Preparation method of copolyesteramide

Abstract

The invention discloses a preparation method of copolyesteramide, which comprises the following steps: (1) putting dibasic acid and dihydric alcohol into a reaction kettle according to the molar ratio of carboxylic acid group to alcoholic hydroxyl group of (2.0-2.1): 1, and carrying out esterification dehydration reaction at 150-190 DEG C for 2-3 hours; performing reduced pressure distillation to remove redundant dihydric alcohol and by-products to obtain ester group-containing dicarboxylic acid; (2) putting dibasic acid, the ester group-containing dicarboxylic acid, aliphatic diamine, lactam, a stabilizer, an end-capping reagent and other auxiliaries into a salifying kettle, and carrying out polymerization reaction at 220-250 DEG C under 1.0-1.8 MPa for 3-5 hours; then vacuumizing until the melt index is 35 to 40g / 10min; and (3) releasing the vacuum, and discharging while hot to obtain the copolyesteramide. According to the invention, the molecular weight and molecular weight distribution of copolyamide can be controlled, so that the whole molecular chain structure is uniform, and collaborative optimization of polyester and polyamide performance is realized to the greatest extent.

Description

Technical Field

[0001] This invention belongs to the field of polyester hot melt adhesive technology, specifically relating to a method for preparing copolyesteramide for use in garment linings, textile fibers and adhesives. Background Technology

[0002] Polyamides are a general term for polymers containing repeating amide groups in their main molecular chain. They are semi-crystalline polymers with high strength, good toughness, excellent wear resistance, and corrosion resistance, and are widely used in textiles, electronics, machinery, and other industries. Copolyamides are prepared by copolymerizing several polyamide monomers. Copolymerization reduces the regularity of macromolecules and increases the disorder of intermolecular arrangement. While changing their composition and structure, it also significantly alters their melting point, solubility, crystallinity, and transparency. This results in copolyamides with a series of special properties such as low melting and softening points, good transparency, high adhesive strength, and good flexibility, which are widely used in the hot melt adhesive industry and are particularly favored in the heat sealing and finishing processes of garment linings.

[0003] However, copolyamide molecules are highly polar and easily absorb water, resulting in poor dimensional stability. In applications such as clothing linings, they also cause problems with water resistance. Although copolyesters do not have the same temperature resistance as polyamides, they still have excellent properties. Moreover, the water absorption rate of their ester bonds is lower than that of amide bonds. Therefore, ester bonds can effectively improve the poor water resistance of copolyamides and enhance their dimensional stability. Combining the advantages of both, copolyamides have become an important material.

[0004] Copolyesteramides are novel polymer materials formed by copolymerizing polyester and polyamide segments. They combine the excellent properties of polyester, such as water resistance and flexibility, with those of polyamide, such as temperature resistance and high strength, making them widely used in the polymer industry. For a long time, developing efficient methods for preparing copolyesteramides and controlling parameters such as the ratio of ester to amide bonds and the molecular weight and distribution of the polymer have been key research focuses in this field.

[0005] Patent document CN111748092A discloses a method for preparing polyesteramide, in which the content of diethylene glycol (DEG) in the polyesteramide is controlled at 0.3-6 wt%. Ethylene glycol and aromatic dicarboxylic acids (or their derivatives) are used to prepare a copolyester via esterification or transesterification, which is then polycondensed with polyamide monomers to prepare the copolyamide. However, this document describes the synthesis of a copolyester prepolymer through esterification or transesterification at 200-270°C, adding the copolyamide monomer at the initial stage or during the reaction, or preparing a prepolymer of copolyamide and copolyester separately, which is then reacted with the polyamide monomer to generate the copolyamide. However, the molecular weight and molecular weight distribution of the copolyamide prepared by this method are difficult to control, and the method of adding the polyamide monomer introduces certain difficulties and complexities to the process operation.

