Efficient capacity-increasing chain extender applied to polyester polycondensate and preparation method of efficient capacity-increasing chain extender

Abstract

The invention belongs to the technical field of polyester polycondensate preparation, and particularly relates to an efficient capacity-increasing chain extender applied to polyester polycondensate and a preparation method thereof.The preparation method includes the steps that S1, styrene monomers, acrylic acid monomers and epoxy acrylic acid monomers are added into a reaction flask and stirred for 20 min at the room temperature, and a reaction solution A is obtained; s2, adding an organic solvent, a monomaleimide monomer, a bismaleimide monomer, an initiator and a molecular weight regulator into a reaction bottle, and stirring at room temperature for 30 minutes to obtain a reaction solution B; and S3, adding the reaction solution A into a reaction bottle, controlling the reaction temperature at 55-95 DEG C under the protection of nitrogen, dropwise adding the solution B into the reaction solution A within 1-3 hours, continuing to react for 4-6 hours after the solution B is completely added, and stopping the reaction. S4, the reaction liquid is subjected to negative pressure desolvation, and the capacity-increasing chain extender is obtained and has the effects of preventing gelling and rapidly improving the strength of polyester melt.

Description

Technical Field

[0001] The invention belongs to the technical field of polyester condensation polymer preparation, and particularly relates to a high-efficiency volume-increasing and chain-extending agent applied to polyester condensation polymer and a preparation method thereof. Background Art

[0002] Polyester condensation polymers such as polyethylene terephthalate (PET), polylactic acid (PLA), polycarbonate (PC), and polybutylene terephthalate (PBT) are widely used in sports equipment, packaging, and other fields due to their excellent solvent resistance, high elastic modulus, impact resistance, and superior mechanical properties. During the manufacturing process, these materials undergo hydrolysis and thermal cracking, which causes the molecular chains of the condensation polymer to break down, forming small molecules such as carboxyl and hydroxyl groups, resulting in varying degrees of decrease in molecular weight and melt strength. These polyester materials, in particular, generate a large amount of waste annually, causing significant environmental pollution. As these condensation polymers have the highest recycling value, efficient recycling is particularly important. Research on improving the strength, chain extension, and capacity enhancement of both virgin and recycled polyester materials has garnered significant attention in this field. Chain extenders are currently the most effective materials for improving the properties of polyester polycondensates. By reacting their reactive functional groups with the carboxyl or hydroxyl groups of the polycondensate, they increase molecular weight, crosslink density, intrinsic viscosity, and melt strength, ultimately improving the processability and hydrolysis resistance of the polyester polycondensate. Depending on the type of reactive functional group, chain extenders are primarily categorized as epoxies, anhydrides, polyisocyanates, and oxazolines. Anhydride-type chain extenders can cause acidic corrosion to the screw during use, and polyisocyanates can leave residual isocyanates during processing, making them unsuitable for use in food packaging materials. Oxazoline-type chain extenders suffer from poor water resistance and are prone to localized gelation and decomposition during extrusion. Epoxy-type chain extenders, however, offer advantages such as mild chain extension conditions and a low gel point, and have been extensively studied in recent years.

[0003] Epoxy-based compatibilizers and chain extenders are usually materials formed by random copolymerization of propylene esters, epoxy propylene ethers, and epoxy propylene ester copolymers with alkyl chains of different lengths. However, the reactivity rates of these types of propylene ester (ether) monomers vary greatly. During the copolymerization of the monomers, it is very easy to form self-polymers and blocks. The stability of the resulting compatibilizer and chain extender is difficult to control, and it is impossible to obtain uniformly dispersed epoxy groups. The effective component is low, and the utilization rate of epoxy in the structure is low. Only 20% of the epoxy can be effectively utilized, and the compatibilizer and chain extender effect is not ideal. Even if the amount of compatibilizer and chain extender is increased, the improvement of the properties of polyester is not very obvious. If the addition amount is too large, greater than 3%, it is easy to produce material accumulation at the head of the screw during the polyester processing, and even cause the screw to be blocked. Summary of the Invention

[0004] The present invention aims to provide a high-efficiency volume-increasing and chain-extending agent for polyester polycondensates and a preparation method thereof. By introducing monomaleimide monomers and bismaleimide monomers with large steric hindrance, the present invention can hinder the aggregation of the components, effectively prevent the self-polymerization of acrylate monomers, prevent gelation, and quickly improve the melt strength of polyester.

