid, 5-methylisophthalic acid, phenylsuccinic acid, benzymalonic acid, furandicarboxylic acid, pyridinedicarboxylic acid, cyclohexanedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, dimer acid, hydrogenated dimer acid, hydrogenated dimer oleic acid, dimer linoleic acid, dimer linolenic acid, dimer myristic acid, polyethylene glycol terminated with carboxyl groups at both ends, polypropylene glycol terminated with carboxyl groups at both ends, polytetrahydrofuran terminated with carboxyl groups at both ends, or one or more of cationic Na + , K + , Ca 2+ Mg 2+ , Li + , Sr 2 + NH4 + 、Zn 2+ And one or more of dibasic acid salts composed of anionic carboxylate, sulfate, sulfite, nitrate, acetate, phosphate and sulfonate.

9. The method according to any one of claims 1 to 8, characterized in that: In the step (2), the temperature of the esterification reaction is 130 to 220° C., and the time is 6 to 10 hours.

10. The method according to any one of claims 1 to 8, characterized in that: In the step (3), the vacuum degree is less than 30 Pa, the temperature of the polycondensation reaction is 220-260° C., and the time is 2-8 hours.

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