[0006] Patent document CN109134850A discloses a method for preparing polyesteramide and its application in fibers. The method involves adding diol, terephthalic acid and / or its derivatives, and diamine and / or its derivatives to a reaction vessel, controlling the temperature rise to allow 90%–100% of the terephthalic acid and / or its derivatives to undergo esterification and acylation reactions to obtain copolyesteramide. However, this method struggles to achieve the correct ratio of amide to ester bonds in the copolyesteramide, and the dispersed molecular weight distribution results in an uneven molecular chain structure, leading to phenomena such as fiber breakage and fuzzing during spinning. Summary of the Invention

[0007] This invention provides a method for preparing copolyesteramide, aiming to solve the problems of difficult control of the reaction system, uncontrollable degree of polymerization of amide segments, and narrow applicability of products in the preparation of existing copolyesteramides; the product has a low melting point, good strength, and excellent water resistance, and can be widely used in clothing linings, textile fibers and adhesives.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for preparing a copolyesteramide according to the present invention includes the following steps: (1) Add aliphatic diacids and / or aromatic diacids to aliphatic diols or alicyclic diols in a reaction vessel at a molar ratio of carboxylic acid group to alcohol hydroxyl group (2.0-2.1):1, add an esterification catalyst, and carry out an esterification dehydration reaction at 150-190℃ for 2-3 hours; then remove excess diols and by-products by vacuum distillation to obtain ester-containing dicarboxylic acids; (2) Aliphatic dicarboxylic acids and / or aromatic dicarboxylic acids, the ester-containing dicarboxylic acid, aliphatic diamine, lactam, stabilizer, end-capping agent and other auxiliaries are added to a salt-forming reactor in proportion. Nitrogen gas is introduced into the reactor to replace the air, and the temperature is gradually raised to 220-250°C. The polymerization reaction is carried out at a pressure of 1.0-1.8 MPa for 3-5 hours. After depressurization, a vacuum is drawn until the melt index is 35-40 g / 10 min. The amount of the ester-containing dicarboxylic acid is 5%-15% of the molar amount of the dicarboxylic acid. The lactam is at least one of the cyclic lactams with 6-12 carbon atoms, and its amount accounts for 40%-50% of the total weight of the raw materials. (3) After the reaction is complete, nitrogen gas is introduced to release the vacuum, and the material is discharged while hot to obtain the copolyesteramide; In step (1), the aliphatic dicarboxylic acid is at least one of 1,4-succinic acid, 1,5-pentanoic acid, 1,6-adipic acid, 1,7-heptanoic acid, 1,8-octanoic acid, 1,9-azelaic acid, 1,10-sebacic acid, undecanoic acid (CAS No. 1852-04-6), and dodecanoic acid (CAS No. 693-23-2); the aromatic dicarboxylic acid is at least one of phthalic acid, isophthalic acid, and terephthalic acid; the aliphatic diol is at least one of 1,4-butanediol, 1,5-pentanediol, neopentanediol, and 1,6-hexanediol; and the alicyclic diol is at least one of 1,4-cyclohexanediol, 1,2-cyclohexanediol, and 2-methyl-1,3-cyclohexanediol.

[0009] In step (1), a dicarboxylic acid (aliphatic dicarboxylic acid and / or aromatic dicarboxylic acid) reacts with a diol (aliphatic diol or alicyclic diol). By controlling process parameters such as reaction temperature, reaction pressure, heating rate, and reaction time, and since the molar ratio of carboxylic acid group to alcohol hydroxyl group is (2.0~2.1):1, a ternary copolymer "ABA" structure containing an ester group dicarboxylic acid is obtained, the structure of which is as follows: HOOC-(CH2) m -COO-(CH2) n -OOC-(CH2) m -COOH Where n is an integer from 4 to 10, and m is an integer from 4 to 14.

[0010] Preferably, in step (1), the vacuum degree of the reduced pressure distillation is 1 to 100 Pa, and the distillation temperature exceeds the boiling point of the diol by 10 to 30°C, so as to remove unreacted raw materials, auxiliary raw materials and by-products with low boiling points from the crude product.