[0005] The above technical objectives of the present invention are achieved through the following technical solutions: A high-efficiency volume-increasing and chain-extending agent for polyester polycondensation, comprising the following components and their mass fractions: 35-70 parts of styrene monomer 1-2.8 parts of monomaleimide monomer 0.3-1.2 parts of bismaleimide monomer 10-45 parts of acrylic monomer 15-25 parts of epoxy acrylic monomer 0.5-5 parts initiator 3-15 parts of molecular weight regulator 40-120 parts of organic solvent.

[0006] The structural formula of the chain extender is:

[0007]

[0008] The value range of m, n, p, q, r, s, t, u, and v is 1-80.

[0009] By adopting the above technical solution, the present invention introduces a monomaleimide monomer and a bismaleimide monomer with large steric hindrance, wherein the monomaleimide monomer with large steric hindrance can adjust the arrangement of each acrylate, hinder the aggregation between the components, effectively prevent the self-polymerization of the acrylate monomer, and effectively integrate the epoxy acrylic monomer into the acrylate main chain structure. The bismaleimide monomer reduces the aggregation density of the epoxy group monomer component, thereby preventing gelation. At the same time, the large epoxy monomer can quickly improve the melt strength of the polyester.

[0010] The present invention is further configured as follows: the acrylic monomer is preferably one or more combinations of acrylic acid, methacrylic acid, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, pentyl methacrylate, hexyl methacrylate, and hydroxyethyl methacrylate.

[0011] By adopting the above technical solution, styrene monomers and acrylic monomers are used to adjust the soft and hard segment contents of the compatibilizer and chain extender, thereby giving the material processing properties during processing with polyester materials.

[0012] The present invention is further configured as follows: the epoxy acrylic monomer is preferably a combination of one or more of glycidyl acrylate, glycidyl methacrylate and glycidyl diacrylate.

[0013] By adopting the above technical solution, the epoxy acrylic monomer in the reaction composition is used to provide reactive epoxy structural groups for chemically reacting with functional groups such as hydroxyl and carboxyl groups in the polyester condensation polymer to improve the melt strength.

[0014] The present invention is further configured as follows: the initiator is preferably dibenzoyl peroxide, 1,4-bis(tert-butylperoxydiisopropyl)benzene, 1,3-bis(tert-butylperoxydiisopropyl)benzene, 2,5-dimethyl-2,5-(di-tert-butylperoxy)hexane, 2,5-dimethyl-2,5-(di-tert-butylperoxy)-3-hexyne, ethyl-3,3-(di-tert-butylperoxy)butyrate and ethyl-3,3-di(tert-amylperoxy)butyrate; one or more of azobisisobutyronitrile, di-tert-butyl peroxide and azoisoheptylnitrile.

[0015] The present invention is further configured as follows: the styrene monomer comprises one or more combinations of styrene, methylstyrene, ethylstyrene, and chlorostyrene.

[0016] The present invention is further configured as follows: the organic solvent comprises one or more combinations of toluene, xylene, chloroform, dichloromethane and carbon tetrachloride.

[0017] The present invention is further configured as follows: the monomaleimide includes a combination of N-phenylmaleimide, N-cyclohexylmaleimide, N-benzylmaleimide, N-(1-pyrene)-maleimide, N-ethylmaleimide, N-(2-hydroxyethyl)maleimide and N-tert-butylmaleimide.

[0018] By adopting the above technical solution, the monomaleimide uses its large steric hindrance structure to effectively isolate the various acrylates, thereby reducing the risk of self-polymerization of the various acrylate monomers.

[0019] The present invention is further configured as follows: the bismaleimide comprises a combination of N, N-m-phenylene bismaleimide, N, N-tetramethylene bismaleimide, 4,4'-diphenylmethane bismaleimide and disulfide-bismaleimidoethane.