[0011] Preferably, in step (2), the molar ratio of the total carboxylic acid group of the aliphatic dicarboxylic acid and / or aromatic dicarboxylic acid and the total amino group of the ester-containing dicarboxylic acid to the total amino group of the aliphatic diamine is (1.00-1.05):1; the aliphatic diamine is one or more of 1,4-butanediamine, 1,5-pentanediamine, 2-methylpentanediamine, hexanediamine, decanediamine, and dodecanediamine.

[0012] The stabilizer is one or more of light stabilizers, heat stabilizers, hindered phenolic antioxidants, and pentaerythritol ester antioxidants, and the amount of the stabilizer is 0.05% to 1% of the total weight of the raw materials; the end-capping agent is one or more of stearic acid, adipic acid, and glacial acetic acid, and its addition amount is 0.2% to 0.5% of the total weight of the raw materials; the other additives include one or more of reinforcing agents, lubricants, plasticizers, nucleating agents, antistatic agents, and matting agents, and their addition amount is 0.5% to 1.5% of the total weight of the raw materials.

[0013] Compared with the prior art, the present invention has the following advantages: This invention first synthesizes an ester-containing dicarboxylic acid by embedding ester groups into the molecular chain of a dicarboxylic acid using a prepolymerization method. This prepolymer is then used as a reactant monomer to react with the remaining monomers. Residual diols and oligomers are removed by short-path distillation to purify the ester-containing dicarboxylic acid. Finally, it is compounded with the dicarboxylic acid and then polymerized with a diamine in a predetermined ratio to prepare a copolyesteramide. This method allows for precise control of the molecular weight and molecular weight distribution of the copolyamide, ensuring a uniform molecular chain structure and maximizing the synergistic optimization of the properties of polyester and polyamide. It avoids the problems of high dispersion coefficient, low molecular weight, and uneven molecular weight distribution caused by the different reactivity of esterification and amidation reactions. Furthermore, this invention lowers the reaction temperature, preventing yellowing of the product caused by the high reactivity of amino groups during the copolymerization of polyamide and polyester raw materials. The copolyesteramide obtained by this invention exhibits good alcohol solubility, effectively improving the spinnability of the product, and can be widely used in textiles, clothing linings, and other fields. Detailed Implementation

[0014] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0015] Example 1 A method for preparing copolyesteramide includes the following steps: (1) Take 427.9g of adipic acid (2.928mol) and 173g of 1,6-hexanediol (1.464mol) in a reaction vessel, add 0.2g of tetrabutyl titanate catalyst, replace with nitrogen and slowly raise the temperature to 160℃ for esterification and dehydration reaction. After the dehydration is completed after 2h of reaction, crude dicarboxylic acid containing ester group is obtained. Short-path vacuum distillation is carried out under the conditions of temperature 175℃ and vacuum degree 60Pa to remove residual water, diol and low boiling point by-products in the crude product to obtain dicarboxylic acid A containing ester group with molecular weight 484 and acid value 240mgKOH / g.

[0016] (2) According to the design ratio, 215g caprolactam, 32g adipic acid (0.219mol), 53g ester-containing dicarboxylic acid A (0.110mol), 175g dodecanoic acid (0.761mol), 126g hexamethylenediamine (1.084mol), 3g stearic acid, 0.6g antioxidant 1010, and 3g lubricant polyethylene wax were added to the reactor. After nitrogen purging, the temperature was slowly raised to 100℃. After the materials were completely melted, the stirring was started, and the temperature was raised to 250℃. The pressure was maintained at 1.0MPa for 2 hours. The pressure was slowly released to atmospheric pressure, and the dehydration reaction proceeded in the forward direction. Then, a vacuum was drawn to promote the polycondensation reaction until the melt index was within 35-40g / 10min. (3) After the reaction is complete, nitrogen gas is introduced to release the vacuum, and the material is discharged while hot to obtain copolyesteramide.

[0017] Example 2 A method for preparing copolyesteramide includes the following steps: (1) Take 434g of azelaic acid (2.305mol) and 166g of 1,4-cyclohexanediethanol (1.153mol) in a reaction vessel, add 0.2g of tetrabutyl titanate catalyst, replace with nitrogen and slowly raise the temperature to 150℃ for esterification and dehydration reaction. After the dehydration is completed after 2h of reaction, crude dicarboxylic acid containing ester group is obtained. Short-path vacuum distillation is carried out at 160℃ and 100Pa to remove residual water, diol and low-boiling by-products in the crude product to obtain dicarboxylic acid B containing ester group with molecular weight 374 and acid value 305mgKOH / g.

[0018] (2) According to the design ratio, 219g caprolactam, 32g adipic acid (0.219mol), 41g ester-containing dicarboxylic acid B (0.110mol), 178g dodecanoic acid (0.774mol), 128g hexamethylenediamine (1.103mol), 3g stearic acid, 0.6g antioxidant 1010, and 3g lubricant polyethylene wax were added to the reactor. After nitrogen purging, the temperature was slowly raised to 100℃. After the materials were completely melted, the stirring was started, and the temperature was raised to 240℃. The pressure was maintained at 1.3MPa for 2 hours. The pressure was slowly released to atmospheric pressure, and the dehydration reaction proceeded in the forward direction. Then, a vacuum was drawn to promote the polycondensation reaction until the melt index was within 35-40g / 10min. (3) After the reaction is complete, nitrogen gas is introduced to release the vacuum, and the material is discharged while hot to obtain copolyesteramide.

[0019] Comparative Example 1 (Copolyamide) According to the design ratio, 226g caprolactam, 33g adipic acid (0.226mol), 23g sebacic acid (0.114mol), 184g dodecanoic acid (0.8mol), 133g hexamethylenediamine (1.144mol), 3g stearic acid, 0.6g antioxidant 1010, and 3g lubricant polyethylene wax were added to the reactor. After nitrogen purging, the temperature was slowly raised to 100℃. After the materials were completely melted, stirring was started, and the temperature was further raised to 250℃. The pressure was maintained at 10 bar for 2 hours. After slowly depressurizing, a vacuum was drawn until the qualified index was reached. After the reaction was completed, nitrogen was introduced to release the vacuum, and the material was discharged while hot to obtain copolyesteramide.

[0020] Test Experiment Example The copolyesteramides prepared in Examples 1-2 and Comparative Example 1 are listed in Table 1, and then tested.

[0021] Table 1. Physical properties of the copolyesteramides in Examples 1-2 and Comparative Example 1 As can be seen from Table 1, the copolyamide polymerized from ester-containing dicarboxylic acids in this invention has a lower melting point and lower water washing failure rate, which greatly improves the water resistance of the copolyamide.

[0022] Figure 1 The infrared spectrum of the ester-containing dicarboxylic acid of Example 1 of the present invention is shown below. Figure 1 As can be seen from this, ester-containing dicarboxylic acids retain 1687 cm⁻¹ -1 In addition to the characteristic peak of the carboxyl group, at 1722 cm⁻¹ -1 The characteristic peak for ester group formation corresponds to 3300 cm⁻¹. -1 The disappearance of the characteristic peaks proves that the synthesized product is indeed a dicarboxylic acid containing an ester group, and that there is basically no residual diol after short-path vacuum distillation.

[0023] The greatest advantage of this invention lies in the fact that it first synthesizes a dicarboxylic acid containing an ester group and then purifies it by short-path distillation, which to a certain extent clarifies the ratio of ester bonds to amide bonds and can better control the molecular weight and molecular weight distribution. Secondly, it introduces a copolyester amide polymerized with ester groups into the copolyamide. The amide bonds and ester bonds work together to reduce the water absorption of the copolyamide and improve its water resistance, and optimize the heat resistance of the copolyester, so that the two can exert a better synergistic effect.