[0020] By adopting the above technical solution, bismaleimide utilizes its effective rigid structure and greater steric hindrance to form a "double-chain" structure with epoxy groups and each monomer, which is more conducive to improving the melt strength of polyester.

[0021] The present invention is further configured as follows: the molecular weight regulator is one or more combinations of ethanethiol, butyl mercaptan, hexyl mercaptan and dodecyl mercaptan, phenyl mercaptan, benzyl mercaptan, thioglycolic acid, 3-mercaptopropionic acid and thiosalicylic acid, 2-mercaptoethanol and 3-mercapto-1,2-propanediol, and pentaerythritol tetrakis (3-mercapto) propionate.

[0022] The present invention is further provided with: a method for preparing a high-efficiency volume-increasing and chain-extending agent for polyester polycondensation, S1: Add styrene monomer, acrylic monomer, and epoxy acrylic monomer into a reaction flask and stir at room temperature for 20 minutes to obtain reaction solution A; S2: Add an organic solvent, monomaleimide monomer, bismaleimide monomer, initiator, and molecular weight regulator to a reaction flask and stir at room temperature for 30 minutes to obtain reaction solution B; S3: Add reaction solution A to the reaction flask. Under nitrogen protection, control the reaction temperature at 55-95°C. Add solution B dropwise to reaction solution A. Add the solution within 1-3 hours. After all the solution is added, continue the reaction for 4-6 hours and then stop the reaction.

[0023] S4: Desolventize the reaction solution under negative pressure to obtain a volume-increasing and chain-extending agent.

[0024] The preparation steps of the high-efficiency volume-increasing chain extender are as follows:

[0025]

[0026] The beneficial effects of the present invention are: 1. The present invention introduces a monomaleimide monomer and a bismaleimide monomer with large steric hindrance. The monomaleimide monomer with large steric hindrance can adjust the arrangement of each acrylate, hinder the aggregation between the components, effectively prevent the self-polymerization of the acrylate monomer, and effectively integrate the epoxy acrylic monomer into the acrylate main chain structure. The bismaleimide monomer reduces the aggregation density of the epoxy group monomer component, thereby preventing gelation. However, the large epoxy monomer can also quickly improve the melt strength of the polyester.

[0027] 2. The introduction of monomaleimide with large steric hindrance effectively reduces the excessive epoxy concentration during random polymerization, effectively isolates the epoxy components, and avoids the self-polymerization of epoxy monomers. The added bismaleimide effectively separates the epoxy components, greatly improving the reaction efficiency of epoxy groups in condensation polymers. 3. The present invention reduces the amount of compatibilizer and chain extender in polyester condensation polymer to 0.2%, which is much lower than the amount of more than 0.5% of traditional epoxy compatibilizer and chain extender. The melt index of PC and PA66 can be reduced by more than 40%, and the melt index of PET and PBT is reduced by more than 30%. The tensile strength of PBT exceeds 53%, and the tensile strength of PC, PET and PA66 also exceeds 17%. The unnotched impact strength of PA66 is increased by more than 45%, and the unnotched impact strength of PBT, PET and PC is also greatly improved. Compared with the product without monomaleimide and bismaleimide monomers, the overall melt strength is greatly improved. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments are described clearly and completely below. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are also within the scope of protection of the present invention. Example 1

[0029] Step 1: Add 35 g of styrene, 10 g of acrylic acid, and 15 g of glycidyl acrylate into a reaction flask and stir at room temperature for 20 min to obtain reaction solution A; Step 2: 40 g of dichloromethane, 1 g of N-phenylmaleimide, 0.3 g of N,N-m-phenylenebismaleimide, 0.5 g of dibenzoyl peroxide, and 3 g of ethanethiol were added to a reaction flask and stirred at room temperature for 30 min to obtain reaction solution B; Step 3: Add reaction solution A to the reaction flask. Under nitrogen protection, control the reaction temperature at 55°C. Add solution B dropwise to reaction solution A. Add the solution within 1 hour. After all the solution is added, continue the reaction for 6 hours and then stop the reaction.

[0030] The fourth step is to desolventize the reaction solution under negative pressure to obtain a volume-increasing and chain-extending agent.

[0031] Appearance: white to light yellow crystals, yield: 95.8%, purity: 99.5%, Tg: 120°C. Example 2

[0032] Step 1: Add 70 g of methylstyrene, 45 g of methyl methacrylate, and 25 g of glycidyl methacrylate into a reaction flask and stir at room temperature for 20 min to obtain reaction solution A; Step 2: 120 g of xylene, 2.8 g of N-cyclohexylmaleimide, 1.2 g of N,N-tetramethylenebismaleimide, 5 g of 1,3-bis(tert-butylperoxydiisopropyl)benzene, and 15 g of hexanethiol were added to a reaction flask and stirred at room temperature for 30 min to obtain reaction solution B; Step 3: Add reaction solution A to the reaction flask. Under nitrogen protection, control the reaction temperature at 95°C. Add solution B dropwise to reaction solution A. Add the solution within 3 hours. After all the solution is added, continue the reaction for 4 hours and then stop the reaction.

[0033] The fourth step is to desolventize the reaction solution under negative pressure to obtain a volume-increasing and chain-extending agent.

[0034] Appearance: white to light yellow crystals, yield: 97.2%, purity: 99.8%, Tg: 98.2°C. Example 3

[0035] Step 1: Add 45 g of ethylstyrene, 20 g of propyl methacrylate, and 21 g of glycidyl diacrylate into a reaction flask and stir at room temperature for 20 min to obtain reaction solution A; Step 2: 80 g of toluene, 2 g of N-benzylmaleimide, 0.5 g of 4,4'-diphenylmethanebismaleimide, 3 g of 2,5-dimethyl-2,5-(di-tert-butylperoxy)-3-hexyne, and 8 g of benzylmercaptan were added to a reaction flask and stirred at room temperature for 30 min to obtain reaction solution B. Step 3: Add reaction solution A to the reaction flask. Under nitrogen protection, control the reaction temperature at 65°C. Add solution B dropwise to reaction solution A. Add the solution within 2 hours. After all the solution is added, continue the reaction for 5 hours and then stop the reaction.

[0036] The fourth step is to desolventize the reaction solution under negative pressure to obtain a volume-increasing and chain-extending agent.

[0037] Appearance: white to light yellow crystals, yield: 94.1%, purity: 99.3%, Tg: 112°C. Example 4

[0038] Step 1: Add 55 g of chlorostyrene, 35 g of amyl methacrylate, and 18 g of glycidyl methacrylate into a reaction flask and stir at room temperature for 20 min to obtain reaction solution A; Step 2: 105 g of chloroform, 2.5 g of N-(1-pyrene)-maleimide, 0.7 g of disulfide-bismaleimidoethane, 4 g of di-tert-butyl peroxide, and 12 g of 3-mercapto-1,2-propylene glycol were added to a reaction flask and stirred at room temperature for 30 min to obtain reaction solution B; Step 3: Add reaction solution A to the reaction flask. Under nitrogen protection, control the reaction temperature at 80°C. Add solution B dropwise to reaction solution A. Add the solution within 1.5 hours. After all the solution is added, continue the reaction for 5.5 hours and then stop the reaction.

[0039] The fourth step is to desolventize the reaction solution under negative pressure to obtain a volume-increasing and chain-extending agent.

[0040] Appearance: white to light yellow crystals, yield: 89.5%, purity: 99.2%, Tg: 105°C. Example 5

[0041] Step 1: Add 60 g of methylstyrene, 14 g of hexyl methacrylate, and 20.5 g of glycidyl acrylate into a reaction flask and stir at room temperature for 20 min to obtain reaction solution A; Step 2: Add 68 g of carbon tetrachloride, 1.5 g of N-ethylmaleimide, 1.0 g of N,N-tetramethylenebismaleimide, 3.5 g of azobisisobutyronitrile, and 11.5 g of pentaerythritol tetrakis(3-mercapto)propionate into a reaction flask and stir at room temperature for 30 min to obtain reaction solution B; Step 3: Add reaction solution A to the reaction flask. Under nitrogen protection, control the reaction temperature at 70°C. Add solution B dropwise to reaction solution A. Add the solution within 1 hour. After all the solution is added, continue the reaction for 4.5 hours and then stop the reaction.