Claims

1. A method for preparing copolyesteramide, characterized in that, Includes the following steps: (1) Add aliphatic diacids and / or aromatic diacids to aliphatic diols or alicyclic diols in a reaction vessel at a molar ratio of carboxylic acid group to alcohol hydroxyl group (2.0-2.1):1, add an esterification catalyst, and carry out an esterification dehydration reaction at 150-190℃ for 2-3 hours; then remove excess diols and by-products by vacuum distillation to obtain ester-containing dicarboxylic acids; (2) Add aliphatic diacids and / or aromatic diacids, the ester-containing dicarboxylic acids, aliphatic diamines, lactams, stabilizers, end-capping agents and other auxiliaries into a salt-forming reactor in proportion, purge the reactor with nitrogen to replace the air, and then gradually raise the temperature to 220-250°C and polymerize at a pressure of 1.0-1.8 MPa for 3-5 hours; after depressurization, evacuate to a melt index of 35-40 g / 10 min; (3) After the reaction is complete, nitrogen gas is introduced to release the vacuum, and the material is discharged while hot to obtain the copolyesteramide; The amount of the ester-containing dicarboxylic acid is 5% to 15% of the molar amount of the dicarboxylic acid; the lactam is at least one of the cyclic lactams with 6 to 12 carbon atoms, and its amount is 40% to 50% of the total weight of the raw materials.

2. The method for preparing the copolyesteramide according to claim 1, characterized in that, In step (1), the aliphatic dicarboxylic acid is at least one of 1,4-succinic acid, 1,5-pentanoic acid, 1,6-adipic acid, 1,7-heptanoic acid, 1,8-octanoic acid, 1,9-azelaic acid, 1,10-sebacic acid, undecanoic acid, and dodecanoic acid; the aromatic dicarboxylic acid is at least one of phthalic acid, isophthalic acid, and terephthalic acid; the aliphatic diol is at least one of 1,4-butanediol, 1,5-pentanediol, neopentanediol, and 1,6-hexanediol; and the alicyclic diol is at least one of 1,4-cyclohexanediol, 1,2-cyclohexanediol, and 2-methyl-1,3-cyclohexanediol.

3. The method for preparing the copolyesteramide according to claim 1, characterized in that, The ester-containing dicarboxylic acid is a ternary copolymer with an "ABA" structure containing an ester group, and its structure is as follows: HOOC-(CH2) m -COO-(CH2) n -OOC-(CH2) m -COOH Where n is an integer from 4 to 10, and m is an integer from 4 to 14.

4. The method for preparing the copolyesteramide according to claim 1, characterized in that, In step (1), the vacuum degree of the reduced pressure distillation is 1 to 100 Pa, and the distillation temperature exceeds the boiling point of the diol by 10 to 30°C.

5. The method for preparing the copolyesteramide according to claim 1, characterized in that, In step (2), the molar ratio of the total carboxylic acid group of the aliphatic dicarboxylic acid and / or aromatic dicarboxylic acid and the total amino group of the ester-containing dicarboxylic acid to the total amino group of the aliphatic diamine is (1.00~1.05):

1.

6. The method for preparing the copolyesteramide according to claim 5, characterized in that, The aliphatic diamine is one or more of 1,4-butanediamine, 1,5-pentanediamine, 2-methylpentanediamine, hexanediamine, decanediamine, and dodecanediamine.

7. The method for preparing the copolyesteramide according to claim 1, characterized in that, The stabilizer is one or more of light stabilizers, heat stabilizers, hindered phenolic antioxidants, and pentaerythritol ester antioxidants, and the amount of the stabilizer is 0.05% to 1% of the total weight of the raw materials.

8. The method for preparing the copolyesteramide according to claim 1, characterized in that, The capping agent is one or more of stearic acid, adipic acid, and glacial acetic acid, and its addition amount is 0.2% to 0.5% of the total weight of the raw materials.

9. The method for preparing the copolyesteramide according to claim 1, characterized in that, The other additives include one or more of the following: reinforcing agents, lubricants, plasticizers, nucleating agents, antistatic agents, and matting agents, and their addition amount is 0.5% to 1.5% of the total weight of the raw materials.

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