[0042] The fourth step is to desolventize the reaction solution under negative pressure to obtain a volume-increasing and chain-extending agent.

[0043] Appearance: white to light yellow crystals, yield: 90.4%, purity: 99.3%, Tg: 107°C. Example 6

[0044] Step 1: Add 52 g of methylstyrene, 30 g of hydroxyethyl methacrylate, and 22.5 g of glycidyl diacrylate into a reaction flask and stir at room temperature for 20 min to obtain reaction solution A; Step 2: 98 g of dichloromethane, 2.2 g of N-tert-butylmaleimide, 0.6 g of 4,4'-diphenylmethanebismaleimide, 3 g of 2,5-dimethyl-2,5-(di-tert-butylperoxy)hexane, and 10 g of thiosalicylic acid were added to a reaction flask and stirred at room temperature for 30 min to obtain reaction solution B. Step 3: Add reaction solution A to the reaction flask. Under nitrogen protection, control the reaction temperature at 75°C. Add solution B dropwise to reaction solution A. Add the solution within 2 hours. After all the solution is added, continue the reaction for 5.5 hours and then stop the reaction.

[0045] The fourth step is to desolventize the reaction solution under negative pressure to obtain a volume-increasing and chain-extending agent.

[0046] Appearance: white to light yellow crystals, yield: 90.2%, purity: 99.7%, Tg: 115°C.

[0047] Comparative Example 1 The N-phenylmaleimide and N,N-m-phenylenebismaleimide in Example 1 were completely removed, and the rest were prepared according to the method of Example 1.

[0048] Comparative Example 2 The N,N-m-phenylene bismaleimide in Example 1 was removed, and the rest was prepared according to the method of Example 1.

[0049] Comparative Example 3 Except for removing N-phenylmaleimide in Example 1, the rest of the preparation was carried out in accordance with the method of the example.

[0050] Compatibility and chain extension of different polyester polycondensates (polyethylene terephthalate (PET), polyhexamethylene adipamide (PA66), polycarbonate (PC), polybutylene terephthalate (PBT)) Steps for increasing PC capacity and extending the chain: After drying the PC at 115°C for 3 hours, a 0.2% mass fraction of the compatibilizer and chain extender prepared in Examples 1-6 and Comparative Examples 1-3 was added to the PC at room temperature and mixed uniformly in a high-speed mixer. The mixture was then extruded, cooled, and granulated using a twin-screw extruder to obtain compatibilized and chain-extended particles. The processing temperatures for each stage were: 100, 250, 260, 250, 245, 240, 230, 230, and 240°C (die head temperature), and the relative vacuum was -0.05 MPa.

[0051] The processing of PBT, PET and PA66 refers to the PC capacity expansion and chain extension preparation process.

[0052] Table 1 shows the performance test results of the compatibilizers and chain extenders prepared in Examples 1-6 and Comparative Examples 1-3 on different polyester polycondensates.

[0053] Table 2 shows the performance results of different polyester polycondensates before compatibilization and chain extension.

[0054] Table 1

[0055] Table 2 Properties of polyester polycondensates before compatibilization and chain extension

[0056] The present invention reduces the amount of the compatibilizer and chain extender in the polyester condensation polymer to 0.2%, which is much lower than the amount of more than 0.5% of the traditional epoxy compatibilizer and chain extender; the melt index of PC and PA66 can be reduced by more than 40%, and the melt index of PET and PBT is reduced by more than 30%; the tensile strength of PBT exceeds 53%, and the tensile strength of PC, PET and PA66 also exceeds 17%; the unnotched impact strength of PA66 is increased by more than 45%, and the unnotched impact strength of PBT, PET and PC is also greatly improved. Compared with the product without monomaleimide and bismaleimide monomers, the overall melt strength is greatly improved.

Claims

1. A high-efficiency volume-increasing and chain-extending agent for polyester polycondensation, characterized in that: Includes the following components and their mass fractions: Styrene monomer 35-70 Monomaleimide monomer 1-2.8 Bismaleimide monomer 0.3-1.2 Acrylic monomer 10-45 Epoxy acrylic monomer 15-25 Initiator 0.5-5 Molecular weight regulator 3-15 Organic solvent 40-120.

2. The high-efficiency volume-increasing and chain-extending agent for polyester polycondensation according to claim 1, characterized in that: The acrylic monomer is preferably one or more of acrylic acid, methacrylic acid, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, pentyl methacrylate, hexyl methacrylate, and hydroxyethyl methacrylate.

3. The high-efficiency volume-increasing and chain-extending agent for polyester polycondensation according to claim 1, characterized in that: The epoxy acrylic monomer is preferably one or more of glycidyl acrylate, glycidyl methacrylate and glycidyl diacrylate.

4. The high-efficiency volume-increasing and chain-extending agent for polyester polycondensation according to claim 1, characterized in that: The initiator is preferably dibenzoyl peroxide, 1,4-bis(tert-butylperoxydiisopropyl)benzene, 1,3-bis(tert-butylperoxydiisopropyl)benzene, 2,5-dimethyl-2,5-(di-tert-butylperoxy)hexane, 2,5-dimethyl-2,5-(di-tert-butylperoxy)-3-hexyne, ethyl-3,3-(di-tert-butylperoxy)butyrate and ethyl-3,3-di(tert-amylperoxy)butyrate; one or more of azobisisobutyronitrile, di-tert-butyl peroxide and azoisoheptylnitrile.

5. The high-efficiency volume-increasing and chain-extending agent for polyester polycondensation according to claim 1, characterized in that: The styrene monomers include one or more combinations of styrene, methyl styrene, ethyl styrene and chlorostyrene.

6. The high-efficiency volume-increasing and chain-extending agent for polyester polycondensation according to claim 1, characterized in that: The organic solvent includes one or more combinations of toluene, xylene, chloroform, dichloromethane and carbon tetrachloride.

7. The high-efficiency volume-increasing and chain-extending agent for polyester polycondensation according to claim 1, characterized in that: The monomaleimide includes a combination of N-phenylmaleimide, N-cyclohexylmaleimide, N-benzylmaleimide, N-(1-pyrene)-maleimide, N-ethylmaleimide, N-(2-hydroxyethyl)maleimide and N-tert-butylmaleimide.

8. The high-efficiency volume-increasing and chain-extending agent for polyester polycondensation according to claim 1, characterized in that: The bismaleimide comprises a combination of N, N-m-phenylene bismaleimide, N, N-tetramethylene bismaleimide, 4,4'-diphenylmethane bismaleimide and disulfide-bismaleimidoethane.

9. The high-efficiency volume-increasing and chain-extending agent for polyester polycondensation according to claim 1, characterized in that: The molecular weight regulator is one or more of ethanethiol, butyl mercaptan, hexyl mercaptan and dodecyl mercaptan, phenyl mercaptan, benzyl mercaptan, thioglycolic acid, 3-mercaptopropionic acid and thiosalicylic acid, 2-mercaptoethanol and 3-mercapto-1,2-propanediol, and pentaerythritol tetrakis (3-mercapto) propionate.

10. The method for preparing a high-efficiency volume-increasing and chain-extending agent for polyester polycondensation according to claim 1, characterized in that: S1: Add styrene monomer, acrylic monomer, and epoxy acrylic monomer into a reaction flask and stir at room temperature for 20 minutes to obtain reaction solution A; S2: Add an organic solvent, monomaleimide monomer, bismaleimide monomer, initiator, and molecular weight regulator to a reaction flask and stir at room temperature for 30 minutes to obtain reaction solution B; S3: Add reaction solution A to the reaction flask. Under nitrogen protection, control the reaction temperature at 55-95°C. Add solution B dropwise to reaction solution A within 1-3 hours. After all the addition is complete, continue the reaction for 4-6 hours and then stop the reaction. S4: Desolventize the reaction solution under negative pressure to obtain a volume-increasing and chain-extending agent.

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